WO2022239831A1 - Imaging element, focus detection device, and imaging device - Google Patents

Abstract

This imaging element comprises: a first pixel that outputs a signal used for image generation has a first photoelectric conversion unit that generates charge by photoelectrically converting light that has passed through a first micro-lens; and a second pixel that generates a signal used for focus detection and has a second photoelectric conversion unit that generates charge by photoelectrically converting light that has passed through a second micro-lens having a different refractive power than the first micro-lens.

Description

Imaging device, focus detection device and imaging device

The present invention relates to an imaging device, a focus detection device, and an imaging device.
This application claims priority based on Japanese Patent Application No. 2021-082167 filed on May 14, 2021, the content of which is incorporated herein.

An imaging device in which a plurality of microlenses are formed for each unit pixel is known (for example, Patent Document 1). 2. Description of the Related Art Conventionally, there has been a demand for an imaging device that performs focus detection with high accuracy.

JP 2015-167219 A

An imaging device according to a first aspect of the present invention has a first photoelectric conversion unit that photoelectrically converts light that has passed through a first microlens to generate an electric charge, and first pixels that output signals used for image generation. and a second photoelectric conversion unit that photoelectrically converts light passing through a second microlens having a refractive power different from that of the first microlens to generate an electric charge, and a second pixel that generates a signal used for focus detection. And prepare.
An imaging device according to a second aspect of the present invention has a first photoelectric conversion section that photoelectrically converts light that has passed through a plurality of first microlenses to generate electric charges, and a first photoelectric conversion section that outputs a signal used for image generation. and a second pixel that has a second photoelectric conversion unit that photoelectrically converts light that has passed through the second microlens to generate an electric charge and that outputs a signal used for focus detection.

1 is a cross-sectional view for explaining the main configuration of an imaging device according to an embodiment; FIG. It is a figure explaining typically the structure of the image pick-up element in embodiment. 4A and 4B are diagrams schematically illustrating configurations of imaging pixels and focus detection pixels in the first embodiment; FIG. FIG. 4 is a diagram schematically explaining another example of the configuration of imaging pixels and focus detection pixels in the first embodiment; FIG. 4 is a diagram schematically explaining another example of the configuration of imaging pixels and focus detection pixels in the first embodiment; FIG. 10 is a diagram schematically illustrating the configuration of imaging pixels and focus detection pixels in the second embodiment; FIG. 10 is a circuit diagram of focus detection pixels included in the image pickup device according to the second embodiment; 9 is a timing chart for explaining signal readout of focus detection pixels in the second embodiment; 9 is a timing chart illustrating another example of signal readout of focus detection pixels in the second embodiment; FIG. 11 is a diagram schematically illustrating another example of the configuration of imaging pixels and focus detection pixels in the second embodiment; FIG. 10 is a circuit diagram of another example of focus detection pixels included in the image pickup device according to the second embodiment; FIG. 10 is a timing chart for explaining signal readout of another example of the focus detection pixel in the second embodiment; FIG. FIG. 11 is a timing chart illustrating another example of signal readout of another example of the focus detection pixel in the second embodiment; FIG. FIG. 10 is a diagram schematically illustrating another example of the configuration of focus detection pixels in the second embodiment;

<First Embodiment>
An imaging device according to a first embodiment and an imaging apparatus including this imaging device will be described with reference to the drawings.
FIG. 1 is a cross-sectional view for explaining the configuration of a digital camera 100, which is an imaging device according to the first embodiment. For convenience of explanation, an orthogonal coordinate system consisting of x-axis, y-axis and z-axis is set as illustrated. In FIG. 1, the z-axis is set along the horizontal direction of the drawing, the y-axis is set along the vertical direction of the drawing, and the x-axis is set along the direction orthogonal to the y-axis and the z-axis.

The digital camera 100 is composed of a camera body 200 and a photographing lens body 300, and the photographing lens body 300 is mounted via a mount (not shown). A photographing lens body 300 having various photographing optical systems can be attached to the camera body 200 via a mount section.

The photographic lens body 300 includes the photographic optical system 1 . The imaging optical system 1 is an optical system for forming an image of a subject on the imaging surface of the imaging element 8, and is composed of a plurality of lenses including a focusing lens. A focus adjustment lens that constitutes the imaging optical system 1 is driven to an in-focus position along the direction of the optical axis L (z direction) by a drive unit (not shown) according to the lens drive amount. The lens drive amount is calculated by a drive section (not shown) using a defocus amount input from the camera body 200 side via an electrical contact provided on a mount section (not shown).

A control unit 5 and a focus detection device 6 having an imaging device 8 and a focus detection calculation unit 14 are provided inside the camera body 200 . An operation unit 11 is provided in the camera body 200 . The imaging device 8 is, for example, a back-illuminated CMOS or other image sensor, and has imaging pixels and focus detection pixels that are arranged two-dimensionally (rows and columns) on the xy plane. The imaging pixels receive the light flux that has passed through the entire exit pupil area of the imaging optical system 1 and output image signals. The focus detection pixels receive light beams that have passed through a part of the exit pupil areas, such as left, right, top, and bottom, of the imaging optical system 1, and output focus detection signals. The imaging pixels of the imaging device 8 are provided with color filters of R (red), G (green), and B (blue), respectively. Since the imaging pixels capture the subject image through the color filters, the imaging signal has color information of the RGB color system. Note that the focus detection pixels may not be provided with color filters, and all the focus detection pixels may be provided with the same (for example, G) color filter. Details of the imaging device 8 will be described later.

