Image sensor, image generation method and photoelectric equipment

Abstract

The invention relates to the technical field of image sensors, and discloses an image sensor, an image generation method and photoelectric equipment, the image sensor is a pixel array composed of a plurality of pixels, and each pixel comprises an input circuit, a floating diffusion node, a buffer branch, a first read-out branch and a second read-out branch; the input circuit is used for converting incident light into corresponding charges and outputting the charges to the floating diffusion node so as to form voltage on the floating diffusion node; the buffer branch is configured with a contact point, and the buffer branch performs potential buffer on the voltage formed on the floating diffusion node so as to output the voltage through the contact point; the contact point is connected with the first read-out branch and the second read-out branch; the first read-out branch outputs a gray scale signal according to the voltage output by the contact point; the second readout branch outputs an event signal according to the voltage output by the contact point. According to the invention, different image signals can be output through a single pixel without greatly changing a pixel circuit structure of a single image signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image sensors, in particular to an image sensor, an image generation method and an optoelectronic device. BACKGROUND

[0002] An image sensor is a device that converts an optical image into an electrical signal, and it has a wide range of applications in the field of digital imaging, such as digital cameras, mobile phones, monitoring devices, etc. Traditional image sensors are mainly based on Charge-Coupled Device (CCD) and Complementary Metal Oxide Semiconductor (CMOS) technologies. CCD image sensors are known for their high image quality and low noise, but their manufacturing process is complex, the cost is high, and the power consumption is large. CMOS image sensors gradually become the mainstream of the market with the advantages of low cost, low power consumption and easy integration.

[0003] In recent years, Event-based Vision Sensor (EVS) has emerged. Compared with Active Pixel Sensor (APS), i.e. CMOS image sensor, EVS can record hundreds or even thousands of images within milliseconds. This high-speed shooting capability makes event cameras have unique advantages in capturing moving objects or rapidly changing scenes. Therefore, in order to balance the advantages of high imaging quality of APS and the shooting capability of EVS on moving scenes, the prior art fuses the two types of sensors to realize a composite image sensor that can output APS data and EVS data. However, on the one hand, most of the existing composite image sensors cannot realize the compatible output of APS data and EVS data on the same pixel; on the other hand, some composite image sensors can output APS data and EVS data on the same pixel, but they need to make great changes to the existing mature and stable APS pixel circuit structure, which not only increases the area of each pixel, but also has high implementation difficulty and is easy to cause a significant reduction in the imaging quality of the fused pixel. SUMMARY

[0004] The embodiments of the present application provide an image sensor, an image generation method and an optoelectronic device, which can solve the technical problem that the current composite image sensor needs to make great changes to the pixel circuit structure when performing fusion, resulting in a significant reduction in the imaging quality of the fused pixel.

[0005] A first aspect of the embodiments of the present application provides an image sensor, comprising a pixel array composed of a plurality of pixels, and each pixel comprises an input circuit, a floating diffusion node, a buffer branch, a first readout branch and a second readout branch.

[0006] The input circuit is connected with the floating diffusion node, and the input circuit is configured to convert incident light into corresponding electric charges and output the electric charges to the floating diffusion node to form a voltage on the floating diffusion node;

[0007] The buffer branch is connected with the floating diffusion node, and the buffer branch is configured with a contact point, and the buffer branch is configured to perform potential buffering on the voltage formed on the floating diffusion node to output the voltage through the contact point;

[0008] The contact point is configured to connect the first readout branch and the second readout branch;

[0009] The first readout branch is configured to output a corresponding gray scale signal according to the voltage output by the contact node;

[0010] The second readout branch is configured to output a corresponding event signal according to the voltage output by the contact node.

