Light detection device, method for detecting light, and distance measuring sensor

Abstract

The present disclosure relates to a light detection device, a method for detecting light, and a distance measurement sensor. According to the present disclosure, the distance measurement sensor includes: a single photon avalanche diode (SPAD) element, a first constant current source and a second constant current source, a first switch, a second switch, and a gating switch. The SPAD element outputs a signal when receiving light reflected from a measurement object due to light emitted from a light source. The first constant current source and the second constant current source are connected in parallel to the cathode of the SPAD element. The first switch is connected between the SPAD element and the first constant current source. The second switch is connected between the SPAD element and the second constant current source. The gating switch is connected between the SPAD element and the first switch and between the SPAD element and the ground potential.

Description

Technical Field

[0001] The present disclosure relates to a distance measuring sensor. Background Art

[0002] As a distance measurement method for measuring the distance to a measured object using light, a distance measurement method called a direct ToF (time of flight) method is known. In the direct ToF method, light emitted from a light source is reflected by a measurement object, the reflected light is received by a light receiving element, and the distance to the target is measured based on the time from when the light is emitted to when the light is received as reflected light (for example, refer to PTL 1).

[0003] [Citation List]

[0004] [Patent Document]

[0005] [PTL 1]

[0006] JP 2015-117970 A Summary of the invention

[0007] [Technical issues]

[0008] The present disclosure proposes a distance measuring sensor capable of quickly and appropriately performing a gating operation of a SPAD element.

[0009] [Solution to the problem]

[0010] According to the present disclosure, a light detection device is provided. The light detection device includes: an avalanche photodiode, wherein an electrode of the avalanche photodiode is coupled to a first node; a first switch coupled to the first node and coupled to a first potential line via a first current source; a second switch coupled to the first node and coupled to the first potential line via a second current source; and a delay circuit coupled to the first switch and the second switch.

[0011] [Advantageous Effects of the Invention]

[0012] According to the present disclosure, the gating operation of the SPAD element can be performed quickly and appropriately.It should be noted that the effects described here do not necessarily have to be limited, and may be any effect described in the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram schematically illustrating distance measurement by a direct ToF method applied to each embodiment of the present disclosure.

[0014] Figure 2 is a diagram showing a histogram based on an example of time when light is received by a light receiving unit applied to each embodiment of the present disclosure.

[0015] Figure 3 is a block diagram showing a configuration of an example of an electronic device using a distance measuring apparatus according to an embodiment.

[0016] Figure 4 is a block diagram showing the configuration of an example of a distance measurement device applied to the embodiment in more detail.

[0017] Figure 5 is a block diagram showing a configuration example of a distance measurement sensor according to each embodiment of the present disclosure.

[0018] Figure 6 is a schematic diagram illustrating an example of a configuration of a device applied to a light receiving unit according to each embodiment of the present disclosure.

[0019] Figure 7 is a circuit diagram showing a configuration example of a pulse output unit according to the first embodiment of the present disclosure.

[0020] Figure 8 is a timing chart showing an operation example of the pulse output unit according to the first embodiment of the present disclosure.

[0021] Fig. 9 : is a circuit diagram showing a configuration example of a delay circuit and a pulse generating circuit according to the first embodiment of the present disclosure.

[0022] Fig.10 is a circuit diagram showing another configuration example of the delay circuit and the pulse generating circuit according to the first embodiment of the present disclosure.

[0023] Fig.11 is a circuit diagram showing a configuration example of a pulse output unit according to a second embodiment of the present disclosure.

[0024] Fig.12 is a timing chart showing an operation example of the pulse output unit according to the second embodiment of the present disclosure.

[0025] Fig.13 is a circuit diagram showing a configuration example of a pulse output unit according to a modification of the first embodiment of the present disclosure.

[0026] Fig.14 is a timing chart showing an operation example of the pulse output unit according to the modification of the first embodiment of the present disclosure.

[0027] Fig.15 is a circuit diagram showing another configuration example of a pulse output unit according to a modification of the first embodiment of the present disclosure.

[0028] Fig.16is a timing chart showing another operation example of the pulse output unit according to the modification of the first embodiment of the present disclosure.

[0029] Fig.17 is a circuit diagram showing a configuration example of a pulse output unit according to a modification of the second embodiment of the present disclosure.

[0030] Fig.18 is a timing chart showing an operation example of the pulse output unit according to the modification of the second embodiment of the present disclosure.

[0031] Fig.19 is a circuit diagram showing another configuration example of a pulse output unit according to a modification of the second embodiment of the present disclosure.

[0032] Fig. 20 is a timing chart showing another operation example of the pulse output unit according to the modification of the second embodiment of the present disclosure.

[0033] Fig.21 is a block diagram showing an example of a schematic configuration of a vehicle control system.

[0034] Fig. 22 2 is a diagram showing an example of installation positions of the vehicle exterior information detection unit and the imaging unit. DETAILED DESCRIPTION

[0035] Hereinafter, each embodiment of the present disclosure will be described in detail based on the accompanying drawings. In the following embodiments, the same parts will be represented by the same reference numerals without redundant description.

[0036] As a distance measurement method that uses light to measure the distance to a measured object, a distance measurement method called a direct ToF method is known. In the direct ToF method, light emitted from a light source is reflected by a measured object, the reflected light is received by a light receiving element, and the distance to the target is measured based on the time from when the light is emitted to when the light is received as reflected light.

[0037] In the distance measurement method, a light receiving element including a single photon avalanche photodiode (SPAD) element is used as a light receiving unit. In the SPAD element, there is a predetermined dead zone after receiving light and outputting a signal. For this reason, in order to reliably receive reflected light from a measurement object and output a signal, the SPAD element is controlled to be in an invalid state until the light source emits light.

[0038] Then, a process called a gating operation of switching the SPAD element from an inactive state to an active state is performed in the distance measuring sensor in synchronization with the light emitting operation of the light source.

[0039] On the other hand, the light emitted from the light source may be reflected by the housing of the distance measuring sensor, etc. and may return as stray light earlier than the reflected light from the measuring object. Further, due to the stray light, the above-mentioned gate operation may not be properly performed.

[0040] This is because when stray light is incident on the SPAD element, the stray light is accumulated as electrons, and thus the SPAD element may react unintentionally during a gating operation due to the accumulated electrons.

[0041] In order to improve the problem caused by the accumulated electrons, it is effective to perform the gating operation for a relatively long time. Therefore, since the gating operation can be performed while eliminating the accumulated electrons generated by stray light, it is possible to suppress the SPAD element from reacting unintentionally due to the accumulated electrons.

[0042] However, because the gating operation takes a long time, the time required for the SPAD element to switch from the inactive state to the active state also becomes longer. As a result, when a measuring object exists near the distance measuring sensor, the SPAD element cannot be switched to the active state before the reflected light from the measuring object reaches the distance measuring sensor. Therefore, it becomes difficult to measure the distance of the measuring object near the distance measuring sensor.

[0043] Therefore, it is desirable to realize a distance measuring sensor that can overcome the above-mentioned problems and quickly and appropriately perform a gating operation of a SPAD element.

[0044] <Distance measurement method>

[0045] The present disclosure relates to a technology for performing distance measurement using light. Therefore, in order to facilitate understanding of each embodiment of the present disclosure, reference will be made to Figure 1 and Figure 2 A distance measurement method applied to each embodiment is described.

[0046] Figure 1 is a diagram schematically illustrating distance measurement by a direct ToF method applied to each embodiment of the present disclosure. In each embodiment, the direct ToF method is applied as a distance measurement method.

[0047] The direct ToF method is a method of receiving reflected light L2 obtained by reflecting emission light L1 from the light source unit 2 by the measuring object X by the light receiving unit 3 and performing distance measurement based on the time difference between emission and reception timings of the light.

[0048] The distance measuring sensor 1 includes a light source unit 2 and a light receiving unit 3. The light source unit 2 has a light source 4 (refer to Figure 5)(i.e., for example, a laser diode) and is driven to emit a laser beam in a pulsed manner.

[0049] The light L1 emitted from the light source 2 is reflected by the measurement object X and received as the reflected light L2 by the light receiving unit 3. The light receiving unit 3 includes a pixel array unit 6 that converts light into an electrical signal through photoelectric conversion (see Figure 5 ) and outputs a signal according to the received light.

[0050] Here, the time when the light source 2 emits light (light emission time) is defined as time t0, and the time when the light receiving unit 3 receives the reflected light L2 obtained by the measurement object X reflecting the emitted light L1 from the light source unit 2 (light reception time) is defined as time t1.

[0051] If a constant c is defined as the speed of light (2.9979×10 8 [m / s]), the distance D between the distance measurement sensor 1 and the measurement object X is calculated by the following mathematical formula (1).

[0052] D = (c / 2) × (t1 - t0)...(1)

[0053] The distance measurement sensor 1 can repeatedly execute the above process multiple times. Further, the light receiving unit 3 may have a plurality of SPAD elements 6a (see Figure 6 ) and calculate the distance D based on each light reception time when each SPAD element 6a receives the reflected light L2.

[0054] The distance measurement sensor 1 divides the time t from the light emission time t0 to the light reception time when the light is received by the light receiving unit 3 based on a category (binary (bin)), and generates a histogram. m (hereinafter also referred to as "light reception time t m ").

[0055] Figure 2 is a diagram showing an example of a histogram based on the time when the light is received by the light receiving unit 3 applied to each embodiment of the present disclosure. In Figure 2 , the horizontal axis represents the binary and the vertical axis represents the frequency of each binary. The binary is obtained by dividing the light reception time t m for each predetermined unit time d.

[0056] Specifically, binary #0 satisfies 0 ≤ t m < d, binary #1 satisfies d ≤ t m < 2×d, binary #2 satisfies 2×d ≤ t m < 3×d,..., binary #(N - 2) satisfies (N - 2)×d ≤ t m<(N-1)×d. When the exposure time of the light receiving unit 3 is defined as time t ep When t ep =N×d.

[0057] The distance measurement sensor 1 obtains the light receiving time t based on the binary pair m The number of times is counted, the frequency 200 of each bin is obtained, and a histogram is generated. Here, the light receiving unit 3 also receives light other than the reflected light L2 of the light L1 emitted from the light source unit 2.

[0058] For example, as an example of light other than the target reflected light L2, there is ambient light around the distance measuring sensor 1. Ambient light is light randomly incident on the light receiving unit 3, and an ambient light component 201 due to ambient light in the histogram becomes noise relative to the target reflected light L2.

