A light intensity change detection module and image sensor

Abstract

The present invention discloses a light intensity change detection module and an image sensor. The light intensity change detection module includes: a plurality of light intensity change detection pixel units, which are suitable for responding to light intensity changes in the field of view and entering a trigger state when the light intensity change meets a predetermined condition, and outputting a current pulse signal; a light intensity change detection control unit, which is coupled to each light intensity change detection pixel unit, and is suitable for judging whether the total pulse current is greater than a threshold value based on the current pulse signal, and generating a pulse signal when the total pulse current is greater than the threshold value; the light intensity change detection pixel unit is also suitable for being set after entering the trigger state to re-respond to the light intensity change in the field of view and continuously output the current pulse signal; the light intensity change detection control unit is also suitable for judging whether the light intensity change is a periodic light intensity change based on the pulse signal, and generating and outputting the frequency information of the light intensity change when the light intensity change is a periodic light intensity change. The present invention also discloses a method for detecting periodic light intensity changes.

Description

Technical Field

[0001] The present invention relates to the technical field of image sensors, and in particular to a light intensity change detection module and an image sensor. Background Art

[0002] In recent years, dynamic vision image sensors, which only perceive dynamic information within the field of view, have gained increasing attention due to their advantages in motion detection. As a biomimetic device, their basic operating principle differs significantly from that of mainstream active-pixel sensors. Dynamic vision image sensors abandon the concept of image frames, focusing solely on the dynamic components of the field of view that cause light intensity variations and automatically filtering out useless background information. Specifically, each pixel in the sensor no longer passively senses external light intensity, but instead actively monitors light intensity variations in real time and outputs its position information when the intensity changes meet certain conditions. This operating method automatically filters out useless background information at the sensor level, allowing the dynamic vision image sensor to output only the data stream information from the useful pixel units, thus saving output bandwidth. This allows the back-end image processing system to directly acquire and process the useful dynamic information in the field of view, significantly reducing storage and computing power requirements and achieving better real-time performance.

[0003] On the other hand, brief changes in light intensity, such as "flashes" in the field of view, can also cause changes in light intensity in the corresponding pixel area, causing the dynamic vision image sensor to output data. In some scenarios, this "flash" is completely unrelated to the object's motion and is simply a momentary or periodic change in light intensity at certain locations in the field of view. For example, if there is an LED light indoors that flashes at a fixed frequency, the periodic flashes appearing throughout the field of view will cause all pixels to detect the light intensity changes and be output by the sensor. However, this data output by the sensor does not accurately represent the object's motion information. If the data is not differentiated, the performance of the various motion detection algorithms executed by the back-end processor will be reduced, limiting the application scenarios of dynamic vision sensors.

[0004] Based on the above pain points, a solution is needed that can detect changes in light intensity in the field of view that do not represent object motion information. Summary of the Invention

[0005] The present invention provides a light intensity change detection module and an image sensor, in an effort to solve or at least alleviate at least one of the above problems.

[0006] According to one aspect of the present invention, a light intensity change detection module is provided, comprising: a plurality of light intensity change detection pixel units, the light intensity change detection pixel units being adapted to respond to light intensity changes in a field of view and entering a trigger state when the light intensity change meets a predetermined condition, and outputting a current pulse signal; a light intensity change detection control unit being coupled to each light intensity change detection pixel unit, being adapted to determine whether a total pulse current is greater than a threshold value based on the current pulse signal from each light intensity change detection pixel unit, and generating a pulse signal when the total pulse current is greater than the threshold value; the light intensity change detection pixel unit being further adapted to be set after entering the trigger state, so as to re-respond to light intensity changes in the field of view and continuously output current pulse signals to the light intensity change detection control unit; and the light intensity change detection control unit being further adapted to determine whether the light intensity change is a periodic light intensity change based on the pulse signal, and to generate and output frequency information of the light intensity change when the light intensity change is a periodic light intensity change.

[0007] Optionally, in the light intensity change detection module according to the present invention, the light intensity change detection control unit includes: a light intensity change judgment subunit, suitable for receiving current pulse signals from all light intensity change detection units via the current pulse output signal line, and generating a pulse signal when the total pulse current is greater than a threshold; a pulse frequency judgment subunit, suitable for judging whether the pulse signal is a periodic signal by calculating the time difference between multiple pulse signals. If the pulse signal is a periodic signal, the light intensity change is a periodic light intensity change.

[0008] Optionally, in the light intensity change detection module according to the present invention, the pulse frequency judgment subunit is also suitable for calculating the time difference between adjacent pulses, and determining that the pulse signal is a periodic signal when the time difference between adjacent pulse signals is the same; and the pulse frequency judgment subunit is also suitable for calculating the frequency information of the light intensity change based on the time difference when determining that the light intensity change is a periodic light intensity change.

[0009] Optionally, in the light intensity change detection module according to the present invention, the light intensity change detection pixel unit includes: a photoelectric detection subunit, suitable for monitoring the light signal irradiated thereon in real time and outputting a corresponding electrical signal; a trigger generation subunit, a first input end of which is coupled to the photoelectric detection subunit, and a first output end of which is coupled to the logic subunit, the trigger generation subunit being suitable for generating a trigger generation signal to the logic subunit when the electrical signal meets a predetermined condition; a logic subunit, an input end of which is coupled to the trigger generation subunit, and an output end is coupled to the current pulse generation subunit, the logic subunit being suitable for outputting a signal to the current pulse generation subunit upon receiving the trigger generation signal; and a current pulse generation subunit being suitable for generating and outputting a current pulse signal upon receiving the output signal of the logic subunit.

