CN114827467A - Event type image sensor and control method - Google Patents

Abstract

The invention relates to an event type image sensor and a control method thereof, which are applied to an event camera and comprise the following steps: acquiring a real-time voltage in response to an incident optical signal; taking the difference voltage of the real-time voltage and a preset reference voltage as an input voltage, performing frequency separation on the input voltage and a noise voltage, and filtering the noise voltage according to the separated frequency to obtain an output voltage; comparing the output voltage with a preset voltage range; and outputting an event signal according to the comparison result. According to the embodiment of the invention, the input voltage and the noise voltage are subjected to frequency separation, and then the noise voltage is filtered according to the separated frequency to obtain the output voltage without the noise voltage; because the output voltage is the voltage after the noise voltage is removed, when the event signal is output according to the comparison result, the output event signal is more accurate.

Description

Event-type image sensor and control method

technical field

The invention belongs to the technical field of computer vision, and in particular relates to an event-type image sensor and a control method.

Background technique

Traditional cameras, whether CMOS sensors, CCD sensors, or RGBD cameras, capture images at a constant frequency. In this way, even if the frame rate can reach 1KHz, that also has a delay of 1ms. Therefore, traditional cameras have a certain delay problem. With the development of the times, an event camera (Event-based Vision, EVS) has emerged. The event camera is a dynamic vision sensor that senses changes in incident light and generates events based on changes in light, outputs event signals, and has The advantages of fast frame rate and low power.

However, in the existing event camera, due to the process deviation in the production process of the integrated circuit, there are some factors such as noise and offset among the sub-circuits, which may cause the event signal output error.

SUMMARY OF THE INVENTION

The present invention provides an event-type image sensor and a control method, which are used to solve the technical problem of inaccurate output of event signals in the prior art.

In one aspect, the present invention provides an event-type image sensor, which is applied to an event camera. The event-type image sensor includes: an input unit, a chopper unit, a comparison unit, and a readout unit, the input unit, the chopper unit, The comparison unit and the readout unit are connected in sequence; wherein,

the input unit is used for acquiring real-time voltage in response to the incident light signal;

The chopper unit is configured to use the difference voltage between the real-time voltage and the preset reference voltage as the input voltage, separate the input voltage from the noise voltage in frequency, and then filter the noise voltage according to the separated frequency. , get the output voltage;

the comparison unit is used for comparing the output voltage with a preset voltage range;

The readout unit is used for outputting an event signal according to the comparison result.

In a second aspect, the present invention provides an event-based image sensor control method applied to an event camera, the method comprising:

obtaining a real-time voltage in response to an incident light signal;

The difference voltage between the real-time voltage and the preset reference voltage is used as the input voltage, the frequency of the input voltage and the noise voltage is separated, and then the noise voltage is filtered according to the separated frequency to obtain an output voltage;

comparing the output voltage to a preset voltage range;

An event signal is output according to the comparison result.

It can be seen from the above-mentioned embodiments of the present invention that in the embodiments of the present invention, the frequency of the input voltage and the noise voltage is separated, and then the noise voltage is filtered according to the separated frequency to obtain an output voltage that removes the noise voltage; since the output voltage is the noise-removed voltage After the voltage, when the event signal is output according to the comparison result, the output event signal is more accurate.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is a schematic flowchart of a method for controlling an event-type image sensor in an embodiment of the present application;

FIG. 2 is a circuit structure diagram of an event-type image sensor in an embodiment of the present application;

3 is a circuit structure diagram of a chopper unit in an embodiment of the application;

4 is a schematic diagram of the relationship between signal frequency/chopping frequency, input voltage and noise voltage in an embodiment of the application;

5 is a schematic diagram of the relationship between signal frequency/chopping frequency and intermediate voltage signal in an embodiment of the application;

6 is a schematic diagram of the relationship between signal frequency/chopping frequency, demodulation voltage and noise voltage in an embodiment of the present application;

7 is a schematic diagram of the relationship between signal frequency/chopping frequency, output voltage and noise voltage in an embodiment of the application;

8 is a schematic diagram of the relationship between input voltage and time in an embodiment of the application;

FIG. 9 is a schematic diagram of the relationship between modulation voltage and time in an embodiment of the present application;

10 is a schematic diagram of the relationship between demodulation voltage and time in an embodiment of the application;

FIG. 11 is a schematic diagram of the relationship between output voltage and time in an embodiment of the present application.

