JP2012231421A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of pixel signals output by an image pickup device included in an imaging apparatus.SOLUTION: An imaging apparatus comprises: an image pickup device in which a plurality of pixels are disposed, each of the pixels including an electric charge storage part for storing electric charge corresponding to the amount of incident light and an electric charge holding part for holding the electric charge transferred from the electric charge storage part, and which includes a signal output part for outputting a pixel signal corresponding to the electric charge transferred from the electric charge storage part to the electric charge holding part; storage means for prestoring, for each of the plurality of pixels, information on incompletely transferred electric charge corresponding to the remaining incompletely transferred electric charge in the electric charge storage part as the charge is transferred from the electric charge storage part to the electric charge holding part, for each pixel corresponding to the electric charge storage part; and correction means for correcting the pixel signal output by the signal output part on the basis of the incompletely transferred electric charge information stored by the storage means.

Description

  The present invention relates to an image pickup apparatus using a charge storage type image pickup element such as a CCD and a CMOS.

  The charge storage type imaging device has a plurality of pixels, and each pixel includes a photoelectric conversion charge storage portion such as a photodiode. The charges accumulated by the photoelectric conversion charge accumulation unit according to the amount of incident light are transferred to the outside of the photoelectric conversion charge accumulation unit, and an electrical signal corresponding to the transferred charge amount is output to the outside of the image sensor. The imaging device generates image data according to a pixel signal based on an electrical signal output from the imaging element, and performs a focus detection operation.

  In general, when the charge accumulated in the photoelectric conversion charge storage unit is transferred to the outside of the photoelectric conversion charge storage unit, there is a phenomenon that a part of the charge remains in the photoelectric conversion charge storage unit due to incomplete transfer. In order to prevent an adverse effect on image color reproducibility due to such an incomplete transfer phenomenon of accumulated charges, it is known to add a correction amount that is uniform for all pixels according to the ISO sensitivity to the output signal of the image sensor. (For example, refer to Patent Document 1).

JP 2006-157777 A

  However, the amount of charge remaining in the photoelectric conversion charge storage unit when the charge is transferred from the photoelectric conversion charge storage unit to the outside differs depending on the photoelectric conversion unit of each pixel. Even if the incomplete transfer of accumulated charges in the above-described prior art is corrected, such non-uniformity in the residual charge amount of each pixel is recognized as an image pattern. Therefore, there is a problem that the accuracy of the pixel signal output from the image sensor is not necessarily high.

  In the imaging device according to the first aspect, a plurality of pixels are arranged, and each of the plurality of pixels holds a charge accumulation unit that accumulates a charge corresponding to the amount of incident light and a charge transferred from the charge accumulation unit. An image sensor having a signal output unit that outputs a pixel signal corresponding to a transfer charge amount transferred from the charge storage unit to the charge storage unit, and each of the plurality of pixels from the charge storage unit. Storage means for storing incompletely transferred charge amount information corresponding to the incompletely transferred charge amount remaining in the charge accumulation unit during charge transfer to the charge holding unit for each pixel corresponding to the charge accumulation unit, and a signal output unit And a correction unit that corrects the output pixel signal based on the incomplete transfer charge amount information stored in the storage unit.

  ADVANTAGE OF THE INVENTION According to this invention, the precision of the pixel signal which the image pick-up element which an imaging device has can output can be raised.

It is a cross-sectional view which shows the structure of the digital still camera of 1st Embodiment. It is a figure which shows the focus detection area on the imaging | photography screen set to the scheduled image formation surface of an interchangeable lens. It is a front view which shows the detailed structure of an image pick-up element. It is a figure which shows the relationship of a pair of focus detection light beam which arrives at each focus detection area from a pair of ranging pupil. FIG. 6 is a conceptual diagram of a circuit configuration of an image sensor, and a block diagram illustrating a flow of correction processing of a focus detection pixel signal in the body drive control device. It is a detailed circuit diagram of each pixel. It is a figure which shows the cross-section of an image pick-up element. It is an operation | movement timing chart of an image pick-up element. It is an electric potential distribution diagram showing operation of an imaging pixel and a focus detection pixel. It is a flowchart which shows the imaging operation of a digital still camera. It is a graph which shows the relationship between the electric charge amount accumulate | stored in the photoelectric conversion charge storage part of the focus detection pixel, and the signal value of a pixel signal. It is a graph which shows the relationship between the electric charge amount information proportional to the electric charge amount accumulate | stored in the photoelectric conversion electric charge accumulation | storage part of a focus detection pixel, and the signal value of a pixel signal. It is a graph which shows the relationship between charge amount information and the signal value of a pixel signal in the case of correcting sensitivity non-uniformity in addition to incomplete transfer correction.

--- First embodiment ---
A lens interchangeable digital still camera will be described as an example of the imaging apparatus according to the first embodiment. FIG. 1 is a cross-sectional view illustrating a configuration of a digital still camera 201 according to the first embodiment. A digital still camera 201 according to the present embodiment includes an interchangeable lens 202 and a camera body 203, and the interchangeable lens 202 is attached to the camera body 203 via a mount unit 204. An interchangeable lens 202 having various photographing optical systems can be attached to the camera body 203 via a mount unit 204.

  The interchangeable lens 202 includes a lens 209, a zooming lens 208, a focusing lens 210, a diaphragm 211, a lens drive control device 206, and the like. The lens drive control device 206 includes a microcomputer (not shown), a memory, a drive control circuit, and the like. The lens drive control device 206 performs drive control for adjusting the focus of the focusing lens 210 and adjusting the aperture diameter of the aperture 211, and detecting the states of the zooming lens 208, the focusing lens 210, and the aperture 211, and the like. In addition, lens information is transmitted and camera information (defocus amount, aperture value, etc.) is received by communication with a body drive control device 214 described later. The aperture 211 forms an aperture having a variable aperture diameter at the center of the optical axis in order to adjust the amount of light and the amount of blur.

  The camera body 203 includes an imaging element 212, a body drive control device 214, a liquid crystal display element drive circuit 215, a liquid crystal display element 216, an eyepiece lens 217, a nonvolatile memory 218, a memory card 219, and the like. In the imaging device 212, imaging pixels are two-dimensionally arranged, and focus detection pixels are arranged at portions corresponding to the focus detection positions. As will be described later, the nonvolatile memory 218 stores output information of the focus detection pixel, that is, correction information for correcting the focus detection signal for each focus detection pixel. Based on the correction information stored in the nonvolatile memory 218, the body drive control device 214 performs correction processing described later on the focus detection signal.