[0010] Optionally, in the light intensity change detection module according to the present invention, the logic subunit includes a latch and a delay circuit. When the trigger generation signal is received, the latch is set, and after the delay of the delay circuit, the latch is restored to the reset state; and the output signal of the latch is the reset signal of the trigger generation subunit, so as to reset the trigger generation subunit during the period when the latch is set.

[0011] Optionally, in the light intensity change detection module according to the present invention, the current pulse generating subunit includes: a current source; a transistor, whose gate is connected to the output of the logic subunit, whose source is connected to the current source, and whose drain is coupled to the light intensity change detection control unit through the current pulse output signal line.

[0012] Optionally, in the light intensity change detection module according to the present invention, the light intensity change judgment subunit includes: a reference current source; a current comparator, whose non-inverting input terminal is connected to the current pulse output signal line, and the inverting input terminal is connected to the reference current source, and whose output terminal is connected to the pulse frequency judgment subunit, which is suitable for outputting a pulse signal to the pulse frequency judgment subunit when it is judged that the total pulse current from the current pulse output signal line exceeds the reference current source.

[0013] Optionally, in the light intensity change detection module according to the present invention, the light intensity change judgment subunit includes: a current analog-to-digital converter, whose input end is connected to the current pulse output signal line, and whose output end is connected to the digital comparator, suitable for quantizing the total current pulse into a digital signal and outputting it to the digital comparator; a digital comparator, whose input end is connected to the current analog-to-digital converter, and whose output end is connected to the pulse frequency judgment subunit, suitable for outputting a pulse signal to the pulse frequency judgment subunit after confirming that the output of the current analog-to-digital converter exceeds the threshold.

[0014] Optionally, in the light intensity change detection module according to the present invention, the threshold is determined based on at least the number of light intensity change detection pixel units.

[0015] Optionally, in the light intensity change detection module according to the present invention, a plurality of light intensity change detection pixel units are arranged around the main pixel array, and the main pixel array is suitable for triggering the corresponding main pixel unit when the light intensity change in the field of view reaches a predetermined condition, and at least outputting the address information of the triggered main pixel unit; and the number of light intensity change detection pixel units is determined based on the main pixel array.

[0016] According to another aspect of the present invention, a method for detecting periodic light intensity changes is provided, which is suitable for execution in the light intensity change detection module as described above, and includes: generating a current pulse signal by monitoring the light intensity changes in the field of view, wherein the current pulse signal is generated when the light intensity change meets a predetermined condition; determining whether to generate a pulse signal by judging the size of the current pulse signal; repeatedly iterating the steps of monitoring the light intensity changes and judging the size of the current pulse signal to generate multiple pulse signals; and judging whether the light intensity change is a periodic light intensity change by calculating the time difference between the multiple pulse signals.

[0017] Optionally, the method according to the present invention further comprises: when it is determined that the light intensity variation is a periodic light intensity variation, outputting frequency information of the light intensity variation.

[0018] Optionally, in the method according to the present invention, whether to generate a pulse signal is determined by judging the size of the current pulse signal, including: when the total instantaneous current of the received current pulse signal is greater than a threshold, confirming the generation of the pulse signal.

[0019] According to yet another aspect of the present invention, an image sensor is provided, comprising: a core circuit component adapted to trigger a corresponding primary pixel unit when a light intensity change in a field of view satisfies a predetermined condition, and to output at least address information of the triggered primary pixel unit; and a light intensity change detection module as described above, arranged around the primary pixel array, adapted to detect periodic light intensity changes based on the light intensity changes in the field of view.

[0020] Optionally, in the image sensor according to the present invention, the core circuit component includes a main pixel array, and the main pixel array includes multiple main pixel units; the number of light intensity change detection pixel units in the light intensity change detection module is determined by the number of rows and columns of the main pixel array.

[0021] In summary, the present invention's solution, without changing the existing dynamic vision sensor structure, can detect periodic light intensity variations in the field of view by adding an independent light intensity variation detection module. When periodic light intensity variations occur in the field of view, the module outputs the frequency information of these variations to the back-end processing unit. This solution effectively reduces the interference of these periodic light intensity variations in the field of view on the output data of the dynamic vision sensor, improving motion detection performance.

[0022] At the same time, the light intensity change detection module does not need to be coupled to the core circuit components. On the one hand, the core circuit components and the light intensity change detection module can independently complete their respective tasks without affecting each other, thereby improving the working efficiency of the image sensor; on the other hand, the light intensity change detection module is easy to deploy, and only needs to determine the number of light intensity change detection pixel units based on the main pixel array in the core circuit components. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To achieve the above and related purposes, certain illustrative aspects are described herein in conjunction with the following description and accompanying drawings, which indicate various ways in which the principles disclosed herein may be practiced, and all aspects and their equivalents are intended to fall within the scope of the claimed subject matter. The above and other objects, features, and advantages of the present disclosure will become more apparent by reading the following detailed description in conjunction with the accompanying drawings. Throughout this disclosure, the same reference numerals generally refer to the same parts or elements.

