JP2017112420A - Imaging element and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging element and an imaging device capable of using the charges, generated in a photodiode, effectively.SOLUTION: An imaging element includes a photoelectric conversion part for generating charges by performing photoelectric conversion of incident light, and a plurality of pixels having first and second reading parts connected with the photoelectric conversion part. The first reading part has a first charge voltage conversion part for converting the charges, transferred from the photoelectric conversion part, into a voltage, and a first output part for outputting an output signal corresponding to the voltage of the first charge voltage conversion part. The second reading part has a second charge voltage conversion part for converting the charges, transferred from the photoelectric conversion part, into a voltage, and a second output part for outputting an output signal corresponding to the voltage of the second charge voltage conversion part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging element and an imaging apparatus.

  A global shutter type imaging device is known (for example, Patent Document 1). The prior art has a problem that charges generated in the photodiode cannot be effectively used.

JP 2004-297089 A

The image pickup device according to claim 1 includes a plurality of pixels each including a photoelectric conversion unit that photoelectrically converts incident light to generate a charge, and first and second readout units connected to the photoelectric conversion unit, A first reading unit configured to convert a charge transferred from the photoelectric conversion unit into a voltage; a first output unit configured to output an output signal corresponding to the voltage of the first charge voltage conversion unit; And the second reading unit outputs a second charge-voltage conversion unit that converts the charge transferred from the photoelectric conversion unit into a voltage, and an output signal corresponding to the voltage of the second charge-voltage conversion unit. And a second output unit.
An imaging device according to a seventh aspect creates a first display image based on the imaging element according to any one of the first to sixth aspects and an output signal output from the first output unit. And an image creating unit that creates a second display image based on an output signal output from the second output unit, and an image display unit that alternately displays the first display image and the second display image. Prepare.
An imaging apparatus according to an eighth aspect includes the imaging element according to any one of claims 2 to 6, an open state that does not block incident light on the imaging element, and an incidence on the imaging element. A shutter device capable of switching between a light blocking state and a light blocking state, wherein the first reading unit converts the charge generated by the photoelectric conversion unit during the first period in which the shutter device is in the open state into the first charge. Then, the output signal corresponding to the electric charge is output from the first output unit, and the second readout unit is configured to output a first signal that is not overlapped with the first period when the shutter device is in the open state. The charge generated by the photoelectric conversion unit in two periods is transferred to the second charge holding unit, and then an output signal corresponding to the charge is output from the second output unit, and the shutter device includes the shutter device. Is in the open state before The charge generated by the photoelectric conversion unit in the third period after the first period and the second period is switched to the light-shielding state and held in the photoelectric conversion unit, and the first reading unit is connected to the shutter device. After the output from the first output unit, the output signal based on the charge generated by the photoelectric conversion unit in the first period is output from the first output unit. Transfer to the first charge holding unit.
An imaging device according to an eleventh aspect includes the imaging element according to any one of the second to sixth aspects, and a projection unit that projects predetermined modulated light onto a subject, wherein the first reading unit includes: , The photoelectric conversion unit transfers the charge generated by photoelectrically converting a part of the reflected light of the modulated light to the first charge holding unit, and outputs an output signal based on the charge from the first output unit, The second reading unit transfers the charge generated by the photoelectric conversion unit photoelectrically converting the remaining part of the reflected light of the modulated light to the second charge holding unit, and outputs based on the charge A distance calculation unit that outputs a signal from the second output unit and calculates a distance to the subject based on the output signal output from the first output unit and the output signal output from the second output unit Is provided.
The image pickup device according to claim 12 includes a plurality of pixels each including a photoelectric conversion unit that photoelectrically converts incident light to generate charges, and first and second readout units connected to the photoelectric conversion unit, The first reading unit includes: a first charge holding unit that holds the charge transferred from the photoelectric conversion unit; and a first output unit that outputs an output signal corresponding to the charge held in the first charge holding unit. And the second readout unit outputs a second charge holding unit that holds the charge transferred from the photoelectric conversion unit and an output signal corresponding to the charge held in the second charge holding unit. And an output unit.

It is a schematic diagram which shows the structure of the imaging device which concerns on the 1st Embodiment of this invention. 2 is a plan view schematically showing an imaging surface 10 of an imaging element 120. FIG. 2 is a circuit diagram of an imaging pixel 20. FIG. 3 is an enlarged schematic diagram of an imaging pixel 20 on the imaging surface 10. FIG. 2 is a cross-sectional view and a potential diagram of an imaging pixel 20. FIG. It is a timing chart of live view operation. It is a timing chart of live view operation. It is a timing chart of this imaging | photography. It is a timing chart of this imaging | photography. It is a timing chart of live view operation. It is a timing chart of live view operation. It is a timing chart of this imaging | photography. It is a timing chart of this imaging | photography. It is a timing chart of exposure auto bracketing photographing operation. It is a figure which shows typically the exposure time of high dynamic range composition. It is a schematic diagram which shows the structure of the imaging device which concerns on the 4th Embodiment of this invention. It is a timing chart of ranging operation.

(First embodiment)
FIG. 1 is a schematic diagram showing the configuration of the imaging apparatus according to the first embodiment of the present invention. The imaging device 100 includes an imaging optical system 110, an imaging element 120, a control circuit 130, a mechanical shutter 140, a display device 150, and a recording medium 160.

  The imaging optical system 110 forms a subject image on the imaging surface of the image sensor 120. The control circuit 130 controls the entire imaging apparatus 100. The mechanical shutter 140 is a so-called focal plane shutter, and is provided in the vicinity of the imaging surface of the imaging device 120. The display device 150 is a display device such as a liquid crystal display. The recording medium 160 is a portable recording medium such as a memory card.

  FIG. 2 is a plan view schematically showing the imaging surface 10 of the imaging device 120. A large number of imaging pixels 20 are two-dimensionally arranged on the imaging surface 10. The imaging pixel 20 corresponds to any one of red (R), green (G), and blue (B) color components, respectively. For example, the imaging pixel 20 corresponding to the red (R) color component outputs a photoelectric conversion signal (imaging signal) obtained by photoelectrically converting light of the red color component in the incident light. These three types of imaging pixels 20 form a so-called Bayer array.

  The control circuit 130 reads out the image pickup signal from all of the image pickup pixels when taking a recording image (so-called main image pickup). On the other hand, when shooting an image for live view, the control circuit 130 performs thinning readout of the imaging pixel 20 in accordance with the number of display pixels of the display device 150. In other words, the imaging signals are not read from all the imaging pixels 20, but the imaging signals are read only from the imaging pixels 20 every three rows, for example, according to the number of display pixels of the display device 150 (only one row of the three rows is read). The remaining two lines are skipped).

  Next, the configuration of the imaging pixel 20 will be described in detail with reference to FIGS. FIG. 3 is a circuit diagram of the imaging pixel 20. The imaging pixel 20 includes a photoelectric conversion unit PD, a first reading unit 21, a second reading unit 22, and a reset transistor R.

  The photoelectric conversion unit PD is a photodiode, and generates charges by photoelectrically converting incident light. The imaging pixel 20 is provided with a microlens (not shown), and incident light on the imaging pixel 20 is condensed on the photoelectric conversion unit PD by the microlens. The first reading unit 21 and the second reading unit 22 are connected in parallel to the cathode terminal of the photoelectric conversion unit PD.

