WO2008004302A1

WO2008004302A1 - Solid-state imaging device and method of controlling the same

Info

Publication number: WO2008004302A1
Application number: PCT/JP2006/313541
Authority: WO
Inventors: Tadao Inoue; Katsuyoshi Yamamoto
Original assignee: Fujitsu Microelectronics Limited
Priority date: 2006-07-07
Filing date: 2006-07-07
Publication date: 2008-01-10
Also published as: JPWO2008004302A1

Abstract

A solid-state imaging device has a solid-state imaging element (4) having pixels and also has a liquid crystal shutter (2) for setting the imaging element (4) to either a state where light enters into all the pixels of the imaging element (4) or a state where all the pixels of the imaging element (4) are shielded from light. During exposure to light, the liquid crystal shutter (2) allows light to enter all the pixels, and in other cases, a moving image is taken with all the pixels shielded from light by the liquid crystal shutter (2).

Description

Specification

Solid-state imaging device and control method thereof

Technical field

The present invention relates to a solid-state imaging device and a control method thereof.

Background art

Conventionally, CMOS (Complementary Metal Oxide Semiconductor) image sensors and CCD (Charge Coupled Device) image sensors are known as image sensors used in solid-state imaging devices.

In the CMOS image sensor, there are a rolling shutter method (also known as a line shutter method!) And a global shutter method (also known as a simultaneous shutter method or a batch shutter method) as exposure methods.

[0004] The rolling shutter method is a method in which a series of imaging sequences of reset, exposure, and readout are sequentially performed for each line, and is the most common method among CMOS image sensors. In this method, the exposure timing is different in the vertical direction of the image, so when shooting a moving subject, the shot subject is unnaturally distorted.

[0005] On the other hand, the global shutter method is a method in which all pixels are reset at the same time, exposed at the same time, and simultaneously transferred to a shielded node, which enables simultaneous exposure in all pixels. . In this method, the exposure timing is the same for all pixels, so even if a moving subject is shot, the shot subject will not be distorted.

[0006] In a global shutter type CMOS image sensor, for example, when each pixel is configured by a 5 Tr type pixel circuit, each pixel circuit includes a photodiode that generates an electric charge by light irradiation, and a photodiode. A first transfer transistor that transfers charge from the charge holding region to the charge holding region, a second transfer transistor that transfers charge to the reading node that is the location where the charge holding region force signal is read, and a reset that resets the reading node. A switching transistor, an amplifying transistor, and a selection transistor for performing line selection. In a CMOS image sensor with such a configuration, all pixel circuits are simultaneously Since the charge is transferred from the photodiode to the charge holding area, the exposure timing is the same for all pixels, and the global shutter function can be realized. However, there is a problem that the number of circuit elements constituting the pixel circuit increases, so that the pixel cannot be reduced, and the size and cost cannot be reduced.

[0007] In CCD image sensors, all pixels that make up the frame are simultaneously read out after charge transfer at the same time, so the exposure time until charge transfer is the same for all pixels, realizing a global shutter function. ing. However, there are drawbacks such as high chip cost, smearing, and difficulty in one-chip digital circuit compared to CMOS image sensors. The occurrence of smear is a phenomenon in which when a high-luminance object such as the sun is photographed, surplus charges move in the transfer direction, and a solid white vertical line is generated in the obtained image. Say.

[0008] When the solid-state imaging device is a digital camera equipped with a mechanical shutter, exposure is performed simultaneously for all pixels by changing the mechanical shutter from a closed state to an open state. The global shutter function can be realized by closing the mechanical shutter and reading. Using a mechanical shutter in this way, regardless of whether the image sensor is a CMOS or a CCD, low noise, smearing can be prevented, and a global shutter function can be realized. However, it is technically difficult to open and close the mechanical shutter at high speed and continuously, and even if it is forcibly manufactured, there is a problem that the size, power consumption, and cost are significantly increased.

In view of the above circumstances, an object of the present invention is to provide a solid-state imaging device having a global shutter function for moving image shooting that requires a high frame rate and a control method therefor.

Patent Document 1: Japanese Patent Laid-Open No. 7-78954

Patent Document 2: Japanese Patent Laid-Open No. 2003-332546

Patent Document 3: Japanese Patent Application Laid-Open No. 2004-14802

Disclosure of the invention

[0010] A solid-state imaging device according to the first aspect of the present invention includes a solid-state imaging device having a plurality of pixels, A liquid crystal shutter in a state where light is incident on the plurality of pixels or a state in which the plurality of pixels are shielded, and during the exposure, light is incident on the plurality of pixels by the liquid crystal shutter. Except for the inside, moving image shooting is performed with the liquid crystal shutters shielding the plurality of pixels.