[0011] The image sensor provided by the embodiment of the present application includes a pixel array composed of a plurality of pixels, and each unit pixel in the pixel array is configured with an input circuit, a floating diffusion node, a buffer branch, a first readout branch and a second readout branch. The input circuit is connected with the floating diffusion node, and the input circuit is configured to convert incident light into corresponding electric charges and output the electric charges to the floating diffusion node to form a voltage on the floating diffusion node. The buffer branch is connected with the floating diffusion node, and the buffer branch is configured with a contact point, and the buffer branch is configured to perform potential buffering on the voltage formed on the floating diffusion node to output the voltage through the contact point. The contact point is configured to connect the first readout branch and the second readout branch. The first readout branch is configured to output a corresponding gray scale signal according to the voltage output by the contact node. The second readout branch is configured to output a corresponding event signal according to the voltage output by the contact node. Thus, the pixel of the image sensor of the present application has the ability to detect and output different signals, and the present application connects two different readout branches at the same contact point, so that different image signals can be output on the same pixel without significantly changing the existing pixel circuit structure (such as the pixel circuit structure corresponding to APS) of a single image sensor, thereby reducing the difficulty of implementing multi-image sensor fusion to generate an image, improving the imaging quality of the fused pixel, and improving stability and reliability.

[0012] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, but not limiting the present disclosure.

[0013] The second aspect of the embodiment of the present application provides an image generation method applied to an image sensor, and the method includes:

[0014] Acquiring incident light of the image sensor;

[0015] generating an event signal and a gray scale signal from the incident light, wherein the event signal and the gray scale signal are used to generate an image.

[0016] A third aspect of the embodiments of the present application provides an optoelectronic device, comprising the image sensor described above.

[0017] It can be understood that the beneficial effects of the second aspect and the third aspect described above can be referred to the related description in the first aspect described above, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0019] Figure 1 is a first module block diagram of the image sensor provided by the embodiments of the present application;

[0020] Figure 2 is a second module block diagram of the image sensor provided by the embodiments of the present application;

[0021] Figure 3 is a third module block diagram of the image sensor provided by the embodiments of the present application;

[0022] Figure 4 is a circuit structure schematic diagram of the pixel in the image sensor provided by the embodiments of the present application;

[0023] Figure 5 is a flowchart of the image generation method provided by the embodiments of the present application.

[0024] FIG. 1 is a circuit structure schematic diagram of the pixel in the image sensor provided by the embodiments of the present application; FIG. 2 is a flowchart of the image generation method provided by the embodiments of the present application; FIG. 3 is a first module block diagram of the image sensor provided by the embodiments of the present application; FIG. 4 is a second module block diagram of the image sensor provided by the embodiments of the present application; FIG. 5 is a third module block diagram of the image sensor provided by the embodiments of the present application; FIG. 6 is a circuit structure schematic diagram of the pixel in the image sensor provided by the embodiments of the present application; 100, pixel; 110, input circuit; 111, photoelectric conversion unit; 112, first switch unit; 120, floating diffusion node FD; 130, buffer branch; 140, contact point; 150, first readout branch; 160, second readout branch; 170, integration circuit; 180, reset circuit; 190, second switch unit; 200, control circuit; FD, floating diffusion node; C, integration capacitor; PD, photodiode; TG, transfer transistor; TX, control signal of transfer transistor; RST, reset transistor; RS, control signal of reset transistor; SF, follow transistor; SEL, selection transistor; V1, reset power supply; V2, driving power supply. DETAILED DESCRIPTION

[0025] In order to make the personnel in the technical field better understand the scheme of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0026] The following disclosure provides different embodiments or examples to implement different features of the provided subject matter. Specific examples of components and arrangements are described below to make the present disclosure simple. Of course, these are only examples and are not intended to be limiting. For example, in the following description, forming a first feature on or over a second feature can include embodiments in which the first feature is formed directly contacting the second feature, and can also include embodiments in which additional features can be formed between the first feature and the second feature such that the first feature can not directly contact the second feature. In addition, reference numbers and / or letters can be repeatedly used in various examples in the present disclosure. This repetition is for the purpose of simplicity and clarity, and does not essentially indicate the relationship between the various embodiments and / or configurations discussed.

[0027] In addition, the description involving "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that the technical solutions can be realized by those of ordinary skill in the art. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

[0028] The term "and / or" herein is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality, for example, including at least one of A, B and C can mean including any one or more elements selected from the set consisting of A, B and C.

[0029] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0030] In addition, for better illustrating the present application, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand, however, that the application can be practiced without certain of the specific details herein. In some instances, well-known methods, structures, elements, and circuits have not been described in detail in order to avoid obscuring the application.

