JP2021131285A - Sensor device, distance measuring device, sensing method - Google Patents

Abstract

To improve the accuracy of distance measurement.SOLUTION: A sensor device is provided, comprising: a photoelectric conversion element; a first transfer gate element transferring an electric charge obtained by performing photoelectric conversion by the photoelectric conversion element and causing a first electric charge accumulation unit to accumulate the transferred electric charge; and a second transfer gate element transferring the electric charge obtained by performing photoelectric conversion by the photoelectric conversion element and causing a second electric charge accumulation unit to accumulate the transferred electric charge. This sensor device is constituted in such a manner that in one modulation period out of an accumulation period in which the irradiation of light that is received by the photoelectric conversion element repeats a light emission period and a non-light emission period as one modulation period, there occurs a non-transfer period in which neither the first transfer gate element nor the second transfer gate element performs transfer of electric charges.SELECTED DRAWING: Figure 11

Description

The present technology relates to a sensor device for distance measurement, a distance measuring device, and a sensing method of the sensor device.

Various distance measuring techniques for measuring the distance to a target object are known, and in recent years, for example, a distance measuring technique based on the ToF (Time of Flight) method has attracted attention.
A distance measuring technique based on the ToF method is disclosed in, for example, Patent Document 1.

JP-A-2009-8537

In a semiconductor detection element for measuring the distance to a distance measuring object (an object that becomes a reflector; hereinafter, also simply referred to as an "object") by the ToF method, the light emitted from the light source is reflected by the object. The reflected light is photoelectrically converted by a photodiode. The signal charge generated by the photoelectric conversion is distributed to two floating diffusions (charge storage units) by a pair of transfer gate elements driven alternately.
In a semiconductor detection element using such a pair of transfer gate element structures, due to a timing shift between transfer gate elements due to blunting of the transfer gate drive waveform or the like, the other transfer gate is turned on before the other transfer gate is turned off. May turn on. That is, both transfer gates open at the same time. This causes a period in which the signal charge generated by the photoelectric conversion is transferred to both of the two floating diffusions, which causes a problem that the distance measurement error increases.
The present technology has been made in view of such a situation, and an object thereof is to prevent deterioration of distance measurement accuracy due to opening of both pair of transfer gates.

The sensor device according to the present technology includes a photoelectric conversion element, a first transfer gate element that transfers charges obtained by performing photoelectric conversion with the photoelectric conversion element and stores them in a first charge storage unit, and the photoelectric conversion element. The second transfer gate element that transfers the electric charge obtained by performing the photoelectric conversion in the above and stores it in the second charge storage unit, and the irradiation of the light received by the photoelectric conversion element monomodulates the light emitting period and the non-light emitting period. The first transfer gate element and the said A transfer gate drive unit for driving the second transfer gate element is provided.
In the distance measurement by the indirect ToF (indirect ToF) method, the distance to the object is calculated based on the phase difference between the irradiation light for the object and the reflected light obtained by reflecting the irradiation light by the object. Specifically, the sensor device side calculates the distance to the object from the ratio of the amount of charge distributed to the first charge storage unit and the second charge storage unit. In this case, within the light emission cycle, a period during which the charge is not transferred to either the first charge storage unit or the second charge storage unit is set.

In the sensor device according to the present technology described above, in the storage period, the non-transfer period, the period in which the first transfer gate element is in the transfer state, the non-transfer period, and the second transfer gate element in the transfer state. It is conceivable to drive the first transfer gate element and the second transfer gate element so that a cycle in the order of the period to be performed occurs.
That is, a non-transfer period is always generated when the period in which the first transfer gate element is in the transfer state and the period in which the second transfer gate element is in the transfer state are switched.

In the sensor device according to the present technology described above, the transfer gate drive unit includes a first transfer drive signal that controls the first transfer gate element to a transfer state within the light emission period, and the first transfer gate drive signal during the non-light emission period. 2 The transfer period of the first transfer gate element is set by the pulse duty of the first transfer drive signal and the second transfer drive signal while outputting the second transfer drive signal that controls the transfer gate element to the transfer state. It is conceivable that the non-transfer period occurs by making the transfer period of the second transfer gate element shorter than the light emitting period and shorter than the non-light emitting period.
For example, in the transfer gate drive unit, the transfer period of the first transfer gate element is shorter than the light emission period due to the setting of the pulse duty of the first transfer drive signal and the second transfer drive signal, and the transfer period of the second transfer gate element is not. Make it shorter than the light emission period.

In the sensor device according to the present technology described above, when the light emitting period and the non-light emitting period have the same period length, the first transfer drive signal for controlling the first transfer gate element to the transfer state within the light emitting period. The non-transfer period is generated by setting the pulse duty of It is conceivable to do so.
When the light emission period length and the non-light emission period length are the same on the light irradiation side, normally, the first transfer drive signal and the second transfer drive signal each have a pulse duty of 50% to correspond to the light emission period. The first transfer gate element is put into the transfer state, and the second transfer gate element is put into the transfer state corresponding to the non-light emitting period. By setting these pulse duties to less than 50%, a period during which the first and second transfer gate elements are not transferred is provided.

In the sensor device according to the present technology described above, it is conceivable to variably set the pulse duty of the first transfer drive signal and the pulse duty of the second transfer drive signal.
For example, calibration is performed to obtain a pulse duty so as to maximize the transfer efficiency, and the pulse duty is set to that pulse duty.

In the sensor device according to the present technology described above, it is conceivable to variably set the pulse duty of the first transfer drive signal and the pulse duty of the second transfer drive signal according to the transfer gate drive frequency.
Depending on the transfer gate drive frequency, the degree of influence of the waveform blunting of the transfer gate drive signal differs. Therefore, the pulse duty is variably set according to the transfer gate drive frequency.

In the sensor device according to the present technology described above, the end timing of the light emitting period and the end timing of the transfer state of the first transfer gate element are matched, and the end timing of the non-light emitting period and the transfer of the second transfer gate element are matched. It is conceivable to drive the first transfer gate element and the second transfer gate element so that the end timings of the states are matched.
That is, the non-transfer period is provided at the beginning side of the light emitting period and the beginning side of the non-light emitting period.

In the sensor device according to the present technology described above, the first transfer gate element and the first transfer gate element and the first transfer gate element are set by the transfer gate drive unit by setting the threshold voltage of the first transfer gate element and the threshold voltage of the second transfer gate element. 2 It is conceivable that the non-transfer period occurs when the transfer gate element is driven.
That is, the threshold voltage of the first transfer gate element and the second transfer gate element is designed to be higher than usual.

