Filming equipment

Abstract

The imaging device (1) comprises: a variable focus lens (10); and an imaging sensor (15) that outputs a signal corresponding to light. The imaging sensor (15) comprises: a photoelectric conversion unit (PD) that converts light into electric charge; a charge readout region (R1 to R4); a transfer control electrode (E1 to E4); a gate control circuit (26) that sequentially applies control signals (TG1 to TG4) to the transfer control electrodes (E1 to E4) corresponding to the position of the focus (P) of the variable focus lens (10); and a readout circuit (27) that outputs a signal corresponding to the amount of charge transferred to the charge readout region (R1 to R4). The gate control circuit (26) repeatedly performs the operation of outputting control signals (TG1 to TG4) when the position of the focus (P) is within a focus range (BF1 to BF4) during a frame period.

Description

Technical Field

[0001] The invention relates to a photographing device. Background Art

[0002] Generally, the focal length of a lens is a unique value for each lens. On the other hand, a so-called variable focus lens capable of changing the focal length is known. For example, Patent Document 1 discloses a technology related to a variable focus lens. The variable focus lens of Patent Document 1 uses a liquid as an element for refracting light. Then, if the liquid is vibrated resonantly, a density distribution is generated. As a result, the focal length of the variable focus lens changes at a speed determined by the frequency of the vibration. The frequency of the vibration is, for example, in the range of tens of Hz to hundreds of kHz.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: U.S. Patent Application Publication No. 2013 / 0321927 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] Research is underway on a photographing device using a variable focus lens and an image sensor. A variable focus lens using liquid changes the focal length through resonant vibration. Therefore, the focal length of the variable focus lens changes continuously. When the photographing range is set to include a range in which the position of the focus changes, exposure is performed only during the period when the focus exists in the photographing range. However, since the period when the focus exists in the photographing range is extremely short, the exposure period is also shortened. When the exposure period is short, the amount of light incident on the image sensor is insufficient. In other words, the brightness of the resulting image becomes low.

[0008] Therefore, the present invention provides a photographing device capable of improving the brightness of an obtained image.

[0009] Means used to solve problems

[0010] An imaging device according to one embodiment of the present invention comprises: a variable focus lens, the position of the focus periodically changes between the farthest point and the closest point during a frame period; and a pixel circuit unit, which is arranged in a manner overlapping with the optical axis of the variable focus lens, receives light passing through the variable focus lens, and outputs a signal corresponding to the light. The pixel circuit unit comprises: a photoelectric conversion unit, which converts light into electric charge; a charge readout region, which is arranged close to the photoelectric conversion unit; a transfer control electrode, which is arranged between the photoelectric conversion unit and the charge readout region, and receives a transfer control signal for charge transfer between the photoelectric conversion unit and the charge readout region; a charge discharge region, which is arranged close to the photoelectric conversion unit and separated from the charge readout region, and discharges electric charge not used for reading the signal corresponding to the light; a discharge control electrode, which is arranged between the photoelectric conversion unit and the charge discharge region, and receives a discharge control signal for charge transfer between the photoelectric conversion unit and the charge discharge region; a control mechanism, which applies a transfer control signal to the transfer control electrode corresponding to the position of the focus of the variable focus lens, and applies a discharge control signal to the discharge control electrode; and a signal readout mechanism, which outputs a signal corresponding to the amount of electric charge transferred to the charge readout region. The control mechanism repeatedly performs the following actions during a frame period: outputting a transfer control signal when the focus position is within a focus range set in the shooting range; and outputting an ejection control signal when the focus position is within a non-shooting range that does not overlap with the shooting range.

[0011] The photographing device has a variable focus lens. The focus position of the variable focus lens changes periodically between the farthest point and the closest point during a frame. Furthermore, the charge transfer control mechanism transfers the charge generated in the photoelectric conversion unit to the charge readout region when the focus position is located in the photographing range. The charge transfer control mechanism transfers the charge to the charge discharge region when the focus position is located in the non-photographing range. Furthermore, the charge transfer control mechanism repeatedly performs transfer to the charge readout region and transfer to the charge discharge region during a frame. As a result, each time these transfer actions are repeated, the charge obtained when the focus position is located in the photographing range is accumulated in the charge readout region. That is, even if the amount of charge transferred in one transfer action is small, the amount of charge accumulated in the charge readout region will increase by repeating the transfer action. Therefore, according to the increase in the amount of charge, the brightness of the obtained image can be improved.

[0012] The pixel circuit unit of a shooting device of one embodiment may also have: one or more additional charge readout regions, which are arranged close to the photoelectric conversion unit and separated from the charge readout region; and one or more additional transfer control electrodes, which are arranged between the photoelectric conversion unit and the additional charge readout region, and receive additional transfer control signals for charge transfer between the photoelectric conversion unit and the additional charge readout region. The control mechanism may also perform the following actions during the frame period: when the focus position is set in the shooting range and is located in the additional focus range that does not overlap with the focus range, the action of outputting the additional transfer control signal. The signal readout mechanism may also output a signal corresponding to the amount of charge transferred to the additional charge readout region, that is, the charge amount. According to this structure, multiple focus ranges can be set in the shooting range. Therefore, a focused and clear image can be obtained.

[0013] A control mechanism of a camera device of one embodiment can generate a transfer control signal and an additional transfer control signal so that the length of a period during which charge is allowed to be transferred from a photoelectric conversion unit to a charge readout region and the length of a period during which charge is allowed to be transferred from a photoelectric conversion unit to one or more additional charge readout regions are equal to each other. According to this structure, the transfer operation can be switched at a constant time interval. Therefore, the control performed by the charge transfer control mechanism can be simplified.

[0014] A control mechanism of an imaging device of one embodiment can generate a transfer control signal and an additional transfer control signal so that the amount of change in the focus position during the period in which the charge is allowed to transfer from the photoelectric conversion unit to the charge readout region and the amount of change in the focus position during the period in which the charge is allowed to transfer from the photoelectric conversion unit to one or more additional charge readout regions are equal to each other. Based on this result, the length of each focus range can be made constant.

[0015] The control mechanism of the imaging device of one embodiment may also set a plurality of sub-frame periods included in a frame period. The control mechanism may set an imaging range for each of the plurality of sub-frame periods. According to this structure, the focus range included in the imaging range can be set in detail.

[0016] In one embodiment, the imaging ranges set for each of the plurality of subframe periods may not overlap with each other. According to this configuration, the imaging range can be expanded.

[0017] In one embodiment, the imaging ranges set for each of the plurality of sub-frame periods may overlap with each other. According to this configuration, the focus range included in the imaging range can be set in further detail.

[0018] The control mechanism of the imaging device of one embodiment can output the transfer control signal twice during one cycle of the focus position change. According to this structure, the amount of charge transferred to the charge reading unit increases. Therefore, the brightness of the obtained image can be further improved.

[0019] The control mechanism of the imaging device of one embodiment can output a transition control signal once during one cycle of focal position change. According to this structure, the synchronization condition between the periodic movement of the focal position of the variable focus lens and the transition operation in the pixel circuit unit can be relaxed.

[0020] The variable focus lens of a camera device of one embodiment may also include: a lens unit through which light is transmitted; and a lens driving unit that periodically changes the position of the focus of the lens unit by providing a lens driving signal to the lens unit. The camera device may also have a pixel control unit that receives the lens driving signal from the lens driving unit and provides a control signal for the pixel circuit unit to the pixel circuit unit based on the lens driving signal. According to this structure, the operation of the lens unit can be synchronized with the operation of the pixel circuit unit.

[0021] A charge readout region of a camera device of one embodiment may also have a two-stage transfer structure. The two-stage transfer structure may be composed of the following parts: a charge accumulation part that receives charge from the photoelectric conversion part; a floating diffusion part that receives charge from the charge accumulation part and is connected to the signal readout mechanism; a reset drain that receives charge from the floating diffusion part; a transfer gate electrode that controls the transfer of charge from the charge accumulation part to the floating diffusion part; and a reset gate electrode that controls the transfer of charge from the floating diffusion part to the reset drain. According to this structure, it is possible to reduce noise caused by the reset action of the floating diffusion part.