The operation unit 11 includes various switches provided corresponding to various operation members operated by the user, and outputs operation signals to the control unit 5 according to the operation of the operation members. Operation members include, for example, a release button, a menu button for displaying a menu screen on a rear monitor (not shown) provided on the rear surface of the camera body 200, and a cross key operated when selecting and operating various settings. , a determination button for determining settings selected by the cross key, an operation mode switching button for switching the operation of the digital camera 100 between shooting mode and playback mode, and an exposure mode switching button for setting the exposure mode. .

The control unit 5 is an arithmetic circuit that has a CPU, ROM, RAM, etc., and controls each component of the digital camera 100 and executes various data processing based on a control program. The control program is stored in a non-volatile memory (not shown) within the control unit 5 . The control unit 5 controls the driving of the imaging element 8 to cause the imaging element 8 to perform charge accumulation, readout of imaging signals, and the like. The control unit 5 uses the imaging signal output from the imaging pixels of the imaging element 8 as an image signal, performs various image processing on the image signal to generate image data, and then adds additional information and the like to generate an image. Generate files. The generated image file is recorded in a recording medium (not shown) such as a memory card. The control unit 5 generates display image data for display on a rear monitor (not shown) based on the generated image data and the image data recorded on the recording medium. The focus detection calculation unit 14 uses the focus detection signals output from the focus detection pixels of the image sensor 8 to calculate the defocus amount by a known phase difference detection method.

Next, the imaging element 8 in the first embodiment will be described in detail.
FIG. 2 is a diagram schematically showing an imaging surface 800 of the imaging element 8 of the first embodiment. Also in FIG. 2, an orthogonal coordinate system consisting of the x-axis, y-axis, and z-axis is set in the same manner as in the example shown in FIG. A plurality of imaging pixels 810 and a plurality of focus detection pixels 820 for acquiring focus detection signals used for calculating the defocus amount are arranged on the imaging plane 800 . In FIG. 2, the focus detection pixels 820 are shaded. The focus detection pixels 820 are arranged for each predetermined pixel row (y direction). In pixel rows in which the focus detection pixels 820 are arranged, for example, the focus detection pixels 820 are arranged every one imaging pixel 810 . Note that the arrangement of the imaging pixels 810 and the focus detection pixels 820 shown in FIG. 2 is an example, and the arrangement is not limited to this example.

3A and 3B schematically show an example of the structure of the image pickup pixel 810 and the image pickup pixel 810, and FIG. 3A schematically shows the planar structure of the adjacent image pickup pixel 810 and focus detection pixel 820. FIG. FIG. 3B is a diagram schematically showing the cross-sectional structure of the imaging pixel 810 and the focus detection pixel 820, showing the cross section taken along the line aa of FIG. 3A. Also in FIG. 3, an orthogonal coordinate system consisting of the x-axis, the y-axis, and the z-axis is set in the same manner as in the example shown in FIG. In this embodiment, a case where the pixel pitch (size) of the imaging pixels 810 and the focus detection pixels 820 is about 10 μm is taken as an example.

As shown in FIGS. 3A and 3B, the imaging pixel 810 includes a first microlens 811 and a first photoelectric conversion lens that photoelectrically converts light passing through the first microlens 811 to generate electric charges. 812 and outputs a signal (imaging signal) used for image generation. The imaging pixel 810 has a first boundary shielding portion 813 between the first microlens 811 and the first photoelectric conversion portion 812 . The first boundary light shielding portion 813 is provided on a plane parallel to the xy plane at the boundary between adjacent focus detection pixels 820 .

The focus detection pixel 820 has a second microlens 821 and a second photoelectric conversion unit 822 that photoelectrically converts light that has passed through the second microlens 821 to generate an electric charge. signal). The second microlens 821 has a refractive power different from that of the first microlens 811 . In the present embodiment, the focal position of the first microlens 811 is located on the far side (z direction - side in FIG. 3B) from the focal position of the second microlens 821 . In the example shown in FIG. 3B, the focal position of the first microlens 811 is the position FP1, and the focal position of the second microlens 821 is the position FP2.

In the focus detection pixel 820, the area of the second microlens 821 on the xy plane intersecting the optical axis direction (z direction) of the second microlens 821 is smaller than the area of the first microlens 811 on the xy plane. . In other words, in the focus detection pixel 820, a plurality of second microlenses 821 are arranged in a region (hereinafter referred to as a unit region) having the same area as the first microlenses 811 on the xy plane. . The example of FIG. 3 shows a case where four second microlenses 821a, 821b, 821c, and 821d (collectively referred to as 821) are arranged in the unit area. Four second microlenses 821 are arranged along the x-direction and the y-direction. That is, the second microlenses 821a and 821b are arranged along the x-direction, and the second microlenses 821c and 821d are arranged along the x-direction. Also, the second microlenses 821a and 821c are arranged along the y direction, and the second microlenses 821b and 821d are arranged along the y direction.

