JP5414358B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus.

  As one of methods for detecting the focus state of a photographing lens, Patent Document 1 describes an apparatus that performs pupil division type focus detection using a two-dimensional sensor in which a microlens is formed on each pixel of an imaging sensor. Yes. In the apparatus of Patent Document 1, the photoelectric conversion unit of each pixel constituting the imaging sensor is divided into a plurality of parts, and the divided photoelectric conversion unit receives different areas of the pupil of the photographing lens through the microlens. It is composed.

  In recent years, CMOS image sensors capable of reading image signals at high speed have been used in imaging devices such as digital still cameras and digital video camcorders as the number of pixels in the pixel array increases.

  The present applicant discloses an imaging apparatus that performs pupil-division focus detection using a CMOS image sensor in Patent Document 2. The CMOS image sensor of Patent Document 2 has a configuration in which the photoelectric conversion unit is divided into two parts to detect the focus state of the photographing lens in some of the many pixels constituting the CMOS image sensor. Yes. The photoelectric conversion unit is configured to receive a predetermined region of the pupil of the photographing lens via the microlens. FIG. 12 shows a drawing similar to FIG.

  In the pixel array PA illustrated in FIG. 12, R, G, and B indicate pixels that are R, G, and B pixels in the Bayer array and are not used for focus detection. On the other hand, a focus detection pixel group in which the photoelectric conversion unit is divided into two is arranged at a part of the pixel position corresponding to the G pixel in the Bayer array. In FIG. 12, the photoelectric conversion unit of the focus detection pixel group is shown in white.

  In addition, the CMOS image sensor disclosed in Patent Document 2 includes a focus detection pixel group in which the photoelectric conversion unit is divided in the horizontal direction so that a vertical stripe subject can be easily detected, and a photoelectric detection so that a horizontal stripe subject can be easily detected. The conversion unit has a focus detection pixel group divided in the vertical direction. FIG. 12 shows a plurality of first pixels P1 (1,1) to P1 (5,7) as a focus detection pixel group in which the photoelectric conversion unit is divided in the horizontal direction (row direction). A plurality of second pixels P2 (3, 2) to P2 (7, 8) are shown as a focus detection pixel group in which the photoelectric conversion unit is divided in the vertical direction (column direction).

  In an image pickup apparatus having such a CMOS image sensor, photoelectric conversion in which light beams transmitted through the first region and the second region shifted in the horizontal direction on the pupil of the photographing lens are divided in the horizontal direction in the focus detection pixels. Each department receives. Then, the focal state of the photographing lens is detected by performing a correlation operation between the image generated by the light beam transmitted through the first region on the pupil of the photographing lens and the image generated by the light beam transmitted through the second region. . At this time, if the photographing lens is in an in-focus state, the phase of the image generated by the light beam transmitted through the first region on the pupil of the photographing lens and the phase of the image generated by the light beam transmitted through the second region are Match. On the other hand, if the photographic lens is not in focus, the phase of the image generated by the light beam transmitted through the first area on the pupil of the photographic lens deviates from the phase of the image generated by the light beam transmitted through the second area. In this way, the in-focus state of the taking lens is detected.

  Patent Document 3 describes that focus detection is performed by performing correlation calculation of an image generated from a light beam that has passed through different pupil regions of a photographing lens.

JP-A-58-24105 JP 2005-106994 A JP-A-5-127074

  In the CMOS image sensor shown in FIG. 13, the signal accumulation operation is sequentially started from the first row to the 32nd row in the pixel array PAi, and then the accumulation operation is sequentially performed from the first row to the 32nd row. The operation of reading the signal is performed. That is, in the CMOS image sensor, a slit rolling shutter operation is performed. In this case, the timing of the signal accumulation operation in the pixel is different for each row.

  Here, in the pixel array PAi, a focus detection pixel group in a horizontally long region TR for obtaining an AF (Auto Focus) image having a horizontal field of view (row direction field of view) and an AF image of a vertical field of view (column direction field of view) are obtained. It is assumed that the focus detection pixel group in the vertically long region LR to be obtained is arranged. In FIG. 13, the focus detection pixels are indicated by black squares for convenience.

  In the horizontally long region TR, for example, the signal accumulation operation timing in the focus detection pixel P2 (12, 7) located in the 12th row and the focus detection pixel P2 (11, 48) located in the 11th row. The timing of the signal accumulation operation is almost the same. At this time, when the subject approaches or moves away from the imaging device, the motion of the subject image formed on the pixel array PAi occurs. Even in this case, the distance to the subject indicated by the signal of the focus detection pixel P2 (12, 7) is almost the same as the distance to the subject indicated by the signal of the focus detection pixel P2 (11, 48).

  On the other hand, in the vertically long region LR, for example, the timing of the signal accumulation operation in the focus detection pixel P1 (3, 20) located in the third row and the focus detection pixel P1 (31 in the 31st row). , 24) is significantly different from the timing of the signal accumulation operation. At this time, when the subject approaches or moves away from the imaging device, the motion of the subject image formed on the pixel array PAi occurs. In this case, the distance to the subject indicated by the signal of the focus detection pixel P1 (3, 20) and the distance to the subject indicated by the signal of the focus detection pixel P1 (31, 24) may be greatly different. .

  Here, a longitudinal visual field AF image is obtained from the focus detection pixel group signal in the vertically long region LR, and a lateral visual field AF image is obtained from the focus detection pixel group signal in the laterally long region TR. In this case, the distance to the subject indicated by the longitudinal visual field AF image is less reliable than the distance to the subject indicated by the lateral visual field AF image. As a result, when focus adjustment is performed using an AF image with a vertical field of view and an AF image with a horizontal field of view, the accuracy of focus adjustment may be reduced.

  On the other hand, if focus adjustment is performed using only the lateral view AF image, there is a possibility that the focus adjustment cannot be performed depending on the subject.

  An object of the present invention is to improve the accuracy of focus adjustment for a photographic lens in an imaging apparatus.

An imaging apparatus according to one aspect of the present invention is a photographic lens and a pixel array in which an image of a subject is formed by the photographic lens, wherein a plurality of pixels are arranged in a row direction and a column direction, and the plurality of pixels Are a first focus detection pixel group that photoelectrically converts an image of a subject from a first exit pupil region that is a part of the entire exit pupil region of the photographing lens, and the entire exit pupil region of the photographing lens. A second focus detection pixel group that photoelectrically converts a subject image from a second exit pupil region that is a part of the first exit pupil region and is biased in a row direction with respect to the first exit pupil region; A third focus detection pixel group that photoelectrically converts an image of a subject from a third exit pupil area that is a part of the exit pupil area, and a part of the entire exit pupil area of the photographing lens. Fourth exit pupil region biased in a column direction with respect to the third exit pupil region A pixel array including a fourth focus detection pixel group that photoelectrically converts a subject image from the camera, and a shooting pixel group that photoelectrically converts a subject image from all exit pupil regions of the photographing lens, and the pixel array An imaging sensor having a selection unit that sequentially selects the rows in the image sensor; a readout unit that reads out signals from the pixels in the row selected by the selection unit; and the first focus detection pixel that is read out by the readout unit. First focus detection means for detecting the focus state of the photographing lens in the field of view in the row direction using the group signal and the signal of the second focus detection pixel group, and read by the readout means Second focus detection means for detecting a focus state of the photographing lens in a field of view in a column direction using a signal of the third focus detection pixel group and a signal of the fourth focus detection pixel group; In the pixel array A motion detection unit configured to detect the motion of the image of the subject formed, and when the motion detection unit detects the motion of the image of the subject, the detection result of the first focus detection unit is expressed with a first weight. A focus adjustment unit that performs focus adjustment by using a detection result of the second focus detection unit used with a second weight lower than the first weight, and in which the imaging pixel group is disposed The first focus detection pixel group, the second focus detection pixel group, the third focus detection pixel group, and the fourth focus detection pixel group are each discrete in a first period . It is arranged in order.

  According to the present invention, in the imaging apparatus, it is possible to improve the accuracy of focus adjustment for the photographic lens.

