Signal receiving system, signal processing method and detection chip

Abstract

This application discloses a signal receiving system, a signal processing method, and a detection chip. The signal receiving system includes a receiving array, N accumulation units, N buffer units, N event determination units, and a summarizing unit. The receiving array includes N receiving units. Each accumulation unit increments the photon count by one each time an avalanche breakdown occurs within a preset time period, obtaining a frame grayscale value for the corresponding pixel. The buffer units, upon receiving the current frame grayscale value of a corresponding pixel, store the current frame grayscale value and output the previous frame grayscale value. The event determination units determine whether an event has occurred for each pixel based on the difference between the current frame photon count value and the previous frame photon count value. The summarizing unit summarizes the difference, coordinates, and timestamp information corresponding to the pixels that have experienced events into event data. Through this method, an event camera can be implemented using a single-photon avalanche photodiode array.

Description

Technical Field

[0001] This application relates to the field of laser detection technology, and in particular to a signal receiving system, a signal processing method, and a detection chip. Background Technology

[0002] An event-based camera is a novel type of biologically inspired visual sensor, sometimes also called a dynamic vision sensor (DVS) or DAVIS (Dynamic and Active-PixelVision Sensor). Compared to standard cameras that acquire images at a fixed frame rate, it features low latency, high dynamic range, and high temporal resolution. Traditional CMOS image sensors generally struggle to meet the requirements of event cameras. Summary of the Invention

[0003] This application provides a signal receiving system, a signal processing method, and a detection chip that can realize an event camera through a single-photon avalanche photodiode array.

[0004] In a first aspect, embodiments of this application provide a signal receiving system, including a receiving array, N accumulation units, N buffer units, N event determination units, and a summarizing unit. The receiving array includes N receiving units, where each receiving unit is a single-photon avalanche photodiode, and N is an integer greater than 1. Each accumulation unit corresponds one-to-one with a receiving unit and is configured to increment the corresponding photon count by one each time an avalanche breakdown occurs within a preset time period, so as to obtain a frame grayscale value of the pixel corresponding to the corresponding receiving unit based on the accumulated photon count value within the preset time period, wherein one receiving unit corresponds to one pixel. Each buffer unit corresponds one-to-one with an accumulation unit and is configured to, upon receiving the current frame grayscale value of the corresponding pixel, store the current frame grayscale value of the corresponding pixel and output the previous frame grayscale value of the corresponding pixel, wherein the previous frame grayscale value is the grayscale value already stored in the buffer unit. The event determination unit corresponds one-to-one with the buffer unit. The event determination unit is configured to receive the current frame grayscale value and the previous frame grayscale value of the corresponding pixel, and determine whether an event has occurred for the corresponding pixel based on the difference between the current frame grayscale value and the previous frame grayscale value. The aggregation unit is configured to aggregate the difference, coordinates, and timestamp information corresponding to the pixels that have experienced events in a grayscale image frame into a frame of event data. The grayscale image includes multiple pixels.

[0005] In one or more embodiments, the signal receiving system further includes a quenching circuit disposed between the receiving array and N accumulating units, the quenching circuit being configured to quench and restore receiving units that have experienced avalanche breakdown.

[0006] In one or more embodiments, the signal receiving system further includes a frame rate configuration unit and a control unit. The frame rate configuration unit is configured to output corresponding frame rate information based on the determination result of the event determination unit. The control unit is configured to perform at least one of the following processes based on the frame rate information: adjusting the frame rate, adjusting the number of active receiving units in the receiving array, and controlling the active portions of the signal receiving system during the interval between each frame, wherein when a receiving unit is not active, the accumulator unit, buffer unit, and event determination unit corresponding to that receiving unit are all deactivated.

[0007] In one or more embodiments, the control unit is further configured to: when it is determined from the determination result that no event has occurred in the pixels of a series of grayscale images, perform at least one of the following processes based on the frame rate information: adjust the frame rate to decrease, adjust the number of activated receiving units in the receiving array to be less than N, and control all parts of the signal receiving system except the control unit to be turned off during the interval between each frame.

