JP2011250299A - Imaging element unit and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging element unit capable of suppressing charge saturation while enhancing photosensitivity.SOLUTION: An imaging element unit 100 comprises: a photoelectric conversion part 114; a plurality of movable mirrors 121; and a drive unit 125. The photoelectric conversion part 114 comprises a plurality of photoelectric conversion elements 119 arranged in a matrix state to convert light into charge. The plurality of movable mirrors 121 arranged in a matrix state reflects transmission light through the photoelectric conversion part 114 toward the photoelectric conversion part 114. The drive unit 125 is provided so that an angle of the movable mirrors 121 against the photoelectric conversion part 114 is individually changeable.

Description

  The technology disclosed herein relates to an imaging element unit that converts light into an electrical signal and an imaging apparatus including the imaging element unit.

2. Description of the Related Art Conventionally, imaging devices that convert received light into electrical signals by photoelectric conversion, such as CCD (Charge Coupled Device) and CMOS (Complimentary Metal Oxide Semiconductor), are known.
As this type of image sensor, for example, a front-illuminated image sensor is used. A front-illuminated image sensor generally has a multilayer structure formed on a Si substrate by a semiconductor process. For example, a photoelectric conversion unit composed of a photodiode, a circuit, a mask, a color filter, and a microlens are sequentially formed on the Si substrate. An insulating layer is formed on the photoelectric conversion portion, and circuits and masks are formed in a lattice pattern in the insulating layer. The light incident on the microlens passes through the color filter, passes between the circuit and the mask, and reaches the photoelectric conversion unit. The photoelectric conversion unit has a plurality of photoelectric conversion elements, and light reaching the photoelectric conversion unit is converted into an electric signal by each photoelectric conversion element.

In the surface irradiation type imaging device described above, the circuit is formed to be thin so as to secure a light receiving area as much as possible. When the total area of the photoelectric conversion portion is used as a reference, an aperture ratio of, for example, a little over 60% can be ensured by forming the circuit thin.
However, when the size of the image sensor is the same, the area of the photoelectric conversion element corresponding to one pixel becomes smaller as the number of pixels of the image sensor increases, and as a result, the amount of light received by each photoelectric conversion element decreases. Although the aperture ratio is maintained by miniaturization of the semiconductor process, the light receiving sensitivity of the image pickup device is lowered with a decrease in the amount of light received by the photoelectric conversion device.
Therefore, a so-called back-illuminated image sensor has been proposed. In the back-illuminated image sensor, the Si substrate is ground to the vicinity of the photoelectric conversion unit or until the photoelectric conversion unit is exposed. In the above-described surface irradiation type, the Si substrate is disposed on the back side of the imaging device, whereas in the back side irradiation type, the ground surface is used as the incident side, so the back side (exit side) of the photoelectric conversion unit A circuit and a mask are arranged in the circuit. Therefore, the aperture ratio of the image sensor can be set to 100%, and the light receiving sensitivity can be increased.

JP 2005-353996 A

Since it is manufactured by grinding the Si substrate, the back-illuminated image sensor is very thin. Therefore, it has also been proposed to bond a support substrate such as a Si substrate on the side opposite to the incident side in order to ensure strength. In this case, since the Si substrate has a high reflectance, the light transmitted through the photoelectric conversion unit is reflected by the Si substrate and is incident again on the photoelectric conversion element. As a result, for example, the light receiving sensitivity of the back-side illuminated image sensor is improved to at least twice that of the front surface illuminated image sensor.
However, with the back-illuminated type, as a result, the ISO sensitivity becomes too high, and in high-intensity photography, the charge is often saturated with the photoelectric conversion element. In this case, so-called whiteout (Blown out highlights) occurs on the image. Therefore, in the field of imaging devices, in addition to increasing the light receiving sensitivity, it is also required to suppress charge saturation.

The image sensor unit disclosed herein includes a photoelectric conversion unit, a plurality of reflective optical elements, and a drive unit. The photoelectric conversion unit includes a plurality of photoelectric conversion elements that are arranged in a matrix and converts light into electric charges, and a light receiving surface that is formed by the plurality of photoelectric conversion elements and receives incident light. The plurality of reflective optical elements are arranged in a matrix and reflect light transmitted through the photoelectric conversion unit toward the photoelectric conversion unit. The drive unit is provided so that the angle of each reflective optical element with respect to the photoelectric conversion unit can be individually changed.
In this imaging element unit, the transmitted light of each photoelectric conversion element is reflected by the reflective optical element to the photoelectric conversion unit, so that the total amount of light incident on the photoelectric conversion element can be increased and the light receiving sensitivity can be increased.
In addition, since the angle of the plurality of reflective optical elements with respect to the photoelectric conversion unit can be individually changed by the drive unit, the amount of reflected light incident on each photoelectric conversion element can be adjusted for each reflective optical element. As a result, the total amount of light incident on the photoelectric conversion element can be adjusted for each photoelectric conversion element, and charge saturation can be suppressed.

  With this imaging element unit, it is possible to suppress charge saturation while increasing the light receiving sensitivity. In addition, an imaging apparatus using this imaging element unit can perform imaging with high sensitivity and a wide dynamic range.

Schematic configuration diagram of digital camera Schematic block diagram of digital camera Schematic sectional view of the image sensor unit Schematic sectional view of the image sensor unit Partial plan view of image sensor unit Flow chart for shooting Flow chart for shooting (A) and (B) A graph showing the relationship between average luminance and reflectance

<Configuration of digital camera>
The digital camera 1 will be described with reference to FIG.
A digital camera 1 (an example of an imaging device) is an interchangeable lens digital camera, and includes an interchangeable lens unit 2 and a camera body 3. Although the digital camera 1 does not have a quick return mirror, a quick return mirror may be mounted like a conventional digital single lens reflex camera.
(1) Interchangeable Lens Unit As shown in FIG. 1, the interchangeable lens unit 2 includes a lens mount 95, an optical system O, a lens controller 40, an aperture adjustment unit 73, a zoom ring unit 83, and a focus ring unit 88. And a focus adjustment unit 72.

The lens mount 95 is provided so as to be attachable to the body mount 4 of the camera body 3 and has a lens side contact 91. The optical system O is a zoom lens system, for example, and forms an optical image of a subject. The optical system O has a focus lens L for focus adjustment.
The aperture adjustment unit 73 includes an aperture unit 62 and an aperture drive control unit 42. The aperture unit 62 includes an aperture mechanism (not shown) having aperture blades and an aperture drive motor (not shown) that drives the aperture mechanism, and is provided so that the aperture value of the optical system O can be changed. ing. The aperture drive control unit 42 controls the aperture unit 62 based on a command sent from the lens controller 40.
The lens controller 40 includes a CPU (not shown), a ROM 40b, and a RAM 40a, and various functions can be realized by reading a program stored in the ROM 40b into the CPU 10c. For example, the lens controller 40 can grasp the absolute position of the focus lens L from a detection signal of a position detection sensor 67 (described later). Further, the lens controller 40 can calculate the focal length of the optical system O based on the detection result of a linear position sensor 87 (described later). The ROM 40b is a non-volatile memory, and can retain stored information even when power supply is stopped. For example, information (lens information) related to the interchangeable lens unit 2 is stored in the ROM 40b. The lens controller 40 can transmit / receive information to / from a body controller 10 (described later) via a lens side contact 91.

