JP6362511B2 - Imaging apparatus and control method thereof - Google Patents

Description

  The present invention relates to an imaging apparatus and a control method thereof.

  A technique has been proposed in which a phase difference detection function is added to a solid-state imaging device so that a dedicated AF (Auto Focus) sensor is unnecessary and high-speed phase difference AF is realized. For example, in Patent Document 1, in some light receiving elements (pixels) of a solid-state imaging element, a pupil division function is provided by decentering the sensitivity region of the light receiving unit with respect to the optical axis of the on-chip microlens. These pixels are used as focus detection pixels and are discretely arranged between the imaging pixel groups at predetermined row intervals to perform phase difference focus detection.

  The subject distance (distance to the object) is measured by projecting pulsed light onto the subject (object), receiving the reflected light with a solid-state imaging device, and measuring the flight time (delay time) of this pulsed light. There is a TOF (Time-Of-Flight) method for measuring the time. By applying the principle of the TOF method, a technique for acquiring distance information using a CMOS type solid-state imaging device having a charge distribution type pixel structure has been proposed. For example, the signal component corresponding to the preceding part and the signal part corresponding to the following part of the reflected pulse light that arrives after the irradiation pulse light is reflected by the object is distributed by the switch, and the ratio is obtained for each pixel. Distance information for each pixel can be obtained (see Patent Document 2). In addition, a method has been proposed in which distance information is obtained using different pixel outputs by changing the transfer timing between even-numbered pixels and odd-numbered pixels using the TOF method (see Patent Document 3).

JP 2010-219958 A JP 2004-294420 A JP 2010-213231 A

  In Patent Document 1, focus detection pixels included in a solid-state image sensor are discretely arranged, and pixel signals are read out in units of pixel rows. Therefore, when reading a pixel signal in a pixel row in which a focus detection pixel is arranged at the time of moving image shooting, in addition to a pixel signal of the focus detection pixel, a pixel of a non-focus detection pixel arranged in the same pixel row The signal is also read out simultaneously. However, the pixel signal of the non-focus detection pixel read out at this time is not used for image generation or focus detection, and the time for reading the pixel signal and the power consumption of the readout circuit are redundant, resulting in waste. It was. An object of the present invention is to provide an imaging apparatus that can effectively use distance detection accuracy by effectively using non-focus detection pixels arranged in the same pixel row as focus detection pixels of a solid-state imaging device. It is.

  The imaging apparatus according to the present invention includes a plurality of pixels arranged in a two-dimensional manner, and a plurality of second pixels that generate a signal for image generation by photoelectrically converting a subject image formed by a photographing lens as the plurality of pixels. A plurality of second pixels which are discretely arranged between one pixel and the first pixel, and which photoelectrically convert a subject image from a region obtained by dividing the pupil region of the photographing lens to generate a phase difference detection signal. An image is generated based on signals from a plurality of first pixels, a solid-state imaging device having two pixels, a light projecting unit that projects pulsed light onto a subject, and signals from the plurality of second pixels The focus detection is performed on the basis of the second pixel and the pulsed light projected by the light projecting means is reflected by the plurality of third pixels different from the second pixels arranged in the same row as the second pixels. A plurality of the above-mentioned obtained by photoelectric conversion Based on the signal from 3 pixels and having a processing means for performing a distance detection to the object.

  According to the present invention, focus detection by phase difference AF can be performed using signals from a plurality of second pixels, and signals from third pixels arranged in the same row as the second pixels can be detected. It is possible to detect the distance to the subject. Thereby, pixels that are not used for focus detection arranged in the same row as the pixels used for focus detection can be effectively used, and the distance detection accuracy can be improved.