[0008] In one or more embodiments, the control unit is further configured to: when a pixel occurrence event in a grayscale image is determined based on a determination result, perform at least one of the following processes based on frame rate information: adjusting the frame rate increase, adjusting the number of activated receiving units in the receiving array to be equal to N, and controlling each part of the signal receiving system to be activated during the interval between each frame.

[0009] In one or more embodiments, the signal receiving system further includes a timestamp unit and a communication unit.

[0010] The timestamp unit is configured to acquire the timestamp information of the event and send the timestamp information to the aggregation unit. The communication unit is configured to communicate with external devices to send event data to the external devices.

[0011] Secondly, embodiments of this application provide a signal processing method applied to a receiving array, the receiving array including N receiving units, wherein the receiving unit is a single-photon avalanche photodiode, and N is an integer greater than 1. The method includes: within a preset time period, incrementing the corresponding photon count value by one each time an avalanche breakdown occurs in the receiving unit, so as to obtain a frame grayscale value of the pixel corresponding to the receiving unit based on the accumulated photon count value within the preset time period, wherein one receiving unit corresponds to one pixel; acquiring the current frame grayscale value and the previous frame grayscale value of each pixel, and determining whether an event has occurred in each pixel based on the difference between the current frame grayscale value and the previous frame grayscale value of each pixel; summarizing the difference, coordinates, and timestamp information corresponding to the pixels that have occurred in a frame grayscale image into a frame event data, wherein the grayscale image includes multiple pixels.

[0012] In one or more embodiments, the signal processing method further includes: when it is determined that no event has occurred in pixels of a series of grayscale images, performing at least one of the following processes: adjusting the frame rate to decrease, adjusting the number of activated receiving units in the receiving array to be less than N, and controlling all parts of the signal receiving system except the control unit to be turned off during the interval between each frame.

[0013] In one or more embodiments, the signal processing method further includes: upon determining that a pixel event has occurred in a grayscale image, performing at least one of the following processes: adjusting the frame rate increase, adjusting the number of activated receiving units in the receiving array to be equal to N, and controlling each part of the signal receiving system to be activated during the interval between each frame.

[0014] Thirdly, embodiments of this application provide a detection chip, including: a transmitting module and a signal receiving system as described in the first aspect. The transmitting module is configured to emit a detection laser. When the receiving array receives an echo signal, at least one receiving unit in the receiving array experiences avalanche breakdown, wherein the echo signal is a signal formed by the detection laser reflected from a target object.

[0015] The beneficial effects of this application are as follows: The signal receiving system of this application embodiment includes a receiving array, N accumulation units, N buffer units, N event determination units, and a summarizing unit. The receiving array includes N receiving units, wherein each receiving unit is a single-photon avalanche photodiode, and N is an integer greater than 1. Each accumulation unit corresponds one-to-one with a receiving unit. Within a preset time period, the accumulation unit increments the corresponding photon count value by one each time an avalanche breakdown occurs in the corresponding receiving unit, so as to obtain a frame grayscale value of the pixel corresponding to the corresponding receiving unit based on the accumulated photon count value within the preset time period, wherein one receiving unit corresponds to one pixel. Each buffer unit corresponds one-to-one with an accumulation unit. When the buffer unit receives the current frame grayscale value of the corresponding pixel, it stores the current frame grayscale value of the corresponding pixel and outputs the previous frame grayscale value of the corresponding pixel, wherein the previous frame grayscale value is the grayscale value already stored in the buffer unit. The event determination unit corresponds one-to-one with the buffer unit. The event determination unit receives the current frame grayscale value and the previous frame grayscale value of the corresponding pixel, and determines whether an event has occurred for the corresponding pixel based on the difference between the current frame grayscale value and the previous frame grayscale value. The aggregation unit aggregates the difference, coordinates, and timestamp information corresponding to the pixels that have experienced events in a frame of grayscale image into a frame of event data. Thus, the process of determining whether an event has occurred for each pixel and obtaining event data through a signal receiving system is realized. Furthermore, this signal receiving system includes a receiving array composed of N single-photon avalanche photodiodes, thereby realizing an event camera through a single-photon avalanche photodiode array. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are not intended to limit the embodiments, and elements having the same reference numerals in the drawings are designated as similar elements.

