TDC device and measuring apparatus

Abstract

To provide a technique for avoiding an influence of a power supply variation in a TDC device having a structure that a common clock signal is supplied to a plurality of TDC circuits.SOLUTION: A TDC device comprises: a plurality of TDC circuits; a clock supply part that supplies a common clock signal to the plurality of TDC circuits; and a start control part that outputs a count start signal that instructs a start timing of a count operation to the plurality of TDC circuits. The start control part outputs the count start signal after a predetermined delay time is passed from a timing when the common clock signal is supplied to the plurality of TDC circuits from the clock supply part.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a TDC device and a distance measuring device. [Background technology]

[0002] There is known a photoelectric conversion device that can detect weak light at the single photon level by utilizing avalanche multiplication. Patent Document 1 discloses a photoelectric conversion device in which a sensor chip on which a plurality of pixels are arranged and a circuit chip on which a circuit for performing signal processing is formed are both electrically connected in a stacked structure. It is also disclosed that avalanche photodiodes (APDs), in which electric charges undergo avalanche multiplication, are used for the pixels in the sensor chip of this photoelectric conversion device.

[0003] As an application example of a photoelectric conversion device, a technology is known that measures the distance to an object from the time difference between the timing of emitting light and the timing of detecting reflected light from the object. This type of distance measuring device is called an optical TOF (Time of Flight) sensor. A TOF sensor that can obtain three-dimensional information (depth map) of a subject using a pixel array in which pixels having photoelectric conversion elements are arranged two-dimensionally is also called a TOF camera or a 3D measurement device. For example, Patent Document 2 discloses a configuration in which a TOF sensor counts the elapsed time until detecting reflected light using a time-to-digital converter (hereinafter, referred to as TDC). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2017 / 0186798 [Patent Document 2] JP 2022-124396 A Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors have been studying a configuration in which a common clock signal is simultaneously supplied to the TDC circuits for multiple columns corresponding to each column of the pixel array, and all the TDC circuits are driven simultaneously. This configuration is expected to have the effects of speeding up distance measurement processing and simplifying the circuit structure.

[0006] However, in the course of experiments, the inventors found that in the above configuration, when a common clock signal is supplied to all the circuits at once, the current flowing through the circuit changes suddenly, which can cause the power supply voltage of the TDC circuit to fluctuate. If such a power supply fluctuation occurs during TDC operation, it may cause a malfunction of the TD conversion, leading to failure of distance measurement or a decrease in accuracy.

[0007] The power supply fluctuations become larger the more TDC circuits are driven simultaneously, i.e., the more pixels (columns) in the pixel array. Also, the higher the time resolution of the TDC circuit, the more susceptible it is to the effects of power supply fluctuations, increasing the risk of malfunction. Therefore, the higher the resolution and distance measurement resolution of TOF sensors, the more difficult it becomes to ignore the above problems.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a technique for avoiding the effects of power supply fluctuations in a TDC device configured to supply a common clock signal to multiple TDC circuits. [Means for solving the problem]

[0009] The present disclosure provides a clock supply unit that supplies a common clock signal to a plurality of TDC (Time to Digital Converter) circuits, a start control unit that outputs a count start signal that instructs the plurality of TDC circuits to start their count operations, and the start control unit outputs the count start signal after a predetermined delay time has elapsed from the timing at which the common clock signal is supplied from the clock supply unit to the plurality of TDC circuits. Effect of the Invention

[0010] In a TDC device configured to supply a common clock signal to multiple TDC circuits, it is possible to avoid the effects of power supply fluctuations. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a distance measuring device. [Diagram 2] FIG. 1 illustrates a configuration of a photoelectric conversion device. [Diagram 3] FIG. 4 is a diagram showing an example of the arrangement of a sensor substrate. [Figure 4] FIG. 4 is a diagram showing an example of the layout of a circuit board. [Diagram 5] FIG. 2 is a block diagram including an equivalent circuit of a photoelectric conversion element. [Figure 6] FIG. 4 is a diagram showing the relationship between the operation of an APD and an output signal. [Figure 7] FIG. 1 is a diagram showing the configuration of a TDC device according to a first embodiment. [Figure 8] FIG. 2 is a diagram showing the configuration of a start control unit according to the first embodiment. [Figure 9] 4 is a timing chart of the start control in the first embodiment. [Figure 10] 5 is a timing chart of start control in a comparative example. [Figure 11] FIG. 13 is a diagram showing the configuration of a TDC device according to a second embodiment. [Figure 12] FIG. 13 is a diagram showing the configuration of a start control unit according to a second embodiment. [Figure 13] FIG. 13 is a diagram showing the configuration of a delay circuit according to a second embodiment. [Figure 14] 10 is a timing chart of a start control according to a second embodiment. [Figure 15] FIG. 11 is a block diagram including an equivalent circuit of a photoelectric conversion element according to a third embodiment. [Figure 16] FIG. 13 is a diagram illustrating an in-vehicle camera system and a moving object according to a fourth embodiment. [Figure 17] FIG. 13 is a diagram illustrating an electronic device according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The following embodiments are intended to embody the technical ideas of the present invention, and are not intended to limit the present invention. The sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the description. In the following description, the same components may be designated by the same reference numerals, and the description may be omitted.

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "upper", "lower", "right", "left" and other terms including these terms) will be used as necessary. The use of these terms is for the purpose of facilitating understanding of the embodiment with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms.

[0014] In this specification, the plan view refers to a view from a direction perpendicular to the light incident surface of the semiconductor layer. Also, the cross-sectional view refers to a surface in a direction perpendicular to the light incident surface of the semiconductor layer. Note that, when the light incident surface of the semiconductor layer is a rough surface when viewed microscopically, the plan view is defined based on the light incident surface of the semiconductor layer when viewed macroscopically.

[0015] The semiconductor layer has a first surface and a second surface, which is the surface opposite to the first surface and into which light is incident. In this specification, the depth direction is the direction from the first surface toward the second surface of the semiconductor layer on which the avalanche photodiode (APD) is disposed. Hereinafter, the "first surface" may be referred to as the "front surface" and the "second surface" may be referred to as the "rear surface." A certain point or a certain region in the semiconductor layer "Depth" in refers to the distance of that point or region from the first surface (surface). If there is a point (or region) Z1 whose distance (depth) from the first surface is d1, and a point (or region) Z2 whose distance (depth) from the first surface is d2, and d1>d2, it can be expressed as "Z1 is deeper than Z2" or "Z2 is shallower than Z1". Also, if there is a point (or region) Z3 whose distance (depth) from the first surface is d3, and d1>d3>d2 holds, it can be expressed as "Z3 is at a depth between Z1 and Z2" or "Z3 is between Z1 and Z2 in the depth direction".