As shown in FIG. 1, the zoom ring unit 83 includes a zoom ring 84 and a linear position sensor 87. The linear position sensor 87 detects the rotation position and rotation direction of the zoom ring 84 and transmits the detection result to the lens controller 40 at a predetermined cycle. The lens controller 40 calculates the focal length of the optical system O based on the detection result of the linear position sensor 87, and transmits the calculated focal length to the body controller 10 at a predetermined cycle. Thus, the body controller 10 can grasp the focal length of the optical system O.
The focus ring unit 88 includes a focus ring 89 and a focus ring angle detection unit 90. The focus ring angle detection unit 90 detects the rotation angle and rotation direction of the focus ring 89 and transmits the detection result to the lens controller 40 at a predetermined cycle. In the manual focus mode, the lens controller 40 transmits the detection result of the focus ring angle detection unit 90 to a focus drive control unit 41 (described later), and the focus drive control unit 41 controls the focus motor 64 (described later) based on the detection result. Control.

As shown in FIGS. 1 and 2, the focus adjustment unit 72 drives the focus lens L in accordance with the operation of the focus ring 89 or in accordance with the calculated defocus amount. The focus adjustment unit 72 includes a focus motor 64, a position detection sensor 67, and a focus drive control unit 41. The focus motor 64 drives the focus lens L in a direction along the optical axis AZ of the optical system O. The position detection sensor 67 detects the position of the focus lens L. The focus drive control unit 41 controls the focus motor 64 based on a command from the lens controller 40.
(2) Camera Body As shown in FIGS. 1 and 2, the camera body 3 includes a body mount 4, an image acquisition unit 35, a display unit 36, a finder unit 38, an operation unit 39, and a body controller 10 ( An example of a control unit), an image recording unit 18, and an image recording control unit 19 are provided.

As shown in FIG. 1, the body mount 4 is a portion to which the lens mount 95 of the interchangeable lens unit 2 is attached, and has a body side contact 92 that can be electrically connected to the lens side contact 91. The camera body 3 can transmit and receive data to and from the interchangeable lens unit 2 via the body mount 4 and the lens mount 95. For example, the body controller 10 transmits a control signal such as an exposure synchronization signal to the lens controller 40 via the body mount 4 and the lens mount 95. Further, the body controller 10 can acquire lens information regarding the interchangeable lens unit 2 from the lens controller 40 via the body mount 4 and the lens mount 95.
As shown in FIG. 1, the operation unit 39 includes, for example, a power switch 25, a release button 30, and a shooting mode switching dial 26. The power switch 25 is provided to turn on / off the power of the digital camera 1 or the camera body 3. The release button 30 is a two-stage switch that can be pressed halfway and fully, and is operated by the user during shooting. The body controller 10 can detect half-pressing and full-pressing operations of the release button 30. When the user presses the release button 30 halfway, for example, photometry processing, distance measurement processing, and focus detection processing are started. When the user fully operates the release button 30, the image acquisition unit 35 acquires the image data of the subject.

The shooting mode switching dial 26 is provided for switching whether to shoot in a so-called live view mode. By operating the shooting mode switching dial 26, it is possible to select whether to shoot through the viewfinder eyepiece window 9 or to shoot while looking at the liquid crystal monitor 20.
As shown in FIGS. 1 and 2, the image acquisition unit 35 includes an image sensor unit 100, a shutter unit 33, a shutter control unit 31, an image processing unit 11, and a timing generator 12.
As shown in FIGS. 1 and 2, the image sensor unit 100 includes an image sensor 110 and a reflection unit 120. The imaging device 110 is a CMOS image sensor, for example, and converts an optical image formed by the optical system O into an electrical signal. Details of the image sensor unit 100 will be described later. The image sensor 110 may be another image sensor such as a CCD image sensor.

As shown in FIG. 1, the shutter unit 33 adjusts the exposure state of the image sensor unit 100. The shutter control unit 31 controls the shutter unit 33 based on a command from the body controller 10. The exposure time is adjusted by the shutter unit 33 and the shutter control unit 31.
The image processing unit 11 performs predetermined image processing on an electrical signal output from an image sensor 110 (described later) of the image sensor unit 100. Specifically, as shown in FIG. 2, the image processing unit 11 includes an analog signal processing unit 13, an A / D conversion unit 14, a digital signal processing unit 15, a buffer memory 16, an image compression unit 17, have. The electrical signal output from the image sensor 110 is sequentially sent from the analog signal processing unit 13 to the A / D conversion unit 14, the digital signal processing unit 15, the buffer memory 16, and the image compression unit 17 for processing.

  The analog signal processing unit 13 performs analog signal processing such as gamma processing on the electrical signal output from the image sensor 110. The A / D conversion unit 14 converts the analog signal output from the analog signal processing unit 13 into a digital signal. The digital signal processing unit 15 performs digital signal processing such as noise removal and edge enhancement on the image signal converted into a digital signal by the A / D conversion unit 14. The buffer memory 16 is a RAM and temporarily stores an image signal as image data. The image data stored in the buffer memory 16 is sequentially sent from the image compression unit 17 to the image recording unit 18 for processing. The image data stored in the buffer memory 16 is read by an instruction from the image recording control unit 19 and transmitted to the image compression unit 17. The image data transmitted to the image compression unit 17 is compressed in accordance with an instruction from the image recording control unit 19. The image data has a smaller data size than the original data by this compression processing. As a method for compressing image data, for example, a JPEG (Joint Photographic Experts Group) method for compressing each frame of image data is used. Thereafter, the compressed image data is recorded in the image recording unit 18 by the image recording control unit 19. In addition, when recording by RAW data is selected by the user, it is possible to record the RAW data in the image recording unit 18 through the image compression unit 17.

The timing generator 12 generates a timing signal for driving the image sensor 110. In this embodiment, the image sensor 110 has a frame rate of 30 [fps].
Note that the digital camera 1 employs a contrast detection method (also referred to as contrast AF) that uses image data generated by the image sensor unit 100 as an autofocus method. By using the contrast detection method, highly accurate focus adjustment can be realized.
The body controller 10 is a control device that controls the center of the camera body 3, and controls each part of the digital camera 1 according to operation information input to the operation unit 39. Specifically, as shown in FIG. 2, the body controller 10 includes a CPU 10c, a ROM 10b, and a RAM 10a, and the body controller 10 realizes various functions by reading a program stored in the ROM 10b into the CPU 10c. can do. For example, the body controller 10 has an arithmetic processing function for autofocus and a function for controlling the reflection unit 120. Details of the body controller 10 will be described later.