  The body drive control device 214 includes a microcomputer, a memory, a drive control circuit, and the like. The body drive control device 214 repeatedly performs drive control of the image sensor 212, readout of the image signal and focus detection signal, focus detection calculation based on the focus detection signal, and focus adjustment of the interchangeable lens 202, and processing of the image signal. Also performs recording, camera operation control, etc. The body drive control device 214 communicates with the lens drive control device 206 via the electrical contact 213 to receive lens information and send camera information.

  The liquid crystal display element 216 functions as an electric view finder (EVF). The liquid crystal display element driving circuit 215 displays a through image on the liquid crystal display element 216 based on the image signal read from the image sensor 212, and the photographer can observe the through image through the eyepiece 217. The memory card 219 is an image storage that stores image data generated based on an image signal captured by the image sensor 212.

  A subject image is formed on the light receiving surface of the image sensor 212 by the light beam that has passed through the interchangeable lens 202. This subject image is photoelectrically converted by the image sensor 212, and an image signal and a focus detection signal are sent to the body drive control device 214.

  The body drive control device 214 has an imaging control function and a focus detection control function, as will be described later with reference to FIG. The body drive control device 214 calculates the defocus amount based on the focus detection signal from the focus detection pixel of the image sensor 212 and sends this defocus amount to the lens drive control device 206. The body drive control device 214 processes the image signal from the image sensor 212 to generate image data, stores the image data in the memory card 219, and transmits the through image signal from the image sensor 212 to the liquid crystal display element drive circuit 215. The through image is displayed on the liquid crystal display element 216. Further, the body drive control device 214 sends aperture control information to the lens drive control device 206 to control the aperture of the aperture 211.

  The lens drive controller 206 updates the lens information according to the focusing state, zooming state, aperture setting state, aperture opening F value, and the like. Specifically, the positions of the zooming lens 208 and the focusing lens 210 and the aperture value of the aperture 211 are detected, and lens information is calculated according to these lens positions and aperture values, or prepared in advance. Lens information corresponding to the lens position and aperture value is selected from the look-up table.

  The lens drive control device 206 calculates a lens drive amount based on the received defocus amount, and drives the focusing lens 210 to the in-focus position according to the lens drive amount. Further, the lens drive control device 206 drives the diaphragm 211 in accordance with the received diaphragm value.

  FIG. 2 is a diagram showing a focus detection position (focus detection area) on a scheduled imaging plane of the interchangeable lens 202, that is, a shooting screen set on the imaging plane. An example of a region (focus detection area, focus detection position) where an image is sampled on a shooting screen at the time of detection is shown. In this example, focus detection areas 101 to 103 are arranged at the center and three locations above and below the rectangular shooting screen 100. Focus detection pixels are linearly arranged in the longitudinal direction of the focus detection area indicated by a rectangle.

  FIG. 3 is a front view showing a detailed configuration of the image sensor 212, and shows an enlarged vicinity of the focus detection area 101 on the image sensor 212. In the imaging element 212, the imaging pixels 310 are densely arranged in a two-dimensional square lattice, and focus detection pixels 313 and 314 for focus detection are linearly arranged in a vertical direction at positions corresponding to the focus detection area 101. Adjacently arranged alternately. The configuration in the vicinity of the focus detection areas 102 and 103 is the same as the configuration shown in FIG.

  As shown in FIG. 3, the imaging pixel 310 includes a microlens 10, a photoelectric conversion unit 11, and a color filter (not shown). The color filter includes three types of red (R), green (G), and blue (B), and has spectral sensitivity characteristics corresponding to each color. In the image pickup device 212, image pickup pixels 310 having respective color filters are arranged in a Bayer array.

  As shown in FIG. 3, the focus detection pixel 313 includes the microlens 10 and the photoelectric conversion unit 13, and the photoelectric conversion unit 13 has a semicircular shape. Further, the focus detection pixel 314 includes the microlens 10 and the photoelectric conversion unit 14 as illustrated in FIG. 3, and the photoelectric conversion unit 14 has a semicircular shape. The focus detection pixels 313 and the focus detection pixels 314 are alternately arranged in the vertical direction in the focus detection areas 101 to 103 as shown in FIGS. In this focus detection pixel array, the photoelectric conversion unit 13 of the focus detection pixel 313 is arranged at the upper half position of the microlens 10, and the photoelectric conversion unit 14 of the focus detection pixel 314 is arranged at the lower half position of the microlens 10. Is done.

  Since the focus detection pixels 313 and 314 are not provided with a color filter to increase the amount of light, the focus detection pixels 313 and 314 have a spectral sensitivity of a photodiode (described later) that performs photoelectric conversion, and an infrared cut filter (not shown). ) Shows the spectral sensitivity characteristics combined with the spectral sensitivity characteristics. That is, the focus detection pixels 313 and 314 exhibit spectral sensitivity obtained by adding the spectral sensitivity characteristics of the green pixel, the red pixel, and the blue pixel. The light wavelength region exhibiting high sensitivity includes the light wavelength region in which each color filter exhibits high sensitivity in each of the green pixel, the red pixel, and the blue pixel.

  The focus detection pixels 313 and 314 for focus detection are arranged in a column in which the blue pixel and the green pixel of the imaging pixel 310 are to be arranged. The focus detection pixels 313 and 314 for focus detection are arranged in the column where the blue pixel and the green pixel of the imaging pixel 310 are to be arranged in order to obtain an image signal for imaging at the position of the focus detection pixel. This is because when an interpolation error occurs in the interpolation process, the blue pixel interpolation error is less conspicuous than the red pixel interpolation error due to human visual characteristics.

  The photoelectric conversion unit 11 of the imaging pixel 310 is designed so as to receive all the light beams passing through the exit pupil diameter (for example, F1.0) of the brightest interchangeable lens 202 via the microlens 10. Further, the photoelectric conversion units 13 and 14 of the focus detection pixels 313 and 314 receive all light beams passing through a predetermined region (for example, F2.8) of the exit pupil of the interchangeable lens 202 via the microlens 10. Designed to shape.

  FIG. 4 shows a configuration of a focus detection optical system of a pupil division type phase difference detection method using a microlens. The focus detection pixel portion is shown in an enlarged manner. In the focus detection pixels 313 and 314 arranged in the focus detection area 101 in the center of the screen in FIG. 2, the microlens 10 is arranged in front of the photoelectric conversion units 13 and 14, and the shape of the photoelectric conversion units 13 and 14 is formed by the microlens 10. Is projected forward. The photoelectric conversion units 13 and 14 are formed on a semiconductor circuit substrate, and the microlens 10 is integrally and fixedly formed thereon by a semiconductor image sensor manufacturing process. 4, the optical axis 91 of the interchangeable lens, the micro lenses 10a, 10b, 10c and 10d, the photoelectric conversion units 13a, 14a, 13b and 14b, the focus detection pixels 313a, 314a, 313b and 314b, and the focus detection light beam 73, 74, 83 and 84 are represented. In FIG. 4, the exit pupil 90 is set at a position of a distance d forward from the microlenses 10a, 10b, 10c, and 10d arranged on the planned imaging plane of the interchangeable lens 202 of FIG. This distance d is the curvature and refractive index of the microlenses 10a, 10b, 10c and 10d, and the distances between the microlenses 10a, 10b, 10c and 10d and the corresponding photoelectric conversion units 13a, 14a, 13b and 14b. Depends on etc. This distance d is referred to herein as a distance measuring pupil distance.