  The first reading unit 21 includes a first charge holding unit SG1, a first transfer transistor TX1, a first charge voltage conversion unit FD1, a first amplification transistor SF1, a first output transistor S1, and a first output unit 23. And have. A first constant current source 25 is connected between the first output transistor S 1 and the first output unit 23. One first constant current source 25 exists for each column, and the imaging pixels 20 for all rows existing in one column are connected in parallel.

  The first charge holding unit SG1 is an N-type MOSFET. Although details will be described later, the first charge holding unit SG1 has a large capacity so that the charge generated by the photoelectric conversion unit PD can be temporarily held. The first transfer transistor TX1 is an N-type MOSFET and has a function of transferring the charge held in the first charge holding unit SG1 to the first charge voltage conversion unit FD1.

  The first charge voltage conversion unit FD1 is a so-called floating diffusion, and is held in the first charge holding unit SG1 by temporarily holding the charge transferred from the first charge holding unit SG1 by the first transfer transistor TX1. A potential corresponding to the amount of charge that has been stored is taken. That is, the charge held in the first charge holding unit SG1 is converted into a voltage. The first amplification transistor SF1 is an N-type MOSFET, and outputs an output signal corresponding to the amount of charge held in the first charge-voltage conversion unit FD1 (the potential of the first charge-voltage conversion unit FD1) to the first output transistor S1. Output to. The first output transistor S <b> 1 is an N-type MOSFET, and outputs the output signal output from the first amplification transistor SF <b> 1 to the first output unit 23. That is, the first output unit 23 outputs an output signal corresponding to the amount of charge held in the first charge-voltage conversion unit FD1.

  The drain terminal of the first charge holding unit SG1 is connected to the cathode terminal of the photoelectric conversion unit PD. The source terminal of the first charge holding unit SG1 is connected to the drain terminal of the first transfer transistor TX1. The source terminal of the first transfer transistor TX1 is connected to the source terminal of the reset transistor R, the gate terminal of the first amplification transistor SF1, and the first charge / voltage converter FD1. The drain terminal of the reset transistor R and the drain terminal of the first amplification transistor SF1 are connected to the power supply VDD. The source terminal of the first amplification transistor SF1 is connected to the drain terminal of the first output transistor S1. The source terminal of the first output transistor S <b> 1 is connected to the output terminal of the first constant current source 25 and the first output unit 23. The remaining terminals, that is, the gate terminal of the first charge holding unit SG1, the gate terminal of the first transfer transistor TX1, and the gate terminal of the first output transistor S1 are connected to a scanning circuit (not shown), respectively. Controlled by a circuit.

  In the following description, the control operation originally performed by the scanning circuit in the image sensor 120 is described as being performed by the control circuit 130 for convenience. In the following description, various operations described as being performed by the control circuit 130 may be performed by a circuit in the image sensor 120 (for example, a scanning circuit (not shown)), or a circuit outside the image sensor 120 ( For example, the control circuit 130 or other circuits may be used.

  The second readout unit 22 includes a second charge holding unit SG2, a second transfer transistor TX2, a second charge voltage conversion unit FD2, a second amplification transistor SF2, a second output transistor S2, and a second output unit 24. And have. A second constant current source 26 is connected between the second output transistor S2 and the second output unit 24. One second constant current source 26 exists for each column, and is connected in parallel for the imaging pixels 20 for all rows existing in one column. Since each of these units is the same as the first reading unit 21, a description thereof will be omitted. The reset transistor R is an N-type MOSFET and has a function of resetting the photoelectric conversion unit PD, the first charge holding unit SG1, the second charge holding unit SG2, the first charge voltage conversion unit FD1, and the second charge voltage conversion unit FD2. Have

  FIG. 4 is an enlarged schematic diagram of the imaging pixel 20 on the imaging surface 10. The photoelectric conversion unit PD is disposed in the upper right corner of the imaging pixel 20 and occupies a relatively large area with respect to the entire imaging pixel 20 so that the generated charges can be held to a certain degree. The first reading unit 21 and the second reading unit 22 are disposed on the lower side and the left side of the photoelectric conversion unit PD, respectively.

  The first charge holding unit SG1 and the second charge holding unit SG2 are disposed adjacent to the lower end and the left end of the photoelectric conversion unit PD, respectively. The first charge holding unit SG1 and the second charge holding unit SG2 have a relatively large capacitance (for example, a larger capacitance than the photoelectric conversion unit PD) so as to hold the charge generated in the photoelectric conversion unit PD. It is necessary to have it. Therefore, the first charge holding unit SG1 and the second charge holding unit SG2 have an area close to the photoelectric conversion unit PD. The first charge voltage conversion unit FD1 and the second charge voltage conversion unit FD2 have a larger capacitance than the first charge holding unit SG1 and the second charge holding unit SG2.

  The remaining area, that is, the first transfer transistor TX1, the second transfer transistor TX2, the first charge voltage conversion unit FD1, and the second charge are formed in the remaining area of about one-fourth of the entire imaging pixel 20. A voltage conversion unit FD2, a first amplification transistor SF1, a second amplification transistor SF2, a first output transistor S1, a second output transistor S2, and a reset transistor R are arranged.

  FIG. 5A is a diagram schematically showing the A-A ′ section of FIG. 3, and FIG. 5B is a potential diagram thereof. As shown in FIG. 5A, the photoelectric conversion unit PD includes a p + type region 31 on the light receiving surface side (insulating film 30 side) and an n type region 32 on the substrate side.

  The first charge holding unit SG <b> 1 includes a gate 33 formed on the insulating film 30, and an n − type region 34 and an n type region 35 formed under the insulating film 30. An n-type region 35 is formed in most of the area of the first charge holding unit SG1, and the n − -type region 34 is formed only in a part adjacent to the photoelectric conversion unit PD. Although not shown in FIG. 5A, it is desirable to cover the surface of the gate 33 with a light shielding layer formed of metal or the like to prevent light leakage.

  The first transfer transistor TX1 includes a gate 36 formed on the insulating film 30 and an n-type region 37 formed under the insulating film 30. An n − type region 38 is formed between the first charge holding unit SG1 and the first transfer transistor TX1. The first charge-voltage conversion unit FD1 adjacent to the first transfer transistor TX1 is configured by an n + type region 39 formed under the insulating film 30. Next to that is a gate 40 which functions as a reset transistor R. When a voltage of a predetermined level or higher is applied to the gate 40, that is, the gate terminal of the reset transistor R, the n + type region formed on the opposite side of the gate 40 from the n + type region 39 which is the first charge voltage conversion unit FD1. A current flows through 41.

  Next, the operation of each part will be described with reference to the potential diagram of FIG. Note that in the potential diagram of FIG. 5B, the lower the paper surface, the higher the potential.

  A predetermined high (H) level voltage or a predetermined low (L) level voltage is applied to the gate 33 of the first charge holding unit SG1. When an L level voltage is applied to the gate 33 of the first charge holding unit SG1, the potential of the n − type region 34 of the first charge holding unit SG1 is higher than the potential of the n type region 32 of the photoelectric conversion unit PD. Since it is low, the charge generated in the photoelectric conversion unit PD is accumulated in the n-type region 32 of the photoelectric conversion unit PD. When an H level voltage is applied to the gate 33 of the first charge holding unit SG1, the potentials of the n − type region 34 and the n type region 35 of the first charge holding unit SG1 are changed in the n type region 32 of the photoelectric conversion unit PD. Since the potential is higher than the potential, the charges accumulated in the n-type region 32 of the photoelectric conversion unit PD are transferred to the n-type region 35 of the first charge holding unit SG1.