[0011] According to this configuration, the liquid crystal shutter can function as a high-speed continuous shutter, and all pixels can be exposed simultaneously. Therefore, a global shutter function for moving image shooting that requires a high frame rate is provided. The apparatus which it has can be provided.

[0012] Further, the solid-state imaging device according to the second aspect of the present invention is the above-described first aspect, wherein the pixel control means for controlling the plurality of pixels and the signal output from the pixels are read out. A reading means; a control means for controlling each of the means and the liquid crystal shutter; and at the time of moving image shooting, the liquid crystal shutter is configured to shield the plurality of pixels and reset the plurality of pixels. In addition, light is incident on the plurality of pixels by the liquid crystal shutter, and the plurality of pixels are exposed simultaneously, and then the plurality of pixels are shielded from light by the liquid crystal shutter. The control means controls each of the means and the liquid crystal shutter so as to read a signal output from a pixel.

According to this configuration, even if a CMOS image sensor, for example, is used as the solid-state image sensor, all the pixels can be exposed simultaneously by the liquid crystal shutter, so that an apparatus having a glossy shutter function can be provided. it can.

[0014] Further, in the solid-state imaging device according to the third aspect of the present invention, in the second aspect, each of the plurality of pixels includes a photoelectric conversion element, a transfer element, a reset element, and an amplification element. An element and a selection element, wherein the plurality of pixels are shielded from light by the liquid crystal shutter at the time of moving image shooting, and the reset element and the transfer element are provided in each pixel of the plurality of pixels. The photoelectric conversion element is reset by control, the light is then incident on the plurality of pixels by the liquid crystal shutter, and the plurality of pixels are simultaneously exposed, and then the liquid crystal shutter is used. In a state where the plurality of pixels are shielded from light, for each pixel of the plurality of pixels, the reset element and the selection element are controlled and read out, and then the first signal is read. Hexene The control means controls the means and the liquid crystal shutter so as to read out the second signal output by controlling the selection element, and then subtract the first signal from the second signal. It is characterized by that.

[0015] According to this configuration, the first and second signals are read for one reset and the latter force is subtracted, so the kTC noise is not limited to noise due to element variation of the amplifying element. (Reset noise) can also be canceled, reducing noise and increasing SZN.

[0016] Further, in the solid-state imaging device according to the fourth aspect of the present invention, in the third aspect, at the time of the moving image shooting, the control unit performs reset of the photoelectric conversion element that is performed first. It is characterized by controlling so that it may perform simultaneously by the pixel of this.

[0017] According to this configuration, it is possible to reset the photoelectric conversion elements of all the pixels, which is performed first during moving image shooting, in a shorter time.

Further, the solid-state imaging device according to the fifth aspect of the present invention is the first aspect, wherein the first charge transfer means provided corresponding to each pixel of the plurality of pixels and the plurality of pixels are provided. A second charge transfer means provided corresponding to each column of the first charge transfer means, a third charge transfer means connected to each of the second charge transfer means, an amplification means for converting the charge into an electric signal, Each of the means and a control means for controlling the liquid crystal shutter, and a state power for shielding the plurality of pixels by the liquid crystal shutter during the moving image shooting so that light is incident on the plurality of pixels, The pixels are simultaneously exposed to light, and then the plurality of pixels are shielded from light by the liquid crystal shutter, and the second charges corresponding to the charges generated in the pixels by the first transfer means are respectively associated. To the charge transfer means, and then The control means controls the means and the liquid crystal shutter so that the charge is further transferred to the amplifying means by the second and third charge transferring means and converted into an electric signal by the amplifying means. It is characterized by that.

[0018] According to this configuration, even if a CCD image sensor is used as the solid-state image sensor, all pixels are shielded by the liquid crystal shutter except during exposure (for example, during charge transfer), so that smear is not generated. Therefore, a high-quality image can be obtained.

[0019] In addition to the solid-state imaging device according to each aspect described above, the present invention provides a method for controlling a solid-state imaging device It can be configured as a law.