[0031] At present, in order to take into account the advantages of good imaging quality of APS and the shooting ability of EVS on the moving scene, the two kinds of sensors are fused to realize a composite image sensor capable of outputting APS data and EVS data. However, the inventors have found that most of the composite image sensors cannot realize the compatible output of APS data and EVS data in the same pixel. Even if part of the composite image sensors can output APS data and EVS data on the same pixel, it is necessary to make great changes to the existing mature and stable APS pixel circuit structure, which not only increases the area of each pixel, but also has high implementation difficulty, and is easy to cause the problem of significant reduction of the imaging quality of the fused pixel.

[0032] Based on this, embodiments of this application propose an image sensor, an image generation method, and an optoelectronic device. The image sensor includes a pixel array composed of multiple pixels. Each pixel in the pixel array is configured with an input circuit, a floating diffusion node, a buffer branch, a first readout branch, and a second readout branch. The input circuit is connected to the floating diffusion node and is used to convert incident light into a corresponding charge and output the charge to the floating diffusion node to form a voltage on the floating diffusion node. The buffer branch is connected to the floating diffusion node and is configured with a contact point. The buffer branch is used to buffer the voltage formed on the floating diffusion node so that the voltage is output through the contact point. The contact point is used to connect the first readout branch and the second readout branch. The first readout branch is used to output a corresponding grayscale signal based on the voltage output from the contact point. The second readout branch is used to output a corresponding event signal based on the voltage output from the contact point. This enables the pixels of the image sensor of this application to detect and output different signals. Furthermore, by connecting two different readout branches to the same contact point, this application can achieve the output of different image signals on the same pixel without making significant modifications to the existing pixel circuit structure corresponding to a single image sensor (such as the pixel circuit structure corresponding to APS). This reduces the difficulty of generating images by fusing multiple image sensors, improves the imaging quality of the fused pixels, and enhances stability and reliability.

[0033] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of an image sensor according to an embodiment of the present invention. Figure 1 The image sensor includes a pixel array consisting of multiple pixels 100. Each pixel 100 includes an input circuit 110, a floating diffusion node (FD) 120, a buffer branch 130, a first readout branch 150, and a second readout branch 160. Specifically:

[0034] Input circuit 110 is connected to floating diffusion node 120. Input circuit 110 can be used to convert incident light into corresponding charge and output the charge to floating diffusion node 120 to form a voltage on floating diffusion node 120. Buffer branch 130 is connected to floating diffusion node 120 and is configured with contact point 140. Buffer branch 130 can be used to buffer the voltage formed on floating diffusion node 120 so that the output voltage through contact point 140 follows the voltage formed on floating diffusion node 120. Contact point 140 is used to connect first readout branch 150 and second readout branch 160. First readout branch 150 can be used to output a corresponding grayscale signal according to the voltage output from contact point 140, and second readout branch 160 can be used to output a corresponding event signal according to the voltage output from contact point 140.

[0035] In the embodiment, the input circuit 110 can receive incident light and convert the incident light into corresponding charges. The input circuit 110 can be configured in one pixel of the pixel array, or shared by multiple pixels.

[0036] As shown in Figure 2 , Figure 2 A second module block diagram of the image sensor provided by the embodiment of the present application is shown. In Figure 2 , as an embodiment, the input circuit 110 includes a photoelectric conversion unit 111 and a first switch unit 112. The photoelectric conversion unit 111 receives incident light, and the photons of the incident light excite electrons in the semiconductor in the photoelectric conversion unit 111, i.e., to convert charges (photocharges). When the first switch unit 112 is off, the photoelectric conversion unit 111 can store the charges, such as storing the converted photocharges in the space charge region of the diode of the photoelectric conversion unit 111. When the first switch unit 112 is on, the photoelectric conversion unit 111 transmits the charges to the floating diffusion node 120, and a voltage corresponding to the charges is formed at the floating diffusion node 120.

[0037] In some embodiments, the first readout branch 150 corresponds to an active pixel sensor (APS), and the second readout branch 160 corresponds to an event-based vision sensor (EVS).

[0038] In Figure 2 , as an embodiment, the image sensor further includes an integration circuit 170 and a reset circuit 180, the integration circuit 170 is connected between the floating diffusion node 120 and the ground, and the reset circuit 180 is connected to the floating diffusion node 120. The integration circuit 170 can be used to form an integration voltage based on the charges accumulated at the floating diffusion node 120. The reset circuit 180 can be used to reset the voltage at the floating diffusion node 120 to a first voltage when the first switch unit 112 is off. The buffer branch 130 buffers the first voltage and / or the integration voltage, and outputs the first voltage and / or the integration voltage and / or the buffered first voltage and / or the buffered integration voltage to the first readout branch 150 through the contact point 140. The first readout branch 150 outputs corresponding gray scale signals according to the first voltage and / or the integration voltage and / or the buffered first voltage and / or the buffered integration voltage.