  The region 93 is a region determined by projecting the photoelectric conversion units 13a and 13b by the microlenses 10a and 10c. In FIG. 4, the region 93 is shown as an elliptical region for easy understanding, but the shape of the photoelectric conversion unit is actually an enlarged projection shape. Similarly, the region 94 is a region determined by projecting the photoelectric conversion units 14a and 14b by the microlenses 10b and 10d. In this specification, the regions 93 and 94 are called distance measuring pupils, respectively. In FIG. 4, the regions 93 and 94 are shown as elliptical regions for easy understanding, but actually the photoelectric conversion units 13a, 14a, 13b, and 14b are enlarged and projected.

  In FIG. 4, four focus detection pixels 313a, 313b, 314a, and 314b adjacent to the photographing optical axis 91 are schematically illustrated. In the other focus detection pixels in the focus detection area 101 and also in the focus detection pixels in the focus detection areas 102 and 103 at the periphery of the screen, the photoelectric conversion unit arrives at each microlens from the corresponding distance measurement pupils 93 and 94, respectively. It is configured to receive the luminous flux to be received. The arrangement direction of the focus detection pixels is made to coincide with the arrangement direction of the pair of distance measuring pupils, that is, the arrangement direction of the pair of photoelectric conversion units.

  The microlenses 10a to 10d are disposed in the vicinity of the planned imaging plane of the interchangeable lens 202 in FIG. The shapes of the photoelectric conversion units 13a, 13b, 14a, and 14b disposed behind the microlenses 10a to 10d are projected onto the exit pupil 90 that is separated from the microlenses 10a to 10c by the distance measurement pupil distance d. The projection shape forms distance measuring pupils 93 and 94. That is, on the exit pupil 90 at the projection distance d, the distance measuring pupils 93 formed by the projection shapes of the photoelectric conversion units 13a and 13b of the focus detection pixels 313a and 313b coincide with each other, and the focus detection pixels 314a and 314b The relative positional relationship between the microlens and the photoelectric conversion unit in each focus detection pixel is determined so that the distance measuring pupils 94 formed by the projection shapes of the photoelectric conversion units 14a and 14b coincide with each other, and thereby each focus detection pixel. The projection direction of the photoelectric conversion unit is determined.

  The photoelectric conversion unit 13a outputs a signal corresponding to the intensity of the image formed on the microlens 10a by the light beam 73 passing through the distance measuring pupil 93 and traveling toward the microlens 10a. Similarly, the photoelectric conversion unit 13b outputs a signal corresponding to the intensity of the image formed on the microlens 10c by the light beam 83 passing through the distance measuring pupil 93 and traveling toward the microlens 10c. In addition, the photoelectric conversion unit 14a outputs a signal corresponding to the intensity of the image formed on the microlens 10b by the light beam 74 passing through the distance measuring pupil 94 and traveling toward the microlens 10b. Similarly, the photoelectric conversion unit 14b outputs a signal corresponding to the intensity of the image formed on the microlens 10d by the light beam 84 that passes through the distance measuring pupil 94 and travels toward the microlens 10d.

  A large number of the above-described two types of focus detection pixels are arranged in a straight line, and the output of the photoelectric conversion unit of each pixel is collected into a pair of output groups corresponding to the distance measurement pupil 93 and the distance measurement pupil 94, thereby the distance measurement pupil 93. Further, information on the intensity distribution of the pair of images formed on the pixel array by the pair of focus detection light beams that respectively pass through the distance measuring pupil 94 is obtained. By applying an image shift detection calculation process (correlation calculation process, phase difference detection process) to this information, an image shift amount of a pair of images by a so-called pupil division type phase difference detection method is detected. Furthermore, by performing a conversion operation according to the center-of-gravity interval of the pair of distance measuring pupils with respect to the image shift amount, the current image plane (the position on the microlens array) on the planned image plane (the position of the micro lens array) The deviation (defocus amount) of the actual imaging plane at the focus detection position is calculated.

  FIG. 5 is a conceptual diagram of the circuit configuration of the image sensor 212 and a block diagram showing a flow of correction processing of the focus detection pixel signal in the body drive control device 214.

  The image sensor 212 is configured as a CMOS image sensor, for example. The circuit configuration of the image sensor 212 will be described in a simplified manner with a layout of 8 pixels in the horizontal direction and 4 pixels in the vertical direction. FIG. 5 is drawn corresponding to the focus detection area 101 in the vertical direction of FIG. 2, and the focus detection pixels 313 and 314 are arranged in the same column in the vertical direction.

  The fourth column is a column in which focus detection pixels 313 and 314 are arranged in the vertical direction, and the two central focus detection pixels 313 and 314 (indicated by ◯) represent a plurality of focus detection pixels, Upper and lower imaging pixels 310 (indicated by □) represent a plurality of imaging pixels arranged above and below the plurality of focus detection pixels.

  The other columns except for the fourth column are columns in which only the imaging pixels 310 (indicated by □) are arranged, and only from the imaging pixels arranged on the left and right of the column in which the plurality of focus detection pixels 313 and 314 are arranged. Represents the column.

  The imaging pixel 310 and the focus detection pixels 313 and 314 have, as a basic configuration, a photodiode PD that is a photoelectric conversion charge accumulation unit that generates and accumulates charges according to the amount of received light, and charges transferred from the photodiode PD. A floating diffusion (floating diffusion layer) FD that is a charge holding unit that temporarily holds the pixel signal for conversion into a pixel signal, and a signal output that outputs a pixel signal corresponding to the amount of charge transferred from the photodiode PD to the floating diffusion FD And an amplifying MOS transistor AMP (amplifier).

  The line memory 320 is a buffer that samples and holds pixel signals of pixels for one row and temporarily holds them.

  Output of pixel signals from the imaging pixel 310 and the focus detection pixels 313 and 314 is independently controlled for each row by control signals φS1 to φS4, φT1 to φT4, and φR1 to φR4 generated by the vertical scanning circuit 502. The charges accumulated in the photodiode PD of the imaging pixel 310 and the focus detection pixels 313 and 314 are transferred to the floating diffusion FD by control signals φT1 to φT4 that rise in synchronization with the rise of the control signals φS1 to φS4.

