JP2024041961A - Distance image capturing device and distance image capturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an apparent number of taps by a method that is different from a method for increasing the number of subframes.

SOLUTION: Each of a plurality of pixels is classified into one of predetermined two or more groups. With a storage timing relative to an irradiation timing mutually different for each group in pixels belonging to each of the two or more groups, a timing control unit exercises control in such a way that a first charge storage unit in pixels belonging to a first group stores charges in an external light storage period before optical pulses are irradiated, and that charges corresponding to reflected light and external light component are stored in a second and a third charge storage unit of pixels belonging to the first group, and charges corresponding to light that includes external light component or reflected light and external light component are stored in three of the charge storage units of pixels belonging to a second group, and that the next irradiation timing arrives after storing of charges in all of the charge storage units that the pixels include is completed in accordance with the irradiation timing.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a distance image capturing device and a distance image capturing method.

Traditionally, time-of-flight (hereinafter referred to as "TOF") distance imaging utilizes the known speed of light to measure the distance to an object based on the flight time of light. There is an imaging device. Similar to an imaging device, in a distance image imaging device, a plurality of pixels that detect light for measuring distance are arranged in a two-dimensional matrix, and information on the two-dimensional distance to the subject and an image of the subject can be acquired (imaged).

In such a distance image capturing device, the distance to the subject is measured by calculating the delay time of pulsed light reflected by the subject based on the ratio of the charges distributed to the plurality of charge storage units included in the pixel. can do. A configuration including such a plurality of charge storage sections and a charge distribution structure is called a multi-tap configuration or the like. In Patent Document 1, the apparent number of taps (the number of charge storage units) is increased by using a configuration that distributes charges to charge storage units at different timings for each frame, thereby increasing the distance measurement range without reducing the distance resolution. Techniques are disclosed that can be scaled up.

Japanese Patent Application Publication No. 2010-32425

However, with the technique disclosed in Patent Document 1, there is room for improvement when attempting to further expand the distance measurement range. In other words, if the number of frames is increased to enable measurement of a distant range, the interval from the first frame to the last frame will increase, and there is a possibility that accurate measurement will not be possible when the object to be measured is a moving object. there were.
In the following description, in one image (one frame image) created using a plurality of frames, the plurality of frames used to create one frame image will be referred to as subframes.
Another possible method for making it possible to measure a distant range is to increase the number of charge storage units included in each pixel. With this method, even if the object to be measured is a moving object, it is possible to measure it more accurately than when measuring by increasing the number of subframes, but there is a problem in that the pixel size increases.

The present invention has been made based on the above-mentioned problems, and provides a distance image capturing device and a distance image capturing method that can increase the apparent number of taps by a method different from the method of increasing the number of subframes. is intended to provide.

According to the present invention, a distance image capturing device includes a light receiving unit having a light source unit that irradiates a measurement space with a light pulse, a plurality of pixels arranged in a two-dimensional matrix, each of which has a photoelectric conversion element that generates a charge according to the incident light and three or more charge accumulation units that accumulate the charge, a pixel drive circuit that distributes and accumulates charge in each of the charge accumulation units at a predetermined accumulation timing synchronized with the irradiation timing at which the irradiation of the light pulse begins, a timing control unit that controls the accumulation timing, and a distance calculation unit that calculates a distance to a subject present in the measurement space based on the amount of charge accumulated in each of the charge accumulation units, each of the plurality of pixels being classified into one of two or more predetermined groups, and the timing control unit controls the timing of the illumination at pixels belonging to each of the two or more groups. The accumulation timing with respect to the irradiation timing is different for each group, and during an external light accumulation period before the light pulse is irradiated, a first charge accumulation unit in a pixel belonging to a first group of the two or more groups accumulates a charge corresponding to an external light component that does not include reflected light of the light pulse, a second charge accumulation unit and a third charge accumulation unit in the pixel belonging to the first group accumulate a charge corresponding to light including the reflected light and the external light component, and three charge accumulation units in a pixel belonging to a second group different from the first group accumulate a charge corresponding to the external light component or the reflected light and the external light component, and the next irradiation timing is controlled to arrive after charge accumulation in all of the charge accumulation units provided in the pixels belonging to each of the two or more groups according to the irradiation timing is completed.

According to the present invention, in the above-mentioned distance image imaging device, the timing control section is configured to control the total accumulation time for accumulating charges in each of the charge accumulating sections in which charges are accumulated at the accumulation timing subsequent to the irradiation timing. Control is performed such that the smaller the delay time from the irradiation timing is, the smaller the sum is, and the longer the delay time is, the larger the sum is.

According to the present invention, in the distance image imaging device described above, the plurality of charge storage sections in the pixel include three charge storage sections, a first charge storage section, a second charge storage section, and a third charge storage section. The timing control section controls the first charge accumulation section in the pixels belonging to the second group during a first reflected light accumulation period from the irradiation timing to the end of the irradiation period in which the light pulse is irradiated. a second charge accumulation section in pixels belonging to the first group during a second reflected light accumulation period from the timing at which the first reflected light accumulation period ends until a time corresponding to the irradiation period has elapsed; the charges are accumulated in a second charge accumulation section of the pixels belonging to the second group until a time corresponding to the irradiation period elapses from the timing at which the second reflected light accumulation period ends. During the third reflected light accumulation period, the charges are accumulated in the third charge accumulation sections of the pixels belonging to the first group, and the charges are accumulated in the third charge accumulation sections of the pixels belonging to the second group.

According to the present invention, in the above-mentioned distance image capturing device, the multiple charge accumulation sections in the pixel are composed of three charge accumulation sections, namely, a first charge accumulation section, a second charge accumulation section, and a third charge accumulation section, and the timing control section accumulates charge in the first charge accumulation section in the pixel belonging to the second group during the external light accumulation period, accumulates charge in the second charge accumulation section in the pixel belonging to the first group during a first reflected light accumulation period from the irradiation timing to the end of the irradiation period in which the light pulse is irradiated, accumulates charge in the third charge accumulation section in the pixel belonging to the first group during a second reflected light accumulation period from the timing at which the first reflected light accumulation period ends until the time equivalent to the irradiation period has elapsed, accumulates charge in the second charge accumulation section in the pixel belonging to the second group during a first semi-reflective light accumulation period from the timing before the irradiation period has elapsed after the irradiation of the light pulse begins until the irradiation period ends, and accumulates charge in the third charge accumulation section in the pixel belonging to the second group during a second semi-reflective light accumulation period from the timing at which the first semi-reflective light accumulation period ends until the time equivalent to the irradiation period ends.

According to the present invention, in the distance image imaging device described above, the plurality of charge storage sections in the pixel include three charge storage sections, a first charge storage section, a second charge storage section, and a third charge storage section. The timing control section controls the second charge accumulation section in the pixels belonging to the first group during a first reflected light accumulation period from the irradiation timing to the end of the irradiation period in which the light pulse is irradiated. A third charge storage section in a pixel belonging to the first group during a second reflected light accumulation period from the timing when the first reflected light accumulation period ends until a time corresponding to the irradiation period elapses after accumulating charges. during a half-delay external light accumulation period from a timing before a time corresponding to the irradiation period has elapsed from the start of the external light accumulation period until a time corresponding to the irradiation period ends. Charges are accumulated in first charge accumulation sections in pixels belonging to two groups, during a first half-reflected light accumulation period from the timing at which the half-delayed external light accumulation period ends until the time corresponding to the irradiation period ends, The charge is accumulated in a second charge storage section of the pixel belonging to the second group, and second semi-reflected light is generated from the timing when the first semi-reflected light accumulation period ends until the time corresponding to the irradiation period ends. During the accumulation period, the charges are accumulated in a third charge accumulation section in the pixels belonging to the second group.

According to the present invention, in the distance image imaging device described above, the plurality of charge storage sections in the pixel include three charge storage sections, a first charge storage section, a second charge storage section, and a third charge storage section. The timing control section controls the second charge accumulation section in the pixels belonging to the first group during a first reflected light accumulation period from the irradiation timing to the end of the irradiation period in which the light pulse is irradiated. A third charge storage section in a pixel belonging to the first group during a second reflected light accumulation period from the timing when the first reflected light accumulation period ends until a time corresponding to the irradiation period elapses after accumulating charges. in a first semi-reflected light accumulation period from a timing before a time corresponding to the irradiation period has elapsed from the start of the first reflected light accumulation period until a time corresponding to the irradiation period ends. , second semi-reflected light from the timing at which the first semi-reflected light accumulation period ends until the time corresponding to the irradiation period ends by accumulating charges in the first charge accumulating section of the pixels belonging to the second group; During the accumulation period, the charges are accumulated in a second charge accumulation section of the pixels belonging to the second group, and the charge is accumulated from the timing when the second semi-reflection light accumulation period ends until the time corresponding to the irradiation period ends. During the third half-reflection light accumulation period, the charges are accumulated in the third charge accumulation section of the pixels belonging to the second group.

