JP2019091093A - Focus adjustment device - Google Patents

Abstract

To prevent an erroneous operation of focus detection.SOLUTION: A focus adjustment device comprises: an imaging element having a plurality of first focus detection pixels arranged in a first direction and outputting a focus detection signal and a plurality of second focus detection pixels arranged in a second direction different from the first direction and outputting a focus detection signal, the imaging element performing a rolling shutter operation in which reading of the first focus detection pixels and reading of the second focus detection pixels are sequentially performed in the second direction for each row in the first direction; a focus detection unit for detecting the focus state of a photographing optical system by the focus detection signal of the first focus detection pixels and detecting the focus state of the photographing optical system by the focus detection signal of the second focus detection pixels; and a control unit for controlling driving of a diaphragm arranged in the photographing optical system and driving of the photographing optical system in accordance with the focus state detected by the focus detection unit. When the diaphragm is driven, the control unit controls driving of the imaging optical system in accordance with the focus state detected by the focus detection signal of the first focus detection pixels.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a focusing device and an electronic camera.

  There is known an image pickup apparatus including an image pickup element in which an image pickup pixel and a pupil division type focus detection pixel are mixedly mounted (for example, see Patent Document 1). In such an imaging device, in the imaging plane, the pupil division type focus detection pixels are linearly arranged, and the focus adjustment state of the image formed on the focus detection pixel array is detected based on the output of the focus detection pixel array. doing. In addition, a complementary metal oxide semiconductor (CMOS) image sensor is known as an imaging device. In a basic operation method of a CMOS image sensor, image data is read out in time series by a rolling shutter (line exposure sequential readout method).

Unexamined-Japanese-Patent No. 1-216306

  However, when the CMOS sensor is applied to the imaging device described in Patent Document 1, in the CMOS image sensor, the exposure time is shifted for each horizontal line due to the rolling shutter. Therefore, when the exposure condition of the focus detection pixel changes during the rolling shutter operation, each focus detection pixel in the focus detection pixel array outputs a signal under different exposure condition, so that accurate focus detection is performed. You may not be able to

The focusing device includes a plurality of first focus detection pixels arranged in a first direction and outputting a focus detection signal, and a plurality of second focus pixels arranged in a second direction different from the first direction and outputting a focus detection signal. An imaging element that has a detection pixel, and performs a rolling shutter operation in which reading of the first focus detection pixel and the second focus detection pixel is sequentially performed in the second direction for each row in the first direction; A focus detection unit that detects a focus state of a photographing optical system by the focus detection signal of a focus detection pixel and detects a focus state of the photographing optical system by the focus detection signal of the second focus detection pixel; A control unit for controlling the drive of the photographing optical system according to the drive of the diaphragm disposed in the lens and the focus state detected by the focus detection unit, and the control unit is driving the diaphragm , Said first focus inspection Controlling the driving of the photographing optical system by said focus state detected by the focus detection signal of the pixel.
The electronic camera has the above-described focusing device and a recording unit that records the signal of the imaging pixel.

  According to the present invention, it is possible to prevent a malfunction in focus detection even in the case where the aperture condition changes during the rolling shutter operation and the exposure condition changes.

FIG. 1 is a cross-sectional view showing a configuration of a digital still camera according to an embodiment. It is a figure which shows the focus detection position on the imaging | photography screen of an interchangeable lens. It is a front view which shows the detailed structure of an image pick-up element. It is a front view which shows the detailed structure of an image pick-up element. It is a figure which shows the shape of the micro lens of an imaging pixel and a focus detection pixel. It is a front view of an imaging pixel. It is a front view of a focus detection pixel. It is a figure which shows the spectral characteristics of a green pixel, a red pixel, and a blue pixel. It is a figure which shows the spectral characteristic of a focus detection pixel. It is a sectional view of an image pick-up pixel. It is a sectional view of a focus detection pixel. It is a figure for demonstrating the mode of the imaging | photography light beam which an imaging pixel light-receives. It is a figure for demonstrating the mode of the imaging | photography light beam which a focus detection pixel light-receives. It is a figure which simplifies and shows the circuit composition of an image sensor. It is a figure which shows the basic circuit structure with respect to one photoelectric conversion part in an imaging pixel and a focus detection pixel. It is an operation timing chart of an image sensor. 5 is a flowchart showing an imaging operation of the digital still camera. It is a figure which shows the relationship of correlation amount C (k) with respect to shift amount k of a pair of data. It is explanatory drawing in the case of converting image shift amount into defocusing amount. It is a flowchart which shows the detail of defocusing amount arithmetic processing. It is a timing chart which shows the state of iris diaphragm diameter, and the relation between the operation of an image sensor and time progress. It is a front view which shows the detailed structure of an image pick-up element. It is a front view which shows the detailed structure of an image pick-up element. It is a front view of a focus detection pixel. It is a sectional view of a focus detection pixel. It is a figure which shows the focus detection position on the imaging | photography screen of an interchangeable lens. It is a front view which shows the detailed structure of an image pick-up element. It is a front view which shows the detailed structure of an image pick-up element. It is a front view of a focus detection pixel.

  A lens-interchangeable digital still camera will be described as an example of an imaging apparatus according to one embodiment. FIG. 1 is a cross-sectional view showing the configuration of a digital still camera according to an embodiment. The 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 mounted on 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 the mount unit 204.

  The interchangeable lens 202 includes a lens 209, a zooming lens 208, a focusing lens 210, an aperture 211, a lens drive controller 206, and the like. The lens drive control device 206 includes a microcomputer, a memory, a drive control circuit, and the like (not shown). 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 diaphragm 211, and detects the state of the zooming lens 208, the focusing lens 210, and the diaphragm 211. Further, transmission of lens information and reception of camera information (such as defocus amount and aperture value) are performed through communication with a body drive control device 214 described later. The diaphragm 211 forms an aperture having a variable aperture diameter at the center of the optical axis in order to adjust the light amount and the blur amount.

  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 memory card 219, and the like. In the imaging element 212, imaging pixels are two-dimensionally arranged, and focus detection pixels are incorporated in a portion corresponding to a focus detection position (focus detection area). The details of the image sensor 212 will be described later.

  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 an image signal and a focus detection signal, focus detection calculation based on a focus detection signal, and focus adjustment of the interchangeable lens 202. Processing and recording, operation control of the digital still camera 201, and the like are performed. Also, the body drive control device 214 communicates with the lens drive control device 206 via the electrical contact 213 to receive lens information and transmit camera information.

  The liquid crystal display element 216 functions as an electrical view finder (EVF: Electronic View Finder). The liquid crystal display element drive circuit 215 displays the through image by the imaging element 212 on the liquid crystal display element 216, and the photographer can observe the through image through the eyepiece lens 217. The memory card 219 is an image storage that stores an image captured by the image sensor 212.

  An object image is formed on the light receiving surface of the imaging element 212 by the light flux that has passed through the interchangeable lens 202. The 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 calculates the defocus amount based on the focus detection signal from the focus detection pixel of the image sensor 212, and sends the defocus amount to the lens drive control device 206. Further, the body drive control device 214 processes the image signal from the imaging element 212 to generate image data, stores it in the memory card 219, and sends the through image signal from the imaging element 212 to the liquid crystal display element driving circuit 215. Then, 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 perform aperture control of the aperture 211.