As shown in FIGS. 1 and 2, the display unit 36 includes a liquid crystal monitor 20, a display control unit 21, and a finder unit 38. The liquid crystal monitor 20 displays the image signal recorded in the image recording unit 18 or the buffer memory 16 as a visible image based on a command from the display control unit 21. That is, the liquid crystal monitor 20 displays an image based on the electrical signal generated by the image sensor 110. As a display form on the liquid crystal monitor 20, a display form in which only an image signal is displayed as a visible image and a display form in which the image signal and information at the time of photographing are displayed as a visible image are conceivable.
As shown in FIG. 1, the finder unit 38 includes a liquid crystal finder 8 that displays an image acquired by the image sensor 110 and a finder eyepiece window 9 provided on the back surface. The user can view the image displayed on the liquid crystal finder 8 by looking through the finder eyepiece window 9.

As illustrated in FIG. 2, the image recording unit 18 creates a still image file or a moving image file by associating image data with predetermined information to be recorded based on a command from the image recording control unit 19. Further, the image recording unit 18 records a still image file or a moving image file based on a command from the image recording control unit 19. The image recording unit 18 is a recording medium such as an internal memory or a memory card. Note that the predetermined information to be recorded together with the image signal includes, for example, the date and time when the image was shot, focal length information, shutter speed information, aperture value information, and shooting mode information.
<Image sensor unit>
Here, the structure of the image sensor unit 100 will be described in detail. As shown in FIGS. 1 to 3, the image sensor unit 100 includes an image sensor 110 and a reflection unit 120.

(1) Image Sensor The image sensor 110 is a back-illuminated image sensor, and is disposed at a position where it can receive light emitted from the optical system O. As shown in FIGS. 3 and 4, the image sensor 110 includes a photoelectric conversion unit 114, a reinforcing glass 111, a circuit unit 118, a color filter 113, a microlens 112, and a back mask 117 (an example of a light shielding unit). And have.
The photoelectric conversion unit 114 is made of a semiconductor material and performs photoelectric conversion on incident light. The photoelectric conversion unit 114 includes a plurality of photoelectric conversion elements 119 arranged in a matrix and a separation region 116 that forms a boundary between adjacent photoelectric conversion elements 119. As will be described later, since the color filter 113 is provided on the front side (incident side) of the photoelectric conversion unit 114, each photoelectric conversion element 119 has red (R), green (G), and blue (B). Only one color of light is incident. The photoelectric conversion unit 114 has a light receiving surface 119a that receives light.

The photoelectric conversion element 119 is composed of, for example, a photodiode, and converts light into an electric signal (charge). In general, in a photodiode, a p-type semiconductor film (not shown) is formed on a region (not shown) made of an n-type semiconductor. In the present embodiment, the photoelectric conversion element 119 corresponds to a region where an n-type semiconductor and a p-type semiconductor as photodiodes are formed.
As shown in FIGS. 3 to 5, the separation region 116 is provided between the photoelectric conversion elements 119 and is provided in a lattice shape. As a method for forming the isolation region 116, a semiconductor process can be used as in the photoelectric conversion element 119. Since the structure of the semiconductor layer formed in the separation region 116 is different from the structure of the semiconductor layer formed in the photoelectric conversion element 119, the charge generated by the photoelectric conversion element 119 is transmitted to the adjacent photoelectric conversion element 119. Not. As described above, the separation region 116 separates the plurality of photoelectric conversion elements 119.

A substrate layer 130 is disposed on the incident side of the photoelectric conversion unit 114. The substrate layer 130 is a part of the Si substrate remaining after being ground. Since the imaging element 110 is a back-illuminated type, the Si substrate is ground from the back side (the upper side in FIGS. 3 and 4) after the photoelectric conversion unit 114, the circuit unit 118, and the insulating layer 118c are formed on the Si substrate. . As a result, the substrate layer 130 which is a part of the Si substrate remains on the incident side of the photoelectric conversion unit 114.
The circuit unit 118 forms a transmission path for outputting the electric signal (charge) generated by the photoelectric conversion element 119 to the image processing unit 11, and is arranged in a grid along the separation region 116. Since the circuit portion 118 is provided in a lattice shape, the circuit portion 118 has a plurality of substantially square openings 118d. Specifically, the circuit unit 118 includes an electric circuit 118a and a mask 118b. The electric circuit 118 a includes transistors and signal lines, and is arranged in a lattice pattern along the isolation region 116. The mask 118b covers the electric circuit 118a, and is arranged in a lattice pattern similarly to the electric circuit 118a. Since the imaging element 110 is a backside illumination type, the circuit unit 118 is arranged on the back side (outgoing side) of the photoelectric conversion unit 114. The circuit unit 118 is disposed between the photoelectric conversion element 119 and the reflection unit 120. More specifically, an insulating layer 118c is formed between the photoelectric conversion element 119 and the reflection unit 120, and the circuit unit 118 is formed in the insulating layer 118c.

A back mask 117 is disposed on the reflection unit 120 side of the circuit unit 118. The back mask 117 is provided to prevent the light reflected by the reflection unit 120 from entering the adjacent photoelectric conversion element 119, and is formed in a lattice shape like the circuit unit 118. The back mask 117 has a plurality of substantially square openings 117a and is provided in the reflection unit 120 of the insulating layer 118c. When viewed from a direction parallel to the optical axis AZ, the circuit unit 118 and the back mask 117 overlap each other. By providing the back mask 117, it is possible to prevent the transmitted light of the photoelectric conversion element 119 from being reflected by the movable mirror 121 (described later) and entering the adjacent photoelectric conversion element 119 as shown in FIG.
The color filter 113 is a Bayer array primary color filter and is arranged on the incident side of the photoelectric conversion unit 114. More specifically, the color filter 113 is formed on the incident side of the substrate layer 130. It can also be said that the substrate layer 130 is disposed between the color filter 113 and the photoelectric conversion unit 114. The color filter 113 includes a plurality of red filters R, a plurality of green filters G, and a plurality of blue filters B. The red filter R is a filter having a higher transmittance in the visible light wavelength region of red than in the visible light wavelength region of colors other than red. The green filter G is a filter having a higher transmittance in the green visible light wavelength region than in the visible light wavelength region of colors other than green. The blue filter B is a filter having a higher transmittance in the visible light wavelength region of blue than in the visible light wavelength region of colors other than blue.

The red filter R, green filter G, and blue filter B are arranged in a matrix. Specifically, as shown in FIG. 5, when the red filter R, the two green filters G, and the blue filter B arranged in two rows and two columns are set as one unit region Q, a plurality of unit regions Q are arranged in a matrix. Is arranged. In the unit region Q, the two green filters G are arranged diagonally. In the present embodiment, any one of the red filter R, the green filter G, and the blue filter B is disposed at a position corresponding to one photoelectric conversion element 119. That is, one unit region Q corresponds to the photoelectric conversion element 119 for four pixels. The color filter 113 may be a complementary color filter.
The micro lens 112 is a lens for preventing or suppressing color mixing, and is disposed on the incident side of the color filter 113. It can also be said that the color filter 113 is disposed between the microlens 112 and the photoelectric conversion unit 114. The microlens 112 has a plurality of lens portions 112 a corresponding to the red filters R, the green filters G, and the blue filters B. Each lens unit 112a collects light so that light enters the corresponding filter correctly. The photoelectric conversion unit 114 can be efficiently irradiated by the micro lens 112.