According to the present invention, a distance image capturing method includes a light source unit that irradiates a measurement space with a light pulse, a photoelectric conversion element that generates charges according to the incident light, and three or more charge storage units that accumulate charges. and a plurality of pixels arranged in a two-dimensional matrix, and charges are distributed and accumulated in each of the charge accumulation sections at a predetermined accumulation timing synchronized with the irradiation timing at which irradiation of the light pulse is started. a pixel drive circuit that controls the measurement, a timing control section that controls the accumulation timing, and a distance to the object existing in the measurement space based on the amount of charge accumulated in each of the charge accumulation section. A distance image capturing method carried out by a distance image capturing device comprising a distance calculating section for calculating, each of the plurality of pixels being classified into one of two or more predetermined groups, and the timing controlling section , the accumulation timing with respect to the irradiation timing in the pixels belonging to each of the two or more groups is different for each group, and during the external light accumulation period before the light pulse is irradiated, the accumulation timing for the pixels belonging to each of the two or more groups is Charges corresponding to an external light component that does not include reflected light of the optical pulse are accumulated in a first charge accumulation section of the pixels belonging to one group, and a second charge accumulation section of the pixels belonging to the first group and a third charge accumulation section of the pixels belonging to the first group are accumulated. Charges corresponding to the reflected light and the light including the external light component are stored in the charge storage section, and the charge corresponding to the external light component or the external light component is stored in the three charge storage sections of pixels belonging to a second group different from the first group. After charges corresponding to the reflected light and the light including the external light component are accumulated, and charge accumulation is completed in all of the charge accumulation sections included in the pixels belonging to each of the two or more groups according to the irradiation timing. , the control is performed so that the next irradiation timing arrives.

According to each of the above aspects, the apparent number of taps can be increased by a method different from the method of increasing the number of subframes.

1 is a block diagram showing a schematic configuration of a distance image capturing device 1 according to an embodiment. 1 is a block diagram showing a schematic configuration of an imaging element used in a distance image capturing device 1 of an embodiment. FIG. 2 is a circuit diagram showing an example of a configuration of a pixel 321 arranged in a light receiving area of an image sensor used in the distance image imaging device 1 of the embodiment. 4 is a timing chart showing timings for driving pixels in the range image pickup device of the first embodiment. 5 is a timing chart showing the timing of driving pixels in the distance image capturing device of the first embodiment. 5 is a timing chart showing the timing of driving pixels in the distance image capturing device of the first embodiment. 5 is a timing chart showing the timing of driving pixels in the distance image capturing device of the first embodiment. FIG. 3 is a diagram showing an example of grouping of pixel groups in the distance image capturing device of the first embodiment. FIG. 3 is a diagram showing an example of grouping of pixel groups in the distance image capturing device of the first embodiment. FIG. 3 is a diagram showing an example of grouping of pixel groups in the distance image capturing device of the first embodiment. FIG. 7 is a diagram illustrating an example of grouping of pixel groups in the distance image capturing device according to the second embodiment. 7 is a timing chart showing the timing of driving pixels in the distance image capturing device of the second embodiment. FIG. 7 is a diagram illustrating an example of grouping of pixel groups in the distance image capturing device according to the second embodiment. FIG. 7 is a diagram for explaining an example of a process of composing a plurality of subframes in a distance image capturing device according to a second embodiment. 12 is a timing chart showing the timing of driving pixels in the distance image capturing device of the third embodiment. 12 is a timing chart showing the timing of driving pixels in the distance image capturing device of the third embodiment. 12 is a timing chart showing the timing of driving pixels in the distance image capturing device of the third embodiment. 2 is a timing chart showing the timing of driving pixels in a conventional distance image capturing device.

The following describes an embodiment of the present invention with reference to the drawings.

(Embodiment)
First, an embodiment will be described. Here, the configuration of the distance image imaging device 1, which is common to the first to third embodiments described later, will be described.
FIG. 1 is a block diagram showing a schematic configuration of a distance image capturing device according to an embodiment. A distance image imaging device 1 having the configuration shown in FIG. 1 includes a light source section 2, a light receiving section 3, and a distance image processing section 4. Note that FIG. 1 also shows a subject S, which is an object whose distance is to be measured in the distance image capturing device 1.

The light source section 2 irradiates the space of the object to be photographed in which the object S whose distance is to be measured in the distance image capturing device 1 exists, with a light pulse PO, under the control from the distance image processing section 4 . The light source unit 2 is, for example, a surface-emitting semiconductor laser module such as a vertical cavity surface-emitting laser (VCSEL). The light source section 2 includes a light source device 21 and a diffusion plate 22.

The light source device 21 is a light source that emits laser light in a near-infrared wavelength band (for example, a wavelength band of 850 nm to 940 nm) that becomes a light pulse PO that is irradiated onto the subject S. The light source device 21 is, for example, a semiconductor laser light emitting device. The light source device 21 emits pulsed laser light under control from the timing control section 41.

The diffuser plate 22 is an optical component that diffuses the laser light in the near-infrared wavelength band emitted by the light source device 21 over a surface onto which the subject S is irradiated. The pulsed laser light diffused by the diffusion plate 22 is emitted as a light pulse PO, and is irradiated onto the subject S.

The light receiving unit 3 receives the reflected light RL of the optical pulse PO reflected by the subject S whose distance is to be measured in the distance image capturing device 1, and outputs a pixel signal according to the received reflected light RL. The light receiving section 3 includes a lens 31 and a distance image sensor 32.

The lens 31 is an optical lens that guides the incident reflected light RL to the distance image sensor 32. The lens 31 emits the incident reflected light RL to the distance image sensor 32 side, and causes the light to be received (incident) by a pixel provided in a light receiving area of the distance image sensor 32.

The distance image sensor 32 is an image sensor used in the distance image imaging device 1. The distance image sensor 32 includes a plurality of pixels in a two-dimensional light receiving area. Each pixel of the distance image sensor 32 is provided with one photoelectric conversion element, a plurality of charge storage sections corresponding to this one photoelectric conversion element, and a component that distributes charge to each charge storage section. . In other words, a pixel is an image sensor having a distribution configuration in which charges are distributed and accumulated in a plurality of charge storage sections.

The distance image sensor 32 distributes the charges generated by the photoelectric conversion elements to the respective charge storage sections according to control from the timing control section 41. Further, the distance image sensor 32 outputs a pixel signal according to the amount of charge distributed to the charge storage section. The distance image sensor 32 has a plurality of pixels arranged in a two-dimensional matrix, and outputs pixel signals for one frame corresponding to each pixel.

The distance image processing unit 4 controls the distance image capturing device 1 and calculates the distance to the subject S. The distance image processing section 4 includes a timing control section 41 and a distance calculation section 42.

The timing control unit 41 controls the timing of outputting various control signals required for measurement. The various control signals here include, for example, a signal that controls the irradiation of the optical pulse PO, a signal that distributes the reflected light RL to a plurality of charge storage units, a signal that controls the number of times of distribution per frame, and the like. The number of times of distribution is the number of times that the process of distributing charges to the charge storage sections is repeated.

In an embodiment of the present invention, each of the multiple pixels included in the distance image capturing device 1 is classified into one of two or more predetermined groups. The timing control unit 41 controls the accumulation period of the charge accumulation unit in each of the pixels belonging to each of the two or more groups so that the accumulation period is different for each group. The accumulation period is the period during which charge is accumulated in the charge accumulation unit. Details of the method by which the timing control unit 41 controls the timing at which charge is accumulated in the charge accumulation unit will be described in detail in each of the first to third embodiments described below.

The distance calculation unit 42 outputs distance information obtained by calculating the distance to the subject S based on the pixel signal output from the distance image sensor 32. The distance calculation unit 42 calculates the delay time Td (see FIG. 18) from irradiation of the optical pulse PO to reception of the reflected light RL, based on the amount of charge accumulated in the plurality of charge storage units. The distance calculation unit 42 calculates the distance to the subject S according to the calculated delay time Td.

With such a configuration, in the distance image capturing device 1, the light receiving unit 3 receives the reflected light RL, which is the light pulse PO in the near-infrared wavelength band that is irradiated onto the subject S by the light source unit 2, and is reflected by the subject S. The distance image processing unit 4 outputs distance information obtained by measuring the distance to the subject S.

Note that although FIG. 1 shows the distance image capturing device 1 having a configuration including the distance image processing unit 4 inside, the distance image processing unit 4 is a component provided outside the distance image capturing device 1. It's okay.

Next, the configuration of the distance image sensor 32 used as an image sensor in the distance image imaging device 1 will be explained. FIG. 2 is a block diagram showing a schematic configuration of an image sensor (distance image sensor 32) used in the distance image imaging device 1 according to the embodiment of the present invention.

As shown in FIG. 2, the distance image sensor 32 includes, for example, a light receiving area 320 in which a plurality of pixels 321 are arranged, a control circuit 322, a vertical scanning circuit 323 having a distribution operation, a horizontal scanning circuit 324, A pixel signal processing circuit 325 is provided.

The light receiving area 320 is an area in which a plurality of pixels 321 are arranged, and FIG. 2 shows an example in which they are arranged in a two-dimensional matrix of 8 rows and 8 columns. The pixel 321 accumulates charges according to the amount of light it receives. The control circuit 322 controls the distance image sensor 32 in an integrated manner. The control circuit 322 controls the operations of the components of the distance image sensor 32, for example, in accordance with instructions from the timing control section 41 of the distance image processing section 4. Note that the components included in the distance image sensor 32 may be directly controlled by the timing control section 41, and in this case, the control circuit 322 may be omitted.

The vertical scanning circuit 323 is a circuit that controls the pixels 321 arranged in the light receiving area 320 row by row in accordance with the control from the control circuit 322. The vertical scanning circuit 323 causes the pixel signal processing circuit 325 to output a voltage signal corresponding to the amount of charge accumulated in each charge accumulation section of the pixel 321. In this case, the vertical scanning circuit 323 distributes the charge converted by the photoelectric conversion element to each charge storage section of the pixel 321. In other words, the vertical scanning circuit 323 is an example of a "pixel drive circuit."