[0022] The charge readout region of a camera device of one embodiment may also have a one-stage transfer structure. The charge readout region may also have a one-stage transfer structure. The one-stage transfer structure may be composed of the following parts: a floating diffusion part that receives charge from the photoelectric conversion part; a reset drain that receives charge from the floating diffusion part; and a reset gate electrode that controls the transfer of charge from the floating diffusion part to the reset drain. According to this structure, the structure of the charge readout region can be simplified. In other words, the structure of the pixel circuit part can be simplified.

[0023] The control mechanism of the imaging device of one embodiment may also output a transfer control signal, and after outputting the transfer control signal, output a discharge control signal, and after outputting the discharge control signal, output an additional transfer control signal, and after outputting the additional transfer control signal, output the discharge control signal again. According to this structure, each focal range can be discretely set within a narrow range. As a result, since the focal range in which light from different focal points is averaged becomes narrower, the clarity of the image in each focal range can be improved.

[0024] Effects of the Invention

[0025] According to the present invention, there is provided an imaging device capable of improving the brightness of an obtained image. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a diagram showing the structure of an imaging device according to an embodiment.

[0027] Figure 2 Yes means Figure 1 The diagram shows the structure of the imaging sensor.

[0028] Figure 3 It indicates that the signal line Figure 2 A diagram showing the pixel connections shown.

[0029] Figure 4 Yes means Figure 2 Diagram of the structure of a pixel shown.

[0030] Figure 5 It is a magnified representation Figure 4 A diagram of the main parts of the pixels shown.

[0031] Figure 6 It is a diagram showing the relationship between the operation of the variable focus lens and the focal range.

[0032] Figure 7 It is a diagram for explaining the operation of the imaging device.

[0033] Figure 8 Part (a) is a graph showing the change in focus in the imaging device according to the embodiment. Figure 8 Part (b) is a timing diagram showing the operation of the implementation method.

[0034] Fig. 9 Part (a) is a graph showing the change in focus in the imaging device of Modification 1. Fig. 9 Part (b) is a timing diagram showing the operation of Modification Example 1.

[0035] Fig.10 Parts (a) and (c) are graphs showing changes in focus in the imaging device of Modification 2. Fig.10 Parts (b) and (d) are timing diagrams showing the operation of Modification Example 2.

[0036] Fig.11 Parts (a) and (c) are graphs showing changes in focus in the imaging device of Modification 3. Fig.11 Parts (b) and (d) are timing diagrams showing the operation of Modification Example 3.

[0037] Fig.12 This is a diagram for explaining the imaging range in the imaging device of Modification 3.

[0038] Fig.13 Part (a) is a graph showing the change in focus in the imaging device of Modification 4. Fig.13 Part (b) is a timing diagram showing the operation of variant example 4.

[0039] Fig.14 Part (a) is a graph showing the change in focus in the imaging device of Modification 5. Fig.14 Part (b) is a timing diagram showing the operation of variant example 5.

[0040] Fig.15 This is a diagram showing an enlarged view of a main portion of pixels included in the imaging device of Modification 6.

[0041] Fig.16 It is a diagram showing the structure of an imaging sensor according to Modification 7.

[0042] Fig.17 Yes means Fig.16 Diagram of the structure of a pixel shown.

[0043] Fig.18 Part (a) is a graph showing the focal position and focal range of the variable focus lens. Fig.18 Part (b) indicates Fig.16 as well as Fig.17 The timing diagram of the pixel operation is shown.

[0044] Fig.19 It is a diagram showing the imaging range of the imaging device of Modification Example 8.

[0045] Fig. 20 Part (a) is a graph showing the change in focus in the imaging device of Modification Example 8. Fig. 20 Part (b) is a timing diagram showing the action of variant example 8. DETAILED DESCRIPTION

[0046] Hereinafter, the mode for implementing the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same reference numerals are attached to the same components, and overlapping descriptions are omitted.

[0047] like Figure 1 As shown, the imaging device 1 includes a variable focus lens 10 and an imaging sensor 15 .

[0048] The variable focus lens 10 forms an image of a photographic object on a photographing sensor 15. The position of the focus of the variable focus lens 10 changes periodically between the farthest point and the closest point. The variable focus lens 10 has a lens unit 11 and a lens driving unit 12. The lens driving unit 12 provides a lens driving signal to the lens unit 11. As a result, the position of the focus of the lens unit 11 changes periodically. As such a variable focus lens 10, for example, a lens disclosed in U.S. Patent Application Publication No. 2013 / 0321927 may also be used.

[0049] (Photo sensor)

[0050] The imaging sensor 15 obtains an image of the object to be photographed. The imaging sensor 15 includes: a pixel circuit unit 20, a pixel control unit 50, and an image processing unit 60. The pixel circuit unit 20 is connected to the pixel control unit 50. The pixel circuit unit 20 operates according to a control signal provided from the pixel control unit 50. The actions referred to here include, for example, exposure actions and transfer actions. In addition, the pixel circuit unit 20 is connected to the image processing unit 60. The pixel circuit unit 20 provides an output signal to the image processing unit 60. The pixel circuit unit 20 includes a pixel array 21 and a peripheral circuit 25. The pixel array 21 and the peripheral circuit 25 are arranged on the same semiconductor chip.

[0051] (Pixel Control Unit)

[0052] The operation of the variable focus lens 10 and the operation of the pixel circuit unit 20 are synchronized with each other. Therefore, the pixel control unit 50 receives a reference signal from the variable focus lens 10. The frequency of the reference signal is consistent with the frequency of the lens drive signal. On the other hand, the difference between the phase of the reference signal and the phase of the lens drive signal can be zero or include a specified value. For example, the reference signal can also be the lens drive signal itself. Then, the pixel control unit 50 provides the control signal generated based on the reference signal to the pixel circuit unit 20.

[0053] (Image Processing Unit)

[0054] The image processing unit 60 generates a composite image using the signal provided from the pixel circuit unit 20. The image processing unit 60 generates first to fourth partial images using the signal obtained from the pixel circuit unit 20. The partial images are images obtained at different focus positions. Furthermore, the image processing unit 60 generates a composite image using the first to fourth partial images.

[0055] (Pixel circuit part)

[0056] The pixel circuit unit 20 is configured to overlap with the optical axis of the variable focus lens 10. The pixel circuit unit 20 receives light that has passed through the variable focus lens 10 and outputs a signal corresponding to the light. Figure 2As shown, the pixel array 21 of the pixel circuit unit 20 has a plurality of pixels 22. The plurality of pixels 22 are arranged two-dimensionally. The pixel 22 includes a photoelectric conversion unit PD, charge readout regions R1, R2, R3, R4, buffer amplifiers A1, A2, A3, A4, and a drain DR (charge discharge region).

[0057] Here, the charge readout region R1 is a charge readout region mentioned in the claims. In addition, the charge readout regions R2, R3, and R4 are additional charge readout regions mentioned in the claims. The drain DR is a charge discharge region mentioned in the claims.

[0058] The peripheral circuit 25 includes a gate control circuit 26 (control mechanism), a readout circuit 27 (signal readout mechanism), and an AD conversion circuit 28. The gate control circuit 26 and the readout circuit 27 are connected to the pixel control unit 50 and the pixel array 21, respectively. Specifically, the gate control circuit 26 and the readout circuit 27 are connected to each pixel 22 of the pixel array 21. The gate control circuit 26 and the readout circuit 27 output various signals for controlling the pixel array 21 to the pixel 22.

[0059] The gate control circuit 26 operates based on the signal from the pixel control unit 50. Then, the pixel control unit 50 operates based on the reference signal from the lens driving unit 12. That is, the gate control circuit 26 operates based on the reference signal from the lens driving unit 12. On the other hand, the readout circuit 27 may also operate based on the reference signal from the lens driving unit 12. In addition, the readout circuit 27 may not operate based on the reference signal. That is, the readout circuit 27 may also operate based on a reference signal different from the reference signal.

