JP6399844B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus.

  2. Description of the Related Art In recent years, imaging apparatuses such as electronic cameras that can acquire not only light intensity distribution but also light incident direction and distance information are known.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique capable of pupil focus type focus detection in an imaging apparatus. In Patent Document 1, one pixel has two photodiodes (hereinafter, these are referred to as divided pixels), and each photodiode receives light that has passed through different pupils of the photographing lens by one microlens. Accordingly, by comparing the output signal waveforms from the two photodiodes, it is possible to acquire the pupil division phase difference AF and the distance detection image. Moreover, a normal captured image can be obtained by adding the output signals from the two photodiodes.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique that enables the imaging apparatus to perform distance measurement using a so-called optical travel time method or TOF (Time of Flight) method. In Patent Document 2, one pixel has two floating diffusions and two transfer switches for one photodiode. Then, in synchronization with the pulse timing of the projection light, the two transfer switches are alternately opened and closed to distribute the charge generated by the reflected light from one photodiode to two floating diffusions. The distance to the subject can be estimated from the charge distribution ratio.

JP 2001-124984 A International Publication No. 2007/026777

  However, the focus detection of the pupil division method can speed up the distance measurement compared to the contrast method that uses the contrast of the subject, but it can be used in situations where the depth of field is deep or in the peripheral area of the image. It is difficult to obtain a pupil division phase difference depending on various conditions. Therefore, it may be difficult for the focus detection of the pupil division method to obtain a good distance measurement or distance detection image. On the other hand, in the light travel time method, distance information can be obtained in pixel units up to the periphery of the image. Therefore, suitable distance measurement according to various optical conditions can be performed by appropriately combining the two. However, even in the light transit time method, incident light rays concentrate on the outer photoelectric conversion unit with respect to the optical axis in the peripheral portion of the image, and the light receiving efficiency to the photoelectric conversion unit arranged on the inner side decreases. In other words, the S / N of the photoelectric conversion unit that is difficult for light to enter deteriorates, which affects the distance measurement accuracy and the image quality. Further, such processing of pixels that are not necessarily used can be a burden on the image processing circuit.

  An object of the present invention is to provide an imaging apparatus capable of improving the accuracy and image quality of distance measurement regardless of the area in the imaging element.

  The imaging device of the present invention includes a plurality of microlenses and an imaging element that corresponds to each of the plurality of microlenses and includes a plurality of unit pixels that are two-dimensionally arranged, and each of the plurality of unit pixels includes , First and second photoelectric conversion units that convert light received through the same microlens into electric charges, and first and second photoelectric conversion units that transfer electric charges of the first photoelectric conversion units to different charge storage units, respectively. Two transfer switches, and third and fourth transfer switches that transfer the charges of the second photoelectric conversion unit to different charge storage units, respectively, in the unit pixel in the first region of the image sensor The charge of the first photoelectric conversion unit is transferred by the first transfer switch or the second transfer switch, and the charge of the second photoelectric conversion unit is transferred by the third transfer switch or the fourth transfer. By switch In the unit pixel in the second region of the image sensor, the charge of the first photoelectric conversion unit is not transferred by the first transfer switch or the second transfer switch, and the second pixel is not transferred. The charge of the photoelectric conversion unit is transferred by the third transfer switch or the fourth transfer switch.

  The accuracy and image quality of distance measurement can be improved regardless of the area in the image sensor.

It is a figure which shows the structural example of an imaging device. FIG. 6 is a layout diagram of unit pixels. It is a conceptual diagram in which the light beam emitted from the exit pupil of the photographing lens enters the unit pixel. It is a layout figure which shows the structural example of a unit pixel. It is a circuit diagram which shows the structural example of a unit pixel. It is a figure which shows the structural example of the read-out circuit of an image pick-up element. It is a circuit diagram which shows the structural example of the horizontal signal line by 1st Embodiment. It is a figure which shows the concept of the read division | segmentation pixel by 1st Embodiment. It is a timing chart which shows the 1st drive method. It is a timing chart which shows the 2nd drive method. It is a figure explaining the pulse timing by a light transit time method. It is a timing chart which shows the 3rd drive method. 6 is a flowchart illustrating a method for driving the imaging apparatus. It is a circuit diagram which shows the structural example of the horizontal signal line by 2nd Embodiment. It is a figure which shows the concept of the read division | segmentation pixel by 2nd Embodiment. It is a circuit diagram which shows the structural example of the horizontal signal line by 3rd Embodiment. It is a layout figure which shows the other structural example of a unit pixel.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration example of an imaging apparatus 100 according to the first embodiment of the present invention. The light that has passed through the photographing lens 101 forms an image in the vicinity of the focal position of the photographing lens 101 via the lens diaphragm 204. The microlens array 102 has a plurality of microlenses 1020, is arranged in the vicinity of the focal position of the photographing lens 101, and divides and emits light that has passed through different pupil regions of the photographing lens 101 for each pupil region. The image sensor 103 has a plurality of pixels and is a solid-state image sensor such as a CMOS image sensor or a CCD image sensor. A plurality of pixels are arranged so as to correspond to one microlens 1020. Thereby, the light emitted after being divided for each pupil region by the microlens 1020 is received while maintaining the division information, and is converted into an image signal that can be processed.

  An analog signal processing circuit (AFE) 104 performs correlated double sampling processing, signal amplification, reference level adjustment, analog / digital (A / D) conversion processing, and the like on the image signal output from the image sensor 103. A digital signal processing circuit (DFE) 105 performs digital image processing such as reference level adjustment on the image signal output from the analog signal processing circuit 104.

  The image processing circuit 106 performs correlation calculation, focus detection, predetermined image processing, defect correction, and the like described later on the image signal output from the digital signal processing circuit 105. The memory circuit 107 and the recording circuit 108 are recording media such as a nonvolatile memory or a memory card that records and holds an image signal output from the image processing circuit 106.

  The control circuit 109 drives and controls the entire imaging device such as the photographing lens 101, the imaging element 103, the image processing circuit 106, the operation circuit 110, the display circuit 111, and the light emitting device 112. The operation circuit 110 inputs a signal from an operation member provided in the imaging apparatus 100 and outputs a user command to the control circuit 109. The display circuit 111 displays a captured image, a live view image, various setting screens, and the like. The light emitting device 112 emits light according to a signal PLIGHT (FIGS. 9 and 10) from the control circuit 109.

  Next, the relationship between the photographic lens 101, the microlens array 102, and the image sensor 103, the definition of the pixels, and the principle of focus detection by the pupil division method in the imaging apparatus 100 of this embodiment will be described.