[0039] It can be understood that resetting the voltage at the floating diffusion node 120 to the first voltage actually pulls up the voltage at the floating diffusion node 120, so that when the first switch unit 112 is on, the charges accumulated by the photoelectric conversion unit 111 can be completely transmitted to the floating diffusion node 120.

[0040] It can also be understood that the integration circuit 170 can be a parasitic capacitance of the floating diffusion node 120 to ground. After the floating diffusion node 120 receives the charge accumulated by the photoelectric conversion unit 111, the parasitic capacitance at the floating diffusion node 120 performs charge-to-voltage conversion to obtain a linearly integrated voltage signal.

[0041] In some embodiments, when the first switch unit 112 is off, the reset circuit 180 resets the voltage of the floating diffusion node 120 to a first voltage, and the buffer branch 130 buffers the first voltage, so that the first voltage is output to the contact point 140. The first voltage is transmitted to the first readout branch 150 through the contact point 140. When the reset circuit 180 is off, the first voltage is reset for voltage sampling. When the first switch unit 112 is on, the charge accumulated and stored in the photoelectric conversion unit 111 is transmitted to the floating diffusion node 120, and the charge received by the floating diffusion node 120 is integrated on the integration circuit 170 to form an integrated voltage. The integrated voltage is buffered by the buffer branch 130, and the integrated voltage is output so that the integrated voltage is output to the contact point 140. The integrated voltage is transmitted to the first readout branch 150 through the contact point 140. The first readout branch 150 digitally quantizes the integrated voltage and / or the first voltage and / or the buffered first voltage and / or the buffered integrated voltage, and outputs a corresponding gray scale signal.

[0042] As an example, as shown in FIG. 1, the image sensor further includes a second switch unit 190 connected between the contact point 140 and the first readout branch 150. The second switch unit 190 can be used to gate the path between the first readout branch 150 and the contact point 140. Figure 2

[0043] In this embodiment, by controlling the on and off of the second switch unit 190, it can be determined whether to output a corresponding gray scale signal, so that the image sensor can have different modes. For example, the first readout branch 150 is an APS readout branch, and the second readout branch 160 is an EVS readout branch. By turning on and off the second switch unit 190, the image sensor can be switched between different modes.

[0044] When the second switch unit 190 is on, the path between the first readout branch 150 and the contact point 140 is on. The integrated voltage is output to the contact point 140, and reaches the first readout branch 150 through the second switch unit 190. The first readout branch 150 digitally quantizes the integrated voltage and the first voltage, and outputs a corresponding gray scale signal. When the second switch unit 190 is off, the voltage of the floating diffusion node 120 reaches the second readout branch 160 through the buffer branch 130 and the contact point 140, and the second readout branch 160 generates a corresponding event signal.​

[0045] As an embodiment, the reset circuit 180 is further configured to output a second voltage, the second voltage and the photo current corresponding to the electric charge form a logarithmic voltage at the floating diffusion node 120. The buffer branch 130 is further configured to buffer the second voltage and / or the logarithmic voltage, and output the second voltage and / or the logarithmic voltage and / or the buffered second voltage and / or the buffered logarithmic voltage to the second readout branch 160 through the contact point 140. The second readout branch 160 outputs a corresponding event signal according to the second voltage and / or the logarithmic voltage and / or the buffered second voltage and / or the buffered logarithmic voltage.

[0046] In the embodiment, the event signal is used to represent the change of the incident light intensity. By comparing the size of the adjacent two logarithmic voltages output by the second readout branch 160, the change of the current incident light intensity can be determined. For example, when the difference between the current sampled logarithmic voltage and the previous logarithmic voltage is higher than a preset threshold, it can be determined that the light incident to the image sensor is stronger than the light that generates the previous logarithmic voltage. When the difference between the current sampled logarithmic voltage and the previous logarithmic voltage is less than the preset threshold, it indicates that the light incident to the image sensor is weaker than the light that generates the previous logarithmic voltage.