Brief Description of Drawings

[0020] The present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

FIG. 1 is a diagram showing the mounting structure of an image sensor chip and a liquid crystal shutter provided in the solid-state imaging device according to Embodiment 1.

FIG. 2 is a diagram illustrating a circuit configuration of an image sensor chip on which a liquid crystal shutter is mounted according to the first embodiment.

FIG. 3 is a timing chart showing an operation during moving image shooting according to the first embodiment.

FIG. 4 is a timing chart showing an operation at the time of moving image shooting according to a modification of the first embodiment.

FIG. 5 is a diagram showing a circuit configuration of an image sensor chip on which a liquid crystal shutter is mounted according to Example 2.

FIG. 6 is a timing chart showing the operation during moving image shooting according to the second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1

FIG. 1 is a diagram illustrating a mounting structure of an imaging element chip and a liquid crystal shutter that are included in the solid-state imaging device according to Embodiment 1 of the present invention.

As shown in the figure, in the solid-state imaging device according to the present embodiment, the liquid crystal shutter 2 is mounted on the imaging element chip 1 by being adhered by the conductive adhesive 3. In this embodiment, the bonding force by the conductive adhesive 3 The liquid crystal shutter 2 is placed on the image sensor chip 1 by bonding with solder bumps that can be processed at a low temperature that does not affect the liquid crystal shutter 2. It can also be implemented.

[0023] The image pickup device chip 1 is a Si substrate LSI, and includes a CMOS image sensor (CMOS solid-state image pickup device) in which each pixel is configured by a 4Tr type pixel circuit, a readout circuit, a control circuit, and the like. Yes. In this embodiment, it is also possible to apply other image sensors such as a CMD (Charge Modulation Device) image sensor that applies a CMOS image sensor as a solid-state imaging device. The liquid crystal shutter 2 is a transmissive liquid crystal shutter, and the liquid crystal is controlled to be transparent and opaque under the control of a control circuit mounted on the image sensor chip 1, and light ( (Image light) is incident, or all pixels are shielded.

[0025] Note that the liquid crystal can be switched between light and dark according to the moving image as already used in displays of televisions, computers, workstations, and the like. By using it as a shutter for an imaging device, it realizes a high-speed continuous shutter and enables high frame rate movie shooting. It is assumed that the liquid crystal shutter 2 is capable of high-speed operation that can express a moving image of television.

FIG. 2 is a diagram showing a circuit configuration of the image sensor chip 1 on which the liquid crystal shutter 2 is mounted.

In the figure, the CMOS image sensor 4 is composed of a plurality of pixels in N rows (lines) and XM columns (columns), and the pixel circuit of each pixel is composed of a 4Tr type pixel circuit as shown in frame 5. Has been. The 4Tr pixel circuit consists of a photodiode (hereinafter referred to as “PD” t), which is a photoelectric conversion element that generates charges when irradiated with light, and a reading node (hereinafter referred to as “FD” t, where PD force is also a signal readout location). (FD: Floating Diffiision)) Transfer transistor (hereinafter referred to as "TG-Tr") (TG: Transfer Gate) that transfers charge to FD and reset device that resets FD Transistor (hereinafter referred to as “RST-Tr”), amplification transistor (hereinafter referred to as “SF—Tr” (SF)) whose gate terminal is connected to FD, and CMOS image sensor 4 A selection transistor (hereinafter referred to as “SLCT-Tr”), which is a selection element for selecting one line from a plurality of lines commonly connected to each column output, is provided. RST-Tr, TG-Tr, SF-Tr, and SL CT-Tr are n-channel MOS transistors. RST is a signal for controlling RST-Tr, TG is a signal for controlling TG-Tr, SLCT is a signal for controlling SLCT-Tr, V DD is a power supply voltage, and VR is a reset voltage.

A line control circuit (an example of pixel control means) 6 controls each pixel circuit of the CMOS image sensor 4 for each line. A readout circuit (an example of readout means) 7 reads out the signal of each pixel output from each column of the CMOS image sensor 4. Further, the readout circuit 7 includes a CDS circuit, and from the signal read out when the charge force FD generated by exposure is present, A difference signal obtained by subtracting the signal read at the time of the output is output. The ADC (AD converter) 8 converts the analog signal output from the readout circuit 7 into a digital signal and outputs it. The drive circuit 9 drives the liquid crystal shutter 2.