It is a figure which shows the structural example of the solid-state image sensor in embodiment of this invention. It is a figure which shows the structural example of the imaging device in this embodiment. It is a figure which shows the example of pixel arrangement | positioning of the solid-state image sensor in this embodiment. It is a figure which shows the structural example of the pixel of the solid-state image sensor in this embodiment. It is a figure which shows the structural example of the read-out part of the solid-state image sensor in this embodiment. It is a timing chart which shows the operation example of still image photography in this embodiment. It is a timing chart which shows the operation example of the moving image photography in this embodiment. It is a timing chart which shows the example of the read-out operation | movement of the pixel signal which concerns on the distance detection at the time of the video recording in this embodiment. It is a figure which shows the example of the signal read-out operation | movement in the moving image photography in this embodiment. It is a flowchart which shows the example of control of the imaging device in this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of a solid-state imaging device according to an embodiment of the present invention. The solid-state imaging device 100 according to the present embodiment includes a pixel unit 101, a vertical scanning unit 102, a reading unit 103, a horizontal scanning unit 104, and a difference output circuit (reading amplifier) 110. Note that the solid-state imaging device 100 may include a timing generator (timing generation circuit) that supplies a timing signal or the like to each circuit.

  The pixel unit 101 has a plurality of unit pixels arranged two-dimensionally (in a row direction and a column direction), and receives a subject image formed by an optical system including a photographing lens. Each pixel of the pixel unit 101 photoelectrically converts the subject image to generate a pixel signal. The vertical scanning unit 102 selects the rows of the pixel units 101 in the designated order by driving the signal PTX, the signal PRES, and the signal PSEL. The horizontal scanning unit 104 sequentially selects a plurality of columns of the pixel unit 101 by driving the signal ph.

  The reading unit 103 amplifies and holds an analog signal output for each column from the pixel unit 101 by the vertical scanning unit 102 and a switch, and an analog that converts the analog signal held in the signal holding unit into a digital signal. -It has a digital conversion part (AD conversion part). Further, the reading unit 103 latches the digital signal converted by the AD conversion unit, and sequentially reads the digital signal to the difference output circuit 110 by the pulse signal ph supplied from the horizontal scanning unit 104. The difference output circuit 110 outputs a difference signal between the read S signal (optical signal component and noise component) and N signal (noise component).

  FIG. 2 is a diagram illustrating a configuration example of an imaging apparatus having a solid-state imaging device in the present embodiment. The imaging apparatus according to the present embodiment can generate subject distance information (distance image) by the TOF (Time-Of-Flight) method using the solid-state imaging device 100. The imaging apparatus according to the present embodiment includes a solid-state imaging device 100, a photographing lens 201, a light emitting device 202, a timing generation circuit 203, a signal processing unit 204, and a control unit 205.

  The solid-state imaging device 100 is the solid-state imaging device shown in FIG. 1 and photoelectrically converts a received optical image (subject image). The taking lens 201 collects light from the object scene onto the solid-state imaging device 100. A light emitting element 202 as a light projecting unit irradiates a subject with pulsed light. For example, the light emitting element 202 is driven to project light onto the subject when the pulse signal pled supplied from the timing generation circuit 203 becomes high level. The timing generation circuit 203 drives the solid-state imaging element 100 and the light emitting element 203 according to control by the control unit 205.

  The signal processing unit 204 performs various types of signal processing using signals from the solid-state imaging device 100 according to control by the control unit 205. For example, the signal processing unit 204 generates a captured image based on a pixel signal from an imaging pixel included in the solid-state imaging device 100. The signal processing unit 204 performs focus detection processing based on, for example, a pixel signal from a focus detection pixel included in the solid-state imaging device 100, or from a non-focus detection pixel arranged in the same row as the focus detection pixel. A distance detection process by the TOF method is performed based on the pixel signal. That is, distance information (distance image) to the subject is generated by measuring the time until the light emitted from the light emitting element 202 is reflected by the subject and received by the solid-state imaging device 100.

  The control unit 205 controls each unit included in the imaging apparatus. The control unit 113 includes a microcontroller and an arithmetic processing unit (CPU) that control each unit of the imaging apparatus by executing a program describing a control method, for example. For example, the control unit 205 controls the signal processing unit 204 and the timing generation circuit 203 according to the shooting mode and the like, and controls the driving of the shooting lens 201 according to the processing result at the signal processing unit 204 and the like.

