Distance measurement systems and electronics

Abstract

A system includes: a processor; a light source controlled by the processor and configured to emit light; and an event-based visual sensor controlled by the processor. The sensor includes a plurality of pixels. At least one of the plurality of pixels includes a photosensor configured to detect incident light; and a first circuit configured to output a first signal based on an output from the photosensor. The first signal represents a change in the amount of incident light. The sensor also includes a comparator configured to output a comparison result based on at least one of a first reference voltage and a second reference voltage and the first signal. The processor is configured to selectively apply one of the first reference voltage and the second reference voltage to the comparator based on operation of the light source.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority from Japanese patent application JP 2019-154499, filed on August 27, 2019, which is hereby incorporated by reference herein in its entirety. Technical Field

[0003] The present disclosure relates to ranging systems and electronic devices. Background Art

[0004] As a system for acquiring three-dimensional (3D) images (depth information / depth level information of an object's surface) and measuring the distance to a subject, a structured light-related technology has been proposed (for example, see PTL 1). This technology uses a dynamic projector and a dynamic vision camera. According to the structured light-related technology, the dynamic projector projects a predetermined pattern of light onto a measurement target / subject, analyzes the distortion of the pattern based on the imaging results obtained by the dynamic vision camera, and acquires depth information / distance information.

[0005] PTL 1 discloses a technology that uses a vertical-cavity surface-emitting laser (VCSEL) as a dynamic projector's light source and an event detection sensor called a dynamic vision sensor (DVS) as a dynamic vision camera's light receiving unit. The event detection sensor detects as an event a change in the brightness of a pixel that performs photoelectric conversion on incident light that exceeds or equals a predetermined threshold.

[0006] List of citations

[0007] Patent Literature

[0008] PTL 1: U.S. Patent Publication No. US2019 / 0045173A1 Summary of the Invention

[0009] Technical issues

[0010] According to the related art described in PTL 1 listed above, if the dynamic projector and event detection sensor are not controlled synchronously with each other, event information generated by changes in background light or the pattern projected on the subject and event information generated by the subject's movement will appear mixed. As a result, in order to obtain the event information generated by the subject's movement, the application processor that processes the event information must perform separation processing on the mixed multiple pieces of event information. However, the related art described in PTL 1 does not consider controlling the dynamic projector and event detection sensor synchronously with each other.

[0011] It is desirable to provide a distance measurement system and an electronic device including the distance measurement system, wherein the distance measurement system can output event information generated due to motion of a subject but does not include event information generated due to other reasons.

[0012] Technical solutions to the problem

[0013] According to an embodiment of the present disclosure, a system is provided, comprising: a processor; a light source controlled by the processor and configured to emit light; and an event-based visual sensor controlled by the processor. The event-based visual sensor comprises a plurality of pixels and a comparator. At least one of the plurality of pixels comprises: a photosensor configured to detect incident light; and a first circuit configured to output a first signal based on an output from the photosensor. The first signal represents a change in the amount of incident light. The comparator is configured to output a comparison result based on at least one of a first reference voltage and a second reference voltage and the first signal. The processor is configured to selectively apply one of the first reference voltage and the second reference voltage to the comparator based on the operation of the light source.

[0014] According to one aspect of the present disclosure, there is provided a system, wherein the operation is one of a switch-on event signal detection and a switch-off event signal detection.

[0015] According to one aspect of the present disclosure, there is provided a system, wherein when the first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores power-on event data in a memory of the system.

[0016] According to one aspect of the present disclosure, there is provided a system, wherein when the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores turn-off event data in the memory.

[0017] According to one aspect of the present disclosure, there is provided a system, wherein the stored power-on event data and the power-off event data are sequentially transmitted to a readout circuit.

[0018] According to one aspect of the present disclosure, a system is provided, wherein the light source is a vertical cavity surface emitting laser.

[0019] According to one aspect of the present disclosure, there is provided a system, wherein the stored power-on event data and the power-off event data are used to perform face detection processing.

[0020] According to an embodiment of the present disclosure, a system is provided, comprising: an image sensor configured to output an image signal; a light source configured to emit light; and an event-based vision sensor configured to output an event signal. The event-based vision sensor comprises a plurality of pixels and a comparator. At least one of the plurality of pixels comprises: a photosensor configured to detect incident light; and a first circuit configured to output a first signal based on an output from the photosensor. The first signal represents a change in the amount of incident light. The comparator is configured to output a comparison result based on at least one of a first reference voltage and a second reference voltage and the first signal. The system further comprises: a system controller configured to synchronously control the event-based vision sensor and the light source; and a processor. The processor is configured to process the image signal and the event signal. The system controller selectively applies the first reference voltage and the second reference voltage to the comparator based on the operation of the light source.

[0021] According to one aspect of the present disclosure, a system is provided, wherein the image sensor comprises an RGB camera.

[0022] According to one aspect of the present disclosure, there is provided a system, wherein the operation is one of a switch-on event signal detection and a switch-off event signal detection.

[0023] According to one aspect of the present disclosure, there is provided a system, wherein when the first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores power-on event data in a memory of the system.

[0024] According to one aspect of the present disclosure, there is provided a system, wherein when the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores turn-off event data in the memory.

[0025] According to one aspect of the present disclosure, there is provided a system, wherein the stored power-on event data and the power-off event data are sequentially transmitted to a readout circuit.

[0026] According to one aspect of the present disclosure, there is provided a system, wherein the stored power-on event data and the power-off event data are used to perform face detection processing.

[0027] According to one aspect of the present disclosure, a system is provided, wherein the power-on event data and the power-off event data are used to generate a depth map.

[0028] According to one aspect of the present disclosure, a system is provided, wherein the depth map is used for recognizing a face.

[0029] According to one aspect of the present disclosure, there is provided a system, wherein the face is detected using an image sensor before the first reference voltage is applied.

[0030] According to one aspect of the present disclosure, there is provided a system, wherein the processor is configured to recognize a face using the depth map and the image signal.

[0031] According to one aspect of the present disclosure, a system is provided, wherein the light source is a vertical cavity surface emitting laser.

[0032] According to one aspect of the present disclosure, there is provided a system, wherein the image sensor is controlled by a camera control section.

[0033] According to an embodiment of the present disclosure, a method for driving a ranging system is provided. The method includes: selectively applying one of a first reference voltage and a second reference voltage to a comparator using a processor based on the operation of a light source; and comparing the one of the first reference voltage and the second reference voltage with a first signal output by a circuit of a pixel using the comparator. The light source is controlled by the processor and is configured to emit light. The pixel is one of a plurality of pixels included in an event-based visual sensor. The pixel includes: a photosensor configured to detect incident light; and a first circuit that outputs the first signal based on an output from the photosensor. The first signal represents a change in the amount of incident light.

[0034] According to aspects of the present disclosure, there is provided a method, wherein the operation is one of a turn-on event signal detection and a turn-off event signal detection.

[0035] According to aspects of the present disclosure, there is provided a method wherein when a first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores power-on event data in a memory of the system.

[0036] According to aspects of the present disclosure, there is provided a method, wherein when the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores turn-off event data in the memory.

[0037] According to aspects of the present disclosure, there is provided a method, wherein the stored power-on event data and the power-off event data are sequentially transmitted to a readout circuit.

[0038] According to aspects of the present disclosure, there is provided a method, wherein the stored power-on event data and the power-off event data are used to perform a face detection process.

[0039] According to aspects of the present disclosure, a method is provided, wherein the light source is a vertical cavity surface emitting laser.

[0040] According to an embodiment of the present disclosure, there is provided a ranging system, the ranging system comprising:

[0041] a light source unit configured to emit light toward a subject;

[0042] an event detection sensor configured to receive the light reflected by the subject and detect a change in brightness of a pixel exceeding or equal to a predetermined threshold as an event; and

[0043] A control section configured to control the light source section and the event detection sensor in synchronization with each other.

[0044] In addition, according to an embodiment of the present disclosure, it is desirable to provide an electronic device including the ranging system constructed as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1A is a schematic diagram illustrating an example of a configuration of a distance measurement system according to an embodiment of the present disclosure. Figure 1B is a block diagram showing an example of a circuit configuration.

[0046] Figure 2A is a diagram illustrating a random point arrangement of light sources of a vertical cavity surface emitting laser in a ranging system according to an embodiment of the present disclosure. Figure 2B FIG. 1 is a diagram showing an array point arrangement of a vertical cavity surface emitting laser light source.

[0047] Figure 3A is a diagram showing a combination of two light sources according to an array point arrangement. Figure 3B is a diagram for describing driving example 1 of a light source.

[0048] Figure 4 is a diagram for describing driving example 2 of a light source.

[0049] Figure 5 is a diagram for describing driving example 3 of a light source.

[0050] Figure 6 is a block diagram illustrating an example of a configuration of an event detection sensor in a distance measurement system according to an embodiment of the present disclosure.

[0051] Figure 7 is a circuit diagram showing a circuit configuration of a pixel according to Circuit Configuration Example 1.

[0052] Figure 8 is a circuit diagram showing a circuit configuration of a pixel according to Circuit Configuration Example 2.

[0053] Figure 9 is a circuit diagram showing a circuit configuration of a pixel according to Circuit Configuration Example 3.

[0054] Figure 10 is a circuit diagram showing a circuit configuration of a pixel according to Circuit Configuration Example 4.

[0055] Figure 11 : is a flowchart showing the flow of the synchronous control process according to the first embodiment.

[0056] Figure 12 : is a flowchart showing the flow of synchronous control processing according to the second embodiment.

[0057] Figure 13 1 is a flowchart showing the flow of synchronous control processing according to the third embodiment.

[0058] Figure 14 1 is a flowchart showing the flow of synchronous control processing according to the fourth embodiment.

[0059] Figure 15A and Figure 15B : is a diagram showing a pixel arrangement example (Part 1) of ON pixels and OFF pixels according to Example 5.

[0060] Figure 16A and Figure 16B : is a diagram showing a pixel arrangement example (part 2) of ON pixels and OFF pixels according to Example 5.

[0061] Figure 17 1 is a flowchart showing the flow of synchronous control processing according to the sixth embodiment.

[0062] Figure 18 1 is a flowchart showing the flow of synchronous control processing according to the seventh embodiment.

[0063] Figure 19 1 is a flowchart showing the flow of synchronous control processing according to the eighth embodiment.

[0064] Figure 20 is a block diagram showing an example of a circuit configuration of a distance measuring system according to Embodiment 9.

[0065] Figure 21 : is a flowchart showing the flow of face authentication processing according to the tenth embodiment.

[0066] Figure 22is an external view of a smartphone, which is a specific example of the electronic device according to an embodiment of the present disclosure, when viewed from the front. DETAILED DESCRIPTION

[0067] The embodiments for implementing the technology according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the accompanying drawings. The technology according to the present disclosure is not limited to these embodiments. In the following description, the same or similar numbers or symbols will refer to the same or similar elements or functions, and no repeated explanation will be given. It should be noted that the description will be given in the following order.