  The amplification MOS transistor AMP of each pixel outputs a pixel signal corresponding to the amount of charge transferred from the photodiode PD to the floating diffusion FD. Accordingly, the pixel signals of the pixels in the row selected by the control signals φS1 to φS4 are output to the vertical signal line 501.

  The pixel signals in the same row output to the vertical signal line 501 are sampled and held based on a control signal φH1 that is issued from the vertical scanning circuit 502 in synchronization with the control signals φS1 to φS4.

  The pixel signals held in the line memory 320 are sequentially transferred to the output circuit 330 by the control signals φV 1 to φV 8 generated by the horizontal scanning circuit 503, amplified by the amplification set by the output circuit 330, and output from the image sensor 212. Output to the outside.

  The photodiode PD and the floating diffusion FD of the imaging pixel 310 and the focus detection pixels 313 and 314 are control signals generated by the vertical scanning circuit 502 in synchronization with the fall of the control signals φS1 to φS4 after the pixel signal is sampled and held. It is reset by φR1 to φR4, and then charge accumulation for the next pixel signal output is started at the fall of the control signals φT1 to φT4.

  The pixel signal held in the line memory 320 is reset in synchronization with the rise of the control signals φS1 to φS4.

  The output circuit 330 can amplify the pixel signal with different amplification degrees, and the amplification degree is set by a sensitivity setting device 2141 included in the body drive control device 214. The sensitivity setting device 2141 sets the amplification degree by manual setting or automatic setting according to the brightness.

  The pixel signal output from the output circuit 330 is AD converted into pixel data (pixel signal) of a digital signal value by an AD conversion device 2142 included in the body drive control device 214. FIG. 5 shows processing of pixel data (pixel signal) of the focus detection pixels 313 and 314. The pixel data (pixel signal) of the imaging pixel 310 is processed according to the conventional technique in a processing path different from the processing path shown in FIG. 5 after the AD conversion process.

  In the non-volatile memory 218, correction information corresponding to the incomplete transfer charge amount indicating the remaining charge amount remaining in the photodiode PD at the time of charge transfer from the photodiode PD of each focus detection pixel 313 and 314 to the floating diffusion FD. And position information (row address and column address) of the focus detection pixels 313 and 314 on the image sensor 212, that is, focus detection pixel position information is stored in pairs.

  When the pixel signals of the focus detection pixels 313 and 314 are sent from the AD converter 2142 to the correction device 2143 included in the body drive control device 214, the focus detection pixels 313 and 314 are output according to the output timing of the pixel signals. The focus detection pixel position information is determined. Based on the focus detection pixel position information, the correction device 2143 reads correction information corresponding to the incomplete transfer charge amount stored in the nonvolatile memory 218 in pairs with the focus detection pixel position information from the nonvolatile memory 218. The correction device 2143 multiplies the correction information by a conversion amplification factor including a coefficient (amplification degree) corresponding to the sensitivity setting, and then adds it to the pixel data (pixel signal) of each focus detection pixel 313 and 314, thereby The pixel data (pixel signal) of the focus detection pixels 313 and 314 is corrected. The corrected pixel data (pixel signal) of the focus detection pixels 313 and 314 is subjected to focus detection processing by the focus detection device 2144 included in the body drive control device 214.

  FIG. 6 is a detailed circuit diagram of the image pickup pixel 310 and the focus detection pixels 313 and 314 of the image pickup element 212 shown in FIG. 5, and the photoelectric conversion charge storage unit is configured by a photodiode PD. The photodiode PD and the floating diffusion FD (floating diffusion layer) are connected via a MOS transistor 511 controlled by a control signal φTn (φT1 to φT4). The charge generated by the photodiode PD is transferred to the floating diffusion FD during the period when the MOS transistor 511 is turned on by the control signal φTn (φT1 to φT4). The floating diffusion FD is connected to the gate of the amplification MOS transistor AMP (amplifier). The amplification MOS transistor AMP outputs a pixel signal corresponding to the amount of charge transferred to the floating diffusion FD.

  The floating diffusion FD is connected to the power supply voltage Vdd via the reset MOS transistor 510. When the reset MOS transistor 510 is turned on by the control signal φRn (φR1 to φR4), the charge accumulated in the floating diffusion FD is cleared and the reset state is set. If the MOS transistor 511 is turned on by the control signal φTn (φT1 to φT4) while the reset MOS transistor 510 is turned on by the control signal φRn (φR1 to φR4), the charge remaining in the photodiode PD is cleared.

  The output of the amplification MOS transistor AMP is connected to the vertical output line 501 via the row selection MOS transistor 512. When the row selection MOS transistor 512 is turned on by the control signal φSn (φS1 to φS4), the output of the amplification MOS transistor AMP is output to the vertical output line 501.

  FIG. 7 is a diagram illustrating a cross-sectional structure of the imaging element 212 corresponding to the detailed circuit diagram of the imaging pixel 310 of the imaging element 212 illustrated in FIG. 6.

  An embedded photodiode PD composed of a P layer and an N + layer is formed on a P-type semiconductor substrate, and a floating diffusion FD composed of an N + layer is formed next to the embedded photodiode PD. Another N + layer is formed adjacent to the floating diffusion FD, and this N + layer is connected to the power supply voltage Vdd. The floating diffusion FD is connected to the gate of the amplification MOS transistor AMP. A gate 521 of the MOS transistor 511 is disposed between the floating diffusion FD and the photodiode PD, and a control signal φTn is connected to the gate 521. A gate 520 of the MOS transistor 510 is arranged between the floating diffusion FD and the adjacent N + layer, and a control signal φRn is connected to the gate 520.

  FIG. 8 is an operation timing chart of the image sensor 212 shown in FIG. FIG. 9 is a potential distribution diagram showing the operation of the imaging pixel 310 and the focus detection pixels 313 and 314 of the imaging element 212.

  In a CMOS image sensor as an example of the image sensor 212, pixel resetting, exposure, and pixel signal reading are sequentially performed for each row as described below by a so-called rolling shutter operation (line exposure).

  Prior to time t0, the vertical scanning circuit 502 turns off the control signal φS1, turns off the control signal φT1, and turns on the control signal φR1, and charges are accumulated in the photodiode PD. At this time, the pixels in the first row are in the potential distribution state shown in FIG. At this time, the floating diffusion FD and the photodiode PD are separated from each other, the electric charge 920 is accumulated in the photodiode PD, and the floating diffusion FD is reset to the potential of the power supply voltage.

  At time t0, the vertical scanning circuit 502 turns on the control signal φS1, turns on the control signal φT1, and turns off the control signal φR1. The pixels in the first row are selected when the control signal φS1 is turned on, and the charges accumulated in the photodiode PD are transferred to the floating diffusion FD when the control signal φT1 is turned on. A pixel signal corresponding to the amount of charge transferred to the floating diffusion FD is output from the selected pixel in the first row to the vertical signal line 501.