Control circuit (an example of control means) 10 controls each circuit of the line control circuit 6, the read circuit 7, the ADC 8, and the drive circuit 9. The control circuit 10 has an exposure time control unit 10a that controls the exposure time according to the exposure time obtained by the AE (Automatic Exposure) function provided in the solid-state imaging device, and is controlled by the exposure time control unit 10a. Each circuit is also controlled accordingly. Note that the exposure time required by the AE function is determined according to the brightness of the subject. Further, the AE function can be mounted on the image sensor chip 1 or can be mounted outside the image sensor chip 1.

Next, as the operation of the circuit configuration shown in FIG. 2, the operation during moving image shooting will be described in detail.

FIG. 3 is a timing chart showing an operation during moving image shooting according to the present embodiment.

In FIG. 3, the “shutter control signal” is a signal output from the control circuit 10 to the drive circuit 9 in order to control the liquid crystal shutter 2. The drive circuit 9 drives the liquid crystal shutter 2 so as to make it transparent Z opaque in accordance with the shutter control signal.

In addition, the control signals of “first row control signal”, “second row control signal”,..., “J row control signal”,. These signals are output from the line control circuit 6 to the pixel circuits of the pixels of the CMOS image sensor 4 under the control of the control circuit 10. Each of these control signals is a “reset signal” (RST) that controls the RST-Tr and a “transfer signal” that controls the TG-Tr in the pixel circuit (see frame 5 in FIG. 2). (TG) and “selection signal” (SLCT) which is a signal for controlling S LCT-Tr.

In addition, “read circuit CDS circuit operation” indicates the operation of the read circuit 7 including the CDS circuit. “ADC circuit operation” indicates the operation of ADC8.

As shown in the timing chart of FIG. 3, in the operation at the time of moving image shooting, first, (S1) the shutter control signal makes the liquid crystal shutter 2 opaque and blocks all pixels of the CMOS image sensor 4.

[0033] Next, (S2) 1 of the CMOS image sensor 4 is controlled by a control signal from the line control circuit 6. As for the row power, the following operation (S2a) is performed in the pixel circuit of each pixel in each line in order up to the Nth row.

[S2a] The reset signal and transfer signal are turned ON and OFF simultaneously to turn ON RST-Tr and TG-Tr at the same time to reset the PD (advanced reset: Al).

Subsequently, (S3) the liquid crystal shutter 2 is made transparent by the shutter control signal. As a result, light (image light) is simultaneously incident on all the pixels of the CMOS image sensor 4, and simultaneous exposure of all the pixels is performed (exposure for one frame). At this time, charges are generated in the PD of each pixel due to light irradiation.

Note that the time during which the liquid crystal shutter 2 is made transparent in this (S3), that is, the exposure time, is determined according to the exposure time obtained by the AE function of the solid-state imaging device, and the exposure time control unit Controlled by 10a.

Subsequently, (S4) the liquid crystal shutter 2 is made opaque again by the shutter control signal, and all pixels of the CMOS image sensor 4 are shielded from light again.

Subsequently, (S5) In response to a control signal from the line control circuit 6, the first row force of the CMOS image sensor 4 is also sequentially applied to each pixel line in each pixel up to the Nth row. The operations of .about. (S5e) are performed in order, the readout circuit 7 is also operated in (S5b), and the readout circuit 7 and ADC8 are also operated in (S5d) (output operation for one frame).

[0037] (S5a) Turn the reset signal ON and OFF to turn on the RST-Tr and reset the FD (Reading reset: A2).

(S5b) Turn ON / OFF the selection signal to turn on SLCT-Tr, and output the reset signal from SF-Tr (Read selected row reset level: A3). The reset signal output here is read out by the readout circuit 7 (reset level sampling: A4).

[0038] (S5c) The transfer signal is turned ON / OFF to turn TG-Tr ON, and the charge accumulated in the PD is transferred to the FD (signal charge transfer: A5).

(S5d) Turn ON / OFF the selection signal to turn on SLCT-Tr, and output the signal when the charge accumulated in PD is transferred to FD, such as SF-Tr force (read out selected row signal: A6) . The signal output here is read out by the readout circuit 7 (signal readout: A7), and reset by the CDS circuit of the readout circuit 7 in the above (S5b) for each column. The hour signal is subtracted and the difference signal is output. This makes it possible to simultaneously cancel the reset noise (kTC noise), which is slightly different each time the signal level at the time of resetting, and the noise due to SF-Tr element noise for each column. The difference signal output from the readout circuit (CDS circuit) 7 is converted into a digital signal by the ADC 8 and output.