[0016] In the following description, the anode of the avalanche photodiode (APD) is set to a fixed potential, and a signal is taken from the cathode side. Therefore, the first conductive type semiconductor region having charges of the same polarity as the signal charge as the majority carrier is an N-type semiconductor region, and the second conductive type semiconductor region having charges of a different polarity from the signal charge as the majority carrier is a P-type semiconductor region. The present invention is also valid when the cathode of the APD is set to a fixed potential, and a signal is taken from the anode side. In this case, the first conductive type semiconductor region having charges of the same polarity as the signal charge as the majority carrier is a P-type semiconductor region, and the second conductive type semiconductor region having charges of a different polarity from the signal charge as the majority carrier is an N-type semiconductor region. In the following, a case where one node of the APD is set to a fixed potential will be described, but the potentials of both nodes may fluctuate.

[0017] In this specification, when the term "impurity concentration" is used simply, it means the net impurity concentration minus the amount compensated by the impurity of the opposite conductivity type. In other words, "impurity concentration" refers to the NET doping concentration. A region where the P-type doped impurity concentration is higher than the N-type doped impurity concentration is a P-type semiconductor region. Conversely, a region where the N-type doped impurity concentration is higher than the P-type doped impurity concentration is an N-type semiconductor region.

[0018] In addition, in the following embodiments, the connection between elements of a circuit may be described. In this case, even if another element is interposed between the elements of interest, the elements of interest are treated as being electrically connected to each other unless otherwise specified. For example, assume that an element A is connected to one node of a capacitive element C having multiple nodes, and an element B is connected to the other node. Even in such a case, the elements A and B are treated as being electrically connected to each other unless otherwise specified. In addition, when elements are connected to each other without other elements being interposed, they may be described as being directly connected. In the above example, when no other elements are provided between the element A and the capacitive element C, it can be said that the element A and the capacitive element C are directly connected.

[0019] Metallic members such as wiring and pads described in this specification may be composed of a single metal element or may be a mixture (alloy). For example, wiring described as copper wiring may be composed of a single copper element or may be composed mainly of copper and further contain other components. Also, for example, pads connected to external terminals may be composed of a single aluminum element or may be composed mainly of aluminum and further contain other components. The copper wiring and aluminum pads shown here are examples and can be changed to various metals.

[0020] Moreover, the wiring and pads shown here are one example of metal members used in a photoelectric conversion device, and the present invention can also be applied to other metal members.

[0021] In the following embodiments, as an application example of a photoelectric conversion device, an optical distance measuring device (TOF sensor) that measures the distance to an object from the time difference between the timing of emitting light and the timing of detecting reflected light from the object will be mainly described. However, each embodiment is not limited to a distance measuring device, and can be applied to other examples of photoelectric conversion devices. For example, there are an imaging device, a photometric device (a device for measuring the amount of incident light, etc.), etc.

[0022] The configuration of a distance measuring device (TOF sensor) according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an example of the configuration of a distance measuring device.

[0023] 1, the distance measuring device 1 includes a control unit 150, a light source 151, an optical system 152, a photoelectric conversion device 100, an image processing circuit 153, a memory 154, and a display device 155. The distance measuring device 1 emits light from the light source 151, and detects the reflected light reflected from an object by the photoelectric conversion device 100. Then, information on the distance to the object is obtained by calculating the time difference between the timing at which the light is emitted and the timing at which the reflected light is detected (corresponding to the flight time of light between the distance measuring device 1 and the object).

[0024] The light source 151 is, for example, a near-infrared laser light source of 850 nm to 940 nm. Visible light may be used, but the use of invisible light such as near-infrared light has the advantage that distance measurement is possible without causing visual interference. The light source 151 emits light for distance measurement toward the subject in accordance with an emission timing signal from the control unit 150. For example, modulated light, pulsed light, etc. may be used as the light for distance measurement.

[0025] The optical system 152 is configured with one or more lenses, and guides reflected light from the subject to the photoelectric conversion device 100, and forms an image on the light receiving surface (sensor unit) of the photoelectric conversion device 100. The photoelectric conversion device 100 mainly includes a pixel array in which a plurality of pixels, each having a photoelectric conversion element, are arranged two-dimensionally, and a TDC (Time to Digital Converter) device. A signal output from a pixel that detects reflected light is converted into digital time information by the TDC device. The time information measured by each pixel (or distance information obtained by converting the time information into distance) is output to the image processing circuit 153. The image processing circuit 153 generates a distance image for one frame based on the time information (or distance information) supplied from the photoelectric conversion device 100. The distance image is, for example, a two-dimensional image having distance information (depth information) as pixel values, and is data representing three-dimensional information of the subject. The distance image is also called a depth map or three-dimensional data. It is also possible to perform distance measurement at a predetermined frame rate and generate moving image data of distance images based on multiple frames of distance images obtained continuously. The distance image data generated by the image processing circuit 153 may be stored (recorded) in memory 154, or displayed on the display device 155. The distance image data may also be transmitted to an external device via a cable or network (not shown).

[0026] The configuration of a photoelectric conversion device according to the present invention will be described with reference to FIGS.

[0027] FIG. 2 is a diagram showing the configuration of a photoelectric conversion device 100 in an embodiment of the present invention. In the following, a case where the photoelectric conversion device 100 is a stacked type photoelectric conversion device will be described as an example. That is, a photoelectric conversion device configured by stacking and electrically connecting two substrates, a sensor substrate 11 and a circuit substrate 21, will be described as an example. However, the photoelectric conversion device is not limited to this. For example, the photoelectric conversion device may be a photoelectric conversion device in which the configuration included in the sensor substrate 11 and the configuration included in the circuit substrate 21 are arranged on a common semiconductor layer, as described below. In the following, a photoelectric conversion device in which the configuration included in the sensor substrate 11 and the configuration included in the circuit substrate 21 are arranged on a common semiconductor layer is also referred to as a non-stacked photoelectric conversion device.

[0028] The sensor substrate 11 has a first semiconductor layer having photoelectric conversion elements 102 described later, and a first wiring structure. The circuit substrate 21 has a second semiconductor layer having circuits such as a signal processing unit 103 described later, and a second wiring structure. The photoelectric conversion device 100 is configured by laminating the second semiconductor layer, the second wiring structure, the first wiring structure, and the first semiconductor layer in this order.

[0029] In Figure 2, light enters from the second surface (back side) and is reflected by the first surface (front side), which is the surface opposite the second surface. 2 illustrates a back-illuminated photoelectric conversion device in which a circuit board 21 is disposed on the back surface of the photoelectric conversion device. In the case of a non-stacked photoelectric conversion device, the surface on which the transistors of the signal processing circuit are disposed is referred to as the first surface. In the case of a front-illuminated photoelectric conversion device, the front surface is the second surface (light incident surface) and the back surface is the first surface.

[0030] In the following, the sensor substrate 11 and the circuit substrate 21 will be described as diced chips, but are not limited to chips. For example, each substrate may be a wafer. Also, each substrate may be stacked in a wafer state and then diced, or each chip may be stacked and bonded after being chipped.

[0031] A pixel region 12 is disposed on the sensor substrate 11, and a circuit region 22 that processes signals detected in the pixel region 12 is disposed on the circuit substrate 21.