[0047] Optionally, the voltage compared with the current logarithmic voltage can also be a preset voltage.

[0048] In the second readout branch 160, as in the EVS readout circuit (EVS backend circuit), 2bit data such as on and off can be defined to represent the relationship between the current logarithmic voltage and the previous logarithmic voltage. When the difference between the current sampled logarithmic voltage and the previous logarithmic voltage is higher than a preset threshold, it is defined as on in the second readout branch 160; when the difference between the current sampled logarithmic voltage and the previous logarithmic voltage is less than the preset threshold, it is defined as off in the second readout branch 160; and when the difference between the adjacent two logarithmic voltages is between the preset threshold, it is defined as no event in the second readout branch 160.

[0049] Exemplarily, take on represented by 10, off represented by 01, and no event represented by 00 in the second readout branch 160 as an example. When the second readout branch 160 outputs 10, it indicates that the light currently incident to the image sensor is stronger than the light that generates the logarithmic voltage in the previous time; when the second readout branch 160 outputs 01, it indicates that the light currently incident to the image sensor is weaker than the light that generates the logarithmic voltage in the previous time; when the second readout branch 160 outputs 00, it indicates that the light intensity has not changed; and when the second readout branch 160 outputs 11, it indicates abnormal data. Among them, when the second readout branch 160 outputs 10 and 01, it is determined that an event occurs, and the other two cases are determined as no event occurs. After the event occurs, the logarithmic voltage of this sampling is stored on a capacitor, and the next sampling is compared with the stored logarithmic voltage.

[0050] In some embodiments, the first switch unit 112 is turned on, and a reference voltage, i.e., the second voltage, is provided by the reset circuit 180. The incident light is photoelectrically converted by the photoelectric conversion unit 111 to obtain a corresponding photoelectric current. When the photoelectric current passes through the first switch unit 112 and the reset circuit 180, a voltage in logarithmic relationship with the photoelectric current, i.e., a logarithmic voltage, is generated on the floating diffusion node 120. The logarithmic voltage is buffered by the buffer branch 130, followed by being output to the contact point 140, and then reaches the corresponding second readout branch 160 through the contact point 140. After the logarithmic voltage is sampled by the second readout branch 160, it is compared with the second voltage. If the difference exceeds a preset threshold, a corresponding event signal is output, and the voltage is recorded as a new reference value.

[0051] As shown in Figure 3 , Figure 3 is a third module block diagram of the image sensor provided by the embodiments of the present application. In Figure 3 , as an embodiment, the image sensor further includes a control circuit 200, which is connected with the first switch unit 112, the reset circuit 180, the first readout branch 150, the second readout branch 160, and the second switch unit 190, respectively. By connecting the control circuit 200 with the first switch unit 112, the on-off of the first switch unit 112 can be controlled. By connecting the control circuit 200 with the reset circuit 180, the output voltage of the reset circuit 180 can be adjusted, and the reset circuit 180 can be controlled to output the first voltage and / or the second voltage. By connecting the control circuit 200 with the first readout branch 150 and the second readout branch 160, the corresponding image can be generated according to the gray scale signal and the event signal output by the unit pixel. By connecting the control circuit 200 with the second switch unit 190, the on-off of the second switch unit 190 can be controlled.

[0052] Figure 4The circuit structure of the pixel 100 in the image sensor provided by some embodiments of the present application is shown, and subsequent embodiments are described with reference to the same Figure 4 The circuit structure of the pixel 100 in the image sensor provided by some embodiments of the present application is shown, and subsequent embodiments are described with reference to the same

[0053] In some embodiments, the photoelectric conversion unit 111 can include a photodiode PD, a phototransistor, a clamping photodiode, or other devices that can achieve photoelectric conversion function in the art.

[0054] Exemplarily, the photoelectric conversion unit 111 includes a photodiode PD, the anode of which is grounded, and the cathode of which is connected to one end of the first switch unit 112.

[0055] Optionally, in some embodiments, the first switch unit 112 includes a transfer transistor TG, the first end of which is connected to the photoelectric conversion unit 111, the second end of which is connected to the control circuit 200 (the control signal of the transfer transistor is TX), and the third end of which is connected to the floating diffusion node FD. In some embodiments, the transfer transistor TG can be turned on or turned off according to the timing requirement under the control of the control circuit 200, and only when the transfer transistor TG is turned on, the floating diffusion node FD can receive the photocharge accumulated / generated by the photoelectric conversion unit 111 through the transfer transistor TG.

