Time measuring device

Abstract

The present application provides a kind of time measuring device, it has: pixel, with light receiving element, can generate the pulse signal containing logic pulse based on the light receiving result of light receiving element;Time detection unit, can detect the light receiving time of light receiving element based on pulse signal;Pulse number detection unit, can detect the pulse number of logic pulse contained in pulse signal;And control unit, can control the action of the light source that emits multiple light pulses based on pulse number.

Description

TECHNICAL FIELD

[0001] The present application relates to a time measurement device that measures a time from a time when light is emitted to a time when the light is detected. BACKGROUND

[0002] In measuring a distance to an object to be measured, a TOF (Time Of Flight) method is generally used. In the TOF method, light is emitted and reflected light reflected by the object to be measured is detected. Also, in the TOF method, a distance to the object to be measured is measured by measuring a time difference between a time when the light is emitted and a time when the reflected light is detected (for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Publication No. 2010-91377 SUMMARY

[0004] However, in general, in electronic devices, it is desirable to reduce power consumption, and even in the time measurement device, it is desirable to reduce power consumption.

[0005] It is desirable to provide a time measurement device that can reduce power consumption.

[0006] A first time measurement device of one embodiment of the present application includes a pixel, a time detection unit, a pulse number detection unit, and a control unit. The pixel includes a light receiving element and can generate a pulse signal including a logic pulse on the basis of a light receiving result of the light receiving element. The time detection unit can detect a light receiving time of the light receiving element on the basis of the pulse signal. The pulse number detection unit can detect a pulse number of the logic pulse included in the pulse signal. The control unit can control an operation of a light source that emits a plurality of light pulses on the basis of the pulse number.

[0007] A second time measurement device of one embodiment of the present application includes a first pixel, a second pixel, a time detection unit, a pulse number detection unit, and a control unit. The first pixel includes a first light receiving element and can generate a first pulse signal including a logic pulse on the basis of a light receiving result of the first light receiving element. The second pixel includes a second light receiving element and can generate a second pulse signal including a logic pulse on the basis of a light receiving result of the second light receiving element. The time detection unit can detect a light receiving time of the first light receiving element on the basis of the first pulse signal. The pulse number detection unit can detect a pulse number of the logic pulse included in the second pulse signal. The control unit can control an operation of a light source that emits a plurality of light pulses on the basis of the pulse number.

[0008] In the first time measurement device of one embodiment of the present application, a pulse signal including a logic pulse is generated on the basis of a light-receiving result of a light-receiving element, and a light-receiving timing of the light-receiving element is detected on the basis of the pulse signal. Further, the number of pulses of the logic pulse included in the pulse signal is detected, and the operation of the light source that emits a plurality of light pulses is controlled on the basis of the number of pulses.

[0009] In the second time measurement device of one embodiment of the present application, a first pulse signal including a logic pulse is generated on the basis of a light-receiving result of a first light-receiving element, and a light-receiving timing of the first light-receiving element is detected on the basis of the first pulse signal. Further, a second pulse signal including a logic pulse is generated on the basis of a light-receiving result of a second light-receiving element. Then, the number of pulses of the logic pulse included in the second pulse signal is detected, and the operation of the light source that emits a plurality of light pulses is controlled on the basis of the number of pulses.

[0010] The first time measurement device and the second time measurement device according to one embodiment of the present application control the operation of the light source on the basis of the number of pulses of the logic pulse included in the pulse signal, and thus power consumption can be reduced. Note that the effects described here are not limiting, and any of the effects described in the present application can be included. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 FIG. 1 is a block diagram illustrating one embodiment of a time measurement device according to the present application.

[0012] Figure 2 FIG. 2 is a block diagram illustrating one embodiment of a sensor portion of the time measurement device. Figure 1

[0013] Figure 3 FIG. 3 is a circuit diagram illustrating one embodiment of a pixel array of the time measurement device. Figure 2

[0014] Figure 4 FIG. 4 is a circuit diagram illustrating one embodiment of an inverter of the time measurement device. Figure 3

[0015] Figure 5 FIG. 5 is a diagram illustrating one example of a histogram generated by a histogram generation circuit of the time measurement device. Figure 2

[0016] Figure 6A FIG. 6 is a diagram illustrating one example of an operation of a light intensity measurement portion of the time measurement device. Figure 2

[0017] Figure 6B FIG. 7 is a diagram illustrating another example of an operation of the light intensity measurement portion of the time measurement device. Figure 2

[0018] Figure 6C ​​​​​​is a diagram showing Figure 2 is a diagram showing another operation example of the light intensity measuring section.

[0019] Figure 7 is a diagram showing Figure 2 is a diagram showing an installation example of the sensor section.

[0020] Figure 8 is a diagram showing Figure 1 is a time chart showing an operation example of the time measuring device.

[0021] Figure 9 is a time chart showing an operation example of the time measuring device in a dark environment.

[0022] Figure 10 is a time chart showing an operation example of the time measuring device in a bright environment.

[0023] Figure 11 is a diagram showing an example of a histogram in a dark environment.

[0024] Figure 12 is a diagram showing an example of a histogram in a bright environment.

[0025] Figure 13 is a diagram showing an example of a histogram involved in a comparative example.

[0026] Figure 14 is a block diagram showing a configuration example of the time measuring device involved in a modification example.

[0027] Figure 15 is a block diagram showing a configuration example of the sensor section involved in another modification example.

[0028] Figure 16 is a block diagram showing a configuration example of the time measuring device involved in still another modification example.

[0029] Figure 17 is a diagram showing Figure 16 is a block diagram showing a configuration example of the sensor section.

[0030] Figure 18 is a block diagram showing a configuration example of the time measuring device involved in another modification example.

[0031] Figure 19 is a diagram showing Figure 18 is a block diagram showing a configuration example of the sensor section.

[0032] Figure 20 is a block diagram showing a configuration example of the sensor section involved in another modification example.

[0033] Figure 21is a block diagram showing a configuration example of a sensor section according to another modification example.

[0034] Figure 22 is a block diagram showing a configuration example of a sensor section according to still another example.

[0035] Figure 23 is a configuration diagram showing a configuration example of a time measuring device according to an embodiment.

[0036] Figure 24 is a block diagram showing a configuration example of a sensor section according to the second embodiment.

[0037] Figure 25 is an explanatory diagram showing an example of a light pulse according to the second embodiment.

[0038] Figure 26 is a block diagram showing a configuration example of a sensor section according to the third embodiment.

[0039] Figure 27 is an explanatory diagram showing an example of a histogram in a dark environment.

[0040] Figure 28 is an explanatory diagram showing an example of a histogram in a bright environment.

[0041] Figure 29 is a configuration diagram showing a configuration example of an imaging device according to an application example.

[0042] Figure 30 is a block diagram showing a configuration example of an imaging section shown in Figure 29

[0043] is an explanatory diagram showing a configuration example of a pixel in a pixel array shown in Figure 31 Figure 30 DETAILED DESCRIPTION

[0044] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings. In addition, the description is made in the following order.

[0045] 1. First Embodiment

[0046] 2. Second Embodiment

[0047] 3. Third Embodiment

[0048] 4. Application Example (Application to Imaging Device)

[0049] <1. First Embodiment>

[0050] [Configuration Example]

[0051] ​​Figure 1 Fig. 1 shows a configuration example of a time measurement device (time measurement device 1) according to the first embodiment. The time measurement device 1 emits light and detects reflected light reflected by a measurement target object, and measures a time difference between a time at which the light is emitted and a time at which the reflected light is detected. The time measurement device 1 includes a light source 11, a light source drive section 12, a lens 13, and a sensor section 20.

[0052] The light source 11 emits a light pulse L1 toward the measurement target object, and is configured using, for example, a pulsed laser light source.

[0053] The light source drive section 12 drives the light source 11 based on an instruction from the sensor section 20. Specifically, the light source drive section 12 controls the operation of the light source 11 based on an emission trigger signal S1 supplied from the sensor section 20, so that the light source 11 emits light at a time corresponding to a trigger pulse included in the emission trigger signal S1. In addition, the light source drive section 12 has a function of controlling the light intensity of the light pulse L1 emitted from the light source 11 based on a light intensity control signal S2 supplied from the sensor section 20.

[0054] The lens 13 images an image on a sensor surface of the sensor section 20. A light pulse (reflected light pulse L2) reflected by the measurement target object is incident on the lens 13.

[0055] The sensor section 20 generates a depth image (depth image) PIC having information on the distance to the measurement target object by detecting the reflected light pulse L2. A plurality of pixel values included in the depth image PIC respectively represent values on the depth (depth values D). Then, the sensor section 20 outputs the generated depth image PIC. In addition, the sensor section 20 also has a function of generating the emission trigger signal S1 and the light intensity control signal S2, and supplying these signals to the light source drive section 12.

