JP3977062B2 - Imaging apparatus and focus adjustment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging device capable of capturing a still image and / or a moving image with a large number of two-dimensionally configured photoelectric conversion devices, and a focus state detection method in an imaging device using the imaging device.
[0002]
[Prior art]
Conventionally, there are a phase difference detection method (referred to as a shift method) and a contrast detection method (referred to as a blur method) as a general method using a light beam that has passed through a photographing lens in an automatic focus detection / adjustment method of an image pickup device. .
[0003]
The phase difference detection method is often used in a single-lens reflex camera using a silver salt film, and is the technology that has contributed most to the practical application of an auto focus (AF) single-lens reflex camera. In the phase difference detection method, the light beam that has passed through the exit pupil of the photographic lens is divided into two, and the two divided light beams are received by a set of focus detection sensors, and the amount of deviation of the signal that is output according to the amount of received light That is, the amount of deviation of the photographing lens in the focus direction is directly obtained by detecting the amount of relative positional deviation in the beam splitting direction. Therefore, once the accumulation operation is performed by the focus detection sensor, the amount and direction of the focus shift can be obtained, and a high-speed focus adjustment operation is possible. However, in order to divide the light beam that has passed through the exit pupil of the photographic lens into two and obtain signals corresponding to the respective light beams, it is common to provide two systems for focus detection optical system and sensors, Conversion from the detected signal shift amount to the focus shift amount is also required.
[0004]
On the other hand, the contrast detection method is a method often used in video movie equipment (camcorder) for video recording and electronic still cameras. Unlike the phase difference detection method, an imaging sensor is used as a focus detection sensor. Focusing on the output signal of the image sensor, particularly information on high-frequency components (contrast information), the position of the photographing lens having the largest evaluation value is used as the in-focus position. However, as it is said to be a hill-climbing method, it is necessary to find the evaluation value while moving the photographic lens by a small amount and move it until it is determined that the evaluation value is the maximum as a result. It is said that. However, since the evaluation is performed using a signal obtained from the image sensor, a high accuracy is obtained.
[0005]
A method for realizing both of the above two methods using a line sensor for focus detection is disclosed in Japanese Patent Application Laid-Open No. 59-146010.
[0006]
Further, the present applicant has applied for a focus detection device capable of obtaining an evaluation value of a phase difference detection method while being an image sensor as Japanese Patent Application Laid-Open No. 2000-156823 and Japanese Patent Application No. 2000-117510.
[0007]
On the other hand, Japanese Patent Application Laid-Open No. 10-51672 proposes to use both focus detection systems for both types in an imaging apparatus having two shooting modes of silver salt photography and video movie.
[0008]
[Problems to be solved by the invention]
However, in Japanese Patent Laid-Open No. 2000-156823, a part of pixels of the image sensor is configured to output a focus detection signal other than for forming an image signal, that is, a phase difference detection method. However, the contrast detection method is not disclosed.
[0009]
On the other hand, in Japanese Patent Application No. 2000-117510, the detection direction in the same distance measurement area is orthogonal to each other by performing the accumulation / focus detection operation twice using both the phase difference detection method and the contrast detection method. A focus detection device is proposed. However, since accumulation is performed twice for the focus detection operation, it is not fast enough.
[0010]
In Japanese Patent Laid-Open No. 59-146919, focus adjustment is performed quickly by using both methods. However, since a sensor array dedicated to focus detection is used, the configuration of the apparatus becomes complicated.
[0011]
Furthermore, Japanese Patent Laid-Open No. 10-51672 comprises both the phase difference detection method and the contrast detection method using separate sensors, which again complicates the apparatus configuration.
[0012]
The present invention has been made in view of the above-mentioned problems, and it is possible to quickly detect a focus by both a phase difference detection method and a contrast detection method with an inexpensive configuration using an imaging sensor without using a dedicated sensor. It aims to make it possible.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, an imaging apparatus of the present invention includes a plurality of pixels, and each pixel receives a plurality of photoelectric conversion regions and a signal obtained from the plurality of photoelectric conversion regions for each photoelectric conversion region. An image pickup device having an output system capable of outputting, and the plurality of photoelectric conversion regions; Signal output from each From , And calculate the evaluation value of the phase difference and the contrast of the subject image, respectively. Computing means; After driving the focus lens in the first mode based on the phase difference and performing focusing control, the focus lens is driven in the second mode based on the evaluation value. Perform focus control The focus lens is driven in the same direction when switching from the first mode to the second mode. Focusing control means.
[0019]
In order to achieve the above object, each pixel includes a plurality of pixels, and each pixel outputs a plurality of photoelectric conversion regions and a signal obtained from the plurality of photoelectric conversion regions for each photoelectric conversion region. The focus of the present invention for an image pickup apparatus having an image pickup device having an image pickup device and an image pickup optical system Adjustment The method includes the imaging device Each of the plurality of photoelectric conversion regions A reading step of reading a signal from, Read in the reading step signal To calculate the evaluation value of the phase difference and the contrast of the subject image, respectively. A calculation process; A phase difference focusing step in which focus control is performed by driving the focus lens in the first mode based on the phase difference; and the focus lens is moved in the second mode based on the evaluation value after the phase difference focusing step. Drive Perform focus control contrast Together Kako About A control step of controlling the phase difference focusing step and the contrast focusing step so that the driving directions of the focus lens in the switching from the first mode to the second mode are the same direction; Have
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[0023]
First, an image sensor used in the embodiment of the present invention will be described.
[0024]
A CMOS process compatible sensor (hereinafter referred to as “CMOS sensor”), which is one of the amplification type solid-state imaging devices, is used as the imaging element.
[0025]
One of the features of the CMOS sensor is that the number of masks and the number of process steps can be greatly reduced as compared with the CCD because the MOS transistor in the light receiving portion and the MOS transistor in the peripheral circuit can be formed in the same step. Taking advantage of this feature, in this embodiment, two photoelectric conversion units are configured in one pixel, and a floating diffusion (FD) region and a source follower amplifier, which are conventionally provided in each photoelectric conversion unit, are arranged in two photoelectric conversion units in each pixel. One is formed per one. The two photoelectric conversion regions are connected to the FD region via a MOS transistor switch.
[0026]
Accordingly, since the charges of the two photoelectric conversion units can be transferred simultaneously or separately to the floating diffusion unit, the signal charges of the two photoelectric conversion units can be added only by the ON / OFF timing of the transfer MOS transistor connected to the FD region. Therefore, non-addition read control can be easily performed. Using this structure, in this embodiment, an addition output mode for performing photoelectric conversion output by a light beam from the entire exit pupil of the imaging optical system and a photoelectric conversion output by a light beam from a part of the exit pupil of the imaging optical system are performed. It is possible to switch between non-addition output modes performed separately. In the addition output mode in which signals are added at the pixel level, a signal with less noise can be obtained as compared with a method of adding signals after they are read out.
