WO2021128535A1

WO2021128535A1 - Pixel readout system of dual-modality bionic vision sensor

Info

Publication number: WO2021128535A1
Application number: PCT/CN2020/073537
Authority: WO
Inventors: 施路平; 杨哲宇; 赵蓉; 裴京; 徐海峥
Original assignee: 清华大学
Priority date: 2019-12-24
Filing date: 2020-01-21
Publication date: 2021-07-01
Also published as: CN111083405B; CN111083405A

Abstract

Embodiments of the present invention provide a pixel readout system of a dual-modality bionic vision sensor. Data is transmitted by using a digital-to-analog converter data input bus and a first data output bus, so that the high-speed transmission of input data and output data of a first type of control circuit can be implemented, and then the image generation speed of the dual-modality bionic vision sensor is increased.

Description

Pixel readout system of dual-mode bionic vision sensor

Technical field

The present invention relates to the field of integrated circuit technology, and more specifically, to a dual-mode bionic vision sensor pixel readout system.

Background technique

At present, with the continuous in-depth research on image sensors and image processing and recognition algorithms, bionic vision sensors are playing an increasingly important role in many application fields such as industrial manufacturing, intelligent transportation, and intelligent robots.

The bionic vision sensor mainly simulates the modalities of the retina of the human eye. The retina of the human eye mainly includes two visual perception cells, namely cone cells and rod cells, corresponding to two different modalities respectively. Among them, the mode of cone cells is mainly sensitive to absolute light intensity information and color information, and has high image restoration accuracy, but the restoration speed is slow; contrary to the mode of cone cells, rod cells mainly respond to light. The strong gradient information is perceived, and it has a faster perceiving speed and a larger perceptual dynamic range, but it cannot perceive absolute light intensity information and color information.

However, all the bionic vision sensors in the prior art can only simulate one of the modalities of the retina of the human eye, forming a single perception mode, and thus can only perceive a certain type of information. For example, traditional cameras, similar to cones, mainly perceive color information. For example, Dynamic Vision Sensor (DVS), similar to rod cells, mainly perceives light intensity gradient information. However, the application scenarios of single-modal vision sensors are limited. For example, for a bionic vision sensor similar to cone cells, since it captures absolute light intensity information instead of light intensity gradient information, although it is widely used in home entertainment electronic equipment, it often faces speed in the field of industrial control. Insufficient dynamic range is too small and other issues, so it is difficult to apply. For the bionic vision sensor similar to the rod cell, although the sensing speed is very fast, it is only sensitive to moving targets, which makes it difficult to capture images, or the captured images are of poor quality, which is difficult to meet the needs of entertainment electronic devices. Moreover, because the bionic vision sensor only contains a single perception mode, the bionic vision sensor will fail when this perception mode fails, which has great limitations for unmanned, unmanned aerial vehicles and other robots that have high requirements for stability. In addition, the current main indicators for evaluating the performance of the bionic vision sensor include image quality, dynamic range and shooting speed. As can be seen from the above content, in the framework of the traditional bionic vision sensor, these three indicators are often mutually exclusive: for example, when the shooting speed increases, the dynamic range of the bionic vision sensor will decrease; when the image quality increases, the shooting speed will generally be It is difficult to take both into consideration at the same time.

Therefore, there is an urgent need to provide a bionic vision sensor with dual perception modes, that is, a dual-mode bionic vision sensor that can sense absolute light intensity information, color information, and light intensity gradient information at the same time, and furthermore, it is necessary to provide a matching pixel Read the system.

Summary of the invention

In order to overcome the above-mentioned problems or at least partially solve the above-mentioned problems, embodiments of the present invention provide a dual-mode bionic vision sensor pixel readout system.

The embodiment of the present invention provides a dual-mode bionic vision sensor pixel readout system, including: a digital-to-analog converter data input bus and a first data output bus;

The data input bus of the digital-to-analog converter is connected to the digital-to-analog converter corresponding to the control circuit of the first type, and the first data output bus is connected to the output terminal of the control circuit of the first type; the control circuit of the first type It is the control circuit corresponding to the target first type photosensitive device in the pixel array of the dual-mode bionic vision sensor;

Wherein, the target first-type photosensitive device is used to obtain a target light signal and convert the target light signal into a first-type current signal; the first-type control circuit is used to compare the first-type current signal with The difference between the sum of the second-type current signals converted by a first preset number of non-target first-type photosensitive devices around the target first-type photosensitive device, and outputting information representing the light intensity gradient information in the target optical signal Specify a digital signal.

