JP6470589B2 - IMAGING DEVICE, ITS CONTROL METHOD, PROGRAM, AND STORAGE MEDIUM - Google Patents

Description

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

  In an imaging apparatus such as a digital camera that performs imaging using a solid-state imaging element such as a CMOS or a CCD, an imaging element having a structure in which an imaging surface is curved has been proposed in order to correct lens aberration (see Patent Document 1). ). As in Patent Document 1, it is possible to make the imaging plane orthogonal to the light beam from the subject incident from the lens by curving the imaging plane of the imaging device.

Japanese Patent No. 4604307

  However, as in Patent Document 1, if the imaging surface of the imaging device is curved, there is a possibility of affecting the peripheral circuits of the pixels. In the peripheral circuit of the image sensor, circuit elements are stacked on a flat substrate. Some circuit elements have characteristics that change depending on the interval and shape of the components that make up the element. Therefore, design characteristics may not be obtained if the peripheral circuit is deformed by curving the image sensor.

  The present invention has been made in view of the above problems, and an object thereof is to realize a technique capable of appropriately controlling a force applied to an image sensor in accordance with a change in characteristics of the image sensor and peripheral circuits during image capturing. .

In order to solve the above-described problems and achieve the object, an imaging device according to the present invention includes an imaging device including a readout circuit in which a plurality of pixels are arranged two-dimensionally and reads a signal accumulated in the pixels, and the imaging element stress is generated on, wherein when the drive means Ru is curved imaging surface, in accordance with the signal reading characteristics of the reading circuit in which the imaging surface is changed by bending, performs the signal accumulation operation of the image sensor And control means for controlling the driving means so that the stress received by the image sensor becomes larger than the stress received by the image sensor when performing a signal reading operation of the image sensor.

In addition, an imaging device according to the present invention includes an imaging device including a readout circuit that reads out signals accumulated in the plurality of pixels in a two-dimensional manner, and a driving unit that curves the imaging surface of the imaging device. wherein when in accordance with a signal reading characteristics of the reading circuit in which the imaging surface is changed by bending, the curvature of the imaging surface in the case of performing the signal accumulation operation of the image pickup device performs a signal read operation of the imaging device Control means for controlling the driving means so as to be larger than the curvature of the imaging surface .

  ADVANTAGE OF THE INVENTION According to this invention, the stress which an image pick-up element receives according to the change of the characteristic of an image pick-up element or a peripheral circuit can be controlled appropriately.

1 is a block diagram illustrating a configuration of an imaging apparatus according to an embodiment. FIG. 3 is a circuit diagram showing an electrical configuration of the image sensor of the present embodiment. The figure which shows the structure of the stress control part of this embodiment. Explanatory drawing of the capacitance characteristic of the image sensor of this embodiment. Explanatory drawing of the column amplifier circuit of the image pick-up element of this embodiment. 5 is a flowchart at the time of normal image capturing according to the first embodiment. 3 is a timing chart at the time of normal image capturing according to the first embodiment. 9 is a flowchart at the time of capturing a shaded image for blackening processing according to the second embodiment. 9 is a timing chart at the time of capturing a shaded image for blackening processing according to the second embodiment.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention with reference to an accompanying drawing is demonstrated in detail. The embodiment described below is an example for realizing the present invention, and should be appropriately modified or changed according to the configuration and various conditions of the apparatus to which the present invention is applied. It is not limited to the embodiment. Moreover, you may comprise combining suitably one part of each embodiment mentioned later.

  [Embodiment 1] An embodiment in which the present invention is applied to an image pickup apparatus such as a digital camera capable of taking a still image or a moving image will be described below. The present invention can also be applied to other devices having a function capable of controlling the bending of the imaging surface by applying a force to the imaging element to generate a bending stress.

  <Apparatus Configuration> With reference to FIG. 1, an outline of a configuration and functions of an imaging apparatus according to an embodiment of the present invention will be described.

  In FIG. 1, the imaging apparatus of the present embodiment includes an optical system 101, an imaging element 102, an imaging control unit 103, a preprocessing unit 104, a signal processing unit 105, a memory unit 106, a display unit 107, a recording unit 108, and an operation unit 109. The main control unit 110 and the stress control unit 111 are included.

  The optical system 101 includes a focus lens that forms a subject image on the image sensor 102, a zoom lens that optically zooms, a diaphragm that adjusts the brightness of the subject image, a mechanical shutter that controls exposure (hereinafter referred to as a shutter), and the like. Including.

