JP5212536B2 - Solid-state imaging device, signal processing method for solid-state imaging device, and imaging device - Google Patents

Description

  The present invention relates to a solid-state imaging device, a signal processing method for the solid-state imaging device, and an imaging device.

  In a solid-state imaging device, many proposals have been made so far regarding color coding color filter arrays using a color that is a main component of a luminance signal, for example, white (W), and signal processing for the purpose of increasing sensitivity. (For example, see Patent Document 1). As color coding using white, there are many color coding of white checkered in which white is arranged in a checkered pattern.

  Since the color filter array using white has a higher output voltage than the color filter array of the RGB Bayer array that has been widely used heretofore, the sensitivity of the solid-state imaging device can be increased. Here, the RGB Bayer arrangement is color coding in which green (G; Green) is arranged in a checkered pattern and red (R; Red) and blue (B: Blue) are arranged in a checkered pattern in the remaining part.

  On the other hand, in a solid-state imaging device using an RGB Bayer array color filter array, a luminance signal Y is generated when converting an RGB signal into a YUV signal (Y: luminance signal, U, V: color difference signal). Therefore, an arithmetic process is required. As the calculation process, for example, a calculation of Y = 0.29891 × R + 0.58661 × G + 10.1448 × B is performed.

  These arithmetic processes are generally performed by a DSP (Digital Signal Processor) provided outside the substrate (sensor chip) of the solid-state imaging device. Therefore, even in a solid-state imaging device using a color filter array including white, the arithmetic processing is performed by a DSP outside the sensor chip to generate the luminance signal Y.

JP 2007-287891 A

  However, an existing RGB Bayer array DSP cannot be used for signal processing of a solid-state imaging device using a color filter array including white. Therefore, if the color coding is changed, a new DSP needs to be developed. In addition, enormous development costs are required to change a widely used RGB Bayer array DSP to a white checkered DSP. Since this development cost is reflected in the product price of the camera module including the DSP, it hinders the cost reduction of the camera module and prevents the spread of color coding using white.

  Therefore, the present invention provides a solid-state image pickup device and a solid-state image pickup device signal that enable use of an existing RGB Bayer array DSP when using color coding in which the main component of the luminance signal is arranged in a checkered pattern. An object is to provide a processing method and an imaging apparatus.

In order to achieve the above object, the present invention provides pixels on a pixel array unit in which pixels are arranged two-dimensionally in a matrix, and white filters corresponding to the color that is the main component of the luminance signal are arranged in a checkered pattern, red and blue of each filter in a checkered arrangement of 2 × 2 pixel pitch, and between red and blue of each filter is in two oblique pixel shift, and the color filter unit rest is in the green filter, the same as the pixel array unit provided on the substrate, and a conversion processing unit for converting into a corresponding signal of the signal corresponding to the color arrangement of the color filter unit to the base tire sequences output from each pixel of the pixel array unit, The conversion processing unit performs addition between the two pixels of the same color with one pixel skipping diagonally with respect to the red and blue pixel signals at the time of moving image capturing, and generates a pixel signal of each color of the Bayer array using the pixel signal after the addition. .

  In the solid-state imaging device having the above-described configuration, the colors arranged in a checkered pattern are the colors that are the main components of the luminance signal. Can be restored. Therefore, it is possible to increase the conversion efficiency when converting a signal corresponding to the color arrangement of the color filter section into a signal corresponding to the Bayer arrangement. Then, by outputting a signal corresponding to the Bayer array from the substrate (sensor chip) on which the pixel array unit is formed, an existing DSP for Bayer array can be used as a signal processing unit at the subsequent stage.

  According to the present invention, even if the color coding is changed, the existing RGB Bayer array DSP can be used, so that it is not necessary to newly develop a DSP that requires enormous development costs.

1 is a system configuration diagram illustrating an outline of a configuration of a CMOS image sensor according to an embodiment of the present invention. It is a circuit diagram which shows an example of the circuit structure of a unit pixel. It is a circuit diagram which shows an example of a circuit structure in case adjacent 4 pixel addition is performed within a pixel. It is a color arrangement | sequence diagram which shows the color coding which concerns on a 1st specific example. It is a color arrangement | sequence figure which shows the color coding which concerns on a 2nd specific example. It is a color arrangement | sequence diagram which shows the color coding which concerns on a 3rd specific example. It is a color arrangement | sequence diagram which shows the color coding which concerns on a 4th specific example. It is a color arrangement | sequence diagram which shows the color coding which concerns on a 5th specific example. It is a color arrangement | sequence diagram which shows the color coding which concerns on a 6th specific example. It is a color arrangement | sequence diagram which shows the color coding which concerns on a 7th specific example. It is a color arrangement | sequence diagram which shows the color coding based on an 8th example. It is a color arrangement | sequence diagram which shows the color coding which concerns on a 9th specific example. It is a flowchart which shows the flow of an example of the color conversion process 1 at the time of the high brightness | luminance at the time of a full scan in the case of the color coding which concerns on a 1st specific example. It is a conceptual diagram of the color conversion process 1 at the time of high brightness | luminance at the time of a full scan in the case of the color coding which concerns on a 1st specific example. It is a flowchart which shows the flow of an example of the color conversion process 2 at the time of the low brightness at the time of a full scan in the case of the color coding which concerns on a 1st specific example. It is a conceptual diagram of the color conversion process 2 at the time of low brightness at the time of full scan in the case of color coding according to the first specific example. It is a flowchart which shows the flow of an example of the pixel addition process 1 in the case of the color coding which concerns on a 1st specific example. It is a conceptual diagram of the pixel addition process 1 in the case of the color coding which concerns on a 1st specific example. It is explanatory drawing about FD addition and counter addition. It is a flowchart which shows the flow of an example of the pixel addition process 2 in the case of the color coding which concerns on a 1st specific example. It is a conceptual diagram of the pixel addition process 2 in the case of the color coding which concerns on a 1st specific example. It is a flowchart which shows the flow of an example of the pixel addition process 3 in the case of the color coding which concerns on a 1st specific example. It is a conceptual diagram of the pixel addition process 3 in the case of the color coding which concerns on a 1st specific example. It is a conceptual diagram of the color conversion process at the time of a full scan in the case of the color coding which concerns on a 2nd example. It is a conceptual diagram of the pixel addition process in the case of the color coding which concerns on a 2nd specific example. It is a conceptual diagram of the color conversion process at the time of a full scan in the case of the color coding which concerns on a 3rd example. It is a conceptual diagram of the pixel addition process in the case of the color coding which concerns on a 3rd specific example. It is a conceptual diagram of the color conversion process at the time of a full scan in the case of the color coding which concerns on a 4th specific example. It is a conceptual diagram of the 1st pixel addition process in the case of the color coding which concerns on a 4th specific example. It is a conceptual diagram of the 2nd pixel addition process in the case of the color coding which concerns on a 4th specific example. It is a conceptual diagram of the 3rd pixel addition process in the case of the color coding which concerns on a 4th specific example. It is a conceptual diagram of the 4th pixel addition process in the case of the color coding which concerns on a 4th specific example. It is a conceptual diagram of the color conversion process at the time of a full scan in the case of the color coding which concerns on a 5th example. It is a conceptual diagram of the pixel addition process in the case of the color coding which concerns on a 5th example. It is a conceptual diagram of the color conversion process 1 in the case of the color coding which concerns on a 6th specific example. It is a conceptual diagram of the color conversion process 2 in the case of the color coding which concerns on a 6th specific example. It is a conceptual diagram of the pixel addition process 1 in the case of the color coding which concerns on a 6th specific example. It is a conceptual diagram of the pixel addition process 2 in the case of the color coding which concerns on a 6th specific example. It is a conceptual diagram of the color conversion process at the time of a full scan in the case of the color coding which concerns on a 7th example. It is a conceptual diagram of the pixel addition process in the case of the color coding which concerns on a 7th specific example. It is a conceptual diagram of the color conversion process at the time of a full scan in the case of the color coding which concerns on an 8th specific example. It is a conceptual diagram of the pixel addition process in the case of the color coding which concerns on an 8th example. It is a conceptual diagram of the color conversion process at the time of a full scan in the case of the color coding which concerns on a 9th example. It is a conceptual diagram of the pixel addition process in the case of the color coding which concerns on a 9th specific example. It is a block diagram which shows an example of a structure of the imaging device which concerns on this invention.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment 1-1. System configuration 1-2. Color coding of color filter array 1-3. Specific example of color coding 1-4. W: G: R: B sensitivity ratio 1-5. 1. Color conversion process Application example (imaging device)

<1. Embodiment> [1-1. System configuration]
FIG. 1 is a system configuration diagram showing an outline of the configuration of a solid-state imaging device according to an embodiment of the present invention, for example, a CMOS image sensor which is a kind of XY address type solid-state imaging device.