Preferably, the dual-mode bionic vision sensor pixel readout system further includes: an addressing decoder;

The address decoder is used to read the output result of the second type of control circuit, the second type of control circuit is the control circuit corresponding to the second type of photosensitive device in the pixel array;

Wherein, the second type photosensitive device is used to obtain the target light signal, extract the light signal of a specified frequency band from the target light signal, and convert the light signal of the specified frequency band into a third type current signal; The second type of control circuit is configured to output an analog voltage signal representing the light intensity information in the target light signal based on the third type of current signal.

Preferably, the dual-mode bionic vision sensor pixel readout system further includes: an analog-to-digital converter;

The analog-to-digital converter is connected to the addressing decoder, and the analog-to-digital converter is used to convert the output result of the second-type control circuit read by the addressing decoder into a digital voltage signal.

Preferably, the dual-mode bionic vision sensor pixel readout system further includes: a second data output bus;

The second data output bus is connected to the analog-to-digital converter.

Preferably, the dual-mode bionic vision sensor pixel readout system further includes: a correlated double sampling circuit CDS;

The CDS is connected between the second type control circuit and the address decoder.

Preferably, every second predetermined number of control circuits of the first type share one digital-to-analog converter.

Preferably, the dual-mode bionic vision sensor pixel readout system further includes: a first storage unit;

The first storage unit is configured to store the output results of the first-type control circuit for every second preset number.

Preferably, the dual-mode bionic vision sensor pixel readout system further includes: a second storage unit;

The second storage unit is used to store all output results of the first-type control circuit stored in the first storage unit.

Preferably, the dual-mode bionic vision sensor pixel readout system further includes: a clock and a phase-locked loop;

The clock is connected to the phase-locked loop, and the phase-locked loop is connected to the digital-to-analog converter corresponding to the first type of control circuit, the first storage unit, and the second storage unit.

Preferably, the addressing decoder specifically includes: an X-direction addressing decoder and a Y-direction addressing decoder;

The X-direction addressing decoder is used to read the output result of the second-type control circuit corresponding to the second-type photosensitive device in each column of the pixel array;

The Y-direction addressing decoder is used to read the output results of the second-type control circuit corresponding to the second-type photosensitive device in each row of the pixel array.

According to an embodiment of the present invention, a dual-mode bionic vision sensor pixel read-out system can realize data input and output to the first type of control circuit by using a digital-to-analog converter data input bus and a first data output bus to transmit data. The high-speed transmission of data further increases the image generation speed of the dual-mode bionic vision sensor.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

FIG. 1 is a schematic diagram of an arrangement of a pixel array of a dual-mode bionic vision sensor according to an embodiment of the present invention;

2 is a schematic diagram of the arrangement of a pixel array of a dual-mode bionic vision sensor according to an embodiment of the present invention;

3 is a schematic structural diagram of a first-type current mode active pixel sensor circuit for controlling a target first-type photosensitive device according to an embodiment of the present invention;

4 is a schematic diagram of the variation of the designated digital signal input to the DAC 15 in the first type of current mode active pixel sensor circuit provided by an embodiment of the present invention;

5 is a schematic diagram of a specific structure of a first type of current mode active pixel sensor circuit provided by an embodiment of the present invention;

6 is a schematic structural diagram of a dual-mode bionic vision sensor pixel readout system provided by an embodiment of the present invention;

7 is a schematic diagram of a specific structure of a voltage mode active pixel sensor circuit provided by an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of an address decoder provided by an embodiment of the present invention;

9 is a schematic diagram of a specific structure of a second type of current mode active pixel sensor circuit provided by an embodiment of the present invention;

FIG. 10 is a schematic diagram of the connection of an addressing decoder provided by an embodiment of the present invention;

FIG. 11 is a schematic structural diagram of a CDS provided by an embodiment of the present invention;

FIG. 12 is a circuit timing diagram of a CDS provided by an embodiment of the present invention;

Figure 13 is a schematic structural diagram of a CDS provided by an embodiment of the present invention;

FIG. 14 is a schematic structural diagram of a pixel readout system of a dual-mode bionic vision sensor provided by an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are 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 of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

In the description of the embodiments of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" The orientation or positional relationship indicated by "" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present invention and simplifying the description, and does not indicate or imply that the pointed device or element must have a specific orientation, It is constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiment of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be interpreted broadly. For example, they may be fixed connections or Removable connection or integral connection; it can be mechanical connection or electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood in specific situations.