[0056] Figure 2 Fig. 2 shows a configuration example of the sensor section 20. The sensor section 20 includes a pixel array 21, a selection signal generation section 22, a counting section 123, a time measurement section 124, a histogram generation section 125, a processing section 26, and a control section 27.

[0057] The pixel array 21 has a plurality of pixels PZ arranged in a matrix shape.

[0058] Figure 3 Fig. 3 shows a configuration example of the pixel array 21. The pixel array 21 has a plurality of selection lines SEL and a plurality of signal lines SGL. Figure 3 Fig. 4 illustrates four (= 2 x 2) pixels PZ adjacent to each other in the pixel array 21. The pixel array 21 has a plurality of selection lines SEL and a plurality of signal lines SGL. The plurality of selection lines SEL respectively extend in the vertical direction in Fig. 4, and the plurality of signal lines SGL respectively extend in the horizontal direction in Fig. 4. Figure 2 、 3 ,Figure 2 As shown in FIG. 2, one end of the selection line SEL is connected to the selection signal generating section 22. The selection signal SSEL is applied to the selection line SEL by the selection signal generating section 22. The plurality of signal lines SGL extend in the horizontal direction in the pixel array 21, as shown in FIG. 2, and one end of each of the signal lines SGL is connected to the inverter 34. Figure 2 、 3 As shown in FIG. 2, one end of the selection line SEL is connected to the selection signal generating section 22. The selection signal SSEL is applied to the selection line SEL by the selection signal generating section 22. The plurality of signal lines SGL extend in the horizontal direction in the pixel array 21, as shown in FIG. 2, and one end of each of the signal lines SGL is connected to the inverter 34. Figure 2 As shown in FIG. 2, one end of the selection line SEL is connected to the selection signal generating section 22. The selection signal SSEL is applied to the selection line SEL by the selection signal generating section 22. The plurality of signal lines SGL extend in the horizontal direction in the pixel array 21, as shown in FIG. 2, and one end of each of the signal lines SGL is connected to the inverter 34.

[0059] The light-receiving element 31 is a photodiode that detects light, and is configured using, for example, a single photon avalanche diode (SPAD). The negative electrode of the light-receiving element 31 is connected to the drain of the transistors 32 and 33 and the input terminal of the inverter 34, and the positive electrode is supplied with a prescribed bias voltage Vbias.

[0060] The transistor 32 is a P-type MOS (Metal Oxide Semiconductor) transistor, the source of which is supplied with a power supply voltage Vdd, the gate of which is supplied with a voltage Vgl, and the drain of which is connected to the negative electrode of the light-receiving element 31, the drain of the transistor 33, and the input terminal of the inverter 34. In the case where the pixel array 21 is operating, the transistor 32 functions as a constant current source that flows a prescribed current corresponding to the voltage Vgl to the light-receiving element 31. Further, in the case where the pixel array 21 is not operating, the voltage Vgl becomes a high level, whereby the transistor 32 is set to an off state.

[0061] The transistor 33 is an N-type MOS transistor, the source of which is grounded, the gate of which is supplied with a voltage Vg2, and the drain of which is connected to the negative electrode of the light-receiving element 31, the drain of the transistor 32, and the input terminal of the inverter 34. In the case where the pixel array 21 is operating, the voltage Vg2 becomes a low level, whereby the transistor 33 is set to an off state. Further, in the case where the pixel array 21 is not operating, the voltage Vg2 becomes a high level, whereby the transistor 33 is set to an on state.

[0062] The inverter 34 inverts the voltage in the input terminal and outputs the inverted voltage from the output terminal. Further, the inverter 34 also has a function of making the output impedance a high impedance based on the selection signal SSEL input to the control terminal. The input terminal of the inverter 34 is connected to the negative electrode of the light-receiving element 31 and the drains of the transistors 32 and 33, the control terminal is connected to the selection line SEL, and the output terminal is connected to the signal line SGL.

[0063] Figure 4 FIG. 4 shows a configuration example of the inverter 34. The inverter 34 has transistors 35 to 38 and an inverter 39.

[0064] The transistors 35 and 36 are P-type MOS transistors. The source of the transistor 35 is supplied with the power supply voltage Vdd, the gate is connected to the output terminal of the inverter 39, and the drain is connected to the source of the transistor 36. The source of the transistor 36 is connected to the drain of the transistor 35, the gate is connected to the input terminal of the inverter 34, and the drain is connected to the output terminal of the inverter 34. The transistors 37 and 38 are N-type MOS transistors. The drain of the transistor 37 is connected to the output terminal of the inverter 34, the gate is connected to the input terminal of the inverter 34, and the source is connected to the drain of the transistor 38. The drain of the transistor 38 is connected to the source of the transistor 37, the gate is connected to the control terminal of the inverter 34, and the source is grounded. The input terminal of the inverter 39 is connected to the control terminal of the inverter 34, and the output terminal is connected to the gate of the transistor 35.

[0065] According to this configuration, the inverter 34 inverts the voltage of the input terminal and outputs the inverted voltage from the output terminal when the voltage of the selection signal SSEL input to the control terminal is high. Further, the inverter 34 makes the output impedance high impedance when the voltage of the selection signal SSEL input to the control terminal is low.

[0066] In the pixel array 21, a column amount of the pixels PZ among the plurality of pixels PZ are selected based on the selection signal SSEL. Specifically, the selection signal generation section 22 selects a column amount of the pixels PZ connected to the selection line SEL to which the selection signal SSEL of which the voltage is made high is supplied, by making the voltage of one selection signal SSEL among the plurality of selection signals SSEL high. In the selected pixels PZ, if the light pulse (the reflected light pulse L2) is incident to the light-receiving element 31, a current flows in the light-receiving element 31, and the voltage of the negative electrode of the light-receiving element 31 is temporarily lowered. The inverter 34 outputs the pulse PU from the output terminal based on the voltage of the negative electrode of the light-receiving element 31. In this way, the selected pixels PZ output the pixel signal SIG including the pulse PU corresponding to the incident reflected light pulse L2.

[0067] The selection signal generation section 22 Figure 2 generates the plurality of selection signals SSEL based on the control signal supplied from the control section 27, and supplies the plurality of selection signals SSEL to the plurality of columns of the pixels PZ in the pixel array 21, respectively. The selection signal generation section 22 sequentially sets the voltage of one selection signal SSEL among the plurality of selection signals SSEL to high, and sequentially selects the plurality of pixels PZ in column units.

[0068] The counter section 123 has a plurality of counters 23 (counters 23(1), 23(2), 23(3),...). The plurality of counters 23 are connected to the plurality of signal lines SGL in the pixel array 21, respectively. The plurality of counters 23 count the number of the pulses PU included in the pixel signal SIG supplied from the pixel array 21 via the signal line SGL, respectively, on the basis of a control signal supplied from the control section 27. Then, the counter section 123 supplies the count results (count values CNT) of the plurality of counters 23 to the control section 27.

[0069] The time measurement section 124 has a plurality of TDCs (Time to Digital Converters) 24 (TDCs 24(1), 24(2), 24(3),...). The plurality of TDCs 24 are connected to the plurality of signal lines SGL in the pixel array 21, respectively. The plurality of TDCs 24 measure the time of the pulses PU included in the pixel signal SIG supplied from the pixel array 21 via the signal line SGL, respectively, on the basis of a control signal supplied from the control section 27. Specifically, the TDC 24 starts counting the clock pulses of a clock signal CK supplied from the control section 27 on the basis of a start signal STT supplied from the control section 27. Then, the TDC 24 outputs the count value at the time when the pulse PU appears in the pixel signal SIG. The time indicated by the start signal STT corresponds to the time of the emission of the light pulse L1 by the light source 11. Therefore, the count value outputted by the TDC 24 corresponds to the time difference between the time of the emission of the light pulse L1 by the light source 11 and the time of the detection of the reflected light pulse L2 by the pixel PZ, in other words, the distance between the time measurement device 1 and the measurement target object. That is, the count value outputted by the TDC 24 is the depth value D. In this way, the time measurement section 124 outputs the depth value D every time the pulse PU appears in the pixel signal SIG.

[0070] The histogram generation section 125 has a plurality of histogram generation circuits 25 (histogram generation circuits 25(1), 25(2), 25(3),...). The plurality of histogram generation circuits 25 are provided corresponding to the plurality of TDCs 24, respectively. The histogram generation circuit 25(1) generates a histogram HY of the depth values D supplied from the TDC 24(1) on the basis of a control signal supplied from the control section 27. The histogram generation circuit 25(2) generates a histogram HY of the depth values D supplied from the TDC 24(2) on the basis of a control signal supplied from the control section 27. The same applies to the other histogram generation circuits 25.