  The CMOS image sensor 10 according to the present embodiment includes a pixel array unit 12 formed on a semiconductor substrate (hereinafter sometimes simply referred to as “sensor chip”) 11 and the same semiconductor substrate 11 as the pixel array unit 12. And a peripheral circuit portion integrated thereon. As the peripheral circuit unit, for example, a vertical driving unit 13, a column processing unit 14, a horizontal driving unit 15, a conversion processing unit 16, and a system control unit 18 are provided.

  In the pixel array unit 12, unit pixels (not shown) including a photoelectric conversion element that photoelectrically converts incident visible light into a charge amount corresponding to the amount of light (hereinafter sometimes simply referred to as “pixel”) are arranged in a matrix. Are two-dimensionally arranged. A specific circuit configuration of the unit pixel will be described later. A color filter array 30 is provided on the light receiving surface (light incident surface) side of the pixel array unit 12. In this embodiment, the color coding of the color filter array 30 is one of the features, and details thereof will be described later.

  The pixel array unit 12 is further provided with a pixel drive line 18 for each row of the matrix-like pixel arrangement along the horizontal direction (pixel arrangement direction / horizontal direction of the pixel row) for each row, and a vertical signal for each column. A line 19 is formed along the vertical direction (pixel array direction / vertical direction of the pixel column) in the figure. In FIG. 1, one pixel drive line 18 is shown, but the number is not limited to one. One end of the pixel drive line 18 is connected to an output end corresponding to each row of the vertical drive unit 13.

  The vertical drive unit 13 includes a shift register, an address decoder, and the like. Here, although the illustration of a specific configuration is omitted, the vertical drive unit 13 has a configuration including a readout scanning system and a sweep scanning system. The readout scanning system sequentially performs selective scanning in units of rows for unit pixels from which signals are read out.

  On the other hand, the sweep-out scanning system removes unnecessary charges from the photoelectric conversion elements of the unit pixels of the readout row preceding the readout scan by the time of the shutter speed with respect to the readout row where the readout scanning is performed by the readout scanning system. Sweep out (reset) sweep scanning. A so-called electronic shutter operation is performed by sweeping (reset) unnecessary charges by the sweep scanning system. Here, the electronic shutter operation refers to an operation in which the photoelectric charge of the photoelectric conversion element is discarded and a new exposure is started (photocharge accumulation is started).

The signal read by the reading operation by the reading scanning system corresponds to the amount of light incident after the immediately preceding reading operation or electronic shutter operation. The period from the read timing by the previous read operation or the sweep timing by the electronic shutter operation to the read timing by the current read operation is the photocharge accumulation time (exposure time) in the unit pixel.

  A signal output from each unit pixel of the pixel row selectively scanned by the vertical driving unit 13 is supplied to the column processing unit 14 through each of the vertical signal lines 19. The column processing unit 14 performs predetermined signal processing on the analog pixel signal output from each pixel in the selected row for each pixel column of the pixel array unit 12.

  Examples of signal processing in the column processing unit 14 include CDS (Correlated Double Sampling) processing. In the CDS process, a reset level and a signal level output from each pixel in a selected row are captured, and a signal of pixels for one row is obtained by taking a difference between these levels, and a fixed pattern noise of the pixel is removed. It is. The column processing unit 14 may be provided with an A / D conversion function for digitizing an analog pixel signal.

  The horizontal driving unit 15 includes a shift register, an address decoder, and the like, and selectively scans circuit portions corresponding to the pixel columns of the column processing unit 14 in order. By the selective scanning by the horizontal driving unit 15, pixel signals that are signal-processed for each pixel column by the column processing unit 14 are sequentially output.

  The conversion processing unit 16 converts a signal corresponding to the color array of the color filter array (color filter unit) 30 output from each pixel of the pixel array unit 12 into a signal corresponding to the Bayer array by arithmetic processing. Perform the process. In the present embodiment, the conversion processing unit 16 is provided on the same substrate as the pixel array unit 12, that is, the sensor chip 11, and color conversion processing is performed on the sensor chip 11 to output a signal corresponding to the Bayer array outside the sensor chip 11. Another feature is the point of output to. Details of specific conversion processing in the conversion processing unit 16 will be described later in detail.

Here, as is well known, the Bayer array is two types of color information components in which colors that are the main components of a luminance signal that requires high resolution are arranged in a checkered pattern, and the remaining portions do not require a relatively high resolution. A color arrangement in which the colors of are arranged in a checkered pattern. As a basic form of the Bayer arrangement, color coding of a color arrangement in which green (G), which has a large contribution ratio of the luminance signal, is arranged in a checkered pattern and R (red) / B (blue) is arranged in a checkered pattern in the remaining part. Is mentioned.

  The system control unit 17 receives a clock given from the outside of the sensor chip 11, data for instructing an operation mode, and the like, and outputs data such as internal information of the CMOS image sensor 10. The system control unit 17 further includes a timing generator that generates various timing signals, and based on the various timing signals generated by the timing generator, the vertical driving unit 13, the column processing unit 14, the horizontal driving unit 14, and the like. Drive control of the conversion processing unit 16 and the like is performed.

(Circuit configuration of unit pixel)
FIG. 2 is a circuit diagram illustrating an example of a circuit configuration of the unit pixel 20. As shown in FIG. 2, the unit pixel 20 according to this circuit example includes a photoelectric conversion element, for example, a photodiode 21, and four transistors, for example, a transfer transistor 22, a reset transistor 23, an amplification transistor 24, and a selection transistor 25. It has a configuration.

  Here, as the four transistors 22 to 25, for example, N-channel MOS transistors are used. However, the conductivity type combinations of the transfer transistor 22, the reset transistor 23, the amplification transistor 24, and the selection transistor 25 illustrated here are merely examples, and are not limited to these combinations.

  For the unit pixel 20, as the pixel drive line 18, for example, three drive wirings of a transfer line 181, a reset line 182 and a selection line 183 are provided in common for each pixel in the same pixel row. One end of each of the transfer line 181, the reset line 182, and the selection line 183 is connected to the output end corresponding to each pixel row of the vertical drive unit 13 in units of pixel rows.

  The photodiode 21 has an anode electrode connected to a negative power source (for example, ground), and photoelectrically converts received light into photocharge (here, photoelectrons) having a charge amount corresponding to the light amount. The cathode electrode of the photodiode 21 is electrically connected to the gate electrode of the amplification transistor 24 through the transfer transistor 22. A node 26 electrically connected to the gate electrode of the amplification transistor 24 is referred to as an FD (floating diffusion) portion.

  The transfer transistor 22 is connected between the cathode electrode of the photodiode 21 and the FD portion 26. A transfer pulse φTRF in which the high level (for example, Vdd level) is active (hereinafter referred to as “High active”) is applied to the gate electrode of the transfer transistor 22 via the transfer line 181. When the transfer pulse φTRF is applied, the transfer transistor 22 is turned on and the photoelectric charge photoelectrically converted by the photodiode 21 is transferred to the FD unit 26.

  The reset transistor 23 has a drain electrode connected to the pixel power source Vdd and a source electrode connected to the FD unit 26. A high active reset pulse φRST is applied to the gate electrode of the reset transistor 23 via the reset line 182 prior to the transfer of the signal charge from the photodiode 21 to the FD unit 26. When the reset pulse φRST is given, the reset transistor 23 is turned on, and the FD unit 26 is reset by discarding the charge of the FD unit 26 to the pixel power supply Vdd.

  The amplification transistor 24 has a gate electrode connected to the FD unit 26 and a drain electrode connected to the pixel power source Vdd. Then, the amplification transistor 24 outputs the potential of the FD unit 26 after being reset by the reset transistor 23 as a reset signal (reset level) Vreset. The amplification transistor 24 further outputs the potential of the FD unit 26 after the transfer of the signal charge by the transfer transistor 22 as a light accumulation signal (signal level) Vsig.

  For example, the selection transistor 25 has a drain electrode connected to the source electrode of the amplification transistor 24 and a source electrode connected to the vertical signal line 17. A high active selection pulse φSEL is applied to the gate electrode of the selection transistor 25 via a selection line 163. When the selection pulse φSEL is given, the selection transistor 25 is turned on, the unit pixel 20 is selected, and the signal output from the amplification transistor 24 is relayed to the vertical signal line 17.

  Note that the selection transistor 25 may have a circuit configuration connected between the pixel power supply Vdd and the drain of the amplification transistor 24.

  In addition, the unit pixel 20 is not limited to the pixel configuration including the four transistors having the above configuration. For example, a pixel configuration including three transistors that serve as both the amplification transistor 24 and the selection transistor 25 may be used, and the configuration of the pixel circuit is not limited.