Between the second microlens 821a and the second photoelectric conversion part 822, a first light shielding part for shielding light incident on the + side in the x direction from the center of the second microlens 821a on a plane parallel to the xy plane. 823a is provided. Similarly, between each of the second microlenses 821b, 821c, and 821d and the second photoelectric conversion unit 822, each center of each of the second microlenses 821b, 821c, and 821d parallel to the xy plane. First light blocking portions 823b, 823c, and 823d (hereinafter collectively referred to as reference numeral 823) are provided to block light incident on the + side in the x direction. The first light shielding portion 823 is arranged such that its z-direction position substantially coincides with the z-direction position of the focal position FP2 of the second microlens 821 described above.
Also, in the vicinity of the boundary with the imaging pixel 810, a second boundary light shielding section 824 is provided between the second microlens 821 and the second photoelectric conversion section 822 in parallel with the xy plane.

3(a) and 3(b) show, as an example, the case where the focus detection pixel 820 has the first light shielding portion 823 that shields the + side of the second microlens 821 in the x direction. However, the focus detection pixels 820 also include those having a light shielding portion 825 that shields the - side of the second microlenses 821 in the x direction, as shown in FIG. 3(c).

The configuration of the focus detection pixel 820 is not limited to the example shown in FIG. can have a light blocking portion extending to the
An example of this case is shown in FIG. FIG. 4(a) is a diagram schematically showing a cross section of the image sensor 810 and the focus detection pixel 820, taken along the line aa in FIG. 3(a) described above. In this case, the focus detection pixel 820 has a second light shielding section 826 on the first light shielding section 823a and on the boundary with the second microlens 821b. The second light shielding portion 826 is formed along the z direction so as to extend to the + side in the z direction. Accordingly, it is possible to prevent the light passing through the second microlens 821a from entering the region of the second photoelectric converter 822 under the second microlens 821b.
Although not shown in FIG. 4A, a similar second light shielding section 826 is provided above the first light shielding section 823c of the focus detection pixel 820 as well.

Between the focus detection pixel 820 having the configuration shown in FIG. may have. Examples of this case are shown in FIGS. 4B and 4C are diagrams schematically showing cross sections of the focus detection pixel 820, taken along line aa in FIG. 3A described above.
In FIG. 4B, the focus detection pixel 820 has a third light shielding portion 827 in the second boundary light shielding portion 824 and the first light shielding portion 823b. The third light shielding portion 827 is formed along the z-direction so as to extend to the - side in the z-direction. In this case, the third light shielding section 827 is similarly provided in the first light shielding section 823d, which is not shown in FIG. 4B.
In FIG. 4C , the focus detection pixel 820 has a fourth light shielding portion 828 in the second boundary light shielding portion 824 and the second light shielding portion 826 . The fourth light shielding portion 828 is formed along the z direction so as to extend to the + side in the z direction. In this case, the fourth light shielding portion 828 is similarly provided in the first light shielding portion 823d, which is not shown in FIG. 4(c).
By having the configurations shown in FIGS. 4B and 4C, the light passing through the second microlens 821a or 821b of the focus detection pixel 820 can be prevented from entering the adjacent imaging pixel 810. can. The focus detection pixel 820 having the configuration described above can improve focus detection accuracy without increasing the distance in the z direction between the second microlens 821 and the second photoelectric conversion unit 822 .

3 and 4 show an example in which four second microlenses 821 are arranged in a unit area in the focus detection pixel 820, but the number of the second microlenses 821 is more than four. or less.
FIG. 5 schematically shows a case where two second microlenses 821 are arranged within a unit area. FIG. 5(a) is a plan view schematically showing the imaging pixels 810 and the focus detection pixels 820 as in FIG. 3(a). 5A, the focus detection pixel 820 has only the second microlenses 821b and 821c of the second microlenses 821 shown in FIG. 3A. That is, the focus detection pixel 820 has the second microlenses 821 arranged along the diagonal direction of the rectangular area of the second photoelectric conversion section 822 . Note that the focus detection pixel 820 may have only the second microlenses 821a and 821d shown in FIG. It may have only lenses 821b and 821d.

The plan view of FIG. 5(b) schematically shows the case where the focus detection pixel 820 has the second microlenses 821e and 821f. The second microlenses 821e and 821f are arranged along the y-direction. In this case, the second microlens 821e in FIG. 5B is arranged at a position corresponding to the positions where the second microlenses 821a and 821b are arranged in FIG. It is arranged at a position corresponding to the position where the second microlenses 821c and 821d are arranged in 3(a). Between the second microlens 821e and the second photoelectric conversion part 822, a first light shielding part 823e is provided parallel to the xy plane for shielding a region on the + side in the x direction from the center of the second microlens 821e. Between the second microlens 821f and the second photoelectric conversion part 822, a first light shielding part 823f is provided parallel to the xy plane for shielding a region on the + side in the x direction from the center of the second microlens 821f.

Using focus detection signals output from a pair of focus detection pixels 820 (the focus detection pixel 820 in FIG. 3A and the focus detection pixel 820 in FIG. 3C) having the above configuration, the focus detection calculation unit 14 calculates the defocus amount using a known phase difference detection method. The focus detection calculation unit 14 combines the first signal train {an} in which the focus detection signals from the second photoelectric conversion units 822 of the focus detection pixels 820 shown in FIG. The amount of relative deviation from the second signal train {bn} in which the focus detection signals from the photoelectric conversion unit 822 of the focus detection pixels 820 are sequentially arranged is detected, and the focus adjustment state of the photographing optical system 1, that is, the defocus amount is determined. To detect.

