JP2007329803A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of controlling exposure even when an illumination part for illuminating an object, especially an illumination part for emitting a flash such as flash light, is used and capable of reducing noise caused by a dark current and obtaining a fine image. <P>SOLUTION: Since a light shielding member is applied to the surfaces of pixels of an imaging element and the shielding of incident light to a photoelectrical conversion part is controlling by moving the light shielding member, the imaging apparatus capable of controlling exposure even when the illumination part for emitting a flash such as flash light is used, reducing noise caused by a dark current and obtaining file images can be provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus including an illumination unit that illuminates a subject and a light shielding member that covers a photoelectric conversion unit on an imaging element.

  Conventionally, a CCD (Charge Coupled Device) type image sensor has been used for an image sensor such as a digital camera or a camera module for a mobile phone. On the other hand, recently, CMOS (Complementary Metal Oxide Semiconductor) type image sensors are often used because smear and blooming, which are disadvantages of CCD type image sensors, are less likely to occur and the power supply voltage may be low. It is coming.

  In a CMOS type image sensor, incident light is converted into electric charges by a photoelectric conversion unit arranged in a pixel to obtain a video signal. As the photoelectric conversion unit, for example, a photo MOS gate or a photodiode is used, and it has a structure for accumulating charges generated by light incidence for a certain exposure time. The corresponding image signal is output.

  Since the amount of charge that can be accumulated is finite, when strong light is incident, the charge is saturated and an appropriate output signal cannot be obtained. In order to prevent this, if the light incidence is limited by optical means such as a filter or a diaphragm, the accumulated charge amount is too small for the weak light incidence, and the output signal is buried in the surrounding noise, so it is appropriate Can not obtain a stable output signal.

  That is, the CMOS image sensor has an incident light amount range (dynamic range; hereinafter referred to as D range) in which an appropriate output signal can be obtained. The range is generally narrower than the D range (usually called latitude) of a silver salt film. Therefore, the required accuracy of exposure control in a CMOS image sensor is stricter than that of a silver salt film.

  In particular, when flash light is used as a means for illuminating a subject, the flash time of the flash light is as short as a few microseconds at the maximum, so exposure variation using a normal mechanical aperture or shutter causes variations in exposure. It is large and it is difficult to obtain the exposure accuracy required by the CMOS image sensor.

  Therefore, in a CMOS image sensor, an electronic shutter is used for exposure control of flash light (see, for example, Patent Document 1). By using the electronic shutter, the exposure can be completed during the short flash time of the flash light, and the exposure accuracy required by the CMOS image sensor can be obtained.

On the other hand, with the advancement of micromachine technology, a light-shielding mask that shields a part of the opening of each pixel is provided on the pixel of the image sensor, and the position of the light-shielding mask is switched using a microactuator to capture images multiple times. A method for increasing the resolution without increasing the number has been proposed (see, for example, Patent Document 2).
JP 2001-320627 A JP-A-8-163449

  However, as will be described in detail later with reference to FIG. 3 and FIG. 4, when the exposure of flash light is controlled using an electronic shutter as in the method described in Patent Document 1, the obtained image signal is output. In other words, noise due to dark current is superimposed on the signal, resulting in a problem that a good image cannot be obtained.

  The method of Patent Document 2 controls the light shielding amount only by increasing the resolution by switching the opening position in time series by changing the light shielding position relative to the opening of the pixel of the light shielding mask. It is not a proposal for exposure control.

  The present invention has been made in view of the above circumstances, and exposure control is possible even when an illuminating unit that illuminates a subject, particularly an illuminating unit that emits flash light such as flash light, is good with less noise due to dark current. An object of the present invention is to provide an imaging device capable of obtaining a clear image.

  The object of the present invention can be achieved by the following constitution.