The data input bus of the digital-to-analog converter is connected to a digital-to-analog converter (DAC) corresponding to the control circuit of the first type, and the first data output bus is connected to the output terminal of the control circuit of the first type; One type of control circuit is the control circuit corresponding to the target first type photosensitive device in the pixel array of the dual-mode bionic vision sensor;

Specifically, in the embodiment of the present invention, the pixel array of the dual-mode bionic vision sensor is formed by arranging a plurality of first-type photosensitive devices and a plurality of second-type photosensitive devices. Specifically, it may be composed of first-type photosensitive devices and second-type photosensitive devices. The photosensitive devices are arranged alternately. Each photosensitive device of the first type and each photosensitive device of the second type respectively serve as a pixel. Among them, the number of photosensitive devices of the first type and the number of photosensitive devices of the second type can be set according to the size of the pixel array, and can be the same or different, which is not specifically limited in the embodiment of the present invention.

Both the first type of photosensitive device and the second type of photosensitive device are used to obtain the target light signal.

The first type of photosensitive device includes the target type 1 photosensitive device and the non-target type 1 photosensitive device. The target type 1 photosensitive device is also used to convert the target light signal into the first type current signal, and the non-target type 1 photosensitive device is also Used to convert the target light signal into the second type current signal. The first type of photosensitive device may specifically be a photodiode with the same response curve.

The second type of photosensitive device is also used to extract the optical signal of the specified frequency band from the target optical signal, and convert the optical signal of the specified frequency band into the third type of current signal. The second type of photosensitive device has photodiodes that may have different response curves. The response frequency band of the second type of photosensitive device is specifically a designated frequency band, and the designated frequency band may be a red light frequency band, a blue light frequency band or a green light frequency band. The second type of photosensitive device can also be composed of photodiodes and color filters (CF) with the same response curve. The color filters can specifically be red, blue, or green filters, respectively It is used to extract the optical signal in the red, blue or green frequency band from the target optical signal. It should be noted that the color filter may be a light filter or a lens. When the color filter is a lens, a Byron lens may be used, or other types of lenses may be used.

In the following embodiments, only the second type of photosensitive device is composed of photodiodes and color filters with the same response curve as an example for description.

The pixel array of the dual-mode bionic vision sensor can be arranged as shown in Figure 1. Figure 1 only shows a 7×7 pixel array, consisting of 25 first-type photosensitive devices 11 and 24 second-type photosensitive devices The 12-phase arrangement is formed. The “+” marks in Figure 1 are the target first-type photosensitive devices, the “-” marks are non-target first-type photosensitive devices, and the R, G, and B marks are all second-type photosensitive devices. And respectively represent the second type of photosensitive device that extracts light signals in the red frequency band, the second type of photosensitive device that extracts light signals in the green frequency band, and the second type of photosensitive device that extracts light signals in the blue frequency band. For example, they are a second-type photosensitive device with a red color filter, a second-type photosensitive device with a green color filter, and a second-type photosensitive device with a blue color filter, respectively. The arrangement of the pixel array of the dual-mode bionic vision sensor may also be as shown in FIG. 2 or other arrangements, which are not specifically limited in the embodiment of the present invention.

Each target first-type photosensitive device corresponds to a control circuit, and the control circuit corresponding to the target first-type photosensitive device is a first-type control circuit, specifically a first-type current-mode active pixel sensor circuit, which is used based on the first-type The difference between the current signal and the sum of the second-type current signal converted by the first preset number of non-target first-type photosensitive devices around the target first-type photosensitive device, and output the designation that characterizes the light intensity gradient information in the target optical signal Digital signal. In the embodiment of the present invention, the first type of control circuit is used to simulate the action of excitatory rod cells.

The control circuit of the first type includes a target first-type photosensitive device, a first current amplifier, a comparator, an adder, a digital-to-analog converter, and a tri-state gate circuit; the target first-type photosensitive device is connected to the first current amplifier, so The first current amplifier is connected to an input terminal of the comparator; the input terminals of the adder are respectively connected to the first type control switch, and the output terminal of the adder is connected to the other input of the comparator. Terminal connected; the output terminal of the comparator is connected to the digital-to-analog converter, and the digital-to-analog converter converts the input specified digital signal into a specified analog signal, and outputs the specified analog signal to the first The current amplifier or the adder until the output terminal of the comparator outputs an event pulse signal, that is, the comparator is in an edge trigger state, the first type current mode active pixel sensor circuit outputs the designated digital signal, and the The designated digital signal is used to characterize the light intensity gradient information in the target light signal.