  The lens drive control device 206 updates lens information in accordance with the focusing state, the zooming state, the aperture setting state, the 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 diaphragm 211 are detected, and lens information is calculated according to these lens positions and aperture values, or a prepared look-up is made. The lens information according to the lens position and the aperture value is selected from the table.

  The lens drive control device 206 calculates the 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 view showing a focus detection position (focus detection area) on the shooting screen of the interchangeable lens 202, and a focus detection pixel row on the image sensor 212 described later samples an image on the shooting screen when focus is detected. An example of the region (focus detection area, focus detection position) to be displayed is shown. In this example, focus detection areas 101 to 105 are arranged at the center (on the optical axis) and five places in the top, bottom, left, and right of the rectangular shooting screen 100. The focus detection pixels are linearly arranged in the longitudinal direction of the focus detection area indicated by a rectangle. In the focus detection areas 101, 102, and 103, focus detection pixels are arranged in the horizontal direction, and in the focus detection areas 104, 105, focus detection pixels are arranged in the vertical direction.

  3 and 4 are front views showing the detailed configuration of the image sensor 212. FIG. 3 shows details of the pixel array in which the vicinity of the focus detection areas 101, 102 and 103 in FIG. 2 is enlarged, and FIG. 4 shows details of the pixel array in which the vicinity of the focus detection areas 104 and 105 in FIG. Show. In the imaging element 212, imaging pixels 310 are densely arranged in a two-dimensional square lattice shape. The imaging pixel 310 includes red pixels (R), green pixels (G), and blue pixels (B), and is arranged according to the arrangement rule of the Bayer arrangement. In FIG. 4, for focus detection in the vertical direction, focus detection pixels 313 and 314 for vertical focus detection having the same pixel size as the imaging pixel 310 are alternately arranged, and green pixels and blue pixels are continuously arranged alternately. Are arranged continuously on a straight line in the vertical direction. Similarly, in FIG. 3, the focus detection pixels 315 and 316 for horizontal direction focus detection having the same pixel size as the imaging pixels for horizontal direction focus detection alternately alternate the original green pixel and the blue pixel. It is continuously arranged on a horizontal straight line to be arranged.

  FIG. 5 is a view showing the shapes of the microlenses 10 of the imaging pixel 310 and the focus detection pixels 313, 314, 315, and 316. The shapes of the microlenses 10 of the imaging pixel 310 and the focus detection pixels 313, 314, 315, and 316 are originally a shape cut out in a square shape corresponding to the pixel size from the circular microlens 9 larger than the pixel size. . The cross section in the diagonal direction passing through the optical axis of the micro lens 10 and the cross section in the horizontal direction passing through the optical axis of the micro lens 10 have shapes shown in (a) and (b) of FIG.

  The imaging pixel 310 includes a rectangular microlens 10, a photoelectric conversion unit 11 whose light receiving area is limited to a square by a light shielding mask described later, and a color filter (not shown) as shown in FIG. The color filters consist of three types of red (R), green (G) and blue (B), and their spectral sensitivities have the characteristics shown in FIG. In the imaging element 212, imaging pixels 310 provided with respective color filters are Bayer-arranged.

  The focus detection pixels 313, 314, 315, and 316 are provided with a white filter that transmits all visible light in order to perform focus detection for all colors. The spectral sensitivity characteristic of the white filter is shown in FIG. It becomes the characteristic to show. That is, the spectral sensitivity characteristic is obtained by adding the spectral sensitivity characteristics of the green pixel, the red pixel and the blue pixel shown in FIG. 8, and the light wavelength region corresponding to such a spectral sensitivity characteristic is the green pixel, the red pixel and the blue pixel Is inclusive of the light wavelength region which exhibits high spectral sensitivity.

  FIG. 7 is a front view of the focus detection pixels 313, 314, 315, and 316. As shown in FIG. 7A, the focus detection pixel 313 is limited to the upper half of the square (upper half in the case where the square is equally divided by the horizontal line) with the rectangular microlens 10 and the light shielding mask described later. And a white filter (not shown).

  Further, as shown in FIG. 7B, the focus detection pixel 314 has a rectangular micro-lens 10 and a light receiving area in the lower half of the square (the lower half in the case where the square is equally divided by the horizontal line) by the light shielding mask described later. It consists of the restricted photoelectric conversion unit 14 and a white filter (not shown).

  When the focus detection pixels 313 and the focus detection pixels 314 are superimposed and displayed with the microlens 10 as a reference, the photoelectric conversion units 13 and 14 whose light receiving regions are restricted by the light shielding mask are aligned in the vertical direction.

  Further, in FIGS. 7A and 7B, if the remaining portion (broken line portion) obtained by halving the square is added to the portion of the light receiving region obtained by halving the square, a square having the same size as the light receiving region of the imaging pixel 310 Become.

  As shown in FIG. 7C, the focus detection pixel 315 is divided into the left half of the square (the left half when the square is equally divided by the vertical line) by the rectangular microlens 10 and the light shielding mask described later. It consists of the restricted photoelectric conversion unit 15 and a white filter (not shown).

  Further, as shown in FIG. 7D, the focus detection pixel 316 is a right half of a square (a half of a square divided by a vertical line by dividing the light receiving area by a rectangular microlens 10 and a light shielding mask described later). And a white filter (not shown).

  When the front view of the focus detection pixel 315 and the front view of the focus detection pixel 316 are superimposed and displayed with the microlens 10 as a reference, the photoelectric conversion units 15 and 16 whose light receiving regions are limited by the light shielding mask are aligned horizontally. There is.

  Further, in FIGS. 7C and 7D, if the remaining portion (broken line portion) obtained by halving the square is added to the portion of the light receiving region obtained by halving the square, a square having the same size as the light receiving region of the imaging pixel 310 Become.

  FIG. 10 is a cross-sectional view of the imaging pixel 310 when the cross section of the imaging pixel array is taken along a straight line in the vertical direction. In the imaging pixel 310, the light shielding mask 30 is formed in proximity to the photoelectric conversion unit 11 for imaging, and the photoelectric conversion unit 11 receives the light that has passed through the opening 30 a of the light shielding mask 30. A planarization layer 31 is formed on the light shielding mask 30, and a color filter 38 is formed thereon. A planarization layer 32 is formed on the color filter 38, and the microlens 10 is formed thereon. The shape of the opening 30 a is projected forward by the microlens 10. The photoelectric conversion unit 11 is formed on the semiconductor circuit substrate 29.

  FIG. 11 is a cross-sectional view of the focus detection pixels 313 and 314 when a cross section of the focus detection pixel array consisting of the focus detection pixels 313 and 314 is taken along a straight line in the vertical direction. In the focus detection pixels 313 and 314, the light shielding mask 30 is formed closely on the photoelectric conversion units 13 and 14 for focus detection, and the photoelectric conversion units 13 and 14 are light which has passed through the openings 30b and 30c of the light shielding mask 30. Receive light. A planarization layer 31 is formed on the light shielding mask 30, and a white filter 34 is formed thereon. A planarization layer 32 is formed on the white filter 34, and the microlens 10 is formed thereon. The shapes of the openings 30 b and 30 c are projected forward by the microlens 10. The photoelectric conversion units 13 and 14 are formed on the semiconductor circuit substrate 29.

