Image signal reading circuit, image signal reading method, and electronic device

Abstract

The invention discloses an image signal reading circuit, an image signal reading method and electronic equipment, and belongs to the technical field of electronics. The readout circuit comprises a voltage regulation module, wherein the first end of the voltage regulation module is connected with the output ends of at least two pixel units; the reset analysis module is connected with the second end of the voltage regulation module, and is used for performing reset analysis on the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the reset voltage mean value of the pixel in the read-out area is greater than a reference threshold value; controlling the voltage regulation module to regulate the voltage output to the output end of the pixel unit; the reference voltage module is used for outputting reference voltage; the switch module is used for controlling the on-off of the reference voltage module or the pixel unit; and the measuring module is used for measuring the output voltage of the pixel unit.

Description

Technical Field

[0001] The present application belongs to the field of electronic technology, and specifically relates to an image signal readout circuit, an image signal reading method and an electronic device. Background Art

[0002] Mobile phones and other electronic devices usually need to perform noise reduction processing to ensure image quality during the shooting process. The common method in the industry is to use noise reduction algorithms at the back end of the image processing chip (Image Signal Processor, ISP), such as multi-frame noise reduction, wavelet noise reduction, median filtering, Gaussian filtering, etc., but the noise reduction effect is not ideal. In order to improve the noise reduction effect, artificial intelligence (AI) noise reduction technology is proposed, that is, noise reduction is performed in the raw domain of the front end. However, the premise of AI noise reduction is that the background noise needs to be accurately calculated. The background noise state of the CMOS image sensor (CIS) changes with factors such as the camera startup time, ambient temperature, and mobile phone temperature. This makes it difficult for AI noise reduction to obtain accurate background noise, resulting in poor noise reduction effect and affecting image quality. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide an image signal readout circuit, an image signal reading method and an electronic device, which can ensure that the pixel outputs a stable photoelectric signal, thereby ensuring the acquisition of a high-quality image with low noise and high signal-to-noise ratio.

[0004] In a first aspect, an embodiment of the present application provides an image signal readout circuit, comprising:

[0005] A voltage regulating module, wherein a first terminal of the voltage regulating module is connected to output terminals of at least two pixel units;

[0006] a reset analysis module, the reset analysis module being connected to the second end of the voltage regulation module, and the reset analysis module being used to control the voltage regulation module to regulate the voltage output to the output end of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the average reset voltage value of the pixels in the readout area is greater than a reference threshold; wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1;

[0007] A reference voltage module, used for outputting a reference voltage;

[0008] A switch module, wherein a first switch end of the switch module is connected to an output end of the pixel unit, a second switch end of the switch module is connected to the reference voltage module, and the switch module is used to control the on / off of the reference voltage module or the pixel unit;

[0009] A measuring module is connected to the fixed end of the switch module, and is used to measure the output voltage of the pixel unit.

[0010] In a second aspect, an embodiment of the present application provides an image sensor, comprising at least two pixel units and the readout circuit described in the first aspect, wherein the output end of the pixel unit is connected to the first end of the voltage regulation module in the readout circuit; and the pixel unit is used to output a reset voltage signal or a pixel voltage signal.

[0011] In a third aspect, an embodiment of the present application provides a camera module, comprising the image sensor described in the second aspect.

[0012] In a fourth aspect, an embodiment of the present application provides an electronic device, comprising the camera module described in the third aspect.

[0013] In a fifth aspect, an embodiment of the present application provides an image signal reading method, which is performed by the electronic device according to the fourth aspect, and the method includes:

[0014] In the case where the switch module switches from the reference voltage module to the pixel unit, the reset analysis module obtains a first reset voltage value output by the pixel unit, and reads a reset voltage value of a pixel in a readout area, wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, where n is an integer greater than 1;

[0015] The reset analysis module determines a reset voltage average of pixels in the readout area according to reset voltage values ​​of pixels in the readout area;

[0016] The reset analysis module controls the voltage regulation module to regulate the voltage output to the output terminal of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the reset voltage average value exceeds a reference threshold;

[0017] The measuring module measures the voltage outputted by the output terminal of the pixel unit.