  FIG. 3 is a diagram illustrating an example of a pixel arrangement of the solid-state imaging device in the present embodiment. In recent years, as a solid-state imaging device, an imaging device having a high pixel count having pixels from millions of pixels to more than 10 million pixels has been put into practical use. A description will be given with an arrangement of 24 pixels and 12 pixels in the vertical direction. In addition, normally, a solid-state image sensor is appropriately provided with a light-shielded optical black pixel (OB pixel) that serves as a reference for pixel output, but this is also omitted from the drawing for the sake of simplicity. Yes.

  The pixel array of the solid-state imaging device in the present embodiment is based on a 2 × 2 Bayer array. The symbols G, R, and B described in the figure indicate green (green), red (red), and blue (blue) color filters, respectively. The Bayer-arranged G pixel, R pixel, and B pixel photoelectrically convert a subject image formed by the photographing lens to generate a signal for image generation. Further, A pixels and B pixels, which are focus detection pixels, are regularly mixed at a predetermined ratio in a part of the solid-state imaging device arranged in the Bayer array. The focus detection pixels A and B generate light to detect a phase difference by photoelectrically converting a subject image from a region obtained by dividing the pupil region of the photographing lens by shielding a part of the photodiode. .

  The focus detection pixels are arranged in pixel rows from which pixel signals are not read out, that is, thinned out in row thinning readout from the solid-state imaging device during moving image shooting. In the example shown in FIG. 3, the focus detection pixels are arranged such that the A pixels, which are reference pixels for phase difference AF, are arranged discretely in the pupil division direction in the v4th row, and the phase difference is in the v5th row. B pixels which are AF reference pixels are discretely arranged for each pixel in the pupil division direction. The defocus amount of the photographing lens can be obtained by obtaining the image shift amount between the A pixel in the v4 row and the B pixel in the v5 row. Also, the A pixel and the B pixel are arranged in the same rule in the v10 and v11 lines, respectively.

  The purpose of discretely arranging the A pixel and the B pixel is that the focus detection pixel is regarded as a defective pixel and is interpolated using information on the surrounding normal pixels. This is because normal pixels are arranged and image deterioration due to interpolation is suppressed. Therefore, it is discretely arranged in the pupil division direction, and is also discretely arranged in the pupil division and the vertical direction, in the present embodiment, in the row direction. The pair of reference pixels and reference pixels in the v4 and v5 rows and the reference pixel and reference pixel pair in the v10 and v11 rows are arranged 5 rows apart. Note that the pixel arrangement in the present embodiment shown in FIG. 3 shows an example of the arrangement, and is not limited to this arrangement.

  FIG. 4 is a diagram illustrating a configuration example of pixels (unit pixels) included in the solid-state imaging device according to the present embodiment. 4 constitutes one pixel, and a plurality of unit pixels 400 shown in FIG. 4 are arranged two-dimensionally (in the row direction and the column direction) in the pixel portion 101. The unit pixel 400 includes a photodiode (PD) 401, a transfer transistor (tx) 402, a reset transistor (tres) 403, an amplifying transistor (tsf) 404, and a selection transistor (tsel) 405. As the transfer transistor 402, the reset transistor 403, the amplification transistor 404, and the selection transistor 405, for example, a MOS (Metal Oxide Semiconductor) transistor is used.

  In the example shown in FIG. 4, the anode side of the photodiode 401 that generates the optical signal charge is grounded. The cathode side of the photodiode 401 is connected to the floating diffusion (Cfd) and the gate of the amplification transistor 404 via the transfer transistor 402. The gate of the amplification transistor 404 is connected to the source of the reset transistor 403 for resetting the photodiode 401 and the floating diffusion (Cfd). The drain of the reset transistor 403 is connected to the power supply voltage VDD. The amplification transistor 404 has a drain connected to the power supply voltage VDD and a source connected to the drain of the selection transistor 405.