  When an L level voltage is applied to the gate 36 of the first transfer transistor TX1, the potential of the n-type region 35 of the first charge holding unit SG1 is higher than the potential of the n-type region 37 of the first transfer transistor TX1. Therefore, the charges transferred to the n-type region 35 of the first charge holding unit SG1 are held in the n-type region 35 of the first charge holding unit SG1.

  When an H level voltage is applied to the gate 36 of the first transfer transistor TX1 when an L level voltage is applied to the gate 33 of the first charge holding unit SG1, the n-type region of the first transfer transistor TX1 is applied. The potential of 37 is higher than the potential of the n-type region 35 of the first charge holding unit SG1. As a result, the charges held in the n-type region 35 of the first charge holding unit SG1 are transferred to the first charge-voltage conversion unit FD1. The potential of the first charge-voltage conversion unit FD1 is determined according to the transferred charge amount. At this time, when an H level voltage is applied to the gate of the first output transistor S1, the amount of charge held by the first charge voltage conversion unit FD1 (of the first charge voltage conversion unit FD1) is supplied to the first output unit 23. An output signal having a magnitude corresponding to (potential) appears.

  The imaging pixel 20 configured as described above includes a first charge holding unit SG1 and a second charge holding unit SG2 that temporarily hold the charge generated by the photoelectric conversion unit PD. Therefore, when performing a so-called global shutter operation, it is possible to simultaneously hold charges corresponding to three captured images. Here, the global shutter operation is an operation in which all of the imaging pixels 20 perform both the start of charge generation (that is, shutter opening operation) and the end of charge generation (that is, shutter close operation) by the photoelectric conversion unit PD. Point to.

  Hereinafter, a method for simultaneously holding charges corresponding to three captured images will be described in detail. In the following description, the mechanical shutter 140 is not included in the configuration. First, when the first global shutter operation is completed, the charges accumulated in the photoelectric conversion units PD in all the imaging pixels 20 are transferred to the first charge holding unit SG1. In the following description, this operation is referred to as global transfer. Next, a second global shutter operation is performed before the output signals are read from the first charge holding units SG1 of all the imaging pixels 20. The charges generated by the photoelectric conversion unit PD in the second global shutter operation are transferred to the second charge holding unit SG2 by global transfer. Thereafter, before the output signals are read out from the first charge holding unit SG1 and the second charge holding unit SG2 of all the imaging pixels 20, that is, the charges transferred together by the first charge holding unit SG1 and the second charge holding unit SG2. While holding, a third global shutter operation is performed. The charge generated by the photoelectric conversion unit PD by the third global shutter operation can be held in the photoelectric conversion unit PD. As described above, the imaging pixel 20 simultaneously holds the charges corresponding to the three captured images at the three locations of the first charge holding unit SG1, the second charge holding unit SG2, and the photoelectric conversion unit PD, respectively. Is possible.

  Next, the live view function of the imaging apparatus 100 will be described. FIG. 6 is a timing chart of the live view operation. In the live view operation described below, “all the imaging pixels 20 used for creating the live view image” means the imaging pixels 20 to be subjected to thinning readout. That is, when thinning readout is performed, there are imaging pixels 20 that are not involved in the live view image, but such imaging pixels 20 are excluded from the following processing.

  First, at time t1, the control circuit 130 simultaneously resets the photoelectric conversion unit PD, the first charge holding unit SG1, and the second charge holding unit SG2 in all the imaging pixels 20 used for creating the live view image (shutter). Equivalent to opening operation). At subsequent time t2, the control circuit 130 simultaneously transfers the charge of the photoelectric conversion unit PD to the first charge holding unit SG1 in all the imaging pixels 20 used for creating the live view image (shutter closing operation, Global transfer, equivalent to the shutter opening operation in the next imaging).

  The charge transferred here is generated by photoelectric conversion by the photoelectric conversion unit PD during a period from time t1 to time t2. That is, it corresponds to an imaging signal in which a period from time t1 to time t2 is an exposure time. In other words, the above operation corresponds to a global shutter operation in which the shutter is opened at time t1 and the shutter is closed at time t2.

  Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the first reading unit 21 of the imaging pixels 20 in the first row. When the readout of the imaging signals from all rows is completed, the control circuit 130 creates a live view image based on the readout imaging signals and displays it on the display device 150.

  The readout time T1 is required to read out the imaging signals from all the rows to be read out. For example, when it is desired to display a live view image at 60 fps based on the imaging signal read from the first reading unit 21, the reading time T1 needs to be 1/60 second or less.

  At time t4 after the read time T1 from time t2, the control circuit 130 again simultaneously charges the photoelectric conversion unit PD to the first charge holding unit SG1 in all the imaging pixels 20 used for creating the live view image. Transfer (shutter closing operation, global transfer, equivalent to shutter opening operation in next imaging). Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the first reading unit 21 of the imaging pixel 20 in the first row, and creates and displays a live view image.

  The control circuit 130 repeats the above operation every read time T1. Thereby, a live view image based on the imaging signal read from the first reading unit 21 is created and displayed, for example, every 1/60 second.

  In parallel with the above operation, the control circuit 130 charges the photoelectric conversion unit PD in all the imaging pixels 20 used for creating the live view image at time t3 after half of the readout time T1 from time t2. Transfer to the second charge holding unit SG2 at the same time (shutter closing operation, global transfer, equivalent to shutter opening operation in the next imaging). The charge transferred here is generated by photoelectric conversion by the photoelectric conversion unit PD during a period from time t2 to time t3. That is, it corresponds to an imaging signal in which a period from time t2 to time t3 is an exposure time. In other words, the above operation corresponds to a global shutter operation in which the shutter is opened at time t2 and the shutter is closed at time t3.

  Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the second reading unit 22 of the imaging pixel 20 in the first row. When the readout of the imaging signals from all rows is completed, the control circuit 130 creates a live view image based on the readout imaging signals and displays it on the display device 150.

  The control circuit 130 repeats the above operation every read time T1. Thereby, a live view image based on the imaging signal read from the second reading unit 22 is created and displayed every 1/60 second, for example.

  As described above, the control circuit 130 reads the imaging signal from the first reading unit 21 and creates and displays the live view image, and reads the imaging signal from the second reading unit 22 and creates and displays the live view image. Are performed in parallel at a timing shifted by a half cycle. Accordingly, the live view image is displayed at a frame rate that is double that of the case where only one of the first reading unit 21 and the second reading unit 22 is used.

  Further, the photoelectric conversion unit PD is not reset except at the start of live view display. That is, it can be said that all the charges generated by the photoelectric conversion unit PD during the live view display are fully used.

  FIG. 7 is a timing chart of the live view operation focusing on one imaging pixel 20. First, at time t11, the control circuit 130 turns on and off the first charge holding unit SG1, the second charge holding unit SG2, the first transfer transistor TX1, the second transfer transistor TX2, and the reset transistor R (the voltage applied to the gate). By switching between H level and L level), the photoelectric conversion unit PD, the first charge holding unit SG1, and the second charge holding unit SG2 are simultaneously reset. At the subsequent time t12, the control circuit 130 transfers the charge from the photoelectric conversion unit PD to the first charge holding unit SG1 by turning on and off the first charge holding unit SG1. As shown in FIG. 7, the timing for turning off the first transfer transistor TX1, the second transfer transistor TX2, and the reset transistor R is higher than the timing for turning off the first charge holding unit SG1 and the second charge holding unit SG2. It is desirable to delay.