[0071] Figure 5 An example of the histogram HY generated by the histogram generation circuit 25 is shown. The horizontal axis indicates the depth value D, and the vertical axis indicates the frequency of the appearance of the depth value D. In this example, the histogram HY has a peak W1 and a floor W2 other than the peak W1.

[0072] The peak Wl is based on the pulse PU corresponding to the reflected light pulse L2. The center value Dl of the peak Wl corresponds to, for example, a time difference between a time at which the light source 11 emits the light pulse LI and a time at which the pixel PZ detects the reflected light pulse L2, and corresponds to a distance between the time measurement device 1 and the measurement target object. That is, for example, the center value Dl is a desired depth value D that the time measurement device 1 should measure. The height of the peak Wl can be increased, for example, by increasing the light intensity of the light pulse LI emitted by the light source 11.

[0073] The bottom wave W2 is based on the pulse PU generated at a random time. That is, in each pixel PZ, ambient light is incident in addition to the reflected light pulse L2, and thus each pixel PZ generates a pulse PU corresponding to the ambient light. Further, in each pixel PZ, even in the case where no light is incident, it is possible, for example, to generate a pulse PU corresponding to so-called dark current. These pulses PU are generated at random times, and thus appear as the bottom wave W2 in the histogram HY as shown in FIG. 6, for example. The bottom wave W2 becomes low in a dark environment and becomes high in a bright environment, for example. When the position of the peak Wl is detected, the bottom wave W2 becomes noise, and thus it is desirable for the bottom wave W2 to be low. In the time measurement device 1, as described later, the light intensity of the light pulse LI is adjusted so that the height of the peak Wl exceeds the bottom wave W2, and the height of the peak Wl does not become excessively high compared to the bottom wave W2. Figure 5

[0074] The plurality of histogram generation circuits 25 respectively generate such generated histograms HY. Then, the histogram generation section 125 supplies information on the histograms HY (for example, the center value Dl of each histogram HY) generated by the histogram generation circuits 25 to the processing section 26.

[0075] The processing section 26 generates a depth image PIC based on a control signal supplied from the control section 27 and information on the plurality of histograms HY supplied from the histogram generation section 125. The plurality of pixel values included in the depth image PIC respectively represent values related to depth (depth values D). Then, the processing section 26 outputs the generated depth image PIC.

[0076] The control section 27 supplies control signals to the selection signal generation section 22, the counting section 123, the time measurement section 124, the histogram generation section 125, and the processing section 26, and supplies a light emission trigger signal SI and a light intensity control signal S2 to the light source drive section 12, thereby controlling the operation of the time measurement device 1. The control section 27 has a light emission time setting section 28 and a light intensity setting section 29.

[0077] ​The light emission timing setting section 28 generates a light emission trigger signal S1 indicating the light emission timing of the light source 11. The light emission trigger signal S1 contains a plurality of trigger pulses. The control section 27 controls the operation of the light source 11 by supplying this light emission trigger signal S1 to the light source drive section 12, so that the light source 11 emits light at the timing corresponding to the trigger pulses contained in the light emission trigger signal S1.

[0078] The light intensity setting section 29 generates a light intensity control signal S2 indicating the light intensity of the light pulse L1 based on the plurality of count values CNT supplied from the counting section 123. The count value CNT contains not only the number of pulses PU corresponding to the reflected light pulse L2, but also the number of pulses PU corresponding to the ambient light and the dark current. Therefore, the bottom wave W2 is low in the case where the count value CNT is small, and the bottom wave W2 is high in the case where the count value CNT is large. The light intensity setting section 29 generates the light intensity control signal S2 indicating the light intensity of the light pulse L1 based on such a count value CNT. The control section 27 controls the operation of the light source 11 by supplying this light intensity control signal S2 to the light source drive section 12, so that the light source 11 emits the light pulse L1 of the light intensity corresponding to the light intensity control signal S2.

[0079] The light intensity setting section 29 sets the light intensity of the light pulse L1 based on, for example, the maximum value (maximum count value CNTmax) of the plurality of count values CNT with respect to all the pixels PZ.

[0080] Figure 6A An example of the operation of the light intensity setting section 29 is shown. The horizontal axis indicates the maximum count value CNTmax, and the vertical axis indicates the light intensity of the light pulse L1. In this example, in the case where the maximum count value CNTmax is equal to or greater than a value Cl and equal to or less than a value C2, the greater the maximum count value CNTmax, the greater the light intensity becomes linearly. Further, in the case where the maximum count value CNTmax is less than the value Cl, the light intensity does not change, and similarly, in the case where the maximum count value CNTmax is greater than the value C2, the light intensity does not change either.

[0081] Figure 6B 、 6C Another example of the operation of the light intensity setting section 29 is shown. As shown in Figure 6B , it can also be that the greater the maximum count value, the greater the light intensity becomes stepwise. Further, as shown in Figure 6C , it can also be that the relationship between the light intensity and the maximum count value CNTmax is a relationship other than a linear function.

[0082] Thus, the light intensity setting section 29 decreases the light intensity of the light pulse L1 in a case where the maximum count value CNTmax is small, and increases the light intensity of the light pulse L1 in a case where the maximum count value CNTmax is large. Thereby, in the time measurement device 1, it is possible to decrease the light intensity of the light pulse L1 in a case where the bottom wave W2 is low, and to increase the light intensity of the light pulse L1 in a case where the bottom wave W2 is high, for example.

[0083] According to this configuration, in the time measurement device 1, the light intensity is adjusted based on the plurality of count values CNT supplied from the counting section 123 so that the height of the peak wave W1 exceeds the bottom wave W2, and the height of the peak wave W1 does not become excessively high compared to the bottom wave W2. Thereby, in the time measurement device 1, it is possible to effectively reduce the power consumption.

[0084] Figure 7 An example of mounting of the sensor section 20 is shown. In this example, the sensor section 20 is formed on two semiconductor substrates 111, 112. On the semiconductor substrate 111, a plurality of light receiving elements 31 included in the pixel array 21 is formed, and on the semiconductor substrate 112, elements other than the plurality of light receiving elements 31 in the pixel array 21, the counting section 123, the time measurement section 124, the histogram generation section 125, the processing section 26, and the control section 27 are formed. The semiconductor substrates 111, 112 are overlapped with each other and electrically connected to each other via a so-called TCV (Through Chip Via) or the like, for example. Note that, in this example, the sensor section 20 is formed on two semiconductor substrates 111, 112, but it is not limited thereto, and instead, for example, the sensor section 20 and the light source driving section 12 can be formed on two semiconductor substrates 111, 112. The light source driving section 12 can be formed on the semiconductor substrate 112, for example. Further, for example, the sensor section 20 can be formed on one semiconductor substrate.

[0085] Here, the pixel PZ corresponds to one specific example of the "pixel" in the present application. The pixel signal SIG corresponds to one specific example of the "pulse signal" in the present application. The time measurement section 124 corresponds to one specific example of the "time point detection section" in the present application. The counting section 123 corresponds to one specific example of the "pulse number detection section" in the present application. The control section 27 corresponds to one specific example of the "control section" in the present application.

[0086] [Operation and Effect]

[0087] Next, the operation and effect of the time measurement device 1 of the present embodiment will be described.

[0088] (Overall Operation Summary)

[0089] First, the configuration of the time measurement device 1 of the present embodiment will be described with reference to FIG. 1. Figure 1An outline of the overall operation of the time measurement device 1 will be described. The light source 11 emits a light pulse L1 toward a measurement target. The light source drive section 12 controls the operation of the light source 11 based on the light emission trigger signal S1 supplied from the sensor section 20 so that the light source 11 emits light at the timing corresponding to the trigger pulse included in the light emission trigger signal S1. Further, the light source drive section 12 controls the light intensity of the light pulse L1 emitted by the light source 11 based on the light intensity control signal S2 supplied from the sensor section 20.

[0090] The sensor section 20 generates a depth image PIC by detecting the reflected light pulse L2. Specifically, the selection signal generation section 22 generates a plurality of selection signals SSEL based on the control signal supplied from the control section 27, thereby sequentially selecting a plurality of pixels PZ in units of columns. The selected pixels PZ in the pixel array 21 output a pixel signal SIG including a pulse PU corresponding to the incident reflected light pulse L2. The counter 23 of the counting section 123 counts the number of pulses PU included in the pixel signal SIG based on the control signal supplied from the control section 27. The TDC 24 of the time measurement section 124 measures the timing of the pulses PU included in the pixel signal SIG based on the control signal supplied from the control section 27, thereby generating a depth value D. The histogram generation circuit 25 of the histogram generation section 125 generates a histogram HY of the depth values D supplied from the TDC 24 based on the control signal supplied from the control section 27. The processing section 26 generates a depth image PIC based on the control signal supplied from the control section 27 and the information on a plurality of histograms HY supplied from the histogram generation section 125. The control section 27 supplies the control signals to the selection signal generation section 22, the counting section 123, the time measurement section 124, the histogram generation section 125, and the processing section 26, and supplies the light emission trigger signal S1 and the light intensity control signal S2 to the light source drive section 12, thereby controlling the operation of the time measurement device 1.