  FIG. 2 is a diagram of the image sensor 103 and the microlens 1020 observed from the direction of the optical axis Z in FIG. In the present embodiment, one unit pixel 200 is provided corresponding to one microlens 1020. The image sensor 103 has a plurality of unit pixels 200 arranged in a matrix. The plurality of unit pixels 200 correspond to the plurality of microlenses 1020, respectively, and are arranged in a two-dimensional matrix. Each of the plurality of unit pixels 200 includes two divided pixels 201A and 201B arranged in the X-axis direction. The divided pixel 201A is disposed on the left of the divided pixel 201B.

  3A and 3B show a state in which light emitted from the photographing lens 101 passes through one microlens 1020 and is received by the unit pixel 200 of the image sensor 103 in a direction perpendicular to the optical axis Z. It is the figure observed from (Y-axis direction). Pupil areas 202 and 203 represent exit pupils when the photographing lens 101 is decomposed into a plurality of areas. As shown in FIG. 3A, when the aperture value of the lens diaphragm 204 is small, the light beam passing through the pupil region 202 passes through the microlens 1020 and is received by the divided pixel 201A. The light beam passing through the pupil region 203 passes through the microlens 1020 and is received by the divided pixel 201B. Accordingly, each of the divided pixels 201A and 201B receives light of an exit pupil region that is a different exit pupil region of the photographing lens 101 and is diagonal to the optical axis.

  Here, a subject image formed by the output signal group of the divided pixels 201A in the plurality of unit pixels 200 is referred to as an A image. Similarly, a subject image formed by the output signal group of the divided pixels 201B in the plurality of unit pixels 200 is defined as a B image. The image processing circuit 106 performs a correlation operation on the A image and the B image, and detects an image shift amount (pupil division phase difference). The image processing circuit 106 can calculate a focal position corresponding to an arbitrary subject position in the image by multiplying the image shift amount by a conversion coefficient determined by the focal position of the photographing lens 101 and the optical system. it can. The control circuit 109 controls the focus of the photographing lens 101 based on the calculated focal position information, thereby enabling autofocus by detecting pupil division phase difference. Further, the image processing circuit 106 can use the A + B image signal for a normal captured image by adding the A image signal and the B image signal to obtain an A + B image signal.

  By the way, as shown in FIG. 3B, for example, when the aperture value of the lens diaphragm 204 is large, the divided pixels 201A and 201B receive light beams on the diagonal side with respect to the optical axis. Light traveling toward 201B is blocked by the lens diaphragm 204. As a result, in the divided pixel 201B, the contribution of the dark component is dominant with respect to the light component, and the accuracy is reduced not only in the distance measurement using the pupil division phase difference but also in the distance measurement using the light travel time method. To do. The purpose of this embodiment is to solve this, and details will be described later.

  FIG. 5 is a circuit diagram illustrating a configuration example of each of the plurality of unit pixels 200. The unit pixel 200 includes a first photodiode (first photoelectric conversion unit) 301A and a second photodiode (second photoelectric conversion unit) 301B. The first photodiode 301A corresponds to the divided pixel 201A, and the second photodiode 301B corresponds to the divided pixel 201B. That is, the first photodiode 301A is arranged on the left side of the second photodiode 301B. Two transfer switches 302A and 302C are connected to the first photodiode 301A, and two transfer switches 302B and 302D are connected to the second photodiode 302B. Floating diffusions 303A to 303D are connected to the transfer switches 302A to 302D, respectively. Reset switches 304A to 304D and source follower amplifiers 305A to 305D are connected to the floating diffusions 303A to 303D, respectively. Select switches 306A to 306D are connected to the source follower amplifiers 305A to 305D, respectively. Here, the drains of the reset switches 304A and 304B and the source follower amplifiers 305A and 305B are connected to the node of the reference potential (VDD) 308. Similarly, the drains of the reset switches 304C and 304D and the source follower amplifiers 305C and 305D are connected to the node of the reference potential (VDD) 308.

  The first photodiode 301A and the second photodiode 301B convert light received through the same microlens 1020 into electric charge. The first transfer switch 302A transfers charges generated in the photodiode 301A to the floating diffusion 303A. The third transfer switch 302B transfers the charge generated in the photodiode 301B to the floating diffusion 303B. The second transfer switch 302C transfers the charge generated in the photodiode 301A to the floating diffusion 303C. The fourth transfer switch 302D transfers the charge generated in the photodiode 301B to the floating diffusion 303D. The transfer switch 302A is controlled by a transfer pulse signal PTXA1 or PTXA2. The transfer switch 302B is controlled by a transfer pulse signal PTXB1 or PTXB2. The transfer switch 302C is controlled by a transfer pulse signal PTXC1 or PTXC2. The transfer switch 302D is controlled by a transfer pulse signal PTXD1 or PTXD2.

  The first transfer switch 302A transfers the charge of the first photodiode 301A to the first floating diffusion (first charge storage unit) 303A. The second transfer switch 302C transfers the charge of the first photodiode 301A to the second floating diffusion (second charge storage unit) 303C. The third transfer switch 302B transfers the charge of the second photodiode 301B to the third floating diffusion (third charge storage unit) 303B. The fourth transfer switch 302D transfers the charge of the second photodiode 301B to the fourth floating diffusion (fourth charge storage unit) 303D. The transfer switches 302A and 302C transfer the charges of the photodiode 301A to different floating diffusions 303A and 303C, respectively. The transfer switches 302B and 302D transfer the charge of the photodiode 301B to different floating diffusions 303B and 303D, respectively.

  The floating diffusions 303 </ b> A to 303 </ b> D are charge-voltage conversion units that temporarily hold charges and convert the held charges into voltage signals. The reset switches 304A to 304D reset the potentials of the floating diffusions 303A to 303D to the reference potential 308, respectively. The reset switches 304A to 304D are controlled by a reset pulse signal PRES.

  The source follower amplifiers 305A to 305D are source follower circuits each composed of a MOS transistor and a reference potential 308, and amplify voltage signals based on the charges held in the floating diffusions 303A to 303D and output them as pixel signals. The select switches 306A to 306D output the pixel signals amplified by the source follower amplifiers 305A to 305D to the vertical output lines 307A to 307D, respectively. As shown in FIG. 6, the vertical output lines 307 </ b> A to 307 </ b> D are shared by the unit pixels 200 in the same column. The select switches 306A to 306D are controlled by a select pulse signal PSEL.

  FIG. 4 is a layout diagram illustrating a configuration example of the unit pixel 200. As shown in FIG. 5, two transfer switches 302A and 302C are connected to both ends of the photodiode 301A, and charges can be transferred by either of the transfer switches 302A and 302C. Similarly, two transfer switches 302B and 302D are connected to both ends of the photodiode 301B, and charges can be transferred by either of the transfer switches 302B and 302D. The transfer switches 302A to 302D are connected to the floating diffusions 303A to 303D, respectively.