The three-state gate circuit is respectively connected to the output terminal of the comparator and the input terminal of the digital-to-analog converter; the three-state gate circuit is used to output the event pulse signal at the output terminal of the comparator , That is, when the comparator is in the edge trigger state, the specified digital signal is output.

As shown in FIG. 3, it is a first-type current mode active pixel sensor circuit for controlling a target first-type photosensitive device provided in an embodiment of the present invention. The first-type current mode active pixel sensor circuit in FIG. 3 includes a target first-type photosensitive device 11, a first current amplifier 12, a comparator 13, an adder 14, and a digital to analog converter (DAC) 15. The target first-type photosensitive device 11 is connected to the first current amplifier 12, and the first current amplifier 12 is used to _{amplify the first-type current signal I 0} converted by the target first-type photosensitive device 11, and the amplification factor is the first preset Set the number, that is, the magnification factor is equal to the number of non-target first-type photosensitive devices around the target first-type photosensitive device 11, so as to ensure that the amplified first-type current signal is equal to the first type around the target first-type photosensitive device 11. It is assumed that the sum of the second-type current signals converted by the number of non-target second-type photosensitive devices is on the same order of magnitude. It should be noted that the first type of photosensitive device provided in the embodiment of the present invention does not extract the optical signal of the specified frequency band from the target light signal, that is, the response curves are all the same or there is no filter in the first type of photosensitive device, therefore The response frequency band of the first type of photosensitive device is related to itself.

The first current amplifier 12 is connected to an input terminal of the comparator 13 and inputs the amplified first-type current signal into the comparator 13. The four non-target first-type photosensitive devices around the target first-type photosensitive device 11 are all connected to the input ends of the adder 14 respectively. Because each non-target first-type photosensitive device is connected in series with a first-type control switch. In the embodiment of the present invention, only the first-type control switches M ₁ , M ₂ , M ₃ , and M ₄ connected in series with each non-target first-type photosensitive device are shown.

The output terminal of the adder 14 is connected to the other input terminal of the comparator 13. _{The current signals I 1} , I ₂ , I ₃ , and I ₄ obtained by the conversion of the four non-target type 1 photosensitive devices are input to the adder 14 respectively, and the adder 14 calculates _{I 1} , I ₂ , I ₃ , and I ₄ And input the sum result to the comparator 13. The comparator 13 compares the amplified first-type current signal and the sum result of the adder 14. If the comparison result between the current moment and the current moment is consistent, no output is made. The DAC15 converts the input designated digital signal into a designated analog signal, and outputs the designated analog signal to the first current amplifier 12 or the adder 14, and then outputs it to the first current amplifier 12 or the adder 14. The designated analog signal of a current amplifier 12 is denoted as I _DA2 , and the designated analog signal output to the adder 14 is denoted as I _DA1 . After the output, the comparator 13 is used for comparison. When the comparison result at the current moment is opposite to the latter moment, the output terminal of the comparator 13 outputs the event pulse signal, that is, the comparator 13 is in the edge-triggered state. At this time, the first type of current The pattern active pixel sensor circuit outputs a designated digital signal, and the designated digital signal is used to characterize the light intensity gradient information in the target light signal. Among them, the designated digital signal output by the first-type current mode active pixel sensor circuit is a digital signal represented by 0 and 1. The tri-state gate circuit 41 is respectively connected to the output terminal of the comparator 13 and the input terminal of the DAC 15; the tri-state gate circuit 41 is used to output an event pulse signal at the output terminal of the comparator 13, that is, when the comparator 13 is in the edge trigger state, The specified digital signal is output.

Among them, the designated digital signal input to the DAC15 can be a designated digital signal that is manually inputted periodically. The change form of the designated digital signal is shown in Fig. 4, and the designated digital signal increases stepwise with time. In the case of N*step, the designated digital signal value is ΔI, and the comparator 13 outputs an event pulse signal, that is, the comparator 13 is in an edge-triggered state, and the ΔI at this time is used as the output of the first-type current mode active pixel sensor circuit. Among them, N is the number of steps passed before, and step is the time length of each step.