[0017] Figure 1 This is a schematic diagram of the signal receiving system provided in the embodiments of this application. Figure 1 ; Figure 2 This is a schematic diagram of the signal receiving system provided in the embodiments of this application. Figure 2 ; Figure 3 This is a schematic diagram of the signal receiving system provided in the embodiments of this application. Figure 3 ; Figure 4 This is a schematic diagram of the signal receiving system provided in the embodiments of this application. Figure 4 ; Figure 5 This is a schematic diagram of the detection chip provided in an embodiment of this application; Figure 6 This is a flowchart of the signal processing method provided in the embodiments of this application.

[0018] Figure label: 2000, Target object; 1000, Detection chip; 200, Transmitting module; 100, Signal receiving system; 60, Communication unit; 50, Timestamp unit; 40, Control unit; 30, Frame rate configuration unit; 20, Summarizing unit; 10, Receiving array. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and thoroughly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0020] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements between them.

[0021] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0022] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the block diagram of the signal receiving system provided in an embodiment of this application. Figure 1As shown, the signal receiving system 100 includes a receiving array 10, N accumulator units, N buffer units, N event determination units, and a summarizing unit 20.

[0023] The receiving array 10 comprises N receiving units, each of which is a single-photon avalanche photodiode, where N is an integer greater than 1. The N receiving units include a first receiving unit A1, a second receiving unit A2, ..., an Nth receiving unit AN. A single-photon avalanche diode (SPAD) is a highly sensitive semiconductor photodetector capable of detecting a single photon. A SPAD can detect a single photon and output a digital pulse signal that can be recognized by a circuit.

[0024] The N accumulation units include a first accumulation unit B1, a second accumulation unit B2, ..., an Nth accumulation unit BN. Each accumulation unit corresponds one-to-one with a receiving unit. The accumulation unit is configured to increment the corresponding photon count by one each time an avalanche breakdown occurs in the corresponding receiving unit within a preset time period. This allows the accumulation of the photon count within the preset time period to obtain a frame of grayscale value for the pixel corresponding to the receiving unit. Here, one receiving unit corresponds to one pixel. Specifically, the first accumulator B1 increments the corresponding photon count by one each time the first receiver A1 experiences an avalanche breakdown within a preset time period, obtaining the accumulated photon count within the preset time period. Then, based on the accumulated photon count within the preset time period, it obtains a frame of grayscale value for the pixel corresponding to the first receiver A1. Similarly, the second accumulator B2 increments the corresponding photon count by one each time the second receiver A2 experiences an avalanche breakdown within a preset time period, obtaining the accumulated photon count within the preset time period. Then, based on the accumulated photon count within the preset time period, it obtains a frame of grayscale value for the pixel corresponding to the second receiver A2. ...; the Nth accumulator BN increments the corresponding photon count by one each time the Nth receiver AN experiences an avalanche breakdown within a preset time period, obtaining the accumulated photon count within the preset time period. Then, based on the accumulated photon count within the preset time period, it obtains a frame of grayscale value for the pixel corresponding to the Nth receiver AN. Grayscale value refers to the brightness level of each pixel in an image. In digital image processing, grayscale values ​​are usually represented by integers from 0 to 255. 0 represents black, 255 represents white, and values ​​in between represent different levels of gray.

[0025] It is understandable that the preset duration is a pre-set duration that can be set based on the actual application scenario. The preset duration can also be understood as the exposure duration, which represents the total time window from when the system begins receiving photon events (i.e., when the receiving unit is allowed to start and record photons) to when recording stops. This means that a longer preset duration allows more photons to be detected. In other words, within the preset duration, each receiving unit continuously detects incident photons, and each receiving unit updates its corresponding photon count value according to the flight time of the received photons, thus obtaining the accumulated photon count value for each receiving unit. The flight time is the time from when the detection laser from the transmitting module occurs to when each receiving unit experiences avalanche breakdown.