[0039] (S5e) Similarly to (S2a) above, the reset signal and the transfer signal are turned ON and OFF simultaneously to turn ON RST-Tr and TG-Tr simultaneously, and the PD is reset (advanced reset: Al).

[0040] When the operation in (S5) is completed, the process returns to (S3), and similarly, exposure and output operations for the next one frame are started.

In this way, moving image shooting is performed by repeating exposure and output for one frame.

As described above, according to the solid-state imaging device according to the present embodiment, the liquid crystal shutter 2 mounted on the imaging element chip 1 uses the CMOS image sensor in which each pixel is configured by a 4Tr type pixel circuit. A global shutter function that enables simultaneous exposure of all pixels can be realized, so that even if a moving subject is shot, the shot subject will not be distorted. In addition, each pixel is a 4Tr type pixel circuit. Since it is configured, it is possible to reduce the size and cost.

[0042] In addition, by switching between the incidence of light on all pixels of the CMOS image sensor 4 and the light shielding by the liquid crystal shutter 2, it becomes possible to repeat the light incidence and light shielding at high speed and continuously during movie shooting. There is no problem that the size, power consumption, and cost are significantly increased as in the case of using a mechanical shutter.

[0043] Further, in the solid-state imaging device according to the present embodiment, a PD can be embedded in the substrate (inside the imaging device chip 1) by using a 4Tr type pixel circuit as the pixel circuit of each pixel. Therefore, the influence of dark current noise caused by a large number of crystal defects on the substrate surface can be reduced.

Further, in the solid-state imaging device according to the present embodiment, a 4Tr type pixel circuit is used as the pixel circuit of each pixel, and the reset level of (S5b) is compared to the single readout reset of (S5a). Signal reading and the above signal reading (S5d) are performed. —KTC noise (reset noise) that can be canceled out only by noise due to element variations of Tr can be canceled, and SZN can be increased by reducing noise.

Note that in the solid-state imaging device according to the present embodiment, a force using a 4Tr type pixel circuit as a pixel circuit, for example, a 3Tr type pixel circuit without TG-Tr, or two pixels, RST-Tr and SF— It is also possible to use a 4Tr-Tr shared pixel circuit that shares Tr and SLCT-Tr. For example, if a 3Tr type pixel circuit is used, reset the liquid crystal shutter 2 with the liquid crystal shutter 2 opaque, then perform the exposure with the transparency, and then read with the opaque Thus, all pixels can be exposed simultaneously.

[0046] Further, in the solid-state imaging device according to the present embodiment, the operation at the time of moving image shooting has been described using the timing chart shown in FIG. 3. First, in this timing chart, In the operation of (S2) to be performed, the operation of (S2a) is performed in the pixel circuit of each pixel in each line in order for each line up to the first line Nth line of the CMOS image sensor 4. As shown in the timing chart of FIG. 4, it is also possible to perform the above operation (S2a) in the pixel circuit of each pixel in each line simultaneously with all the lines of the CMOS image sensor 4. As a result, the first reset for the pixel circuits of all the pixels, which is performed first, can be performed in a short time, and the frame rate can be further increased.

In the solid-state imaging device according to the present embodiment, the image sensor chip 1 is further provided with an image processing circuit such as color processing, gamma processing, contour correction processing, and AWB (Automatic White Balance) processing. It is also possible to configure.

Example 2

[0048] The solid-state imaging device according to the second embodiment of the present invention is an aspect in which a CCD image sensor is used instead of the CMOS image sensor in the solid-state imaging device according to the first embodiment. That is, in the solid-state imaging device according to the present embodiment, a liquid crystal shutter is mounted on the image sensor chip on which the CCD image sensor is mounted, and light to the CCD image sensor is driven by driving the liquid crystal shutter. (Image light) is switched between incident and shading.

FIG. 5 is a diagram showing a circuit configuration of an imaging element chip on which a liquid crystal shutter is mounted in the solid-state imaging device according to the present embodiment. In the figure, the same elements as shown in FIG. These elements are denoted by the same reference numerals.