The pixel signal processing circuit 325 is a circuit that performs predetermined signal processing (e.g., noise suppression processing, A/D conversion processing, etc.) on the voltage signals output from the pixels 321 in each column to the corresponding vertical signal lines in response to control from the control circuit 322.

The horizontal scanning circuit 324 is a circuit that sequentially outputs the signals output from the pixel signal processing circuit 325 to the horizontal signal line in accordance with the control from the control circuit 322. As a result, pixel signals corresponding to the amount of charge accumulated for one frame are sequentially output to the distance image processing section 4 via the horizontal signal line.

In the following explanation, it is assumed that the pixel signal processing circuit 325 performs A/D conversion processing and the pixel signal is a digital signal.

Here, the configuration of the pixel 321 arranged in the light receiving region 320 of the distance image sensor 32 will be described. FIG. 3 is a circuit diagram showing an example of the configuration of the pixel 321 arranged in the light receiving region 320 of the imaging element (distance image sensor 32) used in the distance image capturing device 1 according to an embodiment of the present invention. FIG. 3 shows an example of the configuration of one pixel 321 out of the multiple pixels 321 arranged in the light receiving region 320. The pixel 321 is an example of a configuration equipped with three pixel signal readout units.

Pixel 321 includes one photoelectric conversion element PD, a drain transistor GD, and three pixel signal readout units RU that output voltage signals from corresponding output terminals O. Each pixel signal readout unit RU includes a readout transistor G, a floating diffusion FD, a charge storage capacitance C, a reset transistor RT, a source follower transistor SF, and a selection transistor SL. In each pixel signal readout unit RU, the floating diffusion FD and the charge storage capacitance C form a charge storage unit CS.

In addition, in FIG. 3, each pixel signal readout unit RU is distinguished by adding a number “1”, “2”, or “3” after the code “RU” of the three pixel signal readout units RU. do. Similarly, each component included in the three pixel signal readout units RU is indicated by a number representing each pixel signal readout unit RU after the symbol, so that each component corresponds to the pixel signal readout unit RU. RUs are represented separately.

In the pixel 321 shown in FIG. 3, the pixel signal readout unit RU1 that outputs a voltage signal from the output terminal O1 includes a readout transistor G1, a floating diffusion FD1, a charge storage capacitor C1, a reset transistor RT1, and a source follower transistor SF1. and a selection transistor SL1. In the pixel signal readout section RU1, a charge storage section CS1 is configured by a floating diffusion FD1 and a charge storage capacitor C1. The pixel signal readout unit RU2 and the pixel signal readout unit RU3 have similar configurations. The charge storage section CS1 is an example of a "first charge storage section." The charge storage section CS2 is an example of a "second charge storage section". The charge storage section CS3 is an example of a "third charge storage section".

The photoelectric conversion element PD is an embedded photodiode that photoelectrically converts incident light to generate charges and stores the generated charges. The structure of the photoelectric conversion element PD may be arbitrary. The photoelectric conversion element PD may be, for example, a PN photodiode having a structure in which a P-type semiconductor and an N-type semiconductor are joined, or a PN photodiode having a structure in which an I-type semiconductor is sandwiched between a P-type semiconductor and an N-type semiconductor. It may also be a PIN photodiode. Further, the photoelectric conversion element PD is not limited to a photodiode, and may be a photogate type photoelectric conversion element, for example.

In the pixel 321, the photoelectric conversion element PD photoelectrically converts the incident light, and the generated charge is distributed to each of the three charge storage sections CS, and each voltage signal corresponding to the amount of the distributed charge is sent to the pixel. It is output to the signal processing circuit 325.

The configuration of the pixels arranged in the distance image sensor 32 is not limited to the configuration including three pixel signal readout units RU as shown in FIG. 3, but may include a plurality of pixel signal readout units RU. Any pixel of any configuration may be used. That is, the number of pixel signal readout units RU (charge storage units CS) provided in the pixels arranged in the distance image sensor 32 may be two, or may be four or more.

Further, in the pixel 321 having the configuration shown in FIG. 3, an example is shown in which the charge storage section CS is configured by a floating diffusion FD and a charge storage capacitor C. However, the charge storage section CS only needs to be configured by at least the floating diffusion FD, and the pixel 321 may not include the charge storage capacitor C.

Further, in the pixel 321 having the configuration shown in FIG. 3, an example of the configuration including the drain transistor GD is shown, but if there is no need to discard the charge accumulated (remaining) in the photoelectric conversion element PD, , the structure may not include the drain transistor GD.

Next, a method for driving (controlling) the pixels 321 in the distance image capturing device 1 will be described using FIG. 18. FIG. 18 is a timing chart showing the timing of drive signals for driving pixels in a conventional distance image capturing device.

In FIG. 18, the timing of irradiating the optical pulse PO is "Light", the timing of receiving the reflected light is "REFRECTION", the timing of the drive signal TX1 is "G1", the timing of the drive signal TX2 is "G2", and the timing of the drive signal TX2 is "G2". The timing of TX3 is shown as "G3", and the timing of drive signal RSTD is shown as "GD". Further, a series of light receiving operation timings in the distance image capturing device are indicated by the item name "Camera". In "Camera", the timings at which the read transistors G1, G2, G3 and drain transistor GD are turned on are indicated by "G1", "G2", "G3", and "GD", respectively. Note that the drive signal TX1 is a signal that drives the read transistor G1. The same applies to drive signals TX2 and TX3.

As shown in FIG. 18, it is assumed that the optical pulse PO is emitted for an irradiation time To, and the reflected light RL is received by the distance image sensor 32 after a delay time Td. The vertical scanning circuit 323 accumulates charges in the order of charge storage units CS1, CS2, and CS3 in synchronization with the irradiation of the optical pulse PO.

First, the vertical scanning circuit 323 turns on the read transistor G1. Thereby, the charge photoelectrically converted by the photoelectric conversion element PD is accumulated in the charge storage section CS1 via the readout transistor G1. After that, the vertical scanning circuit 323 turns off the read transistor G1. As a result, the transfer of charges to the charge storage section CS1 is stopped. In this way, the vertical scanning circuit 323 causes the charge storage section CS1 to accumulate charges.

Next, the vertical scanning circuit 323 turns on the readout transistor G2 at the timing when the charge accumulation in the charge accumulation section CS1 is finished, and starts accumulation of charge in the charge accumulation section CS2. The subsequent flow of the process for accumulating charges in the charge storage section CS2 is similar to the flow of the process for accumulating charges in the charge accumulation section CS1. Therefore, the explanation thereof will be omitted.

On the other hand, the light source section 2 emits the optical pulse PO at the timing when the readout transistor G1 is turned off, that is, at the timing when the readout transistor G2 is turned on. The irradiation time To during which the light source unit 2 irradiates the optical pulse PO is the same length as the accumulation period Ta. Here, the period (accumulation period Ta) in which the readout transistor G1 is in an on state and charges are accumulated in the charge accumulation section CS1 is an example of an "external light accumulation period."

Next, the vertical scanning circuit 323 turns on the readout transistor G3 at the timing when the charge storage in the charge storage section CS2 is finished, and starts storing the charge in the charge storage section CS3. The subsequent flow of processing for accumulating charges in charge storage section CS3 is similar to the flow of processing for accumulating charges in charge accumulation section CS1. Therefore, the explanation thereof will be omitted.

Next, the vertical scanning circuit 323 turns on the drain transistor GD at the timing when the charge accumulation in the charge storage section CS3 is completed, and discharges the charge. Thereby, the charge photoelectrically converted by the photoelectric conversion element PD is discarded via the drain transistor GD.

As described above, the accumulation of charges in the charge storage section CS by the vertical scanning circuit 323 and the discarding of the charges photoelectrically converted by the photoelectric conversion element PD are repeatedly performed over one frame. As a result, charges corresponding to the amount of light received by the distance image capturing device 1 during a predetermined time interval are accumulated in each of the charge accumulation sections CS. The horizontal scanning circuit 324 outputs an electric signal corresponding to the amount of charge for one frame accumulated in each of the charge storage sections CS to the distance calculation section 42.

Due to the relationship between the timing of irradiating the optical pulse PO and the timing of accumulating charges in each of the charge storage sections CS, the charge storage section CS1 has an external light component such as background light before the irradiation of the optical pulse PO. The amount of charge is retained. In addition, the charge storage units CS2 and CS3 distribute and hold charge amounts according to the reflected light RL and external light components. The distribution (distribution ratio) of the amount of charge distributed to the charge storage units CS2 and CS3 is a ratio according to the delay time Td from when the optical pulse PO is reflected by the subject S to when it is input to the distance image capturing device 1. .

Using this principle, the distance calculation unit 42 calculates the delay time Td using the following equation (1).

Td=To×(Q3-Q1)/(Q2+Q3-2×Q1)…(1)

Here, To is the period during which the optical pulse PO was irradiated, Q1 is the amount of charge accumulated in the charge storage section CS1, Q2 is the amount of charge accumulated in the charge accumulation section CS2, and Q3 is the amount of charge accumulated in the charge accumulation section CS3. Indicates the amount of charge. In addition, in equation (1), it is assumed that among the amount of charge accumulated in the charge storage units CS2 and CS3, the component corresponding to the external light component is the same amount as the amount of charge accumulated in the charge accumulation unit CS1. Assumed.

The distance calculation unit 42 calculates the round trip distance to the subject S by multiplying the delay time calculated using equation (1) by the speed of light. Then, the distance calculation unit 42 calculates the distance to the subject S by halving the round trip distance calculated above.