The reinforcing glass 111 is provided to ensure the strength of the image sensor 110. Specifically, the reinforcing glass 111 is disposed on the incident side of the microlens 112. The reinforcing glass 111 is bonded and fixed to the microlens 112 with a resin 115.
As described above, the light incident on the image sensor 110 passes through the reinforcing glass 111, the resin 115, the microlens 112, the color filter 113, and the photoelectric conversion unit 114 in order. Part of the transmitted light from the photoelectric conversion unit 114 is converted into electric charges, and the remaining transmitted light passes between the circuit unit 118 and the back mask 117 and enters the reflection unit 120.
(2) Reflection unit The reflection unit 120 is a unit for reflecting the transmitted light of the image sensor 110 toward the image sensor 110, and is a kind of MEMS (Micro Electro Mechanical Systems). In the present embodiment, the reflection unit 120 is configured by a so-called DMD (Digital Micromirror Device). Specifically, as shown in FIGS. 3 and 4, the reflection unit 120 includes a plurality of movable mirrors 121 (an example of a reflection optical element) and a drive unit 125 that drives the plurality of movable mirrors 121. Yes.

The plurality of movable mirrors 121 are arranged in a matrix and reflect light transmitted through the photoelectric conversion unit 114 toward the photoelectric conversion unit 114. The movable mirror 121 is a square plate made of a metal such as aluminum and has a reflecting surface 121a. Each movable mirror 121 is disposed so as to be able to receive light transmitted through the four photoelectric conversion elements 119. Each movable mirror 121 is disposed so as to face the emission surface of the photoelectric conversion unit 114 across the circuit unit 118 in a direction orthogonal to the light receiving surface 119a (a direction parallel to the optical axis AZ).
As shown in FIGS. 3 to 5, in the present embodiment, one movable mirror 121 is disposed so as to correspond to four photoelectric conversion elements 119. In addition, one movable mirror 121 is arranged so as to correspond to one unit region Q (two green filters G, one red filter R, and one blue filter B arranged diagonally) of the color filter 113. ing. That is, one movable mirror 121 is arranged for four pixels.

The plurality of movable mirrors 121 are arranged in a matrix at the first pitch P1. On the other hand, the plurality of photoelectric conversion elements 119 are arranged in a matrix at the second pitch P2. Here, the first pitch P1 means the interval between the centers of the movable mirror 121, and the second pitch P2 means the interval between the centers of the photoelectric conversion elements 119. In the present embodiment, the first pitch P1 is set to be larger than the second pitch P2, and is twice the second pitch P2.
The drive unit 125 is a kind of MEMS (Micro Electro Mechanical Systems) manufactured by a semiconductor manufacturing process, and the angle of each movable mirror 121 with respect to the photoelectric conversion unit 114 can be individually changed. The drive unit 125 is disposed on the opposite side of the plurality of movable mirrors 121 from the photoelectric conversion unit 114. The drive unit 125 includes a CMOS substrate 124 and a plurality of actuators 126 provided on the CMOS substrate 124.

  Each actuator 126 is provided for each movable mirror 121. As shown in FIG. 4, the actuator 126 can hold the movable mirror 121 in the first state E1 and the second state E2. As shown in FIG. 4, in the first state E1, the reflecting surface 121a of the movable mirror 121 is parallel to the light receiving surface 119a, and in the second state E2, the reflecting surface 121a of the movable mirror 121 is predetermined with respect to the light receiving surface 119a. In this state, it is inclined by an angle (for example, 10 degrees). In the first state E1, all or most of the transmitted light of the photoelectric conversion element 119 is reflected by the movable mirror 121 and reenters the transmitted photoelectric conversion element 119 from the back surface. On the other hand, as shown in FIG. 4, in the second state E2, a part of the transmitted light of the photoelectric conversion element 119 is blocked by the back mask 117 and the mask 118b of the circuit unit 118, and reappears in any photoelectric conversion element 119. Not incident. Thus, since the re-incident light amount in the second state E2 is smaller than the re-incident light amount in the first state E1, when the light amount is large, by holding the movable mirror 121 in the second state E2, The total amount of light incident on the photoelectric conversion element 119 can be reduced.

Furthermore, the driving speed of the actuator 126 is very high, and only about 10 [μsec] is required to switch from the first state E1 to the second state E2. Therefore, by adjusting the ratio of the first state E1 and the second state E2 per unit time while driving the movable mirror 121 at a high speed, the reflectance at each movable mirror 121 is adjusted separately and substantially in a stepless manner. can do. For example, by storing the relationship between the reflectance and the drive pattern of the actuator 126 in advance in the ROM 10b of the body controller 10, the drive pattern of the actuator 126 can be calculated based on the reflectance. The reflectance of each movable mirror 121 is set by a reflectance setting unit 51g described later.
It should be noted that the driving angle of the actuator 126 may be adjusted in multiple steps or steplessly by analog control.

  As shown in FIGS. 3 to 5, the actuator 126 includes a hinge portion 128, a pair of support portions 127, a yoke 122, and a pair of electrodes 123. The hinge portion 128 is an elongated plate-like portion, and both ends are supported by a pair of support portions 127. A movable mirror 121 is fixed to the yoke 122. The electrode 123 generates an electrostatic attractive force for driving the yoke 122. Each electrode 123 is disposed on the CMOS substrate 124. When a voltage is supplied to the electrode 123 via the CMOS substrate 124, an electrostatic attractive force is generated between the electrode 123 and the yoke 122. The end portion of the yoke 122 is attracted toward the electrode 123 by the electrostatic attraction, and the movable mirror 121 is held in the second state E2. When no voltage is supplied to the electrode 123, the movable mirror 121 is held in the first state E1 due to the rigidity of the hinge portion 128. By turning on and off the voltage supply at high speed, the movable mirror 121 can be driven at high speed, and the reflectance at the movable mirror 121 can be adjusted as described above.

The CMOS substrate 124 supports a plurality of actuators 126 and is provided so that a voltage can be separately supplied to each electrode 123. The CMOS substrate 124 is made of a semiconductor material and is disposed substantially in parallel with the photoelectric conversion unit 114. The CMOS substrate 124 and the image sensor 110 are mounted on a package (not shown) with a predetermined interval maintained.
<Body controller>
As shown in FIG. 2, the body controller 10 includes a luminance calculation unit 51f, a selection unit 51b, a saturated pixel detection unit 51c, a charge deficient pixel detection unit 51e, a reflectance setting unit 51g, and a drive control unit 51a. And a focusing calculation unit 54. Each of these units represents a functional block realized by a program. Each of these functional blocks may be realized by software, hardware, and a combination of software and hardware.