  FIG. 6 is a diagram illustrating a configuration example of a readout circuit of the image sensor 103. The imaging element 103 has an imaging surface including a plurality of unit pixels 200 arranged in a matrix. In FIG. 6, the unit pixels 200 are illustrated as a total of 12 units of 4 rows and 3 columns, but in actuality, the unit pixels 200 are composed of millions and tens of millions of unit pixels 200. The unit pixels 200 are arranged according to the Bayer array, and are provided with, for example, red (R), green (G), and blue (B) color filters. Here, an infrared filter or a transparent filter may be formed in order to use infrared light as the projection light of the light emitting device 112 or to increase the light receiving efficiency of reflected light. The vertical shift registers 4011 and 4012 select and drive the unit pixels 200 in each row via a signal line 402 connected to each row. Signals converted by the floating diffusions 303A to 303D of the unit pixel 200 are input to the column circuit 403 through the vertical output lines 307A to 307D, respectively. The signal processed by the column circuit 403 is transferred to the output amplifier 407 through the horizontal output lines 405 and 406 by the horizontal shift register 404.

  Next, the circuit configuration of the column circuit 403 will be described. The clamp capacitor (C0) 408 is connected between the vertical output lines 307A to 307D and the input terminal of the operational amplifier 410. The feedback capacitor (Cf) 409 is connected between the input terminal and the output terminal of the operational amplifier 410. The reference power supply 411 supplies the reference voltage Vref to the operational amplifier 410. The switch 412 is a switch for short-circuiting both ends of the feedback capacitor 409. The switch 412 is controlled by a reset signal PC0R. A capacitor (CTS) 413 and a capacitor (CTN) 414 are capacitors for holding a signal voltage. The switches 415 and 416 are switches that control writing to the capacitors 413 and 414, respectively. Switch 415 is controlled by signal PTS, and switch 416 is controlled by signal PTN. The switches 417 and 418 receive the signal from the horizontal shift register 404 and output the signal to the output amplifier 407 via the horizontal output lines 405 and 406, respectively. The switch 417 is controlled by the signal PHS of the horizontal shift register 404, and the switch 418 is controlled by the signal PHN. The output amplifier 407 outputs the difference between the signals on the horizontal output lines 405 and 406.

  FIG. 7 is an example of a diagram showing the wiring of the transfer pulse signals PTXA1, PTXA2, PTXB1, PTXB2, PTXC1, PTXC2, PTXD1, and PTXD2 according to the present embodiment. In this example, the horizontal direction of the image is defined as the left-right direction with the intersection of the optical axis of the photographing lens 101 and the imaging surface of the imaging element 103 as a boundary. That is, it is intended to distribute from the center of the optical axis of the photographic lens 101.

  The first vertical shift register 4011 supplies the transfer pulse signal PTXA1 to the divided pixel 201A in the unit pixel 200 in the left region (first region) 701 of the image sensor 103. The transfer switch 302A of the divided pixel 201A in the unit pixel 200 in the left region 701 of the image sensor 103 is controlled by the transfer pulse signal PTXA1.

  The first vertical shift register 4011 supplies the transfer pulse signal PTXB1 to the divided pixel 201B in the unit pixel 200 in the left region 701 of the image sensor 103. The transfer switch 302B of the divided pixel 201B in the unit pixel 200 in the left region 701 of the image sensor 103 is controlled by the transfer pulse signal PTXB1.

  The first vertical shift register 4011 supplies the transfer pulse signal PTXC1 to the divided pixels 201A in the unit pixel 200 in the left region 701 of the image sensor 103. The transfer switch 302C of the divided pixel 201A in the unit pixel 200 in the left region 701 of the image sensor 103 is controlled by the transfer pulse signal PTXC1.

  The first vertical shift register 4011 supplies the transfer pulse signal PTXD1 to the divided pixel 201B in the unit pixel 200 in the left region 701 of the image sensor 103. The transfer switch 302D of the divided pixel 201B in the unit pixel 200 in the left region 701 of the image sensor 103 is controlled by the transfer pulse signal PTXD1.

  The second vertical shift register 4012 supplies the transfer pulse signal PTXA2 to the divided pixel 201A in the unit pixel 200 in the right region (second region) 702 of the image sensor 103. The transfer switch 302A of the divided pixel 201A in the unit pixel 200 in the right region 702 of the image sensor 103 is controlled by the transfer pulse signal PTXA2.

  The second vertical shift register 4012 supplies the transfer pulse signal PTXB2 to the divided pixel 201B in the unit pixel 200 in the right region 702 of the image sensor 103. The transfer switch 302B of the divided pixel 201B in the unit pixel 200 in the right region 702 of the image sensor 103 is controlled by the transfer pulse signal PTXB2.

  The second vertical shift register 4012 supplies the transfer pulse signal PTXC2 to the divided pixel 201A in the unit pixel 200 in the right region 702 of the image sensor 103. The transfer switch 302C of the divided pixel 201A in the unit pixel 200 in the right region 702 of the image sensor 103 is controlled by the transfer pulse signal PTXC2.

  The second vertical shift register 4012 supplies the transfer pulse signal PTXD2 to the divided pixel 201B in the unit pixel 200 in the right region 702 of the image sensor 103. The transfer switch 302D of the divided pixel 201B in the unit pixel 200 in the right region 702 of the image sensor 103 is controlled by the transfer pulse signal PTXD2.

  As described above, the unit pixel 200 in the left region 701 of the image sensor 103 is driven by the first vertical shift register 4011. The unit pixel 200 in the right region 702 of the image sensor 103 is driven by the second vertical shift register 4012. The unit pixel 200 in the left region 701 and the unit pixel 200 in the right region 702 have different transfer pulse signal wirings. In addition, horizontal wiring of signals PRES and PSEL is also provided between the vertical shift registers 4011 and 4012 and the unit pixel 200.

  FIGS. 8A and 8B are schematic diagrams showing the region of FIG. 7 as a captured image. FIG. 8A shows an overall image of the subject. As shown in FIG. 8B, only the first divided pixel 201A is read out in the left region 701, and only the second divided pixel 201B is read out in the right region 702. That is, in the left region 701, the charge of the first photodiode 301A is transferred by the transfer switch 302A or 302C, and the charge of the second photodiode 301B is not transferred by the transfer switch 302B or 302D. In the right region 702, the charge of the first photodiode 301A is not transferred by the transfer switch 302A or 302C, and the charge of the second photodiode 301B is transferred by the transfer switch 302B or 302D. By performing this readout method at the time of distance measurement by the light travel time method, when the aperture value of the lens diaphragm 204 is large (FIG. 3B), a pixel having a relatively high light output at the periphery of the screen is selectively Can be used.