  By the way, in general, pixel addition is performed to add and read signals from a plurality of adjacent pixels in order to increase the frame rate when capturing a moving image. This can be performed in the pixel, on the signal line, in the column processing unit 14, or in the subsequent signal processing unit. Here, as an example, a pixel configuration in the case where signals of four pixels adjacent vertically and horizontally are added within the pixel will be described.

  FIG. 3 is a circuit diagram showing an example of a circuit configuration in the case where adjacent four-pixel addition is performed within a pixel. In FIG. 3, the same parts as those in FIG.

  In FIG. 3, the four-pixel photodiodes 21 that are adjacent vertically and horizontally are referred to as photodiodes 21-1, 21-2, 21-3, and 21-4. For these photodiodes 21-1, 21-2, 21-3, 21-4, four transfer transistors 22-1, 22-2, 22-3, 22-4 are provided, and reset transistors 23, One amplification transistor 24 and one selection transistor 25 are provided.

  That is, each of the transfer transistors 22-1, 22-2, 22-3, and 22-4 has one electrode connected to each cathode electrode of the photodiodes 21-1, 21-2, 21-3, and 21-4. The other electrode is connected in common to the gate electrode of the amplification transistor 24. A common FD section 26 is electrically connected to the photodiodes 21-1, 21-2, 21-3, and 21-4 at the gate electrode of the amplification transistor 24. The reset transistor 23 has a drain electrode connected to the pixel power source Vdd and a source electrode connected to the FD unit 26.

  In the pixel configuration corresponding to the addition of adjacent four pixels in the above configuration, the transfer pulses φTRF are applied to the four transfer transistors 22-1, 22-2, 22-3, and 22-4 at the same timing so as to be adjacent to each other. Pixel addition between four pixels can be realized. That is, the signal charges transferred from the photodiodes 21-1, 21-2, 21-3, 21-4 to the FD unit 26 by the transfer transistors 22-1, 22-2, 22-3, 22-4 are The FD unit 26 adds the values.

  On the other hand, by supplying the transfer pulse φTRF to the transfer transistors 22-1, 22-2, 22-3, and 22-4 at different timings, signal output in units of pixels can be realized. That is, the frame rate can be improved by performing pixel addition at the time of moving image capturing, whereas the resolution can be improved by reading the signals of all the pixels independently at the time of still image capturing.

[1-2. Color coding of color filter array]
Next, color coding of the color filter array 30 as one of the features of the present embodiment will be described.

  The color filter array 30 according to the present embodiment has a color coding of a color arrangement in which the colors that are the main components of the luminance signal are arranged in a checkered pattern and a plurality of colors that are the color information components are arranged in the remaining portion. . Here, examples of the color that is the main component of the luminance signal include white (W), green (G), and luminance spectroscopy.

  Since the W filter has a sensitivity that is about twice as high as that of the G filter (the output level is high), a high S / N can be realized. However, since the W filter includes various types of color information, so-called color falsification that reproduces a color different from the original color of the subject is likely to occur. Conversely, the G filter is less sensitive than the W filter, but is less likely to produce color falsification. That is, sensitivity and color falsity are in a trade-off relationship.

  When the W filter is arranged in a checkered pattern as the main component of the luminance signal, the multiple color filters that are color information components arranged in the remaining portion are R / G / B filters. On the other hand, when the G filters are arranged in a checkered pattern as the main component of the luminance signal, the multiple color filters that are color information components arranged in the remaining portions are R / B filters.

  As described above, by using a color coding array in which the W filter is arranged in a checkered pattern as the main color of the luminance signal as the color filter array 30, the sensitivity of the W filter is higher than that of other colors. Therefore, high sensitivity of the CMOS image sensor 10 can be achieved. On the other hand, since the color filter array 30 uses a color coding array in which the G filter is arranged in a checkered pattern as the main component of the luminance signal, the G filter is less prone to color falsification than the W filter. The color reproducibility of the CMOS image sensor 10 can be improved.

  When any color coding color filter array 30 is used, signals corresponding to these color arrays are converted on the sensor chip 11 into signals corresponding to the Bayer array. At this time, since the colors that are the main components of the luminance signal are arranged in a checkered pattern, the signals of the other main colors can be restored using the color signals that are the main components. The conversion efficiency of the color conversion in the unit 16 can be increased.

  Further, by outputting a signal corresponding to the Bayer array from the sensor chip 11, an existing DSP for the Bayer array can be used as a signal processing unit at the subsequent stage. The DSP for the Bayer array performs a process of generating the luminance signal Y and the two color difference signals U (B−Y) and V (R−Y) based on the signal corresponding to the Bayer array output from the sensor chip 11. Basic processing.

  As described above, since the existing DSP for the Bayer array can be used, even if the color coding of the color filter array 30 is changed, it is not necessary to newly develop a DSP that requires enormous development costs. As a result, the cost of the camera module including the DSP can be reduced, and in particular, the color filter array 30 for color coding using the W filter can be contributed.

[1-3. Specific example of color coding of color filter array]
Next, a specific example of color coding that facilitates conversion from a signal corresponding to a color array in which the main component of the luminance signal is arranged in a checkered pattern to a signal corresponding to the RGB Bayer array will be described.

(First example)
FIG. 4 is a color arrangement diagram showing color coding according to the first specific example. As shown in FIG. 4, in the color coding according to the first specific example, the W filters having the highest output level are arranged in a checkered pattern, the R / B filters are in a checkered arrangement with a vertical and horizontal pixel pitch, and R The / B filters are diagonally shifted by one pixel, and the rest are G filters.

  Specifically, the W filters are arranged in a checkered pattern when the vertical 4 pixels and the horizontal 4 pixels are used as a unit. The R filter is arranged in the first column of the second row and the third column of the fourth row, and the B filter is arranged in the second column of the first row and the fourth column of the third row. This arrangement is a checkered arrangement with a vertical and horizontal two-pixel pitch. Then, G filters are arranged at the remaining pixel positions. At this time, the G filter has an oblique stripe arrangement.

(Second specific example)
FIG. 5 is a color arrangement diagram showing color coding according to the second specific example. As shown in FIG. 5, in the color coding according to the second specific example, the W filters are arranged in a checkered pattern, the R / B filters are arranged in a square with a vertical and horizontal pixel pitch of 4 pixels, and the R / B filters are interleaved. Is one pixel shift, and the rest is a G filter.

  Specifically, the W filters are arranged in a checkered pattern when the vertical 4 pixels and the horizontal 4 pixels are used as a unit. The R filter is arranged in the third column of the second row, and the B filter is arranged in the second column of the third row. This arrangement is a square arrangement with a vertical and horizontal 4-pixel pitch. Then, G filters are arranged at the remaining pixel positions. At this time, the G filter has an oblique stripe arrangement.

(Third example)
FIG. 6 is a color arrangement diagram showing color coding according to the third specific example. As shown in FIG. 6, in the color coding according to the third specific example, the W filters are arranged in a checkered pattern, the R / B filters are arranged in a square with a vertical and horizontal 4 pixel pitch, and the R / B filters are arranged between the R / B filters. Is an oblique two-pixel shift, and the rest is a G filter.

  Specifically, the W filters are arranged in a checkered pattern when the vertical 4 pixels and the horizontal 4 pixels are used as a unit. The R filter is arranged in the first column of the second row, and the B filter is arranged in the third column of the fourth row. This arrangement is a square arrangement with a vertical and horizontal 4-pixel pitch. Then, G filters are arranged at the remaining pixel positions. At this time, the G filter has an oblique stripe arrangement.

(Fourth specific example)
FIG. 7 is a color arrangement diagram showing color coding according to the fourth specific example. As shown in FIG. 7, in the color coding according to the fourth specific example, the W filters are arranged in a checkered pattern, the R / B filters are arranged in a checkered pattern with a vertical and horizontal pixel pitch, and between the R / B filters. Is an oblique two-pixel shift, and the rest is a G filter.

  Specifically, the W filters are arranged in a checkered pattern when the vertical 4 pixels and the horizontal 4 pixels are used as a unit. The R filter is arranged in the second column of the first row and the fourth column of the third row, and the B filter is arranged in the second column of the third row and the fourth column of the first row. This arrangement is a checkered arrangement with a vertical and horizontal two-pixel pitch. Then, G filters are arranged at the remaining pixel positions.

(Fifth example)
FIG. 8 is a color arrangement diagram showing color coding according to the fifth specific example. As shown in FIG. 8, in the color coding according to the fifth specific example, the W filters are arranged in a checkered pattern, the R / B filters are arranged in a square with a vertical and horizontal 2 pixel pitch, and between the R / B filters. Is one pixel misalignment.

  Specifically, the W filters are arranged in a checkered pattern when the vertical 4 pixels and the horizontal 4 pixels are used as a unit. The R filter is arranged in the first and third columns of the second and fourth rows, and the B filter is arranged in the second and fourth columns of the first and third rows. This arrangement is a square arrangement with a vertical and horizontal two-pixel pitch.