1. An image sensor in which pixels having a photoelectric conversion unit are two-dimensionally arranged;
A light shielding member for shielding all or a part of incident light to the photoelectric conversion unit, wherein at least one side of the pixel row is arranged in the arrangement direction of a pixel and a pixel adjacent to the pixel row A light-shielding device including the light-shielding member in which light-shielding pieces shorter than the distance to the row are connected to each other at an end, and a light-shielding drive unit for moving the position of the light-shielding member on the photoelectric conversion unit In the provided imaging device,
An illumination unit that illuminates the subject;
An imaging apparatus comprising: an imaging control unit configured to control a light shielding operation of all or part of incident light to the photoelectric conversion unit performed by the light shielding member in association with light emission of the illumination unit.

  2. The imaging apparatus according to 1, wherein the imaging control unit controls a light shielding operation of the light shielding member in synchronization with light emission of the illumination unit.

  3. The imaging apparatus according to 1, wherein the imaging control unit controls a light shielding amount of the light shielding member in synchronization with light emission of the illumination unit.

  According to the present invention, an illumination unit that emits flash light such as flash light by providing a light shielding member on a pixel of an image sensor and controlling the light shielding of incident light to the photoelectric conversion unit by moving the light shielding member. It is possible to provide an image pickup apparatus that can control exposure even when using, and can obtain a good image with less noise due to dark current.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol shows the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  First, the configuration of the imaging apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating an internal configuration of the imaging apparatus. In FIG. 1, the imaging apparatus 1 includes an operation unit 111, a control unit 151, an imaging unit 160, a lens 211, a lens driving unit 221, an illumination unit 141, a photometry unit 171, a display unit 131, a recording medium 191, and the like. .

  The imaging unit 160 includes an imaging control unit 161, an imaging element 162, an analog / digital converter (hereinafter referred to as an A / D converter) 164, an image processing unit 165, a light shielding control unit 167, a light shielding device 162x, and the like. . The light shielding device 162x is provided on the imaging surface of the imaging element 162, and controls the shielding of light incident on the imaging element 162 from the lens 211. The operation of the light shielding device 162x is controlled by a light shielding device control signal MS output from the light shielding control unit 167 under the control of the imaging control unit 161.

  The imaging signal Vs of the imaging element 162 is converted into digital data by the A / D converter 164, subjected to predetermined processing by the image processing unit 165, and input to the imaging control unit 161 as image data 165a. The operation 160 is controlled by the imaging control unit 161 under the control of the control unit 151. The image data 165a input to the imaging control unit 161 is recorded on a recording medium 191 configured by, for example, a memory card via the control unit 151, and a display configured by, for example, a liquid crystal display panel or the like as necessary. Displayed on the part 131.

  The operation unit 111 is used for input of start and end of various operations such as imaging, image recording, and image display of the imaging apparatus 1 and input of various settings such as an imaging mode and a recording mode. 151 is input. The illumination unit 141 includes, for example, a xenon tube and a flash circuit, and the light emission is controlled by the control unit 151.

  The photometry unit 171 includes, for example, a light receiving element and a photometry circuit. The photometry unit 171 measures light from a subject including flash light under the control of the control unit 151 and inputs a photometric signal to the control unit 151. Here, the photometric unit 171 is illustrated as a so-called external light type photometric unit that directly measures light from a subject, but may be a so-called TTL type photometric unit that measures light from a subject that has passed through the lens 211. . The control unit 151 controls all the various operations described above.

  Next, the configuration of the imaging element 162 used in the imaging apparatus 1 will be described with reference to FIG. FIG. 2 is a block diagram showing the internal configuration of the image sensor 162. In FIG. 2, an image pickup device 162 is a CMOS type image pickup device. On the image pickup surface 162a, a plurality of pixels 162b, a vertical scanning circuit 162c, a sample hold circuit 162d, and an output arranged in a matrix form in the horizontal and vertical directions are output. A circuit 162e, an output amplifier 162g, a horizontal scanning circuit 162f, a timing generator 162h, and the like are arranged, and the horizontal scanning arrangement of the pixels 162b and the vertical scanning circuit 162c are connected by a row selection line 162i, and each vertical column of the pixel 162b. Each arrangement and the sample hold circuit 162d are connected by a vertical signal line 162j.