Detailed ways

In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described above are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the embodiments of the present invention, it should be understood that the terms "first" and "second" are only used for description purposes, and should not be interpreted as indicating or implying relative importance or implicitly indicating the indicated technical features. quantity. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the embodiments of the present invention, unless otherwise expressly specified and limited, terms such as “installation”, “connection”, “connection”, and “fixation” should be understood in a broad sense. For example, it may be a fixed connection or a It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of the two elements or the interaction relationship between the two elements. Those of ordinary skill in the art can understand the specific meanings of the above terms in the embodiments of the present invention according to specific situations.

Referring to FIG. 1 , an event-based image sensor control method according to an embodiment of the present invention, applied to an event camera, is shown, and the method includes:

Step S100, acquiring a real-time voltage in response to the incident light signal.

In an exemplary embodiment, the step S100 specifically includes:

generating a photocurrent in response to the incident light signal; converting the photocurrent to a real-time voltage.

In this embodiment, the event camera is an event-type image sensor, and the event-type image sensor includes a pixel array composed of a plurality of pixels, each pixel in the pixel array includes a corresponding pixel sensor, and the pixel sensor can collect incident light signals. The incident light signal is collected by the pixels in the image sensor, and each pixel is collected accordingly. The collected incident light signal is photoelectrically converted by the photoelectric conversion element to obtain the corresponding current value, and the current value is processed by the current-voltage conversion element. The current-voltage conversion can obtain the corresponding real-time voltage, and convert the optical signal into a voltage signal to facilitate data calculation. The photoelectric conversion element can be a photodiode, a phototransistor, a clamp photodiode, or any other similar components that perform photoelectric conversion. The realization circuit of the current-to-voltage element is relatively common, and can be realized by the voltage divider method, the Hall sensor method, the integrating circuit method, etc., which will not be repeated here.

Step S120: Use the difference voltage between the real-time voltage and the preset reference voltage as the input voltage, separate the input voltage from the corresponding noise voltage in frequency, and filter the noise voltage according to the separated frequency to obtain an output Voltage.

In this embodiment, the first chopper modulates the input voltage according to the preset modulation signal, and does not modulate the noise voltage, and then amplifies the modulated input voltage together with the noise voltage to obtain an intermediate voltage signal. The corresponding demodulation signal demodulates the modulation voltage in the intermediate voltage signal, so that the modulation voltage in the intermediate voltage signal and the noise voltage are separated in frequency, the noise voltage is a high-frequency signal, and the demodulated modulation voltage is a low-frequency signal; The separated frequencies low-pass filter the noise voltage to obtain the output voltage.

In this embodiment, the step S120 specifically includes:

The difference voltage between the real-time voltage and the preset reference voltage is used as the input voltage, and after the input voltage is modulated, frequency amplification is performed simultaneously with the noise voltage to obtain an intermediate voltage signal; the modulation in the intermediate voltage signal is After the voltage demodulation, low-pass filtering is performed, and the output voltage is obtained after filtering the noise voltage.

In this embodiment, as a preferred implementation manner, the step S120 specifically includes:

The difference voltage between the real-time voltage and the preset reference voltage is used as an input voltage for modulation; the modulated input voltage and the noise voltage are simultaneously amplified in frequency to obtain an intermediate voltage signal; Modulation voltage demodulation; low-pass filtering is performed on the demodulated intermediate voltage signal, and an output voltage is obtained after filtering the noise voltage.