1 is a diagram illustrating a configuration of an imaging apparatus 1 according to a first embodiment of the present invention. The figure which shows the structure of the CMOS image sensor 100 in 1st Embodiment of this invention. FIG. 9 illustrates a structure of a pixel. The figure which shows the layout structure of pixel array PA100 of the CMOS image sensor 100 in 1st Embodiment of this invention. The figure which shows the cross-sectional structure of the CMOS image sensor 100 in 1st Embodiment of this invention. FIG. 4 is a diagram for explaining a light receiving region on a pupil of a photographing lens 5 of focus detection pixels arranged in a part of the CMOS image sensor 100. The figure which shows the structure of the CMOS image sensor 100i in the modification of 1st Embodiment of this invention. The timing chart which shows operation | movement of the CMOS image sensor 100i in the modification of 1st Embodiment of this invention. 3 is a flowchart showing a focus adjustment operation of the imaging apparatus 1 according to the first embodiment of the present invention. 9 is a flowchart showing a focus adjustment operation of the imaging apparatus according to the second embodiment of the present invention. 10 is a flowchart showing a focus adjustment operation of the imaging apparatus according to the third embodiment of the present invention. The figure for demonstrating background art. The figure for demonstrating a subject.

  An imaging apparatus 1 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of an imaging apparatus 1 according to the first embodiment of the present invention.

  The imaging device 1 is, for example, a single-lens reflex digital still camera. The imaging device 1 includes a photographing lens 5 and a main body 2. The photographing lens 5 is configured to be detachable from the main body 2.

  The photographing lens 5 includes a lens 5a, a zoom lens 5c, a focus lens 5b, a diaphragm device 53, a lens CPU 50, a lens driving mechanism 55, a diaphragm driving mechanism 52, a lens driving mechanism 51, and a shake detection device 54.

  The lens 5a refracts the incident light and guides it to the zoom lens 5c.

  The zoom lens (movable optical element) 5c is arranged between the lens 5a on the optical axis LA and the diaphragm device 53, and guides the light guided from the lens 5a to the focus lens 5b via the diaphragm device 53. . The zoom lens is configured to be movable along the optical axis LA.

  The aperture device 53 is disposed between the zoom lens 5c and the focus lens 5b on the optical axis LA, and adjusts the amount of light guided to the focus lens 5b after passing through the zoom lens 5c. The diaphragm device 53 is disposed in the vicinity of the pupil plane of the photographing lens 5.

  The focus lens 5b is arranged between the diaphragm 53 on the optical axis LA and a CMOS image sensor 100 described later, and refracts the guided light to image the subject on the imaging surface (pixel array) of the CMOS image sensor 100. Form.

  The lens CPU 50 performs various control operations in accordance with instructions received from the main body 2 via the electrical contacts 26.

  For example, when receiving an instruction to change the image magnification, the lens CPU 50 controls the lens driving mechanism 55 so that the image magnification according to the instruction is obtained. Thereby, the lens driving mechanism (driving means) 55 moves (drives) the zoom lens 5c along the optical axis LA so that an image magnification according to the instruction can be obtained. At this time, the lens CPU 50 supplies information indicating that the zoom lens 5 c is being driven to the main body 2 via the electrical contact 26.

  For example, when receiving an aperture value change instruction, the lens CPU 50 controls the aperture drive mechanism 52 so that an exposure value corresponding to the instruction is obtained. Thereby, the aperture drive mechanism 52 adjusts the opening degree of the aperture device 53 so that the aperture value according to the instruction is obtained.

  For example, when receiving a focus adjustment operation instruction (focus adjustment information), the lens CPU 50 controls the lens driving mechanism 51 so as to perform a focus adjustment operation in accordance with the instruction. Thereby, the lens driving mechanism 51 moves (drives) the focus lens 5b to the in-focus position along the optical axis LA.

  The shake detection device 54 includes a vibration gyro and detects the shake of the imaging device. The shake detection device 54 supplies the detection result to the main body 2 via the lens CPU 50 and the electrical contact 26.

  The main body 2 includes a CMOS image sensor (imaging sensor) 100, an image sensor control circuit 21, an image processing unit 24, a liquid crystal display element driving circuit 25, a liquid crystal display element 9, an eyepiece lens 3, a memory circuit 22, and a CPU 20.

  The CMOS image sensor 100 is disposed on the planned imaging plane of the taking lens 5. The CMOS image sensor 100 converts a subject image formed in a pixel array into an image signal. The CMOS image sensor 100 reads out the image signal from the pixel array and outputs it.

  Specifically, as shown in FIG. 2, the CMOS image sensor 100 includes a pixel array PA100, a vertical scanning circuit (selecting means) 116, a readout circuit 130, a horizontal scanning circuit 115, and an output amplifier 114. FIG. 2 is a diagram showing a configuration of the CMOS image sensor 100 according to the first embodiment of the present invention.

  In the pixel array PA100, a plurality of pixels are arrayed in the row direction and the column direction. The plurality of pixels include a first pixel group, a second pixel group, a third pixel group, a fourth pixel group, and a fifth pixel group.

  The first pixel group photoelectrically converts a subject image from a first exit pupil region (for example, regions Sα1 to Sα4 shown in FIG. 6) which is a part of the entire exit pupil region of the photographing lens 5. Pixel group. The second pixel group is a part of the entire exit pupil area of the photographic lens 5 and is a second exit pupil area (for example, the areas Sβ1 to S1 shown in FIG. 6) that is biased in the row direction with respect to the first exit pupil area. A pixel group for photoelectrically converting the image of the subject from Sβ4).

  Further, the first pixel group is a group of pixels arranged in the row direction for obtaining an AF image in the field of view in the row direction (lateral field of view, distance measuring field in the x direction shown in FIG. 4) (see FIG. 4). 4 and Pα1 to Pα4) arranged in the row direction. The second pixel group is a pixel group (a group of pixels arranged in the row direction for obtaining an AF image of a field of view in the row direction (horizontal field of view, a distance measuring field in the x direction shown in FIG. 4)). Pβ1 to Pβ4) arranged in the row direction. The first pixel group and the second pixel group are arranged at positions shifted in the row direction in the pixel array PA100.

  The third pixel group is a third exit pupil area that is a part of the entire exit pupil area of the photographing lens 5 (for example, an area obtained by rotating the areas Sα1 to Sα4 shown in FIG. 6 by 90 degrees clockwise). This is a pixel group for photoelectrically converting the image of the subject from The fourth pixel group is a part of the entire exit pupil area of the photographic lens 5 and is a fourth exit pupil area (for example, the areas Sβ1 to S1 shown in FIG. 6) that is biased in the column direction with respect to the third exit pupil area. This is a pixel group for photoelectrically converting an image of a subject from a region obtained by rotating Sβ4 by 90 degrees clockwise.

  The third pixel group is a group of pixels arranged in the column direction (see FIG. 4) for obtaining an AF image of the column direction field of view (vertical field of view, distance measurement field of y direction shown in FIG. 4). Qα1 to Qα4) arranged in the column direction shown in FIG. The fourth pixel group is a pixel group (a group of pixels arranged in the column direction for obtaining an AF image of a field of view in the column direction (vertical field of view, a distance measuring field of y direction shown in FIG. 4) (see FIG. 4). Qβ1 to Qβ4) arranged in the column direction. The third pixel group and the fourth pixel group are arranged at positions shifted from each other in the column direction in the pixel array PA100.

  The fifth pixel group is a pixel group for photoelectrically converting a subject image from all exit pupil regions of the photographing lens. The fifth pixel group is a pixel group that is a group of pixels for obtaining an image, and is a pixel group excluding the first to fourth pixel groups in the pixel array PA100 (R, Pixel groups indicated as G and B).

  Here, as shown in FIG. 3, each pixel P1 in the first pixel group includes a first photoelectric conversion unit 11a, a transfer unit 12, a charge-voltage conversion unit 103, a reset unit 104, an output unit 105, and a selection unit. 106. FIG. 3 is a diagram illustrating a configuration of a pixel.

