Imaging device, control method thereof, and program

Abstract

To prevent a reduction in ranging accuracy even when tilt photographing is performed by using a solid state image sensor having phase difference detection pixels.SOLUTION: An imaging apparatus has a solid state image sensor that has a plurality of two-dimensionally arranged pixels, wherein at least some pixels of the plurality of pixels are phase difference detection pixels each including a first photoelectric conversion part and a second photoelectric conversion part for performing phase difference AF. The imaging apparatus has a driving mechanism that can change the angle of an imaging surface of the solid state image sensor with respect to a principal surface of an imaging optical system, and a reading unit that reads out signals obtained by the first photoelectric conversion part and second photoelectric conversion part in the order according to the angle.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an imaging device, a control method thereof, and a program.

Background Art

[0002] In the case of a camera having a lens with a telephoto and bright F-number, generally the depth of field is shallow. Therefore, when shooting with AF function from an oblique direction (non-orthogonal direction) with respect to the subject plane using a camera having such a lens, an in-focus image is obtained only near the center, and an out-of-focus image is obtained in the area outside the vicinity of the center. In the same situation, when using a technique called so-called tilt photography in which the optical axis of the lens is tilted with respect to the solid-state imaging device, the in-focus range can be widened.

[0003] In Patent Document 1, in order to achieve focusing at high speed during tilt photography, an imaging device using a solid-state imaging device having phase difference detection pixels and using a so-called imaging plane phase difference AF technique has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When using the imaging device disclosed in Patent Document 1 and performing focusing during tilt photography by imaging plane phase difference AF, depending on the tilt angle, a sensitivity difference occurs between a plurality of photoelectric conversion units. As a result, the ranging accuracy in the phase difference detection pixels decreases, the accuracy of focused shooting decreases, and the focusing becomes slower.

[0006] The present invention aims to provide a technique for suppressing a decrease in distance measurement accuracy in an imaging apparatus that performs aoli imaging using a solid-state imaging device having phase difference detection pixels.

Means for Solving the Problem

[0007] To solve this problem, for example, the imaging apparatus of the present invention has the following configuration. That is, An imaging apparatus having a solid-state imaging device having a plurality of pixels arranged in a two-dimensional array, wherein at least some of the plurality of pixels are phase difference detection pixels including a first photoelectric conversion unit and a second photoelectric conversion unit for performing phase difference AF, a drive mechanism capable of changing the angle of the imaging surface of the solid-state imaging device with respect to the principal plane of the imaging optical system, and a reading means for reading signals obtained by the first photoelectric conversion unit and the second photoelectric conversion unit in an order corresponding to the angle.

Effects of the Invention

[0008] According to the present invention, even when performing aoli imaging using a solid-state imaging device having phase difference detection pixels, a decrease in distance measurement accuracy can be suppressed.

Brief Description of the Drawings

[0009]

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[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0011] [First Embodiment] The configuration of the imaging device according to the first embodiment is shown in FIG. 1. As shown in FIG. 1, the imaging device 100 includes an imaging optical system 101, a focus control unit 102, a solid-state imaging device 103, an aoli control unit 104, a main control unit 105, a signal processing unit 106, an operation unit 160, and a readout unit 161. Note that the imaging device 100 also includes an operation unit for a user to input various instructions, a recording unit for recording an imaging image on a storage medium, a display unit for displaying an imaging image, etc., but these are not the main points of the present invention and are thus omitted.

[0012] The main control unit 105 is composed of a CPU, a ROM that stores programs executed by the CPU, and a RAM used by the CPU as a work area. Then, the main control unit 105 inputs instructions from the user via the operation unit 160, and controls the focus control unit 102, the solid-state imaging device 103, the tilt control unit 104, and the signal processing unit 106 to control the entire device.

[0013] <Focus Control> The imaging optical system 101 is composed of a plurality of lenses. The focus control unit 102 drives a drive mechanism such as a stepping motor (not shown) under the control of the control unit 105, and moves the focus lens in the imaging optical system 101 along the Z axis indicated by the arrow 150. Thereby, the focus control unit 102 can adjust the focus position of the imaging optical system 101.

[0014] <Tilt Control> The solid-state imaging device 103 is pivotally supported so as to be rotatable within the X-Z plane (arrow 151 in the figure) in order to be able to change the tilt angle with respect to the optical axis direction. The tilt control unit 104 drives a drive mechanism such as a stepping motor (not shown) under the control of the control unit 105, and can change the angle of the solid-state imaging device 103 with respect to the main plane of the imaging optical system 101 (the angle of the imaging surface, hereinafter referred to as the tilt angle). This tilt angle is set by the user operating the operation unit 160.

[0015] <Tilt Control Mechanism of Solid-State Imaging Device> The relationship among the subject plane, the lens, and the imaging surface of the solid-state imaging device in tilt photography will be described with reference to FIG. 2. The reference numeral 103a in the figure indicates the imaging surface of the solid-state imaging device 103. Further, the reference numeral 108 indicates the main plane of the imaging optical system 101 (the plane indicated by that lens when the imaging optical system 101 is regarded as a single lens). The reference numeral 107 indicates the focal plane that is in focus in the tilt photography of the subject 109.