  Here, the sample hold circuit 162d includes two capacitors (not shown) for each vertical signal line 162j. In the driving method of the image sensor 162 described later with reference to FIGS. The so-called CDS (Correlated Double Sampling) operation is performed, in which the image signal Vout including the noise is held, the noise signal Vnoise of each pixel is held in the other capacitor, and the difference between them is taken, and the noise is removed.

  The imaging operation of the imaging device 162 is controlled by the timing generator 162h according to the imaging control signal 161a from the imaging control unit 161, and the imaging signal Vs that is the output of the imaging device 162 is input to the A / D converter 164.

  Next, the configuration of the pixel 162b of the imaging element 162 will be described with reference to FIG. FIG. 3 is a circuit diagram illustrating an example of the configuration of the pixel 162b. In FIG. 3, the pixel 162b includes a photodiode PD functioning as a photoelectric conversion unit and four N-channel MOS transistors (hereinafter referred to as transistors) Q1 to Q4. The photodiode PD is preferably a buried photodiode from the viewpoint of reducing noise. Here, VDD is a power supply potential, GND is a ground potential, reset signal φRST, transfer signal φTX, and pixel output signal φV are control signals for driving each transistor.

  Light incident on the pixel 162b is photoelectrically converted by the photodiode PD to be converted into a photocurrent Ip, and is stored as a photoelectric charge Qp in the parasitic capacitance Cp. The transistor Q1 is called a transfer gate, and is controlled by a transfer signal φTX input to the gate terminal thereof to completely transfer the photocharge Qp accumulated in the parasitic capacitance Cp of the photodiode PD to the floating diffusion FD. The transferred photocharge Qp is held in the floating diffusion FD and becomes an optical signal Vp.

  The transistor Q2 is called a reset gate, and is controlled by a reset signal φRST input to its gate terminal to reset the potential Vfd of the floating diffusion FD to the power supply potential VDD. Reset noise Vrn remains in the reset floating diffusion FD. The transistor Q3 forms a source follower circuit, and lowers the impedance of the potential Vfd (= Vp or Vrn) of the floating diffusion FD connected to the gate terminal thereof.

  The transistor Q4 is called a row selection transistor, and is controlled by the pixel output signal φV input to the row selection line 162i to which the gate terminal is connected, and the potential Vfd (=) of the floating diffusion FD whose impedance is lowered by the transistor Q3. Vp or Vrn) is output to the vertical signal line 162j.

  Next, FIG. 4 shows the problem that “a good image cannot be obtained because noise due to dark current is superimposed on an image when the exposure control of flash light is performed using an electronic shutter”, which is an object of the present invention. It will be described in detail. FIG. 4 is a timing chart showing a driving method of the pixel 162b of the image sensor 162 shown in FIG. 3, FIG. 4 (a) is a timing chart at the time of imaging in which all pixels of the image sensor are driven simultaneously, and FIG. FIG. 4B is a timing chart at the time of outputting an imaging signal that is sequentially driven for each horizontal pixel row, following FIG.

  In FIG. 4A, the transfer signal φTX is set to the high potential H from timing t41 to t42, so that the photocharge Qp accumulated in the parasitic capacitance Cp of the photodiode PD is completely transferred to the floating diffusion FD through the transistor Q1. Then, the parasitic capacitance Cp of the photodiode PD is reset. At the same time, the reset signal φRST is set to the high potential H, so that the floating diffusion FD is reset to the power supply potential VDD via the transistor Q2.

  When the transfer signal φTX is set to the low potential L at the timing T42, accumulation of the photocharge Qp by the steady light in the parasitic capacitance Cp of the photodiode PD is started. At the same time, the reset signal φRST is set to the low potential L, so that the floating diffusion FD is brought into a floating state. At this time, the reset noise Vrn remains in the floating diffusion FD. Photometry of the photometry unit 171 is started from timing t42.

  At timing t43, the flash emission start signal TRG is set to a high potential, so that the emission of the flash light FL is started. When it is determined that the exposure amount of the image sensor 162 has reached an appropriate exposure by photometry at the photometry unit 171, an exposure completion signal SP is output from the photometry unit 171 at a timing t44, and a transfer signal is synchronized with the exposure completion signal SP. When φTX is set to the high potential H, the photocharge Qp accumulated in the parasitic capacitance Cp of the photodiode PD is completely transferred to the floating diffusion FD via the transistor Q1, and is held in the floating diffusion FD as the optical signal Vp. .