  At time t <b> 13, the control circuit 130 reads the imaging signal from the first reading unit 21. The control circuit 130 first turns on the first output transistor S1. Then, the reset transistor R is turned on / off while the first output transistor S1 is turned on, and then the first transfer transistor TX1 is turned on / off. Thereby, the charge held in the first charge holding unit SG1 is transferred to the first charge voltage conversion unit FD1, and an output signal having a magnitude corresponding to the amount of the charge is output to the first output unit 23. . Thereafter, the control circuit 130 turns off the first output transistor S1.

  At time t14 after time t13, the control circuit 130 transfers the charge from the photoelectric conversion unit PD to the second charge holding unit SG2 by turning on and off the second charge holding unit SG2. At time t <b> 15, the control circuit 130 reads the imaging signal from the second reading unit 22. The control circuit 130 first turns on the second output transistor S2. Then, the reset transistor R is turned on / off with the second output transistor S2 turned on, and then the second transfer transistor TX2 is turned on / off. As a result, the charge held in the second charge holding unit SG2 is transferred to the second charge voltage conversion unit FD2, and an output signal having a magnitude corresponding to the amount of the charge is output to the second output unit 24. . Thereafter, the second output transistor S2 is turned off.

  The control circuit 130 reads the imaging signal alternately from the first reading unit 21 and the second reading unit 22 by repeatedly performing the above operation.

  Next, main shooting (shooting for creating a recorded image) during the live view operation will be described. FIG. 8 is a timing chart of the actual photographing. Assume that a predetermined main photographing operation (for example, a full pressing operation of the release switch) is performed at time t21.

  When the readout of the imaging signal from the first readout unit 21 currently being executed at time t23 is completed, the control circuit 130 performs a predetermined transfer from time t22 when the charge transfer to the nearest second charge holding unit SG2 is performed. At time t24 when the exposure time T2 has elapsed, in all the imaging pixels 20, the charges of the photoelectric conversion units PD are simultaneously transferred to the first charge holding unit SG1.

  Further, at time t25 when a predetermined exposure time T3 (a time different from the exposure time T2) has elapsed from time t24, the control circuit 130 transfers the charge of the photoelectric conversion unit PD to the second charge holding unit SG2 in all the imaging pixels 20. To the same time.

  Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the first reading unit 21 of the imaging pixels 20 in the first row. In parallel with this, the control circuit 130 reads out the imaging signal for each row in order from the second reading unit 22 of the imaging pixel 20 in the first row. Thereby, from the image sensor 120, an image signal corresponding to the exposure time T2 and an image signal corresponding to the exposure time T3 are obtained simultaneously.

  When reading of the imaging signals from all rows is completed, the control circuit 130 creates a recording image based on the readout imaging signals and records it on the recording medium 160. For example, the first recording image based on the imaging signal read from the first reading unit 21 and the second recording image based on the imaging signal read from the second reading unit 22 may be recorded on the recording medium 160, or A single recording image may be created by combining two imaging signals and recorded on the recording medium 160. When the recording of the recorded image is completed, the control circuit 130 starts executing the operation from the time t1 in FIG. 6 again, and resumes the live view display.

  FIG. 9 is a timing chart of the main photographing focusing on one imaging pixel 20. At time t31, it is assumed that charges are transferred from the photoelectric conversion unit PD to the second charge holding unit SG2 for live view display. The control circuit 130 transfers the charge from the photoelectric conversion unit PD to the first charge holding unit SG1 by turning on and off the first charge holding unit SG1 at a time t32 when a predetermined exposure time T2 has elapsed from the time t31. The control circuit 130 transfers the charge from the photoelectric conversion unit PD to the second charge holding unit SG2 by turning on and off the second charge holding unit SG2 at a time t33 when a predetermined exposure time T3 has elapsed from the time t32.

  At subsequent time t <b> 34, the control circuit 130 simultaneously reads the imaging signal from the first reading unit 21 and the second reading unit 22. First, the control circuit 130 turns on the first output transistor S1 and the second output transistor S2 simultaneously. The control circuit 130 turns on and off the reset transistor R with the first output transistor S1 and the second output transistor S2 turned on, and then turns on and off the first transfer transistor TX1 and the second transfer transistor TX2. Thereby, the charge held in the first charge holding unit SG1 is transferred to the first charge voltage conversion unit FD1, and the charge held in the second charge holding unit SG2 is transferred to the second charge voltage conversion unit FD2. The transferred output signal having a magnitude corresponding to each charge amount is output to the first output unit 23 and the second output unit 24. Thereafter, the control circuit 130 turns off the first output transistor S1 and the second output transistor S2.

According to the imaging apparatus according to the first embodiment described above, the following operational effects can be obtained.
(1) The image sensor 120 includes a photoelectric conversion unit PD that photoelectrically converts incident light to generate charges, and an imaging pixel that includes a first reading unit 21 and a second reading unit 22 connected to the photoelectric conversion unit PD. A plurality of 20 are provided. The first reading unit 21 includes a first charge holding unit SG1 that temporarily holds the charge transferred from the photoelectric conversion unit PD, and a first charge voltage that converts the charge transferred from the first charge holding unit SG1 into a voltage. It has conversion part FD1, and the 1st output part 23 which outputs the output signal according to the voltage of 1st charge voltage conversion part FD1. Similarly, the second reading unit 22 temporarily holds the charge transferred from the photoelectric conversion unit PD, and the second charge holding unit SG2 that temporarily converts the charge transferred from the second charge holding unit SG2. A two-charge voltage conversion unit FD2, and a second output unit 24 that outputs an output signal corresponding to the voltage of the second charge-voltage conversion unit FD2. Since it did in this way, the electric charge which generate | occur | produced with the photodiode (photoelectric conversion part PD) can be used effectively.

(2) The capacitance of the first charge voltage conversion unit FD1 is larger than the capacitance of the first charge holding unit SG1. Similarly, the capacitance of the second charge voltage conversion unit FD2 is larger than the capacitance of the second charge holding unit SG2. That is, the capacitance increases in the order in which the charges generated by the photoelectric conversion unit PD are transferred. Since it did in this way, it can handle, without impairing the electric charge produced | generated by photoelectric conversion part PD.

(3) The first reading unit 21 outputs the output signal corresponding to the charge from the second output unit 24 from the first time when the charge is transferred from the photoelectric conversion unit PD to the second charge holding unit SG2. Charges generated by the photoelectric conversion unit PD within a period of up to two times are transferred to the first charge holding unit SG1. The second reading unit 22 starts from the third time when the charge is transferred from the photoelectric conversion unit PD to the first charge holding unit SG1 to the fourth time when the output signal corresponding to the charge is output from the first output unit 23. The charge generated by the photoelectric conversion unit PD within the period is transferred to the second charge holding unit SG2. Since it did in this way, the electric charge produced | generated by the photoelectric conversion part PD during the read-out operation in one read-out part can be transferred and utilized for the other read-out part, without discarding.

(4) The control circuit 130 creates a first display image based on the output signal output from the first output unit 23 and creates a second display image based on the output signal output from the second output unit 24. Functions as an image creation unit. The display device 150 functions as an image display unit that alternately displays the first display image and the second display image. Since it did in this way, a live view image can be displayed with a frame rate double the frame rate prescribed by the reading speed of an image pick-up signal (output signal).