[0026] The N buffer units include a first buffer unit C1, a second buffer unit C2, ..., an Nth buffer unit CN. Each buffer unit corresponds one-to-one with an accumulation unit. A buffer unit is configured to, upon receiving the current frame grayscale value of a corresponding pixel, store the current frame grayscale value of that pixel and output the previous frame grayscale value of that pixel, where the previous frame grayscale value is the grayscale value already stored in the buffer unit. Specifically, when the first accumulation unit B1 outputs a frame grayscale value of a corresponding pixel, this frame grayscale value is recorded as the current frame grayscale value of the pixel corresponding to the first receiving unit A1. When the first buffer unit C1 receives the current frame grayscale value of the pixel corresponding to the first receiving unit A1, it stores the current frame grayscale value of the pixel corresponding to the first receiving unit A1 and outputs the previous frame grayscale value of the pixel corresponding to the first receiving unit A1. When the second accumulation unit B2 outputs a frame grayscale value of a corresponding pixel, this frame grayscale value is recorded as the current frame grayscale value of the pixel corresponding to the second receiving unit A2. When the second buffer unit C2 receives the current frame grayscale value of the pixel corresponding to the first receiving unit A1, it stores the current frame grayscale value of the pixel corresponding to the first receiving unit A1 and outputs the previous frame grayscale value of the pixel corresponding to the first receiving unit A1. When the current frame grayscale value of the pixel corresponding to the second receiving unit A2 is received, the current frame grayscale value of the pixel corresponding to the second receiving unit A2 is stored and the previous frame grayscale value of the pixel corresponding to the second receiving unit A2 is output; ...; when the Nth accumulator BN outputs a frame grayscale value of the corresponding pixel, this frame grayscale value is recorded as the current frame grayscale value of the pixel corresponding to the Nth receiving unit AN. When the Nth buffer unit CN receives the current frame grayscale value of the pixel corresponding to the Nth receiving unit AN, it stores the current frame grayscale value of the pixel corresponding to the Nth receiving unit AN and outputs the previous frame grayscale value of the pixel corresponding to the Nth receiving unit AN. It can be understood that if the buffer unit does not have a frame grayscale value of the corresponding pixel, then when the buffer unit receives the current frame grayscale value of the corresponding pixel, it can simply store the current frame grayscale value of the corresponding pixel.

[0027] The N event determination units include a first event determination unit D1, a second event determination unit D2, ..., an Nth event determination unit DN. Each event determination unit corresponds one-to-one with a buffer unit. The event determination unit is configured to receive the current frame grayscale value and the previous frame grayscale value of the corresponding pixel, and determine whether an event has occurred for the corresponding pixel based on the difference between the current frame grayscale value and the previous frame grayscale value. Specifically, the first event determination unit D1 receives the current frame grayscale value of the pixel corresponding to the first receiving unit A1 output by the first accumulator B1, and receives the previous frame grayscale value of the pixel corresponding to the first receiving unit A1 output by the first buffer unit C1, and then determines whether an event has occurred for the pixel corresponding to the first receiving unit A1 based on the difference between the current frame grayscale value and the previous frame grayscale value; the second event determination unit D2 receives the current frame grayscale value of the pixel corresponding to the second receiving unit A2 output by the second accumulator B2, and receives the previous frame grayscale value of the pixel corresponding to the second receiving unit A2 output by the second buffer unit C2. The corresponding pixel's previous frame grayscale value is used as the basis for determining whether an event has occurred in the pixel corresponding to the second receiving unit A1, based on the difference between the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the second receiving unit A2; ...; The Nth event determination unit DN receives the current frame grayscale value of the pixel corresponding to the Nth receiving unit AN output by the Nth accumulator unit BN, and receives the previous frame grayscale value of the pixel corresponding to the Nth receiving unit AN output by the Nth buffer unit CN, and then determines whether an event has occurred in the pixel corresponding to the Nth receiving unit AN based on the difference between the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the Nth receiving unit AN.

[0028] In some embodiments, if the difference between the current frame grayscale value and the previous frame grayscale value corresponding to any pixel is greater than a first preset threshold, then it is determined that an event has occurred for that pixel; if the difference between the current frame grayscale value and the previous frame grayscale value corresponding to any pixel is less than or equal to the first preset threshold, then it is determined that no event has occurred for that pixel. Specifically, when the difference between the current frame grayscale value and the previous frame grayscale value corresponding to any pixel is greater than the first preset threshold, it can be considered that the grayscale value of that pixel has changed significantly, causing a change in the image content, and thus an event is considered to have occurred for that pixel; otherwise, no event is considered to have occurred for that pixel. It is understood that the first preset threshold is a pre-set threshold that can be set based on the actual application scenario.