[0068] 1. General Description of Distance Measuring System and Electronic Device According to Embodiments of the Present Disclosure 2. Distance Measuring System According to Embodiments

[0069] 2-1. System Structure

[0070] 2.2. Vertical Cavity Surface Emitting Laser (VCSEL)

[0071] 2-2-1. Random point arrangement

[0072] 2-2-2. Array point arrangement

[0073] 2-3. Example of driving a light source based on an array point arrangement

[0074] 2-3-1. Light Source Driving Example 1 (Example of Forming an Intensity Peak at the Midpoint Between Two Light Sources)

[0075] 2-3-2. Light Source Driving Example 2 (Example Using Sensitivity Adjustment of Event Detection Sensors Simultaneously)

[0076] 2-3-3. Light Source Driving Example 3 (Example of Simultaneously Driving Two Light Sources While Adjusting the Luminous Intensity of the Two Light Sources to Keep the Intensity Peak Constant While Shifting the Peak Position)

[0077] 2-4. Event Detection Sensor (DVS)

[0078] 2-4-1. Example of event detection sensor structure

[0079] 2-4-2. Example of Pixel Circuit Structure

[0080] 2-4-2-1. Circuit Configuration Example 1 (Example of Detecting an ON Event and an OFF Event in a Time-Sharing Manner by Using a Single Comparator)

[0081] 2-4-2-2. Circuit Configuration Example 2 (Example of Detecting Turn-On and Turn-Off Events in Parallel Using Two Comparators)

[0082] 2-4-2-3. Circuit Configuration Example 3 (Example of Detecting Only a Turn-On Event by Using a Single Comparator)

[0083] 2-4-2-4. Circuit Configuration Example 4 (Example of Detecting Only a Shutdown Event by Using a Single Comparator)

[0084] 2-5. Synchronous Control of a Vertical Cavity Surface-Emitting Laser and an Event Detection Sensor

[0085] 2-5-1. Example 1 (Synchronous Control Example Used in the Case of Circuit Configuration Example 1)

[0086] 2-5-2. Example 2 (Synchronous Control Example Used in the Case of Circuit Configuration Example 2)

[0087] 2-5-3. Example 3 (Synchronous Control Example Used in the Case of Circuit Configuration Example 3)

[0088] 2-5-4. Example 4 (Synchronous Control Example Used in the Case of Circuit Configuration Example 4)

[0089] 2-5-5. Example 5 (Example of Pixel Arrangement Used When the Pixel Array Section Includes Both ON Pixels and OFF Pixels)

[0090] 2-5-6. Example 6 (Example of Synchronous Control Used in Example 5 (Part 1))

[0091] 2-5-7. Example 7 (Example of Synchronous Control Used in Example 5 (Part 2))

[0092] 2-5-8. Example 8 (Example of application to facial recognition)

[0093] 2-5-9. Example 9 (Example including an RGB camera in addition to an event detection sensor)

[0094] 2-5-10. Example 10 (Application to Face Recognition)

[0095] 3. Modifications

[0096] 4. Application Examples

[0097] 5. Electronic Device According to an Embodiment of the Present Disclosure (Example of Smartphone)

[0098] 6. Configurations that embodiments of the present disclosure may have

[0099] <General Description of Distance Measurement System and Electronic Device According to Embodiments of the Present Disclosure>

[0100] In a ranging system and electronic device according to an embodiment of the present disclosure, a pixel can be configured to have a function of detecting an on-event and an off-event in a time-sharing manner using a single comparator, where an on-event indicates that the amount of change in the photocurrent exceeds or is equal to an upper threshold, and an off-event indicates that the amount of change in the photocurrent is less than or equal to a lower threshold. Furthermore, the single comparator can be configured to receive a voltage based on the photocurrent as a first input, receive a voltage for detecting an on-event and a voltage for detecting an off-event provided in a time-sharing manner as second inputs, and output a comparison result between the first and second inputs as on-event information and off-event information.

[0101] In the ranging system and electronic device including the above-described advantageous configuration according to an embodiment of the present disclosure, the control section is configured to perform a global reset of the first input of the comparator, set the second input of the comparator to a voltage for detecting a turn-on event, emit light from the light source section toward the subject, store the turn-on event information in a memory, set the second input of the comparator to a voltage for detecting a turn-off event, stop emitting light toward the subject, store the turn-off event information in a memory, and sequentially transmit the turn-on event information and the turn-off event information to the readout circuit.

[0102] In addition, in the ranging system and electronic device including the above-described advantageous configuration according to an embodiment of the present disclosure, the pixel can be configured to have a function of detecting a turn-on event and a turn-off event in parallel by using two comparators, the turn-on event indicating that the amount of change in the photocurrent exceeds or is equal to an upper threshold value, and the turn-off event indicating that the amount of change in the photocurrent is less than or equal to a lower threshold value. In addition, one of the two comparators can be configured to receive a voltage based on the photocurrent as a first input, receive a voltage for detecting a turn-on event as a second input, and output a comparison result between the first input and the second input as turn-on event information, while the other of the two comparators can be configured to receive a voltage based on the photocurrent as a first input, receive a voltage for detecting a turn-off event as a second input, and output a comparison result between the first input and the second input as turn-off event information.

[0103] In addition, in the ranging system and electronic device including the above-mentioned advantageous structure according to the embodiment of the present disclosure, the control unit can be configured to perform a global reset of the first input of the comparator, emit light from the light source unit to the subject, store the on-event information in the memory, stop emitting light to the subject, store the off-event information in the memory, and transmit the on-event information and the off-event information to the readout circuit in sequence.

[0104] In addition, in a ranging system and electronic device including the above-described advantageous configuration according to an embodiment of the present disclosure, the pixel can be configured to have a function of detecting a turn-on event using a single comparator, where the turn-on event indicates that the amount of change in the photocurrent exceeds or equals an upper threshold value. In addition, the single comparator can be configured to receive a voltage based on the photocurrent as a first input, receive a voltage for detecting a turn-on event as a second input, and output a comparison result between the first input and the second input as turn-on event information. In addition, the control unit can be configured to perform a global reset of the first input of the comparator, emit light from the light source unit toward the subject, store the turn-on event information in a memory, and sequentially transmit the turn-on event information to the readout circuit.

[0105] In addition, in the ranging system and electronic device including the above-mentioned advantageous configuration according to the embodiment of the present disclosure, the pixel can be constructed to have a function of detecting a shutdown event by using a single comparator, and the shutdown event indicates that the amount of change in the photocurrent is lower than or equal to the lower threshold. In addition, the single comparator can be constructed to receive a voltage based on the photocurrent as a first input, receive a voltage for detecting a shutdown event as a second input, and output a comparison result between the first input and the second input as shutdown event information. In addition, the control unit can be constructed to perform a global reset of the first input of the comparator, emit light from the light source unit to the subject, turn on the reset switch connected between the first input terminal and the output terminal of the comparator, stop emitting light to the subject, store the shutdown event information in the memory, and then transmit the shutdown event information to the readout circuit in sequence.

[0106] In addition, in the ranging system and electronic device including the above-mentioned advantageous configuration according to the embodiments of the present disclosure, the pixel array portion of the event detection sensor may include both a first pixel and a second pixel, the first pixel having a function of using a comparator and detecting a turn-on event indicating that the amount of change in the photocurrent exceeds or is equal to an upper threshold value, and the second pixel having a function of using a comparator and detecting a turn-off event indicating that the amount of change in the photocurrent is lower than or equal to a lower threshold value.

[0107] In addition, in the ranging system and electronic device including the above-mentioned advantageous configuration according to the embodiment of the present disclosure, the control unit can be configured to first perform a global reset of all pixels including the first pixel and the second pixel, emit light from the light source unit toward the subject, store the on-event information detected by the first pixel in a memory, turn on the reset switch between the first input terminal and the output terminal of the comparator connected to the second pixel, stop emitting light toward the subject, store the off-event information detected by the second pixel in the memory, transmit the on-event information and the off-event information to the readout circuit in sequence, and then perform a global reset of the first input of the comparator.

[0108] Alternatively, in a ranging system and an electronic device including the above-described advantageous configuration according to an embodiment of the present disclosure, the control unit may be configured to first perform a global reset of all pixels including a first pixel and a second pixel, emit light from the light source unit toward the subject, store the on-event information detected by the first pixel in a memory, transmit the on-event information to the readout circuit in sequence, turn on a reset switch between the first input terminal and the output terminal of the comparator connected to the second pixel, stop emitting light toward the subject, store the off-event information detected by the second pixel in a memory, transmit the off-event information to the readout circuit in sequence, and then perform a global reset of the first input of the comparator.

[0109] In addition, in the distance measurement system and electronic device according to the embodiments of the present disclosure including the advantageous configuration described above, the light source unit may include a surface-emitting semiconductor laser. A favorable surface-emitting semiconductor laser is a vertical cavity surface-emitting laser. In addition, the vertical cavity surface-emitting laser can be configured to project a predetermined pattern of light onto the subject.

[0110] A ranging system according to another embodiment of the present disclosure includes:

[0111] a light source unit configured to emit light toward a subject;

[0112] an event detection sensor configured to receive light reflected by a subject and detect a change in brightness of a pixel exceeding or equal to a predetermined threshold as an event;

[0113] an imaging unit configured to capture an image of a subject and generate an image signal;

[0114] a processor configured to process an event signal generated by the event detection sensor and extract a region of interest based on an image signal from the imaging section; and

[0115] The control section is configured to control the light source section and the event detection sensor in synchronization with each other and to control the imaging section.

[0116] In addition, an electronic device according to another embodiment of the present disclosure includes the ranging system constructed as described above.

[0117] In another embodiment of the present disclosure, in a ranging system and electronic device including the above-described configuration, the processor may be configured to acquire ranging information based on the event signal and perform pattern matching in a region of interest based on the image signal. Furthermore, the processor may be configured to perform facial authentication of the user based on the acquired ranging information and pattern matching.

[0118] <Ranging System According to Implementation>

[0119] The ranging system according to an embodiment of the present disclosure is a system that uses structured light-related technology to measure the distance to a subject. In addition, the ranging system according to an embodiment of the present disclosure can also be used as a system for acquiring three-dimensional (3D) images. In this case, such a system can be referred to as a three-dimensional image acquisition system. Based on the structured light-related technology, it is possible to perform ranging by using pattern matching to identify the coordinates of a point image and the light source (so-called point light source) from which the point image is projected.

[0120] (System Structure)

[0121] Figure 1A is a schematic diagram illustrating an example of a configuration of a distance measurement system according to an embodiment of the present disclosure. Figure 1B is a block diagram showing an example of a circuit configuration.

[0122] The ranging system according to this embodiment uses a surface-emitting semiconductor laser such as a vertical cavity surface emitting laser (VCSEL) 10 as a light source unit, and uses an event detection sensor 20 called a DVS as a light receiving unit. As used herein, the DVS may also be referred to as an event-based visual sensor. The vertical cavity surface emitting laser (VCSEL) 10 projects a predetermined pattern of light onto a subject. In addition to the vertical cavity surface emitting laser 10 and the event detection sensor 20, the ranging system 1 according to this embodiment further includes a system control unit 30, a light source driving unit 40, a sensor control unit 50, a light source side optical system 60, and a camera side optical system 70.

[0123] The vertical cavity surface emitting laser (VCSEL) 10 and the event detection sensor (DVS) 20 will be described in detail later. The system control section 30 is implemented by a processor (e.g., a CPU), for example. The system control section 30 drives the vertical cavity surface emitting laser 10 through the light source driving section 40, and drives the event detection sensor 20 through the sensor control section 50. More specifically, the system control section 30 controls the vertical cavity surface emitting laser 10 and the event detection sensor 20 in synchronization with each other. A specific example of controlling the vertical cavity surface emitting laser 10 and the event detection sensor 20 in synchronization with each other under the control of the system control section 30 will be described later.

[0124] In the ranging system 1 constructed as described above according to the present embodiment, the vertical cavity surface emitting laser 10 emits light of a predetermined pattern, and the light of the predetermined pattern passes through the light source side optical system 60 and is projected onto the subject (measurement target) 100. The subject 100 reflects the projected light. Subsequently, the light reflected by the subject 100 passes through the camera side optical system 70 and enters the event detection sensor 20. The event detection sensor 20 receives the light reflected by the subject 100 and detects a brightness change of a pixel exceeding or equal to a predetermined threshold as an event. The event information detected by the event detection sensor 20 is supplied to the application processor 200 outside the ranging system 1. The application processor 200 performs predetermined processing on the event information detected by the event detection sensor 20.

[0125] (Vertical Cavity Surface Emitting Laser (VCSEL))

[0126] (Random point arrangement)

[0127] According to the technology related to structured light, in order to recognize the coordinates of a point image and to recognize from which light source (point light source) the point image is projected, pattern matching taking into account affine transformation is necessary. In order to realize pattern matching taking into account affine transformation, as Figure 2A As shown, the light sources 11 of the VCSEL 10 are arranged in a non-repeating pattern, which is a so-called random point arrangement characterized by its spatial orientation.

[0128] Regarding the arrangement of the light sources 11 of the vertical cavity surface emitting laser 10, a random dot arrangement is also applicable to the distance measurement system 1 according to this embodiment. However, with a random dot arrangement, it is difficult to increase the number of light sources 11 while maintaining the specificity of the arrangement pattern of the light sources 11 for easy identification. Therefore, it may not be possible to improve the resolution of the distance image determined by the number of light sources 11. Here, a "range image" is an image used to obtain information about the distance to the subject.

[0129] (Array point arrangement)

[0130] Therefore, the distance measuring system 1 according to the present embodiment uses a so-called array point arrangement as the arrangement of the light source 11 of the vertical cavity surface emitting laser 10. According to the array point arrangement, as shown in FIG. Figure 2B As shown, the light sources 11 are arranged two-dimensionally in an array (matrix) at a constant pitch. In the distance measurement system 1 according to this embodiment, which combines the VCSELs 10 and the event detection sensor 20, without randomly arranging the light sources 11, it is easy to identify which light source 11 projected the image by sequentially turning on the light sources 11 of the VCSELs 10 and checking the time stamps (time information) of the events recorded by the event detection sensor 20.