According to the first embodiment described above, the following effects are obtained.
(1) The imaging element 8 has a first photoelectric conversion unit 812 that photoelectrically converts light that has passed through the first microlens 811 to generate an electric charge. A focus detection pixel 820 that has a second photoelectric conversion unit 822 that photoelectrically converts light passing through a second microlens 821 that has a refractive power different from that of the one microlens 811 to generate electric charges, and that generates a signal used for focus detection. And prepare. As a result, it is possible to suppress an increase in the thickness of the second focus detection pixel 820 in the optical axis direction (z direction), thereby suppressing the light passing through the second microlens 821 from entering the adjacent imaging pixel 810. can. The focus detection pixel 820 can improve focus detection accuracy without increasing the distance in the z direction between the second microlens 821 and the second photoelectric conversion unit 822 .

(2) The focal position FP1 of the first microlens 811 is positioned on the - side in the z direction with respect to the focal position FP2 of the second microlens 821 . Accordingly, light can be collected on the second photoelectric conversion unit 822 without increasing the thickness of the focus detection pixel 820 in the z direction. In addition, it is possible to suppress the light that has passed through the second microlens 821 from entering the first photoelectric conversion unit 812 of the imaging device 810 .

(3) The area of the second microlens 821 on the plane (xy plane) intersecting the optical axis of the second microlens 821 is the area of the first microlens 811 on the plane intersecting the optical axis of the first microlens 811. smaller than area. Thereby, an increase in the thickness of the second focus detection pixel 820 in the optical axis direction (z direction) can be suppressed.

(4) a plurality of second microlenses 821 in a region (unit region) having the same area as the first microlenses 811 on a plane (xy plane) intersecting the optical axis of the first microlenses 811; is placed. Thereby, an increase in the thickness of the second focus detection pixel 820 in the optical axis direction (z direction) can be suppressed.

(5) The focus detection pixel 820 has a second light shielding portion 826 extending toward the second microlens 821 along the optical axis direction (z direction) of the second microlens 821 between adjacent focus detection pixels 820 . have. As a result, it is possible to prevent the light that should be incident on the area below the microlens 821a in the second photoelectric conversion unit 822 from entering the area below the microlens 821, thereby suppressing a decrease in focus detection accuracy.

(6) The focus detection pixel 820 has a third light shielding portion 827 or a fourth light shielding portion 828 formed along the optical axis direction (z direction) of the second microlens 821 between the adjacent imaging pixels 810. have. This makes it possible to prevent the light that has passed through the second microlens 821 of the focus detection pixel 820 from entering the first photoelectric conversion unit 812 of the imaging pixel 810 .

<Second Embodiment>
An imaging device according to a second embodiment and an imaging apparatus having this imaging device will be described with reference to the drawings. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and differences are mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment in that the focus detection pixel has a plurality of second photoelectric conversion units in a region having the same area as the first microlens of the imaging pixel on the xy plane. different.

6A and 6B are diagrams schematically showing the schematic configuration of the image sensor 8 according to the second embodiment, FIG. ) shows a cross section of the imaging pixel 810 and the focus detection pixel 920 along the line aa in FIG. 6(a). The configuration of the imaging pixel 810 is the same as in the case of the first embodiment.

FIG. 6 illustrates a case where four focus detection pixels 920 (920a, 920b, 920c, 920d) are provided in the unit area. Note that the number of focus detection pixels 920 in the unit area is not limited to this, and may exceed four or may be fewer. Each focus detection pixel 920 includes a second microlens 921, two second photoelectric conversion units 922a and 922b (referred to collectively by reference numeral 922), a first light shielding unit 923, and a second boundary light shielding unit. 924. Focus detection pixels 920a and 920b are arranged along the x-direction, and focus detection pixels 920c and 920d are arranged along the x-direction.

As in the first embodiment, the second microlens 921 has a refractive power different from that of the first microlens 811 , and the focal position of the second microlens 821 is higher than the focal position of the first microlens 811 . Located on the + side in the z direction. Also in the second embodiment, the area of the second microlens 921 is smaller than the area of the unit area of the first microlens 811 in the xy plane intersecting the optical axis of the second microlens 921 . In other words, a plurality of second microlenses 921 are arranged in the unit area.

Two second photoelectric conversion units 922a and 922b included in each focus detection pixel 920 are arranged along the x direction.
The first light shielding portion 923 is arranged near the boundary between the adjacent focus detection pixels 920 on a plane parallel to the xy plane between the second microlens 921 and the second photoelectric conversion portion 922 . The second boundary light shielding portion 924 is arranged near the boundary between the adjacent imaging pixels 810 on a plane parallel to the xy plane between the second microlens 921 and the second photoelectric conversion portion 922 .