  FIG. 9 is a timing chart illustrating a first driving method of the imaging apparatus 100 according to the present embodiment. The first driving method shows a first pixel signal reading method at the time of distance measurement by the light travel time method. The first driving method is applied when the aperture value of the taking lens 101 is small, and the charges generated in the two photodiodes 301A and 302B are sequentially transferred to different sets of floating diffusions 303A, 303C, 303B, and 303D, respectively. .

  First, in the period HBLK, the signal PRES becomes a high level, the reset switches 304A to 304D are turned on, and the floating diffusions 303A to 303D are reset. At time t1, the signals PTXA1, PTXA2, PTXB1, and PTXB2 are at a high level, the transfer switches 302A and 302B are turned on in all unit pixels 200, and the photodiodes 301A and 301B are reset. At time t2, the signals PTXA1, PTXA2, PTXB1, and PTXB2 become low level, the transfer switches 302A and 302B are turned off in all the unit pixels 200, and charge accumulation of the photodiodes 301A and 301B starts.

  After the start of accumulation, at time t3, the signal PSEL becomes high level, the select switches 306A to 306D are turned on, and the source follower amplifiers 305A to 305D are set in an operating state. At time t4, the signal PRES becomes a low level, the reset switches 304A to 304D are turned off, and the reset of the floating diffusions 303A to 303D is released. The source follower amplifiers 305A to 305D amplify the voltages of the floating diffusions 303A to 303D, and output the amplified voltages to the column circuit 403 as reset signal levels (noise components) via the vertical output lines 307A to 307D.

  In the column circuit 403, at time t5, the signal PC0R becomes low level, the switch 412 is turned off, and the reference voltage output state of the operational amplifier 410 is released. At time t6, the signal PTN goes high, the switch 416 is turned on, and the output signal of the operational amplifier 410 is written to the capacitor 414 as the reset signal level. At time t7, the signal PTN becomes low level, the switch 416 is turned off, and writing to the capacitor 414 is completed.

  Next, at time t8, the signals PTXA1, PTXA2, PTXB1, and PTXB2 become high level. Then, in all the unit pixels 200, the transfer switches 302A and 302B are turned on, and start to transfer the photocharges accumulated in the photodiodes 301A and 301B to the floating diffusions 303A and 303B, respectively. Thereafter, at time t9, the signal PLIGHT becomes high level, and the light emitting device 112 starts projecting pulsed light. At time t10, the signals PTXA1, PTXA2, PTXB1, and PTXB2 become low level, the transfer switches 302A and 302B are turned off in all the unit pixels 200, and the transfer to the floating diffusions 303A and 303B is completed. At time t10, the signals PTXC1, PTXC2, PTXD1, and PTXD2 become high level. Then, in all the unit pixels 200, the transfer switches 302C and 302D are turned on, and start to transfer the photoelectric charges accumulated in the photodiodes 301A and 301B to the floating diffusions 303C and 303D, respectively. At time t11, the signal PLIGHT becomes a low level, and the light emitting device 112 finishes projecting the pulsed light. At time t12, the signals PTXC1, PTXC2, PTXD1, and PTXD2 are at a low level, the transfer switches 302C and 302D are turned off in all the unit pixels 200, and the transfer to the floating diffusions 303C and 303D is completed. As described above, the transfer switches 302A and 302B perform transfer in the first period from time t8 to t10, and the transfer switch 302C and transfer switch 302D perform transfer in the second period from time t10 to t12.

  The potential fluctuations of the floating diffusions 303A to 303D according to the amount of charge are output as optical signal levels (light component + noise component) to the column circuit 403 via the vertical output lines 307A to 307D. In the column circuit 403, at time t13, the signal PTS becomes high level, the switch 415 is turned on, and the output signal of the operational amplifier 410 is written to the capacitor 413 as an optical signal level. At time t14, the signal PTS becomes low level, the switch 415 is turned off, and writing to the capacitor 413 is completed. The operational amplifier 410 amplifies and outputs with an inversion gain corresponding to the ratio of the capacitance value of the clamp capacitor 408 and the feedback capacitor 409.

  Thereafter, at time t15, the signal PRES becomes high level, the reset switches 304A to 304D are turned on, and the floating diffusions 303A to 303D are reset.

  Next, in a period HSR, from time t16 to t17, the switches 417 and 418 in the column circuit 403 in each column are sequentially turned on by the pulses of the signals PHS and PHN. Then, the signals held in the capacitors 413 and 414 are output to the output amplifier 407 via the horizontal output lines 405 and 406. The output amplifier 407 outputs a difference signal (light component) between the signals of the horizontal output lines 405 and 406.

  The image processing circuit 106 is a distance calculation unit, and is based on the ratio of the signal based on the charge transferred in the first period from time t8 to t10 and the signal based on the charge transferred in the second period from time t10 to t12. The delay time of the reflected light with respect to the projection light is calculated, and the distance to the subject is calculated. The image processing circuit 106 may add different signals obtained by sequentially driving the transfer switch 302A (302B) and the transfer switch 302C (302D).

  FIG. 10 is a timing chart illustrating the second driving method of the imaging apparatus 100 according to the present embodiment. The second driving method shows a second pixel signal reading method at the time of distance measurement by the light travel time method. The second driving method is applied when the aperture value of the photographic lens 101 is large, and does not read the signals of the divided pixels on the optical axis side in the first pixel signal reading of FIG.

  First, in the period HBLK, the signal PRES becomes a high level, the reset switches 304A to 304D are turned on, and the floating diffusions 303A to 303D are reset. At time t1, the signals PTXA1 and PTXB2 become high level. Then, in the unit pixel 200 in the left region 701 of the image sensor 103, the transfer switch 302A is turned on and the photodiode 301A is reset. In the unit pixel 200 in the right region 702 of the image sensor 103, the transfer switch 302B is turned on and the photodiode 301B is reset. At time t2, the signals PTXA1 and PTXB2 become low level. Then, the charge accumulation of the photodiode 301A is started in the unit pixel 200 in the left region 701 of the image sensor 103, and the charge accumulation of the photodiode 301B is started in the unit pixel 200 in the right region 702 of the image sensor 103.

  After the start of accumulation, at time t3, the signal PSEL becomes high level, the select switches 306A to 306D are turned on, and the source follower amplifiers 305A to 305D are activated. At time t4, the signal PRES goes low, the reset switches 304A to 304D are turned off, and the reset of the floating diffusions 303A to 303D is released. The source follower amplifiers 305A to 305D amplify the voltages of the floating diffusions 303A to 303D, and output the amplified voltages to the column circuit 403 as reset signal levels (noise components) via the vertical output lines 307A to 307D.