[0060] The AD conversion circuit 28 is connected to the pixel array 21. The AD conversion circuit 28 converts the output signal received from the pixel array 21 from an analog signal to a digital signal. The AD conversion circuit 28 may also include: a folded integral type conversion circuit unit 28a and a cyclic type conversion circuit 28b. The AD conversion circuit 28 includes a circuit unit including a folded integral type conversion circuit unit 28a and a cyclic type conversion circuit 28b. The circuit unit is arranged in each column. The output of the pixel array 21 is connected to the input of the folded integral type conversion circuit unit 28a. Furthermore, the output of the folded integral type conversion circuit unit 28a is connected to the input of the cyclic type conversion circuit 28b. The output of the cyclic type conversion circuit 28b is connected to the image processing unit 60. The AD conversion circuit 28 outputs the output signal converted into a digital signal to the image processing unit 60.

[0061] Such an AD conversion circuit 28 performs a folded integral type AD conversion operation. According to the folded integral type AD conversion operation, the dynamic range can be expanded. Moreover, according to the K-folded integral type AD conversion operation, the signal component of the pixel 22 increases by K times. On the other hand, the random noise component increases by √K times (the square root of K). Therefore, the S / N ratio (signal-to-noise ratio) can be improved by √K times.

[0062] In addition, the AD conversion circuit 28 may also include the above-mentioned folded integral type conversion circuit section 28a and the cyclic type conversion circuit 28b as independent circuits. In this case, the folded integral type conversion operation and the cyclic type conversion operation can be performed in parallel. In other words, pipeline processing can be applied. As a result, the AD conversion operation can be accelerated.

[0063] On the other hand, the AD conversion circuit 28 can also realize the above-mentioned folded-integral type conversion circuit section 28a and cyclic type conversion circuit 28b by changing the circuit structure by switches in one circuit. According to this structure, the AD conversion circuit 28 can be made into a single-ended structure.

[0064] In addition, the AD conversion circuit 28 may also include a correlated double sampling circuit (so-called CDS circuit). The CDS circuit reduces noise caused by the reset operation in the charge readout regions R1, R2, R3, and R4 described later. The CDS circuit outputs a signal obtained by removing the reset level component from the signal provided by the pixel 22. The CDS circuit receives the output of the pixel array 21. The CDS circuit outputs the processed signal to the folded integral type conversion circuit unit 28a.

[0065] The arrangement of the gate control circuit 26 , the readout circuit 27 , and the AD conversion circuit 28 in the semiconductor chip is not particularly limited. The gate control circuit 26 , the readout circuit 27 , and the AD conversion circuit 28 can be appropriately set according to the structure of the pixel circuit unit 20 .

[0066] In more detail, Figure 3 As shown, a plurality of signal lines are connected to the pixel 22. The transfer control electrodes E1, E2, E3, E4 and the discharge control electrode ED of the pixel 22 are connected to the gate control circuit 26 via the signal lines. The transfer control electrode E1 receives a control signal TG1. The transfer control electrode E2 receives a control signal TG2. The transfer control electrode E3 receives a control signal TG3. The transfer control electrode E4 receives a control signal TG4. The discharge control electrode ED receives a control signal TD.

[0067] The charge readout regions R1, R2, R3, and R4 of the pixel 22 are connected to the power supply 29 via the power supply line. The charge readout regions R1, R2, R3, and R4 receive the voltage VDD from the power supply line. In addition, the charge readout regions R1, R2, R3, and R4 are connected to the gate control circuit 26 via the signal line. The charge readout regions R1, R2, R3, and R4 receive control signals RT and TX from the gate control circuit 26. Furthermore, the charge readout regions R1, R2, R3, and R4 are connected to the buffer amplifiers A1, A2, A3, and A4 via the signal lines, respectively. The buffer amplifiers A1, A2, A3, and A4 are connected to the AD conversion circuit 28.

[0068] The drain DR is connected to the power source 29 via a power line. The drain DR receives the voltage VDD from the power line.

[0069] The buffer amplifiers A1, A2, A3, and A4 are connected to the readout circuit 27 via signal lines, respectively. The buffer amplifiers A1, A2, A3, and A4 receive a control signal SEL from the readout circuit 27.

[0070] Figure 4 2 is a diagram showing the structure of the pixel 22. The pixel 22 includes a light detection unit 22a and an amplifier unit 22b. The light detection unit 22a receives light to generate electric charge. The electric charge is output as a voltage to the AD conversion circuit 28 via the amplifier unit 22b.

[0071] The light detection unit 22a has a photoelectric conversion unit PD and a charge transfer unit 30. The light detection unit 22a has a structure based on the principle of a lateral electric field controlled charge modulator (LEFM) developed by the inventors of this case. The lateral electric field controlled charge modulator controls the electric field of the charge transfer path by utilizing a lateral electric field formed by a plurality of gates arranged on the side of the charge transfer path, thereby controlling the transport of high-speed electrons. As a lateral electric field controlled charge modulator, for example, the structure shown in Japanese Patent No. 6476138 by the inventors of this case can also be adopted.

[0072] The photoelectric conversion unit PD generates charges corresponding to the light received via the opening AP and supplies the charges to the charge transfer unit 30 .

[0073] The charge transfer unit 30 receives the charge supplied from the photoelectric conversion unit PD. The charge transfer unit 30 supplies a voltage based on the charge to the buffer amplifiers A1, A2, A3, A4. The charge transfer unit 30 has a charge collection region 31, a charge distribution unit 32, a drain 33, and charge readout regions R1, R2, R3, R4.

[0074] The charge collecting region 31 collects the charges generated in the photoelectric conversion portion PD, and the charge distributing portion 32 transfers the collected charges to any one of the charge readout regions R1 , R2 , R3 , R4 and the drain 33 .

[0075] The charge distribution unit 32 distributes the charge according to the position of the focus P of the variable focus lens 10. The charge distribution unit 32 has: transfer control electrodes E1, E2, E3, E4 (transfer control electrodes) and a discharge control electrode ED. Signal lines are connected to the transfer control electrodes E1, E2, E3, E4, respectively. The transfer control electrode E1 receives a control signal TG1. The transfer control electrode E2 receives a control signal TG2. The transfer control electrode E3 receives a control signal TG3. The transfer control electrode E4 receives a control signal TG4. The transfer control electrodes E1, E2, E3, E4 transfer the charge from the charge collection region 31 to any one of the charge readout regions R1, R2, R3, R4 according to the control signals TG1, TG2, TG3, TG4.

[0076] The signal line is connected to the discharge control electrode ED. The discharge control electrode ED receives a control signal TD. The discharge control electrode ED controls the transfer of charges from the charge collection region 31 to the drain 33 according to the control signal TD supplied from the signal line.

[0077] The power source 29 is connected to the drain 33. During the period when the photoelectric conversion unit PD receives light, the photoelectric conversion unit PD continues to generate charges. On the other hand, in the charge readout regions R1, R2, R3, and R4, during the period when the prescribed processing is performed on the charges, the charges are prohibited from being transferred to the charge readout regions R1, R2, R3, and R4. The prescribed processing performed on the charges refers to, for example, a readout operation. Therefore, the drain 33 receives the charges generated during the period when the charges are prohibited from being transferred to the charge readout regions R1, R2, R3, and R4. That is, during the period when the drain 33 receives the charges, the charges are not accumulated in the charge readout regions R1, R2, R3, and R4.

[0078] The charge readout regions R1, R2, R3, and R4 provide voltages corresponding to the transferred charges to the buffer amplifiers A1, A2, A3, and A4, respectively. The charge readout regions R1, R2, R3, and R4 differ from each other only in configuration and connection structure. Therefore, the charge readout region R1 will be described in detail.

[0079] like Figure 5 As shown, the charge readout region R1 includes a charge accumulation portion 41, a floating diffusion portion 42, and a reset drain 43. The charge accumulation portion 41 is adjacent to the charge collection region 31. The floating diffusion portion 42 is adjacent to the charge accumulation portion 41. In addition, the floating diffusion portion 42 is connected to the buffer amplifier A1 via an output line. The reset drain 43 is adjacent to the floating diffusion portion 42. The reset drain 43 is connected to the power supply 29 and receives the voltage VDD.

[0080] These regions are regions where charges are temporarily accumulated. And the transfer of charges between these regions is controlled by voltages supplied from some electrodes. The charge readout region R1 has a transfer gate electrode 44 and a reset gate electrode 45. The transfer gate electrode 44 controls the transfer of charges from the charge accumulation portion 41 to the floating diffusion portion 42 according to a control signal TX supplied from a signal line. The reset gate electrode 45 resets the floating diffusion portion 42 to a voltage VDD through a reset drain 43 according to a control signal RT supplied from a signal line.