[0029] The aggregation unit 20 is configured to aggregate the difference, coordinates, and timestamp information corresponding to the pixels where an event occurs in a grayscale image frame into a frame of event data. The grayscale image includes multiple pixels. Specifically, based on the aforementioned information, the pixels where the event occurs in a grayscale image frame can be determined, and the difference between the current frame grayscale value and the previous frame grayscale value of the pixels where the event occurred can be obtained. Furthermore, based on the coordinates of the receiving unit corresponding to the pixels where the event occurred in the grayscale image frame, the coordinates of the pixels where the event occurred are determined. Finally, based on the specific time when the event occurred in the pixels of the grayscale image frame, the timestamp information of the pixels where the event occurred is determined.

[0030] In summary, the process of determining whether an event has occurred at each pixel and obtaining event data through the signal receiving system 100 is realized. Furthermore, the signal receiving system 100 includes a receiving array composed of N single-photon avalanche photodiodes (denoted as a single-photon avalanche photodiode array), thus realizing an event camera through the signal receiving system 100 including the single-photon avalanche photodiode array.

[0031] In some embodiments, such as Figure 2 As shown, the signal receiving system 100 also includes a quenching circuit 30.

[0032] The quenching circuit 30 is located between the receiving array 10 and the N accumulating units. The quenching circuit 30 is configured to quench and restore the receiving unit that has experienced avalanche breakdown. Specifically, the quenching circuit 30 is used to immediately reduce the bias voltage below the breakdown voltage after the single-photon avalanche photodiode is triggered by avalanche, terminate the avalanche process, and restore the single-photon avalanche photodiode within a safe time, so that the single-photon avalanche photodiode regains its detection capability, thereby achieving repeated and reliable detection of a single photon.

[0033] In some embodiments, such as Figure 3 As shown, the signal receiving system 100 also includes a frame rate configuration unit 30 and a control unit 40.

[0034] The frame rate configuration unit 30 is configured to output corresponding frame rate information based on the determination result of the event determination unit. The determination result of any event determination unit is whether an event has occurred or not for the pixel corresponding to the receiving unit corresponding to that event determination unit. For example, the determination result of the first event determination unit D1 is whether an event has occurred or not for the pixel corresponding to the receiving unit (i.e., the first receiving unit A1) corresponding to the first event determination unit D1. Frame rate refers to the number of image frames displayed per second, usually measured in FPS (Frames Per Second).

[0035] The control unit 40 is configured to perform at least one of the following processes based on frame rate information: adjusting the frame rate, adjusting the number of active receiving units in the receiving array 10, and controlling the active portion of the signal receiving system during the interval between frames. When a receiving unit is not active, the corresponding accumulation unit, buffer unit, and event determination unit are all deactivated. On one hand, this allows for dynamic adjustment of the frame rate based on the determination result, avoiding unnecessary power consumption caused by a fixed high frame rate. On the other hand, it allows for dynamic adjustment of the number of active receiving units based on the determination result, thereby reducing the number of active receiving units at low frame rates to lower power consumption. Furthermore, it allows for dynamic control of the active portion of the signal receiving system 100 during the interval between frames based on the determination result, thereby selectively deactivating at least some modules or units in the signal receiving system 100 during the interval between frames to lower power consumption. The interval between frames refers to the time interval between two image acquisition frames (i.e., the idle period in the frame period). The "enabled parts" in the signal receiving system 100 refer to the various modules or units that are enabled in the signal receiving system 100, such as the receiving array 10, the summarizing unit 20, the quenching circuit 30, each accumulation unit, each buffer unit, and each event determination unit.

[0036] In some embodiments, the control unit 40 is further configured to: when it is determined, based on the determination result, that no event has occurred in the pixels of a series of consecutive grayscale images, perform at least one of the following processes based on the frame rate information: adjust the frame rate to decrease, adjust the number of activated receiving units in the receiving array 10 to be less than N, and deactivate all parts of the inter-frame interval control signal receiving system 100 except for the control unit 40. At this time, the frame rate configuration unit 30 outputs the corresponding frame rate information as a low frame rate based on the determination result of the event determination unit.