  The structure of the focus detection pixels 315 and 316 is also the same as the structure of the focus detection pixels shown in FIG. 11, except that the structure of the focus detection pixels 313 and 314 is rotated by 90 degrees.

  FIG. 12 is a view for explaining the state of the imaging light flux received by the imaging pixel 310 shown in FIGS. 3, 4 and 10, and a cross section of the imaging pixel array is taken along a straight line in the vertical direction.

  The photoelectric conversion units 11 of all the imaging pixels 310 arranged on the imaging element 212 receive the light flux that has passed through the opening 30 a of the light shielding mask 30 disposed close to the photoelectric conversion unit 11. The shape of the opening 30 a of the light shielding mask 30 is projected by the micro lens 10 of each image pickup pixel 310 on the area 95 common to all image pickup pixels on the exit pupil 90 separated from the micro lens 10 by the distance measuring pupil distance d.

  Therefore, the photoelectric conversion unit 11 of each imaging pixel 310 receives the imaging light beam 71 passing through the area 95 and the microlens 10 of each imaging pixel 310, passes through the area 95, and travels toward the microlens 10 of each imaging pixel 310 A signal corresponding to the intensity of the image formed on each of the microlenses 10 by the light beam 71 is output.

  FIG. 13 is a view for explaining the state of the focus detection light beams received by the focus detection pixels 313 and 314 shown in FIGS. 4 and 11 in comparison with FIG. Taking a cross section of

  The photoelectric conversion units 13 and 14 of all the focus detection pixels arranged on the image pickup device 212 receive the light flux that has passed through the openings 30 b and 30 c of the light shielding mask 30 disposed close to the photoelectric conversion units 13 and 14. Receive light. The shape of the opening 30b of the light shielding mask 30 is a region 93 common to all the focus detection pixels 313 on the exit pupil 90 separated from the microlens 10 by the distance measurement pupil distance d by the microlens 10 of each focus detection pixel 313. It is projected. Similarly, the shape of the opening 30c of the light shielding mask 30 is common to all the focus detection pixels 314 on the exit pupil 90 separated from the microlens 10 by the distance measurement pupil distance d by the micro lenses 10 of the focus detection pixels 314. It is projected to the area 94. The pair of areas 93 and 94 is called a focusing pupil.

  Accordingly, the photoelectric conversion unit 13 of each focus detection pixel 313 receives the focus detection light beam 73 passing through the distance measuring pupil 93 and the microlens 10 of each imaging pixel 310, passes through the distance measuring pupil 93, and A signal corresponding to the intensity of the image formed on each of the microlenses 10 is output by the focus detection light beam 73 directed to the microlenses 10. The photoelectric conversion unit 14 of each focus detection pixel 314 receives the focus detection light beam 74 passing through the distance measurement pupil 94 and the microlens 10 of each image pickup pixel 310, passes through the distance measurement pupil 94, and each image pickup pixel 310. A signal corresponding to the intensity of the image formed on each of the microlenses 10 is output by the focus detection light beam 74 directed to the microlenses 10 of FIG.

  A combined area of the ranging pupils 93 and 94 on the exit pupil 90 through which the focus detection light beams 73 and 74 received by the pair of focus detection pixels 313 and 314 pass is an exit through which the imaging light beam 71 received by the imaging pixel 310 passes. It coincides with the area 95 on the pupil 90. The focus detection light beams 73 and 74 have a complementary relationship with the imaging light beam 71 on the exit pupil 90.

  A large number of the above-described pair of focus detection pixels 313 and 314 are alternately and linearly arranged. By combining the outputs of the photoelectric conversion units 13 and 14 of the focus detection pixels 313 and 314 into a pair of output groups corresponding to the ranging pupil 93 and the ranging pupil 94, the ranging pupil 93 and the ranging pupil 94 are respectively passed Information on the intensity distribution of a pair of images formed by the pair of luminous fluxes on the focus detection pixel array (vertical direction) is obtained. By performing image shift detection calculation processing (correlation calculation processing, phase difference detection processing) described later on this information, the amount of image shift of a pair of images is detected by a so-called pupil division type phase difference detection method. Furthermore, the deviation between the planned imaging surface and the imaging surface at the focus detection position (vertical direction) is performed by performing a conversion operation according to the proportional relationship between the distance between the center of gravity of a pair of distance measuring pupils and the distance measuring pupil distance to the image shift amount. (Defocus amount) is calculated.

  The focus detection light fluxes received by the focus detection pixels 315 and 316 are also rotated by only 90 degrees between the pair of focus detection light fluxes 73 and 74 received by the focus detection pixels 313 and 314, basically the focus detection light flux shown in FIG. Similar to 73 and 74, a pair of distance measurement pupils obtained by rotating the distance measurement pupils 93 and 94 by 90 degrees is set. A large number of pairs of focus detection pixels 315 and 316 are alternately and linearly arranged. By combining the outputs of the photoelectric conversion units 15 and 16 of the focus detection pixels 315 and 316 into a pair of output groups corresponding to a pair of distance measurement pupils, a pair of light beams respectively passing through the pair of distance measurement pupils is a focus detection pixel Information on the intensity distribution of a pair of images formed on the array (horizontally) can be obtained. Based on this information, the deviation (defocus amount) of the predetermined imaging plane and the imaging plane at the focus detection position (horizontal direction) is calculated.

  The imaging element 212 is configured as a CMOS image sensor. FIG. 14 shows a circuit diagram of the image sensor 212.

  The circuit configuration of the image sensor 212 will be simplified into a layout of 8 pixels in the horizontal direction × 4 pixels in the vertical direction. FIG. 14 is drawn corresponding to the horizontal focus detection areas 101, 102, and 103 in FIG. 2, and the focus detection pixels 315 and 316 are arranged in the same row in the horizontal direction. In the vertical focus detection areas 104 and 105, the focus detection pixels 313 and 314 are vertically arranged and arranged in different rows.

  In the second row, focus detection pixels 315 and 316 are arranged. In FIG. 14, four focus detection pixels 315 and 316 in the center indicated by “o” are shown as a representative of the plurality of focus detection pixels, and two imaging pixels 310 (indicated by “□”) on the left and right are illustrated. ) Is shown as a representative of a plurality of imaging pixels arranged on the left and right of the focus detection pixel.

  Only the imaging pixel 310 is arranged in the first, third, and fourth rows. In FIG. 14, the imaging pixels 310 in the first row, the third row, and the fourth row are shown as a representative of a row including only a plurality of imaging pixels above and below the row where the focus detection pixels are arranged.

  In FIG. 14, a line memory 320 is a buffer for sampling and holding pixel signals of pixels in one row and temporarily holding them, and a vertical scanning circuit generates pixel signals of the same row output to the vertical signal line 501. It samples and holds based on the control signal 発 す る H1 to be emitted. The pixel signals held in the line memory 320 are reset in synchronization with the rising edges of the control signals SS1 to ΦS4.

  Outputs of pixel signals from the imaging pixel 310 and the focus detection pixels 315 and 316 are controlled independently for each row by control signals (ΦS1 to SS4) generated by the vertical scanning circuit. The pixel signals of the pixels in the row selected by the control signals (ΦS1 to 4S4) are output to the vertical signal line 501.