  After the transfer of the photocharge Qp is completed, the transfer signal φTX is quickly returned to the low potential L at the timing t45, whereby the photodiode PD and the floating diffusion FD are disconnected by the transistor Q1.

  As a result, as shown in FIG. 4A, the electronic shutter can be closed at the same time during the emission of the flash light FL, and exposure control under illumination of the flash light can be performed. Here, the exposure time SS is from the timing t42 to t45. In the imaging operation in which the above operations are performed simultaneously for all pixels, the optical signal Vp of each pixel is held in the floating diffusion FD of each pixel at the stage of timing t45.

  Next, in FIG. 4B, the pixel output signal φVj applied to the row selection line 162i of the pixel row of the horizontal j row from the timing t51 to t52 is set to the high potential H, so that The optical signal Vp held in the floating diffusion FD of each pixel in the pixel row is output to the vertical signal line 162j as the imaging signal Vout of each pixel in the horizontal j-th pixel row via the transistors Q3 and Q4. It is held in one of the CDS capacitors of the sample hold circuit 162d.

  At timing t53 to t54, the reset signal φRSTj of the horizontal j-th pixel row is set to the high potential H, so that the floating diffusion FD of each pixel of the horizontal j-th pixel row is set to the power supply potential VDD via the transistor Q2. Reset. At this time, reset noise is generated along with the reset operation, and remains in the floating diffusion FD as reset noise Vrn.

  At timings t55 to t56, the pixel output signal φVj of the horizontal j-th pixel row is again set to the high potential H, whereby the reset noise Vrn remaining in the floating diffusion FD of each pixel of the horizontal j-th pixel row. Is output to the vertical signal line 162j as a noise signal Vnoise of each pixel, and held in the other of the CDS capacitors of the sample and hold circuit 162d.

  The sample hold circuit 162d performs noise removal by taking the difference between the imaging signal Vout and the noise signal Vnoise of each pixel in the horizontal j-th row held by the two CDS capacitors. From timing t57 to t58, the imaging signal Vs from which noise has been removed is output from the output circuit 162e via the output amplifier 162g in synchronization with the horizontal transfer signal φH, and input to the A / D converter 164. Subsequently, the operation proceeds to the output operation of the imaging signal Vs of the horizontal (j + 1) -th pixel row, and the same operation is sequentially performed for all the horizontal pixel rows of the image sensor 162.

  As described above, since the output of the imaging signal Vout of each pixel is sequentially performed for each horizontal pixel row, the time from the timing t45 to the output is different for each horizontal pixel row, and the pixel row having a long time to output is long. It is necessary to hold the optical signal Vp in the floating diffusion FD of each pixel over time. However, the floating diffusion FD has a large dark current due to its structure, and the amount of dark current noise mixed into the optical signal Vp increases due to long-time charge retention, resulting in a problem that a good image cannot be obtained. .

  Next, a method for solving the problem of the present invention described with reference to FIG. 4 will be described with reference to FIGS. FIG. 5 is a diagram showing an imaging device and a light shielding device according to an embodiment of the present invention, and is a schematic diagram showing an example in which the light shielding device 162x is arranged on the imaging surface 162a of the imaging device 162.

  In FIG. 5, the configuration of the image sensor 162 is the same as that shown in FIG. 2, and the pixels 162 b include photodiodes PD and are arranged in a matrix in the horizontal and vertical directions. Here, an example of a 16-pixel image sensor having four pixels in both the horizontal and vertical directions is exemplified, but the present invention is not limited to this.

  On each horizontal pixel row, a light shielding member 623, which is one of the components of the light shielding device 162x, is arranged for each horizontal pixel row, and each light shielding member 623 is arranged on the image sensor 100 at the right end of the drawing. Outside the arrayed region, they are connected and integrated in the vertical direction by the connecting portion 621. The light shielding member 623 is set to a size that shields all or part of the light incident on the photodiode PD.

