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WO2022061761A1 - Image sensor and control method therefor, and imaging device carrying image sensor - Google Patents

Image sensor and control method therefor, and imaging device carrying image sensor Download PDF

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Publication number
WO2022061761A1
WO2022061761A1 PCT/CN2020/117891 CN2020117891W WO2022061761A1 WO 2022061761 A1 WO2022061761 A1 WO 2022061761A1 CN 2020117891 W CN2020117891 W CN 2020117891W WO 2022061761 A1 WO2022061761 A1 WO 2022061761A1
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WIPO (PCT)
Prior art keywords
pixel
floating diffusion
voltage
diffusion region
photosensitive element
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Application number
PCT/CN2020/117891
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French (fr)
Chinese (zh)
Inventor
徐泽
周雪梅
肖�琳
Original Assignee
深圳市大疆创新科技有限公司
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Application filed by 深圳市大疆创新科技有限公司 filed Critical 深圳市大疆创新科技有限公司
Priority to CN202080016807.8A priority Critical patent/CN113491108A/en
Priority to PCT/CN2020/117891 priority patent/WO2022061761A1/en
Publication of WO2022061761A1 publication Critical patent/WO2022061761A1/en

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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/70SSIS architectures; Circuits associated therewith
    • H04N25/702SSIS architectures characterised by non-identical, non-equidistant or non-planar pixel layout
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/70SSIS architectures; Circuits associated therewith
    • H04N25/76Addressed sensors, e.g. MOS or CMOS sensors
    • H04N25/77Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Definitions

  • the present application relates to the technical field of image sensors, and in particular, to an image sensor, a control method thereof, and an imaging device equipped with an image sensor.
  • Image sensors are widely used in consumer electronics, security monitoring, industrial automation, artificial intelligence, Internet of Things and other fields. They are used to collect and organize image data information and provide information sources for subsequent processing and applications.
  • the image sensor can be divided into a photosensitive circuit area and a peripheral reading circuit area according to its functional composition.
  • the function of the photosensitive circuit area is to convert the optical signal into an electrical signal through the photosensitive element and store it, and then hand it over to the subsequent peripheral readout circuit for conversion into a digital image signal.
  • the dynamic range (DR) is limited.
  • the present application provides an image sensor and a control method thereof, and an imaging device equipped with the image sensor, which can realize a wider dynamic range of the image sensor.
  • an embodiment of the present application provides a control method for an image sensor, the image sensor includes a plurality of pixels, and the pixels include a photosensitive element, a transfer tube, a floating diffusion area, a reset tube, and a readout circuit, so the transfer tube is connected between the photosensitive element and the floating diffusion region, and the floating diffusion region is connected with the reset tube and the readout circuit;
  • the method includes:
  • the transfer tube When the photosensitive element receives photons to generate photo-generated charges, controlling the transfer tube to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion region;
  • the imaging parameter of the pixel is determined according to the first reference voltage of the floating diffusion region and the first signal voltage.
  • an embodiment of the present application provides an image sensor, the image sensor includes a peripheral circuit and a plurality of pixels, and the pixels include a photosensitive element, a transfer tube, a floating diffusion area, a reset tube, and a readout circuit, so the transfer tube is connected between the photosensitive element and the floating diffusion region, and the floating diffusion region is connected with the reset tube and the readout circuit;
  • the peripheral circuit is used to perform the following steps:
  • the transfer tube When the photosensitive element receives photons to generate photo-generated charges, controlling the transfer tube to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion region;
  • the imaging parameter of the pixel is determined according to the first reference voltage of the floating diffusion region and the first signal voltage.
  • an embodiment of the present application provides an imaging device equipped with any of the above-mentioned image sensors.
  • the embodiments of the present application provide an image sensor and a control method thereof, and an imaging device equipped with the image sensor.
  • the transmission tube is controlled to be in a sub-threshold state to make the photo-generated charges exceeding the capacity of the photo-sensitive element.
  • the imaging parameters of the pixels are determined according to the first reference voltage and the first signal voltage of the floating diffusion area, so that the pixels have different sensitivities in bright and dark places, and a wider dynamic range of the image sensor can be achieved.
  • FIG. 1 is a schematic flowchart of a control method of an image sensor provided by an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of an image sensor in an embodiment
  • FIG. 3 is a schematic structural diagram of a pixel in an embodiment
  • FIG. 4 is a schematic structural diagram of a pixel array in one embodiment
  • 5 is a schematic diagram of the relationship between the output signal of the pixel and the light intensity
  • FIG. 6 is a schematic diagram of imaging of pixels under different illumination intensities in one embodiment
  • FIG. 7 is a timing diagram of an image sensor pixel during operation in an embodiment
  • FIG. 9 is a schematic diagram of imaging of pixels under different illumination intensities in another embodiment
  • FIG. 10 is a schematic diagram of determining a deviation correction value of a pixel
  • FIG. 11 is a schematic structural diagram of an imaging device provided by an embodiment of the present application.
  • FIG. 1 is a schematic flowchart of a control method of an image sensor provided by an embodiment of the present application.
  • the control method of the image sensor can be applied in the image sensor 200 and/or the control device of the image sensor, for example, in the complementary semiconductor image sensor (CIS) chip, or in the peripheral circuit 220 of the image sensor 200, using It is used to control the imaging of the image sensor 200 and other processes.
  • CIS complementary semiconductor image sensor
  • the image sensor 200 can be divided into a photosensitive circuit area 210 for photosensitive and a peripheral circuit 220 (also referred to as a control circuit) for controlling and processing signals according to functional composition, wherein
  • the photosensitive circuit area 210 may include multiple, such as tens of thousands to hundreds of millions of pixels 211 (pixels, also referred to as photosensitive units).
  • the so-called pixel array The peripheral circuit 220 is responsible for converting the signal induced by the pixel 211 into a digital signal and reading it out.
  • control circuit may be used to implement tasks such as exposure time control, automatic gain control, and the like.
  • tasks such as exposure time control, automatic gain control, and the like.
  • multiple timing control signals must be used.
  • it is also required to output some timing signals, such as synchronization signal, line start signal, field start signal, etc.
  • the row select logic unit gates the corresponding row pixels as needed.
  • the image signals in the row pixels are transmitted to the corresponding analog signal processing unit and the A/D converter through the signal bus of the respective column, and are converted into digital image signals for output.
  • the row selection logic unit can scan the pixel array progressively or interlaced.
  • the row selection logic unit is used in conjunction with the column selection logic unit to realize the window extraction function of the image.
  • the main function of the analog signal processing unit is to amplify the signal and improve the signal-to-noise ratio.
  • the pixel 211 includes a photosensitive element PD, a transfer transistor TX, a floating diffusion FD, a reset transistor RST, and a readout circuit.
  • the photosensitive element PD may be a photodiode.
  • the readout circuit may include a source follower transistor SF and a row strobe transistor SEL.
  • the structure of the pixel 211 shown in FIG. 3 is only an example, and the embodiment of the present application is not limited thereto.
  • the control method of the embodiment of the present application can be applied to the photosensitive element PD of the pixel 211 to be connected to float through a transmission tube TX.
  • the photosensitive element PD converts photons into electrons, and then the transmission tube TX transmits the photogenerated electrons to the floating diffusion area FD, and induces a voltage signal corresponding to the light intensity.
  • the peripheral circuit 220 is converted into a digital signal after certain processing, and then image information is formed.
  • the transmission transistor TX is connected between the photosensitive element PD and the floating diffusion area FD, and the floating diffusion area FD is connected to the reset transistor RST and the readout circuit.
  • the photosensitive element PD can generate photo-generated charges under the action of incident light, and when the transfer tube TX is turned on (ie, turned on), the photo-generated charges are transferred to the floating diffusion region FD, and the readout circuit can determine the floating diffusion.
  • the voltage change of the area FD under the action of the photo-generated charges can be converted into a digital signal representing image information through a subsequent analog-to-digital (AD) conversion circuit. Analog-to-digital conversion is performed, for example, by the peripheral circuit 220 .
  • AD analog-to-digital
  • the peripheral circuit 220 may be included, of course, the peripheral circuit 220 may not be included, for example, functions such as analog-to-digital conversion may be implemented by the additionally mounted peripheral circuit 220 .
  • FIG. 4 is a schematic circuit diagram of a 2 ⁇ 2 pixel array in the image sensor 200 .
  • the transmission tube TX control signal line is used to control the transmission tube TX. For example, when the potential of the transmission tube TX control signal line is at a high level, the transmission tube TX is turned on to connect the photosensitive element PD and the floating diffusion area FD; reset the power supply The line is connected to one end of the reset transistor RST, and the reset transistor RST control signal line is used to control the reset transistor RST. For example, when the potential of the reset transistor RST control signal line is high, the reset transistor RST is turned on, so that the floating diffusion area FD is connected.
  • the photo-generated charges in the floating diffusion area FD can be cleared, and the reset of the floating diffusion area FD can be realized.
  • the first high voltage of the reset power line can reset the floating diffusion FD and the photosensitive element PD.
  • the row strobe SEL control signal line is used to control the row strobe SEL.
  • the row strobe SEL When the potential of the row strobe SEL control signal line is high, the row strobe SEL is turned on, and the voltage of the floating diffusion area FD can be read by The output circuit reads, when the potential of the control signal line of the row strobe SEL is a low level, the row strobe SEL is turned off.
  • the reset power line, the reset transistor RST control signal line, the transmission transistor TX control signal line, and the row strobe SEL control signal line are wires arranged in the row direction of the image sensor 200 .
  • the drain terminals of the source follower transistor SF are all connected to the power supply VDD, and the source follower transistor SF has a high input resistance and a low output resistance, which is equivalent to an open circuit for the previous stage circuit, and is equivalent to a constant voltage for the latter stage circuit. source, the output voltage is not affected by the impedance of the subsequent circuit.
  • the response of the general image sensor 200 to light is close to linear, and the photo-generated charges generated under the action of light are first stored in the capacitance of the photosensitive element PD.
  • the photo-generated charge stored in the photosensitive element PD reaches saturation and will no longer increase.
  • the PD capacitance of the photosensitive element is saturated, and the output signal is full scale, resulting in the loss of image details in the bright part, that is, the dynamic range is limited.
  • the inventors of the present application have improved the control method of the image sensor 200 to prevent the image sensor 200 from losing image details in bright areas during imaging.
  • control method of the image sensor according to the embodiment of the present application includes steps S110 to S150.
  • the subthreshold state of a transistor is an important working state of a transistor (eg, a MOSFET), and may be referred to as a subthreshold region of the transistor.
  • a transistor eg, a MOSFET
  • the transmission tube When the transmission tube is in the sub-threshold state, the voltage Vgs of the transmission tube grid is below the threshold voltage VT, and the transmission tube does not have a conductive channel, that is, the transmission tube is at Vgs ⁇ VT, and the surface potential ⁇ s is roughly equal to the Fermi potential ⁇ b ( That is, the surface is in the state of weak inversion), at this time, the transmission tube can pass a small current, which can be called subthreshold current.
  • the voltage for controlling the transmission tube to be in a sub-threshold state is greater than zero and less than the voltage for controlling the conduction of the transmission tube.
  • the voltage for controlling the conduction of the transmission tube is 2.5-5 volts
  • the voltage for controlling the transmission tube to be in a sub-threshold state is 0.5-2.5 volts.
  • it can be determined according to the process and performance parameters of the image sensor.
  • the photosensitive element when the pixel A and the pixel B in the image sensor are exposed, the photosensitive element receives photons to generate photo-generated charges.
  • the number of the generated photo-generated charges is different.
  • part of the photogenerated charge of pixel B exceeds the capacity of the photosensitive element of pixel B.
  • the transfer tube is in a sub-threshold state, the photo-generated charges exceeding the capacity of the photosensitive element of pixel B enter the floating diffusion region of pixel B through the transfer tube of pixel B.
  • the timing of the operation of the image sensor pixels is shown in FIG. 7 .
  • the level of the control signal line of the row strobe tube is a low level, and the readout circuit may not work.
  • the period S1 when the potential of the reset transistor control signal line is low, the reset transistor is turned off, the image sensor can be exposed, and the photosensitive element receives photons to generate photo-generated charges, so the period S1 includes the exposure phase.
  • the level of the transfer tube control signal line is set to the voltage Vm, and the voltage Vm is less than the threshold voltage VT, the transfer tube is in a sub-threshold state, as shown in FIG. The transfer tube enters the floating diffusion area of pixel B.
  • the reset transistor and the transfer transistor are controlled to be turned on to reset the photosensitive element and the transfer transistor. the floating diffusion region.
  • the electrical level of the reset tube control signal line is set to a high level, and the level of the transmission tube control signal line is set to a voltage Vh (which may be called a high level),
  • Vh is greater than the threshold voltage VT, so that the transfer tube is turned on to connect the photosensitive element and the floating diffusion area, and the reset tube is turned on so that the floating diffusion area is connected to the reset power line, as shown in Figure 6, the floating diffusion area can be reset and photosensitive element, emptying the floating diffusion and photo-generated charge in the photosensitive element.
  • the time period S1 therefore includes the reset phase.
  • the conduction of the reset tube and the conduction of the transmission tube may be controlled to reset the photosensitive element and the floating diffusion region.
  • the reset transistor when the photosensitive element receives photons to generate photo-generated charges, the reset transistor is controlled to be turned off.
  • the electrical position of the control signal line of the reset tube is set to a low level, and the reset tube is controlled to be turned off, so that the photosensitive element receives photons to generate photo-generated charges and store photo-generated charges.
  • the level of the transfer tube control signal line is set to the voltage Vm, so that the photo-generated charge exceeding the capacity of the photosensitive element enters the floating diffusion region.
  • the level of the transmission tube control signal line is set to a low level, and the transmission tube is controlled to be turned off (completely closed).
  • the photo-generated charges are accumulated in the photosensitive element.
  • the exposure time is short and the signal is less at the beginning.
  • the photo-generated charges accumulated in the photosensitive element increase rapidly with the exposure intensity, which is the first response stage.
  • the photosensitive element is close to saturation. Since the transfer tube is in a sub-threshold state, when the photosensitive element is close to saturation, a part of the photo-generated charge will pass through the bottom of the transfer tube and enter the floating diffusion area.
  • the photo-generated charge is The voltage of the floating diffusion area is reduced when the electrons are present. At this time, the response of the accumulated photo-generated charges of the photosensitive element to the exposure intensity becomes slower, and the second response stage is entered.
  • the capacity of the photosensitive element can affect the inflection point between the first response stage and the second response stage. For example, when the photogenerated charge accumulated in the photosensitive element is less than the capacity of the photosensitive element, the photogenerated charge accumulated in the photosensitive element increases rapidly with the exposure intensity; when the photogenerated charge accumulated in the photosensitive element reaches or exceeds the capacity of the photosensitive element, the photosensitive element accumulates The photogenerated charge responds slower with exposure intensity.
  • the electrical position of the reset transistor control signal line is set to a high level for a preset period of time, while the transmission transistor is kept off, so that the floating diffusion area is connected Resetting the power line, the first high voltage of the reset power line can clear the photo-generated charge in the floating diffusion area, and realize the reset of the floating diffusion area. Since the transfer tube is turned off, the charge in the photosensitive element can be retained.
  • the level of the transmission tube control signal line is set to a high level for a preset period of time, and the transmission tube is controlled to be turned on. For a predetermined period of time, as shown in FIG. 6 , the photo-generated charges in the photosensitive element are transferred to the floating diffusion region.
  • the photo-generated charges in the photosensitive element are transferred to the floating diffusion area, which will cause the voltage of the floating diffusion area to change.
  • the magnitude of the voltage change is positively related to the amount of photo-generated charges transferred to the floating diffusion area.
  • the amplitude determines the amount of photo-generated charge accumulated in the photosensitive element when the pixel is exposed, so that the light intensity corresponding to the pixel can be obtained.
  • the electrical position of the row strobe control signal line is set to a high level during the time period S2, so that the row strobe is turned on, so that the readout circuit can read the
  • the voltage of the floating diffusion region is the first signal voltage Vsig1. It can be understood that the gate transistor can be continuously turned on during the entire time period S2, or can be turned on when reading the voltage of the floating diffusion region.
  • Time period S2 may include a valid signal readout phase.
  • the voltage of the floating diffusion can be read at the source of the source follower transistor.
  • the transmission transistor when the readout circuit is controlled to read the first signal voltage of the floating diffusion region, the transmission transistor is controlled to be turned off. As shown in FIG. 7 , after the level of the transmission tube control signal line is set to a high level for a preset duration, it is set to a low level to turn off the transmission tube. After the transmission tube is turned off, the readout circuit can be controlled to read Take the first signal voltage Vsig1 of the floating diffusion area. The accuracy of the floating diffusion voltage reading can be improved.
  • the first signal voltage of pixel A may be represented as Vsig1_a
  • the first signal voltage of pixel B may be represented as Vsig1_b.
  • the photo-generated charge accumulated in the photosensitive element of pixel B is more than that of pixel A
  • the floating The photo-generated charges in the diffusion area are also more than those of the pixel A.