  The pixel signals held in the line memory 320 are sequentially transferred to the output circuit 330 by control signals (.PHI.V1 to .PHI.V8) generated by the horizontal scanning circuit, and are amplified by the set amplification degree in the output circuit 330 and externally Output to

  The imaging pixel 310 and the focus detection pixels 315 and 316 are reset by the control signal (ΦR1 to RR4) generated by the vertical scanning circuit after the pixel signal is sampled and held, and the next pixel is generated at the fall of the control signal RR1 to RR4. Start charge accumulation for signal output.

  Control signal φSync is a vertical synchronization signal, and is externally output for each frame. Control signals 信号 S1 to ΦS4 and control signals RR1 to RR4 are also output to the outside.

  FIG. 15 is a detailed circuit diagram of the imaging pixel 310 and the focus detection pixels 315 and 316 of the imaging element 212 shown in FIG. The photoelectric conversion unit is configured by a photodiode (PD). The charge accumulated in PD is accumulated in the floating diffusion layer (floating diffusion: FD). The FD is connected to the gate of the amplification MOS transistor (AMP), and the AMP generates a signal according to the amount of charge stored in the FD.

  The FD portion 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 RRn (ΦR1 to RR3), the charges accumulated in the FD and PD are cleared and the reset state is established.

  The output of 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 SnSn (ΦS1 to SS3), the output of AMP is output to the vertical output line 501.

  FIG. 16 is an operation timing chart of the image sensor 212 shown in FIG. In the CMOS image sensor, driving readout of pixels, that is, reset, exposure, and readout of pixel signals are sequentially performed for each row as follows by so-called rolling shutter operation. In synchronization with the output of signals of all pixels from the imaging element 212 (output of an image signal for one frame), a vertical synchronization signal φSync is issued.

  The imaging pixel 310 in the first row is selected by the control signal SS1 generated by the vertical scanning circuit in synchronization with the vertical synchronization signal φSync, and the pixel signal of the selected imaging pixel 310 is output to the vertical signal line 501. The pixel signals of the first row, which are output to the vertical signal line 501 by the control signal HH1 generated in synchronization with the control signal ΦS1, are temporarily held in the line memory 320. The pixel signals of the imaging pixels 310 in the first row held in the line memory 320 are transferred to the output circuit 330 in accordance with control signals VV1 to ΦV8 sequentially issued from the horizontal scanning circuit, and the amplification factor set in the output circuit 330 Is amplified and output to the outside.

  When transfer of the pixel signal of the imaging pixel 310 in the first row to the line memory 320 is completed, the imaging pixel 310 in the first row is reset by the control signal ΦR1 generated from the reset circuit, and the fall of the control signal RR1 occurs. The charge accumulation next to the imaging pixel 310 in the first row is started.

  When the output from the output circuit 330 of the pixel signal of the imaging pixel 310 in the first row is finished, the imaging pixel 310 and the focus detection pixels 315 and 316 in the second row are selected by the control signal ΦS2 emitted by the vertical scanning circuit. The pixel signal of the selected imaging pixel 310 is output to the vertical signal line 501.

  Thereafter, similarly, the pixel signals of the imaging pixel 310 and the focus detection pixels 315 and 316 in the second row are held, the imaging pixel 310 is reset, the pixel signal is output, and the next charge accumulation is started. Subsequently, holding of pixel signals of the imaging pixels 310 in the third and fourth rows and resetting of the imaging pixels 310, output of pixel signals of the imaging pixels 310, and start of the next charge accumulation are performed. When the output of the pixel signals of all the pixels is finished, the operation returns to the first row again and the above operation is periodically repeated.

  The reset operation of the imaging pixel 310 and the focus detection pixels 315 and 316 in the nth row is performed in the time from the rise to the fall of the control signal φRn, and the exposure of the imaging pixel 310 and the focus detection pixels 315 and 316 in the nth row is performed. The operation is performed in a time (exposure time, accumulation time) from the falling of control signal φRn to the rising of control signal φSn, and the signal readout operation of imaging pixel 310 and focus detection pixels 315 and 316 in the nth row is This is performed in the time from the rise of control signal φSn to the rise of control signal φSn + 1.

  FIG. 17 is a flowchart showing the imaging operation of the digital still camera 201. When the power of the digital still camera 201 is turned on in step S100, the body drive control device 214 starts an imaging operation after step S110. In step S110, the imaging element 212 is set to an operation mode (for example, outputting 60 frames per second) in which the imaging operation is repeated at a constant cycle. Then, all pixel data of one frame is read out. In the subsequent step S120, data obtained by thinning out a part of the data of the imaging pixel 310 is displayed on the liquid crystal display element 216 (live view display). In step S130, focus detection is performed in the five focus detection areas 101 to 105 based on the data of the focus detection pixels 313, 314, 315, and 316, and one defocus amount is finally calculated. When the reliability of the defocus amount is low or when the defocus amount can not be calculated, focus detection becomes impossible. Details of the process of calculating the defocus amount in step S130 will be described later.

  In step S140, it is checked whether it is in the vicinity of the in-focus state, that is, whether or not the calculated absolute value of the defocus amount is within the predetermined value. If it is determined not to be in the vicinity of the in-focus position, 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. Thereafter, the process returns to step S110 to repeat the above-described operation.

  If the focus can not be detected, the process branches to this step, and a scan drive command is sent to the lens drive controller 206 to scan drive the focusing lens 210 of the interchangeable lens 202 from infinity to close range. Thereafter, the process returns to step S110 to repeat the above-described operation.

  If it is determined in step S140 that the camera is in the vicinity of the in-focus state, the process proceeds to step S160, and it is determined whether the shutter release is performed by the operation of the 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, an aperture adjustment command is transmitted to the lens drive control device 206, and the aperture value of the interchangeable lens 202 is controlled to an F value (F set by the photographer or automatically Value). When the aperture control is completed, the image pickup device 212 performs an image pickup operation with an exposure time according to the subject brightness, and image data from the image pickup pixel 310 of the image pickup device 212 and all focus detection pixels 313, 314, 315, 316 read out.

  In step S180, data of virtual imaging pixels at each pixel position of the focus detection pixel column, data of imaging pixels 310 around the focus detection pixels 313, 314, 315, and 316, and focus detection pixels 313, 314, 315, 316 Interpolate pixels based on the data of In the subsequent step S190, image data including the data of the imaging pixel 310 and the data of the interpolated virtual imaging pixel is stored in the memory card 219, and the process returns to step S110 to repeat the above-described operation.

  The body drive control device 214 detects subject brightness in real time according to the output of a photometric sensor (not shown). Depending on the detection result, during the live view display operation period (loop operation from step S110 to step S160), an aperture adjustment command is sent to the lens drive control device 206 so that the pixel signal is at an appropriate level. To adjust the aperture diameter. Therefore, the aperture diameter may change even during the exposure period of one frame.

  Next, details of general image shift detection calculation processing (correlation calculation processing, phase difference detection processing) used in step S130 of FIG. 17 will be described. Although the processing for the focus detection pixel array of one focus detection area is described for simplicity, the processing in the other focus detection areas is the same.

  As for the pair of images detected by the focus detection pixels 313 and 314 or the focus detection pixels 315 and 316, it is possible that the distance measuring pupils are vignetted by the aperture of the lens and the light amount balance is broken. Are subjected to the type of correlation calculation capable of maintaining the image shift detection accuracy.