[0091] (Detailed Operation)

[0092] Figure 8 An example of the operation of the time measurement device 1 will be described. (A) shows the waveform of the emitted light emitted from the light source 11, (B) shows the operation of the pixel PZ(1) in the first column from the left in the pixel array 21, (C) shows the operation of the pixel PZ(2) in the second column from the left in the pixel array 21, (D) shows the operation of the pixel PZ(3) in the third column from the left in the pixel array 21, (E) shows the operation of the pixel PZ(N) in the rightmost column (Nth column) in the pixel array 21, and (F) shows the operation of the counting section 123. In Figure 8 In (B) to (E), the hatched portions show the pixels PZ that are selected, and the non-hatched portions show the pixels PZ that are not selected. Further, in Figure 8In (F), the hatched portion indicates that the counting section 123 performs the counting operation, and the non-hatched portion indicates that the counting section 123 does not perform the counting operation.

[0093] When the frame period F starts at time t1, first, during the period from time t1 to t3, the selection signal generation section 22 selects the 1st column of pixels PZ(1) (B). Then, the light source drive section 12 controls the operation of the light source 11 during the period from time t1 to t3 based on the light emission trigger signal S1 so that the light source 11 emits light pulses L1 (A) a plurality of times (for example, 1000 times) with a prescribed light emission period (light emission period T). Thereby, the pixel PZ(1) outputs a pixel signal SIG that contains a pulse PU corresponding to the incident reflected light pulse L2. The TDC 24 of the time measurement section 124 generates a depth value D each time the pulse PU appears in the pixel signal SIG. The histogram generation circuit 25 of the histogram generation section 125 generates a histogram HY of the depth values D supplied from the TDC 24 and supplies information about the histogram HY to the processing section 26. Figure 8 Figure 8 (A). Thereby, the pixel PZ(1) outputs a pixel signal SIG that contains a pulse PU corresponding to the incident reflected light pulse L2. The TDC 24 of the time measurement section 124 generates a depth value D each time the pulse PU appears in the pixel signal SIG. The histogram generation circuit 25 of the histogram generation section 125 generates a histogram HY of the depth values D supplied from the TDC 24 and supplies information about the histogram HY to the processing section 26.

[0094] Further, the counter 23 of the counting section 123 counts the number of pulses PU contained in the pixel signal SIG during the period from time t1 to t2. The length of the counting period (the period from time t1 to t2) during which the counter 23 performs the counting operation is set to a time longer than the time corresponding to the period (light emission period T) with which the light source 11 emits the light pulse L1. Then, the counting section 123 supplies the counting results (count values CNT) of the plurality of counters 23 to the light intensity setting section 29 of the control section 27.

[0095] Figure 9 An example of an operation of the time measurement device 1 when the time measurement device 1 is caused to operate in a dark environment, Figure 10 An example of an operation of the time measurement device 1 when the time measurement device 1 is caused to operate in a bright environment. In Figure 9 , 10 In (A), (B) indicates the waveform of the emitted light emitted from the light source 11, and (C) indicates the waveform of the pixel signal SIG.

[0096] In this example, at time t11, the light source 11 emits a light pulse L1, and at time t12, the pixel PZ detects a reflected light pulse L2 and generates a pulse PU (pulse PU1) corresponding to the reflected light pulse L2. Thereby, the histogram HY has a peak W1 at the position of the depth value D corresponding to time t12.

[0097] Further, during the period from time t11 to t13, the pixel PZ generates a pulse PU corresponding to the ambient light and the dark current at a random time. In Figure 9 ​In the example of FIG. 10, since the time measurement device 1 is caused to operate in a dark environment, the occurrence frequency of the pulse PU corresponding to ambient light and dark current is low, and in the example of FIG. 11, since the time measurement device 1 is caused to operate in a bright environment, the occurrence frequency of the pulse PU corresponding to ambient light and dark current is high. Thus, in the example of FIG. 10, the bottom wave W2 is low, and in the example of FIG. 11, the bottom wave W2 is high. Figure 10 Figure 9 Figure 10

[0098] Then, during the period from time t3 to t5, the selection signal generation section 22 selects the pixel PZ(2) of the 2nd column (C). Then, the light source drive section 12 controls the operation of the light source 11 during the period from time t3 to t5 based on the light emission trigger signal S1 so that the light source 11 emits the light pulse L1 (A) a plurality of times (e.g., 1000 times) with a prescribed light emission period (light emission period T). Figure 8 Figure 8 (A). Thus, the pixel PZ(2) outputs the pixel signal SIG containing the pulse PU corresponding to the incident reflected light pulse L2. The TDC 24 generates the depth value D every time the pulse PU appears in the pixel signal SIG. The histogram generation circuit 25 generates the histogram HY of the depth values D supplied from the TDC 24 and supplies information about the histogram HY to the processing section 26.

[0099] Further, the counters 23 of the counting section 123 count the number of pulses PU contained in the pixel signal SIG during the period from time t3 to t4. Then, the counting section 123 supplies the count results (count values CNT) of the plurality of counters 23 to the light intensity setting section 29 of the control section 27.

[0100] Thus, the sensor section 20 sequentially selects a plurality of pixels PZ in column units during the period from time t1 to t7 (frame period F), the histogram generation section 125 generates the histogram HY about all the pixels PZ of the pixel array 21, and the counting section 123 generates the count values CNT about all the pixels PZ of the pixel array 21.

[0101] Then, the processing section 26 generates the depth image PIC based on the information about the histogram HY of all the pixels PZ. Further, the light intensity setting section 29 of the control section 27 generates the light intensity control signal S2 based on the count values CNT of all the pixels PZ and supplies the light intensity control signal S2 to the light source drive section 12. Thus, as shown in FIG. 12 (A), the light intensity of the light pulse L1 emitted in the next frame period F from time t7 is set. Figure 8 (A).

[0102] (Setting of Light Intensity)

[0103] ​​​​The light intensity setting section 29 sets the light intensity of the light pulse Ll, for example, based on the plurality of count values CNT. Specifically, as shown in Figure 6A the light intensity setting section 29 decreases the light intensity of the light pulse Ll in the case where the maximum count value CNTmax is small, and increases the light intensity of the light pulse Ll in the case where the maximum count value CNTmax is large. Thereby, in the time measurement device 1, it is possible to effectively reduce the power consumption. Hereinafter, the operation will be described in detail.

[0104] Figure 11 a histogram HY indicating that the time measurement device 1 is operated in a dark environment, Figure 12 a histogram HY indicating that the time measurement device 1 is operated in a bright environment.

[0105] In the case where the time measurement device 1 is operated in a dark environment, as shown in Figure 9 the count value CNT becomes small and the bottom wave W2 becomes low because the occurrence frequency of the pulse PU corresponding to the ambient light and the dark current is low. The light intensity setting section 29 acquires the maximum value (the maximum count value CNTmax) of the count values CNT with respect to all the pixels PZ based on the count values CNT obtained in a certain frame period F. This maximum count value CNTmax is smaller than the maximum count value CNTmax in the case where the time measurement device 1 is operated in a bright environment. The light intensity setting section 29 sets the light intensity of the light pulse Ll in the next frame period F based on this maximum count value CNTmax. In the case where the maximum count value CNTmax is like this, as shown in Figure 6A the light intensity setting section 29 decreases the light intensity of the light pulse Ll. Thereby, in the time measurement device 1, as shown in Figure 11 the height of the peak wave Wl can be made not to become too high compared with the bottom wave W2.

[0106] Further, in the case where the time measurement device 1 is operated in a bright environment, as shown in Figure 10 the count value CNT becomes large and the bottom wave W2 becomes high because the occurrence frequency of the pulse PU corresponding to the ambient light and the dark current is high. The light intensity setting section 29 acquires the maximum value (the maximum count value CNTmax) of the count values CNT with respect to all the pixels PZ based on the count values CNT obtained in a certain frame period F. This maximum count value CNTmax is larger than the maximum count value CNTmax in the case where the time measurement device 1 is operated in a dark environment. The light intensity setting section 29 sets the light intensity of the light pulse Ll in the next frame period F based on this maximum count value CNTmax. In the case where the maximum count value CNTmax is like this, as shown in Figure 6A the light intensity setting section 29 increases the light intensity of the light pulse Ll. Thereby, in the time measurement device 1, as shown in Figure 12 the height of the peak wave Wl exceeds the bottom wave W2.