  The first photoelectric conversion unit 11a performs an accumulation operation for generating and accumulating charges (signals) corresponding to the received light. The first photoelectric conversion unit 11a is, for example, a photodiode.

  The transfer unit 12 transfers the charge of the first photoelectric conversion unit 11 a to the charge voltage conversion unit 103. The transfer unit 12 is, for example, a transfer transistor, and is turned on when an active level transfer control signal φTX is supplied from the vertical scanning circuit 116 to the gate, thereby converting the charge of the first photoelectric conversion unit 11a into a charge-voltage converter. The data is transferred to the unit 103.

  The charge-voltage converter 103 converts the transferred charge into a voltage. The charge-voltage conversion unit 103 is, for example, a floating diffusion.

  The reset unit 104 resets the charge / voltage conversion unit 103. The reset unit 104 is, for example, a reset transistor, and resets the charge-voltage conversion unit 103 by turning on when an active level reset control signal φRES is supplied from the vertical scanning circuit 116 to the gate.

  The output unit 105 outputs a signal corresponding to the voltage of the charge-voltage conversion unit 103 to the vertical signal line SL. The output unit 105 is, for example, an amplification transistor, and performs a source follower operation together with the constant current source 107 connected to the vertical signal line SL, whereby a signal corresponding to the voltage of the charge-voltage conversion unit 103 is sent to the vertical signal line SL. Output. That is, the output unit 105 outputs a noise signal corresponding to the voltage of the charge voltage conversion unit 103 to the vertical signal line SL in a state where the charge voltage conversion unit 103 is reset by the reset unit 104. The output unit 105 outputs an optical signal corresponding to the voltage of the charge-voltage conversion unit 103 to the vertical signal line SL in a state where the charge of the first photoelectric conversion unit 11 a is transferred to the charge-voltage conversion unit 103 by the transfer unit 12. .

  The selection unit 106 puts the pixel P1 into a selected state / non-selected state. The selection unit 106 is, for example, a selection transistor, and is turned on when an active level selection control signal φSEL is supplied from the vertical scanning circuit 116 to the gate, thereby bringing the pixel P1 into a selected state. The selection unit 106 turns off when the selection control signal φSEL of the non-active level is supplied from the vertical scanning circuit 116 to the gate, thereby bringing the pixel P1 into a non-selected state.

  Each pixel P2 in the second pixel group is different from each pixel P1 in the first pixel group in that it includes a second photoelectric conversion unit 11b instead of the first photoelectric conversion unit 11a. Each pixel P3 in the third pixel group is different from each pixel P1 in the first pixel group in that it includes a third photoelectric conversion unit 11c instead of the first photoelectric conversion unit 11a. Each pixel P4 in the fourth pixel group is different from each pixel P1 in the first pixel group in that it includes a fourth photoelectric conversion unit 11d instead of the first photoelectric conversion unit 11a. Each pixel P5 in the fifth pixel group is different from each pixel P1 in the first pixel group in that it includes a fifth photoelectric conversion unit 11e instead of the first photoelectric conversion unit 11a.

  The relative position in the center pixel of the light receiving region of the first photoelectric conversion unit 11a (for example, the white region in the pixel Pα1 shown in FIG. 4) is within the pixel in the center of the light receiving region of the fifth photoelectric conversion unit 11e. Shifting to the first side (left side) in the row direction (x direction) with respect to the relative position. As a result, the first photoelectric conversion unit 11a receives the light in the first region that is biased from the center in the pupil region of the photographing lens 5 toward the first side (left side) in the row direction (x direction). The photoelectric conversion unit 11 e receives light from a region including the center in the pupil region of the photographing lens 5.

  The relative position in the center pixel of the light receiving region of the second photoelectric conversion unit 11b (for example, the white region in the pixel Pβ1 shown in FIG. 4) is within the pixel in the center of the light receiving region of the first photoelectric conversion unit 11a. The relative position is shifted to the second side (right side) in the row direction (x direction). Accordingly, the second photoelectric conversion unit 11b receives light in the second region that is biased from the first region in the pupil region of the photographing lens 5 to the second side (right side) in the row direction (x direction).

  The relative position in the center pixel of the light receiving region of the third photoelectric conversion unit 11c (for example, the white region in the pixel Qα1 shown in FIG. 4) is within the pixel in the center of the light receiving region of the fifth photoelectric conversion unit 11e. Shifting to the third side (upper side) in the column direction (y direction) with respect to the relative position. As a result, the third photoelectric conversion unit 11 c receives the light in the third region that is biased from the center in the pupil region of the photographic lens 5 to the third side (upper side) in the column direction (y direction).

  The relative position in the center pixel of the light receiving region of the fourth photoelectric conversion unit 11d (for example, the white region in the pixel Qβ1 shown in FIG. 4) is within the pixel in the center of the light receiving region of the third photoelectric conversion unit 11a. Shifting to the fourth side (lower side) in the column direction (y direction) with respect to the relative position. Accordingly, the fourth photoelectric conversion unit 11d receives the light in the fourth region that is biased from the third region in the pupil region of the photographing lens 5 to the fourth side (lower side) in the column direction (y direction). .

  2 scans the pixel array PA100 in the vertical direction (column direction), and sequentially selects rows (reading rows) from which signals in the pixel array PA100 are to be read. Specifically, the vertical scanning circuit 116 sequentially performs signal accumulation operation from the pixel in the uppermost row to the pixel in the lowermost row in the pixel array PA100, and then performs the operation from the pixel in the uppermost row to the lowermost row. The signals are sequentially read out to the pixels.

  The readout circuit 130 reads out signals (noise signals and optical signals) from the pixels in each column in the row selected by the vertical scanning circuit 116, and temporarily holds the read signals in each column. Specifically, after the signal accumulation operation is started, the readout circuit 130 sequentially receives signals (optical signals) from the pixel in the uppermost row to the pixel in the lowermost row in the pixel array PA100. ). Thereby, the slit rolling shutter operation of the CMOS image sensor 100 is realized. Here, the pixels in each row in the pixel array PA100 have different signal accumulation timings.

  The read circuit 130 includes transfer switches 133 and 134, CTN 137, CTS 138, and transfer switches 135 and 136 (see FIG. 7). The transfer switch 133 transfers the noise signal output to the vertical signal line SL to the CTN 137 by turning on when the active level control signal φTN is supplied to the gate. Thereafter, when the transfer switch 133 is turned off, the CTN 137 temporarily holds the transferred noise signal. The transfer switch 134 is turned on when the active level control signal φTS is supplied to the gate, thereby transferring the optical signal output to the vertical signal line SL to the CTS 138. Thereafter, when the transfer switch 134 is turned off, the CTS 138 temporarily holds the transferred optical signal. The transfer switch 135 is turned on when an active level horizontal scanning signal is supplied from the horizontal scanning circuit 115 to the gate, thereby transferring the noise signal held in the CTN 137 to the output amplifier 114 via the horizontal signal line 137. The transfer switch 136 is turned on when an active level horizontal scanning signal is supplied from the horizontal scanning circuit 115 to the gate, thereby transferring the optical signal held in the CTS 138 to the output amplifier 114 via the horizontal signal line 138.

  Note that the horizontal signal line 137 and the horizontal signal line 138 are provided with a reset switch 113. The reset switch 113 is turned on when an active level control signal φHc is supplied to the gate, thereby resetting the potentials of the horizontal signal line 137 and the horizontal signal line 138 to the reset potential VHc.

  The horizontal scanning circuit 115 scans the readout circuit 130 in the horizontal direction (row direction), thereby sequentially transferring the signals (noise signal, optical signal) of each column held in the readout circuit 130 to the output amplifier 114. That is, the horizontal scanning circuit 115 sequentially supplies an active level horizontal scanning signal to the gates of the transfer switches 135 and 136 of each column in the readout circuit 130.

  The output amplifier 114 generates and outputs an image signal based on the transferred signal (noise signal, optical signal). For example, the output amplifier 114 generates and outputs an image signal by performing CDS processing for obtaining an image signal from which noise has been removed by taking a difference between a noise signal and an optical signal.