For a pair of data strings (A11 to A1M and A21 to A2M: M is the number of data) read out from the focus detection pixel row, using the correlation operation equation (1) disclosed in JP 2007-333720 A, The correlation amount C (k) is calculated.
C (k) =. SIGMA. | A1n.times.A2n + 1 + k-A2n + k.times.A1n + 1 | (1)

  In equation (1), the Σ operation is accumulated for n, but the range taken by n is limited to the range in which data of A1n, A1n + 1, A2n + k, A2n + 1 + k exist depending on the image shift amount k. The image shift amount k is an integer and is a relative shift amount in units of data intervals of the data string.

  As shown in FIG. 18A, the calculation result of equation (1) shows that the correlation amount C (k) is minimal at the shift amount where the correlation between the pair of data is high (k = kj = 2 in FIG. 18A). (The smaller the degree, the higher the degree of correlation).

Using the three-point interpolation method according to equations (2) to (5), the shift amount ks which gives the minimum value C (ks) for the continuous correlation amount is determined.
ks = kj + D / SLOP (2)
C (ks) = C (kj)-| D | (3)
D = {C (kj-1) -C (kj + 1)} / 2 (4)
SLOP = MAX {C (kj + 1) -C (kj), C (kj-1) -C (kj)}
(5)

  Whether the shift amount ks calculated by equation (2) is reliable or not is determined as follows. As shown in FIG. 18B, when the degree of correlation between the pair of data is low, the value of the minimum value C (ks) of the interpolated correlation amount becomes large. Therefore, when C (ks) is equal to or greater than the predetermined threshold value, it is determined that the reliability of the calculated shift amount is low, and the calculated shift amount ks is cancelled.

  Alternatively, to normalize C (ks) with the data contrast, the reliability of the calculated shift amount if the value obtained by dividing C (ks) by SLOP, which is a value proportional to the contrast, is equal to or greater than a predetermined value. Is determined to be low, and the calculated shift amount ks is cancelled.

  Alternatively, if the SLOP, which is a value proportional to the contrast, is equal to or less than a predetermined value, it is determined that the subject has low contrast and the reliability of the calculated shift amount is low, and the calculated shift amount ks is cancelled.

  As shown in FIG. 18C, when the correlation degree of a pair of data is low and there is no drop in the correlation amount C (k) between the shift amount range kmin to kmax, the minimum value C (ks) is obtained In such a case, it is determined that focus detection is impossible.

If it is determined that the calculated shift amount ks is reliable, it is converted to the image shift amount shft by equation (6). In equation (6), PY is twice the pixel pitch of the focus detection pixels 313 and 314 or the focus detection pixels 315 and 316 (detection pitch).
shft = PY × ks (6)

The image shift amount calculated by equation (6) is multiplied by a predetermined conversion coefficient Kd to convert it into the defocus amount def. The conversion coefficient Kd corresponds to the opening angle of a pair of luminous fluxes received by the focus detection pixels 313 and 314 or the focus detection pixels 315 and 316, and the distance measuring pupil distance d corresponds to the barycentric distance between the pair of distance measuring pupils. It is the value divided by. The conversion coefficient Kd changes according to the stop aperture diameter because the distance between the centers of gravity of the distance measuring pupils changes according to the stop aperture diameter.
def = Kd x shft (7)

  FIG. 19 shows an actual image with respect to an imaging surface which is an amount of image shift (relative displacement of a pair of images in a direction perpendicular to the optical axis of the optical system) and an amount of defocus (reference surface in the optical axis of the optical system) It is explanatory drawing in the case of converting into the deviation amount of a surface.

Reference numeral 110 denotes an imaging plane, reference numeral 140 denotes an image plane, reference numeral 125 denotes a stop plane, and reference numeral 91 denotes an optical axis. The symbol def indicates the defocus amount (the distance from the imaging surface 110 to the image surface 140), and the distance PO indicates the distance from the imaging surface 110 to the diaphragm surface 125. Positions G1 and G2 are the positions at which the central light fluxes of the pair of focus detection light beams 73 and 74 intersect with the diaphragm surface when the diaphragm F value is Fc, and positions G3 and G4 are the diaphragm F value Fd (<Fc) Represents the position where the central luminous flux of each of the pair of focus detection luminous fluxes 73 and 74 in the case of {circle around (1)} intersects the stop surface. The distance Q1 is the distance between the position G1 and the position G2, the distance Q2 is the distance between the position G3 and the position G4, the symbol S1 is the image shift amount of a pair of images when the F value of the aperture is Fc, and the symbol S2 is This shows the image shift amount of a pair of images when the f-number of the aperture is Fd. The angle θ1 is the opening angle of the central light beam of the pair of focus detection light beams 73 and 74 when the aperture F value is Fc, and the angle θ2 is the opening of the central light beam of the pair of focus detection light beams 73 and 74 when the diaphragm F value is Fd. Suppose it is a horn. Although the distance PO changes in accordance with the type of the interchangeable lens 202, its average distance is set to be approximately equal to the distance-measuring pupil distance d in FIG. When the defocus amount def is smaller than the distance PO (that is, when it can be approximated as PO-def PO PO), the defocus amount def in the case where the aperture F value is Fc is calculated by equation (8) .
def = S1 / (2 · tan (θ1 / 2)) = S1 · PO / Q1 (8)

Accordingly, the conversion coefficient Kd1 when the aperture F value is Fc is expressed by equation (9).
Kd1 = 1 / (2 · tan (θ1 / 2)) = PO / Q1 (9)

Similarly, the defocus amount def and the conversion coefficient Kd2 when the aperture F value is Fd (> Fc) are calculated by the equations (10) and (11).
def = S2 / (2 · tan (θ2 / 2)) = S2 · PO / Q2 (10)
Kd2 = 1 / (2 · tan (θ2 / 2)) = PO / Q2 (11)

  A conversion coefficient Kd corresponding to the f-stop number is stored as lens information on the interchangeable lens 202 side, and when the image shift amount shft calculated with a given f-stop value is converted to the defocus amount def, the stop The transform coefficient Kd corresponding to the F value is used.

  Details of the process of step S130 of FIG. 17 will be described with reference to FIG. As described above, the aperture diameter may change even during operation of one frame of the imaging device. In the CMOS image sensor, if the aperture opening diameter changes during the rolling shutter operation, the exposure timing may differ from row to row, which may cause a problem in focus detection.

  Therefore, in step S200, it is checked whether the aperture diameter has changed during the exposure period when the data of the focus detection pixels 313, 314, 315, and 316 to be used thereafter are acquired. FIG. 21 is an operation timing chart showing the time lapse on the horizontal axis, the state of the stop aperture diameter on the upper stage, and the operation of the imaging device in parallel on the lower stage. In FIG. 21, the aperture diameter changes from F1.4 at time t1 to F5.6 at time t2 over about two frames (frames A and B).

  The imaging element 212 sequentially performs drive readout of all pixels in a frame unit, that is, reset of all pixels, exposure, and pixel signal readout for each row as shown in FIG. In FIG. 21, the number of rows is 10, and a focus detection area composed of focus detection pixels 315 and 316 in the horizontal direction is arranged in the fifth row (indicated by “R” in FIG. 21). A focus detection area composed of focus detection pixels 313 and 314 in the vertical direction is disposed in the line.