[0131] In the case of an array point arrangement, the number of light sources 11 can be increased compared to the case of a random point arrangement. Therefore, the resolution of the distance image determined based on the number of light sources (points) 11 can be improved. By modifying the driving of the light sources 11 in the array point arrangement of the vertical cavity surface emitting laser 10 and also characterizing the time axis direction, the distance measurement system 1 according to this embodiment can further improve the resolution of the distance image based on the resolution determined based on the number of light sources 11.

[0132] (Example of driving a light source based on an array point arrangement)

[0133] When driving the light source 11 in the array point arrangement of the vertical cavity surface emitting laser 10, the driving is performed in units of two adjacent light sources 11 and 11 in the array point arrangement. Figure 3A As shown, examples of combinations of two adjacent light sources 11 and 11 may include a combination A of two light sources 11 and 11 adjacent in the row direction (X direction), a combination B of two light sources 11 and 11 adjacent in the column direction (Y direction), and a combination C of two light sources 11 and 11 adjacent in an inclined direction.

[0134] (Light source driving example 1)

[0135] Here, taking the case of a combination A of two light sources 11 and 11 adjacent to each other in the row direction as an example, driving of the light source based on the combination A will be described as driving example 1 of the light source. Figure 3B 1 is a diagram for describing a driving example 1 of a light source. The light source 11 is driven by the light source driving section 40 under the control of the system control section 30. The same applies to various driving examples described below.

[0136] Driving Example 1 is an example in which two adjacent light sources 11 and 11 are driven to emit light at the same time, and an intensity peak is formed at the middle position during the period in which the light sources 11 and 11 are driven to emit light independently. Here, the wording "middle position" has the meaning of a strictly middle position and the meaning of an approximately middle position. Various changes in design or manufacturing are allowed. In addition, in Driving Example 1, it is assumed that the luminous intensity of the two light sources 11 and 11 is the same. Here, the wording "same" has the meaning of a strictly identical case and the meaning of an approximately identical case. Various changes in design or manufacturing are allowed.

[0137] Regarding the two light sources 11 and 11 adjacent to each other in the row direction (X direction), at time t1, the first light source 11 ( Figure 3A At time t2, the two light sources 11 and 11 are driven to emit light at the same time (two-point light-emitting drive), and then at time t3, the second light source 11 is driven ( Figure 3AIn other words, under the control of the system control unit 30, during the period between time t1 and time t3 at which the two light sources 11 and 11 are driven to emit light independently, that is, during the period between the two light sources 11 and 11, advantageously at the middle of the period, the two light sources 11 and 11 are simultaneously driven to emit light (at time t2).

[0138] Here, the time t2 at which the two light sources 11 and 11 are simultaneously driven to emit light is set to the middle time between time t1 and time t3, that is, the time at the middle position between the intensity peak position of the first light source 11 and the intensity peak position of the second light source 11 in the row direction (X direction). Therefore, the interval between the peak position obtained when the first light source 11 is driven to emit light and the peak position obtained when the two-point light emission drive is performed is the interval d, which is the same as the interval between the peak position obtained when the two-point light emission drive is driven to emit light and the peak position obtained when the second light source 11 is driven to emit light.

[0139] As described above, in driving example 1, driving is performed in units of two adjacent light sources 11 and 11, and in addition to the operation of driving the two light sources 11 and 11 to emit light independently, an operation of simultaneously driving the two light sources 11 and 11 to emit light is also performed (in this example, the operation of simultaneously driving the two light sources 11 and 11 to emit light during the time period between the timings of driving the light sources to emit light independently). Therefore, an intensity peak can be formed at a position different from the case where the two light sources 11 and 11 are driven to emit light independently (in this example, at an intermediate position during the period between the two light sources 11 and 11). This drive can characterize the time axis direction in addition to the spatial direction. Therefore, the resolution of the distance image for obtaining information about the distance to the subject can be improved while maintaining the specificity of the arrangement pattern of the light source 11 so as to identify the light source, without increasing the number of light sources 11.

[0140] Note that, in Driving Example 1, the two light sources 11 and 11 serving as the driving unit are set to have the same luminous intensity. However, the luminous intensity of one or both of the two light sources 11 and 11 may be adjusted.

[0141] In addition, driving example 1 describes the case of a combination A of two light sources 11 and 11 as an example. Even in the case of combination B or combination C, by driving the light sources 11 in a manner similar to the case of driving example 1, it is basically possible to improve the resolution of the distance image while maintaining the specificity of the arrangement pattern of the light sources 11 for identifying the light sources, without increasing the number of light sources 11. This also applies to the various driving examples described below.

[0142] (Light source driving example 2)

[0143] Driving Example 2 is an example of using sensitivity adjustment of the event detection sensor (DVS) 20 in the case of a combination A of two light sources 11 and 11. Here, for convenience of description, the first light source 11 (in the X direction) of the two light sources 11 and 11 adjacent in the row direction (X direction) is used. Figure 3A The second light source 11 (located on the left) is called light source 1, and the second light source 11 (located on the left) is called light source 1. Figure 3A The light source 2 is located on the right side.

[0144] Figure 4 : is a diagram for describing driving example 2 of a light source. Figure 4 , the current of light source 1 is represented by a dashed line, and the current of light source 2 is represented by a dotted line. In addition, the sensitivity of the event detection sensor (DVS) 20 is represented by a solid line. In driving example 2, the two light sources 1 and 2 are set to have the same luminous intensity in a manner similar to driving example 1. However, the luminous intensity of one or both of the two light sources 1 and 2 can also be adjusted.

[0145] In Driving Example 2, during time period T1, light source 1 is driven to emit light, and during the subsequent time period T2, light source 2 is driven to emit light. Therefore, light source 1 and light source 2 can emit light simultaneously during time period T2. By emitting light simultaneously from light source 1 and light source 2, the peak intensity during time period T2 can be increased to a level greater than that in the case where light is emitted only from light source 1 (which is the same as in the case of Driving Example 1).

[0146] Next, during the time period T2, the sensitivity of the event detection sensor (DVS) 20 is controlled so that the sensitivity during the time period T2 becomes lower than the sensitivity obtained when only the light source 1 emits light (during the time period T1). This control for adjusting the sensitivity of the event detection sensor 20 is performed under the control of the system control section 30 (see FIG1). Here, as the event detection sensor 20 reacts to more incident light, the sensitivity of the event detection sensor 20 becomes lower.

[0147] Next, during time period T3, light source 1 is driven to stop emitting light, thereby increasing the sensitivity of event detection sensor 20. At this time, it is advantageous to restore the sensitivity of event detection sensor 20 to the sensitivity obtained before light source 1 and light source 2 were simultaneously driven to emit light, that is, the same sensitivity as that obtained when only light source 1 emitted light (during time period T1). Here, the wording "same sensitivity" has the following meanings: a case where they have exactly the same sensitivity and a case where they have approximately the same sensitivity. Various variations in design or manufacturing are permitted.

[0148] As described above, in driving example 2, by setting the sensitivity of event detection sensor 20 to a lower sensitivity than that obtained when only light source 1 emits light during time period T2 when both light sources 1 and 2 are driven to emit light simultaneously, three reaction positions with respect to event detection sensor 20 can be formed by driving both light sources 1 and 2 to emit light. This driving method can characterize the time axis direction in addition to the spatial direction. Therefore, the resolution of the distance image can be improved while maintaining the specificity of the arrangement pattern of light sources 11 for light source identification, without increasing the number of light sources 11.

[0149] (Light source driving example 3)

[0150] Driving Example 3 is an example in which, in the case of combination A of two light sources 11 and 11, when the two light sources 11 and 11 are driven simultaneously, the luminous intensities of the two light sources 11 and 11 are adjusted to obtain a constant peak intensity and the peak position is shifted. Here, the term "constant peak intensity" means both a completely constant peak intensity and a substantially constant peak intensity. Various variations in design and manufacturing are permitted.

[0151] Likewise, in driving example 3, for convenience of description, the first light source 11 (in the row direction) of the two light sources 11 and 11 adjacent to each other is referred to as Figure 3A The second light source 11 (located on the left) is called light source 1, and the second light source 11 (located on the left) is called light source 1. Figure 3A The light source 2 is located on the right side.

[0152] Figure 5 3 is a diagram for describing a driving example 3 of a light source. Figure 5 In FIG, the current of light source 1 is represented by a dashed line, and the current of light source 2 is represented by a dotted line. In addition, the intensity waveform obtained when only light source 1 or light source 2 emits light and the intensity waveform obtained when light sources 1 and 2 emit light simultaneously are represented by solid lines. In the case of driving example 3, it is assumed that the sensitivity of the event detection sensor (DVS) 20 is constant.

[0153] In driving example 3, for example, light sources 1 and 2 are driven so that the luminous intensity of light source 1 gradually decreases and the luminous intensity of light source 2 gradually increases in synchronization with the decrease in the luminous intensity of light source 1. Therefore, when light sources 1 and 2 emit light simultaneously in a period after only light source 1 emits light (light emission stops) and before only light source 2 emits light, a constant peak intensity can be obtained. This driving method makes it possible to shift (shift) the peak position (little by little) by a predetermined amount while maintaining a constant peak intensity.

[0154] As described above, in driving example 3, when light sources 1 and 2 emit light simultaneously, by controlling and driving both light sources 1 and 2 to emit light in a manner that adjusts the luminous intensity of both light sources 1 and 2 to achieve a constant peak intensity, a greater number of reaction positions can be formed with respect to the event detection sensor 20. This type of driving can characterize the time axis direction in addition to the spatial direction. Therefore, the resolution of the distance image can be improved while maintaining the specificity of the arrangement pattern of light sources 11 for light source identification, without increasing the number of light sources 11.

[0155] Note that driving examples 1 to 3 describe the case of driving only light source 1 to emit light, driving both light source 1 and light source 2 to emit light, and driving only light source 2 to emit light, based on the combination A of two light sources 11 and 11. The same applies to the subsequent processes. In other words, for example, the light sources are repeatedly driven to emit light in such a manner that only light source 2 emits light, light source 2 and light source 3 emit light simultaneously, only light source 3 emits light, light source 3 and light source 4 emit light simultaneously, and only light source 4 emits light.

[0156] In addition, any one of combination A, combination B, and combination C of two adjacent light sources 11 and 11 can be selectively employed. Alternatively, these combinations can be combined. When combination A is employed, the resolution in the row direction (horizontal direction) can be improved. When combination B is employed, the resolution in the column direction (vertical direction) can be improved. When combination C is employed, the resolution in the oblique direction can be improved.

[0157] (Event Detection Sensor (DVS))

[0158] Next, the event detection sensor 20 will be described.

[0159] (Configuration example of event detection sensor)

[0160] Figure 6 : is a block diagram showing an example of the configuration of the event detection sensor 20 in the distance measuring system 1 configured as described above according to the embodiment of the present disclosure.

[0161] The event detection sensor 20 according to this example includes a pixel array unit 22 in which a plurality of pixels 21 are arranged two-dimensionally in a matrix (in an array). The plurality of pixels 21 each generate an analog signal having a voltage corresponding to a photocurrent serving as an electrical signal generated by photoelectric conversion as a pixel signal, and output the analog signal. In addition, the plurality of pixels 21 each detects whether an event has occurred based on whether a change in the photocurrent corresponding to the brightness of the incident light exceeds or is equal to a predetermined threshold. In other words, the plurality of pixels 21 each detects a brightness change exceeding or equal to a predetermined threshold as an event.

[0162] The event detection sensor 20 includes, in addition to the pixel array section 22 , a drive section 23 as a peripheral circuit section of the pixel array section 22 , an arbitrator section (arbitration section) 24 , a column processing section 25 , and a signal processing section 26 .

[0163] When an event is detected, each of the pixels 21 outputs a request to the arbiter unit 24. This request requests the output of event data indicating the occurrence of the event. Subsequently, upon receiving a response from the arbiter unit 24, each of the pixels 21 outputs the event data to the driver unit 23 and the signal processing unit 26. This response indicates that the output of the event data is permitted. Furthermore, the pixel 21 that detected the event outputs an analog pixel signal generated through photoelectric conversion to the column processing unit 25.

[0164] The driving section 23 drives each pixel 21 in the pixel array section 22 . For example, the driving section 23 detects an event, drives the pixel 21 that has output event data, and causes the analog pixel signal of the pixel 21 to be output to the column processing section 25 .

[0165] The arbiter section 24 arbitrates requests to output pieces of event data supplied from the respective pixels 21 , and transmits a response based on the arbitration result (whether output of pieces of event data is permitted) and a reset signal for resetting event detection to the pixels 21 .