(Sixth example)
FIG. 9 is a color arrangement diagram showing color coding according to the sixth specific example. As shown in FIG. 9, in the color coding according to the sixth specific example, the W filters are arranged in a checkered pattern, the R / B filters are arranged in a square with a vertical and horizontal 4 pixel pitch, and between the R / B filters. Are arranged in units of two pixels in an oblique direction, and the rest is a G filter.

  Specifically, the W filters are arranged in a checkered pattern when the vertical 4 pixels and the horizontal 4 pixels are used as a unit. The R filter is arranged in the fourth column of the third row and the third column of the fourth row, and the B filter is arranged in the second column of the first row and the first column of the second row. This arrangement is a square arrangement with a vertical and horizontal 4-pixel pitch. Then, G filters are arranged at the remaining pixel positions. At this time, the G filter has an oblique stripe arrangement.

  Each of the color codings according to the first to sixth specific examples described above has a color arrangement in which W filters are arranged in a checkered pattern as a color filter that is a main component of a luminance signal having the highest output level. Since the W filter is arranged in a checkered pattern, the W filter includes R / G / B color components, so that the conversion accuracy into a signal corresponding to the RGB Bayer array can be improved.

  In these color codings, when a W filter pixel is replaced with a G filter in a color conversion process described later, each R / B filter matches a part of the position of each R / B filter in the Bayer array. It has the feature. For missing portions that do not match, it can be said that the conversion efficiency is very good because the information of each pixel of R / B can be restored by using the information of the pixel of the W filter.

  Further, in the color coding according to the first to third specific examples and the sixth specific example, the W filter is arranged in a checkered pattern, and a part of the G filter is arranged in a diagonal stripe form in units of four pixels. It is characterized by that. In this color coding, the luminance signal amount can be increased by adding the signal of the G filter pixel adjacent to the pixel of the W filter to the signal of the pixel of the W filter to be the main component of the luminance signal. The sensitivity (S / N) can be improved.

  In particular, in the case of color coding according to the first specific example, the R / B filters are arranged in a checkered pattern with two vertical and horizontal pixel pitches, and the R / B filters are shifted one pixel diagonally. The conversion efficiency into signals corresponding to the Bayer array can be increased. In the case of color coding according to the second specific example, the R / B filters are arranged in a square arrangement with a vertical and horizontal pixel pitch of 4 pixels, and the R / B filters are arranged in an arrangement shifted by one diagonal pixel. Efficiency can be kept high. In the case of color coding according to the second specific example, since there are many G filters, the conversion efficiency of G can be increased.

  In the color coding according to the first and sixth specific examples, the G filters are arranged in stripes in units of four pixels in an oblique direction. Therefore, in the case of these color codings, one or two G pixel signals adjacent to the W pixel are added to the signal of the W pixel and used as a main component of the luminance signal in the color conversion processing described later. Thus, high sensitivity (high S / N) can be realized while suppressing a decrease in resolution. This effect is not limited to the case where the G filters are arranged in stripes in units of 4 pixels in the oblique direction, but the same applies to cases where the G filters are arranged in stripes in units of 4 pixels in the vertical or horizontal direction. I can say.

(Seventh example)
FIG. 10 is a color arrangement diagram showing color coding according to the seventh specific example. As shown in FIG. 10, in the color coding according to the seventh specific example, the G filter is arranged in a checkered pattern as a color filter that is a main component of the luminance signal, and each R / B filter is in a checkered arrangement with a vertical and horizontal pixel pitch. In addition, the R / B filters are diagonally shifted by two pixels, and the rest are W filters.

  Specifically, the G filters are arranged in a checkered pattern when the vertical 4 pixels and the horizontal 4 pixels are used as a unit. The R filter is arranged in the first column of the first row and the third column of the third row, and the B filter is arranged in the third column of the first row and the first column of the third row. This arrangement is a checkered arrangement with a vertical and horizontal two-pixel pitch. Then, W filters are arranged at the remaining pixel positions.

  The color coding according to the first to seventh specific examples described above has a configuration in which W filters or G filters are arranged in a checkered pattern as color filters that are main components of luminance signals. However, color coding that can be easily converted into a signal corresponding to the RGB Bayer array by the conversion processing unit 16 on the sensor chip 11 is not limited to a configuration in which W filters or G filters are arranged in a checkered pattern. Hereinafter, color coding in which the W filter or the G filter is not arranged in a checkered manner will be described as an eighth specific example and a ninth specific example.

(Eighth specific example)
FIG. 11 is a color arrangement diagram showing color coding according to the eighth example. As shown in FIG. 11, the color coding according to the eighth specific example is configured by WRGB filters for every 2 × 2 pixels, and has an array of vertical and horizontal 2 pixel pitches. Specifically, the W filter is arranged in an even column of an even row, the R filter is arranged in an odd column of an even row, the G filter is arranged in an odd column of an odd row, and the B filter is arranged in an even column of an odd row. Has been placed.

(Ninth example)
FIG. 12 is a color arrangement diagram showing color coding according to the ninth specific example. As shown in FIG. 12, in the color coding according to the ninth specific example, the RGB filters are in the same color Bayer array in units of 2 × 2 pixels. Specifically, the G filter is arranged in the first row, the first row of the second row, the second row and the third row, the fourth row, the third row, the fourth row, and the B filter is placed in the first row. The second row is arranged in the third column and the fourth column, and the R filter is arranged in the first row and the second row of the third row and the fourth row.

[1-4. W: G: R: B sensitivity ratio]
Here, the sensitivity ratio of W: G: R: B will be described. In color coding including a W filter, pixels of the W filter having a high output signal level are saturated earlier than pixels of other color filters. Therefore, by reducing the sensitivity of the pixels of the W filter and relatively increasing the sensitivity of the pixels of the other color filters, the sensitivity of each W: G: R: B pixel is balanced, that is, W: G: It is necessary to adjust the sensitivity ratio of each pixel of R: B.

  A known exposure control technique can be used to adjust the sensitivity ratio. Specifically, there is a technique for balancing the amount of incident light among pixels of each color by adjusting the size of an on-chip microlens provided in units of pixels outside the color filter array 30 (for example, Japanese Patent Laid-Open No. Hei 9- 116127). Utilizing this technology, the size of the on-chip microlens of the W pixel is made smaller than that of the other color pixels, thereby reducing the sensitivity of the W filter pixels and relatively increasing the sensitivity of the other color filter pixels. be able to.

  As another exposure control technique, in color coding including a W filter, there is a technique for reducing the sensitivity difference by eliminating the on-chip microlens of the W pixel and at the same time increasing the color sensitivity to improve the color S / N. (For example, refer to JP 2007-287891 A). By utilizing this technique, it is possible to reduce the sensitivity of the pixels of the W filter and relatively increase the sensitivity of the pixels of the other color filters.

  In addition, there is a technique for preventing color balance from being lost by performing shutter exposure control that shortens the exposure time of the G filter pixels as compared to the exposure time of the R / B filter pixels (for example, see Japanese Patent Application Laid-Open (JP-A)). 2003-60992 gazette). Combining this shutter exposure control technique with the control of the light receiving area can also reduce the sensitivity of the pixels of the W filter and relatively increase the sensitivity of the pixels of other color filters. The coloring of can be eliminated. As a result, an achromatic process in an external signal processor (DSP) is not necessary.

  The exposure control technique used for adjusting the sensitivity ratio mentioned here is merely an example, and is not limited to the above three examples.

  Here, an example of the size proposal when the size of the former W pixel on-chip microlens is adjusted will be described. The approximate ratio of the output level of each pixel of W / G / B / R is W: G: B: R = 2: 1: 0.5: 0.5.

  For the on-chip microlens of W pixel, the area difference is doubled by ± 0.1 μm sizing with 1.1 μm pixel, so the output level of W pixel is equal to G pixel at the same size with double sensitivity difference Can be completely corrected to the same level. Even if the size is 1.1 μm and ± 0.05 μm sizing, the area difference is 1.42 times, so the sensitivity difference can be reduced to 1.42 times. At this time, the remaining difference (sensitivity difference) may be corrected together with the shutter exposure control.

[1-5. Color conversion process]
Next, details of a process (color conversion process) for converting into a signal corresponding to the RGB Bayer array by the color conversion process by the conversion processing unit 16 will be described.

  Regarding color conversion processing, color conversion processing at the time of still image imaging (at the time of full scanning) that scans all pixels and color conversion processing at the time of video imaging (at the time of pixel addition) that adds the signals of a plurality of adjacent pixels Divided. In the case of the color coding according to the first specific example and the sixth specific example, as described above, it is a color conversion process capable of realizing high sensitivity, and a low illumination mode can be adopted. The color conversion process can be divided into two color conversion processes.