As shown in FIG. 5, it is a schematic diagram of the specific structure of the first type of current mode active pixel sensor circuit provided in the embodiment of the present invention. In FIG. 5, the circuit structure 51 simulates a rod cell circuit, and the circuit structure 52 simulates a ganglion cell and a bipolar cell. Vcc is the power supply of the control circuit. The target first-type photosensitive device 53 is connected to Vcc. The first-type current signal I ₀ converted by the target first-type photosensitive device 53 is amplified by 4 times by the current mirror 54 and then compared with the comparator (Comparer, CP). ) 56 is connected to the input terminal, and the current signals converted by the four non-target first-type photosensitive devices around the target first-type photosensitive device 53 are respectively I ₁ , I ₂ , I ₃ , and I ₄ .

It should be noted that the current mirror 54 in FIG. 5 is the first current amplifier. Fig. 5 does not show the four non-target first-type photosensitive devices around the target first-type photosensitive device 53, only the first-type control switches M ₁ , which are connected in series with each non-target first-type photosensitive device. M ₂ , M ₃ , M ₄ . The lines where I ₁ , I ₂ , I ₃ , and I ₄ are located are merged into one line to realize the function of an adder. The combined line is connected to the input terminal of CP56. The CP56 compares the amplified first-type current signal and the sum of I ₁ , I ₂ , I ₃ , and I ₄ . If the comparison result between the current moment and the current moment is consistent, no output is made. The DAC55 converts the input designated digital signal into a designated analog signal, and outputs the designated analog signal to the target type 1 photosensitive device 53 or a non-target A type of photosensitive device. After the output, the CP56 is used for comparison. When the comparison result of the current time and the next time is opposite, the output terminal of the CP56 outputs the event pulse signal, that is, the CP56 is in the edge-triggered state. At this time, the three-state gate circuit 57 outputs the specified digital signal .

In FIG. 5, a capacitor 58 is also connected between CP56 and ground. The capacitor 58 can be an actual capacitor or a virtual parasitic capacitor in the first-type current mode active pixel sensor circuit. This is in the embodiment of the present invention. There is no specific limitation.

As shown in Figure 6, the dual-mode bionic vision sensor pixel readout system includes: a digital-to-analog converter data input bus and a first data output bus; the digital-to-analog converter data input bus is connected to the DAC corresponding to the first type of control circuit , The first data output bus is connected with the output terminal of the first type of control circuit. In Figure 6, the pixel array used is composed of multiple M rows and N columns of sub-pixel arrays. Each sub-pixel array has a total of M×N pixels, which are Pixel(0,0), Pixel(1,0),... , Pixel(N,0),..., Pixel(N,M). Each pixel corresponds to one photosensitive device, and the arrangement of the photosensitive devices can be as shown in Fig. 1 or Fig. 2. Each control circuit of the first type can correspond to a DAC, or as shown in Figure 6, a plurality of control circuits of the first type share one DAC, and the number of the control circuits of the first type sharing the DAC is specifically the second preset number. That is, the number of first-type control circuits corresponding to all target first-type photosensitive devices included in each sub-pixel array.

In the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention, the data input bus and the first data output bus of the digital-to-analog converter are used to transmit data, and the input data and output data to the first-type control circuit can be realized. The high-speed transmission, which in turn improves the image generation speed of the dual-mode bionic vision sensor.

On the basis of the foregoing embodiment, the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention further includes: an addressing decoder;

Specifically, in the embodiment of the present invention, the control circuit corresponding to the second type of photosensitive device in the pixel array of the dual-mode bionic vision sensor is a second type of control circuit, and the second type of control circuit is specifically a voltage mode active pixel sensor circuit , For outputting an analog voltage signal representing the light intensity information in the target light signal based on the third type of current signal. As shown in FIG. 7, in FIG. 7, there are a total of 4 second-type photosensitive devices, namely 71, 72, 73, and 74. The second-type photosensitive device 71 and the second-type control switch 75 are connected in series to form the first device branch. , The second type of photosensitive device 72 and the second type of control switch 76 are connected in series to form a second device branch, the second type of photosensitive device 73 and the second type of control switch 78 are connected in series to form a third device branch, and the second type of photosensitive device 74 is connected in series with The second type of control switches 77 are connected in series to form a fourth device branch. The first device branch, the second device branch, the third device branch, and the fourth device branch are connected in parallel to the

MOS transistors

79 and 710, and the MOS transistor 710 is connected to the MOS transistor 711. The MOS tube 79 is used for biasing, the MOS tube 710 is used for switching, and the MOS tube 711 is used for current integration of the third type current signal converted by the second type photosensitive device on a certain device branch to obtain the analog The voltage signal represents the light intensity information in the target light signal.