[0166] The column processing section 25 includes an analog-to-digital conversion section including a group of analog-to-digital converters installed for each pixel column in the pixel array section 22. Examples of the analog-to-digital converter include a single-slope analog-to-digital converter, a successive approximation analog-to-digital converter, and a delta-sigma modulation (ΔΣ modulation) analog-to-digital converter.

[0167] The column processing section 25 converts analog pixel signals output from the pixels 21 in each pixel column in the pixel array section 22 into digital signals. The column processing section 25 may also perform correlated double sampling (CDS) on the digitized pixel signals.

[0168] The signal processing section 26 performs predetermined signal processing on the digitized pixel signal supplied from the column processing section 25 and the event data output from the pixel array section 22 , and outputs the event data and pixel signal subjected to the signal processing.

[0169] As described above, the change in the photocurrent generated by the pixel 21 can also be considered as a change in the amount of light (brightness) of the light entering the pixel 21. Therefore, it can be said that an event can be a change in the amount of light (brightness) of the pixel 21 that exceeds or equals a predetermined threshold. The event data indicating the occurrence of the event includes at least position information, such as the coordinates of the position of the pixel 21 where the light amount change as the event occurred. In addition to the position information, the event data may also include the polarity of the light amount change.

[0170] Regarding a series of event data output from pixel 21 in sequence when an event occurs, it can be said that the event data implicitly includes time information representing the relative time when the event occurs, as long as the intervals between multiple event data are kept the same as the intervals when the event occurs.

[0171] However, if the intervals between multiple pieces of event data are not kept the same as the intervals between events, the time information implicitly included in the event data will be lost. One reason for this is that multiple pieces of event data are stored in, for example, a memory. Therefore, before the intervals between multiple pieces of event data are kept the same as the intervals between events, the signal processing unit 26 includes time information indicating the relative time when the event occurred, such as a timestamp, in the event data.

[0172] (Pixel Circuit Configuration Example)

[0173] Next, a description will be given of a specific circuit configuration example of the pixel 21. The pixel 21 has an event detection function of detecting a change in luminance exceeding or equal to a predetermined threshold as an event.

[0174] The pixel 21 detects whether an event has occurred based on whether the amount of change in the photocurrent exceeds or is equal to a predetermined threshold value. Examples of events include an on-event and an off-event. An on-event indicates that the amount of change in the photocurrent exceeds or is equal to an upper threshold value. An off-event indicates that the amount of change is lower than or equal to a lower threshold value. In addition, the event data (event information) indicating the occurrence of an event includes, for example, a bit indicating the detection result of an on-event and a bit indicating the detection result of an off-event. It should be noted that the pixel 21 can also be constructed in such a way that the pixel 21 has the function of detecting only an on-event, or the pixel 21 has the function of detecting only an off-event.

[0175] <<Circuit Configuration Example 1>>

[0176] Circuit Configuration Example 1 is an example of detecting a turn-on event and a turn-off event in a time-sharing manner by using a single comparator. Figure 71 shows a circuit diagram of a pixel 21 according to circuit configuration example 1. The pixel 21 according to circuit configuration example 1 has a circuit configuration including a light receiving element 211, a light receiving circuit 212, a storage capacitor 213, a comparator 214, a reset circuit 215, an inverter 216, and an output circuit 217. The pixel 21 detects an on event and an off event under the control of the sensor control section 50.

[0177] The first electrode (anode electrode) of the light receiving element 211 is connected to the input port of the light receiving circuit 212. The second electrode (cathode electrode) of the light receiving element 211 is connected to the ground node as the reference potential node. The light receiving element 211 performs photoelectric conversion on the incident light and generates a charge of an amount corresponding to the light intensity (light amount). In addition, the light receiving element 211 converts the generated charge into a photocurrent I photo .

[0178] The light receiving circuit 212 converts the photocurrent I photo Converted to voltage V pr . Photocurrent I photo Detected by the light receiving element 211 and corresponds to the light intensity (light quantity). Here, generally, the light intensity is proportional to the voltage V pr The relationship between is a logarithmic relationship. In other words, the light receiving circuit 212 converts the photocurrent I photo Converted to voltage V pr . Photocurrent I photo Corresponds to the intensity of light emitted to the light receiving surface of the light receiving element 211. Voltage V pr is a logarithmic function. However, the photocurrent I photo With voltage V pr The relationship between is not limited to a logarithmic relationship.

[0179] The output from the light receiving circuit 212 and the photocurrent I photo The corresponding voltage V pr Through the storage capacitor 213, and as the voltage V diff The inverting input is the first input of the comparator 214. Generally, the comparator 214 is implemented by a differential pair of transistors. The comparator 214 receives the threshold voltage V provided by the sensor control unit 50. b As a non-inverting (+) input, the non-inverting input is the second input. In addition, the comparator 214 detects the turn-on event and the turn-off event in a time-sharing manner. In addition, after detecting the turn-on event and the turn-off event, the reset circuit 215 resets the pixel 21.

[0180] In a time-sharing manner, the sensor control unit 50 outputs the voltage V on As the threshold voltage V b , in the stage of detecting the shutdown event, the output voltage Voff , and output voltage V during the reset phase reset . Set the voltage V reset Set to voltage V on With voltage V off and is advantageously set to a voltage V on With voltage V off Here, the wording "intermediate value" has the meaning of a strictly intermediate value and a roughly intermediate value. Various variations in design or manufacture are permitted.

[0181] Furthermore, the sensor control unit 50 outputs an ON selection signal to the pixel 21 when detecting an ON event, outputs an OFF selection signal to the pixel 21 when detecting an OFF event, and outputs a global reset signal to the pixel 21 when performing a reset. The ON selection signal is supplied as a control signal to the selection switch SW inserted between the inverter 216 and the output circuit 217. on The shutdown selection signal is supplied as a control signal to the selection switch SW inserted between the comparator 214 and the output circuit 217. off .

[0182] During the detection phase of the on-state event, the comparator 214 converts the voltage V on With voltage V diff When the voltage V diff Exceeds or equals voltage V on When the photocurrent I photo The change in the value of exceeds or equals the upper limit. The ON event information On is inverted by the inverter 216 and is selected by the switch SW on , and is supplied to the output circuit 217.

[0183] During the shutdown event detection phase, the comparator 214 converts the voltage V off With voltage V diff When the voltage V diff Lower than voltage V off When the photocurrent I photo The change in the value is lower than the lower limit. The shutdown event information Off is selected by the switch SW off , and is supplied to the output circuit 217.

[0184] The reset circuit 215 includes a reset switch SW RS, two-input OR gate 2151 and two-input AND gate 2152. Reset switch SW RS Connected between the inverting (-) input terminal and the output terminal of the comparator 214. RS When turned on (closed), the reset switch SW RS The inverting input terminal and the output terminal are selectively short-circuited.

[0185] OR gate 2151 receives the signal received by selection switch SW on The on event information On and has been selected by the switch SW off The AND gate 2152 receives the output signal from the OR gate 2151 as one input and the global reset signal provided by the sensor control unit 50 as the other input, and detects one of the turn-on event information On and the turn-off event information Off. When the global reset signal is active, the AND gate 2152 resets the reset switch SW RS Connect (close).

[0186] As described above, when the output signal from the AND gate 2152 becomes active, the reset switch SW RS The inverting input terminal and the output terminal of the comparator 214 are short-circuited, and a global reset is performed on the pixels 21. Therefore, the reset operation can be performed only on the pixels 21 in which an event is detected.

[0187] The output circuit 217 includes an off-event output transistor NM1, an on-event output transistor NM2, and a current source transistor NM3. The off-event output transistor NM1 includes a memory (not shown) for storing off-event information Off in its gate. The memory is implemented by the gate parasitic capacitance of the off-event output transistor NM1.

[0188] In a similar manner to the off-event output transistor, the on-event output transistor NM2 includes a memory (not shown) for storing on-event information On in its gate. The memory is implemented by the gate parasitic capacitance of the on-event output transistor NM2.

[0189] In the readout phase, when the sensor control section 50 supplies a row selection signal to the gate electrode of the current source transistor NM3, the off-event information Off stored in the memory of the off-event output transistor NM1 and the on-event information On stored in the memory of the on-event output transistor NM2 are transmitted to the readout circuit 80 via the output line nRxOff and the output line nRxOn for each pixel row in the pixel array section 22. The readout circuit 80 may be, for example, a circuit installed in the signal processing section 26 (see FIG. Figure 6 ) in the circuit.

[0190] As described above, according to Circuit Configuration Example 1, the pixel 21 is configured in such a manner that it has an event detection function of detecting an on event and an off event in a time-sharing manner by using a single comparator 214 under the control of the sensor control section 50 .

[0191] <<Circuit Configuration Example 2>>

[0192] Circuit Configuration Example 2 is an example of detecting a turn-on event and a turn-off event in parallel (simultaneously) by using two comparators. Figure 8 A circuit diagram of a pixel 21 according to Circuit Configuration Example 2 is shown.

[0193] like Figure 8 As shown, pixel 21 according to circuit configuration example 2 is configured such that pixel 21 includes a comparator 214A for detecting an on-event and a comparator 214B for detecting an off-event. As described above, when two comparators 214A and 214B are used to detect events, the on-event detection operation and the off-event detection operation can be performed in parallel. As a result, the on-event detection operation and the off-event detection operation can be performed more quickly.

[0194] Typically, the comparator 214A for detecting the turn-on event is implemented by a differential pair of transistors. The comparator 214A receives the photocurrent I photo The corresponding voltage V diff As the non-inverting (+) input serving as the first input, it receives the threshold voltage V b The voltage V on The inverting (-) input serves as the second input, and outputs the turn-on event information On as the comparison result between the non-inverting (+) input and the inverting (-) input. Generally, the comparator 214B for detecting the turn-off event is also implemented by a differential pair of transistors. The comparator 214B receives the photocurrent I photo The corresponding voltage V diff As the first input, the inverting input receives the threshold voltage V b The voltage V off As a non-inverting input serving as a second input, the turn-off event information Off is output as a comparison result between the inverting input and the non-inverting input.

[0195] Selector switch SW on Connected between the output terminal of the comparator 214A and the gate electrode of the on-event output transistor NM2 of the output circuit 217. The selection switch SW off Connected between the output terminal of the comparator 214B and the gate electrode of the off-event output transistor NM1 of the output circuit 217. The selection switch SW on and selector switch SW offThe sensor is controlled to be on (closed) or off (open) by a sampling signal output from the sensor control unit 50 .

[0196] The ON event information On as the comparison result of the comparator 214A is transmitted via the selection switch SW on The memory for storing the on-event information On is implemented by the parasitic capacitance of the gate of the on-event output transistor NM2. The off-event information Off as the comparison result of the comparator 214B is transmitted via the selection switch SW off The memory for storing the off-event information Off is implemented by the parasitic capacitance of the gate of the off-event output transistor NM1.

[0197] When the sensor control unit 50 provides a row selection signal to the gate electrode of the current source transistor NM3, for each pixel row in the pixel array unit 22, the on-event information On stored in the memory of the on-event output transistor NM2 and the off-event information Off stored in the memory of the off-event output transistor NM1 are transmitted to the readout circuit 80 via the output line nRxOn and the output line nRxOff.

[0198] As described above, according to Circuit Configuration Example 2, the pixel 21 is configured in such a manner that it has an event detection function of detecting an on event and an off event in parallel (simultaneously) by using two comparators 214A and 214B under the control of the sensor control section 50 .

[0199] <<Circuit Configuration Example 3>>

[0200] Circuit Configuration Example 3 is an example of detecting only a power-on event. Figure 9 A circuit diagram of a pixel 21 according to Circuit Configuration Example 3 is shown.

[0201] The pixel 21 according to the circuit configuration example 3 includes a single comparator 214. The comparator 214 receives a signal corresponding to the photocurrent I photo The corresponding voltage V diff As the inverting (-) input serving as the first input, a voltage used as a threshold voltage V supplied from the sensor control section 50 is received. b The voltage V on As the non-inverting (+) input serving as the second input, the inverting (-) input is compared with the non-inverting (+) input, and the on-event information On is output as the comparison result. Here, n-type transistors are used as differential pair transistors for realizing the comparator 214. Therefore, the circuit configuration example 1 (see Figure 7 ) used in the inverter 216.