The ranging device according to the present technology includes a light emitting unit that irradiates light so as to repeat a light emitting period and a non-light emitting period as one modulation period, and the above-mentioned photoelectric conversion element, first transfer gate element, and second transfer gate element. A sensor device having a transfer gate drive unit is provided.
In the sensing method of the sensor device according to the present technology, the first transfer gate element within the one modulation period during the accumulation period in which the irradiation of the light received by the photoelectric conversion element repeats the light emission period and the non-light emission period as one modulation period. The first transfer gate element and the second transfer gate element are driven so that a non-transfer period occurs in which both the second transfer gate element and the second transfer gate element do not transfer charges. This prevents a period in which the first transfer gate element and the second transfer gate element are turned on at the same time.

It is a block diagram of the distance measuring device of embodiment of this technique. It is explanatory drawing of the timing of the irradiation light and the transfer drive signal of the modulation period of a distance measuring device. It is explanatory drawing of the operation timing of a distance measuring device. It is a block diagram of the sensor part of embodiment. It is an equivalent circuit diagram of the pixel circuit of the sensor part of embodiment. It is explanatory drawing of the pixel structure of the sensor part of embodiment. It is explanatory drawing of the pixel structure of the sensor part of embodiment. It is explanatory drawing of the transition of the potential energy of electric charge in a pixel circuit. It is a waveform diagram of the transfer drive signal of the comparative example. It is explanatory drawing of the transition of the potential energy of the electric charge of the comparative example. It is a waveform diagram of the transfer drive signal of 1st Embodiment. It is explanatory drawing of the transition of the potential energy of the electric charge of 1st Embodiment. It is explanatory drawing of the light emitting period and non-light emitting period of the irradiation light of 1st Embodiment, and the timing of the end of transfer. It is a waveform diagram of the transfer drive signal of the 2nd Embodiment.

Hereinafter, embodiments according to the present technology will be described in the following order with reference to the accompanying drawings.
<1. Distance measuring device configuration>
<2. Circuit configuration of sensor section>
<3. Circuit configuration of pixel array section>
<4. Sensor unit structure>
<5. First Embodiment>
<6. Second Embodiment>
<7. Summary and modification>

<1. Distance measuring device configuration>
FIG. 1 is a block diagram for explaining a configuration example of the ranging device 10 as an embodiment according to the present technology.
The distance measuring device 10 includes a sensor unit 1, a light emitting unit 2, a control unit 3, a distance image processing unit 4, and a memory 5. The distance measuring device 10 is a device that performs distance measuring by the ToF (Time of Flight) method. Specifically, the distance measuring device 10 of this example performs distance measurement by an indirect ToF (indirect ToF) method. The indirect ToF method is a distance measuring method that calculates the distance to the object Ob based on the phase difference between the irradiation light Li for the object Ob and the reflected light Lr obtained by reflecting the irradiation light Li by the object Ob. be.

The light emitting unit 2 has one or more light emitting elements as a light source, and emits irradiation light Li for the object Ob. In this example, the light emitting unit 2 emits infrared light having a wavelength in the range of, for example, 780 nm to 1000 nm as the irradiation light Li.

The control unit 3 controls the light emission operation of the irradiation light Li by the light emitting unit 2 as shown in FIG. In the case of the indirect ToF method, as the irradiation light Li, light whose intensity is modulated so that the intensity changes at a predetermined cycle is used. Specifically, in this example, the irradiation light Li emits light as pulsed light so that the light emitting period and the non-light emitting period are repeated at a predetermined cycle.
Hereinafter, the light emission cycle of such pulsed light will be referred to as "light emission cycle Cl".
Further, the period between the emission start timings of the pulsed light when the pulsed light is repeatedly emitted by the emission cycle Cl, that is, the period consisting of one emission period and one non-emission period is defined as "one modulation period Pm" or simply. Notated as "modulation period Pm".
The control unit 3 controls the light emitting operation of the light emitting unit 2 so as to emit the irradiation light Li only for a predetermined light emitting period for each modulation period Pm.
Here, in the indirect ToF method, the light emission period Cl is relatively high, for example, about several tens of MHz to several hundreds of MHz.

The sensor unit 1 of FIG. 1 receives the reflected light Lr and outputs distance measurement information by the indirect ToF method based on the phase difference between the reflected light Lr and the irradiation light Li.
As will be described later, the sensor unit 1 of this example includes a photoelectric conversion element (photodiode PD), a first transfer gate element (transfer transistor TG-A) for transferring the accumulated charge of the photoelectric conversion element, and a second transfer. It has a pixel array unit 11 in which a plurality of pixels Px including a gate element (transfer transistor TG-B) are arranged in two dimensions, and distance measurement information by an indirect ToF method is obtained for each pixel Px.
Hereinafter, the information representing the distance measurement information (distance information) for each pixel Px in this way is referred to as a “distance image”.

Here, as is known, in the indirect ToF method, the signal charges accumulated in the photoelectric conversion element in the pixel Px are alternately turned on by the first transfer gate element and the second transfer gate element, resulting in two floating diffusions (FD). It is distributed to. At this time, the cycle in which the first transfer gate element and the second transfer gate element are alternately turned on is the same as the light emission cycle Cl of the light emitting unit 2.
That is, the first transfer gate element and the second transfer gate element are turned on once for each modulation period Pm, and the above-mentioned distribution of the signal charge to the two floating diffusions is performed during the modulation period Pm. It is repeated every time.
For example, as shown in FIG. 2, the transfer transistor TG-A as the first transfer gate element is turned on during the light emission period of the irradiation light Li in the modulation period Pm (period T1). Further, the transfer transistor TG-B as the second transfer gate element is turned on during the non-emission period of the irradiation light Li in the modulation period Pm (period T2).
In addition, "on" of the transfer transistor which is a transfer gate element means a transfer state, and "off" means a non-transfer state.
However, as will be described later, in the present embodiment, the periods T1 and T2 in which the transfer transistors TG-A and TG-B are turned on do not coincide with the light emitting period and the non-light emitting period as shown in FIG.

As described above, since the light emission cycle Cl is relatively high, the signal charge accumulated in each floating diffusion by one distribution using the first and second transfer gate elements as described above is relatively small. It will be something like that. For this reason, in the indirect ToF method, the emission of the irradiation light Li is repeated thousands to tens of thousands of times for each distance measurement (that is, for obtaining a distance image for one image), and the sensor unit 1 is described in this way. While the irradiation light Li is repeatedly emitted, the signal charge is repeatedly distributed to each floating diffusion using the first and second transfer gate elements as described above.
FIG. 3 schematically shows the state of the accumulation period Pr in which the irradiation light Li is repeatedly emitted as the on-timing of the irradiation light Li and the transfer transistors TG-A and TG-B. FIG. 2 above is an enlargement of a part of the modulation period Pm in the accumulation period Pr of FIG.