In the embodiment of the present invention, the main function of the addressing decoder is to convert N channels of input data to ^2N conversion. As shown in Figure 8, the N inputs of the addressing decoder can be the output results of N second-type control circuits, denoted as I ₀ , I ₁ , ..., I _N-1 , the addressing decoder’s 2 ^N output is denoted as

The addressing decoder is controlled by the clock Clk and powered by En.

In the embodiment of the present invention, the address decoder is introduced to read the output results of the second-type control circuit, which can avoid that each second-type control circuit is connected to an output line to output the results, which can save resources and improve data. The transmission speed.

On the basis of the foregoing embodiment, in the embodiment of the present invention, the control circuit of the dual-mode bionic vision sensor further includes: a third control circuit for controlling each non-target first-type photosensitive device. The third control circuit is specifically a second type of current mode active pixel sensor circuit. The third control circuit includes a non-target first-type photosensitive device and a second preset number of current mirrors; each current mirror is connected in series with a second-type photosensitive device around the non-target first-type photosensitive device.

Specifically, each second-type current mode active pixel sensor circuit in the embodiment of the present invention controls a non-target first-type photosensitive device.

As shown in FIG. 9, the second-type current mode active pixel sensor circuit includes a non-target first-type photosensitive device 81 and four first-type current mirrors 82, 83, 84, 85. Each first-type current mirror is connected in series with a target first-type photosensitive device around the non-target first-type photosensitive device 81, that is, the current signal I ₁ obtained by the conversion of the non-target first-type photosensitive device 81 is copied into four I ₁ , Which are respectively used for the first-type current mode active pixel sensor circuit of each target first-type photosensitive device around the non-target first-type photosensitive device 81 to obtain the light intensity gradient information in the target light signal to achieve the non-target The multiplexing of the first type of photosensitive device improves the pixel fill factor of the reconfigurable dual-mode bionic vision sensor.

As shown in FIG. 10, on the basis of the foregoing embodiment, in the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention, the addressing decoder specifically includes: an X-direction addressing decoder and Y-direction addressing decoder;

Specifically, in the embodiment of the present invention, if the pixel array size of the dual-mode bionic vision sensor is 640*240, the size of each sub-pixel array is 40*40. For each sub-pixel array, the value of N in the X-direction addressing decoder is N=10 (log ₂ 640), and the value of N in the Y-direction addressing decoder is N=8 (log ₂ 240). When the X-direction addressing decoder is used for vertical X or the Y-direction addressing decoder is used for horizontal Y access, the output results of the control circuit corresponding to the pixels in the pixel array will be sequentially addressed and read.

On the basis of the foregoing embodiment, the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention further includes: an analog-to-digital converter (ADC), ADC and addressing decoding The ADC is specifically connected with the X-direction addressing decoder, and the ADC is used to convert the output result of the second type of control circuit read by the addressing decoder into a digital voltage signal.

Specifically, in the embodiment of the present invention, for each sub-pixel array, the output result of the second type of control circuit in FIG. 7 is the result obtained by the current integration of the MOS tube 711, which is an analog voltage signal, which needs to be connected to the ADC to achieve analog-to-digital conversion. Get the digital voltage signal.

On the basis of the foregoing embodiment, the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention further includes: a second data output bus;

The second data output bus is connected to the analog-to-digital converter.

As shown in FIG. 10, on the basis of the foregoing embodiment, the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention further includes: a correlated double sampling circuit (Correlated Double Sampling, CDS), and the CDS is connected to The second type of control circuit and the addressing decoder can be specifically connected between the second type of control circuit and the X-direction addressing decoder, and the CDS and the X-direction addressing decoder are connected through a bus.

Specifically, in the embodiment of the present invention, the purpose of using CDS is to reduce the output noise of the second type of control circuit. CDS basic circuit shown in Figure 11, the left side in FIG. 11 only shows a control device of the second type branch circuit, the second type and the second type sensing device PD M _TG control switch in series, and M _TG The MOS tube M _RS and M _{SF are} connected, and the MOS tube M _{SF is} connected with the MOS tube M _SEL . The MOS tube M _{RS is} used for biasing, the MOS tube M _{SF is} used for switching, and the MOS tube M _{SEL is} used for current integration of the third type current signal obtained by PD conversion to obtain an analog voltage signal to represent the target light signal In the light intensity information, and output analog voltage signal. M _RS and M _SF are also connected to a capacitor FD. The capacitor FD may be an actual capacitor or a parasitic capacitor of the CDS, which is not specifically limited in the embodiment of the present invention.