(First embodiment)
Here, a first embodiment will be described. In this embodiment, one pixel 321 in the light receiving section 3 includes four charge storage sections CS (charge storage sections CS1 to CS4). That is, the distance image imaging device 1 of this embodiment has a four-tap configuration. In this case, the pixel 321 in FIG. 3 further includes a pixel signal readout unit RU4. The pixel signal readout unit RU4 has the same configuration as the pixel signal readout unit RU1. Here, the charge storage section CS4 is an example of a "fourth charge storage section".

4 to 7 are timing charts showing the timing of driving pixels in the distance image imaging device of the first embodiment.
FIG. 4 shows a timing chart for a case where a plurality of pixels 321 in the light receiving section 3 are classified into one of two groups Gr1 and Gr2, and one frame consists of two subframes Sf1 and Sf2. An example is shown. Here, group Gr1 is an example of a "first group." Further, group Gr2 is an example of a "second group". Further, the period required for one frame is an example of a "frame period." Further, the period required for each of subframes Sf1 and Sf2 is an example of a "subframe period." Further, the period required for subframe Sf1 is an example of a "first subframe period." Further, the period required for subframe Sf2 is an example of a "second subframe period."

The items “REFRECTION”, “G1”, “G2”, “G3”, and “GD” in FIG. 4 are the same as in FIG. 18. Therefore, the explanation thereof will be omitted. "G4" indicates the timing of the drive signal TX4. The drive signal TX4 is a signal that drives the read transistor G4.

In Fig. 4, the horizontal axis indicates time t, and the scale on the horizontal axis is marked for each time section corresponding to "period To". "Period To" corresponds to the irradiation period of the light pulse PO and the accumulation period Ta of one charge accumulation unit CS. The light pulse PO is irradiated during the period from "0" to "1" on the horizontal axis scale. In this example, the case where the reflected light RL is incident during an incidence period R1 after the elapse of time Td1 from the irradiation of the light pulse PO, and the case where the reflected light RL is incident during an incidence period R2 after the elapse of time Td2 are shown.
In FIG. 4, the time Ton during which each gate (read transistors G1 to G4 and drain transistor GD) is in the on state is set to a time slightly shorter than the accumulation period Ta of each gate. This makes it possible to suppress charge discharge and charge distribution errors (crosstalk) caused by simultaneously generating the timing of changing the drain transistor GD from the on state to the off state and the timing of changing the first gate (read transistor G1) from the off state to the on state. In addition, it is possible to suppress charge distribution errors caused by simultaneously generating the timing of changing the first gate from the on state to the off state and the timing of changing the second gate (read transistor G2) from the off state to the on state. Similarly, by setting the timing relationship between the second gate and the third gate (read transistor G3) and the relationship between the third gate and the drain transistor GD to the timing shown in FIG. 4, it is possible to suppress charge discharge and charge distribution errors. The same applies to the timing charts shown in FIG. 5 to FIG. 7.

“Gr1, Sf1” in FIG. 4 shows a timing chart for driving pixels belonging to group Gr1 in subframe Sf1. "Gr2, Sf1" indicates a timing chart for driving pixels belonging to group Gr2 in subframe Sf1. “Gr1, Sf2” indicates a timing chart for driving pixels belonging to group Gr1 in subframe Sf2. “Gr2, Sf2” indicates a timing chart for driving pixels belonging to group Gr2 in subframe Sf2.

The incident period R1 shown in FIG. 4 spans the period in which the readout transistors G3 and G4 are in the on state in "Gr1, Sf1", and in this case, charges corresponding to the reflected light RL are transferred to the charge storage units CS3 and CS4. It is accumulated across the board.

This indicates that the incident period R1 is the reflected light from the subject S located approximately at the upper limit of the distance that can be measured with the conventional 4-tap configuration without subframes. That is, a subject S located further away is incident later than the incident period R1, and cannot be measured with the conventional 4-tap configuration. For example, during the incident period R2, the reflected light RL is incident later than the incident period R1, and charges corresponding to the reflected light RL cannot be accumulated in any of the readout transistors G in the conventional 4-tap configuration. Therefore, distance cannot be measured.

As a countermeasure against this, in this embodiment, the plurality of pixels 321 included in the distance image capturing device 1 are classified into groups Gr1 and Gr2. Then, the timing control unit 41 controls the groups Gr1 and Gr2 to operate in conjunction with each other at different timings.

Specifically, as shown in "Gr1, Sf1", the timing control unit 41 sequentially turns on the readout transistors G1 to G4 in the pixels belonging to the group Gr1, and charges are accumulated in the charge storage units CS1 to CS4 in order. do it like this.

Further, as shown in "Gr2, Sf1", the timing control unit 41 controls the readout transistor G1 in the pixel belonging to the group Gr2 at the timing when the readout transistor G4 in the pixel belonging to the group Gr1 changes from the on state to the off state. G4 is turned on in order so that charge is accumulated in charge storage sections CS1 to CS4 in order. That is, the timing control unit 41 sequentially distributes and stores charges in each of the charge storage units CS1 to CS4 in the pixel 321 belonging to the group Gr1 and the charge accumulation units CS1 to CS4 in the pixel 321 belonging to the group Gr2.

That is, the timing control section 41 controls the charge storage sections CS so that the respective storage periods Ta do not overlap. Thereby, the delay time Td of the reflected light RL that can be received by the distance image capturing device 1 is expanded.

As a result, the incident period R2 extends over the period in which the readout transistors G3 and G4 shown in "Gr2, Sf1" are in the on state, and the charge according to the reflected light RL is accumulated in the pixel 321 belonging to the group Gr2. The information is stored across the sections CS3 and CS4. That is, with the "configuration in which groups Gr1 and Gr2 operate in conjunction with each other at different timings" of this embodiment, the apparent number of taps can be set to 8, which can be increased from the actual number of taps of 4. Therefore, it becomes possible to measure the distance to the subject S corresponding to the incident period R2, which could not be measured with the 4-tap configuration, without increasing the number of subframes.

In FIG. 4, one frame is configured to include two subframes Sf1 and Sf2. This configuration is not a configuration for increasing the apparent number of taps, but is a configuration for evenly distributing external light noise to the two groups Gr, as described below.

As shown in "Gr1, Sf1" and "Gr2, Sf2", the timing control unit 41 determines the timing to drive the pixel 321 belonging to the group Gr1 in the subframe Sf1, and the timing to drive the pixel 321 belonging to the group Gr2 in the subframe Sf2. control is performed so that the timing at which the first timing is set is the same timing (an example of the "first timing").

Further, as shown in "Gr2, Sf1" and "Gr1, Sf2", the timing control unit 41 determines the timing for driving the pixel 321 belonging to the group Gr2 in the subframe Sf1, and the timing for driving the pixel 321 belonging to the group Gr1 in the subframe Sf2. Control is performed so that the timing at which the driver is driven is the same timing (an example of "second timing").

In this way, in FIG. 4, the drive timing in subframe Sf1 and the drive timing in subframe Sf2 are alternately swapped for each group. Thereby, it is possible to prevent specific external light noise from being accumulated in one of the groups Gr. The unique external light noise here is the external light that can be accumulated when the driving timing of the group Gr is not changed for each subframe Sf. For example, the external light that is linked to the period of the subframe is periodically This is a case that occurs in In other words, with the configuration in which the driving timing of the groups Gr is alternately changed for each subframe, even if external light that is linked to the period of the subframe is generated periodically, the external light component is transferred to the groups Gr1, The pixels 321 belonging to Gr2 can be made to receive light in a substantially evenly distributed manner. Therefore, it is possible to improve measurement accuracy compared to the case where unique external light noise is received biased to only one group.

FIG. 5 is a timing chart in a case where a plurality of pixels 321 in the light receiving section 3 are classified into one of two groups Gr1 and Gr2, and one frame consists of four subframes Sf1 to Sf4. An example is shown. In FIG. 5, "Gr1, Sf3" indicates a timing chart for driving pixels belonging to group Gr1 in subframe Sf3. “Gr2, Sf3” indicates a timing chart for driving pixels belonging to group Gr2 in subframe Sf3. “Gr1, Sf4” indicates a timing chart for driving pixels belonging to group Gr1 in subframe Sf4. "Gr2, Sf4" indicates a timing chart for driving pixels belonging to group Gr2 in subframe Sf4. Note that items in FIG. 5 that have the same item names as those in FIG. 4 are the same as those in FIG. 4, and therefore their explanations will be omitted.

As shown in FIG. 5, the timing control unit 41 controls the groups Gr1 and Gr2 to operate in conjunction with each other at different timings over subframes Sf1 to Sf4.

Specifically, as shown in "Gr1, Sf1", in subframe Sf1, the timing control unit 41 sequentially turns on the readout transistors G1 to G4 in the pixels belonging to group Gr1, and sequentially turns on the readout transistors G1 to G4 in the charge storage units CS1 to CS4. Allows charge to accumulate.

Furthermore, as shown in "Gr2, Sf1", the timing control unit 41 controls the pixel belonging to the group Gr2 at the timing when the readout transistor G4 in the pixel belonging to the group Gr1 changes from the on state to the off state in the subframe Sf1. The read transistors G1 to G4 are sequentially turned on, so that charge is accumulated in the charge storage sections CS1 to CS4 in order.

Further, as shown in "Gr1, Sf2", in subframe Sf2, the timing control unit 41 controls the group The readout transistors G1 to G4 in the pixels belonging to Gr1 are sequentially turned on, so that charges are accumulated in the charge storage sections CS1 to CS4 in order.