[0037] Specifically, firstly, when the signal receiving system 100 starts working, it samples using a default frame rate. Then, if the determination result indicates that no events have occurred in pixels across multiple consecutive grayscale images, the frame rate can be gradually reduced to save power. Furthermore, the number of active receiving units in the receiving array 10 can be adjusted to be less than N, i.e., some receiving units in the receiving array 10 can be turned off. For example, only one receiving unit can be active in each 2x2 receiving unit group, or only one receiving unit can be active in each 4x4 receiving unit group. When a receiving unit is not active, the corresponding accumulator, buffer, and event determination unit are all turned off. For example, when the first receiving unit A1 is not active, the first accumulator B1, the first buffer C1, and the first event determination unit D1 are all turned off, which also reduces power consumption. Additionally, during the interval between each frame, all parts of the signal receiving system 100 except for the control unit 40 are turned off to reduce power consumption.

[0038] In some embodiments, the control unit 40 is further configured to: when a pixel occurrence event is determined in the grayscale image based on the determination result, execute at least one of the following processes based on the frame rate information: adjust the frame rate increase, adjust the number of activated receiving units in the receiving array 10 to be equal to N, and control all parts of the signal receiving system 100 to be activated during the interval between each frame. At this time, the frame rate configuration unit 30 outputs the corresponding frame rate information as a standard frame rate or a high frame rate based on the determination result of the event determination unit.

[0039] If the determination result indicates that an event has occurred in a pixel of the grayscale image, then on the one hand, the frame rate can be adjusted to increase in order to ensure detailed tracking of the event; on the other hand, the number of receiving units turned on in the receiving array 10 can be adjusted to be equal to N, that is, all receiving units in the receiving array 10 are turned on, and all parts of the signal receiving system 100 are turned on.

[0040] In some embodiments, such as Figure 4 As shown, the signal receiving system 100 also includes a timestamp unit 50 and a communication unit 60.

[0041] The timestamp unit 50 is configured to acquire the timestamp information of the event and send the timestamp information to the aggregation unit 20. The communication unit 60 is configured to communicate with an external device to send event data to the external device.

[0042] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the detection chip provided in an embodiment of this application. Figure 5 As shown, the detector chip 1000 includes a signal receiving system 100 and a transmitting module 200 in any embodiment of this application.

[0043] The emitting module 200 is configured to emit a probe laser. In some embodiments, the emitting module 200 includes an emitting array comprising a plurality of emitting devices. In some embodiments, the emitting devices are vertical-cavity surface-emitting lasers (VCSELs) or edge-emitting lasers (EELs).

[0044] When the receiving array 10 in the signal receiving system 100 receives an echo signal, at least one receiving unit in the receiving array 10 undergoes avalanche breakdown. The echo signal is the signal formed by the reflection of the probe laser from the target object 2000. Subsequently, the signal receiving system 100 can generate a grayscale image, determine whether an event has occurred in a pixel of the grayscale image, and summarize the difference, coordinates, and timestamp information corresponding to the pixels in the grayscale image where an event occurred into event data. Thus, an event camera is realized using a single-photon avalanche photodiode array.

[0045] Please refer to Figure 6 , Figure 6 This is a flowchart illustrating a signal processing method provided in an embodiment of this application. The signal processing method is applied to a receiving array, which includes N receiving units, where each receiving unit is a single-photon avalanche photodiode, and N is an integer greater than 1. Figure 6 As shown, the signal processing method includes the following steps S610 to S630.

[0046] Step S610: Within a preset time period, each time an avalanche breakdown occurs in the receiving unit, the corresponding photon count value is incremented by one, so as to obtain a frame grayscale value of the pixel corresponding to the receiving unit based on the accumulated photon count value within the preset time period, wherein one receiving unit corresponds to one pixel.

[0047] Step S620: Obtain the current frame grayscale value and the previous frame grayscale value of each pixel, and determine whether an event has occurred for each pixel based on the difference between the current frame grayscale value and the previous frame grayscale value of each pixel.

[0048] Step S630: The difference, coordinates and timestamp information corresponding to the pixels where the event occurred in a grayscale image frame are summarized into a frame of event data, wherein the grayscale image includes multiple pixels.