[0016] In panning shooting, according to the principle of shine-proof, the imaging surface 103a, the principal plane 108 of the imaging optical system 101, and the subject plane 107 intersect at a point 110 extending in one Y-axis direction. Therefore, the subject plane 107 is inclined with respect to the principal plane 108 of the imaging optical system 101. That is, in panning shooting, by matching the focus plane 107 with the subject 109 inclined with respect to the principal plane 108 of the imaging optical system 101, imaging with a wide range of focus on the subject 109 becomes possible. The angle θ formed between the imaging surface 103a of the solid-state imaging device 103 and the principal plane 108 of the imaging optical system 101 is called the panning angle.

[0017] <Solid-state imaging device> FIG. 3 shows the structure of the solid-state imaging device 103 in the embodiment. In the solid-state imaging device 103, a plurality of pixels are two-dimensionally arranged, and at least a part of the pixel groups among the plurality of pixels are phase difference detection pixels 111. AF using such phase difference detection pixels is generally called image plane phase difference AF. FIG. 3 shows an example in which the solid-state imaging device 103 has pixels two-dimensionally arranged in 12×4, and all the pixels are phase difference detection pixels 111. Note that the number of pixels shown is for easy understanding and is not particularly limited.

[0018] <Phase difference detection pixel> FIG. 4 is a diagram for explaining the structure of one phase difference detection pixel 111. The phase difference detection pixel 111 includes a first photoelectric conversion unit 112 located on the left side (-X direction), a second photoelectric conversion unit 113 located on the right side (+X direction), and a microlens 114. Although not shown, it also includes wiring for driving the pixel circuit. In addition, it may include a color filter for detecting color signals.

[0019] The microlens 114 is arranged such that the exit pupil 120 of the imaging optical system 101 and the first photoelectric conversion unit 112 and the second photoelectric conversion unit 113 are in a conjugate positional relationship. As a result, a light beam that has mainly passed through the right half of the imaging optical system 101 is guided to the first photoelectric conversion unit 112, and a light beam that has mainly passed through the left half of the imaging optical system 101 is guided to the second photoelectric conversion unit 113. Therefore, by detecting the amount of image shift between the first image generated from the pixel signals acquired by the first photoelectric conversion unit 112 of each of the plurality of phase difference detection pixels 111 and the second image generated from the pixel signals acquired by the second photoelectric conversion unit 113, the amount of deviation from the in-focus position of the subject can be obtained.

[0020] <Sensitivity difference between photoelectric conversion units> Figs. 5(a) to (c) and Figs. 6(a) to (c) are diagrams schematically showing the light beams incident on the first photoelectric conversion unit 112 and the light beams incident on the second photoelectric conversion unit 113 when the aoli angle is changed. Figs. 5(a) to (c) show a case where the aoli angle is small, particularly a case where the aoli angle is 0 degrees. Figs. 6(a) to (c) show a case where the aoli angle is large. Also, Figs. 5(a) and 6(a) show the phase difference detection pixels 111 located in the central region of the solid-state imaging device 103. Similarly, Figs. 5(b) and 6(b) show the phase difference detection pixels 111 located in the peripheral region in the -X direction, and Figs. 5(c) and 6(c) show the phase difference detection pixels 111 located in the peripheral region in the +X direction.

[0021] <When the aoli angle is small> First, the case where the aoli angle is 0 degrees as shown in Figs. 5(a) to (c) will be described. As shown in Fig. 5(a), the light beam 124 incident on the first photoelectric conversion unit 112 and the light beam 125 incident on the second photoelectric conversion unit 113 of the phase difference detection pixel 111 located in the central region of the imaging surface 103a are in a line-symmetrical positional relationship with respect to the center of the exit pupil of the imaging optical system 101. Therefore, the sensitivities of the first photoelectric conversion unit 112 and the second photoelectric conversion unit 113 in the phase difference detection pixel 111 located in the central region of the imaging surface 103a are equal to each other.

[0022] When the exit pupil distance of the imaging optical system 101 is infinite, the sensitivities of the first photoelectric conversion unit 112 and the second photoelectric conversion unit 113 of the phase difference detection pixels in the peripheral region outside the central region of the solid-state imaging device 103 are equal. However, generally, due to requirements for miniaturization of the imaging optical system, etc., the exit pupil distance is often located at a finite distance. Therefore, FIGS. 5(b) and (c) show the case where the exit pupil distance is located at a finite distance.

[0023] As is clear from FIG. 5(b), in the phase difference detection pixel 111 located at a deviated position in the -X direction on the imaging plane 103a, the light beam 134 incident on the first photoelectric conversion unit 112 is more than the light beam 135 incident on the second photoelectric conversion unit 113. That is, in the phase difference detection pixel 111 located in the peripheral region in the -X direction on the imaging plane 103a, the sensitivity of the first photoelectric conversion unit 112 is higher than the sensitivity of the second photoelectric conversion unit 113.

[0024] Similarly, from FIG. 5(c), in the phase difference detection pixel 111 located at a deviated position in the +X direction on the imaging plane 103a, the light beam 145 incident on the second photoelectric conversion unit 113 is more than the light beam 144 incident on the first photoelectric conversion unit 112. That is, in the phase difference detection pixel 111 located in the peripheral region in the +X direction on the imaging plane 103a, the sensitivity of the second photoelectric conversion unit 113 is higher than the sensitivity of the first photoelectric conversion unit 112.

[0025] <When the aoli angle is large> Next, the case where the aoli angle is large will be described. When the aoli angle is large, the exit pupil 120 of the imaging optical system 101 is inclined with respect to the imaging plane 103a. Therefore, as shown in FIG. 6(a), even in the phase difference detection pixel 111 located in the central region of the imaging plane 103a, the sensitivities of the first photoelectric conversion unit 112 and the second photoelectric conversion unit 113 are different. Specifically, the sensitivity of the first photoelectric conversion unit 112 located in the -X direction is higher than the sensitivity of the second photoelectric conversion unit 113 located in the +X direction.