In FIG. 5, a CCD image sensor 21 is an IT (Interline Transfer) type CCD image sensor having a plurality of pixels of N rows (lines) XM columns (columns), and each pixel has a PD. A vertical transfer CCD (an example of the second charge transfer means) 22 is provided adjacent to each column PD, and each vertical transfer CCD 22 has a horizontal transfer CCD (of the third charge transfer means). Example) 23 is connected. Here, PD is a photodiode, which is a photoelectric conversion element that generates charges when irradiated with light. The vertical transfer CCD 22 is charge transfer means for transferring charges in the vertical direction (the direction of the horizontal transfer CCD 23). The horizontal transfer CCD 23 is charge transfer means for transferring charges in the horizontal direction (in the direction of the output amplifier 26). In the figure, the vertical transfer CCD 22 and the horizontal transfer CCD 23 are schematically shown by bold arrows including the transfer direction. However, for the vertical transfer CCD 22, only the first column, the second force ram, and the last column are shown. In the CCD image sensor 21, each PD is connected to an adjacent vertical transfer CCD via a transfer gate (an example of first charge transfer means, hereinafter referred to as “TGP”). In the figure, only some TGPs are shown as “TG P”.

[0051] The line driving circuit 24 applies a positive voltage pulse to each TGP as a transfer signal (Tf) to transfer the charge accumulated in each PD to the adjacent vertical transfer CCD 22, and for vertical transfer. By changing the positive pulse phase of the voltage applied to the CCD22 transfer gate group (hereinafter “TGV” t) as the vertical transfer signal in the order of ν φ 1, νφ 2 and νφ 3, Transfer in the direction of CCD23 for transfer). In the figure, only some TGVs are indicated as “TGV”.

[0052] The column drive circuit 25 determines the positive pulse phase of the voltage applied as a horizontal transfer signal to the transfer gate group (hereinafter “TGH” t ヽぅ) of the CCD 23 for horizontal transfer as Η φ 1, Η φ 2, Η φ Change to the order of 3 to transfer the charge in the horizontal direction (in the direction of output amplifier 26). In the figure, only a part of TGH is shown as “TGH”.

The output amplifier 26 is an amplifying means for converting the transferred charge into an electric signal, and generates a voltage corresponding to the transferred charge by the parasitic capacitance of the input node and outputs it. The control circuit 27 includes a line drive circuit 24, a column drive circuit 25, an output amplifier 26, and a drive. Controls each circuit of the dynamic circuit 9. Similarly to the first embodiment, the control circuit 27 has an exposure time control unit 27a that controls the exposure time according to the exposure time obtained by the AE function provided in the solid-state imaging device, and the exposure time control unit 27a Each circuit is also controlled according to the control by.

Next, as the operation of the circuit configuration shown in FIG. 5, the operation during moving image shooting will be described in detail.

FIG. 6 is a timing chart showing an operation during moving image shooting according to the present embodiment.

In the same figure, the “shutter control signal” is a signal output from the control circuit 27 to the drive circuit 9 in order to control the liquid crystal shutter 2 as in the first embodiment.

The “transfer signal Tf” is a transfer pulse signal that is output from the line drive circuit 24 to each TGP under the control of the control circuit 27 and transfers charges from the PD to the vertical transfer CCD 22. The “vertical transfer signals V φ 1”, “V φ 2”, and “V φ 3” are output from the line drive circuit 24 to the TGV of each vertical transfer CCD 22 under the control of the control circuit 27 for vertical transfer. This is a pulse signal that transfers charges along the CCD22. The “horizontal transfer signals Η φ 1”, “Η φ 2”, and “H φ 3” are output from the column drive circuit 25 to the TGH of the horizontal transfer CCD 23 under the control of the control circuit 27, and the horizontal transfer CCD 23 Is a pulse signal for transferring charges along the line.

“RST” is a signal that resets the charge sensing node that converts the charge that is output from the control circuit 27 to the output amplifier 26 and transferred to the output amplifier into a voltage. The charge sensing node is an input node of an amplifier having a parasitic capacitance, and more specifically, a gate terminal of an amplifying transistor. “Output” is an output signal of the output amplifier 26.

[0057] As shown in the timing chart of the figure, in the operation during moving image shooting, first, (S11) the liquid crystal shutter 2 is changed from opaque to transparent by a shutter control signal. As a result, light (image light) enters the PD of all pixels, and all pixels are exposed simultaneously (exposure for one frame). At this time, charges are generated in the PD of each pixel by light irradiation.

Note that the time during which the liquid crystal shutter 2 is made transparent in this (S11), that is, the exposure time, is determined according to the exposure time obtained by the AE function of the solid-state imaging device, and the exposure time control unit Controlled by 27a.