Further, as shown in "Gr2, Sf2", the timing control unit 41 controls the pixel belonging to the group Gr2 at the timing when the readout transistor G4 in the pixel belonging to the group Gr1 changes from the on state to the off state in the subframe Sf2. The read transistors G1 to G4 are sequentially turned on, so that charge is accumulated in the charge storage sections CS1 to CS4 in order.

That is, the timing control unit 41 sequentially distributes and stores charges in each of the charge storage units CS1 to CS4 in the pixel 321 belonging to the group Gr1 and the charge accumulation units CS1 to CS4 in the pixel 321 belonging to the group Gr2 in the subframe Sf1. By setting the apparent number of taps to 8, the measurable range is expanded.

Further, in subframe Sf2, the timing control unit 41 controls charge storage units CS1 to CS4 in the pixels 321 belonging to group Gr1 and charge storage units CS1 to CS4 in the pixels 321 belonging to group Gr2 from the timing when the accumulation in subframe Sf1 ends. Charge is distributed and accumulated in each of them in order, and the apparent number of taps is further increased by 8 taps, making the total apparent number of taps 16 taps.

This allows the measurable range to be further expanded. Furthermore, by forming one frame into four subframes, the time required for measurement becomes shorter than when the apparent number of taps is 16. Therefore, even if the object is a moving object, it is possible to suppress deterioration in measurement accuracy compared to a configuration in which one frame has four subframes.

In FIG. 5, one frame is configured to include two subframes Sf3 and Sf4 in addition to the above two subframes Sf1 and Sf2. This configuration is not a configuration for increasing the apparent number of taps, but is a configuration for allowing the two groups Gr to receive external light noise equally, as described below.

As shown in "Gr1, Sf1" and "Gr2, Sf3", the timing control unit 41 determines the timing to drive the pixel 321 belonging to the group Gr1 in the subframe Sf1, and the timing to drive the pixel 321 belonging to the group Gr2 in the subframe Sf3. control is performed so that the timing at which the first timing is set is the same timing (an example of the "first timing").

Further, as shown in "Gr2, Sf1" and "Gr1, Sf3", the timing control unit 41 determines the timing for driving the pixel 321 belonging to the group Gr2 in the subframe Sf1, and the timing for driving the pixel 321 belonging to the group Gr1 in the subframe Sf3. Control is performed so that the timing at which the driver is driven is the same timing (an example of "second timing").

Further, as shown in "Gr1, Sf2" and "Gr2, Sf4", the timing control unit 41 determines the timing for driving the pixel 321 belonging to the group Gr1 in the subframe Sf2, and the timing for driving the pixel 321 belonging to the group Gr2 in the subframe Sf4. Control is performed so that the timing at which the driver is driven is the same timing (an example of "first timing").

Further, as shown in "Gr2, Sf2" and "Gr1, Sf4", the timing control unit 41 determines the timing for driving the pixel 321 belonging to the group Gr2 in the subframe Sf2, and the timing for driving the pixel 321 belonging to the group Gr1 in the subframe Sf4. Control is performed so that the timing at which the driver is driven is the same timing (an example of "second timing").

In this manner, in FIG. 5, the drive timings are alternately exchanged for each group Gr between the drive timings in subframes Sf1 and Sf2 and the drive timings in subframes Sf3 and Sf4. As a result, even if external light noise linked to the subframe cycle occurs periodically, the pixels 321 belonging to groups Gr1 and Gr2 can receive the external light component almost equally. . Therefore, it is possible to improve measurement accuracy compared to the case where unique external light noise is received biased to only one group.

Similar to FIG. 4, FIG. 6 shows a case where a plurality of pixels 321 in the light receiving section 3 are classified into one of two groups Gr1 and Gr2, and one frame is divided into two subframes Sf1 and Sf2. An example of a timing chart in the case of the following is shown. Since the items in FIG. 6 are the same as those in FIG. 4, their explanation will be omitted.

In FIG. 6, the timing control unit 41 controls the groups Gr1 and Gr2 so that the drive timings of the groups Gr1 and Gr2 partially overlap when controlling the groups Gr1 and Gr2 to operate in conjunction with each other at different timings. This differs from FIG. 4 in this point.

Specifically, as shown in "Gr1, Sf1", the timing control unit 41 sequentially turns on the readout transistors G1 to G4 in the pixels belonging to the group Gr1, and charges are accumulated in the charge storage units CS1 to CS4 in order. do it like this.

Further, as shown in "Gr2, Sf1", the timing control unit 41 controls the readout transistor G1 in the pixel belonging to the group Gr2 at an arbitrary timing while the readout transistor G4 in the pixel belonging to the group Gr1 is in the on state. to G4 are sequentially turned on, and from then on, charge is accumulated in the charge storage sections CS1 to CS4 in order.

That is, the timing control unit 41 controls the accumulation period Ta of the charge accumulation unit CS4 in the pixel 321 belonging to group Gr1 to overlap with a portion of the accumulation period Ta of the charge accumulation unit CS1 in the pixel 321 belonging to group Gr2. This prevents the measurement accuracy from deteriorating when reflected light RL is incident at the timing Ts when driving of group Gr1 is switched to driving of group Gr2.

In FIG. 6, one frame is configured to include two subframes Sf1 and Sf2. This configuration is not intended to increase the apparent number of taps, but rather to distribute external light noise evenly to the two groups Gr. This configuration is the same as that in FIG. 4. Therefore, its description will be omitted.

As with FIG. 6, FIG. 7 shows an example of a timing chart in which the pixels 321 in the light receiving section 3 are classified into one of two groups, Gr1 and Gr2, and one frame consists of four subframes Sf1 to Sf4. The items in FIG. 7 are the same as those in FIG. 6, so their explanation will be omitted.

As shown in FIG. 7, the timing control unit 41 controls the groups Gr1 and Gr2 to operate in conjunction with each other at different timings over subframes Sf1 and Sf2. At this time, the timing control unit 41 controls so that the drive timings of the groups Gr1 and Gr2 partially overlap. This configuration is similar to that in FIG. Therefore, the explanation thereof will be omitted.

Further, in FIG. 7, one frame is configured to include two subframes Sf3 and Sf4 in addition to the above two subframes Sf1 and Sf2. This configuration is not a configuration for increasing the apparent number of taps, but is a configuration for allowing the two groups Gr to receive external light noise equally, as described below. This configuration is similar to that in FIG. Therefore, the explanation thereof will be omitted.

FIGS. 8 to 10 are diagrams showing examples of grouping of pixel groups in the distance image imaging device of the first embodiment. 8 to 10 schematically show pixels 321 arranged two-dimensionally.

As shown in FIG. 8, for example, each column of pixels 321 may be classified into two groups Gr1 and Gr2.
As shown in FIG. 9, for example, each row of pixels 321 may be classified into two groups Gr1 and Gr2.
As shown in FIG. 10, for example, each pixel 321 (pixel by pixel) may be classified into four groups Gr1 to Gr4. In this case, for example, the four pixels P1 to P4 are classified into four groups, and each group is driven at a different timing.

As described above, in this embodiment, the pixel group in the distance image capturing device may be classified into three or more groups, and each group may be driven at different timings. Even in this configuration, the same method as in the case of classifying into two groups Gr1 and Gr2 can be applied.

Further, the pixels 321 may be grouped according to the two-dimensional arrangement of the pixels 321. For example, when the pixels 321 are arranged in a horizontally long sensor in which the row direction is longer than the column direction, the control lines are generally mounted along the row direction. In this case, in view of ease of control, a configuration in which each row is classified into a different group is suitable.

As described above, in the first embodiment, a plurality of pixels 321 are arranged in a two-dimensional matrix, and each of the plurality of pixels 321 is assigned to one of two or more predetermined groups Gr1 and Gr2. It is classified as crab. The timing control unit 41 controls the storage periods Ta of the charge storage units CS in the pixels 321 belonging to each of the two or more groups Gr1 and Gr2 to have different timings for each group. Thereby, the groups Gr1 and Gr2 can be linked, and the apparent number of taps can be increased without increasing the number of subframes.

Further, in the first embodiment, the distance image imaging device 1 has a 4-tap configuration, and the timing control unit 41 sequentially controls the groups Gr1 and Gr2 so that the accumulation periods Ta of the respective charge accumulation units CS do not overlap. drive. This produces effects similar to those described above.
Further, in the first embodiment, the distance image capturing device 1 has a 4-tap configuration, and the timing control unit 41 sequentially drives the groups Gr1 and Gr2, and adjusts the accumulation period Ta of the charge accumulation unit CS4 of the group Gr1 and the group Control is performed so that at least a part of the period overlaps with the storage period Ta of the charge storage section CS1 of Gr2. Thereby, it is possible to perform control such that driving of group Gr2 is started before driving of group Gr1 is ended, and it is possible to improve measurement accuracy.
Furthermore, in the first embodiment, one frame is composed of a plurality of subframes Sf1 and Sf2, and the timing control unit 41 drives group Gr2 in subframe Sf2 at the timing when group Gr1 is driven in subframe Sf1. let Further, the timing control unit 41 drives the group Gr1 in the subframe Sf2 at the timing when the group Gr2 is driven in the subframe Sf1. Thereby, it is possible to prevent external light noise from being accumulated in one group, and to suppress deterioration of measurement accuracy. Furthermore, in the first embodiment, when increasing the number of subframes, it is possible to increase resistance to external light or increase the apparent number of taps.