  An image sensor control circuit 21 shown in FIG. 1 controls driving of the CMOS image sensor 100. For example, the image sensor control circuit 21 generates and supplies signals for driving the vertical scanning circuit 116, the readout circuit 130, and the horizontal scanning circuit 115 to each of them.

  The image processing unit 24 receives the image signal output from the CMOS image sensor 100. The image processing unit 24 performs predetermined image processing on the received image signal.

  For example, the image processing unit 24 A / D converts the received image signal (analog signal) to generate an image signal (digital signal). The image processing unit 24 performs arithmetic processing such as various corrections on the generated image signal (digital signal) to generate image data.

  Then, the image processing unit 24 generates a display image signal (analog signal) from the image data, and supplies the generated display image signal to the liquid crystal display element driving circuit 25. Alternatively, the image processing unit 24 generates compressed image data for recording from the image data, and supplies the generated compressed image data for recording to the memory circuit 22. Alternatively, the image processing unit 24 supplies the image data to the interface circuit 23.

  The liquid crystal display element driving circuit 25 receives a display image signal from the image processing unit 24. The liquid crystal display element driving circuit 25 displays an image corresponding to the received image signal for display, that is, a subject image on the liquid crystal display element 9.

  The eyepiece 3 is arranged at a position where the subject image displayed on the liquid crystal display element 9 can be observed.

  The memory circuit 22 receives the compressed image data for recording from the image processing unit 24. The memory circuit 22 records the received compressed image data for recording on a predetermined recording medium. The predetermined recording medium may be an external recording medium detachably connected to the main body 2 or an internal recording medium fixedly arranged in the main body 2.

  An external device such as a personal computer is detachably connected to the interface circuit 23. The interface circuit 23 receives image data from the image processing unit 24. The interface circuit 23 outputs the received image data to a connected external device.

  The CPU 20 controls each part of the imaging device 1 as a whole.

  For example, the CPU 20 controls a focus adjustment operation for adjusting the focus of the photographing lens 5. Specifically, the CPU 20 includes a focus adjustment unit 20a. The focus adjustment unit 20a controls the focus adjustment operation. The focus adjustment unit 20a includes a first focus detection unit 20a1, a second focus detection unit 20a2, a motion detection unit 20a3, and a focusing unit 20a4.

  The first focus detection unit 20a1 includes a signal of the first pixel group (Pα1 to Pα4 shown in FIG. 4) read by the readout circuit 130 (see FIG. 2) and the first pixel group (Pβ1 shown in FIG. 4). To Pβ4) from the CMOS image sensor 100. The first focus detection unit 20a1 generates a first AF image in the visual field in the row direction from the signal of the first pixel group, and the second AF in the visual field in the row direction from the signal of the second pixel group. Generate an image. The first focus detection unit 20a1 compares the first AF image and the second AF image, that is, calculates the first shift amount in the row direction between the first AF image and the second AF image. As a result, the in-focus state of the photographic lens 5 in the field of view in the row direction is detected. The first focus detection unit 20a1 supplies the detection result to the focusing unit 20a4.

  The second focus detection unit 20a2 includes the signals of the third pixel group (Qα1 to Qα4 shown in FIG. 4) read by the readout circuit 130 (see FIG. 2) and the fourth pixel group (Qβ1 shown in FIG. 4). To Qβ4) from the CMOS image sensor 100. The second focus detection unit 20a2 generates a third AF image in the column direction visual field from the signal of the third pixel group, and the fourth AF in the column direction visual field from the signal of the fourth pixel group. Generate an image. The second focus detection unit 20a2 compares the third AF image and the fourth AF image, that is, calculates the second shift amount in the column direction between the third AF image and the fourth AF image. As a result, the in-focus state of the photographic lens 5 in the field of view in the column direction is detected. The second focus detection unit 20a2 supplies the detection result to the focusing unit 20a4.

  The motion detection unit 20a3 receives information indicating that the zoom lens 5c is being driven from the lens CPU 50 via the electrical contact 26. When the motion detection unit 20a3 receives information indicating that the zoom lens 5c is being driven, the motion detection unit 20a3 determines that the lens driving mechanism 55 is moving (driving) the zoom lens 5c along the optical axis LA. That is, the motion detection unit 20a3 detects the motion of the subject image formed in the pixel array PA100 (see FIG. 2) by detecting that the lens driving mechanism 55 is driving the zoom lens 5c. The motion detection unit 20a3 supplies the detection result to the focusing unit 20a4.

  When the motion detection unit 20a3 detects the movement of the subject image, the focusing unit 20a4 uses the detection result of the first focus detection unit 20a1 with the first weight and uses the detection result of the second focus detection unit 20a2. The photographic lens 5 is controlled by using a second weight lower than the first weight.

  Specifically, the focusing unit 20a4 uses a value obtained by multiplying the first deviation amount by a first weight and a value obtained by multiplying the second deviation amount by a second weight. The focus position of the focus lens 5b in the photographing lens 5 is calculated. The focusing unit 20 a 4 supplies a focus adjustment operation instruction (focus adjustment information) including information on the calculated focus position to the lens CPU 50 via the electrical contact 26. Accordingly, the lens CPU 50 moves (drives) the focus lens 5b to the in-focus position via the lens driving mechanism 51.

  In addition, when the motion detection unit 20a3 does not detect the movement of the subject image, the focusing unit 20a4 outputs the detection result of the first focus detection unit 20a1 and the detection result of the second focus detection unit 20a2 to the third level. The photographic lens 5 is controlled by using the weight of. Note that the third weight may be the same as the first weight.

  Specifically, the focusing unit 20a4 uses a value obtained by applying the third weight to the first deviation amount and a value obtained by applying the third weight to the second deviation amount, The focus position of the focus lens 5b in the photographing lens 5 is calculated. The focusing unit 20 a 4 supplies a focus adjustment operation instruction (focus adjustment information) including information on the calculated focus position to the lens CPU 50 via the electrical contact 26. Accordingly, the lens CPU 50 moves (drives) the focus lens 5b to the in-focus position via the lens driving mechanism 51.

  Here, when the lens driving mechanism 55 is driving the zoom lens 5c, the positional relationship in the distance direction between the subject and the CMOS image sensor changes with time, and the subject on the pixel array of the CMOS image sensor is equivalently changed. The statue moves.

  On the other hand, in the present embodiment, the following operation is performed. When the motion detection unit 20a3 detects the motion of the image of the subject and determines that the reliability of the focus detection result in the column direction field of view is low, the focus detection result in the column direction field of view is determined as the row direction field of view. The focus adjustment is performed using a weighting lower than the focus detection result in. Thereby, in the imaging apparatus, even when there is a movement in the image of the subject formed in the pixel array by the photographic lens, it is possible to suppress a decrease in focus adjustment accuracy with respect to the photographic lens.

  In addition, when the motion detection unit 20a3 does not detect the motion of the image of the subject and it is determined that the reliability of the focus detection result in the column direction field of view is not low, the focus detection result in the column direction field of view Is used with the same weighting as the focus detection result in the field of view in the row direction. Thereby, in the imaging apparatus, when there is no movement in the image of the subject formed in the pixel array by the photographing lens, it is possible to improve the focus adjustment accuracy with respect to the photographing lens.

  That is, in the imaging apparatus, it is possible to improve the accuracy of focus adjustment with respect to the photographic lens.

  Next, the layout configuration of the pixel array PA100 of the CMOS image sensor 100 will be described with reference to FIG. FIG. 4 is a diagram showing a layout configuration of the pixel array PA100 of the CMOS image sensor 100 according to the first embodiment of the present invention. FIG. 4 illustrates a case where the pixel array PA100 is configured with pixels of 16 rows × 16 columns. Actually, for example, the pixel pitch is 2 μm, the number of effective pixels is 3000 horizontal columns × 2000 vertical rows = 6 million pixels, and the size of the screen arrangement is 6 mm horizontal × 4 mm vertical.