As can be understood from the above description, in the sensor unit 1, the first transfer gate element and the second transfer gate element are driven for each pixel Px at a timing corresponding to the emission cycle of the irradiation light Li. Therefore, a synchronization signal Ss indicating the timing of the light emission cycle Cl is input to the sensor unit 1 from the control unit 3 and used for driving the first and second transfer gate elements in each pixel Px.

The distance image processing unit 4 inputs the distance image obtained by the sensor unit 1, performs predetermined signal processing such as compression coding, and outputs the distance image to the memory 5.
The memory 5 is, for example, a storage device such as a flash memory, an SSD (Solid State Drive), or an HDD (Hard Disk Drive), and stores a distance image processed by the distance image processing unit 4.

The frequency setting unit 6 sets the frequency as the on / off cycle of the light emission cycle Cl and the first and second transfer gate elements (transistors TG-A and TG-B).
For example, the frequency setting unit 6 sets the frequency according to user operation, control from a device using a distance measuring device (for example, an imaging device, etc.), control by an application using the distance measuring device, and the like. The control unit 3 will generate a synchronization signal Ss according to the frequency set by the frequency setting unit 6.

<2. Circuit configuration of sensor section>
FIG. 4 is a block diagram illustrating an internal circuit configuration of the sensor unit 1.
As shown in the figure, the sensor unit 1 includes a pixel array unit 11, a transfer gate drive unit 12, a vertical drive unit 13, a system control unit 14, a column processing unit 15, a horizontal drive unit 16, a signal processing unit 17, and a data storage unit 18. It has.

The pixel array unit 11 has a configuration in which a plurality of pixels Px are two-dimensionally arranged in a matrix in the row direction and the column direction. Each pixel Px has a photodiode PD, which will be described later, as a photoelectric conversion element. The details of the pixel Px will be described again with reference to FIG.
Here, the row direction means the arrangement direction of the pixels Px in the horizontal direction, and the column direction means the arrangement direction of the pixels Px in the vertical direction. In the figure, the row direction is the horizontal direction and the column direction is the vertical direction.

In the pixel array unit 11, pixel drive lines 20 are wired along the row direction for each pixel row in a matrix-like pixel array, and two gate drive lines 21 and two vertical signals are provided in each pixel row. Each of the wires 22 is wired along the row direction. For example, the pixel drive line 20 transmits a drive signal for driving when reading a signal from the pixel Px.
In FIG. 4, the pixel drive line 20 is shown as one wiring, but the wiring is not limited to one. One end of the pixel drive line 20 is connected to the output end corresponding to each line of the vertical drive unit 13.

The system control unit 14 is composed of a timing generator or the like that generates various timing signals based on the synchronization signal Ss, and the transfer gate drive unit 12 and the vertical drive unit 12 are based on the various timing signals generated by the timing generator. Drive control of 13, the column processing unit 15, the horizontal drive unit 16, and the like is performed.

Based on the control of the system control unit 14, the transfer gate drive unit 12 drives two transfer gate elements provided for each pixel Px through the gate drive lines 21 provided for each pixel row as described above.
As described above, the two transfer gate elements are assumed to be turned on alternately every modulation period Pm. Therefore, the system control unit 14 controls the on / off timing of the two transfer gate elements by the transfer gate drive unit 12 based on the synchronization signal Ss described with reference to FIG.

The vertical drive unit 13 is composed of a shift register, an address decoder, and the like, and drives all the pixels of the pixel Px of the pixel array unit 11 at the same time or in line units. That is, the vertical drive unit 13 constitutes a drive unit that controls the operation of each pixel Px of the pixel array unit 11 together with the system control unit 14 that controls the vertical drive unit 13.

The detection signal output (read) from each pixel Px in the pixel row according to the drive control by the vertical drive unit 13, specifically, the signal charge accumulated in each of the two floating diffusions provided for each pixel Px. The signal corresponding to is input to the column processing unit 15 through the corresponding vertical signal line 22. The column processing unit 15 performs predetermined signal processing on the detection signal read from each pixel Px through the vertical signal line 22, and temporarily holds the detected signal after the signal processing. Specifically, the column processing unit 15 performs noise removal processing, A / D (Analog to Digital) conversion processing, and the like as signal processing.

Here, the two detection signals (detection signals for each floating diffusion) are read out from each pixel Px for each repeated emission of the irradiation light Li for a predetermined number of times (every thousands to tens of thousands of repeated emissions described above). Will be done.
Therefore, the system control unit 14 also controls the vertical drive unit 13 based on the synchronization signal Ss with respect to the read timing of the detection signal from each pixel Px.

The horizontal drive unit 16 is composed of a shift register, an address decoder, and the like, and sequentially selects unit circuits corresponding to the pixel strings of the column processing unit 15. By the selective scanning by the horizontal drive unit 16, the detection signals that have been signal-processed for each unit circuit in the column processing unit 15 are sequentially output.

The signal processing unit 17 has at least an arithmetic processing function, and performs various signal processing such as distance calculation processing corresponding to the indirect ToF method based on the detection signal output from the column processing unit 15. A known method can be used for calculating the distance information by the indirect ToF method based on two types of detection signals (detection signals for each floating diffusion) for each pixel Px, and the description thereof is omitted here. ..

The data storage unit 18 temporarily stores data necessary for the signal processing in the signal processing unit 17.

The sensor unit 1 configured as described above outputs a distance image representing the distance to the object Ob for each pixel Px. The distance measuring device 10 having such a sensor unit 1 is mounted on a vehicle, for example, an in-vehicle system that measures the distance to an object Ob outside the vehicle, or a distance to an object such as a user's hand. Can be applied to a gesture recognition device or the like that measures a user's gesture and recognizes a user's gesture based on the measurement result.

<3. Circuit configuration of pixel array section>
FIG. 5 shows an equivalent circuit of pixels Px two-dimensionally arranged in the pixel array unit 11.
The pixel Px has one photodiode PD and one OF (overflow) gate transistor OFG as photoelectric conversion elements.
Further, the pixel Px has two transfer transistors TG, two floating diffusion FDs, a reset transistor RST, an amplification transistor AMP, and two selection transistors SEL as transfer gate elements.

Here, when distinguishing each of the transfer transistor TG, the floating diffusion FD, the reset transistor RST, the amplification transistor AMP, and the selection transistor SEL provided in the pixel Px, as shown in FIG. 5, the transfer transistor TG- It is referred to as A and TG-B, floating diffusion FD-A and FD-B, reset transistors RST-A and RST-B, amplification transistors AMP-A and RST-B, and selection transistors SEL-A and SEL-B.
The OF gate transistor OFG, the transfer transistor TG, the reset transistor RST, the amplification transistor AMP, and the selection transistor SEL are composed of, for example, an N-type MOS transistor.