(Second embodiment)
Next, a second embodiment will be described. In this embodiment, one pixel 321 in the light receiving section 3 includes three charge storage sections CS (charge storage sections CS1 to CS3). That is, the distance image imaging device 1 of this embodiment has a three-tap configuration.

FIG. 11 is a diagram illustrating an example of grouping of pixel groups in the distance image capturing device of the second embodiment. FIG. 11 shows an example in which pixels 321 arranged two-dimensionally are classified into one of two groups Gr1 and Gr2 alternately in the vertical and horizontal directions in a houndstooth pattern. TX_CTRL[0] in FIG. 11 is a timing signal that drives the pixels 321 classified into group Gr1. Furthermore, TX_CTRL[1] is a timing signal for driving the pixels 321 classified into group Gr2.

FIG. 12 is a timing chart showing the timing of driving pixels in the distance image capturing device of the second embodiment.
Among the items shown in FIG. 12, "Gr1" indicates a timing chart for driving pixels belonging to group Gr1. "Gr2" indicates a timing chart for driving pixels belonging to group Gr2. In "Gr1_Camera", the timings at which read transistors G1, G2, G3 and drain transistor GD belonging to group Gr1 turn on are indicated by "G1", "G2", "G3", and "GD", respectively. There is. In "Gr2_Camera", the timings at which read transistors G1, G2, G3 and drain transistor GD belonging to group Gr2 turn on are indicated by "G1", "G2", "G3", and "GD", respectively. There is. In "Synthesis", the charges when groups Gr1 and Gr2 are synthesized are shown as "G1", "G2", "G3", "G4" and "GD", respectively.

Note that among the items shown in FIG. 12, "Light", "G1", "G2", "G3", and "GD" are the same as in FIG. 18. Therefore, the explanation thereof will be omitted.

In FIG. 12, the timing control unit 41 performs control so that charges are accumulated in the charge accumulation units CS of both groups Gr1 and Gr2 at timings that are likely to cause relatively poor accuracy in measurement. On the other hand, the timing control section 41 controls so that charges are accumulated only in one of the charge accumulation sections CS of the group Gr1 or Gr2 at a timing that is relatively unlikely to cause deterioration of accuracy.

Here, the timing that is likely to cause relatively poor accuracy is the timing at which the reflected light RL from the subject S located at a relatively long distance is incident. On the other hand, the timings that are relatively unlikely to cause accuracy deterioration are the timing at which external light (background light) is received and the timing at which the reflected light RL from the subject S located at a relatively short distance is incident. This is because the amount of light has the property of decreasing in inverse proportion to the square of the distance.

Specifically, first, the timing control section 41 causes charges to be accumulated only in the charge accumulation section CS1 in the pixel 321 belonging to the group Gr1 during the external light accumulation period Tn in which the optical pulse PO is not irradiated.
Next, the timing control section 41 causes charges to be accumulated only in the charge accumulation section CS1 in the pixel 321 belonging to the group Gr2 during the first reflected light accumulation period T1 during which the optical pulse PO is irradiated.
Next, the timing control unit 41 controls the charge storage section CS2 in the pixel 321 belonging to the group Gr1 and the charge in the pixel 321 belonging to the group Gr2 in the second reflected light accumulation period T2 after the first reflected light accumulation period T1 has elapsed. Charges are accumulated in both of the accumulation sections CS2.

Then, during the third reflected light accumulation period T3 after the second reflected light accumulation period T2 has elapsed, the timing control unit 41 accumulates charge in the charge accumulation unit CS3 in the pixel 321 belonging to group Gr1 and in the charge accumulation unit CS3 in the pixel 321 belonging to group Gr2. This makes it possible to prevent the amount of light received from decreasing compared to when the reflected light is received from a short distance, even when the reflected light is received from a relatively long distance. Therefore, it is possible to prevent deterioration in the accuracy of the measurement.

Note that the synthesis method may be arbitrary. Synthesis here means combining the charge accumulated by driving group Gr1 and a signal corresponding to the charge with the charge accumulated by driving group Gr2 and a signal corresponding to the charge. This is the process of For example, the distance calculation unit 42 performs a combining process and calculates a distance using the combined result. In this case, the distance calculation unit 42 generates charges that are twice the charges accumulated in the external light accumulation period Tn and the first reflected light accumulation period T1, the second reflected light accumulation period T2, and the third reflected light accumulation period Tn. Combination is performed using the charges obtained by adding the charges accumulated in T3. Alternatively, the charges accumulated in the external light accumulation period Tn and the first reflected light accumulation period T1, and the charges accumulated in the second reflected light accumulation period T2 and the third reflected light accumulation period T3, respectively, are added and averaged. It may also be possible to use it for synthesis.

FIG. 13 is a diagram illustrating an example of grouping of pixel groups in the distance image capturing device of the second embodiment. In FIG. 13, pixels 321 arranged two-dimensionally span two columns in the vertical direction, and are alternately classified into one of two groups Gr1 and Gr2 in the first column, and two groups are alternately classified in the second column. An example is shown in which the images are classified into either group Gr3 or Gr4 and the combination of the first and second columns is expanded in the horizontal direction. TX_CTRL[0] and TX_CTRL[1] in FIG. 13 are the same as in FIG. 11. TX_CTRL[2] is a timing signal that drives the pixels 321 classified into group Gr3. Furthermore, TX_CTRL[3] is a timing signal for driving the pixels 321 classified into group Gr4.

In this manner, in this embodiment, the pixel group in the distance image imaging device 1 may be classified into three or more groups, and each group may be driven at different timings. Even in this configuration, the same method as in the case of classifying into two groups Gr1 and Gr2 can be applied.

In this embodiment, one frame may include a plurality of subframes. FIG. 14 is a diagram for explaining an example of a process of composing a plurality of subframes in the distance image capturing apparatus according to the second embodiment.
The timing control unit 41 drives each group at different timings in each subframe. In the following, a case where one frame consists of two subframes Sf1 and Sf2 will be explained as an example, but the present invention is not limited to this. Even when one frame is composed of three or more subframes, the combining method described below can be applied.

Further, in this embodiment, similarly to the first embodiment, the timing control unit 41 may drive group Gr2 in subframe Sf2 at the timing at which group Gr1 is driven in subframe Sf1. Alternatively, the timing control unit 41 may control the drive timings of the groups Gr1 and Gr2 in both subframes Sf1 and Sf2 so as not to change. Processing can be simplified by not changing the drive timing.

As shown in FIG. 14, the distance image capturing device 1 alternately repeats the process using the subframe Sf1 (processing F1) and the process using the subframe Sf2 (processing F2).
At timing Tm1, the distance image imaging device 1 stores the processing result of the process F1 in the frame memory, and temporarily holds the processing result of the subframe Sf1 (processing F4).
The distance image imaging device 1 stores the processing result of the process F2 in the frame memory at timing Tm2 following the timing Tm1, and temporarily holds the processing result of the subframe Sf2 (processing F3).
The distance image imaging device 1 combines the two processing results of subframe Sf1 and subframe Sf2 using the processing result of processing F3 and the processing result of processing F1 at timing Tm3 following timing Tm2. (Processing F5).
At timing Tm2, the distance image imaging device 1 combines the two processing results of subframe Sf2 and subframe Sf1 using the processing result of processing F4 and the processing result of processing F2 (processing F6).

As described above, in the second embodiment, the distance image capturing device 1 has a three-tap configuration, and the timing control unit 41 causes the charge storage unit CS1 of the group Gr1 to accumulate charges during the external light accumulation period Tn, During the first reflected light accumulation period T1, charge is accumulated in the charge accumulation section CS1 of group Gr2. Furthermore, the timing control section 41 causes the charge storage sections CS2 of both groups Gr1 and Gr2 to accumulate charges in the second reflected light accumulation period T2. Furthermore, the timing control section 41 causes the charge storage sections CS2 of both groups Gr1 and Gr2 to accumulate charges in the third reflected light accumulation period T3. Thereby, even when measuring a long distance where the amount of received light is reduced compared to a short distance, it is possible to suppress deterioration of measurement accuracy.

In the second embodiment, one frame is made up of multiple subframes, and the distance calculation unit 42 combines the amount of charge accumulated in the charge accumulation unit CS in each of the multiple subframes. This makes it possible to increase the apparent number of taps by using both the method of dividing the pixel group into multiple groups and driving them, and the method of using subframes, and achieves the same effect as described above.

(Third embodiment)
Next, a third embodiment will be described. In this embodiment, one pixel 321 in the light receiving section 3 includes three charge storage sections CS (charge storage sections CS1 to CS3). That is, the distance image imaging device 1 of this embodiment has a three-tap configuration.

In this embodiment, the timing control unit 41 controls the drive timing of the charge storage unit CS so as to increase the number of distance regions with high distance resolution. That is, the timing control unit 41 can drive the pixels 321 belonging to the group Gr1 at the conventional light reception timing as shown in FIG. The pixels 321 belonging to the group Gr2 are driven so that the range of the distance becomes larger.
Details of this embodiment will be explained below using FIGS. 15 to 17.

15 to 17 are timing charts showing the timing of driving pixels in the distance image capturing device of the third embodiment.
Among the items shown in FIGS. 15 to 17, "Gr1 or Sf1" indicates a timing chart for driving the pixel 321 belonging to the group Gr1 or the pixel 321 in the subframe Sf1. “Gr2 or Sf2” indicates a timing chart for driving the pixel 321 belonging to the group Gr2 or the pixel 321 in the subframe Sf1.
Among the items shown in FIGS. 15 to 17, "Light", "G1", "G2", "G3", and "GD" are the same as in FIG. 18. Therefore, the explanation thereof will be omitted.