  In the figure, reference numerals 131 and 132 denote wirings. The area delimited by the wirings 131 and 132 represents one pixel, and the characters “R”, “G”, and “B” written in one pixel represent the hue of the color filter of each pixel. The pixel on which the letter “R” is written includes a color filter that is disposed above the fifth photoelectric conversion unit 11 e and transmits red component light. The pixel on which the letter “G” is written includes a color filter that is disposed above the fifth photoelectric conversion unit 11 e and transmits green component light. The pixel on which the letter “B” is written includes a color filter that is disposed above the fifth photoelectric conversion unit 11e and transmits blue component light. Further, each pixel on which the letters “R”, “G”, and “B” are written is configured to receive the entire pupil region of the photographing lens 5.

  When the color filter array is a Bayer array, one picture element is composed of “R” and “B” pixels and two “G” pixels. In the present embodiment, the image sensor that constitutes the imaging apparatus has a focus detection pixel (first pixel) that receives a part of the pupil region of the photographing lens 5 in a part of the pixels that should be “R” or “B” in the Bayer array. 1 to 4) are allocated.

  In the figure, Pα1, Pβ1, Pα2, Pβ2, Pα3, Pβ3, Pα4, and Pβ4 are pixels for detecting the in-focus state of the taking lens 5, and the opening in the x direction in the figure is restricted by the wiring 131. Yes. In the focus detection pixels arranged in a part of the CMOS image sensor 100 of the present embodiment, eight types of aperture center positions in the x direction of the apertures limited by the wiring 131 are set with respect to the pixel center. Yes. The focus detection pixels having the same wiring opening are arranged in a cycle of 4 pixels in the + x direction in the drawing to form a distance measuring field (horizontal field) in the lateral (x) direction. In the imaging apparatus according to the present embodiment, photographing is performed based on the image generated by the focus detection pixels Pα1, Pβ1, Pα2, Pβ2, Pβ3, Pβ3, Pα4, and Pβ4 and the focus detection pixel group having the same wiring opening. The in-focus state of the lens 5 is detected. In particular, when a focus detection pixel group in which the wiring opening is deviated in the x direction in the drawing is used, good focus detection can be performed on a subject image having a contrast in the x direction in the drawing on the CMOS image sensor 100.

  For example, a focus detection pixel having a similar wiring opening at a position adjacent to four pixels in the x direction with respect to the focus detection pixel Pα1 in which the opening determined by the wiring 131_1 and the wiring 131_2 is deviated in the + x direction with respect to the pixel center. Pixels are arranged.

  In addition, a focus detection pixel Pβ1 in which an opening determined by the wiring 131_3 and the wiring 131_4 substantially coincides with the pixel center is disposed at a position obliquely adjacent to the focus detection pixel Pα1. Further, focus detection pixels having similar wiring openings are disposed at positions adjacent to the focus detection pixel Pβ1 by four pixels in the x direction.

  The focus detection pixels Pα2 and Pβ2, the focus detection pixels Pα3 and Pβ3, and the focus detection pixels Pα4 and Pβ4, which have different aperture positions determined by the wiring 131, are similarly arranged.

  Next, a cross-sectional configuration of the CMOS image sensor 100 will be described with reference to FIG. FIG. 5 is a diagram showing a cross-sectional configuration of the CMOS image sensor 100 according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view taken along the plane A-A ′ of FIG. 4.

  The right pixel in FIG. 5 indicates a pixel that can receive the entire pupil region of the photographic lens 5, and the left pixel in the drawing indicates a focus detection pixel that can receive a light beam from a part of the pupil region of the photographic lens 5. Is shown. Hereinafter, a case where the right pixel is the pixel P5 (see FIG. 3) and the left pixel is the pixel P1 (see FIG. 3) will be described as an example.

  The CMOS image sensor 100 shown in FIG. 5 includes the following components.

  The semiconductor substrate SB includes a first photoelectric conversion unit 11a and a fifth photoelectric conversion unit 11e, and a well 110 is formed around the first photoelectric conversion unit 11a and the fifth photoelectric conversion unit 11e. ing. The first photoelectric conversion unit 11a and the fifth photoelectric conversion unit 11e are semiconductor regions containing a high concentration of conductive (for example, N-type) impurities corresponding to charges (for example, negative charges). The well 110 is a semiconductor region containing an impurity of a conductivity type (for example, P type) opposite to the conductivity type at a low concentration.

  An interlayer insulating film 124 is provided between the photoelectric conversion unit (the first photoelectric conversion unit 11 a and the fifth photoelectric conversion unit 11 e) and the wiring 131, and an interlayer insulating film 125 is provided between the wiring 131 and the wiring 132. Is arranged. In addition, an interlayer insulating film 123 is disposed on the light incident side of the wiring 132, and a passivation film 140 and a planarizing layer 150 are further disposed.

  Color filter layers 151 and 154, a planarizing layer 152, and a microlens 153 are formed on the light incident side of the planarizing layer 150. Here, the power of the micro lens 153 is set so that the pupil of the photographing lens 5 and the photoelectric conversion unit are substantially conjugate. Further, in the pixel located at the center of the CMOS image sensor 100, the microlens 153 is disposed at the center of the pixel, and at the pixels located at the periphery, the microlens 153 is disposed offset to the optical axis side of the photographing lens 5.

  The subject light transmitted through the photographing lens 5 is condensed near the CMOS image sensor 100. Further, the light that reaches each pixel of the CMOS image sensor 100 is refracted by the microlens 153 and collected on the photoelectric conversion unit. In the pixel on the right side in the drawing used for normal imaging, a first wiring 131 and a second wiring 132 are provided so as not to block incident light.

  On the other hand, in the pixel that performs focus detection of the photographing lens 5 on the left side in the drawing, a part of the wiring 131 extends so as to cover the photoelectric conversion unit. As a result, the focus detection pixel on the left side in the drawing can receive a light beam that passes through a part of the pupil of the photographing lens 5. Further, in order to prevent the output of the photoelectric conversion unit from being reduced because the wiring 131 blocks a part of the incident light flux, the color filter layer 154 of the focus detection pixel is made of a resin having high transmittance that does not absorb light. Is formed.

  The focus detection pixels arranged in a part of the CMOS image sensor 100 of the present embodiment receive light on the pupil of the photographing lens 5 by making the relative position of the microlens 153 and the opening center of the wiring 131 different. The area is configured to be different.

  Next, the light receiving area on the pupil of the photographing lens 5 for each focus detection pixel will be described with reference to FIG. FIG. 6 is a diagram for explaining a light receiving area on the pupil of the photographing lens 5 of the focus detection pixels arranged in a part of the CMOS image sensor 100. In FIG. 6, the diagonal checkered area indicates the pupil of the photographic lens 5, and the white area indicates the light receiving area of the focus detection pixel.

  FIG. 6A shows a light receiving region on the pupil of the photographing lens 5 of the focus detection pixel Pα1 shown in the partial plan view of the CMOS image sensor 100 of FIG. The center of the opening determined by the wiring 131_1 and the wiring 131_2 of the focus detection pixel Pα1 is greatly deviated in the −x direction with respect to the center of the pixel. For this reason, the center of the light-receiving area Sα1 of the photoelectric conversion unit of the focus detection pixel Pα1 is a distance + xα1 deviation with respect to the optical axis (the intersection of the x axis and the y axis in the drawing) on the exit pupil of the photographing lens 5. doing.

  FIG. 6B shows a light receiving area on the pupil of the photographing lens 5 of the focus detection pixel Pβ1 shown in the partial plan view of the CMOS image sensor 100 of FIG. The center of the opening determined by the wiring 131_3 and the wiring 131_4 of the focus detection pixel Pβ1 is slightly deviated in the −x direction with respect to the center of the pixel. For this reason, the center of the light receiving region Sβ1 of the photoelectric conversion unit of the focus detection pixel Pβ1 is the distance + xβ1 deviation with respect to the optical axis (the intersection of the x axis and the y axis in the drawing) on the exit pupil of the photographing lens 5. doing.