FIG 11 is a right side the CDS, by two S / H circuit, and a differential amplifier, specifically to work: the reset level and the signal level is sampled and held in the capacitor C _R, respectively, and the capacitance C _S, C _R are connected to the MOS transistor M _R and M _Y, C _S is connected to the MOS transistor M _S and M _Y; each of the reset level and the signal level remains at the C _R and C _S is obtained by differentiating the output signal. The circuit timing diagram of CDS is shown in Figure 12. In Figure 12

with

They respectively represent the levels of the MOS transistors M _SEL , M _RS , the second type control switch M _TG , and the MOS transistors M _R , M _S , and M _Y.

In the signal readout stage, the MOS tube M _{SEL is} always on from t ₁ to t ₇ , so M _{SEL is} always on.

Always at a high level; at t ₁ time, ADC reads the reset level and switching noise, and then at t ₂

Set high (at this time, the capacitor FD is reset) after the

Stored in the capacitor _CR ; at this time, the sample-and-hold reset signal is in the capacitor _CR , and at t ₃

Set high, and then read the signal level; at t ₄ by

Set high, opening charge a second type of control switch M _TG accumulated in the FD is transferred to the capacitor; at the time t ₅

Set high, the accumulated charge in the capacitor FD is sampled and held in C _S ; finally, at t ₆

Set high to realize the integration of the accumulation signal and the reset signal.

It should be noted that the schematic structural diagram of the CDS in the embodiment of the present invention may also be as shown in FIG. 13. The specific values of the capacitors C ₁ and C ₂ can be set according to requirements, which are not specifically limited in the embodiment of the present invention.

On the basis of the foregoing embodiment, the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention further includes: a first storage unit;

Specifically, in the embodiment of the present invention, for each sub-pixel array, there is a first storage unit that stores the output results of the first-type control circuit corresponding to all the target first-type photosensitive devices in the sub-pixel array. In other words, the second preset number refers to the number of first-type control circuits corresponding to all target first-type photosensitive devices in each sub-pixel array. The first storage unit may specifically be a register, a latch, an SRAM, a DRAM, a memristor, etc.

On the basis of the foregoing embodiment, the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention further includes: a second storage unit;

The second storage unit is used for summarizing the output results of the first-type control circuit stored in all the first storage units.

Specifically, in the embodiment of the present invention, for the pixel array of the dual-mode bionic vision sensor, there is a second storage unit, which stores the control circuit of the first type in the first storage unit in all the sub-pixel arrays in the pixel array. The output results are summarized. The second storage unit may specifically be a register, a latch, an SRAM, a DRAM, a memristor, etc.

On the basis of the foregoing embodiment, the dual-mode bionic vision sensor pixel readout system provided in the embodiment of the present invention further includes: a clock and a phase-locked loop;

As shown in FIG. 14, for each sub-pixel array, the sub-pixel array includes M rows and N columns of pixels, and the pixel arrangement can be as shown in FIG. 1 or FIG. 2. The first-type control circuit corresponding to all the target first-type photosensitive devices in each sub-pixel array corresponds to the same DAC. The input end of the DAC is connected to the data input bus of the digital-to-analog converter, and the input is DA_par, which is output by the DAC to each sub-pixel array. The output of one type of control circuit is DA_val. The X-direction addressing decoder and the Y-direction addressing decoder are used to respectively address the first-type control circuits corresponding to all target first-type photosensitive devices in each sub-pixel array in the X-direction and the Y-direction. Before addressing in the X direction, CDS is also used to reduce the output noise of the second type of control circuit. The first storage unit stores the output results of the first-type control circuit corresponding to all the target first-type photosensitive devices in the sub-pixel array. The first storage unit is connected to the second storage unit. The second storage unit is connected to the user interface 1 through a first data bus, and the user interface 1 is used to display an image formed by a designated digital signal obtained by a dual-mode bionic vision sensor. On the other hand, the X-direction addressing decoder is connected to the ADC, and the input of the ADC is AD_par. The ADC is connected to the user interface 2 through a second data bus, and the user interface 2 is used to display the image formed by the digital voltage signal obtained by the dual-mode bionic vision sensor.