[0056] Optionally, in some embodiments, the reset circuit 180 includes a reset power supply V1 and a reset transistor RST, the drain of which is connected to the reset power supply V1, the gate of which is connected to the control circuit 200 (the control signal of the reset transistor is RS), and the source of which is connected to the floating diffusion node FD. In some embodiments, such as in the scenario that the image sensor single pixel 100 outputs gray scale data (such as APS data), the reset transistor RST can be turned on under the control of the control circuit 200, and only when the reset transistor RST is turned on, the reset power supply V1 can reset the voltage of the floating diffusion node FD to its own voltage.

[0057] Optionally, in some embodiments, the buffer branch 130 includes a follower transistor SF and a driving power supply V2, the gate of which is connected to the floating diffusion node FD, the drain of which is connected to the driving power supply V2, and the source of which is connected to the contact point 140. The follower transistor SF is equivalent to a source follower amplifier, which can buffer the potential of the floating diffusion node FD, so as to output the voltage to the contact point 140 (the source of the follower transistor SF).

[0058] Optionally, in some embodiments, the second switch unit 190 includes a selection transistor SEL, the drain of the selection transistor SEL is connected to the buffer branch 130, the gate of the selection transistor SEL is connected to the control circuit 200 (the control signal is READ), and the source of the selection transistor SEL is used to connect the first readout branch 150. In some embodiments, the selection transistor SEL can receive the voltage output by the buffer branch 130, and be turned on or turned off according to the timing requirements under the control of the control circuit 200, and only when the selection transistor SEL is turned on can the first readout branch 150 receive the voltage, and then the first readout branch 150 can output the corresponding gray scale signal according to the received voltage.

[0059] Optionally, in some embodiments, the second readout branch 160 connected by the contact point 140 is arranged on a wafer layer different from the wafer layer where the pixel 100 is located, the bonding structure is led out at the contact point 140 to perform bonding of the two wafer layers, and the 3D stacking process of the double-layer wafer is adopted, so that the photoelectric sensing part of the image sensor of the embodiment of the application is separated from the readout and processing circuit, which can greatly reduce the influence of noise crosstalk and temperature imbalance.

[0060] Further, the two wafer layers described above are bonded based on the hybrid bonding (HBM) technology (HBM), and the two wafer layers are stacked by the 3D stacking process of the double-layer wafer.

[0061] At the same time, the HBM adopted by the embodiment of the application can shorten the transmission distance of the signal from the pixel 100 to the image processing circuit, thereby improving the readout speed, and has more advantages in high-speed photography and video applications. In addition, the HBM can provide higher mechanical strength and better long-term reliability than traditional bonding technology, which is very important for improving the durability of the image sensor.

[0062] It should be noted that in the above embodiments, the setting form of the photoelectric conversion unit 111, the control circuit 200, the first readout branch 150, and the second readout branch 160 can be that one is arranged in each pixel 100 in the pixel array, or only one is arranged, so that all the pixels 100 in the pixel array share the same one, or a plurality of ones are arranged, so that all the pixels 100 in the same array unit in the pixel array share the same one. The pixel array can be divided into a plurality of array units, and each array unit includes a preset number of pixels 100. For example, each column of pixels 100 in the pixel array constitutes an array unit, or each row of pixels 100 in the pixel array constitutes an array unit. As for the exposure mode of the image sensor, global exposure or rolling shutter exposure can be adopted, and the timing of turning on / off of the transistors in the pixels 100 is different in different exposure modes, which can be set according to actual needs, and details are not described herein.

[0063] In summary, the image sensor provided by the embodiment of the present application only needs to set a contact point 140 at the connection between the buffer branch 130 and the second switch unit 190 in the existing APS pixel circuit structure, i.e., the 4T Pinned Photodiode (PPD) pixel structure, to connect the EVS readout circuit, without obviously changing the APS pixel circuit structure, so that the same pixel has the ability to output APS data and EVS data, which reduces the difficulty of implementation and improves the stability and reliability.