[0059] On the other hand, the target reflected light L2 is light received according to a specific distance and appears in the histogram as an active light component 202. The bin corresponding to the peak frequency in the active light component 202 becomes a bin corresponding to the distance D of the measuring object X.

[0060] The distance measuring sensor 1 obtains a representative time of a binary system (eg, a time at the center of a binary system) as the above time t1, thereby calculating the distance D from the measuring object X according to the above mathematical formula (1). As described above, by using a plurality of light reception results, appropriate distance measurement can be performed for random noise.

[0061] <Configuration of electronic devices>

[0062] Figure 3 is a block diagram showing a configuration of an example of an electronic device using a distance measuring apparatus according to each embodiment. Figure 3 In the embodiment, the electronic device 56 includes a distance measuring device 51, a light source unit 52, a storage unit 53, a control unit 54 and an optical system 55.

[0063] For example, the light source unit 52 corresponding to the above-mentioned light source unit 2 is a laser diode and is driven to emit a laser beam in a pulsed manner. As the light source unit 52, a vertical cavity surface emitting laser (VCSEL) that emits a laser beam can be applied as a surface light source. However, the present disclosure is not limited to this, and a configuration can be applied as the light source unit 52, wherein an array in which laser diodes are arranged in a row is used to scan a laser beam emitted from a laser diode in a direction perpendicular to the row. Further, a configuration can be applied, wherein a laser beam emitted from a laser diode is scanned in horizontal and vertical directions using a laser diode as a single light source.

[0064] The distance measuring device 51 includes a plurality of light receiving elements corresponding to the above-mentioned light receiving unit 3. For example, the plurality of light receiving elements are arranged in a two-dimensional lattice form to form a light receiving surface. The optical system 55 guides light incident from the outside to the light receiving surface included in the distance measuring device 51.

[0065] The control unit 54 controls the overall operation of the electronic device 56. For example, the control unit 54 supplies a light emission trigger as a trigger for causing the light source unit 52 to emit light to the distance measuring device 51. The distance measuring device 51 causes the light source unit 52 to emit light at a timing based on the light emission trigger, and stores a time t0 indicating the light emission timing. Further, for example, the control unit 54 performs setting of a mode at a distance measurement time relative to the distance measuring device 51 according to an instruction from the outside.

[0066] The distance measuring device 51 acquires time information indicating the time when light is received by the light receiving surface (light receiving time t m ) is counted, the frequency of each binary is calculated, and the above-mentioned histogram is generated. Further, the distance measurement device 51 calculates the distance D to the measurement object based on the generated histogram. Information indicating the calculated distance D is stored in the storage unit 53.

[0067] Figure 4 is a block diagram showing the configuration of an example of the distance measurement device 51 applied to each embodiment in more detail. Figure 4 In the embodiment, the distance measuring device 51 includes a pixel array unit 100, a distance measurement processing unit 101, a pixel control unit 102, an overall control unit 103, a clock generating unit 104, a light emission timing control unit 105, and an interface (I / F) 106. For example, the pixel array unit 100, the distance measurement processing unit 101, the pixel control unit 102, the overall control unit 103, the clock generating unit 104, the light emission timing control unit 105, and the interface (I / F) 106 are arranged on one semiconductor chip.

[0068] exist Figure 4 In the embodiment of the present invention, for example, the overall control unit 103 controls the overall operation of the distance measuring device 51 according to a program installed in advance. Further, the overall control unit 103 is also capable of performing control according to an external control signal supplied from the outside. The clock generation unit 104 generates one or more clock signals used in the distance measuring device 51 based on a reference clock signal supplied from the outside. The light emission timing control unit 105 generates a light emission control signal indicating the light emission timing according to a light emission trigger signal supplied from the outside. The light emission control signal is supplied to the light source unit 52 and to the distance measurement processing unit 101.

[0069] The pixel array unit 100 includes a plurality of pixel circuits 60 arranged in a two-dimensional lattice, each pixel circuit 60 including a light receiving element. The operation of each pixel circuit 60 is controlled by the pixel control unit 102 according to the instruction of the overall control unit 103. For example, for a block of (p×q) pixel circuits 60 including p pixel circuits in the row direction and q pixel circuits in the column direction, the pixel control unit 102 can control the reading of pixel signals from each pixel circuit 60 of each block. Further, by scanning each pixel circuit 60 in units of blocks in the row direction and further scanning each pixel circuit 60 in the column direction, the pixel control unit 102 can read pixel signals from each pixel circuit 60. However, the present disclosure is not limited thereto, and the pixel control unit 102 can independently control each pixel circuit 60. Further, the pixel control unit 102 can use a predetermined area of ​​the pixel array unit 100 as a target area to set the pixel circuit 60 included in the target area as a target pixel circuit 60 from which the pixel signal is read. Further, the pixel control unit 102 can collectively scan a plurality of rows (a plurality of lines), further scan them in the column direction, and read a pixel signal from each pixel circuit 60 .

[0070] The pixel signal read from each pixel circuit 60 is supplied to the distance measurement processing unit 101. The distance measurement processing unit 101 includes a conversion unit 110, a generation unit 111, and a signal processing unit 112.

[0071] The pixel signal read from each pixel circuit 60 and output from the pixel array unit 100 is supplied to the conversion unit 110. Here, the pixel signal is asynchronously read from each pixel circuit 60 and supplied to the conversion unit 110. That is, the pixel signal is read from the light receiving element according to the timing of receiving light in each pixel circuit 60 and the pixel signal is output.

[0072] The conversion unit 110 converts the pixel signal supplied from the pixel array unit 100 into digital information. That is, the pixel signal supplied from the pixel array unit 100 is output according to the time when the light receiving element included in the pixel circuit 60 corresponding to the pixel signal receives light. The conversion unit 110 converts the supplied pixel signal into time information indicating the time.

[0073] The generation unit 111 generates a histogram based on the time information into which the pixel signal is converted by the conversion unit 110. Here, the generation unit 111 calculates the time information based on the unit time d set by the setting unit and generates a histogram.

[0074] For example, the signal processing unit 112 performs predetermined algorithm processing and calculates distance information based on the data of the histogram generated by the generating unit 111. For example, the signal processing unit 112 creates a curve approximation of the histogram based on the data of the histogram generated by the generating unit 111. The signal processing unit 112 can detect a peak of the curve approximation of the histogram, and can calculate the distance D based on the detected peak.

[0075] When performing curve approximation of the histogram, the signal processing unit 112 can perform filter processing on the curve approximated by the histogram. For example, the signal processing unit 112 can suppress noise components by performing low-pass filter processing on the curve approximated by the histogram.

[0076] The distance information obtained by the signal processing unit 112 is supplied to the interface 106. The interface 106 outputs the distance information supplied from the signal processing unit 112 to the outside as output data. As the interface 106, for example, a Mobile Industry Processor Interface (MIPI) can be applied.

[0077] In the above description, the distance information obtained by the signal processing unit 112 is output to the outside via the interface 106, but it is not limited to this example. That is, such a configuration can be used, that is, in which the histogram data as the data of the histogram generated by the generating unit 111 is output to the outside from the interface 106. In this case, the distance measurement condition information set by the setting unit can ignore the information indicating the filter coefficient. For example, the histogram data output from the interface 106 is supplied to an external information processing device and approximation processing is performed.

[0078] <Configuration of distance measuring sensor>

[0079] Then, reference will be made to Figure 5 and Figure 6 The configuration of the distance measuring sensor 1 according to each embodiment is described. Figure 5 1 is a block diagram showing a configuration example of the distance measurement sensor 1 according to each embodiment of the present disclosure. As described above, the distance measurement sensor 1 includes the light source unit 2 , the light receiving unit 3 , and the housing 9 .

[0080] The light source unit 2 has a light source 4 and a light source driving unit 5. For example, the light source 4 is composed of a laser diode such as a vertical cavity surface emitting laser (VCSEL). The light source 4 is not limited to the VCSEL, and a laser diode array in which laser diodes are arranged in a row or the like can be used as the light source 4.

[0081] The light source driving unit 5 drives the light source 4. For example, the light source driving unit 5 drives the light source 4 based on the light emission control signal from the control unit 8 of the light receiving unit 3, so that emission light L1 having a predetermined timing and pulse width is emitted from the light source 4.

[0082] For example, the light source driving unit 5 can drive the light source 4 so that the laser beam is scanned in a direction perpendicular to the row from the light source 4 having laser diodes arranged in a row.

[0083] The light receiving unit 3 has a pixel array unit 6 , a pulse output unit 7 , and a control unit 8 .

[0084] The pixel array unit 6 has a plurality of SPAD elements 6a arranged in a two-dimensional lattice (see Figure 6 ). In the SPAD element 6a, by applying a large reverse bias voltage that causes avalanche multiplication to the cathode, avalanche multiplication occurs inside due to electrons generated by the incidence of one photon.

[0085] That is, the SPAD element 6a has a characteristic that a large current flows in response to the incidence of one photon. Furthermore, in the SPAD element 6a, the incidence of one photon included in the reflected light L2 can be detected with high sensitivity by using the above-mentioned characteristic.

[0086] The operation of the plurality of SPAD elements 6a in the pixel array unit 6 is controlled by the control unit 8. For example, for each block of (n×m) SPAD elements 6a including n pixels in the row direction and m pixels in the column direction, the control unit 8 can control the reading of signals from each SPAD element 6a.

[0087] Further, the control unit 8 can read a signal from each SPAD element 6 a by scanning each SPAD element 6 a in units of blocks in the row direction and scanning each SPAD element 6 a in the column direction for each row.

[0088] In each embodiment, the control unit 8 can read a signal independently from each SPAD element 6 a The signal generated by the SPAD element 6 a of the pixel array unit 6 is supplied to the pulse output unit 7 .

[0089] The pulse output unit 7 outputs a predetermined pulse signal as a digital signal according to the signal generated by the SPAD element 6a to the control unit 8. The details of the pulse output unit 7 will be described later.

[0090] For example, the control unit 8 controls the overall operation of the distance measuring sensor 1 according to a program installed in advance. For example, the control unit 8 controls the light emission timing of the light source 4 by controlling the light source driving unit 5.