[0032] 3 is a layout diagram of the sensor substrate 11. Pixels 101, each having a photoelectric conversion element 102 including an avalanche photodiode (APD), are arranged two-dimensionally to form a pixel region 12. This pixel region 12 is also called a pixel array.

[0033] The pixel 101 is typically a pixel for forming an image, but when used for TOF (Time of Flight), it does not necessarily have to form an image. That is, the pixel 101 may be a pixel for measuring the time when light arrives. When the pixel 101 is a pixel for forming an image, a pixel signal corresponding to the amount of light (amount of charge) detected during a predetermined exposure period is output from the pixel 101. On the other hand, when the pixel 101 is a pixel for measuring the time when light arrives, a pixel signal is output at the timing when light is detected. Note that the pixel 101 may serve as both a pixel for forming an image and a pixel for measuring the time when light arrives.

[0034] 4 is a configuration diagram of the circuit board 21. It has a signal processing unit 103 that processes charges photoelectrically converted by the photoelectric conversion element 102 in FIG. 3, a TDC device 112, a control pulse generating unit 115, a horizontal transfer circuit unit 111, vertical output lines 113, a vertical scanning circuit unit 110, and drive lines 116.

[0035] The photoelectric conversion element 102 in FIG. 3 and the signal processing unit 103 in FIG. 4 are electrically connected via connection wiring provided for each pixel.

[0036] The vertical scanning circuit unit 110 receives a control pulse supplied from a control pulse generating unit 115, and supplies the control pulse to each pixel via a drive line 116. The vertical scanning circuit unit 110 functions as a row selection circuit that selects one row of pixels by outputting a control pulse (selection signal) to the drive line 116 of the pixel row from which the signal is to be read out. The vertical scanning circuit unit 110 uses logic circuits such as a shift register and an address decoder.

[0037] The control pulse generating unit 115 has a signal generating unit 215 that generates a control signal P_CLK for a switch, which will be described later. The signal generating unit 215 generates a pulse signal for controlling the switch, as will be described later. For example, as shown in FIG. 5(A), the signal generating unit 215 may generate a control signal P_CLK in common for a plurality of pixels in the pixel region, or as shown in FIG. 5(B), the control signal P_CLK may be generated for each pixel. When the pulse signal P_CLK is generated in common, at least one of the period, the number of pulses, and the pulse width of the signal P_EXP pulse signal for controlling the exposure period is generated in common in correspondence with the exposure period. When the control signal P_CLK is controlled for each pixel, a signal can be generated using both the input signal P_CLK_IN output from the control pulse generating unit 115 and the signal P_EXP for controlling the exposure period. For example, the control pulse generating unit 115 preferably has a frequency dividing circuit. This allows simple control, and reduces an increase in the number of elements.

[0038] The signal output from the photoelectric conversion element 102 of each pixel is processed by the signal processing unit 103. A pixel signal is output from the signal processing unit 103 of the pixel belonging to the row selected by the vertical scanning circuit unit 110 to the vertical output line 113. This pixel signal is input to the TDC device 112 as a stop signal. The TDC device 112 is a device that acquires time information (digital value) indicating the timing at which the stop signal is input, i.e., the timing at which the photoelectric conversion element 102 detects light. The horizontal transfer circuit unit 111 is a circuit that reads out the time information of each column from the memory of the TDC device 112. The read-out time information of the pixels for one row is sent to the image processing circuit 153 (FIG. 1).

[0039] 3, the pixels 101 may be arranged one-dimensionally in the pixel region 12. The function of the signal processing unit 103 does not necessarily need to be provided for each pixel 101, and for example, one signal processing unit 103 may be shared by a plurality of pixels 101, and signal processing may be performed sequentially.

[0040] Figures 5(A) and 5(B) are examples of block diagrams including the equivalent circuits of Figures 2 and 3. Figure 5(A) is an example in which the signal generating unit 215 is provided in common to a plurality of pixels, and Figure 5(B) is an example in which the control signal P_CLK can be controlled for each pixel.

[0041] 5(A) will be described. In Fig. 5(A), a photoelectric conversion element 102 having an APD 201 is provided on a sensor substrate 11, and other members are provided on a circuit substrate 21.

[0042] The APD 201 generates charge pairs according to the incident light by photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD 201. A voltage VH (second voltage) higher than the voltage VL supplied to the anode is supplied to the cathode of the APD 201. A reverse bias voltage that causes the APD 201 to perform avalanche multiplication is supplied to the anode and cathode. With such a voltage supplied, the charges generated by the incident light undergo avalanche multiplication, generating an avalanche current.

[0043] When a reverse bias voltage is supplied, there are two modes: Geiger mode, in which the potential difference between the anode and cathode is greater than the breakdown voltage, and linear mode, in which the potential difference between the anode and cathode is close to or less than the breakdown voltage. An APD operated in Geiger mode is called a SPAD (Single Photon Avalanche Diode). For example, the voltage VL (first voltage) is -30V, and the voltage VH (second voltage) is 1V. The APD201 may be operated in either linear mode or Geiger mode. In the case of a SPAD, the potential difference is greater than in a linear mode APD, and the effect of withstanding voltage becomes more pronounced.

[0044] The switch 202 is connected to a power supply line to which a drive voltage VH is supplied and to the APD 201. The switch 202 is connected to one of the anode and cathode nodes of the APD 201. The switch 202 switches the potential difference between the anode and cathode of the APD 201 between a first potential difference that causes avalanche multiplication and a second potential difference that does not cause avalanche multiplication. Hereinafter, switching from the second potential difference to the first potential difference is also referred to as turning on the switch 202, and switching from the first potential difference to the second potential difference is also referred to as turning off the switch 202. The switch 202 functions as a quenching element. The switch 202 functions as a load circuit (quenching circuit) during signal multiplication by avalanche multiplication, and has a function of suppressing avalanche multiplication by suppressing the voltage supplied to the APD 201 (quenching operation). The switch 202 also has a function of returning the voltage supplied to the APD 201 to the drive voltage VH by passing a current corresponding to the voltage drop caused by the quench operation (recharge operation). 02 functions as a control circuit for controlling the occurrence of avalanche multiplication in the APD 201.

[0045] The switch 202 can be configured, for example, by a MOS transistor. A control signal P_CLK for the switch 202, which is supplied from the signal generating unit 215, is applied to a gate electrode of the MOS transistor that configures the switch 202. In this embodiment, the on / off of the switch 202 is controlled by controlling the voltage applied to the gate electrode of the switch 202.

[0046] The signal processing unit 103 has a waveform shaping unit 210 and a selection circuit 212. In this specification, it is sufficient that the signal processing unit 103 has at least one of the waveform shaping unit 210 and the selection circuit 212. In addition, a counter circuit that counts the pulse signal output from the waveform shaping unit 210 may be provided in the subsequent stage of the waveform shaping unit 210.