The luminance calculation unit 51f calculates the average luminance of each unit region Q (4 pixels) based on the image data. Each average luminance calculated by the luminance calculation unit 51f is temporarily stored in the RAM 10a together with the coordinate information.
The selection unit 51b selects the highest average luminance as the maximum luminance Bmax from the plurality of average luminances calculated by the luminance calculation unit 51f. The maximum luminance Bmax selected by the selection unit 51b is temporarily stored in the RAM 10a together with the coordinate information. The selection unit 51b selects the lowest average luminance as the minimum luminance Bmin from the plurality of average luminances calculated by the luminance calculation unit 51f. The minimum brightness Bmin selected by the selection unit 51b is temporarily stored in the RAM 10a together with the coordinate information. When there are a plurality of unit regions Q having the highest luminance Bmax, or when there are a plurality of unit regions Q having the lowest luminance Bmin, the highest luminance Bmax and the lowest luminance Bmin are stored in the RAM 10a together with each coordinate information. The

The saturated pixel detection unit 51c determines whether or not the maximum luminance Bmax selected by the selection unit 51b is within a predetermined range (first upper limit luminance B1max to first lower limit luminance B1min). If the maximum luminance Bmax is within a predetermined range, the high luminance side of the dynamic range is maintained at an appropriate level. Here, the first upper limit luminance B1max is set to a value smaller than the maximum value of the gradation that can be expressed by the image data generated by the image sensor 110. When the maximum brightness Bmax is higher than the first upper limit brightness B1max, it can be determined that there is a high possibility that the incident light amount of the four photoelectric conversion elements 119 corresponding to the maximum brightness Bmax is large and the charge is saturated. Further, the first lower limit luminance B1min is set to a value smaller than the first upper limit luminance B1max.
The charge deficient pixel detection unit 51e determines whether or not the minimum luminance Bmin selected by the selection unit 51b is within a predetermined range (second upper limit luminance B2max to second lower limit luminance B2min). If the minimum luminance Bmin is within a predetermined range, the low luminance side of the dynamic range is maintained at an appropriate level. Here, the second lower limit luminance B2min is set to a value larger than the minimum gradation value that can be expressed by the image data generated by the image sensor 110. When the minimum luminance Bmin is lower than the second lower limit luminance B2min, it can be determined that there is a high possibility that the amount of incident light of the four photoelectric conversion elements 119 corresponding to the minimum luminance Bmin is small and the charge is insufficient. Further, the second upper limit luminance B2max is set to a value larger than the second lower limit luminance B2min.

When the saturation pixel detection unit 51c determines that the maximum luminance Bmax is higher than the first upper limit luminance B1max, the reflectance setting unit 51g sets the reflectance of the movable mirror 121 corresponding to the maximum luminance Bmax to the minimum value (minimum reflectance). Rmin). The reflectance setting unit 51g sets the reflectance of the movable mirror 121 corresponding to the minimum luminance Bmin to the maximum value (when the minimum luminance Bmin is determined to be lower than the second lower limit luminance B2min by the insufficient charge pixel detection unit 51e. Maximum reflectance Rmax).
Further, the reflectance setting unit 51g calculates the reflectance of each movable mirror 121 in the unit region Q other than the unit region Q corresponding to the highest luminance Bmax and the unit region Q corresponding to the lowest luminance Bmin. Specifically, the reflectivity setting unit 51g determines the maximum brightness Bmax, the minimum brightness Bmin, the reflectivity of the unit area Q corresponding to the maximum brightness Bmax, and the reflectivity of the unit area Q corresponding to the minimum brightness Bmin. The reflectance corresponding to the average luminance of the unit region Q is calculated. In the present embodiment, the reflectance is calculated by the reflectance setting unit 51g using linear interpolation.

Here, the reflectance represents the proportion of light that re-enters the photoelectric conversion element 119 per unit time in the reflected light of the movable mirror 121. As described above, the movable mirror 121 can be held in the two states of the first state E1 and the second state E2 by the actuator 126 of the drive unit 125. Therefore, the reflectance can be adjusted by switching the first state E1 and the second state E2 at high speed and changing the ratio of the first state E1 and the second state E2 per unit time. For example, the reflectance in the first state E1 is about 100%, and the reflectance in the second state E2 is about 10%.
Even when the concept of reflectance is not actively used, the reflectance is set if time-division intensity modulation is performed by high-speed switching of the movable mirror 121.
The drive control unit 51a controls each actuator 126 according to the reflectance set or calculated by the reflectance setting unit 51g. The ROM 10b stores in advance a drive pattern of the movable mirror 121 corresponding to the reflectance. Based on this drive pattern, the drive controller 51a individually controls each actuator 126 of the reflection unit 120 according to the reflectance of each movable mirror 121 set by the reflectance setting unit 51g.

The focus calculation unit 54 calculates the position of the focus lens L corresponding to the focus state based on the image data. Specifically, the focus calculation unit 54 calculates an AF evaluation value from the image data, and uses the calculated AF evaluation value to obtain the position of the focus lens L corresponding to the in-focus state by a so-called hill climbing method.
<Operation>
The operation of the digital camera 1 will be described with reference to FIGS. 6 and 7 show an operation flowchart at the time of still image shooting.
As shown in FIG. 6, for example, when the digital camera 1 is switched to a shooting mode such as a live view mode, the reflection unit 120 is reset (step S1). Specifically, the reflectance of all the movable mirrors 121 is set to the maximum value in the reflectance setting unit 51g so that all the movable mirrors 121 are set to the first state E1. As a result, each actuator 126 is controlled by the drive control unit 51a, and the movable mirror 121 is in the first state E1. At this time, the reflectance of each movable mirror 121 is temporarily stored in the RAM 10a of the body controller 10 together with the coordinate information.

  Next, image data is acquired by the image sensor 110 (step S2). Specifically, the charge of the image sensor 110 is once discharged, and the shutter unit 33 is driven by the shutter control unit 31. Specifically, the shutter unit 33 is driven so that the image sensor 110 is exposed for a predetermined exposure time. Light enters each photoelectric conversion element 119 by an amount corresponding to the exposure time. Light transmitted through the photoelectric conversion element 119 reenters the photoelectric conversion element 119 from the back surface by the movable mirror 121. The photoelectric conversion element 119 accumulates electric charges according to the amount of incident light, and the electric charge of each photoelectric conversion element 119 is output from the imaging element 110 to the image processing unit 11 via the circuit unit 118 as an electric signal. In the image processing unit 11, predetermined processing is performed on the electrical signal output from the image sensor 110 to generate image data. The generated image data is temporarily stored in the buffer memory 16. In the live view mode, this image data is displayed on the liquid crystal monitor 20, for example, as a visible image.