[0091] Further, the control unit 8 generates a pulse signal based on the pulse signal output from the pulse output unit 7. Figure 2 Further, the control unit 8 performs predetermined arithmetic processing based on the data for which the histogram has been generated and calculates the distance D to the measuring object X.

[0092] The housing 9 accommodates the light source unit 2 and the light receiving unit 3. Figure 3 As shown in FIG. 1 , if the emission light L1 is reflected by the housing 9, it is incident on the pixel array unit 6 of the light receiving unit 3 as stray light L3. Then, the stray light L3 is incident on the pixel array unit 6 earlier than the reflected light L2 from the measuring object X.

[0093] Figure 6 is a schematic diagram showing an example of a configuration of a device applied to the light receiving unit 3 according to each embodiment of the present disclosure. Figure 6 In FIG. 3 , the light receiving unit 3 is configured by laminating a light receiving chip 3 a and a logic chip 3 b each formed of a semiconductor chip. For ease of understanding, Figure 6 The light receiving chip 3 a and the logic chip 3 b are shown in an independent state.

[0094] In the light receiving chip 3a, the SPAD elements 6a are arranged in a two-dimensional lattice form in the area of ​​the pixel array unit 6. The logic chip 3b is provided with a pulse output unit 7 and a control unit 8. The configuration of the light receiving chip 3a and the logic chip 3b is not limited to Figure 6 Instances in .

[0095] <Configuration and Operation of Pulse Output Unit (First Embodiment)>

[0096] Then, reference will be made to Figures 7 to 10 The configuration and operation of the pulse output unit 7 according to the first embodiment are described. Figure 7 : is a circuit diagram showing a configuration example of the pulse output unit 7 according to the first embodiment of the present disclosure.

[0097] like Figure 7 As shown in FIG. 1 , the pulse output unit 7 includes a first constant current source 11 , a second constant current source 12 , a first switch 13 , a second switch 14 , a gate switch 15 and an inverter 16 .

[0098] The first constant current source 11 is connected between a predetermined power supply voltage Vdd and the first switch 13, and causes a current having a predetermined current value I1 to flow to the first switch 13. The second constant current source 12 is connected between the power supply voltage Vdd and the second switch 14, and causes a current having a predetermined current value I2 to flow to the second switch 14.

[0099] The first switch 13 is connected between the first constant current source 11 and the signal line 17, and the second switch 14 is connected between the second constant current source 12 and the signal line 17. The signal line 17 connects the cathode (ie, diode) of the SPAD element 6a and the input terminal of the inverter 16 via the connection unit 6b of the pixel array unit 6.

[0100] That is, in the pulse output unit 7 according to the first embodiment, the first constant current source 11 and the second constant current source 12 are connected in parallel to the cathode of the SPAD element 6 a via the first switch 13 and the second switch 14 , respectively.

[0101] Then, the first constant current source 11 and the second constant current source 12 cause currents of current value I1 and current value I2 to flow to the cathode of the SPAD element 6a, respectively. The anode of the SPAD element 6a is connected to a predetermined voltage Va, and the output terminal of the inverter 16 is connected to the control unit 8 (refer to Figure 5 ).

[0102] Here, the control unit 8 controls the amount of current flowing to the cathode of the SPAD element 6a by controlling the first switch 13 and the second switch 14. The first switch 13 and the second switch 14 are switched between an on state (conductive state) and an off state (power-off state) based on an enable signal output from the control unit 8.

[0103] Specifically, the enable signal is directly input to the first switch 13. That is, when the enable signal is switched from off to on, the first switch 13 is immediately switched from off to on.

[0104] Further, the enable signal is input to the second switch 14 via the delay circuit 18 and the pulse generation circuit 19. That is, when the enable signal is switched from OFF to ON, the second switch 14 is switched from OFF to ON within a predetermined period after a predetermined time has elapsed.

[0105] The gate switch 15 is connected between the signal line 17 and the ground potential. That is, the gate switch 15 is connected between the SPAD element 6a and the first switch 13 and between the SPAD element 6a and the ground potential.

[0106] The gate switch 15 switches between an on state and an off state based on an enable signal output from the control unit 8. Specifically, the enable signal is input to the gate switch 15 via the inverter 20.

[0107] That is, when the enable signal is switched from off to on, the gate switch 15 is immediately switched from on to off. Therefore, the control unit 8 can perform the gate operation of the SPAD element 6a by controlling the gate switch 15.

[0108] For example, the control unit 8 can ground the cathode of the SPAD element 6a by turning on the gate switch 15. Therefore, the reverse bias voltage is not applied to the SPAD element 6a, so that the control unit 8 can put the SPAD element 6a into an inactive state.

[0109] On the other hand, the control unit 8 can cause the cathode of the SPAD element 6a to enter a floating state by turning off the gate switch 15. Therefore, a reverse bias voltage can be applied to the SPAD element 6a, so that the control unit 8 can cause the SPAD element 6a to enter an active state.

[0110] Next, remove the reference Figure 7 Other Figure 8 The operation of the pulse output unit 7 according to the first embodiment is described. Figure 8 : is a timing chart showing an operation example of the pulse output unit 7 according to the first embodiment of the present disclosure.

[0111] exist Figure 8 In the example of , since the enable signal is kept in the off state in the initial state, the gate switch 15 is kept in the on state, and the SPAD element 6a enters the inactive state.

[0112] Then, the control unit 8 controls the light source driving unit 5 so that the light source 4 emits light in a pulsed manner at time T1. Therefore, the stray light L3 is incident on the SPAD element 6a at time T2. Figure 8 As shown in FIG. 6 , the stray light L3 is incident on the SPAD element 6 a earlier than the reflected light L2 from the measuring object X.

[0113] The stray light L3 is incident on the SPAD element 6a, causing electrons to be accumulated in the SPAD element 6a in an inactive state.

[0114] Next, control unit 8 switches the enable signal from OFF to ON at time T3 when a predetermined time elapses from time T1 when light is emitted from light source 4. As a result, gate switch 15 switches from ON to OFF at time T3, and the cathode of SPAD element 6a enters a floating state.

[0115] Further, the first switch 13 is switched from off to on at time T3. Therefore, a current having a current value I1 is supplied from the first constant current source 11 to the cathode of the SPAD element 6a, so that the cathode voltage of the SPAD element 6a gradually increases from 0 (V).

[0116] As described above, in the first embodiment, after the gate operation is started, the cathode of the SPAD element 6a is boosted by using one constant current source (first constant current source 11) among a plurality of constant current sources connected in parallel to the cathode of the SPAD element 6a.

[0117] Therefore, the speed of boosting the cathode of the SPAD element 6a can be limited. Therefore, according to the first embodiment, since the gating operation can be performed while eliminating the electrons accumulated in the SPAD element 6a, it is possible to suppress the SPAD element 6a from reacting unintentionally due to the accumulated electrons.

[0118] Then, the enable signal transmitted from the control unit 8 is transmitted to the second switch 14 via the above-mentioned delay circuit 18 and pulse generation circuit 19. Therefore, the second switch 14 is switched from off to on at time T4 when a predetermined delay time has elapsed from time T3.

[0119] Therefore, a current having a current value I1+I2 is supplied from the first constant current source 11 and the second constant current source 12 to the cathode of the SPAD element 6a, so that the cathode voltage of the SPAD element 6a increases rapidly from the voltage V1 at the time point of time T4.

[0120] Then, the voltage reaches a predetermined voltage V2 at time T5, and the second switch 14 switches from on to off at time T5. Thereafter, a current having a current value I1 is supplied from the first constant current source 11 to the cathode of the SPAD element 6a, so that the cathode voltage of the SPAD element 6a is kept at voltage V2.

[0121] As described above, in the first embodiment, the electrons accumulated in the SPAD element 6a can be sufficiently eliminated in the period until time T4. In other words, in the first embodiment, the time in which the electrons accumulated in the SPAD element 6a can be sufficiently eliminated is set as the delay time set by the delay circuit 18.

[0122] Therefore, even if the cathode voltage of the SPAD element 6 a increases rapidly at time T4 , it is possible to suppress the SPAD element 6 a from reacting unintentionally.

[0123] Furthermore, in the first embodiment, the time until the cathode voltage of the SPAD element 6a reaches the voltage V2 can be reduced by using any of the plurality of constant current sources from time T4 to boost the cathode of the SPAD element 6a. That is, in the first embodiment, the gating operation can be completed in a short time.

[0124] Therefore, according to the first embodiment, a plurality of constant current sources are connected in parallel to the cathode of the SPAD element 6 a , thereby enabling the gating operation of the SPAD element 6 a to be performed quickly and appropriately.

[0125] Further, in the first embodiment, the current value I1 of the first constant current source 11 can be smaller than the current value I2 of the second constant current source 12. Therefore, the voltage rise speed of the cathode of the SPAD element 6a can be further limited until the time T4 when the second switch 14 is turned on. Further, from the time T4 when the second switch 14 is turned on, the cathode voltage of the SPAD element 6a can increase more rapidly.

[0126] Therefore, according to the first embodiment, the gating operation of the SPAD element 6 a can be performed more quickly and appropriately.

[0127] Further, in the first embodiment, the control unit 8 may keep the first switch 13 in the on state during a period until the second switch 14 switches from off to on (ie, a period until time T4).

[0128] As a result, until time T4, the cathode voltage of the SPAD element 6a can be continuously increased, so that the time until the cathode voltage of the SPAD element 6a increases to the voltage V2 can be reduced. Therefore, according to the first embodiment, the gating operation of the SPAD element 6a can be performed more quickly.

[0129] The description of the timing chart will be continued after time T5. At time T5, the reverse bias voltage V2 is applied to the cathode of the SPAD element 6a until a state called Geiger mode occurs, that is, just before avalanche multiplication occurs.

[0130] That is, at time T5, the signal output from the cathode of the SPAD element 6a has a voltage V2. Then, because the voltage V2 equal to or greater than the predetermined threshold voltage is input as a signal to the inverter 16, the inverter 16 outputs a low-level signal S1 (reference Figure 7 ).

[0131] Therefore, if one photon generated by the reflected light L2 is incident on the SPAD element 6 a to which the voltage V2 is applied at time T6 , the SPAD element 6 a breaks down and current flows to the first constant current source 11 .

[0132] As a result, the cathode voltage of the SPAD element 6 a increases rapidly from the voltage V2 , and when the cathode voltage becomes smaller than the threshold voltage, the inverter 16 outputs a high-level signal S1 .