FIG. 7 shows a circuit diagram of the focus detection pixel 920 within the unit area. A common reset transistor RST is provided for the four focus detection pixels 920 in the unit area, and the reset transistor RST is turned on and off by the reset wiring 900 . Transfer transistors TX1L, TX1R, TX2L, TX2R, TX3L, 3X3R, TX4L, and TX4R (collectively referred to as TX) are provided for each second photoelectric conversion unit 922 . Transfer transistors TX1L and TX1R provided in the second photoelectric conversion units 922a and 922b of the focus detection pixel 920a are turned on and off by transfer wirings 911 and 912, respectively. The transfer transistors TX2L and TX2R provided in the second photoelectric conversion units 922a and 922b of the focus detection pixel 920b are turned on and off by transfer wirings 913 and 914, respectively. Transfer transistors TX3L and TX3R provided in the second photoelectric conversion units 922a and 922b of the focus detection pixel 920c are turned on and off by transfer wirings 915 and 916, respectively. The transfer transistors TX4L and TX4R provided in the second photoelectric conversion units 922a and 922b of the focus detection pixel 920d are turned on and off by transfer wirings 917 and 918, respectively. A common selection transistor SEL is provided for the four focus detection pixels 920 in the unit area, and is turned on and off by a selection wiring 919 .

By turning on and off the reset transistor RST and the transfer transistor TX in the unit area, the charge accumulation including the charge accumulation start time, the accumulation end time, and the transfer timing is controlled for the four focus detection pixels 920 included in the unit area. can do. Also, by turning on/off the selection transistor SEL of the unit area, the photoelectric conversion signal of each focus detection pixel 920 can be output via the common output wiring 901 .

In the focus detection pixel 920 having the above circuit configuration, the photoelectric conversion signals (addition signal) from the second photoelectric conversion units 922a on the x-direction - side of the four focus detection pixels 920 in the unit area are collectively read out. After that, photoelectric conversion signals (addition signals) from the second photoelectric conversion units 922b on the + side in the x direction are collectively read out.

A timing chart for this case is shown in FIG. In FIG. 8, when the signal RST becomes high level at time t1, the reset transistor RST is turned on, and the potentials of FD1 to FD8 become reset potentials. Furthermore, at time t1, the signal SEL becomes high level, so that a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. That is, a signal (noise signal) when FD1 to FD8 are set to the reset potential is read out to the output wiring 901 .

At time t2, the signals TX1L, TX2L, TX3L, and TX4L go high, turning on the transfer transistors TX1L, TX2L, TX3L, and TX4L, and charges are transferred from the four second photoelectric conversion units 922a. Further, at time t2, since the signal SEL is at high level, the addition signal obtained by adding the charges from the four second photoelectric conversion units 922a is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL1. be.

At time t3, the signals TX1R, TX2R, TX3R, and TX4R go high to turn on the transfer transistors TX1R, TX2R, TX3R, and TX4R, and charges are transferred from the four photoelectric conversion units 922b. Further, at time t3, since the signal SEL is at high level, the addition signal obtained by adding the charges from the four second photoelectric conversion units 922a is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL1. be.
Thereafter, in the same manner as in the period from time t1 to time t3, readout of noise signals and readout of addition signals from the focus detection pixels 920 of other pixel rows are performed.

In the above description, for each of the four focus detection pixels 920 in the unit area, the addition signals from the second photoelectric conversion units 922a on the negative side in the x direction and the second photoelectric conversion units 922b on the positive side in the x direction are combined. Although the case of reading is mentioned as an example, it is not limited to this example. For example, for each of the four focus detection pixels 920 in the unit area, the photoelectric conversion signals may be sequentially and individually read out from the second photoelectric conversion units 922a and 922b.

A timing chart for this case is shown in FIG. In FIG. 9, when the signal RST becomes high level at time t1, the reset transistor RST is turned on, and the potentials of FD1 to FD8 become reset potentials. Furthermore, at time t1, the signal SEL becomes high level, so that a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL1. That is, a signal (noise signal) when the FDs 1 to 8 are set to the reset potential is read out to the output wiring 901 .

At time t2, the signal TX1L goes high, turning on the transfer transistor TX1L and transferring the charge from the second photoelectric conversion unit 922a of the focus detection pixel 920a. Also, at time t2, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922a of the focus detection pixel 920a is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL. At time t3, the transfer transistor TX1R is turned on by the high level of TX1R, and charges are transferred from the second photoelectric conversion unit 922b of the focus detection pixel 920a. Also, at time t3, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922b of the focus detection pixel 920a is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL.

At time t4, the reset transistor RST is turned on by the signal RST becoming high level, and a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. At time t5, the signal TX2L becomes high level, so that the transfer transistor TX2L is turned on, and charges are transferred from the second photoelectric conversion unit 922a of the focus detection pixel 920b. Also, at time t5, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922a of the focus detection pixel 920b is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL. At time t6, the transfer transistor TX2R is turned on by the high level of TX2R, and charges are transferred from the second photoelectric conversion unit 922b of the focus detection pixel 920b. Also, at time t6, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922b of the focus detection pixel 920b is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL1.

At time t7, the reset transistor RST is turned on by the signal RST becoming high level, and a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. At time t8, the signal TX3L becomes high level, so that the transfer transistor TX3L is turned on, and charges are transferred from the second photoelectric conversion unit 922a of the focus detection pixel 920c. Also, at time t8, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922a of the focus detection pixel 920c is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL. At time t9, TX3R goes high to turn on the transfer transistor TX3R, and charge is transferred from the second photoelectric conversion unit 922b of the focus detection pixel 920c. Also, at time t9, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922b of the focus detection pixel 920c is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL.