In this embodiment, the input voltage is accompanied by a noise voltage, and the first chopper can modulate the input voltage according to the preset modulation signal, and output the modulated input voltage. Then, the modulated input voltage and the noise voltage are simultaneously amplified in frequency by the amplifier to obtain an intermediate voltage signal. At this time, the noise voltage is amplified into a high-frequency voltage. Then, the modulation voltage in the intermediate voltage signal is demodulated by the second chopper, that is, the modulation voltage is demodulated into a low frequency signal. Finally, after passing through the low-pass filter, low-pass filtering is performed on the demodulated modulation voltage together with the noise voltage, and the noise voltage is filtered out to obtain the output voltage.

Step S140, compare the output voltage with a preset voltage range.

In this embodiment, a more accurate event signal is output by comparing the voltage value of the output voltage from which the noise voltage is removed with a preset voltage range.

Step S160, output an event signal according to the comparison result.

In this embodiment, the output voltage is compared with a preset voltage range. When the output voltage is greater than the preset voltage range, an UP event occurs in the incident light signal collected by the pixel, that is, the intensity of the incident light collected by the pixel becomes stronger, resulting in an UP event. Event signal; when the output voltage is less than the preset voltage range, a DN event occurs in the incident light signal collected by the pixel, that is, the intensity of the incident light collected by the pixel becomes weaker, and a DN event signal is generated. Assuming that the preset voltage range is (-0.1V, 0.1V), when the output voltage is 0.2V, the comparison result is (1, 0), indicating that 0.2V is greater than 0.1V, the UP event signal is output; when the output voltage is - When the output voltage is 0.2V, the comparison result is (0, 1), indicating that -0.2V is less than -0.1V, and the DN event signal is output; when the output voltage is 0.05V, the comparison result is (0, 0), indicating that no event is generated, Do not output event signal, continue to collect real-time voltage. Of course, in practical applications, it is not ruled out that the system may have errors and output (1, 1). This event signal is usually a noise signal. In this embodiment, the noise voltage is removed to reduce the system error rate. Since the output voltage eliminates the offset voltage, when the output voltage is compared with the preset voltage range, the comparison result is more accurate, which improves the accuracy of the output event signal.

In this embodiment, the event-based image sensor control method further includes updating the preset reference voltage stored in the capacitor. If the real-time voltage collected at the current moment and the preset reference voltage are processed according to steps S120 to S160, an event is output signal, the real-time voltage at the current moment is stored in the capacitor as an updated preset reference voltage. If the real-time voltage collected in the preset collection time period does not output an event signal after processing according to steps S120 to S160, the switch is closed and then opened to reset the preset reference voltage in the capacitor; and then according to the updated Steps S100 to S160 are re-executed to output the event signal for the preset reference voltage.

In this embodiment, after the demodulated modulation voltage is filtered by a low-pass filter, the noise voltage is filtered out, and the high-frequency noise is effectively removed. The input voltage is frequency separated from the noise voltage after modulation and demodulation by the first chopper and the second chopper. During amplification, the noise voltage is amplified into a high-frequency signal, which is filtered out after low-pass filtering. The offset voltage is modulated and demodulated. It is also eliminated during the adjustment process.

In this embodiment, the input voltage is the difference voltage between the real-time voltage and the preset reference voltage. The input voltage is accompanied by noise voltage during the transmission process. When the input voltage is modulated, the noise voltage is not modulated. The noise voltage and modulation The modulated input voltage and the noise voltage are amplified into a high-frequency signal to obtain an intermediate voltage signal. The intermediate voltage signal undergoes demodulation processing. Since the noise voltage is not modulated, only the modulation voltage in the intermediate voltage signal is demodulated. Finally, the demodulated modulation signal and the amplified noise voltage are subjected to low-pass filtering to obtain the output. Since the noise voltage at this time is a high-frequency signal, it can be filtered out by a low-pass filter, so that the offset voltage and high-frequency noise can be filtered out.