(5) The first charge holding unit SG1 and the second charge holding unit SG2 have a so-called buried channel structure. As a result, unlike the so-called floating diffusion, a charge generated by the photoelectric conversion unit PD is accumulated in the first charge holding unit SG1 and the second charge holding unit SG2 without being damaged for a relatively long time. It is possible to leave.

(Second Embodiment)
The imaging apparatus according to the second embodiment has the same configuration as that of the imaging apparatus 100 according to the first embodiment, but the driving method of the imaging element 120 is different from that of the first embodiment. ing. In the following, an imaging apparatus according to the second embodiment will be described, focusing on differences from the first embodiment.

  In the first embodiment, a live view image is captured at an exposure time (for example, about 1/60 second) according to a frame rate (for example, 60 fps) of a live view display. In the present embodiment, live view display is performed at double speed as in the first embodiment, but the exposure time of each live view image is arbitrarily set.

  FIG. 10 is a timing chart of the live view operation. First, at time t41, the control circuit 130 simultaneously resets the photoelectric conversion unit PD and the first charge holding unit SG1 in all the imaging pixels 20 used for creating the live view image. At the time t42 after the predetermined exposure time T4 from the time t41, the control circuit 130 simultaneously charges the photoelectric conversion unit PD in the first charge holding unit SG1 in all the imaging pixels 20 used for creating the live view image. Forward.

  Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the first reading unit 21 of the imaging pixels 20 in the first row. Reading time T1 is required to read the imaging signals from all rows. At the time t45 when the read time T1 has elapsed from the time t42, the readout of the imaging signals from all the rows is completed. The control circuit 130 creates a live view image based on the read imaging signal and displays it on the display device 150.

  At time t45 when reading of the imaging signal is completed, the control circuit 130 resets the photoelectric conversion unit PD and the first charge holding unit SG1. At time t46, which is the exposure time T4 after time t45, the control circuit 130 simultaneously transfers the charge of the photoelectric conversion unit PD to the first charge holding unit SG1 for all the imaging pixels 20 used for creating the live view image. . Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the first reading unit 21 of the imaging pixel 20 in the first row, and creates and displays a live view image.

  The control circuit 130 repeats the above operation every reading time T1 + exposure time T4. Thereby, a live view image based on the imaging signal read from the first reading unit 21 is created and displayed every time T1 + T4 (for example, every 1/60 second). This live view image is an image taken at the exposure time T4.

  In parallel with the above operation, the control circuit 130 also creates and displays a live view image in the second reading unit 22 in the same manner. Consider a time t43 corresponding to the center of the period from time t41 to t45. At time t43, the control circuit 130 resets the photoelectric conversion unit PD and the second charge holding unit SG2. At time t44 after the exposure time T4 from time t43, the control circuit 130 simultaneously transfers the charge of the photoelectric conversion unit PD to the second charge holding unit SG2 for all the imaging pixels 20 used for creating the live view image. . Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the second readout unit 22 of the imaging pixel 20 in the first row, and creates and displays a live view image.

  The control circuit 130 repeats the above operation every reading time T1 + exposure time T4. Thereby, a live view image based on the imaging signal read from the second reading unit 22 is created and displayed every 1/60 second, for example. This live view image is an image taken at the exposure time T4.

  As described above, the control circuit 130 reads the imaging signal from the first reading unit 21 and creates and displays the live view image, and reads the imaging signal from the second reading unit 22 and creates and displays the live view image. Are performed in parallel at a timing shifted by a half cycle ((T1 + T4) / 2). Accordingly, the live view image is displayed at a frame rate that is double that of the case where only one of the first reading unit 21 and the second reading unit 22 is used.

  FIG. 11 is a timing chart of a live view operation focusing on one imaging pixel 20. First, at time t51, the control circuit 130 turns on the first charge holding unit SG1, the first transfer transistor TX1, and the reset transistor R (switches the voltage applied to the gate from L level to H level), thereby performing photoelectric conversion. The part PD and the first charge holding part SG1 are simultaneously reset.

  At time t52 after the exposure time T4 from time t51, the control circuit 130 turns on the first charge holding unit SG1, thereby transferring charges from the photoelectric conversion unit PD to the first charge holding unit SG1.

  At time t <b> 55, the control circuit 130 reads the imaging signal from the first reading unit 21. The control circuit 130 first turns on the first output transistor S1. The control circuit 130 turns on and off the reset transistor R with the first output transistor S1 turned on, and then turns on and off the first transfer transistor TX1. Thereby, the charge held in the first charge holding unit SG1 is transferred to the first charge voltage conversion unit FD1, and an output signal having a magnitude corresponding to the amount of the charge is output to the first output unit 23. . Thereafter, the control circuit 130 turns off the first output transistor S1.

  At time t53 after time t52, the control circuit 130 turns on the second charge holding unit SG2, the second transfer transistor TX2, and the reset transistor R (switches the voltage applied to the gate from L level to H level). Thus, the photoelectric conversion unit PD and the second charge holding unit SG2 are simultaneously reset.

  At time t54 after the exposure time T4 from time t53, the control circuit 130 turns on the second charge holding unit SG2, thereby transferring the charge from the photoelectric conversion unit PD to the second charge holding unit SG2.

  At time t <b> 56, the control circuit 130 reads the imaging signal from the second reading unit 22. The control circuit 130 first turns on the second output transistor S2. The control circuit 130 turns on and off the reset transistor R with the second output transistor S2 turned on, and then turns on and off the second transfer transistor TX2. As a result, the charge held in the second charge holding unit SG2 is transferred to the second charge voltage conversion unit FD2, and an output signal having a magnitude corresponding to the amount of the charge is output to the second output unit 24. . Thereafter, the control circuit 130 turns off the second output transistor S2.

  The control circuit 130 repeatedly reads out the imaging signal corresponding to the exposure time T4 from the first reading unit 21 and the second reading unit 22 by repeatedly performing the above operation.

  Next, actual photographing during the live view operation will be described. FIG. 12 is a timing chart of the actual photographing. Assume that a predetermined main photographing operation (for example, a full pressing operation of the release switch) is performed at time t61.

  When the readout of the imaging signal from the first readout unit 21 currently being executed at time t62 ends, the control circuit 130 simultaneously resets the photoelectric conversion unit PD and the first charge holding unit SG1 for all the imaging pixels 20. . The control circuit 130 simultaneously transfers the charge of the photoelectric conversion unit PD to the first charge holding unit SG1 for all the imaging pixels 20 at time t63 after a predetermined exposure time T5 from time t62.

  The control circuit 130 simultaneously resets the photoelectric conversion unit PD and the second charge holding unit SG2 for all the imaging pixels 20 at time t64 after time t63. The control circuit 130 simultaneously transfers the charge of the photoelectric conversion unit PD to the second charge holding unit SG2 for all the imaging pixels 20 at time t65 after a predetermined exposure time T6 from time t64.

  Thereafter, the control circuit 130 reads the imaging signal for each row in order from the first reading unit 21 of the imaging pixels 20 in the first row. In parallel with this, the control circuit 130 reads out the imaging signal for each row in order from the second reading unit 22 of the imaging pixel 20 in the first row. Thereby, from the image sensor 120, an image signal corresponding to the exposure time T5 and an image signal corresponding to the exposure time T6 are obtained simultaneously.

  When reading of the imaging signals from all rows is completed, the control circuit 130 creates a recording image based on the readout imaging signals and records it on the recording medium 160. For example, the first recording image based on the imaging signal read from the first reading unit 21 and the second recording image based on the imaging signal read from the second reading unit 22 may be recorded on the recording medium 160, or A single recording image may be created by combining two imaging signals and recorded on the recording medium 160.