[0018] In a sixth aspect, an embodiment of the present application provides an electronic device, comprising a processor and a memory, wherein the memory stores programs or instructions that can be run on the processor, and when the programs or instructions are executed by the processor, the steps of the method described in the fourth aspect are implemented.

[0019] In a seventh aspect, an embodiment of the present application provides a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the method described in the fourth aspect are implemented.

[0020] In an eighth aspect, an embodiment of the present application provides a chip, comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a program or instruction to implement the method described in the fourth aspect.

[0021] In a ninth aspect, an embodiment of the present application provides a computer program product, which is stored in a storage medium and is executed by at least one processor to implement the method described in the fourth aspect.

[0022] In an embodiment of the present application, an image signal readout circuit includes: a voltage regulating module, a first end of which is connected to output ends of at least two pixel units; a reset analysis module, which is connected to a second end of the voltage regulating module, and is used to control the voltage regulating module to adjust the voltage output to the output end of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the average reset voltage of the pixels in the readout area is greater than a reference threshold; wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1; a reference voltage module, which is used to output a reference voltage; a switch module, a first switching end of the switch module is connected to the output end of the pixel unit, and a second switching end of the switch module is connected to the reference voltage module, and the switch module is used to control the on and off of the reference voltage module or the pixel unit; a measurement module, which is connected to a fixed end of the switch module, and is used to measure the output voltage of the pixel unit. In this way, by designing an improved readout circuit, the real-time reset voltage of the pixel is compared with the average reset voltage of the surrounding pixels, and the pixel reset voltage is adjusted when the difference is large, thereby ensuring that the pixel outputs a stable photoelectric signal, thereby ensuring the acquisition of high-quality images with low noise and high signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a structural diagram of an image signal readout circuit provided by some embodiments of the present application;

[0024] Figure 2 is a structural diagram of a pixel circuit provided by some embodiments of the present application;

[0025] Figure 3 is a working principle diagram of a pixel circuit provided by some embodiments of the present application;

[0026] Figure 4 is a working principle diagram of an image signal readout circuit provided by some embodiments of the present application;

[0027] Figure 5is a flowchart of an image signal reading method provided by some embodiments of the present application;

[0028] Figure 6 is a structural diagram of an electronic device provided by some embodiments of the present application;

[0029] Figure 7 This is a hardware structure diagram of an electronic device provided in some embodiments of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0031] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0032] In order to make the embodiments of the present application clearer, the relevant technical knowledge involved in the embodiments of the present application is first introduced as follows:

[0033] The camera module of mobile phones and other electronic devices consists of multiple parts such as lens, focus motor, complementary metal oxide semiconductor (CMOS) photosensor, analog-to-digital converter (ADC), image processor ISP, memory, etc. The general principle of shooting is that when the camera is aimed at the scene to take a picture, the light first passes through the lens and shines on the sensor. The sensor converts the light signal into an analog signal, and then converts it into a digital signal through the analog-to-digital converter. Finally, the image processor ISP generates image information and stores it on the mobile phone.

[0034] The camera sensor is the core of the camera and the most critical technology in the camera. There are two types of sensors, one is the widely used charge-coupled device (CCD), and the other is the CMOS device. Compared with traditional cameras, traditional cameras use "film" as the carrier of their information recording, while the "film" of digital cameras is its imaging photosensitive element. The photosensitive element is the "film" of digital cameras that does not need to be replaced and is integrated with the camera.

[0035] Currently, the mainstream device is CMOS, which, like CCD, is a semiconductor that can record light changes in digital cameras. The general working process of CMOS is to sense light signals through a large number of photodiodes (pixels) and convert them into electrical signals, which are then passed through amplification circuits and AD conversion circuits to form a digital signal matrix (i.e., image), which is then compressed and stored after ISP processing.