It can be seen from the above-mentioned embodiments of the present invention that in the embodiments of the present invention, the frequency of the input voltage is modulated to separate the input voltage from the frequency of the noise voltage, so as to facilitate the removal of the offset voltage; and then the modulated input voltage and the noise voltage are amplified. Then, the noise voltage is converted into a high-frequency signal, which can be filtered out by filtering; then the intermediate voltage signal is demodulated, and the modulation voltage in the intermediate voltage signal is demodulated into a low-frequency signal, and the noise amplified into a high-frequency signal The voltage is separated in frequency, and finally the noise voltage amplified into a high-frequency signal is filtered out by a filter; since the output voltage is the voltage after removing the noise voltage, when the event signal is output according to the comparison result, the output event signal is more accurate.

Please refer to FIG. 2 again, which shows an event-type image sensor 20 according to an embodiment of the present invention, which is applied to an event camera. The event-type image sensor 20 includes an input unit 21 , a chopper unit 22 , a comparison unit 24 and a readout unit 21 . The output unit 25, the input unit 21, the chopper unit 22, the comparison unit 24 and the readout unit 25 are connected in sequence. The specific description is as follows:

The input unit 21 is used to acquire real-time voltage in response to the incident light signal.

In an exemplary embodiment, the input unit 21 includes a conversion element 210 , a switch 211 and a capacitor 212 , and the switch 211 is connected to the first output terminal of the conversion element 210 and the first input of the differential unit 23 between the terminals, the connection terminal of the switch 211 and the first input terminal of the differential unit 23 is connected to the non-ground terminal of the capacitor 212 , the second output terminal of the conversion element 210 is connected to the second output terminal of the differential unit 23 input connection;

The conversion element 210 is used to convert the incident light signal into a real-time voltage;

The capacitor 212 is used to update the preset reference voltage when the switch 211 is switched from a closed state to an open state.

In an exemplary embodiment, the conversion element 210 includes a photoelectric conversion element and a current-voltage conversion element, an output terminal of the photoelectric conversion element is connected to an input terminal of the current-voltage conversion element, and an output terminal of the current-voltage conversion element is connected to the input terminal of the current-voltage conversion element. The first output terminal is connected to the switch 211 , and the second output terminal of the current-voltage conversion element is connected to the second input terminal of the differential unit 23 ;

the photoelectric conversion element is used to generate a photocurrent in response to the incident light signal;

The current-to-voltage conversion element is used to convert the photocurrent into the real-time voltage.

The chopper unit 22 is configured to use the difference voltage between the real-time voltage and the preset reference voltage as the input voltage, separate the input voltage from the corresponding noise voltage in frequency, and divide the noise voltage according to the separated frequency. After filtering, the output voltage is obtained.

In an exemplary embodiment, the chopper unit 22 includes a first chopper unit and a second chopper unit, and the first chopper unit is connected between the input unit 21 and the second chopper unit between;

The first chopper unit is configured to use the difference voltage between the real-time voltage and the preset reference voltage as the input voltage, and after modulating the input voltage, perform frequency amplification simultaneously with the noise voltage to obtain the intermediate voltage Signal;

The second chopper unit is used for demodulating the modulation voltage in the intermediate voltage signal and performing low-pass filtering, and filtering the noise voltage to obtain an output voltage.

In an exemplary embodiment, referring to FIG. 3 , the first chopper unit includes a first chopper 221 and an amplifier 222 , an input end of the first chopper 221 and an output end of the input unit 21 connection, the output end of the first chopper 221 is connected to the input end of the amplifier 222, and the output end of the amplifier 222 is connected to the input end of the second chopper unit;

The first chopper 221 is used to modulate the difference voltage between the real-time voltage and the preset reference voltage as an input voltage;

The amplifier 222 is used for frequency amplifying the modulated input voltage and the noise voltage at the same time to obtain an intermediate voltage signal.