  • the photo-generated charges are electrons
  • the voltage drop of the pixel B is larger than that of the pixel A, for example, Vsig1_a is larger than Vsig1_b.
  • the first reference voltage includes the voltage when there is no photo-generated charge in the floating diffusion region, or includes the voltage of the floating diffusion region before the photo-generated charge in the photosensitive element is transferred to the floating diffusion region.
  • the first reference voltages of different pixels may be the same or different; the first reference voltages of the same pixel under different working conditions may be the same or different.
  • the readout circuit may be controlled to read the first value of the floating diffusion. reference voltage.
  • the readout is controlled before the transfer tube is controlled to be turned on in the time period S2 so that the photo-generated charges in the photosensitive element are transferred to the floating diffusion region.
  • the circuit reads the voltage of the floating diffusion as the first reference voltage Vref1.
  • the first reference voltage of pixel A may be represented as Vref1_a
  • the first reference voltage of pixel B may be represented as Vref1_b.
  • the transfer transistor when the readout circuit is controlled to read the first reference voltage of the floating diffusion region, the transfer transistor is controlled to be turned off to prevent the photo-generated charges in the photosensitive element from affecting the voltage of the floating diffusion region.
  • the reference voltage of the floating diffusion region may be stored in advance, for example, an empirical value or a reference voltage read during a certain imaging, or a reference voltage read at any time. All pixels in an image sensor can use the same reference voltage, or each can use different reference voltages.
  • deltaV1 is the signal voltage related to the illumination intensity of the corresponding pixel, and is the voltage difference caused by the incident light signal, which can be converted into a digital signal representing image information through a subsequent analog-to-digital (AD) conversion circuit. Analog-to-digital conversion is performed, for example, by peripheral circuits.
  • the image captured by the image sensor can be obtained according to the imaging parameters of each pixel in the pixel array.
  • the control method of the image sensor provided by the embodiment of the present application, by controlling the transfer tube to be in a sub-threshold state when the photosensitive element receives photons to generate photo-generated charges, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion area, and then reset the floating area the diffusion area, and control the conduction of the transfer tube to transfer the photo-generated charges in the photosensitive element to the floating diffusion area, and control the readout circuit to read the first signal voltage of the floating diffusion area, according to the first reference of the floating diffusion area
  • the voltage and the first signal voltage determine the imaging parameters of the pixels, so that the pixels have different sensitivities in bright and dark places, and a wider dynamic range of the image sensor can be realized.
  • the light intensity of the pixel in the bright place is stronger, but the photo-generated charge that exceeds the capacity of the photosensitive element will enter the floating diffusion area and be emptied, so the sensitivity of the pixel in the bright place is low, and the difference in the high light signal level can be preserved more.
  • the light intensity of the pixel in the dark place is weak, and the probability of the photo-generated charge exceeding the capacity of the photosensitive element is low, so the pixel in the dark place has a low sensitivity and a good signal-to-noise ratio. Pixels have different sensitivities to different light intensities, which can preserve details in dark areas and retain more color and/or brightness levels in highlights.
  • the inflection point between the first response stage and the second response stage of each pixel is not completely consistent, so there are differences in the response of different pixels to the light intensity, For example, it will affect the consistency of the entire image in the highlights, resulting in noise in the image captured by the image sensor.
  • the determining the imaging parameter of the pixel according to the first reference voltage of the floating diffusion region and the first signal voltage includes: according to a deviation correction value corresponding to the pixel, and the The pixel's first reference voltage and the pixel's first signal voltage determine an imaging parameter of the pixel.
  • the difference calibration mechanism of the inflection points between the first response stage and the second response stage of different pixels is realized, so that the inflection points of different pixels tend to be consistent, so that the whole The image has better consistency in highlights and lower fixed pattern noise.
  • the method further includes: determining a deviation correction value corresponding to the pixel.
  • the deviation correction value corresponding to each pixel may be stored in advance, such as an empirical value or a deviation correction value corresponding to each pixel determined during a certain imaging, or it may be determined at any time corresponding to a pixel Bias correction value. In other embodiments, the deviation correction value corresponding to each pixel may be determined during each imaging, with a higher accuracy.
  • the capacity of the photosensitive element can affect the inflection point between the first response stage and the second response stage.
  • the deviation correction value is used to indicate the deviation of the capacity of the photosensitive element in the pixel.
  • the transfer tube is in a sub-threshold state, photo-generated charges exceeding the capacity of the photosensitive elements of pixel C and pixel D enter the floating diffusion regions of pixel C and pixel D through the transfer tube.
  • the capacity of the photosensitive element of the pixel C is smaller than that of the pixel D, the pixel C has more photo-generated charges entering the floating diffusion area of the pixel C, and the pixel D has less photo-generated charges entering the floating diffusion area of the pixel D. .
  • each pixel resets the floating diffusion area, and transfers the photo-generated charges in the photosensitive element to the floating diffusion area.
  • Pixel C has less photo-generated charges transferred to the floating diffusion area of pixel C, and pixel D has more photo-generated charges.
  • a large amount of photo-generated charges are transferred to the floating diffusion area of pixel D.
  • the photo-generated charges are electrons, the voltage drop in the floating diffusion area of pixel C is smaller than that of pixel D.
  • the imaging parameters of the pixel C and the pixel D with the same illumination intensity can be made consistent.
  • the determining the imaging parameter of the pixel according to the deviation correction value corresponding to the pixel, the first reference voltage of the pixel and the first signal voltage of the pixel includes: according to the pixel The difference between the first reference voltage and the first signal voltage of the pixel, and the deviation correction value of the pixel determine the imaging parameter of the pixel.
  • the difference value of pixel C is represented as delta V1_c
  • the deviation correction value of pixel C is represented as Vv_c
  • the difference value of pixel D is represented as delta V1_d
  • the deviation correction value of pixel D is represented as Vv_d.
  • the difference between the first reference voltage of each pixel and the first signal voltage of the pixel may be added to the deviation correction value of each pixel to obtain the imaging parameter of the pixel. If the deviation correction value Vv_c of the pixel C with a small photosensitive element capacity is greater than the deviation correction value Vv_d of the pixel D with a large photosensitive element capacity, and delta V1_c is smaller than delta V1_d, the sum of delta V1_c and the larger deviation correction value Vv_c can be equal to delta The sum of V1_d and the larger deviation correction value Vv_d.
  • the deviation correction value of each pixel may be subtracted from the difference between the first reference voltage of each pixel and the first signal voltage of the pixel to obtain the imaging parameter of the pixel. If the deviation correction value Vv_c of the pixel C with a small photosensitive element capacity is smaller than the deviation correction value Vv_d of the pixel D with a large photosensitive element capacity, and delta V1_c is smaller than delta V1_d, the difference between delta V1_c and the small deviation correction value Vv_c can be equal to delta The difference between V1_d and the larger deviation correction value Vv_d.
  • the determining the deviation correction value corresponding to the pixel includes: setting the reset voltage of the reset transistor to a target voltage, where the target voltage is greater than zero and less than a voltage capable of resetting the floating diffusion region. voltage, so that the floating diffusion area can store charges under the action of the target voltage; control the transfer tube to be in a sub-threshold state, so that the charges stored in the floating diffusion area enter the photosensitive element; control the The reset tube resets the floating diffusion area; controls the transfer tube to conduct, so that the charge in the photosensitive element is transferred to the floating diffusion area; controls the readout circuit to read the floating diffusion area
  • the second signal voltage of the floating diffusion area is determined according to the second signal voltage of the floating diffusion area.
  • the deviation correction value corresponding to the pixel is determined.
  • the voltage of the reset power line is set to the target voltage Vg, for example, the voltage of the reset power line is changed from the first high voltage to the target voltage Vg, the target voltage Vg.
  • the voltage is greater than zero and less than a voltage capable of resetting the floating diffusion.
  • the first high voltage (not less than a voltage capable of resetting the floating diffusion region) is greater than the target voltage Vg.
  • the reset transistor when the reset voltage of the reset transistor is set to the target voltage, the reset transistor is controlled to be turned on for a preset period of time and then turned off, so that the floating diffusion region is in the The charge is stored under the action of the target voltage.
  • the floating diffusion area stores charges under the action of the target voltage, so that the voltage of the floating diffusion area is floated to Vfdm, and Vfdm is less than or equal to the target voltage Vg.
  • the reset voltage of the reset transistor is kept set to the target voltage, so as to improve the accuracy of the deviation correction value.
  • the transfer transistor when the reset transistor is controlled to be turned on for a predetermined period of time and then turned off, the transfer transistor is controlled to be in a sub-threshold state, so that the charges stored in the floating diffusion region enter the photosensitive element.
  • the level of the transfer tube control signal line can be set to the voltage Vm for a preset time period, so that the transfer tube is in a sub-threshold state, and the charges stored in the floating diffusion area can be reversed at this time. through) into the photosensitive element, as shown in FIG. 10 , due to the deviation of process manufacturing, the number of reversed charges between different pixels will not be completely consistent. For example, pixel C has more charges poured back into the photosensitive element than pixel D.
  • the time period S3 may include a calibration signal generation phase.
  • the voltage of the reset power line is set to the first high voltage
  • the electrical position of the reset tube control signal line is set to the first high voltage preset time period
  • the transmission tube is kept off. off
  • the floating diffusion area is connected to the reset power line
  • the first high voltage of the reset power line can clear the charge in the floating diffusion area and realize the reset of the floating diffusion area. Reserve.
  • the level of the transfer tube control signal line is set to a high level for a preset duration, and the transmission tube is controlled to be turned on for a preset duration.
  • the charges in the photosensitive element are transferred to the floating diffusion area.
  • all the charges in the photosensitive element are transferred to the floating diffusion area, which is only an example or an ideal situation. It is understood that the charges in the photosensitive element may be partially, such as 80%, transferred to the floating diffusion area. , the amount of charge transferred to the floating diffusion is positively correlated with the amount of charge accumulated in the photosensitive element. The transfer of charges in the photosensitive element to the floating diffusion area will cause the voltage of the floating diffusion area to change, and the magnitude of the voltage change is positively related to the amount of charges transferred to the floating diffusion area.
  • the electrical position of the row strobe control signal line is set to a high level in the time period S4, so that the row strobe is turned on, so that the readout circuit can read the floating diffusion
  • the voltage of the region is the second signal voltage Vsig2.
  • the gate transistor can be continuously turned on during the entire time period S4, or can be turned on when reading the voltage of the floating diffusion region.
  • the time period S4 may include a calibration signal readout phase.
  • the transfer transistor when the readout circuit is controlled to read the second signal voltage Vsig2 of the floating diffusion region, the transfer transistor is controlled to be turned off. As shown in FIG. 7 , after the level of the transfer tube control signal line is set to a high level for a preset period of time, so that the charges in the photosensitive element are transferred to the floating diffusion region, it is set to a low level to turn off
  • the transmission tube can control the readout circuit to read the second signal voltage Vsig2 of the floating diffusion region after the transmission tube is turned off. The accuracy of the floating diffusion voltage reading can be improved.
  • the second signal voltage of pixel C may be represented as Vsig2_c
  • the second signal voltage of pixel D may be represented as Vsig2_d.
  • the deviation correction value of each pixel can be determined according to the second signal voltage of the floating diffusion area of different pixels, for example
  • the deviation correction value Vv_c of pixel C is greater than the deviation correction value Vv_d of pixel D, and the difference delta V1 between the first reference voltage and the first signal voltage of each pixel is corrected according to the deviation correction value of each pixel, for example, when delta V1_c is smaller than delta When V1_d, delta V1_c+Vv_c can be equal to delta V1_d+Vv_d, so the imaging parameters of pixel C and pixel D with the same light intensity can be consistent.
  • the deviation correction value Vv_c of the pixel C can also be determined according to the second signal voltage of the pixel C and the pixel D to be smaller than the deviation correction value Vv_d of the pixel D.
  • the deviation correction value of each pixel is subtracted from the difference value of the first signal voltage, and the imaging parameter of the pixel is obtained.
  • the determining the offset correction value corresponding to the pixel according to the second signal voltage of the floating diffusion region includes: according to the second reference voltage of the floating diffusion region and the second signal The voltage determines the offset correction value corresponding to the pixel.
  • the second reference voltage includes a voltage when there is no charge in the floating diffusion region caused by the target voltage Vg, or includes a floating diffusion region before the charge in the photosensitive element caused by the target voltage Vg is transferred to the floating diffusion region zone voltage.
  • the second reference voltages of different pixels may be the same or different; the second reference voltages of the same pixel under different working conditions may be the same or different.
  • the readout circuit may be controlled to read the second reference voltage of the floating diffusion region.
  • the readout circuit is controlled before the transfer transistor is controlled to be turned on so that the charges in the photosensitive element are transferred to the floating diffusion region.
  • the voltage read from the floating diffusion region is the second reference voltage Vref2.
  • the first reference voltage of pixel C may be represented as Vref2_c
  • the first reference voltage of pixel D may be represented as Vref2_d.
  • the transfer transistor when the readout circuit is controlled to read the second reference voltage of the floating diffusion region, the transfer transistor is controlled to be turned off to prevent the electric charge in the photosensitive element from affecting the voltage of the floating diffusion region.
  • the second reference voltage of the floating diffusion region may be stored in advance, for example, an empirical value or a reference voltage read during a certain imaging, or a reference voltage read at any time. All pixels in the image sensor may use the same second reference voltage, or use different second reference voltages respectively.
  • the second reference voltage may be the same as the aforementioned first reference voltage, for example, the readout circuit may be controlled to read the reference voltage of the floating diffusion region only once during the period S1 to the period S4.
  • the second reference voltage of the floating diffusion region may be determined according to the first reference voltage of the floating diffusion region.
  • the determining the offset correction value corresponding to the pixel according to the second reference voltage of the floating diffusion region and the second signal voltage includes: according to the second reference voltage of the floating diffusion region The voltage difference between the voltage and the second signal voltage determines the offset correction value corresponding to the pixel.
  • delta V2_c Vref2_d-Vsig2_d.
  • the determining the deviation correction value corresponding to the pixel according to the voltage difference between the second reference voltage of the floating diffusion region and the second signal voltage includes: according to the voltage difference of the pixel The difference between the value and the reference voltage of the image sensor is used to determine the offset correction value corresponding to the pixel.
  • the reference voltage difference is used to indicate the reference of the voltage difference of the pixels in the image sensor.
  • the reference voltage difference value is determined according to the voltage difference value of at least one pixel in the image sensor, for example, the voltage difference value of one pixel may be determined as the reference voltage difference value, or the reference voltage difference value may be determined according to The average, extreme, median, or mathematical expectation of the voltage difference values of a plurality of pixels in the image sensor determines the reference voltage difference value.
  • the deviation correction value of each pixel according to the deviation degree (for example, the difference of subtraction) between the voltage difference value of each pixel and the reference voltage difference value, the imaging parameters of each pixel are corrected and calibrated according to the deviation correction value of each pixel.
  • the inflection point deviation of the first response stage and the second response stage between different pixels can be compensated due to the manufacturing process deviation, so that the inflection points between the first response stage and the second response stage of different pixels tend to be consistent, so It can reduce or eliminate the difference in the response of different pixels to the light intensity, improve the consistency of the entire image in the highlight, and reduce the noise in the image captured by the image sensor.
  • the determining the deviation correction value corresponding to the pixel according to the second signal voltage includes: determining the pixel according to the second signal voltage of the pixel and the reference signal voltage of the image sensor Corresponding deviation correction value.
  • the reference signal voltage is used to indicate the reference of the second signal voltage of the pixel in the image sensor.
  • the reference signal voltage is determined according to the second signal voltage of at least one pixel in the image sensor.
  • the second signal voltage of one pixel may be determined as the reference signal voltage, or the reference signal voltage may be determined according to the image sensor.
  • the reference signal voltage is determined by an average value, extreme value, median, or mathematical expectation of the second signal voltages of the plurality of pixels.
  • Correcting and calibrating the imaging parameters of each pixel according to the deviation correction value of each pixel can compensate the inflection point deviation of the first response stage and the second response stage between different pixels due to the deviation of the manufacturing process, so that the The inflection point between the first response stage and the second response stage tends to be consistent, so it is possible to reduce or eliminate the difference in the response of different pixels to the light intensity, improve the consistency of the entire image in the highlight, and reduce the image captured by the image sensor. the presence of noise.
  • control method of the image sensor includes the following four stages.
  • the first stage S1 is the reset exposure stage.
  • the transfer tube is set to a high level Vh first, so that the charge in the photosensitive element is completely emptied, the reset is completed, and then the transfer tube is placed at the voltage Vm (the voltage Vm is less than the high level Vh), and at the same time
  • the reset tube is turned off, the exposure starts, and the photogenerated charges are accumulated in the photosensitive element.
  • the exposure time is short and the signal is less.
  • the electrons accumulated in the photosensitive element increase rapidly with the exposure intensity, which is the first response stage (as shown in Figure 5). When the time is prolonged or the light is strong, the photosensitive element is close to saturation.