[0059] When exposure for the exposure time is completed, the following (S12) to (S14) are performed, and one frame Perform the output operation for the number of seconds.

First, (S12) the liquid crystal shutter is made opaque by the shutter control signal, and the PDs of all pixels are shielded from light.

Subsequently, (S 13) A positive voltage pulse is given as a transfer signal (TF) from the line drive circuit 24 to all TGPs. As a result, the charges accumulated in each PD are adjacent to each other for vertical transfer.

Transferred to CCD22 (simultaneous transfer of all pixels).

[0061] Next, (S14) from the first line to the last line (N line), the next page (S14a) and (S14b) for one line is displayed for each line. Performs output operation (operation to read charge for one line with output amplifier 26).

[0062] (S14a) The positive pulse phase of the voltage applied as a vertical transfer signal from the line drive circuit 24 to the TGV of the vertical transfer CCD 22 is changed in the order of νφ 1, νφ 2, and ν φ 3, and the charge is supplied for one line. Transfer in the vertical direction (direction of CCD23 for horizontal transfer). As a result, the charge for one line is transferred to the CCD 23 for horizontal transfer.

[0063] (S14b) From the first column to the last column (M column) in the charge for one line transferred to the CCD 23 for horizontal transfer, the next (S14b— 1 ) ~ (S1

4b— Perform step 3).

[0064] (S14b—1) The input node of the output amplifier 26 is reset by the signal (RST) from the control circuit 27.

(S 14b-2) Change the positive pulse phase of the voltage applied as a horizontal transfer signal from the line drive circuit 24 to the TGH of the horizontal transfer CCD 23 as 水平 φ 1, Η φ 2, and Η φ 3 in this order. Is transferred horizontally by one column (in the direction of output amplifier 26). As a result, the charge for one column is transferred to the input node of the output amplifier 26.

[0065] (S14b—3) When the charge for one column is transferred to the input node, the output amplifier 26 generates a voltage corresponding to the transferred charge by the parasitic capacitance of the input node, and outputs this voltage. The

[0066] When the operation of (S14) is completed, the process returns to (S11), and similarly, the exposure and output operations for the next one frame are started.

In this way, moving images are shot by repeating exposure and output for one frame. The

As described above, according to the solid-state imaging device according to the present embodiment, by mounting the liquid crystal shutter 2 on the imaging element chip on which the CCD image sensor 21 is mounted, the liquid crystal shutter 2 is used except for the exposure during moving image shooting. Since all pixels can be shielded from light, it is possible to prevent smear. Therefore, high-speed movie shooting without smear is possible while using a CCD image sensor as the image sensor.

[0068] Compared to a conventional solid-state imaging device equipped with a CCD image sensor that does not include shutter means such as the liquid crystal shutter 2, the conventional apparatus does not include shutter means, so all pixels are exposed even during exposure. Light continues to be incident on the PD, and a large amount of charge continues to be generated in the PD. At this time, in pixels where the brightness is high, such as the sun, the charge generated in the PD exceeds TGP and overflows to the CCD 22 for vertical transfer. As a result, the overflowing charge is sent to the output amplifier 26, and white vertical lines, or smears, appear in the image. In contrast, in the solid-state imaging device according to the present embodiment, all pixels are shielded by the liquid crystal shutter 2 except during exposure, so that no light enters the PD and smear does not occur.

[0069] Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the scope of the present invention. Of course!

As described above, according to the present invention, it is possible to provide a solid-state imaging device having a global shutter function for moving image shooting that requires a high frame rate and a control method thereof.

Claims

The scope of the claims

[1] a solid-state imaging device having a plurality of pixels;

A liquid crystal shutter that makes light incident on the plurality of pixels or blocks the plurality of pixels;

During exposure, the liquid crystal shutter is used to make light incident on the plurality of pixels, and when not exposed, the liquid crystal shutter is used to shield the plurality of pixels to perform moving image shooting.

A solid-state imaging device.

[2] pixel control means for controlling the plurality of pixels;

Reading means for reading out signals output from the pixels;

Each means and a control means for controlling the liquid crystal shutter,

At the time of moving image shooting, the plurality of pixels are shielded from light by the liquid crystal shutter, the plurality of pixels are reset, and then the liquid crystal shutter is in a state where light is incident on the plurality of pixels. The control means is configured to perform exposure with a plurality of pixels at the same time, and then to read out signals output from the pixels in a state where the plurality of pixels are shielded from light by the liquid crystal shutter. Control the LCD shutter,

The solid-state imaging device according to claim 1, wherein:

[3] Each of the plurality of pixels includes a photoelectric conversion element, a transfer element, a reset element, an amplification element, and a selection element.