In FIG. 15, first, the timing control unit 41 causes the charge accumulation unit CS1 belonging to both the groups Gr1 and Gr2 to accumulate charges during the external light accumulation period Tn.
Next, the timing control unit 41 causes the charge accumulation unit CS2 belonging to the group Gr1 to accumulate charges during the first reflected light accumulation period T1.
Next, the timing control unit 41 accumulates charge in the charge accumulation unit CS2 belonging to group Gr2 during a reflected light accumulation period T105, which is shifted (delayed) by half the accumulation period Ta (Ta/2) from the first reflected light accumulation period T1.
Next, the timing control unit 41 causes the charge accumulation unit CS3 belonging to the group Gr1 to accumulate charges during the second reflected light accumulation period T2.
Next, the timing control unit 41 accumulates charge in the charge accumulation unit CS3 belonging to group Gr2 during a reflected light accumulation period T205, which is shifted (delayed) by half the accumulation period Ta (Ta/2) from the second reflected light accumulation period T2.

Thereby, the charge storage unit CS2 of the group Gr2 can be stored to include the timing Tp1 at which the charge storage unit CS2 in the group Gr1 switches to the charge storage unit CS3. Therefore, it is possible to accumulate charges with high accuracy at timing Tp1. Further, after the timing Tp2 at which the accumulation in the charge accumulation section CS3 in the group Gr1 is ended, the accumulation in the charge accumulation section CS3 in the group Gr2 can be performed. Therefore, the amount of charge corresponding to the reflected light RL incident after timing Tp2 can be accumulated, and the range of distance that can be measured can be expanded.
In addition, in this example, the accumulation period (first reflected light accumulation period T1, second reflected light accumulation period T2) of the charge accumulation sections CS2 and CS3 belonging to the group Gr1 and the accumulation period of the charge accumulation sections CS2 and CS3 belonging to the group Gr2 are explained. The period (reflected light accumulation period T105, T205) is shifted by half (Ta/2) of the accumulation period Ta. Thereby, in both groups Gr1 and Gr2, charges can be distributed and stored in the charge storage sections CS2 and CS3 at a substantially equal distribution ratio. Therefore, the range of distances with high distance resolution can be increased. Further, in a portion where the accumulation periods overlap between the groups Gr1 and Gr2, charges can be accumulated in the two charge accumulation sections CS. Therefore, the time resolution can be doubled compared to the case where charges are accumulated in one charge accumulation section CS. Therefore, it becomes possible to measure distance with high accuracy.
In addition, by "shifting by half", the "edge locations" where it is difficult to accumulate charge accurately in group Gr1 become the "center locations" where it is possible to accumulate charges accurately in group Gr2. can be controlled. The "end point" is the timing of switching the charge storage section CS from the on state to the off state. The "middle point" is the timing in the middle of the period from when the charge storage section CS is turned on to when it is turned off. In other words, the groups Gr1 and Gr2 complement each other, thereby suppressing a decrease in measurement accuracy.
However, strictly speaking, "shifting by half" the accumulation period Ta does not necessarily provide control that allows for the most accurate measurement. In reality, factors that degrade measurement may include distortions in optical pulses, delays in charge transfer, and distortions in electrical pulses applied to transfer electrodes. In view of the complementary relationship with such deterioration factors, it is desirable to perform control so that the storage periods of groups Gr1 and Gr2 are shifted by "a time effectively equivalent to half of the storage period Ta."

In FIG. 16, first, the timing control unit 41 causes the charge accumulation unit CS1 belonging to the group Gr1 to accumulate charges during the external light accumulation period Tn.
Next, the timing control unit 41 causes the charge accumulation unit CS1 belonging to group Gr2 to accumulate charge during accumulation period Tn05, which is shifted (delayed) from the external light accumulation period Tn by half (Ta/2) of the accumulation period Ta.
Next, the timing control unit 41 causes the charge accumulation unit CS2 belonging to the group Gr1 to accumulate charges during the first reflected light accumulation period T1.
Next, the timing control unit 41 accumulates charge in the charge accumulation unit CS2 belonging to group Gr2 during a reflected light accumulation period T105, which is shifted (delayed) by half the accumulation period Ta (Ta/2) from the first reflected light accumulation period T1.
Next, the timing control unit 41 causes the charge accumulation unit CS3 belonging to the group Gr1 to accumulate charges during the second reflected light accumulation period T2.
Next, the timing control unit 41 accumulates charge in the charge accumulation unit CS3 belonging to group Gr2 during a reflected light accumulation period T205, which is shifted (delayed) by half the accumulation period Ta (Ta/2) from the second reflected light accumulation period T2.

Thereby, the charge storage unit CS1 of the group Gr2 can be stored so as to include the timing Tp0 at which the charge storage unit CS1 in the group Gr1 switches to the charge storage unit CS2. Therefore, it is possible to accurately accumulate the amount of charge according to the reflected light RL incident at timing Tp0. In other words, it is suitable for measuring a subject S located at a short distance.
Further, as in FIG. 15, it is possible to accumulate charges with high accuracy at timing Tp1. Further, as in FIG. 15, the amount of charge can be accumulated in the period after timing Tp2, and the measurable distance can be expanded.

In FIG. 17, first, the timing control unit 41 causes the charge storage unit CS1 belonging to the group Gr1 to accumulate charges during the external light accumulation period Tn.
Next, the timing control unit 41 causes the charge storage unit CS2 belonging to the group Gr1 to accumulate charges during the first reflected light accumulation period T1.
Next, the timing control unit 41 stores charges belonging to group Gr2 in a reflected light accumulation period T105 that is shifted (delayed) by half (Ta/2) of the accumulation period Ta from the first reflected light accumulation period T1. Charge is accumulated in the portion CS1.
Next, the timing control unit 41 causes the charge storage unit CS3 belonging to the group Gr1 to accumulate charges during the second reflected light accumulation period T2.
Next, the timing control unit 41 stores charges belonging to group Gr2 in a reflected light accumulation period T205 that is shifted (delayed) by half (Ta/2) of the accumulation period Ta from the second reflected light accumulation period T2. Charge is accumulated in part CS2.
Next, after the reflected light accumulation period T205 has elapsed, the timing control section 41 causes the charge accumulation section CS3 belonging to the group Gr2 to accumulate charges in the reflected light accumulation period T305.

Thereby, the amount of charge can be accumulated in a longer period after timing Tp2 than in the case of FIG. 16, and it is possible to expand the measurable distance. In other words, it is suitable for measuring a subject S located at a long distance.
Further, as in FIG. 15, it is possible to accumulate charges with high precision at timing Tp1.

As described above, the distance image imaging device 1 of the third embodiment has a three-tap configuration, and the timing control unit 41 charges the charge storage unit CS1 belonging to the groups Gr1 and Gr2 during the external light accumulation period Tn. is accumulated in the charge accumulation section CS2 belonging to the group Gr1 during the first reflected light accumulation period T1, and accumulated in the charge accumulation section CS3 belonging to the group Gr1 during the second reflected light accumulation period T2, During the reflected light accumulation period T105 (first period) including the timing Tp1 (end timing) at which the first reflected light accumulation period T1 ends, charge is accumulated in the charge storage section CS2 belonging to group Gr2, and the second reflected light accumulation period During the reflected light accumulation period T205 (second period) including the timing Tp2 (end timing) at which T2 ends, charges are accumulated in the charge accumulation section CS3 belonging to the group Gr2. Thereby, charges can be accumulated with high precision at timing Tp1, and distance resolution can be improved. Further, it is possible to accumulate charges corresponding to the reflected light RL incident after timing Tp2, and it is possible to expand the measurable distance.

Further, the distance image capturing device 1 of the third embodiment accumulates charges in the charge storage section CS1 belonging to the group Gr1 during the external light accumulation period Tn, and accumulates charges belonging to the group Gr1 during the first reflected light accumulation period T1. An accumulation period including a timing Tp0 (end timing) at which the charge storage section CS2 accumulates charges, the charge accumulation section CS3 belonging to the group Gr1 ends during the second reflected light accumulation period T2, and the external light accumulation period Tn ends. During Tn05 (first period), charge is accumulated in the charge storage unit CS1 belonging to group Gr2, and reflected light accumulation period T105 (second period) includes timing Tp1 (end timing) at which the first reflected light accumulation period T1 ends. , charges are accumulated in the charge accumulation unit CS2 belonging to the group Gr2, and during the reflected light accumulation period T205 (third period) including the timing Tp2 (end timing) at which the second reflected light accumulation period T2 ends, the charge accumulation unit CS2 belonging to the group Gr2 is stored. Charges are accumulated in the charge accumulation section CS3. Thereby, charges can be accumulated with high accuracy at timings Tp0 and Tp1, and distance resolution can be improved. Further, it is possible to accumulate charges corresponding to the reflected light RL incident after timing Tp2, and it is possible to expand the measurable distance.