  The transfer transistor 402 is supplied with the signal PTX at its gate terminal, and transfers the signal of the photodiode 401 to the floating diffusion and the gate of the amplification transistor 404. The reset transistor 403 is supplied with a signal PRES at its gate terminal, and resets the floating diffusion and the photodiode 401. In the selection transistor 405, the signal PSEL is supplied to the gate terminal, and the signal is output from the terminal out. The terminal out is connected to a vertical output line (column output line) (not shown). The amplification transistor 404 functions as a source follower amplifier by being connected to the current source load via the selection transistor 405.

  FIG. 5 is a diagram illustrating a part of the reading unit of the solid-state imaging device according to the present embodiment. In FIG. 5, as unit pixels, “00” in the v0 row h0 column, “10” in the v1 row h0 column, “01” in the v0 row h1 column, and the v1 row shown in FIG. Only four pixels (2 × 2) of “11” in the eye h1 column are shown. Actually, a plurality of such unit pixel groups are arranged in the row direction and the column direction.

  The output of the unit pixel is connected to vertical output lines (column output lines) 500 and 502 to which current source loads 501 and 503 are connected. Two vertical output lines 500 and 502 are arranged for each pixel column. The unit pixel output read to the vertical output line is amplified by the amplification amplifier 504 and held in the holding capacitors 506 and 508 via the MOS switches 505 and 507 driven by the control pulses PTS and PTN. Here, the holding capacitor 508 holds an output (N signal) after the reset of the unit pixel is released, and the holding capacitor 506 holds a signal output (S signal) from the unit pixel.

  The signals (S signal and N signal) held in this way are AD-converted by an AD converter (not shown) and then transferred to the differential output circuit 110 by the horizontal scanning unit 104, and the difference between the S signal and the N signal A signal is output. As shown in FIG. 5, the solid-state imaging device according to the present embodiment includes two vertical output lines 500 and 502 for one column of unit pixels, and unit pixels of even and odd rows are connected to each other. Yes. That is, it is possible to obtain unit pixel outputs for two rows by a signal reading operation for one row.

  FIG. 6 illustrates how the signal accumulated in the photodiode (PD) 401 is read for all pixels of one screen in order to capture a still image in the solid-state imaging device according to the present embodiment illustrated in FIGS. 1 to 5. It is a timing chart to do. In FIG. 6, the passage of time is shown in the horizontal direction. FIG. 6 shows the read operation from the pixels in the v0-th to v3-th rows shown in FIG. 3, and the pixel signals of the pixels in the subsequent rows including the focus detection pixel row are also read out by the same operation. It is.

  When the signal HD changes from the low level to the high level, the pixel selection row by the vertical scanning unit 102 is switched, and the phase of the signal HD indicates the phase of the signal PSEL supplied to the pixels of the selection row. Each pulse signal turns on the corresponding transistor at a high level.

  Further, the transfer transistors (tx) 402 of the pixels in two rows that are read simultaneously are driven every two rows by the signal PTX. For example, when pixel signals are read from the pixels in the v0 and v1 rows, the signal PTX_0i (i is a subscript, i = 0, 1, 2, 3,. )) And PTX_1i supplied to the pixels in the v1th row are driven simultaneously. Further, for example, in reading out pixel signals from the pixels in the v2 row and the v3 row, the signal PTX_2i supplied to the v2 row pixel and the PTX_3i supplied to the v3 row pixel are driven simultaneously.

  Here, in order to simplify the description, it is assumed that exposure is performed before time T1 and signal charges are accumulated in the photodiode (PD) 401 of the solid-state imaging device, and the description after time T1 will be described. First, at time T1 to time T2, the signal HD (PSEL) changes from the low level to the high level, whereby the pixels in the v0 and v1 rows are selected by the vertical scanning unit 102, and the v0 and v1 rows are selected. Are output to the vertical output line. At this time, the signal PRES is at a high level, and the floating diffusion (Cfd) of the pixel is in a reset state.