At time t10, the signal RST becomes high level to turn on the reset transistor RST, and a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. At time t11, the signal TX4L becomes high level, so that the transfer transistor TX4L is turned on, and charges are transferred from the second photoelectric conversion unit 922a of the focus detection pixel 920d. Also, at time t11, the signal SEL is high level, so the charge from the second photoelectric conversion unit 922a of the focus detection pixel 920d is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL. At time t12, the transfer transistor TX4R is turned on by the high level of TX4R, and charges are transferred from the second photoelectric conversion unit 922b of the focus detection pixel 920d. Also, at time t12, since the signal SEL is at high level, the charge from the second photoelectric conversion section 922b of the focus detection pixel 920d is output to the output wiring 901 via the amplification section AMP and the selection transistor SEL.
Thereafter, similarly to the period from time t1 to time t12, readout of noise signals and readout of photoelectric conversion signals (focus detection signals) from the focus detection pixels 920 of other pixel rows are performed.

In the above description, the case where each of the four focus detection pixels 920 provided in the unit area has two second photoelectric conversion units 922a and 922b was taken as an example, but the configuration of the focus detection pixel 920 is It is not limited to this example.
FIG. 10 schematically shows the configuration of another example of the focus detection pixel 920. As shown in FIG. 10(a) shows a plane of the imaging pixel 810 and the focus detection pixel 920, and FIG. 10(b) shows a cross section of the imaging pixel 810 and the focus detection pixel 920 along the line aa in FIG. 10(a). show. The configuration of the imaging pixel 810 is the same as in the case of the first embodiment.

FIG. 10 illustrates a case where four focus detection pixels 920 (920a, 920b, 920c, 920d) are provided in the unit area. Also in this case, the number of focus detection pixels 920 in the unit area is not limited to this, and may exceed four or may be less. Each focus detection pixel 920 has a second microlens 921 , a second photoelectric conversion section 922 , a first light shielding section 923 , and a second boundary light shielding section 924 . That is, in the example shown in FIG. 10, each focus detection pixel 920 has one second photoelectric conversion unit 922, unlike the example shown in FIG. Focus detection pixels 920a and 920b are arranged along the x-direction, and focus detection pixels 920c and 920d are arranged along the x-direction. The first light shielding portion 923 of the focus detection pixel 920a and the focus detection pixel 920c shields the half region of the second photoelectric conversion portion 922 on the + side in the x direction from light, and the first light shielding portion 923 of the focus detection pixel 920b and the focus detection pixel 920d is blocked. The light shielding portion 923 shields the half region of the second photoelectric conversion portion 922 on the − side in the x direction. Other points are the same as the focus detection pixel 920 shown in FIG.

FIG. 11 shows a circuit diagram of the focus detection pixel 920 within the unit area. A common reset transistor RST is provided for the four focus detection pixels 920 in the unit area, and the reset transistor RST is turned on and off by the reset wiring 900 . Transfer transistors TX1L, TX2R, TX3L, and TX4R are provided for each second photoelectric conversion unit 922 . The transfer transistor TX1L provided in the second photoelectric conversion unit 922 of the focus detection pixel 920a is turned on and off by the transfer wiring 911. FIG. The transfer transistor TX2R provided in the second photoelectric conversion unit 922 of the focus detection pixel 920b is turned on and off by the transfer wiring 912. FIG. The transfer transistor TX3L provided in the second photoelectric conversion unit 922 of the focus detection pixel 920c is turned on and off by the transfer wiring 913. FIG. The transfer transistor TX4R provided in the second photoelectric conversion unit 922 of the focus detection pixel 920d is turned on and off by the transfer wiring 914. FIG. A common selection transistor SEL is provided for the four focus detection pixels 920 in the unit area, and is turned on and off by a selection wiring 919 .

By turning on and off the reset transistor RST and the transfer transistor TX in the unit area, the charge accumulation including the charge accumulation start time, the accumulation end time, and the transfer timing is controlled for the four focus detection pixels 920 included in the unit area. can do. Also, by turning on/off the selection transistor SEL of the unit area, the photoelectric conversion signal of each focus detection pixel 920 can be output via the common output wiring 901 .

In the focus detection pixel 920 having the above circuit configuration, photoelectric conversion from the second photoelectric conversion units 922a and 922c of the focus detection pixels 920a and 920c on the − side in the x direction among the four focus detection pixels 920 in the unit area. The signals (addition signals) are read out collectively, and then the photoelectric conversion signals (addition signals) from the second photoelectric conversion units 922b and 921d of the focus detection pixel 920b on the + side in the x direction are collectively read out.

A timing chart for this case is shown in FIG. In FIG. 12, when the signal RST becomes high level at time t1, the reset transistor RST is turned on, and the potentials of FD1 to FD4 become reset potentials. Furthermore, at time t1, the signal SEL becomes high level, so that a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. That is, a signal (noise signal) when the FDs 1 to 4 are set to the reset potential is read out to the output wiring 901 .

At time t2, the signals TX1L and TX3L become high level, so that the transfer transistors TX1L and TX3L are turned on, and charges are transferred from the second photoelectric conversion units 922a and 921c. Further, at time t2, since the signal SEL is at high level, the addition signal obtained by adding the charges from the second photoelectric conversion units 922a and 922c is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL. .