At the time of shooting the moving image, the plurality of pixels are shielded from light by the liquid crystal shutter, and the photoelectric conversion element is controlled by controlling the reset element and the transfer element in each pixel of the plurality of pixels. Next, the liquid crystal shutter is used to make light incident on the plurality of pixels, and the plurality of pixels are exposed simultaneously, and then the liquid crystal shutter is used to block the plurality of pixels. Then, for each pixel of the plurality of pixels, the first signal output by controlling the reset element and the selection element is read, and then the transfer element and the selection element are controlled and output. Read out the second signal, and then subtract the first signal from the second signal. 3. The solid-state imaging device according to claim 2, wherein the control unit controls each of the units and the liquid crystal shutter.

[4] At the time of moving image shooting, the control means controls to reset the photoelectric conversion element first performed at the plurality of pixels simultaneously.

The solid-state imaging device according to claim 3.

[5] The solid-state imaging device is a CMOS image sensor.

The solid-state imaging device according to claim 2, wherein:

[6] first charge transfer means provided corresponding to each pixel of the plurality of pixels;

A second charge transfer means provided corresponding to each column of the plurality of pixels; a third charge transfer means connected to each of the second charge transfer means; and converts the charge into an electric signal. Amplifying means;

Each means and a control means for controlling the liquid crystal shutter,

At the time of shooting the moving image, the liquid crystal shutter is used to make light incident on the plurality of pixels from the state where the plurality of pixels are shielded from light, and then the plurality of pixels are simultaneously exposed, and then the liquid crystal shutter is used. The plurality of pixels are shielded from light, and the charge generated in each pixel by the first transfer means is transferred to the corresponding second charge transfer means, and then the second and third The control means controls each means and the liquid crystal shutter so that the charge is further transferred to the amplifying means by the charge transferring means and converted into an electric signal by the amplifying means.

The solid-state imaging device according to claim 1, wherein:

[7] The solid-state imaging device is a CCD image sensor.

The solid-state imaging device according to claim 6.

[8] The control means includes an exposure time control means for controlling a time during which light is incident on the plurality of pixels according to an exposure time determined according to the brightness of a subject. The solid-state imaging device according to any one of claims 1 to 7.

[9] The liquid crystal shutter is provided on the solid-state imaging device by bonding with a conductive adhesive or bonding with solder bumps that can be processed at a low temperature that does not affect the liquid crystal shutter. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is provided.

[10] A method for controlling a solid-state imaging device, comprising: a solid-state imaging device having a plurality of pixels; and a liquid crystal shutter in a state in which light enters the plurality of pixels or a state in which the plurality of pixels are shielded. And

A control method for a solid-state imaging device.

[11] The solid-state imaging device includes a pixel control unit that controls the plurality of pixels, and a reading unit that reads a signal output from the pixel.

The plurality of pixels are shielded from light by the liquid crystal shutter, and the plurality of pixels are reset.

With the liquid crystal shutter in a state where light is incident on the plurality of pixels, the plurality of pixels are simultaneously exposed,

Reading out signals output from the pixels in a state in which the plurality of pixels are shielded from light by the liquid crystal shutter;

So as to control each means and the liquid crystal shutter,

11. The method for controlling a solid-state imaging device according to claim 10, wherein:

[12] The solid-state imaging device includes: a first charge transfer unit provided corresponding to each pixel of the plurality of pixels; and a second charge provided corresponding to each column of the plurality of pixels. A transfer means; a third charge transfer means connected to each of the second charge transfer means; and an amplifying means for converting the charge into an electric signal.

From the state where the plurality of pixels are shielded from light by the liquid crystal shutter to the state where light is incident on the plurality of pixels, exposure is performed simultaneously on the plurality of pixels,

The plurality of pixels are shielded from light by the liquid crystal shutter, and the charge generated in each pixel by the first transfer means is transferred to the corresponding second charge transfer means,

Charges are further transferred to the amplification means by the second and third charge transfer means. Converted into an electrical signal by the amplification means,

11. The control method for a solid-state imaging device according to claim 10, wherein the respective units and the liquid crystal shutter are controlled as described above.