  FIG. 6C shows a light receiving region on the pupil of the photographing lens 5 of the focus detection pixel Pα2 shown in the partial plan view of the CMOS image sensor 100 of FIG. The center of the opening determined by the wiring 131_1 and the wiring 131_2 of the focus detection pixel Pα2 is deviated by a predetermined amount in the −x direction with respect to the center of the pixel. For this reason, the center of the light receiving region Sα2 of the photoelectric conversion unit of the focus detection pixel Pα2 is the distance + xα2 deviation on the exit pupil of the photographing lens 5 with respect to the optical axis (the intersection of the x axis and the y axis in the drawing). doing.

  FIG. 6D shows a light receiving region on the pupil of the photographing lens 5 of the focus detection pixel Pβ2 shown in the partial plan view of the CMOS image sensor 100 of FIG. Since the center of the aperture determined by the wiring 131_3 and the wiring 131_4 of the focus detection pixel Pβ2 substantially coincides with the center of the pixel, the center of the light receiving region Sβ2 of the photoelectric conversion unit of the focus detection pixel Pβ2 is the shooting lens. 5 substantially coincides with the optical axis (the intersection of the x-axis and the y-axis in the figure) on the 5 exit pupil.

  FIG. 6E shows a light receiving region on the pupil of the photographing lens 5 of the focus detection pixel Pα3 shown in the partial plan view of the CMOS image sensor 100 of FIG. The center of the opening determined by the wiring 131_1 and the wiring 131_2 of the focus detection pixel Pα3 is slightly deviated in the −x direction with respect to the center of the pixel. Therefore, the center of the light receiving region Sα3 of the photoelectric conversion unit of the focus detection pixel Pα3 is the distance + xα3 deviation with respect to the optical axis (the intersection of the x axis and the y axis in the drawing) on the exit pupil of the photographing lens 5. doing.

  FIG. 6F shows a light receiving region on the pupil of the photographing lens 5 of the focus detection pixel Pβ3 shown in the partial plan view of the CMOS image sensor 100 of FIG. The center of the opening determined by the wiring 131_3 and the wiring 131_4 of the focus detection pixel Pβ3 is deviated by a predetermined amount in the + x direction with respect to the center of the pixel. For this reason, the center of the light receiving region Sβ3 of the photoelectric conversion unit of the focus detection pixel Pβ3 is a distance −xβ3 deviation with respect to the optical axis (the intersection of the x axis and the y axis in the drawing) on the exit pupil of the photographing lens 5. Is ranked.

  FIG. 6G shows a light receiving region on the pupil of the photographing lens 5 of the focus detection pixel Pα4 shown in the partial plan view of the CMOS image sensor 100 of FIG. Since the center of the opening determined by the wiring 131_1 and the wiring 131_2 of the focus detection pixel Pα4 is substantially coincident with the center of the pixel, the center of the light receiving region Sα4 of the photoelectric conversion unit of the focus detection pixel Pα4 is the photographic lens. 5 substantially coincides with the optical axis (the intersection of the x-axis and the y-axis in the figure) on the 5 exit pupil.

  FIG. 6H shows a light receiving area on the pupil of the photographing lens 5 of the focus detection pixel Pβ4 shown in the partial plan view of the CMOS image sensor 100 of FIG. The center of the opening determined by the wiring 131_3 and the wiring 131_4 of the focus detection pixel Pβ4 is greatly deviated in the + x direction with respect to the center of the pixel. Therefore, the center of the light receiving region Sβ4 of the photoelectric conversion unit of the focus detection pixel Pβ4 is a distance −xβ4 bias with respect to the optical axis (the intersection of the x axis and the y axis in the figure) on the exit pupil of the photographing lens 5. Is ranked.

  Similarly, in some of the focus detection pixels arranged in a part of the CMOS image sensor 100 of this embodiment, the center position of the opening limited by the wiring 132 is different in the y direction with respect to the pixel center. Type is set. In the figure, Qα1, Qβ1, Qα2, Qβ2, Qα3, Qβ3, Qα4, and Qβ4 are pixels for detecting the in-focus state of the taking lens 5, and the opening in the y direction in the figure is restricted by the wiring 132. The focus detection pixels having the same wiring opening are arranged in a cycle of 4 pixels in the −y direction in the drawing to form a distance measuring field in the vertical (y) direction.

  In the imaging apparatus of the present embodiment, photographing is performed based on images generated by focus detection pixels Qα1, Qβ1, Qα2, Qβ2, Qα3, Qβ3, Qα4, and Qβ4 and the focus detection pixel group having the same wiring opening. The in-focus state of the lens 5 is detected. In particular, when a focus detection pixel group in which the wiring opening is deviated in the y direction in the drawing is used, good focus detection can be performed on a subject image having a contrast in the y direction in the drawing on the CMOS image sensor 100.

  The light receiving areas on the pupil of the photographing lens 5 of the focus detection pixels Qα1, Qβ1, Qα2, Qβ2, Qα3, Qβ3, Qα4, and Qβ4 are focus detection pixels Pα1, Pβ1, Pα2, Pβ2, Pα3, Pβ3, Pα4, and Pβ4. The light receiving area is rotated by 90 °.

  The CMOS image sensor 100i may include a pixel unit array PUA100 instead of the pixel array PA100, as shown in FIG. In the pixel unit array PUA100, a plurality of pixel units PU11 to PU22 are arrayed in the row direction and the column direction. FIG. 7 illustrates a case where the pixel unit array PUA100 is configured by pixel units of 2 rows × 2 columns. FIG. 7 is a diagram showing a configuration of a CMOS image sensor 100i in a modification of the first embodiment of the present invention.

  Each of the pixel units PU11 to PU22 has a configuration in which the charge-voltage conversion unit 103, the reset unit 104, the output unit 105, and the selection unit 106 are shared by two pixels adjacent in the column direction in the pixel array PA100 illustrated in FIG. Yes. To the charge voltage conversion unit 103, the charge of the photoelectric conversion unit 111 is transferred by the transfer unit 121, and the charge of the photoelectric conversion unit 112 is transferred by the transfer unit 122.

  Next, the operation of the CMOS image sensor 100i shown in FIG. 7 will be described with reference to FIG. FIG. 8 is a timing chart showing the operation of the CMOS image sensor 100i in the modification of the first embodiment of the present invention.

  First, according to the timing output from the vertical scanning circuit 116, the control signal φL is set to high to reset the vertical signal line SL. Further, the control signal φR0 is set high, and the reset unit 104 is turned on.

  At time T0, the control signal φS0 is set high, the selection unit 106 is turned on, and the pixel units PU11 and PU12 in the first row are selected.

  Next, the reset of the charge voltage conversion unit 103 is completed by setting the control signal φR0 to low. The charge voltage conversion unit 103 is set in a floating state, and the gate and source of the output unit 105 are set to through. The output unit 105 outputs a noise signal corresponding to the voltage of the charge-voltage conversion unit 103 to the vertical signal line SL.

  At time T1, the control signal φTN is set high, and the noise signal output to the vertical signal line SL is transferred to the CTN 137.

  At time T2, the control signal φTXo0 is set high to turn on the transfer unit 121. Thereby, the charge of the photoelectric conversion unit 111 is transferred to the charge-voltage conversion unit 103. The output unit 105 outputs an optical signal corresponding to the voltage of the charge-voltage conversion unit 103 to the vertical signal line SL.

  At time T3, the control signal φTS is set high, and the optical signal output to the vertical signal line SL is transferred to the CTS 138.

  At time T4, the control signal φHC is temporarily set high to turn on the reset switch 113. As a result, the horizontal signal lines 137 and 138 are reset.

  In the horizontal transfer period, a pixel noise signal and an optical signal are output to the horizontal signal line by the horizontal scanning signal of the horizontal scanning circuit 115. The output amplifier 114 generates and outputs an image signal by taking the difference between the noise signal and the optical signal.

  Then, operations similar to those at times T0 to T4, but different in the following points, are performed on the photoelectric conversion unit 112.

  At time T5, instead of the operation at time T2, the control signal φTXe0 is set high to turn on the transfer unit 122. Thereby, the charge of the photoelectric conversion unit 112 is transferred to the charge-voltage conversion unit 103. The output unit 105 outputs an optical signal corresponding to the voltage of the charge-voltage conversion unit 103 to the vertical signal line SL.