[0133] Therefore, since avalanche multiplication in the SPAD element 6a stops at time T7, the cathode voltage of the SPAD element 6a stops decreasing at 0 (V). Further, when the SPAD element 6a is recharged by the first constant current source 11 (so-called quenching operation), the cathode voltage of the SPAD element 6a increases.

[0134] Then, if the cathode voltage of the SPAD element 6a becomes equal to or greater than the threshold voltage, the inverter 16 outputs a low-level signal S1.

[0135] As described above, if reflected light L2 is incident on SPAD element 6a, inverter 16 outputs pulse signal S1 generated from reflected light L2 to control unit 8. Finally, the cathode voltage of SPAD element 6a returns to predetermined voltage V2 at time T8, and SPAD element 6a returns to the initial state.

[0136] Fig. 9 1 is a circuit diagram showing a configuration example of the delay circuit 18 and the pulse generating circuit 19 according to the first embodiment of the present disclosure. Fig. 9 As shown in FIG. 1 , the delay circuit 18 has inverters 18 a and 18 b , a CMOS circuit 18 c , a constant current source 18 d , a NAND circuit 18 e , and a capacitor 18 f .

[0137] An input terminal 18i of the delay circuit 18 is connected to an input terminal of the inverter 18a. An output terminal of the inverter 18a is connected to an input terminal of the CMOS circuit 18c and an input terminal of the inverter 18b.

[0138] A predetermined current is supplied to the CMOS circuit 18c through the constant current source 18d. An output terminal of the CMOS circuit 18c is connected to one input terminal of the NAND circuit 18e.

[0139] The other input terminal of the NAND circuit 18e is connected to the output terminal of the inverter 18b. The output terminal of the NAND circuit 18e is connected to the output terminal 18o of the delay circuit 18. The capacitor 18f is connected between the output terminal of the CMOS circuit 18c and the ground potential.

[0140] In the above circuit configuration, the delay time of the delay circuit 18 can be controlled by appropriately adjusting the current value of the constant current source 18 d and the capacitance value of the capacitor 18 f.

[0141] The pulse generating circuit 19 has a CMOS circuit 19a, a constant current source 19b, an XOR circuit 19c, and a capacitor 19d. An input terminal 19i of the pulse generating circuit 19 is connected to an input terminal of the CMOS circuit 19a and to one input terminal of the XOR circuit 19c.

[0142] A predetermined current is supplied to the CMOS circuit 19a by the constant current source 19b. The output terminal of the CMOS circuit 19a is connected to the other input terminal of the exclusive OR circuit 19c.

[0143] The output terminal of the exclusive OR circuit 19c is connected to the output terminal 19o of the pulse generating circuit 19. The capacitor 19d is connected between the output terminal of the CMOS circuit 19a and the ground potential.

[0144] In the above circuit configuration, the length of the pulse output from the pulse generating circuit 19 can be controlled by appropriately adjusting the current value of the constant current source 19 b and the capacitance value of the capacitor 19 d .

[0145] The circuit configurations of the delay circuit 18 and the pulse generating circuit 19 are not limited to Fig. 9 Instances in . Fig.10 is a circuit diagram showing another configuration example of the delay circuit 18 and the pulse generating circuit 19 according to the first embodiment of the present disclosure.

[0146] exist Fig.10 In the example of FIG. 1 , the delay circuit 18 has inverters 18 a, 18 b, and 18 h, a NAND circuit 18 e, and an inverter group 18 g.

[0147] An input terminal 18i of the delay circuit 18 is connected to an input terminal of the inverter 18a. An output terminal of the inverter 18a is connected to an input terminal of an inverter group 18g and an input terminal of the inverter 18b.

[0148] The inverter group 18g has an even number (four in the figure) of inverters connected in series. The output terminal of the inverter group 18g is connected to the input terminal of the inverter 18h. The output terminal of the inverter 18h is connected to one input terminal of the NAND circuit 18e.

[0149] The other input terminal of the NAND circuit 18 e is connected to the output terminal of the inverter 18 b , and the output terminal of the NAND circuit 18 e is connected to the output terminal 18 o of the delay circuit 18 .

[0150] In the above-described circuit configuration, the delay time of the delay circuit 18 can be controlled by appropriately adjusting the number of inverter groups 18g.

[0151] The pulse generating circuit 19 has an exclusive OR circuit 19c, an inverter group 19e, and an inverter 19f. An input terminal 19i of the pulse generating circuit 19 is connected to an input terminal of the inverter group 19e and to one input terminal of the exclusive OR circuit 19c.

[0152] Inverter group 19e has an even number (four in the figure) of inverters connected in series. The output terminal of inverter group 19e is connected to the input terminal of inverter 19f. The output terminal of inverter 19f is connected to the other input terminal of XOR circuit 19c. The output terminal of XOR circuit 19c is connected to output terminal 19o of pulse generating circuit 19.

[0153] In the above-described circuit configuration, the length of the pulse output from the pulse generating circuit 19 can be controlled by appropriately adjusting the number of inverter groups 19e.

[0154] <Second Embodiment>

[0155] Then, reference will be made to Fig.11 and Fig.12 The configuration and operation of the pulse output unit 7 according to the second embodiment are described. Fig.11 : is a circuit diagram showing a configuration example of the pulse output unit 7 according to the second embodiment of the present disclosure.

[0156] like Fig.11 As shown in FIG. 1 , the pulse output unit 7 includes a first constant current source 11 , a second constant current source 12 , a first switch 13 , a second switch 14 , a gate switch 15 and an inverter 16 .

[0157] The first constant current source 11 is connected between the first switch 13 and the ground potential, and causes a current having a predetermined current value I1 to flow to the ground potential. The second constant current source 12 is connected between the second switch 14 and the ground potential, and causes a current having a predetermined current value I2 to flow to the ground potential.

[0158] The first switch 13 is connected between the first constant current source 11 and the signal line 17, and the second switch 14 is connected between the second constant current source 12 and the signal line 17. The signal line 17 connects the anode of the SPAD element 6a and the input terminal of the inverter 16 via the connection unit 6b of the pixel array unit 6.

[0159] That is, in the pulse output unit 7 according to the second embodiment, the first constant current source 11 and the second constant current source 12 are connected in parallel to the anode of the SPAD element 6 a via the first switch 13 and the second switch 14 , respectively.

[0160] Therefore, the first constant current source 11 and the second constant current source 12 cause currents of current values ​​I1 and I2 to flow from the anode of the SPAD element 6a to the ground potential, respectively. The cathode of the SPAD element 6a is connected to a predetermined voltage Vc, and the output terminal of the inverter 16 is connected to the control unit 8 (reference Figure 5 ).

[0161] Here, the control unit 8 controls the amount of current flowing from the anode of the SPAD element 6a by controlling the first switch 13 and the second switch 14. The first switch 13 and the second switch 14 are switched between an on state and an off state based on an enable signal output from the control unit 8.

[0162] Specifically, the enable signal is directly input to the first switch 13. That is, when the enable signal is switched from off to on, the first switch 13 is immediately switched from off to on.

[0163] Further, the enable signal is input to the second switch 14 via the delay circuit 18 and the pulse generating circuit 19. That is, when the enable signal is switched from off to on, the second switch 14 is switched from off to on within a predetermined period of time after a predetermined time has elapsed. The same circuit as the first embodiment can be used for the delay circuit 18 and the pulse generating circuit 19.

[0164] The gate switch 15 is connected between the signal line 17 and the power supply voltage Vdd. That is, the gate switch 15 is connected between the SPAD element 6a and the first switch 13 and between the SPAD element 6a and the power supply voltage Vdd.

[0165] The gate switch 15 switches between an on state and an off state based on an enable signal output from the control unit 8. Specifically, the enable signal is input to the gate switch 15 via the inverter 20.

[0166] That is, when the enable signal is switched from off to on, the gate switch 15 is immediately switched from on to off. Therefore, the control unit 8 can perform the gate operation of the SPAD element 6a by controlling the gate switch 15.

[0167] For example, the control unit 8 can set the voltage of the anode of the SPAD element 6a to the power supply voltage Vdd by turning on the gate off 15. As a result, the reverse bias voltage is not applied to the SPAD element 6a, so that the control unit 8 can put the SPAD element 6a into an inactive state.

[0168] On the other hand, the control unit 8 can bring the anode of the SPAD element 6a into a floating state by closing the gate switch 15. Therefore, a reverse bias voltage can be applied to the SPAD element 6a, so that the control unit 8 can bring the SPAD element 6a into an active state.

[0169] Next, except Fig.11 In addition, reference will be made to Fig.12 The operation of the pulse output unit 7 according to the second embodiment is described. Fig.12 : is a timing chart showing an operation example of the pulse output unit 7 according to the second embodiment of the present disclosure.

[0170] exist Fig.12 In the example of , since the enable signal remains in the off state in the initial state, the gate switch 15 remains in the on state, and the SPAD element 6a enters the inactive state.

[0171] Therefore, the control unit 8 controls the light source driving unit 5 so that the light source 4 emits light in a pulsed manner at time T1. As a result, the stray light L3 is incident on the SPAD element 6a at time T2. The stray light L3 is incident on the SPAD element 6a, so that electrons are accumulated in the SPAD element 6a in the inactive state.

[0172] Next, control unit 8 switches enable signal from OFF to ON at time T3 when a predetermined time has elapsed from time T1 when light is emitted from light source 4. Therefore, gate switch 15 switches from ON to OFF at time T3, thereby bringing the anode of SPAD element 6a into a floating state.

[0173] Further, the first switch 13 is switched from off to on at time T3. Therefore, a current having a current value I1 flows from the anode of the SPAD element 6a through the first constant current source 11, so that the anode voltage of the SPAD element 6a gradually decreases from the power supply voltage Vdd.

[0174] As described above, in the second embodiment, after starting the gate operation, the cathode of the SPAD element 6a is stepped down by using one constant current source (first constant current source 11) among a plurality of constant current sources connected in parallel to the anode of the SPAD element 6a.

[0175] As a result, the voltage drop rate of the anode of the SPAD element 6a can be limited. Therefore, according to the second embodiment, since the gating operation can be performed while eliminating the electrons accumulated in the SPAD element 6a, it is possible to suppress the SPAD element 6a from reacting unintentionally due to the accumulated electrons.