  In the column circuit 403, at time t5, the signal PC0R becomes low level, the switch 412 is turned off, and the reference voltage output state of the operational amplifier 410 is released. At time t6, the signal PTN goes high, the switch 416 is turned on, and the output signal of the operational amplifier 410 is written to the capacitor 414 as the reset signal level. At time t7, the signal PTN becomes low level, the switch 416 is turned off, and writing to the capacitor 414 is completed.

  Next, at time t8, the signals PTXA1 and PTXB2 become high level. Then, in the unit pixel 200 in the left region 701 of the image sensor 103, the transfer switch 302A is turned on, and starts to transfer the photocharge accumulated in the photodiode 301A to the floating diffusion 303A. In the unit pixel 200 in the right region 702 of the image sensor 103, the transfer switch 302B is turned on and starts to transfer the photocharge accumulated in the photodiode 301B to the floating diffusion 303B. Thereafter, at time t9, the signal PLIGHT becomes high level, and the light emitting device 112 starts projecting pulsed light.

  At time t10, the signals PTXA1 and PTXB2 become low level. Then, in the unit pixel 200 in the left region 701 of the image sensor 103, the transfer switch 302A is turned off, and the transfer to the floating diffusion 303A is completed. In the unit pixel 200 in the right region 702 of the image sensor 103, the transfer switch 302B is turned off, and the transfer to the floating diffusion 303B is completed.

  At time t10, the signals PTXC1 and PTXD2 are at a high level. Then, in the unit pixel 200 in the left region 701 of the image sensor 103, the transfer switch 302C is turned on, and the photoelectric charge accumulated in the photodiode 301A starts to be transferred to the floating diffusion 303C. In the unit pixel 200 in the right region 702 of the image sensor 103, the transfer switch 302D is turned on, and starts to transfer the photocharge accumulated in the photodiode 301B to the floating diffusion 303D. At time t11, the signal PLIGHT becomes a low level, and the light emitting device 112 finishes projecting the pulsed light.

  At time t12, the signals PTXC1 and PTXD2 become low level. Then, in the unit pixel 200 in the left region 701 of the image sensor 103, the transfer switch 302C is turned off, and the transfer to the floating diffusion 303C is completed. In the unit pixel 200 in the left region 701 of the image sensor 103, the transfer switch 302D is turned off, and the transfer to the floating diffusion 303D is completed.

  As described above, in the first period from time t8 to time t10, the transfer switch 302A of the unit pixel 200 in the left region 701 of the image sensor 103 and the transfer switch 302B of the unit pixel 200 in the right region 702 of the image sensor 103 perform transfer. Do. Thereafter, in the second period from time t10 to t12, the transfer switch 302C of the unit pixel 200 in the left region 701 of the image sensor 103 and the transfer switch 302D of the unit pixel 200 in the right region 702 of the image sensor 103 perform transfer.

  The potential fluctuations of the floating diffusions 303A to 303D are output as optical signal levels (light component + noise component) to the column circuit 403 via the vertical output lines 307A to 307C. In the column circuit 403, at time t13, the signal PTS becomes high level, the switch 415 is turned on, and the output signal of the operational amplifier 410 is written to the capacitor 413 as an optical signal level. At time t14, the signal PTS becomes low level, the switch 415 is turned off, and writing to the capacitor 413 is completed. The operational amplifier 410 amplifies and outputs with an inversion gain corresponding to the ratio of the capacitance value of the clamp capacitor 408 and the feedback capacitor 409.

  Thereafter, at time t15, the signal PRES becomes high level, the reset switches 304A to 304D are turned on, and the floating diffusions 303A to 303D are reset.

  Next, in a period HSR, from time t16 to t17, the switches 417 and 418 in the column circuit 403 in each column are sequentially turned on by the pulses of the signals PHS and PHN. Then, the signals held in the capacitors 413 and 414 are output to the output amplifier 407 via the horizontal output lines 405 and 406. The output amplifier 407 outputs a difference signal (light component) between the signals of the horizontal output lines 405 and 406.

  The image processing circuit 106 is a distance calculation unit, and is based on the ratio of the signal based on the charge transferred in the first period from time t8 to t10 and the signal based on the charge transferred in the second period from time t10 to t12. The delay time of the reflected light with respect to the projection light is calculated, and the distance to the subject is calculated.

  Unlike the first driving method, the second driving method can selectively use the reflected light component by not reading the divided pixels on the optical axis side in which light is difficult to enter in the unit pixel 200. In addition, the second driving method can reduce the load on the image processing circuit 106 by reducing the number of divided pixels to be used, as another effect.

  FIG. 11 shows a part of the timing chart of FIG. 9 or FIG. 10, and is a diagram for explaining distance measurement by the optical travel time method. At time t1, the signal PTXA (PTXB) becomes a high level, and the transfer switch 302A (302B) is turned on. At time t3, the signal PTXA (PTXB) becomes low level, the transfer switch 302A (302B) is turned off, and at the same time, the signal PTXC (PTXD) becomes high level, and the transfer switch 302C (302D) is turned on. At time t5, the signal PTXC (PTXD) becomes a low level, and the transfer switch 302C (302D) is turned off. Here, the ON times of the transfer switch 302A (302B) and the transfer switch 302C (302D) are equal. At times t2 to t4, the signal PLIGHT becomes high level, and the light emitting device 112 projects pulsed light onto the subject. The photodiodes 301A and 301B convert the reflected light from the subject into electric charges.

  If the distance from the imaging device 100 to the subject is zero, the reflected light from the subject is received at the same timing as the signal PLIGHT. In this case, the signal transferred to the floating diffusion 303A (303B) by the signal PTXA (PTXB) is equal to the signal transferred to the floating diffusion 303C (303D) by the signal PTXC (PTXD). However, when the distance from the imaging apparatus 100 to the subject is not zero, the reflected light is received with a delay of (t2'-t2) from the timing of the signal PLIGHT as shown in FIG. As a result, the signal transferred to the floating diffusion 303A (303B) by the signal PTXA (PTXB) corresponds to the reflected light received during the period (t3-t2 '). The signal transferred to the floating diffusion 303C (303D) by the signal PTXC (PTXD) corresponds to the reflected light received during the period (t4'-t3). The signal of the floating diffusion 303A (303B) and the signal of the floating diffusion 303C (303D) are biased. Based on the ratio of the signal based on the charge transferred in the first period from time t1 to t3 and the signal based on the charge transferred in the second period from time t3 to t5, the image processing circuit 106 The delay time with respect to the projection light is estimated, and the distance to the subject is calculated from the product of the delay time and the speed of light.