  Here, in the period when the pixel units in one row are selected, the charge of the photoelectric conversion unit 111 is transferred to the charge-voltage conversion unit 103 until the charge of the photoelectric conversion unit 112 is transferred to the charge-voltage conversion unit 103. , | T5-T2 |

  Next, the focus adjustment operation of the imaging apparatus 1 will be described with reference to FIG. FIG. 9 is a flowchart showing the focus adjustment operation of the imaging apparatus 1 according to the first embodiment of the present invention.

  If the photographer performs a previous operation (SW1-ON) of a shutter release switch (not shown) (s201), the CPU 20 sends a signal to the image sensor control circuit 21 and takes an image with the CMOS image sensor 100. The focus adjustment unit 20a acquires an AF image signal among image signals captured by the CMOS image sensor 100 (s202).

  The focus adjustment unit 20a of the CPU 20 generates a first focus detection image from the focus detection pixel group having the same wiring opening as the focus detection pixel Pα1, and similarly, the focus having the same wiring opening as the focus detection pixel Pβ1. A second focus detection image is generated from the detection pixel group.

  The focus adjustment unit 20a performs correlation calculation based on the first focus detection image and the second focus detection image, thereby measuring the distance in the horizontal (x) direction where the focus detection pixels Pα1 and Pβ1 are located. The focus state def_hor_1 of the photographing lens 5 in the field of view is detected.

  Similarly, the focus adjustment unit 20a detects the in-focus state def_hor_2 of the photographing lens 5 in the lateral (x) direction distance measuring field in which the focus detection pixels Pα2 and Pβ2 are located.

  Similarly, the focus adjusting unit 20a detects the in-focus state def_hor_3 of the photographing lens 5 in the lateral (x) direction distance measuring field where the focus detection pixels Pα3 and Pβ3 are located.

  Similarly, the focus adjusting unit 20a detects the in-focus state def_hor_4 of the photographing lens 5 in the lateral (x) distance measuring field where the focus detection pixels Pα4 and Pβ4 are located.

  Then, the focus adjustment unit 20a averages the focus detection results def_hor_1 to def_hor_4 as in Expression 1.

def_hor = (def_hor_1 + def_hor_2 + def_hor_3 + def_hor_4) / 4 Equation 1
Next, the focus adjustment unit 20a of the CPU 20 generates a first focus detection image from the focus detection pixel group having the same wiring opening as the focus detection pixel Qα1, and similarly the same wiring opening as the focus detection pixel Qβ1. A second focus detection image is generated from the focus detection pixel group having.

  The focus adjusting unit 20a performs correlation calculation based on the first focus detection image and the second focus detection image, thereby performing distance measurement in the vertical (y) direction where the focus detection pixels Qα1 and Qβ1 are located. The focus state def_ver_1 of the photographing lens 5 in the visual field is detected.

  Similarly, the focus adjustment unit 20a detects the in-focus state def_ver_2 of the photographing lens 5 in the longitudinal (y) range-finding field in which the focus detection pixels Qα2 and Qβ2 are located.

  Similarly, the focus adjustment unit 20a detects the in-focus state def_ver_3 of the photographing lens 5 in the longitudinal (y) range-finding field in which the focus detection pixels Qα3 and Qβ3 are located.

  Similarly, the focus adjustment unit 20a detects the in-focus state def_ver_4 of the photographing lens 5 in the longitudinal (y) range-finding field in which the focus detection pixels Qα4 and Qβ4 are located.

  The focus adjustment unit 20a averages the focus detection results def_ver_1 to def_ver_4 as in Expression 2.

def_ver = (def_ver_1 + def_ver_2 + def_ver_3 + def_ver_4) / 4 Equation 2
When the focus detection of the distance measuring field in the horizontal (x) direction and the distance measuring field in the vertical (y) direction is completed (s203), the focus adjusting unit 20a checks whether the zoom lens 5c of the photographing lens 5 is being driven. (S204).

  If the zoom lens 5c is being driven, the subject image on the pixel array PA100 moves as the zoom lens 5c is driven. As a result, since the focus state of the image differs between the readout start line of the CMOS image sensor 100 and the subsequent lines, the reliability of the detection result of the focus state in the distance measuring field in the vertical (y) direction is reliable. Lower.

  Therefore, when the focus adjusting unit 20a detects that the zoom lens 5c is being driven through the lens driving mechanism 51 (s204), the focus adjusting unit 20a performs the following operation. The focus adjustment unit 20a sets the weight m_ver for the detection result in the distance measurement field in the vertical (y) direction to be smaller than the weight m_vhor for the detection result in the distance measurement field in the horizontal (x) direction (for example, m_ver = 0.0.1). 2. m_hor = 0.8) (s205).

  Alternatively, when it is confirmed that the zoom lens 5c is not being driven via the lens driving mechanism 51, the focus adjusting unit 20a performs the following operation. The focus adjustment unit 20a sets the same weight m_ver for the detection result in the distance measurement field in the vertical (y) direction and weight m_vhor for the detection result in the distance measurement field in the horizontal (x) direction (for example, m_ver = 0.0). 5. m_hor = 0.5) (s206).

  When the weight m_ver for the detection result of the focus state of the distance measuring field in the vertical (y) direction and the weight m_vhor for the detection result of the focus state of the distance measurement field in the horizontal (x) direction are set, the focus adjustment unit 20a Based on Formula 3, the in-focus state of the taking lens 5 is calculated (s207).

def = (m_hor * def_hor + m_ver * def_ver) / (m_hor + m_ver) Equation 3
When the in-focus state of the photographic lens 5 is calculated (s207), the focus adjustment unit 20a determines whether or not the photographic lens 5 is in focus based on the focus detection result (s208). If it is determined that the photographic lens 5 is not in focus (s208), the focus adjustment unit 20a sends focus adjustment information to the lens driving mechanism 51 based on the focus detection result to adjust the focus of the photographic lens 5. (S209).

  On the other hand, if it is determined that the taking lens 5 is in focus (s208), the process waits for the next operation (s210).

  As described above, according to the present embodiment, it is possible to perform good focus adjustment even when the image of the subject moves on the pixel array of the CMOS image sensor.

  Next, an imaging apparatus according to the second embodiment of the present invention will be described.

  The imaging apparatus according to the present embodiment is different in focus adjustment operation from the first embodiment as shown in FIG. FIG. 10 is a flowchart showing the focus adjustment operation of the imaging apparatus according to the second embodiment of the present invention. Below, it demonstrates centering on a different part from 1st Embodiment.

  The focus adjustment unit 20a of the CPU 20 averages the focus detection results def_hor_1 to def_hor_4 in the lateral (x) direction distance measuring field as represented by Equation 1. In addition, the focus adjustment unit 20a initially sets the focus detection result weight m_hor = 1 (s223).

  When the focus adjustment unit 20a finishes detecting the focus of the photographing lens 5 in the lateral (x) distance measurement field of view (s223), the imaging device 1 causes camera shake from the detection result information received from the shake detection device 54. Check if it is. That is, the motion detection unit 20a3 of the focus adjustment unit 20a detects the movement of the subject image formed in the pixel array PA100 by detecting the shake of the imaging device 1 (s224).

  If the imaging apparatus 1 is shaken, the subject image on the CMOS image sensor 100 moves. As a result, since the captured image differs between the read start line of the CMOS image sensor 100 and the subsequent lines, the reliability of the detection result of the in-focus state in the longitudinal (y) direction visual field is reliable. Lower.

  Therefore, when the focus adjustment unit 20a detects from the information of the shake detection device 54 that the imaging device 1 is shaken (s224), the focus adjustment unit 20a detects the in-focus state in the distance measuring field in the vertical (y) direction. First, the in-focus state of the photographic lens 5 is calculated based on the equation 3 (s226).

  At this time, since the in-focus state is not detected in the distance measurement visual field in the vertical (y) direction, the weight m_ver = 0 and the initial value are set.