[0081] The buffer amplifiers A1, A2, A3, and A4 differ from each other only in their configuration and connection structure. Therefore, the buffer amplifier A1 will be described in detail.

[0082] The buffer amplifier A1 includes a transistor TA and a transistor TS. The drain of the transistor TA is connected to the power supply 29. The gate of the transistor TA is connected to the floating diffusion 42 of the charge readout region R1. The source of the transistor TA is connected to the transistor TS. The transistor TS performs switching control of whether to output an output signal from the buffer amplifier A1. The drain of the transistor TS is connected to the source of the transistor TA. The gate of the transistor TS is connected to a signal line for a control signal SEL. The source of the transistor TS is connected to a signal line for an AD conversion circuit 28. The buffer amplifier A1 outputs a voltage corresponding to the charge accumulated in the floating diffusion 42 to the signal line according to the control signal SEL supplied to the gate of the transistor TS.

[0083] (Gate control circuit)

[0084] The gate control circuit 26 generates a control signal to be supplied to the pixel array 21 based on the control signal supplied from the pixel control unit 50. Figure 6 , Figure 7 , Figure 8 and Fig. 9 , the operation of the gate control circuit 26 is described.

[0085] Figure 6 The following conceptually shows a situation where the position of the focus P of the variable focus lens 10 changes periodically. The graph G6 shows the relationship between time (phase) and the position of the focus P. As shown in the graph G6, the position of the focus P changes periodically with the passage of time. For example, the position of the focus P changes in a sinusoidal shape with respect to the passage of time.

[0086] The position of the focus P of the variable focus lens 10 is represented by the closest point Pc, the farthest point Pd, and the central point Pm. The closest point Pc is the point with the shortest distance from the variable focus lens 10. For example, the distance from the variable focus lens 10 to the closest point Pc is represented by the distance Lc. The farthest point Pd is the point with the farthest distance from the variable focus lens 10. For example, the distance from the variable focus lens 10 to the farthest point Pd is represented by the distance Ld. The central point Pm is the center of the distance from the closest point Pc to the farthest point Pd. That is, the distance Lmc from the central point Pm to the closest point Pc is equal to the distance Lmd from the central point Pm to the farthest point Pd. The position of the focus P changes periodically between the closest point Pc and the farthest point Pd.

[0087] The shooting range B of the variable focus lens 10 can be set to any range from the nearest point Pc to the farthest point Pd. The shooting range B is determined by the shooting near point Fc and the shooting far point Fd. The shooting near point Fc and the shooting far point Fd are set between the nearest point Pc and the farthest point Pd. For example, by setting the shooting near point Fc at the position of the nearest point Pc and setting the shooting far point Fd at the position of the farthest point Pd, the shooting range B becomes maximum. Various shooting changes can be achieved by setting the shooting near point Fc and the shooting far point Fd. Several changes are described later as modified examples 1 to 4. The shooting near point Fc of the present embodiment is set between the nearest point Pc and the center point Pm. Moreover, the shooting far point Fd of the present embodiment is set between the farthest point Pd and the center point Pm. According to these settings, the shooting range B is a range including the center point Pm.

[0088] There may be various photographic objects in the photographic range B. For example, when there is a photographic object 100 on the side close to the variable focus lens 10, if the position of the focus P of the variable focus lens 10 is the position of the photographic object 100 (refer to Figure 7 If the position of the focus P of the variable focus lens 10 is not the position of the object 100 (refer to Figure 7 If the image is exposed by using the image P2 of the reference numeral, a clear image of the photographic object 100 cannot be obtained. Therefore, the photographic range B is divided into several parts. For example, Figure 6As shown, four parts are set in the shooting range B. These parts are called focus ranges BF1, BF2, BF3, and BF4. Here, the focus range BF1 is the focus range mentioned in the claims. In addition, the focus ranges BF2, BF3, and BF4 are the additional focus ranges mentioned in the claims. And, the way of changing the exposure action is for each of the focus ranges BF1, BF2, BF3, and BF4. The exposure action refers to the action of accumulating the charge obtained by exposure. And, the way of changing the exposure action means that the area where the charge obtained by exposure is accumulated is different in each of the focus ranges BF1, BF2, BF3, and BF4.

[0089] For example, when the position of the focus P is within the focus range BF1, the imaging sensor 15 accumulates the charge in the charge readout region R1. When the position of the focus P is within the focus range BF2, the imaging sensor 15 accumulates the charge in the charge readout region R2. When the position of the focus P is within the focus range BF3, the imaging sensor 15 accumulates the charge in the charge readout region R3. When the position of the focus P is within the focus range BF4, the imaging sensor 15 accumulates the charge in the charge readout region R4. In addition, the correspondence between the focus range and the charge readout region is not limited to the above-mentioned example, and can be appropriately set according to the structure or operation of the imaging device.

[0090] The position of the focus P is Figure 6 The image sensor 15 changes periodically as shown in the graph G6 of FIG. 1 . Thus, during one cycle of the change in the position of the focus P, for example, the position of the focus P passes through the focus ranges BF1, BF2, BF3, and BF4 twice each. Therefore, during one cycle, each time the position of the focus P passes through the focus ranges BF1, BF2, BF3, and BF4, the imaging sensor 15 distributes the charge to any one of the corresponding charge readout regions R1, R2, R3, and R4. Thus, for example, each time the position of the focus P passes through the focus range BF1, the charge obtained when the position of the focus P is in the focus range BF1 is accumulated. Therefore, even if the amount of charge accumulated in one exposure action (accumulation action) is small, by performing multiple exposure actions, the amount of charge used to obtain an image corresponding to the focus range BF1 can be increased. As a result, the brightness of the obtained image can be improved.

[0091] In this embodiment, the lengths of the exposure period S1 corresponding to the focal range BF1, the exposure period S2 corresponding to the focal range BF2, the exposure period S3 corresponding to the focal range BF3, and the exposure period S4 corresponding to the focal range BF4 are set to be equal to each other. In this case, the lengths of the focal ranges BF1 and BF4 are different from the lengths of the focal ranges BF2 and BF3.

[0092] The gate control circuit 26 will Figure 8 The control signals TG1, TG2, TG3, TG4, and TD shown in the timing diagram are provided to the pixel array 21. In addition, the control signal TG1 is a transfer control signal. In addition, the control signals TG2, TG3, and TG4 are additional transfer control signals. Moreover, the control signal TD is a discharge control signal.

[0093] First, the gate control circuit 26 is in the phase To Phase During the period S2, the following control signals TG1, TG2, TG3, TG4, and TD are applied to the pixel array 21. To Phase The period S2 corresponds to the focus range BF2. According to these control signals TG1, TG2, TG3, TG4, TD, charges are accumulated in the charge readout region R2. In addition, "LOW" means that the transfer of charges is prohibited. "HIGH" means that the transfer of charges is permitted.

[0094] TG1: LOW.

[0095] TG2:HIGH.

[0096] TG3: LOW.

[0097] TG4: LOW.

[0098] TD:LOW.

[0099] Next, the gate control circuit 26 switches from the phase To Phase During the period S1, the following control signals TG1, TG2, TG3, TG4, TD (first control signal) are provided to the pixel array 21. To Phase The period S1 corresponds to the focal range BF1. According to these control signals TG1, TG2, TG3, TG4, TD, charges are accumulated in the charge readout region R1.

[0100] TG1:HIGH.

[0101] TG2: LOW.

[0102] TG3: LOW.

[0103] TG4: LOW.

[0104] TD:LOW.

[0105] Next, the gate control circuit 26 switches from the phase To Phase During the period SD, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period SD is a non-shooting period. Charges are discharged to the drain 33 according to these control signals TG1, TG2, TG3, TG4, and TD.

[0106] TG1: LOW.

[0107] TG2: LOW.

[0108] TG3: LOW.

[0109] TG4: LOW.

[0110] TD: HIGH.

[0111] Next, the gate control circuit 26 switches from the phase To Phase During the period S1, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period S1 corresponds to the focal range BF1. According to these control signals TG1, TG2, TG3, TG4, TD, the charges are accumulated again in the charge readout region R1.