  A second comb-like electrode 627 constituting the light shielding drive unit 162y is provided on the back surface of the connecting portion 621 in the vertical direction of the light shielding member 623. A first comb-like electrode 625 is provided on the surface of the portion facing the comb-like electrode 627 and is applied between the first comb-like electrode 625 and the second comb-like electrode 627. By controlling the voltage, the light shielding members 623 of all the pixels can be moved together to change the light shielding area of all the pixels simultaneously. Accordingly, it is possible to realize a shutter function that can control the exposure amount of the pixel 162b or perform simultaneous exposure of all the pixels of the image sensor 162.

  According to the present embodiment, the amount of movement of the light shielding member 623 is about the size of the photodiode PD and is very small, about several micrometers, so that the speed of the light shielding operation can be increased. Compared to this, a much faster shutter can be realized. Furthermore, since exposure timing does not differ depending on the position on the image sensor as in the conventional focal plane shutter, all pixels can be exposed simultaneously, so exposure control is possible even with flash light such as flash light. .

  In the example illustrated in FIG. 5, the light shielding member 623 is provided for each horizontal pixel, but is not limited thereto, and may be provided for each vertical column and connected horizontally outside the pixel region. In the example shown in FIG. 5, the light shielding member 623 is connected in the vertical direction only on one side (the right side in the figure). However, a connecting part 621 is provided on the left side in the figure, and the connecting part 621 on the left side is also the first. One comb-like electrode 625 and a second comb-like electrode 627 may be provided. In this case, although there is a drawback that the area of the portion where the connecting portion 621 is arranged is increased, the force for driving the light shielding member 623 is increased and the mechanical strength is increased, so that a higher-speed shutter function can be realized.

  As shown in FIG. 5, the length a of at least one side of the light shielding member 623 is set to be shorter than the distance d between the columns of the pixels 162b (hereinafter referred to as the inter-column distance) d. Here, the inter-column distance d will be described in detail with reference to FIG. FIG. 6 is a schematic diagram showing the arrangement of the pixels 162b for explaining the definition of the inter-column distance d.

  In FIG. 6A, when the rectangular pixels 162b are arranged in a matrix in the horizontal and vertical directions, for example, an array Hn of adjacent pixels in the nth column in the horizontal direction and an array Hn + 1 in the pixels in the (n + 1) th column. , The inter-column distance d is the distance between Hn and Hn + 1, that is, the pixel pitch Dh. The same idea may be applied to the vertical direction.

  On the other hand, in the imaging device having a structure (so-called honeycomb structure) in which hexagonal pixels 162b are densely arranged as shown in FIG. 6B, the horizontal and vertical directions may be the same as those in FIG. As for the diagonal direction, when considering the pixel array Hn and the pixel sequence Hn + 1 of the n + 1th column in the diagonal direction shown in FIG. 6B, the inter-column distance d is Hn and Hn + 1. The distance between them, that is, the diagonal pixel pitch Db. Thus, when there are a plurality of inter-column distances according to the arrangement of the pixels, the length a of at least one side of the light shielding member 623 is set to be shorter than at least one inter-column distance d.

  FIG. 7 is a timing chart showing a driving method of the pixel 162b of the image sensor 162 and the light shielding device 162x shown in FIG. 5, and FIG. 7A shows that all pixels of the image sensor and the light shielding device 162x are driven simultaneously. FIG. 7B is a timing chart at the time of imaging signal output that is sequentially driven for each horizontal pixel row, following FIG. 7A. Here, the circuit of the pixel 162b is the same as that shown in FIG.

  In FIG. 7A, in the initial state, the light shielding device control signal MS is set to a low potential L. In this state, the light shielding member 623 completely shields the photodiode PD. Since the transfer signal φTX is set to the high potential H from timing t61 to t62, the photocharge Qp accumulated in the parasitic capacitance Cp of the photodiode PD is completely transferred to the floating diffusion FD via the transistor Q1, and the photodiode PD The parasitic capacitance Cp is reset. At the same time, the reset signal φRST is set to the high potential H, so that the floating diffusion FD is reset to the power supply potential VDD via the transistor Q2.