  When the recording of the recorded image is completed, the control circuit 130 starts executing the operation from time t51 in FIG. 11 again, and resumes the live view display.

  FIG. 13 is a timing chart of the main imaging focusing on one imaging pixel 20. At time t71, the control circuit 130 turns on the reset transistor R, the first charge holding unit SG1, and the first transfer transistor TX1, thereby resetting the photoelectric conversion unit PD and the first charge holding unit SG1.

  The control circuit 130 transfers the charge from the photoelectric conversion unit PD to the first charge holding unit SG1 by turning on the first charge holding unit SG1 at time t72 when a predetermined exposure time T5 has elapsed from time t71.

  At time t73 after time t72, the control circuit 130 resets the photoelectric conversion unit PD and the second charge holding unit SG2 by turning on the reset transistor R, the second charge holding unit SG2, and the second transfer transistor TX2. To do.

  The control circuit 130 transfers the charge from the photoelectric conversion unit PD to the second charge holding unit SG2 by turning on the second charge holding unit SG2 at time t74 when a predetermined exposure time T6 has elapsed from time t73.

  At subsequent time t75, the control circuit 130 simultaneously reads out the imaging signal from the first reading unit 21 and the second reading unit 22. First, the control circuit 130 turns on the first output transistor S1 and the second output transistor S2 simultaneously. The control circuit 130 turns on and off the reset transistor R with the first output transistor S1 and the second output transistor S2 turned on, and then turns on and off the first transfer transistor TX1 and the second transfer transistor TX2. Thereby, the charge held in the first charge holding unit SG1 is transferred to the first charge voltage conversion unit FD1, and the charge held in the second charge holding unit SG2 is transferred to the second charge voltage conversion unit FD2. The output signals having the magnitudes corresponding to the respective charge amounts are output to the first output unit 23 and the second output unit 24. Thereafter, the control circuit 130 turns off the first output transistor S1 and the second output transistor S2.

  According to the imaging apparatus according to the second embodiment described above, the same operational effects as those of the first embodiment can be obtained.

(Third embodiment)
The imaging apparatus according to the third embodiment performs a function of performing exposure auto bracketing imaging and high-dynamic range synthesis (HDR synthesis) with the same configuration as the imaging apparatus 100 according to the first embodiment. It has a function. Of these two functions, the exposure auto bracketing photographing function will be described in detail first.

  FIG. 14 is a timing chart of the exposure auto bracketing shooting operation. It is assumed that a predetermined main photographing operation (for example, full pressing operation of the release switch) is performed at time t81. Further, it is assumed that readout of the live view imaging signal from the first readout unit 21 that is currently being executed ends at time t83 after time t81.

  The control circuit 130 resets the photoelectric conversion unit PD in the imaging pixels 20 in the first row at a time t82 that is a predetermined time T7 before the time t83. Thereafter, the control circuit 130 sequentially resets the photoelectric conversion unit PD for each row from time t82 to time t83, such as the second row, the third row, and so on. Here, the predetermined time T7 is a time required for the mechanical shutter 140 to travel, that is, a time necessary for switching the mechanical shutter 140 from the fully open state to the light-blocking state. is there. Thereafter, the control circuit 130 resets the first charge holding unit SG1 for all the imaging pixels 20 as soon as the readout of the live view imaging signal from the first readout unit 21 is completed. Similarly, the second charge holding unit SG2 resets the second charge holding unit SG2 for all the imaging pixels 20 as soon as the readout of the live view imaging signal from the second reading unit 22 is completed.

  The control circuit 130 transfers the charge of the photoelectric conversion unit PD to the first charge holding unit SG1 for the imaging pixels 20 in the first row at time t84 after a predetermined exposure time T8 from time t82. The control circuit 130 thereafter transfers the charge of the photoelectric conversion unit PD to the first charge holding unit SG1 for each row from time t84 to time t85 after a predetermined time T7, as in the second row, the third row,. Sequentially.

  The control circuit 130 transfers the charge of the photoelectric conversion unit PD to the second charge holding unit SG2 for the imaging pixels 20 in the first row at time t86 after a predetermined exposure time T9 from time t84. The control circuit 130 then transfers the charge of the photoelectric conversion unit PD to the second charge holding unit SG2 for each row from time t86 to time t87 after a predetermined time T7, as in the second row, third row,. Sequentially.

  The control circuit 130 starts running the mechanical shutter 140 at a time t88 after a predetermined exposure time T10 from the time t86, and puts the mechanical shutter 140 in a closed state (light shielding state). As described above, traveling of the mechanical shutter 140 requires a predetermined time T7. Therefore, the traveling of the mechanical shutter 140 is completed at the time t89 after the predetermined time T7 from the time t88, and the image sensor 120 is covered with the mechanical shutter 140 (light-shielding state).

  At time t89, the charge corresponding to the exposure time T10 is accumulated in the photoelectric conversion unit PD of the imaging pixel 20. Since the mechanical shutter 140 is closed, thereafter, the amount of charge accumulated in the photoelectric conversion unit PD of the imaging pixel 20 does not vary. That is, charges corresponding to the exposure time T10 are held in the photoelectric conversion unit PD.

  At time t89, the control circuit 130 reads the imaging signal for each row in order from the first reading unit 21 of the imaging pixel 20 in the first row. In parallel with this, the control circuit 130 reads out the imaging signal for each row in order from the second reading unit 22 of the imaging pixel 20 in the first row. Thereby, from the image sensor 120, an imaging signal corresponding to the exposure time T8 and an imaging signal corresponding to the exposure time T9 are obtained simultaneously.

  At time t90 when reading of these imaging signals is completed, the control circuit 130 converts the charges accumulated in the photoelectric conversion unit PD (charges corresponding to the exposure time T10) into the first charge holding unit SG1 and the second charge holding unit SG2. Forward to. At this time, the control circuit 130 transfers charges to the first charge holding unit SG1 for a certain half of the rows (for example, odd rows) of all the rows of the image sensor 120, and for the remaining half of the rows (for example, even rows). The charge is transferred to the second charge holding unit SG2.

  Thereafter, the control circuit 130 reads out the imaging signal for each row in order from the first reading unit 21 of the imaging pixel 20 in the first row for the former half of the rows (for example, odd rows). In parallel with this, the control circuit 130 reads out the imaging signal for each row in order from the second readout unit 22 of the imaging pixel 20 in the first row for the latter half of the rows (for example, even rows).

  As a result, an image signal corresponding to the exposure time T10 is obtained from the image sensor 120. Further, half of all the rows are read from the first reading unit 21 and the other half of the rows are read from the second reading unit 22, so that the time required for reading all the rows is the first reading unit. Compared to the case of using only 21 (or only the second reading unit 22), it is about half.

  Note that the reading need not be distributed to the first reading unit 21 and the second reading unit 22 in this way. That is, for example, an imaging signal corresponding to the exposure time T <b> 10 may be read from only the first reading unit 21.

  When the reading of all the imaging signals is finished, the control circuit 130 creates three types of recorded images based on the read three types of imaging signals and records them on the recording medium 160. These three types of recorded images are recorded images based on different exposure times T8, T9, and T10. For example, the exposure time T8 corresponds to a time corresponding to proper exposure, the exposure time T9 corresponds to a time one step higher than the proper exposure (ie, overexposed), and the exposure time T10 corresponds to one step lower than the proper exposure (ie, If the time is underexposed, the three types of recorded images are images obtained by so-called exposure auto bracketing photography.