  The image sensor 102 includes a plurality of pixels arranged in a two-dimensional manner and a circuit that reads signals read from these pixels in a predetermined order.

  The imaging control unit 103 operates in accordance with a control signal from the main control unit 110, and drives each element of the optical system 101 and the imaging element 102 by supplying a pulse with enhanced constant voltage and driving capability. Further, the imaging control unit 103 switches the readout mode of the imaging element 102 to a normal image shooting mode and a black-drawing shooting mode, which will be described later, based on a control signal from the main control unit 110.

  The preprocessing unit 104 operates in accordance with a control signal from the main control unit 110, and a correlated double sampling circuit (CDS circuit) that removes noise components such as reset noise included in the output signal of the image sensor 102 that is an analog signal. It includes a gain control amplifier that adjusts the amplitude of the output signal from which noise has been removed, an A / D conversion circuit that converts the output signal, which is an analog signal whose amplitude has been adjusted, into a digital signal, and the like. Note that these components included in the preprocessing unit 104 may be incorporated in the image sensor 102.

  The signal processing unit 105 operates in accordance with a control signal from the main control unit 110, performs color conversion processing, gamma correction processing, defective pixel correction processing, and the like on the digital signal output from the preprocessing unit 104, and performs compression processing. To generate image data. The signal processing unit 105 outputs image data to the memory unit 106 and the recording unit 108 and performs predetermined signal processing on the image data read from the memory unit 106 and the recording unit 108. Further, the signal processing unit 105 has a function of detecting photometric data such as an in-focus state and an exposure amount from a signal from the image sensor 102 and outputting the photometric data to the main control unit 110.

  The memory unit 106 temporarily stores a digital signal output from the preprocessing unit 104 and image data output from the signal processing unit 105 based on a control signal from the main control unit 110. In addition, the signal processing unit 105 outputs display image data to the display unit 107.

  The display unit 107 uses, for example, an electronic viewfinder (EVF) or a liquid crystal display (LCD), and displays display image data stored in the memory unit 106 based on a control signal from the main control unit 110. While viewing the image displayed on the display unit 107, the user can determine the composition before shooting and confirm the image after shooting.

  The recording unit 108 records image data output from the signal processing unit 105 based on a control signal from the main control unit 110 or outputs already recorded image data. The recording unit 108 may be a memory card or a hard disk drive mounted on the imaging apparatus, or may be a flash memory or a hard disk drive built in the imaging apparatus. Further, the same configuration as that of the memory unit 106 described above may be used.

  The operation unit 109 is an operation unit that receives a user operation for inputting various instructions to the imaging apparatus 100, and includes various operation units such as a physical operation member such as a button or a switch, or an on-screen input unit through a touch panel. Forms are available. The operation unit 109 includes, for example, a menu switch for performing various settings at the time of image shooting and playback, a zoom lever for instructing a zoom operation, a switch for switching an operation mode such as a shooting mode and a playback mode, a shutter switch, and a power switch. Including. The main control unit 110 controls the imaging device based on instructions and settings input by the user via the operation unit 109, and displays setting information, operation states, images, and the like on the display unit 107.

  The main control unit 110 includes a CPU, a main memory (RAM), an input / output circuit, a timer circuit, and the like. The CPU expands the program stored in the memory unit 106 in the RAM work area and executes the program, thereby Control overall operation. Note that the main memory and the memory unit 106 may have the same configuration.

  In response to an instruction from the operation unit 109, the main control unit 110 controls the optical system 101 in accordance with photometric data such as an in-focus state and an exposure amount obtained by the signal processing unit 105, so that an optimal subject image is obtained. An image is formed on the image sensor 102. Further, a control signal is output to the stress control unit 111 according to an instruction from the operation unit 109 or a predetermined photographing condition, and an external force is applied to the image sensor 102 to generate a predetermined stress. Further, the main control unit 110 can monitor the usage status of the memory unit 106 and the recording unit 108.

  The stress control unit 111 operates in response to a control signal from the main control unit 110, applies a force to the image sensor 102 to generate a bending stress as described later, and curves the imaging surface.

  The operation of the imaging apparatus according to the present embodiment is performed as follows.

<Control of display image>
(1) The power is turned on by an instruction from the power switch of the operation unit 109.

  (2) The signal processing unit 105 converts the output signal from the image sensor 102 into image data for display, displays the image data on the display unit 107, detects photometric data, and outputs it to the main control unit 110.

  (3) The main control unit 110 controls the optical system 101 based on the photometric data.