[0049] Specifically, within a preset time period, each time an avalanche breakdown occurs in the first receiving unit A1, the corresponding photon count value is incremented by one, and the accumulated photon count value within the preset time period is obtained. Then, based on the accumulated photon count value within the preset time period, a frame grayscale value of the pixel corresponding to the first receiving unit A1 is obtained. Next, the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the first receiving unit A1 are obtained. Then, based on the difference between the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the first receiving unit A1, it is determined whether an event has occurred in the pixel corresponding to the first receiving unit A1.

[0050] Within a preset time period, each time an avalanche breakdown occurs in the second receiving unit A2, the corresponding photon count value is incremented by one, and the accumulated photon count value within the preset time period is obtained. Then, based on the accumulated photon count value within the preset time period, a frame grayscale value of the pixel corresponding to the second receiving unit A2 is obtained. Next, the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the second receiving unit A2 are obtained. Then, based on the difference between the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the second receiving unit A2, it is determined whether an event has occurred at the pixel corresponding to the second receiving unit A2.

[0051] And so on… Within a preset time period, each time an avalanche breakdown occurs in the Nth receiving unit AN, the corresponding photon count value is incremented by one, and the accumulated photon count value within the preset time period is obtained. Then, based on the accumulated photon count value within the preset time period, a frame grayscale value of the pixel corresponding to the Nth receiving unit AN is obtained. Next, the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the Nth receiving unit AN are obtained. Then, based on the difference between the current frame grayscale value and the previous frame grayscale value of the pixel corresponding to the Nth receiving unit AN, it is determined whether an event has occurred in the pixel corresponding to the Nth receiving unit AN.

[0052] Thus, based on the above, the pixel in a grayscale image where the event occurred can be determined, and the difference between the current frame grayscale value and the previous frame grayscale value of the pixel in a grayscale image where the event occurred can be obtained; and based on the coordinates of the receiving unit corresponding to the pixel in a grayscale image where the event occurred, the coordinates of the pixel in a grayscale image where the event occurred can be determined; and based on the specific time when the event occurred in the pixel in a grayscale image, the timestamp information of the pixel in a grayscale image where the event occurred can be determined.

[0053] In some embodiments, the signal processing method further includes the following steps: when it is determined that no event has occurred in the pixels of a series of grayscale images, performing at least one of the following processes: adjusting the frame rate to decrease, adjusting the number of activated receiving units in the receiving array to be less than N, and controlling all parts of the signal receiving system except the control unit to be turned off during the interval between each frame.

[0054] Specifically, firstly, when the signal receiving system 100 starts working, it samples using a default frame rate. Then, if it is determined that no events have occurred in the pixels of consecutive grayscale images, the frame rate can be gradually reduced to save power. Furthermore, the number of active receiving units in the receiving array 10 can be adjusted to be less than N, i.e., some receiving units in the receiving array 10 can be turned off. Additionally, during the intervals between frames, all parts of the signal receiving system 100 except for the control unit 40 are turned off to reduce power consumption.

[0055] In some embodiments, the signal processing method further includes the following steps: when determining that a pixel event has occurred in a grayscale image, performing at least one of the following processes: adjusting the frame rate increase, adjusting the number of activated receiving units in the receiving array to be equal to N, and controlling each part of the signal receiving system to be activated during the interval between each frame.

[0056] If the determination result indicates that an event has occurred in a pixel of the grayscale image, then on the one hand, the frame rate can be adjusted to increase in order to ensure detailed tracking of the event; on the other hand, the number of receiving units turned on in the receiving array 10 can be adjusted to be equal to N, that is, all receiving units in the receiving array 10 are turned on, and all parts of the signal receiving system 100 are turned on.