In an exemplary embodiment, the second chopper unit includes a second chopper 223 and a low-pass filter 224, and the input end of the second chopper 223 is connected to the output end of the amplifier 222, so The output end of the second chopper 223 is connected to the input end of the low-pass filter 224, and the output end of the low-pass filter 224 is connected to the comparison unit 24;

the second chopper 223 is used for demodulating the modulation voltage in the intermediate voltage signal;

The low-pass filter 2231 is used for low-pass filtering the demodulated intermediate voltage signal, and filtering the noise voltage to obtain an output voltage.

The comparison unit 24 is used for comparing the output voltage with a preset voltage range.

In this embodiment, the comparison unit 24 may be a processor or a controller, and the processor compares the output voltage with a preset voltage range.

The readout unit 25 is used for outputting an event signal according to the comparison result.

In this embodiment, when the output voltage is greater than the preset voltage range, an UP event occurs in the incident light signal collected by the pixel, that is, the intensity of the incident light collected by the pixel becomes stronger, and an UP event signal is generated; when the output voltage is less than the preset voltage When the range is in the range, a DN event occurs in the incident light signal collected by the pixel, that is, the intensity of the incident light collected by the pixel becomes weaker, and a DN event signal is generated. Since the output voltage eliminates the noise voltage, when the output voltage is compared with the preset voltage range, the comparison result is more accurate, which improves the accuracy of the output event signal.

In an exemplary embodiment, the event-type image sensor further includes: a controller, which may also be a processor in the comparison unit. The controller sends control signals to the input unit 21 , the chopper unit 22 , the comparison unit 24 and the readout unit 25 , so that the input unit 21 , the chopper unit 22 , the comparison unit 24 and the readout unit 25 respectively perform corresponding operations according to the control signals. operate.

In this embodiment, the input voltage is accompanied by a low-frequency noise voltage during the transmission process, and the input voltage is input to the first chopper for modulation, the noise voltage is not modulated, and the noise voltage and the modulated input voltage are input to the amplifier together , the noise voltage and the modulated input voltage are amplified into a high-frequency signal, that is, an intermediate voltage signal. The intermediate voltage signal is demodulated by the second chopper, and the modulation voltage of the intermediate voltage signal is demodulated, and the amplified noise voltage does not need to be demodulated, and the modulation voltage is demodulated into a low-frequency signal, so that the modulation voltage is demodulated. The frequency is separated from the frequency of the amplified noise voltage; finally, the output voltage is obtained through low-pass filtering. Since the noise voltage before filtering is a high-frequency signal, it can be filtered by a low-pass filter, so that high-frequency noise can be filtered out.

In an exemplary embodiment, the event-type image sensor further includes: a differential unit 23, the input terminal of the differential unit 23 is connected to the output terminal of the input unit 21, and the output terminal of the differential unit 23 is connected to the output terminal of the differential unit 23. The input end of the chopper unit 22 is connected;

The difference unit 23 is used for making the difference between the real-time voltage and the preset reference voltage to obtain the difference voltage.

In an exemplary embodiment, applied to an event camera, the event-type image sensor includes: an input unit 21 , a differential unit 23 , a chopper unit 22 , a comparison unit 24 and a readout unit 25 , the input unit 21 , all The difference unit 23, the chopper unit 22, the comparison unit 24 and the readout unit 25 are connected in sequence; wherein,

The input unit 21 is used for acquiring real-time voltage in response to the incident light signal;

The difference unit 23 is used to make a difference between the real-time voltage and the preset reference voltage to obtain the difference voltage;

The chopper unit 22 is configured to use the difference voltage as an input voltage, separate the input voltage from the corresponding noise voltage in frequency, and filter the noise voltage according to the separated frequency to obtain an output voltage;

The comparison unit 24 is used for comparing the output voltage with a preset voltage range;

The readout unit 25 is used for outputting an event signal according to the comparison result.

In this embodiment, the voltage value of the output voltage is within the preset voltage range, indicating that no event signal is output, and it is necessary to continue to collect real-time voltage. When the output is a valid event signal, the current real-time voltage is stored in the capacitor as The reference voltage is preset, and the switch is in an off state at this time, and the operations from step S100 to step S160 are performed again.