[0176] Then, the enable signal transmitted from the control unit 8 is transmitted to the second switch 14 via the above-mentioned delay circuit 18 and pulse generation circuit 19. As a result, the second switch 14 is switched from off to on at time T4 when a predetermined delay time has elapsed from time T3.

[0177] Therefore, a current having a current value I1+I2 flows from the anode of the SPAD element 6a through the first constant current source 11 and the second constant current source 12, so that the anode voltage of the SPAD element 6a is rapidly reduced from the voltage V4 at the time point of time T4.

[0178] Then, the voltage reaches predetermined voltage V3 at time T5, and second switch 14 switches from on to off at time T5. Thereafter, current having current value I1 flows from the anode of SPAD element 6a through first constant current source 11, thereby keeping the anode voltage of SPAD element 6a at voltage V3.

[0179] As described above, in the second embodiment, similar to the first embodiment, the electrons accumulated in the SPAD element 6a can be sufficiently eliminated in the time period until time T4. In other words, in the second embodiment, the time in which the electrons accumulated in the SPAD element 6a can be sufficiently eliminated is set as the delay time set by the delay circuit 18.

[0180] Therefore, even if the anode voltage of the SPAD element 6 a decreases rapidly from the time T4 , it is possible to suppress the SPAD element 6 a from reacting unintentionally.

[0181] Furthermore, in the second embodiment, the time until the anode voltage of the SPAD element 6a reaches the voltage V3 can be reduced by using any of the plurality of constant current sources to step down the anode voltage of the SPAD element 6a from time T4. That is, in the second embodiment, the gating operation can be completed in a short time.

[0182] Therefore, according to the second embodiment, it is possible to quickly and appropriately perform the gating operation of the SPAD element 6 a by connecting a plurality of constant current sources in parallel to the anode of the SPAD element 6 a .

[0183] Further, in the second embodiment, the current value I1 of the first constant current source 11 may be smaller than the current value I2 of the second constant current source 12. Therefore, the voltage drop speed of the anode of the SPAD element 6a until the time T4 when the second switch 14 is turned on may be further limited. Further, from the time T4 when the second switch 14 is turned on, the anode voltage of the SPAD element 6a may be reduced more quickly.

[0184] Therefore, according to the second embodiment, the gating operation of the SPAD element 6 a can be performed more quickly and appropriately.

[0185] Further, in the second embodiment, the control unit 8 may keep the first switch 13 in the on state during a period until the second switch 14 is switched from off to on (ie, a period until time T4 ).

[0186] As a result, until time T4, the anode voltage of SPAD element 6a can be continuously reduced, thereby enabling reduction of the time until the voltage of the anode of SPAD element 6a is reduced to voltage V3. Therefore, according to the second embodiment, the gating operation of SPAD element 6a can be performed more quickly.

[0187] The description of the timing chart after time T5 will be continued. At time T5, the reverse bias voltage V3 is applied to the anode of the SPAD element 6a until a state called Geiger mode occurs, that is, occurs just before avalanche multiplication.

[0188] That is, at time T5, the signal output from the anode of the SPAD element 6a has a voltage V3. Then, because the voltage V3 less than the predetermined threshold voltage is input as a signal to the inverter 16, the inverter 16 outputs a high-level signal S1 (reference Fig.11 ).

[0189] Then, if one photon generated by the reflected light L2 is incident on the SPAD element 6 a to which the voltage V3 is applied at time T6 , the SPAD element 6 a breaks down and current flows to the first constant current source 11 .

[0190] As a result, the anode voltage of the SPAD element 6 a increases rapidly from the voltage V3 , and when the anode voltage becomes equal to or greater than the threshold voltage, the inverter 16 outputs a low-level signal S1 .

[0191] Then, because avalanche multiplication in the SPAD element 6a stops at time T7, the anode voltage of the SPAD element 6a stops increasing at the power supply voltage Vdd. Further, when current flows through the first constant current source 11 (so-called quenching operation), the anode voltage of the SPAD element 6a decreases.

[0192] Therefore, if the anode voltage of the SPAD element 6 a becomes lower than the threshold voltage, the inverter 16 outputs a high-level signal S1 .

[0193] As described above, if reflected light L2 is incident on SPAD element 6a, inverter 16 outputs pulse signal S1 generated from reflected light L2 to control unit 8. Finally, the anode voltage of SPAD element 6a returns to predetermined voltage V3 at time T8, and SPAD element 6a returns to the initial state.

[0194] <Various deformations>

[0195] Then, reference will be made to Figures 13 to 20 Various modifications of the pulse output unit 7 are described.

[0196] <Variation of First Embodiment>

[0197] Fig.13 : is a circuit diagram showing a configuration example of the pulse output unit 7 according to a modification of the first embodiment of the present disclosure. Fig.13 The examples in Figure 7 The first embodiment shown in FIG. 1 is different in the configuration of a path for transmitting an enable signal to the first switch 13 and the second switch 14 .

[0198] Specifically, the enable signal is input to the first switch 13 via the pulse generation circuit 19 , and the enable signal is input to the first switch 13 via the delay circuit 18A.

[0199] That is, when the enable signal is switched from off to on, the first switch 13 is switched from off to on within a predetermined period of time, and the first switch 13 is switched from off to on after a predetermined time has elapsed.

[0200] Further, the enable signal is input to the second switch 14 via the pulse generation circuit 19 and the delay circuit 18B. That is, when the enable signal is switched from OFF to ON, the second switch 14 is switched from OFF to ON within a predetermined period after a predetermined time has elapsed.

[0201] Next, except Fig.13 In addition, reference will be made to Fig.14 The operation of the pulse output unit 7 according to the modification of the first embodiment is described. Fig.14 : is a timing chart showing an operation example of the pulse output unit 7 according to the modification of the first embodiment of the present disclosure.

[0202] exist Fig.14 In the example of , since the enable signal remains in the off state in the initial state, the gate switch 15 remains in the on state, and the SPAD element 6a enters the inactive state.

[0203] Then, the control unit 8 controls the light source driving unit 5 so that the light source 4 emits light in a pulsed manner at time T11. As a result, the stray light L3 is incident on the SPAD element 6a at time T12. The stray light L3 is incident on the SPAD element 6a, so that electrons are accumulated in the SPAD element 6a in the inactive state.

[0204] Next, control unit 8 switches enable signal from OFF to ON at time T13 which is a predetermined time elapsed from time T11 when light is emitted from light source 4. As a result, gate switch 15 switches from ON to OFF at time T13, thereby bringing the cathode of SPAD element 6a into a floating state.

[0205] Further, the first switch 13 is switched from off to on at time T13. As a result, a current having a current value I1 is supplied from the first constant current source 11 to the cathode of the SPAD element 6a, so that the cathode voltage of the SPAD element 6a gradually increases from 0 (V).

[0206] On the other hand, in this modification, the first switch 13 is switched from on to off at time T14 , so that the cathode voltage of the SPAD element 6 a becomes constant at the predetermined voltage V1 a from time T14 .

[0207] Then, the enable signal transmitted from the control unit 8 is transmitted to the second switch 14 via the above-mentioned pulse generation circuit 19 and delay circuit 18B. As a result, the second switch 14 is switched from off to on at time T15 when a predetermined delay time has elapsed from time T14.

[0208] Therefore, a current having a current value I2 is supplied from the second constant current source 12 to the cathode of the SPAD element 6a, so that the cathode voltage of the SPAD element 6a increases rapidly from the voltage V1a at the time point of time T15. Then, the voltage reaches a predetermined voltage V2 at time T16, and at time T16, the second switch 14 is switched from on to off.

[0209] Further, the enable signal transmitted from the control unit 8 is transmitted to the first switch 13 via the delay circuit 18A. Therefore, at time T16, the first switch 13 is switched from off to on. As a result, a current having a current value I1 is supplied from the first constant current source 11 to the cathode of the SPAD element 6a, so that the cathode voltage of the SPAD element 6a is maintained at the voltage V2.

[0210] because Fig.14 The operation described in time T17 to T19 is the same as Figure 8 The operations at time T6 to T8 in the example are the same, so the detailed description will be omitted.

[0211] As described above, in the modification of the first embodiment, during the gate operation, the current supplied to the SPAD element 6a by the first constant current source 11 is temporarily stopped at time T14, so that the cathode voltage of the SPAD element 6a is kept constant at the voltage V1a.

[0212] As described above, the cathode voltage is kept constant at a voltage higher than 0 (V) and lower than the breakdown voltage (voltage V2) of the SPAD element 6a, thereby enabling electrons accumulated due to the stray light L3 to be appropriately discharged from the SPAD element 6a.

[0213] The reason is as follows: The cathode voltage of the SPAD element 6a is kept constant at a voltage close to 0 (V), thereby intentionally causing the SPAD element 6a to be slightly broken down, thereby eliminating accumulated electrons from the SPAD element 6a due to the breakdown.

[0214] Even if the SPAD element 6 a is intentionally made to break down slightly, the small breakdown is completed in a short time and the SPAD element 6 a immediately returns to a stable state, so there is almost no negative effect on the overall gating operation.

[0215] The configuration of the transmission path of the enable signal that can realize the above-mentioned deformation is not limited to Fig.13 Instances in . Fig.15 : is a circuit diagram showing another configuration example of the pulse output unit 7 according to the modification of the first embodiment of the present disclosure.

[0216] exist Fig.15In the example of , the enable signal is input to the first switch 13 via the pulse generation circuit 19A, and the enable signal is input to the first switch 13 via the delay circuit 18A.

[0217] As a result, even in Fig.15 In the example of, when the enable signal is switched from off to on, the first switch 13 can also be switched from off to on within a predetermined time period. Further, even in Fig.15 In the example of , the first switch 13 can also be switched from off to on after a further predetermined time has elapsed.

[0218] Further, the enable signal is input to the second switch 14 via the delay circuit 18B and the pulse generating circuit 19B. As a result, even in Fig.15 In the example, when the enable signal is switched from off to on, the second switch 14 can also be switched from off to on within a predetermined period of time after a predetermined time has elapsed.

[0219] exist Fig.15 In the example of , since pulses can be generated by independent pulse generating circuits 19A and 19B, the time for which the first switch 13 is kept in the on state and the time for which the second switch 14 is kept in the on state can be independently controlled. Fig.15 , the gating operation can be performed more smoothly.