[0027]
FIG. 1 is a circuit configuration diagram of an area sensor unit in an image sensor. This diagram shows a two-dimensional × two-row pixel two-dimensional area sensor for simplification of the drawing, but actually has a very large number of pixels and obtains a practical resolution.
[0028]
In FIG. 1, reference numerals 1 and 51 denote first and second photoelectric conversion units each including a MOS transistor gate and a depletion layer under the gate, 2 and 52 are photogates, 3 and 53 are transfer switch MOS transistors, and 4 is a reset MOS transistor. 5 is a source follower amplifier MOS transistor, 6 is a vertical selection switch MOS transistor, 7 is a load MOS transistor of the source follower, 8 is a dark output transfer MOS transistor, 9 is a light output transfer MOS transistor, and 10 is a dark output storage capacitor C _TN , 11 is the bright output storage capacity C _TS , 12 and 54 are vertical transfer MOS transistors, 13 and 55 are vertical output line reset MOS transistors, 14 is a differential output amplifier, 15 is a vertical scanning unit, and 16 is a horizontal scanning unit.
[0029]
FIG. 2 shows a cross-sectional view of the light receiving unit (for example, 30-11). The light receiving units 30-21, 30-12, 30-22, and the like have the same structure.
[0030]
In this figure, 17 is a P-type well, 18 and 58 are gate oxide films, 19 and 59 are first-layer poly-Si, 20, 50 are second-layer poly-Si, and 21 is an n + floating diffusion region.
[0031]
The FD region 21 is connected to the first photoelectric conversion unit 1 and the second photoelectric conversion unit 51 via the transfer MOS transistors 3 and 53. In the figure, the first photoelectric conversion unit 1 and the second photoelectric conversion unit 51 are drawn apart from each other, but in reality, the boundary portion is extremely small, and the first photoelectric conversion unit 1 and the second photoelectric conversion unit are practically small. The part 51 may be regarded as being in contact.
[0032]
Reference numeral 22 denotes a color filter that transmits light in a specific wavelength range, and reference numeral 23 denotes a microlens for efficiently guiding a light beam from the imaging optical system to the first and second photoelectric conversion units 1 and 51.
[0033]
FIG. 3 is a plan view showing the arrangement of pixels, photoelectric conversion units, and color filters of the image sensor according to the present embodiment. Here, only 4 columns × 4 rows are extracted and shown. Each pixel including the light receiving portion and the MOS transistor is laid out in a substantially square shape and is arranged adjacent to the grid. Each of the pixels 70-11 to 71-44 has the same configuration as the light receiving units 30-11, 30-21, 30-12, and 30-22 described above with reference to FIG.
[0034]
In addition, this area sensor has an R (red), G (green), and B (blue) color filter alternately arranged in each pixel to form a Bayer array in which four pixels are a set. In the Bayer array, the overall image performance is improved by arranging more G pixels that are easily felt when an observer views an image than R and B pixels. In general, in this type of image sensor, the luminance signal is generated mainly from G, and the color signal is generated from R, G, and B.
[0035]
As described above, each pixel has two photoelectric conversion units. R, G, and B attached to the light receiving portion of each pixel indicate that red, green, and blue color filters are provided, respectively, and 1 or 2 following RGB is the first photoelectric conversion portion or the second photoelectric conversion. This represents the distinction between parts. For example, R1 is a first photoelectric conversion unit having a red color filter, and G2 means a second photoelectric conversion unit having a green color filter.
[0036]
Furthermore, in order to effectively use the light beam emitted from the imaging optical system in each pixel, it is necessary to provide a condensing lens in each light receiving part and to deflect light to reach other than the light receiving part to the light receiving part. It becomes. For this purpose, a microlens 23 shown in FIG. 2 is provided in front of the image sensor. The microlens 23 of each pixel is an axisymmetric spherical lens or aspherical lens in which the center of the light receiving portion and the optical axis approximately coincide with each other, each having a rectangular effective portion, and having a light incident side as a convex shape and a lattice shape Are closely arranged.
[0037]
The power of each microlens 23 is set so as to project each light receiving portion of the image sensor onto the exit pupil of the imaging optical system. At this time, the projection magnification is set so that the projected image of each light receiving unit is slightly larger than the exit pupil of the stop of the imaging optical system, and the relationship between the amount of light incident on the light receiving unit and the stop of the imaging optical system is approximately linear. To do. In this way, shooting according to the subject brightness becomes possible, and focus detection can be performed by operating the two photoelectric conversion units separately.
[0038]
Next, a sensor driving method in the present embodiment will be described.
[0039]
As described above, by dividing the photoelectric conversion unit into two, it is possible to easily perform addition reading or non-addition reading control of the accumulated charges in the two regions. In the present embodiment, the operation is performed in the addition output mode for imaging and luminance calculation and in the non-addition output mode for focus detection.
[0040]
First, an outline of the charge accumulation operation of the image sensor will be described with reference to FIGS.
[0041]
Control pulse φPG to expand the depletion layer under the photogates 2 and 52 ₀₀ , ΦPG _e0 Apply a positive voltage to The FD unit 21 controls the control pulse φR to prevent blooming during accumulation. ₀ Set the power supply voltage V to _DD It is fixed to. When photons hν are irradiated and carriers are generated under the photogates 2 and 52, electrons are accumulated in the depletion layer under the photogates 2 and 52, and holes are discharged through the P-type well 17.
[0042]
An energy barrier by the transfer MOS transistor 3 is formed between the photoelectric conversion unit 1 and the FD unit 21, and an energy barrier by the transfer MOS transistor 53 is formed between the photoelectric conversion unit 51 and the FD unit 21. For this reason, electrons are present under the photogates 2 and 52 during photocharge accumulation. Thereafter, when the horizontal scanning unit 16 is scanned and the same charge accumulation operation is sequentially performed for all the photoelectric conversion units, the image is accumulated on the entire surface.
[0043]
In the read state, the control pulse φPG is used so that the barrier below the transfer MOS transistor 3 or 53 is eliminated and the electrons below the photogates 2 and 52 are completely transferred to the FD section 21. ₀₀ , ΦPG _e0 , Control pulse φTX ₀₀ , ΦTX _e0 Set.
[0044]
Next, the reading operation of the image sensor will be described with reference to the timing chart of FIG. This timing chart is for the non-addition output mode in which the charges of the two photoelectric conversion units 1 and 51 are independently output, and is used for reading the focus detection image.