  FIG. 12 is a timing chart showing the third driving method of the imaging apparatus 100 according to the present embodiment. The third driving method shows a third pixel signal reading method in normal imaging and pupil division phase difference detection. In the third driving method, charges generated in the photodiodes 301A and 301B are transferred to the floating diffusions 303A and 303B, respectively.

  First, in the period HBLK, the signal PRES is in a high level state, and the reset switches 304A and 304B are turned on to reset the floating diffusions 303A and 303B, respectively. At time t1, the signals PTXA and PTXB become high level, the transfer switches 302A and 302B are turned on, and the photodiodes 301A and 301B are reset, respectively.

  At time t3, the signal PSEL goes high, the select switches 306A and 306B are turned on, and the source follower amplifiers 305A and 305B are in the operating state. At time t4, the signal PRES goes low, the reset switches 304A and 304B are turned off, and the reset of the floating diffusions 303A and 303B is released. The source follower amplifiers 305A and 305B amplify the voltages of the floating diffusions 303A and 303B, respectively, and output them to the column circuit 403 as reset signal levels (noise components) via the vertical output lines 307A and 307B.

  In the column circuit 403, at time t5, the signal PC0R becomes low level, the switch 412 is turned off, and the reference voltage output state of the operational amplifier 410 is released. At time t6, the signal PTN goes high, the switch 416 is turned on, and the output signal of the operational amplifier 410 is written to the capacitor 414 as the reset signal level. At time t7, the signal PTN becomes low level, the switch 416 is turned off, and writing to the capacitor 414 is completed.

  Next, at time t8, the signals PTXA1, PTXA2, PTXB1, and PTXB2 become high level. Then, in all the unit pixels 200, the transfer switches 302A and 302B are turned on to transfer the photocharges accumulated in the photodiodes 301A and 301B to the floating diffusions 303A and 303B, respectively. Then, the potential fluctuations of the floating diffusions 303A and 303B according to the charge amount are output as optical signal levels (light component + noise component) to the column circuit 403 via the vertical output lines 307A and 307B, respectively. At time t10, the signals PTXA1, PTXA2, PTXB1, and PTXB2 are at a low level, and in all the unit pixels 200, the transfer switches 302A and 302B are turned off, and the above transfer ends. As described above, in all the unit pixels 200, the transfer switches 302A and 302B perform transfer at the same timing.

  In the column circuit 403, at time t13, the signal PTS becomes high level, the switch 415 is turned on, and the output signal of the operational amplifier 410 is written to the capacitor 413 as an optical signal level. At time t14, the signal PTS becomes low level, the switch 415 is turned off, and writing to the capacitor 413 is completed. Note that when signals are written to the capacitors 413 and 414, the operational amplifier 410 amplifies and outputs with an inversion gain corresponding to the ratio of the capacitance values of the clamp capacitor 408 and the feedback capacitor 409.

  Thereafter, at time t15, the signal PRES becomes high level, the reset switches 304A and 304B are turned on, and the floating diffusions 303A and 303B are reset.

  Next, in a period HSR, from time t16 to t17, the switches 417 and 418 in the column circuit 403 in each column are sequentially turned on by the pulses of the signals PHS and PHN. Then, the signals held in the capacitors 413 and 414 are output to the output amplifier 407 via the horizontal output lines 405 and 406. The output amplifier 407 outputs a difference signal (light component) between the signals of the horizontal output lines 405 and 406.

  Thereafter, when driven for normal photographing, the image processing circuit 106 is an adder, and may add a signal based on the charges transferred from the photodiodes 301A and 301B to obtain a captured image. On the other hand, at the time of detecting the pupil division phase difference, the image processing circuit 106 inputs a signal based on the charges transferred at time t8 to t10, performs the correlation calculation on the A image and the B image, and information on the distance to the subject. Is calculated. In this case, the image processing circuit 106 may add the signals of the A image and the B image after acquiring the distance information.

  FIG. 13 is a flowchart illustrating a method for driving the imaging apparatus 100 according to the present embodiment. In step S1301, mode settings such as still image shooting and moving image shooting, and shooting condition settings such as sensitivity and aperture value are set by the control circuit 109 from the user through the operation circuit 110 or automatically from the imaging apparatus 101.

  In step S1302, the imaging apparatus 100 determines whether to perform focus detection or obtain a normal captured image. If focus detection is to be performed, the process proceeds to step S1305. If a normal captured image is acquired, the process advances to step S1303.

  In step S1303, the imaging apparatus 100 reads an image signal by the third driving method (normal shooting) in FIG. Next, in step S1304, the image processing circuit 106 performs predetermined image processing corresponding to each reading on the image signal read in step S1303, and outputs the image signal to the memory circuit 107 and the recording circuit 108. To do. Further, the image processing circuit 106 outputs an image signal to the display circuit 111 via the control circuit 109.

  In step S1305, the imaging apparatus 100 determines whether or not the aperture value of the photographing lens 101 is greater than a threshold value in order to select a focus detection method. If it is greater than the threshold value, the process proceeds to step S1306, and if it is less than the threshold value, the process proceeds to step S1307.

  In step S1306, the imaging apparatus 100 reads out a signal by the second driving method in FIG. 10 and acquires a distance detection image. Thereafter, the process proceeds to step S1308.

  In step S1307, the imaging apparatus 100 reads out a signal by the first driving method in FIG. 9 or the third driving method in FIG. 12 (pupil division phase difference detection), and acquires a distance detection image. The selection of the first driving method or the third driving method may be designated in advance by the user using the operation circuit 110, or may be automatically determined by the control circuit 109. Thereafter, the process proceeds to step S1308.

  In step S1308, the imaging apparatus 100 performs processing on the read distance detection image by the light travel time method or the pupil division phase difference detection method, and calculates distance information to the subject. Note that the imaging apparatus 100 may output a distance detection image or distance information to the memory circuit 107, the recording circuit 108, and the display circuit 111.

  Next, in step S1309, the imaging apparatus 100 determines the presence / absence of photographing, and if continuing, proceeds to step S1310, and if finished, ends a series of operations.

  In step S1310, the image processing circuit 106 calculates a lens driving amount based on the distance information to the subject obtained in step S1308.

  Next, in step S1311, the control circuit 109 performs focus driving by driving the photographing lens 101 based on the above lens driving amount. Then, it returns to step S1301 and repeats said operation | movement.

  In step S1310, when the aperture value of the photographing lens 101 is larger than a predetermined value, it may be regarded as pan focus, and focus detection and lens driving may be passed through. In step S1305, the driving method is selected based on the aperture value of the photographic lens 101. However, the actual use of the imaging apparatus 100 does not depend on the aperture value of the photographic lens 101, and the first to third driving. Any method may be selected and operated.