Fig. 14 also includes a logic control center, which is used to implement logic control; it also includes a user configuration interface, which is used to implement user configuration; and a third storage unit, which is used to implement storage of user configuration information. The third storage unit may specifically be a register, a latch, an SRAM, a DRAM, a memristor, etc. Fig. 14 also includes a clock CLK and a phase-locked loop (Phase Locked Loop, PLL). The clock CLK is used to send a clock signal clk0 to the PLL to realize clock control of the PLL. The clock CLK also sends the clock signal clk1 to the DAC through the PLL, the clock signal clk2 to the first storage unit, the clock signal clk3 to the second storage unit, the clock signal clk4 to the ADC, the clock signal clk5 to the user interface 1, and the logic The control center sends the clock signal clk6 to realize the clock control of the DAC, the first storage unit, the second storage unit, the ADC, the user interface 1, and the logic control center. The input of the DAC and the input of the ADC can be controlled through the logic control center.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions recorded in the foregoing embodiments are modified, or some of the technical features thereof are equivalently replaced; these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

A dual-mode bionic vision sensor pixel readout system is characterized by comprising: a digital-to-analog converter data input bus and a first data output bus;

The data input bus of the digital-to-analog converter is connected to the digital-to-analog converter corresponding to the control circuit of the first type, and the first data output bus is connected to the output terminal of the control circuit of the first type; the control circuit of the first type It is the control circuit corresponding to the target first type photosensitive device in the pixel array of the dual-mode bionic vision sensor;

Wherein, the target first-type photosensitive device is used to obtain a target light signal and convert the target light signal into a first-type current signal; the first-type control circuit is used to compare the first-type current signal with The difference between the sum of the second-type current signals converted by a first preset number of non-target first-type photosensitive devices around the target first-type photosensitive device, and outputting information representing the light intensity gradient information in the target optical signal Specify a digital signal.
The dual-mode bionic vision sensor pixel readout system according to claim 1, further comprising: an addressing decoder;

The address decoder is used to read the output result of the second type of control circuit, the second type of control circuit is the control circuit corresponding to the second type of photosensitive device in the pixel array;

Wherein, the second type photosensitive device is used to obtain the target light signal, extract the light signal of a specified frequency band from the target light signal, and convert the light signal of the specified frequency band into a third type current signal; The second type of control circuit is configured to output an analog voltage signal representing the light intensity information in the target light signal based on the third type of current signal.
The dual-mode bionic vision sensor pixel readout system according to claim 2, further comprising: an analog-to-digital converter;

The analog-to-digital converter is connected to the addressing decoder, and the analog-to-digital converter is used to convert the output result of the second-type control circuit read by the addressing decoder into a digital voltage signal.
The dual-mode bionic vision sensor pixel readout system according to claim 3, further comprising: a second data output bus;

The second data output bus is connected to the analog-to-digital converter.
The dual-mode bionic vision sensor pixel readout system according to claim 2, further comprising: a correlated double sampling circuit CDS;

The CDS is connected between the second type control circuit and the address decoder.
The dual-mode bionic vision sensor pixel readout system according to claim 1, wherein every second preset number of the first-type control circuits share one digital-to-analog converter.
The dual-mode bionic vision sensor pixel readout system according to claim 6, further comprising: a first storage unit;

The first storage unit is configured to store the output results of the first-type control circuit for every second preset number.
8. The dual-mode bionic vision sensor pixel readout system according to claim 7, further comprising: a second storage unit;

The second storage unit is used for summarizing the output results of the first-type control circuit stored in all the first storage units.
8. The dual-mode bionic vision sensor pixel readout system according to claim 8, further comprising: a clock and a phase-locked loop;

The clock is connected to the phase-locked loop, and the phase-locked loop is connected to the digital-to-analog converter corresponding to the first type of control circuit, the first storage unit, and the second storage unit.
The dual-mode bionic vision sensor pixel readout system according to claim 2, wherein the addressing decoder specifically comprises: an X-direction addressing decoder and a Y-direction addressing decoder;

The X-direction addressing decoder is used to read the output result of the second-type control circuit corresponding to the second-type photosensitive device in each column of the pixel array;

The Y-direction addressing decoder is used to read the output results of the second-type control circuit corresponding to the second-type photosensitive device in each row of the pixel array.