[0064] More importantly, almost all the pixels in the embodiment of the present application are output by the follow transistor SF, whether it is voltage output or charge output, the pixel structure of the embodiment of the present application is applicable, and the existing APS pixel circuit structure described above, whether it is 4T, 5T, 6T, or 8T, the embodiment of the present application can make a single pixel have the ability to output at least two kinds of image sensor signals through the above-mentioned setting of the contact point, which has strong universality.

[0065] Meanwhile, based on the design idea of the above-mentioned image sensor, the present application further provides an image generation method applied to the above-mentioned image sensor. Since the technical principles of the method embodiment are similar to those of the above-mentioned device embodiment, the same technical details will not be described repeatedly.

[0066] In detail, as shown in Figure 5 In an optional embodiment of the present application, the image generation method includes:

[0067] S401, acquiring incident light of the image sensor;

[0068] S402, generating an event signal and a gray scale signal according to the incident light, the event signal and the gray scale signal being used to generate an image.

[0069] In an embodiment of the present application, the image generation method further comprises:

[0070] converting incident light into corresponding electric charges by a photoelectric conversion unit of an image sensor, transferring the electric charges to a floating diffusion node of the image sensor when a first switch unit of the image sensor is turned on, and storing the electric charges when the first switch unit is turned off.

[0071] In an embodiment of the present application, the generating a gray scale signal according to the incident light comprises:

[0072] forming an integration voltage based on the electric charges accumulated on the floating diffusion node by an integration circuit of the image sensor, the electric charges being converted from the incident light;

[0073] resetting the voltage of the floating diffusion node to a first voltage by a reset circuit of the image sensor when the first switch unit is turned off;

[0074] buffering the first voltage and / or the integration voltage by a buffer branch of the image sensor, and outputting the first voltage and / or the integration voltage to a first readout branch through the contact point;

[0075] outputting a corresponding gray scale signal according to the first voltage and / or the integration voltage by the first readout branch of the image sensor.

[0076] In an embodiment of the present application, the image generation method further comprises:

[0077] selecting a path of the first readout branch and the contact point by a second switch unit of the image sensor.

[0078] In an embodiment of the present application, the generating an event signal according to the incident light comprises:

[0079] outputting a second voltage by a reset circuit of the image sensor, the second voltage and a photoelectric current corresponding to the electric charges forming a logarithmic voltage at the floating diffusion node, the photoelectric current being converted from the incident light;

[0080] buffering the second voltage and / or the logarithmic voltage by a buffer branch of the image sensor, and outputting the second voltage and / or the logarithmic voltage to a second readout branch through the contact point;

[0081] outputting a corresponding event signal according to the second voltage and / or the logarithmic voltage by the second readout branch of the image sensor.

[0082] In one embodiment of this application, the above-described image generation method further includes:

[0083] The control circuit of the image sensor controls the on and off states of the first switching unit.

[0084] In one embodiment of this application, the above-described image generation method further includes:

[0085] The control circuit of the image sensor controls the on and off states of the second switching unit.

[0086] In one embodiment of this application, the above-described image generation method further includes:

[0087] The image sensor's control circuit controls the reset circuit to output the first voltage and / or the second voltage.

[0088] In one embodiment of this application, the above-described image generation method further includes:

[0089] An image is generated based on the event signal and the grayscale signal through the control circuit of the image sensor.

[0090] Understandably, in Figure 5 In the embodiments shown, due to the improvements and specific implementation methods related to this application, [the following has been implemented]. Figures 1 to 4 The corresponding embodiments provide detailed explanations, and in specific implementations, can be... Figures 1 to 4 The content of the corresponding embodiments, combined with Figures 1 to 4 The embodiments described herein are used to implement the technical solution of this application, and therefore will not be repeated here.

[0091] It should be noted that the image generation method provided in the above embodiments and the image sensor provided in the above embodiments belong to the same concept. The specific ways in which each module and unit performs its operations have been described in detail in the method embodiments and will not be repeated here. In practical applications, the image processing device provided in the above embodiments can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above, and no limitation is made here.

[0092] In addition, the present invention also provides an optoelectronic device, which includes the image sensor described above.

[0093] The steps of a method or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM, flash memory, ROM, electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD ROM, or any other form of storage medium known in the art. The storage medium can be loaded into the computer or other programmable device to cause the computer or other programmable device to perform a series of instructions to produce the steps described that one of ordinary skill in the art would recognize as producing the functions or operations described.