[0107] Thus, in the time measurement device 1, the light intensity of the light pulse L1 is adjusted based on the count value CNT supplied from the counting section 123. Specifically, as shown in FIG. 9, the light intensity setting section 29 decreases the light intensity of the light pulse L1 in a case where the maximum count value CNTmax is small, and increases the light intensity of the light pulse L1 in a case where the maximum count value CNTmax is large. Thereby, in the time measurement device 1, the light intensity of the light pulse L1 can be adjusted so that the height of the peak W1 exceeds the bottom wave W2, and the height of the peak W1 does not become excessively high compared to the bottom wave W2. As a result, in the time measurement device 1, the consumed power can be effectively reduced. Figure 6A

[0108] That is, for example, in a case where the time measurement device 1 is caused to operate in a dark environment, when the light intensity of the light pulse L1 is set to be the same as in a case where the time measurement device 1 is caused to operate in a bright environment, as shown in FIG. 8, the height of the peak W1 can become excessively high with respect to the bottom wave W2. In this case, the light source 11 consumes a large amount of power. On the other hand, in the present embodiment, the light intensity of the light pulse L1 is adjusted based on the plurality of count values CNT supplied from the counting section 123, and thus, as shown in FIG. 9, the height of the peak W1 can not become excessively high compared to the bottom wave W2. Thus, in the time measurement device 1, the light intensity of the light pulse L1 can be set to the necessary minimum light intensity with respect to the bottom wave W2, and thus, the power consumed in the light source 11 can be suppressed, and as a result, the consumed power can be effectively reduced. Figure 13 Figure 11

[0109] Further, in the time measurement device 1, the light intensity setting section 29 adjusts the light intensity of the light pulse L1 based on the maximum value (the maximum count value CNTmax) of the count values CNT with respect to all of the pixels PZ. The pixel PZ related to the maximum count value CNTmax is, for example, a case where the pixel PZ in which the bottom wave W2 is the highest among all of the pixels PZ. Therefore, by adjusting the light intensity of the light pulse L1 to this maximum count value CNTmax, the possibility that the peak W1 is buried in the bottom wave W2 in the histogram HY related to a part of the pixels PZ can be reduced.

[0110] [Effects]

[0111] As described above, in the present embodiment, since the light intensity of the light pulse is adjusted based on the count value supplied from the counting section, the consumed power can be effectively reduced.

[0112] In the present embodiment, since the light intensity of the light pulse is adjusted based on the maximum count value, the possibility that the peak is buried in the bottom wave in the histogram HY can be reduced.

[0113] ​​​[Variation Example 1-1]

[0114] In the above embodiment, the sensor unit 20 supplies a light emission trigger signal S1 to the light source driving unit 12, and the sensor unit 20 controls the operation of the light source 11, but it is not limited to this. Alternatively, for example... Figure 14 As shown in the time measuring device 1A, the light source driving unit supplies a trigger signal indicating the operation time to the sensor unit. The time measuring device 1A includes a light source driving unit 12A and a sensor unit 20A. The light source driving unit 12A generates a trigger signal S3 indicating the operation time of the sensor unit 20A and supplies the trigger signal S3 to the sensor unit 20A. The sensor unit 20A operates based on the trigger signal S3.

[0115] [Variations 1-2]

[0116] In the above embodiment, the light intensity of the light pulse L1 is adjusted based on the maximum value (maximum count value CNTmax) of the count values ​​CNT for all pixels PZ, but it is not limited to this. For example, when the count values ​​CNT for all pixels PZ are approximately equal, the light intensity setting unit 29 can adjust the light intensity of the light pulse L1 based on the average value of the count values ​​CNT for all pixels PZ. In this case, for example, even if there is a faulty pixel PZ, it is possible to suppress the influence of the faulty pixel PZ on the light intensity.

[0117] [Variations 1-3]

[0118] In the above embodiment, by setting a plurality of counters 23 equal to the number of signal lines SGL, the count value CNT of all pixels PZ can be obtained, but this is not a limitation. Alternatively, for example, a smaller number of counters 23 can be set to obtain the count value CNT of a subset of pixels PZ. The number of counters 23 can be multiple, or for example, as follows: Figure 15 There is one sensor unit 20C as shown. This sensor unit 20C includes a counter 23 and a control unit 27C. The counter 23 is connected to one of the multiple signal lines SGL of the pixel array 21 (in this example, the uppermost signal line SGL), and counts the number of pulses PU contained in the pixel signal SIG supplied from the pixel array 21 via the signal line SGL based on a control signal supplied from the control unit 27C. Thus, the counter 23 obtains the count value CNT of the multiple pixels PZ connected to the signal line SGL. Then, the counter 23 supplies these count values ​​CNT to the control unit 27C. The control unit 27C includes a light intensity setting unit 29C. The light intensity setting unit 29C generates a light intensity control signal S2 indicating the light intensity of the light pulse L1 based on the multiple count values ​​CNT supplied from the counter 23.

[0119] [Modified example 1-4]

[0120] In the above embodiment, the sensor section 20 supplies the light source drive section 12 with the light intensity control signal S2, but it is not limited thereto. Hereinafter, several examples will be described.

[0121] Figure 16 A configuration example of a time measuring apparatus ID pertaining to the present modified example will be described. The time measuring apparatus ID is provided with a light source drive section 12D and a sensor section 20D. The light source drive section 12D has a light intensity setting section 17D. The light intensity setting section 17D is identical to the light intensity setting section 29 pertaining to the above embodiment, and sets the light intensity of the light pulse LI emitted from the light source 11 based on the count value CNT supplied from the sensor section 20D.

[0122] Figure 17 A configuration example of the sensor section 20D will be described. The sensor section 20D has a counter 23 and a control section 27D. The counter 23 is connected to one of the plurality of signal lines SGL of the pixel array 21 (in this example, the uppermost signal line SGL), and counts the number of pulses PU included in the pixel signal SIG supplied from the pixel array 21 via the signal line SGL based on the control signal supplied from the control section 27C. Thereby, the counter 23 obtains the count values CNT of the plurality of pixels PZ connected to this signal line SGL. Then, the counter 23 supplies these count values CNT to the light intensity setting section 17D of the light source drive section 12D. The control section 27D omits the light intensity setting section 29 from the control section 27 of the above embodiment.

[0123] Figure 18 A configuration example of a time measuring apparatus IE pertaining to the present modified example will be described. The time measuring apparatus IE is provided with a light source drive section 12E and a sensor section 20E. The light source drive section 12E has a counter 16E and a light intensity setting section 17D. The counter 16E is identical to the counter 23 pertaining to the above embodiment, and counts the number of pulses PU included in the pixel signal SIG. Then, the counter 16E supplies the count result (count value CNT) to the light intensity setting section 17D. The light intensity setting section 17D sets the light intensity of the light pulse LI emitted from the light source 11 based on the count value CNT supplied from the counter 16E.

[0124] Figure 19This illustrates one configuration example of the sensor unit 20E. The sensor unit 20E includes a control unit 27E. The sensor unit 20E supplies one of the multiple pixel signals SIG generated by the pixel array 21 to the counter 16E of the light source driving unit 12E. The control unit 27E omits the light intensity setting unit 29 and the function of controlling the operation of the counter 23, as described in the control unit 27 of the above embodiment.

[0125] [Variations 1-5]

[0126] In the above embodiment, the pixel signal SIG generated by the pixel PZ used to determine the depth value D is supplied to the counter 23, but this is not a limitation. Alternatively, for example, ... Figure 20 As shown in the sensor unit 20F, pixel signals SIG generated by pixels other than pixel PZ used to determine the depth value D are supplied to the counter 23. The sensor unit 20F includes a pixel array 21F and a counter 23. The pixel array 21F has multiple virtual pixels PDMs. The circuit structure of the virtual pixels PDMs is similar to the circuit structure of pixel PZ (…). Figure 3 The same applies. Multiple virtual pixels (PDMs) are connected to one signal line (SGL). Here, pixel PZ corresponds to a specific example of the "first pixel" in this invention. Virtual pixel PDMs correspond to a specific example of the "second pixel" in this invention. Counter 23 is connected to the signal line (SGL) to which the multiple virtual pixel PDMs are connected. Counter 23 counts the number of pulses PU contained in the pixel signal SIG supplied from the virtual pixel PDMs.