  Since the transfer signal φTX is set to the low potential L at the timing t62, it is possible to accumulate the photocharge Qp by the steady light in the parasitic capacitance Cp of the photodiode PD. At this timing, the light shielding device control signal MS is set to the low potential L. Therefore, the light shielding member 623 keeps the photodiode PD completely shielded from light, and the accumulation of the photocharge Qp by the steady light is not started. At the same time, the reset signal φRST is set to the low potential L, so that the floating diffusion FD is brought into a floating state. At this time, the reset noise Vrn remains in the floating diffusion FD.

  When the light-shielding device control signal MS is set to the high potential H at timing t63, the light-shielding member 623 is moved from the position where the photodiode PD is completely shielded, and the steady light from the subject is incident on the photodiode PD. Accumulation of photocharge Qp by stationary light in the parasitic capacitance Cp of the PD, that is, imaging is started. At the same time, photometry of the photometry unit 171 is started.

  The amount of movement of the light shielding member 623 is calculated from the incident light quantity obtained from the previous photometric result by the photometry unit 171 and is determined by the percentage of the incident light quantity that should be reduced, as in the case of normal lens aperture value control. Is done. Of course, the light shielding member 623 may be completely moved from above the photodiode PD, and the amount of incident light may be reduced using a lens diaphragm.

  At timing t64, the flash emission start signal TRG is set to a high potential, so that the flash light FL starts to be emitted. When it is determined that the exposure amount of the image sensor 162 has reached an appropriate exposure by photometry at the photometry unit 171, an exposure completion signal SP is output from the photometry unit 171 at timing t65, and the timing is synchronized with the exposure completion signal SP. Since the light-shielding device control signal MS is set to the low potential L at t66, the light-shielding member 623 completely shields the photodiode PD and the imaging is finished. The photocharge Qp accumulated in the parasitic capacitance Cp of the photodiode PD is held in the parasitic capacitance Cp as it is.

  As a result, as shown in FIG. 7A, during the emission of the flash light FL, all the pixels can be simultaneously shielded by the light shielding device 162x, and exposure control under the illumination of the flash light can be performed. . Here, the exposure time SS is from timing t63 to t66. In the imaging operation in which the above operations are performed simultaneously for all the pixels, the photoelectric charge Cp of each pixel is held in the parasitic capacitance Cp of the photodiode PD of each pixel at the stage of timing t66. Since the photodiode PD is composed of an embedded photodiode, the dark current is very small, and the influence of noise is very small even if it is held for a long time.

  Next, in FIG. 7B, the reset signal φRSTj of the horizontal j-th pixel row is set to the high potential H from timing t71 to t72, so that the floating diffusion FD of each pixel of the horizontal j-th pixel row. Is reset to the power supply potential VDD via the transistor Q2. At this time, reset noise is generated along with the reset operation, and remains in the floating diffusion FD as reset noise Vrn.

  The pixel output signal φVj applied to the horizontal j-th row selection line 162i at the timing t73 to t74 is set to the high potential H, so that it remains in the floating diffusion FD of each pixel in the horizontal j-th pixel row. The reset noise Vrn is output to the vertical signal line 162j as a noise signal Vnoise of each pixel, and is held by one of the CDS capacitors of the sample hold circuit 162d.

  At timing t75 to t76, the transfer signal φTXj of the horizontal j-th pixel row is set to the high potential H, whereby the light held in the parasitic capacitance Cp of the photodiode PD of each pixel of the horizontal j-th pixel row. The charge Qp is completely transferred to the floating diffusion FD of each pixel and held as an optical signal Vp.

  At timings t77 to t78, the pixel output signal φVj of the horizontal j-th pixel row is again set to the high potential H, so that it is completely transferred and held in the floating diffusion FD of each pixel of the horizontal j-th pixel row. The optical signal Vp is output to the vertical signal line 162j as the imaging signal Vout of each pixel in the horizontal j-th pixel row via the transistors Q3 and Q4, and is held on the other CDS capacitor of the sample hold circuit 162d.