[0094] In the embodiments described above, the functions performed can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, the functions can be embodied in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed by a computer, the computer instructions cause the computer to perform the steps described in whole or in part. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, such as from a website, a computer, a server, or a data center to another website, computer, server, or data center via a wired (such as a coaxial cable, an optical fiber, a digital subscriber line) or wireless (such as infrared, wireless, microwave, etc.) means. The computer readable storage medium can be any available medium or a set of media that is accessible by a computer or a data storage device such as a server, data center, etc. that includes one or more of the available media. The available media can be a magnetic medium (such as a floppy diskette, a hard disk drive, a magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a Solid State Disk), etc.

[0095] Although embodiments of the present application have been shown and described, it would be recognized by those of ordinary skill in the art that various changes, modifications, substitutions, and alterations can be made hereto without departing from the spirit and scope of the present application. The scope of the present application is limited only by the claims and the equivalents thereof.

Claims

1. An image sensor comprising a pixel array of a plurality of pixels, characterized in that, The pixel comprises an input circuit, a floating diffusion node, a buffer branch, a first readout branch and a second readout branch; The input circuit is connected with the floating diffusion node, and is configured to convert incident light into corresponding electric charges and output the electric charges to the floating diffusion node to form a voltage on the floating diffusion node; The buffer branch is connected with the floating diffusion node, and is configured with a contact point, and is configured to perform potential buffering on the voltage formed on the floating diffusion node to output the voltage through the contact point; The contact point is configured to connect the first readout branch and the second readout branch; The first readout branch is configured to output a corresponding gray scale signal according to the voltage output by the contact point; The second readout branch is configured to output a corresponding event signal according to the voltage output by the contact point.

2. The image sensor of claim 1, wherein, The input circuit comprises a photoelectric conversion unit and a first switch unit; The photoelectric conversion unit is configured to convert incident light into corresponding electric charges, and transmit the electric charges to the floating diffusion node when the first switch unit is turned on, and store the electric charges when the first switch unit is turned off.

3. The image sensor of claim 2, wherein, Further comprising: An integration circuit connected between the floating diffusion node and the ground, and configured to form an integration voltage based on the electric charges accumulated on the floating diffusion node; A reset circuit connected with the floating diffusion node, and configured to reset the voltage of the floating diffusion node to a first voltage when the first switch unit is turned off; The buffer branch is configured to buffer the first voltage and / or the integration voltage, and output the first voltage and / or the integration voltage to the first readout branch through the contact point; The first readout branch is configured to output a corresponding gray scale signal according to the first voltage and / or the integration voltage.

4. The image sensor of claim 3, wherein, Further comprising: A second switch unit connected between the contact point and the first readout branch, and configured to select the pass of the first readout branch and the contact point.

5. The image sensor of claim 4, wherein, The reset circuit is further configured to output a second voltage, and a photoelectric current corresponding to the electric charges forms a logarithmic voltage on the floating diffusion node; The buffer branch is further configured to buffer the second voltage and / or the logarithmic voltage, and output the second voltage and / or the logarithmic voltage to the second readout branch through the contact point; The second readout branch is configured to output a corresponding event signal according to the second voltage and / or the logarithmic voltage.

6. The image sensor of claim 2, wherein, The image sensor further comprises a control circuit connected with the first switch unit, and the control circuit is configured to control the turn-on and turn-off of the first switch unit.

7. The image sensor of claim 4, wherein, The image sensor further comprises a control circuit connected with the second switch unit, and the control circuit is configured to control the turn-on and turn-off of the second switch unit.

8. The image sensor of claim 5, wherein, The image sensor further comprises a control circuit connected with the reset circuit, and the control circuit is configured to control the reset circuit to output the first voltage and / or the second voltage.

9. The image sensor according to any one of claims 1 to 5, characterized by, The image sensor further comprises a control circuit for generating an image from the event signals and the gray scale signals.

10. An image generation method characterized by, The method is applied to the image sensor of claim 1, the method comprising: acquiring incident light of the image sensor; generating event signals and gray scale signals from the incident light, the event signals and the gray scale signals being used to generate an image.

11. An optoelectronic device, characterized by The optoelectronic device comprises the image sensor of any one of claims 1 to 9.

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