[0127] [Variations 1-6]

[0128] In the above embodiment, multiple counters 23 are provided, and the light intensity of the light pulse L1 is set based on the count values ​​CNT of these counters 23, but this is not a limitation. Alternatively, for example, Figure 21As shown in the sensor unit 20G, the light intensity of the light pulse L1 is set based on the histogram HY generated by the histogram generation circuit 25. The sensor unit 20G includes a histogram generation unit 125G and a control unit 27G. The histogram generation unit 125G has the function of supplying information about the bottom wave W2 from the histograms HY generated by the multiple histogram generation circuits 25 to the control unit 27G. The control unit 27G includes a control unit 27G and a light intensity setting unit 29G. The light intensity setting unit 29G sets the light intensity of the light pulse L1 based on the information about the bottom wave W2 supplied from the histogram generation unit 125G. Specifically, the light intensity setting unit 29G sets the light intensity of the light pulse L1, for example, based on the highest bottom wave W2 among the bottom waves W2 included in the multiple histograms HY. For example, the light intensity setting unit 29G decreases the light intensity of the light pulse L1 when the bottom wave W2 is low, and increases the light intensity of the light pulse L1 when the bottom wave W2 is high. Then, the light intensity setting unit 29G generates a light intensity control signal S2 that indicates the light intensity of the light pulse L1 based on the set light intensity of the light pulse L1. Here, the histogram generation unit 125G corresponds to a specific example of the "pulse number detection unit" in this invention.

[0129] [Variations 1-7]

[0130] In the above embodiment, pixels PZ are selected in the pixel array 21 on a column-by-column basis, but this is not a limitation. Alternatively, for example, ... Figure 22 As shown in the sensor unit 20H, pixels PZ are selected in units of multiple columns (in this example, in units of two columns). The sensor unit 20H has a pixel array 21H. The pixel array 21H has multiple selection lines SEL, multiple signal lines SGL, and multiple pixels PZ. For example, the multiple pixels PZ in the first and second columns from the left are connected to the first selection line SEL from the left. Furthermore, the multiple pixels PZ in the third and fourth columns are connected to the second selection line SEL. The same applies to the fifth column and beyond. Additionally, for example, in the first row, pixels PZ belonging to odd-numbered columns and pixels PZ belonging to even-numbered columns are connected to different signal lines SGL. The same applies to the second row and beyond. According to this structure, pixels PZ are selected in units of two columns in the sensor unit 20H.

[0131] [Variations 1-8]

[0132] In the above embodiment, the counting unit 123 and the time measuring unit 124 operate during the same period, but this is not a limitation. Alternatively, for example, the counting unit 123 may operate in advance to set the light intensity of the light pulse L1, and then the light source 11 may generate the light pulse L1 based on the set light intensity, thereby generating a depth image PIC by the time measuring device 1.

[0133] [Other modifications]

[0134] Furthermore, two or more of these modifications can be combined.

[0135] <2. Second Embodiment>

[0136] Next, the time measurement device 2 according to the second embodiment will be described. This embodiment adjusts the number of light pulses L1 based on a plurality of count values CNT. In addition, the same reference numerals are assigned to the substantially same components as those of the time measurement device 1 according to the first embodiment, and the description will be appropriately omitted.

[0137] Figure 23 A configuration example of the time measurement device 2 will be described. The time measurement device 2 includes a light source driving section 42 and a sensor section 40.

[0138] The light source driving section 42 drives the light source 11 based on an instruction from the sensor section 40. Specifically, the light source driving section 42 controls the operation of the light source 11 based on the light emission trigger signal S1 supplied from the sensor section 40 so that the light source 11 emits light at a timing corresponding to a trigger pulse included in the light emission trigger signal S1. In this example, the number of trigger pulses varies. Thus, in the time measurement device 2, the number of light pulses L1 can be changed.

[0139] The sensor section 40 generates a depth image PIC having information on the distance to the measurement target object by detecting the reflected light pulse L2. In addition, the sensor section 40 has a function of generating the light emission trigger signal S1 and supplying the light emission trigger signal S1 to the light source driving section 42.

[0140] Figure 24 A configuration example of the sensor section 40 will be described. The sensor section 40 includes a control section 47. The control section 47 supplies a control signal to the selection signal generating section 22, the counting section 123, the time measurement section 124, the histogram generating section 125, and the processing section 26, and controls the operation of the time measurement device 2 by supplying the light emission trigger signal S1 to the light source driving section 42. The control section 47 includes a light pulse number setting section 49 and a light emission timing setting section 48.

[0141] The light pulse number setting section 49 sets the number of light pulses Ll emitted by the light source 11 based on the plurality of count values CNT supplied from the counting section 123. Specifically, the light pulse number setting section 49 sets the number of light pulses Ll for the next frame period F based on, for example, the maximum value (maximum count value CNTmax) of the plurality of count values CNT for all the pixels PZ obtained during a certain frame period F. For example, the light pulse number setting section 49 reduces the number of light pulses Ll in the case where the maximum count value CNTmax is small, and increases the number of light pulses Ll in the case where the maximum count value CNTmax is large.

[0142] The light emission timing setting section 48 generates a light emission trigger signal S1 indicating the light emission timing of the light source 11 based on the number of light pulses Ll set by the light pulse number setting section 49.

[0143] Figure 25 An example of the light pulse Ll generated by the light source 11 of the time measurement device 2 is shown. In this example, the light source 11 emits light pulses Ll at a prescribed light emission period during the initial frame period F (time t21 to t22). Also, in this example, the maximum count value CNTmax obtained during this frame period F is small, and therefore the light pulse number setting section 49 sets the number of light pulses Ll to a small number. The light emission timing setting section 48 sets the light emission timing of the light source 11 in such a way that the light pulses Ll are emitted sparsely based on the number of light pulses Ll set by the light pulse number setting section 49. As a result, as shown in FIG. 23, the light source 11 emits a smaller number of light pulses Ll during the next frame period F (time t22 to t23) than during the time t21 to t22. Figure 25

[0144] Thus, in the time measurement device 2, the light pulse number setting section 49 adjusts the number of light pulses Ll based on the count value CNT supplied from the counting section 123. Specifically, the light pulse number setting section 49 reduces the number of light pulses Ll in the case where the maximum count value CNTmax is small, and increases the number of light pulses Ll in the case where the maximum count value CNTmax is large. As a result, in the time measurement device 2, as in the time measurement device 1, the number of light pulses Ll can be adjusted so that the height of the peak Wl exceeds the bottom wave W2, and the height of the peak Wl does not become excessively high compared to the bottom wave W2. As a result, in the time measurement device 2, the power consumption of the light source 11 can be effectively reduced.

[0145] Further, in the case where the number of light pulses Ll is reduced, the operation time of the counting section 123 and the time measurement section 124 becomes shorter, and the amount of computation of the histogram generation section 155 and the processing section 26 becomes smaller. As a result, the power consumption in the counting section 123, the time measurement section 124, the histogram generation section 125, and the processing section 26 can be effectively reduced. ​

[0146] As described above, in this embodiment, since the number of light pulses is adjusted based on the count value supplied from the counting unit, power consumption can be effectively reduced.

[0147] [Variation Example 2]

[0148] The various modifications of the first embodiment described above can also be applied to the time measuring device 2 described in the above embodiments.

[0149] <3. Third Implementation>

[0150] Next, the time measuring device 3 according to the third embodiment will be described. In this embodiment, the operation of the light source 11 is stopped when the height of the peak W1 in the histogram HY reaches the threshold TH corresponding to the bottom wave W2. In addition, the same reference numerals are used to mark the components that are substantially the same as those in the time measuring device 1 according to the first embodiment, and descriptions are omitted as appropriate.

[0151] like Figure 23 As shown, the time measuring device 3 includes a sensor unit 50. The sensor unit 50 generates a depth image PIC containing information about the distance to the object being measured by detecting a reflected light pulse L2. Furthermore, the sensor unit 50 has the function of generating a light emission trigger signal S1 and supplying this light emission trigger signal S1 to the light source driving unit 42.

[0152] Figure 26 This illustrates one configuration example of the sensor unit 50. The sensor unit 50 includes a histogram generation unit 155 and a control unit 57.

[0153] The histogram generation unit 155 has multiple histogram generation circuits 25 (histogram generation circuits 25(1), 25(2), 25(3), ...). Based on a threshold TH supplied from the control unit 57, the histogram generation unit 155 checks whether the height of the peak W1 in the histogram HY generated by the multiple histogram generation circuits 25 reaches the threshold TH. Then, the histogram generation unit 155 generates a stop signal STP when the height of the peak W1 in all histograms HY related to a column of pixels PZ reaches the threshold TH. The histogram generation unit 155 then supplies the stop signal STP to the control unit 57.

[0154] The control unit 57 controls the operation of the time measuring device 3 by supplying control signals to the selection signal generation unit 22, the counting unit 123, the time measuring unit 124, the histogram generation unit 155, and the processing unit 26, and by supplying a light emission trigger signal S1 to the light source driving unit 42. The control unit 57 includes a threshold setting unit 59 and a light emission timing setting unit 58.