  The lens drive control device 206 changes the aperture diameter as shown in FIG. 21 according to a command from the body drive control device 214, but detects the value of the aperture diameter in real time and controls the value of the aperture diameter as body drive control. It feeds back to the device 214. Therefore, the body drive control device 214 monitors the value of the aperture diameter output from the lens drive control device 206 also during the imaging operation, and exposes when the value of the aperture diameter changes by a predetermined value or more during one frame period. It is determined that the aperture diameter has changed during the period. For example, when focus detection is performed using focus detection pixel data read out during the period of frame A (time t3 to t4), the difference between the stop aperture diameter at time t3 and the aperture diameter at time t4 is equal to or greater than a predetermined value If it is determined that there is a change in aperture diameter.

  If it is determined in step S200 that there is no change in the aperture diameter, the defocus amount def in all the five focus detection areas 101 to 105 is calculated in step S210, and among the reliable defocus amounts The defocus amount indicating the closest distance is adopted as the final defocus amount, and the process proceeds to step S140 in FIG.

  As the conversion coefficient Kd at the time of calculating the defocus amount def, the conversion coefficient Kd corresponding to the aperture diameter at the time t3 or t4 is used.

  When it is determined in step S200 that there is a change in the aperture diameter, in step S220, the defocus amount def in the two focus detection areas 104 and 105 in which the focus detection pixels 313 and 314 are arranged in the vertical direction. The calculation is inhibited, and the defocus amount def is calculated only in the three focus detection areas 101 to 103 in which the focus detection pixels 315 and 316 are arranged in the horizontal direction. When the focus detection pixels 313 and 314 are arranged in the vertical direction, the exposure timing and the exposure amount are different for each row when the aperture diameter of the diaphragm changes, and the conversion coefficient Kd is also different for each row. The conversion error at the time of focus amount calculation becomes large. In order to prevent this, when the aperture diameter changes, the calculation of the defocus amount def in the focus detection areas 104 and 105 in the vertical direction is prohibited. On the other hand, when the focus detection pixels 315 and 316 are arranged in the horizontal direction, the exposure timing and the exposure amount become the same in the same row even if the aperture opening diameter changes, so accurate focus detection is possible. However, since the aperture diameter is different for each row, each aperture diameter at the middle point of the exposure time of each row in which the three focus detection areas in which the horizontal focus detection pixels 315 and 316 are arranged are located is detected The image shift amount shft in the three focus detection areas 101 to 103 in the horizontal direction is converted into the defocus amount def according to the conversion coefficient Kd corresponding to the detected aperture diameter.

  For example, the case of converting the image shift amount shft based on the focus detection pixel data of the focus detection pixels 315 and 316 arranged in the fifth row of the image sensor 212 in FIG. 21 into the defocus amount def will be described. The image shift amount shft based on the focus detection pixel data acquired in the frame A uses the conversion coefficient Kd according to the diaphragm aperture diameter Fa detected at the time ta of the middle point of the exposure time of the fifth line of the frame A. The defocus amount is changed to def. The image shift amount shft based on the focus detection pixel data acquired in frame B uses a conversion coefficient according to the aperture diameter Fb detected at time tb at the midpoint of the exposure time of the fifth row of frame B. Is changed to the defocus amount def. In this way, it is possible to calculate the correct defocus amount def based on the focus detection pixel data of the focus detection pixels 315 and 316 arranged in different rows in the horizontal direction.

  In step S220, the defocus amount def is calculated only in the three focus detection areas 101 to 103 in the horizontal direction as described above, and the defocus amount indicating the closest distance among the reliable defocus amounts is finalized. The process proceeds to step S140 in FIG.

  In the embodiment described above, a change in aperture diameter during rolling shutter operation of a CMOS image sensor having focus detection pixels arranged in the horizontal direction (same row) and the vertical direction (same row) is detected. If a change occurs, focus detection based on the signal of the focus detection pixel arranged in the vertical direction is prohibited, so that malfunction in focus detection caused by a change in aperture diameter can be prevented. Also, when there is a change in the aperture diameter, the image shift amount based on the signal of the focus detection pixel arranged in the horizontal direction is determined according to the aperture diameter at the exposure timing when the signal of the focus detection pixel is acquired. Since the conversion factor is used to convert into the defocus amount, it becomes possible to calculate the correct defocus amount regardless of the change in the aperture diameter of the stop.

-Modified example-
<Has a pair of light receiving areas in one focus detection pixel>
In the partial enlarged view of the image sensor 212 shown in FIGS. 3 and 4, an example in which a pair of focus detection pixels 313 and 314 and a pair of focus detection pixels 315 and 316 having one photoelectric conversion unit in each pixel is shown. A pair of photoelectric conversion units may be provided in one focus detection pixel. 22 and 23 are partial enlarged views of the image sensor 212 corresponding to FIG. 3 and FIG. 4, and the focus detection pixels 311 and 312 include a pair of photoelectric conversion units.

  The focus detection pixel 311 shown in FIG. 24 (a) functions as a pair of the focus detection pixel 313 and the focus detection pixel 314 shown in FIGS. 7 (a) and 7 (b), and the focus detection pixel 311 shown in FIG. The detection pixel 312 has a function corresponding to the pair of the focus detection pixel 315 and the focus detection pixel 316 shown in FIGS. 7C and 7D. As shown in FIGS. 24A and 24B, the focus detection pixels 311 and 312 include the microlens 10, a pair of photoelectric conversion units 13 and 14, and a pair of photoelectric conversion units 15 and 16. White filters are disposed in the focus detection pixels 311 and 312, and their spectral sensitivity characteristics are obtained by combining the spectral sensitivity of the photodiode performing photoelectric conversion and the spectral sensitivity characteristics of the infrared cut filter (not shown). The sensitivity characteristic (see FIG. 9) is obtained. That is, the spectral sensitivity characteristic is obtained by adding the spectral sensitivity characteristics of the green pixel, the red pixel, and the blue pixel shown in FIG. 8, and the light wavelength region where the focus detection pixels 311 and 312 exhibit high spectral sensitivity is the green pixel, the red pixel. The pixel and the blue pixel cover the light wavelength region showing high spectral sensitivity.

  FIG. 25 is a cross-sectional view of the focus detection pixel 311 shown in FIG. 24A, in which the light shielding mask 30 is formed closely on the photoelectric conversion units 13 and 14, and the photoelectric conversion units 13 and 14 The light passing through the opening 30 d of the light shielding mask 30 is received. A planarization layer 31 is formed on the light shielding mask 30, and a white filter 34 is formed thereon. A planarization layer 32 is formed on the white filter 34, and the microlens 10 is formed thereon. The shape of the photoelectric conversion units 13 and 14 limited to the opening 30 d by the microlens 10 is projected forward to form a pair of distance measurement pupils. The photoelectric conversion units 13 and 14 are formed on the semiconductor circuit substrate 29.

  The structure of the focus detection pixel 312 is also the same as that of the focus detection pixel shown in FIG. 25 except that the structure of the focus detection pixel 311 is rotated by 90 degrees.