[0112] TG1:HIGH.

[0113] TG2: LOW.

[0114] TG3: LOW.

[0115] TG4: LOW.

[0116] TD:LOW.

[0117] Next, the gate control circuit 26 switches from the phase To Phase During the period S2, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period S2 corresponds to the focal range BF2. According to these control signals TG1, TG2, TG3, TG4, TD, the charges are accumulated again in the charge readout region R2.

[0118] TG1: LOW.

[0119] TG2:HIGH.

[0120] TG3: LOW.

[0121] TG4: LOW.

[0122] TD:LOW.

[0123] Next, the gate control circuit 26 switches from the phase To Phase During the period S3, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period S3 corresponds to the focus range BF3. According to these control signals TG1, TG2, TG3, TG4, TD, charges are accumulated in the charge readout region R3.

[0124] TG1: LOW.

[0125] TG2: LOW.

[0126] TG3:HIGH.

[0127] TG4: LOW.

[0128] TD:LOW.

[0129] Next, the gate control circuit 26 switches from the phase To Phase During the period S4, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period S4 corresponds to the focus range BF4. According to these control signals TG1, TG2, TG3, TG4, TD, charges are accumulated in the charge readout region R4.

[0130] TG1: LOW.

[0131] TG2: LOW.

[0132] TG3: LOW.

[0133] TG4:HIGH.

[0134] TD:LOW.

[0135] Next, the gate control circuit 26 switches from the phase To Phase During the period SD, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period SD is a non-shooting period. Charges are discharged to the drain 33 according to these control signals TG1, TG2, TG3, TG4, and TD.

[0136] TG1: LOW.

[0137] TG2: LOW.

[0138] TG3: LOW.

[0139] TG4: LOW.

[0140] TD: HIGH.

[0141] Next, the gate control circuit 26 switches from the phase To Phase During the period S4, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period S4 corresponds to the focal range BF4. According to these control signals TG1, TG2, TG3, TG4, TD, the charges are accumulated again in the charge readout region R4.

[0142] TG1: LOW.

[0143] TG2: LOW.

[0144] TG3: LOW.

[0145] TG4:HIGH.

[0146] TD:LOW.

[0147] Then, the gate control circuit 26 is in the phase To Phase During the period S3, the following control signals TG1, TG2, TG3, TG4, and TD are provided to the pixel array 21. To Phase The period corresponds to the focal range BF3. According to these control signals TG1, TG2, TG3, TG4, TD, the charges are accumulated again in the charge readout region R3.

[0148] TG1: LOW.

[0149] TG2: LOW.

[0150] TG3:HIGH.

[0151] TG4: LOW.

[0152] TD:LOW.

[0153] Through the above operation, one cycle of exposure operation at the position of the focal point P is completed. Thereafter, the above exposure operation is repeatedly performed during the frame period.

[0154] After the frame period has passed, the voltage corresponding to the charge accumulated in each charge readout region R1, R2, R3, and R4 is output to the AD conversion circuit 28 through the readout circuit 27. Then, the image processing unit 60 generates an image for each of the charge readout regions R1, R2, R3, and R4 using the signal output from the AD conversion circuit 28. As a result, the first to fourth partial images can be obtained. The image processing unit 60 can output the result as a partial image or as a composite image in which the partial images are composited into one image.

[0155] <Effects>

[0156] The imaging device 1 has a variable focus lens 10. During a frame period, the position of the focus P of the variable focus lens 10 changes periodically between the farthest point Pd and the closest point Pc. Furthermore, the gate control circuit 26 transfers the charge generated in the photoelectric conversion unit PD to the charge readout region R1 when the position of the focus P is located in the focus range BF1, and transfers the charge to the drain DR when the position of the focus P is located in the non-shooting range C. Furthermore, the gate control circuit 26 repeatedly performs the transfer to the charge readout region R1 and the transfer to the drain DR during the frame period. As a result, each time these transfer actions are repeated, the charge obtained when the position of the focus P is located in the focus range BF1 is accumulated in the charge readout region R1. That is, even if the amount of charge transferred in one transfer action is small, the amount of charge accumulated in the charge readout region R1 will increase by repeating the transfer action. Therefore, according to the increase in the amount of charge, the brightness of the obtained image can be improved.

[0157] The pixel circuit unit 20 of the imaging device 1 includes charge readout regions R2 to R4 in addition to the charge readout region R1. According to this configuration, a plurality of focus ranges BF1 to BF4 can be set in the imaging range B. Therefore, a focused and clear image can be obtained.

[0158] The gate control circuit 26 generates the first control signal and the second control signal so that the period S1 during which the charge is allowed to be transferred from the photoelectric conversion unit PD to the charge readout region R1 and the period S2 during which the charge is allowed to be transferred from the photoelectric conversion unit PD to the charge readout region R2 are equal to each other. According to this structure, the transfer operation can be switched at a constant time interval. Therefore, the control performed by the gate control circuit 26 can be simplified.

[0159] Moreover, switching the transfer operation at a constant time interval means that the exposure time of each of the focus ranges BF1 to BF4 is constant. Assuming that the intensity of the light incident on the imaging sensor 15 does not change over time, the amount of charge obtained for each of the focus ranges BF1 to BF4 is approximately constant when the exposure time is constant. The amount of charge ultimately corresponds to the brightness (brightness) of the image. In other words, the brightness of each image obtained for each of the focus ranges BF1 to BF4 can be made constant.

[0160] The gate control circuit 26 outputs the first control signal twice and the second control signal twice during one cycle of the change in the position of the focal point P. According to this configuration, the amount of charge transferred to the gate control circuit 26 increases. Therefore, the brightness of the obtained image can be further improved.

[0161] The variable focus lens 10 includes: a lens portion 11 through which light is transmitted; and a lens driving portion 12 that periodically changes the position of the focus P of the lens portion 11 by providing a lens driving signal to the lens portion 11. The gate control circuit 26 receives the lens driving signal from the lens driving portion 12. The gate control circuit 26 generates a first control signal and a second control signal based on the lens driving signal. According to this structure, the operation of the lens portion 11 can be synchronized with the operation of the pixel circuit portion 20.

[0162] In addition, the present invention is not limited to the above-mentioned embodiment. For example, the gate control circuit 26 may also output a signal based on Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 as well as Fig.14 The control signals shown in the timing diagram have been replaced by Figure 8 The timing diagram is shown.

[0163] <Modification 1>

[0164] In the embodiment, the shooting range B is set to a wider area from the vicinity of the closest point Pc to the vicinity of the farthest point Pd. That is, the shooting range B is set to an area that can be regarded as equivalent to the range from the closest point Pc to the farthest point Pd of the variable focus lens 10. The shooting range B can be set in a desired manner within the range from the closest point Pc to the farthest point Pd. Fig. 9 1 is a timing diagram showing variation 1. Fig. 9As shown in FIG. 1 , the shooting range B1 may be narrower than half the amplitude of the focal point P. Furthermore, the shooting range B1 may be set between the closest point Pc and the central point Pm. Furthermore, in the focal range (non-shooting range C) not included in the shooting range B1, all the charges generated in the photoelectric conversion unit PD are discharged to the drain DR. For example, the gate control circuit 26 Fig. 9 In the period SD shown, the control signal TD is set to HIGH. According to such a shooting range B1, the ranges of the focus ranges BF1, BF2, BF3, and BF4 can be narrowed. Therefore, the shooting object can be focused more precisely. In other words, a clearer image can be obtained.

[0165] <Modification 2>

[0166] In the operation of Modification 1, it is possible to focus more precisely on the photographic object. On the other hand, the photographing range B1 is limited. Therefore, in Modification 2, an operation is shown that can expand the photographing range while maintaining precise focus. Fig.10 A timing chart showing variation example 2.

[0167] In the second modification, the concept of a so-called subframe period is introduced. During the frame period, for example, the focus P is periodically changed N times repeatedly. The gate control circuit 26 performs an operation with the imaging range B2a as the object in n times of the N operations ( Fig.10 Part (a) of Fig.10 The period of one cycle shown in the timing diagram of the same modification example 1 is called the first subframe operation. The period in which the first subframe operation is repeated n times is called the first subframe period. In addition, the gate control circuit 26 performs the operation shown in other timing diagrams with the imaging range B2b as the object in the remaining (Nn) times ( Fig.10 Part (c) of Fig.10 (d) of the Fig.10 Part (c) of Fig.10 The period of one cycle shown in the part (d) of FIG. 1 is referred to as a second subframe operation. The period in which the second subframe operation is repeated n times is referred to as a second subframe period.