[0024] Figure 1 shows a schematic diagram of an image sensor 100 according to some embodiments of the present invention;

[0025] Figure 2 shows a schematic diagram of a light intensity change detection module 120 according to some embodiments of the present invention;

[0026] Figure 3 shows a schematic diagram of a current pulse generating subunit 240 according to some embodiments of the present invention;

[0027] Figure 4 shows a schematic diagram of a light intensity change detection control unit 400 according to some embodiments of the present invention;

[0028] Figure 5A and Figure 5B Schematic diagrams of the light intensity change determination subunit 410 according to some embodiments of the present invention are respectively shown;

[0029] Figure 6 FIG. 6 is a flow chart illustrating a method 600 for detecting periodic light intensity changes according to some embodiments of the present invention. DETAILED DESCRIPTION

[0030] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0031] As mentioned above, the dynamic visual image sensor (hereinafter referred to as the dynamic visual sensor) detects dynamic information in the field of view at the pixel level. Each pixel unit in the dynamic visual sensor monitors the change in light intensity in real time, and confirms the occurrence of a pixel event when the change reaches a predetermined condition (the predetermined condition is, for example, a preset value or a preset interval, etc., but is not limited thereto), and outputs pixel event information (for example, the position information of the pixel unit). Since the movement of an object will cause the light intensity of the corresponding area in the field of view perceived by the corresponding pixel unit to change, the moving object in the field of view can be detected. However, on the other hand, there are some light intensity changes in the field of view that cannot represent the motion information of the object, but can cause the light intensity of the pixel unit to change and cause the dynamic visual sensor to output data. In particular, when this type of light intensity change is a global light intensity change (for example, a vehicle entering / exiting a tunnel), the dynamic visual sensor will output full-frame useless data, which will occupy a high output bandwidth and interfere with subsequent image processing.

[0032] The applicant has found through research that when there are periodic changes in light intensity in the field of view, if the dynamic vision sensor can give the frequency of the light intensity change in some way, then the back-end processor can extract the events generated by effective object motion in a variety of ways to improve the signal-to-noise ratio of the event signal. For example, the back-end processing unit can extract the events generated by object motion during that period by subtracting the corresponding event frames based on the light intensity conversion frequency. Due to the periodicity of light intensity changes, it will generate irrelevant events at fixed times and positions. These redundant information can be easily removed by subtracting the previous and next event frames. In addition, for light intensity changes with very short change times, the back-end processing unit can also periodically reset the dynamic vision sensor for a short period of time based on the frequency of the light intensity change to shield the light intensity change.

[0033] In view of this, according to an embodiment of the present invention, a solution for detecting periodic light intensity changes in a field of view is provided. When periodic light intensity changes in the field of view are detected, frequency information of the light intensity changes can be provided to a back-end processing unit for processing.

[0034] Figure 1 A schematic diagram of an image sensor 100 according to some embodiments of the present invention is shown.

[0035] This image sensor 100 builds upon the existing structure of a dynamic vision sensor by adding an independent circuit component to detect periodic light intensity changes within the field of view. According to one implementation, the image sensor 100 is coupled to an external image acquisition system and transmits the output data to the external image acquisition system for further calculation and processing. This is not a limitation of the present invention.

[0036] like Figure 1 As shown, the image sensor 100 includes at least: a core circuit component 110 and a light intensity change detection module 120. Among them, the core circuit component 110 completes the core function of the image sensor 100: detecting light intensity changes and outputting pixel event information. In some embodiments, the core circuit component 110 mainly includes a plurality of main pixel units. When the light intensity change in the field of view reaches a predetermined condition, the main pixel units in the corresponding area will be triggered, and the core circuit component 110 outputs the address information of the triggered main pixel units. In some embodiments, the core circuit component 110 can also output the time information of the triggered main pixel units. The light intensity change detection module 120 is arranged around the core circuit component 110, and is used to complete the detection and judgment functions of periodic light intensity changes in the field of view. At the same time, the light intensity change detection module 120 will also calculate the frequency of light intensity changes when periodic light intensity changes are detected.

[0037] According to an embodiment of the present invention, the core circuit component 110 detects and outputs dynamic information in the field of view. Furthermore, the core circuit component 110 includes: a main pixel array 112, a readout unit 114 and a main pixel array control unit 116. Figure 1 The main pixel array 112 is composed of multiple identical pixel acquisition circuits (or called "main pixel units") in one dimension or two dimensions. Figure 1 A 3×3 main pixel array is shown in the figure, but is not limited to this. Each main pixel unit independently and in real time monitors the light intensity changes in the corresponding area in the field of view, and enters a trigger state when it senses that the light intensity change meets a predetermined condition (for example, the light intensity change exceeds a preset value). Optionally, the preset value of the light intensity change that the main pixel unit can determine can be adjusted according to different application scenarios by a filter (such as a high-pass filter) arranged in the main pixel unit to ensure that only light intensity changes that reach a certain preset value are considered "motion" and detected. When the main pixel unit enters the trigger state, it sends a request signal to the peripheral readout unit 114. When it is selected by the readout unit 114, the readout unit 114 encodes the address information of the main pixel unit (including the row address and the column address) and outputs it. The main pixel array control unit 116 is coupled to each main pixel unit through a global reset signal line and sends a global reset signal to the main pixel unit to control the state of each main pixel unit.