In this embodiment, if no event signal is output after the real-time voltage collected in the preset collection time period is processed according to steps S120 to S160, the switch is closed and then opened to reset the preset reference in the capacitor. voltage; and then perform steps S100 to S160 again to output an event signal according to the updated preset reference voltage.

Please refer to FIG. 2 again, which shows a circuit diagram of an event-type image sensor 30 according to an embodiment of the present invention. The circuit diagram includes: a differential unit 23 , a conversion element 210 , a switch 211 , a capacitor 212 , a chopper unit 22 , a comparison unit 24 , and a readout unit 25 .

The input end of the differential unit 23 is connected to the output end of the conversion element 210, and the output end of the differential unit 23 is connected to the input end of the chopper unit 22; the conversion element 210 is used to convert the current corresponding to the incident light signal to obtain the incident light signal The corresponding real-time voltage; the differential unit 23 is used to make a difference between the real-time voltage and the preset reference voltage to obtain the difference voltage.

Please refer to FIG. 3 , the chopper unit 22 includes a first chopper 221 , a second chopper 223 , an amplifier 222 and a low-pass filter 224 . The incident light signal is sampled at time _t1 , the voltage corresponding to the incident light signal is V ₁ , the switch 211 is turned off, and the voltage V ₁ is stored in the capacitor 212 and recorded as the preset reference voltage V ₁ (that is, the voltage of the node A is V 1 ). The voltage is V ₁ ); the real-time voltage corresponding to the incident light signal collected at time t ₂ is V ₂ (ie, the voltage of node B is V ₂ ), that is, the input voltage is V ₂ -V ₁ .

The second output end B of the conversion element 210 is connected to the second input end of the differential unit 23 , the output end of the differential unit 23 is connected to the input end of the first chopper 221 , the first output end of the conversion element 210 is connected to one end of the switch 211 , The other end of the switch 211 is connected to one end of the capacitor 212 and the first input end of the differential unit 23 , and the other end of the capacitor 212 is grounded. The output end of the first chopper 221 is connected to the amplifier 222, the output end of the amplifier 222 is connected to the input end of the second chopper 223, the output end of the second chopper 223 is connected to the low-pass filter 224, and the low-pass filter 224 The output end is connected to a processor or a controller (not shown in the figure).

In this embodiment, the first chopper 221 modulates the difference voltage output by the differential unit 23 as the input voltage, so as to separate the frequency of the input voltage and the noise voltage.

The amplifier 222 amplifies the modulated input voltage together with the noise voltage to obtain an intermediate voltage signal. The intermediate voltage signal is then demodulated by the second chopper 223 according to the preset demodulation signal. The low-pass filter 224 performs low-pass filtering on the demodulated modulation signal and the amplified noise voltage to remove the noise voltage and obtain an output voltage. The modulation and demodulation processing of the first chopper 221 and the second chopper 223 is used to remove the offset voltage.

In this embodiment, the principle of the chopper unit 22 is exemplarily described as follows:

Assume that the relationship between the current signal voltage (V _signal ) and the noise voltage (V _noise ) and the signal frequency (f)/chopping frequency (f _chop ) are shown in FIG. 4 , and the chopping frequency (f _chop ) is the The working frequency, the signal frequency (f) is the frequency of the signal voltage (V _signal ), which can be understood as the current signal voltage is the real-time voltage. The input voltage is modulated by the first chopper 221, and the noise only passes through the amplifier 222 without modulation. The modulated input voltage and the noise voltage are amplified by the amplifier 222, and the signal voltage (V _signal ) and the noise voltage (V The relationship between _noise ) is shown in FIG. 5 , and it can be understood that the signal voltage is an intermediate voltage signal, and the chopping frequency is the operating frequency of the first chopper. Then the signal voltage (V _signal ) and the noise voltage (V _noise ) pass through the second chopper 223 together. The relationship between the signal voltage (V _signal ) and the noise voltage (V _noise ) is shown in FIG. 6 . It can be understood that the signal voltage is The modulated signal after demodulation. Finally, the signal voltage (V _signal ) and the noise voltage (V _signal ) pass through the low-pass filter, and the noise voltage (V _noise ) can be filtered out by the low-pass filter 224 because it is a high-frequency signal, and the output voltage V _out , as shown in the figure 7, it can be understood that the input voltage is the demodulation voltage, and the chopping frequency is the operating frequency of the second chopper. Thus, the modulation and demodulation of the voltage by the chopper unit 22 are realized, so that the frequency of the signal voltage (V _signal ) and the noise voltage (V _noise ) can be changed alternately, so as to filter out the offset voltage and high frequency in the signal voltage noise.