  From time T3 to time T4, when the control pulses PTS and PTN are at a high level, the storage capacitor 506 and the storage capacitor 508 are reset. At time T5, the signal PRES goes low, and the reset of the floating diffusion (Cfd) is released. After that, at time T6 to time T7, the control pulse PTN becomes high level again, so that the output (N signal, noise component) after reset release of the unit pixel is held in the holding capacitor 508.

  Next, from time T8 to time T9, the signal PTX_0i and the signal PTX_1i are at a high level, so that the signals from the photodiodes (PD) 401 of all the pixels in the selected row are transferred to the floating diffusion (Cfd). Thereafter, the signal output (S signal, optical signal component, and noise component) from the unit pixel is held in the holding capacitor 506 when the control pulse PTS again becomes high level from time T9 to time T10.

  Subsequently, after the S signal and the N signal held in the holding capacitors 506 and 508 are AD-converted between time T10 and time T11, the signal ph is driven by the horizontal scanning unit 104 and transferred to the differential output circuit 110. Then, a differential signal between the S signal and the N signal is output. At time T11, the signal PRES becomes high level, and at time T11 to time T12, the signal HD (PSEL) changes from low level to high level again, so that the next row (here, the v2 row and the v3 row). Reading of the unit pixel output is started.

  By repeating the readout operation for every two rows in this way, it is possible to read out all the unit pixel outputs for one screen in the solid-state imaging device. Thereby, a pixel signal for one screen for imaging the subject is obtained. In addition, since distance detection by the TOF method is not performed in still image shooting, the pulse signal pred remains at a low level, and the light emitting element 202 is not driven to emit light.

  FIG. 7 illustrates how the signal accumulated in the photodiode (PD) 401 in the imaging row is read out in order to capture a moving image in the solid-state imaging device according to the present embodiment illustrated in FIGS. 1 to 5. It is a timing chart. The imaging row is a pixel row in which imaging pixels that generate an image generation signal are arranged.

  The driving operation of each signal is the same as the operation example shown in FIG. 6, and time T21 to time T32 shown in FIG. 7 correspond to time T1 to time T12 shown in FIG. 6, respectively. Different rows are selected to perform decimation readout. In the example shown in FIG. 7, the rows selected between time T21 and time T32 are the v0th and v3th rows, and the subsequent selected rows are the v6th and v9th rows, and focus detection is performed. The rows in which the pixels are arranged (for example, the v4th and v5th rows) are not read out here.

  With the operation shown in FIG. 7, the moving image capturing pixel signal for 1/3 of all the pixel rows in the solid-state imaging device can be read. Here, since distance detection by the TOF method is not performed, the pulse signal pred remains at a low level, and the light emitting element 202 is not driven to emit light.

  FIG. 8 shows a focus for performing focus detection using a focus detection pixel and distance detection by a TOF method using a non-focus detection pixel in the solid-state imaging device according to the present embodiment shown in FIGS. A reading operation of the detection pixel row will be described. This operation is performed subsequently after the readout operation of the moving image capturing pixel signal for one third of the pixel rows described in FIG. The focus detection pixel row is a pixel row in which focus detection pixels for generating a phase difference detection signal are arranged, and is not only used for focus detection pixels but also used for focus detection. Pixels are also arranged.

  In the example shown in FIG. 8, the pixels in the focus detection pixel row shown in FIG. 3 are based on a 2 × 2 Bayer array, and the phase difference AF is set by the A pixel and the B pixel that are focus detection pixels. Let it be done. Further, the remaining two non-focus detection pixels (for example, a pixel in the v4th row h1 column and a pixel in the v5th row h0 column) arranged in the same row as the focus detection pixel reach the subject by the TOF method. It is assumed that distance detection is performed.

  Here, in order to simplify the description, it is assumed that signal charges are accumulated in the photodiode (PD) 401 of the focus detection pixel before the time T41, and the description after the time T41 is given. First, at time T41 to time T42, the signal HD (PSEL) is changed from the low level to the high level, so that the pixels in the v4 and v5 rows are selected by the vertical scanning unit 102, and the v4 and v5 rows are selected. Are output to the vertical output line.