The OF gate transistor OFG becomes conductive when the OF gate signal SOFG supplied to the gate is turned on.
When the OF gate transistor OFG becomes conductive, the photodiode PD is clamped to a predetermined reference potential VDD and the accumulated charge is reset.
The OF gate signal SOFG is supplied from, for example, the vertical drive unit 13.

The transfer transistor TG-A becomes conductive when the transfer drive signal STG-A supplied to the gate is turned on, and transfers the signal charge stored in the photodiode PD to the floating diffusion FD-A.
The transfer transistor TG-B becomes conductive when the transfer drive signal STG-B supplied to the gate is turned on, and transfers the electric charge stored in the photodiode PD to the floating diffusion FD-B.
The transfer drive signals STG-A and STG-B are each supplied from the transfer gate drive unit 12 through the gate drive lines 21-A and 21-B provided as one of the gate drive lines 21 shown in FIG. ..

The floating diffusion FD-A and FD-B are charge holding units that temporarily hold the charge transferred from the photodiode PD.

The reset transistor RST-A becomes conductive when the reset signal SRST supplied to the gate is turned on, and resets the potential of the floating diffusion FD-A to the reference potential VDD.
Similarly, the reset transistor RST-B becomes conductive when the reset signal SRST supplied to the gate is turned on, and resets the potential of the floating diffusion FD-B to the reference potential VDD.
The reset signal SRST is supplied from, for example, the vertical drive unit 13.

In the amplification transistor AMP-A, the source is connected to the vertical signal line 22-A via the selection transistor SEL-A, and the drain is connected to the reference potential VDD (constant current source) to form a source follower circuit.
In the amplification transistor AMP-B, the source is connected to the vertical signal line 22-B via the selection transistor SEL-B, and the drain is connected to the reference potential VDD (constant current source) to form a source follower circuit.
Here, the vertical signal lines 22-A and 22-B are provided as one of the vertical signal lines 22 shown in FIG. 4, respectively.

The selection transistor SEL-A is connected between the source of the amplification transistor AMP-A and the vertical signal line 22-A, and becomes conductive when the selection signal SSEL supplied to the gate is turned on, and the floating diffusion FD- The electric charge held in A is output to the vertical signal line 22-A via the amplification transistor AMP-A.
The selection transistor SEL-B is connected between the source of the amplification transistor AMP-B and the vertical signal line 22-B, and becomes conductive when the selection signal SSEL supplied to the gate is turned on, and the floating diffusion FD- The charge held in B is output to the vertical signal line 22-B via the amplification transistor AMP-A.
The selection signal SSEL is supplied from the vertical drive unit 13 via the pixel drive line 20.

The operation of the pixel Px will be briefly described.
First, before starting light reception, a reset operation for resetting the charge of the pixel Px is performed on all pixels (reset period in FIG. 3). That is, for example, the OF gate transistor OFG, each reset transistor RST, and each transfer transistor TG are turned on (conducting state), and the accumulated charges of the photodiode PD and each floating diffusion FD are reset.

After resetting the accumulated charge, the light receiving operation for distance measurement is started for all pixels. The light receiving operation referred to here means a light receiving operation performed for one distance measurement. That is, during the light receiving operation, the operation of alternately turning on the transfer transistors TG-A and TG-B is repeated a predetermined number of times (in this example, about several thousand to tens of thousands of times). The period of the charge accumulation operation by receiving light received for such one distance measurement is described as "accumulation period Pr" as shown in FIG.

In the storage period Pr, within one modulation period Pm of the light emitting unit 2, for example, a period T1 in which the transfer transistor TG-A is on (that is, a period in which the transfer transistor TG-B is off) is continued for the light emission period of the irradiation light Li. After that, the remaining period, that is, the non-emission period of the irradiation light Li is set to the period T2 in which the transfer transistor TG-B is on (that is, the period in which the transfer transistor TG-A is off). That is, in the accumulation period Pr, the operation of distributing the electric charge of the photodiode PD to the floating diffusion FD-A and the floating diffusion FD-B within one modulation period Pm is repeated a predetermined number of times.

Then, when the accumulation period Pr ends, each pixel Px of the pixel array unit 11 is selected in line order. At the selected pixel Px, the selection transistors SEL-A and SEL-B are turned on. As a result, the electric charge accumulated in the floating diffusion FD-A is output to the column processing unit 15 via the vertical signal line 22-A. Further, the electric charge accumulated in the floating diffusion FD-B is output to the column processing unit 15 via the vertical signal line 22-B (reading period in FIG. 3).

With the above, one light receiving operation is completed, and the next light receiving operation starting from the reset operation is executed.

Here, the reflected light received by the pixel Px is delayed according to the distance from the timing when the light emitting unit 2 emits the irradiation light Li to the object Ob. Since the distribution ratio of the electric charge accumulated in the two floating diffusion FD-A and FD-B changes depending on the delay time according to the distance to the object Ob, these two floating diffusion FD-1 and FD-B are used. The distance to the object Ob can be obtained from the distribution ratio of the accumulated charges.

<4. Sensor unit structure>
Next, the structure of the sensor unit 1 will be described.
6 and 7 show a schematic structure of a pixel Px, specifically, a photodiode PD formed in a region of one pixel Px on a semiconductor substrate, an OF gate transistor OFG, transfer transistors TG-A, TG-B, and floating diffusion. It is a figure exemplifying the positional relationship of FD-A and FD-B, FIG. 6 is a top view, and FIG. 7 is a cross-sectional view cut at the position of XX'shown in FIG. Note that in FIGS. 6 and 7, the illustration of pixel transistors such as the reset transistor RST and the amplification transistor AMP is omitted.

The photodiode PD is formed inside the semiconductor substrate, has a substantially rectangular shape when viewed from above, and is formed substantially at the center in the plane of the pixel Px. Here, the in-plane means the in-plane parallel to the horizontal direction (row direction) and the vertical direction (column direction) described above. The horizontal direction corresponds to the horizontal direction of the paper in FIGS. 6 and 7. The vertical direction corresponds to the vertical direction of the paper surface of FIG.

The transfer transistors TG-A and TG-B are formed on a semiconductor substrate and have a substantially rectangular shape when viewed from above. The positions of the transfer transistors TG-A and TG-B in the plane are set to be near the corresponding end of both ends of the photodiode PD in the horizontal or vertical direction. Specifically, in this example, the transfer transistors TG-A and TG-B are positioned in the plane at one of the corresponding ends of the photodiode PD in the horizontal direction (horizontal direction on the paper surface). On the other hand, it is said that a part of it overlaps. The positions of the transfer transistors TG-A and TG-B in the vertical direction are substantially the same.