[0047] The waveform shaping unit 210 shapes the potential change of the cathode of the APD 201 obtained when a photon is detected, and outputs a pulse signal. The node on the input side of the waveform shaping unit 210 is nodeA, and the node on the output side is nodeB. The waveform shaping unit 210 changes the output potential from the node nodeB depending on whether the input potential to the node nodeA is equal to or higher than a predetermined value or lower. For example, in FIG. 6, when the input potential to the node nodeA becomes a high potential equal to or higher than the judgment threshold, the output potential from the node nodeB becomes a low level. When the input potential to the node nodeA becomes a potential lower than the judgment threshold, the output potential from the node nodeB becomes a high level. For example, an inverter circuit is used as the waveform shaping unit 210. In FIG. 5(A), an example in which one inverter is used as the waveform shaping unit 210 is shown, but a circuit in which multiple inverters are connected in series may be used, or other circuits having a waveform shaping effect may be used.

[0048] It is possible to perform a quench operation and a recharge operation using the switch 202 according to the avalanche multiplication in the APD 201, but depending on the timing of photon detection, the charge generated in the APD 201 may not be determined as an output signal. For example, assume that avalanche multiplication occurs in the APD 201, the node nodeA becomes low level, and a recharge operation is performed. In general, the decision threshold of the waveform shaping unit 210 is set to a potential higher than the potential difference at which avalanche multiplication occurs in the APD 201. When a photon is incident on the APD 201 when the potential of the node nodeA is lower than the decision threshold due to the recharge operation and the potential is such that avalanche multiplication is possible in the APD 201, avalanche multiplication occurs in the APD 201 and the voltage of the nodeA drops. In other words, since the potential of the nodeA drops at a voltage lower than the decision threshold, no potential change occurs across the decision threshold, and the output potential from the node nodeB does not change. Therefore, even though avalanche multiplication occurs, the photon detection is not determined as a signal. Particularly under high illuminance, photons enter the APD 201 continuously in a short period of time, making it difficult for the incident light to be determined as a signal. As a result, even under high illuminance, the actual number of incident photons and the output signal tend to diverge.

[0049] In contrast, by applying a control signal P_CLK to the switch 202 to switch the switch 202 between an on state and an off state, it is possible to determine a signal even when photons continuously enter the APD 201 in a short period of time. In FIG. 6, an example is described in which the control signal P_CLK is a pulse signal with a repetitive cycle. In other words, in FIG. 6, a form is described in which the switch 202 is switched on and off at a predetermined clock frequency. However, the effect of suppressing an increase in power consumption of the photoelectric conversion device 100 can be obtained even if the pulse signal is not a signal with a repetitive cycle.

[0050] The selection circuit 212 is connected to the vertical scanning circuit unit 110 shown in FIG. A signal pSEL is supplied to the selection circuit 212, which switches between electrical connection and non-connection between the waveform shaping section 210 and the vertical output line 113. The selection circuit 212 includes, for example, a buffer circuit for outputting a signal.

[0051] The electrical connection may be switched by disposing a switch such as a transistor between the switch 202 and the APD 201 or between the photoelectric conversion element 102 and the signal processing unit 103. Similarly, the supply of the voltage VH or the voltage VL to the photoelectric conversion element 102 may be electrically switched using a switch such as a transistor.

[0052] FIG. 6 is a diagram showing a schematic diagram of the relationship between the control signal P_CLK of the switch, the potential of the node nodeA, the potential of the node nodeB, and the output signal. In this embodiment, when the control signal P_CLK is at a high level, the drive voltage VH is not easily supplied to the APD 201, and when the control signal P_CLK is at a low level, the drive voltage VH is supplied to the APD 201. The high level of the control signal P_CLK is, for example, 1V, and the low level of the control signal P_CLK is, for example, 0V. When the control signal P_CLK is at a high level, the switch is turned off, and when the control signal P_CLK is at a low level, the switch is turned on. The resistance value of the switch when the control signal P_CLK is at a high level is higher than the resistance value of the switch when the control signal P_CLK is at a low level. When the control signal P_CLK is at a high level, even if avalanche multiplication occurs in the APD 201, a recharge operation is not easily performed, so the potential supplied to the APD 201 is a potential equal to or lower than the breakdown voltage of the APD 201. Therefore, the avalanche multiplication operation in the APD 201 stops.

[0053] 5A, it is preferable that the switch 202 is configured with one transistor and that the quench operation and the recharge operation are performed by one transistor. This makes it possible to reduce the number of circuits compared to the case where the quench operation and the recharge operation are performed by different circuit elements.

[0054] At time t1, the control signal P_CLK changes from high level to low level, the switch is turned on, and the recharge operation of the APD 201 is started. This causes the potential of the cathode of the APD 201 to transition to high level. Then, the potential difference between the potentials applied to the anode and cathode of the APD 201 becomes a state in which avalanche multiplication is possible. The potential of the cathode is the same as that of the node nodeA. Therefore, when the potential of the cathode transitions from low level to high level, the potential of the node nodeA becomes equal to or higher than the judgment threshold at time t2. At this time, the pulse signal output from the node nodeB is inverted and goes from high level to low level. After that, the potential difference of the drive voltage VH-drive voltage VL is applied to the APD 201. The control signal P_CLK becomes high level, and the switch is turned off.

[0055] Next, at time t3, when a photon is incident on the APD 201, avalanche multiplication occurs in the APD 201, and the voltage of the cathode drops. That is, the voltage of the node nodeA drops. When the amount of voltage drop becomes larger and the voltage difference applied to the APD 201 becomes smaller, the avalanche multiplication of the APD 201 stops as at time t2, and the voltage level of the node nodeA does not drop by more than a certain value. When the voltage of the node nodeA becomes lower than the decision threshold while the voltage of the node nodeA is dropping, the voltage of the node nodeB goes from low level to high level. That is, the part of the output waveform at the node nodeA that exceeds the decision threshold is shaped by the waveform shaping unit 210 and is output as a signal at the nodeB.

[0056] Between time t3 and time t4, photons are incident on the APD 201. However, since the switch is in the off state and the voltage applied to the APD 201 does not have a potential difference that allows avalanche multiplication, the voltage level of the node A does not exceed the decision threshold.

[0057] At time t4, the control signal P_CLK changes from high to low, and the switch is turned on. As a result, a current flows to node A to compensate for the voltage drop from the drive voltage VH, and the voltage of node A transitions to its original voltage level. At this time, the voltage of node A becomes equal to or higher than the decision threshold at time t5, so the pulse signal of node B is inverted and goes from high to low.

[0058] At time t6, node A is stabilized to the original voltage level, and the control signal P_CLK goes from low to high. Therefore, the switch is turned off. After this, the potentials of the nodes and signal lines change in response to the control signal P_CLK and the incidence of photons, as described from time t1 to time t6.

[0059] An example of the configuration of the TDC device will be described in more detail below.

[0060] (First embodiment) FIG. 7 shows a schematic configuration of the TDC device 112 of the first embodiment.

[0061] The TDC device 112 is a multi-channel TDC (M-input TDC) having M stop channels, and includes M TDC circuits 70 operating in parallel. The TDC device 112 also includes a start circuit 71, a multi-phase clock generation unit 72, a start control unit 73, and N+1 AND circuits 74.