  At this time, the pixels in the first row are in the potential distribution state shown in FIG. 9B, and a pixel signal corresponding to the charge 921 transferred to the floating diffusion FD is output to the vertical signal line 501. Charge 922 remains in the photodiode PD due to incomplete transfer. Since the amount of the electric charge 922 is nonuniform for each pixel (different for each pixel), the pixel signal of each pixel is corrected by the process described later.

  The pixel signal of the first row output to the vertical signal line 501 by the control signal φH1 issued from the vertical scanning circuit 502 at time t1 is temporarily held in the line memory 320. The pixel signals of the pixels in the first row held in the line memory 320 are transferred to the output circuit 330 according to the control signals φV1 to φV8 sequentially issued from the horizontal scanning circuit 503, and are amplified with the amplification degree set by the output circuit 330. And output to the outside of the image sensor 212.

  At the time t2 after the pixel signal of the pixel in the first row is held in the line memory 320, the vertical scanning circuit 502 turns on the control signal φR1 and turns off the control signal φS1, and then controls the control signal φT1 at time t3. Is turned off, the pixels in the first row are reset. That is, from time t2 to time t3, the pixels in the first row are in the potential distribution state shown in FIG. 9C, and the charge 922 remaining in the photodiode PD and the charge 921 transferred to the floating diffusion FD are present. The floating diffusion FD is reset to the power supply voltage by being sucked into the power supply voltage Vdd.

  At time t3, the vertical scanning circuit 502 turns off the control signal φT1, and charge accumulation in the photodiode PD of the pixels in the first row is started. At this time, the pixels in the first row are in the potential distribution state shown in FIG. 9D, and charges generated by the photodiode PD after time t3 are accumulated in the photodiode PD.

  When the output of the pixel signal of the pixel in the first row from the output circuit 330 is completed, the pixel in the second row is selected by the control signal φS2 generated by the vertical scanning circuit 502. The pixel signals of the selected pixels in the second row are output to the vertical signal line 501, held in the line memory 320, and further output from the output circuit 330 to the outside of the image sensor 212. At the same time, the pixels in the second row are reset and the charge accumulation starts in the same manner as the pixels in the first row.

  Subsequently, selection of pixels in the third and fourth rows, holding and outputting of pixel signals, resetting of pixels, and start of charge accumulation in the pixels are performed. When the output of the pixel signals of all the pixels is completed, the operation returns to the first row again and the above operation is repeated periodically.

  In FIG. 8, the period from the rising edge of the control signal φS1 to the rising edge of the next control signal φS1 corresponds to the operation of outputting an image signal for one frame of the imaging operation, that is, one screen. The period from the falling edge of the control signal φTn to the next rising edge of the control signal φTn is the charge accumulation period of the pixel in the nth row. By changing the time t3 of the fall of the control signal φTn, the length of the charge accumulation period is increased. Can be changed.

  FIG. 10 is a flowchart showing an imaging operation of the digital still camera 201 of the present embodiment. Each processing step shown in FIG. 10 is executed by the body drive control device 214. When the power of the digital still camera 201 is turned on by the body drive control device 214 in step S100, the camera operation after step S110 is started. In step S110, the image sensor 214 is set to an operation mode (for example, an operation mode for outputting 60 frames per second) that repeats an imaging operation at a constant cycle. The body drive control device 214 converts the data (pixel signal) of the imaging pixel 310 and the focus detection pixels 313 and 314 for one frame in accordance with the amplification MOS transistor AMP having a predetermined amplification factor and the brightness of the object scene. It is read out from the image sensor 212 via the output circuit 330 in which the amplification degree corresponding to the sensitivity setting is set.

  In step S120, image data based on the data (pixel signal) of the imaging pixel 310 is generated, and a display image based on the image data is displayed on the liquid crystal display element 216.

  In step S121, the incompletely transferred charge amount information of the focus detection pixels 313 and 314 is read from the nonvolatile memory 218.

  In step S122, the incomplete transfer correction data (correction value) of the focus detection pixels 313 and 314 is calculated by multiplying the incomplete transfer charge amount information of the focus detection pixels 313 and 314 by a conversion amplification factor described later. As will be described later, the conversion amplification factor includes a predetermined amplification factor set in the amplification MOS transistor AMP and an amplification factor based on sensitivity when a pixel signal is output from the output circuit 330.

  In step S123, correction is performed by adding incomplete transfer correction data (correction values) of the focus detection pixels 313 and 314 to data (pixel signals) of the focus detection pixels 313 and 314.

  Details of the processing from step S121 to step S123 will be described later.

  In step S130, in the focus detection area selected by the user among the three focus detection areas 101, 102, and 103 shown in FIG. 2, focus detection calculation is performed based on the corrected focus detection pixel data (pixel signal). Calculate the defocus amount. When the reliability of the defocus amount is low or when the defocus amount cannot be calculated, focus detection is impossible.

  In step S140, it is checked whether or not the focus adjustment state is in the vicinity of in-focus, that is, whether or not the calculated absolute value of the defocus amount is within a predetermined value. If it is determined that the focus adjustment state is not in the vicinity of the in-focus state, the process proceeds to step S150, the defocus amount is transmitted to the lens drive control device 206, and the focusing lens 210 of the interchangeable lens 202 is driven to the in-focus position. Then, it returns to step S110 and repeats the operation | movement mentioned above.

  Even when focus detection is impossible, the process branches to this step, a scan drive command is transmitted to the lens drive control device 206, and the focusing lens 210 of the interchangeable lens 202 is scan-driven from infinity to the nearest. Then, it returns to step S110 and repeats the operation | movement mentioned above.

  If it is determined in step S140 that the focus is close, the process proceeds to step S160, and it is determined whether or not a shutter release has been performed by operating a shutter button (not shown). If it is determined that the shutter release has not been performed, the process returns to step S110 and the above-described operation is repeated. On the other hand, if it is determined that the shutter release has been performed, the process proceeds to step S170, where an aperture adjustment command is transmitted to the lens drive control unit 206, and the aperture value of the interchangeable lens 202 is set to the control F value (the F value set by the photographer or F value set automatically). When the aperture control is completed, the image pickup device 212 is caused to perform an image pickup operation with an exposure time (charge accumulation time) corresponding to the subject luminance, and is set from the image pickup pixel 310 and the focus detection pixels 313 and 314 of the image pickup device 212. Data (pixel signal) is read according to the sensitivity.