[0220] Further, in Fig.13 and Fig.15 The pulse output unit 7 shown can perform the same Fig.14 Another operation that is different from the instance of . Fig.16 : is a timing chart showing another operation example of the pulse output unit 7 according to the modification of the first embodiment of the present disclosure.

[0221] Fig.16 The example is an example in which the gating operation is started before causing the light source 4 to emit light. First, the control unit 8 switches the enable signal from off to on at time T21 (ie, a predetermined time before time T23 when the light source 4 is caused to emit light).

[0222] As a result, the gate switch 15 is switched from on to off at time T21, thereby causing the cathode of the SPAD element 6a to enter a floating state.

[0223] Further, the first switch 13 is switched from off to on at time T21. As a result, a current having a current value I1 is supplied from the first constant current source 11 to the cathode of the SPAD element 6a, so that the cathode voltage of the SPAD element 6a gradually increases from 0 (V). Then, the cathode voltage of the SPAD element 6a becomes constant at a predetermined voltage V1a from time T22.

[0224] Then, the control unit 8 controls the light source driving unit 5 so that the light source 4 emits light in a pulsed manner at time T23. As a result, the stray light L3 is incident on the SPAD element 6a at time T24.

[0225] Here, in Fig.16 In the example, since the cathode voltage of the SPAD element 6a has increased to the voltage V1a at time T24 when the stray light L3 is incident, the breakdown of the SPAD element 6a is small, and the cathode voltage of the SPAD element 6a is reduced to 0 (V).

[0226] As mentioned above, in Fig.16 In the example of FIG. 1 , breakdown occurs in the SPAD element 6a due to the stray light L3. Therefore, even if the stray light L3 is incident, the electrons generated by the stray light L3 are not accumulated in the SPAD element 6a.

[0227] That is, in Fig.16 In the example, before the light source 4 is caused to emit light, the first switch 13 is switched from off to on, and the breakdown of the SPAD element 6a due to the incidence of the stray light L3 is intentionally made small. Therefore, the accumulation of electrons due to the stray light L3 can be suppressed.

[0228] Therefore, according to Fig.16 In this example, accumulation of electrons in the SPAD element 6a due to stray light L3 can be suppressed during the gating operation.

[0229] because Fig.16 The operation of time T25 to T29 shown in Fig.14 The operations from time T16 to T19 in the example are the same, so the detailed description will be omitted.

[0230] <Variation of Second Embodiment>

[0231] Fig.17 : is a circuit diagram showing a configuration example of the pulse output unit 7 according to a modification of the second embodiment of the present disclosure. Fig.17 The examples in Fig.11 The second embodiment shown in FIG. 1 is different in the configuration of a path for transmitting an enable signal to the first switch 13 and the second switch 14 .

[0232] Specifically, the enable signal is input to the first switch 13 via the pulse generation circuit 19 , and the enable signal is input to the first switch 13 via the delay circuit 18A.

[0233] That is, when the enable signal is switched from off to on, the first switch 13 is switched from off to on within a predetermined period of time, and the first switch 13 is switched from off to on after a predetermined time has elapsed.

[0234] Further, the enable signal is input to the second switch 14 via the pulse generation circuit 19 and the delay circuit 18B. That is, when the enable signal is switched from OFF to ON, the second switch 14 is switched from OFF to ON within a predetermined period after a predetermined time has elapsed.

[0235] Next, except Fig.17 In addition, reference will be made to Fig.18 The operation of the pulse output unit 7 according to the modification of the second embodiment is described. Fig.18 : is a timing chart showing an operation example of the pulse output unit 7 according to the modification of the second embodiment of the present disclosure.

[0236] exist Fig.14 In the example of , since the enable signal remains in the off state in the initial state, the gate switch 15 remains in the on state, and the SPAD element 6a enters the inactive state.

[0237] Then, the control unit 8 controls the light source driving unit 5 so that the light source 4 emits light in a pulsed manner at time T11. As a result, the stray light L3 is incident on the SPAD element 6a at time T12. The stray light L3 is incident on the SPAD element 6a, so that electrons are accumulated in the SPAD element 6a in the inactive state.

[0238] Next, control unit 8 switches enable signal from OFF to ON at time T13 which is a predetermined time elapsed from time T11 when light is emitted from light source 4. As a result, gate switch 15 switches from ON to OFF at time T13, thereby bringing the anode of SPAD element 6a into a floating state.

[0239] Further, the first switch 13 is switched from off to on at time T13. Therefore, a current having a current value I1 flows from the anode of the SPAD element 6a to the first constant current source 11, so that the anode voltage of the SPAD element 6a gradually decreases from the power supply voltage Vdd.

[0240] On the other hand, in this modification, the first switch 13 is switched from on to off at time T14 , so that the anode voltage of the SPAD element 6 a becomes constant at a predetermined voltage V4 a from time T14 .

[0241] Then, the enable signal transmitted from the control unit 8 is transmitted to the second switch 14 via the above-mentioned pulse generation circuit 19 and delay circuit 18B. As a result, the second switch 14 is switched from off to on at time T15 after a predetermined delay time has elapsed from time T14.

[0242] As a result, a current having a current value I2 flows from the anode of the SPAD element 6a to the second constant current source 12, so that the anode voltage of the SPAD element 6a decreases rapidly from the voltage V4a at the time point of time T15. Then, the voltage reaches the predetermined voltage V3 at time T16, and the second switch 14 switches from on to off at time T16.

[0243] Further, the enable signal sent from the control unit 8 is sent to the first switch 13 via the delay circuit 18A. Therefore, at time T16, the first switch 13 is switched from off to on. As a result, a current having a current value I1 flows from the anode of the SPAD element 6a to the first constant current source 11, so that the anode voltage of the SPAD element 6a is maintained at the voltage V3.

[0244] because Fig.18 The operation described in time T17 to T19 is the same as Fig.12 The operations at time T6 to T8 in the example are the same, so the detailed description will be omitted.

[0245] As described above, in the modification of the second embodiment, during the gate operation, the current emitted from the SPAD element 6a by the first constant current source 11 is temporarily stopped at time T14, so that the anode voltage of the SPAD element 6a is kept constant at the voltage V4a.

[0246] As described above, the anode voltage is kept constant at a voltage lower than the power supply voltage Vdd and higher than the breakdown voltage (voltage V3) of the SPAD element 6a, thereby enabling electrons accumulated due to the stray light L3 to be appropriately discharged from the SPAD element 6a.

[0247] The reason is as follows: The anode voltage of the SPAD element 6a is kept constant at a voltage close to the power supply voltage Vdd to intentionally make the SPAD element 6a break down less, thereby eliminating the accumulated electrons from the SPAD element 6a due to the breakdown.

[0248] Even if the SPAD element 6 a is intentionally made to break down slightly, the small breakdown is completed in a short time and the SPAD element 6 a immediately returns to a stable state, so there is almost no negative effect on the overall gating operation.

[0249] The configuration of the transmission path of the enable signal that can realize the above-mentioned deformation is not limited to Fig.17 Instances in . Fig.19 : is a circuit diagram showing another configuration example of the pulse output unit 7 according to the modification of the second embodiment of the present disclosure.

[0250] exist Fig.19In the example of , the enable signal is input to the first switch 13 via the pulse generation circuit 19A, and the enable signal is input to the first switch 13 via the delay circuit 18A.

[0251] As a result, even in Fig.19 In the example of, when the enable signal is switched from off to on, the first switch 13 can be switched from off to on within a predetermined time period. Further, even in Fig.19 In the example of , the first switch 13 can also be switched from off to on after a further predetermined time has elapsed.

[0252] Further, the enable signal is input to the second switch 14 via the delay circuit 18B and the pulse generating circuit 19B. Fig.19 In the example of, when the enable signal is switched from off to on, the second switch 14 can be switched from off to on within a predetermined period of time after a predetermined time has elapsed.

[0253] exist Fig.19 In the example of , since pulses can be generated by independent pulse generating circuits 19A and 19B, the time for which the first switch 13 is kept in the on state and the time for which the second switch 14 is kept in the on state can be independently controlled. Fig.19 , the gating operation can be performed more smoothly.

[0254] Further, in Fig.17 and Fig.19 The pulse output unit 7 shown can also perform the same Fig.18 Different operations for instances. Fig. 20 : is a timing chart showing another operation example of the pulse output unit 7 according to the modification of the second embodiment of the present disclosure.

[0255] Fig. 20 The example is an example in which the strobe operation is started before causing the light source 4 to emit light. First, the control unit 8 switches the enable signal from off to on at time T21 (ie, a predetermined time before time T23 when causing the light source 4 to emit light).

[0256] As a result, the gate switch 15 is switched from on to off at time T21 , thereby causing the anode of the SPAD element 6 a to enter a floating state.

[0257] Further, the first switch 13 is switched from off to on at time T21. As a result, a current having a current value I1 flows from the anode of the SPAD element 6a to the first constant current source 11, so that the anode voltage of the SPAD element 6a gradually decreases from the power supply voltage Vdd. Therefore, the anode voltage of the SPAD element 6a becomes constant at a predetermined voltage V4a from time T22.

[0258] Therefore, the control unit 8 controls the light source driving unit 5 so that the light source 4 emits light in a pulsed manner at time T23. As a result, the stray light L3 is incident on the SPAD element 6a at time T24.

[0259] Here, in Fig. 20 In the example, because the anode voltage of the SPAD element 6a has been reduced to the voltage V4a at time T24 when the stray light L3 is incident, the breakdown of the SPAD element 6a is small, and the anode voltage of the SPAD element 6a increases to the power supply voltage SPAD element 6a.

[0260] As mentioned above, in Fig. 20 In the example of FIG. 1 , the SPAD element 6a is broken down by the stray light L3. Therefore, even if the stray light L3 is incident, the electrons generated by the stray light L3 are not accumulated in the SPAD element 6a.

[0261] That is, in Fig. 20 In the example, before the light source 4 is caused to emit light, the first switch 13 is switched from off to on, and the SPAD element 6a is intentionally made to break down less due to the incidence of the stray light L3. Therefore, the accumulation of electrons due to the stray light L3 can be suppressed.

[0262] Therefore, according to Fig. 20 In this example, during the gating operation, the accumulation of electrons in the SPAD element 6a due to the stray light L3 can be suppressed.

[0263] because Fig. 20 The operation of time T25 to T29 described in Fig.18 The operations from time T16 to T19 in the example are the same, so the detailed description will be omitted.