[0062] The M TDC circuits 70 correspond to a pixel group of M columns of the pixel array. That is, the M TDC circuits 70 are respectively connected to M vertical output lines 113 of the pixel array, and pixel signals output from M pixels of a row selected by the vertical scanning circuit unit 110 are input as stop signals to the corresponding TDC circuits 70 (stop channels). This allows TDC operations for one row to be performed in parallel, realizing distance measurement processing at a high frame rate.

[0063] The start circuit 71 is a circuit that supplies a start signal to the TDC circuit 70. When a count start signal count_start is input from the start control unit 73, the start circuit 71 supplies a start signal to the M TDC circuits 70, causing the M TDC circuits 70 to simultaneously start their counting operations.

[0064] The multi-phase clock generating unit 72 is a circuit that generates a common clock signal to be supplied to the M TDC circuits 70. The multi-phase clock generating unit 72 generates a multi-phase clock signal composed of a plurality of clock signals (φ0 to φN) that are out of phase with each other. The time resolution of the TDC circuit 70 is determined by the phase difference of the multi-phase clock signals. In this embodiment, for example, a 1.25 GHz, 8-phase multi-phase clock signal is used, and the phase difference, i.e., the time resolution, is 100 psec. Note that the value of the time resolution is an example, and may be appropriately designed according to the required specifications of the distance measuring device 1.

[0065] Each output terminal of the multi-phase clock generation unit 72 is connected to an input terminal of a corresponding AND circuit 74. When a clock supply start signal clk_start is input from the start control unit 73 to each AND circuit 74, the multi-phase clock signals are simultaneously supplied to the M TDC circuits 70. That is, in this embodiment, a clock supply unit that simultaneously supplies a common clock signal to the multiple TDC circuits 70 is realized by combining the multi-phase clock generation unit 72 and the AND circuit 74.

[0066] The start control unit 73 determines the timing at which a common clock signal is supplied to the TDC circuit 70 (clock supply timing) and the timing at which the TDC circuit 70 starts counting (count The start control unit 73 is a circuit that controls the count start timing (count start timing). In this embodiment, the start control unit 73 controls the count start timing so that the count operation of the TDC circuit 70 starts after a predetermined delay time τ has elapsed from the clock supply timing. The delay time τ is set to a length required for stabilizing the power supply fluctuation of the TDC circuit 70 that may occur due to the simultaneous supply of the common clock signal so that it does not affect the TDC operation, and is set to a value of, for example, several hundred psec to several nsec. The behavior of the power supply fluctuation changes depending on the number of channels of the TDC circuit 70 and the capacity of the external power supply system that supplies power to the TDC device 112. Therefore, it is preferable to perform experiments under various expected usage conditions and set an appropriate delay time τ. Even if a power supply fluctuation occurs due to the simultaneous supply of the common clock signal, by providing the above-mentioned delay time τ, the count operation starts after the power supply fluctuation disappears or becomes sufficiently stable, so that the malfunction of the TDC circuit due to the power supply fluctuation can be prevented in advance.

[0067] 8 shows a configuration example of the start control unit 73. The start control unit 73 of this embodiment is composed of a latch circuit 730 and a delay circuit 731, and generates a clock supply start signal clk_start and a count start signal count_start based on the emission timing signal laser_start. The emission timing signal laser_start is a signal synchronized with the timing at which the light source 151 emits light, and is supplied from the control unit 150 (FIG. 1) or the control pulse generation unit 115 (FIG. 4).

[0068] The latch circuit 730 is composed of an SR latch that combines two NOR circuits, and the emission timing signal laser_start is input to the Set terminal. The reset signal reset supplied from the control pulse generating unit 115 (FIG. 4) is input to the Reset terminal of the latch circuit 730. The reset signal reset is a signal for resetting the counting operation and returning the TDC circuit to its initial state, and is reset before starting counting for each row.

[0069] The delay circuit 731 is a generating unit that generates a count start signal count_start by delaying the injection timing signal laser_start by a predetermined delay time τ. The delay circuit 731 is composed of, for example, an inverter chain, a flip-flop, and the like.

[0070] The effect of the start control of the first embodiment will be described with reference to Figures 9 and 10. Figure 9 is an example of a timing chart of the start control of the first embodiment, and Figure 10 is an example of a timing chart of the start control of a comparative example.

[0071] First, the start control of the first embodiment will be described with reference to FIG.

[0072] At time t0, when the reset signal reset is input to the start control unit 73, the latch circuit 730 is reset and the clock supply start signal clk_start goes low, which closes the gate of the AND circuit 74 and stops the supply of multiphase clock signals to the TDC circuit 70.

[0073] At time t1, when the injection timing signal laser_start is input to the start control unit 73, the S terminal of the latch circuit 730 becomes High. As a result, at time t2, the clock supply start signal clk_start, which is the Q output of the latch circuit 730, becomes High and is maintained in that state until the next reset.

[0074] At time t2, when the clock supply start signal clk_start goes High, the gate of the AND circuit 74 opens, and the multi-phase clock signals φ0 to φN are simultaneously supplied to the M TDC circuits 70. At this time, the amount of current flowing through the circuit changes suddenly, causing the TDC Power supply fluctuations in the circuit 70 occur.

[0075] Then, after the power supply voltage of the TDC circuit 70 has sufficiently stabilized, at time t3, a count start signal count_start is output from the delay circuit 731 of the start control unit 73. When the count start signal count_start is supplied to each TDC circuit 70 via the start circuit 71, each TDC circuit 70 starts counting the clock signal.

[0076] When a stop signal output from a pixel that detects reflected light is input to the TDC circuit 70, the TDC circuit 70 stops counting, and the count value at that time is latched. For example, as shown in FIG. 9, when a stop signal is input at time t4, a count value corresponding to the time difference Δt between the count start timing t3 and the input timing t4 of the stop signal is acquired. This count value corresponds to time information indicating the timing (time t4) at which the photoelectric conversion element 102 detects light. In the signal processing at the subsequent stage, Δt is calculated from the phase difference between the count value and the clock signal, and a delay time τ is added to calculate the flight time T (=t4-t1=Δt+τ) of light, and further the distance d to the subject can be calculated by the following equation. d=c×T / 2 (c is the speed of light)

[0077] According to the start control of the present embodiment described above, even if a power supply fluctuation occurs due to the simultaneous supply of a common clock signal, the counting operation starts after the power supply fluctuation disappears or becomes sufficiently stable, so that it is possible to prevent malfunction of the TDC circuit due to the power supply fluctuation before it occurs, and therefore it is possible to measure the distance d to the subject with high accuracy.

[0078] 10, the delay time τ is not set, and the multiphase clock signals φ0 to φN are simultaneously supplied at time t2, and the counting operation of the TDC circuit is started at the same time. In the case of control such as the comparative example, it can be seen that a power supply fluctuation occurs immediately after the start of the counting operation. Such a power supply fluctuation may cause a malfunction of the counting operation, leading to a malfunction of the TDC device 112, and ultimately to a failure or deterioration of the accuracy of distance measurement.