  In step S180, virtual imaging pixel data at each focus detection pixel position in the focus detection pixel row is obtained by using the data (pixel signals) of the imaging pixels 310 around the focus detection pixels 313 and 314 and the data (pixels) of the focus detection pixels. Signal), and the data of the virtual imaging pixel is used as an image signal at each focus detection pixel position of the focus detection pixel column. As the pixel interpolation process here, for example, the pixel interpolation process disclosed in Japanese Patent Application Laid-Open No. 2009-94881 is performed. In the subsequent step S190, image data (image signal) composed of image data (pixel signal) and interpolated image data is generated, and the generated image data is output to the memory card 219 for storage. Then, it returns to step S110 and repeats the operation | movement mentioned above.

  Details of calculation of the defocus amount in step S130 of FIG. 10 and general image shift detection calculation processing (correlation calculation processing) used for the calculation are disclosed in Japanese Patent Application Laid-Open No. 2010-129783. The defocus amount is calculated by multiplying the shift amount by the conversion coefficient. Note that the conversion coefficient changes according to the aperture diameter (F value) because the center-of-gravity interval of the distance measuring pupil changes according to the aperture diameter.

  Next, the details of the incomplete transfer charge correction process from step S121 to step S123 of FIG. 10 will be described.

  FIG. 11 shows the case where the charge amount accumulated in the photodiode PD (photoelectric conversion charge accumulation unit) of the focus detection pixel is input X, and the data value corresponding to the charge amount, that is, the signal value of the pixel signal is output Y. 4 is a graph showing a relationship between an input X and an output Y.

The signal value Yr when incomplete transfer occurs is expressed by a linear expression (1) of the charge amount X, using the conversion amplification factor a and the incomplete transfer charge amount b when converting the charge amount to a signal value. The relationship is expressed. However, the conversion amplification factor a is obtained by multiplying the amplification factor of the amplification MOS transistor AMP in FIG. 6 and the amplification factor according to the sensitivity setting of the output circuit 330 in FIG. The amount of charge transferred from the photoelectric conversion charge storage unit to the outside is represented by (X−b).
Yr = a · (X−b) (1)

Since the incomplete transfer charge amount b varies for each focus detection pixel, the incomplete transfer charge amount is measured for each focus detection pixel and stored in the nonvolatile memory 218 in advance. The incomplete transfer charge amount for each focus detection pixel is measured as follows, for example. Assuming that the quantization efficiency representing the relationship between the amount of incident light and the amount of generated charge at the focus detection pixel is known and constant for the measurement system, the charge generated when a certain amount of light is incident on the focus detection pixel The amount X1 is known. Based on the signal value Y1 obtained at that time and the conversion amplification factor a, the incomplete transfer charge amount b can be calculated by the following equation (2).
b = X1-Y1 / a (2)

  The incompletely transferred charge amount b obtained by Expression (2) is stored in the nonvolatile memory 218 for each focus detection pixel, and is read out in step S121 of FIG.

In FIG. 11, the signal value Ys when the incomplete transfer has not occurred, that is, when the incomplete transfer charge amount is 0, has a relationship represented by a linear expression of the charge amount X. Specifically, as shown in the equation (3), the signal value Ys is set to the incomplete transfer charge amount b with respect to the signal value Yr when incomplete transfer based on the incomplete transfer charge amount b occurs. It is equal to a value obtained by adding a value obtained by multiplying the conversion amplification factor a.
Ys = a · X = Yr + a · b (3)

Therefore, in step S122 in FIG. 10, the incomplete transfer correction is performed by multiplying the incomplete transfer charge amount b (incomplete transfer charge amount information) by the conversion amplification factor a (conversion coefficient corresponding to the sensitivity) for each focus detection pixel. Data (correction value) is calculated, and in step S123, the incomplete transfer correction data (correction value) is added to the signal value (data) of the pixel signal of each focus detection pixel. The error is corrected. For example, the corrected signal value Y3 is calculated by the following equation (4) with respect to the signal value Y2 before correction, the incomplete transfer charge amount b, and the conversion amplification factor a of a certain focus detection pixel. Here, the conversion amplification factor a is assumed to be the same value as when measuring the incomplete transfer charge amount.
Y3 = Y2 + a · b (4)

Further, since the incomplete transfer charge amount b does not depend on the conversion amplification factor a, the signal of the pixel signal before correction is obtained even when the conversion amplification factor a has a value a1 different from that at the time of measuring the incomplete transfer charge amount. The signal value Y5 of the pixel signal after correction with respect to the value Y4 is calculated by the following equation (5). Note that the measurement of the incompletely transferred charge amount b and the writing to the nonvolatile memory 218 are performed by, for example, mechanical and electrical adjustment performed when the imaging element 212 is replaced or before shipment from the factory.
Y5 = Y4 + a1 · b (5)

  In general, in the case of incomplete transfer in which a part of the charge accumulated in the photoelectric conversion charge accumulation unit of the focus detection pixel remains in the photoelectric conversion accumulation unit during the charge transfer from the photoelectric conversion charge accumulation unit to the outside, Nonuniform fixed pattern noise is superimposed on the data (pixel signal) of the focus detection pixel depending on the pixel. Thereby, an error occurs in the focus detection result. In particular, since imaging is performed with high sensitivity at low luminance, the ratio between the accumulated charge amount and the incompletely transferred charge amount becomes small and the S / N value falls, so that focus detection may not be possible. Even if it is possible to generate high-quality image data by performing various corrections on the image signal read from the image sensor 212, if focus detection is impossible, high-quality image data that is in focus Is not obtained after all. In contrast, in the first embodiment described above, it is possible to perform focus detection well even in a high-sensitivity imaging state by correcting the incomplete transfer charge amount for each focus detection pixel.

---- Modified example ---
(1) In the first embodiment described above, the incomplete transfer charge amount is directly stored in the nonvolatile memory 218 for each focus detection pixel. However, the data stored in the nonvolatile memory 218 is incomplete. As long as there is a proportional relationship with the transfer charge amount, data of a dimension other than the charge amount may be used.

  In FIG. 12, charge amount information proportional to the amount of charge accumulated in the photodiode PD (photoelectric conversion accumulation unit) of the focus detection pixel is input Z, and the signal value of the pixel signal corresponding to the charge amount information is output Y. It is a graph which shows the relationship between the input Z and the output Y when doing.

In general, the signal value Yr of the pixel signal is 1 of the charge amount information Z using the conversion amplification factor α when the charge amount information is converted into the signal value and the charge amount information β corresponding to the incomplete transfer charge amount. The relationship is expressed by the following formula (6). Transfer charge amount information corresponding to the transfer charge amount from the photoelectric conversion charge storage unit to the outside is represented by (Z−β).
Yr = α · (Z−β) (6)

  The charge amount information Z is not a parameter that directly represents the charge amount, but is information that represents an amount proportional to the charge amount. For example, in FIG. 12, charge amount information when an image is captured with an arbitrary amount of light depending on the luminance of the subject, the charge accumulation time, and the aperture value of the optical system is defined as the reference value Z1, and the signal value Y1 of the pixel signal at that time is measured in advance. To do. Further, the signal value Y2 at that time is measured with respect to the charge amount information Z2 when the image is picked up by the half light amount. The half light quantity is obtained by halving the charge accumulation time, so the charge amount information Z2 is equal to half the reference value Z1, that is, Z1 / 2.