  (4) Repeat (2) and (3) and wait for an instruction from the operation unit 109.

<Control of still image shooting>
(1) Still image shooting control is started by an instruction from the shooting switch of the operation unit 109.

  (2) The signal processing unit 105 detects photometric data from the output signal from the image sensor 102 and outputs it to the main control unit 110.

  (3) The main control unit 110 controls the optical system 101 based on the photometric data.

  (4) The image sensor 102 performs exposure for recording a still image and outputs a signal.

  (5) The signal processing unit 105 converts the output signal from the image sensor 102 into image data for recording, outputs it to the recording unit 108, records it, and converts it into image data for display. 107.

  (6) Return to display image control.

  <Image Sensor> Next, the detailed configuration of the image sensor 102 of the present embodiment will be described with reference to FIG.

  FIG. 2 is a circuit diagram showing an electrical configuration of the image sensor 102 of the present embodiment. In FIG. 2, for simplification of explanation, only the unit pixels 201 are shown as 4 rows × 4 columns, but in reality, a large number of unit pixels 201 are two-dimensionally arranged.

  In FIG. 2, a unit pixel 201 includes a photodiode (PD) 202, a transfer switch 203, a floating diffusion (FD) 204, an amplification MOS amplifier 205 that functions as a source follower, a selection switch 206, and a reset switch 207. Light is converted into electric charge in the PD 202, and the electric charge generated in the PD 202 is transferred from the PD 202 to the FD 204 by applying the transfer signal φTX to the transfer switch 203 and temporarily stored in the FD 204. A floating diffusion amplifier is configured by the FD 204, the amplification MOS amplifier 205, and the constant current source 209 serving as a load of the amplification MOS amplifier 205. Then, by applying the selection signal φSEL, the selection switch 206 is turned on, the signal charge accumulated in the FD 204 of the selected pixel is converted into a voltage, and is output to the readout circuit 213 via the signal output line 208. . Further, the horizontal scanning circuit 214 outputs a selection signal to the selection signal line 210 to select a signal to be output from the reading circuit 213, and the selected output signal is output from the image sensor 102 via the output amplifier 211. Is output. The charge accumulated in the FD 204 is removed by applying a reset signal φRES to the reset switch 207. The vertical scanning circuit 212 performs driving to selectively turn on / off the transfer switch 203, the selection switch 206, and the reset switch 207.

  <Stress Control Unit> Next, the configuration of the stress control unit 111 for applying a force to the image sensor 102 will be described with reference to FIG.

  As a method for applying force to the image sensor 102, there is a method using magnetic force or negative pressure. In the present embodiment, a stress control mechanism that applies a tensile force to the image sensor 102 using a negative pressure of gas or liquid will be described.

  FIG. 3 shows a cross-sectional configuration of the image sensor 102 to which the stress control mechanism is connected. 3A shows a state where no force is applied to the image sensor 102, and FIG. 3B shows a state where a force is applied to the image sensor 102.

  3A, the image sensor 102 includes a pixel chip portion 301, a holding portion 302, a lid portion 303, a space portion 304, and a suction portion 305. The pixel chip portion 301 of the image sensor 102 has an imaging region (imaging surface) in which unit pixels 201 are two-dimensionally arranged in the central portion, and a semiconductor substrate having the circuit portions 209 to 215 in FIG. 2 in the peripheral portion. It is. The holding unit 302 holds the pixel chip unit 301 in a bendable state. The lid part 303 is joined to the holding part 302. The space portion 304 is a sealed space surrounded by the pixel chip portion 301, the holding portion 302, the lid portion 303, and the suction portion 305, and is filled with gas or liquid.

  The suction unit 305 can discharge a gas or liquid medium from the space 304 to the outside, or can introduce the medium into the space 304. That is, the medium in the space 304 is taken in and out through the suction part 305.

  By controlling the amount of medium introduced into and discharged from the space portion 304, the pressure in the space portion 304 can be changed to control the force applied to the pixel chip portion 301 (that is, the stress received by the pixel chip portion 301). it can.

  In the state of FIG. 3A, since the suction part 305 does not generate a negative pressure with respect to the space part 304, no bending stress is generated in the pixel chip part 301. At this time, the stress received by the pixel chip unit 301 is F0, and in this embodiment, control is performed so that the signal reading operation of the image sensor 102 is performed in this state. FIG. 3B shows a state where the bending stress is generated in the pixel chip portion 301 by sucking and discharging the medium in the space portion 304 by the suction portion 305 from the state where the bending stress is zero.