[0036] The camera lens is the most important part of the camera, because its quality directly affects the quality of the image taken. Lenses can be divided into two categories: zoom and fixed-focus. Among them, zoom lenses are lenses with variable focal length and variable viewing angle, that is, lenses that can be pushed and pulled; fixed-focus lenses are lenses with fixed focal lengths that cannot be changed and have only one focal length, or only one viewing angle.

[0037] CMOS Camera Module is the mainstream camera module currently used in mobile phones. It is mainly composed of lens, voice coil motor, infrared filter, image sensor (CMOS), digital signal processor (DSP) and flexible printed circuit (FPC).

[0038] The lens group (Lens) is used for gathering and focusing. The lens is wrapped and fixed by the voice coil motor, and the upper and lower ends of the voice coil motor are connected to the shrapnel. When focusing, the motor generates electromagnetic force by powering on, and this force is ultimately balanced with the elastic force of the shrapnel. The position of the motor can be controlled by the amount of power, thereby pushing the motor and the lens to the focusing position. The scene light that converges into the module is projected onto the IR filter. The function of the IR filter is to filter out unnecessary light projected onto the sensor, preventing the sensor from generating false colors / ripples, so as to improve its effective resolution and color reproduction. The light that passes through the IR filter can be sensed by the pixels on the image sensor and converted into photoelectricity.

[0039] Currently, the cameras of mobile electronic devices such as mobile phones have more and more photo-taking functions, and consumers have higher and higher requirements for the photo-taking experience of mobile phones, which poses a huge challenge to the functions, performance and effects of mobile phone cameras.

[0040] The purpose of this application is to design a new image signal readout circuit and image sensor. The image sensor includes a conventional pixel unit and is equipped with a new image signal readout circuit with noise reduction function, which allows AI noise reduction to accurately obtain the background noise state of the CIS in real time and improve the AI ​​noise reduction effect. Even in extreme environments, each pixel can output a stable photoelectric signal to obtain high-quality images with low noise and high signal-to-noise ratio. At the same time, the sensor fixed pattern noise can be eliminated to improve the final image quality.

[0041] The image signal readout circuit and the image signal reading method provided in the embodiments of the present application are described in detail below through specific embodiments and their application scenarios in conjunction with the accompanying drawings.

[0042] See also Figure 1 , Figure 1 The structure diagram of the image signal readout circuit provided in the embodiment of the present application is as follows: Figure 1 As shown, the image signal readout circuit includes:

[0043] A voltage regulating module 11, wherein a first terminal of the voltage regulating module 11 is connected to output terminals of at least two pixel units 20;

[0044] A reset analysis module 12, the reset analysis module 12 is connected to the second end of the voltage regulation module 11, and the reset analysis module 12 is used to control the voltage regulation module 11 to adjust the voltage output to the output end of the pixel unit 20 when the absolute value of the difference between the first reset voltage value output by the pixel unit 20 and the average reset voltage value of the pixels in the readout area exceeds the reference threshold value; wherein the readout area is a square area centered on the pixel where the pixel unit 20 is located, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1;

[0045] A reference voltage module 13, used for outputting a reference voltage;

[0046] A switch module 14, wherein a first switch end of the switch module 14 is connected to an output end of the pixel unit 20, and a second switch end of the switch module 14 is connected to the reference voltage module 13, and the switch module 14 is used to control the on / off of the reference voltage module 13 or the pixel unit 20;

[0047] The measuring module 15 is connected to the fixed end of the switch module 14 , and is used to measure the output voltage of the pixel unit 20 .

[0048] In the embodiment of the present application, the image information readout circuit is an improved circuit for reading the output voltage signal of each pixel unit in the image sensor.