The floating diffusion FD-A and FD-B are formed inside the semiconductor substrate and have a substantially rectangular shape when viewed from above. The in-plane position of the floating diffusion FD-A is partly relative to the outer edge of the transfer transistor TG-A, that is, the edge opposite to the edge that overlaps the photodiode PD as described above. Is the overlapping position. Further, the position of the floating diffusion FD-B in the plane partially overlaps with the outer edge portion of the transfer transistor TG-B (the end edge portion opposite to the end edge portion overlapping with the photodiode PD). It is said to be a position. The positions of the floating diffusion FD-A and FD-B in the vertical direction are substantially the same.

The OF gate transistor OFG is formed on a semiconductor substrate and has a substantially rectangular shape when viewed from above, and the position in the plane is the transfer transistor TG-A among the four end portions of the photodiode PD. , TG-B is set to a position where a part of the TG-B overlaps with the non-overlapping edge portion. That is, in this example, the position is set so that a part of the photodiode PD overlaps one end of both ends in the vertical direction.

<5. First Embodiment>
Hereinafter, the first embodiment will be described, but first, the process leading to the present technology will be described.
The operation timings are shown in FIGS. 2 and 3 above, and the description will be given focusing on one modulation period Pm in the accumulation period Pr.
FIG. 2 shows a period T1 in which the transfer transistor TG-A is on (transfer state) and a period T2 in which the transfer transistor TG-B is on.

In the case of FIG. 2, the period T1 coincides with the light emitting period of the irradiation light Li, and the period T2 coincides with the non-light emitting period. That is, the transfer transistor TG-A is turned on in synchronization with the light emitting period, and the transfer transistor TG-B is turned on during the non-light emitting period.
The potential energies of the electrons of T1 and T2 during this period are schematically shown in FIG. The high and low potential energies are shown in the vertical direction, and each part of the floating diffusion FD-A, the transfer transistor TG-A, the photodiode PD, the transfer transistor TG-B, and the floating diffusion FD-B is shown in the horizontal direction.
During the period T1, the transfer transistor TG-A is turned on, and the photoelectrons generated in the photodiode PD are transferred to the floating diffusion FD-A.
During the period T2, the transfer transistor TG-B is turned on, and the photoelectrons generated in the photodiode PD are transferred to the floating diffusion FD-B.
The distance to the object can be calculated from the ratio of the signal amounts distributed to the floating diffusion FD-A and FD-B in this way.

Here, the ON period of the transfer transistor TG-A in FIG. 2 is a period of 50% of the modulation period Pm, and the ON period of the transfer transistor TG-B is also a period of 50% of the modulation period Pm.
Therefore, the transfer drive signals STG-A and STG-B output by the transfer gate drive unit 12 may ideally have a pulse as shown in FIG. 2 as the on-period of the transfer transistors TG-A and TG-B. .. That is, each of the transfer drive signals STG-A and STG-B is a pulse having a duty of 50% with respect to the modulation period Pm.

This is the drive method for the transfer transistors TG-A and TG-B that are usually assumed, but the actual pulse waveforms of the transfer drive signals STG-A and STG-B are the capacitances of the gate drive lines 21-A and 21-B. And resistance slows the rise and fall of the waveform, for example, as shown in FIG.
When the waveform becomes dull, the timing at which the transfer transistors TG-A and TG-B are turned on (that is, the gate is opened) and the timing at which the transfer transistors TG-A and TG-B are turned off (that is, the gate is closed) are delayed.
Further, the threshold voltages Vth1 and Vth2 of the transfer transistors TG-A and TG-B fluctuate due to manufacturing variations, but this also affects the timing at which the transfer transistors TG-A and TG-B are turned on.

Due to the timing fluctuation caused by these causes, there may be a period in which the transfer transistors TG-A and TG-B are opened at the same time. For example, the shaded period T3 in FIG.
The period T3 in which the transfer transistors TG-A and TG-B are open at the same time may also occur due to a pulse timing shift between the transfer drive signals STG-A and STG-B.

FIG. 10 shows changes in potential energy during the period T2, the period T3, and the period T1 shown in FIG.
The periods T1 and T2 are the same as those in FIG. 8 described above, but when the transfer transistors TG-A and TG-B are open at the same time as in the period T3, the electrons existing in the photodiode PD are floating diffusion FD-A. And FD-B. Therefore, the transfer efficiency (Cmod) is lowered.
When the transfer efficiency (Cmod) is lowered, the S / N of the distance measuring signal is lowered and the distance measuring error is increased.

When normal driving is performed in this way, the transfer transistors TG-A and TG-B are simultaneously driven due to the blunting of the transfer drive signals STG-A and STG-B and the timing deviation between the transfer transistors TG-A and TG-B. There is a period when it is turned on, and the distance measurement error may increase.
Therefore, in the embodiment, both the transfer transistors TG-A and TG-B are turned off during the transfer period to the floating diffusion FD-A (period T1) and the transfer period to the floating diffusion FD-B (period T2). It is configured to provide a period of.

FIG. 11 shows the transfer drive signals STG-A and STG-B as the first embodiment. Here, the waveform is shown in a dull state due to the above-mentioned reason, but the transfer drive signals STG-A and STG-B output by the transfer gate drive unit 12 are both rectangular with the on-control pulse duty set to 40%. Suppose it is a pulse.
The threshold values Vth1 and Vth2 are the threshold voltages of the transfer transistors TG-A and TG-B.
It is assumed that the transfer gate drive unit 12 outputs the transfer drive signals STG-A and STG-B with the pulse duty set to 40%, respectively, and as a result, the waveform becomes dull as shown in the figure.
In this case, the transfer transistor TG-A is turned on during the period T1 in which the voltage of the transfer drive signal STG-A exceeds the threshold value Vth1 of the transfer transistor TG-A.
Further, the transfer transistor TG-A is turned on during the period T2 in which the voltage of the transfer drive signal STG-B exceeds the threshold value Vth2 of the transfer transistor TG-B.

In this case, in the process of switching from the transfer transistor TG-A on to the transfer transistor TG-B on, and in the process of switching the transfer transistor TG-B from on to the transfer transistor TG-A on, diagonal lines are shown as shown in the figure. The attached period (non-transfer period T4) occurs. That is, it is a period in which both the transfer transistors TG-A and TG-B are off.
FIG. 12 shows changes in potential energy during the period T2, the non-transfer period T4, and the period T1 shown in FIG.
During this non-transfer period T4, the electrons of the photodiode PD are not transferred to either the floating diffusion FD-A or FD-B and are accumulated in the photodiode PD.

That is, in the first embodiment, the transfer gate drive unit 12 outputs the transfer drive signals STG-A and STG-B with the pulse duty set to less than 50% so that the non-transfer period T4 is generated, thereby causing the non-transfer period T4. It is avoided that the electric charge of the photodiode PD is transferred to the floating diffusion FD-A and FD-B at the same time. As a result, the transfer efficiency (Cmod) does not deteriorate.