  • the second stage S2 is the signal readout stage.
  • the row strobe tube is set to a high level and turned on, the reset tube is set to a low level first, and the first reference voltage Vref1 is read out at the source end of the source follower tube, and then the transmission tube is turned on.
  • the photo-generated charges in the photosensitive element are poured into the floating diffusion area, and then the transfer tube is placed at a low potential V1 and turned off. At this time, the voltage of the floating diffusion area becomes low, and the first signal voltage Vsig1 is read at the source end of the source follower tube, which can be determined.
  • the third stage S3 is the self-calibration signal generation stage.
  • the reset power line changes from the first high voltage to a medium voltage target voltage Vg, and then the reset transistor is turned off.
  • the floating diffusion area floats a medium voltage Vfdm, and then The transfer tube changes from the low level Vl to the voltage Vm.
  • the charge in the floating diffusion area will be fed through into the photosensitive element. Due to the deviation of the manufacturing process, the number of back-feeding electrons between different pixels will not be exactly the same. .
  • the embodiment of the present application further provides an image sensor 200, please refer to FIG. 2 in conjunction with the above-mentioned embodiment.
  • the image sensor 200 includes a peripheral circuit 220 and a plurality of pixels 211.
  • the pixels 211 include a photosensitive element PD, a transmission transistor TX, a floating diffusion area FD, a reset transistor RST, and a readout circuit.
  • the transmission tube TX is connected between the photosensitive element PD and the floating diffusion region FD, and the floating diffusion region FD is connected with the reset tube RST and the readout circuit;
  • the peripheral circuit 220 is used to perform the following steps:
  • the transmission tube TX is controlled to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element PD enter the floating diffusion region FD;
  • the imaging parameter of the pixel 211 is determined according to the first reference voltage of the floating diffusion area FD and the first signal voltage.
  • FIG. 11 is a schematic block diagram of an imaging device 600 provided by an embodiment of the present application.
  • This imaging device 600 is equipped with the aforementioned image sensor 601 .
  • the imaging device 600 may further include a processor 602 , where the processor 602 is configured to process the image data output by the image sensor 601 into a captured picture that can be presented on the display screen 603 .
  • the imaging device 600 may further include a display screen 603 , and the processor 602 is configured to process the image data output by the image sensor 601 into a shooting picture that can be presented on the display screen 603 .
  • the imaging device may be a terminal.
  • the terminal may be a terminal device integrated with a camera and a display screen, including but not limited to a smart phone, a tablet, a handheld computer, a camera, and the like.
  • the camera in the terminal can be used to realize the functions of taking pictures and video
  • the display screen can be used to realize the preview function of the shooting picture, that is, by displaying the picture currently collected by the camera in real time for preview, so as to achieve the viewfinder. Effect.

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Abstract

A control method for an image sensor, an image sensor, and an imaging device. Said method comprises: enabling a pass transistor to be in a subthreshold state during exposure, so that photogenerated charges exceeding the capacity enter a floating diffusion region (S110); resetting the floating diffusion region (S120); turning on the pass transistor, so that the photogenerated charges in a photosensitive element are transmitted to the floating diffusion region (S130); reading a signal voltage of the floating diffusion region (S140); and determining imaging parameters of a pixel according to the signal voltage (S150). Said method can implement a wide dynamic range.

Description

图像传感器及其控制方法、搭载图像传感器的成像装置Image sensor and control method thereof, and imaging device equipped with image sensor 技术领域technical field
本申请涉及图像传感器技术领域,尤其涉及一种图像传感器及其控制方法、搭载图像传感器的成像装置。The present application relates to the technical field of image sensors, and in particular, to an image sensor, a control method thereof, and an imaging device equipped with an image sensor.
背景技术Background technique
图像传感器广泛用于消费电子、安防监控、工业自动化、人工智能、物联网等领域,用于图像数据信息的采集和整理,为后续处理和应用提供信息源。Image sensors are widely used in consumer electronics, security monitoring, industrial automation, artificial intelligence, Internet of Things and other fields. They are used to collect and organize image data information and provide information sources for subsequent processing and applications.
图像传感器按功能组成可以分为感光电路区和外围读取电路区。其中感光电路区的功能是负责把光信号,通过光敏元件转换成电信号并存储,然后交给后续外围读出电路用于转换成数字图像信号。The image sensor can be divided into a photosensitive circuit area and a peripheral reading circuit area according to its functional composition. The function of the photosensitive circuit area is to convert the optical signal into an electrical signal through the photosensitive element and store it, and then hand it over to the subsequent peripheral readout circuit for conversion into a digital image signal.
当外部场景的明暗对比十分强烈时,图像传感器如果要获得图像暗处的细节,容易导致亮处的图像细节会丢失,即动态范围(Dynami c Range,DR)受到限制。When the contrast between light and dark in the external scene is very strong, if the image sensor wants to obtain the details of the dark part of the image, it is easy to cause the loss of the image details in the bright part, that is, the dynamic range (DR) is limited.
发明内容SUMMARY OF THE INVENTION
基于此,本申请提供了一种图像传感器及其控制方法、搭载图像传感器的成像装置,能够实现图像传感器的较宽的动态范围。Based on this, the present application provides an image sensor and a control method thereof, and an imaging device equipped with the image sensor, which can realize a wider dynamic range of the image sensor.
第一方面,本申请实施例提供了一种图像传感器的控制方法,所述图像传感器包括多个像素,所述像素包括光敏元件、传输管、浮置扩散区、复位管和读出电路,所述传输管连接于所述光敏元件和所述浮置扩散区之间,所述浮置扩散区连接所述复位管和所述读出电路;In a first aspect, an embodiment of the present application provides a control method for an image sensor, the image sensor includes a plurality of pixels, and the pixels include a photosensitive element, a transfer tube, a floating diffusion area, a reset tube, and a readout circuit, so the transfer tube is connected between the photosensitive element and the floating diffusion region, and the floating diffusion region is connected with the reset tube and the readout circuit;
所述方法包括:The method includes:
在所述光敏元件接收光子以生成光生电荷时,控制所述传输管处于亚阈状态,以使超过所述光敏元件容量的光生电荷进入所述浮置扩散区;When the photosensitive element receives photons to generate photo-generated charges, controlling the transfer tube to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion region;
控制所述复位管复位所述浮置扩散区;controlling the reset tube to reset the floating diffusion region;
控制所述传输管导通,以使所述光敏元件中的光生电荷传输至所述浮置扩散区;controlling the conduction of the transfer tube, so that the photo-generated charges in the photosensitive element are transferred to the floating diffusion region;
控制所述读出电路读取所述浮置扩散区的第一信号电压;controlling the readout circuit to read the first signal voltage of the floating diffusion;
根据所述浮置扩散区的第一参考电压和所述第一信号电压确定所述像素的成像参数。The imaging parameter of the pixel is determined according to the first reference voltage of the floating diffusion region and the first signal voltage.
第二方面,本申请实施例提供了一种图像传感器,所述图像传感器包括外围电路和多个像素,所述像素包括光敏元件、传输管、浮置扩散区、复位管和读出电路,所述传输管连接于所述光敏元件和所述浮置扩散区之间,所述浮置扩散区连接所述复位管和所述读出电路;In a second aspect, an embodiment of the present application provides an image sensor, the image sensor includes a peripheral circuit and a plurality of pixels, and the pixels include a photosensitive element, a transfer tube, a floating diffusion area, a reset tube, and a readout circuit, so the transfer tube is connected between the photosensitive element and the floating diffusion region, and the floating diffusion region is connected with the reset tube and the readout circuit;
所述外围电路用于执行以下步骤:The peripheral circuit is used to perform the following steps:
在所述光敏元件接收光子以生成光生电荷时,控制所述传输管处于亚阈状态,以使超过所述光敏元件容量的光生电荷进入所述浮置扩散区;When the photosensitive element receives photons to generate photo-generated charges, controlling the transfer tube to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion region;
控制所述复位管复位所述浮置扩散区;controlling the reset tube to reset the floating diffusion region;
控制所述传输管导通,以使所述光敏元件中的光生电荷传输至所述浮置扩散区;controlling the conduction of the transfer tube, so that the photo-generated charges in the photosensitive element are transferred to the floating diffusion region;
控制所述读出电路读取所述浮置扩散区的第一信号电压;controlling the readout circuit to read the first signal voltage of the floating diffusion;
根据所述浮置扩散区的第一参考电压和所述第一信号电压确定所述像素的成像参数。The imaging parameter of the pixel is determined according to the first reference voltage of the floating diffusion region and the first signal voltage.
第三方面,本申请实施例提供了一种成像装置,搭载任一上述的图像传感器。In a third aspect, an embodiment of the present application provides an imaging device equipped with any of the above-mentioned image sensors.
本申请实施例提供了一种图像传感器及其控制方法、搭载图像传感器的成像装置,通过在光敏元件接收光子以生成光生电荷时,控制传输管处于亚阈状态以使超过光敏元件容量的光生电荷进入浮置扩散区,之后复位浮置扩散区,和控制传输管导通以使光敏元件中的光生电荷传输至浮置扩散区,以及控制读出电路读取浮置扩散区的第一信号电压,根据浮置扩散区的第一参考电压和第一信号电压确定像素的成像参数,使像素在亮处和暗处分别有不同的灵敏度,可以实现图像传感器的较宽的动态范围。The embodiments of the present application provide an image sensor and a control method thereof, and an imaging device equipped with the image sensor. When the photosensitive element receives photons to generate photo-generated charges, the transmission tube is controlled to be in a sub-threshold state to make the photo-generated charges exceeding the capacity of the photo-sensitive element. Enter the floating diffusion area, then reset the floating diffusion area, and control the conduction of the transfer tube to transfer the photo-generated charges in the photosensitive element to the floating diffusion area, and control the readout circuit to read the first signal voltage of the floating diffusion area , the imaging parameters of the pixels are determined according to the first reference voltage and the first signal voltage of the floating diffusion area, so that the pixels have different sensitivities in bright and dark places, and a wider dynamic range of the image sensor can be achieved.
应当理解的是,以上的一般描述和后文的细节描述仅是示例性和解释性的,并不能限制本申请实施例的公开内容。It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and do not limit the disclosure of the embodiments of the present application.
附图说明Description of drawings
为了更清楚地说明本申请实施例的技术方案,下面将对实施例描述中所需要使用的附图作简单地介绍,显而易见地,下面描述中的附图是本申请的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其他的附图。In order to explain the technical solutions of the embodiments of the present application more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.
图1是本申请实施例提供的一种图像传感器的控制方法的流程示意图;FIG. 1 is a schematic flowchart of a control method of an image sensor provided by an embodiment of the present application;
图2是一实施方式中图像传感器的结构示意图;2 is a schematic structural diagram of an image sensor in an embodiment;
图3是一实施方式中像素的结构示意图;3 is a schematic structural diagram of a pixel in an embodiment;
图4是一实施方式中像素阵列的结构示意图;4 is a schematic structural diagram of a pixel array in one embodiment;
图5是像素的输出信号与光照强度的关系示意图;5 is a schematic diagram of the relationship between the output signal of the pixel and the light intensity;
图6是一实施方式中像素在不同光照强度下成像的示意图;6 is a schematic diagram of imaging of pixels under different illumination intensities in one embodiment;
图7是一实施方式中图像传感器像素工作时的时序示意图;FIG. 7 is a timing diagram of an image sensor pixel during operation in an embodiment;
图8是不同像素的输出信号与光照强度的关系示意图;8 is a schematic diagram of the relationship between the output signal of different pixels and the light intensity;
图9是另一实施方式中像素在不同光照强度下成像的示意图;9 is a schematic diagram of imaging of pixels under different illumination intensities in another embodiment;
图10是确定像素的偏差修正值的示意图;10 is a schematic diagram of determining a deviation correction value of a pixel;
图11是本申请实施例提供的一种成像装置的结构示意图。FIG. 11 is a schematic structural diagram of an imaging device provided by an embodiment of the present application.
具体实施方式detailed description
下面将结合本申请实施例中的附图,对本申请实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例是本申请一部分实施例,而不是全部的实施例。基于本申请中的实施例,本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例,都属于本申请保护的范围。The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.
附图中所示的流程图仅是示例说明,不是必须包括所有的内容和操作/步骤,也不是必须按所描述的顺序执行。例如,有的操作/步骤还可以分解、组合或部分合并,因此实际执行的顺序有可能根据实际情况改变。The flowcharts shown in the figures are for illustration only, and do not necessarily include all contents and operations/steps, nor do they have to be performed in the order described. For example, some operations/steps can also be decomposed, combined or partially combined, so the actual execution order may be changed according to the actual situation.
下面结合附图,对本申请的一些实施方式作详细说明。在不冲突的情况下,下述的实施例及实施例中的特征可以相互组合。Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and features in the embodiments may be combined with each other without conflict.
请参阅图1,图1是本申请实施例提供的一种图像传感器的控制方法的流 程示意图。所述图像传感器的控制方法可以应用在图像传感器200和/或图像传感器的控制装置中,例如用于互补型半导体图像传感器(CIS)芯片中,或者用于图像传感器200的外围电路220中,用于控制图像传感器200成像等过程。Please refer to FIG. 1. FIG. 1 is a schematic flowchart of a control method of an image sensor provided by an embodiment of the present application. The control method of the image sensor can be applied in the image sensor 200 and/or the control device of the image sensor, for example, in the complementary semiconductor image sensor (CIS) chip, or in the peripheral circuit 220 of the image sensor 200, using It is used to control the imaging of the image sensor 200 and other processes.
在一些实施方式中,如图2所示,图像传感器200按功能组成可以分为用于感光的感光电路区210和用来控制和处理信号的外围电路220(又可称为控制电路),其中感光电路区210可以包括多个,如几万至几亿的像素211(pixel,又可称为感光单元),例如感光电路区210可以由大量的像素211按一定的方式组成阵列而成,即所谓的像素阵列。外围电路220则负责把像素211感生的信号转换成数字信号并读出。In some embodiments, as shown in FIG. 2 , the image sensor 200 can be divided into a photosensitive circuit area 210 for photosensitive and a peripheral circuit 220 (also referred to as a control circuit) for controlling and processing signals according to functional composition, wherein The photosensitive circuit area 210 may include multiple, such as tens of thousands to hundreds of millions of pixels 211 (pixels, also referred to as photosensitive units). The so-called pixel array. The peripheral circuit 220 is responsible for converting the signal induced by the pixel 211 into a digital signal and reading it out.
示例性的,控制电路可以用于实现曝光时间控制、自动增益控制等任务。为了使中各部分电路按规定的节拍动作,必须使用多个时序控制信号,为了便于摄像头的应用,还要求该能输出一些时序信号,如同步信号、行起始信号、场起始信号等。Exemplarily, the control circuit may be used to implement tasks such as exposure time control, automatic gain control, and the like. In order to make each part of the circuit operate according to the specified rhythm, multiple timing control signals must be used. In order to facilitate the application of the camera, it is also required to output some timing signals, such as synchronization signal, line start signal, field start signal, etc.
示例性的,外界光照射像素阵列,发生光电效应,在像素211内产生相应的电荷。行选择逻辑单元根据需要,选通相应的行像素。行像素内的图像信号通过各自所在列的信号总线传输到对应的模拟信号处理单元以及A/D转换器,转换成数字图像信号输出。其中的行选择逻辑单元可以对像素阵列逐行扫描也可隔行扫描。行选择逻辑单元与列选择逻辑单元配合使用可以实现图像的窗口提取功能。模拟信号处理单元的主要功能是对信号进行放大处理,并且提高信噪比。Exemplarily, when the pixel array is illuminated by external light, a photoelectric effect occurs, and corresponding charges are generated in the pixels 211 . The row select logic unit gates the corresponding row pixels as needed. The image signals in the row pixels are transmitted to the corresponding analog signal processing unit and the A/D converter through the signal bus of the respective column, and are converted into digital image signals for output. The row selection logic unit can scan the pixel array progressively or interlaced. The row selection logic unit is used in conjunction with the column selection logic unit to realize the window extraction function of the image. The main function of the analog signal processing unit is to amplify the signal and improve the signal-to-noise ratio.
在一些实施方式中,如图3所示,像素211包括光敏元件PD、传输管TX、浮置扩散区FD、复位管RST和读出电路。其中,光敏元件PD可以为光电二极管。In some embodiments, as shown in FIG. 3 , the pixel 211 includes a photosensitive element PD, a transfer transistor TX, a floating diffusion FD, a reset transistor RST, and a readout circuit. Wherein, the photosensitive element PD may be a photodiode.
示例性的,读出电路可以包括源跟随管SF和行选通管SEL。Exemplarily, the readout circuit may include a source follower transistor SF and a row strobe transistor SEL.