[0045]
First, in response to a timing signal output from the horizontal scanning unit 16, the control pulse φL is set to high to reset the horizontal output line. Also, the control pulse φR ₀ , ΦPG ₀₀ , ΦPG _e0 Is set high, the reset MOS transistor 4 is turned on, and the first-layer poly Si 19 of the photogate 2 is set high. Time T ₀ Control pulse φS ₀ Is turned on, the vertical selection switch MOS transistor 6 is turned on, and the light receiving unit 30-11 is selected. Next, control pulse φR ₀ Is set low, the reset of the FD region 21 is stopped, the FD region 21 is brought into a floating state, and the source-follower amplifier MOS transistor 5 is made through between the gate and the source, and then the time T ₁ Control pulse φT _N , And the dark voltage of the FD region 21 is stored in the storage capacitor C by the source follower operation. _TN 10 to output.
[0046]
Next, in order to perform charge output of the first photoelectric conversion unit 1, a control pulse φTX of the first photoelectric conversion unit 1 is used. ₀₀ Is set to high and the transfer switch MOS transistor 3 is turned on, and then the time T ₂ Control pulse φPG ₀₀ Lower as low. At this time, a voltage relationship is preferable in which the potential well that has spread under the photogate 2 is raised so that photogenerated carriers are completely transferred to the FD region 21.
[0047]
Time T ₂ Thus, the electric charge from the photoelectric conversion unit 1 of the photodiode is transferred to the FD region 21, so that the potential of the FD region 21 changes according to light. At this time, since the source follower amplifier MOS transistor 5 is in a floating state, the potential of the FD region 21 is set to the time T _Three Control pulse φT _s Storage capacity C _TS 11 is output. At this time, the dark output and the light output of the first photoelectric conversion unit 1 are respectively stored in the storage capacitor C. _TN 10 and C _TS 11 and the time T _Four The vertical output line reset MOS transistors 13 and 55 are turned on by resetting the control pulse φHC to be temporarily high to reset the vertical output line. Output light output. Storage capacity C _TN 10 and C _TS 11 differential output amplifier 14 allows differential output V _OUT By taking this, a signal with good S / N from which random noise and fixed pattern noise of the pixel are removed can be obtained.
[0048]
Note that the photocharges of the light receiving unit 30-12 are stored in the respective storage capacitors C simultaneously with the light receiving unit 30-11. _TN And C _TS In the readout, the timing pulse from the vertical scanning unit 15 is delayed by one light receiving portion, read out to the vertical output line, and output from the differential output amplifier 14. Since it is the difference in timing pulse of one light receiving portion, the accumulation time of both can be regarded as substantially the same.
[0049]
Next, storage capacity C _TS After the bright output is output to 11, the control pulse φR ₀ Is made high, the reset MOS transistor 4 is turned on, and the FD region 21 is set to the power supply voltage V _DD Reset to.
[0050]
After the vertical transfer of the first photoelectric conversion unit 1 is completed, the second photoelectric conversion unit 51 is read. Reading of the second photoelectric conversion unit 52 is performed with the control pulse φR. ₀ Is set low, the reset of the FD region 21 is stopped, the FD region 21 is brought into a floating state, and the source-follower amplifier MOS transistor 5 is made through between the gate and the source, and then the time T _Five Control pulse φT _N , And the dark voltage in the FD region 21 is again stored by the source follower operation. _TN 10 to output.
[0051]
In order to perform the photoelectric conversion output of the second photoelectric conversion unit 51, the control pulse φTX of the second photoelectric conversion unit 51 _e0 Is set to high and the transfer switch MOS transistor 53 is turned on, and then the time T ₆ Control pulse φPG _e0 Lower as low.
[0052]
Time T ₆ Thus, the electric charge from the second photoelectric conversion unit 51 of the photodiode is transferred to the FD region 21, so that the potential of the FD region 21 changes according to light. At this time, since the source follower amplifier MOS transistor 5 is in a floating state, the potential of the FD region 21 is set to the time T ₇ Control pulse φT _s Storage capacity C _TS 11 is output. At this time, the dark output and the light output of the second photoelectric conversion unit 51 are respectively stored in the storage capacitor C. _TN 10 and C _TS 11 at time T ₈ The vertical output line reset MOS transistors 13 and 55 are turned on by resetting the control pulse φHC to be temporarily high to reset the vertical output line. Output light output. And storage capacity C _TN And C _TS On the basis of the output from the differential output V of the second photoelectric conversion unit by the differential amplifier 14 _OUT Get.
[0053]
With the above driving, the first and second photoelectric conversion units 1 and 51 can be read independently.
[0054]
Thereafter, by scanning the horizontal scanning unit and performing the reading operation in the same manner, independent outputs of all the photoelectric conversion units can be obtained. That is, in the case of the next column, first, the control pulse φS ₁ To high, then φR ₁ To low, then control pulse φT _N , ΦTX ₀₁ , And control pulse φPG ₀₁ Low, control pulse φT _S , And the control pulse φHC is temporarily high, the signals of the first photoelectric conversion units of the light receiving units 30-21 and 30-22 are read. Subsequently, the control pulse φTX _e1 , ΦPG _e1 In the same manner as described above, a control pulse is applied to read out signals from the second photoelectric conversion units of the light receiving units 30-21 and 30-22.
[0055]
Next, an addition output mode for outputting a signal based on a light beam from all pupils of the objective lens by adding the signals of the first and second photoelectric conversion units in the FD region 21 will be described. This operation mode corresponds to image output by a normal image sensor.
[0056]
FIG. 5 shows a timing chart when the signals of the first and second photoelectric conversion units are added. In FIG. 4 showing the control in the non-addition output mode, the control pulse φTX ₀₀ And control pulse φTX _e0 , Control pulse φPG ₀₀ And control pulse φPG _e0 However, the timing is the same for addition. That is, in order to simultaneously read from the first photoelectric conversion unit 1 and the second photoelectric conversion unit 51 of the light receiving unit 30-11, first, the control pulse φT _N To read the noise component from the horizontal output line and control pulse φTX ₀₀ And control pulse φTX _e0 And control pulse φPG ₀₀ And control pulse φPG _e0 Are simultaneously transferred to the FD area 21 as high and low, respectively. As a result, the signals of the upper and lower photoelectric conversion units 1 and 51 can be added simultaneously in the FD region 21. Since signal addition is performed at the pixel level, it is not affected by amplifier noise, and an image with a high S / N that cannot be obtained by addition after signal readout is obtained.
[0057]
With the configuration of the image sensor described above and the driving method thereof, a single sensor can function as a light receiving element for imaging and focus detection.