[0038] According to an embodiment of the present invention, the operating state of the core circuit component 110 depends on the global reset signal issued by the main pixel array control unit 116. During initialization, the main pixel array control unit 116 sends a global reset signal to each main pixel unit in the main pixel array 112 via the global reset signal line to shut down the main pixel unit so that it no longer responds to changes in light intensity in the field of view, thereby initializing the entire main pixel array 112. At the same time, while the global reset signal is valid, the readout unit 114 is also reset, and the core circuit component 110 enters a light intensity detection reset state, does not respond to changes in light intensity in the field of view, and does not output data. When the global reset signal is removed, the core circuit component 110 of the image sensor 100 enters a light intensity detection enabled state and begins normal operation.

[0039] According to an embodiment of the present invention, the light intensity change detection module 120 disposed outside the core circuit component 110 is mainly used to detect periodic light intensity changes in the field of view that are unrelated to object motion. According to an embodiment of the present invention, the light intensity changes are global.

[0040] Combine Figure 1 The light intensity change detection module 120 further includes a plurality of light intensity change detection pixel units 200 and a light intensity change detection control unit 400. Specifically, the light intensity change detection pixel units 200 are used to detect whether there is a global light intensity change phenomenon in the field of view. The light intensity change detection control unit 400 serves as the global light intensity change determinator of the dynamic vision sensor, managing the light intensity change detection pixel units 200 and, when it determines that a global light intensity change phenomenon has occurred, calculating the interval between light intensity changes to obtain the light intensity change frequency.

[0041] According to some embodiments of the present invention, the light intensity change detection pixel units 200 are distributed in the form of an array on the periphery of the main pixel array 112. In one embodiment, at least one row / column of light intensity change detection pixel units 200 are arranged in the four directions of up, down, left, and right of the main pixel array 112, that is, light intensity change detection pixel rows or light intensity change detection pixel columns. Moreover, the number of light intensity change detection pixel units 200 is determined by the number of rows and columns of the main pixel units in the main pixel array. More specifically, the number of light intensity change detection pixel units 200 in the light intensity change detection pixel rows is consistent with the number of columns of the main pixel array 112; the number of light intensity change detection pixel units 200 in the light intensity change detection pixel columns is consistent with the number of rows of the main pixel array 112. For example, Figure 1The number of rows and columns of the main pixel array is 3, so the number of light intensity change detection pixel units 200 is 3*4=12. That is, a row / column of light intensity change detection pixel units 200 is arranged in the four directions of the main pixel array 112, namely, the top, bottom, left, and right directions, and the number of light intensity change detection pixel units 200 in each row / column is 3. It should be noted that, for the sake of simplicity, Figure 1 Only the light intensity change detection pixel units 200 are shown as being distributed above and to the right of the main pixel array 112, and three light intensity change detection pixel units 200 form a light intensity change detection pixel row, and three light intensity change detection pixel units 200 form a light intensity change detection pixel column. It should be understood that Figure 1 For illustration only, only a portion of the light intensity change detection pixel unit 200 is shown.

[0042] The basic function of the light intensity change detection pixel unit 200 is essentially the same as that of the main pixel unit: both detect light intensity in a corresponding area within the field of view. The light intensity change detection pixel unit 200 responds to changes in light intensity within the corresponding area of ​​the field of view and, when the change meets a predetermined condition, enters a trigger state and generates a current pulse signal.

[0043] The light intensity change detection control unit 400 is connected to all light intensity change detection pixel units 200 via current pulse output signal lines. Thus, the light intensity change detection control unit 400 uses the received current pulse signals to determine whether there is a global light intensity change in the field of view. If a global light intensity change is confirmed, the control unit 400 then determines whether the global light intensity change is periodic. If the global light intensity change is periodic, the control unit 400 calculates and outputs the frequency information of the light intensity change to the back-end processing unit.

[0044] In summary, the image sensor 100 according to the present invention, without changing the existing dynamic vision sensor structure, can detect periodic light intensity variations in the field of view by adding a set of pixel units for detecting light intensity variations. When periodic light intensity variations occur in the field of view, the image sensor 100 outputs the frequency information of these variations to a back-end processing unit. This approach effectively reduces the interference of these periodic light intensity variations in the field of view on the output data of the dynamic vision sensor, improving motion detection performance.

[0045] At the same time, the light intensity change detection module 120 does not need to be coupled to the core circuit component 110. On the one hand, the core circuit component 110 and the light intensity change detection module 120 can independently complete their respective tasks without affecting each other, thereby improving the working efficiency of the image sensor; on the other hand, the light intensity change detection module 120 is easy to deploy, and only needs to determine the number of light intensity change detection pixel units based on the main pixel array in the core circuit component 110.

[0046] Regarding the specific structure of the core circuit component 110, reference may be made to the relevant content of the dynamic vision sensor, and no further restrictions will be made here.

[0047] The light intensity change detection module 120 in the image sensor 100 will be further explained below with reference to the accompanying drawings.