  In FIG. 3B, the pixel chip portion 301 is bent and deformed and bent like the pixel chip portion 301 ′ by applying a downward suction force to the pixel chip portion 301.

  At this time, a predetermined bending stress is generated in the pixel chip portion 301 ′ in FIG. At this time, the stress received by the pixel chip unit 301 is F1, and in this embodiment, control is performed so that the signal storage operation of the image sensor 102 is performed in this state.

  <Photoelectric Conversion Characteristics of Image Sensor> Next, the photoelectric conversion characteristics of the image sensor 102 will be described with reference to FIG.

  As shown in FIG. 4A, the FD 204 included in each unit pixel 201 of the image sensor 102 includes a positive electrode 401, a negative electrode 402, an anode plate 403, and a cathode plate 404. A capacitor C is provided that can store a charge Q when a voltage V is applied between the positive electrode 401 and the negative electrode 402.

  The parameters for determining the capacitance C [F] are the electrode plate distance d [m], the electrode plate area S [m 2] where the anode plate 403 and the cathode plate 404 overlap, and the dielectric constant ε of the electrode plate dielectric 406. .

  The capacity C at this time is obtained from Equation 1.

C = ε × S / d (1)
Next, a change in photoelectric conversion characteristics when the capacitance C of the FD 204 is deformed due to stress applied to the imaging element will be described with reference to FIG.

  When the negative pressure in the space 304 is changed from the no-load state of FIG. 3A to the state of FIG. 3B by the suction unit 305, the pixel chip unit 301 is bent like a pixel chip unit 301 '. At this time, since the electrode plate area S changes, the capacitance C of the FD 204 of each pixel of the pixel chip unit 301 changes, and the capacitance C ′ of the FD 204 of each pixel of the pixel chip unit 301 ′ differs from that of the pixel chip unit 301. Indicates a different value.

  FIG. 4B shows a state in which bending stress is generated from the state of FIG. 4A, and the anode plate 403 and the cathode plate 404 are deformed to become the anode plate 403 ′ and the cathode plate 404 ′. Yes.

  Parameters for determining the capacitance C ′ [F] of the FD 204 of the pixel chip portion 301 ′ are the electrode plate distance d ′ [m], and the electrode plate area S ′ [m2] where the anode plate 403 ′ and the cathode plate 404 ′ overlap. The dielectric constant ε of the interelectrode dielectric 406 ′ (same as the dielectric constant ε of the interelectrode dielectric 406).

  The capacitance C ′ at this time is obtained from Equation 2.

C ′ = ε × S ′ / d ′ (2)
At this time, Equation 3 is obtained, and C and C ′ have the relationship of Equation 4.

S / d ≠ S ′ / d ′ (3)
C ≠ C '(4)
As described above, the imaging element 102 according to the present embodiment has a characteristic in which the FD capacitance of the pixel portion varies due to bending deformation, and the photoelectric conversion characteristics change.

  <Peripheral Circuit Characteristics of Image Sensor> Next, the characteristics of the column amplifier circuit constituting the peripheral circuit of the image sensor 102 of this embodiment will be described with reference to FIG.

  FIG. 5 is a circuit diagram of a column amplifier included in the read circuit 213 of FIG.

  The column amplifier includes a differential amplifier circuit 501, capacitors C0, C1, and C2, and transistors Tr1 and Tr2.

  A constant voltage Vref is input to the differential amplifier circuit 501 as a reference voltage.

  The pixel signal output from the pixel unit 201 is input to the input terminal Vin. The pixel signal amplified by the differential amplifier circuit 501 is output from the output terminal Vout.

  The amplification factor of the differential amplifier circuit 501 is determined by the input capacitor C0. Capacitors C1 and C2 are feedback capacitors of the differential amplifier circuit 501.

  Depending on the state of the control lines G1 and G2, the transistors Tr1 and Tr2 are connected or disconnected, and the feedback capacitors C1 and C2 are selectively connected to switch the amplification factor of the differential amplifier circuit 501.

  Here, the operation of the column amplifier of FIG. 5 will be described.

  The column amplifier can switch the amplification factor by a combination of the input capacitor C0 and the feedback capacitors C1 and C2.

  For example, when the transistor Tr1 is disconnected by the control lines G1 and G2 and the transistor Tr2 is connected, the capacitor C1 does not function as a feedback capacitor, and the capacitor C2 becomes a feedback capacitor. In this case, the output voltage Vout1 of the output terminal Vout is obtained from Equation 5.