[0168] That is, the frame period includes a first sub-frame period in which a first sub-frame operation is performed a plurality of times and a second sub-frame period in which a second sub-frame operation is performed a plurality of times.

[0169] The shooting range B2b set in the second sub-frame operation does not overlap with the shooting range B2a set in the first sub-frame operation. That is, in the second sub-frame operation, the shooting range B2b is set in a different area from that in the first sub-frame operation. Fig.10 Part (c) of Fig.10As shown in part (d) of FIG. 1 , the shooting range B2b of the second sub-frame action can be set between the farthest point Pd and the central point Pm. In this way, in the action of the modified example 2, the shooting range B2a related to the first sub-frame action and the shooting range B2b related to the second sub-frame action are combined to form the overall shooting range B2. In other words, the shooting range B2 can be expanded, and the shooting object can be focused more precisely for each shooting range B2a and B2b.

[0170] In summary, the gate control circuit 26 sets the first subframe period and the second subframe period included in the frame period. In the first subframe period, the shooting range B2a is set between the central point Pm and the closest point Pc. In the second subframe period, the shooting range B2b is set between the central point Pm and the farthest point. According to this structure, a fine focus range can be set. In addition, a wider shooting range B2 can be set.

[0171] The number of subframe periods set in a frame period is not limited to 2. For example, a frame period may include a first subframe period during which a first subframe operation is performed multiple times, a second subframe period during which a second subframe operation is performed multiple times, and a third subframe period during which a third subframe operation is performed multiple times.

[0172] <Variation 3>

[0173] In the second modification, the imaging range B2a is set in the first subframe period (see Fig.10 (a) of the figure), the shooting range B2b is set in the second subframe period (refer to Fig.10 (c) part). These shooting ranges B2a and B2b do not overlap with each other in the moving direction of the focus P of the variable focus lens 10. The shooting range set for each subframe period is not limited to the range that does not overlap with each other. In other words, the shooting range set for each subframe period may also overlap with each other. The overlap may be completely consistent or partially overlapped.

[0174] Fig.11 and Fig.12 An example of a case where the imaging ranges overlap is shown. Fig.11 Part (a) shows the shooting range B2a during the first subframe period. Fig.11 Part (b) of FIG. 1 shows a timing chart in the first subframe period. The operation in the first subframe period is the same as that in the second modification.

[0175] Then, Fig.11 Part (c) of FIG. 1 represents the shooting range B2a' during the second subframe period. Fig.11Part (d) of FIG. 1 shows a timing diagram in the second subframe period. The shooting range B2a in the first subframe period is set between the central point Pm and the closest point Pc. The shooting range B2a' in the second subframe period is also set between the central point Pm and the closest point Pc. Fig.11 Part (c) of Fig.11 As shown in part (d) of FIG. 1 , in the second subframe operation repeatedly performed in the second subframe period, the control signals TG1 to TG4 and TD are outputted with a delay period ΔS from the time when the position of the focal point P is the center point Pm. Fig.11 As shown in part (c) of FIG. 1 , the focal ranges BF1 ′ to BF4 ′ corresponding to the control signals TG1 to TG4 are set close to the closest point Pc.

[0176] In this way, Fig.12 As shown, in the first subframe period, the focus range BF1 to BF4 is set in the shooting range B2a. Similarly, in the second subframe period, the focus range BF1' to BF4' is set in the shooting range B2a'. These focus ranges BF1 to BF4 and BF1' to BF4' constitute an overlapping range BD. And, in this overlapping range BD, images Q1 to Q4 are obtained from the first subframe period. In addition, in this overlapping range BD, images Q1' to Q4' are obtained from the second subframe period.

[0177] The shooting range formed by the images Q1 to Q4 and the shooting range formed by the images Q1' to Q4' have an overlapping range BD that overlaps each other. On the other hand, in the overlapping range BD, the focus ranges BF1 to BF4 corresponding to the images Q1 to Q4 and the focus ranges BF1' to BF4' corresponding to the images Q1' to Q4' are different from each other. That is, according to the operation of the modification example 3, by dividing the same range into focus ranges of different partitions, a plurality of images Q1 to Q4 and Q1' to Q4' can be obtained.

[0178] That is, the subframe operation of Modification 3 can obtain a plurality of images Q1 to Q4 and Q1' to Q4' having different focus ranges in the overlap range BD. As a result, a clear image can be obtained when photographing a subject having a complex concavoconvex shape.

[0179] <Variation 4>

[0180] The focus P passes through the same focus range BF1, BF2, BF3, BF4 twice during one cycle. In addition, in the operation of the embodiment and modified examples 1 and 2, the focus P performs a transfer operation twice in each focus range BF1, BF2, BF3, BF4 during one cycle. However, the transfer operation may be performed only once during one cycle of the focus P.

[0181] Fig.13 Part (a) of Fig.13 Part (b) of FIG. 1 shows a timing diagram of variant example 4. Fig.13 As shown in part (a) of , even if the change in the position of the focus P is a sine wave as shown in the graph G11a, there may be a case where the waveform of the reference signal obtained from the variable focus lens 10 is distorted as shown in the graph G11b. Even in this case, the focus P passes through the same focus range BF1, BF2, BF3, BF4 twice. However, it is difficult to accurately perform transfer control based on the accurate knowledge of the moment of the first passage and the moment of the second passage. If the moment is staggered, it may occur that the charge accumulated in a certain charge readout area comes from two focus ranges. In addition, even if there is no distortion in the waveform of the reference signal, the same situation will occur when a phase shift occurs between the waveform representing the actual change of the focus P and the waveform of the reference signal.

[0182] Therefore, the operation of the modification example 4 is to perform only one transfer operation to the charge readout regions R1, R2, R3, and R4 during the period when the focus P passes through one cycle. According to such an operation, the influence of the unintentional offset between the waveform representing the actual change of the focus P and the reference signal can be suppressed. The unintentional offset includes the distortion and phase shift of the above-mentioned waveform. In other words, according to this structure, the synchronization condition between the periodic movement of the position of the focus of the variable focus lens 10 and the transfer operation performed by the gate control circuit 26 can be relaxed.

[0183] <Variation 5>

[0184] In the operation of the embodiment and the modifications 1 to 4, the transfer time from the photoelectric conversion unit PD to the charge readout regions R1, R2, R3, and R4 is constant. Figure 8 As shown in part (b), the periods S1, S2, S3, and S4 of the output control signals TG1, TG2, TG3, and TG4 are equal to each other. That is, in the actions of the embodiment and variants 1 to 4, time is selected as the basis for the action. Time can also be understood as a phase. Depending on the frequency of the focus P, the movement amount of the focus P per unit time is different. In this way, when the time is constant, the focus range is different from each other according to the frequency of the focus P.

[0185] For example, the focus ranges BF1, BF2, BF3, and BF4 may be selected instead of time as the basis for the action. Fig.14 As shown in part (a) of FIG. 1 , the focal ranges BF1, BF2, BF3, and BF4 are constant. Fig.14As shown in part (b) of FIG. 1 , the periods S1 , S2 , S3 , and S4 of the output control signals TG1 , TG2 , TG3 , and TG4 are adjusted. Therefore, the lengths of the periods S1 , S2 , S3 , and S4 are not constant.

[0186] In summary, the gate control circuit 26 generates the first control signal and the second control signal so that the amount of change in the position of the focus P during the period S1 during which the charge is allowed to transfer from the photoelectric conversion unit PD to the charge readout region R1 is equal to the amount of change in the position of the focus P during the period S2 during which the charge is allowed to transfer from the photoelectric conversion unit PD to the charge readout region R2. According to this structure, the length of each focus range can be made constant.