[0048] Figure 2 FIG. 2 shows a schematic diagram of a light intensity change detection pixel unit 200 in a light intensity change detection module 120 according to an embodiment of the present invention. Figure 2 As shown, the light intensity change detection pixel unit 200 includes a photodetection subunit 210 , a trigger generation subunit 220 , a logic subunit 230 and a current pulse generation subunit 240 .

[0049] The structure and function of the photodetection subunit 210 and the trigger generation subunit 220 are completely consistent with those of the main pixel unit. Specifically, the photodetection subunit 210 monitors the light signal irradiated thereon in real time and outputs the corresponding electrical signal. Figure 2 The photodetection subunit 210 shown is a logarithmic photodetector comprising a photodiode PD1 with a grounded anode, a first transistor T1, and a first amplifier A1. The source of the first transistor T1 is connected to the cathode of the photodiode PD1, and its drain is connected to a power supply VDD. The first amplifier A1 is connected between the cathode of the photodiode PD1 and the gate of the first transistor T1. A1 can improve the response speed of voltage changes generated between the source and gate of T1.

[0050] The first input terminal of the trigger generation subunit 220 is coupled to the photodetection subunit 210, and the first output terminal thereof is coupled to the logic subunit 230. When the electrical signal meets a predetermined condition, the trigger generation subunit 220 generates a trigger generation signal to the logic subunit 230. According to one embodiment, the trigger generation subunit 220 further includes a pre-processing module 221 and a threshold comparison module 222. Figure 2The preprocessing module 221 in the trigger generation subunit 220 includes an amplifier A2. The threshold comparison module 222 in the trigger generation subunit 220 includes a first voltage comparator VC1, a second voltage comparator VC2, and an OR logic unit. The inverting input of the first voltage comparator VC1 is connected to a fixed voltage level, which serves as the first threshold of the threshold comparison module 222. Its non-inverting input is connected to the output of the preprocessing module 221. The non-inverting input of the second voltage comparator VC2 is connected to a fixed voltage level, which serves as the second threshold of the threshold comparison module 222. Its inverting input is connected to the output of the preprocessing module 221. The OR logic unit performs an OR logic operation on the outputs of the two voltage comparators. When the output signal of the preprocessing module 221 is greater than the first threshold or less than the second threshold (i.e., the light intensity change meets a predetermined condition), the OR logic unit outputs a valid trigger generation signal to the back-end logic subunit 230.

[0051] The input end of the logic subunit 230 is coupled to the trigger generation subunit 220, and the output end is coupled to the current pulse generation subunit 240. Upon receiving the trigger generation signal, the logic subunit 230 outputs a signal to the current pulse generation subunit 240. In one embodiment, upon receiving the trigger generation signal, the logic subunit 230 outputs a high level to the current pulse generation subunit 240; otherwise, the logic subunit 230 outputs a low level to the current pulse generation subunit 240. After receiving the output signal from the logic subunit 230, the current pulse generation subunit 240 generates and outputs a current pulse signal.

[0052] According to some embodiments of the present invention, logic subunit 230 includes a latch and a delay circuit. Upon receiving a trigger generation signal, the latch is set and, after a delay in the delay circuit, returns to a reset state. Simultaneously, the latch's output signal serves as a reset signal for trigger generation subunit 220, resetting the trigger generation subunit during the latch's set period and preparing for the next light intensity change detection. In some embodiments, the latch's output signal serves as a reset signal for the amplifier in preprocessing module 221, thereby resetting trigger generation subunit 220.

[0053] The current pulse generation subunit 240 receives the output signal of the logic subunit 230, converts it into a current pulse signal, and sends it to the current pulse output signal line. Specifically, when the light intensity change detection pixel unit 200 detects a change in light intensity and sets the latch, the current pulse generation subunit 240 generates a fixed current to the current pulse output signal line. Conversely, when no light intensity change is detected, no current flows on the current pulse output signal line.

[0054] Figure 3 FIG. 2 shows a schematic diagram of the current pulse generating subunit 240 according to some embodiments of the present invention.

[0055] The current pulse generating subunit 240 includes a transistor M1 and a current source I1. Figure 3 The gate of the transistor M1 is connected to the output of the logic sub-unit 230, the source is connected to the current source I1, and the drain is coupled to the light intensity change detection control unit 400 through the current pulse output signal line. It should be noted that the current pulse output signal line is coupled to all the light intensity change detection pixel units 200 in the light intensity change detection module 120 to automatically realize the current summation function. When the light intensity change detection pixel unit 200 is not triggered, the logic sub-unit 230 outputs a low level, the transistor M1 is turned off, and the current of the current source I1 does not flow through the current pulse output signal line; when the light intensity change detection pixel unit 200 is triggered, the logic sub-unit 230 outputs a high level, the transistor M1 is turned on, and the current of the current source I1 flows through the current pulse output signal line.

[0056] It should be noted that each sub-unit in the light intensity change detection pixel unit 200 has multiple implementation methods, and the embodiments of the present invention are not limited thereto.