[0058]
Here, regarding a method for adjusting the focus on a subject, a method for detecting a defocus amount, which is a focus shift amount of an imaging optical system, using a phase difference detection method that is a well-known technique will be described first.
[0059]
6A and 6B, for easy understanding, the light beam incident on the first photoelectric conversion unit and the light beam incident on the second photoelectric conversion unit in the light receiving unit 72-11 illustrated in FIG. It is the figure which divided and showed each of these. 6A showing the light beam incident on the first photoelectric conversion unit, FIG. 6B shows the light beam incident from the lower side of the figure on the first photoelectric conversion unit G1 and incident on the second photoelectric conversion unit. ), It can be seen that the light beam from above in the figure is incident on the second photoelectric conversion unit G2.
[0060]
That is, in the entire image sensor, the light beam incident on the second photoelectric conversion unit at any position of the area sensor unit is a light beam that passes through half of the exit pupil of the imaging optical system. On the other hand, the light beam incident on the first photoelectric conversion unit of the entire imaging device may be considered as being inverted with the optical axis of the imaging lens as the symmetry axis. That is, the division of the exit pupil of the imaging optical system is as shown in FIG.
[0061]
In FIG. 7, reference numeral 220 denotes an exit pupil of the imaging optical system. 221 is a first region on the exit pupil through which the light beam incident on the first photoelectric conversion unit of the image sensor passes, and 222 is a second region on the exit pupil through which the light beam incident on the second photoelectric conversion unit of the image sensor passes. It is an area. That is, the image signal obtained from the first photoelectric conversion unit and the image signal obtained from the second photoelectric conversion unit are both formed from a half light beam obtained by substantially dividing the exit pupil of the imaging optical system into two.
[0062]
In the optical system as described above, for example, when an object image is formed in front of the image sensor, the half light beam passing through the right side of the exit pupil is shifted to the left side on the image sensor, and the left side of the exit pupil is The passing half-beam is shifted to the right. That is, a pair of image signals formed by a light beam that passes through each half of the pupil of the imaging optical system has a phase shifted in the left-right direction in FIG. 3 according to the imaging state of the object image. Therefore, in order to obtain the defocus amount, a shift amount that is a relative positional relationship between two subject images may be obtained from the correlation. An example of a calculation method for specifically obtaining this will be described with reference to FIG.
[0063]
The area U (the sum of the smaller values of the A and B images) of the AND region of the image signal indicating the two subject images (A and B images) shown in FIG. 8 is the one image (A image in FIG. 8). The image signal is shifted by one pixel (1 bit) of the photoelectric conversion element, and the maximum value is obtained. If the two images coincide with each other, the maximum value is inevitably obtained. Therefore, the shift amount that causes the maximum value is the relative shift amount of the two images. This deviation amount and the conversion coefficient to the defocus amount determined by the imaging optical system are obtained.
[0064]
The other well-known technique, a contrast detection method, will also be briefly described.
[0065]
In this method, the brightness (output of the image sensor) is detected for every minute area in the entire area or a part of the image to be photographed, and the focus is based on the difference in brightness between adjacent areas, that is, the contrast. Whether or not.
[0066]
In general, an area sensor is used to obtain a difference in received light amount (difference in pixel output) between adjacent pixels, and the sum of absolute values of the differences is used as an evaluation value as a contrast value. When the photographic lens is focused on the subject, the contrast value of the area sensor inevitably increases, and conversely, when the focus is not focused on the subject. Since there are fluctuations due to the characteristics of the subject itself, there is no standard evaluation value for determining in-focus, but the maximum evaluation value is always obtained when in-focus.
[0067]
Therefore, the focus adjustment operation is called a hill-climbing method, and the focus position of the photographic lens is moved every minute section, and after confirming that the evaluation value is maximum, the focus position is determined. It is not possible to obtain information on the first moving direction, that is, whether the current pin is the front pin or the rear pin.
[0068]
FIG. 9 is a diagram showing an image pickup apparatus such as a digital still camera or a digital video camera using the above-described solid-state image pickup device. In FIG. 9, 101 is a barrier that serves as a lens protect and a main switch, and 102 is an optical image of a subject. A lens that forms an image on the solid-state image sensor 104; 103, a diaphragm for adjusting the amount of light that has passed through the lens 102; 104, a solid-state image sensor having the above-described configuration for capturing the subject imaged by the lens 102 as an image signal; Reference numeral 105 denotes an image pickup signal processing circuit including a variable gain amplifier for amplifying an image signal output from the solid-state image sensor 104 and a gain correction circuit for correcting the gain value. 106 denotes an image output from the solid-state image sensor 104. An A / D converter that performs analog-digital conversion of a signal. A signal processing unit 107 performs various corrections on the image data output from the A / D converter 106 and compresses the data, and 108 indicates a solid-state image sensor 104, an imaging signal processing circuit 105, and an A / D converter 106. A timing generation unit that outputs various timing signals to the signal processing unit 107, 109 an overall control / calculation unit that controls various calculations and the entire still video camera, and 110 a memory unit for temporarily storing image data, Reference numeral 111 denotes an interface unit for recording or reading on a recording medium, 112 denotes a removable recording medium such as a semiconductor memory for recording or reading image data, and 113 denotes an interface unit for communicating with an external computer or the like. is there.
[0069]
Next, an outline of the camera operation at the time of shooting by the imaging apparatus having the above configuration will be described.
[0070]
When the barrier 101 is opened, the main power supply is turned on, then the control system power supply is turned on, and the power supply of the imaging system circuit such as the A / D converter 106 is turned on. Then, in order to control the exposure amount, the overall control / arithmetic unit 109 opens the aperture 103, and the signal output from the solid-state image sensor 104 is converted by the A / D converter 106 and then sent to the signal processing unit 107. Entered. Based on this data, exposure calculation is performed by the overall control / calculation unit 109. The brightness is determined based on the result of the photometry, and the overall control / calculation unit 109 controls the aperture according to the result. Next, based on the signal output from the solid-state imaging device 104, the overall control / calculation unit 109 performs a focus adjustment described later. Thereafter, the lens is driven to determine whether or not it is in focus. When it is determined that the lens is not in focus, the lens is driven again to perform distance measurement. Then, after the in-focus state is confirmed, the actual shooting starts. When shooting is completed, the image signal output from the solid-state image sensor 104 is A / D converted by the A / D converter 106, passes through the signal processing unit 107, and is written in the memory unit 110 by the overall control / calculation unit 109. Thereafter, the data stored in the memory unit 110 is recorded on a removable recording medium 112 such as a semiconductor memory through the recording medium control I / F unit 111 under the control of the overall control / arithmetic unit 109. Further, the image processing may be performed by directly entering the computer or the like through the external I / F unit 113.