Further, the distance image capturing device 1 of the third embodiment accumulates charges in the charge storage section CS1 belonging to the group Gr1 during the external light accumulation period Tn, and accumulates charges belonging to the group Gr1 during the first reflected light accumulation period T1. Accumulating charge in the storage unit CS2, accumulating charges in the charge storage unit CS3 belonging to group Gr1 during the second reflected light accumulation period T2, and including timing Tp1 (end timing) at which the first reflected light accumulation period T1 ends. During the reflected light accumulation period T105 (second period), charges are accumulated in the charge accumulation section CS1 belonging to group Gr2, and the reflected light accumulation period T205 (including the timing Tp2 (end timing) at which the second reflected light accumulation period T2 ends) During the third period), charges are accumulated in the charge accumulation section CS2 belonging to the group Gr2, and after the elapse of the reflected light accumulation period T205 (third period), charges are accumulated in the charge accumulation section CS3 belonging to the group Gr2. Thereby, charges can be accumulated with high precision at Tp1, and distance resolution can be improved. Furthermore, it is possible to accumulate charges corresponding to the reflected light RL incident after timing Tp2, and it is possible to further expand the measurable distance.

In addition, in the embodiment mentioned above, the case where the distance image imaging device 1 has a 4-tap configuration or a 3-tap configuration has been described as an example. However, it is not limited to this. The distance image capturing device 1 only needs to include at least a plurality of charge storage sections CS. That is, the distance image imaging device 1 may have an M tap configuration including M charge storage units CS (M is an integer of 2 or more).
Further, in the above-described embodiment, the case where each of the plurality of pixels 321 is classified into one of the two groups Gr1 and Gr2 has been described as an example, but the present invention is not limited to this. In the distance image imaging device 1, each of the pixels 321 may be divided into N groups (N is an integer of 2 or more).

According to each of the above embodiments, the apparent number of taps can be increased by a method different from the method of increasing the number of subframes.

1 Distance image imaging device 2 Light source section 3 Light receiving section 31 Lens 32 Distance image sensor 321 Pixel 4 Distance image processing section 41 Timing control section 42 Distance calculation section PD Photoelectric conversion element GD Drain transistor G Readout transistor CS Charge storage section PO Light pulse

Claims (7)

a light source unit that irradiates a light pulse into the measurement space;
A plurality of pixels arranged in a two-dimensional matrix are provided with a photoelectric conversion element that generates a charge according to the incident light, and three or more charge storage sections that accumulate the charge, and a plurality of pixels are arranged in a two-dimensional matrix, and the irradiation with the light pulse a pixel drive circuit that distributes and accumulates charges in each of the charge accumulation sections at a predetermined accumulation timing synchronized with the starting irradiation timing;
a timing control section that controls the accumulation timing;
a distance calculation unit that calculates a distance to an object existing in the measurement space based on the amount of charge accumulated in each of the charge storage units;
Equipped with
Each of the plurality of pixels is classified into one of two or more predetermined groups,
The timing control section includes:
The accumulation timing relative to the irradiation timing in pixels belonging to each of the two or more groups is different for each group,
During an external light accumulation period before the light pulse is irradiated, an external light component that does not include the reflected light of the light pulse is stored in the first charge storage section of the pixel belonging to the first group of the two or more groups. Accumulate the corresponding charge,
Charges corresponding to the reflected light and the light including the external light component are accumulated in the second charge accumulation section and the third charge accumulation section of the pixels belonging to the first group, and the charges are accumulated in the second group different from the first group. Charges corresponding to the external light component or the light including the reflected light and the external light component are accumulated in the three charge storage sections of the pixel to which it belongs,
Control is performed so that the next irradiation timing arrives after charge accumulation has been completed in all of the charge storage units included in pixels belonging to each of the two or more groups according to the irradiation timing;
Distance image imaging device. The timing control section includes:
Regarding the total accumulation time for accumulating charges in each of the charge accumulation sections in which charges are accumulated at the accumulation timing after the irradiation timing, the shorter the delay time from the irradiation timing, the smaller the total is. control such that the larger the sum, the larger the sum is;
The distance image imaging device according to claim 1. The plurality of charge storage units in the pixel include three charge storage units, a first charge storage unit, a second charge storage unit, and a third charge storage unit,
The timing control section includes:
accumulating charges in a first charge accumulation section in pixels belonging to the second group during a first reflected light accumulation period from the irradiation timing to the end of an irradiation period in which the light pulse is irradiated;
Accumulating the charges in a second charge accumulation section of pixels belonging to the first group during a second reflected light accumulation period from the timing at which the first reflected light accumulation period ends until a time corresponding to the irradiation period elapses. causing the charges to be accumulated in a second charge accumulation section in the pixels belonging to the second group;
Accumulating the charges in a third charge accumulation section in pixels belonging to the first group during a third reflected light accumulation period from the timing when the second reflected light accumulation period ends until a time corresponding to the irradiation period elapses. and causing the charge to be accumulated in a third charge accumulation section in the pixel belonging to the second group.
The distance image imaging device according to claim 2. The plurality of charge storage units in the pixel include three charge storage units, a first charge storage unit, a second charge storage unit, and a third charge storage unit,
The timing control section includes:
accumulating charges in a first charge accumulation section of pixels belonging to the second group during the external light accumulation period;
accumulating charges in a second charge accumulation section of pixels belonging to the first group during a first reflected light accumulation period from the irradiation timing until the end of an irradiation period in which the light pulse is irradiated;
During a second reflected light accumulation period from the timing at which the first reflected light accumulation period ends until a time corresponding to the irradiation period elapses, charges are accumulated in a third charge accumulation section in the pixels belonging to the first group. ,
a second charge storage section in a pixel belonging to the second group during a first semi-reflection light accumulation period from a timing before the irradiation period elapses after the irradiation of the light pulse starts until the end of the irradiation period; Accumulate a charge in
During a second half-reflection light accumulation period from the end of the first half-reflection light accumulation period to the end of a time corresponding to the irradiation period, charges are added to a third charge storage section in the pixels belonging to the second group. accumulate,
The distance image imaging device according to claim 2. The plurality of charge storage units in the pixel include three charge storage units, a first charge storage unit, a second charge storage unit, and a third charge storage unit,
The timing control section includes:
accumulating charges in a second charge accumulation section of pixels belonging to the first group during a first reflected light accumulation period from the irradiation timing until the end of an irradiation period in which the light pulse is irradiated;
During a second reflected light accumulation period from the timing at which the first reflected light accumulation period ends until a time corresponding to the irradiation period elapses, charges are accumulated in a third charge accumulation section in the pixels belonging to the first group. ,
In the pixels belonging to the second group during the half-delayed external light accumulation period from the timing before the time corresponding to the irradiation period has elapsed from the start of the external light accumulation period until the time corresponding to the irradiation period ends, accumulating charges in the first charge accumulating section;
During a first half-reflection light accumulation period from the end of the half-delayed external light accumulation period to the end of a time corresponding to the irradiation period, the charges are added to the second charge storage section of the pixels belonging to the second group. let it accumulate,
During a second half-reflection light accumulation period from the end of the first half-reflection light accumulation period to the end of a time corresponding to the irradiation period, the charges are stored in the third charge storage section of the pixels belonging to the second group. accumulate,
The distance image imaging device according to claim 1. The plurality of charge storage units in the pixel include three charge storage units, a first charge storage unit, a second charge storage unit, and a third charge storage unit,
The timing control section includes:
accumulating charges in a second charge accumulation section of pixels belonging to the first group during a first reflected light accumulation period from the irradiation timing until the end of an irradiation period in which the light pulse is irradiated;
During a second reflected light accumulation period from the timing at which the first reflected light accumulation period ends until a time corresponding to the irradiation period elapses, charges are accumulated in a third charge accumulation section in the pixels belonging to the first group. ,
In the second group during a first semi-reflected light accumulation period from a timing before a time corresponding to the irradiation period has elapsed from the start of the first reflected light accumulation period until a time corresponding to the irradiation period ends. accumulating charges in a first charge accumulating section in the pixel to which it belongs;
During a second half-reflection light accumulation period from the end of the first half-reflection light accumulation period to the end of a time corresponding to the irradiation period, the charge is stored in the second charge storage section of the pixels belonging to the second group. accumulate,
During the third half-reflection light accumulation period from the end of the second half-reflection light accumulation period to the end of the time corresponding to the irradiation period, the charge is stored in the third charge storage section of the pixels belonging to the second group. accumulate,
The distance image imaging device according to claim 2. It is equipped with a light source unit that irradiates a light pulse into the measurement space, a photoelectric conversion element that generates charges according to the incident light, and three or more charge storage units that accumulate charges, and is arranged in a two-dimensional matrix. a plurality of pixels, and a pixel drive circuit that distributes and accumulates charges in each of the charge accumulation sections at a predetermined accumulation timing synchronized with the irradiation timing at which irradiation of the light pulse is started; A distance image capturing device comprising: a timing control unit that controls the accumulation timing; and a distance calculation unit that calculates a distance to a subject existing in the measurement space based on the amount of charge accumulated in each of the charge accumulation units. A distance image imaging method performed by a device, the method comprising:
Each of the plurality of pixels is classified into one of two or more predetermined groups,
The timing control section includes:
The accumulation timing relative to the irradiation timing in pixels belonging to each of the two or more groups is different for each group,
During an external light accumulation period before the light pulse is irradiated, an external light component that does not include the reflected light of the light pulse is stored in the first charge storage section of the pixel belonging to the first group of the two or more groups. Accumulate the corresponding charge,
Charges corresponding to the reflected light and the light including the external light component are accumulated in the second charge accumulation section and the third charge accumulation section of the pixels belonging to the first group, and the charges are accumulated in the second group different from the first group. Charges corresponding to the external light component or the light including the reflected light and the external light component are accumulated in the three charge storage sections of the pixel to which it belongs,
Control is performed so that the next irradiation timing arrives after charge accumulation has been completed in all of the charge storage units included in pixels belonging to each of the two or more groups according to the irradiation timing;
Distance image imaging method.

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