可以理解的,图3所示的像素211的结构仅是举例,本申请实施例不限于此,例如本申请实施例的控制方法可以应用于像素211的光敏元件PD通过一传输管TX连接浮置扩散区FD的各种结构的图像传感器200。It can be understood that the structure of the pixel 211 shown in FIG. 3 is only an example, and the embodiment of the present application is not limited thereto. For example, the control method of the embodiment of the present application can be applied to the photosensitive element PD of the pixel 211 to be connected to float through a transmission tube TX. The image sensor 200 of various structures of the diffusion region FD.
具体的,光敏元件PD把光子转换成电子,然后传输管TX把光生电子传输到浮置扩散区FD,感生出一个与光照强度对应的电压信号,该电压信号经过源跟随器电位平移后,交给外围电路220经过一定的处理转换成数字信号,进而 形成图像信息。Specifically, the photosensitive element PD converts photons into electrons, and then the transmission tube TX transmits the photogenerated electrons to the floating diffusion area FD, and induces a voltage signal corresponding to the light intensity. The peripheral circuit 220 is converted into a digital signal after certain processing, and then image information is formed.
具体的,如图3所示,传输管TX连接于所述光敏元件PD和所述浮置扩散区FD之间,所述浮置扩散区FD连接所述复位管RST和所述读出电路。Specifically, as shown in FIG. 3 , the transmission transistor TX is connected between the photosensitive element PD and the floating diffusion area FD, and the floating diffusion area FD is connected to the reset transistor RST and the readout circuit.
示例性的,光敏元件PD可以在入射光作用下生成光生电荷,以及在传输管TX打开(即,导通)时,将光生电荷传输至浮置扩散区FD,读出电路可以确定浮置扩散区FD在光生电荷作用下的电压变化,经过后续模拟-数字(AD)转换电路,即可转换成表征图像信息的数字信号。例如由外围电路220进行模拟-数字转换。Exemplarily, the photosensitive element PD can generate photo-generated charges under the action of incident light, and when the transfer tube TX is turned on (ie, turned on), the photo-generated charges are transferred to the floating diffusion region FD, and the readout circuit can determine the floating diffusion. The voltage change of the area FD under the action of the photo-generated charges can be converted into a digital signal representing image information through a subsequent analog-to-digital (AD) conversion circuit. Analog-to-digital conversion is performed, for example, by the peripheral circuit 220 .
在一些实施方式中,可以包括外围电路220,当然也可以不包括外围电路220,例如可以通过额外搭载的外围电路220实现模数转换等功能。In some embodiments, the peripheral circuit 220 may be included, of course, the peripheral circuit 220 may not be included, for example, functions such as analog-to-digital conversion may be implemented by the additionally mounted peripheral circuit 220 .
在一些实施方式中,如图4所示为图像传感器200中2×2像素阵列的电路原理示意图。其中,传输管TX控制信号线用于控制传输管TX,例如当传输管TX控制信号线的电位为高电平时,传输管TX导通以使光敏元件PD和浮置扩散区FD连通;复位电源线连接于复位管RST的一端,复位管RST控制信号线用于控制复位管RST,例如当复位管RST控制信号线的电位为高电平时,复位管RST导通,使得浮置扩散区FD连接复位电源线,当复位电源线的电压为第一高电压时,可以清空浮置扩散区FD中的光生电荷,实现浮置扩散区FD的复位,当复位管RST和传输管TX均导通时,复位电源线的第一高电压可以复位浮置扩散区FD和光敏元件PD。行选通管SEL控制信号线用于控制行选通管SEL,当行选通管SEL控制信号线的电位为高电平时,行选通管SEL导通,浮置扩散区FD的电压可以由读出电路读取,当行选通管SEL控制信号线的电位为低电平时,行选通管SEL关断。In some embodiments, FIG. 4 is a schematic circuit diagram of a 2×2 pixel array in the image sensor 200 . The transmission tube TX control signal line is used to control the transmission tube TX. For example, when the potential of the transmission tube TX control signal line is at a high level, the transmission tube TX is turned on to connect the photosensitive element PD and the floating diffusion area FD; reset the power supply The line is connected to one end of the reset transistor RST, and the reset transistor RST control signal line is used to control the reset transistor RST. For example, when the potential of the reset transistor RST control signal line is high, the reset transistor RST is turned on, so that the floating diffusion area FD is connected. Reset the power line, when the voltage of the reset power line is the first high voltage, the photo-generated charges in the floating diffusion area FD can be cleared, and the reset of the floating diffusion area FD can be realized. When both the reset transistor RST and the transmission transistor TX are turned on , the first high voltage of the reset power line can reset the floating diffusion FD and the photosensitive element PD. The row strobe SEL control signal line is used to control the row strobe SEL. When the potential of the row strobe SEL control signal line is high, the row strobe SEL is turned on, and the voltage of the floating diffusion area FD can be read by The output circuit reads, when the potential of the control signal line of the row strobe SEL is a low level, the row strobe SEL is turned off.
示例性的,复位电源线、复位管RST控制信号线、传输管TX控制信号线、行选通管SEL控制信号线为图像传感器200的行方向上布置的导线。Exemplarily, the reset power line, the reset transistor RST control signal line, the transmission transistor TX control signal line, and the row strobe SEL control signal line are wires arranged in the row direction of the image sensor 200 .
示例性的,源跟随管SF的漏端均连接电源VDD,源跟随管SF具有较高的输入电阻和较低的输出电阻,对前级电路相当于开路,对后级电路相当于一个恒压源,输出电压不受后级电路阻抗影响。Exemplarily, the drain terminals of the source follower transistor SF are all connected to the power supply VDD, and the source follower transistor SF has a high input resistance and a low output resistance, which is equivalent to an open circuit for the previous stage circuit, and is equivalent to a constant voltage for the latter stage circuit. source, the output voltage is not affected by the impedance of the subsequent circuit.
可以理解的,一般的图像传感器200对光的响应都是接近线性的,在光照作用下产生的光生电荷首先会被存储在光敏元件PD的电容里。如图5所示,随着光照强度的增加,光敏元件PD内存储的光生电荷达到饱和便不再增加,这样 的像素211单用于拍照采图时,当外部场景的明暗对比十分强烈时,如果要获得图像暗处的细节,那么图像高亮的区域,由于信号强度过大导致光敏元件PD电容饱和,输出信号满量程,导致亮处的图像细节会丢失,即动态范围受到限制。It can be understood that the response of the general image sensor 200 to light is close to linear, and the photo-generated charges generated under the action of light are first stored in the capacitance of the photosensitive element PD. As shown in FIG. 5 , with the increase of the light intensity, the photo-generated charge stored in the photosensitive element PD reaches saturation and will no longer increase. When such a pixel 211 is only used for taking pictures, when the contrast between light and dark in the external scene is very strong, If you want to obtain the details in the dark part of the image, then in the highlighted area of the image, due to the excessive signal intensity, the PD capacitance of the photosensitive element is saturated, and the output signal is full scale, resulting in the loss of image details in the bright part, that is, the dynamic range is limited.
针对该发现,本申请的发明人对图像传感器200的控制方法进行了改进,以防止图像传感器200在成像时亮处的图像细节丢失。In response to this finding, the inventors of the present application have improved the control method of the image sensor 200 to prevent the image sensor 200 from losing image details in bright areas during imaging.
如图1所示,本申请实施例的图像传感器的控制方法包括步骤S110至步骤S150。As shown in FIG. 1 , the control method of the image sensor according to the embodiment of the present application includes steps S110 to S150.
S110、在所述光敏元件接收光子以生成光生电荷时,控制所述传输管处于亚阈状态,以使超过所述光敏元件容量的光生电荷进入所述浮置扩散区。S110. When the photosensitive element receives photons to generate photo-generated charges, control the transfer tube to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion region.
晶体管的亚阈状态是晶体管(例如,如MOSFET)的一种重要工作状态,可称为晶体管的亚阈值区(Subthreshold region)。传输管处于亚阈状态时,传输管栅极的电压Vgs处在阈值电压VT以下,且传输管没有出现导电沟道,即传输管处于Vgs≤VT,且表面势ψs大致等于费米势ψb(即表面为弱反型)的状态,这时传输管可以通过一股较小的电流,该电流可称为亚阈电流。The subthreshold state of a transistor is an important working state of a transistor (eg, a MOSFET), and may be referred to as a subthreshold region of the transistor. When the transmission tube is in the sub-threshold state, the voltage Vgs of the transmission tube grid is below the threshold voltage VT, and the transmission tube does not have a conductive channel, that is, the transmission tube is at Vgs≤VT, and the surface potential ψs is roughly equal to the Fermi potential ψb ( That is, the surface is in the state of weak inversion), at this time, the transmission tube can pass a small current, which can be called subthreshold current.
可以理解的,控制所述传输管处于亚阈状态的电压大于零且小于控制所述传输管导通的电压。It can be understood that the voltage for controlling the transmission tube to be in a sub-threshold state is greater than zero and less than the voltage for controlling the conduction of the transmission tube.
示例性的,控制所述传输管导通的电压为2.5-5伏,控制所述传输管处于亚阈状态的电压为0.5-2.5伏。具体可以根据图像传感器的工艺、性能参数等确定。Exemplarily, the voltage for controlling the conduction of the transmission tube is 2.5-5 volts, and the voltage for controlling the transmission tube to be in a sub-threshold state is 0.5-2.5 volts. Specifically, it can be determined according to the process and performance parameters of the image sensor.
示例性的,如图6所示,图像传感器中的像素A和像素B在曝光时,光敏元件接收光子以生成光生电荷,像素A和像素B的光照强度不同时,生成的光生电荷的数量不同,如图6所示,像素B的部分光生电荷超过像素B的光敏元件的容量。在传输管处于亚阈状态时,超过像素B的光敏元件的容量的光生电荷通过像素B的传输管进入像素B的浮置扩散区。Exemplarily, as shown in FIG. 6 , when the pixel A and the pixel B in the image sensor are exposed, the photosensitive element receives photons to generate photo-generated charges. When the illumination intensity of the pixel A and the pixel B are different, the number of the generated photo-generated charges is different. , as shown in FIG. 6 , part of the photogenerated charge of pixel B exceeds the capacity of the photosensitive element of pixel B. When the transfer tube is in a sub-threshold state, the photo-generated charges exceeding the capacity of the photosensitive element of pixel B enter the floating diffusion region of pixel B through the transfer tube of pixel B.
在一些实施方式中,图像传感器像素工作时的时序如图7所示。In some embodiments, the timing of the operation of the image sensor pixels is shown in FIG. 7 .
如图7所示,在时间段S1,行选通管控制信号线的电平为低电平,读出电路可以不工作。在时间段S1,当复位管控制信号线的电位为低电平时,复位管关断,图像传感器可以曝光,光敏元件接收光子以生成光生电荷,因此时间段S1包括曝光阶段。当传输管控制信号线的电平置为电压Vm,且电压Vm小于阈 值电压VT时,传输管处于亚阈状态,如图6所示,超过像素B的光敏元件的容量的光生电荷通过像素B的传输管进入像素B的浮置扩散区。As shown in FIG. 7 , in the time period S1 , the level of the control signal line of the row strobe tube is a low level, and the readout circuit may not work. In the period S1, when the potential of the reset transistor control signal line is low, the reset transistor is turned off, the image sensor can be exposed, and the photosensitive element receives photons to generate photo-generated charges, so the period S1 includes the exposure phase. When the level of the transfer tube control signal line is set to the voltage Vm, and the voltage Vm is less than the threshold voltage VT, the transfer tube is in a sub-threshold state, as shown in FIG. The transfer tube enters the floating diffusion area of pixel B.
在一些实施方式中,如图6和图7所示,在所述光敏元件接收光子以生成光生电荷之前,控制所述复位管导通和所述传输管导通,以复位所述光敏元件和所述浮置扩散区。In some embodiments, as shown in FIG. 6 and FIG. 7 , before the photosensitive element receives photons to generate photo-generated charges, the reset transistor and the transfer transistor are controlled to be turned on to reset the photosensitive element and the transfer transistor. the floating diffusion region.
如图7所示,在时间段S1开始时,将复位管控制信号线的电位置为高电平,以及将传输管控制信号线的电平置为电压Vh(可称为高电平),电压Vh大于阈值电压VT,从而传输管导通以使光敏元件和浮置扩散区连通,且复位管导通使得浮置扩散区连接复位电源线,如图6所示,可以复位浮置扩散区和光敏元件,清空浮置扩散区和光敏元件中的光生电荷。因此时间段S1包括复位阶段。As shown in FIG. 7 , at the beginning of the time period S1, the electrical level of the reset tube control signal line is set to a high level, and the level of the transmission tube control signal line is set to a voltage Vh (which may be called a high level), The voltage Vh is greater than the threshold voltage VT, so that the transfer tube is turned on to connect the photosensitive element and the floating diffusion area, and the reset tube is turned on so that the floating diffusion area is connected to the reset power line, as shown in Figure 6, the floating diffusion area can be reset and photosensitive element, emptying the floating diffusion and photo-generated charge in the photosensitive element. The time period S1 therefore includes the reset phase.
在另一些实施方式中,可以在图像传感器每次成像结束后,控制所述复位管导通和所述传输管导通,以复位所述光敏元件和所述浮置扩散区。In other embodiments, after each imaging of the image sensor is completed, the conduction of the reset tube and the conduction of the transmission tube may be controlled to reset the photosensitive element and the floating diffusion region.
示例性的,在所述光敏元件接收光子以生成光生电荷时,控制所述复位管关断。如图7所示,在复位浮置扩散区和光敏元件之后,将复位管控制信号线的电位置为低电平,控制所述复位管关断,以便光敏元件接收光子生成光生电荷和存储光生电荷,以及将传输管控制信号线的电平置为电压Vm,以使超过所述光敏元件容量的光生电荷进入所述浮置扩散区。Exemplarily, when the photosensitive element receives photons to generate photo-generated charges, the reset transistor is controlled to be turned off. As shown in FIG. 7 , after resetting the floating diffusion region and the photosensitive element, the electrical position of the control signal line of the reset tube is set to a low level, and the reset tube is controlled to be turned off, so that the photosensitive element receives photons to generate photo-generated charges and store photo-generated charges. charge, and the level of the transfer tube control signal line is set to the voltage Vm, so that the photo-generated charge exceeding the capacity of the photosensitive element enters the floating diffusion region.
示例性的,在曝光结束后,将传输管控制信号线的电平置为低电平,控制传输管关断(完全关闭)。Exemplarily, after exposure is completed, the level of the transmission tube control signal line is set to a low level, and the transmission tube is controlled to be turned off (completely closed).
可以理解的,如图5所示,曝光开始时,光生电荷积累在光敏元件中,刚开始曝光时间短,信号较少,光敏元件中积累的光生电荷随曝光强度迅速增加,为第一响应阶段,当曝光时间延长或光照很强时,光敏元件接近饱和,由于传输管处于亚阈状态,光敏元件接近饱和时,一部分光生电荷会穿过传输管的底部,进入浮置扩散区,光生电荷为电子时使得浮置扩散区电压降低,此时光敏元件积累光生电荷随曝光强度的响应变慢,进入第二响应阶段。It can be understood that, as shown in Figure 5, at the beginning of exposure, the photo-generated charges are accumulated in the photosensitive element. The exposure time is short and the signal is less at the beginning. The photo-generated charges accumulated in the photosensitive element increase rapidly with the exposure intensity, which is the first response stage. , when the exposure time is prolonged or the light is strong, the photosensitive element is close to saturation. Since the transfer tube is in a sub-threshold state, when the photosensitive element is close to saturation, a part of the photo-generated charge will pass through the bottom of the transfer tube and enter the floating diffusion area. The photo-generated charge is The voltage of the floating diffusion area is reduced when the electrons are present. At this time, the response of the accumulated photo-generated charges of the photosensitive element to the exposure intensity becomes slower, and the second response stage is entered.
可以理解的,所述光敏元件的容量可以影响到第一响应阶段和第二响应阶段之间的拐点。例如当光敏元件中积累的光生电荷少于光敏元件的容量时,光敏元件中积累的光生电荷随曝光强度迅速增加;当光敏元件中积累的光生电荷达到或超过光敏元件的容量时,光敏元件积累光生电荷随曝光强度的响应变慢。It can be understood that the capacity of the photosensitive element can affect the inflection point between the first response stage and the second response stage. For example, when the photogenerated charge accumulated in the photosensitive element is less than the capacity of the photosensitive element, the photogenerated charge accumulated in the photosensitive element increases rapidly with the exposure intensity; when the photogenerated charge accumulated in the photosensitive element reaches or exceeds the capacity of the photosensitive element, the photosensitive element accumulates The photogenerated charge responds slower with exposure intensity.
S120、控制所述复位管复位所述浮置扩散区。S120. Control the reset transistor to reset the floating diffusion region.
在一些实施方式中,如图6和图7所示,在时间段S2,将复位管控制信号线的电位置为高电平预设时长,同时保持传输管关断,使得浮置扩散区连接复位电源线,复位电源线的第一高电压可以清空浮置扩散区中的光生电荷,实现浮置扩散区的复位,由于传输管关断,光敏元件中的电荷可以保留。In some embodiments, as shown in FIG. 6 and FIG. 7 , in the time period S2, the electrical position of the reset transistor control signal line is set to a high level for a preset period of time, while the transmission transistor is kept off, so that the floating diffusion area is connected Resetting the power line, the first high voltage of the reset power line can clear the photo-generated charge in the floating diffusion area, and realize the reset of the floating diffusion area. Since the transfer tube is turned off, the charge in the photosensitive element can be retained.