  At this time, the signal PRES is at a high level, and the floating diffusion (Cfd) of all the pixels in the focus detection pixel row is in a reset state. Further, the signal PTX supplied to the non-focus detection pixels such as the signals PTX_41, PTX_101, the signal PTX_50, and the signal PTX_110 is at a high level, and the photodiode (PD) 401 is also in a reset state in the non-focus detection pixels.

  At time T43, the signal PRES becomes low level, and the reset of the floating diffusion (Cfd) of all the pixels in the focus detection pixel row is released. At time T43, the signal PTX supplied to the non-focus detection pixel becomes low level, and the reset of the photodiode (PD) 401 of the non-focus detection pixel is released. From time T44 to time T45, the signals PTX supplied to the focus detection pixels such as the signals PTX_40 and PTX_100 and the signals PTX_51 and PTX_111 are at a high level. As a result, signals from the photodiodes (PD) 401 of all focus detection pixels are transferred to the floating diffusion (Cfd).

  Subsequently, during the period from time T46 to time T48, the signal PTX supplied to the non-focus detection pixels in the focus detection pixel row in which the A pixels such as the signals PTX_41 and PTX_101 are arranged is at a high level. As a result, the signal from the photodiode (PD) 401 of the non-focus detection pixels on the v4th and v10th rows is transferred to the floating diffusion (Cfd).

In the period from time T48 to time T50, the signal PTX supplied to the non-focus detection pixels in the focus detection pixel row in which the B pixels such as the signals PTX_50 and PTX_110 are arranged is at a high level. As a result, the signal from the photodiode (PD) 401 of the non-focus detection pixels on the v5th and v11th lines is transferred to the floating diffusion (Cfd). In the period from time T47 to time T49, when the pulse signal pled is at a high level, the light emitting element 202 is driven to emit light, and pulse light is projected onto the subject.
That is, during the period from time T46 to time T50, light projection and signal accumulation for distance detection by the TOF method are performed.

  After that, at time T51 to time T52, the control pulse PTS becomes high level, so that the signal outputs (S signals) of the focus detection pixels and the non-focus detection pixels in the v4th and v5th rows are stored in the storage capacitor 506. Retained. Subsequently, at time T52 to time T53, when the signal PRES in the v4th and v5th rows becomes high level, the floating diffusion (Cfd) of the focus detection pixels and the non-focus detection pixels in the v4th and v5th rows. ) Is reset. After that, at time T53 to time T54, the output (N signal) after the reset release of the focus detection pixels and the non-focus detection pixels in the v4th and v5th rows is held by the control pulse PTN becoming a high level. The capacity 508 is held.

  Subsequently, after the S and N signals held in the holding capacitors 506 and 508 are AD-converted between time T54 and time T55, the signal ph is driven by the horizontal scanning unit 104 and transferred to the differential output circuit 110. Then, a differential signal between the S signal and the N signal is output. At time T55 to time T56, the signal HD (PSEL) is changed from the low level to the high level again, whereby reading of the unit pixel output of the next row (here, the v10th row and the v11th row) is started. Here, after time T56, since the pixel signal of the pixel in the focus detection pixel row has already been transferred to the floating diffusion (Cfd), vertical transfer and horizontal scanning similar to those at time T51 to time T55 are performed.

  By performing such a reading operation, the pixel signal of the focus detection pixel row in the solid-state imaging device can be read, and focus detection can be performed using the pixel signal read from the focus detection pixel. It becomes possible. Also, using the pixel signal read out from the non-focus detection pixel, the ratio of the pixel signal from one of the two non-focus detection pixels to be paired and the pixel signal from the other pixel is combined. By calculating each time, the distance to the subject can be calculated by the TOF method.

  Here, during the period from time T44 to time T45, after the signals from the photodiodes (PD) 401 of all focus detection pixels are transferred to the floating diffusion (Cfd), the signals from the non-focus detection pixels are transferred. Is going. That is, during the period from time T46 to time T48 and the period from time T48 to time T50, the signal from the photodiode (PD) 401 of the non-focus detection pixel is transferred to the floating diffusion (Cfd). This is to prevent projection light used in distance detection by the TOF method from affecting the focus detection pixels.