[0202] The on-event information On, which is the comparison result of comparator 214, is stored in a memory on the gate of on-event output transistor NM2. The memory for storing on-event information On is implemented by the parasitic capacitance of the gate of on-event output transistor NM2. When the sensor control unit 50 provides a row select signal to the gate electrode of current source transistor NM3, the on-event information On stored in the memory of on-event output transistor NM2 is transmitted to the readout circuit 80 via output line nRxOn for each pixel row in pixel array unit 22.

[0203] As described above, according to Circuit Configuration Example 3, the pixel 21 is configured in such a manner that the pixel 21 has an event detection function of detecting only an ON event by using a single comparator 214 under the control of the sensor control section 50 .

[0204] <<Circuit Configuration Example 4>>

[0205] Circuit Configuration Example 4 is an example of detecting only a shutdown event. Figure 10 A circuit diagram of a pixel 21 according to Circuit Configuration Example 4 is shown.

[0206] The pixel 21 according to the circuit configuration example 4 includes a single comparator 214. The comparator 214 receives a signal corresponding to the photocurrent I photo The corresponding voltage V diff As the inverting (-) input serving as the first input, a voltage used as a threshold voltage V supplied from the sensor control section 50 is received. b The voltage V off As the non-inverting (+) input serving as the second input, the inverting (−) input is compared with the non-inverting (+) input, and shutdown event information Off is output as a comparison result. P-type transistors can be used as differential pair transistors for implementing the comparator 214.

[0207] The shutdown event information Off, which is the comparison result of comparator 214, is stored in a memory on the gate of shutdown event output transistor NM1. The memory for storing the shutdown event information Off is implemented by the parasitic capacitance of the gate of shutdown event output transistor NM1. When the sensor control unit 50 provides a row select signal to the gate electrode of current source transistor NM3, the shutdown event information Off stored in the memory of shutdown event output transistor NM1 is transmitted to the readout circuit 80 via output line nRxOff for each pixel row in pixel array unit 22.

[0208] As described above, according to the circuit configuration example 4, the pixel 21 is configured in such a manner that the pixel 21 has an event detection function of detecting only the off event information Off by using the single comparator 214 under the control of the sensor control section 50. Figure 10The circuit configuration shown, although the reset switch SW RS The reset switch SW is controlled by the output signal from the AND gate 2152, but can also be directly controlled by the global reset signal. RS .

[0209] (Synchronous Control of Vertical Cavity Surface Emitting Lasers and Event Detection Sensors)

[0210] In this embodiment, in the ranging system 1 using the event detection sensor 20 including the pixel 21 constructed according to the above-mentioned circuit configuration example 1, circuit configuration example 2, circuit configuration example 3 or circuit configuration example 4, the vertical cavity surface emitting laser 10 and the event detection sensor 20 are controlled in synchronization with each other under the control of the system control unit 30.

[0211] By controlling the vertical cavity surface emitting laser 10 and the event detection sensor 20 in synchronization with each other, it is possible to output event information generated by the motion of the subject, while excluding event information generated by other causes. Examples of event information other than event information generated by the motion of the subject may include event information generated by changes in background light or a pattern projected on the subject. By outputting event information generated by the motion of the subject, while excluding event information generated by other causes, event information generated by the motion of the subject can be reliably acquired, and the processing performed by the application processor that processes the event information to separate multiple mixed pieces of event information can be omitted.

[0212] Next, a specific example of controlling the vertical cavity surface emitting laser 10 and the event detection sensor 20 under the control of the system control section 30 will be described. Figure 1B Under the control of the system control section 30 shown, synchronous control is performed by the light source driving section 40 and the sensor control section 50. In other words, it can be said that the wording "control section" described in the embodiments of the present disclosure refers to the light source driving section 40 and the sensor control section 50 operating under the control of the system control section 30.

[0213] (Example 1)

[0214] Embodiment 1 is a synchronous control example used in the case where the pixel 21 is configured according to Circuit Configuration Example 1 (in other words, an example of detecting an on event and an off event in a time-sharing manner by using a single comparator). Figure 11 FIG. 1 is a flowchart showing a synchronous control process according to Embodiment 1. The synchronous control process can be performed, for example, using the following system. Figure 11The flowchart shown is as follows: The system includes an image sensor configured to output an image signal, a light source configured to emit light (such as a vertical cavity surface emitting laser 10), and an event-based visual sensor configured to output an event signal. The event-based visual sensor may include a plurality of pixels and a comparator 214. One or more of the plurality of pixels may include a photosensor configured to detect incident light and a first circuit configured to output a first signal based on the output from the photosensor. The first signal may represent a change in the amount of incident light. The comparator 214 may be configured to output a comparison result based on at least one of a first reference voltage and a second reference voltage and the first signal. The system controller or sensor control unit 50 may be configured to synchronously control the event-based visual sensor and the light source. The processor may be configured to process the image signal and the event signal. The system controller may selectively apply the first reference voltage and the second reference voltage to the comparator based on the operation of the light source.

[0215] The sensor control unit 50 controls the voltage V diff A global reset is performed, and the threshold voltage V b Set as the voltage V used to detect the turn-on event on (Step S11).

[0216] Voltage V diff The global reset of can be performed after the event information is transmitted to the readout circuit 80. It should be noted that the voltage V diff A global reset is performed by Figure 7 The reset circuit 215 shown is connected (closed) with the reset switch SW RS This also applies to the various embodiments described below.

[0217] Next, the VCSEL 10 as the light source emits light of a predetermined pattern toward the subject (measurement target) (step S12). The VCSEL 10 is driven by the light source driver 40 under the control of the system controller 30. This also applies to the other embodiments described below.

[0218] Next, the sensor control section 50 stores the ON event information On as the comparison result of the comparator 214 in the memory (step S13 ). Here, the memory for storing the ON event information On is the gate parasitic capacitance of the ON event output transistor NM2 in the output circuit 217 .

[0219] Next, the sensor control unit 50 sets the threshold voltage V b Set as the voltage V used to detect the shutdown event off(Step S14). Next, the light source driving unit 40 stops emitting light toward the subject (Step S15). Next, the sensor control unit 50 stores the shutdown event information Off, which is the comparison result of the comparator 214, in the memory (Step S16). Here, the memory for storing the shutdown event information Off is the gate parasitic capacitance of the shutdown event output transistor NM1 in the output circuit 217.

[0220] Subsequently, the sensor control section 50 sequentially transmits the on-event information On stored in the gate parasitic capacitance of the on-event output transistor NM2 and the off-event information Off stored in the gate parasitic capacitance of the off-event output transistor NM1 to the readout circuit 80 (step S17), and ends a series of synchronous control processes.

[0221] (Example 2)

[0222] Embodiment 2 is a synchronous control example used in the case where the pixel 21 is configured according to Circuit Configuration Example 2 (in other words, an example in which an on event and an off event are detected in parallel by using two comparators). Figure 12 A flowchart of the synchronous control process according to the second embodiment is shown.

[0223] The sensor control unit 50 controls the voltage V diff A global reset is performed (step S21 ). Next, the light source driving section 40 causes the vertical cavity surface emitting laser 10 as the light source section to emit light of a predetermined pattern toward the subject (step S22 ).

[0224] Next, the sensor control unit 50 stores the ON event information On as the comparison result of the comparator 214A in the memory (step S23 ). Here, the memory for storing the ON event information On is the gate parasitic capacitance of the ON event output transistor NM2 in the output circuit 217 .

[0225] Next, the light source driving unit 40 stops emitting light toward the subject (step S24). Next, the sensor control unit 50 stores the shutdown event information Off, which is the comparison result of the comparator 214B, in the memory (step S25). Here, the memory used to store the shutdown event information Off is the gate parasitic capacitance of the shutdown event output transistor NM1 in the output circuit 217.

[0226] Subsequently, the sensor control section 50 sequentially transmits the on-event information On stored in the gate parasitic capacitance of the on-event output transistor NM2 and the off-event information Off stored in the gate parasitic capacitance of the off-event output transistor NM1 to the readout circuit 80 (step S26), and ends a series of synchronous control processes.

[0227] (Example 3)

[0228] Embodiment 3 is a synchronous control example used in the case where the pixel 21 is configured according to Circuit Configuration Example 3 (in other words, an example in which only an ON event is detected by using a single comparator). Figure 13 A flowchart of the synchronous control process according to the third embodiment is shown.

[0229] The sensor control unit 50 controls the voltage V diff A global reset is performed (step S31 ). Next, the light source driving section 40 causes the vertical cavity surface emitting laser 10 as the light source section to emit light of a predetermined pattern toward the subject (step S32 ).

[0230] Next, the sensor control section 50 stores the on-event information On, which is the comparison result of the comparator 214, in the memory (step S33). Here, the memory for storing the on-event information On is the gate parasitic capacitance of the on-event output transistor NM2 in the output circuit 217. Subsequently, the sensor control section 50 sequentially transmits the on-event information On stored in the gate parasitic capacitance of the on-event output transistor NM2 to the readout circuit 80 (step S34), and the series of synchronous control processes ends.

[0231] (Example 4)

[0232] Embodiment 4 is a synchronous control example used in the case where the pixel 21 is configured according to Circuit Configuration Example 4 (in other words, an example in which only a turn-off event is detected by using a single comparator). Figure 14 A flowchart of the synchronous control process according to the fourth embodiment is shown.

[0233] The sensor control unit 50 controls the voltage V diff A global reset is performed (step S41 ). Next, the light source driving section 40 causes the vertical cavity surface emitting laser 10 as the light source section to emit light of a predetermined pattern toward the subject (step S42 ).

[0234] Next, the sensor control unit 50 turns on the reset switch SW RS (Step S43). Next, the light source driving unit 40 stops emitting light toward the subject (Step S44). Next, the sensor control unit 50 stores the shutdown event information Off, which is the comparison result of the comparator 214, in the memory (Step S45). Here, the memory used to store the shutdown event information Off is the gate parasitic capacitance of the shutdown event output transistor NM1 in the output circuit 217.

[0235] Subsequently, the sensor control section 50 sequentially transfers the turn-off event information Off stored in the gate parasitic capacitance of the turn-off event output transistor NM1 to the readout circuit 80 (step S46 ), and ends a series of processes of the synchronous control.

[0236] (Example 5)

[0237] Example 5 is an example of a pixel arrangement used when the pixel array section 22 includes both ON pixels and OFF pixels. Here, an "ON pixel" is a pixel 21 configured according to Circuit Configuration Example 3, that is, a first pixel having a function of detecting only an ON event. Furthermore, an "OFF pixel" is a pixel 21 configured according to Circuit Configuration Example 4, that is, a second pixel having a function of detecting only an OFF event.

[0238] Figure 15A and Figure 15B A pixel arrangement example of ON pixels and OFF pixels according to Embodiment 5 is shown (Part 1). Figure 16A and Figure 16B Here, in order to simplify the drawings, Figures 15A to 16B A pixel arrangement (pixel array) of 16 pixels including four pixels in each row in the X direction (row direction / horizontal direction) and four pixels in each column in the Y direction (column direction / vertical direction) is shown.

[0239] according to Figure 15A As shown in the pixel arrangement, ON pixels and OFF pixels are arranged alternately in the X direction and the Y direction. Figure 15B In the pixel arrangement shown, four pixels (two pixels in the X direction×two pixels in the Y direction) form one block (one unit), and blocks of ON pixels and blocks of OFF pixels are alternately arranged in the X direction and the Y direction.

[0240] according to Figure 16A In the pixel arrangement shown, the 4 pixels in the center of the 16 pixels are ON pixels, and the 12 pixels around the ON pixels are OFF pixels. Figure 16B In the pixel arrangement shown, among the 16 pixels, pixels arranged in odd columns and even rows are ON pixels, and the other pixels are OFF pixels.

[0241] It should be noted that the pixel arrangement of ON pixels and OFF pixels illustrated above is merely an example, and the present disclosure is not limited thereto.

[0242] (Example 6)

[0243] Example 6 is a synchronous control example (Part 1) used in the case of Example 5, that is, a synchronous control example (Part 1) used in the case where the pixel array section 22 includes a pixel arrangement of both ON pixels and OFF pixels. Figure 17 A flowchart of the synchronous control process according to the sixth embodiment is shown.

[0244] The sensor control unit 50 first performs a global reset on all pixels, including both ON and OFF pixels (step S51). Next, the light source driver 40 causes the vertical cavity surface emitting laser 10, serving as the light source, to emit a predetermined pattern of light toward the subject (step S52). Next, the sensor control unit 50 stores the ON event information On detected by the ON pixels in a memory (step S53). Here, the memory used to store the ON event information On is the gate parasitic capacitance of the ON event output transistor NM2 in the output circuit 217.