S130、控制所述传输管导通,以使所述光敏元件中的光生电荷传输至所述浮置扩散区。S130. Control the conduction of the transfer tube, so that the photo-generated charges in the photosensitive element are transferred to the floating diffusion region.
在一些实施方式中,如图7所示,在时间段S2复位所述浮置扩散区之后,将传输管控制信号线的电平置为高电平预设时长,控制所述传输管导通预设时长,如图6所示,光敏元件中的光生电荷传输至所述浮置扩散区。In some embodiments, as shown in FIG. 7 , after the floating diffusion area is reset in the time period S2, the level of the transmission tube control signal line is set to a high level for a preset period of time, and the transmission tube is controlled to be turned on. For a predetermined period of time, as shown in FIG. 6 , the photo-generated charges in the photosensitive element are transferred to the floating diffusion region.
在图6中,光敏元件中的光生电荷全部传输至所述浮置扩散区,仅为举例或理想情况,可以理解的,光敏元件中的光生电荷可以部分,如80%传输至所述浮置扩散区,传输至浮置扩散区的光生电荷的数量和光敏元件中积累的光生电荷的数量正相关。In FIG. 6 , all the photo-generated charges in the photosensitive element are transferred to the floating diffusion region, which is only an example or an ideal situation. It is understood that the photo-generated charges in the photosensitive element can be partially, such as 80%, transferred to the floating diffusion area. Diffusion region, the amount of photo-generated charge transferred to the floating diffusion region is positively correlated with the amount of photo-generated charge accumulated in the photosensitive element.
S140、控制所述读出电路读取所述浮置扩散区的第一信号电压。S140. Control the readout circuit to read the first signal voltage of the floating diffusion area.
光敏元件中的光生电荷传输至所述浮置扩散区,会引起浮置扩散区的电压发生变化,电压变化的幅度与传输至浮置扩散区的光生电荷的数量正相关,可以根据电压变化的幅度确定在像素曝光时光敏元件中积累的光生电荷的多少,从而可以得到该像素对应的光照强度。The photo-generated charges in the photosensitive element are transferred to the floating diffusion area, which will cause the voltage of the floating diffusion area to change. The magnitude of the voltage change is positively related to the amount of photo-generated charges transferred to the floating diffusion area. The amplitude determines the amount of photo-generated charge accumulated in the photosensitive element when the pixel is exposed, so that the light intensity corresponding to the pixel can be obtained.
在一些实施方式中,如图7所示,在时间段S2将行选通管控制信号线的电位置为高电平,以使行选通管导通,从而读出电路可以读取所述浮置扩散区的电压为第一信号电压Vsig1。可以理解的,选通管可以在整个时间段S2持续导通,也可以在读取浮置扩散区的电压时导通。时间段S2可以包括有效信号读出阶段。In some embodiments, as shown in FIG. 7 , the electrical position of the row strobe control signal line is set to a high level during the time period S2, so that the row strobe is turned on, so that the readout circuit can read the The voltage of the floating diffusion region is the first signal voltage Vsig1. It can be understood that the gate transistor can be continuously turned on during the entire time period S2, or can be turned on when reading the voltage of the floating diffusion region. Time period S2 may include a valid signal readout phase.
示例性的,可以在源跟随管的源端(source)读取浮置扩散区的电压。Exemplarily, the voltage of the floating diffusion can be read at the source of the source follower transistor.
示例性的,在控制所述读出电路读取所述浮置扩散区的第一信号电压时,控制所述传输管关断。如图7所示,在将传输管控制信号线的电平置为高电平预设时长之后,置为低电平以关断传输管,传输管关断后可以控制所述读出电路读取所述浮置扩散区的第一信号电压Vsig1。可以提高浮置扩散区电压读取的准确性。Exemplarily, when the readout circuit is controlled to read the first signal voltage of the floating diffusion region, the transmission transistor is controlled to be turned off. As shown in FIG. 7 , after the level of the transmission tube control signal line is set to a high level for a preset duration, it is set to a low level to turn off the transmission tube. After the transmission tube is turned off, the readout circuit can be controlled to read Take the first signal voltage Vsig1 of the floating diffusion area. The accuracy of the floating diffusion voltage reading can be improved.
如图6所示,像素A的第一信号电压可以表示为Vsig1_a,像素B的第一 信号电压可以表示为Vsig1_b。当像素A的光照强度小于像素B的光照强度时,像素B的光敏元件中积累的光生电荷多于像素A,光敏元件中的光生电荷传输至所述浮置扩散区后,像素B的浮置扩散区中的光生电荷也多于像素A,光生电荷为电子时,像素B的电压下降幅度大于像素A,例如Vsig1_a大于Vsig1_b。As shown in FIG. 6, the first signal voltage of pixel A may be represented as Vsig1_a, and the first signal voltage of pixel B may be represented as Vsig1_b. When the light intensity of pixel A is lower than the light intensity of pixel B, the photo-generated charge accumulated in the photosensitive element of pixel B is more than that of pixel A, and after the photo-generated charge in the photosensitive element is transferred to the floating diffusion area, the floating The photo-generated charges in the diffusion area are also more than those of the pixel A. When the photo-generated charges are electrons, the voltage drop of the pixel B is larger than that of the pixel A, for example, Vsig1_a is larger than Vsig1_b.
S150、根据所述浮置扩散区的第一参考电压和所述第一信号电压确定所述像素的成像参数。S150. Determine the imaging parameter of the pixel according to the first reference voltage of the floating diffusion region and the first signal voltage.
具体的,第一参考电压包括浮置扩散区中没有光生电荷时的电压,或者包括光敏元件中的光生电荷传输至所述浮置扩散区之前浮置扩散区的电压。不同像素的第一参考电压可以相同,也可以不相同;同一像素在不同工作条件下的第一参考电压可以相同,也可以不相同。Specifically, the first reference voltage includes the voltage when there is no photo-generated charge in the floating diffusion region, or includes the voltage of the floating diffusion region before the photo-generated charge in the photosensitive element is transferred to the floating diffusion region. The first reference voltages of different pixels may be the same or different; the first reference voltages of the same pixel under different working conditions may be the same or different.
在一些实施方式中,可以在控制所述复位管复位所述浮置扩散区,浮置扩散区被浮置为高电位之后,控制所述读出电路读取所述浮置扩散区的第一参考电压。In some embodiments, after the reset transistor is controlled to reset the floating diffusion and the floating diffusion is floated to a high level, the readout circuit may be controlled to read the first value of the floating diffusion. reference voltage.
示例性的,如图6和图7所示,在在时间段S2控制所述传输管导通以使所述光敏元件中的光生电荷传输至所述浮置扩散区之前,控制所述读出电路读取所述浮置扩散区的电压为第一参考电压Vref1。如图6所示,像素A的第一参考电压可以表示为Vref1_a,像素B的第一参考电压可以表示为Vref1_b。Exemplarily, as shown in FIG. 6 and FIG. 7 , the readout is controlled before the transfer tube is controlled to be turned on in the time period S2 so that the photo-generated charges in the photosensitive element are transferred to the floating diffusion region. The circuit reads the voltage of the floating diffusion as the first reference voltage Vref1. As shown in FIG. 6 , the first reference voltage of pixel A may be represented as Vref1_a, and the first reference voltage of pixel B may be represented as Vref1_b.
示例性的,在控制所述读出电路读取所述浮置扩散区的第一参考电压时,控制所述传输管关断,防止光敏元件中的光生电荷影响浮置扩散区的电压。Exemplarily, when the readout circuit is controlled to read the first reference voltage of the floating diffusion region, the transfer transistor is controlled to be turned off to prevent the photo-generated charges in the photosensitive element from affecting the voltage of the floating diffusion region.
在另一些实施方式中,所述浮置扩散区的参考电压可以预先存储,例如为经验值或者在某一次成像时读取的参考电压,也可以是在任意时刻读取的参考电压。图像传感器中的全部像素可以使用相同的参考电压,或者分别使用不同的参考电压。In other embodiments, the reference voltage of the floating diffusion region may be stored in advance, for example, an empirical value or a reference voltage read during a certain imaging, or a reference voltage read at any time. All pixels in an image sensor can use the same reference voltage, or each can use different reference voltages.
在一些实施方式中,可以根据各像素的浮置扩散区的第一参考电压Vref1和所述第一信号电压Vsig1的差值deltaV1=Vref1-Vsig1确定所述像素的成像参数。可以理解的,deltaV1为与相应像素的光照强度相关的信号电压,为入射光信号引起的电压差,经过后续模拟-数字(AD)转换电路,即可转换成表征图像信息的数字信号。例如由外围电路进行模拟-数字转换。根据像素阵列中各像素的成像参数可以得到图像传感器拍摄的图像。In some embodiments, the imaging parameter of each pixel can be determined according to the difference deltaV1=Vref1−Vsig1 between the first reference voltage Vref1 of the floating diffusion region of each pixel and the difference value deltaV1=Vref1−Vsig1 of the first signal voltage Vsig1 . It can be understood that deltaV1 is the signal voltage related to the illumination intensity of the corresponding pixel, and is the voltage difference caused by the incident light signal, which can be converted into a digital signal representing image information through a subsequent analog-to-digital (AD) conversion circuit. Analog-to-digital conversion is performed, for example, by peripheral circuits. The image captured by the image sensor can be obtained according to the imaging parameters of each pixel in the pixel array.
本申请实施例提供的图像传感器的控制方法,通过在光敏元件接收光子以 生成光生电荷时,控制传输管处于亚阈状态以使超过光敏元件容量的光生电荷进入浮置扩散区,之后复位浮置扩散区,和控制传输管导通以使光敏元件中的光生电荷传输至浮置扩散区,以及控制读出电路读取浮置扩散区的第一信号电压,根据浮置扩散区的第一参考电压和第一信号电压确定像素的成像参数,使像素在亮处和暗处分别有不同的灵敏度,可以实现图像传感器的较宽的动态范围。The control method of the image sensor provided by the embodiment of the present application, by controlling the transfer tube to be in a sub-threshold state when the photosensitive element receives photons to generate photo-generated charges, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion area, and then reset the floating area the diffusion area, and control the conduction of the transfer tube to transfer the photo-generated charges in the photosensitive element to the floating diffusion area, and control the readout circuit to read the first signal voltage of the floating diffusion area, according to the first reference of the floating diffusion area The voltage and the first signal voltage determine the imaging parameters of the pixels, so that the pixels have different sensitivities in bright and dark places, and a wider dynamic range of the image sensor can be realized.
具体的,亮处的像素光照强度较强,但超过光敏元件容量的光生电荷会进入浮置扩散区并被清空,因此亮处的像素灵敏度较低,高光信号层次差异可以被较多的保留下来;暗处的像素光照强度较弱,光生电荷超出光敏元件容量的概率较低,因此暗处的像素灵敏度较低,信噪比好。像素对不同光强的响应灵敏度不同,既可以保持暗处的细节,也可以较多的保留高亮处的颜色和/或亮度的层次。Specifically, the light intensity of the pixel in the bright place is stronger, but the photo-generated charge that exceeds the capacity of the photosensitive element will enter the floating diffusion area and be emptied, so the sensitivity of the pixel in the bright place is low, and the difference in the high light signal level can be preserved more. ; The light intensity of the pixel in the dark place is weak, and the probability of the photo-generated charge exceeding the capacity of the photosensitive element is low, so the pixel in the dark place has a low sensitivity and a good signal-to-noise ratio. Pixels have different sensitivities to different light intensities, which can preserve details in dark areas and retain more color and/or brightness levels in highlights.
在一些实施方式中,如图8所示,由于实际工艺的偏差,每个像素的第一响应阶段和第二响应阶段之间的拐点不完全一致,因此不同像素对光照强度的响应存在差异,例如会影响整个图像在高亮处的一致性,造成图像传感器拍摄的图像存在噪声。In some embodiments, as shown in FIG. 8, due to the deviation of the actual process, the inflection point between the first response stage and the second response stage of each pixel is not completely consistent, so there are differences in the response of different pixels to the light intensity, For example, it will affect the consistency of the entire image in the highlights, resulting in noise in the image captured by the image sensor.
在一些实施方式中,所述根据所述浮置扩散区的第一参考电压和所述第一信号电压确定所述像素的成像参数,包括:根据所述像素对应的偏差修正值,以及所述像素的第一参考电压和所述像素的第一信号电压确定所述像素的成像参数。In some embodiments, the determining the imaging parameter of the pixel according to the first reference voltage of the floating diffusion region and the first signal voltage includes: according to a deviation correction value corresponding to the pixel, and the The pixel's first reference voltage and the pixel's first signal voltage determine an imaging parameter of the pixel.
通过根据不同像素各自对应的偏差修正值,修正像素的成像参数,实现了不同像素的第一响应阶段和第二响应阶段之间拐点的差异校准机制,使不同像素的拐点趋于一致,使整个图像在高亮处的一致性更好,固定噪声(fixed pattern noise)更低。By correcting the imaging parameters of the pixels according to the corresponding deviation correction values of different pixels, the difference calibration mechanism of the inflection points between the first response stage and the second response stage of different pixels is realized, so that the inflection points of different pixels tend to be consistent, so that the whole The image has better consistency in highlights and lower fixed pattern noise.
示例性的,所述方法还包括:确定所述像素对应的偏差修正值。Exemplarily, the method further includes: determining a deviation correction value corresponding to the pixel.
在一些实施方式中,所述各像素对应的偏差修正值可以预先存储,例如为经验值或者在某一次成像时确定的各像素对应的偏差修正值,也可以是在任意时刻确定的像素对应的偏差修正值。在另一些实施方式中,可以在每次成像时,均确定各像素对应的偏差修正值,准确率更高。In some embodiments, the deviation correction value corresponding to each pixel may be stored in advance, such as an empirical value or a deviation correction value corresponding to each pixel determined during a certain imaging, or it may be determined at any time corresponding to a pixel Bias correction value. In other embodiments, the deviation correction value corresponding to each pixel may be determined during each imaging, with a higher accuracy.
可以理解的,所述光敏元件的容量可以影响到第一响应阶段和第二响应阶 段之间的拐点。示例性的,所述偏差修正值用于指示所述像素中光敏元件的容量的偏差。It will be appreciated that the capacity of the photosensitive element can affect the inflection point between the first response stage and the second response stage. Exemplarily, the deviation correction value is used to indicate the deviation of the capacity of the photosensitive element in the pixel.
示例性的,如图9所示,图像传感器中的像素C和像素D在曝光时,光照强度相同,生成的光生电荷的数量相同,且均有部分光生电荷超过光敏元件的容量。在传输管处于亚阈状态时,超过像素C和像素D的光敏元件的容量的光生电荷通过传输管进入像素C和像素D的浮置扩散区。Exemplarily, as shown in FIG. 9 , when the pixel C and the pixel D in the image sensor are exposed, the light intensity is the same, the number of photogenerated charges is the same, and some of the photogenerated charges exceed the capacity of the photosensitive element. When the transfer tube is in a sub-threshold state, photo-generated charges exceeding the capacity of the photosensitive elements of pixel C and pixel D enter the floating diffusion regions of pixel C and pixel D through the transfer tube.
如图9所示,像素C的光敏元件的容量小于像素D,像素C有较多的光生电荷进入像素C的浮置扩散区,像素D有较少的光生电荷进入像素D的浮置扩散区。之后各像素复位浮置扩散区,以及使所述光敏元件中的光生电荷传输至所述浮置扩散区,像素C有较少的光生电荷传输至像素C的浮置扩散区,像素D有较多的光生电荷传输至像素D的浮置扩散区,光生电荷为电子时,像素C的浮置扩散区的电压下降幅度小于像素D,像素C的第一参考电压Vref1_c和所述第一信号电压Vsig1_c的差值可以表示为delta V1_c=Vref1_c-Vsig1_c,第一参考电压Vref1_d和所述第一信号电压Vsig1_d的差值可以表示为delta V1_d=Vref1_d-Vsig1_d,则当像素C和像素D的参考电压相同,如Vref1_c等于Vref1_d,Vsig1_c大于Vsig1_d时,有delta V1_c小于delta V1_d。。因此,在高亮处的不同像素对光照强度的响应存在差异,会影响整个图像的一致性,造成图像传感器拍摄的图像存在噪声。As shown in FIG. 9 , the capacity of the photosensitive element of the pixel C is smaller than that of the pixel D, the pixel C has more photo-generated charges entering the floating diffusion area of the pixel C, and the pixel D has less photo-generated charges entering the floating diffusion area of the pixel D. . After that, each pixel resets the floating diffusion area, and transfers the photo-generated charges in the photosensitive element to the floating diffusion area. Pixel C has less photo-generated charges transferred to the floating diffusion area of pixel C, and pixel D has more photo-generated charges. A large amount of photo-generated charges are transferred to the floating diffusion area of pixel D. When the photo-generated charges are electrons, the voltage drop in the floating diffusion area of pixel C is smaller than that of pixel D. The first reference voltage Vref1_c of pixel C and the first signal voltage The difference of Vsig1_c can be expressed as delta V1_c=Vref1_c-Vsig1_c, and the difference between the first reference voltage Vref1_d and the first signal voltage Vsig1_d can be expressed as delta V1_d=Vref1_d-Vsig1_d, then when the reference voltages of pixel C and pixel D are The same, if Vref1_c is equal to Vref1_d, when Vsig1_c is greater than Vsig1_d, delta V1_c is smaller than delta V1_d. . Therefore, there are differences in the response of different pixels in the highlight to the light intensity, which will affect the consistency of the entire image, resulting in noise in the image captured by the image sensor.