  In the sample and hold circuit 162d, noise is removed by taking the difference between the imaging signal Vout and the noise signal Vnoise of each pixel in the horizontal j-th row held by the two CDS capacitors. The image signal from which noise has been removed is denoted by Vs (= Vout−Vnoise). From timing t79 to t80, the noise-removed imaging signal Vs is output from the output circuit 162e via the output amplifier 162g in synchronization with the horizontal transfer signal φH, and input to the A / D converter 164. Subsequently, the operation proceeds to the output operation of the imaging signal Vs of the horizontal (j + 1) -th pixel row, and the same operation is sequentially performed for all the horizontal pixel rows of the image sensor 162.

  As described above, since the photodiode PD is composed of an embedded photodiode, the dark current is very small, and the photocharge Cp held in the parasitic capacitance Cp of the photodiode PD of each pixel is long. The influence of noise is very small even by holding.

  Further, since the photocharge Cp held in the parasitic capacitance Cp of the photodiode PD of each pixel is output to the vertical signal line 162j immediately after being completely transferred to the floating diffusion FD, it is held in the floating diffusion FD. The time is short, and it is hardly affected by the dark current generated in the floating diffusion FD. Therefore, the problem such as “a good image cannot be obtained by dark current” as described in FIG. 4 does not occur.

  As described above, according to the present invention, the light shielding member is provided on the pixel of the image sensor, and the light shielding member is moved to control the shielding of the incident light to the photoelectric conversion unit. It is possible to provide an imaging apparatus that can control exposure even when using an illumination unit that emits such flash light, and that can obtain a good image with less noise due to dark current.

  The detailed configuration and detailed operation of each component constituting the imaging apparatus according to the present invention can be changed as appropriate without departing from the spirit of the present invention.

It is a block diagram which shows the internal structure of an imaging device. It is a block diagram which shows the internal structure of an image pick-up element. It is a circuit diagram which shows an example of a structure of a pixel. 4 is a timing chart illustrating a method for driving pixels of the image sensor illustrated in FIG. 3. It is a figure which shows the image pick-up element and light-shielding device which are one embodiment of this invention. It is a schematic diagram which shows the arrangement | sequence of the pixel for demonstrating the definition of the distance between columns. 6 is a timing chart showing a method for driving the pixels of the image sensor shown in FIG. 5 and a light shielding device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 111 Operation part 131 Display part 141 Illumination part 151 Control part 160 Imaging part 161 Imaging control part 162 Image pick-up element 162a Imaging surface 162b Pixel 162c Vertical scanning circuit 162d Sample hold circuit 162e Output circuit 162f Horizontal scanning circuit 162h Output amplifier 162h Generator 162i Row selection line 162j Vertical signal line 162x Light shielding device 621 Connection part 623 Light shielding member 162y Light shielding drive part 625 First comb-like electrode 627 Second comb-like electrode 164 Analog digital (A / D) converter 165 Image Processing Unit 167 Shading Control Unit 171 Photometry Unit 191 Recording Medium 211 Lens 221 Lens Drive Unit PD Photodiode

Claims (3)

An image sensor in which pixels having a photoelectric conversion unit are two-dimensionally arranged;
A light shielding member for shielding all or a part of incident light to the photoelectric conversion unit, wherein at least one side has a pixel row arranged in an arrangement direction of pixels and a pixel adjacent to the pixel row A light-shielding device including the light-shielding member in which light-shielding pieces shorter than the distance to the row are connected to each other at an end, and a light-shielding drive unit for moving the position of the light-shielding member on the photoelectric conversion unit In the provided imaging device,
An illumination unit that illuminates the subject;
An image pickup apparatus comprising: an image pickup control unit that controls light blocking operation of all or part of incident light to the photoelectric conversion unit performed by the light blocking member in association with light emission of the illumination unit. The imaging apparatus according to claim 1, wherein the imaging control unit controls a light shielding operation of the light shielding member in synchronization with light emission of the illumination unit. The imaging apparatus according to claim 1, wherein the imaging control unit controls a light shielding amount of the light shielding member in synchronization with light emission of the illumination unit.

Images