[0079] Second embodiment A TDC device 112 of the second embodiment will be described with reference to Figures 11 to 13. The difference from the first embodiment is that the start control unit 75 can change the delay amount of the count start signal count_start. Since the other configurations are the same as those of the first embodiment, the following description will focus on the configurations unique to the second embodiment.

[0080] 11, the TDC device 112 of the second embodiment is configured to include M TDC circuits 70, a start circuit 71, a multiphase clock generating unit 72, a start control unit 75, and N+1 AND circuits 74. The start control unit 75 receives an injection timing signal laser_start, a reset signal reset, and a delay amount selection signal delay_select from the control unit 150 (FIG. 1) or the control pulse generating unit 115 (FIG. 4).

[0081] As shown in FIG. 12, the start control unit 75 of this embodiment is composed of a latch circuit 750 and a delay circuit 751. The latch circuit 750 is the same as the latch circuit 730 (FIG. 8) of the first embodiment. The delay circuit 751 is a generation unit that generates a count start signal count_start by delaying the injection timing signal laser_start. While the delay circuit 731 of the first embodiment has a fixed delay amount, the delay circuit 751 of the second embodiment can change the delay amount by a delay amount selection signal delay_select. Cut.

[0082] 13 shows an example of the configuration of the delay circuit 731. The delay circuit 731 has a plurality of delay elements 752 connected in series and a selector 753. The selector 753 receives the injection timing signal laser_start and the output of each delay element 752, and can select a signal to be output as the count start signal count_start by the delay amount selection signal delay_select. When the injection timing signal laser_start is selected, a count start signal count_start synchronized with the injection timing signal laser_start (without a delay amount) is output. When the output of the delay element 752 is selected, a count start signal count_start delayed more than the injection timing signal laser_start is output. The more stages of delay elements 752 are passed through, the larger the delay amount becomes.

[0083] The effect of the start control of the second embodiment will be described with reference to Figures 14(A) and 14(B). For example, the behavior of the power supply fluctuation changes depending on the number of channels of the TDC circuit 70 and the capacity of the external power supply system that supplies power to the TDC device 112. Figure 14(A) shows an example where the power supply fluctuation is small, and Figure 14(B) shows an example where the power supply fluctuation is large. When the power supply fluctuation is small as in Figure 14(A), the delay amount τ1 may be set small. On the other hand, when the power supply fluctuation is large as in Figure 14(B), the delay amount τ2 is increased. When it is expected that the power supply fluctuation will not occur or will be sufficiently small, no delay amount is set.

[0084] If a stop signal is input between the emission of light and the start of counting (time period t1 to t3), counting is not performed and distance information cannot be obtained. In other words, the delay amount affects the minimum distance that can be measured. Therefore, it is not appropriate to unnecessarily increase the delay amount, and it is preferable to determine the delay amount by balancing the risk of malfunction due to power supply fluctuation and the measurable range. According to the configuration of this embodiment, the delay amount can be optimized in consideration of the configuration, use, and required specifications of the distance measuring device 1, the performance of the external power supply system, and the like, so that the convenience and flexibility of the distance measuring device 1 can be improved. Note that, when the optimal value of the delay amount is expected, the delay amount may be preset in the distance measuring device 1. Also, the user may be able to change the set value of the delay amount. Alternatively, the distance measuring device 1 may detect the presence or absence and the degree of power supply fluctuation, and perform calibration to obtain the optimal delay amount.

[0085] Third embodiment In the first and second embodiments, a configuration in which an avalanche photodiode is used as the photoelectric conversion element has been described. In the third embodiment, a charge-accumulation type photodiode is used as the photoelectric conversion element. Since other configurations (such as the configuration of the TDC device) may be the same as those in the first or second embodiment, only the pixel circuit, which is a configuration unique to the third embodiment, will be described below.

[0086] FIG. 15 is an equivalent circuit diagram of a pixel using a charge-storage type photodiode. In the following description, it is assumed that the charge stored in the photodiode, which is a photoelectric conversion element, is electrons, and all the transistors provided in the pixel are N-type transistors. Note that the charge stored in the photodiode is not limited to electrons, and the charge stored in the photodiode may be holes. In this case, the transistor of the pixel may be a P-type transistor. In other words, the definition of the conductivity type used in the following description can be changed according to the polarity of the charge handled as a signal.

[0087] The pixel includes a photodiode D1, a transfer transistor M1, a charge conversion unit C1, a reset transistor M3, an amplification transistor M4, and a selection transistor M5.

[0088] The photodiode D1 is a photoelectric conversion element that converts incident light into electric charges. The transfer transistor M1 is provided in an electrical path between the photodiode D1 and a node to which the charge conversion unit C1, the reset transistor M3, and the amplification transistor M4 are connected. One end of the source or drain of the reset transistor M3 is connected to a common node to the charge conversion unit C1 and the amplification transistor M4, and a power supply voltage VDD is applied to the other end. The gate of the amplification transistor M4 is connected to a common node to the charge conversion unit C1 and the source or drain of the reset transistor M3. One end of the source or drain of the amplification transistor M4 is applied to a power supply voltage VDD, and the other end is connected to one end of the source or drain of the selection transistor M5. The selection transistor M5 is provided in an electrical path between the amplification transistor M4 and the vertical output line 113. In other words, the amplification transistor M4 is electrically connected to the vertical output line 113 via the selection transistor M5. The charge conversion section C1 corresponds to the floating diffusion section, and is a capacitance including a floating diffusion capacitance provided in the semiconductor substrate and a parasitic capacitance of an electrical path from the transfer transistor M1 to the amplification transistor M4 via the floating diffusion capacitance. In reality, the floating diffusion capacitance is provided as a wiring capacitance.

[0089] The signals pRES, pTx, and pSEL in Fig. 15 are control signals supplied to pixels from the vertical scanning circuit unit 110 shown in Fig. 2. The signal pTx is supplied to the gate of the transfer transistor M1. The signal pRES is supplied to the gate of the reset transistor M3, and the signal pSEL is supplied to the gate of the selection transistor M5.

[0090] A current source (not shown) is connected to the vertical output line 113. When a signal pSEL supplied to the gate of the selection transistor M5 becomes active level, the selection transistor M5 is turned on. As a result, a current is supplied from the current source to the amplification transistor M4. In the pixel, a source follower circuit is formed by a power supply voltage VDD, the amplification transistor M4, and a current source (not shown) connected to the vertical output line 113. This source follower circuit outputs a signal based on the potential of the charge conversion unit C1 to the vertical output line 113 via the transistor M5.

[0091] For pixels located in a pixel row where the signal pSEL is at an active level, the vertical scanning circuit unit 110 sets the signal pTx output to the pixels located in that pixel row to an active level throughout the entire period when the signal pSEL is at an active level. As a result, during the period when the signal pSEL is at an active level, the signal level output by the amplifying transistor M4 changes at the timing when a signal (light reflected from a subject of laser light) is input to the photodiode D1. This change in signal level is input to the TDC circuit 70 via the vertical output line 113 as a stop signal. This makes it possible to obtain time information of the digital signal indicating the timing when the signal (light reflected from a subject of laser light) is input to the photodiode.