[0026] The phase difference detection pixel 111 shifted in the -X direction of the imaging surface 103a is located in a direction away from the center of the exit pupil with respect to the phase difference detection pixel 111 in the central region. Therefore, as shown in FIG. 6(b), the sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit is further enlarged compared to the central region. That is, the sensitivity of the first photoelectric conversion unit 132 of the phase difference detection pixel 111 in the region shifted in the -X direction of the imaging surface 103a is higher than the sensitivity of the second photoelectric conversion unit 133.

[0027] On the other hand, as shown in FIG. 6(c), the phase difference detection pixel 111 shifted in the +X direction of the imaging surface 103a is located in a direction approaching the center of the exit pupil with respect to the central region. Therefore, the sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit is determined by the exit pupil distance and the aoli angle of the imaging optical system. When the exit pupil distance is sufficiently long and the aoli angle is large, as shown in FIG. 6(c), the sensitivity of the first photoelectric conversion unit 112 of the phase difference detection pixel 111 shifted in the +X direction of the imaging surface 103a is higher than the sensitivity of the second photoelectric conversion unit 113. On the other hand, when the exit pupil distance is short and the aoli angle is not large, the sensitivity of the second photoelectric conversion unit 143 is higher than that of the first photoelectric conversion unit 142.

[0028] <Summary> Summarizing the above description, when aoli photography is performed with an imaging device using the solid-state imaging device 103 having the phase difference detection pixel 111, depending on the magnitude of the aoli angle and the position of the imaging surface 103a, the magnitude relationship between the sensitivities of the first photoelectric conversion unit and the second photoelectric conversion unit of the phase difference detection pixel is different. The table in FIG. 7 summarizes the above relationship.

[0029] In FIG. 7, "First > Second" indicates that the sensitivity of the first photoelectric conversion unit 112 is higher than that of the second photoelectric conversion unit 113. Similarly, "First < Second" means that the sensitivity of the second photoelectric conversion unit 113 is higher than that of the first photoelectric conversion unit 112, and "First = Second" means that the sensitivities of the first photoelectric conversion unit 112 and the second photoelectric conversion unit 113 are equal.

[0030] In the imaging device of the present embodiment, in order to suppress a decrease in distance measurement accuracy caused by a sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit, the reading order of the first photoelectric conversion unit and the second photoelectric conversion unit is changed according to the aoli angle. Hereinafter, the reading of the pixel signal and the effects of the present embodiment will be described.

[0031] <Pixel circuit> FIG. 8 is a diagram showing an equivalent circuit diagram of the phase difference detection pixel 111 in the solid-state imaging device 103. The phase difference detection pixel includes a first photoelectric conversion unit (PD_A), a second photoelectric conversion unit (PD_B), a first transfer transistor (TX_A), and a second transfer transistor (TX_B), and PD_A and PD_B share a floating diffusion (FD). Further, the phase difference detection pixel has a reset transistor (RST), a selection transistor (SEL), and a source follower unit (SF) that converts the charge accumulated in the FD into a voltage signal and reads it out, with respect to the shared FD. The timings of TX_A, TX_B, RST, and SEL are controlled from the peripheral circuit in the solid-state imaging device 103 via a horizontal control line extending in the row direction. In addition, SF is connected to the vertical signal line, and the pixel signals acquired by each photoelectric conversion unit are sent to the signal processing unit 106 by the reading unit 161. This reading unit 161 reads the signals of the photoelectric conversion units in order according to the control by the main control unit 160.

[0032] <Timing chart and addition reading> FIG. 9 is a diagram for explaining the timing chart when the reading unit 161 reads the pixel signal from the phase difference detection pixel 111. First, at time t1, RST, TX_A, and TX_B are turned on to reset the potentials of PD_A, PD_B, and FD. At time t2, RST, TX_A, and TX_B are turned off, and the charge accumulation in PD_A and PD_B is started. After the start of charge accumulation, after a predetermined accumulation time has elapsed, the pixel signals of PD_A and PD_B are read out.

[0033] In the imaging device of the present embodiment, the pixel signal S1 acquired by one photoelectric conversion unit and the sum S of the pixel signals acquired by both photoelectric conversion units 1+2Then, read out S 1+2 A so-called additive readout is used, in which the pixel signal S2 of the other photoelectric conversion unit is obtained by subtracting S1 from S1. The following describes an example in which the signal of PD_A is read out first, but if the signal of PD_B is read out first, A and B can be swapped. As a peripheral circuit for swapping A and B, two types of vertical scanning circuits that swap the timing of TX_A and TX_B are prepared, and the vertical scanning circuit to be connected is changed depending on the column.

[0034] First, RST is turned ON at time t3, and then SEL is turned ON at time t4 to read out the noise level. Next, TX_A is turned ON at time t5, and SEL is turned ON at time t6 to obtain the pixel signal of the photoelectric conversion unit PD_A. Finally, TX_B is turned ON at time t7, and SEL is turned ON at time t8 to obtain the sum of the image signals of the photoelectric conversion units PD_A and PD_B.