[0187] In addition, as described in the effect of the embodiment, the length of each period S1 to S4 corresponds to the brightness of each image. As in the embodiment, when the length of each period S1 to S4 is made constant, the brightness of each image can be made constant. On the other hand, as in Modification 5, when the periods S1 to S4 are set in such a way as to make the length of the focal range constant, the lengths of the periods S1, S2, S3, and S4 are not constant. As a result, the brightness of each image may be different. Therefore, in Modification 5, the brightness of the image may also be corrected (brightness correction). For example, the image obtained for each of the focal ranges BF1 to BF4 may be multiplied by a correction coefficient corresponding to the length of the period S1 to S4.

[0188] Modifications 1 to 4 show modifications related to timing charts. As other modifications, hardware modifications such as those shown in modifications 6 and 7 can also be applied.

[0189] <Variation 6>

[0190] In the embodiment, in the charge readout region R1 and the like, a so-called two-stage transfer structure is adopted. Fig.15 As shown in the imaging device 1A of the modification 6, the charge readout region R1s may also adopt a one-stage transfer structure instead of a two-stage transfer structure. In the charge readout region R1s, the transfer gate electrode 44 is omitted. The charge readout region R1s is a member in which the charge accumulation portion 41 and the floating diffusion portion 42 are electrically integrated. With such a structure, the structure of the charge readout region R1s can be simplified.

[0191] <Variation 7>

[0192] The pixel 22 of the embodiment includes: a photoelectric conversion unit PD; four charge readout regions R1, R2, R3, R4; four buffer amplifiers A1, A2, A3, A4 and a drain DR. The number of charge readout regions and buffer amplifiers corresponds to the number of focus ranges set in the shooting range. In the embodiment, the number of focus ranges set in the shooting range is 4. Therefore, the number of charge readout regions and buffer amplifiers is 4, respectively.

[0193] The number of focus ranges set in the shooting range may be 1, 2, or 3. In addition, the number of focus ranges set in the shooting range may be 5 or more. For example, when the number of focus ranges set in the shooting range is 1, Fig.16 As shown, the pixel 22A constituting the pixel circuit section 20A may include a photoelectric conversion section PD, one charge readout region R1 , one buffer amplifier A1 , and a drain DR.

[0194] like Fig.17 As shown, the pixel 22A has a light detection unit 22aA and an amplifier unit 22bA. The light detection unit 22aA has a photoelectric conversion unit PD and a charge transfer unit 30A. The charge transfer unit 30A has a charge collection region 31, a drain 33, and a charge readout region R1. In addition, the amplifier unit 22bA has a buffer amplifier A1.

[0195] like Fig.18 As shown in part (a) of FIG. 1 , in modification 7, a focal range BF1 is set in the shooting range B. That is, the shooting range B coincides with the focal range BF1. And, when the focal position of the variable focus lens 10 is located in the focal range BF1, the gate control circuit 26 outputs the control signal TG1 (HIGH) and outputs the control signal TD (LOW). When the focal position of the variable focus lens 10 is located in the non-shooting range C, the gate control circuit 26 outputs the control signal TG1 (LOW) and outputs the control signal TD (HIGH). According to this control, during one cycle of the focal position, two moments of accumulating charges in the charge transfer unit 30A are generated.

[0196] The imaging device 1A including the pixel 22A according to the modification 7 can also obtain the same effects as those of the imaging device 1 according to the embodiment.

[0197] <Variation 8>

[0198] like Figure 8As shown in part (b) of the embodiment, the imaging device 1 of the embodiment sets the exposure period S1 corresponding to the focal range BF1 immediately after setting the exposure period S2 corresponding to the focal range BF2. That is, the focal ranges BF1, BF2, BF3, and BF4 in the imaging device 1 of the embodiment are adjacent to each other. The setting of the focal ranges BF1, BF2, BF3, and BF4 is not limited to the case where they are adjacent to each other.

[0199] like Fig.19 As shown, the variable focus lens 10 can set the focus inside the shooting range B. In the modification 8, the focus range BF1 is set at the position closest to the variable focus lens 10. The focus range BF4 is set at the position farthest from the variable focus lens 10. Here, a non-shooting range C is set between the focus range BF1 and the focus range BF2. Similarly, a non-shooting range C is also set between the focus range BF3 and the focus range BF4, and a non-shooting range C is also set between the focus range BF2 and the focus range BF3. That is, in the operation of the modification 8, in the direction away from the variable focus lens 10, each area is set in the order of the non-shooting range C, the focus range BF1, the non-shooting range C, the focus range BF2, the non-shooting range C, the focus range BF3, the non-shooting range C, the focus range BF4 and the non-shooting range C.

[0200] According to such setting, when the focus position exists in the focus range BF1 (refer to Fig.19 The charge transfer operation to the charge readout region is also called exposure operation. Similarly, when the focus position is within the focus range BF2, BF3, BF4 (refer to Fig.19 The charges are transferred to the charge readout regions R2, R3, R4 respectively.

[0201] As an example, the duration of the action of transferring the charge to the charge readout region (S1 to S4) is about 200 nanoseconds to 2000 nanoseconds. In other words, the duration of the action of transferring the charge to the charge readout region is the exposure time. When the focus is in the non-shooting range C, the duration (SD) of the action of discharging the charge to the charge discharging region is also roughly the same. In addition, as an example, the time interval (T) after the exposure action corresponding to the focus range BF1 is performed until the exposure action corresponding to the focus range BF1 is performed again is TAG ) is about 14.5 microseconds. Moreover, the frame period (T frame ) is about 10 milliseconds.

[0202] The operation of Modification Example 8 is described using a timing diagram. Fig. 20As shown in part (a) of FIG. 1 , the shooting range B of the modification 8 includes: a focus range BF1 set near the closest point Pc; a focus range BF2 including the central point Pm; a focus range BF4 set near the farthest point Pd; and a focus range BF3 set between the focus range BF2 and the focus range BF4. A non-shooting range C is set between each of the focus ranges BF1, BF2, BF3, and BF4.

[0203] like Fig. 20 As shown in (b), first, during the period S2 when the focus exists in the focus range BF2, the gate control circuit 26 transfers the charge to the charge readout region R2. Next, during the period SD when the focus exists in the non-shooting range C between the focus range BF2 and the focus range BF1, the gate control circuit 26 discharges the charge to the drain DR. Next, during the period S1 when the focus exists in the focus range BF1, the gate control circuit 26 transfers the charge to the charge readout region R1. And, during the period SD when the focus exists in the non-shooting range C between the focus range BF1 and the focus range BF2, the gate control circuit 26 again discharges the charge to the drain DR. As described above, the gate control circuit 26 alternately performs the action of transferring the charge to the charge readout regions R1, R2, R3, and R4 and the action of discharging the charge to the drain DR.

[0204] That is, the gate control circuit 26 of the modified example 8 performs the action of outputting the transfer control signal, and after the action of outputting the transfer control signal, performs the action of outputting the discharge control signal, and after the action of outputting the discharge control signal, performs the action of outputting the additional transfer control signal, and after the action of outputting the additional transfer control signal, performs the action of outputting the discharge control signal again. According to this structure, each focal range can be discretely set within a narrow range. As a result, since the focal range in which the light from different focal points is averaged is narrowed, the clarity of the image in each focal range can be improved.

[0205] Furthermore, according to such an operation, for example, before and after the transfer operation to the charge readout region R2 is switched to the transfer operation to the charge readout region R1, the charge to be transferred to the charge readout region R2 is not transferred to the charge readout region R1. In other words, according to such an operation, the charge to be transferred to the charge readout region R1 and the charge to be transferred to the charge readout region R2 can be reliably separated.