  One of the two color conversion processes is a color conversion process at a time of high luminance in which the incident light luminance is higher than a predetermined reference luminance, and this is referred to as color conversion processing 1. The other is color conversion processing at low luminance below the reference luminance, which is referred to as color conversion processing 2. Also, the color conversion process at the time of pixel addition can be divided into a plurality of color conversion processes depending on the difference in the combination of pixels to be added.

  Note that the color conversion processing at the time of full scanning in the case of color coding according to specific examples other than the first and sixth specific examples cannot take the low illuminance mode, so only the high illuminance mode is adopted. . That is, the color conversion processing at the time of full scanning in the case of color coding according to the second to fifth specific examples and the seventh to ninth specific examples is performed at the time of high luminance in the case of color coding according to the first and sixth specific examples. The color conversion process 1 of FIG.

(In the case of color coding according to the first specific example)
First, color conversion processing in the case of color coding according to the first specific example will be described. First, the color conversion process 1 at the time of high brightness at the time of full scan will be described using the flowchart of FIG. 13 and the conceptual diagram of FIG.

  As shown in the flowchart of FIG. 13, the color conversion process 1 at the time of high luminance is basically realized by sequentially executing the processes of step S11, step S12, and step S13. FIG. 14A shows a color arrangement of 4 × 4 pixels of color coding according to the first specific example.

  In step S11, as shown in FIG. 14B, processing for expanding checkered white (W) pixel components into pixels of all colors by determining the directionality of the resolution is performed. Here, the direction of resolution means the direction in which the pixel signal exists. In FIG. 14B, W indicated by a white square (□) represents a W pixel component developed for each color.

  In developing the W pixel component to all other color pixels, signal processing using a well-known directional correlation can be used. As a signal processing technique using this directional correlation, for example, a plurality of color signals corresponding to a specific pixel are obtained, and the correlation values in the vertical direction and / or the horizontal direction at the position corresponding to the specific pixel are obtained. Examples of the technology to be obtained (for example, see Japanese Patent No. 2931520).

  In step S12, as shown in FIG. 14C, the W pixel is replaced with the G pixel from the correlation between the W pixel and the G pixel. As is clear from the color arrangement of the various color codings described above, the W pixel and the G pixel are adjacent to each other. Looking at the correlation between the W pixel and the G pixel in a certain region, both are colors that are the main components of the luminance signal, and thus have a fairly strong correlation, and the correlation value (correlation coefficient) is close to 1. By determining the directionality of the resolution using this color correlation and changing the output level of the W pixel to a level equivalent to the G pixel, the W pixel can be replaced with the G pixel.

  In step S13, Bayer R / B pixels shown in FIG. 14D are generated from the correlation between the W pixel and the R / B pixels. Since the W filter includes R / G / B color components, the W pixel and the R / B pixels can be correlated. For this signal processing, a well-known technique (for example, see Japanese Patent Application Laid-Open No. 2005-160044) that interpolates the luminance signal substituted for G in all the pixels in the four color arrangement can be used.

  Next, the color conversion process 2 at the time of low brightness during full scan will be described with reference to the flowchart of FIG. 15 and the conceptual diagram of FIG.

  First, the directionality of the resolution is observed as shown in FIG. 16A by using the signal processing using the well-known directional correlation described above (step S21). Then, it is determined whether or not the directionality can be determined (step S22). If the directionality can be determined, the checkered W pixel components are developed into pixels of all colors (step S23).

  Next, by using the above-described well-known technique, as shown in FIG. 16B, each R / B pixel is generated from the correlation between the W pixel and each R / B pixel (step S24). Next, as shown in FIG. 16C, the signal of the two R pixels adjacent to the W pixel is added to the signal of the W pixel and approximated to G (= W + 2G). As shown, each pixel of the Bayer R / B is generated (step S25).

  If the directionality cannot be determined in step S22, each pixel of the Bayer R / B is generated by simple four-pixel equal interpolation that complements equally between four pixels that are vertically and horizontally adjacent (step S26).

  As described above, by using the color conversion processing 1 or the color conversion processing 2 according to the luminance of incident light, a signal corresponding to a color array in which W filters are arranged in a checkered pattern is converted into a signal corresponding to an RGB Bayer array. Can be converted and output on the sensor chip 11.

  Next, two color conversion processes at the time of pixel addition during moving image capturing will be described. These two color conversion processes are referred to as pixel addition process 1 and pixel addition process 2.

  First, pixel addition processing 1 will be described with reference to the flowchart of FIG. 17 and the conceptual diagram of FIG.

  First, with respect to the W pixel, addition processing is performed between two pixels positioned in the oblique direction (step S31). Specifically, as shown in FIG. 18A, addition is performed between the pixel of interest and a pixel located diagonally to the lower right of the pixel of interest (a pixel on the right next to one column and one row below). For the addition of the W pixel, in the pixel configuration shown in FIG. 3, the transfer pulse φTRF is simultaneously applied to the transfer transistors 22 of the two pixels to be added, in this example, the transfer transistors 22-1 and 22-4. In the FD unit 26, two-pixel addition can be performed. This pixel addition is called FD addition.

  Next, for each pixel of R / G / B, interlaced addition is performed between two pixels located in an oblique direction opposite to the case of the W pixel (step S32). Specifically, as shown in FIG. 18B, interlaced addition is performed between the pixel of interest and a pixel located diagonally to the left of the pixel of interest (pixels adjacent to the left of two columns and two rows below). As for the addition of the R / G / B pixels, for example, when the column processing unit 14 shown in FIG. 1 has an A / D conversion function, the interlaced addition can be performed at the time of the A / D conversion.

  More specifically, in the color arrangement shown in FIG. 19, the signals of the B1 and G1 pixels are read out independently, and after these signals are A / D converted, the signals of the B2 and G3 pixels are read out continuously. Two-pixel addition can be performed by performing A / D conversion. As a technique for performing pixel addition at the time of A / D conversion in the column processing unit 14, a known technique for converting an analog pixel signal into a digital pixel signal using a counter (for example, JP-A-2006-033454) Reference) can be used.

  A process of performing pixel addition using a counter that constitutes a part of the A / D conversion unit is referred to as counter addition. If the gain is changed for each line when performing this counter addition, the addition ratio can be made variable. Counter addition can be performed in the same manner for the R pixel. Incidentally, in the above-described two-pixel addition for the W pixel, FD addition is performed between the pixels W1 and W2 and between the pixels W3 and W4.

  Next, as shown in FIG. 18C, the component of the W pixel is fitted to each pixel of R / G / B (step S33). Next, as shown in FIG. 18D, four pixels of the RGB Bayer array are generated (step S34).

  Next, the pixel addition process 2 will be described using the flowchart of FIG. 20 and the conceptual diagram of FIG.

  First, for the W pixel and the G pixel, W / R / G / B is generated by performing FD addition between two pixels located in the left-right diagonal direction (step S41). Specifically, as for the W pixel, as shown in FIG. 21A, between the pixel of interest and a pixel located diagonally to the lower right of the pixel of interest (a pixel on the right next to one column and one row below). FD addition is performed. As for the G pixel, as shown in FIG. 21B, FD addition is performed between the pixel of interest and a pixel located diagonally to the lower left of the pixel of interest (pixel adjacent to the left of one column and one row below).

  Here, in a total of 8 pixels of 4 vertical pixels × 4 horizontal pixels, one set of R / B signals is not used. That is, thinning readout without pixel addition is performed for each R / B pixel. Accordingly, since the sensitivity of R / B is lower than that in the case of the pixel addition processing 1, the color S / N is poor.

  Next, as shown in FIG. 21C, the W pixel component is fitted to each R / G / B pixel (step S42). Next, as shown in FIG. 21D, four pixels of the RGB Bayer array are generated (step S43). In the pixel addition process 2, the center of gravity of the RGB Bayer array is slightly shifted from that in the pixel addition process 1.

  Further, the pixel addition process 3 will be described with reference to the flowchart of FIG. 22 and the conceptual diagram of FIG.

  First, as shown in FIG. 23 (A), all pixels of WRGB are diagonally interlaced and two-pixel addition is performed (step S51). By this addition processing, as shown in FIG. 23B, a color array in which a certain row is R, W, G, W,... And a next row is W, G, W, R. Then, as in the case of the processing at the time of full scan, each pixel of the Bayer R / B shown in FIG. 23C is generated from the correlation between the W pixel and each R / B pixel (step S52).

  As described above, by using the pixel addition process 1, the pixel addition process 2, or the pixel addition process 3 at the time of moving image capturing, a signal corresponding to a color array in which a W filter is arranged in a checkered pattern corresponds to an RGB Bayer array. Signals can be converted and output on the sensor chip 11.

  In the following, color conversion processing in the case of color coding according to the second to ninth specific examples will be described. In many cases, the flow of a series of processing is generally based on the case of color coding according to the first specific example. It is said.