After the image data is acquired, the average luminance of each unit region Q (more specifically, the average luminance of four pixels) is calculated by the luminance calculation unit 51f based on the image data (step S3). Each average luminance is temporarily stored in the RAM 10a together with the coordinate information.
Next, the highest average luminance is selected from the plurality of average luminances as the maximum luminance Bmax by the selection unit 51b (step S4). The selected maximum luminance Bmax is temporarily stored in the RAM 10a together with the coordinate information. Also, the lowest average luminance is selected from the plurality of average luminances as the minimum luminance Bmin by the selection unit 51b (step S5). The selected minimum luminance Bmin is temporarily stored in the RAM 10a together with the coordinate information.
Further, the saturated pixel detection unit 51c determines whether or not the selected maximum luminance Bmax is within a predetermined range (first upper limit luminance B1max to first lower limit luminance B1min). Specifically, the saturated pixel detection unit 51c compares the maximum brightness Bmax with a preset first upper limit brightness B1max (step S6). When the maximum brightness Bmax is higher than the first upper limit brightness B1max, it can be determined that the amount of incident light in the unit region Q corresponding to the maximum brightness Bmax is so large that the charge amount of the photoelectric conversion element 119 is saturated. Therefore, the reflectance at the movable mirror 121 corresponding to the maximum luminance Bmax is set to the minimum value by the reflectance setting unit 51g (see step S7A, FIG. 8B). Specifically, the minimum reflectance Rmin stored in advance in the ROM 10b is temporarily stored in the RAM 10a together with the coordinate information as a new reflectance. When there are a plurality of unit areas Q corresponding to the maximum luminance Bmax, the minimum reflectance Rmin is temporarily stored in the RAM 10a as a new reflectance together with the coordinate information of the unit areas Q.

On the other hand, when the maximum brightness Bmax is equal to or less than the first upper limit brightness B1max, it can be determined that the amount of incident light in the unit region Q corresponding to the maximum brightness Bmax is not so large that the charge of the photoelectric conversion element 119 is saturated. In this case, the saturated pixel detection unit 51c compares the maximum luminance Bmax with the preset first lower limit luminance B1min (step S7B). When the maximum brightness Bmax is equal to or higher than the first lower limit brightness B1min, the current reflectance at the movable mirror 121 corresponding to the maximum brightness Bmax is used as it is. When the maximum brightness Bmax is smaller than the preset first lower limit brightness B1min, the reflectance of the movable mirror 121 corresponding to the maximum brightness Bmax is increased at a predetermined rate, and the increased reflectance becomes a new reflectance. It is stored in the RAM 10a (see step S8, FIG. 8A).
By steps S6, S7A, S7B, and S8, the maximum luminance Bmax is easily maintained within a predetermined range (first upper limit luminance B1max to first lower limit luminance B1min).

  Similarly to the maximum luminance Bmax, the insufficient charge pixel detection unit 51e determines whether or not the selected minimum luminance Bmin is within a predetermined range (second upper limit luminance B2max to second lower limit luminance B2min). The selected minimum luminance Bmin is compared with the preset second lower limit luminance B2min by the charge-deficient pixel detection unit 51e (step S9). When the minimum luminance Bmin is lower than the second lower limit luminance B2min, it can be determined that the amount of incident light in the unit region Q corresponding to the minimum luminance Bmin is too small. Therefore, the reflectance at the movable mirror 121 corresponding to the lowest luminance Bmin is set to the maximum value (see step S10A, FIG. 8B). Specifically, the maximum reflectance Rmax preset in the ROM 10b is temporarily stored in the RAM 10a together with the coordinate information as a new reflectance. When there are a plurality of unit areas Q corresponding to the minimum luminance Bmin, the maximum reflectance Rmax is temporarily stored in the RAM 10a together with the coordinate information of the unit areas Q.

On the other hand, when the minimum luminance Bmin is equal to or higher than the second lower limit luminance B2min, it can be determined that the amount of incident light of the four pixels corresponding to the minimum luminance Bmin is not too small. In this case, the minimum luminance Bmin is compared with the preset second upper limit luminance B2max by the insufficient charge pixel detection unit 51e (step S10B). When the minimum luminance Bmin is equal to or higher than the second upper limit luminance B2max, the current reflectance at the movable mirror 121 corresponding to the four pixels with the minimum luminance Bmin is used as it is. When the minimum brightness Bmin is larger than the preset second upper limit brightness B2max, the reflectivity of the movable mirror 121 corresponding to the four pixels of the minimum brightness Bmin is decreased at a predetermined rate, and the decreased reflectivity is new. The reflectance is stored in the RAM 10a (see step S11, FIG. 8A).
By steps S9, S10A, S10B, and S11, the minimum luminance Bmin is easily maintained within a predetermined range (second upper limit luminance B2max to second lower limit luminance B2min).

Further, in the unit region Q other than the unit region Q corresponding to the highest luminance Bmax and the unit region Q corresponding to the lowest luminance Bmin, the reflectance of each movable mirror 121 is calculated by the reflectance setting unit 51g (step S12). Specifically, based on the reflectance of the unit region Q corresponding to the highest luminance Bmax, the lowest luminance Bmin, and the highest luminance Bmax and the reflectance of the unit region Q corresponding to the lowest luminance Bmin, the reflectance setting unit 51g The reflectance Rx corresponding to the average luminance Bx is calculated by, for example, linear interpolation (see FIGS. 8A and 8B). In the present embodiment, the reflectance Rx is calculated based on the alternate long and short dash line shown in FIGS. 8 (A) and 8 (B). The calculated reflectance Rx is temporarily stored in the RAM 10a together with the coordinate information of the unit region Q.
After calculating the reflectance, each movable mirror 121 is driven by the drive unit 125 based on the calculated reflectance (step S13). Specifically, each actuator 126 is controlled by the drive control unit 51a, and the switching between the first state E1 and the second state E2 of the movable mirror 121 is executed according to the reflectance. As a result, the maximum luminance Bmax and the minimum luminance Bmin are easily maintained within a predetermined range, and the dynamic range is adjusted using the reflection unit 120.

Here, the effects obtained by the processing from step S6 to step S13 will be described in detail with reference to FIGS. 8A and 8B.
As shown in FIG. 8A, when the maximum brightness Bmax is smaller than the first lower limit brightness B1min and the minimum brightness Bmin is greater than the second upper limit brightness B2max, the reflectance Rx and the average brightness of each movable mirror 121 are obtained. The relationship with Bx can be expressed as a solid line. Maximum brightness Bmax can be expressed by point P11, and minimum brightness Bmin can be expressed by point P21. As described above, when the maximum brightness Bmax is smaller than the first lower limit brightness B1min, the reflectance of the movable mirror 121 corresponding to the maximum brightness Bmax increases, and when the minimum brightness Bmin is greater than the second upper limit brightness B2max, the lowest The reflectivity of the movable mirror 121 corresponding to the brightness Bmin decreases (steps 7B and S8). Therefore, as shown in FIG. 8A, before driving the movable mirror 121, the point R11 moves to the point R12, and the point R21 moves to the point R22. That is, when the reflectance Rx is calculated by linear interpolation in step S12, the relationship between the average luminance Bx and the reflectance Rx stored in the RAM 10a can be expressed by a one-dot chain line.