[0206] Description of reference numerals:

[0207] 1: imaging device, 10: variable focus lens, 11: lens unit, 12: lens driving unit, 15: imaging sensor, 20: pixel circuit unit, 21: pixel array, 25: peripheral circuit, 26: gate control circuit (control mechanism), 27: readout circuit (signal readout mechanism), 50: pixel control unit, 60: image processing unit, B: imaging range, BF1, BF2, BF3, BF4: focal range, DR: drain (charge discharge area), E1, E2, E3, E4: transfer control electrode, ED: discharge control electrode, P: focal point, Pc: nearest point, PD: photoelectric conversion unit, Pd: farthest point, Pm: center point, R1, R1s, R2, R3, R4: charge readout area

Claims

1. A photographing device, wherein: The photographing device comprises: A variable focus lens, in which the position of the focal point changes periodically between the farthest point and the closest point during a frame; as well as a pixel circuit unit, arranged so as to overlap with the optical axis of the variable focus lens, receiving light passing through the variable focus lens, and outputting a signal corresponding to the light, The pixel circuit unit comprises: a photoelectric conversion unit that converts the light into electric charges; A charge readout region is disposed close to the photoelectric conversion unit; a transfer control electrode, disposed between the photoelectric conversion unit and the charge readout region, and receiving a transfer control signal for charge transfer between the photoelectric conversion unit and the charge readout region; one or more additional charge readout regions, provided proximate to the photoelectric conversion unit and separated from the charge readout region; one or more additional transfer control electrodes, disposed between the photoelectric conversion unit and the additional charge readout region, receiving an additional transfer control signal for charge transfer between the photoelectric conversion unit and the additional charge readout region, a charge discharge region which is provided close to the photoelectric conversion section and separated from the charge readout region and discharges the charge which is not used for reading out a signal corresponding to the light; a discharge control electrode, disposed between the photoelectric conversion unit and the charge discharge region, and receiving a discharge control signal for charge transfer between the photoelectric conversion unit and the charge discharge region; a control mechanism that applies the transfer control signal to the transfer control electrode and applies the discharge control signal to the discharge control electrode in correspondence with the position of the focus of the variable focus lens; as well as a signal reading mechanism that outputs the signal corresponding to the amount of charge transferred to the charge reading region, The control mechanism repeatedly performs the following actions during the frame period: outputting the transfer control signal when the focus position is within the focus range set in the shooting range; outputting the ejection control signal when the focus position is within the non-shooting range that does not overlap with the shooting range; and outputting the additional transfer control signal when the focus position is set in the shooting range and within the additional focus range that does not overlap with the focus range. The signal readout mechanism outputs the signal corresponding to the amount of charge transferred to the charge readout region after the frame period has elapsed, and also outputs the signal corresponding to the amount of charge transferred to the additional charge readout region.

2. The photographing device according to claim 1, wherein: The control mechanism generates the transfer control signal and the additional transfer control signal so that the length of the period during which the charge is allowed to be transferred from the photoelectric conversion unit to the charge readout region and the length of the period during which the charge is allowed to be transferred from the photoelectric conversion unit to one or more of the additional charge readout regions are equal to each other.

3. The photographing device according to claim 1, wherein: The control mechanism generates the transfer control signal and the additional transfer control signal so that the amount by which the position of the focal point changes while allowing the charge to transfer from the photoelectric conversion unit to the charge readout region and the amount by which the position of the focal point changes while allowing the charge to transfer from the photoelectric conversion unit to one or more of the additional charge readout regions are equal to each other.

4. The photographing device according to claim 1, wherein: The control unit sets a plurality of subframe periods included in the frame period. The control unit sets the imaging range for each of the plurality of sub-frame periods.

5. The photographing device according to claim 2, wherein: The control unit sets a plurality of subframe periods included in the frame period. The control unit sets the imaging range for each of the plurality of sub-frame periods.

6. The photographing device according to claim 3, wherein: The control unit sets a plurality of subframe periods included in the frame period. The control unit sets the imaging range for each of the plurality of sub-frame periods.

7. The photographing device according to claim 4, wherein: The imaging ranges set for each of the plurality of sub-frame periods do not overlap with each other.

8. The photographing device according to claim 4, wherein: The imaging ranges set for each of the plurality of sub-frame periods overlap with each other.

9. The photographing device according to any one of claims 1 to 8, wherein: The control mechanism performs an operation of outputting the transition control signal twice during one cycle of the change in the position of the focal point.

10. The photographing device according to any one of claims 1 to 8, wherein: The control mechanism performs an operation of outputting the transition control signal once during one cycle of the change in the position of the focal point.

11. The photographing device according to any one of claims 1 to 8, wherein: The variable focus lens comprises: A lens portion through which the light passes; and a lens driving unit that periodically changes the position of the focal point of the lens unit by supplying a lens driving signal to the lens unit; The imaging device further includes a pixel control unit that receives the lens driving signal from the lens driving unit and provides a control signal for the pixel circuit unit to the pixel circuit unit based on the lens driving signal.

12. The photographing device according to claim 9, wherein: The variable focus lens comprises: A lens portion through which the light passes; and a lens driving unit that periodically changes the position of the focal point of the lens unit by supplying a lens driving signal to the lens unit; The imaging device further includes a pixel control unit that receives the lens driving signal from the lens driving unit and provides a control signal for the pixel circuit unit to the pixel circuit unit based on the lens driving signal.

13. The photographing device according to claim 10, wherein: The variable focus lens comprises: A lens portion through which the light passes; and a lens driving unit that periodically changes the position of the focal point of the lens unit by supplying a lens driving signal to the lens unit; The imaging device further includes a pixel control unit that receives the lens driving signal from the lens driving unit and provides a control signal for the pixel circuit unit to the pixel circuit unit based on the lens driving signal.

14. The photographing device according to any one of claims 1 to 8, wherein: The charge readout region has a two-level transfer structure, The secondary transfer structure is composed of the following parts: a charge accumulation section that receives the charge from the photoelectric conversion section; a floating diffusion portion receiving the charge from the charge accumulation portion and connected to the signal readout mechanism; a reset drain receiving the charge from the floating diffusion; a transfer gate electrode for controlling the charge to be transferred from the charge accumulation portion to the floating diffusion portion; as well as The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

15. The photographing device according to claim 9, wherein: The charge readout region has a two-level transfer structure, The secondary transfer structure is composed of the following parts: a charge accumulation section that receives the charge from the photoelectric conversion section; a floating diffusion portion receiving the charge from the charge accumulation portion and connected to the signal readout mechanism; a reset drain receiving the charge from the floating diffusion; a transfer gate electrode for controlling the charge to be transferred from the charge accumulation portion to the floating diffusion portion; as well as The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

16. The photographing device according to claim 10, wherein: The charge readout region has a two-level transfer structure, The secondary transfer structure is composed of the following parts: a charge accumulation section that receives the charge from the photoelectric conversion section; a floating diffusion portion receiving the charge from the charge accumulation portion and connected to the signal readout mechanism; a reset drain receiving the charge from the floating diffusion; a transfer gate electrode for controlling the charge to be transferred from the charge accumulation portion to the floating diffusion portion; as well as The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

17. The photographing device according to claim 11, wherein: The charge readout region has a two-level transfer structure, The secondary transfer structure is composed of the following parts: a charge accumulation section that receives the charge from the photoelectric conversion section; a floating diffusion portion receiving the charge from the charge accumulation portion and connected to the signal readout mechanism; a reset drain receiving the charge from the floating diffusion; a transfer gate electrode for controlling the charge to be transferred from the charge accumulation portion to the floating diffusion portion; as well as The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

18. The photographing device according to any one of claims 1 to 8, wherein: The charge readout region has a primary transfer structure, The primary transfer structure is composed of the following parts: a floating diffusion portion receiving the charges from the photoelectric conversion portion; a reset drain receiving the charge from the floating diffusion; and The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

19. The photographing device according to claim 9, wherein: The charge readout region has a primary transfer structure, The primary transfer structure is composed of the following parts: a floating diffusion portion receiving the charges from the photoelectric conversion portion; a reset drain receiving the charge from the floating diffusion; and The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

20. The photographing device according to claim 10, wherein: The charge readout region has a primary transfer structure, The primary transfer structure is composed of the following parts: a floating diffusion portion receiving the charges from the photoelectric conversion portion; a reset drain receiving the charge from the floating diffusion; and The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

21. The photographing device according to claim 11, wherein: The charge readout region has a primary transfer structure, The primary transfer structure is composed of the following parts: a floating diffusion portion receiving the charges from the photoelectric conversion portion; a reset drain receiving the charge from the floating diffusion; and The reset gate electrode controls the charge to be transferred from the floating diffusion to the reset drain.

22. The photographing device according to claim 1, wherein: The control mechanism performs the following actions: outputting the transfer control signal, After the transfer control signal is output, the discharge control signal is output. After the action of outputting the discharge control signal is performed, the action of outputting the additional transfer control signal is performed, After the operation of outputting the additional transfer control signal is performed, the operation of outputting the discharge control signal is performed again.

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