[0245] Next, the sensor control unit 50 turns off the reset switch SW of the pixel. RS The light source driver 40 then stops emitting light toward the subject (step S55). The sensor controller 50 then stores the off-event information Off detected by the OFF pixel in a memory (step S56). The memory used to store the off-event information Off is the gate parasitic capacitance of the off-event output transistor NM1 in the output circuit 217.

[0246] Subsequently, the sensor control section 50 sequentially transmits the on-event information On and the off-event information Off to the readout circuit 80 (step S57). Next, the sensor control section 50 adjusts the voltage V diff A global reset is performed (step S58 ). Next, the sensor control unit 50 ends a series of synchronous control processes.

[0247] (Example 7)

[0248] Example 7 is a synchronous control example (part 2) used in the case of Example 5, that is, a synchronous control example (part 2) used in the case where the pixel array section 22 includes a pixel arrangement of both ON pixels and OFF pixels. Figure 18 A flowchart of the synchronous control process according to the seventh embodiment is shown.

[0249] The sensor control unit 50 first performs a global reset on all pixels, including both ON and OFF pixels (step S61). Next, the light source driver 40 causes the vertical cavity surface emitting laser 10, serving as the light source, to emit a predetermined pattern of light toward the subject (step S62). Next, the sensor control unit 50 stores the ON event information On detected by the ON pixels in a memory (step S63). Here, the memory used to store the ON event information On is the gate parasitic capacitance of the ON event output transistor NM2 in the output circuit 217.

[0250] Next, the sensor control section 50 sequentially transmits the on-event information On stored in the gate parasitic capacitance of the on-event output transistor NM2 in the output circuit 217 to the readout circuit 80 (step S64), and turns on the reset switch SW of the OFF pixel. RS Turn on (step S65).

[0251] Next, the light source driving section 40 stops emitting light toward the subject (step S66). Next, the sensor control section 50 stores the shutdown event information Off detected by the OFF pixel in a memory (step S67). Here, the memory used to store the shutdown event information Off is the gate parasitic capacitance of the shutdown event output transistor NM1 in the output circuit 217.

[0252] Subsequently, the sensor control section 50 sequentially transmits the off event information Off to the readout circuit 80 (step S68). Next, the sensor control section 50 adjusts the voltage V as the inverting input of the comparator 214 in the pixel that has undergone event detection. diff A global reset is performed (step S69 ). Next, the sensor control unit 50 ends a series of synchronous control processes.

[0253] (Example 8)

[0254] Embodiment 8 is an example in which the distance measuring system 1 according to the present embodiment is applied to face recognition. For example, in Embodiment 8, a case will be described in which the face detection process for face recognition is performed under synchronous control using the circuit configuration example 1. Figure 19 A flowchart of the synchronous control process according to the eighth embodiment is shown.

[0255] The sensor control unit 50 controls the voltage V diff A global reset is performed, and the threshold voltage V b Set as the voltage V used to detect the turn-on event on (Step S71).

[0256] Next, the light source driver 40 causes the vertical cavity surface emitting laser 10, serving as the light source, to emit a predetermined pattern of light toward the subject (measurement target) (step S72). Next, the sensor controller 50 stores the on-event information On, which is the comparison result of the comparator 214, in a memory (step S73). Here, the memory used to store the on-event information On is the gate parasitic capacitance of the on-event output transistor NM2 in the output circuit 217.

[0257] Next, the sensor control unit 50 sets the threshold voltage V b Set as the voltage V used to detect the shutdown event off (Step S74). Next, the light source driving unit 40 stops emitting light toward the subject (Step S75). Next, the sensor control unit 50 stores the shutdown event information Off, which is the comparison result of the comparator 214, in the memory (Step S76). Here, the memory for storing the shutdown event information Off is the gate parasitic capacitance of the shutdown event output transistor NM1 in the output circuit 217.

[0258] Next, the sensor control section 50 sequentially transmits the on-event information On stored in the gate parasitic capacitance of the on-event output transistor NM2 and the off-event information Off stored in the gate parasitic capacitance of the off-event output transistor NM1 to the readout circuit 80 (step S77 ).

[0259] The on event information On and the off event information Off sequentially transmitted to the readout circuit 80, that is, a plurality of pieces of event information detected by the event detection sensor 20 are supplied to the Figure 1B The application processor 200 shown in FIG. The application processor 200 performs face detection processing for face recognition based on the on-event information On and the off-event information Off (step S78).

[0260] (Example 9)

[0261] Example 9 is a variation of the distance measurement system 1 according to this embodiment. Example 9 is an example in which the distance measurement system 1 includes an imaging unit (hereinafter referred to as an "RGB camera") in addition to the event detection sensor 20. The imaging unit includes an image sensor such as a CMOS image sensor, and each pixel includes various color filters such as a red (R) filter, a green (G) filter, and a blue (B) filter.

[0262] Figure 20 : is a block diagram showing an example of a circuit configuration of a distance measuring system according to Embodiment 9. Figure 20As shown, the distance measurement system 1 according to the modified example of the present embodiment further includes an RGB camera 91 and a camera control section 92 for controlling the RGB camera 91, in addition to the event detection sensor 20. Under the control of the system control section 30, the RGB camera 91 acquires image information of a subject detected by the event detection sensor 20, supplies the acquired image information to the system control section 30, supplies the acquired image information to the camera control section 92, and supplies the image information to the application processor 200 via the camera control section 92.

[0263] The imaging section serving as the RGB camera is a synchronous imaging device that captures images at a predetermined frame rate and has a better resolution than the event detection sensor 20. Therefore, the distance measurement system 1 according to the modification of the present embodiment can use the RGB camera 91 and can acquire image information of an area including an event at a higher resolution than the event detection sensor 20. As a result, it is possible to more accurately identify an object of the event (such as the face of a predetermined user) based on the image information of the area including the event acquired through imaging performed by the RGB camera 91.

[0264] It should be noted that since the pixel 21 has Figure 7 The circuit configuration example shown is 1. Figure 8 The circuit configuration example shown in 2, Figure 9 Circuit Configuration Example 3 shown or Figure 10 The circuit configuration of circuit configuration example 4 shown, therefore, the event detection sensor 20 necessarily has a larger pixel size than the RGB camera 91 implemented by the synchronous camera device. Therefore, it can be said that the event detection sensor 20 has a lower resolution than the RGB camera 91 that captures images at a predetermined frame rate. In other words, it can be said that the RGB camera 91 has a better resolution than the event detection sensor 20. In some embodiments, the RGB camera can be integrated into the event-based vision sensor as a single chip. In such an embodiment, the sensor is capable of detecting events and RGB photography. The sensor may include a pixel array including one or more pixels capable of detecting visible light for RGB photography and one or more pixels capable of detecting infrared light for event detection. As another example, the chip sensor may include a pixel array including one or more pixels capable of detecting infrared light for event detection and visible light for RGB photography.

[0265] (Example 10)

[0266] Example 10 is an example of performing facial recognition (facial authentication) using a distance measurement system 1 according to a variation of this embodiment (i.e., a combination of an event detection sensor 20 and an RGB camera 91). In this case, the application processor 200 of the distance measurement system 1 according to Example 9 processes the event signal generated by the event detection sensor 20 and extracts a region of interest based on the image signal from the RGB camera 91, which serves as an imaging unit. Furthermore, the application processor 200 has the function of acquiring distance measurement information based on the event signal and performing pattern matching in the region of interest based on the image signal. Furthermore, the application processor 200 has the function of performing facial authentication on the user based on the acquired distance measurement information and pattern matching.

[0267] Figure 21 FIG2 shows a flowchart of facial recognition processing according to Example 10. In Example 10, similarly to the above-described embodiments, the vertical cavity surface emitting laser 10 and the event detection sensor 20 are also controlled in synchronization with each other by the light source driving section 40 and the sensor control section 50 under the control of the system control section 30. Note that the facial recognition processing is executed by the application processor 200.

[0268] The system control unit 30 first activates the RGB camera 91 (step S81), then causes the RGB camera 91 to capture an image (step S82). Next, the system control unit 30 detects a face in the RGB image captured by the RGB camera 91 (step S83), and then determines whether the image information of the detected facial portion matches the image information of the face of a predetermined user (step S84). If it is determined that the image information does not match (No in step S84), the system control unit 30 returns to step S81.

[0269] When it is determined that the above-mentioned image information matches each other (Yes in step S84), the system control section 30 uses the voltage V diff A global reset is performed, and the threshold voltage V b Set as the voltage V used to detect the turn-on event on (Step S85).

[0270] Next, the system control unit 30 causes the vertical cavity surface emitting laser 10, which serves as the light source unit, to emit light toward the detected facial portion (step S86), and stores the on-event information On, which is the comparison result of the comparator 214, in the memory (step S87). Here, the memory for storing the on-event information On is the gate parasitic capacitance of the on-event output transistor NM2 in the output circuit 217.

[0271] Next, the system control unit 30 sets the threshold voltage V bSet as the voltage V used to detect the shutdown event off (Step S88), and then stops emitting light toward the facial portion (Step S89). Next, the system control unit 30 stores the shutdown event information Off, which is the comparison result of the comparator 214, in the memory (Step S90). Here, the memory for storing the shutdown event information Off is the gate parasitic capacitance of the shutdown event output transistor NM1 in the output circuit 217.

[0272] Next, the system control unit 30 sequentially transfers the on-event information On stored in the gate parasitic capacitance of the on-event output transistor NM2 and the off-event information Off stored in the gate parasitic capacitance of the off-event output transistor NM1 to the readout circuit 80 (step S91 ).

[0273] The on-event information On and the off-event information Off transmitted to the readout circuit 80 in sequence, that is, the multiple event information detected by the event detection sensor 20, are supplied to the application processor 200. The application processor 200 generates a depth map for facial recognition based on the on-event information On and the off-event information Off (step S92). Next, the application processor 200 uses a pattern matching function in the region of interest based on the image signal, and determines whether the generated depth map matches the depth map of the face of the predetermined user (step S93). In the case where it is determined that the above-mentioned depth maps match each other (yes in step S93), the application processor 200 ends a series of processes for facial recognition. In the case where it is determined that the above-mentioned depth maps do not match each other (no in step S93), the application processor 200 returns to step S81.

[0274] <Modification>

[0275] The technology according to the present disclosure has been described above based on advantageous embodiments. However, the technology according to the present disclosure is not limited to these embodiments. The configuration and structure of the distance measurement system described in the above embodiments are merely illustrative and can be modified appropriately.

[0276] <Application Examples>

[0277] The above-described distance measurement system according to the embodiment and modified examples of the present disclosure can be used in various situations. Examples of the various situations may include the devices listed below.

[0278] - Equipment used in transportation, such as: in-vehicle sensors that capture images of the front, rear, surroundings, and interior of a car for safe driving, such as automatic stopping, and for identifying the driver's condition; surveillance cameras that monitor moving vehicles and roads; or ranging sensors that measure the distance between vehicles.

[0279] -Devices for home appliances such as TVs, refrigerators, or air conditioners, for capturing images of user gestures and operating the device based on the gestures.

[0280] - Equipment used for security, such as surveillance cameras for crime prevention or cameras for personal authentication applications, etc.

[0281] <Electronic Device According to Embodiment of the Present Disclosure>

[0282] The above-described distance measurement system according to the embodiments and variations of the present disclosure can be used as a three-dimensional image acquisition system (facial authentication system) installed in, for example, various electronic devices having a facial authentication function. Examples of electronic devices having a facial authentication function include mobile devices such as smartphones, tablets, and personal computers. It should be noted that the electronic devices to which the distance measurement system according to the embodiments or variations of the present disclosure is applicable are not limited to mobile devices.

[0283] (Smartphone)

[0284] Here, a smartphone will be described as a specific example of an electronic device according to an embodiment of the present disclosure to which the distance measurement system according to the embodiment or the modified example of the present disclosure is applied. Figure 22 is an external view of a smartphone, which is a specific example of the electronic device according to an embodiment of the present disclosure, when viewed from the front.

[0285] The smartphone 300 according to the specific example includes a display unit 320 on the front of a housing 310. In addition, the smartphone 300 further includes a light emitting unit 330 and a light receiving unit 340 on the upper side of the front of the housing 310. Figure 22 The arrangement example of the light emitting section 330 and the light receiving section 340 shown is merely an example, and the arrangement is not limited thereto.

[0286] With respect to the smartphone 300 configured as described above and serving as an example of a mobile device, the light source (vertical cavity surface emitting laser 10) in the distance measuring system 1 according to the above-described embodiment can be used as the light emitting section 330, and the event detection sensor 20 can be used as the light receiving section 340. In other words, the smartphone 300 according to this specific example is obtained by using the distance measuring system 1 according to the above-described embodiment as a three-dimensional image acquisition system.