Vout1 = (Vref−Vin) × (C1 / C0) (5)
Further, when the transistor Tr1 is connected and the transistor Tr2 is disconnected, the capacitor C1 serves as a feedback capacitor, and the capacitor C2 does not function as a feedback capacitor.

  In this case, the output voltage Vout2 of the output terminal Vout is obtained from Equation 6.

Vout2 = (Vref−Vin) × (C2 / C0) (6)
For example, when C1 = 2 × C0 and C2 = 4 × C0, the output voltage Vout1 is an output with a double amplification factor, and Vout2 is an output with a fourfold amplification factor.

  The column amplifier having the above-described configuration requires capacity accuracy.

  As can be seen from the above formulas 5 and 6, the capacitance ratio between the capacitor C0 and the capacitor C1 and between the capacitor C0 and the capacitor C2 is related to the amplification factor of the input voltage Vin.

  On the other hand, when bending stress is generated in the image pickup element 102 and deformed, the capacitances of the input capacitance C0 and the feedback capacitances C1 and C2 constituting the column amplifier are the same as the capacitance of the FD 204 described with reference to FIGS. The value also changes. For this reason, if the capacitance value of the input capacitor C0 and the capacitance values of the feedback capacitors C1 and C2 change at different rates, it becomes impossible to obtain a designed amplification factor.

  In the above example, when the image sensor 102 is not deformed, C1 = 2 × C0 and C2 = 4 × C0 hold. However, when the image sensor 102 is deformed and the stress changes, C1 ≠ 2 × C0, C2 ≠ 4 × C0. In this case, the amplification factor of the output voltage Vout1 is twice and the amplification factor of the output voltage Vout2 is four times.

  Similarly, if there is a variation in capacitance inside the image sensor, such as when the amplification factor is different between the center and the periphery of column amplifiers arranged in the horizontal direction, the input voltage of each column varies with the amplification factor for each column amplifier. Vin will be amplified.

  In the present embodiment, the force applied to the image sensor at the time of image capturing is appropriately controlled in consideration of the change in the capacitance of the pixel portion of the image sensor and the change in the characteristics of the peripheral circuit resulting therefrom.

  <Stress Control of Image Sensor> Next, with reference to FIGS. 6 and 7, the stress control process of the image sensor 102 at the time of normal image capturing of this embodiment will be described.

  In the present embodiment, during normal image capturing, a force is applied to the image sensor 102 to generate a bending stress so that the peripheral circuit of the image sensor 102, such as the readout circuit 213 in FIG. 2, operates as designed, Control is performed to curve the imaging surface.

  Specifically, the force applied to the image sensor 102, that is, the stress applied to the image sensor 102, is changed between when the signal storage operation of the image sensor 102 is performed and when the signal read operation is performed. In this embodiment, in order to improve the photoelectric conversion characteristics of the pixel unit when performing the signal accumulation operation, a force is applied so that the stress received by the image sensor 102 becomes F1, and when performing the signal readout operation, Control is performed so that the stress applied to the image sensor 102 is F0 so that the peripheral circuit operates as designed without changing the capacitance (the bending stress is zero). In other words, control is performed so that the stress that the image sensor 102 receives when performing the signal accumulation operation (that is, the curvature of the imaging surface of the image sensor 102) is larger than the stress (curvature) that is received when the signal read operation is performed.

  As described above, during normal image shooting, by performing different stress control when performing signal accumulation operation of the image sensor 102 and when performing signal readout operation, photoelectric conversion characteristics of the image sensor and The peripheral circuit characteristics can be appropriately changed.

  FIG. 6 is a flowchart showing stress control processing of the image sensor 102 during normal image capturing.

  In the following, the processing when the stress received by the image sensor 102 when performing the signal accumulation operation is F1 and the stress received by the image sensor 102 when performing the signal readout operation is F0 will be described. Is not limited to this example.

  The process shown in FIG. 6 is realized by the main control unit 110 and the stress control unit 111 working together, and the CPU of the main control unit 110 developing the program read from the memory unit 106 and executing it in the main memory. The The same applies to the processing of FIG.

  In step S <b> 601, the main control unit 110 controls the suction unit 305 of the stress control unit 111 to apply a force for performing a signal accumulation operation to the image sensor 102 to generate the bending stress F <b> 1 and bend the imaging surface. Thus, an image with reduced curvature of field is formed on the imaging surface of the imaging element 102 with appropriate photoelectric conversion characteristics. In this case, design peripheral circuit characteristics cannot be obtained due to deformation of the imaging surface of the image sensor 102.