<Focus detection pixel arrangement in the 45 ° diagonal direction>
FIG. 26 is a diagram showing a focus detection position (focus detection area) on the shooting screen of the interchangeable lens 202, and an area where the focus detection pixel array on the imaging device 212 samples an image on the shooting screen at the time of focus detection. An example of (focus detection area, focus detection position) is shown. In this example, the focus detection areas 101 to 105 are arranged at five positions in the center, top, bottom, left, and right on the rectangular shooting screen 100, and the focus detection areas 106 to 109 in the diagonal direction of the shooting screen 100. In the focus detection areas 106 to 109, in the longitudinal direction of the focus detection area indicated by a rectangle, the focus detection pixels are linearly arranged in the diagonally upper right 45 degrees direction or the diagonal left upper direction 45 degrees.

  FIG. 27 and FIG. 28 are front views showing the detailed configuration of the image sensor 212, showing the focus detection areas 106 and 108 and the vicinity of the focus detection areas 107 and 109 on the image sensor 212 in an enlarged manner. In the imaging element 212, imaging pixels 310 are densely arranged in a two-dimensional square lattice shape. The imaging pixels 310 include red pixels (R), green pixels (G), and blue pixels (B), and are arranged according to the arrangement rule of the Bayer arrangement. At positions corresponding to the focus detection areas 106 and 108, the focus detection pixels 323 and 324 having the same pixel size as the imaging pixel 310 and provided with a white filter are alternately alternately provided with green pixels. It is continuously arranged on a straight line in the 45 ° direction. Along with this, at positions corresponding to the focus detection areas 107 and 109, focus detection pixels 325 and 326 having the same pixel size as the imaging pixel 310 and provided with a white filter alternately have natural green pixels continuous alternately. It is continuously arranged on a straight line in the 45-degree direction toward the upper left side to be arranged. The focus detection pixels 323 and 324 and the focus detection pixels 325 and 326 are disposed at pixel positions where green pixels are originally disposed.

  In the focus detection pixel 323, as shown in FIG. 29A, the light receiving region is half of a square by the rectangular microlens 10 and the light shielding mask 30 (upper right in the case where the square is equally divided by the diagonal in the 45.degree. And a white filter (not shown).

  Further, as shown in FIG. 29B, in the focus detection pixel 324, the light receiving area is half of a square by the rectangular micro lens 10 and the light shielding mask 30 (when the square is bisected by the diagonal in the 45.degree. And the white filter (not shown).

  When the focus detection pixel 323 and the focus detection pixel 324 are superimposed and displayed with the microlens 10 as a reference, the photoelectric conversion units 23 and 24 whose light receiving regions are limited by the light shielding mask are aligned in the 45 ° upward slanting direction .

  Further, in FIGS. 29A and 29B, if the remaining portion (broken line portion) obtained by halving the square is added to the portion of the light receiving region obtained by halving the square, a square having the same size as the light receiving region of the imaging pixel 310 Become.

  In the focus detection pixel 325, as shown in FIG. 29C, the light receiving area is half of a square by the rectangular microlens 10 and the light shielding mask 30 (upper left in the case where the square is equally divided by the diagonal in the 45.degree. And a white filter (not shown).

  Further, as shown in FIG. 29D, the focus detection pixel 326 is a rectangular micro lens 10 and a half of a square of a light receiving area with a light shielding mask (a square divided into two by a diagonal in the 45.degree. The lower half) is constituted by the photoelectric conversion unit 26 limited to the lower half, and a white filter (not shown).

  When the focus detection pixel 325 and the focus detection pixel 326 are superimposed and displayed with the microlens 10 as a reference, the photoelectric conversion units 25 and 26 whose light receiving region is limited by the light shielding mask are aligned in the 45 ° direction with an upward left angle. .

  Further, in FIGS. 29C and 29D, if the remaining portion (broken line portion) obtained by halving the square is added to the portion of the light receiving region obtained by halving the square, a square having the same size as the light receiving region of the imaging pixel is obtained. Become.

  In the image sensor 212 having the arrangement of the focus detection areas as shown in FIG. 26, the change in the aperture diameter is detected during the rolling shutter operation of the CMOS image sensor, and the vertical direction is detected if there is a change in the aperture diameter. The focus detection based on the pixel signals of the focus detection pixels 313 and 314 belonging to the focus detection areas 104 and 105 arranged in the above is prohibited. At the same time, focus detection based on the pixel signals of the focus detection pixels 323 to 326 belonging to the focus detection areas 106 to 109 arranged in the oblique direction is also prohibited. This is because the focus detection pixels 323 to 326 belonging to the focus detection areas 106 to 109 arranged in an oblique direction are arranged in different rows from one another. The exposure timing and the exposure amount are different from each other, which makes it difficult to perform accurate focus detection.

  In the embodiment described above, changes in the aperture diameter are detected during the rolling shutter operation of the CMOS image sensor (image sensor 212), and if there is a change in the aperture diameter, the focal points arranged in different rows The focus detection based on the pixel signals of the detection pixels 313, 314, and 323 to 326 was prohibited. However, compared to focus detection based on the signals of the focus detection pixels 315 and 316 arranged in the same horizontal row, based on the pixel signals of the focus detection pixels 313, 314 and 323 to 326 arranged in different rows. The priority of focus detection may be lowered. That is, they are arranged in different rows only when the reliability of focus detection based on the pixel signals of the focus detection pixels 315 and 316 arranged in the same row in the horizontal direction is extremely low or when focus detection is disabled. The focus detection based on the pixel signals of the focus detection pixels 313, 314, and 323 to 326 may be recognized.

  In the embodiment described above, the change in aperture diameter is detected during the rolling shutter operation of the CMOS image sensor (image sensor 212) in which the focus detection pixels are arranged in the vertical direction and the horizontal direction. In this case, focus detection based on pixel signals of the focus detection pixels 313, 314, and 323 to 326 arranged in different rows is prohibited. In focus detection based on pixel signals of the focus detection pixels 315 and 316 arranged in the same row in the horizontal direction, the aperture diameter is detected in synchronization with the exposure timing of the row, and the aperture diameter is detected according to the aperture diameter. Accurate focus detection is made possible by converting the image shift amount shft into the defocus amount def with the conversion coefficient Kd. However, the focus detection pixels 315 and 316 belonging to one focus detection area arranged only in the same row in the horizontal direction detect changes in the aperture diameter during the rolling shutter operation of the CMOS image sensor, and change in the aperture diameter If there is a problem, focus detection may be performed as follows. That is, in focus detection based on pixel signals of the focus detection pixels 315 and 316 arranged in the same row in the horizontal direction, the aperture diameter is detected in synchronization with the exposure timing of the row, and conversion according to the aperture diameter Correct focus detection can also be achieved by converting the image shift amount shft into the defocus amount def with a coefficient Kd.

  In the embodiment described above, an example of a pupil division type focus detection pixel is shown as a focus detection pixel, but the focus detection pixel is not limited to this, and a focus detection pixel using another focus detection method is used. The present invention can also be applied. For example, in a system for detecting image contrast as another focus detection system, the focus detection pixels may be the same as the imaging device, and in the case of detecting contrast in the row direction and column direction, the pupil division type described above The same problem as in the case of using a focus detection pixel occurs.