[0057] Figure 4 FIG2 shows a schematic diagram of a light intensity change detection control unit 400 according to some embodiments of the present invention. The light intensity change detection control unit 400 resets all light intensity change detection pixel units 200 at the initial power-on moment, and then monitors the current magnitude on the current pulse output signal line in real time. In some embodiments, at the initial power-on moment, the light intensity change detection control unit 400 resets the trigger generation subunit 220 and the logic subunit 230 (such as the light intensity change detection pixel unit 200) in the light intensity change detection pixel unit 200 through the initial reset signal line. Figure 2 ).

[0058] like Figure 4 The light intensity change detection control unit 400 mainly includes: a light intensity change judgment subunit 410 and a pulse frequency judgment subunit 420.

[0059] The light intensity change determination subunit 410 receives current pulse signals from all light intensity change detection pixel units 200 via the current pulse output signal line. As previously described, the current pulse output signal line is coupled to all light intensity change detection pixel units 200 and can automatically implement the current summation function. Therefore, the light intensity change determination subunit 410 obtains the total pulse current at the current moment, that is, the total instantaneous current, through the current pulse output signal line. The magnitude of this total instantaneous current represents the number of light intensity change detection pixel units 200 triggered in the light intensity change detection module 120 at the current moment, that is, the global light intensity change in the field of view. When the total pulse current is greater than the threshold, it outputs a pulse signal to the pulse frequency determination subunit 420.

[0060] Figure 5A and Figure 5B Schematic diagrams of light intensity change judgment subunits according to some embodiments of the present invention are respectively shown.

[0061] like Figure 5A As shown, the light intensity change judgment subunit 410 includes a current comparator and a reference current source. The non-inverting input terminal of the current comparator is connected to the current pulse output signal line, the inverting input terminal is connected to the reference current source, and the output terminal of the current comparator is connected to the pulse frequency judgment subunit 420. In this way, the current comparator judges the size of the total pulse current from the current pulse output signal line and the reference current source, and outputs a pulse signal to the pulse frequency judgment subunit 420 when the total pulse current exceeds the reference current source. The reference current source indicates a threshold value. The threshold value is determined based on at least the number of light intensity change detection pixel units 200. Generally speaking, when other conditions remain unchanged, the greater the number of light intensity change detection pixel units 200 in the light intensity change detection module 120, the greater the threshold value.

[0062] like Figure 5B The light intensity change judgment subunit 410 includes a current analog-to-digital converter (ADC) and a digital comparator. The current ADC quantizes the input total current pulse into a digital signal. The digital comparator at the back end determines whether the output of the current ADC exceeds the threshold. After confirming that the output of the current ADC exceeds the threshold, it outputs a pulse signal to the pulse frequency judgment subunit 420. For more information on the selection of the threshold, please refer to Figure 5A Related description.

[0063] Pulse frequency determination subunit 420 determines whether the pulse signal output by light intensity change determination subunit 410 is a periodic signal. According to one embodiment, pulse frequency determination subunit 420 calculates the time difference between adjacent pulses and determines that the received pulse signal is a periodic signal when the time differences between adjacent pulses are the same.

[0064] When it is confirmed that the pulse signal is a periodic signal, the pulse frequency judgment subunit 420 confirms that the corresponding light intensity change is a periodic light intensity change. At this time, the pulse frequency judgment subunit 420 calculates the frequency of the light intensity change based on the time difference between adjacent pulses. Specifically, the time difference between adjacent pulses is the light intensity change period, and the frequency of the light intensity change can also be obtained by conversion. According to some embodiments, the pulse frequency judgment subunit 420 outputs the frequency of the light intensity change to the back-end processing unit as a detection output of the periodic light intensity. The pulse frequency judgment subunit 420 can adopt a general period detection method, such as a counter-based detection method, which will not be repeated here.

[0065] According to the present invention, without changing the existing dynamic vision sensor structure, the detection of periodic light intensity changes in the field of view can be achieved by adding an independent light intensity change detection module. Furthermore, the light intensity change detection module does not need to be coupled to the core circuit assembly. On the one hand, the core circuit assembly and the light intensity change detection module can perform their respective functions independently without affecting each other, improving the operating efficiency of the image sensor. On the other hand, the light intensity change detection module is easy to deploy, and the number of light intensity change detection pixel units only needs to be determined based on the main pixel array of the core circuit assembly.

[0066] At the same time, the light intensity change detection module also outputs the frequency information of these light intensity changes to the back-end processing unit when it detects periodic light intensity changes in the field of view. According to the solution of the present invention, it can effectively reduce the interference of such periodic light intensity changes in the field of view on the output data of the dynamic vision sensor, thereby improving the performance of motion detection.

[0067] Accordingly, the present invention also provides a method for detecting periodic light intensity changes using the above-mentioned image sensor 100 or light intensity change detection module 120. Figure 6 FIG. 6 is a flow chart of a method 600 for detecting periodic light intensity changes according to some embodiments of the present invention. According to some implementations of the present invention, the method 600 is executed in the light intensity change detection module 120 .

[0068] like Figure 6 As shown, the method 600 starts at 610. In 610, the light intensity change detection pixel unit 200 generates a current pulse signal by monitoring the light intensity change in the field of view, wherein the current pulse signal is generated when the light intensity change meets a predetermined condition.

[0069] In step 620, the light intensity change detection control unit 400 determines whether to generate a pulse signal by determining the magnitude of the current pulse signal. According to some embodiments, when the total instantaneous current of the received current pulse signal is greater than a threshold, a global light intensity change is considered to have occurred, and a pulse signal is generated.