[0155] The threshold setting unit 59 generates a threshold TH based on a plurality of count values ​​CNT supplied from the counting unit 123. Specifically, the threshold setting unit 59 sets the threshold TH to be used in the next frame period F based, for example, on the maximum value (maximum count value CNTmax) of the plurality of count values ​​CNT obtained for all pixels PZ during a certain frame period F. For example, the threshold setting unit 59 lowers the threshold TH when the maximum count value CNTmax is small, and raises the threshold TH when the maximum count value CNTmax is large.

[0156] The emission timing setting unit 58 generates an emission trigger signal S1 that indicates the emission timing of the light source 11. Then, the emission timing setting unit 58 stops generating the emission trigger signal S1 based on the stop signal STP supplied from the histogram generation unit 155.

[0157] Figure 27 The histogram HY represents the time measuring device 3 operating in a dark environment. Figure 28 The histogram HY represents the time measuring device 3 operating in a bright environment.

[0158] When the time measuring device 3 operates in a dark environment, the count value CNT is small, so the threshold setting unit 59... Figure 27 The threshold TH is lowered as shown. Then, during the next frame, F is lowered as shown. Figure 27 As shown, when the heights of the peaks W1 in all histograms HY related to pixel PZ in the first column reach the threshold TH, the histogram generation unit 155 generates a stop signal STP. Therefore, the light source 11 stops generating the light pulse L1. The same applies to the second column and thereafter. Thus, in the time measuring device 3, as... Figure 27 As shown, this ensures that the height of the peak W1 is not too high compared to the bottom wave W2.

[0159] Furthermore, when the time measuring device 3 operates in a bright environment, the threshold setting unit 59, due to the large count value CNT, will... Figure 28 Increase the threshold TH as shown. Then, during the next frame, F, as shown... Figure 28 As shown, when the heights of the peaks W1 in all histograms HY related to pixel PZ in the first column reach the threshold TH, the histogram generation unit 155 generates a stop signal STP. Therefore, the light source 11 stops generating the light pulse L1. The same applies to the second column and thereafter. Thus, in the time measuring device 3, as... Figure 28 As shown, this allows the height of the crest W1 to exceed that of the bottom wave W2.

[0160] Thus, in the time measurement device 3, the threshold value TH is set based on the count value CNT supplied from the counting section 123. Specifically, the threshold value setting section 59 lowers the threshold value TH in the case where the maximum count value CNTmax is small, and raises the threshold value TH in the case where the maximum count value CNTmax is large. Then, in the time measurement device 3, when the height of the peak Wl in the histogram HY reaches the threshold value TH, the generation of the light pulse Ll is stopped. Thus, in the time measurement device 3, as in the time measurement device 1, the number of light pulses Ll can be adjusted so that the height of the peak Wl exceeds the bottom wave W2, and the height of the peak Wl does not become excessively high compared to the bottom wave W2. As a result, in the time measurement device 3, the power consumption of the light source 11 can be effectively reduced.

[0161] Further, in the case where the number of light pulses Ll is reduced, the operation time of the counting section 123 and the time measurement section 124 becomes short, and the amount of calculation of the histogram generation section 155 and the processing section 26 becomes small. Thus, the power consumption of the counting section 123, the time measurement section 124, the histogram generation section 155, and the processing section 26 can be effectively reduced.

[0162] As described above, in the present embodiment, the threshold value is set based on the count value supplied from the counting section, and when the height of the peak in the histogram reaches the threshold value, the generation of the light pulse is stopped, whereby the power consumption can be effectively reduced.

[0163] <4. Application Examples>

[0164] Next, application examples of the time measurement device according to the above-described embodiments will be described.

[0165] Figure 29 An example of a configuration of a camera 9 is shown. The camera 9 applies the technology according to the time measurement device 1 of the first embodiment to a camera. In addition, it is not limited thereto, and the technology according to the time measurement device 2 of the second embodiment or the technology according to the time measurement device 3 of the third embodiment can also be applied to the camera. The camera 9 is provided with an imaging section 60.

[0166] The imaging section 60 generates an imaging image PIC2 by performing an imaging operation. Further, the imaging section 60 also has a function of generating a depth image PIC by detecting the reflected light pulse L2 when the light source 11 is caused to operate. Then, the imaging section 60 outputs the generated imaging image PIC2 and the depth image PIC. Further, the imaging section 60 also has a function of generating the light emission trigger signal S1 and the light intensity control signal S2 when the depth image PIC is generated, and supplying these light emission trigger signal S1 and the light intensity control signal S2 to the light source drive section 12.

[0167] Figure 30A configuration example of the imaging section 60 is shown. The imaging section 60 has the pixel array 61, the counting section 163, and the processing section 66.

[0168] The pixel array 61 has a plurality of pixels P. The plurality of pixels P includes a plurality of red pixels PR, a plurality of green pixels PG, a plurality of blue pixels PB, and a plurality of pixels PZ. The red pixels PR detect light of red, the green pixels PG detect light of green, and the blue pixels PB detect light of blue. The circuit structure of the red pixels PR, the green pixels PG, and the blue pixels PB is the same as that of the pixel PZ. Figure 3 ) In the red pixels PR, a red filter is formed, in the green pixels PG, a green filter is formed, and in the blue pixels PB, a blue filter is formed.

[0169] Figure 31 A configuration example of the red pixels PR, the green pixels PG, the blue pixels PB, and the pixel PZ in the pixel array 61 is shown. In the pixel array 61, four pixels (unit U) configured in two rows and two columns are repeatedly configured. In the unit U, the green pixel PG is configured at the upper left, the blue pixel PB is configured at the lower left, the red pixel PR is configured at the upper right, and the pixel PZ is configured at the lower right.

[0170] Further, as shown in Figure 30 , the pixel array 61 has a plurality of selection lines SEL, a plurality of signal lines SGL, and a plurality of signal lines SGL2. The plurality of signal lines SGL respectively extend along the lateral direction of Figure 30 , as shown in Figure 30 , one end is connected to the time measuring section 124. The plurality of signal lines SGL2 respectively extend along the lateral direction of Figure 30 , as shown in Figure 30 , one end is connected to the counting section 163.

[0171] In the unit U, the green pixel PG and the blue pixel PB are connected to the same selection line SEL, and the red pixel PR and the pixel PZ are connected to a selection line SEL different from the selection line SEL to which the green pixel PG and the blue pixel PB are connected. Further, in the unit U, the green pixel PG and the red pixel PR are connected to the same signal line SGL2, and the blue pixel PB is connected to a signal line SGL2 different from the signal line SGL2 to which the green pixel PG and the red pixel PR are connected. Further, the pixel PZ is connected to the signal line SGL.

[0172] The counter section 163 has a plurality of counters 63 (counters 63(1), 63(2), 63(3), 63(4),...). The plurality of counters 63 are connected to the plurality of signal lines SGL2 in the pixel array 21, respectively. The plurality of counters 63 count the number of the pulses PU included in the pixel signal SIG supplied from the pixel array 61 via the signal line SGL2, respectively, on the basis of the control signal supplied from the control section 27. Then, the counter section 163 supplies the count results in the plurality of counters 63 to the processing section 66. Further, the counter section 163 has a function of supplying the count results (count values CNT) in the plurality of counters 63 to the light intensity setting section 29 of the control section 27.

[0173] The processing section 66 generates the captured image PIC2 on the basis of the count results supplied from the counter section 163. Then, the processing section 66 outputs the generated captured image PIC2.

[0174] Here, the pixel PZ corresponds to one specific example of the "first pixel" in the present application. The red pixel PR, the green pixel PG, and the blue pixel PB correspond to one specific example of the "second pixel" in the present application.

[0175] In the imaging device 9, the plurality of red pixels PR, the plurality of green pixels PG, and the plurality of blue pixels PB in the pixel array 61 output the pixel signal SIG, and the plurality of counters 63 of the counter section 163 count the number of the pulses PU included in the pixel signal SIG. Then, the processing section 66 generates the captured image PIC2 on the basis of the count results in the plurality of counters 63.

[0176] Further, in a case where the imaging device 9 generates the depth image PIC, the counter section 163 supplies the count results (count values CNT) in the plurality of counters 63 to the light intensity setting section 29 of the control section 27. The light intensity setting section 29 sets the light intensity of the light pulse L1 on the basis of the plurality of count values CNT supplied from the counter section 163. The light source 11 generates the light pulse L1 on the basis of the set light intensity. The pixel PZ in the pixel array 61 outputs the pixel signal SIG including the pulse PU corresponding to the reflected light pulse L2. The TDC 24 of the time measurement section 124 measures the time of the pulse PU included in the pixel signal SIG on the basis of the control signal supplied from the control section 27, thereby generating the depth value D. The histogram generation circuit 25 of the histogram generation section 125 generates the histogram HY of the depth values D supplied from the TDC 24 on the basis of the control signal supplied from the control section 27. The processing section 26 outputs the depth image PIC on the basis of the control signal supplied from the control section 27 and the information on the plurality of histograms HY supplied from the histogram generation section 125.