  That is, when the aperture opening diameter changes during the rolling shutter operation, the focus detection pixels (identical to the imaging pixels) arranged in the column direction have different exposure amounts at different exposure timings, so an accurate contrast evaluation value Can not be calculated. On the other hand, since the focus detection pixels (identical to the imaging pixels) arranged in the row direction have the same exposure amount at different exposure timings, accurate contrast evaluation values can be calculated, and the calculated contrast values are narrowed. If the aperture diameter (exposure amount) is normalized, it becomes possible to compare and evaluate the contrast evaluation values obtained in different frames. Therefore, as in the above-described embodiment, when the aperture diameter changes during the rolling shutter operation, the calculation of the contrast evaluation value based on the pixel signal of the focus detection pixels arranged in the column direction is prohibited, and the row direction By calculating the contrast evaluation value based on the pixel signal of the focus detection pixel arranged in the above, it is possible to prevent the failure of the focus detection operation caused by the change of the aperture diameter during the rolling shutter operation.

  In the embodiment described above, changes in the aperture diameter are detected during the rolling shutter operation of the CMOS image sensor (image sensor 212), and if there is a change in the aperture diameter, the focal points arranged in different rows The focus detection based on the pixel signal of the detection pixel was prohibited. However, in such a case, the focus detection calculation may be performed without being prohibited, and the focus adjustment operation (lens drive) based on the focus detection result may be prohibited.

  In the embodiment described above, changes in the aperture diameter are detected during the rolling shutter operation of the CMOS image sensor (image sensor 212) in the live view display operation, and when there is a change in the aperture diameter, different rows Focus detection based on pixel signals of focus detection pixels arranged in However, if the focus detection operation and the aperture control are simultaneously performed between frames in the continuous shooting operation, the change of the aperture diameter is detected during the rolling shutter operation of the CMOS image sensor between the frames in the continuous shooting operation. If there is a change in the aperture diameter, focus detection based on pixel signals of focus detection pixels arranged in different rows may be prohibited.

  In the embodiment described above, the change in the aperture diameter is detected during the rolling shutter operation of the CMOS image sensor (image sensor 212) in the live view display operation of still image shooting, and there is a change in the aperture diameter. The focus detection based on the pixel signals of the focus detection pixels arranged in different rows was prohibited. However, if the focus detection operation and the aperture control are performed in parallel during moving image shooting, the change in aperture diameter is detected during rolling shutter operation of the CMOS image sensor at the time of moving image shooting, and the change in aperture diameter If there is a problem, focus detection based on pixel signals of focus detection pixels arranged in different rows may be prohibited.

  In the embodiment described above, changes in the aperture diameter are detected during the rolling shutter operation of the CMOS image sensor (image sensor 212), and if there is a change in the aperture diameter, the focal points arranged in different rows Focus detection based on the signal of the detection pixel was prohibited. However, even in the case where a neutral density (ND) filter is mechanically inserted and retracted in the optical path of the photographing optical system in order to adjust the exposure amount of the imaging element 212, the focus detection pixels arranged in different rows are Since different exposure amounts are obtained at different exposure timings, accurate focus detection can not be performed. Therefore, as in the above-described embodiment, when a change in exposure occurs due to the insertion and withdrawal of the ND filter during the rolling shutter operation, the pixel signal of the focus detection pixels arranged in different rows is used. By prohibiting the focus detection, it is possible to prevent the failure of the focus detection operation.

  In the image sensor 212 in the above-described embodiment, the focus detection pixels 313 to 316 and 323 to 326 have white filters, but the same color filter (for example, green filter) as the image pickup pixels 310 is used. The present invention can also be applied.

  In the imaging element 212 in the above-described embodiment, an example in which the imaging pixel 310 is provided with a Bayer-arranged color filter is shown. However, the configuration and arrangement of the color filters are not limited to this, and the present invention can be applied to arrangements other than complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) and arrays other than the Bayer array. It can apply. The present invention can also be applied to a monochrome image pickup device not provided with a color filter.

  In the embodiment described above, no optical element is disposed between the imaging element 212 and the imaging optical system, but it is possible to insert necessary optical elements as appropriate. For example, an infrared cut filter, an optical low pass filter, a half mirror or the like may be provided.

  The imaging device is not limited to the digital still camera configured as described above, in which the interchangeable lens is mounted on the camera body. 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 or the like, a visual recognition device for a surveillance camera or a robot, an on-vehicle camera, and the like.

9, 10 micro lenses,
11, 13, 14, 15, 16, 23, 24, 25, 26 photoelectric conversion units,
29 semiconductor circuit boards,
30 light shielding mask, 30a, 30b, 30c, 30d openings,
31, 32 flattening layers, 34 white filters, 38 color filters,
71 shooting light flux, 73, 74 focus detection light flux,
90 exit pupil, optical axis of 91 interchangeable lens, 93, 94 focusing pupil, 95 area,
100 shooting screen,
101, 102, 103, 104, 105, 106, 107, 108, 109 focus detection areas,
201 digital still camera, 202 interchangeable lens, 203 camera body,
204 mount unit, 206 lens drive control device,
208 zoom lens, 209 lens, 210 focusing lens,
211 aperture, 212 image sensor, 213 electrical contacts,
214 body drive controller,
215 liquid crystal display drive circuit, 216 liquid crystal display, 217 eyepieces,
219 memory card,
310 imaging pixels,
311, 312, 313, 314, 315, 316, 323, 324, 325, 326 focus detection pixels,
320 line memory, 330 output circuits, 501 vertical output lines,
510 Reset MOS transistor, 512 row selection MOS transistor

The present invention relates to a focus adjustment equipment.

A focusing device according to an aspect of the present invention receives a light transmitted through an optical system having a stop and outputs a signal used for focus detection, and includes a plurality of first pixels arranged in a first direction and the first direction A plurality of second pixels arranged in different second directions, a first signal output from the plurality of first pixels, and a second signal output from the plurality of second pixels The image pickup device having a reading unit performing a rolling shutter operation for reading in the second direction for each row, and the at least one of the first signal and the second signal read by the reading unit, A control unit configured to control a position of the optical system at a focusing position at which an image by the optical system focuses on the imaging device, the control unit driving the diaphragm during exposure of the imaging device; The optical system based on the second signal To prohibit the control of the position.

Claims (4)

A plurality of first focus detection pixels arranged in a first direction to output a focus detection signal, and a plurality of second focus detection pixels arranged in a second direction different from the first direction to output a focus detection signal An imaging device that performs a rolling shutter operation in which readout of the first focus detection pixel and the second focus detection pixel is sequentially performed in the second direction for each row in the first direction;
A focus detection unit that detects a focus state of a photographing optical system based on the focus detection signal of the first focus detection pixel and detects a focus state of the photographing optical system based on the focus detection signal of the second focus detection pixel;
A control unit configured to control driving of the diaphragm disposed in the photographing optical system and driving of the photographing optical system according to a focus state detected by the focus detection unit;
The control unit controls the drive of the photographing optical system according to the focus state detected by the focus detection signal of the first focus detection pixel when driving the diaphragm. A focusing device according to claim 1, wherein
The focus adjustment device detects the focus state of the photographing optical system using a value corresponding to the aperture value of the exposure time of the first focus detection pixel when the control unit drives the aperture. A focusing device according to claim 1 or 2, wherein
The imaging device has imaging pixels arranged.
The image pickup element is a focusing device which performs reading of the first and second focus detection pixels and the image pickup pixels sequentially in a second direction for each row in the first direction. A focusing device according to claim 3;
And a recording unit configured to record the signal of the imaging pixel.

Images