[0070] In 630 , the steps of monitoring the light intensity change (ie 610 ) and determining the magnitude of the current pulse signal (ie 620 ) are repeated and iterated to generate multiple pulse signals.

[0071] In step 640, the time difference between the multiple pulse signals is calculated to determine whether the light intensity variation is a periodic light intensity variation. According to some embodiments, when the time differences between adjacent pulses are the same, the light intensity variation is determined to be a periodic light intensity variation.

[0072] Furthermore, according to some further embodiments of the present invention, when it is determined that the light intensity variation is a periodic light intensity variation, frequency information of the light intensity variation is output.

[0073] It should be understood that the method 600 and the aforementioned image sensor 100 and light intensity change detection module 120 are mutually illustrative, and the repeated parts will be omitted.

[0074] The various techniques described herein may be implemented in conjunction with hardware or software, or a combination thereof. Thus, the methods and apparatus of the present disclosure, or certain aspects or portions of the methods and apparatus of the present disclosure, may take the form of program code (i.e., instructions) embedded in a tangible medium, such as a removable hard disk, a USB flash drive, a floppy disk, a CD-ROM, or any other machine-readable storage medium, wherein when the program is loaded into a machine such as a computer and executed by the machine, the machine becomes an apparatus for practicing the present disclosure.

[0075] When the program code is executed on a programmable computer, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device. The memory is configured to store the program code, and the processor is configured to execute the method for detecting periodic light intensity changes of the present disclosure according to the instructions in the program code stored in the memory.

[0076] By way of example and not limitation, readable media include readable storage media and communication media. Readable storage media store information such as computer-readable instructions, data structures, program modules, or other data. Communication media typically embody computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and include any information delivery medium. Combinations of any of the above are also included within the scope of readable media.

[0077] In the description provided herein, the algorithms and displays are not inherently related to any particular computer, virtual system, or other device. Various general-purpose systems can also be used in conjunction with the examples of the present disclosure. Based on the above description, it is apparent that the structure required for constructing such systems is suitable. In addition, the present disclosure is not directed to any specific programming language. It should be understood that various programming languages ​​can be utilized to implement the content of the present disclosure described herein, and the above description of specific languages ​​is intended to disclose preferred embodiments of the present disclosure.

[0078] In the description provided herein, numerous specific details are described. However, it is understood that embodiments of the present disclosure may be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0079] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present disclosure, various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed approach should not be interpreted as reflecting an intention that the claimed disclosure requires more features than those expressly recited in each claim. Rather, as reflected in the claims below, the disclosed aspects consist of fewer than all the features of the individual embodiments disclosed above. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the present disclosure.

[0080] Those skilled in the art will appreciate that the modules, units, or components of the devices in the examples disclosed herein may be arranged in the device described in the embodiment, or alternatively may be located in one or more devices different from the devices in the examples. The modules in the foregoing examples may be combined into one module or further divided into multiple submodules.

[0081] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and in addition may be divided into multiple submodules or subunits or subcomponents. All features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed herein may be combined in any combination, except that at least some of such features and / or processes or units are mutually exclusive. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0082] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of this disclosure and to form different embodiments. For example, in the claims below, any of the claimed embodiments may be used in any combination.

[0083] In addition, some of the embodiments are described herein as methods or combinations of method elements that can be implemented by a processor of a computer system or by other devices that perform the functions described. Thus, a processor having the necessary instructions for implementing the method or method element forms a device for implementing the method or method element. In addition, the elements described herein of the device embodiments are examples of devices for implementing the functions performed by the elements for the purpose of implementing the disclosed subject matter.

[0084] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved and are not intended to imply that the objects so described must have a given order in time, space, ranking, or in any other manner.

[0085] Although the present disclosure has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having the benefit of the foregoing description, that other embodiments are contemplated within the scope of the disclosure thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, and not for the purpose of explaining or limiting the subject matter of the disclosure. Accordingly, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. With respect to the scope of the disclosure, what has been disclosed is illustrative and not restrictive, and the scope of the disclosure is defined by the appended claims.

Claims

1. A light intensity change detection module, independently arranged on the periphery of the core circuit component of the image sensor, comprising: a plurality of light intensity change detection pixel units, each of which is adapted to respond to a light intensity change in a field of view and enter a trigger state and output a current pulse signal when the light intensity change satisfies a predetermined condition; a light intensity change detection control unit, coupled to each light intensity change detection pixel unit, adapted to determine whether a total pulse current is greater than a threshold value based on current pulse signals from each light intensity change detection pixel unit, and to generate a pulse signal when the total pulse current is greater than the threshold value; The light intensity change detection pixel unit is further adapted to be set after entering a trigger state to re-respond to light intensity changes in the field of view and continuously output a current pulse signal to the light intensity change detection control unit; and The light intensity change detection control unit is further adapted to determine whether the light intensity change is a periodic light intensity change based on the pulse signal, and generate and output frequency information of the light intensity change when the light intensity change is a periodic light intensity change; Wherein, the light intensity change detection pixel unit includes: a photoelectric detection subunit, which is suitable for monitoring the light signal irradiated thereon in real time and outputting a corresponding electrical signal; a trigger generation subunit, whose first input end is coupled to the photoelectric detection subunit, and whose first output end is coupled to the logic subunit, and the trigger generation subunit is suitable for generating a trigger generation signal to the logic subunit when the electrical signal meets a predetermined condition; a logic subunit, whose input end is coupled to the trigger generation subunit, and whose output end is coupled to the current pulse generation subunit, and the logic subunit is suitable for outputting a signal to the current pulse generation subunit when receiving the trigger generation signal; the current pulse generation subunit is suitable for generating and outputting a current pulse signal when receiving the output signal of the logic subunit; The light intensity change detection control unit includes: a pulse frequency judgment subunit, which is suitable for calculating the time difference between adjacent pulses, and when the time difference between adjacent pulse signals is the same, determining that the pulse signal is a periodic signal; if the pulse signal is a periodic signal, the light intensity change is a periodic light intensity change.