[0035] <Signal readout sequence and ranging accuracy> Here, we will explain the noise that appears in the pixel signal read out from the solid-state imaging element 103. The dominant noise components are optical shot noise Ns and readout circuit noise Nr. Optical shot noise occurs during photoelectric conversion, and its magnitude depends on the signal magnitude and is the square root of the signal amount. On the other hand, readout circuit noise Nr occurs when the pixel signal is read out from FD via SF, and is a constant value independent of the signal magnitude. Since optical shot noise and readout circuit noise are independent phenomena, the sum of the noises is the square root of the sum of squares.

[0036] Therefore, the signal-to-noise ratio SN1 of the pixel signal S1 that is read out first is expressed by the formula (1), and the sum signal S 1+2 S / N ratio 1+2 is expressed as follows (2).

[0037]

number

[0038]

number

[0039] On the one hand, the signal-to-noise ratio SN2 of the pixel signal S2 obtained by subtracting the addition signal S 1+2 from the pixel signal S1 is expressed by Equation (3) because noise due to the read signal is added.

[0040] [Number]

[0041] As can be seen by comparing Equation 1 and Equation 3, if the magnitudes of S1 and S2 are the same, the signal-to-noise ratio of the pixel signal of the photoelectric conversion unit read later is lower than that of the photoelectric conversion unit that read the pixel signal earlier.

[0042] [Read the one with lower sensitivity first] As described above, in order to suppress a decrease in the ranging accuracy caused by the sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit, the imaging device according to the present embodiment changes the reading order of the first photoelectric conversion unit and the second photoelectric conversion unit according to the aoli angle. Specifically, the main control unit 105 controls the reading unit 161 to read the pixel signal from the photoelectric conversion unit with lower sensitivity first and the pixel signal from the photoelectric conversion unit with higher sensitivity later. Hereinafter, the reason why the decrease in the ranging accuracy can be suppressed will be described.

[0043] First, consider the case where the pixel signal from the photoelectric conversion unit with higher sensitivity is read first and the pixel signal from the photoelectric conversion unit with lower sensitivity is read later. As described above, when the amount of light incident on the photoelectric conversion unit is the same, the signal-to-noise ratio of the pixel signal of the photoelectric conversion unit read later is lower than that of the photoelectric conversion unit that read the pixel signal earlier.

[0044] That is, when the pixel signal from the highly sensitive photoelectric conversion unit is read first and the pixel signal from the less sensitive photoelectric conversion unit is read later, the signal magnitude of the latter is lower and the noise is also worse. Since the detection accuracy of the image shift amount is mainly determined by the pixel signal on the side with a lower assumed signal-to-noise ratio, when the pixel signal from the less sensitive photoelectric conversion unit is read later, the ranging accuracy will decrease.

[0045] On the other hand, when the pixel signal from the less sensitive photoelectric conversion unit is read first and the pixel signal from the highly sensitive photoelectric conversion unit is read later, the signal magnitude of the former is lower, but the noise characteristics of the former are better. Therefore, it is possible to suppress a decrease in ranging accuracy by reading the pixel signal from the less sensitive photoelectric conversion unit first and the pixel signal from the highly sensitive photoelectric conversion unit later, rather than reading the pixel signal from the highly sensitive photoelectric conversion unit first and the pixel signal from the less sensitive photoelectric conversion unit later.

[0046] <Changed according to the magnitude of the pixel signal> Since the difference between Equation 2 and Equation 3 is the read noise, when the photon shot noise is sufficiently larger than the read noise, the pixel signal of either photoelectric conversion unit may be read first. That is, according to the magnitude of the pixel signal, it is also possible to change whether to specify the read order of the pixel signals from the photoelectric conversion units.

[0047] <Read order when the shear angle is small> As shown in FIG. 7, when the shear angle is small (when the shear angle is equal to or less than a preset threshold value), it is preferable to change the read order of the first photoelectric conversion unit and the second photoelectric conversion unit according to the position of the phase difference detection pixels on the image plane. Specifically, with respect to a line perpendicular to the direction (pupil division direction) connecting the center of the first photoelectric conversion unit and the center of the second photoelectric conversion unit passing through the center of the solid-state imaging device 103, in the -X direction region, the second photoelectric conversion unit is read first, and in the +X direction region, the first photoelectric conversion unit is read first. That is, it is preferable that the read order of the first photoelectric conversion unit and the second photoelectric conversion unit is reversed with a line passing through the center of the solid-state imaging device and perpendicular to the pupil division direction as a boundary.

[0048] As can be seen from FIG. 5(a), in the central region of the solid-state imaging device, the difference in sensitivity between the first photoelectric conversion unit and the second photoelectric conversion unit is small. Therefore, in the central region of the solid-state imaging device, either the first photoelectric conversion unit or the second photoelectric conversion unit may be read out first. That is, in a region that is separated from a line passing through the center of the solid-state imaging device and perpendicular to the pupil division direction by a distance greater than or equal to a first threshold value, it is sufficient that the readout order of the first photoelectric conversion unit and the second photoelectric conversion unit is reversed.

[0049] <Readout order when the yaw angle is large> As shown in FIG. 7, when the yaw angle is large (when the yaw angle is greater than a threshold value), since the sensitivity of the first photoelectric conversion unit is higher regardless of the phase difference detection pixels on the image plane, it is preferable to read out the pixel signals from the second photoelectric conversion unit first. That is, when the yaw angle is large, it is better to read out the signals from the photoelectric conversion unit located on the side where the distance from the image plane to the subject plane is relatively close (+X direction) first.