The duty ratios of the transfer drive signals STG-A and STG-B are controlled by the system control unit 14 of FIG. 4 and reflected in the gate drive signal generated by the transfer gate drive unit 12.

By the way, it is said that the pulse duty of the transfer drive signals STG-A and STG-B is less than 50% to cause the non-transfer period T4, but the actually appropriate pulse duty is the sensor unit 1 (distance measuring device). 10) It is appropriate to calibrate each time to determine. This is because there are individual manufacturing variations.
That is, it is possible to search for the duty ratio that maximizes the transfer efficiency (Cmod) while changing the pulse duty, and determine the pulse duty according to the result.
Thereby, an appropriate pulse duty for forming the non-transfer period T4 can be set.

This calibration may be performed in the manufacturing process of the sensor unit 1 or the distance measuring device 10, or may be performed in a camera, a smartphone, or the like equipped with the distance measuring device 10. Calibration performed on the camera or smartphone may be performed in the manufacturing process of the camera or smartphone, or may be performed each time the user actually uses the camera or smartphone.

Further, the pulse dutys of the transfer drive signals STG-A and STG-B can be changed according to the transfer gate drive frequency (fmod).
The transfer gate drive frequency fmod is a frequency that determines the on / off period of the transfer transistors TG-A and TG-B, that is, corresponds to a frequency that determines the period of the modulation period Pm. Furthermore, it corresponds to the frequency of the pulse emission of the irradiation light Li as shown in FIG. 2, and is set by the control unit 3 based on the input by the frequency setting unit 6 of FIG.

For example, when the transfer gate drive frequency fmod is 10 MHz, the duty ratio is 49%, and when it is 100 MHz, it is 40%. Of course, this is just an example, and the duty ratio may be set according to the actual situation in the range of less than 50%.
As a result, at 10 MHz, which has a small effect on the transfer efficiency (Cmod) of the waveform bluntness, overflow of the signal electrons from the PD is avoided, and at 100 MHz, where the influence on the transfer efficiency (Cmod) of the waveform bluntness increases, the above-mentioned effects and effects are described. Therefore, it is possible to avoid a decrease in Cmod.

In some cases, when the transfer gate drive frequency fmod is low, the pulse duty of the transfer drive signals STG-A and STG-B is left at 50%, and when the transfer gate drive frequency fmod is increased, the pulse duty is increased. It may be changed to less than 50%.

It is also possible to calibrate each transfer gate drive frequency fmod and set the pulse duty according to the frequency.
For example, at the time of calibration, the transfer efficiency (Cmod) is measured while changing the duty ratio at various transfer gate drive frequencies fmod, and the duty ratio at which the transfer efficiency (Cmod) is optimized is determined for each transfer gate drive frequency fmod. be able to.
Similar to the above, this calibration may be performed in the manufacturing process of the sensor unit 1 or the distance measuring device 10, or may be performed in the manufacturing process or each actual use in a camera or smartphone equipped with the distance measuring device 10. good.

Further, the transfer gate drive unit 12 matches the end timing of the light emitting period of the irradiation light Li with the end timing of the transfer state (on period) of the transfer transistor TG-A, and further coincides with the end timing of the non-light emitting period of the irradiation light Li. It is preferable to drive the transfer transistors TG-A and TG-B so that the end timings of the transfer states (on period) of the transfer transistors TG-B are matched.

FIG. 13 shows an on period (period T1) of the transfer transistor TG-A and an on period (period T2) of the transfer transistor TG-B with respect to the light emission period and the non-light emission period of the irradiation light Li in the modulation period Pm.
In this figure, the period T1 ends at the time point tD1, which is the end timing of the light emission period. Further, the period T2 ends at the time point tD2, which is the end timing of the non-light emitting period.
That is, the non-transfer period T4 is provided on the head side of the light emitting period and the head side of the non-light emitting period.

In this way, the charge accumulated in the photodiode PD due to the light reception within the period corresponding to the light emission period is transferred to the floating diffusion FD-A side without any residue, and the light is received within the period corresponding to the non-light emission period. The electric charge accumulated in the photodiode PD can be transferred to the floating diffusion FD-B side. Therefore, the light that has reached the sensor unit 1 within the light emission period and the light that has reached the non-light emission period can be appropriately distributed to the floating diffusion FD-A and FD-B, and the transfer efficiency (Cmod) is improved and the measurement is performed accordingly. It is appropriate in terms of improving distance accuracy.

<6. Second Embodiment>
In the second embodiment, the duty ratio is 50% or more by increasing the threshold voltages Vth1 and Vth2 of the transfer transistors TG-A and TG-B by utilizing the bluntness of the transfer drive signals STG-A and STG-B. The transfer drive signals STG-A and STG-B of the above also provide a non-transfer period T4 in which both the transfer transistors TG-A and TG-B are off.

That is, in this case, it is assumed that the transfer drive signals STG-A and STG-B are pulse signals having a duty ratio of 50% as described with reference to FIG.
By increasing the threshold voltages Vth1 and Vth2 as shown in FIG. 14, the shaded non-transfer period T4 is generated. FIG. 14 shows an example of effective duty = 30%.

That is, when the threshold values Vth1 and Vth2 are increased, the waveforms of the transfer drive signals STG-A and STG-B are blunted, so that the timing at which the transfer transistors TG-A and TG-B are turned on is significantly delayed. The timing of the transfer transistors TG-A and TG-B is slightly delayed when they are turned off, but the non-transfer period T4 occurs due to the difference between the delay when the transfer transistors TG-A and TG-B are turned on and the delay amount when the transfer transistors TG-B are turned off.
As a result, it is possible to prevent deterioration of the transfer efficiency (Cmod) and improve the distance measurement accuracy as in the first embodiment.

The threshold voltages Vth1 and Vth2 of the transfer transistors TG-A and TG-B are used in the manufacturing process of the sensor unit 1 to appropriately adjust the impurity concentration in the Si substrate immediately below the transfer transistor, the gate oxide film thickness, and the like by a known method. It can be controlled by.