  In step S602, the main control unit 110 controls the imaging control unit 103 to open the shutter.

  In step S603, the main control unit 110 controls the image capturing control unit 103 to perform batch reset processing of the image sensor 102 and starts exposure.

  In step S604, the main control unit 110 controls the imaging control unit 103 to close the shutter and end the exposure. Here, the exposure is ended by the shutter closing operation, but when the global shutter circuit is mounted on the image sensor 102, the exposure end processing may be performed by the global shutter reading operation.

  In step S605, the main control unit 110 controls the suction unit 305 of the stress control unit 111 so that no force is applied to the image sensor 102, and the bending stress is set to F0 (= zero). Thereby, the curvature of the image sensor 102 is eliminated, and the designed peripheral circuit characteristics can be obtained when the signal reading operation is performed.

  In step S <b> 606, the main control unit 110 controls the imaging control unit 103 to perform a signal reading operation from the imaging element 102.

  FIG. 7 shows a timing chart from a signal accumulation operation to a signal readout operation during normal image capturing.

  The stress control signal φSt is a signal for the stress control unit 111 to drive and control the suction unit 305. The suction unit 305 is driven and controlled so that a bending stress F1 is generated in the image sensor 102 when the stress control signal φSt is High and the bending stress of the image sensor 102 is F0 when the stress control signal φSt is Low.

  The shutter control signal φSh is a signal for the imaging control unit 103 to drive and control the shutter. When the shutter control signal φSh is High, the shutter is opened, and when the shutter control signal φSh is Low, the shutter is closed.

  The reset control signal φRES is a signal for the imaging control unit 103 to switch the reset switch 207 on and off. The reset switch 207 is connected to reset the FD 204 when High, and the reset switch 207 is disconnected when Low.

  The transfer control signal φTXn is a signal for the imaging control unit 103 to switch on / off of the transfer switch 203. When the transfer control signal φTX is High, the transfer switch 203 is connected to transfer the signal of the PD 202 to the FD 204, and when it is Low, the transfer switch 203 is turned on. Disconnect.

  The selection control signal φSELn is a signal for the imaging control unit 103 to switch the selection switch 206 on and off. When the selection control signal φSELn is High, the selection switch 206 is connected and the signal of the FD 204 is amplified by the amplification MOS amplifier 205 and output. In this case, the selection switch 206 is disconnected.

  Note that the reset control signal φRES, the transfer control signal φTXn, and the selection control signal φSELn exist in each row as shown in FIG. For example, the transfer control signal φTX in the first row is φTX1, the transfer control signal φTX in the second row is φTX2,. . . The transfer control signal φTX in the nth row becomes φTXn.

  In the image sensor 102 of the present embodiment, since the readout circuit 213 performs a signal readout operation for each row, the transfer control signal φTX and the selection control signal φSEL are controlled for each row.

  The timing of each operation in FIG. 7 will be described.

  Time t701 corresponds to the timing at which a force is applied when performing a signal accumulation operation on the image sensor 102 in step S601 of FIG.

  Time t702 corresponds to the timing at which the shutter is opened in step S602 in FIG.

  Time t703 corresponds to the start timing of the process of simultaneously resetting the PDs 202 in all rows in step S603 in FIG.

  Time t704 corresponds to the timing when the batch reset process in step S603 in FIG. 6 ends and exposure is started.

  Time t705 corresponds to the timing when the shutter is closed in step S604 in FIG.

  Time t706 corresponds to the timing at which control is performed so that no force is applied to the image sensor 102 in step S605 of FIG.

  After time t707, this corresponds to the signal read operation for each row in step S606 of FIG.

  At time t707, the transfer switch 203 in the first row is connected, and the pixel signal of the PD 202 is transferred to the FD 204.

  At time t708, the transfer switch 203 in the first row is disconnected, and the pixel signal transfer of the PD 202 in the first row is stopped.

  At time t709, the signal read operation for the first row is executed.

  At time t710, the signal reading operation for the first row is finished.

  At time t711, the transfer switch 203 in the second row is connected, and the pixel signal of the PD 202 in the second row is transferred to the FD 204.

  At time t712, the transfer switch 203 in the second row is disconnected, and the pixel signal transfer of the PD 202 is stopped.

  At time t713, the signal read operation for the second row is executed.

  At time t714, the signal reading operation for the second row is finished.

  After time t715, the same processing is performed for each row.