Furthermore, when the movable mirror 121 is driven in step S13, the maximum luminance Bmax increases with an increase in reflectance, and the minimum luminance Bmin decreases with a decrease in reflectance. That is, after driving the movable mirror 121, it can be expected that the point R12 moves to the point R13 and the point R22 moves to the point R23. Therefore, for example, after the movable mirror 121 is driven, the relationship between the actual average brightness and the reflectance is as shown by the broken line in FIG. 8A, and the dynamic range is maintained at an appropriate level by the above processing. I understand that.
Further, as shown in FIG. 8B, when the maximum luminance Bmax is larger than the first upper limit luminance B1max and the minimum luminance Bmin is smaller than the second lower limit luminance B2min, the reflectance Rx of each movable mirror 121 is The relationship with the average luminance Bx can be expressed as a solid line. The maximum luminance Bmax can be expressed by a point T11, and the minimum luminance Bmin can be expressed by a point T21. As described above, when the maximum brightness Bmax is larger than the first upper limit brightness B1max, the reflectivity of the movable mirror 121 corresponding to the maximum brightness Bmax is set to the minimum reflectivity Rmin (steps S6 and S7A), and the minimum brightness Bmin is set. If it is smaller than the second lower limit luminance B2min, the reflectance of the movable mirror 121 corresponding to the lowest luminance Bmin is set to the maximum reflectance Rmax (steps S9 and S10A). Therefore, as shown in FIG. 8B, before the movable mirror 121 is driven, the point T11 moves to the point T12, and the point T21 moves to the point T22. That is, when the reflectance Rx is calculated by linear interpolation in step S12, the relationship between the average luminance Bx and the reflectance Rx stored in the RAM 10a can be expressed by a one-dot chain line.

Furthermore, when the movable mirror 121 is driven in step S13, the maximum luminance Bmax decreases with the reflectance set to the minimum reflectance Rmin, and the minimum with the reflectance set to the maximum reflectance Rmax. The luminance Bmin increases. That is, after driving the movable mirror 121, it can be expected that the point T12 moves to the point T13 and the point T22 moves to the point T23. Therefore, for example, after the movable mirror 121 is driven, the relationship between the actual average brightness and the reflectance is as shown by the broken line in FIG. 8B, and the dynamic range is maintained at an appropriate level by the above processing. I understand that.
In addition, when performing HDR (High Dynamic Range) imaging, in addition to the above control, the reflectance of each movable mirror 121 may be set so that each pixel is properly exposed based on the luminance information of each pixel. Good.

After the movable mirror 121 is driven, the state of the release button 30 is monitored by the body controller 10 (step S14). Steps S2 to S13 are repeated until the release button 30 is pressed halfway. On the other hand, when the half-pressing operation of the release button 30 is detected by the body controller 10, a shooting preparation operation such as photometric processing or focusing is started (step S15).
Here, there are various types of metering methods such as center-weighted metering, spot metering, and split metering.Normally, the charge amount of each pixel is weighted according to the metering method so that appropriate exposure is obtained. Made. The term “appropriate exposure” as used herein refers to a state in which charge saturation or charge shortage does not occur in the photometry area corresponding to the selected photometry method. Since the dynamic range is maintained at an appropriate level using the reflection unit 120 in steps S3 to S13, so-called whiteout (Blown out highlights) and blackout (Blocked up shadows) can be suppressed, and the accuracy of photometric processing can be improved. The image quality of the captured image can be improved.

In focusing, AF is performed by a so-called contrast detection method. However, since the dynamic range is maintained at an appropriate level, an improvement in AF accuracy can be expected.
After the shooting preparation operation, the state of the release button 30 is monitored by the body controller 10 (step S16). Specifically, when the body controller 10 detects that the release button 30 is fully pressed, the image sensor 110 acquires image data at the calculated shutter speed, and after the image data is subjected to predetermined processing, The subsequent image data is recorded in the image recording unit 18 (steps S17 and S18). After recording the image, the process is repeated from step S2.
If the half-press is released without the release button 30 being fully pressed, the process returns to step S2 (step S19).

<Features>
(1) As described above, in this imaging element unit 100, the transmitted light of each photoelectric conversion element 119 is reflected by the movable mirror 121 to the photoelectric conversion unit 114, so that the total amount of light incident on the photoelectric conversion element 119 And the light receiving sensitivity of the image sensor 110 for the same amount of incident light can be increased. In addition, since the angle of the plurality of movable mirrors 121 with respect to the photoelectric conversion unit 114 can be individually changed by the drive unit 125, the amount of reflected light incident on each photoelectric conversion element 119 can be adjusted for each movable mirror 121. it can.
Therefore, the image sensor unit 100 can suppress charge saturation while increasing the light receiving sensitivity of the image sensor 110.

(2) In this image sensor unit 100, since the circuit unit 118 is disposed between the photoelectric conversion element 119 and the reflection unit 120, light can enter the photoelectric conversion element 119 without being blocked by the circuit unit 118. It has become. Therefore, the aperture ratio is increased as compared with the case where the circuit unit is disposed on the incident side of the photoelectric conversion element 119 (that is, the surface irradiation type imaging element), and as a result, the light receiving sensitivity of the imaging element 110 can be increased. . Further, by combining the back-illuminated imaging device 110 with the reflection unit 120, the light receiving sensitivity of the imaging device 110 can be further increased, and shooting can be performed even in a shooting environment with a small amount of light such as at night.
(3) Further, since the circuit unit 118 is disposed between the photoelectric conversion element 119 and the reflection unit 120, the transmitted light of the photoelectric conversion element 119 is reflected by the movable mirror 121 and enters the adjacent photoelectric conversion element 119. Can be suppressed. Further, since the lattice-like back mask 117 is disposed between the separation region and the plurality of movable mirrors 121, the transmitted light of the photoelectric conversion element 119 is reflected by the movable mirror 121 and reappears to the adjacent photoelectric conversion element 119. The incident can be prevented. With these configurations, it is possible to prevent the accuracy of luminance information obtained from each photoelectric conversion element 119 from being reduced due to the provision of the reflection unit 120.

(4) Since one movable mirror 121 is arranged so as to be able to receive the transmitted light of the four photoelectric conversion elements 119, the number of movable mirrors 121 can be reduced, calculation for driving the reflection unit 120, and the like. Can be reduced. That is, in the image sensor unit 100, the light receiving sensitivity of the image sensor 110 can be increased by the reflection unit 120 while suppressing a reduction in processing speed.
(5) As described above, with the digital camera 1 having the image sensor unit 100, high sensitivity and wide dynamic range shooting is possible.
<Other embodiments>
Embodiments of the present invention are not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit of the present invention. The above-described embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

(1) In the above-described embodiment, the operation of the image sensor unit 100 is described taking still image shooting as an example, but the image sensor unit 100 can be used not only for still image shooting but also for moving image shooting. That is, with the image sensor unit 100, HDR (High Dynamic Range) images can be acquired in still image and moving image shooting.
In addition, as an imaging device in which the imaging device unit 100 is mounted, for example, a digital still camera (including a lens interchangeable digital camera), a digital video camera, a camera-equipped mobile phone, a camera-equipped PDA, and a surveillance camera can be obtained. Devices are possible.
(2) In the above-described embodiment, one movable mirror 121 is arranged so as to be able to receive the light transmitted through the four photoelectric conversion elements 119. However, the correspondence between the movable mirror 121 and the photoelectric conversion element 119 is as described above. The form is not limited. For example, the movable mirror 121 and the photoelectric conversion element 119 may be disposed on a one-to-one basis, or one movable mirror 121 may be disposed so as to be able to receive light transmitted through two photoelectric conversion elements 119. Furthermore, one movable mirror 121 may be arranged so as to be able to receive the transmitted light of five or more photoelectric conversion elements 119. When the movable mirror 121 and the photoelectric conversion element 119 are arranged on a one-to-one basis, the first pitch P1 is the same as the second pitch P2.