At time t3, the signal RST becomes high level to turn on the reset transistor RST, and a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. At time t4, the signals TX2R and TX4R become high level, so that the transfer transistors TX2R and TX4R are turned on, and charges are transferred from the second photoelectric conversion units 922b and 921d. Further, at time t4, since the signal SEL is at a high level, the addition signal obtained by adding the charges from the second photoelectric conversion units 922b and 921d is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL. .
Thereafter, in the same manner as in the period from time t1 to time t4, readout of noise signals and readout of addition signals from the focus detection pixels 920 of other pixel rows are performed.

In the above description, of the four focus detection pixels 920 in the unit area, the addition signal is read from the two focus detection pixels 920a and 920c on the negative side in the x direction, and the two focus detection pixels 920b and 920b on the positive side in the x direction are read out. Although the case where the addition signal is read out from 920d is mentioned as an example, it is not limited to this example. For example, the photoelectric conversion signals may be individually read out sequentially from the four focus detection pixels 920 of the unit area.

A timing chart in this case is shown in FIG. In FIG. 13, when the signal RST becomes high level at time t1, the reset transistor RST is turned on, and the potentials of FD1 to FD4 become reset potentials. Furthermore, at time t1, the signal SEL becomes high level, so that a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. That is, a signal (noise signal) when FD1 to FD4 are set to the reset potential is read out to the output wiring 901 .

At time t2, the signal TX1L goes high, turning on the transfer transistor TX1L and transferring the charge from the second photoelectric conversion unit 922a of the focus detection pixel 920a. Also, at time t2, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922a of the focus detection pixel 920a is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL.

At time t3, the reset transistor RST is turned on by the signal RST becoming high level, and a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. At time t4, the signal TX2R becomes high level, so that the transfer transistor TX2R is turned on, and charges are transferred from the second photoelectric conversion unit 922b of the focus detection pixel 920b. Also, at time t4, the signal SEL is high level, so the charge from the second photoelectric conversion unit 922b of the focus detection pixel 920b is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL.

At time t5, the reset transistor RST is turned on by the signal RST becoming high level, and a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. At time t6, the signal TX3L becomes high level, so that the transfer transistor TX3L is turned on, and charges are transferred from the second photoelectric conversion unit 922c of the focus detection pixel 920c. Also, at time t6, the signal SEL is high level, so the charge from the second photoelectric conversion unit 922c of the focus detection pixel 920c is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL.

At time t7, the signal RST becomes high level to turn on the reset transistor RST, and a signal based on the reset potential is output to the output wiring 901 by the amplifier AMP and the selection transistor SEL. At time t8, TX4R goes high to turn on the transfer transistor TX4R, and charge is transferred from the second photoelectric conversion unit 922d of the focus detection pixel 920d. Also, at time t8, since the signal SEL is at high level, the charge from the second photoelectric conversion unit 922d of the focus detection pixel 920d is output to the output wiring 901 via the amplification unit AMP and the selection transistor SEL.
Thereafter, similarly to the period from time t1 to time t8, readout of noise signals and readout of photoelectric conversion signals (focus detection signals) from the focus detection pixels 920 of other pixel rows are performed.

The imaging device 8 of the second embodiment described above can obtain the same effects as those obtained by the imaging device 8 of the first embodiment.

The second light shielding portion 922 included in the focus detection pixel 920 is not limited to that shown in FIG. For example, the second light shielding portion 922 has a side that is not parallel to the y direction perpendicular to the x direction in which the imaging pixel 810 and the focus detection pixel 920 are aligned in the xy plane that intersects the optical axis of the second microlens 921. shape.

FIG. 14 schematically shows a planar configuration of the imaging pixels 810 and the focus detection pixels 920 in this case. The example shown in FIG. 14 is different from the focus detection pixel 920 of the image sensor 8 of FIG. 10 in the shape of the first light shielding portion 923 in the xy plane, but the other configuration is the same as the focus detection pixel 920 of FIG. be.

A first light shielding portion 923a of the focus detection pixel 920a has two sides 950 and 951 parallel to the x-axis in the xy plane, a side 952 parallel to the y-axis, and a side 953 not parallel to the y-axis. The side 950 is provided on the + side in the y direction and is a straight line extending from the end on the + side in the x direction to the - side in the x direction. The side 951 is provided on the - side in the y direction and is a straight line extending from the end on the + side in the x direction to the - side in the x direction. Side 951 is longer than side 950 . The side 952 is a straight line connecting the endpoints of the sides 950 and 951 on the positive side in the x direction, and the side 953 is a straight line connecting the endpoints of the sides 950 and 951 on the negative side in the x direction.

In the focus detection pixel 920b, the first light shielding portion 923b shields the - side in the x direction. The shape of the first light shielding portion 923b on the xy plane is such that the side parallel to the x-axis on the + side of the y direction is longer than the side parallel to the x-axis on the - side of the y direction, and the side not parallel to the y-axis connect the endpoints of the two sides parallel to the x-axis of the x-direction + side. The first light shielding portion 923c of the focus detection pixel 920c has a shape line-symmetrical to the first light shielding portion 923a with respect to the cc line along the x-axis between the focus detection pixels 920a and 920c. The first light shielding portion 923d of the focus detection pixel 920d has a shape line-symmetrical to the first light shielding portion 923b with respect to the cc line along the x-axis.