  At time t715, the transfer switch 203 in the n-th row is connected, and the pixel signal of the n-th row PD 202 is transferred to the FD 204.

  At time t716, the transfer switch 203 in the n-th row is disconnected, and the pixel signal transfer of the PD 202 is stopped.

  At time t717, the signal reading operation on the nth row is executed.

  At time t718, the signal reading operation on the nth row is finished.

  According to the first embodiment described above, by performing different stress control in the case of performing the signal accumulation operation of the image sensor 102 and in the case of performing the signal read operation during normal image capturing, the image sensor is adjusted in accordance with the image capturing operation. Photoelectric conversion characteristics and peripheral circuit characteristics can be appropriately changed.

  [Embodiment 2] Next, the stress control processing of the image sensor 102 during normal image shooting and black drawing processing image shooting in Embodiment 2 will be described.

  In the first embodiment described above, stress control during normal image capturing has been described. On the other hand, in the second embodiment, a stress control process at the time of capturing a light-shielded image for blackening processing will be described. The blacking process is a second image captured by shading from a first image (exposure image) captured with normal exposure in order to remove fixed pattern noise such as dark current noise caused by the image sensor 102. This is a correction process for subtracting (a black image or a light-shielded image).

  It is desirable to perform a signal reading operation on the blackout shading image under the same conditions as the exposure image. This is because, if the conditions for the exposure image and the light-shielded image are different, the fixed pattern noise of the exposure image cannot be read correctly by the light-shielded image. Therefore, it is necessary to perform stress control during the signal accumulation operation and the signal read operation under the same conditions as during the exposure image capturing process even during the blackout shading image capturing process.

  FIG. 8 is a flowchart showing stress control processing of the image sensor 102 at the time of normal image shooting and at the time of black shooting image shooting.

  Steps S801 to S806 are normal exposure image capturing processes similar to steps S601 to S606 in FIG.

  Steps S807 to S810 are a stress control sequence at the time of capturing a light-shielded image for blackening processing, but differ from that at the time of capturing an exposed image in that stress control and signal accumulation / readout operations are performed in the shutter closed state. .

  In step S <b> 807, the main control unit 110 controls the suction unit 305 of the stress control unit 111 to apply a force for performing a signal accumulation operation to the image sensor 102 to generate the bending stress F <b> 1 and bend the imaging surface. Thereby, the signal accumulation operation of the light-shielded image can be performed under the same conditions as when the exposure image was captured.

  In step S808, the main control unit 110 controls the image capturing control unit 103 to perform batch reset processing of the image sensor 102 and starts a signal accumulation operation.

  In step S809, the main control unit 110 controls the suction unit 305 of the stress control unit 111 so that no force is applied to the image sensor 102, and the bending stress is set to F0 (= zero). As a result, the image sensor 102 is not curved, and the signal reading operation of the light-shielded image can be performed under the same conditions as when the exposure image is captured.

  In step S810, the main control unit 110 controls the imaging control unit 103 to perform a signal read operation from the imaging element 102.

  Thereafter, the main control unit 110 executes blacking processing using the exposure image read in step S806 and the light-shielded image read in step S810.

  FIG. 9 shows a timing chart from signal accumulation operation to signal readout operation at the time of exposure image shooting and light-shielded image shooting.

The control signals in FIG. 9 are the same as those in FIG. In addition, since the exposure image capturing process from time t901 to time t918 is similar to that from time t701 to time t718 in FIG. 7, the description is omitted. At time t919, the signal storage operation is performed on the image sensor 102 in step S <b> 807 in FIG. 8. Corresponds to the timing of applying force when performing.

  Time t920 corresponds to the start timing of the process of simultaneously resetting the PDs 202 in all rows in step S808 in FIG.

  Time t921 corresponds to the timing at which the batch reset process in step S808 in FIG. 8 ends and the signal accumulation operation starts.

  Time t922 corresponds to the timing at which control is performed so that no force is applied to the image sensor 102 in the processing of step S809 in FIG.

  After time t923, this corresponds to the signal read operation for each row in step S810 of FIG.

  At time t923, the transfer switch 203 in the first row is connected, and the pixel signal of the PD 202 is transferred to the FD 204.

  At time t924, the transfer switch 203 in the first row is disconnected and the pixel signal transfer of the PD 202 in the first row is stopped.

  At time t925, a signal read operation for the first row is executed.

  At time t926, the signal reading operation for the first row is finished.

  At time t927, the transfer switch 203 in the second row is connected, and the pixel signal of the PD 202 in the second row is transferred to the FD 204.