示例性的,通过根据偏差修正值对第一参考电压Vref1和所述第一信号电压Vsig1的差值delta V1进行修正,可以使得光照强度相同的像素C和像素D的成像参数一致。Exemplarily, by correcting the difference delta V1 between the first reference voltage Vref1 and the first signal voltage Vsig1 according to the deviation correction value, the imaging parameters of the pixel C and the pixel D with the same illumination intensity can be made consistent.
在一些实施方式中,所述根据所述像素对应的偏差修正值,以及所述像素的第一参考电压和所述像素的第一信号电压确定所述像素的成像参数,包括:根据所述像素的第一参考电压和所述像素的第一信号电压的差值,以及所述像素的偏差修正值所述确定所述像素的成像参数。In some embodiments, the determining the imaging parameter of the pixel according to the deviation correction value corresponding to the pixel, the first reference voltage of the pixel and the first signal voltage of the pixel includes: according to the pixel The difference between the first reference voltage and the first signal voltage of the pixel, and the deviation correction value of the pixel determine the imaging parameter of the pixel.
示例性的,图9中像素C的所述差值表示为delta V1_c,像素C的偏差修正值表示为Vv_c,像素D的所述差值表示为delta V1_d,像素D的偏差修正值表示为Vv_d。Exemplarily, in FIG. 9, the difference value of pixel C is represented as delta V1_c, the deviation correction value of pixel C is represented as Vv_c, the difference value of pixel D is represented as delta V1_d, and the deviation correction value of pixel D is represented as Vv_d. .
示例性的,可以将所述各像素的第一参考电压和所述像素的第一信号电压的差值加上各像素的偏差修正值,得到所述像素的成像参数。若光敏元件容量 较小的像素C的偏差修正值Vv_c大于光敏元件容量较大的像素D偏差修正值Vv_d,delta V1_c小于delta V1_d时,delta V1_c与较大偏差修正值Vv_c的和,能够等于delta V1_d与较大偏差修正值Vv_d的和。Exemplarily, the difference between the first reference voltage of each pixel and the first signal voltage of the pixel may be added to the deviation correction value of each pixel to obtain the imaging parameter of the pixel. If the deviation correction value Vv_c of the pixel C with a small photosensitive element capacity is greater than the deviation correction value Vv_d of the pixel D with a large photosensitive element capacity, and delta V1_c is smaller than delta V1_d, the sum of delta V1_c and the larger deviation correction value Vv_c can be equal to delta The sum of V1_d and the larger deviation correction value Vv_d.
示例性的,可以将所述各像素的第一参考电压和所述像素的第一信号电压的差值减去各像素的偏差修正值,得到所述像素的成像参数。若光敏元件容量较小的像素C的偏差修正值Vv_c小于光敏元件容量较大的像素D偏差修正值Vv_d,delta V1_c小于delta V1_d时,delta V1_c与较小偏差修正值Vv_c的差,能够等于delta V1_d与较大偏差修正值Vv_d的差。Exemplarily, the deviation correction value of each pixel may be subtracted from the difference between the first reference voltage of each pixel and the first signal voltage of the pixel to obtain the imaging parameter of the pixel. If the deviation correction value Vv_c of the pixel C with a small photosensitive element capacity is smaller than the deviation correction value Vv_d of the pixel D with a large photosensitive element capacity, and delta V1_c is smaller than delta V1_d, the difference between delta V1_c and the small deviation correction value Vv_c can be equal to delta The difference between V1_d and the larger deviation correction value Vv_d.
在一些实施方式中,所述确定所述像素对应的偏差修正值,包括:将所述复位管的复位电压置为目标电压,所述目标电压大于零且小于能够复位所述浮置扩散区的电压,以使所述浮置扩散区在所述目标电压作用下储存电荷;控制所述传输管处于亚阈状态,以使所述浮置扩散区储存的电荷进入所述光敏元件;控制所述复位管复位所述浮置扩散区;控制所述传输管导通,以使所述光敏元件中的电荷传输至所述浮置扩散区;控制所述读出电路读取所述浮置扩散区的第二信号电压;根据所述浮置扩散区的第二信号电压确定所述像素对应的偏差修正值。In some embodiments, the determining the deviation correction value corresponding to the pixel includes: setting the reset voltage of the reset transistor to a target voltage, where the target voltage is greater than zero and less than a voltage capable of resetting the floating diffusion region. voltage, so that the floating diffusion area can store charges under the action of the target voltage; control the transfer tube to be in a sub-threshold state, so that the charges stored in the floating diffusion area enter the photosensitive element; control the The reset tube resets the floating diffusion area; controls the transfer tube to conduct, so that the charge in the photosensitive element is transferred to the floating diffusion area; controls the readout circuit to read the floating diffusion area The second signal voltage of the floating diffusion area is determined according to the second signal voltage of the floating diffusion area. The deviation correction value corresponding to the pixel is determined.
示例性的,如图7和图10所示,在时间段S3,将复位电源线的电压置为目标电压Vg,例如将复位电源线的电压从第一高电压变为目标电压Vg,该目标电压大于零且小于能够复位所述浮置扩散区的电压。在一个实施方式中,第一高电压(不小于能够复位所述浮置扩散区的电压)大于目标电压Vg。Exemplarily, as shown in FIG. 7 and FIG. 10 , in the time period S3, the voltage of the reset power line is set to the target voltage Vg, for example, the voltage of the reset power line is changed from the first high voltage to the target voltage Vg, the target voltage Vg. The voltage is greater than zero and less than a voltage capable of resetting the floating diffusion. In one embodiment, the first high voltage (not less than a voltage capable of resetting the floating diffusion region) is greater than the target voltage Vg.
示例性的,如图7所示,在将所述复位管的复位电压置为目标电压时,控制所述复位管导通预设时长后关断,以使所述浮置扩散区在所述目标电压作用下储存电荷。浮置扩散区在所述目标电压作用下储存电荷使得浮置扩散区的电压浮置为Vfdm,Vfdm小于或等于目标电压Vg。Exemplarily, as shown in FIG. 7 , when the reset voltage of the reset transistor is set to the target voltage, the reset transistor is controlled to be turned on for a preset period of time and then turned off, so that the floating diffusion region is in the The charge is stored under the action of the target voltage. The floating diffusion area stores charges under the action of the target voltage, so that the voltage of the floating diffusion area is floated to Vfdm, and Vfdm is less than or equal to the target voltage Vg.
示例性的,在控制所述传输管处于亚阈状态时,保持将所述复位管的复位电压置为所述目标电压,以提高偏差修正值的准确度。Exemplarily, when the transmission transistor is controlled to be in a sub-threshold state, the reset voltage of the reset transistor is kept set to the target voltage, so as to improve the accuracy of the deviation correction value.
示例性的,在控制所述复位管导通预设时长后关断时,控制所述传输管处于亚阈状态,以使所述浮置扩散区储存的电荷进入所述光敏元件。在将复位电压置为目标电压时,可以将传输管控制信号线的电平置为电压Vm预设时长,以使传输管处于亚阈状态,此时浮置扩散区储存的电荷能够倒灌(feed through) 进入所述光敏元件,如图10所示,由于工艺制造的偏差,不同像素之间的倒灌电荷数目也会不完全一致。例如,像素C倒灌进入光敏元件的电荷数目多于像素D。Exemplarily, when the reset transistor is controlled to be turned on for a predetermined period of time and then turned off, the transfer transistor is controlled to be in a sub-threshold state, so that the charges stored in the floating diffusion region enter the photosensitive element. When the reset voltage is set to the target voltage, the level of the transfer tube control signal line can be set to the voltage Vm for a preset time period, so that the transfer tube is in a sub-threshold state, and the charges stored in the floating diffusion area can be reversed at this time. through) into the photosensitive element, as shown in FIG. 10 , due to the deviation of process manufacturing, the number of reversed charges between different pixels will not be completely consistent. For example, pixel C has more charges poured back into the photosensitive element than pixel D.
示例性的,光敏元件容量较小的像素C,倒灌进入光敏元件的电荷较多,光敏元件容量较大的像素D,倒灌进入光敏元件的电荷较少。可以理解的,时间段S3可以包括校准信号生成阶段。Exemplarily, for pixel C with a smaller capacity of the photosensitive element, more charges are poured into the photosensitive element, and for pixel D with a larger capacity of the photosensitive element, less charge is poured into the photosensitive element. It will be appreciated that the time period S3 may include a calibration signal generation phase.
如图7和图10所示,在时间段S4,将复位电源线的电压置为第一高电压,将复位管控制信号线的电位置为第一高电压预设时长,同时保持传输管关断,使得浮置扩散区连接复位电源线,复位电源线的第一高电压可以清空浮置扩散区中的电荷,实现浮置扩散区的复位,由于传输管关断,光敏元件中的电荷可以保留。之后将传输管控制信号线的电平置为高电平预设时长,控制所述传输管导通预设时长,如图10所示,光敏元件中的电荷传输至所述浮置扩散区。As shown in FIG. 7 and FIG. 10 , in the time period S4, the voltage of the reset power line is set to the first high voltage, the electrical position of the reset tube control signal line is set to the first high voltage preset time period, and the transmission tube is kept off. off, the floating diffusion area is connected to the reset power line, and the first high voltage of the reset power line can clear the charge in the floating diffusion area and realize the reset of the floating diffusion area. Reserve. Then, the level of the transfer tube control signal line is set to a high level for a preset duration, and the transmission tube is controlled to be turned on for a preset duration. As shown in FIG. 10 , the charges in the photosensitive element are transferred to the floating diffusion area.
在图10中,光敏元件中的电荷全部传输至所述浮置扩散区,仅为举例或理想情况,可以理解的,光敏元件中的电荷可以部分,如80%传输至所述浮置扩散区,传输至浮置扩散区的电荷的数量和光敏元件中积累的电荷的数量正相关。光敏元件中的电荷传输至所述浮置扩散区,会引起浮置扩散区的电压发生变化,电压变化的幅度与传输至浮置扩散区的电荷的数量正相关。In FIG. 10 , all the charges in the photosensitive element are transferred to the floating diffusion area, which is only an example or an ideal situation. It is understood that the charges in the photosensitive element may be partially, such as 80%, transferred to the floating diffusion area. , the amount of charge transferred to the floating diffusion is positively correlated with the amount of charge accumulated in the photosensitive element. The transfer of charges in the photosensitive element to the floating diffusion area will cause the voltage of the floating diffusion area to change, and the magnitude of the voltage change is positively related to the amount of charges transferred to the floating diffusion area.
如图7和图10所示,在时间段S4将行选通管控制信号线的电位置为高电平,以使行选通管导通,从而读出电路可以读取所述浮置扩散区的电压为第二信号电压Vsig2。可以理解的,选通管可以在整个时间段S4持续导通,也可以在读取浮置扩散区的电压时导通。可以理解的,时间段S4可以包括校准信号读出阶段。As shown in FIG. 7 and FIG. 10 , the electrical position of the row strobe control signal line is set to a high level in the time period S4, so that the row strobe is turned on, so that the readout circuit can read the floating diffusion The voltage of the region is the second signal voltage Vsig2. It can be understood that the gate transistor can be continuously turned on during the entire time period S4, or can be turned on when reading the voltage of the floating diffusion region. It will be appreciated that the time period S4 may include a calibration signal readout phase.
示例性的,在控制所述读出电路读取所述浮置扩散区的第二信号电压Vsig2时,控制所述传输管关断。如图7所示,在将传输管控制信号线的电平置为高电平预设时长,以使光敏元件中的电荷传输至所述浮置扩散区之后,置为低电平以关断传输管,传输管关断后可以控制所述读出电路读取所述浮置扩散区的第二信号电压Vsig2。可以提高浮置扩散区电压读取的准确性。Exemplarily, when the readout circuit is controlled to read the second signal voltage Vsig2 of the floating diffusion region, the transfer transistor is controlled to be turned off. As shown in FIG. 7 , after the level of the transfer tube control signal line is set to a high level for a preset period of time, so that the charges in the photosensitive element are transferred to the floating diffusion region, it is set to a low level to turn off The transmission tube can control the readout circuit to read the second signal voltage Vsig2 of the floating diffusion region after the transmission tube is turned off. The accuracy of the floating diffusion voltage reading can be improved.
如图10所示,像素C的第二信号电压可以表示为Vsig2_c,像素D的第二信号电压可以表示为Vsig2_d。当像素C在拐点处的光照强度小于像素D,例如当像素C的光敏元件的容量小于像素D时,像素C倒灌进入光敏元件的电荷, 以及传输至浮置扩散区的电荷比像素D多,电荷为电子时,像素C的浮置扩散区的电压下降幅度大于像素D,例如可以有Vsig2_c小于Vsig2_d,可以根据不同像素的浮置扩散区的第二信号电压确定各像素的偏差修正值,例如像素C的偏差修正值Vv_c大于像素D偏差修正值Vv_d,以及根据各像素的偏差修正值对各像素的第一参考电压和第一信号电压的差值delta V1进行修正,例如当delta V1_c小于delta V1_d时,delta V1_c+Vv_c可以等于delta V1_d+Vv_d,因此可以使得光照强度相同的像素C和像素D的成像参数一致。可以理解的,也可以根据像素C和像素D的第二信号电压确定像素C的偏差修正值Vv_c小于像素D偏差修正值Vv_d,此时可以将所述各像素的第一参考电压和所述像素的第一信号电压的差值减去各像素的偏差修正值,得到所述像素的成像参数。As shown in FIG. 10 , the second signal voltage of pixel C may be represented as Vsig2_c, and the second signal voltage of pixel D may be represented as Vsig2_d. When the light intensity of the pixel C at the inflection point is lower than that of the pixel D, for example, when the capacity of the photosensitive element of the pixel C is smaller than that of the pixel D, the charge of the pixel C is reversed into the photosensitive element, and the charge transferred to the floating diffusion area is more than that of the pixel D, When the charge is electrons, the voltage drop of the floating diffusion area of pixel C is larger than that of pixel D. For example, Vsig2_c may be smaller than Vsig2_d. The deviation correction value of each pixel can be determined according to the second signal voltage of the floating diffusion area of different pixels, for example The deviation correction value Vv_c of pixel C is greater than the deviation correction value Vv_d of pixel D, and the difference delta V1 between the first reference voltage and the first signal voltage of each pixel is corrected according to the deviation correction value of each pixel, for example, when delta V1_c is smaller than delta When V1_d, delta V1_c+Vv_c can be equal to delta V1_d+Vv_d, so the imaging parameters of pixel C and pixel D with the same light intensity can be consistent. It can be understood that the deviation correction value Vv_c of the pixel C can also be determined according to the second signal voltage of the pixel C and the pixel D to be smaller than the deviation correction value Vv_d of the pixel D. The deviation correction value of each pixel is subtracted from the difference value of the first signal voltage, and the imaging parameter of the pixel is obtained.
在一些实施方式中,所述根据所述浮置扩散区的第二信号电压确定所述像素对应的偏差修正值,包括:根据所述浮置扩散区的第二参考电压和所述第二信号电压确定所述像素对应的偏差修正值。In some embodiments, the determining the offset correction value corresponding to the pixel according to the second signal voltage of the floating diffusion region includes: according to the second reference voltage of the floating diffusion region and the second signal The voltage determines the offset correction value corresponding to the pixel.
具体的,第二参考电压包括浮置扩散区中没有由目标电压Vg引起的电荷时的电压,或者包括由目标电压Vg引起的光敏元件中的电荷传输至所述浮置扩散区之前浮置扩散区的电压。不同像素的第二参考电压可以相同,也可以不相同;同一像素在不同工作条件下的第二参考电压可以相同,也可以不相同。Specifically, the second reference voltage includes a voltage when there is no charge in the floating diffusion region caused by the target voltage Vg, or includes a floating diffusion region before the charge in the photosensitive element caused by the target voltage Vg is transferred to the floating diffusion region zone voltage. The second reference voltages of different pixels may be the same or different; the second reference voltages of the same pixel under different working conditions may be the same or different.
在一些实施方式中,可以在控制所述复位管复位所述浮置扩散区之后,控制所述读出电路读取所述浮置扩散区的第二参考电压。In some embodiments, after controlling the reset transistor to reset the floating diffusion region, the readout circuit may be controlled to read the second reference voltage of the floating diffusion region.