[0071]
<First Embodiment>
In the first embodiment, a focus detection method using the imaging device having the above configuration and capable of being driven in the addition output mode and the non-addition output mode will be described below.
[0072]
In the first embodiment, the contrast evaluation value is also obtained directly from the signal for obtaining the evaluation value of the phase difference detection method. That is, using two signals obtained by operating the image sensor in the non-addition output mode, the shift amount is obtained by the phase difference detection method, and at the same time, the contrast evaluation value is obtained from at least one signal by the contrast method. Although the two signals in the non-addition output mode have a difference in the exit pupil area of the photographing lens, basically the same evaluation can be made in contrast.
[0073]
In the present invention, since the phase difference detection method and the contrast method can be simultaneously evaluated, the contrast evaluation value is also obtained each time the driving direction and the driving amount of the photographing lens are obtained by the phase difference detection method. However, the lens can be driven first with the direction and amount determined by the phase difference detection method.
[0074]
The focus adjustment operation in the first embodiment will be described below with reference to the flowcharts shown in FIGS.
[0075]
FIG. 10 is a flowchart for explaining the basic operation of the focus adjustment in the first embodiment of the present invention.
[0076]
When focus adjustment is started in step S100, first, in step S101, the operation mode of the image sensor is set to the non-addition output mode. In step S102, an imaging operation is performed to read a non-added image signal.
[0077]
In steps S103 and S104, a contrast evaluation value and a phase difference evaluation value are calculated, respectively.
[0078]
In the subsequent step S105, first, the focus of the photographing lens is adjusted according to the direction and amount based on the phase difference evaluation value. Here, the lens driving amount is driven to be smaller than the evaluation value by a predetermined amount (for example, the in-focus width). This is because the driving direction of the lens in the subsequent hill climbing control is aligned in the same direction. Therefore, the focus determination at this point is not performed. In step S106, focus adjustment based on a known contrast evaluation value is performed as hill-climbing control. The operation in step S106 will be described later in detail with reference to FIG.
[0079]
In step S107, it is determined whether focusing by hill-climbing control has been performed. If focusing is achieved, the non-addition output mode of the image sensor is canceled in step S108. On the other hand, when the in-focus state has not been reached, the process returns to step S105, and the lens driving based on the latest phase difference evaluation value is started again. According to the present invention, since the evaluation values of both the phase difference detection method and the contrast method can always be obtained by one accumulation operation, this operation can be performed quickly.
[0080]
As described above, control that combines the phase difference detection method and the contrast method is performed, and the focus adjustment operation is terminated in step S109.
[0081]
FIG. 11 is a flowchart showing the procedure of hill climbing control performed in step S106 of FIG.
[0082]
When the hill climbing control is started, an imaging operation is first performed in step S111. Here, the accumulated charge is read out in the non-addition output mode. Using the read image signal, a contrast evaluation value and a phase difference evaluation value are calculated in steps S112 and S113, respectively.
[0083]
In step S114, it is determined whether the contrast evaluation value obtained this time is higher than the previous evaluation value.
[0084]
If the contrast evaluation value has increased, the sign of the phase difference evaluation value is also confirmed in step S115. Here, attention is paid only to the sign of the phase difference evaluation value, that is, the focus shift direction. This is because if both the increase in the contrast evaluation value and the coincidence of the signs of the phase difference evaluation values are satisfied, it can be determined that the vehicle is smoothly moving toward the in-focus area. Therefore, when these conditions are satisfied, in step S116, the lens is moved in the same direction by a predetermined minute amount, and the hill-climbing control is continued again from step S111.
[0085]
While the hill-climbing control is continuing, if the contrast evaluation value is lower than the previous time in step S114, the sign inversion of the phase difference evaluation value is determined in step S117. If the contrast evaluation value decreases and the sign of the phase difference evaluation value is also inverted, it is considered that the focal point has been passed.
[0086]
Accordingly, if the above condition is satisfied, it is determined that the in-focus point has passed in step S118, the process proceeds to step S119, the lens is driven to the position where the contrast evaluation value is the maximum, that is, the previous position, and the in-focus determination is performed in step S120. End control.
[0087]
On the other hand, when the sign of the phase difference evaluation value is not inverted in step S117, or when the sign of the phase difference evaluation value is inverted in step S115, the behavior of the contrast evaluation value and the phase difference evaluation value does not correspond to each other. It is.
[0088]
In the first embodiment, it is determined that this state is not yet the stage for performing the hill climbing control, and the hill climbing control is terminated while the out-of-focus determination is made in step S121. After that, as described above, the focus determination determination in step S107 in FIG. 10 returns to step S105, and the lens driving based on the phase difference evaluation value is performed again.
[0089]
As described above, according to the first embodiment of the present invention, since the evaluation values of both the phase difference detection method and the contrast method can be obtained simultaneously by a single accumulation operation from the image sensor used for photographing an image, It is not necessary to provide a separate sensor, and although it is inexpensive, it is possible to perform quick focus adjustment control and determination even when two focus adjustment methods are used in combination.
[0090]
<Second Embodiment>
Next, a method for driving an image sensor according to the second embodiment of the present invention, particularly, a region will be described.
[0091]
12 and 13 show examples of combinations of image sensor driving methods and readout regions.
[0092]
12 and 13, the distribution image diagram of the column (a) drive method (circle indicates the drive in the addition output mode, the other indicates the drive in the non-addition output mode), the column (b) is the subject image image diagram, and the column (c) is When the image shown in column (b) is read out by the driving method of the distribution shown in column (a), the signal image diagram for the phase difference detection method, column (d) shows the image shown in (b) in column (a) FIG. 6 is a signal image diagram for a contrast method when read by the driving method having the distribution shown in FIG.
[0093]
In FIG. 12, each row (A) to (C) shows a case where the drive region setting state of the image sensor is different, and (A) is a case where the image sensor is uniformly driven in the non-addition output mode. (B) When the image sensor is driven alternately in the non-addition / addition output mode for each row, (C) is the image sensor driven in the addition output mode only in the four corner areas, and the rest is driven in the non-addition output mode. This is the case.
[0094]
In (A), since the driving is performed in the full non-addition output mode, both the phase difference detection method and the contrast method can be evaluated over the entire surface. On the other hand, the amount of pixel data to be read increases (twice the number of pixels), which takes time.
[0095]
In (B), since the drive mode is switched for each row, the number of pixel data to be read is reduced as compared with the drive method in (A), so that higher speed can be expected. However, both types cannot be evaluated on all screens. Note that the driving method may be changed not only for each row but for each arbitrary row.