[0057] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

[0058] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A signal receiving system, characterized in that, include: The receiving array includes N receiving units, wherein each receiving unit is a single-photon avalanche photodiode, and N is an integer greater than 1; There are N accumulation units, each of which corresponds to a receiving unit. The accumulation unit is configured to increment the corresponding photon count value by one each time the corresponding receiving unit experiences an avalanche breakdown within a preset time period, so as to obtain a frame grayscale value of the pixel corresponding to the receiving unit based on the accumulated photon count value within the preset time period. Here, one receiving unit corresponds to one pixel. There are N buffer units, each of which corresponds to one of the accumulation units. Each buffer unit is configured to store the current frame grayscale value of the corresponding pixel and output the previous frame grayscale value of the corresponding pixel when the current frame grayscale value of the corresponding pixel is received. The previous frame grayscale value is the grayscale value that has been stored in the buffer unit. There are N event determination units, each corresponding to one of the cache units. Each event determination unit is configured to receive the current frame grayscale value and the previous frame grayscale value of the corresponding pixel, and determine whether an event has occurred for the corresponding pixel based on the difference between the current frame grayscale value and the previous frame grayscale value. The aggregation unit is configured to aggregate the difference, coordinates, and timestamp information corresponding to the pixels where an event occurs in a grayscale image frame into a frame of event data, wherein the grayscale image includes multiple pixels.

2. The signal receiving system according to claim 1, characterized in that, Also includes: A quenching circuit, located between the receiving array and the N accumulating units, is configured to quench and restore receiving units that have experienced avalanche breakdown.

3. The signal receiving system according to claim 1 or 2, characterized in that, Also includes: The frame rate configuration unit is configured to output corresponding frame rate information based on the determination result of the event determination unit; The control unit is configured to perform at least one of the following processes based on the frame rate information: adjusting the frame rate, adjusting the number of active receiving units in the receiving array, and controlling the active portions of the signal receiving system during the interval between each frame, wherein when a receiving unit is not active, the accumulator, buffer, and event determination unit corresponding to that receiving unit are all deactivated.

4. The signal receiving system according to claim 3, characterized in that, The control unit is also configured to: When it is determined, based on the determination result, that no event has occurred in the pixels of a series of grayscale images, at least one of the following processes is executed according to the frame rate information: adjusting the frame rate to decrease, adjusting the number of activated receiving units in the receiving array to be less than N, and controlling all parts of the signal receiving system except the control unit to be turned off during the interval between each frame.

5. The signal receiving system according to claim 3, characterized in that, The control unit is also configured to: When determining a pixel occurrence event in a grayscale image based on the determination result, at least one of the following processes is performed based on the frame rate information: adjusting the frame rate increase, adjusting the number of activated receiving units in the receiving array to equal N, and controlling all parts of the signal receiving system to be activated during the interval between each frame.

6. The signal receiving system according to claim 1, characterized in that, Also includes: The timestamp unit is configured to acquire timestamp information of the event that occurred and send the timestamp information to the aggregation unit; The communication unit is configured to communicate with an external device to send the event data to the external device.

7. A signal processing method, characterized in that, The method is applied to a receiving array comprising N receiving units, wherein each receiving unit is a single-photon avalanche photodiode, and N is an integer greater than 1. Within a preset time period, each time an avalanche breakdown occurs in the receiving unit, the corresponding photon count value is incremented by one, so as to obtain a frame grayscale value of the pixel corresponding to the receiving unit based on the accumulated photon count value within the preset time period, wherein one receiving unit corresponds to one pixel. Get the current frame grayscale value and the previous frame grayscale value of each pixel, and determine whether an event has occurred for each pixel based on the difference between the current frame grayscale value and the previous frame grayscale value. The difference, coordinates, and timestamp information corresponding to the pixels where an event occurs in a grayscale image frame are summarized into a frame of event data, wherein the grayscale image includes multiple pixels.

8. The signal processing method according to claim 7, characterized in that, The method further includes: When it is determined that no event has occurred in the pixels of a series of grayscale images, at least one of the following processes is performed: adjusting the frame rate to decrease, adjusting the number of activated receiving units in the receiving array to be less than N, and controlling all parts of the signal receiving system except the control unit to be turned off during the interval between each frame.

9. The signal processing method according to claim 8, characterized in that, The method further includes: When a pixel event is determined to occur in a grayscale image, at least one of the following processes is performed: adjusting the frame rate increase, adjusting the number of activated receiving units in the receiving array to N, and controlling all parts of the signal receiving system to be activated during the interval between each frame.

10. A detection chip, characterized in that, include: The transmitting module is configured to emit a detection laser; And, in the signal receiving system according to any one of claims 1-7, when the receiving array receives an echo signal, at least one receiving unit in the receiving array experiences avalanche breakdown, wherein the echo signal is a signal formed by the detection laser reflected from the target object.

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