[0049] The pixel unit 20 of the embodiment of the present application may refer to a pixel circuit in an image sensor, and the output of each pixel unit may be read out by the readout circuit, and the pixel unit 20 may output a reset voltage signal Reset or a pixel voltage signal Pixel. The pixel circuit structure may be as follows Figure 2 The specific introduction is as follows:

[0050] This pixel structure is called a pinned photodiode pixel (PPD) pixel structure. The PPD pixel includes a photosensitive area of ​​a PD, i.e., a photodiode, and four transistors (a reset transistor RST, a floating switch TG, a row selector Rsel, and a signal amplifier SF), so it is also called a 4T pixel structure. In addition, each PD is also equipped with a parasitic capacitor FD to store the photogenerated electrons in the PD. The PPD structure pixel allows the introduction of a correlated double sampling (CDS) circuit, eliminating the kTC noise introduced by the reset, the 1 / f noise introduced by the transistor, and the offset noise. The pixel structure works as follows:

[0051] First, reset is performed by activating RST and TG to clear the residual electrons in PD and FD.

[0052] Secondly, PD starts to be sensitive to light. Specifically, when RST and TG are disconnected, the pixel starts to be sensitive to light. The electron-hole pairs generated by light irradiation will separate due to the existence of the PD electric field. The electrons move to the n-region and the holes move to the p-region.

[0053] Next, the reset voltage is read out. Specifically, the substrate voltage signal of the FD is output to the readout circuit through SF (source follower) and Rsel (row selector) to be quantized into a digital value V1.

[0054] Then the charge transfer is performed. Specifically, after the PD is exposed to light for a specified time, the TG is activated to completely transfer the charge from the PD to the FD for reading. The mechanism here is similar to the charge transfer in the CCD. The voltage of the FD drops due to the influx of electrons.

[0055] Finally, the signal level is read out, that is, the voltage signal of FD is output to the readout circuit through SF and Rsel and quantized into a digital value V2, then V2-V1=Vout, which is the digital value of the photosensitive signal.

[0056] Often in extreme environments, image sensors work very unstably and pixel outputs are prone to jumps. For example, in a high-temperature environment, after a camera is turned on for a period of time, the CIS will continue to accumulate heat, causing temperature drift in the semiconductor device PD and transistors, and unstable operation. Or in a night scene environment, the light is very weak, and the sensor is often in long exposure mode. When the exposure is too long, the pixel operation will also be very unstable. At this time, the output value of the pixel will jump, resulting in poor consistency of the entire picture, that is, the noise will worsen, and the difference between multiple frames will become larger, resulting in snowflake noise. If the back-end ISP processing adds a high-multiple digital gain, this phenomenon will be aggravated.

[0057] The production principle is as follows Figure 3 As shown, the process is as follows:

[0058] exist Figure 2 During the operation of the pixel circuit shown, the reset signal output by the pixel is first measured by the readout circuit, that is, the time t1 for the reference voltage to drop to the reset voltage is measured to form a digital value D1.

[0059] Then the electrical signal in PD is transferred to FD, and the reference voltage in the readout circuit is reset. The image signal + Reset signal output by the pixel is measured again to obtain the digital value D2.

[0060] D2-D1=D_signal, that is, pure image signal. This method is called correlated double sampling, which can effectively eliminate the interference of dark current and stray signals on the image signal.

[0061] However, in extreme environments, such as the high temperature and long exposure conditions mentioned above, the pixel works unstably, causing the Reset signal to fluctuate greatly, which in turn causes D1 to be inaccurate. Even if the light signal is very stable, the D_signal we obtain will be unstable.

[0062] For the above phenomenon, the present application embodiment proposes an improved image signal readout circuit such as Figure 1 As shown:

[0063] Among them, the reset analysis module 12 (also called Reset Analysis mode, RSM for short) and the voltage regulation module 11 are the core modules of the readout circuit, which are mainly used to adjust and correct the Reset voltage with large fluctuations output by the pixel unit 20 under shooting environments such as high temperature and long exposure.