(In the case of color coding according to the second specific example)
First, color conversion processing during full scanning will be described with reference to the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the second specific example shown in FIG. 24A, looking at the directionality of the resolution, as shown in FIG. Expands to all color pixels. Next, from the correlation between the W pixel and the G pixel, the W pixel is replaced with the G pixel as shown in FIG. Then, from the correlation between the W pixel and each R / B pixel, each Bayer R / B pixel shown in FIG. 24D is generated.

  Next, pixel addition processing will be described using the conceptual diagram of FIG. First, as shown in FIGS. 25A and 25B, for W and G pixels, W / R / G / B is generated by performing FD addition between two pixels positioned diagonally in the left and right direction. . Then, as shown in FIG. 25C, the W pixel component is fitted to each R / G / B pixel to generate four pixels in the RGB Bayer array shown in FIG.

(In the case of color coding according to the third specific example)
First, color conversion processing during full scanning will be described with reference to the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the third specific example shown in FIG. 26 (A), the directionality of the resolution is seen, and as shown in FIG. Expands to all color pixels. Next, from the correlation between the W pixel and the G pixel, the W pixel is replaced with the G pixel as shown in FIG. Then, from the correlation between the W pixel and each R / B pixel, each Bayer R / B pixel shown in FIG. 26D is generated.

  Next, pixel addition processing will be described using the conceptual diagram of FIG. First, as shown in FIGS. 27 (A) and 27 (B), W / Cy (cyan) / G / Ye (yellow) is performed by performing left-right diagonal FD addition for each pixel of W / R / G / B. Is generated. Next, as shown in FIG. 27C, a Bayer array is generated by calculation processing of B = W−Ye and R = W−Cy. At this time, although the S / N of B / R is deteriorated by the subtraction process, the color reproducibility is improved. Then, as shown in FIG. 27D, the W pixel component is fitted to each R / G / B pixel to generate four pixels of the RGB Bayer array shown in FIG.

(In the case of color coding according to the fourth example)
First, color conversion processing during full scanning will be described with reference to the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the fourth specific example shown in FIG. 28A, the directionality of the resolution is seen, and as shown in FIG. Expands to all color pixels. Next, from the correlation between the W pixel and the G pixel, the W pixel is replaced with the G pixel as shown in FIG. Then, each pixel of the Bayer R / B shown in FIG. 28D is generated from the correlation between the W pixel and each of the R / B pixels.

Regarding the pixel addition processing, four processing methods are conceivable. The first pixel addition process will be described with reference to the conceptual diagram of FIG. First, as shown in FIGS. 29A and 29B, for the W pixel, addition is performed between two diagonal pixels, and for each R / B pixel, G and pixel addition are performed between the two diagonal pixels. / Cy / Ye is generated. Next, as shown in FIG. 29C, looking at the directionality of the resolution, each component of Cy / Ye is developed to all pixels. Next, as shown in FIG. 29D, calculation processing of G = Cy + Ye-W, B = W-Ye, and R = W-Cy is performed. Then, as shown in FIG. 29E, the W pixel component is fitted to each R / G / B pixel to generate four pixels in the RGB Bayer array shown in FIG.

  Next, the second pixel addition process will be described with reference to the conceptual diagram of FIG. First, as shown in FIG. 30 (A), two-pixel addition is performed on the R / B pixels by diagonally jumping left and right. For the G pixel, the center G pixel and the average value of the four G pixels on the top, bottom, left, and right of the center pixel are combined. For W pixels, diagonal FD addition is performed as shown in FIG. Then, as shown in FIG. 30C, the W pixel component is fitted to each R / G / B pixel to generate four pixels of the RGB Bayer array shown in FIG.

  Next, the third pixel addition process will be described using the conceptual diagram of FIG. First, as shown in FIG. 31A, addition is performed between two diagonally adjacent pixels for W pixels, and two pixels are diagonally interlaced for RGB. Thereby, a color arrangement as shown in FIG. 31B is obtained. Then, the W pixel component is fitted to each R / G / B pixel to generate four pixels in the RGB Bayer array shown in FIG.

  Finally, the fourth pixel addition process will be described with reference to the conceptual diagram of FIG. First, as shown in FIG. 32 (A), two pixels are added diagonally with respect to WRGB. Next, a W checkered color array shown in FIG. 32B is obtained by synthesizing the W pixel signals of the cross checkered array. Next, as in the case of the processing at the time of full scan, the W pixel is replaced with the G pixel as shown in FIG. 32C from the correlation between the W pixel and the G pixel. Then, from the correlation between the W pixel and each R / B pixel, each Bayer R / B pixel shown in FIG. 32D is generated.

(In the case of color coding according to the fifth example)
First, color conversion processing during full scanning will be described with reference to the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the fifth specific example shown in FIG. 33A, the directionality of the resolution is seen, and as shown in FIG. Expands to all color pixels. Next, from the correlation between the W pixel and each R / B pixel, the components of each R / B pixel are expanded to all pixels as shown in FIG. Then, the component of the W pixel after the calculation processing of G = W−R−B is fitted to each pixel to generate four pixels of the RGB Bayer array shown in FIG.

  Next, pixel addition processing will be described using the conceptual diagram of FIG. First, as shown in FIG. 34 (A), the signals of the respective pixels are added with the R / G / B centroids aligned, and then the calculation process of G = W−R−B is performed. G pixels are generated as shown in B). Next, as shown in FIG. 34C, four pixels are added in the diagonal direction for the B pixel, and five pixels are added for the upper, lower, left, and right for the R pixel, thereby generating each pixel of R / B. Finally, four pixels of the RGB Bayer array shown in FIG. 34D are generated.

(In the case of color coding according to the sixth example)
First, the color conversion process 1 at the time of full scan will be described using the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the sixth specific example shown in FIG. 35A, looking at the directionality of the resolution, as shown in FIG. Expands to all color pixels. Next, from the correlation between the W pixel and the G pixel, the W pixel is replaced with the G pixel as shown in FIG. Then, each pixel of the Bayer R / B shown in FIG. 35D is generated from the correlation between the W pixel and each of the R / B pixels.

  Next, the color conversion processing 2 at the time of full scan will be described using the conceptual diagram of FIG. As in the case of the color conversion process 1, in the color arrangement of 4 × 4 pixels of color coding according to the sixth specific example, the directionality of the resolution is seen, and as shown in FIG. Are expanded to pixels of all colors. From the correlation between the W pixel and each R / B pixel, each R / B pixel is generated as shown in FIG. Next, as shown in FIG. 36C, two G pixel signals adjacent to the W pixel are added to the W pixel signal to approximate G (= W + 2G), as shown in FIG. 36D. Next, each pixel of the Bayer R / B is generated. At this time, if there is directionality, the addition ratio may be changed to active.

  Subsequently, the pixel addition process 1 will be described with reference to FIG. As shown in FIGS. 37A and 37B, W / R / G / B pixels are generated by performing left-right diagonal FD addition on the W pixels and R / G / B pixels. Then, as shown in FIG. 37C, the W pixel component is fitted to each pixel to generate four pixels in the RGB Bayer array shown in FIG.

  Next, the pixel addition process 2 will be described with reference to FIG. As shown in FIGS. 38A and 38B, W / R / G / B pixels are generated by performing left-right diagonal FD addition on the W pixels and R / G / B pixels. Then, as shown in FIG. 38C, the W pixel component is fitted to each R / B pixel to generate four pixels in the RGB Bayer array shown in FIG.

(In the case of color coding according to the seventh example)
First, color conversion processing during full scanning will be described with reference to the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the seventh specific example shown in FIG. 39A, the directionality of the resolution is seen, and as shown in FIG. It develops to each pixel of R / B. Next, from the correlation between the W pixel and each R / B pixel, the W pixel is replaced with each R / B pixel as shown in FIG. Then, four pixels of the RGB Bayer array shown in FIG. 39D are generated.

  Next, pixel addition processing will be described using the conceptual diagram of FIG. First, as shown in FIG. 40 (A), 2R / 2B is generated as shown in FIG. 40 (B) by performing left-right diagonally jump addition for each R / B pixel. Next, as shown in FIG. 40 (C), 4G is generated as shown in FIG. 40 (D) by performing diagonal rhombus addition on the G pixel. Then, by adding Gw / Rw / Bw from the correlation between the W pixel and each of the R / G / B pixels, four pixels of the RGB Bayer array shown in FIG. 40E are generated.

(In the case of color coding according to the eighth example)
First, color conversion processing during full scan will be described with reference to the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the eighth specific example shown in FIG. 41A, looking at the directionality of the resolution, as shown in FIG. 41B, each G / W pixel is checked. Expands into a shape. Next, as shown in FIG. 41C, the W pixel component is fitted to the G pixel to generate four pixels in the RGB Bayer array shown in FIG.