[0096]
(C) is an example in which only the four corner areas are performed in the addition output mode. This is an example of a countermeasure in such a case because the phase difference detection method at the four corners may cause a problem due to kicking of the light beam depending on the optical system of the imaging system.
[0097]
On the other hand, in FIG. 13, when the image sensor is driven in the addition output mode only in the central region and the other in the non-addition output mode in row (D), row (E) separates the left and right from the center in the image sensor. When driving in the non-addition / addition output mode, the row (F) is in the non-addition output mode only in the area in the upper left corner of the image sensor, and the rest is only in the lower left corner area from the driving state in the addition output mode. In the non-addition output mode, the rest is the case where the drive state is changed to the addition output mode.
[0098]
In (D), for example, the main subject is captured in the central region of the entire phase difference operation as shown in (A), focus adjustment is continued using the contrast method after focusing once, and phase difference detection is performed to change the subject to the periphery. This is an example of area division when it is said that the system responds quickly. This is effective in shooting modes that capture the subject in a relatively central part, such as portrait and close-up shooting.
[0099]
In (E), the left half of the subject is an area with relatively high contrast, while the right half is an average low contrast area. In such a case, the phase difference method is difficult to obtain a correct evaluation result when there is no contrast due to the nature of the evaluation value. Therefore, it is also effective to positively set a region using the phase difference method and a region using the contrast method according to the subject condition.
[0100]
In (F), in the explanatory diagram of (a), the phase difference setting region is moved from the upper left corner to the lower left corner. This is a diagram assuming that the setting area is moved according to the photographer's intention using, for example, well-known gaze detection. In this way, by setting the phase difference operation region only for the region necessary for performing quick focus adjustment, the number of pixel data to be read as a whole is reduced, and the configuration of the device with higher responsiveness becomes possible.
[0101]
As described above, it is effective to select an optimal region setting according to the subject condition, the shooting mode, or the system configuration.
[0102]
<Third Embodiment>
Next, a focus detection method according to the third embodiment of the present invention will be described below.
[0103]
In the third embodiment, a case where a contrast evaluation value is directly obtained from an imaging signal will be described. That is, the contrast evaluation value is obtained from a signal obtained by operating the image sensor in the addition output mode.
[0104]
Hereinafter, photographing and focus adjustment operations in the third embodiment will be described with reference to a flowchart shown in FIG.
[0105]
FIG. 14 is a flowchart showing the procedure of the focus adjustment operation and the moving image shooting operation in the third embodiment. Here, a case will be described in which the focus detection is first started by the phase difference detection method in the moving image shooting mode, and the mode is shifted to the contrast method at the start of moving image shooting.
[0106]
When the moving image shooting mode is set (YES in step S200), the state of a release button switch first stage (SW1) (not shown) is first detected in step S201. If the switch is on, in step S202, the operation mode of the image sensor is set to the non-addition output mode, and a series of operations of imaging and reading is performed. In step S203, an evaluation value of the phase difference detection method is calculated from the imaging signal read in the non-addition output mode. In subsequent step S204, the focus of the photographing lens is first adjusted in the direction and amount based on the evaluation value of the phase difference detection method.
[0107]
In step S205, the state of the release button switch second stage (SW2) (not shown) is detected. This is detection of whether or not moving image shooting has started. If not started yet, the process returns to step S201, and the operations from step S201 to step S205 are repeated.
[0108]
On the other hand, if moving image shooting is started, the operation mode of the sensor is set to the addition output mode in step S206, accumulation, reading, and recording operations are performed, and a moving image is shot.
[0109]
In the next step S207, an evaluation value of the contrast method is calculated using the signal obtained in step S206. In step S208, lens driving based on the evaluation value is performed. Specifically, it is moved in a direction to obtain an evaluation value higher than the previous evaluation value by a minute amount of drive.
[0110]
The operations from step S205 to step S208 are continued until the end of moving image capturing, that is, until the state of the release button switch second stage (SW2) (not shown) in step S205 is turned OFF.
[0111]
If it is detected in step S201 that the state of the first stage of the release button switch (not shown) is OFF, the process returns to step S200, and when the setting of the moving image mode is cancelled, the process ends.
[0112]
In the third embodiment, the case where the switching control between the phase difference detection method and the contrast method is automatically performed when the mode is switched to the moving image mode has been described. However, the present invention is not limited to this, and imaging is performed. Any system that automatically controls the phase difference detection method and the contrast method according to the switching of the operation mode of the element may be used. First, focus detection is started in one focus detection mode, and the other focus detection mode is controlled depending on some condition. As long as it moves to.
[0113]
As described above, according to the third embodiment, according to the switching of the operation mode of the image sensor, the focus detection is automatically performed using an appropriate method of the phase difference detection method and the contrast method. A distance measuring sensor is not separately provided, and it is possible to perform quick focus adjustment control and determination using one of two appropriate focus adjustment methods while being inexpensive.
[0114]
<Fourth Embodiment>
A focus detection method according to the fourth embodiment of the present invention will be described below.
[0115]
FIG. 15 is a flowchart showing the procedure of the focus adjustment operation and the photographing operation in the fourth embodiment. Here, a case will be described in which the focus adjustment is performed by the contrast method when the shooting mode is the moving image mode, and by the phase difference detection method when the image is still image.
[0116]
When the photographing operation is selected, first, in step S301, the state of a release button switch first stage (SW1) (not shown) is detected. If the switch is on, it is determined in step S302 whether or not the shooting mode is the moving image mode. If it is not the moving image mode but the still image mode, the process proceeds to step S303, and a still image shooting operation is performed. The operation in step S303 will be described later with reference to FIG.
[0117]
On the other hand, if it is the moving image mode, first, in step S304, the operation mode of the image sensor is set to the addition output mode, and a series of imaging operations of charge accumulation and readout are performed. In the next step S305, an evaluation value is calculated by the contrast method from the latest imaging signal.
[0118]
Subsequently, in step S306, it is determined whether the contrast evaluation value has increased from the previous time, that is, whether it is in the focused state. In the case of the first focus adjustment operation, the process proceeds directly to step S308 without performing the determination in step S306. If the evaluation value is lowered in step S306, the lens drive direction instruction is reversed in step S307.
[0119]
In step S308, the lens is driven in the current setting direction by a predetermined value determined by the design of the photographing optical system, for example, a minute amount corresponding to the focus width.
[0120]
In the next step S309, the state of a release button switch second stage (SW2) (not shown) is detected. That is, it is detected whether or not moving image shooting has started. If not started, the process returns to step S301, and the operations from step S301 to step S309 are repeated.