[0064] Specifically, the reset analysis module 12 can monitor the Reset voltage of each pixel unit 20 in real time, and can record the Reset voltage data of several pixels around the pixel where the currently monitored pixel unit 20 is located, such as the Reset voltage data of 16×16 pixels centered on the pixel. That is to say, in some embodiments, the readout area can be a rectangular area with a side length of 16 pixels centered on the pixel where the currently read pixel unit is located.

[0065] And the reset analysis module 12 can compare the Reset voltage of the currently monitored pixel with the average voltage of the Reset voltage data of the 16×16 pixels around it to determine whether the stability of the Reset voltage of the current pixel is normal, that is, whether it is too different from the average Reset voltage of the surrounding pixels. For example, if it exceeds ±5%, it is considered that the stability of the Reset voltage of the current pixel is abnormal. If it is abnormal, the Reset voltage of the current pixel is adjusted by the voltage adjustment module 11 to return it to a normal state, that is, a state that is basically consistent with the average Reset voltage of the surrounding pixels. Finally, the measurement module 15 measures the adjusted Reset voltage of the current pixel to obtain a relatively stable D1 value.

[0066] Optionally, the measuring module 15 includes an integrator, a comparator, an AND gate and a counter connected in series in sequence.

[0067] like Figure 1 As shown, the resistor R and the capacitor C in the integrator are the integration constants of the integration circuit. The integrator is used to integrate the output voltage of the pixel unit 20 or the reference voltage Vref provided by the reference voltage module 13. The integrator output voltage Uc is output to the comparator. The comparator is used to compare Uc with the ground (0V) and output Uo to the AND gate and pulse counter at the back end. When the voltage of the integrator is the same as Vref, Uc is 0, then the polarity of Uo changes, the counter stops counting and outputs the digital value D. In this way, the output voltage signal of the pixel unit 20 can be measured by simple circuit devices.

[0068] The reference voltage module 13 is used to provide a reference voltage Vref for the integration circuit, which can be output by a ramp voltage generator. The switch module 14 can be a controllable switch S1, which is used for the operation of the double integration process.

[0069] The reset analysis module 12 may include a memory unit and a comparison control unit. The memory unit records the reset voltage of the pixels surrounding each pixel. The comparison control unit compares the reset voltage of the pixel with the average reset voltage of the surrounding pixels, and outputs a corresponding control signal to the voltage regulation module 11 according to the comparison result.

[0070] The voltage regulating module 11 may be a regulating unit including different regulating tendencies, such as respectively increasing and decreasing the output voltage of the output terminal of the pixel unit 20 , which may be implemented by a switch device or a voltage divider module.

[0071] Optionally, the voltage regulating module 11 includes a first voltage regulating unit and a second voltage regulating unit, wherein a first end of the first voltage regulating unit is connected to an output end of the pixel unit 20, a second end of the first voltage regulating unit is connected to the reset analysis module 12, a first end of the second voltage regulating unit is connected to an output end of the pixel unit 20, and a second end of the second voltage regulating unit is connected to the reset analysis module 12;

[0072] The reset analysis module 12 is used for:

[0073] When the absolute value of the difference between the first reset voltage value and the reset voltage average value exceeds a reference threshold value and the first reset voltage value is less than the reset voltage average value, the first voltage regulating unit is controlled to be turned on to output a first voltage to an output terminal of the pixel unit 20, wherein the first voltage is the reset voltage average value;

[0074] When the absolute value of the difference between the first reset voltage value and the reset voltage average exceeds the reference threshold, and the first reset voltage value is greater than the reset voltage average, the second voltage adjustment unit is controlled to be turned on to output a second voltage to the output end of the pixel unit 20, wherein the second voltage is less than the first reset voltage value.

[0075] In some embodiments, two voltage adjustment units can be used to deal with the situations where the Reset voltage of the current pixel is too large or too small, respectively. Specifically, when the Reset voltage of the currently monitored pixel exceeds the reference threshold of the mean Reset voltage of the surrounding pixels, such as exceeding ±5% of the mean Reset voltage of the surrounding pixels, the size of the Reset voltage of the current pixel and the mean Reset voltage of the surrounding pixels can be further determined.