(3) In the above-described embodiment, since one movable mirror 121 is disposed so as to be able to receive the transmitted light of the four photoelectric conversion elements 119, the dynamic range using the reflection unit 120 based on the average luminance of the four pixels is used. However, the dynamic range may be expanded based on the luminance of one pixel. Further, for example, the calculation may be performed on the basis of the average luminance of two pixels corresponding to the green filter G among the four pixels in the unit region Q.
(4) In the above-described embodiment, the dynamic range expansion process is performed on the entire image data. However, for example, the same process may be performed on a specific area. For example, a dynamic range expansion process may be performed on a specific area of the image data in combination with the face recognition technique. In this case, whiteout of a part of the subject's face (eg cheek) can be suppressed or prevented. In backlight photography, it is also possible to increase the brightness of a person while suppressing the brightness of a bright part of the background.

In addition, when taking pictures at night with a surveillance camera, using a normal image sensor unit reduces the overall exposure due to the effects of light emitting signs and flashlights held by suspicious individuals, and the target subject tends to be dark. It is. However, with this image sensor unit 100, even in such a case, the function as a surveillance camera can be sufficiently achieved by reducing the reflectance of the movable mirror 121 corresponding to a bright region.
(5) The operation flowchart shown in FIGS. 6 and 7 is merely an example for explaining the operation of the image sensor unit 100, and the operation of the image sensor unit 100 is not limited to the flow chat shown in FIGS. For example, although the reflectance at the movable mirror 121 corresponding to the maximum brightness Bmax is set to the minimum reflectance Rmin in step S7A, a process of reducing the reflectance at a specific ratio may be used. Further, in step S10A, the reflectance at the movable mirror 121 corresponding to the minimum luminance Bmin is set to the maximum reflectance Rmax, but a process of increasing the reflectance at a specific ratio may be used.

In the above-described embodiment, the processes in steps S6 to S11 are performed so that the maximum luminance Bmax and the minimum luminance Bmin are within a predetermined range. However, if only the processes in steps S6 and S7A are performed, charge saturation is performed. Can be suppressed.
Specifically, the process is performed so that the maximum brightness Bmax is within a predetermined range (for example, the first upper limit brightness B1max to the first lower limit brightness B1min), but the processes in steps S7B and S8 are omitted. Also good. Even in this case, the processing is performed so that the maximum luminance Bmax is equal to or lower than the first upper limit luminance B1max, so that the charge saturation in the photoelectric conversion unit 114 can be suppressed.
Similarly, in the above-described embodiment, the process is performed so that the minimum luminance Bmin is within a predetermined range (for example, the second upper limit luminance B2max to the second lower limit luminance B2min), but steps S10B and S11 are omitted. May be. Even in this case, since the process is performed so that the minimum luminance Bmin is equal to or higher than the second lower limit luminance B2min, the shortage of electric charge in the photoelectric conversion unit 114 can be suppressed.

  The technique described above is useful in the field of imaging devices because charge saturation can be suppressed while increasing the light receiving sensitivity.

1 Digital camera (an example of an imaging device)
10 Body controller (an example of control unit)
51a Drive control unit 51b Selection unit 51c Saturated pixel detection unit 51e Charge-deficient pixel detection unit 51f Luminance calculation unit 51g Reflectivity setting unit 100 Image sensor unit 110 Image sensor 111 Reinforcement glass 112 Micro lens 113 Photoelectric conversion unit 114 Color filter 116 Separation region 117 Back mask (an example of a light shielding part)
118 Circuit Unit 119 Photoelectric Conversion Element 119a Light Receiving Surface 120 Reflecting Unit 121 Movable Mirror (Example of Reflecting Optical Element)
122 Yoke 123 Electrode 124 CMOS substrate 125 Drive unit 126 Actuator 127 Support part 128 Hinge part

Claims (15)

A photoelectric conversion unit having a plurality of photoelectric conversion elements arranged in a matrix and converting light into electric charges, and a light receiving surface formed by the plurality of photoelectric conversion elements and receiving incident light;
A plurality of reflective optical elements that are arranged in a matrix and reflect the light transmitted through the photoelectric conversion unit toward the photoelectric conversion unit;
A drive unit capable of individually changing an angle of each of the reflective optical elements with respect to the photoelectric conversion unit;
An image sensor unit comprising: Each of the reflective optical elements is disposed so as to be able to receive the transmitted light of at least one of the photoelectric conversion units,
The image sensor unit according to claim 1. Each of the reflective optical elements is disposed at a position capable of receiving light transmitted through two or more of the photoelectric conversion elements.
The image sensor unit according to claim 1. The plurality of reflective optical elements are arranged in a matrix at a first pitch,
The plurality of photoelectric conversion elements are arranged in a matrix at a second pitch,
The first pitch is the same as the second pitch or larger than the second pitch.
The image sensor unit according to claim 1. The drive unit is disposed on the opposite side of the photoelectric conversion units of the plurality of reflective optical elements,
The image sensor unit according to claim 1. Further comprising a Bayer color filter disposed on the opposite side of the photoelectric conversion unit from the reflective optical element,
The imaging device unit according to claim 1. A circuit unit that is disposed between the photoelectric conversion unit and the plurality of reflective optical elements and further transmits the electric charges generated by the photoelectric conversion elements;
The imaging device unit according to claim 1. A grid-like separation region disposed between the plurality of photoelectric conversion elements;
A lattice-shaped light shielding portion disposed between the separation region and the plurality of reflective optical elements,
The image sensor unit according to claim 1. The reflective optical element and the drive unit include MEMS (Micro Electro Mechanical Systems),
The image sensor unit according to claim 1. The reflective optical element and the drive unit include a DMD (Digital Micromirror Device),
The image sensor unit according to claim 1. The image sensor unit according to any one of claims 1 to 10,
An image processing unit that performs predetermined processing on the electrical signal generated by the imaging element unit to generate image data;
A control unit that controls the drive unit based on the image data generated by the image processing unit;
An imaging apparatus provided. The drive unit has a plurality of actuators that individually drive the reflective optical elements,
The control unit individually controls the plurality of actuators based on the image data.
The imaging device according to claim 11. The control unit includes a luminance calculation unit that calculates luminance data corresponding to each reflective optical element from the image data, a selection unit that selects the highest luminance from the luminance data calculated by the luminance calculation unit, and the highest A reflectivity setting unit that sets the reflectivity of the reflective optical element corresponding to the brightness based on the maximum brightness,
The imaging device according to claim 11 or 12. The control unit includes a drive control unit that controls the actuator based on the reflectance set by the reflectance setting unit.
The imaging device according to claim 13. The reflectance setting unit newly sets the reflectance so that the reflectance at the reflective optical element corresponding to the highest brightness is reduced when the highest brightness is higher than a reference brightness.
The imaging device according to claim 13 or 14.

Images