The relationship between the time (t) and the input voltage (V _in ) is exemplarily explained. When the input voltage (V _in ) is modulated by the first chopper, the time (t) is related to the input voltage (V in ) after the input voltage (V _in ) is modulated. V _in ) as shown in Figure 8, the input voltage at this time is the modulated input voltage. Then the input voltage (V _in ) passes through the amplifier, and after the input voltage (V _in ) is amplified, time (t) and the input voltage (V _in ), as shown in FIG. 9 , the input voltage is the modulation voltage. Then the input voltage (V _in ) passes through the second chopper, and after the input voltage (V _in ) is demodulated, the time (t) and the input voltage (V _in ) are shown in FIG. 10 , and the input voltage is the demodulated Modulate the signal, i.e. the demodulated voltage. Finally, the input voltage (V _in ) passes through the low-pass filter, and the time (t) and the input voltage (V _in ) are shown in FIG. 11 , thereby outputting the output voltage V _out shown in FIG. 11 .

In the existing offset removal scheme, since in the traditional event camera, the voltage headroom expression after the equivalent offset correction through the amplifier input is as follows:

Among them, V _{offset-residue} represents the voltage margin after correction, and A represents the magnification.

This solution requires a high-gain amplifier to reduce the effect of random offset voltage, and it is very difficult to integrate a high-gain amplifier in each pixel of the image sensor. In addition, a high-gain amplifier will lead to high power consumption, sampling rate is low. In the present application, the step of eliminating inherent random offset storage is simplified by using the modulation and demodulation principle of the chopper unit. Specifically, the frequency of the input voltage and the accompanying noise voltage is separated by the chopper unit, and the frequency after separation Filter the noise voltage to obtain the output voltage, that is, without using a high-gain amplifier, to realize the integration of large-scale event-type pixels with high quality, high resolution, low power consumption, and high frame rate.