  In addition, when the signal from the photodiode (PD) 401 is transferred to the floating diffusion (Cfd) and then transferred to the holding capacitors 506 and 508, noise is superimposed on the signal transferred to the holding capacitor later due to a leak component or the like. There is a concern. However, since the number of pixel rows of the focus detection pixels is smaller than the number of pixel rows of the imaging pixels, the influence is minimized.

  FIG. 9 is a diagram illustrating an example of a moving image capturing pixel signal and a focus detection pixel row signal reading operation at the time of moving image capturing described with reference to FIGS. 7 and 8. In FIG. 9, the vertical direction indicates vertical scanning (read pixel row), and the horizontal direction indicates time. 7 and 8, only pixel signal transfer, vertical transfer, and horizontal transfer during one frame have been described. In the distance detection by the TOF method, since the light is projected onto the subject, the reset of the photodiode (PD) 401 is performed after the projection of the pulsed light to the subject is finished so that the influence does not affect the pixel signal for moving image shooting. There is a need to do. That is, it is necessary to reset the photodiode (PD) 401 (pixel reset shown in FIG. 9) after the pulse signal pled becomes low level. Therefore, in the present embodiment, these scans are performed row by row every two rows as shown in FIG.

  Next, as an example of control of the imaging apparatus according to the present embodiment, an example in which driving control of the imaging lens is performed based on pixel signals obtained by reading signals of focus detection pixel rows during moving image shooting will be described. FIG. 10 shows a method for driving a photographing lens based on pixel signals obtained by reading signals from focus detection pixel rows during moving image photographing described with reference to FIGS. 7 to 9 in the imaging apparatus according to the present embodiment. It is a flowchart explaining these.

  In step 1001, a pixel signal is read from the solid-state imaging device 100 as described with reference to FIGS. That is, row-thinning readout of the imaging row is performed to read out the moving image capturing pixel signal, and then the pixel signal is read out from the pixels (focus detection pixel and non-focus detection pixel) in the focus detection pixel row.

  In step 1002, the signal processing unit 204 calculates the distance to the subject by the TOF method using the pixel signals of the non-focus detection pixels read out by the driving shown in FIG. In step 1003, the signal processing unit 204 performs focus detection by the phase difference AF method using the pixel signals of the focus detection pixels read out by the driving shown in FIG. In step 1004, the signal processing unit 204 calculates the distance to the subject from the focus detection information (so-called defocus amount) obtained in step 1003.

  In step 1005, the control unit 205 determines whether the subject distance calculated by the signal processing unit 204 in each of step 1002 and step 1004 is within a predetermined distance range. That is, whether the difference between the subject distance obtained by the TOF method obtained in step 1002 and the subject distance obtained from the defocus amount in step 1004 is within a predetermined range, that is, the distance detection results by the two methods are approximated. It is determined whether or not.

  As a result of the determination, if the distance detection results by the two methods are approximate (within a predetermined distance range), in step 1006, the control unit 205 assumes that the focus detection result obtained in step 1003 is reliable. The photographing lens 201 is driven according to the focus detection result. On the other hand, if the distance detection results by the two methods are not approximate (outside the predetermined distance range) as a result of the determination, in step 1007, the control unit 205 determines whether the subject brightness is dark.

  Here, it is generally known that the phase difference AF method has a low accuracy in a dark scene, but the TOF method has a high accuracy because a dark scene is less affected by external light. Therefore, if the result of determination in step 1007 is that the subject is dark, in step 1008 the control unit 205 drives the taking lens 201 in accordance with the result of the TOF method. On the other hand, if the result of determination in step 1007 is that the subject is not dark, in step 1006 the control unit 205 drives the photographic lens 201 in accordance with the focus detection result. Thereafter, the operation is terminated at step 1009.