<7. Summary and modification>
The following effects can be obtained in the above embodiments.
The sensor unit 1 (sensor device) of the first and second embodiments transfers the electric charge obtained by performing the photoelectric conversion with the photodiode PD (photoelectric conversion element) and the photodiode PD, and the floating diffusion FD-. Floating diffusion FD-B (second) by transferring the charge obtained by performing photoelectric conversion with the transfer transistor TG-A (first transfer gate element) to be stored in A (first charge storage unit) and the photodiode PD. A transfer transistor TG-B (second transfer gate element) to be stored in the charge storage unit) and a transfer gate drive unit 12 are provided.
In the transfer gate drive unit 12, the irradiation light Li received by the photodiode PD has a storage period Pr in which the light emitting period and the non-light emitting period are repeated as one modulation period Pm, and the transfer transistors TG-A, TG- The transfer transistors TG-A and TG-B are driven so that a non-transfer period T4 in which B does not transfer charges together occurs.
As a result, due to factors such as variations in the threshold voltages Vth1 and Vth2 of the transfer transistors TG-1 and TG-2 and blunting of the waveforms of the transfer drive signals STG-A and STG-B, the transfer transistors TG-1 and TG-2 It is possible to eliminate the period in which both are turned on and the transfer is performed to both the floating diffusion FD-A and FD-B.
Therefore, the transfer efficiency (Cmod) is improved, and the distance measurement accuracy can be improved.
Further, the gain mismatch on the floating diffusion FD-A side and the FD-B side due to the threshold voltage difference between the transfer transistors TG-1 and TG-2 is reduced, and the ranging error (fixed pattern noise) can be reduced.

In the first and second embodiments, the transfer gate drive unit 12 has a non-transfer period T4, a period T1 in which the transfer transistor TG-A is in the transfer state, a non-transfer period T4, and a transfer transistor TG in the storage period Pr. The transfer transistors TG-A and TG-B are driven so that a cycle of the period T2 in which −B is in the transfer state occurs.
As a result, both the transfer transistor TG-2 is turned on while the transfer transistor TG-1 is on and the transfer transistor TG-1 is turned on while the transfer transistor TG-2 is on. It will be resolved.
Therefore, the effect of improving the distance measurement accuracy by improving the transfer efficiency described above can be appropriately exerted.
At least when the transfer transistor TG-1 is turned off, the transfer transistor TG-2 may be turned on through the non-transfer period, and in this case as well, the Cmod improvement effect can be obtained.

In the first embodiment, the transfer period of the transfer transistor TG-A is set by setting the pulse duty of the transfer drive signal STG-A (first transfer drive signal) and the transfer drive signal STG-B (second transfer drive signal). The non-transfer period T4 is caused by shortening the light emission period and shortening the transfer period of the transfer transistor TG-B to the non-light emission period.
By shortening the on-period of the transfer transistors TG-1 and TG-2 by setting the pulse duty of the transfer drive signals STG-A and STG-B, the non-transfer period T4 can be generated. This makes it possible to easily realize the above-mentioned improvement in transfer efficiency (Cmod).

In the first embodiment, when the light emitting period and the non-light emitting period have the same period length, the pulse duty of the transfer drive signal STG-A that controls the transfer transistor TG-A to the transfer state within the light emitting period is set to 50%. The non-transfer period T4 is set to be less than 50% by setting the pulse duty of the transfer drive signal STG-B that controls the transfer transistor TG-B to the transfer state within the non-emission period to less than 50%.
When the light emitting period and the non-light emitting period have the same period length, if the pulse duty of the transfer drive signals STG-A and STG-B is less than 50%, the on periods of the transfer transistors TG-1 and TG-2 emit light, respectively. It can be made shorter than the period or the non-light emitting period so that the non-transfer period T4 occurs. As a result, the above-mentioned improvement in transfer efficiency can be easily realized.

In the first embodiment, it has been described that the pulse duty of the transfer drive signal STG-A and the pulse duty of the transfer drive signal STG-B are variably set.
For example, calibration is performed to obtain a pulse duty so as to maximize the transfer efficiency, and the pulse duty is set to that pulse duty.
This makes it possible to set the pulse duty so as to maximize the transfer efficiency, for example. Therefore, the sensor unit 1 can execute an appropriate gate operation according to its own transistor characteristics and the like.

In the first embodiment, it has been described that the pulse duty of the transfer drive signal STG-A and the pulse duty of the transfer drive signal STG-B are variably set according to the transfer gate drive frequency.
As a result, in the case of a relatively low frequency in which the adverse effect of the waveform blunting on the transfer efficiency is small, overflow of the signal electron from the photodiode PD is avoided, and the influence of the waveform blunting transfer efficiency is increased. In that case, it is possible to avoid a decrease in transfer efficiency due to the above-mentioned effect.

In the first embodiment, the end timing of the light emitting period and the end timing of the transfer state of the transfer transistor TG-A are matched, and the end timing of the non-light emission period and the end timing of the transfer state of the transfer transistor TG-B are matched. As described above, it is described that the transfer transistors TG-A and TG-B are driven.
As a result, the electric charge of the light reaching the sensor unit 1 during the light emitting period and the electric charge of the light reaching the sensor unit 1 during the non-light emitting period are transferred to the floating diffusion FD-A and FD-B without being wasted. Will be done. Therefore, the distance measurement accuracy can be improved.

In the second embodiment, the transfer transistors TG-A and TG-B are driven by the transfer gate drive unit 12 by setting the threshold voltage Vth1 of the transfer transistor TG-A and the threshold voltage Vth2 of the transfer transistor TG-B. An example has been described in which the non-transfer period T4 occurs at that time.
This also eliminates the period in which both the transfer transistors TG-1 and TG-2 are turned on and the transfer is performed to both the floating diffusion FD-A and FD-B, improving the transfer efficiency. It is possible to improve the distance measurement accuracy by.