示例性的,如图7和图10所示,在时间段S4,控制所述传输管导通以使所述光敏元件中的电荷传输至所述浮置扩散区之前,控制所述读出电路读取所述浮置扩散区的电压为第二参考电压Vref2。如图10所示,像素C的第一参考电压可以表示为Vref2_c,像素D的第一参考电压可以表示为Vref2_d。Exemplarily, as shown in FIG. 7 and FIG. 10 , in the time period S4 , the readout circuit is controlled before the transfer transistor is controlled to be turned on so that the charges in the photosensitive element are transferred to the floating diffusion region. The voltage read from the floating diffusion region is the second reference voltage Vref2. As shown in FIG. 10 , the first reference voltage of pixel C may be represented as Vref2_c, and the first reference voltage of pixel D may be represented as Vref2_d.
示例性的,在控制所述读出电路读取所述浮置扩散区的第二参考电压时,控制所述传输管关断,防止光敏元件中的电荷影响浮置扩散区的电压。Exemplarily, when the readout circuit is controlled to read the second reference voltage of the floating diffusion region, the transfer transistor is controlled to be turned off to prevent the electric charge in the photosensitive element from affecting the voltage of the floating diffusion region.
在另一些实施方式中,所述浮置扩散区的第二参考电压可以预先存储,例如为经验值或者在某一次成像时读取的参考电压,也可以是在任意时刻读取的参考电压。图像传感器中的全部像素可以使用相同的第二参考电压,或者分别使用不同的第二参考电压。In other embodiments, the second reference voltage of the floating diffusion region may be stored in advance, for example, an empirical value or a reference voltage read during a certain imaging, or a reference voltage read at any time. All pixels in the image sensor may use the same second reference voltage, or use different second reference voltages respectively.
示例性的,第二参考电压可以与前述的第一参考电压相同,例如可以在时 间段S1至时间段S4,仅控制所述读出电路读取一次所述浮置扩散区的参考电压。例如,所述浮置扩散区的第二参考电压可以根据所述浮置扩散区的第一参考电压确定。Exemplarily, the second reference voltage may be the same as the aforementioned first reference voltage, for example, the readout circuit may be controlled to read the reference voltage of the floating diffusion region only once during the period S1 to the period S4. For example, the second reference voltage of the floating diffusion region may be determined according to the first reference voltage of the floating diffusion region.
在一些实施方式中,所述根据所述浮置扩散区的第二参考电压和所述第二信号电压确定所述像素对应的偏差修正值,包括:根据所述浮置扩散区的第二参考电压和所述第二信号电压的电压差值确定所述像素对应的偏差修正值。In some embodiments, the determining the offset correction value corresponding to the pixel according to the second reference voltage of the floating diffusion region and the second signal voltage includes: according to the second reference voltage of the floating diffusion region The voltage difference between the voltage and the second signal voltage determines the offset correction value corresponding to the pixel.
示例性的,像素C的第二参考电压Vref2_c和第二信号电压Vsig2_c的电压差值可以表示为delta V2_c=Vref2_c-Vsig2_c,第二参考电压Vref2_d和所述第二信号电压Vsig2_d的电压差值可以表示为delta V2_d=Vref2_d-Vsig2_d。例如当Vsig2_c小于Vsig2_d时,有delta V2_c大于delta V2_d。可以根据电压差值delta V2_c和delta V2_d,确定像素C的偏差修正值Vv_c大于像素D偏差修正值Vv_d。Exemplarily, the voltage difference between the second reference voltage Vref2_c and the second signal voltage Vsig2_c of the pixel C may be expressed as delta V2_c=Vref2_c−Vsig2_c, and the voltage difference between the second reference voltage Vref2_d and the second signal voltage Vsig2_d may be Expressed as delta V2_d=Vref2_d-Vsig2_d. For example, when Vsig2_c is less than Vsig2_d, delta V2_c is greater than delta V2_d. According to the voltage difference values delta V2_c and delta V2_d, it can be determined that the deviation correction value Vv_c of the pixel C is greater than the deviation correction value Vv_d of the pixel D.
示例性的,所述根据所述浮置扩散区的第二参考电压和所述第二信号电压的电压差值确定所述像素对应的偏差修正值,包括:根据所述像素的所述电压差值和所述图像传感器的基准电压差值,确定所述像素对应的偏差修正值。Exemplarily, the determining the deviation correction value corresponding to the pixel according to the voltage difference between the second reference voltage of the floating diffusion region and the second signal voltage includes: according to the voltage difference of the pixel The difference between the value and the reference voltage of the image sensor is used to determine the offset correction value corresponding to the pixel.
具体的,基准电压差值用于指示图像传感器中像素的电压差值的基准。示例性的,所述基准电压差值根据所述图像传感器中至少一个像素的所述电压差值确定,例如,可以将其中一个像素的电压差值确定为所述基准电压差值,或者可以根据图像传感器中多个像素的所述电压差值的平均值、极值、中位数或者数学期望确定所述基准电压差值。通过根据各像素的电压差值和所述基准电压差值的偏差程度(例如相减的差)确定各像素的偏差修正值,根据各像素的偏差修正值对各像素的成像参数进行修正、校准,可以补偿由于制造工艺偏差带来的不同像素之间的第一响应阶段和第二响应阶段的拐点偏差,以使不同像素的第一响应阶段和第二响应阶段之间的拐点趋向一致,因此可以减小或消除不同像素对光照强度的响应存在的差异,提高整个图像在高亮处的一致性,降低图像传感器拍摄的图像存在的噪声。Specifically, the reference voltage difference is used to indicate the reference of the voltage difference of the pixels in the image sensor. Exemplarily, the reference voltage difference value is determined according to the voltage difference value of at least one pixel in the image sensor, for example, the voltage difference value of one pixel may be determined as the reference voltage difference value, or the reference voltage difference value may be determined according to The average, extreme, median, or mathematical expectation of the voltage difference values of a plurality of pixels in the image sensor determines the reference voltage difference value. By determining the deviation correction value of each pixel according to the deviation degree (for example, the difference of subtraction) between the voltage difference value of each pixel and the reference voltage difference value, the imaging parameters of each pixel are corrected and calibrated according to the deviation correction value of each pixel. , the inflection point deviation of the first response stage and the second response stage between different pixels can be compensated due to the manufacturing process deviation, so that the inflection points between the first response stage and the second response stage of different pixels tend to be consistent, so It can reduce or eliminate the difference in the response of different pixels to the light intensity, improve the consistency of the entire image in the highlight, and reduce the noise in the image captured by the image sensor.
在一些实施方式中,所述根据所述第二信号电压确定所述像素对应的偏差修正值,包括:根据所述像素的第二信号电压和所述图像传感器的基准信号电压,确定所述像素对应的偏差修正值。In some embodiments, the determining the deviation correction value corresponding to the pixel according to the second signal voltage includes: determining the pixel according to the second signal voltage of the pixel and the reference signal voltage of the image sensor Corresponding deviation correction value.
示例性的,基准信号电压用于指示图像传感器中像素的第二信号电压的基 准。示例性的,所述基准信号电压根据所述图像传感器中至少一个像素的第二信号电压确定,例如,可以将其中一个像素的第二信号电压确定为所述基准信号电压,或者可以根据图像传感器中多个像素的所述第二信号电压的平均值、极值、中位数或者数学期望确定所述基准信号电压。通过根据各像素的第二信号电压和所述基准信号电压的偏差程度(例如相减的差)确定各像素的偏差修正值,可以节省计算量。根据各像素的偏差修正值对各像素的成像参数进行修正、校准,可以补偿由于制造工艺偏差带来的不同像素之间的第一响应阶段和第二响应阶段的拐点偏差,以使不同像素的第一响应阶段和第二响应阶段之间的拐点趋向一致,因此可以减小或消除不同像素对光照强度的响应存在的差异,提高整个图像在高亮处的一致性,降低图像传感器拍摄的图像存在的噪声。Exemplarily, the reference signal voltage is used to indicate the reference of the second signal voltage of the pixel in the image sensor. Exemplarily, the reference signal voltage is determined according to the second signal voltage of at least one pixel in the image sensor. For example, the second signal voltage of one pixel may be determined as the reference signal voltage, or the reference signal voltage may be determined according to the image sensor. The reference signal voltage is determined by an average value, extreme value, median, or mathematical expectation of the second signal voltages of the plurality of pixels. By determining the deviation correction value of each pixel according to the deviation degree (eg, the difference of subtraction) between the second signal voltage of each pixel and the reference signal voltage, the amount of calculation can be saved. Correcting and calibrating the imaging parameters of each pixel according to the deviation correction value of each pixel can compensate the inflection point deviation of the first response stage and the second response stage between different pixels due to the deviation of the manufacturing process, so that the The inflection point between the first response stage and the second response stage tends to be consistent, so it is possible to reduce or eliminate the difference in the response of different pixels to the light intensity, improve the consistency of the entire image in the highlight, and reduce the image captured by the image sensor. the presence of noise.
在一些实施方式中,如图7所示,图像传感器的控制方法包括以下四个阶段。In some embodiments, as shown in FIG. 7 , the control method of the image sensor includes the following four stages.
第一个阶段S1为复位曝光阶段,传输管先置高电平Vh,使光敏元件内电荷被完全清空,复位完成,紧接着传输管置于电压Vm(电压Vm小于高电平Vh),同时复位管关闭,曝光开始,光生电荷积累在光敏元件内,刚开始曝光时间短,信号较少,光敏元件内积累的电子随曝光强度迅速增加,为第一响应阶段(如图5);随曝光时间延长或光照很强时,光敏元件接近饱和,由于传输管处于电压Vm的亚阈曝导通状态,光敏元件接近饱和时,一部分电子会穿过传输管底部,进入浮置扩散区,并使浮置扩散区电压降低,此时光敏元件电荷随曝光强度的响应变慢,进入第二响应阶段(如图5);曝光快结束时,传输管置于低电位Vl(低电位Vl小于电压Vm)使传输管完全关闭;由于实际工艺的偏差,每个像素的第一响应阶段和第二响应阶段的拐点不完全一致(如图8)。The first stage S1 is the reset exposure stage. The transfer tube is set to a high level Vh first, so that the charge in the photosensitive element is completely emptied, the reset is completed, and then the transfer tube is placed at the voltage Vm (the voltage Vm is less than the high level Vh), and at the same time The reset tube is turned off, the exposure starts, and the photogenerated charges are accumulated in the photosensitive element. At the beginning, the exposure time is short and the signal is less. The electrons accumulated in the photosensitive element increase rapidly with the exposure intensity, which is the first response stage (as shown in Figure 5). When the time is prolonged or the light is strong, the photosensitive element is close to saturation. Since the transmission tube is in the subthreshold exposure conduction state of the voltage Vm, when the photosensitive element is close to saturation, a part of the electrons will pass through the bottom of the transmission tube and enter the floating diffusion area. The voltage of the floating diffusion area decreases. At this time, the response of the charge of the photosensitive element to the exposure intensity becomes slower and enters the second response stage (as shown in Figure 5). ) to completely close the transfer tube; due to the deviation of the actual process, the inflection points of the first response stage and the second response stage of each pixel are not completely consistent (as shown in Figure 8).
第二阶段S2为信号读出阶段,行选通管置高电平打开,复位管先置于低电平,在源跟随管的源端读出第一参考电压Vref1,然后导通传输管,光敏元件中的光生电荷灌入浮置扩散区,之后传输管置于低电位Vl关闭,此时浮置扩散区电压变低,在源跟随管的源端读取第一信号电压Vsig1,可以确定delta V1=Vref1–Vsig1,deltaV1即为与光照强度相关的信号电压。The second stage S2 is the signal readout stage. The row strobe tube is set to a high level and turned on, the reset tube is set to a low level first, and the first reference voltage Vref1 is read out at the source end of the source follower tube, and then the transmission tube is turned on. The photo-generated charges in the photosensitive element are poured into the floating diffusion area, and then the transfer tube is placed at a low potential V1 and turned off. At this time, the voltage of the floating diffusion area becomes low, and the first signal voltage Vsig1 is read at the source end of the source follower tube, which can be determined. delta V1=Vref1-Vsig1, deltaV1 is the signal voltage related to the light intensity.
第三阶段S3为自校准信号生成阶段,该阶段复位电源线从第一高电压变为一个中等电压的目标电压Vg,然后关闭复位管,此时浮置扩散区浮置一个中等电压Vfdm,然后传输管从低电平Vl变为电压Vm,此时浮置扩散区内的电荷会倒 灌(feed through)进入光敏元件,由于工艺制造的偏差,不同像素之间的倒灌电子数目也会不完全一致。The third stage S3 is the self-calibration signal generation stage. In this stage, the reset power line changes from the first high voltage to a medium voltage target voltage Vg, and then the reset transistor is turned off. At this time, the floating diffusion area floats a medium voltage Vfdm, and then The transfer tube changes from the low level Vl to the voltage Vm. At this time, the charge in the floating diffusion area will be fed through into the photosensitive element. Due to the deviation of the manufacturing process, the number of back-feeding electrons between different pixels will not be exactly the same. .
第四阶段S4为校准信号读出阶段,复位电源线的电压回升到第一高电压,复位管关闭,读取第二参考电压Vref2,然后传输管开启,读取第二信号电压Vsig2,可以确定delta V2=Vref2–Vsig2,delta V2即可用来补偿由于制造工艺偏差带来的不同像素之间的第一响应阶段和第二响应阶段的拐点偏差,如图8所示,delta V2配以合适的补偿算法,就可以使不同像素的第一响应阶段和第二响应阶段的拐点趋于一致,使整个图像在高亮处的一致性更好,固定噪声更低。The fourth stage S4 is the calibration signal readout stage, the voltage of the reset power line rises back to the first high voltage, the reset tube is turned off, the second reference voltage Vref2 is read, and then the transmission tube is turned on, and the second signal voltage Vsig2 is read to determine delta V2=Vref2–Vsig2, delta V2 can be used to compensate for the inflection point deviation of the first response stage and the second response stage between different pixels due to manufacturing process deviations. As shown in Figure 8, delta V2 is matched with a suitable The compensation algorithm can make the inflection points of the first response stage and the second response stage of different pixels tend to be consistent, so that the consistency of the entire image in the highlight is better, and the fixed noise is lower.
本申请实施例还提供了一种图像传感器200,请结合上述实施例参阅图2。The embodiment of the present application further provides an image sensor 200, please refer to FIG. 2 in conjunction with the above-mentioned embodiment.
如图2所示,所述图像传感器200包括外围电路220和多个像素211,所述像素211包括光敏元件PD、传输管TX、浮置扩散区FD、复位管RST和读出电路,所述传输管TX连接于所述光敏元件PD和所述浮置扩散区FD之间,所述浮置扩散区FD连接所述复位管RST和所述读出电路;As shown in FIG. 2 , the image sensor 200 includes a peripheral circuit 220 and a plurality of pixels 211. The pixels 211 include a photosensitive element PD, a transmission transistor TX, a floating diffusion area FD, a reset transistor RST, and a readout circuit. The transmission tube TX is connected between the photosensitive element PD and the floating diffusion region FD, and the floating diffusion region FD is connected with the reset tube RST and the readout circuit;
所述外围电路220用于执行以下步骤:The peripheral circuit 220 is used to perform the following steps:
在所述光敏元件PD接收光子以生成光生电荷时,控制所述传输管TX处于亚阈状态,以使超过所述光敏元件PD容量的光生电荷进入所述浮置扩散区FD;When the photosensitive element PD receives photons to generate photo-generated charges, the transmission tube TX is controlled to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element PD enter the floating diffusion region FD;
控制所述复位管RST复位所述浮置扩散区FD;controlling the reset transistor RST to reset the floating diffusion region FD;
控制所述传输管TX导通,以使所述光敏元件PD中的光生电荷传输至所述浮置扩散区FD;controlling the transfer tube TX to be turned on, so that the photo-generated charges in the photosensitive element PD are transferred to the floating diffusion region FD;
控制所述读出电路读取所述浮置扩散区FD的第一信号电压;controlling the readout circuit to read the first signal voltage of the floating diffusion region FD;
根据所述浮置扩散区FD的第一参考电压和所述第一信号电压确定所述像素211的成像参数。The imaging parameter of the pixel 211 is determined according to the first reference voltage of the floating diffusion area FD and the first signal voltage.
本申请实施例提供的图像传感器200的具体原理和实现方式均与前述实施例的图像传感器200的控制方法类似,此处不再赘述。The specific principles and implementation manners of the image sensor 200 provided in the embodiments of the present application are similar to the control methods of the image sensor 200 in the foregoing embodiments, and are not repeated here.
请结合上述实施例参阅图11,图11是本申请一实施例提供的成像装置600的示意性框图。该成像装置600搭载前述的图像传感器601。Please refer to FIG. 11 in conjunction with the above embodiment. FIG. 11 is a schematic block diagram of an imaging device 600 provided by an embodiment of the present application. This imaging device 600 is equipped with the aforementioned image sensor 601 .