[0287] The distance measurement system 1 according to the above embodiment can improve the resolution of the distance image without increasing the number of light sources in the array point arrangement of the light source. Therefore, when the distance measurement system 1 according to the above embodiment is used as a three-dimensional image acquisition system (facial authentication system), the smartphone 300 according to the specific example can have a highly accurate facial recognition function (facial authentication function).

[0288] <Configurations that embodiments of the present disclosure can have>

[0289] Note that embodiments of the present disclosure can also be configured as follows.

[0290] <<A. Distance measurement system (Part 1)>>

[0291] (A-1)

[0292] A distance measurement system, comprising:

[0293] A light source unit configured to emit light toward a subject;

[0294] An event detection sensor configured to receive the light reflected by the subject and detect a change in the brightness of a pixel that exceeds or equals a predetermined threshold as an event; and

[0295] A control unit configured to control the light source unit and the event detection sensor synchronously with each other.

[0296] (A-2)

[0297] The distance measurement system according to (A-1),

[0298] wherein the pixel has a function of detecting an on-event and an off-event in a time-sharing manner using a single comparator, the on-event indicating that a change amount of photocurrent exceeds or equals an upper threshold, and the off-event indicating that the change amount of photocurrent is lower than or equals a lower threshold.

[0299] (A-3)

[0300] The distance measurement system according to (A-2),

[0301] wherein the single comparator receives a voltage based on photocurrent as a first input, receives voltages for detecting the on-event and the off-event provided in the time-sharing manner as a second input, and outputs a comparison result between the first input and the second input as on-event information and off-event information.

[0302] (A-4)

[0303] The distance measurement system according to (A-3),

[0304] The control unit performs a global reset on the first input of the comparator, sets the second input of the comparator to the voltage for detecting a turn-on event, emits light from the light source unit to the subject, stores the turn-on event information in a memory, sets the second input of the comparator to the voltage for detecting a turn-off event, stops emitting the light to the subject, stores the turn-off event information in a memory, and then transmits the turn-on event information and the turn-off event information to the readout circuit in sequence.

[0305] (A-5)

[0306] According to the ranging system described in (A-1),

[0307] The pixel has the function of detecting a turn-on event and a turn-off event in parallel by using two comparators, wherein the turn-on event indicates that the change in photocurrent exceeds or is equal to an upper threshold, and the turn-off event indicates that the change in photocurrent is lower than or equal to a lower threshold.

[0308] (A-6)

[0309] The ranging system according to (A-5), wherein

[0310] One of the two comparators receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the turn-on event as a second input, and outputs a comparison result between the first input and the second input as turn-on event information, and

[0311] The other of the two comparators receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the shutdown event as a second input, and outputs a comparison result between the first input and the second input as shutdown event information.

[0312] (A-7)

[0313] According to the ranging system described in (A-6),

[0314] In which, the control unit performs a global reset on the first input of the comparator, emits light from the light source unit to the subject, stores the connection event information in a memory, stops emitting the light to the subject, stores the connection event information in the memory, and then transmits the connection event information and the connection event information to the readout circuit in sequence.

[0315] (A-8)

[0316] According to the ranging system described in (A-1),

[0317] The pixel has a function of detecting a turn-on event by using a single comparator, where the turn-on event indicates that a change in photocurrent exceeds or is equal to an upper threshold.

[0318] (A-9)

[0319] According to the ranging system described in (A-8),

[0320] The single comparator receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the switch-on event as a second input, and outputs a comparison result between the first input and the second input as switch-on event information.

[0321] (A-10)

[0322] According to the ranging system described in (A-9),

[0323] The control unit performs a global reset on the first input of the comparator, emits light from the light source unit toward the subject, stores the power-on event information in a memory, and then sequentially transmits the power-on event information to a readout circuit.

[0324] (A-11)

[0325] According to the ranging system described in (A-1),

[0326] The pixel has a function of detecting a turn-off event by using a single comparator, wherein the turn-off event indicates that a change in the photocurrent is lower than or equal to a lower threshold.

[0327] (A-12)

[0328] According to the ranging system described in (A-11),

[0329] The single comparator receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the shutdown event as a second input, and outputs a comparison result between the first input and the second input as shutdown event information.

[0330] (A-13)

[0331] According to the ranging system described in (A-12),

[0332] In which, the control unit performs a global reset on the first input of the comparator, emits light from the light source unit to the subject, turns on the reset switch connected between the first input terminal and the output terminal of the comparator, stops emitting the light to the subject, stores the shutdown event information in the memory, and then transmits the shutdown event information to the readout circuit in sequence.

[0333] (A-14)

[0334] According to the ranging system described in (A-1),

[0335] The pixel array portion of the event detection sensor includes a first pixel and a second pixel, wherein the first pixel has a function of using a comparator and detecting a turn-on event indicating that the amount of change in photocurrent exceeds or is equal to an upper threshold, and the second pixel has a function of using a comparator and detecting a turn-off event indicating that the amount of change in photocurrent is lower than or equal to a lower threshold.

[0336] (A-15)

[0337] According to the ranging system described in (A-14),

[0338] Among them, the control unit first performs a global reset on all pixels including the first pixel and the second pixel, emits light from the light source unit to the object, stores the turn-on event information detected by the first pixel in a memory, turns on the reset switch between the first input terminal and the output terminal of the comparator connected to the second pixel, stops emitting the light to the object, stores the turn-off event information detected by the second pixel in a memory, transmits the turn-on event information and the turn-off event information to the readout circuit in sequence, and then performs the global reset on the first input of the comparator.

[0339] (A-16)

[0340] According to the ranging system described in (A-14),

[0341] In which, the control unit first performs a global reset on all pixels including the first pixel and the second pixel, emits light from the light source unit to the subject, stores the on-event information detected by the first pixel in a memory, transmits the on-event information to the readout circuit in sequence, turns on the reset switch between the first input terminal and the output terminal of the comparator connected to the second pixel, stops emitting the light to the subject, stores the off-event information detected by the second pixel in a memory, transmits the off-event information to the readout circuit in sequence, and then performs the global reset on the first input of the comparator.

[0342] (A-17)

[0343] The ranging system according to any one of (A-1) to (A-16),

[0344] Wherein, the light source unit includes a surface-emitting semiconductor laser.

[0345] (A-18)

[0346] The distance measurement system according to (A-17),

[0347] wherein the surface-emitting semiconductor laser is a vertical-cavity surface-emitting laser.

[0348] (A-19)

[0349] The distance measurement system according to (A-18),

[0350] wherein the vertical-cavity surface-emitting laser projects light of a predetermined pattern onto the subject.

[0351] <<B. Distance Measurement System (Part 2)>>

[0352] (B-1)

[0353] A distance measurement system, comprising:

[0354] A light source unit configured to emit light toward a subject;

[0355] An event detection sensor configured to receive the light reflected by the subject and detect an event when a change in the brightness of a pixel exceeds or equals a predetermined threshold;

[0356] An imaging unit configured to capture an image of the subject and generate an image signal;

[0357] A processor configured to process an event signal generated by the event detection sensor and extract a region of interest based on the image signal from the imaging unit; and

[0358] A control unit configured to control the light source unit and the event detection sensor synchronously with each other and control the imaging unit.

[0359] (B-2)

[0360] The distance measurement system according to (B-1),

[0361] wherein the pixel has a function of detecting an on-event and an off-event in a time-sharing manner using a single comparator, the on-event indicating that a change amount of photocurrent exceeds or equals an upper threshold, and the off-event indicating that the change amount of photocurrent is lower than or equals a lower threshold.

[0362] (B-3)

[0363] The distance measurement system according to (B-2),

[0364] Among them, the single comparator receives the voltage based on the photocurrent as the first input, receives the voltage for detecting the on-event and the voltage for detecting the off-event provided in the time-sharing manner as the second input, and outputs the comparison result between the first input and the second input as the on-event information and the off-event information.

[0365] (B-4)

[0366] The ranging system according to (B-3),

[0367] Among them, the control unit globally resets the first input of the comparator, sets the second input of the comparator to the voltage for detecting the on-event, emits light from the light source unit to the subject, stores the on-event information in the memory, sets the second input of the comparator to the voltage for detecting the off-event, stops emitting the light to the subject, stores the off-event information in the memory, and then sequentially transmits the on-event information and the off-event information to the readout circuit.

[0368] (B-5)

[0369] The ranging system according to (B-3),

[0370] Among them, the processor has the function of obtaining ranging information based on the event signal and performing pattern matching in the region of interest based on the image signal.

[0371] (B-6)

[0372] The ranging system according to (B-5),

[0373] Among them, the processor has the function of performing face authentication on the user based on the obtained ranging information and the pattern matching.

[0374] <<C. Electronic device>>

[0375] (C-1)

[0376] An electronic device, which includes a ranging system, and the ranging system includes:

[0377] A light source unit, which is configured to emit light to a subject;

[0378] An event detection sensor, which is configured to receive the light reflected by the subject and detect that the brightness change of a pixel exceeds or is equal to a predetermined threshold as an event; and

[0379] A control unit, which is configured to control the light source unit and the event detection sensor synchronously with each other.

[0380] (C-2)

[0381] The electronic device according to (C-1),

[0382] The pixel has the function of detecting a turn-on event and a turn-off event in a time-sharing manner by using a single comparator, wherein the turn-on event indicates that the change in photocurrent exceeds or is equal to an upper threshold, and the turn-off event indicates that the change in photocurrent is lower than or equal to a lower threshold.

[0383] (C-3)

[0384] The electronic device according to (C-2),

[0385] The single comparator receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the turn-on event and a voltage for detecting the turn-off event provided in the time-sharing manner as a second input, and outputs a comparison result between the first input and the second input as turn-on event information and turn-off event information.

[0386] (C-4)

[0387] The electronic device according to (C-3),

[0388] The control unit performs a global reset on the first input of the comparator, sets the second input of the comparator to the voltage for detecting a turn-on event, emits light from the light source unit to the subject, stores the turn-on event information in a memory, sets the second input of the comparator to the voltage for detecting a turn-off event, stops emitting the light to the subject, stores the turn-off event information in a memory, and then transmits the turn-on event information and the turn-off event information to the readout circuit in sequence.

[0389] (C-5)

[0390] The electronic device according to (C-1),

[0391] The pixel has the function of detecting a turn-on event and a turn-off event in parallel by using two comparators, wherein the turn-on event indicates that the change in photocurrent exceeds or is equal to an upper threshold, and the turn-off event indicates that the change in photocurrent is lower than or equal to a lower threshold.

[0392] (C-6)

[0393] The electronic device according to (C-5), wherein

[0394] One of the two comparators receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the turn-on event as a second input, and outputs a comparison result between the first input and the second input as turn-on event information, and

[0395] The other of the two comparators receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the shutdown event as a second input, and outputs a comparison result between the first input and the second input as shutdown event information.

[0396] (C-7)

[0397] The electronic device according to (C-6),

[0398] In which, the control unit performs a global reset on the first input of the comparator, emits light from the light source unit to the subject, stores the connection event information in a memory, stops emitting the light to the subject, stores the connection event information in the memory, and then transmits the connection event information and the connection event information to the readout circuit in sequence.

[0399] (C-8)

[0400] The electronic device according to (C-1),

[0401] The pixel has a function of detecting a turn-on event by using a single comparator, where the turn-on event indicates that a change in photocurrent exceeds or is equal to an upper threshold.

[0402] (C-9)

[0403] The electronic device according to (C-8),

[0404] The single comparator receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the switch-on event as a second input, and outputs a comparison result between the first input and the second input as switch-on event information.

[0405] (C-10)

[0406] The electronic device according to (C-9),

[0407] The control unit performs a global reset on the first input of the comparator, emits light from the light source unit toward the subject, stores the power-on event information in a memory, and then sequentially transmits the power-on event information to a readout circuit.

[0408] (C-11)

[0409] The electronic device according to (C-1),

[0410] The pixel has a function of detecting a turn-off event by using a single comparator, wherein the turn-off event indicates that a change in the photocurrent is lower than or equal to a lower threshold.

[0411] (C-12)

[0412] The electronic device according to (C-11),

[0413] The single comparator receives a voltage based on the photocurrent as a first input, receives a voltage for detecting the shutdown event as a second input, and outputs a comparison result between the first input and the second input as shutdown event information.