[0177] Thus, in the imaging device 9, the count value CNT obtained by the counting section 163 used in the imaging operation can be used to set the light intensity of the light pulse L1 based on the count value CNT. Thus, it is not necessary to separately provide a light intensity setting section for the counting section 163 Figure 2 The counting section 123 illustrated above can thus reduce the circuit size.

[0178] The above describes the present technology by citing several embodiments, modifications, and specific application examples thereof, but the present technology is not limited to these embodiments and the like, and various modifications can be made.

[0179] For example, in each of the above-described embodiments, the time measurement device is configured using a plurality of pixels PZ, but is not limited thereto, and can alternatively be configured using, for example, one pixel PZ. In this case, the time difference between the time at which the emission light is emitted and the time at which the reflected light reflected by the measurement target is detected can also be measured by emitting the emission light and detecting the reflected light.

[0180] In addition, the effects described in this specification are only examples and are not limiting. Other effects can be obtained.

[0181] In addition, the present technology can be formed as a structure as follows.

[0182] (1) A time measurement device including:

[0183] a pixel having a light-receiving element and capable of generating a pulse signal including a logic pulse based on a light-receiving result of the light-receiving element;

[0184] a time point detection section capable of detecting a light-receiving time point of the light-receiving element based on the pulse signal;

[0185] a pulse number detection section capable of detecting a pulse number of the logic pulse included in the pulse signal; and

[0186] a control section capable of controlling an operation of a light source that emits a plurality of light pulses based on the pulse number.

[0187] (2) In the time measurement device described in the above (1),

[0188] the control section is capable of controlling a light intensity of each of the plurality of light pulses based on the pulse number.

[0189] (3) In the time measurement device described in the above (2),

[0190] the control section is capable of setting the light intensity to a first light intensity in a case where the pulse number is a first pulse number, and is capable of setting the light intensity to a second light intensity that is stronger than the first light intensity in a case where the pulse number is a second pulse number that is larger than the first pulse number.

[0191] (4) In the time measurement device described in (1),

[0192] The control section can control the number of light pulses of the plurality of light pulses based on the number of pulses.

[0193] (5) In the time measurement device described in (4),

[0194] The control section can set the number of light pulses to a first number of light pulses when the number of pulses is a first number of pulses, and can set the number of light pulses to a second number of light pulses that is larger than the first number of light pulses when the number of pulses is a second number of pulses that is larger than the first number of pulses.

[0195] (6) In the time measurement device described in (1),

[0196] The time measurement device further includes a histogram generation section that can generate a histogram with respect to the light reception time based on the light reception time.

[0197] (7) In the time measurement device described in (6),

[0198] The control section can stop the operation of the light source when a peak of the histogram reaches a threshold value corresponding to the number of pulses.

[0199] (8) In the time measurement device described in (7),

[0200] The control section can set the threshold value to a first threshold value when the number of pulses is a first number of pulses, and can set the threshold value to a second threshold value that is larger than the first threshold value when the number of pulses is a second number of pulses that is larger than the first number of pulses.

[0201] (9) In any one of the time measurement devices described in (1) to (8),

[0202] The number of pulse detection section can detect the number of pulses based on the pulse signal.

[0203] (10) In any one of the time measurement devices described in (1) to (8),

[0204] The number of pulse detection section can detect the number of pulses by generating a histogram with respect to the light reception time based on the light reception time.

[0205] (11) In any one of the time measurement devices described in (1) to (10),

[0206] The time-of-illumination detecting section can detect the time of illumination of the first light-receiving element based on the time of emission of the light pulse.

[0207] (12) In the time measurement device described in any one of (1) to (11),

[0208] The time measurement device further includes the light source.

[0209] (13) A time measurement device including:

[0210] a first pixel including a first light-receiving element and capable of generating a first pulse signal including a logic pulse based on a result of light reception by the first light-receiving element;

[0211] a second pixel including a second light-receiving element and capable of generating a second pulse signal including a logic pulse based on a result of light reception by the second light-receiving element;

[0212] a time-of-illumination detecting section capable of detecting a time of illumination of the first light-receiving element based on the first pulse signal;

[0213] a pulse number detecting section capable of detecting a number of pulses of the logic pulse included in the second pulse signal; and

[0214] a control section capable of controlling operation of a light source that emits a plurality of light pulses based on the number of pulses.

[0215] (14) In the time measurement device described in (13),

[0216] The second light-receiving element can receive light of a prescribed color.

[0217] This application is based on Japanese Patent Application No. 2018-099515 filed on May 24, 2018 with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0218] Various modifications, combinations, sub-combinations, and alterations can occur to one of ordinary skill in the art based on the disclosure herein, which are intended to be within the scope of the claims and the equiva lents thereof.

Claims

1. A time measuring device, characterized by, Possess: a pixel having a light-receiving element capable of receiving a reflected light pulse reflected by a measurement target and outputting a light-receiving result based on the reflected light pulse, the pixel being capable of generating a pulse signal containing a logical pulse corresponding to the reflected light pulse based on the light-receiving result of the light-receiving element; a time point detection section capable of detecting a light-receiving time point of the light-receiving element based on the pulse signal; a pulse number detection section capable of detecting a number of the logical pulses contained in the pulse signal; and a control section capable of controlling an operation of a light source that emits a plurality of light pulses toward the measurement target based on the number of pulses.

2. The time measurement device according to claim 1, wherein the control section is capable of controlling a light intensity of each of the plurality of light pulses based on the number of pulses.

3. The time measurement device according to claim 2, wherein the control section is capable of setting the light intensity to a first light intensity in a case where the number of pulses is a first number of pulses, and is capable of setting the light intensity to a second light intensity stronger than the first light intensity in a case where the number of pulses is a second number of pulses larger than the first number of pulses.

4. The time measurement device according to claim 1, wherein the control section is capable of controlling a number of light pulses of the plurality of light pulses based on the number of pulses.

5. The time measurement device according to claim 4, wherein the control section is capable of setting the number of light pulses to a first number of light pulses in a case where the number of pulses is a first number of pulses, and is capable of setting the number of light pulses to a second number of light pulses larger than the first number of light pulses in a case where the number of pulses is a second number of pulses larger than the first number of pulses.

6. The time measurement device according to claim 1, further comprising a histogram generation section capable of generating a histogram with respect to the light-receiving time point based on the light-receiving time point.

7. The time measurement device according to claim 6, wherein the control section is capable of stopping the operation of the light source when a peak of the histogram reaches a threshold value corresponding to the number of pulses.

8. The time measurement device according to claim 7, wherein the control section is capable of setting the threshold value to a first threshold value in a case where the number of pulses is a first number of pulses, and is capable of setting the threshold value to a second threshold value larger than the first threshold value in a case where the number of pulses is a second number of pulses larger than the first number of pulses.

9. The time measurement device according to claim 1, wherein the pulse number detection section is capable of detecting the number of pulses based on the pulse signal.

10. The time measurement device according to claim 1, wherein the pulse number detection section is capable of detecting the number of pulses by generating a histogram with respect to the light-receiving time point based on the light-receiving time point.

11. The time measurement device according to claim 1, wherein the time point detection section is capable of detecting the light-receiving time point with reference to a light-emitting time point of the light pulse. ​ 12. The time measuring apparatus according to claim 1, characterized by the time measuring apparatus further comprises the light source.

13. A time measuring device, characterized by comprises: a first pixel having a first light-receiving element capable of receiving a reflected light pulse reflected by a measurement target and outputting a light-receiving result based on the reflected light pulse, the first pixel being capable of generating a first pulse signal containing a logic pulse corresponding to the reflected light pulse based on the light-receiving result of the first light-receiving element; a second pixel having a second light-receiving element capable of receiving a reflected light pulse reflected by the measurement target and outputting a light-receiving result based on the reflected light pulse, the second pixel being capable of generating a second pulse signal containing a logic pulse corresponding to the reflected light pulse based on the light-receiving result of the second light-receiving element; a time point detecting section capable of detecting a light-receiving time point of the first light-receiving element based on the first pulse signal; a pulse number detecting section capable of detecting a pulse number of the logic pulse contained in the second pulse signal; and a control section capable of controlling an operation of a light source that emits a plurality of light pulses toward the measurement target based on the pulse number.

14. The time measuring apparatus according to claim 13, characterized in that the second light-receiving element is capable of receiving light of a prescribed color.

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