  In the above description, the exposure auto bracketing based on the exposure time has been described. However, the exposure auto bracketing shooting may be performed by changing the aperture, the ISO sensitivity, and the like for each shooting. In addition, auto bracketing shooting may be performed in which images having different shooting settings (such as a focus position) other than exposure are obtained at a time.

  The control circuit 130 further creates three types of recorded images based on the three types of readout image signals, and then HDR-synthesizes these three types of recorded images by a well-known method to create one recorded image, thereby creating a recording medium. 160 has a recording function. For example, a blackened portion in a short-stored recorded image is restored with the same portion of a medium-stored recorded image or a long-stored recorded image. Similarly, the portion of the long-stored recorded image that has been blown out is restored with the same portion of the short-stored or intermediate-stored recorded image. Since such a synthesis method is well known, the description thereof is omitted.

  FIG. 15 is a diagram schematically showing the exposure time for high dynamic range synthesis. FIG. 15A shows the exposure time for high dynamic range synthesis using a conventional image sensor. In the conventional imaging device, the first imaging signal is read after the first imaging (short accumulation, that is, imaging based on the underexposure exposure setting), and then the second imaging (medium accumulation, that is, appropriate) (Shooting with exposure setting) and reading of the imaging signal were sequentially performed for the third shooting (shooting based on long accumulation, that is, shooting based on the overexposed exposure setting) and reading of the imaging signal. Therefore, the first to third exposure times are spaced apart from each other.

  As described above, if there is an interval between the shootings, for example, when shooting a moving subject, the positions of the subjects are not aligned in the three imaging signals, and high dynamic range synthesis cannot be performed well.

  FIG. 15B shows the exposure time for high dynamic range synthesis using the imaging apparatus according to the present embodiment. As if the image was taken once, imaging signals corresponding to three types of exposure settings were obtained with continuous exposure time. In particular, the three accumulations (exposures) by these three types of exposure settings are within the pixel output timing for one time in total, so in fact, within the time required for one shooting (that is, within one frame period). ) Has been completed. Therefore, an image for performing high dynamic range composition can be obtained without shifting the subject position as in the case of using a conventional image sensor.

According to the imaging apparatus according to the third embodiment described above, the following operational effects can be obtained.
(1) The mechanical shutter 140 is a so-called shutter device, and is configured to be switchable between an open state where light incident on the image sensor 120 is not blocked and a light shield state where light incident on the image sensor 120 is blocked. The first reading unit 21 transfers the charge generated by the photoelectric conversion unit PD to the first charge holding unit SG1 during the first period in which the mechanical shutter 140 is in the open state, and then outputs an output signal corresponding to the charge. Output from the first output unit 23. The second reading unit 22 transfers the charge generated by the photoelectric conversion unit PD in the second period that is not overlapped with the first period when the mechanical shutter 140 is in the open state to the second charge holding unit SG2, and then An output signal corresponding to the charge is output from the second output unit 24. The mechanical shutter 140 is held in the photoelectric conversion unit PD by switching the electric charge generated in the photoelectric conversion unit PD in the third period after the first period and the second period when the mechanical shutter 140 is in the open state to the light shielding state. . The first reading unit 21 outputs a charge held in the photoelectric conversion unit PD when the mechanical shutter 140 is in a light shielding state, and an output signal based on the charge generated by the photoelectric conversion unit PD in the first period. After the output from 23, the data is transferred to the first charge holding unit SG1. Since it did in this way, continuous photography can be performed to a maximum of three at a time. In the continuous shooting for these maximum three images, it is not necessary to read out the signal between the shootings, so the interval between the shootings is substantially zero.

(2) A first output signal based on the charge generated by the photoelectric conversion unit PD in the first period, a second output signal based on the charge generated by the photoelectric conversion unit PD in the second period, and a photoelectric output in the third period. The third output signal based on the charge generated by the conversion unit PD is an output signal based on different exposure settings. Since it did in this way, what is called exposure auto bracketing imaging | photography can be performed to a maximum of three at once. In the exposure auto bracketing photography performed here, the interval between each photography is extremely short (substantially zero) as compared with normal exposure auto bracketing photography. Accordingly, the positional deviation of the subject for each photographing can be extremely reduced.

(3) The control circuit 130 has a higher dynamic range than an image based on any one output signal based on three imaging signals (first output signal, second output signal, and third output signal) having different exposure settings. It functions as a high dynamic range composition unit that creates images. Since this is done, it is possible to obtain a high dynamic range image in which the positional deviation of the subject for each shooting is extremely small.

(Fourth embodiment)
FIG. 16 is a schematic diagram showing a configuration of an imaging apparatus according to the fourth embodiment of the present invention. In FIG. 16, the same parts as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

  In addition to the imaging optical system 110, the imaging device 120, the control circuit 130, the mechanical shutter 140, the display device 150, and the recording medium 160, the imaging device 200 further includes a projection unit 170. The projection unit 170 projects pulsed light (modulated light) onto a subject within a predetermined angle of view.

  The control circuit 130 has a depth map creation function. The depth map is data obtained by two-dimensionally mapping the depth of each part of the subject (distance from the imaging device 200 to the subject part). The control circuit 130 measures the depth (distance) of each part of the subject using a so-called optical flight time measurement method (ToF; Time of Flight). In the present embodiment, the subject portion is a subject portion corresponding to a block made up of one imaging pixel 20 or a plurality of imaging pixels 20. That is, the control circuit 130 can obtain the depth of the corresponding subject portion for each imaging pixel 20 or for each block composed of a plurality of imaging pixels 20. Hereinafter, the distance measurement operation when creating the depth map will be described in detail.

  FIG. 17 is a timing chart of the distance measuring operation. First, at time t100, the projection unit 170 projects pulsed light for a time T0. At time t100, the control circuit 130 simultaneously resets the photoelectric conversion unit PD, the first charge holding unit SG1, and the second charge holding unit SG2 for all the imaging pixels 20.

  Thereafter, at time t102 when the projection of the pulsed light ends, the control circuit 130 transfers charges from the photoelectric conversion unit PD to the first charge holding unit SG1 for all the imaging pixels 20.

  Furthermore, at time t104, which is a time T0 after time t102, the control circuit 130 transfers charges from the photoelectric conversion unit PD to the second charge holding unit SG2 for all the imaging pixels 20.

  The pulsed light (projection light) that starts projection from time t100 is reflected by the surface of the subject and returns toward the image sensor 120 at time t101, which is a delay time Td after time t100. Here, the delay time Td is a time corresponding to the distance L to the subject portion corresponding to the imaging pixel 20. The longer the distance L, the longer the delay time Td. The reflected light is interrupted in the vicinity of time t103, which is a time T0 after time t101.

  After time t104, the control circuit 130 reads out the imaging signal for each row in order from the first reading unit 21 of the imaging pixel 20 in the first row. In parallel with this, the control circuit 130 reads out the imaging signal for each row in order from the second reading unit 22 of the imaging pixel 20 in the first row. As a result, the imaging element 120 simultaneously obtains an imaging signal corresponding to the exposure period from time t100 to time t102 and an imaging signal corresponding to the exposure period from time t102 to time t104.

  Here, the ratio of the imaging signal (output signal) read from the first reading unit 21 and the imaging signal (output signal) read from the second reading unit 22 is the reflected light received until time t102. And the amount of reflected light received after time t102. Therefore, the delay time Td can be determined from the imaging signal read from the first reading unit 21 and the imaging signal read from the second reading unit 22.