[0050] <The boundary line moves according to the yaw angle> As the yaw angle increases, the inclination of the exit pupil increases. Therefore, the boundary line at which the readout order of the first photoelectric conversion unit and the second photoelectric conversion unit is reversed is in a direction perpendicular to the pupil division direction, and as the yaw angle increases, the boundary line shifts toward the side where the distance from the image plane to the subject plane is relatively close.

[0051] <Specify step by step> It is preferable that the boundary line at which the readout order of the first photoelectric conversion unit and the second photoelectric conversion unit is reversed moves continuously according to the yaw angle, because the ratio of the pixels for which the pixel signals from the photoelectric conversion unit with lower sensitivity are read out first increases, and the ranging accuracy improves. However, it may change step by step. For example, the readout order may be changed depending on whether the yaw angle is greater than or equal to a second threshold value or less than the second threshold value.

[0052] <Specify the pre-read pixels only when the yaw angle is large> Also, as can be seen by comparing FIGS. 5 and 6, in the peripheral region on the side where the shear angle is large and the distance from the image plane to the subject plane is relatively far (-X direction), particularly the sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit becomes large. Therefore, only when the shear angle is larger than the second threshold value, the reading order of the photoelectric conversion units may be specified. Furthermore, only for the phase difference detection pixels in the peripheral region on the side where the distance from the image plane to the subject plane is relatively far (-X direction), the reading order of the photoelectric conversion units may be specified.

[0053] Note that the above shows the case where the phase difference detection pixel has two photoelectric conversion units, but it may have three or more photoelectric conversion units. In that case, it is preferable to first read out the pixel signal of the photoelectric conversion unit with the lowest sensitivity, and then read out the pixel signals in order from the lowest sensitivity.

[0054] [Second Embodiment] The second embodiment will be described. This second embodiment is in the structure of the solid-state imaging device in the first embodiment. The solid-state imaging device in this second embodiment is denoted by reference numeral 203, and its imaging surface is expressed as 203a. Since the other configurations are the same as those in the first embodiment, they will be described with the same reference numerals.

[0055] FIGS. 10(a) to (c) are structural diagrams of the phase difference detection pixel 211 of the solid-state imaging device 203 according to the second embodiment. One phase difference detection pixel 211 in this second embodiment includes a first photoelectric conversion unit 212 located on the left side (-X direction) of the imaging surface 203a, a second photoelectric conversion unit 213 located on the right side (+X direction), and a microlens 214, similar to the phase difference detection pixel 111 in the first embodiment. And the microlens 214 of the phase difference detection pixel 211 in this second embodiment has a structure that is decentered according to the position from the center of the imaging surface 103.

[0056] Specifically, as shown in FIG. 10(a), the microlens 214 of the phase difference detection pixel 211 at a position shifted in the -X direction of the imaging surface 203a is eccentric in the +X direction with respect to the center of the pixel. Further, as shown in FIG. 10(c), the microlens 214 of the phase difference detection pixel 211 at a position shifted in the +X direction of the imaging surface 203a is eccentric in the -X direction with respect to the center of the pixel. And, as shown in FIG. 10(b), the microlens 214 of the phase difference detection pixel 231 located in the central region of the imaging surface 203a is not eccentric with respect to the center of the pixel. By adopting such a configuration, when the exit pupil distance of the imaging optical system is short, it is possible to reduce the sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit in the phase difference detection pixels in the peripheral region.

[0057] FIGS. 11(a) to (c) and FIGS. 12(a) to (c) are diagrams schematically showing the light beam incident on the first photoelectric conversion unit 212 and the light beam incident on the second photoelectric conversion unit 213 when the roll angle is changed. FIGS. 12(a) to (c) show the case where the roll angle is small, particularly the case where the roll angle is 0 degrees, and FIGS. 13(a) to (c) show the case where the roll angle is large. Further, FIGS. 11(a) and 12(a) both show the case where the phase difference detection pixel 211 is located in the central region of the imaging surface 103a. Similarly, FIGS. 11(b) and 12(b) both show the case where the phase difference detection pixel 211 is at a position shifted in the -X direction of the imaging surface 103a. And, FIGS. 11(c) and 12(c) both show the case where the phase difference detection pixel 211 is at a position shifted in the +X direction of the imaging surface 103a.

[0058] In the imaging device according to the second embodiment, since the microlenses of the phase difference detection pixels are decentered in accordance with the exit pupil 220 of the imaging optical system 101, when the aoli angle is 0 degrees as shown in FIGS. 11(a) to 11(c), the sensitivities of the first photoelectric conversion unit and the second photoelectric conversion unit can be made equal in both the central region and the peripheral region. However, when the aoli angle is large, the center of the exit pupil of the imaging optical system is shifted from the center of the solid-state imaging device to the side where the distance from the image plane to the subject plane is relatively short (+X direction). Therefore, when the aoli angle is large as shown in FIGS. 12(a) to 12(c), the first photoelectric conversion unit has a higher sensitivity than the second photoelectric conversion unit.

[0059] Thus, even when the structure of the phase difference detection pixels is optimized in accordance with the exit pupil of the imaging optical system, when aoli photography is performed, depending on the aoli angle, the magnitude relationship of the sensitivities of the first photoelectric conversion unit and the second photoelectric conversion unit of the phase difference detection pixels is different. Therefore, also in the imaging device of the second embodiment, in order to suppress a decrease in the distance measurement accuracy caused by the sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit, the reading order of the first photoelectric conversion unit and the second photoelectric conversion unit is changed according to the aoli angle. Specifically, when the aoli angle is larger than a preset threshold value, by reading out the pixel signals from the second photoelectric conversion unit first, a decrease in the distance measurement accuracy is suppressed.