[0092] It is also possible to use a configuration in which the photodiode D1 and the gate of the amplification transistor M4 are directly connected without providing the transfer transistor M1.

[0093] The above-described configuration can also achieve the same effects as the first and second embodiments.

[0094] (Fourth embodiment) The distance measuring device and the moving body of this embodiment will be described with reference to Fig. 16(A) and Fig. 16(B). Fig. 16(A) is a diagram showing the configuration of an in-vehicle camera system equipped with the distance measuring device of this embodiment, and Fig. 16(B) is a diagram showing the configuration of the moving body of this embodiment.

[0095] As shown in FIG. 16A, the vehicle-mounted camera system 1600 measures the distance to an object. The vehicle-mounted camera system 1600 includes a distance measuring device 1 for measuring the distance between the vehicle and the target object, and a collision determination unit 1618 for determining whether or not there is a possibility of a collision based on the measured distance. Here, the distance measuring device 1 is the TOF sensor described in the first to third embodiments. All or part of the functions of the vehicle-mounted camera system 1600 may be realized by dedicated hardware or by a software module. In addition, they may be realized by a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a combination of these.

[0096] The vehicle-mounted camera system 1600 is connected to a vehicle information acquisition device 1620, and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The vehicle-mounted camera system 1600 is also connected to an ECU 1630, which is a control device that outputs a control signal to generate a braking force for the vehicle based on the judgment result of the collision judgment unit 1618. The vehicle-mounted camera system 1600 is also connected to an alarm device 1640 that issues an alarm to the driver based on the judgment result of the collision judgment unit 1618. For example, when the judgment result of the collision judgment unit 1618 indicates that there is a high possibility of a collision, the ECU 1630 performs vehicle control to avoid a collision and reduce damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 1640 warns the user by sounding an alarm, displaying alarm information on the screen of a car navigation system, etc., or vibrating a seat belt or steering wheel.

[0097] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are captured by an in-vehicle camera system 1600. 16B shows an in-vehicle camera system when capturing an image of the area in front of the vehicle (imaging range 1650). A vehicle information acquisition device 1620 sends an instruction to the in-vehicle camera system 1600. With this configuration, the accuracy of distance measurement can be further improved.

[0098] Although the above describes an example of control to avoid collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to avoid going out of a lane, and the like. Furthermore, the in-vehicle camera system is not limited to vehicles such as automobiles, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. The moving body includes one or both of a driving force generating unit that generates a driving force mainly used for the movement of the moving body, and a rotating body mainly used for the movement of the moving body. The driving force generating unit can be an engine, a motor, and the like. The rotating body can be a tire, a wheel, a screw of a ship, a propeller of an aircraft, and the like. In addition, the present invention can be applied not only to moving bodies, but also to a wide range of devices that use object recognition, such as an intelligent transport system (ITS).

[0099] Fifth embodiment The above-described photoelectric conversion device and distance measuring device may be applied to electronic devices such as so-called smartphones and tablets.

[0100] 17(A) and 17(B) are diagrams showing an example of an electronic device 1700 equipped with a photoelectric conversion device. Fig. 17(A) shows the front side of the electronic device 1700, and Fig. 17(B) shows the rear side of the electronic device 1700.

[0101] 17(A), a display 1710 for displaying an image is disposed in the center of the surface of electronic device 1700. Then, along the upper side of the surface of electronic device 1700, front cameras 1721 and 1722 using photoelectric conversion devices, an IR light source 1730 that emits infrared light, and a visible light source 1740 that emits visible light are disposed.

[0102] 17B, ​​along the upper side of the rear surface of the electronic device 1700, rear cameras 1751 and 1752 using photoelectric conversion devices, an IR light source 1760 that emits infrared light, Also provided is a visible light source 1770 that emits visible light.

[0103] In the electronic device 1700 configured in this manner, by applying the above-mentioned photoelectric conversion device, for example, it is possible to capture a higher quality image. Note that the photoelectric conversion device can also be applied to other electronic devices such as infrared sensors, distance measuring devices using active infrared light sources, security cameras, and personal or biometric authentication cameras. This can improve the accuracy, performance, and the like of these electronic devices.

[0104] (others) In the above embodiment, the count start signal count_start is generated based on the emission timing signal laser_start, but the method of generating the count start signal count_start is not limited to this. For example, the count start signal count_start may be generated based on another signal synchronized with the emission timing of the measurement light, or may be generated based on the clock supply start signal clk_start.

[0105] Although various devices have been described in the above embodiment, a mechanical device may be further provided. The mechanical device in the camera can drive optical components for zooming, focusing, and shutter operation. Alternatively, the mechanical device in the camera can move a photoelectric conversion device for vibration reduction operation.

[0106] The device may be transportation equipment such as a vehicle, ship, or aircraft. A mechanical device in transportation equipment may be used as a moving device. The device as transportation equipment is suitable for transporting a photoelectric conversion device or for assisting and / or automating driving (piloting) by using an imaging function. A processing device for assisting and / or automating driving (piloting) can perform processing for operating the mechanical device as a moving device based on information obtained by the photoelectric conversion device.

[0107] The above-described embodiments can be modified as appropriate without departing from the technical concept. The disclosure of this specification includes not only what is described in this specification, but also all matters that can be understood from this specification and the drawings attached hereto. The disclosure of this specification also includes the complement of the concepts described in this specification. In other words, if this specification contains a statement that "A is greater than B," for example, this specification can be said to disclose that "A is not greater than B" even if the statement that "A is not greater than B" is omitted. This is because when it is stated that "A is greater than B," it is assumed that the case in which "A is not greater than B" is taken into consideration.

[0108] As used herein, expressions such as "A or B," "at least one of A and B," "at least one of A or / and B," "one or more of A or / and B," and the like, can include all possible combinations of the listed items unless expressly defined otherwise. That is, the above expressions are understood to disclose all cases including at least one A, at least one B, and both at least one A and at least one B. This applies equally to combinations of three or more elements.

[0109] The disclosure of this embodiment includes the following configuration.

[0110] (Configuration 1) Multiple TDC (Time to Digital Converter) circuits, a clock supply unit for supplying a common clock signal to the plurality of TDC circuits; A count starter that instructs the plurality of TDC circuits to start counting operations. A start control unit that outputs a start signal, the start control unit outputs the count start signal after a predetermined delay time has elapsed from the timing at which the common clock signal is supplied from the clock supply unit to the plurality of TDC circuits. TDC device.

[0111] (Configuration 2) The common clock signal supplied by the clock supply unit is a multi-phase clock signal composed of a plurality of clock signals having mutually shifted phases. 2. The TDC device according to configuration 1.

[0112] (Configuration 3) the start control unit outputs a clock supply start signal to the clock supply unit to instruct the timing to start supplying the common clock signal, and controls the output timing of each signal so that the count start signal is output after the predetermined delay time has elapsed since the clock supply start signal was output. 3. The TDC device according to configuration 1 or 2.