  For example, when the imaging signal read from the first reading unit 21 and the imaging signal read from the second reading unit 22 are approximately equal for a certain imaging pixel 20, it corresponds to the imaging pixel 20. The delay time Td in the subject portion to be played is half of the time T0. When the magnitude of the imaging signal read from the first reading unit 21 and the imaging signal read from the second reading unit 22 is a ratio of 1: 2, the delay time Td is equal to the time T0. It is two-thirds.

  Since the speed of light c is known, if the delay time Td is known, the distance L to the subject can be calculated. Since such a method for calculating the distance L is well known, a description thereof will be omitted.

According to the imaging apparatus according to the fourth embodiment described above, the following operational effects can be obtained.
(1) The projection unit 170 projects pulsed light that is predetermined modulated light onto a subject. The first reading unit 21 transfers the charge generated by the photoelectric conversion unit PD by photoelectrically converting a part of the reflected light of the projection light to the first charge holding unit SG1, and outputs an output signal based on the charge to the first output unit. 23. The second reading unit 22 transfers charges generated by the photoelectric conversion unit PD photoelectrically converting the remaining reflected light of the projection light to the second charge holding unit SG2, and outputs an output signal based on the charges to the second output unit. 24. The control circuit 130 functions as a distance calculation unit that calculates the distance to the subject based on the output signal output from the first output unit 23 and the output signal output from the second output unit 24. Since it did in this way, the depth map of a to-be-photographed object can be created accurately.

  The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.

(Modification 1)
The first charge holding unit SG1 and the second charge holding unit SG2 may have a configuration different from the above-described embodiment. For example, the first charge holding unit SG1 and the second charge holding unit SG2 may be configured by a charge transfer MOSFET and a capacitance component (for example, a diode) that accumulates charges. Further, the first reading unit 21 and the second reading unit 22 may be configured not to include the first charge holding unit SG1 and the second charge holding unit SG2.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

DESCRIPTION OF SYMBOLS 20 ... Imaging pixel, 21 ... 1st reading part, 22 ... 2nd reading part, 23 ... 1st output part, 24 ... 2nd output part, 100, 200 ... Imaging device, 110 ... Imaging optical system, 120 ... Imaging Elements 130, control circuit 140, mechanical shutter, 150, display device, 160, recording medium, 170, projection unit, PD, photoelectric conversion unit, SG1, first charge holding unit, SG2, second charge holding unit, FD1 ... first charge voltage converter, FD2 ... second charge voltage converter, TX1 ... first transfer transistor, TX2 ... second transfer transistor, S1 ... first output transistor, S2 ... second output transistor, SF1 ... first amplification Transistor, SF2 ... second amplification transistor

Claims (12)

A plurality of pixels having a photoelectric conversion unit that photoelectrically converts incident light to generate charges, and first and second readout units connected to the photoelectric conversion unit,
The first reading unit converts a charge transferred from the photoelectric conversion unit into a voltage, and a first output unit outputs an output signal corresponding to the voltage of the first charge voltage conversion unit. And
The second reading unit converts a charge transferred from the photoelectric conversion unit into a voltage, a second charge voltage conversion unit, and a second output unit that outputs an output signal corresponding to the voltage of the second charge voltage conversion unit And an image pickup device. The imaging device according to claim 1,
The first reading unit further includes a first charge holding unit that holds charges transferred from the photoelectric conversion unit,
The first charge voltage conversion unit converts the charge transferred from the first charge holding unit into a voltage,
The second reading unit further includes a second charge holding unit that holds the charge transferred from the photoelectric conversion unit,
The second charge-voltage conversion unit is an imaging device that converts the charge transferred from the second charge holding unit into a voltage. The imaging device according to claim 2,
The capacitance value of the first charge voltage conversion unit is larger than the capacitance value of the first charge holding unit,
The imaging element having a capacitance value of the second charge-voltage conversion unit larger than a capacitance value of the second charge holding unit. In the imaging device according to claim 2 or 3,
The first charge holding unit holds the charge generated by the photoelectric conversion unit in the first period,
The second charge holding unit is an image sensor that holds charges generated in a second period in which the photoelectric conversion unit does not overlap with the first period. The imaging device according to claim 4,
The length of the first period is an image sensor different from the length of the second period. In the imaging device according to claim 4 or 5,
The first output unit outputs an output signal in a third period that does not overlap with the first period and at least partially overlaps with the second period. The imaging device according to any one of claims 1 to 6,
An image creation unit that creates a first display image based on the output signal output from the first output unit and creates a second display image based on the output signal output from the second output unit;
An image display unit that alternately displays the first display image and the second display image;
An imaging apparatus comprising: The image sensor according to any one of claims 2 to 6,
A shutter device capable of switching between an open state that does not block the incident light to the image sensor and a light blocking state that blocks the incident light to the image sensor,
The first reading unit transfers charges generated by the photoelectric conversion unit during the first period in which the shutter device is in the open state to the first charge holding unit, and then an output signal corresponding to the charges Is output from the first output unit,
The second reading unit transfers the charge generated by the photoelectric conversion unit to the second charge holding unit during a second period in which the shutter device is in the open state and does not overlap with the first period, and then An output signal corresponding to the charge is output from the second output unit,
In the shutter device, the photoelectric conversion unit switches the charge generated by the photoelectric conversion unit in the third period after the first period and the second period when the shutter apparatus is in the open state to the light-shielding state. Hold in the department
The first reading unit outputs an electric charge held in the photoelectric conversion unit when the shutter device is in the light shielding state, and an output signal based on the electric charge generated by the photoelectric conversion unit in the first period. An image pickup apparatus that transfers to the first charge holding unit after outputting from one output unit. The imaging device according to claim 8,
A first output signal based on the charge generated by the photoelectric conversion unit in the first period, a second output signal based on the charge generated by the photoelectric conversion unit in the second period, and the third output period in the third period. The imaging device which is an output signal based on different exposure settings from the third output signal based on the charge generated by the photoelectric conversion unit. The imaging device according to claim 9,
An imaging device that further includes a high dynamic range synthesis unit that creates an image having a higher dynamic range than an image based on any one output signal based on the first output signal, the second output signal, and the third output signal. apparatus. The image sensor according to any one of claims 2 to 6,
A projection unit that projects predetermined modulated light onto a subject;
The first reading unit transfers the charge generated by the photoelectric conversion unit photoelectrically converting a part of the reflected light of the modulated light to the first charge holding unit, and outputs an output signal based on the charge to the first Output from the output section,
The second reading unit transfers the charge generated by the photoelectric conversion unit photoelectrically converting the remaining part of the reflected light of the modulated light to the second charge holding unit, and outputs based on the charge A signal is output from the second output unit;
An imaging apparatus comprising: a distance calculation unit that calculates a distance to the subject based on an output signal output from the first output unit and an output signal output from the second output unit. A plurality of pixels having a photoelectric conversion unit that photoelectrically converts incident light to generate charges, and first and second readout units connected to the photoelectric conversion unit,
The first reading unit includes a first charge holding unit that holds charges transferred from the photoelectric conversion unit, and a first output unit that outputs an output signal corresponding to the charges held in the first charge holding unit. Have
The second reading unit includes a second charge holding unit that holds the charge transferred from the photoelectric conversion unit, and a second output unit that outputs an output signal corresponding to the charge held in the second charge holding unit. An imaging device having

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