[0076] When the Reset voltage of the current pixel is less than the average Reset voltage of the surrounding pixels, the first voltage regulating unit is controlled to be turned on, the average Reset voltage is input to the first voltage regulating unit, and then the average Reset voltage is connected to the output end of the pixel unit 20 through the first voltage regulating unit.

[0077] When the Reset voltage of the current pixel is greater than the average Reset voltage of the surrounding pixels, the second voltage regulating unit is controlled to be turned on, and the Reset voltage of the current pixel is divided by the second voltage regulating unit and then connected to the output end of the pixel unit 20; specifically, the voltage division scheme can be determined according to the difference between the Reset voltage of the current pixel and the average Reset voltage to ensure that the Reset voltage of the current pixel is reduced to a value similar to the average Reset voltage.

[0078] In this way, the Reset voltage of the current pixel can be appropriately adjusted through different voltage adjustment units according to the deviation of the Reset voltage of the current pixel relative to the average Reset voltage of the surrounding pixels, thereby ensuring the stability of the Reset voltage output by the current pixel, and this scheme can ensure the accuracy of the pixel Reset voltage adjustment.

[0079] Further, the first voltage regulating unit includes a first transistor T1, and the second voltage regulating unit includes a second transistor T2 and a variable resistor R′;

[0080] A first end of the reset analysis module 12 is connected to a power supply voltage VCC, a second end of the reset analysis module 12 is connected to a first end and a second end of a first transistor T1, a third end of the first transistor T1 is connected to an output end of the pixel unit 20, a third end of the reset analysis module 12 is connected to a first end of a second transistor T1 and a control end of a variable resistor R′, a second end of the second transistor T2 is connected to a first end of the variable resistor R′, a second end of the variable resistor R′ is grounded, and a third end of the second transistor T2 is connected to an output end of the pixel unit 20;

[0081] The reset analysis module 12 is used for:

[0082] When the absolute value of the difference between the first reset voltage value and the reset voltage average value exceeds the reference threshold value and the first reset voltage value is less than the reset voltage average value, the first transistor T1 is controlled to be in an on state and the second transistor T2 is controlled to be in an off state, and the first voltage is output to the output terminal of the pixel unit 20;

[0083] When the absolute value of the difference between the first reset voltage value and the reset voltage average value exceeds the reference threshold value, and the first reset voltage value is greater than the reset voltage average value, the second transistor T2 is controlled to be in an on state, and the first transistor T1 is controlled to be in an off state, and the second voltage is controlled to be output to the output end of the pixel unit 20 by adjusting the resistance value of the variable resistor R′.

[0084] In some embodiments, the two voltage regulating units can be mainly implemented by transistors, wherein the first voltage regulating unit can be implemented by a transistor T1, and the second voltage regulating unit can be implemented by a transistor T2 and a variable resistor R′. The specific connection relationship is as follows: Figure 2 In this way, the reset analysis module 12 can determine how much reset voltage to output to the output end of the pixel unit 20 by controlling the on / off state of the transistors in the two voltage adjustment units and the variable resistor R′.

[0085] Specifically, when the Reset voltage average of the surrounding pixels is larger, the first transistor T1 can be controlled to be in the on state, and the second transistor T2 can be controlled to be in the off state. Specifically, an enable signal can be controlled to be output to the emitter of the first transistor T1, so that the emitter voltage is higher than the base voltage, forming a forward biased state of the emitter junction, thereby making the first transistor T1 in the on state, and inputting the Reset voltage average to the first transistor T1, and connecting it from its source to the Reset circuit of the pixel unit 20.