2. The light intensity change detection module according to claim 1, wherein: The light intensity change detection control unit also includes: The light intensity change judgment subunit is adapted to receive the current pulse signals from all the light intensity change detection units via the current pulse output signal line, and generate a pulse signal when the total pulse current is greater than a threshold value.

3. The light intensity change detection module according to claim 2, wherein: The pulse frequency determination subunit is further adapted to calculate frequency information of the light intensity change according to the time difference when determining that the light intensity change is a periodic light intensity change.

4. The light intensity change detection module according to any one of claims 1 to 3, wherein: The logic subunit includes a latch and a delay circuit, When the trigger generation signal is received, the latch is set, and after the delay of the delay circuit, the latch is restored to the reset state; and the output signal of the latch is the reset signal of the trigger generation sub-unit, so as to reset the trigger generation sub-unit during the period when the latch is set.

5. The light intensity change detection module according to any one of claims 1 to 3, wherein: The current pulse generating subunit comprises: Current source; A transistor, a gate of which is connected to the output of the logic subunit, a source of which is connected to the current source, and a drain of which is coupled to the light intensity change detection control unit via a current pulse output signal line.

6. The light intensity change detection module according to claim 2 or 3, wherein: The light intensity change judgment subunit includes: Reference current source; A current comparator, whose non-inverting input terminal is connected to the current pulse output signal line, whose inverting input terminal is connected to the reference current source, and whose output terminal is connected to the pulse frequency judgment sub-unit, is suitable for outputting a pulse signal to the pulse frequency judgment sub-unit when it is judged that the total pulse current from the current pulse output signal line exceeds the reference current source.

7. The light intensity change detection module according to claim 2 or 3, wherein: The light intensity change judgment subunit includes: a current analog-to-digital converter, whose input terminal is connected to the current pulse output signal line and whose output terminal is connected to the digital comparator, adapted to quantize the total current pulse into a digital signal and output the digital signal to the digital comparator; A digital comparator, whose input end is connected to the current analog-to-digital converter and whose output end is connected to the pulse frequency judgment subunit, is suitable for outputting a pulse signal to the pulse frequency judgment subunit after confirming that the output of the current analog-to-digital converter exceeds a threshold.

8. The light intensity change detection module according to any one of claims 1 to 3, wherein: The threshold is determined based on at least the number of the light intensity change detection pixel units.

9. The light intensity change detection module according to any one of claims 1 to 3, wherein: The multiple light intensity change detection pixel units are arranged around the main pixel array, and the main pixel array is suitable for triggering the corresponding main pixel unit when the light intensity change in the field of view reaches a predetermined condition, and at least outputting the address information of the triggered main pixel unit; and the number of the light intensity change detection pixel units is determined based on the main pixel array.

10. A method for detecting periodic light intensity changes, the method being suitable for being performed in the light intensity change detection module according to any one of claims 1 to 9, comprising: generating a current pulse signal by monitoring a change in light intensity in a field of view, wherein the current pulse signal is generated when the change in light intensity satisfies a predetermined condition; Determine whether to generate a pulse signal by judging the size of the current pulse signal; Repeating the steps of monitoring the change in light intensity and determining the size of the current pulse signal to generate multiple pulse signals; as well as By calculating the time difference between the multiple pulse signals, it is determined whether the light intensity change is a periodic light intensity change.

11. The method of claim 10, further comprising: When it is determined that the light intensity variation is a periodic light intensity variation, frequency information of the light intensity variation is output.

12. The method according to claim 10 or 11, wherein: Whether to generate a pulse signal is determined by judging the size of the current pulse signal, including: When the total instantaneous current of the received current pulse signal is greater than a threshold value, it is confirmed that the pulse signal is generated.

13. An image sensor comprising: A core circuit component adapted to trigger a corresponding primary pixel unit when a change in light intensity in a field of view satisfies a predetermined condition, and to output at least address information of the triggered primary pixel unit; The light intensity change detection module according to any one of claims 1 to 9 is arranged around the main pixel array and is suitable for detecting periodic light intensity changes based on light intensity changes in the field of view.

14. The image sensor according to claim 13, wherein: The core circuit assembly includes a main pixel array, and the main pixel array includes a plurality of main pixel units; The number of light intensity change detection pixel units in the light intensity change detection module is determined by the number of rows and columns of the main pixel array.

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