  At time t928, the transfer switch 203 in the second row is disconnected, and the pixel signal transfer of the PD 202 is stopped.

  At time t929, the signal read operation for the second row is executed.

  At time t930, the signal reading operation for the second row is finished.

  After time t931, the same processing is performed for each row.

  At time t931, the transfer switch 203 in the n-th row is connected, and the pixel signal of the n-th row PD 202 is transferred to the FD 204.

  At time t932, the transfer switch 203 in the n-th row is disconnected, and the pixel signal transfer of the PD 202 is stopped.

  At time t933, the signal reading operation on the n-th row is executed.

  At time t934, the signal reading operation on the nth row is finished.

  According to the above-described second embodiment, even when a light-shielded image for blackening processing is captured, different stress control is performed depending on whether the signal accumulation operation is performed or the signal readout operation is performed as in the exposure image capturing. By doing so, it is possible to appropriately change the photoelectric conversion characteristics and the peripheral circuit characteristics of the imaging device in accordance with the imaging operation.

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

DESCRIPTION OF SYMBOLS 102 ... Imaging device 103 ... Imaging control part 104 ... Pre-processing part 105 ... Signal processing part 106 ... Memory part 110 ... Main control part 111 ... Stress control part

Claims (10)

An imaging device including a readout circuit in which a plurality of pixels are arranged in a two-dimensional manner and reads out signals accumulated in the pixels ;
The imaging element stress is generated, the driving means Ru is curved imaging surface,
When the signal receiving operation of the image sensor performs the signal read operation of the image sensor when performing the signal accumulation operation of the image sensor in accordance with the signal readout characteristics of the readout circuit that change due to the imaging surface being curved. Control means for controlling the drive means so as to be greater than the stress experienced by the image sensor;
An imaging device comprising:   The imaging apparatus according to claim 1, wherein the control unit controls the driving unit so that a stress applied to the imaging element is zero when the signal reading operation is performed. An imaging device including a readout circuit in which a plurality of pixels are arranged in a two-dimensional manner and reads out signals accumulated in the pixels ;
Driving means for bending the imaging surface of the imaging element;
Wherein when in accordance with a signal reading characteristics of the reading circuit in which the imaging surface is changed by bending, the curvature of the imaging surface in the case of performing the signal accumulation operation of the image pickup device performs a signal read operation of the imaging device Control means for controlling the drive means so as to be larger than the curvature of the imaging surface ;
An imaging device comprising: A shutter for controlling exposure to the image sensor;
4. The control unit according to claim 1, wherein the control unit performs control so that the shutter is opened when the signal accumulation operation is performed, and the shutter is closed when the signal read operation is performed. The imaging apparatus of Claim 1. The control means executes a first imaging process for exposing the imaging element to capture a first image, and a second imaging process for capturing a second image in a state where the imaging element is shielded from light,
5. The control unit according to claim 1, wherein the driving unit performs control so as to perform the same control on the image sensor during the first imaging process and the second imaging process. 6. The imaging device according to item.   6. The imaging according to claim 5, further comprising processing means for correcting the first image obtained by the first imaging process using the second image obtained by the second imaging process. apparatus. Drive means, a plurality of pixels are arranged two-dimensionally, wherein to generate a stress to the imaging device including a reading circuit for reading the accumulated signal to the pixel, and a driving step of Ru is curved imaging surface,
When the control means performs a signal accumulation operation of the image sensor in accordance with the signal readout characteristic of the readout circuit that changes as the imaging surface is curved, the stress that the image sensor receives is a signal readout operation of the image sensor. A control step of controlling the driving means so as to be larger than the stress that the image sensor receives when performing
A method for controlling an imaging apparatus, comprising: A driving step in which a driving unit is configured to bend an imaging surface of an imaging element including a readout circuit in which a plurality of pixels are arranged two-dimensionally and read out signals accumulated in the pixels ;
Control means, in response to the signal reading characteristics of the reading circuit in which the imaging surface is changed by bending, the curvature of the imaging surface in the case of performing the signal accumulation operation of the image pickup device a signal read operation of the imaging device A control step of controlling the driving means so as to be larger than the curvature of the imaging surface when performing;
A method for controlling an imaging apparatus, comprising:   The program for functioning a computer as each means of the imaging device described in any one of Claims 1 thru | or 6.   A computer-readable storage medium storing a program for causing a computer to function as each unit of the imaging apparatus according to any one of claims 1 to 6.

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