By having the first light shielding portion 923 of each focus detection pixel 920 have the above shape on the xy plane, it is possible to detect the focus state of the subject along the x-axis direction. In addition, in order to enable detection of the focus state of an object along the x-axis direction, the image pickup element 8 includes a focus detection pixel having a light-shielding portion shaped to shield the region on the + side of the y direction or the region on the - side of the y direction. Since there is no need to dispose the image pickup pixels 810 at the same position, it is not necessary to reduce the number of the image pickup pixels 810, and deterioration in image quality of the photographed image can be suppressed.

It should be noted that in the above-described first and second embodiments and various modifications thereof, the case where the imaging pixel 810 has one first microlens 811 has been described as an example. However, like the focus detection pixels 820 and 920, the imaging pixel 810 may also have a plurality of first microlenses. That is, the imaging pixel 810 may have a first photoelectric conversion unit 812 that photoelectrically converts light that has passed through the plurality of first microlenses to generate electric charges, and may output a signal used for image generation. Also in this case, the first microlens of the imaging pixel 810 and the second microlenses 821 and 921 of the focus detection pixels 820 and 920 have different refractive powers. As a result, it is possible to obtain the same effect as in the case of having the configurations of the first and second embodiments.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

6 Focus detection device 8 Imaging device 14 Focus detection calculation unit 100 Digital camera 810 Imaging pixel 811 First microlens 812 First photoelectric conversion unit 820, 920 Focus detection pixels 821, 921 Second micro Lenses 822, 922...Second photoelectric converters 823, 923...First light shielding part 826...Second light shielding part 827...Third light shielding part 828...Fourth light shielding part

Claims (18)

1. a first pixel that has a first photoelectric conversion unit that photoelectrically converts light that has passed through the first microlens to generate an electric charge and that outputs a signal used for image generation;
   a second pixel having a second photoelectric conversion unit that photoelectrically converts light passing through a second microlens having a refractive power different from that of the first microlens to generate an electric charge, and that generates a signal used for focus detection; An image sensor.
2. a first pixel that has a first photoelectric conversion unit that photoelectrically converts light that has passed through the plurality of first microlenses to generate an electric charge and that outputs a signal used for image generation;
   and a second pixel that has a second photoelectric conversion unit that photoelectrically converts light that has passed through the second microlens to generate an electric charge, and that outputs a signal used for focus detection.
3. In the imaging device according to claim 2,
   The imaging device, wherein the first microlens and the second microlens have different refractive powers.
4. In the imaging device according to any one of claims 1 to 3,
   The imaging device, wherein the focal position of the first microlens is positioned further away from the microlens than the focal position of the second microlens.
5. In the imaging device according to any one of claims 1 to 4,
   An imaging device, wherein the area of the second microlens on a plane intersecting the optical axis of the second microlens is smaller than the area of the first microlens on the plane intersecting the optical axis of the first microlens. .
6. In the imaging device according to claim 5,
   An imaging device, wherein the plurality of second microlenses are arranged in a region having the same area as that of the first microlenses on a plane intersecting the optical axis of the first microlenses.
7. In the imaging device according to any one of claims 1 to 6,
   An imaging device, wherein a plurality of the second photoelectric conversion units are arranged in a region having the same area as that of the first photoelectric conversion units on a plane intersecting the optical axis of the first microlens.
8. In the imaging device according to any one of claims 1 to 7,
   The imaging element, wherein the first pixel and the second pixel are arranged along a first direction on a plane intersecting the optical axis of the first microlens.
9. In the imaging device according to claim 8,
   The imaging device, wherein the plurality of second pixels are arranged along the first direction and a second direction crossing the first direction.
10. In the imaging device according to claim 8,
    The imaging device, wherein the plurality of second pixels are arranged along a second direction that intersects with the first direction.
11. In the imaging device according to any one of claims 1 to 10,
    The image pickup device, wherein the second pixel includes a first light shielding section that shields part of light that has passed through the second microlens, between the second microlens and the second photoelectric conversion section.
12. In the imaging device according to claim 11,
    The second pixel has, between adjacent second pixels, a second light shielding portion extending toward the second microlens along the optical axis direction of the second microlens.
13. In the imaging device according to claim 11 or 12,
    The imaging device, wherein the second pixel has a second light shielding portion formed along the optical axis direction of the second microlens between the adjacent first pixels.
14. In the imaging device according to any one of claims 11 to 13,
    The first light shielding part has a side that is not parallel to a second direction orthogonal to the first direction in which the first pixel and the second pixel are aligned on a plane that intersects the optical axis of the second microlens. , image sensor.
15. In the imaging device according to any one of claims 1 to 14,
    The second pixels are arranged in a direction in which the first pixels and the second pixels are aligned in a region of one of the second microlenses on a plane intersecting the optical axis of the second microlenses. An imaging device having a plurality of the second photoelectric conversion units.
16. In the imaging device according to any one of claims 1 to 14,
    The image pickup device, wherein the second pixel includes one second photoelectric conversion unit in a region of one second microlens on a plane intersecting the optical axis of the second microlens.
17. an imaging device according to any one of claims 1 to 14;
    A focus detection device comprising: a detection unit that detects a focus state of light incident on the image sensor based on a signal from the second pixel of the image sensor.
18. an imaging optical system;
    An imaging device comprising: the focus detection device according to claim 17 .

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