[0414] (C-13)

[0415] The electronic device according to (C-12),

[0416] In which, the control unit performs a global reset on the first input of the comparator, emits light from the light source unit to the subject, turns on the reset switch connected between the first input terminal and the output terminal of the comparator, stops emitting the light to the subject, stores the shutdown event information in the memory, and then transmits the shutdown event information to the readout circuit in sequence.

[0417] (C-14)

[0418] The electronic device according to (C-1),

[0419] The pixel array portion of the event detection sensor includes a first pixel and a second pixel, wherein the first pixel has a function of using a comparator and detecting a turn-on event indicating that the amount of change in photocurrent exceeds or is equal to an upper threshold, and the second pixel has a function of using a comparator and detecting a turn-off event indicating that the amount of change in photocurrent is lower than or equal to a lower threshold.

[0420] (C-15)

[0421] The electronic device according to (C-14),

[0422] Among them, the control unit first performs a global reset on all pixels including the first pixel and the second pixel, emits light from the light source unit to the object, stores the turn-on event information detected by the first pixel in a memory, turns on the reset switch between the first input terminal and the output terminal of the comparator connected to the second pixel, stops emitting the light to the object, stores the turn-off event information detected by the second pixel in a memory, transmits the turn-on event information and the turn-off event information to the readout circuit in sequence, and then performs the global reset on the first input of the comparator.

[0423] (C-16)

[0424] The electronic device according to (C-14),

[0425] In which, the control unit first performs a global reset on all pixels including the first pixel and the second pixel, emits light from the light source unit to the subject, stores the on-event information detected by the first pixel in a memory, transmits the on-event information to the readout circuit in sequence, turns on the reset switch between the first input terminal and the output terminal of the comparator connected to the second pixel, stops emitting the light to the subject, stores the off-event information detected by the second pixel in a memory, transmits the off-event information to the readout circuit in sequence, and then performs the global reset on the first input of the comparator.

[0426] (C-17)

[0427] The electronic device according to any one of (C-1) to (C-16),

[0428] Wherein, the light source unit includes a surface-emitting semiconductor laser.

[0429] (C-18)

[0430] The electronic device according to (C-17),

[0431] Wherein, the surface emitting semiconductor laser is a vertical cavity surface emitting laser.

[0432] (C-19)

[0433] The electronic device according to (C-18),

[0434] The vertical cavity surface emitting laser projects light of a predetermined pattern onto the object.

[0435] (D-1)

[0436] A system comprising:

[0437] processor;

[0438] a light source controlled by the processor and configured to emit light; and

[0439] An event-based vision sensor controlled by the processor, wherein the event-based vision sensor comprises:

[0440] multiple pixels; and

[0441] a comparator configured to output a comparison result based on at least one of a first reference voltage and a second reference voltage and a first signal,

[0442] Wherein, at least one pixel among the plurality of pixels comprises:

[0443] a photosensor configured to detect incident light; and

[0444] a first circuit configured to output the first signal based on an output from the photosensor, wherein the first signal represents a change in an amount of incident light,

[0445] The processor is configured to selectively apply one of the first reference voltage and the second reference voltage to the comparator based on the operation of the light source.

[0446] (D-2)

[0447] The system according to (D-1), wherein the operation is one of on-event signal detection and off-event signal detection.

[0448] (D-3)

[0449] The system of (D-2), wherein when the first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores on-event data in a memory of the system.

[0450] (D-4)

[0451] The system according to (D-3), wherein when the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores shutdown event data in the memory.

[0452] (D-5)

[0453] The system according to (D-4), wherein the stored on-event data and the off-event data are sequentially transferred to a readout circuit.

[0454] (D-6)

[0455] The system according to (D-1), wherein the light source is a vertical cavity surface emitting laser.

[0456] (D-7)

[0457] The system according to (D-4), wherein the stored on-event data and the off-event data are used to perform face detection processing.

[0458] (E-1)

[0459] A system comprising:

[0460] an image sensor configured to output an image signal;

[0461] a light source configured to emit light;

[0462] an event-based vision sensor configured to output an event signal;

[0463] a system controller configured to synchronously control the event-based vision sensor and the light source; and

[0464] a processor configured to process the image signal and the event signal,

[0465] The event-based vision sensor includes:

[0466] multiple pixels; and

[0467] a comparator configured to output a comparison result based on at least one of a first reference voltage and a second reference voltage and a first signal,

[0468] Wherein, at least one pixel among the plurality of pixels comprises:

[0469] a photosensor configured to detect incident light; and

[0470] a first circuit that outputs the first signal based on an output from the photosensor, wherein the first signal represents a change in the amount of incident light,

[0471] The system controller selectively applies the first reference voltage and the second reference voltage to the comparator based on the operation of the light source.

[0472] (E-2)

[0473] The system of (E-1), wherein the image sensor comprises an RGB camera.

[0474] (E-3)

[0475] The system according to (E-1), wherein the operation is one of on-event signal detection and off-event signal detection.

[0476] (E-4)

[0477] The system of (E-1), wherein when the first reference voltage is applied to the comparator, the light source emits light and the event-based vision sensor stores on-event data in a memory of the system.

[0478] (E-5)

[0479] The system according to (E-4), wherein when the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores shutdown event data in the memory.

[0480] (E-6)

[0481] The system according to (E-5), wherein the stored on-event data and the off-event data are sequentially transferred to a readout circuit.

[0482] (E-7)

[0483] The system according to (E-5), wherein the stored on-event data and the off-event data are used to perform face detection processing.

[0484] (E-8)

[0485] The system of (E-5), wherein the on-event data and the off-event data are used to generate a depth map.

[0486] (E-9)

[0487] The system of (E-8), wherein the depth map is used to recognize a face.

[0488] (E-10)

[0489] The system according to (E-9), wherein the face is detected using the image sensor before applying the first reference voltage.

[0490] (E-11)

[0491] The system of (E-8), wherein the processor is configured to recognize a face using the depth map and the image signal.

[0492] (E-12)

[0493] The system according to (E-1), wherein the light source is a vertical cavity surface emitting laser.

[0494] (E-13)

[0495] The system according to (E-1), wherein the image sensor is controlled by a camera control section.

[0496] (F-1)

[0497] A method for driving a ranging system, the method comprising:

[0498] selectively applying, with a processor, one of a first reference voltage and a second reference voltage to the comparator based on operation of the light source; and

[0499] The one of the first reference voltage and the second reference voltage is compared with a first signal output by a circuit of a pixel using the comparator, wherein:

[0500] The light source is controlled by the processor and is configured to emit light,

[0501] The pixel is one of a plurality of pixels included in an event-based vision sensor,

[0502] The pixel includes: a photosensor configured to detect incident light; and a first circuit that outputs a first signal based on an output from the photosensor, and

[0503] The first signal represents a change in the amount of incident light.

[0504] (F-2)

[0505] The method according to (F-1), wherein the operation is one of on-event signal detection and off-event signal detection.

[0506] (F-3)

[0507] The method of (F-2), wherein when the first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores on-event data in a memory of the system.

[0508] (F-4)

[0509] The method according to (F-3), wherein when the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores turn-off event data in the memory.

[0510] (F-5)

[0511] The method according to (F-4), wherein the stored on-event data and the off-event data are sequentially transferred to a readout circuit.

[0512] (F-6)

[0513] The method according to (F-4), wherein the stored power-on event data and the power-off event data are used to perform face detection processing.

[0514] (F-7)

[0515] The method according to (F-1), wherein the light source is a vertical cavity surface emitting laser.

[0516] Those skilled in the art should understand that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as these modifications, combinations, sub-combinations and alterations are within the scope of the appended claims or the equivalents thereof.

[0517] Reference Signs List

[0518] 1 Ranging System

[0519] 10 Vertical Cavity Surface Emitting Laser (VCSEL)

[0520] 11 light sources (point light sources)

[0521] 20 event detection sensors (DVS)

[0522] 21 pixels

[0523] 22-pixel array unit

[0524] 23 drive unit

[0525] 24 Arbitrator Department

[0526] 25-column processing unit

[0527] 26 Signal Processing Unit

[0528] 30 System Control Department

[0529] 40 light source driving unit

[0530] 50 sensor control unit

[0531] 60 Light source side optical system

[0532] 70 Camera side optical system

[0533] 80 readout circuit

[0534] 91RGB Camera

[0535] 92 Camera Control Unit

[0536] 100 subjects

[0537] 200 application processor

Claims

1. A system comprising: processor; a light source controlled by the processor and configured to emit light; and An event-based vision sensor controlled by the processor, wherein the event-based vision sensor comprises: multiple pixels; and a comparator configured to output a comparison result based on at least one of a first reference voltage for detecting a turn-on event and a second reference voltage for detecting a turn-off event and the first signal, Wherein, at least one pixel among the plurality of pixels comprises: a photosensor configured to detect incident light; and a first circuit configured to output the first signal based on an output from the photosensor, wherein the first signal represents a change in an amount of incident light, The processor is configured to selectively apply one of the first reference voltage and the second reference voltage to the comparator based on the operation of the light source.

2. The system according to claim 1, wherein: The operation is one of on-event signal detection and off-event signal detection.

3. The system according to claim 2, wherein: When the first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores on-event data in a memory of the system.

4. The system according to claim 3, wherein: When the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores turn-off event data in the memory.

5. The system according to claim 4, wherein: The stored on-event data and the off-event data are sequentially transferred to a readout circuit.

6. The system according to claim 4, wherein: The stored on-event data and the off-event data are used to perform face detection processing.

7. The system according to any one of claims 1 to 6, wherein: The light source is a vertical cavity surface emitting laser.

8. A system comprising: an image sensor configured to output an image signal; a light source configured to emit light; an event-based vision sensor configured to output an event signal; a system controller configured to synchronously control the event-based vision sensor and the light source; and a processor configured to process the image signal and the event signal, The event-based vision sensor includes: multiple pixels; and a comparator configured to output a comparison result based on at least one of a first reference voltage for detecting a turn-on event and a second reference voltage for detecting a turn-off event and the first signal, Wherein, at least one pixel among the plurality of pixels comprises: a photosensor configured to detect incident light; and a first circuit that outputs the first signal based on an output from the photosensor, wherein the first signal represents a change in the amount of incident light, The system controller selectively applies the first reference voltage and the second reference voltage to the comparator based on the operation of the light source.

9. The system according to claim 8, wherein: The image sensor includes an RGB camera.

10. The system according to claim 8, wherein: The operation is one of on-event signal detection and off-event signal detection.

11. The system according to claim 8, wherein When the first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores on-event data in a memory of the system.

12. The system according to claim 11, wherein When the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores turn-off event data in the memory.

13. The system according to claim 12, wherein: The stored on-event data and the off-event data are sequentially transferred to a readout circuit.

14. The system according to claim 12, wherein: The stored on-event data and the off-event data are used to perform face detection processing.

15. The system according to claim 12, wherein: The on-event data and the off-event data are used to generate a depth map.

16. The system according to claim 15, wherein: The depth map is used to recognize faces.

17. The system according to claim 16, wherein: Before applying the first reference voltage, the face is detected using the image sensor.

18. The system according to claim 15, wherein: The processor is configured to recognize a face using the depth map and the image signal.

19. The system according to claim 8, wherein: The light source is a vertical cavity surface emitting laser.

20. The system according to any one of claims 8 to 19, wherein The image sensor is controlled by a camera control unit.

21. A method for driving a ranging system, the method comprising: selectively applying, with a processor, one of a first reference voltage for detecting a turn-on event and a second reference voltage for detecting a turn-off event to a comparator based on operation of the light source; and The one of the first reference voltage and the second reference voltage is compared with a first signal output by a circuit of a pixel using the comparator, wherein: The light source is controlled by the processor and is configured to emit light, The pixel is one of a plurality of pixels included in an event-based vision sensor, The pixel includes: a photosensor configured to detect incident light; and a first circuit that outputs the first signal based on an output from the photosensor, and The first signal represents a change in the amount of incident light.

22. The method according to claim 21, wherein The operation is one of on-event signal detection and off-event signal detection.

23. The method according to claim 22, wherein When the first reference voltage is applied to the comparator, the light source emits light, and the event-based vision sensor stores on-event data in a memory of the system.

24. The method according to claim 23, wherein When the second reference voltage is applied to the comparator, the light source stops emitting light, and the event-based vision sensor stores turn-off event data in the memory.

25. The method according to claim 24, wherein The stored on-event data and the off-event data are sequentially transferred to a readout circuit.

26. The method according to claim 24, wherein The stored on-event data and the off-event data are used to perform face detection processing.

27. The method according to any one of claims 21 to 26, wherein The light source is a vertical cavity surface emitting laser.

Images