It should be noted that the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

The present technology can also adopt the following configurations.
(1)
Photoelectric conversion element and
A first transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the first charge storage unit.
A second transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the second charge storage unit.
During the accumulation period in which the irradiation of light received by the photoelectric conversion element repeats the light emitting period and the non-light emitting period as one modulation period, both the first transfer gate element and the second transfer gate element are charged within the one modulation period. A sensor device including the first transfer gate element and a transfer gate drive unit for driving the second transfer gate element so that a non-transfer period in which the transfer is not performed occurs.
(2)
During the accumulation period
The first transfer so that a cycle of the non-transfer period, the period in which the first transfer gate element is in the transfer state, the non-transfer period, and the period in which the second transfer gate element is in the transfer state occurs. The sensor device according to (1) above, wherein the gate element and the second transfer gate element are driven.
(3)
The transfer gate drive unit controls the first transfer drive signal that controls the first transfer gate element to the transfer state during the light emission period, and the second transfer gate element that controls the second transfer gate element to the transfer state during the non-light emission period. 2 While outputting a transfer drive signal,
Due to the pulse duty of the first transfer drive signal and the second transfer drive signal, the transfer period of the first transfer gate element is shorter than the light emission period, and the transfer period of the second transfer gate element is the non-light emission period. The sensor device according to (1) or (2) above, wherein the non-transfer period occurs by making it shorter than.
(4)
When the light emitting period and the non-light emitting period have the same period length,
The pulse duty of the first transfer drive signal that controls the first transfer gate element to the transfer state within the light emission period is set to less than 50%.
By setting the pulse duty of the second transfer drive signal that controls the second transfer gate element to the transfer state within the non-emission period to less than 50%,
The sensor device according to any one of (1) to (3) above, which causes the non-transfer period to occur.
(5)
The sensor device according to (4) above, wherein the pulse duty of the first transfer drive signal and the pulse duty of the second transfer drive signal are variably set.
(6)
The sensor device according to (4) or (5) above, wherein the pulse duty of the first transfer drive signal and the pulse duty of the second transfer drive signal are variably set according to the transfer gate drive frequency.
(7)
The end timing of the light emitting period and the end timing of the transfer state of the first transfer gate element are matched.
The end timing of the non-light emitting period and the end timing of the transfer state of the second transfer gate element are matched.
The sensor device according to any one of (1) to (5) above, which drives the first transfer gate element and the second transfer gate element.
(8)
When the first transfer gate element and the second transfer gate element are driven by the transfer gate driving unit by setting the threshold voltage of the first transfer gate element and the threshold voltage of the second transfer gate element, the transfer gate element is driven. The sensor device according to (1) above, wherein a non-transfer period occurs.
(9)
A light emitting unit that irradiates light so that the light emitting period and the non-light emitting period are repeated as one modulation period,
A photoelectric conversion element that receives the reflected light of the light from the light emitting unit by the distance measuring object, and
A first transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the first charge storage unit.
A second transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the second charge storage unit.
During the accumulation period in which the light emitting period and the non-light emitting period are repeated as one modulation period, there is a non-transfer period in which both the first transfer gate element and the second transfer gate element do not transfer charges within the one modulation period. A distance measuring device including the first transfer gate element and the transfer gate driving unit for driving the second transfer gate element so as to occur.
(10)
Photoelectric conversion element and
A first transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the first charge storage unit.
A second transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the second charge storage unit.
As a sensing method of the sensor device equipped with
During the accumulation period in which the irradiation of light received by the photoelectric conversion element repeats the light emitting period and the non-light emitting period as one modulation period, both the first transfer gate element and the second transfer gate element are charged within the one modulation period. A sensing method for driving the first transfer gate element and the second transfer gate element so that a non-transfer period in which the transfer is not performed occurs.

1 Sensor unit 2 Light emitting unit 3 Control unit 4 Distance image processing unit 5 Memory 6 Frequency setting unit 10 Distance measuring device 11 Pixel array unit 12 Transfer gate drive unit 13 Vertical drive unit 14 System control unit 15 Column processing unit 16 Horizontal drive unit 17 Signal processing unit 18 Data storage unit 20 pixel drive line 21,21-A, 21-B Gate drive line 22, 22-A, 22-B Vertical signal line TG, TG-A, TG-B Transfer transistor Px pixel FD, FD-A, FD-B Floating diffusion PD photodiode STG-A, STG-B Transfer drive signal Pm Modulation period Pr Accumulation period Cl Emission period Li Irradiation light Lr Reflected light

Claims (10)

Photoelectric conversion element and
A first transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the first charge storage unit.
A second transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the second charge storage unit.
During the accumulation period in which the irradiation of light received by the photoelectric conversion element repeats the light emitting period and the non-light emitting period as one modulation period, both the first transfer gate element and the second transfer gate element are charged within the one modulation period. A sensor device including the first transfer gate element and a transfer gate drive unit for driving the second transfer gate element so that a non-transfer period in which the transfer is not performed occurs. During the accumulation period
The first transfer so that a cycle of the non-transfer period, the period in which the first transfer gate element is in the transfer state, the non-transfer period, and the period in which the second transfer gate element is in the transfer state occurs. The sensor device according to claim 1, wherein the gate element and the second transfer gate element are driven. The transfer gate drive unit controls the first transfer drive signal that controls the first transfer gate element to the transfer state during the light emission period, and the second transfer gate element that controls the second transfer gate element to the transfer state during the non-light emission period. 2 While outputting a transfer drive signal,
Due to the pulse duty of the first transfer drive signal and the second transfer drive signal, the transfer period of the first transfer gate element is shorter than the light emission period, and the transfer period of the second transfer gate element is the non-light emission period. The sensor device according to claim 1, wherein the non-transfer period occurs by making the sensor device shorter than the above. When the light emitting period and the non-light emitting period have the same period length,
The pulse duty of the first transfer drive signal that controls the first transfer gate element to the transfer state within the light emission period is set to less than 50%.
By setting the pulse duty of the second transfer drive signal that controls the second transfer gate element to the transfer state within the non-emission period to less than 50%,
The sensor device according to claim 1, wherein the non-transfer period occurs. The sensor device according to claim 4, wherein the pulse duty of the first transfer drive signal and the pulse duty of the second transfer drive signal are variably set. The sensor device according to claim 4, wherein the pulse duty of the first transfer drive signal and the pulse duty of the second transfer drive signal are variably set according to the transfer gate drive frequency. The end timing of the light emitting period and the end timing of the transfer state of the first transfer gate element are matched.
The end timing of the non-light emitting period and the end timing of the transfer state of the second transfer gate element are matched.
The sensor device according to claim 1, wherein the first transfer gate element and the second transfer gate element are driven. When the first transfer gate element and the second transfer gate element are driven by the transfer gate driving unit by setting the threshold voltage of the first transfer gate element and the threshold voltage of the second transfer gate element, the transfer gate element is driven. The sensor device according to claim 1, wherein a non-transfer period occurs. A light emitting unit that irradiates light so that the light emitting period and the non-light emitting period are repeated as one modulation period,
A photoelectric conversion element that receives the reflected light of the light from the light emitting unit by the distance measuring object, and
A first transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the first charge storage unit.
A second transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the second charge storage unit.
During the accumulation period in which the light emitting period and the non-light emitting period are repeated as one modulation period, there is a non-transfer period in which both the first transfer gate element and the second transfer gate element do not transfer charges within the one modulation period. A distance measuring device including the first transfer gate element and the transfer gate driving unit for driving the second transfer gate element so as to occur. Photoelectric conversion element and
A first transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the first charge storage unit.
A second transfer gate element that transfers the electric charge obtained by performing photoelectric conversion with the photoelectric conversion element and stores it in the second charge storage unit.
As a sensing method of the sensor device equipped with
During the accumulation period in which the irradiation of light received by the photoelectric conversion element repeats the light emitting period and the non-light emitting period as one modulation period, both the first transfer gate element and the second transfer gate element are charged within the one modulation period. A sensing method for driving the first transfer gate element and the second transfer gate element so that a non-transfer period in which the transfer is not performed occurs.

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