  As described above, even in the divided pixel structure, the accuracy of distance measurement can be improved regardless of the area in the image sensor 103, and the load of image processing can be reduced.

  In the above description, the pixels for calculating the distance information are used without distinguishing between the color filters. However, only the pixels of the infrared filter may be used according to the color of the projection light, for example, infrared light, or more light. In order to capture the pixel, a transparent filter or a G filter pixel may be used.

(Second Embodiment)
Unlike the first embodiment, the second embodiment of the present invention reads out signals of one divided pixel in the peripheral region of the image sensor 103 and reads out signals of all the divided pixels in the central region of the image sensor 103. I do. This is because when the boundary between the left region 701 and the right region 702 of the image sensor 103 does not coincide with the optical axis of the photographing lens 101 due to an error or the like, or in the central region of the image sensor 103, the left-right difference of incident light is not as great as the peripheral region. Done for.

  FIG. 14 corresponds to FIG. 7 and is an example of a diagram illustrating wiring of transfer pulse signals PTXA1, PTXA2, PTXB1, PTXB2, PTXC1, PTXC2, PTXD1, and PTXD2 according to the second embodiment. The first vertical shift register 4011 outputs transfer pulse signals PTXA1, PTXB1, PTXC1, and PTXD1 to the image sensor 103. The second vertical shift register 4012 outputs transfer pulse signals PTXA 2, PTXB 2, PTXC 2, and PTXD 2 to the image sensor 103.

  First, the unit pixel 200 of the left peripheral region (first region) 1401 of the image sensor 103 will be described. In the divided pixel 201A, the transfer switch 302A is controlled by the transfer pulse signal PTXA1, and the transfer switch 302C is controlled by the transfer pulse signal PTXC1. In the divided pixel 201B, the transfer switch 302B is controlled by the transfer pulse signal PTXB1, and the transfer switch 302D is controlled by the transfer pulse signal PTXD1.

  Next, the unit pixel 200 in the central region (third region) 1402 of the image sensor 103 will be described. In the divided pixel 201A, the transfer switch 302A is controlled by the transfer pulse signal PTXA1, and the transfer switch 302C is controlled by the transfer pulse signal PTXC1. In the divided pixel 201B, the transfer switch 302B is controlled by the transfer pulse signal PTXB2, and the transfer switch 302D is controlled by the transfer pulse signal PTXD2.

  Next, the unit pixel 200 of the right peripheral region (second region) 1403 of the image sensor 103 will be described. In the divided pixel 201A, the transfer switch 302A is controlled by the transfer pulse signal PTXA2, and the transfer switch 302C is controlled by the transfer pulse signal PTXC2. In the divided pixel 201B, the transfer switch 302B is controlled by the transfer pulse signal PTXB2, and the transfer switch 302D is controlled by the transfer pulse signal PTXD2. Peripheral areas 1401 and 1403 are areas around the central area 1402.

  FIGS. 15A and 15B are schematic diagrams corresponding to FIGS. 8A and 8B and showing the region of FIG. 14 as captured images. FIG. 15A shows an overall image of the subject. As shown in FIG. 15B, the left peripheral area 1401, the central area 1402, and the right peripheral area 1403 differ in the divided pixels from which signals are read.

  In the left peripheral area 1401, only the signal of the first divided pixel 201A is read out. That is, in the left peripheral region 1401, the charge of the first photodiode 301A is transferred by the transfer switch 302A or 302C, and the charge of the second photodiode 301B is not transferred by the transfer switch 302B or 302D.

  In the central region 1402, signals of both the first divided pixel 201A and the second divided pixel 201B are read out. That is, in the central region 1402, the charge of the first photodiode 301A is transferred by the transfer switch 302A or 302C, and the charge of the second photodiode 301B is transferred by the transfer switch 302B or 302D.

  In the right peripheral area 1403, only the signal of the second divided pixel 201B is read out. That is, in the right peripheral region 1403, the charge of the first photodiode 301A is not transferred by the transfer switch 302A or 302C, and the charge of the second photodiode 301B is transferred by the transfer switch 302B or 302D.

  The reading method is the same as that in FIGS. 9, 10, 12, and 13. According to the present embodiment, even in the divided pixel structure, the accuracy of distance measurement can be improved and the load of image processing can be reduced regardless of the area in the image sensor 103.

  In this embodiment, the drive pulse signal wiring in the central region 1402 is shared with the drive pulse signal wiring in the left and right peripheral regions 1401 and 1403. However, in order to control the central region 1402 independently, a new drive pulse is used. Signal wiring may be added.

(Third embodiment)
Unlike the second embodiment, the third embodiment of the present invention eliminates unnecessary drive pulse signal wiring, and can improve the layout efficiency.

  FIG. 16 corresponds to FIG. 14 and is an example of a diagram illustrating wiring of transfer pulse signals PTXA1, PTXA2, PTXB1, PTXB2, PTXC1, and PTXD2 according to the third embodiment. The wiring has been deleted. The first vertical shift register 4011 outputs transfer pulse signals PTXA 1, PTXB 1, PTXC 1 to the image sensor 103. The second vertical shift register 4012 outputs transfer pulse signals PTXA 2, PTXB 2, and PTXD 2 to the image sensor 103.

  First, the unit pixel 200 in the left peripheral region 1401 of the image sensor 103 will be described. In the divided pixel 201A, the transfer switch 302A is controlled by the transfer pulse signal PTXA1, and the transfer switch 302C is controlled by the transfer pulse signal PTXC1. In the divided pixel 201B, the transfer switch 302B is controlled by the transfer pulse signal PTXB1, and the transfer switch 302D is controlled by the transfer pulse signal PTXD2.

  Next, the unit pixel 200 in the central region 1402 of the image sensor 103 will be described. In the divided pixel 201A, the transfer switch 302A is controlled by the transfer pulse signal PTXA1, and the transfer switch 302C is controlled by the transfer pulse signal PTXC1. In the divided pixel 201B, the transfer switch 302B is controlled by the transfer pulse signal PTXB2, and the transfer switch 302D is controlled by the transfer pulse signal PTXD2.

  Next, the unit pixel 200 in the right peripheral region 1403 of the image sensor 103 will be described. In the divided pixel 201A, the transfer switch 302A is controlled by the transfer pulse signal PTXA2, and the transfer switch 302C is controlled by the transfer pulse signal PTXC1. In the divided pixel 201B, the transfer switch 302B is controlled by the transfer pulse signal PTXB2, and the transfer switch 302D is controlled by the transfer pulse signal PTXD2.

  Also in this embodiment, signal readout by the first to third driving methods can be performed. According to this embodiment, it is possible to contribute to layout efficiency.