[0060] <Summary of the Second Embodiment> As described above, in the imaging device of the second embodiment, the decentration amount of the microlenses of the phase difference detection pixels is arranged so that the sensitivities of the first photoelectric conversion unit and the second photoelectric conversion unit are equal for the case of the first aoli angle. And in the case of the second aoli angle or more, which is larger than the first aoli angle, the signal from the photoelectric conversion unit located on the side where the distance from the image plane to the subject plane is relatively short (+X direction) is read out first.

[0061] [Third Embodiment] A third embodiment will be described. This third embodiment has the structure of the solid-state imaging device in the first embodiment. The solid-state imaging device in this third embodiment is denoted by reference numeral 303, and its imaging surface is expressed as 303a. Since the other configurations are the same as those in the first embodiment, they will be described with the same reference numerals.

[0062] In this third embodiment, an example is given in which the microlenses of the phase difference detection pixels 311 of the solid-state imaging device 303 are optimized for a large aoli angle.

[0063] Specifically, the microlenses of the phase difference detection pixels 311 in all regions of the solid-state imaging device 303 in this third embodiment are eccentric in the +X direction with respect to the center of each pixel. And the eccentricity of the microlens changes continuously or stepwise so that it is the largest in the peripheral region in the -X direction and the smallest in the peripheral region in the +X direction. By adopting such a configuration, it is possible to reduce the sensitivity difference between the first photoelectric conversion unit and the second photoelectric conversion unit when the aoli angle is large.

[0064] Note that one phase detection pixel in this third embodiment is expressed as the first photoelectric conversion unit on the -X side of the imaging surface 303a and the +X side as the second photoelectric conversion unit, similar to the first and second embodiments.

[0065] Figs. 13(a) to (c) and Figs. 14(a) to (c) schematically show the light beams incident on the first photoelectric conversion unit 312 and the light beams incident on the second photoelectric conversion unit 313 when the aoli angle is changed.

[0066] Figs. 13(a) to 13(c) show the case where the shear angle is small, particularly when the shear angle is 0 degrees, and Figs. 14(a) to 14(c) show the case where the shear angle is large. Also, Figs. 13(a) and 14(a) both show the incident light beams of the first and second photoelectric conversion parts of the phase difference detection pixel 311 located in the central region of the imaging surface 303a. Similarly, Figs. 13(b) and 14(b) show the incident light beams of the first and second photoelectric conversion parts of the phase difference detection pixel 331 at a position shifted in the -X direction of the imaging surface 303a, and Figs. 13(c) and 14(c) show the incident light beams of the first and second photoelectric conversion parts of the phase difference detection pixel 331 at a position shifted in the +X direction of the imaging surface 303a.

[0067] In the imaging device of the third embodiment, the microlens of the phase difference detection pixel 311 is decentered in accordance with the exit pupil 320 of the imaging optical system when the shear angle is large. Therefore, when the shear angle is large as shown in Figs. 14(a) to 14(c), the sensitivities of the first photoelectric conversion part and the second photoelectric conversion part are equal both in the central region and in the peripheral region. However, when the shear angle is small as shown in Figs. 13(a) to 13(c), the second photoelectric conversion part has a higher sensitivity than the first photoelectric conversion part.

[0068] Thus, even when the structure of the phase difference detection pixel is optimized according to the large shear angle, the magnitude relationship of the sensitivities of the first photoelectric conversion part and the second photoelectric conversion part of the phase difference detection pixel differs depending on the shear angle. Therefore, also in the imaging device of the third embodiment, in order to suppress the decrease in the distance measurement accuracy caused by the sensitivity difference between the first photoelectric conversion part and the second photoelectric conversion part, the reading order of the first photoelectric conversion part and the second photoelectric conversion part is changed according to the shear angle. Specifically, when the shear angle is small, the pixel signal from the first photoelectric conversion part can be read first to suppress the decrease in the distance measurement accuracy.

[0069] <Summary of the configuration of the third embodiment> In the imaging device according to the third embodiment, for the case of the third aoli angle, the decentration amount of the microlens of the phase difference detection pixel is arranged so that the sensitivities of the first photoelectric conversion unit and the second photoelectric conversion unit are equal. Then, in the case of an aoli angle less than a fourth aoli angle smaller than the third aoli angle, the signal from the photoelectric conversion unit located on the relatively far side (-X direction) from the image plane to the subject plane is read out first.

[0070] [Fourth Embodiment] As described in the second and third embodiments, the exit pupil position of the imaging optical system 101 changes depending on the aoli angle. Therefore, it is preferable to optimize the decentration amount of the microlens for the intermediate aoli angle. The imaging device shown in the fourth embodiment is an example in which the decentration amount of the microlens is optimized for an angle exactly in the middle between the preset minimum aoli angle and the maximum aoli angle when performing aoli shooting.

[0071] Also in the case of the imaging device according to the fourth embodiment, since the magnitude relationship of the sensitivity differs depending on the aoli angle and the position of the phase difference detection pixel on the image plane, it is preferable to change the reading order of the photoelectric conversion units depending on these. Specifically, the smaller the aoli angle, the larger the ratio of the phase difference detection pixels for which the first photoelectric conversion unit is read out first, and the larger the aoli angle, the larger the ratio of the phase difference detection pixels for which the signal is read out from the second photoelectric conversion unit first. This is preferable because it can suppress a decrease in the ranging accuracy caused by the sensitivity difference of the photoelectric conversion units.