Since equation (6) is a straight line passing through two points (Z1, Y1) and (Z1 / 2, Y2), the conversion amplification factor α and the charge information amount β are obtained by the following equations (7) and (8). be able to.
α = 2 · (Y1-Y2) / Z1 (7)
β = Z1 · (Y1-2 · Y2) / (2 · (Y1−Y2)) (8)

  When the conversion amplification factor α is constant regardless of the focus detection pixel, the conversion amplification factor α is stored in advance in the nonvolatile memory 218 as a fixed value. However, since the conversion amplification factor α depends on the subject luminance, several values corresponding to the subject luminance are stored as the conversion amplification factor α. Since the incomplete transfer charge amount information β varies for each focus detection pixel, the incomplete transfer charge amount information β is measured for each focus detection pixel and stored in the nonvolatile memory 218 in advance. When the correction process is performed, the conversion amplification factor α and the incomplete transfer charge amount information β read from the nonvolatile memory 218 are used.

In FIG. 12, when incomplete transfer has not occurred, that is, when the incomplete transfer charge amount information is 0, the signal value Ys has a relationship represented by the primary expression (9) of the next charge amount information Z. Specifically, as shown in Expression (9), the signal value Ys is incompletely transferred charge amount information relative to the signal value Yr when incomplete transfer based on the incompletely transferred charge amount information β occurs. It is equal to a value obtained by adding a value obtained by multiplying β by the conversion amplification factor α.
Ys = α · Z = Yr + α · β (9)

Therefore, incomplete transfer charge amount information β for each focus detection pixel is multiplied by the conversion amplification factor α to calculate incomplete transfer correction data (correction value), and the data is used as the signal value (data) of each focus detection pixel. By adding to, the signal value error due to incomplete transfer is corrected. For example, the corrected signal value Y4 is calculated by the following equation (10) with respect to the signal value Y3 before correction, incomplete transfer charge amount information β, and conversion amplification factor α of a certain focus detection pixel.
Y4 = Y3 + α · β (10)

Further, since the incomplete transfer charge amount information β does not depend on the conversion amplification factor α, the pixel signal before correction is obtained even when the conversion amplification factor α becomes a value α1 different from that at the time of measuring the incomplete transfer charge amount information. The signal value Y6 of the pixel signal after correction with respect to the signal value Y5 is calculated by the following equation (11).
Y6 = Y5 + α1 · β (11)

  In this modification shown above, the value of quantization efficiency is not necessary, and there is no need for strict charge amount measurement, so that incompletely transferred charge amount information can be easily measured.

(2) In the modified example (1) described above, the conversion amplification factor α is assumed to be constant without depending on each focus detection pixel, but actually the conversion amplification factor α also has a different sensitivity for each focus detection pixel. Depending on the sensitivity non-uniformity, it may vary. In such a case, it is preferable to correct the nonuniformity of the conversion factor amplification α corresponding to the nonuniformity of sensitivity.

  FIG. 13 is a graph showing the relationship between the charge amount information Z and the signal value Y when correcting sensitivity non-uniformity in addition to the above-described incomplete transfer correction.

  As described in the description of the modification (1), the conversion amplification factor α of each focus detection pixel is calculated by the equation (7). Therefore, the calculated conversion gain α is non-volatile for each focus detection pixel. Stored in the memory 218 in advance. When performing the correction process, the conversion amplification factor α is read from the nonvolatile memory 218.

When the conversion amplification factor γ common to all focus detection pixels is used, the signal value Ys ′ in which the sensitivity nonuniformity of the incomplete transfer charge amount information β and the conversion amplification factor α is corrected is generally changed to the signal value Yr before correction. On the other hand, it is represented by the following formula (12).
Ys ′ = γ · Z = (γ / α) · Yr + γ · β (12)

Therefore, the incomplete transfer charge amount information β for each focus detection pixel is multiplied by the conversion amplification factor γ to calculate incomplete transfer correction data (correction value), and each data is corrected for sensitivity nonuniformity. By adding to the signal value (data) of the detection pixel, an error due to incomplete transfer and an error due to sensitivity nonuniformity are corrected. For example, for a signal value Y3 before correction of a certain focus detection pixel, incomplete transfer charge amount information β of the focus detection pixel, conversion amplification factor α of the focus detection pixel, and conversion gain γ common to all focus detection pixels Thus, the corrected signal value Y5 is calculated by the following equation (13).
Y5 = (γ / α) · (Y3 + α · β) = (γ / α) · Y3 + γ · β (13)

  According to the equation (13), the non-uniformity correction coefficient (γ) related to the sensitivity non-uniformity of each pixel is added to the signal value (Y3 + α · β) after the incomplete transfer is corrected by the addition processing shown in (9). / Α) is used to correct the sensitivity non-uniformity. Note that the non-uniformity correction coefficient (γ / α) is stored in advance in the nonvolatile memory 218 for each focus detection pixel. By performing arithmetic processing such as Expression (13), errors due to incomplete transfer and errors due to sensitivity nonuniformity can be corrected well without contradiction.

(3) In the embodiment and the modification described above, when the signal value of the pixel signal before correction is 0, the charge amount accumulated in the photoelectric conversion charge accumulation unit is 0 to the maximum value of the incomplete transfer charge amount. There is a possibility of taking any value within the range. In this case, if the incomplete transfer correction data (correction value) corresponding to the uniform incomplete transfer charge amount is added to the signal value 0 before correction to correct, the charge amount truly accumulated in the photoelectric conversion charge accumulation unit Even if is 0 (dark), the signal value of the corrected pixel signal does not become 0.

  In order to reduce such an error, when the signal value of the pixel signal before correction is 0, (i) correction of incomplete transfer charge amount information is not performed, and (ii) incomplete transfer charge amount. The correction amount for information is set to ½ of the correction amount when the signal value before correction is not 0. (iii) The average value of the signal values of the pixel signals after correction of the same type of focus detection pixels adjacent to each other It is preferable to perform any one of the processes such as substitution.