  In the divided pixel 201B in the left peripheral region 1401, the transfer switch 302D and the floating diffusion 303D may be deleted without connecting the transfer switch 302D to the wiring of the transfer pulse signal PTXD2. Similarly, in the divided pixel 201A in the right peripheral region 1403, the transfer switch 302C and the floating diffusion 303C may be deleted without connecting the transfer switch 302C to the wiring of the transfer pulse signal PTXC1. In this case, signal readout by the first drive method cannot be performed, but signal readout by the second drive method can be substituted, and signal readout by the third drive method is also possible.

  As described above, the first to third embodiments can be variously modified and changed. For example, as shown in FIG. 17, for the purpose of improving the layout efficiency of the unit pixel 200, modifications such as sharing the floating diffusions 503 </ b> A and 503 </ b> B can be performed. The floating diffusion 503A in FIG. 17 corresponds to the floating diffusions 303A and 303B in FIG. The floating diffusion 503B in FIG. 17 corresponds to the floating diffusions 303C and 303D in FIG. The transfer switch 302A transfers the charge of the photodiode 301A to the floating diffusion (first charge storage unit) 503A. The transfer switch 302B transfers the charge of the photodiode 301B to the floating diffusion 503A. The transfer switch 302C transfers the charge of the photodiode 301A to the floating diffusion (second charge storage unit) 503B. The transfer switch 302D transfers the charge of the photodiode 301B to the floating diffusion 503B.

  Further, an analog-digital conversion circuit may be incorporated in the column circuit 403. Further, all the signals of the plurality of photodiodes 301A and 301B sharing the single microlens 1020 may be read out regardless of the area in the image sensor 103. In that case, after that, the image processing circuit 106 may selectively use a signal located outside the intersection of the optical axis of the optical system and the imaging surface for image creation or distance measurement.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

DESCRIPTION OF SYMBOLS 100 Imaging device, 101 Shooting lens, 102 Micro lens array, 1020 Micro lens, 103 Imaging device, 301A, 301B Photo diode, 302A, 302B, 302C, 302D Transfer switch, 303A, 303B, 303C, 303D Floating diffusion

Claims (10)

A plurality of microlenses,
An image sensor that has a plurality of unit pixels that correspond to each of the plurality of microlenses and is arranged two-dimensionally,
Each of the plurality of unit pixels is
First and second photoelectric conversion units that convert light received through the same microlens into electric charge;
First and second transfer switches for transferring charges of the first photoelectric conversion unit to different charge storage units;
A third transfer switch and a fourth transfer switch for transferring the charge of the second photoelectric conversion unit to different charge storage units;
In the unit pixel in the first region of the image sensor, the charge of the first photoelectric conversion unit is transferred by the first transfer switch or the second transfer switch, and the charge of the second photoelectric conversion unit is transferred. Is not transferred by the third transfer switch or the fourth transfer switch,
In the unit pixel in the second region of the image sensor, the charge of the first photoelectric conversion unit is not transferred by the first transfer switch or the second transfer switch, and the second photoelectric conversion unit Charge is transferred by the third transfer switch or the fourth transfer switch.   In the unit pixel in the third region of the image sensor, the charge of the first photoelectric conversion unit is transferred by the first transfer switch or the second transfer switch, and the charge of the second photoelectric conversion unit is transferred. The image pickup apparatus according to claim 1, wherein the image is transferred by the third transfer switch or the fourth transfer switch. The third region of the image sensor is a central region of the image sensor;
The imaging apparatus according to claim 2, wherein the first area of the imaging element and the second area of the imaging element are areas around the third area of the imaging element. The first transfer switch transfers the charge of the first photoelectric conversion unit to a first charge storage unit,
The second transfer switch transfers the charge of the first photoelectric conversion unit to a second charge storage unit,
The third transfer switch transfers the charge of the second photoelectric conversion unit to a third charge storage unit;
4. The imaging apparatus according to claim 1, wherein the fourth transfer switch transfers the charge of the second photoelectric conversion unit to a fourth charge storage unit. 5. The first transfer switch transfers the charge of the first photoelectric conversion unit to a first charge storage unit,
The second transfer switch transfers the charge of the first photoelectric conversion unit to a second charge storage unit,
The third transfer switch transfers the charge of the second photoelectric conversion unit to the first charge storage unit,
The imaging apparatus according to claim 1, wherein the fourth transfer switch transfers the charge of the second photoelectric conversion unit to the second charge storage unit. Furthermore, it has a light emitting device that projects pulsed light onto the subject,
The imaging apparatus according to claim 1, wherein the first photoelectric conversion unit and the second photoelectric conversion unit convert reflected light from the subject into electric charges. In the unit pixel of the first region of the image sensor, the first transfer switch performs transfer in a first period, and the second transfer switch performs transfer in a second period thereafter,
In the unit pixel in the second region of the image sensor, the third transfer switch performs transfer during the first period, and the fourth transfer switch performs transfer during the second period. The imaging device according to any one of claims 1 to 6.   The imaging apparatus according to claim 7, further comprising a distance calculation unit that calculates a distance to a subject according to the charge transferred in the first period and the charge transferred in the second period. . In addition, it has a photographic lens,
If the aperture value of the taking lens is larger than a threshold value,
In the unit pixel in the first region of the imaging device, the first transfer switch performs transfer in a first period, and the second transfer switch performs transfer in a second period thereafter.
In the unit pixel in the second region of the image sensor, the third transfer switch performs transfer during the first period, and the fourth transfer switch performs transfer during the second period,
The distance calculation unit calculates a distance to a subject according to the charge transferred in the first period and the charge transferred in the second period,
If the aperture value of the taking lens is below a threshold value,
In the unit pixels in the first area and the second area of the image sensor, the first transfer switch and the third transfer switch perform transfer in a first period, and in the second period thereafter. The second transfer switch and the fourth transfer switch perform transfer;
The imaging apparatus according to claim 8, wherein the distance calculation unit calculates a distance to a subject according to the charge transferred in the first period and the charge transferred in the second period. In addition, it has a photographic lens,
If the aperture value of the taking lens is larger than a threshold value,
In the unit pixel in the first region of the imaging device, the first transfer switch performs transfer in a first period, and the second transfer switch performs transfer in a second period thereafter.
In the unit pixel in the second region of the image sensor, the third transfer switch performs transfer during the first period, and the fourth transfer switch performs transfer during the second period,
The distance calculation unit calculates a distance to a subject according to the charge transferred in the first period and the charge transferred in the second period,
If the aperture value of the taking lens is below a threshold value,
In the unit pixels of the first region and the second region of the image sensor, the first transfer switch and the third transfer switch perform transfer at the same timing,
The imaging apparatus according to claim 8, wherein the distance calculation unit calculates a distance to a subject in accordance with charges transferred by the first transfer switch and the third transfer switch.

Images