[0113] (Configuration 4) The TDC device acquires time information indicating a timing at which a pixel having a photoelectric conversion element detects light emitted from a light source and reflected by an object, based on a signal output from the pixel. The TDC device according to any one of configurations 1 to 3.

[0114] (Configuration 5) A signal output from a pixel different from another pixel is input to each of the plurality of TDC circuits as a stop signal for stopping a count operation. 5. The TDC apparatus of claim 4.

[0115] (Configuration 6) The start control unit has a generation unit that generates the count start signal based on an emission timing signal synchronized with a timing at which the light source emits light. 6. The TDC device of configuration 4 or 5.

[0116] (Configuration 7) The generation unit is a delay circuit that generates the count start signal by delaying the injection timing signal. 7. The TDC apparatus of claim 6.

[0117] (Configuration 8) The delay circuit is capable of changing the delay amount of the count start signal. 8. The TDC apparatus of claim 7.

[0118] (Configuration 9) A light source; a plurality of pixels each having a photoelectric conversion element for detecting light emitted from the light source and reflected by an object; and a TDC (Time to Digital Converter) device that acquires time information indicating a timing at which the photoelectric conversion element of each pixel detects light based on signals output from the plurality of pixels, The TDC device comprises: A plurality of TDC circuits corresponding to the plurality of pixels; a clock supply unit for supplying a common clock signal to the plurality of TDC circuits; a start control unit that outputs a count start signal that indicates a start timing of a count operation to the plurality of TDC circuits; the start control unit outputs the count start signal after a predetermined delay time has elapsed from the timing at which the common clock signal is supplied from the clock supply unit to the plurality of TDC circuits. Ranging device.

[0119] (Configuration 10) The common clock signal supplied by the clock supply unit is a multi-phase clock signal composed of a plurality of clock signals having mutually shifted phases. A ranging device according to configuration 9.

[0120] (Configuration 11) the start control unit outputs a clock supply start signal to the clock supply unit to instruct the timing to start supplying the common clock signal, and controls the output timing of each signal so that the count start signal is output after the predetermined delay time has elapsed since the clock supply start signal was output. 11. A distance measuring device according to configuration 9 or 10.

[0121] (Configuration 12) A signal output from a pixel different from another pixel is input to each of the plurality of TDC circuits as a stop signal for stopping a count operation. The distance measuring device according to any one of configurations 9 to 11.

[0122] (Configuration 13) The photoelectric conversion element is an avalanche photodiode. The distance measuring device according to any one of configurations 9 to 12.

[0123] (Configuration 14) The avalanche photodiode is a SPAD operating in Geiger mode. 14. A distance measuring device according to claim 13.

[0124] (Configuration 15) The photoelectric conversion element is a charge-accumulation type photodiode. The distance measuring device according to any one of configurations 9 to 12.

[0125] (Configuration 16) The start control unit has a generation unit that generates the count start signal based on an emission timing signal synchronized with a timing at which the light source emits light. The distance measuring device according to any one of configurations 9 to 15.

[0126] (Configuration 17) The generation unit is a delay circuit that generates the count start signal by delaying the injection timing signal. 17. A ranging device according to claim 16.

[0127] (Configuration 18) The delay circuit is capable of changing the delay amount of the count start signal. 18. A distance measuring device according to claim 17.

Claims

1. Multiple TDC (Time to Digital Converter) circuits, A clock supply unit that supplies a common clock signal to the plurality of TDC circuits, The system includes a start control unit that outputs a count start signal to instruct the start timing of the count operation to the plurality of TDC circuits, The start control unit outputs the count start signal after a predetermined delay time has elapsed from the timing at which the supply of the common clock signal from the clock supply unit to the plurality of TDC circuits begins. TDC device.

2. The common clock signal supplied by the clock supply unit is a polyphase clock signal composed of multiple clock signals that are out of phase with each other. The TDC apparatus according to claim 1.

3. The start control unit outputs a clock supply start signal to the clock supply unit to instruct the start timing of supplying the common clock signal, and controls the output timing of each signal so that the count start signal is output after a predetermined delay time has elapsed since the output of the clock supply start signal. The TDC apparatus according to claim 1.

4. The TDC device acquires time information indicating the timing at which the photoelectric conversion element detected light, based on a signal output from a pixel having a photoelectric conversion element that detects light emitted from a light source and reflected by an object. The TDC apparatus according to any one of claims 1 to 3.

5. Each of the aforementioned multiple TDC circuits receives signals output from different pixels as stop signals to halt the counting operation. The TDC apparatus according to claim 4.

6. The start control unit has a generation unit that generates the count start signal based on an emission timing signal synchronized with the timing at which the light source emits light. The TDC apparatus according to claim 4.

7. The generation unit is a delay circuit that generates the count start signal by delaying the injection timing signal. The TDC apparatus according to claim 6.

8. The delay circuit is capable of changing the delay amount of the count start signal. The TDC apparatus according to claim 7.

9. Light source and A plurality of pixels having photoelectric conversion elements that detect light emitted from the light source and reflected by an object, The system includes a Time to Digital Converter (TDC) device that acquires time information indicating the timing at which the photoelectric conversion element of each pixel detected light, based on the signals output from the plurality of pixels, The TDC device is Multiple TDC circuits corresponding to the multiple pixels, A clock supply unit that supplies a common clock signal to the plurality of TDC circuits, The system includes a start control unit that outputs a count start signal to instruct the start timing of the count operation to the plurality of TDC circuits, The start control unit outputs the count start signal after a predetermined delay time has elapsed from the timing at which the supply of the common clock signal from the clock supply unit to the plurality of TDC circuits begins. Ranging device.

10. The common clock signal supplied by the clock supply unit is a polyphase clock signal composed of multiple clock signals that are out of phase with each other. The distance measuring device according to claim 9.

11. The start control unit outputs a clock supply start signal to the clock supply unit to instruct the start timing of supplying the common clock signal, and controls the output timing of each signal so that the count start signal is output after a predetermined delay time has elapsed since the output of the clock supply start signal. The distance measuring device according to claim 9.

12. Each of the aforementioned multiple TDC circuits receives signals output from different pixels as stop signals to halt the counting operation. The distance measuring device according to claim 9.

13. The aforementioned photoelectric conversion element is an avalanche photodiode. The distance measuring device according to claim 12.

14. The avalanche photodiode is a SPAD operating in Geiger mode. The distance measuring device according to claim 13.

15. The aforementioned photoelectric conversion element is a charge-accumulating type photodiode. The distance measuring device according to claim 12.

16. The start control unit has a generation unit that generates the count start signal based on an emission timing signal synchronized with the timing at which the light source emits light. A distance measuring device according to any one of claims 9 to 15.

17. The generation unit is a delay circuit that generates the count start signal by delaying the injection timing signal. The distance measuring device according to claim 16.

18. The delay circuit is capable of changing the delay amount of the count start signal. The distance measuring device according to claim 17.

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