[0072] [Fifth Embodiment] A fifth embodiment will be described. Here, a monitoring system using the imaging device shown in the first to fourth embodiments will be described. FIG. 15 is a configuration diagram of a monitoring system 500 using an imaging device 503 according to any of the first to fourth embodiments. The imaging device 503 and the client device 501 are connected via a network 502 so as to be able to communicate with each other. The client device 501 transmits various commands for controlling the imaging device 503. In response to this, the imaging device 503 transmits a response to the command and the captured image data to the client device 501. Whether to drive the imaging device 503 in the depth-of-field priority mode can be selected by the user via the client device 501.

[0073] The client device 501 is an external device such as a PC, and the network 502 is composed of a wired LAN, a wireless LAN, or the like. Also, a configuration may be adopted in which power is supplied to the imaging device 503 via the network 502.

[0074] (Other embodiments) The present invention can also be realized by supplying a program for realizing one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and causing one or more processors in a computer of the system or device to read and execute the program. It can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

[0075] The disclosure of this specification includes the following imaging device, method, and program. (Item 1) An imaging device having a solid-state imaging device, wherein the solid-state imaging device has phase difference detection pixels having a plurality of pixels arranged in a two-dimensional array, and at least some of the plurality of pixels include a first photoelectric conversion unit and a second photoelectric conversion unit for performing phase difference AF, a drive mechanism capable of changing an angle of an imaging surface of the solid-state imaging device with respect to a principal plane of an imaging optical system, a reading means for reading signals obtained by the first photoelectric conversion unit and the second photoelectric conversion unit in an order corresponding to the angle An imaging device characterized by having (Item 2) The reading means first reads a signal from either the first photoelectric conversion unit or the second photoelectric conversion unit, and then reads the added signal of the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to item 1, characterized by the above. (Item 3) The reading means first reads the photoelectric conversion unit with relatively low sensitivity among the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to item 2, characterized by the above. (Item 4) The reading means changes the reading order of the first photoelectric conversion unit and the second photoelectric conversion unit according to the size of the pixel signal. The imaging device according to any one of items 1 to 3, characterized by the above. (Item 5) When the reading means passes through the center of the solid-state imaging device and sets the regions on both sides that are separated from the center by a distance of at least a first threshold value in a direction perpendicular to the pupil division direction as a first region and a second region, the reading order of the first and second photoelectric conversion units in the first region is reversed in the second region for the reading order of the first and second photoelectric conversion units. The imaging device according to any one of items 1 to 4, characterized by the above. (Item 6) For two regions bounded by a line passing through the center of the solid-state imaging device and perpendicular to the pupil division direction, the reading order of the first and second photoelectric conversion units in one region is reversed from the reading order of the first and second photoelectric conversion units in the other region. The imaging device according to item 5, characterized by the above. (Item 7) The boundary line where the reading order of the first photoelectric conversion unit and the second photoelectric conversion unit is reversed is in a direction perpendicular to the pupil division direction, and the position of the boundary line shifts to the side where the distance from the imaging surface to the subject surface is relatively close as the angle increases. The imaging device according to item 6, characterized by the above. (Item 8) The reading means changes the reading order of the first and second photoelectric conversion units according to whether or not the angle is greater than or equal to a second threshold value. The imaging device according to any one of Items 1 to 7, characterized by the above. (Item 9) It has setting means for setting, in the reading means, which of the first and second photoelectric conversion units is to be read first, only when the angle is greater than or equal to a second threshold value. The imaging device according to any one of Items 1 to 7, characterized by the above. (Item 10) The setting means sets which of the first and second photoelectric conversion units is to be read first only for the phase difference detection pixels in the peripheral region on the side where the distance from the imaging surface to the subject surface is relatively far. The imaging device according to Item 9, characterized by the above. (Item 11) The phase difference detection pixels have microlenses, and the centers of the microlenses of each of the phase difference detection pixels are eccentric according to the position of the solid-state imaging device. The imaging device according to any one of Items 1 to 10, characterized by the above. (Item 12) The reading means when the angle is less than or equal to a preset first angle, reads without changing the reading order of the first and second photoelectric conversion units, and when the angle exceeds the first angle, reads the signal from the photoelectric conversion unit located on the side where the distance from the imaging surface to the subject surface is relatively close first. The imaging device according to Item 11, characterized by the above. (Item 13) The microlenses are eccentrically arranged so that the sensitivities of the first and second photoelectric conversion units are equal at a preset second angle of the angle, and when the angle is smaller than the second angle, the signal from the photoelectric conversion unit on the side located on the side where the distance from the imaging surface to the subject is relatively far is read first. The imaging device according to Item 11, characterized by the above. (Item 14) The micro lens is eccentrically arranged so that the sensitivities of the first photoelectric conversion unit and the second photoelectric conversion unit are equal at the central angle between the maximum angle and the minimum angle that can be changed by the drive mechanism. When the readout means is smaller than the central angle, the ratio of the phase difference detection pixels read out first from the first photoelectric conversion unit is large, and the larger the angle is than the central angle, the larger the ratio of the phase difference detection pixels read out first from the second photoelectric conversion unit is. The imaging device according to item 11, characterized in that. (Item 15) A control method for an imaging device having a solid-state imaging device having a plurality of pixels arranged in a two-dimensional array, at least some of the plurality of pixels being phase difference detection pixels including a first photoelectric conversion unit and a second photoelectric conversion unit for performing phase difference AF, and a drive mechanism capable of changing the angle of the imaging surface of the solid-state imaging device with respect to the principal plane of the imaging optical system, A readout step of reading out signals obtained by the first photoelectric conversion unit and the second photoelectric conversion unit in an order corresponding to the angle A control method for an imaging device, characterized by comprising. (Item 16) A program for causing a computer to read and execute, so that the computer functions as each means according to any one of items 1 to 14.