  Alternatively, when the focus adjustment unit 20a detects from the information of the detection result by the shake detection device 54 that the imaging device 1 is not shaken (s224), the focus adjustment unit 20a is in the focused state in the distance measuring field in the vertical (y) direction. Detection is performed (s225).

  The focus adjustment unit 20a averages the focus detection results def_ver_1 to def_ver_4 as in Expression 2. In addition, the focus adjustment unit 20a initially sets the focus detection result weight m_ver = 1.

  When the focus detection of the distance measuring field in the vertical (y) direction is completed (s225), the in-focus state of the photographing lens 5 is calculated based on the above equation 3 (s226).

  Next, an imaging apparatus according to a third embodiment of the present invention will be described.

  The imaging apparatus according to the present embodiment is different in focus adjustment operation from the first embodiment as shown in FIG. FIG. 11 is a flowchart showing the focus adjustment operation of the imaging apparatus according to the third embodiment of the present invention. Below, it demonstrates centering on a different part from 1st Embodiment.

  When the image pickup apparatus 1 is turned on by the photographer, the CPU 20 sends a signal to the image sensor control circuit 21 and picks up an image with the CMOS image sensor 100. The captured image is subjected to image processing by the image processing unit 24. At this time, the image processing unit 24 determines the movement of the subject from a plurality of images having different shooting periods, and supplies the determination result to the CPU 20. That is, the motion detection unit 20a3 of the focus adjustment unit 20a detects the movement of the subject by comparing the image signals of a plurality of frames read from the pixel array by the readout circuit in a plurality of frame periods via the image processing unit 24. To do. Thereby, the motion detection unit 20a3 detects the motion of the image of the subject formed in the pixel array (s231).

  When the focus adjustment unit 20a finishes detecting the focus in the lateral (x) direction visual field and the longitudinal (y) direction visual field (s234), it is determined from the information from the image processing unit 24 whether the subject is a moving object. Is confirmed (s235).

  If the subject is a moving object, the subject image on the CMOS image sensor 100 moves. As a result, since the captured image differs between the read start line of the CMOS image sensor 100 and the subsequent lines, the reliability of the detection result of the in-focus state in the longitudinal (y) direction visual field is reliable. Lower.

  Therefore, when the focus adjustment unit 20a detects that the subject is a moving object from the information from the image processing unit 24 (s235), the focus adjustment unit 20a performs the following operation. The focus adjustment unit 20a sets the weight m_ver for the detection result in the distance measurement field in the vertical (y) direction to be smaller than the weight m_vhor for the detection result in the distance measurement field in the horizontal (x) direction (for example, m_ver = 0.0.1). 3. m_hor = 0.7) (s237).

  Alternatively, when it is confirmed from the information from the image processing unit 24 that the subject is not a moving object (s235), the focus adjustment unit 20a performs the following operation. The focus adjusting unit 20a sets the weight m_ver for the detection result in the longitudinal (y) direction visual field and the weight m_vhor for the detection result in the lateral (x) direction visual field (for example, m_ver = 0.5). M_hor = 0.5) (s236).

Claims (8)

A taking lens,
A pixel array in which an image of a subject is formed by the photographing lens, wherein a plurality of pixels are arranged in a row direction and a column direction, and the plurality of pixels are a part of a total exit pupil region of the photographing lens. A first focus detection pixel group that photoelectrically converts an image of a subject from a certain first exit pupil region, and a row for the first exit pupil region that is a part of the entire exit pupil region of the photographing lens A second focus detection pixel group that photoelectrically converts a subject image from the second exit pupil region biased in the direction, and a third exit pupil region that is a part of the entire exit pupil region of the photographing lens A third focus detection pixel group that photoelectrically converts the image of the subject from the fourth, and a fourth group that is a part of the entire exit pupil region of the photographing lens and is biased in the column direction with respect to the third exit pupil region Fourth focus detection image for photoelectrically converting the subject image from the exit pupil area A pixel array including a group and a photographing pixel group that photoelectrically converts an object image from all exit pupil regions of the photographing lens, a selection unit that sequentially selects rows in the pixel array, and a selection by the selection unit An image sensor having readout means for reading out signals from pixels in the designated row;
The focus state of the photographing lens in the field of view in the row direction is detected using the signal of the first focus detection pixel group and the signal of the second focus detection pixel group read by the readout means. First focus detection means;
The focus state of the photographing lens in the field of view in the column direction is detected using the signal of the third focus detection pixel group and the signal of the fourth focus detection pixel group read by the readout means. Second focus detection means;
Motion detection means for detecting the motion of the image of the subject formed in the pixel array;
When the movement of the image of the subject is detected by the motion detection unit, the detection result of the first focus detection unit is used as a first weight, and the detection result of the second focus detection unit is used as the first weight. Focusing means for adjusting the focus by using a lower second weight, and
The first focus detection pixel group, the second focus detection pixel group, the third focus detection pixel group, and the fourth focus detection pixel in a region where the photographing pixel group is disposed. An image pickup apparatus, wherein pixel groups are discretely arranged at a first period . The imaging sensor is a CMOS image sensor,
In the imaging sensor, the selection unit causes the pixels in each row in the pixel array to sequentially accumulate signals, and then the readout unit accumulates sequentially from the pixels in each row in the pixel array by the accumulation operation. The imaging apparatus according to claim 1, wherein a read signal is read out. The first focus detection pixel group and the second focus detection pixel group are arranged at positions shifted from each other in the row direction in the pixel array,
The third focus detection pixel group and the fourth focus detection pixel group are arranged at positions shifted from each other in the column direction in the pixel array,
The first focus detection unit compares the image obtained from the signal of the first focus detection pixel group with the image obtained from the signal of the second focus detection pixel group, thereby Detecting the focus state of the taking lens in the field of view;
The second focus detection unit compares the image obtained from the signal of the third focus detection pixel group with the image obtained from the signal of the fourth focus detection pixel group, thereby obtaining a column direction The imaging apparatus according to claim 1, wherein a focus state of the photographing lens in a field of view is detected. Each pixel in the first focus detection pixel group includes a first photoelectric conversion unit,
Each pixel in the second focus detection pixel group includes a second photoelectric conversion unit,
Each pixel in the third focus detection pixel group includes a third photoelectric conversion unit,
Each pixel in the fourth focus detection pixel group includes a fourth photoelectric conversion unit,
The center of the light receiving region of the first photoelectric conversion unit is shifted to the first side in the row direction with respect to the center of the pixel,
The center of the light receiving region of the second photoelectric conversion unit is a second direction opposite to the first side which is the shift direction of the center of the light receiving region of the first photoelectric conversion unit with respect to the center of the pixel. Shifted to the side,
The center of the light receiving region of the third photoelectric conversion unit is shifted to the third side in the column direction with respect to the center of the pixel,
The center of the light receiving region of the fourth photoelectric conversion unit is a fourth direction opposite to the third side which is the shift direction of the center of the light receiving region of the third photoelectric conversion unit with respect to the center of the pixel. The imaging apparatus according to claim 1, wherein the imaging apparatus is shifted to the side. The photographing lens includes a movable optical element,
The imaging apparatus further includes a driving unit that drives the movable optical element,
The motion detection unit detects a motion of an image of the subject formed in the pixel array by detecting that the driving unit is driving the movable optical element. Item 5. The imaging device according to any one of Items 1 to 4. 5. The motion detection unit according to claim 1, wherein the motion detection unit detects a motion of the image of the subject formed in the pixel array by detecting a shake of the imaging device. 6. Imaging device. The motion detection unit compares the image signals of a plurality of frames read from the pixel array by the reading unit in a plurality of frame periods and detects the movement of the subject, thereby forming the pixel array The imaging apparatus according to claim 1, wherein the movement of an image of a subject is detected.   When the movement of the subject image is not detected by the motion detection unit, the focus adjustment unit assigns the same weight to the detection result of the first focus detection unit and the detection result of the second focus detection unit. The imaging apparatus according to claim 1, wherein focus adjustment is performed by using the imaging apparatus.

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