[0121]
On the other hand, if moving image shooting is started, in step S310, the sensor operation mode remains in the addition output mode, shooting is performed by performing accumulation, reading, and recording operations, and the process returns to step S305. That is, the operation from step S305 to step S310 is continued during moving image shooting.
[0122]
If it is detected in step S301 that the state of the first stage of the release button switch (not shown) is OFF, the process returns to step S300, and the process ends when the shooting mode is canceled.
[0123]
FIG. 16 is an explanatory diagram of a focus adjustment operation and shooting flow in still image shooting according to the fourth embodiment. As described above, in the case of a still image, focus adjustment is performed using a phase difference detection method.
[0124]
When the still image shooting operation starts in step S303 in FIG. 15, first, the operation mode of the image sensor is set to the non-addition output mode in step S311, and a series of imaging operations of charge accumulation and readout are performed. In the next step S312, the evaluation value of the phase difference detection method is calculated from the imaging signal obtained by imaging.
[0125]
In subsequent step S313, it is determined whether or not the current focus adjustment state is an in-focus state based on the evaluation value of the phase difference detection method.
[0126]
If not in focus, in step S314, the lens is driven based on the latest evaluation value. Then, the process returns to step S311, and the operation up to step S313 is continued until it is determined to be in focus.
[0127]
If the in-focus state is determined in step S313, the state of the release button switch second stage (SW2) (not shown) is detected in the next step S315. That is, it is detected whether still image shooting has started.
[0128]
If not started yet, the process returns from the still image shooting operation to step S301 in FIG. 15 to continue the operation from step S301 to step S303 and from step S311 to step S315 in FIG.
[0129]
On the other hand, if still image shooting is started, in step S316, the operation mode of the sensor is set as an addition output mode to perform accumulation, readout, and recording operations as shooting, and the process returns to step S301 in FIG.
[0130]
As described above, according to the fourth embodiment, the same effect as that of the third embodiment can be obtained.
[0131]
<Fifth Embodiment>
A focus detection method according to the fifth embodiment of the present invention will be described below.
[0132]
FIG. 17 is a flowchart showing the procedure of the focus adjustment operation and the photographing operation in the fifth embodiment. Here, the case where the shooting mode is the still image mode, and the focus adjustment is performed by the contrast method when the contrast of the subject is low and the phase difference detection method is performed when the contrast is sufficiently high is described. This is because the accuracy of the phase difference detection method greatly depends on the contrast state of the subject.
[0133]
First, when the still image shooting operation is started in step S400 of FIG. 17, first, the operation mode of the image sensor is set to the addition output mode in step S401, and a series of imaging operations of charge accumulation and reading are performed.
[0134]
In the next step S402, the evaluation value of the contrast method is calculated using the above imaging signal. In subsequent step S403, the contrast state of the subject is determined based on the evaluation value, and it is determined whether the contrast is within a range that can be controlled to a sufficiently in-focus state by the phase difference detection method. This is because the focus adjustment operation using the phase difference detection method can be controlled more quickly, and it is therefore desirable to perform focus adjustment using the phase difference detection method as much as possible.
[0135]
If the subject is in a contrast state that can be controlled to a sufficiently in-focus state by the phase difference detection method, the operation mode of the image sensor is set to the non-addition output mode in step S404, and a series of imaging operations of charge accumulation and readout are performed. In the next step S405, an evaluation value in the phase difference detection method is calculated from the imaging signal, and in a subsequent step S406, the current focus adjustment state is determined based on the evaluation value in the phase difference detection method. judge.
[0136]
If not in focus, in step S407, the lens is driven based on the latest evaluation value, and then the process returns to step S404 again until the operation up to step S406 is determined to be in focus. If it is determined in step S406 that the subject is in focus, the process proceeds to step S409.
[0137]
On the other hand, if it is determined in step S403 that the current contrast state of the subject cannot be sufficiently controlled by the phase difference detection method using the phase difference detection method, focus adjustment by scan control generally performed in the contrast method in step S408. Perform the action. This operation will be described later with reference to FIG.
[0138]
If it is determined in step S406 or the scan control of FIG. 17 that the in-focus state is detected, the state of the release button switch second stage (SW2) (not shown) is detected in the next step S409. That is, it is detected whether still image shooting has started. If not, the process returns to step S400.
[0139]
On the other hand, if still image shooting is started, in step S410, the operation mode of the image sensor is stored, read out, and recorded in the addition output mode, and the image is captured and the process returns to step S400. When the still image shooting is canceled in step S400, the process ends.
[0140]
FIG. 18 is a flowchart for explaining the focus adjustment operation when it is determined in step S403 in FIG. 17 that the current subject contrast state cannot be controlled to a sufficiently in-focus state by the phase difference detection method. As described above, in this case, the focus is adjusted by the contrast method.
[0141]
First, in step S411, it is determined whether the focus has already been determined. If it is in focus, the focus adjustment operation is terminated as it is, and the process proceeds to step S409 in FIG.
[0142]
If not in focus, in step S412, the focus state of the photographic optical system is moved to the closest end. This is the lens position at the start of scanning. Next, in step S413, the operation mode of the image sensor is set to the addition output mode, and a series of image capture operations of charge accumulation and readout are performed.
[0143]
In the next step S414, an evaluation value of the contrast method is calculated from the latest imaging signal, and the current lens position and the evaluation value are stored together.
[0144]
In the subsequent step S415, the lens is driven in the infinite end direction by a predetermined value determined by the design of the photographing optical system, for example, a minute amount corresponding to the focus width.
[0145]
In the next step S416, it is determined whether the lens position has reached the infinite end. That is, it is detected whether the driving is completed up to the scanning operation end position. If it has not yet reached the infinite end, the process returns to step S413, and the scanning operation up to step S416 is repeated.
[0146]
On the other hand, when reaching the infinite end, the lens is driven to the position with the largest evaluation value based on the lens position and the contrast evaluation value data obtained by the scanning operation of step S414 in step S417, and the focus is set in step S418. The determination is made, and the focus adjustment operation by the scan control operation is terminated.
[0147]
As described above, according to the fifth embodiment, the focus adjustment method is automatically switched according to the contrast state of the subject. Rapid focus adjustment control and determination using any of the focus adjustment methods becomes possible.
[0148]
[Other Embodiments]
The software configuration and the hardware configuration of the above embodiment can be appropriately replaced.
[0149]
In addition, you may make it this invention combine the above-mentioned each embodiment or those technical elements as needed.
[0150]
Further, the present invention is such that the configuration of the claims or the whole or a part of the configuration of the embodiment forms one device, but is combined with another device. Alternatively, it may be an element constituting the apparatus.