[0076] The invention is not limited to the above embodiments, and various changes and modifications are possible without departing from the spirit and scope of the invention. Therefore, claims are attached to disclose the scope of the invention.

Explanation of reference numerals

[0077] 100, 503... Imaging device, 101... Imaging optical system, 102... Focus control unit, 103... Solid-state imaging device, 104... Vibration control unit, 105... Main control unit, 106... Signal processing unit, 501... Client device, 502... Network

Claims

1. An imaging device having a solid-state imaging device, which has a plurality of pixels arranged in a two-dimensional array, and at least some of the plurality of pixels are phase difference detection pixels including a first photoelectric conversion unit and a second photoelectric conversion unit for performing phase difference AF, a drive mechanism capable of changing the angle of the imaging surface of the solid-state imaging device with respect to the principal plane of the imaging optical system, and a reading means for reading signals obtained by the first photoelectric conversion unit and the second photoelectric conversion unit in an order corresponding to the angle. The imaging device is characterized by comprising the above.

2. The reading means first reads a signal from either the first photoelectric conversion unit or the second photoelectric conversion unit, and then reads a signal obtained by adding the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to claim 1, characterized by the above.

3. The reading means first reads a photoelectric conversion unit having relatively low sensitivity among the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to claim 2, characterized by the above.

4. The reading means changes the reading order of the first photoelectric conversion unit and the second photoelectric conversion unit according to the magnitude of the pixel signal. The imaging device according to claim 1, characterized by the above.

5. When the reading means uses the center of the solid-state imaging device as a reference, and when both regions separated from the center by a distance equal to or greater than a first threshold value in a direction perpendicular to the pupil division direction are defined as a first region and a second region, the reading order of the first and second photoelectric conversion units in the first region is reversed in the second region. The imaging device according to claim 1, characterized by the above.

6. For two regions defined by a line passing through the center of the solid-state imaging device and perpendicular to the pupil division direction, the reading order of the first and second photoelectric conversion units in one region is reversed from that in the other region. The imaging device according to claim 5, characterized by the above.

7. The boundary line where the reading order of the first photoelectric conversion unit and the second photoelectric conversion unit is reversed is in a direction perpendicular to the pupil division direction, and the position of the boundary line shifts to the side where the distance from the imaging surface to the subject surface is relatively close as the angle increases. The imaging device according to claim 6, characterized by the above.

8. The reading means changes the reading order of the first and second photoelectric conversion units according to whether the angle is equal to or greater than a second threshold value. The imaging device according to claim 1, characterized by the above.

9. Only when the angle is equal to or greater than a second threshold value, there is a setting means for setting, in the reading means, which of the first and second photoelectric conversion units is to be read first. The imaging device according to claim 1, characterized in that.

10. The setting means sets which of the first and second photoelectric conversion units is to be read first only for the phase difference detection pixels in the peripheral region on the side where the distance from the imaging surface to the subject surface is relatively far. The imaging device according to claim 9, characterized in that.

11. The phase difference detection pixels have microlenses, The centers of the microlenses of each of the phase difference detection pixels are eccentric according to the position of the solid-state imaging device. The imaging device according to claim 1, characterized in that.

12. The reading means, When the angle is equal to or less than a preset first angle, reads the first and second photoelectric conversion units without changing the reading order, When the angle exceeds the first angle, reads the signal from the photoelectric conversion unit located on the side where the distance from the imaging surface to the subject surface is relatively close first. The imaging device according to claim 11, characterized in that.

13. The microlenses are eccentrically arranged so that the sensitivities of the first and second photoelectric conversion units are equal at a second angle preset for the angle, When the angle is smaller than the second angle, reads the signal from the photoelectric conversion unit on the side where the distance from the imaging surface to the subject is relatively far first. The imaging device according to claim 11, characterized in that.

14. The microlenses are eccentrically arranged so that the sensitivities of the first and second photoelectric conversion units are equal at a central angle between the maximum angle and the minimum angle that can be changed by the drive mechanism, The reading means has a larger ratio of phase difference detection pixels read first from the first photoelectric conversion unit when the angle is smaller than the central angle, and increases the ratio of phase difference detection pixels read first from the second photoelectric conversion unit as the angle is larger than the central angle. The imaging device according to claim 11, characterized in that.

15. A control method for an imaging device having a solid-state imaging device having a plurality of pixels arranged in a two-dimensional array, and at least some of the plurality of pixels being phase difference detection pixels including a first photoelectric conversion unit and a second photoelectric conversion unit for performing phase difference AF, and a drive mechanism capable of changing the angle of the imaging surface of the solid-state imaging device with respect to the principal plane of the imaging optical system. A reading step of reading signals obtained by the first photoelectric conversion unit and the second photoelectric conversion unit in an order corresponding to the angle A control method for an imaging device, characterized by comprising the above. **Claim 16** A program for causing a computer to execute the steps of the method according to claim 15 by causing the computer to read and execute the program.

Images