[0264] <Effect>

[0265] The distance measuring sensor 1 according to the first embodiment includes a single photon avalanche diode (SPAD) element 6a, a first constant current source 11, and a second constant current source 12, a first switch 13, a second switch 14, and a gate switch 15. The SPAD element 6a outputs a signal S1 when receiving light (reflected light L2) reflected from the measuring object X due to the light L1 emitted from the light source 4. The first constant current source 11 and the second constant current source 12 are connected in parallel to the cathode of the SPAD element 6a. The first switch 13 is connected between the SPAD element 6a and the first constant current source 11. The second switch 14 is connected between the SPAD element 6a and the second constant current source 12. The gate switch 15 is connected between the SPAD element 6a and the first switch 13 and between the SPAD element 6a and the ground potential.

[0266] As a result, the gating operation of the SPAD element 6 a can be performed quickly and appropriately.

[0267] The distance measuring sensor 1 according to the second embodiment includes a single photon avalanche diode (SPAD) element 6a, a first constant current source 11 and a second constant current source 12, a first switch 13, a second switch 14, and a gate switch 15. The SPAD element 6a outputs a signal S1 when receiving light (reflected light L2) reflected from the measuring object X due to the light L1 emitted from the light source 4. The first constant current source 11 and the second constant current source 12 are connected in parallel to the anode of the SPAD element 6a. The first switch 13 is connected between the SPAD element 6a and the first constant current source 11. The second switch 14 is connected between the SPAD element 6a and the second constant current source 12. The gate switch 15 is connected between the SPAD element 6a and the first switch 13 and between the SPAD element 6a and the power supply voltage Vdd.

[0268] As a result, the gating operation of the SPAD element 6 a can be performed quickly and appropriately.

[0269] The distance measuring sensor 1 according to various embodiments further includes a light source 4 and a control unit 8. The light source 4 irradiates the measuring object X with light (emission light L1). The control unit 8 controls the light source 4, the first switch 13, the second switch 14, and the gate switch 15. Then, in synchronization with the light emission operation of the light source 4, the control unit 8 switches the gate switch 15 from on to off.

[0270] As a result, because the SPAD element 6 a can react to the reflected light L2 from the measuring object X without causing the SPAD element 6 a to react to the stray light L3 , the distance D to the measuring object X can be measured with high accuracy.

[0271] Further, in the distance measuring sensor 1 according to various embodiments, the control unit 8 switches the first switch 13 from off to on in synchronization with the off operation of the gate switch 15. Further, after switching the first switch 13 from off to on, the control unit 8 switches the second switch 14 from off to on.

[0272] As a result, the gating operation of the SPAD element 6 a can be performed quickly and appropriately.

[0273] Further, in the distance measuring sensor 1 according to various embodiments, the control unit 8 keeps the first switch 13 in the on state during a period until the second switch 14 is switched from off to on.

[0274] Therefore, the gating operation of the SPAD element 6 a can be performed more quickly.

[0275] Further, in the distance measuring sensor 1 according to each embodiment, the control unit 8 switches the first switch 13 from on to off within a period until the second switch 14 switches from off to on.

[0276] Therefore, the electrons accumulated due to the stray light L3 can be appropriately discharged from the SPAD element 6 a .

[0277] Further, in the distance measuring sensor 1 according to various embodiments, the control unit 8 switches the gate switch 15 from on to off before causing the light source 4 to emit light.

[0278] Therefore, accumulation of electrons due to the stray light L3 in the SPAD element 6 a during the gate operation can be suppressed.

[0279] Further, in the distance measuring sensor 1 according to various embodiments, the current value I1 of the first constant current source 11 is smaller than the current value I2 of the second constant current source.

[0280] Therefore, the gating operation of the SPAD element 6 a can be performed more quickly and appropriately.

[0281] <Application example of moving objects>

[0282] The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure can be implemented as a device installed on any type of mobile object such as a car, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobile body, an airplane, a drone, a ship, and a robot.

[0283] Fig.21 is a block diagram showing an example of a schematic configuration of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0284] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. Fig.21 In the illustrated example, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. In addition, a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface (I / F) 12053 are shown as the functional configuration of the integrated control unit 12050.

[0285] The drive system control unit 12010 controls the operation of the devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 is used to control devices such as a drive force generating device (such as an internal combustion engine, a drive motor, etc.) for generating the drive force of the vehicle, a drive force transmitting mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating the braking force of the vehicle.

[0286] The body system control unit 12020 controls the operation of various types of devices configured for the body according to various programs. For example, the body system control unit 12020 is used as a control device to control the following items: a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a reverse light, a brake light, a turn signal, or a fog light. In this case, a radio wave or various switch signals transmitted from a portable device instead of a key can be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals to control the door lock device, the power window device, the lights, etc. of the vehicle.

[0287] The vehicle exterior information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the imaging unit 12031. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to image the vehicle exterior image and receive the imaged image. Based on the received image, the vehicle exterior information detection unit 12030 may perform a process of detecting an object (such as a person, vehicle, obstacle, sign, symbol, etc. on the road), or perform a process of detecting the distance to the object.

[0288] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or can output the electrical signal as information of the measured distance. In addition, the light received by the imaging unit 12031 may be visible light, or may be invisible light such as infrared rays.

[0289] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that images the driver, and the in-vehicle information detection unit 12040 may calculate the driver's fatigue level or the driver's concentration level based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0290] The microcomputer 12051 can calculate the control target value of the driving force generation device, the steering mechanism or the braking device based on the information inside or outside the vehicle obtained by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of the advanced driver assistance system (ADAS), which includes collision avoidance or impact buffering of the vehicle, follow-up driving based on the vehicle-to-vehicle distance, speed maintenance driving, vehicle collision alarm, vehicle lane deviation warning, etc.

[0291] In addition, the microcomputer 12051 can control the driving force generating device, steering mechanism, braking device, etc. based on the information about the vehicle surroundings obtained by the external information detection unit 12030 or the internal information detection unit 12040, thereby performing collaborative control such as automatic driving aimed at automatic movement without relying on the driver's operation.

[0292] In addition, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle obtained by the vehicle exterior information detection unit 12030. For example, the microcomputer 12051 can control the headlights based on the position of the preceding vehicle or the oncoming vehicle detected by the vehicle exterior information detection unit 12030, thereby performing cooperative control aimed at preventing glare, such as changing from high beam to low beam.

[0293] The audio / image output unit 12052 transmits an output signal of at least one of audio and image to an output device, which can provide information to the passengers of the vehicle or the outside of the vehicle in a visual or auditory manner. Fig.21 In the example of FIG. 1 , an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are shown as output devices. The display unit 12062 may include, for example, at least one of an in-vehicle display and a head-up display.

[0294] Fig. 22 is a diagram showing an example of the installation position of the imaging unit 12031.

[0295] exist Fig. 22 In the figure, imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104 and 12105.

[0296] For example, the imaging units 12101, 12102, 12103, 12104, and 12105 may be arranged at locations such as the front nose, side mirrors, rear bumper, rear door, and upper portion of the windshield inside the vehicle 12100. The imaging unit 12101 arranged at the front nose and the imaging unit 12105 arranged at the upper portion of the windshield inside the vehicle mainly obtain images in front of the vehicle 12100. The imaging units 12102 and 12103 arranged at the side mirrors mainly obtain images of the sides of the vehicle 12100. The imaging unit 12104 arranged at the rear bumper or rear door mainly obtains images of the rear of the vehicle 12100. The imaging unit 12105 arranged at the upper portion of the windshield inside the vehicle is mainly used to detect the vehicle in front, or pedestrians, obstacles, signals, traffic signs, lanes, etc.

[0297] Fig. 22 An example of the imaging ranges of the imaging units 12101 to 12104 is shown. The imaging range 12111 represents the imaging range of the imaging unit 12101 arranged at the front nose, the imaging ranges 12112 and 12113 represent the imaging ranges of the imaging units 12102 and 12103 arranged at the side mirrors, respectively, and the imaging range 12114 represents the imaging range of the imaging unit 12104 arranged at the rear bumper or the rear door. For example, the image data imaged by the imaging units 12101 to 12104 are superimposed, thereby obtaining a bird's-eye view image of the vehicle 12100 observed from above.

[0298] At least one of the imaging units 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0299] For example, the microcomputer 12051 can obtain the distance to each three-dimensional object within the imaging range 12111 to 12114 and the time change of the distance (relative speed relative to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, and thereby extract the three-dimensional object (specifically, the closest three-dimensional object on the moving path of the vehicle 12100) traveling at a predetermined speed (e.g., equal to or greater than 0 km / h) in the same direction as the vehicle 12100 as the front vehicle. In addition, the microcomputer 12051 can pre-set the inter-vehicle distance to be maintained from the front vehicle, and perform automatic braking control (including parking control for following), automatic acceleration control (including starting control for following), etc. As described above, cooperative control such as automatic driving aimed at automatic travel without relying on the operation of the driver can be performed.

[0300] For example, the microcomputer 12051 can classify the three-dimensional object data about the three-dimensional object into other three-dimensional objects such as two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians and utility poles based on the distance information obtained from the imaging units 12101 to 12104, extract the data, and use the data to automatically avoid obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 that are visually visible to the driver of the vehicle 12100 and obstacles that are visually invisible to the driver of the vehicle 12100. In addition, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or higher than a set value and there is a possibility of collision, the microcomputer 12051 outputs an alarm to the driver via the audio speaker 12061 or the display unit 12062, or performs forced deceleration or evasive steering through the drive system control unit 12010. As a result, the microcomputer 12051 can assist driving to avoid collision.

[0301] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 is capable of identifying pedestrians by determining whether there are pedestrians in the imaging images of the imaging units 12101 to 12104. For example, such pedestrian recognition is performed by, for example, a program that extracts characteristic points in the imaging images of the imaging units 12101 to 12104 as infrared cameras, and a program that determines whether it is a pedestrian by performing pattern matching processing on a series of characteristic points representing the contour of the object. If the microcomputer 12051 determines that there are pedestrians in the imaging images of the imaging units 12101 to 12104 and thus identifies the pedestrians, the audio / image output unit 12052 controls the display unit 12062 so that the identified pedestrians are superimposed and displayed with a square outline for emphasis. Further, the audio / image output unit 12052 may also control the display unit 12062 so that it displays an icon representing a pedestrian at a desired position.