(4) In the embodiment and the modification described above, the signal values of the pixel signals of all the focus detection pixels 313 and 314 are corrected based on the incomplete transfer charge amount information stored for each focus detection pixel; did. However, this is a correction that can be made when the capacity of the nonvolatile memory 218 for storing the incompletely transferred charge amount information can be secured for all focus detection pixels, and the capacity of the nonvolatile memory 218 cannot be secured sufficiently. If so, correction of the incomplete transfer charge amount can be performed only for some focus detection pixels. Some of these limited focus detection pixels are focus detection pixels having a large incomplete transfer charge amount. The nonvolatile memory 218 stores in advance a pair of position information (row address and column address) on the image sensor 212 of the focus detection pixel and incomplete transfer charge amount information corresponding to each of the focus detection pixels. ing. When the signal value of the pixel signal is read from the image sensor 212, the correction device 2143 matches the position of the pixel from which the signal value is read and the position information of the focus detection pixel stored in the nonvolatile memory 218. In this case, the signal value is corrected based on the incomplete transfer charge amount information paired with the position information.

(5) In the embodiment and the modification described above, the signal values of the pixel signals of the focus detection pixels 313 and 314 are corrected based on the incomplete transfer charge amount information stored for each focus detection pixel. . The signal value of the pixel signal of the imaging pixel 310 is not necessarily corrected based on the incomplete transfer charge amount information. However, this is in consideration of the capacity of the nonvolatile memory 218 for storing the incompletely transferred charge amount information and the importance of the correction effect. If the capacity of the nonvolatile memory 218 can be sufficiently secured, the imaging is performed. You may make it correct | amend the signal value of the pixel signal of the pixel 310 based on the incomplete transfer charge amount information memorize | stored for every imaging pixel. For example, by correcting the signal value of the pixel signal of the imaging pixel 310 before step S120 and step S180 in FIG. 10, the incomplete transfer charge amount at the time of low luminance in each of the plurality of imaging pixels 310 is obtained. The roughness of the image based on non-uniformity is also reduced.

(6) In the above-described embodiment and modification, the signal value of the pixel signal is always corrected based on the incompletely transferred charge amount information. However, the effect of non-uniformity of the incomplete transfer charge amount is that the transfer charge amount from the photoelectric conversion charge storage unit to the outside is larger than the incomplete transfer charge amount. When the amplification degree set in the circuit 330 is small, that is, when the sensitivity is low, it can be almost ignored. Accordingly, the correction processing of the signal value of the pixel signal based on the incompletely transferred charge amount information is performed only when the subject luminance is low and the amplification level set in the output circuit is large, that is, high sensitivity. It may be. In this way, the load necessary for the correction process is reduced at high luminance, so that high-speed image processing and focus detection processing can be performed.

(7) In the above-described embodiments and modifications, the image sensor 212 has been described as a CMOS image sensor. However, even when the image pickup device 212 is an image sensor such as a CCD that performs charge transfer reading, a CMOS image sensor and Similar residual charges are generated due to incomplete transfer. Therefore, the present invention can also be applied to a CCD image sensor.

(8) The imaging apparatus according to the present invention is not limited to the digital still camera 201 having the configuration in which the interchangeable lens 202 is attached to the camera body 203 as described above. For example, the present invention can be applied to a lens-integrated digital still camera or a video camera. Furthermore, the present invention can be applied to a small camera module built in a mobile phone, a surveillance camera, a visual recognition device for a robot, an in-vehicle camera, and the like.

10 microlens, 11, 13, 14 photoelectric conversion unit,
73, 74, 83, 84 Focus detection luminous flux, 90 exit pupil, 91 optical axis,
93, 94 Distance pupil,
100 shooting screen, 101, 102, 103 focus detection area,
201 digital still camera, 202 interchangeable lens, 203 camera body,
204 mount unit, 206 lens drive control device,
208 zooming lens, 209 lens, 210 focusing lens,
211 Aperture, 212 Image sensor, 213 Electrical contact,
214 body drive control device, 215 liquid crystal display element drive circuit, 216 liquid crystal display element,
217 eyepiece, 218 non-volatile memory, 219 memory card,
310 imaging pixels, 313, 314 focus detection pixels,
320 line memory, 330 output circuit,
501 vertical signal line, 502 vertical scanning circuit, 503 horizontal scanning circuit,
510 reset MOS transistor, 511 MOS transistor,
512 row selection MOS transistors, 520, 521 gates,
920, 921, 922 charge,
2141 Sensitivity setting device, 2142 AD conversion device, 2143 correction device,
2144 focus detection device

Claims (6)

A plurality of pixels are arranged, and each of the plurality of pixels includes a charge accumulation unit that accumulates charges according to an incident light amount and a charge holding unit that holds charges transferred from the charge accumulation unit, An image sensor having a signal output unit that outputs a pixel signal corresponding to a transfer charge amount transferred from the storage unit to the charge holding unit;
For each of the plurality of pixels, incomplete transfer charge amount information corresponding to the incomplete transfer charge amount remaining in the charge storage unit at the time of charge transfer from the charge storage unit to the charge holding unit is stored in the charge storage unit. Storage means for storing in advance for each corresponding pixel;
An image pickup apparatus comprising: a correction unit that performs correction based on the incomplete transfer charge amount information stored in the storage unit with respect to the pixel signal output from the signal output unit. The imaging device according to claim 1,
Optical for an image formed on the image sensor based on a corrected pixel signal obtained by performing the correction on the pixel signal by the correcting unit for each of some of the plurality of pixels. A focus detection means for detecting the focus adjustment state of the system;
The pixel signal corresponding to the transfer charge amount transferred from the charge storage unit included in each of the remaining pixels of the plurality of pixels is output as an image signal for generating image data by the signal output unit. An imaging device characterized by that. The imaging device according to claim 1 or 2,
The signal output unit includes an output circuit that outputs the pixel signal to the outside of the imaging device, and an amplification MOS transistor that outputs the pixel signal to the output circuit,
The imaging device, wherein the amplification MOS transistor is included in the plurality of pixels. The imaging device according to any one of claims 1 to 3,
The incompletely transferred charge amount information stored in advance by the storage means is the accumulated charge amount when the signal value of the pixel signal represented by the linear expression of the accumulated charge amount by the charge accumulation unit is 0. An image pickup apparatus characterized by the corresponding information. The imaging apparatus according to claim 4,
The signal output unit outputs the pixel signal indicating a signal value obtained by converting the transfer charge amount based on a conversion amplification factor that is a coefficient of the linear equation,
The correction means converts the incomplete transfer charge amount information into a correction value based on the conversion amplification factor, and adds the correction value to the signal value of the pixel signal output by the signal output unit, An imaging apparatus that corrects a pixel signal. The imaging apparatus according to claim 5,
The storage means stores pixel sensitivity non-uniformity information together with the incomplete transfer charge amount information in advance for each pixel,
The correction unit is configured to apply a correction pixel signal obtained by correcting the pixel signal output from the signal output unit based on the incomplete transfer charge amount information stored in the storage unit, to the correction unit. An image pickup apparatus that further performs correction based on the stored sensitivity non-uniformity information.

Images