  Next, pixel addition processing will be described using the conceptual diagram of FIG. First, as shown in FIG. 42A, the G / W centroids are matched and the signals of these pixels are added. Next, as shown in FIG. 42B, the component of the W pixel is fitted to the G pixel to generate G = G + Gw. Next, as shown in FIG. 42 (C), four pixels in the diagonal direction are added to the B pixel, and five pixels in the vertical and horizontal directions are added to the R pixel, so that the four pixels in the RGB Bayer array shown in FIG. 42 (D) are obtained. Generate.

(In the case of color coding according to the ninth example)
First, color conversion processing during full scanning will be described with reference to the conceptual diagram of FIG. In the color arrangement of 4 × 4 pixels of color coding according to the ninth specific example shown in FIG. 43 (A), the direction of the resolution is seen, and as shown in FIG. It expands to each pixel. Next, four pixels of the RGB Bayer array shown in FIG. 42C are generated from the correlation between the G pixel and each R / B pixel.

  Next, pixel addition processing will be described with reference to the conceptual diagram of FIG. First, as shown in FIG. 44A, FD addition is performed for signals of a total of 4 pixels of 2 × 2 pixels of the same color that are adjacent vertically and horizontally. Finally, four pixels of the RGB Bayer array shown in FIG. 44B are generated.

<2. Application example> [Imaging device]
FIG. 45 is a block diagram showing an example of the configuration of the imaging apparatus according to the present invention.

As shown in FIG. 45, an imaging apparatus 100 according to the present invention includes an optical system including a lens group 101 and the like, an imaging element 102, a DSP circuit 103 which is a camera signal processing circuit, a frame memory 104, a display apparatus 105, and a recording apparatus 106. The operation system 107 and the power supply system 108 are included.
The DSP circuit 103, the frame memory 104, the display device 105, the recording device 106, the operation system 107, and the power supply system 108 are connected to each other via a bus line 109.

  The lens group 101 captures incident light (image light) from a subject and forms an image on the imaging surface of the imaging element 102. The imaging element 102 converts the amount of incident light imaged on the imaging surface by the lens group 101 into an electrical signal in units of pixels and outputs the electrical signal. As the image sensor 102, the CMOS image sensor 10 according to the above-described embodiment is used.

  The CMOS image sensor 10 has a color coding array of color coding in which colors that are main components of a luminance signal are arranged in a checkered pattern and a plurality of colors that are color information components are arranged in the remaining portion as a color filter array. doing. The CMOS image sensor 10 is configured to convert a signal corresponding to the color array of the color filter array into a signal corresponding to the Bayer array by arithmetic processing.

  Therefore, the CMOS image sensor 10 outputs a signal corresponding to the Bayer array while the color filter array is color coding in which the main color of the luminance signal is arranged in a checkered pattern. As a result, the DSP circuit 103 has an existing process for generating the luminance signal Y and the two color difference signals U (B−Y) and V (R−Y) based on signals corresponding to the Bayer array. DSPs for Bayer arrays can be used.

  As described above, since the existing Bayer array DSP can be used, even if the color coding of the color filter array used in the image sensor 102 is changed, it is not necessary to newly develop a DSP that requires enormous development costs. . Thereby, it is possible to contribute to the cost reduction of the imaging apparatus 100 including the DSP circuit 103 and the spread of the color coding color filter array using the W filter.

  The display device 105 includes a panel type display device such as a liquid crystal display device or an organic EL (electroluminescence) display device, and displays a moving image or a still image captured by the image sensor 102. The recording device 106 records a moving image or a still image captured by the image sensor 102 on a recording medium such as a video tape or a DVD (Digital Versatile Disk).

  The operation system 107 issues operation commands for various functions of the imaging apparatus under operation by the user. The power supply system 108 appropriately supplies various power supplies serving as operation power supplies for the DSP circuit 103, the frame memory 104, the display device 105, the recording device 106, and the operation system 107 to these supply targets.

  DESCRIPTION OF SYMBOLS 10 ... CMOS image sensor, 11 ... Semiconductor substrate (sensor chip), 12 ... Pixel array part, 13 ... Vertical drive part, 14 ... Column processing part, 15 ... Horizontal drive part, 16 ... Conversion part, 17 ... System control part, DESCRIPTION OF SYMBOLS 20 ... Unit pixel, 21 ... Photodiode, 22 ... Transfer transistor, 23 ... Reset transistor, 24 ... Amplification transistor, 25 ... Selection transistor, 26 ... FD (floating diffusion) part, 30 ... Color filter array (color filter part)

Claims (22)