[0302] An example of a vehicle control system to which the technology according to the present disclosure can be applied has been described. The technology according to the present disclosure can be applied to the imaging unit 12031 of the above configuration. Specifically, Figure 5 The distance measuring sensor 1 in can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, the gating operation of the SPAD element can be performed quickly and appropriately.

[0303] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above embodiments, and various modifications can be made without departing from the essence of the present disclosure. Further, different embodiments and modified components can be appropriately combined.

[0304] For example, in the above-described embodiments, an example has been shown in which two constant current sources are connected in parallel to the SPAD element 6a. However, the number of constant current sources connected in parallel to the SPAD element 6a is not limited to two, and three or more constant current sources may be connected in parallel.

[0305] Further, the effects described in this specification are merely examples and are not limiting, and other effects may be added.

[0306] The present technology can also adopt the following configurations.

[0307] (1) A distance measuring sensor comprising:

[0308] a single photon avalanche diode (SPAD) element configured to output a signal upon receiving light reflected from a measurement object due to light emitted from a light source;

[0309] A first constant current source and a second constant current source are connected in parallel to the cathode of the SPAD element;

[0310] A first switch connected between the SPAD element and the first constant current source;

[0311] A second switch connected between the SPAD element and the second constant current source; and

[0312] The gate switch is connected between the SPAD element and the first switch and between the SPAD element and the ground potential.

[0313] (2) A distance measuring sensor comprising:

[0314] a single photon avalanche diode (SPAD) element configured to output a signal upon receiving light reflected from a measurement object due to light emitted from a light source;

[0315] A first constant current source and a second constant current source are connected in parallel to the anode of the SPAD element;

[0316] A first switch connected between the SPAD element and a first constant current source;

[0317] A second switch connected between the SPAD element and the second constant current source; and

[0318] The gate switch is connected between the SPAD element and the first switch and between the SPAD element and the power supply voltage.

[0319] (3) The distance measuring sensor according to (1) or (2), further comprising:

[0320] a light source configured to illuminate the measurement object with light; and

[0321] A control unit is configured to control the light source, the first switch, the second switch and the gating switch; wherein,

[0322] The control unit switches the gate switch from on to off in synchronization with the light emitting operation of the light source.

[0323] (4) The distance measuring sensor according to (3), wherein:

[0324] The control unit switches the first switch from off to on in synchronization with the off operation of the gate switch; and

[0325] The control unit switches the second switch from off to on after switching the first switch from off to on.

[0326] (5) The distance measuring sensor according to (4), wherein:

[0327] The control unit keeps the first switch in the on state during a period until the second switch switches from off to on.

[0328] (6) The distance measuring sensor according to (4), wherein:

[0329] The control unit switches the first switch from on to off within a time period until the second switch switches from off to on.

[0330] (7) The distance measuring sensor according to any one of (4) to (6), wherein:

[0331] The control unit switches the gate switch from on to off before causing the light source to emit light.

[0332] (8) The distance measuring sensor according to any one of (1) to (7), wherein:

[0333] The current value of the first constant current source is smaller than the current value of the second constant current source.

[0334] Additionally or alternatively, the present technology can also adopt the following configurations.

[0335] (1') A light detection device comprising:

[0336] an avalanche photodiode, wherein an electrode of the avalanche photodiode is coupled to the first node;

[0337] a first switch coupled to the first node and coupled to the first potential line via a first current source;

[0338] a second switch coupled to the first node and coupled to the first potential line via a second current source; and

[0339] The delay circuit is coupled to the first switch and the second switch.

[0340] (2′) The light detection device according to (1′), further including a third switch coupled to the first node and the second potential line.

[0341] (3′) The light detection device according to (1′) or (2′), wherein a current value of the first current source is smaller than a current value of the second current source.

[0342] (4′) The light detection device according to any one of (1′) to (3′), further including a control circuit configured to control the first switch and the second switch.

[0343] (5′) The light detection device according to (4′), wherein the control circuit is configured to output the enable signal to the first switch and the delay circuit, and the delay circuit is configured to output the delayed enable signal to the second switch.

[0344] (6′) The light detection device according to (5′), wherein the first switch is configured to switch between the conductive state and the disconnected state based on the enable signal, and the second switch is configured to switch between the conductive state and the disconnected state based on the delayed enable signal.

[0345] (7′) The light detection device according to any one of (1′) to (6′), comprising:

[0346] A first chip including an avalanche photodiode; and

[0347] The second chip includes a first switch and a second switch.

[0348] (8′) The light detection device according to any one of (1′) to (7′), further including an inverter coupled to the first potential line and the first node.

[0349] (9') The light detection device according to any one of (1') to (8'), wherein the electrode is an anode.

[0350] (10') The light detection device according to any one of (1') to (8'), wherein the electrode is a cathode.

[0351] (11') A method for detecting light, the method comprising:

[0352] providing an avalanche photodiode, wherein an electrode of the avalanche photodiode is coupled to a first node;

[0353] Providing a first switch, the first switch is coupled to the first node and coupled to the first potential line via a first current source;

[0354] providing a second switch coupled to the first node and to the first potential line via a second current source; and

[0355] A delay circuit is provided and coupled to the first switch and the second switch.

[0356] (12′) The method according to (11′), further comprising: providing a third switch coupled to the first node and the second potential line.

[0357] (13') The method according to (11') or (12'), further comprising: controlling the first switch and the second switch via a control circuit.

[0358] (14′) The method according to (13′), further comprising: outputting an enable signal from the control circuit to the first switch and the delay circuit, and outputting a delayed enable signal from the delay circuit to the second switch.

[0359] (15') The method according to any one of (11') to (14'), comprising:

[0360] providing a first chip including an avalanche photodiode; and

[0361] A second chip including a first switch and a second switch is provided.

[0362] (16′) The method according to any one of (11′) to (15′), further comprising: providing an inverter coupled to the first potential line and the first node.

[0363] (17′) The method according to any one of (11′) to (16′), wherein the electrode is an anode.

[0364] (18') The method according to any one of (11') to (17'), wherein the electrode is a cathode.

[0365] (19') A distance measurement system comprising:

[0366] a light source device configured to emit a first light; and

[0367] A light detection device is configured to receive second light generated from the object due to the first light, the light detection device comprising:

[0368] an avalanche photodiode, wherein an electrode of the avalanche photodiode is coupled to the first node;

[0369] a first switch coupled to the first node and coupled to the first potential line via a first current source;

[0370] a second switch coupled to the first node and coupled to the first potential line via a second current source; and

[0371] The delay circuit is coupled to the first switch and the second switch.

[0372] (20′) The distance measurement system according to (19′), wherein the light detection device includes a third switch coupled to the first node and the second potential line.

[0373] (21′) The distance measurement system according to (20′), wherein the second switch is configured to switch to the conductive state at a time after the third switch switches to the open state and before the light detection device receives the second light.

[0374] [Reference Numbers List]

[0375] 1 Distance measurement sensor

[0376] 4 Light Source

[0377] 6a SPAD element

[0378] 7 Pulse output unit

[0379] 8 Control unit

[0380] 11. First constant current source

[0381] 12. Second constant current source

[0382] 13 First switch

[0383] 14 Second switch

[0384] 15 Enable switch.

Claims

1. A light detection device, comprising: an avalanche photodiode, wherein an electrode of the avalanche photodiode is coupled to the first node; a first switch coupled to the first node and coupled to a first potential line via a first current source; a second switch coupled to the first node and coupled to the first potential line via a second current source; and The delay circuit is coupled to the first switch and coupled to the second switch via a pulse generating circuit. 2 . The light detection device according to claim 1 , further comprising a third switch coupled to the first node and the second potential line.

3. The light detection device according to claim 1, wherein A current value of the first current source is smaller than a current value of the second current source. 4 . The light detection device of claim 1 , further comprising a control circuit configured to control the first switch and the second switch.

5. The light detection device according to claim 4, wherein The control circuit is configured to output an enable signal to the first switch and the delay circuit, and the delay circuit is configured to output a delayed enable signal to the second switch.

6. The light detection device according to claim 5, wherein The first switch is configured to switch between a conductive state and an open state based on the enable signal, and the second switch is configured to switch between a conductive state and an open state based on the delayed enable signal.

7. The light detection device according to claim 1, comprising: A first chip, comprising the avalanche photodiode; and The second chip includes the first switch and the second switch. 8 . The light detecting device according to claim 1 , further comprising an inverter coupled to the first potential line and the first node.

9. The light detection device according to claim 1, wherein The electrode is an anode.

10. The light detection device according to claim 1, wherein The electrode is a cathode.

11. A method for detecting light, the method comprising: providing an avalanche photodiode, wherein an electrode of the avalanche photodiode is coupled to a first node; providing a first switch, the first switch being coupled to the first node and to a first potential line via a first current source; providing a second switch, the second switch being coupled to the first node and to the first potential line via a second current source; and A delay circuit is provided and coupled to the first switch and the second switch.

12. The method according to claim 11, further comprising: A third switch is provided coupled to the first node and the second potential line.

13. The method according to claim 11, further comprising: The first switch and the second switch are controlled via a control circuit.

14. The method according to claim 13, further comprising: An enable signal is output from the control circuit to the first switch and the delay circuit, and a delayed enable signal is output from the delay circuit to the second switch.

15. The method according to claim 11, comprising: providing a first chip including the avalanche photodiode; and A second chip including the first switch and the second switch is provided.

16. The method according to claim 11, further comprising: An inverter coupled to the first potential line and the first node is provided.

17. The method according to claim 11, wherein: The electrode is an anode.

18. The method according to claim 11, wherein: The electrode is a cathode.

19. A distance measurement system, comprising: A light source device configured to emit a first light; and A light detection device, configured to receive second light generated from an object due to the first light, the light detection device comprising: an avalanche photodiode, wherein an electrode of the avalanche photodiode is coupled to the first node; a first switch coupled to the first node and coupled to a first potential line via a first current source; a second switch coupled to the first node and coupled to the first potential line via a second current source; and The delay circuit is coupled to the first switch and coupled to the second switch via a pulse generating circuit.

20. The distance measurement system according to claim 19, wherein: The light detection device comprises a third switch coupled to the first node and a second potential line.

21. The distance measurement system according to claim 20, wherein: The second switch is configured to switch to a conductive state at a time after the third switch switches to an open state and before the light detection device receives the second light.

Images