  In this embodiment, the distance to the subject is obtained by focus detection by phase difference AF using the pixel signal of the focus detection pixel and distance detection to the subject by the TOF method using the pixel signal of the non-focus detection pixel. According to the calculation result of the distance to the subject obtained by these two methods, the photographing lens can be driven to the optimum position by operating as shown in FIG. Can be generated.

  According to this embodiment, it is possible to perform focus detection by phase difference AF using the pixel signal of the focus detection pixel, and from the pixel signal of the non-focus detection pixel arranged in the same row as the focus detection pixel. The distance to the subject can be calculated by the TOF method. Thereby, the non-focus detection pixels arranged in the same row as the focus detection pixels can be effectively used, and the distance detection accuracy can be improved. In addition, for example, since the photographing lens can be driven to an optimal position using the obtained focus detection result by the phase difference AF and the distance detection result by the TOF method, a good photographic image without blur is generated. It becomes possible.

(Other embodiments of the present invention)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  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 as being limited thereto. 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: Solid-state image sensor 201: Shooting lens 202: Light emitting element 203: Timing generation circuit 204: Signal processing circuit 205: Control part 401: Photodiode 402: Transfer transistor 403: Reset transistor 404: Amplification transistor 405: Selection transistor

Claims (7)

A plurality of pixels are two-dimensionally arranged. As the plurality of pixels, a plurality of first pixels that photoelectrically convert a subject image formed by a photographing lens to generate an image generation signal, and the first A solid-state imaging device having a plurality of second pixels that are discretely arranged between the pixels and generate a signal for phase difference detection by photoelectrically converting a subject image from a region obtained by dividing the pupil region of the photographing lens When,
A light projecting means for projecting pulsed light onto a subject;
An image is generated based on signals from the plurality of first pixels, focus detection is performed based on signals from the plurality of second pixels, and the first pixels arranged in the same row as the second pixels Based on signals from the plurality of third pixels obtained by photoelectric conversion of the light reflected by the subject of the pulsed light projected by the light projecting means by a plurality of third pixels different from the second pixel. And a processing means for detecting the distance to the subject.   The processing means detects a distance to a subject based on a ratio of a signal from one of the two pixels in the pair and a signal from the other pixel. Item 2. The imaging device according to Item 1. Each of the pixels includes a photodiode, a floating diffusion, and a transfer transistor that transfers a signal from the photodiode to the floating diffusion.
In the signal readout from the pixel, the transfer transistor of the second pixel is driven to transfer the signal from the photodiode to the floating diffusion, and then the transfer transistor of the third pixel is driven to 3. The imaging apparatus according to claim 1, wherein a signal from a photodiode is transferred to the floating diffusion.   The said 2nd pixel is arrange | positioned in the row | line | column which is not read out of a signal, when reading a signal by carrying out line thinning from the said solid-state image sensor, The any one of Claims 1-3 characterized by the above-mentioned. The imaging device described in 1.   The imaging apparatus according to claim 1, wherein the first pixel is reset after the projection of the pulsed light onto the subject by the light projecting unit is completed.   6. The driving control of the photographing lens according to claim 1, wherein the photographing lens is driven and controlled according to a distance to a subject based on a result of the focus detection by the processing means and a distance to the subject based on a result of the distance detection. The imaging device according to item. A plurality of pixels are two-dimensionally arranged. As the plurality of pixels, a plurality of first pixels that photoelectrically convert a subject image formed by a photographing lens to generate an image generation signal, and the first A solid-state imaging device having a plurality of second pixels that are discretely arranged between the pixels and generate a signal for phase difference detection by photoelectrically converting a subject image from a region obtained by dividing the pupil region of the photographing lens A method of controlling an imaging apparatus that generates an image based on signals from a plurality of the first pixels,
Projecting pulsed light onto the subject by the light projecting means of the imaging device;
Performing focus detection based on signals from the plurality of second pixels;
Based on a signal obtained by photoelectrically converting the light reflected by the subject of the pulsed light by a plurality of third pixels different from the second pixels arranged in the same row as the second pixels. And a method of detecting a distance to a subject.

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