The above is a description of the event-type image sensor and the control method provided by the present invention. For those skilled in the art, according to the idea of the embodiment of the present invention, there will be changes in the specific implementation and application scope. In conclusion, The contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. An event-type image sensor, characterized in that, when applied to an event camera, the event-type image sensor comprises: an input unit, a chopper unit, a comparison unit, and a readout unit, the input unit, the chopper unit , the comparison unit and the readout unit are connected in sequence; wherein, the input unit is used for acquiring real-time voltage in response to the incident light signal; The chopper unit is configured to use the difference voltage between the real-time voltage and the preset reference voltage as the input voltage, separate the input voltage from the noise voltage in frequency, and then filter the noise voltage according to the separated frequency. , get the output voltage; the comparison unit is used for comparing the output voltage with a preset voltage range; The readout unit is used for outputting an event signal according to the comparison result. 2 . The event-type image sensor according to claim 1 , wherein the chopper unit comprises a first chopper unit and a second chopper unit, and the first chopper unit is connected to the input unit and the input unit. 3 . between the second chopper units; The first chopper unit is configured to use the difference voltage between the real-time voltage and the preset reference voltage as an input voltage, and after modulating the input voltage, perform frequency amplification simultaneously with the noise voltage to obtain an intermediate voltage signal; The second chopper unit is used for demodulating the modulation voltage in the intermediate voltage signal and performing low-pass filtering, and filtering the noise voltage to obtain an output voltage. 3 . The event-type image sensor according to claim 2 , wherein the first chopper unit comprises a first chopper and an amplifier, and the input end of the first chopper is connected to the input end of the input unit. 4 . the output end is connected, the output end of the first chopper is connected with the input end of the amplifier, and the output end of the amplifier is connected with the input end of the second chopper unit; The first chopper is used for modulating the difference voltage between the real-time voltage and the preset reference voltage as an input voltage; The amplifier is used for frequency amplifying the modulated input voltage and the noise voltage at the same time to obtain the intermediate voltage signal. 4 . The event-type image sensor according to claim 3 , wherein the second chopper unit comprises a second chopper and a low-pass filter, and an input end of the second chopper is connected to the an output end of the amplifier, the output end of the second chopper is connected to the input end of the low-pass filter, and the output end of the low-pass filter is connected to the comparison unit; the second chopper is used for demodulating the modulation voltage in the intermediate voltage signal; The low-pass filter is used for performing low-pass filtering on the demodulated intermediate voltage signal, and filtering the noise voltage to obtain an output voltage. 5 . The event-type image sensor according to claim 1 , further comprising: a differential unit, the input terminal of the differential unit is connected to the output terminal of the input unit, and the output terminal of the differential unit is connected to the output terminal of the differential unit. 6 . The input end of the chopper unit is connected; The difference unit is used for making a difference between the real-time voltage and a preset reference voltage to obtain the difference voltage. 6 . The event-type image sensor according to claim 5 , wherein the input unit comprises a conversion element, a switch and a capacitor, and the switch is connected between the first output end of the conversion element and the differential unit. 7 . Between the first input terminals, the connection terminal of the switch and the first input terminal of the differential unit is connected to the non-ground terminal of the capacitor, and the second output terminal of the conversion element is connected to the second input terminal of the differential unit. connect; the conversion element is used to convert the incident light signal into the real-time voltage; The capacitor is used to update the preset reference voltage when the switch is switched from a closed state to an open state. 7 . The event-type image sensor according to claim 6 , wherein the conversion element comprises a photoelectric conversion element and a current-voltage conversion element, an output terminal of the photoelectric conversion element and an input terminal of the current-voltage conversion element. 8 . connection, the first output terminal of the current-voltage conversion element is connected with the switch, and the second output terminal of the current-voltage conversion element is connected with the second input terminal of the differential unit; the photoelectric conversion element is used to generate a photocurrent in response to the incident light signal; The current-to-voltage conversion element is used to convert the photocurrent into the real-time voltage. 8. An event-based image sensor control method, characterized in that, applied to an event camera, the method comprising: obtaining a real-time voltage in response to an incident light signal; The difference voltage between the real-time voltage and the preset reference voltage is used as the input voltage, the frequency of the input voltage and the noise voltage is separated, and then the noise voltage is filtered according to the separated frequency to obtain an output voltage; comparing the output voltage to a preset voltage range; An event signal is output according to the comparison result. 9 . The event-based image sensor control method according to claim 8 , wherein the difference voltage between the real-time voltage and the preset reference voltage is used as the input voltage, and the frequency of the input voltage and the noise voltage is performed. 10 . After separation, the noise voltage is filtered according to the separated frequency to obtain an output voltage, including: The difference voltage between the real-time voltage and the preset reference voltage is used as the input voltage, and after the input voltage is modulated, frequency amplification is performed simultaneously with the noise voltage to obtain an intermediate voltage signal; Low-pass filtering is performed after demodulating the modulation voltage in the intermediate voltage signal, and an output voltage is obtained after filtering the noise voltage. 10 . The event-based image sensor control method according to claim 8 , wherein the acquiring a real-time voltage in response to an incident light signal comprises: 10 . generating a photocurrent in response to the incident light signal; The photocurrent is converted to the real-time voltage.

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