在一些实施方式中,图11所示,成像装置600还可以包括处理器602,该处理器602用于将该图像传感器601输出的图像数据处理为可以呈现在显示屏603上的拍摄画面。In some embodiments, as shown in FIG. 11 , the imaging device 600 may further include a processor 602 , where the processor 602 is configured to process the image data output by the image sensor 601 into a captured picture that can be presented on the display screen 603 .
在一些实施方式中,图11所示,成像装置600还可以包括显示屏603,处理器602用于将图像传感器601输出的图像数据处理为可以呈现在显示屏603上的拍摄画面。In some embodiments, as shown in FIG. 11 , the imaging device 600 may further include a display screen 603 , and the processor 602 is configured to process the image data output by the image sensor 601 into a shooting picture that can be presented on the display screen 603 .
示例性的,该成像装置可以为终端。该终端可以是集成了摄像头和显示屏的终端设备,包括但不限于智能手机,平板,掌上电脑,照相机等。该终端中的摄像头可以用于实现拍照、摄像功能,而显示屏可以用于实现对拍摄画面的预览功能,即,通过对摄像头当前收入的画面进行实时显示,以供用于预览,从而达到取景器的效果。Exemplarily, the imaging device may be a terminal. The terminal may be a terminal device integrated with a camera and a display screen, including but not limited to a smart phone, a tablet, a handheld computer, a camera, and the like. The camera in the terminal can be used to realize the functions of taking pictures and video, and the display screen can be used to realize the preview function of the shooting picture, that is, by displaying the picture currently collected by the camera in real time for preview, so as to achieve the viewfinder. Effect.
本申请实施例提供的成像装置备的具体原理和实现方式均与前述实施例的图像传感器类似,此处不再赘述。The specific principles and implementation manners of the imaging device provided by the embodiments of the present application are similar to the image sensors of the foregoing embodiments, and details are not described herein again.
应当理解,在此本申请中所使用的术语仅仅是出于描述特定实施例的目的而并不意在限制本申请。It should be understood that the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the application.
还应当理解,在本申请和所附权利要求书中使用的术语“和/或”是指相关联列出的项中的一个或多个的任何组合以及所有可能组合,并且包括这些组合。It will also be understood that, as used in this application and the appended claims, the term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items.
以上所述,仅为本申请的具体实施方式,但本申请的保护范围并不局限于此,任何熟悉本技术领域的技术人员在本申请揭露的技术范围内,可轻易想到各种等效的修改或替换,这些修改或替换都应涵盖在本申请的保护范围之内。因此,本申请的保护范围应以权利要求的保护范围为准。The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalents within the technical scope disclosed in the present application. Modifications or substitutions shall be covered by the protection scope of this application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (27)

  1. 一种图像传感器的控制方法,其特征在于,所述图像传感器包括多个像素,所述像素包括光敏元件、传输管、浮置扩散区、复位管和读出电路,所述传输管连接于所述光敏元件和所述浮置扩散区之间,所述浮置扩散区连接所述复位管和所述读出电路;A control method of an image sensor, characterized in that the image sensor includes a plurality of pixels, the pixels include a photosensitive element, a transfer tube, a floating diffusion area, a reset tube and a readout circuit, and the transfer tube is connected to the between the photosensitive element and the floating diffusion area, the floating diffusion area is connected to the reset transistor and the readout circuit;
    所述方法包括:The method includes:
    在所述光敏元件接收光子以生成光生电荷时,控制所述传输管处于亚阈状态,以使超过所述光敏元件容量的光生电荷进入所述浮置扩散区;When the photosensitive element receives photons to generate photo-generated charges, controlling the transfer tube to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion region;
    控制所述复位管复位所述浮置扩散区;controlling the reset tube to reset the floating diffusion region;
    控制所述传输管导通,以使所述光敏元件中的光生电荷传输至所述浮置扩散区;controlling the conduction of the transfer tube, so that the photo-generated charges in the photosensitive element are transferred to the floating diffusion region;
    控制所述读出电路读取所述浮置扩散区的第一信号电压;controlling the readout circuit to read the first signal voltage of the floating diffusion;
    根据所述浮置扩散区的第一参考电压和所述第一信号电压确定所述像素的成像参数。The imaging parameter of the pixel is determined according to the first reference voltage of the floating diffusion region and the first signal voltage.
  2. 根据权利要求1所述的方法,其特征在于,在所述光敏元件接收光子以生成光生电荷之前,控制所述复位管导通和所述传输管导通,以复位所述光敏元件和所述浮置扩散区。The method according to claim 1, characterized in that before the photosensitive element receives photons to generate photo-generated charges, the reset transistor and the transfer transistor are controlled to be turned on to reset the photosensitive element and the transfer transistor. Floating diffuser.
  3. 根据权利要求2所述的方法,其特征在于,在所述光敏元件接收光子以生成光生电荷时,控制所述复位管关断。The method according to claim 2, wherein when the photosensitive element receives photons to generate photo-generated charges, the reset transistor is controlled to be turned off.
  4. 根据权利要求1-3中任一项所述的方法,其特征在于,在控制所述复位管复位所述浮置扩散区之后,控制所述读出电路读取所述浮置扩散区的第一参考电压。The method according to any one of claims 1-3, characterized in that after controlling the reset transistor to reset the floating diffusion region, the readout circuit is controlled to read the first number of the floating diffusion region. a reference voltage.
  5. 根据权利要求4所述的方法,其特征在于,在控制所述读出电路读取所述浮置扩散区的第一信号电压和第一参考电压时,控制所述传输管关断。The method according to claim 4, wherein when the readout circuit is controlled to read the first signal voltage and the first reference voltage of the floating diffusion region, the transmission transistor is controlled to be turned off.
  6. 根据权利要求1-5中任一项所述的方法,其特征在于,所述根据所述浮置扩散区的第一参考电压和所述第一信号电压确定所述像素的成像参数,包括:The method according to any one of claims 1-5, wherein the determining the imaging parameter of the pixel according to the first reference voltage of the floating diffusion region and the first signal voltage comprises:
    根据所述像素对应的偏差修正值,以及所述像素的第一参考电压和所述像素的第一信号电压确定所述像素的成像参数。The imaging parameter of the pixel is determined according to the deviation correction value corresponding to the pixel, the first reference voltage of the pixel and the first signal voltage of the pixel.
  7. 根据权利要求6所述的方法,其特征在于,所述偏差修正值用于指示所述像素中光敏元件的容量的偏差。6. The method of claim 6, wherein the deviation correction value is used to indicate the deviation of the capacity of the photosensitive element in the pixel.
  8. 根据权利要求6所述的方法,其特征在于,所述方法还包括:The method according to claim 6, wherein the method further comprises:
    确定所述像素对应的偏差修正值。A deviation correction value corresponding to the pixel is determined.
  9. 根据权利要求8所述的方法,其特征在于,所述确定所述像素对应的偏差修正值,包括:The method according to claim 8, wherein the determining the deviation correction value corresponding to the pixel comprises:
    将所述复位管的复位电压置为目标电压,所述目标电压大于零且小于能够复位所述浮置扩散区的电压,以使所述浮置扩散区在所述目标电压作用下储存电荷;setting the reset voltage of the reset transistor to a target voltage, where the target voltage is greater than zero and less than a voltage capable of resetting the floating diffusion region, so that the floating diffusion region stores charges under the action of the target voltage;
    控制所述传输管处于亚阈状态,以使所述浮置扩散区储存的电荷进入所述光敏元件;controlling the transfer tube to be in a sub-threshold state, so that the charges stored in the floating diffusion region enter the photosensitive element;
    控制所述复位管复位所述浮置扩散区;controlling the reset tube to reset the floating diffusion region;
    控制所述传输管导通,以使所述光敏元件中的电荷传输至所述浮置扩散区;controlling the conduction of the transfer tube, so that the charges in the photosensitive element are transferred to the floating diffusion region;
    控制所述读出电路读取所述浮置扩散区的第二信号电压;controlling the readout circuit to read the second signal voltage of the floating diffusion area;
    根据所述浮置扩散区的第二信号电压确定所述像素对应的偏差修正值。The offset correction value corresponding to the pixel is determined according to the second signal voltage of the floating diffusion region.
  10. 根据权利要求9所述的方法,其特征在于,在将所述复位管的复位电压置为目标电压时,控制所述复位管导通预设时长后关断,以使所述浮置扩散区在所述目标电压作用下储存电荷。The method according to claim 9, wherein when the reset voltage of the reset transistor is set to a target voltage, the reset transistor is controlled to be turned on for a preset period of time and then turned off, so as to make the floating diffusion region Charge is stored under the target voltage.
  11. 根据权利要求10所述的方法,其特征在于,在控制所述复位管导通预设时长后关断时,控制所述传输管处于亚阈状态,以使所述浮置扩散区储存的电荷进入所述光敏元件。10 into the photosensitive element.
  12. 根据权利要求9-11中任一项所述的方法,其特征在于,在控制所述传输管处于亚阈状态时,保持将所述复位管的复位电压置为所述目标电压。The method according to any one of claims 9-11, characterized in that, when the transmission transistor is controlled to be in a sub-threshold state, the reset voltage of the reset transistor is kept set to the target voltage.
  13. 根据权利要求9-12中任一项所述的方法,其特征在于,所述根据所述浮置扩散区的第二信号电压确定所述像素对应的偏差修正值,包括:The method according to any one of claims 9-12, wherein the determining the offset correction value corresponding to the pixel according to the second signal voltage of the floating diffusion region comprises:
    根据所述浮置扩散区的第二参考电压和所述第二信号电压确定所述像素对应的偏差修正值。The offset correction value corresponding to the pixel is determined according to the second reference voltage of the floating diffusion region and the second signal voltage.
  14. 根据权利要求13所述的方法,其特征在于,在控制所述复位管复位所述浮置扩散区之后,控制所述读出电路读取所述浮置扩散区的第二参考电压。The method according to claim 13, wherein after controlling the reset transistor to reset the floating diffusion region, the readout circuit is controlled to read the second reference voltage of the floating diffusion region.
  15. 根据权利要求14所述的方法,其特征在于,在控制所述读出电路读取 所述浮置扩散区的第二信号电压和第二参考电压时,控制所述传输管关断。The method according to claim 14, wherein when the readout circuit is controlled to read the second signal voltage and the second reference voltage of the floating diffusion region, the transfer transistor is controlled to be turned off.
  16. 根据权利要求13所述的方法,其特征在于,所述浮置扩散区的第二参考电压根据所述浮置扩散区的第一参考电压确定。14. The method of claim 13, wherein the second reference voltage of the floating diffusion region is determined according to the first reference voltage of the floating diffusion region.
  17. 根据权利要求13-16中任一项所述的方法,其特征在于,所述根据所述浮置扩散区的第二参考电压和所述第二信号电压确定所述像素对应的偏差修正值,包括:The method according to any one of claims 13-16, wherein the determining the offset correction value corresponding to the pixel according to the second reference voltage of the floating diffusion region and the second signal voltage, include:
    根据所述浮置扩散区的第二参考电压和所述第二信号电压的电压差值确定所述像素对应的偏差修正值。The deviation correction value corresponding to the pixel is determined according to the voltage difference between the second reference voltage of the floating diffusion region and the second signal voltage.
  18. 根据权利要求17所述的方法,其特征在于,所述根据所述浮置扩散区的第二参考电压和所述第二信号电压的电压差值确定所述像素对应的偏差修正值,包括:The method according to claim 17, wherein the determining the offset correction value corresponding to the pixel according to the voltage difference between the second reference voltage of the floating diffusion region and the second signal voltage comprises:
    根据所述像素的所述电压差值和所述图像传感器的基准电压差值,确定所述像素对应的偏差修正值。A deviation correction value corresponding to the pixel is determined according to the voltage difference value of the pixel and the reference voltage difference value of the image sensor.
  19. 根据权利要求18所述的方法,其特征在于,所述基准电压差值根据所述图像传感器中至少一个像素的所述电压差值确定。19. The method of claim 18, wherein the reference voltage difference value is determined according to the voltage difference value of at least one pixel in the image sensor.
  20. 根据权利要求9-12中任一项所述的方法,其特征在于,所述根据所述第二信号电压确定所述像素对应的偏差修正值,包括:The method according to any one of claims 9-12, wherein the determining the deviation correction value corresponding to the pixel according to the second signal voltage comprises:
    根据所述像素的第二信号电压和所述图像传感器的基准信号电压,确定所述像素对应的偏差修正值。A deviation correction value corresponding to the pixel is determined according to the second signal voltage of the pixel and the reference signal voltage of the image sensor.
  21. 根据权利要求20所述的方法,其特征在于,所述基准信号电压根据所述图像传感器中至少一个像素的第二信号电压确定。21. The method of claim 20, wherein the reference signal voltage is determined according to a second signal voltage of at least one pixel in the image sensor.
  22. 根据权利要求6-20中任一项所述的方法,其特征在于,所述根据所述像素对应的偏差修正值,以及所述像素的第一参考电压和所述像素的第一信号电压确定所述像素的成像参数,包括:The method according to any one of claims 6-20, wherein the determining is based on a deviation correction value corresponding to the pixel, a first reference voltage of the pixel, and a first signal voltage of the pixel The imaging parameters of the pixel include:
    根据所述像素的第一参考电压和所述像素的第一信号电压的差值,以及所述像素的偏差修正值所述确定所述像素的成像参数。The imaging parameter of the pixel is determined according to the difference between the first reference voltage of the pixel and the first signal voltage of the pixel, and the deviation correction value of the pixel.
  23. 根据权利要求22所述的方法,其特征在于,将所述像素的第一参考电压和所述像素的第一信号电压的差值加上所述像素的偏差修正值,得到所述像素的成像参数;或者The method according to claim 22, wherein the image of the pixel is obtained by adding a difference between the first reference voltage of the pixel and the first signal voltage of the pixel and a deviation correction value of the pixel parameters; or
    将所述像素的第一参考电压和所述像素的第一信号电压的差值减去所述像 素的偏差修正值,得到所述像素的成像参数。The difference between the first reference voltage of the pixel and the first signal voltage of the pixel is subtracted from the deviation correction value of the pixel to obtain the imaging parameter of the pixel.
  24. 根据权利要求1-23中任一项所述的方法,其特征在于,控制所述传输管处于亚阈状态的电压大于零且小于控制所述传输管导通的电压。The method according to any one of claims 1-23, wherein the voltage for controlling the transmission tube to be in a sub-threshold state is greater than zero and less than the voltage for controlling the conduction of the transmission tube.
  25. 根据权利要求24所述的方法,其特征在于,控制所述传输管导通的电压为2.5-5伏,控制所述传输管处于亚阈状态的电压为0.5-2.5伏。The method according to claim 24, wherein the voltage for controlling the conduction of the transmission tube is 2.5-5 volts, and the voltage for controlling the transmission tube to be in a sub-threshold state is 0.5-2.5 volts.
  26. 一种图像传感器,其特征在于,所述图像传感器包括外围电路和多个像素,所述像素包括光敏元件、传输管、浮置扩散区、复位管和读出电路,所述传输管连接于所述光敏元件和所述浮置扩散区之间,所述浮置扩散区连接所述复位管和所述读出电路;An image sensor, characterized in that the image sensor includes a peripheral circuit and a plurality of pixels, the pixels include a photosensitive element, a transfer tube, a floating diffusion area, a reset tube and a readout circuit, and the transfer tube is connected to the between the photosensitive element and the floating diffusion area, the floating diffusion area is connected to the reset transistor and the readout circuit;
    所述外围电路用于执行以下步骤:The peripheral circuit is used to perform the following steps:
    在所述光敏元件接收光子以生成光生电荷时,控制所述传输管处于亚阈状态,以使超过所述光敏元件容量的光生电荷进入所述浮置扩散区;When the photosensitive element receives photons to generate photo-generated charges, controlling the transfer tube to be in a sub-threshold state, so that the photo-generated charges exceeding the capacity of the photosensitive element enter the floating diffusion region;
    控制所述复位管复位所述浮置扩散区;controlling the reset tube to reset the floating diffusion region;
    控制所述传输管导通,以使所述光敏元件中的光生电荷传输至所述浮置扩散区;controlling the conduction of the transfer tube, so that the photo-generated charges in the photosensitive element are transferred to the floating diffusion region;
    控制所述读出电路读取所述浮置扩散区的第一信号电压;controlling the readout circuit to read the first signal voltage of the floating diffusion;
    根据所述浮置扩散区的第一参考电压和所述第一信号电压确定所述像素的成像参数。The imaging parameter of the pixel is determined according to the first reference voltage of the floating diffusion region and the first signal voltage.
  27. 一种成像装置,其特征在于,搭载如权利要求26所述的图像传感器。An imaging device comprising the image sensor according to claim 26 .
PCT/CN2020/117891 2020-09-25 2020-09-25 Image sensor and control method therefor, and imaging device carrying image sensor WO2022061761A1 (en)

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