[0151]
Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included. Examples of the storage medium for storing the program code include a floppy disk, hard disk, ROM, RAM, magnetic tape, nonvolatile memory card, CD-ROM, CD-R, DVD, optical disk, magneto-optical disk, MO, etc. Can be considered.
[0152]
Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0153]
When the present invention is applied to the above-described storage medium, the storage medium includes program code corresponding to the flowcharts shown in FIGS. 10 and 11, 14, 15 and 16, or FIGS. 17 and 18. Will be stored.
[0154]
【The invention's effect】
As described above, according to the present invention, it is possible to perform rapid focus detection by both the phase difference detection method and the contrast detection method with an inexpensive configuration using an imaging sensor without using a dedicated sensor.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of an imaging area sensor unit in an embodiment of the present invention.
FIG. 2 is a cross-sectional view of an image sensor light receiving portion according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating the arrangement of photoelectric conversion units and color filters of an image sensor according to an embodiment of the present invention.
FIG. 4 is a timing chart for driving the sensor in the non-addition output mode according to the embodiment of the present invention.
FIG. 5 is a timing chart for driving the sensor in the addition output mode according to the embodiment of the present invention.
FIG. 6 is an explanatory diagram of a pupil division method according to the embodiment of the present invention.
FIG. 7 is an explanatory diagram of a pupil division method according to the embodiment of the present invention.
FIG. 8 is a diagram showing a concept of a focus adjustment operation by a phase difference detection method.
FIG. 9 is a block diagram showing a configuration of an image pickup apparatus using the image pickup element of the present invention.
FIG. 10 is a flowchart showing a focus adjustment operation procedure in the first embodiment of the present invention.
FIG. 11 is a flowchart showing a focus adjustment operation procedure in the first embodiment of the present invention.
FIG. 12 is a diagram conceptually illustrating a combination of an image sensor driving method and a readout region in a second embodiment of the present invention.
FIG. 13 is a diagram conceptually illustrating a combination of an image sensor driving method and a readout region in a second embodiment of the present invention.
FIG. 14 is a flowchart showing a moving image shooting and focus adjustment operation procedure in the third embodiment of the present invention.
FIG. 15 is a flowchart showing an imaging and focus adjustment operation procedure in the fourth embodiment of the present invention.
FIG. 16 is a flowchart showing still image shooting and focus adjustment operation procedures in the fourth embodiment of the present invention;
FIG. 17 is a flowchart showing still image shooting and focus adjustment operation procedures in the fifth embodiment of the present invention;
FIG. 18 is a flowchart showing still image shooting and focus adjustment operation procedures in the fifth embodiment of the present invention;
[Explanation of symbols]
1 1st photoelectric conversion part
51 Second photoelectric conversion unit
2,52 Photogate
3,53 Transfer switch MOS transistor
4 Reset MOS transistor
5 Source follower amplifier MOS transistor
6 Vertical selection switch MOS transistor
7 Load MOS transistor
8. Dark output transfer MOS transistor
9 Bright output transfer MOS transistor,
10 Dark output storage capacity
11 Bright output storage capacity
12, 54 Vertical transfer MOS transistor
13,55 Vertical output line reset MOS transistor
14 Differential output amplifier
15 Vertical scanning section
16 Horizontal scanning section
22 Color filter
23 Microlens

Claims (8)

A plurality of pixels, each pixel, and an imaging device having a plurality of photoelectric conversion regions, and a plurality of output systems can output to the photoelectric conversion each photoelectric conversion region signal obtained from the region,
Calculation means for calculating the evaluation value of the phase difference and the contrast of the subject image from the signals output from each of the plurality of photoelectric conversion regions,
Wherein by driving the focus lens after the focusing control in the first mode based on the phase difference, it has rows focusing control by driving the focus lens in the second mode based on the evaluation value, the second And an in- focus control means for controlling the driving direction of the focus lens in the same direction in switching from the first mode to the second mode . A focusing state determination means;
The focus state determination means, the evaluation value of the Contrast is lower than the evaluation value of the Contrast obtained immediately before, and the drive direction of the focus lens based on the phase difference, obtained immediately before the phase is different from the focus direction based on the difference, the imaging apparatus according to claim 1, characterized in that to determine the state of the immediately preceding and an in-focus state. Evaluation value of the Contrast is lower than the evaluation value obtained Contrast immediately before, and the drive direction of the focus lens based on the phase difference, the driving of the focus lens based on the phase difference obtained immediately before same as the direction, and the evaluation value of the contrast is larger than the evaluation value obtained contrast immediately before, and the drive direction of the focus lens based on the phase difference, the phase difference obtained immediately before If the driving direction of the focus lens based on the different image pickup apparatus according to claim 2, characterized in that again the focus control by the focus control means. A plurality of pixels, each pixel comprises a plurality of photoelectric conversion region, and an imaging device having a plurality of output systems can output to the photoelectric conversion each photoelectric conversion region signal obtained from the region, and the imaging optical system A focus adjustment method for an imaging device comprising:
A readout step of reading out signals from each of the plurality of photoelectric conversion regions of the imaging device;
A calculation step of calculating an evaluation value of a phase difference and a contrast of a subject image from the signal read in the reading step ;
A phase difference focusing step of driving the focus lens in the first mode based on the phase difference to perform focusing control;
After the phase-difference in-focus process, a higher contrast if Aseko performing focus control by driving the focus lens in the second mode based on the evaluation value,
And a control step for controlling the phase difference focusing step and the contrast focusing step so that the driving directions of the focus lens in the switching from the first mode to the second mode are the same. focusing wherein. A focusing state determination step;
The focus state determination step, evaluation value of the Contrast is lower than the evaluation value of the Contrast obtained immediately before, and the drive direction of the focus lens based on the phase difference, obtained immediately before the phase focusing method according to claim 4, characterized in that it is determined that if different from the focus direction based on the difference, an in-focus state the state of the immediately preceding. Evaluation value of the Contrast is lower than the evaluation value of the Contrast obtained immediately before, and, focus direction based on the phase difference is the same as the driving direction of the focus lens based on the phase difference obtained immediately before If, and, focus evaluation values of contrast is larger than the evaluation value obtained contrast immediately before, and the drive direction of the focus lens based on the phase difference, based on the phase difference obtained immediately before if different directions, said reading step, the calculating step, the phase difference in-focus process, focus control method according to claim 4 or 5, characterized in that again the contrast focusing process, control process. The computer program of the order to execute the steps of the focusing method of claim 4. A computer-readable storage medium storing the program according to claim 7 .

Images