Pixels are provided on a pixel array section that is two-dimensionally arranged in a matrix, white filters corresponding to the color that is the main component of the luminance signal are arranged in a checkered pattern, and each of the red and blue filters has a vertical and horizontal pixel pitch of 2 pixels. A color filter section having a checkered arrangement, a diagonal two-pixel shift between each of the red and blue filters, and the rest being a green filter;
A conversion processing unit that is provided on the same substrate as the pixel array unit and converts a signal corresponding to the color array of the color filter unit output from each pixel of the pixel array unit into a signal corresponding to the Bayer array and outputs the converted signal. When,
With
The conversion processing unit performs addition between the two pixels of the same color with one pixel skipping diagonally with respect to the red and blue pixel signals at the time of moving image capturing, and generates a pixel signal of each color of the Bayer array using the pixel signal after the addition. Solid-state imaging device. The solid-state imaging device according to claim 1, wherein the conversion processing unit generates a pixel signal of each color of the Bayer array without performing addition between the two pixels of the same color when capturing a still image. In the Bayer array conversion at the time of still image capturing, the conversion processing unit replaces the white pixel signal with the green pixel signal from the correlation between the white pixel signal and the green pixel signal within the 4 × 4 pixel group, The solid-state imaging device according to claim 2, wherein a new red pixel signal is generated from a correlation between signals of the pixel and the red pixel, and a new blue pixel signal is generated from a correlation between the signals of the white pixel and the blue pixel. In the Bayer array conversion at the time of moving image capturing, the conversion processing unit synthesizes a signal with a central pixel and an average value of four pixels, upper, lower, left, and right for a green pixel, and diagonally 1 for each of red and blue pixels. Signal addition is performed between two pixels of the same color with inter-pixel skipping, and for white pixels, signal addition is performed between two diagonally adjacent pixels to generate green, red, blue and white pixel signals, and the generated green The solid-state imaging device according to any one of claims 1 to 3, wherein a pixel signal of each color in the Bayer array is generated by fitting a white pixel signal component to a pixel signal of each color of red, blue, and blue. In the Bayer array conversion at the time of moving image capturing, the conversion processing unit performs signal addition between two pixels of the same color, which is skipped by one diagonal pixel for each of green, red, and blue pixels, and two diagonally adjacent pixels for white pixels By adding signals between them, green, red, blue and white pixel signals are generated, and by fitting white pixel signal components to the generated green, red and blue pixel signals, the Bayer array The solid-state imaging device according to claim 1, wherein a pixel signal for each color is generated. In the Bayer array conversion at the time of moving image capturing, the conversion processing unit performs signal addition between two pixels of the same color with one pixel jumping diagonally for each pixel of green, red, blue, and white, and alternately arranges white pixels and green pixels A color array in which a red pixel and a blue pixel are alternately arranged between every other pixel line and every other white pixel is obtained, and the white pixel is a checkered pattern. The white pixel signal is replaced with the green pixel signal from the correlation between the signal of the pixel and the green pixel, and a new red pixel signal is generated from the correlation between the signal of the white pixel and the red pixel. The solid-state imaging device according to any one of claims 1 to 3, wherein a new blue pixel signal is generated from the correlation between the signals. Pixels are provided on a pixel array section that is two-dimensionally arranged in a matrix, white filters corresponding to the color that is the main component of the luminance signal are arranged in a checkered pattern, and each of the red and blue filters has a vertical and horizontal pixel pitch of 2 pixels. A color filter section having a checkered arrangement, a diagonal two-pixel shift between each of the red and blue filters, and the rest being a green filter;
A conversion processing unit that is provided on the same substrate as the pixel array unit and converts a signal corresponding to the color array of the color filter unit output from each pixel of the pixel array unit into a signal corresponding to the Bayer array and outputs the converted signal. When,
With
The conversion processing unit, in the Bayer array conversion during moving image by performing an addition of pixel signals between white diagonal two pixels to generate a white pixel signal, blue and green pixel signals, red and green pixels signals, respectively, by adding between the white pixel signal at the time of addition of the different directions oblique two pixels to generate un, pixel signals of yellow, said and one or the total pixel signal of cyan and yellow Subtracting the generated white pixel signal to generate green, blue and red pixel signals, and fitting the white pixel signal component to the generated pixel signals of each color, the pixels of each color of the Bayer array Generate signal
Solid-state image sensor. The pixel array unit includes a pixel between two pixels that are obliquely adjacent to each other, a green pixel, and a red or blue pixel, and a photoelectric conversion unit for each pixel through a transfer transistor for each pixel. The solid-state imaging device according to any one of claims 1 to 7, wherein one charge storage unit to which signal charges are transferred is shared. On the pixel array section in which the pixels are two-dimensionally arranged in a matrix, white filters corresponding to the color that is the main component of the luminance signal are arranged in a checkered pattern, and the red and blue filters are arranged in a checkered pattern with vertical and horizontal pixel pitches. And, in the signal processing of the solid-state imaging device having a color filter portion in which the red and blue filters are diagonally shifted by two pixels and the remaining is a green filter,
In Bayer array conversion processing for converting a signal corresponding to the color array of the color filter unit output from each pixel of the pixel array unit into a signal corresponding to the Bayer array on the same substrate as the pixel array unit, moving image imaging Sometimes a signal processing method for adding red pixel signals between two pixels of the same color with one pixel skipping diagonally. The signal processing method according to claim 9, wherein the conversion processing unit generates a pixel signal of each color of the Bayer array without performing addition between the two pixels of the same color when capturing a still image. In the Bayer array conversion process at the time of still image capturing, the white pixel signal is replaced with the green pixel signal from the correlation between the white pixel signal and the green pixel signal in the 4 × 4 pixel group, and the white pixel and the red pixel The signal processing method according to claim 10, wherein a new red pixel signal is generated from the correlation between the signals and the white signal, and a new blue pixel signal is generated from the correlation between the signals of the white pixel and the blue pixel. In the Bayer array conversion process at the time of moving image capturing, a signal is synthesized with a center pixel and an average value of four pixels above, below, left, and right for a green pixel, and for each red and blue pixel, the same color with one pixel jumping diagonally. Signal addition is performed between two pixels, and for white pixels, signal addition is performed between two diagonally adjacent pixels to generate green, red, blue and white pixel signals, and the generated green, red, blue The signal processing method according to claim 9, wherein a pixel signal of each color in the Bayer array is generated by fitting a white pixel signal component to a pixel signal of each color. In the Bayer array conversion processing at the time of moving image capturing, for each pixel of green, red, and blue, signal addition is performed between two pixels of the same color that is skipped by one diagonal pixel, and for white pixels, signal addition is performed between two diagonal pixels adjacent to each other. To generate green, red, blue and white pixel signals, and by fitting white pixel signal components to the generated green, red and blue pixel signals, the pixel signals of each color of the Bayer array The signal processing method according to any one of claims 9 to 11. In the Bayer array conversion process at the time of moving image capturing, a pixel line in which white pixels and green pixels are alternately arranged by performing signal addition between two pixels of the same color, which are jumped diagonally by one pixel, for each pixel of green, red, blue, and white And a pixel line in which red pixels and blue pixels are alternately arranged between every other white pixel, a white pixel and a green pixel are obtained in the obtained color array. The white pixel signal is replaced with the green pixel signal based on the correlation between the white pixel signal and the green pixel signal, and a new red pixel signal is generated from the correlation between the white pixel and the red pixel signal. A new blue pixel signal is generated from the signal processing method according to any one of claims 9 to 11. On the pixel array section in which the pixels are two-dimensionally arranged in a matrix, white filters corresponding to the color that is the main component of the luminance signal are arranged in a checkered pattern, and the red and blue filters are arranged in a checkered pattern with vertical and horizontal pixel pitches. And, in the signal processing of the solid-state imaging device having a color filter portion in which the red and blue filters are diagonally shifted by two pixels and the remaining is a green filter,
Bayer array conversion processing at the time of moving image capturing that converts a signal corresponding to the color array of the color filter section output from each pixel of the pixel array section into a signal corresponding to the Bayer array on the same substrate as the pixel array section in, performs addition of the pixel signals between white diagonal two pixels to generate a white pixel signal, blue and green pixel signals, the red and green pixel signals, respectively, and when the pixel signal addition of the white by adding between two pixels of the oblique in different directions to produce a sheet-en, pixel signals of yellow, performing subtraction between the cyan and one or total white pixel signal pixel signal to have the generation of yellow The green, blue and red pixel signals are generated, and the pixel signal of each color in the Bayer array is generated by fitting a white pixel signal component to the generated pixel signal of each color.
Signal processing method. Pixels are provided on a pixel array section that is two-dimensionally arranged in a matrix, white filters corresponding to the color that is the main component of the luminance signal are arranged in a checkered pattern, and each of the red and blue filters has a vertical and horizontal pixel pitch of 2 pixels. A checkered arrangement, and a color filter portion in which the red and blue filters are diagonally shifted by two pixels, and the rest are green filters, and the pixel array portion is provided on the same substrate. A solid-state imaging device having a conversion processing unit that converts a signal corresponding to a color array of the color filter unit output from a pixel into a signal corresponding to a Bayer array and outputs the signal;
A signal processing unit that generates a luminance signal and a color difference signal based on a signal corresponding to the Bayer array output from the conversion processing unit;
The conversion processing unit performs addition between the two pixels of the same color with one pixel skipping diagonally with respect to the red and blue pixel signals at the time of moving image capturing, and generates a pixel signal of each color of the Bayer array using the pixel signal after the addition. Imaging device. The imaging device according to claim 16, wherein the conversion processing unit generates pixel signals of each color of the Bayer array without performing addition between the two pixels of the same color during still image capturing. In the Bayer array conversion at the time of still image capturing, the conversion processing unit replaces the white pixel signal with the green pixel signal from the correlation between the white pixel signal and the green pixel signal within the 4 × 4 pixel group, The imaging device according to claim 17, wherein a new red pixel signal is generated from a correlation between signals of pixels and red pixels, and a new blue pixel signal is generated from a correlation between signals of white pixels and blue pixels. In the Bayer array conversion at the time of moving image capturing, the conversion processing unit synthesizes a signal with a central pixel and an average value of four pixels, upper, lower, left, and right for a green pixel, and diagonally 1 for each of red and blue pixels. Signal addition is performed between two pixels of the same color with inter-pixel skipping, and for white pixels, signal addition is performed between two diagonally adjacent pixels to generate green, red, blue and white pixel signals, and the generated green The imaging device according to any one of claims 16 to 18, wherein a pixel signal of each color in the Bayer array is generated by fitting a pixel signal component of white to a pixel signal of each color of red, blue, and blue. In the Bayer array conversion at the time of moving image capturing, the conversion processing unit performs signal addition between two pixels of the same color, which is skipped by one diagonal pixel for each of green, red, and blue pixels, and two diagonally adjacent pixels for white pixels By adding signals between them, green, red, blue and white pixel signals are generated, and by fitting white pixel signal components to the generated green, red and blue pixel signals, the Bayer array The imaging device according to any one of claims 16 to 18, which generates a pixel signal of each color. In the Bayer array conversion at the time of moving image capturing, the conversion processing unit performs signal addition between two pixels of the same color with one pixel jumping diagonally for each pixel of green, red, blue, and white, and alternately arranges white pixels and green pixels A color array in which a red pixel and a blue pixel are alternately arranged between every other pixel line and every other white pixel is obtained, and the white pixel is a checkered pattern. The white pixel signal is replaced with the green pixel signal from the correlation between the signal of the pixel and the green pixel, and a new red pixel signal is generated from the correlation between the signal of the white pixel and the red pixel. The imaging device according to any one of claims 16 to 18, wherein a new blue pixel signal is generated from the correlation between the signals. Pixels are provided on a pixel array section that is two-dimensionally arranged in a matrix, white filters corresponding to the color that is the main component of the luminance signal are arranged in a checkered pattern, and each of the red and blue filters has a vertical and horizontal pixel pitch of 2 pixels. A checkered arrangement, and a color filter portion in which the red and blue filters are diagonally shifted by two pixels, and the rest are green filters, and the pixel array portion is provided on the same substrate. A solid-state imaging device having a conversion processing unit that converts a signal corresponding to a color array of the color filter unit output from a pixel into a signal corresponding to a Bayer array and outputs the signal;
A signal processing unit that generates a luminance signal and a color difference signal based on a signal corresponding to the Bayer array output from the conversion processing unit;
Comprising
The conversion processing unit, in the Bayer array conversion during moving image by performing an addition of pixel signals between white diagonal two pixels to generate a white pixel signal, blue and green pixel signals, red and green pixels signals, respectively, by adding between the white pixel signal at the time of addition of the different directions oblique two pixels to generate un, pixel signals of yellow, said and one or the total pixel signal of cyan and yellow Subtracting the generated white pixel signal to generate green, blue and red pixel signals, and fitting the white pixel signal component to the generated pixel signals of each color, the pixels of each color of the Bayer array Generate signal
Imaging device.

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