[0086] When the Reset voltage average of the surrounding pixels is smaller, the second transistor T2 can be controlled to be in the on state, and the first transistor T1 can be controlled to be in the off state. Specifically, the enable signal can be controlled to be output to the base of the second transistor T2, so that the base voltage is higher than the emitter voltage, forming a reverse biased state of the emitter junction, thereby making the second transistor T2 in the on state, and controlling the variable resistor R′, that is, the variable resistor, to adjust the voltage division size, so as to control the reduction of the current output voltage of the output end of the pixel unit 20 through the voltage division effect of the variable resistor R′.

[0087] In this way, the Reset voltage of the current pixel can be reasonably adjusted by simply controlling the transistor and the variable resistor according to the deviation of the Reset voltage of the current pixel relative to the average Reset voltage of the surrounding pixels, thereby ensuring the stability of the Reset voltage output by the current pixel, and this solution is simple and easy to implement.

[0088] It should be noted that, when the absolute value of the difference between the first reset voltage value and the reset voltage average value does not exceed the reference threshold value, the output end of the pixel unit is kept outputting the first reset voltage value. That is, when it is monitored that the Reset voltage of the current pixel is not much different from the Reset voltage average value of the surrounding pixels, it indicates that the Reset voltage stability of the current pixel is normal and does not need to be adjusted, so that the current output is kept and measured by the measurement module 15.

[0089] For example, when the pixel is in a high temperature state, during a certain exposure period, carriers and dark currents in the PD and other semiconductor devices will flow into the Figure 2In the FD shown, the voltage when reading the pixel reset (assuming it is 2.2V, the reference voltage is 2.5V, and every 0.1V is read as 20 digital values. From 2.5V to 2.2V, the voltage difference is 0.3V, so the reset digital value is 60 at this time) is lower than the normal state (2.4V, the reset digital value should be 20 under normal conditions). When reading the image data of the PD, assuming that the reset state returns to normal, the image signal read by the readout circuit will have an error. Assuming that the pure image signal is 2V, the total voltage after being injected into the FD is 0.4V, and the read digital value is 420. Then the image signal actually read is 420-60=360, such as Figure 4 As shown by the thin lines marked with serial numbers ① and ②, changes in the Reset signal will cause errors in the final image signal reading.

[0090] The overall operation process of the image signal readout circuit in the embodiment of the present application is described in detail below, which is as follows:

[0091] In step 1, the pixel unit 20 transmits the Reset voltage value A1 of FD, and the reset analysis module 12 makes a judgment. If the difference between the Reset voltage value of FD and the average Reset voltage of pixels in the 16×16 area stored in the reset analysis module 12 exceeds ±5%, the Reset voltage value A1 of FD is discarded.

[0092] Step 2: The reset analysis module 12 outputs the average Reset voltage value A2 of the pixels in the 16×16 area stored by itself to S1, and measures D2 through the measurement module 15. The average Reset voltage value A2 of the pixels in the 16×16 area stored by the reset analysis module 12 is the average Reset voltage value of the surrounding 16×16=256 pixels with the current pixel as the center.

[0093] Step 3: After the electrons from PD are transferred to FD, the pixel unit transfers the total voltage A3 in FD to S1 and measures D3.

[0094] Step 4: Calculate the difference between D3 and D2, which is the voltage digital value D_pixel corresponding to the pure light signal (image signal).

[0095] In the above action, A2 is used instead of A1 (the voltage value of the residual electrons of the FD) because in a high temperature environment, A1 changes during the entire pixel reading process, such as Figure 4As shown, the line corresponding to serial number ① and the line corresponding to serial number ② are the fluctuation range of A1, and the corresponding D1 in the figure (digital value of FD residual electrons) is also a changing value. Among them, the line corresponding to serial number ① represents that the read Reset signal is too large, and the measured D1 is smaller than the true value at this time. The line corresponding to serial number ② represents that the read Reset signal is too small, and the measured D1 is larger than the true value at this time. Assume that the light signal electron value is 500LSB (LSB is a digital value unit), and the voltage value A1 of the FD residual electrons is 200LSB when measured in step 1, and the FD residual electron voltage changes when measured in step 3, and the measured digital value becomes 300LSB. In step 3, a total of 800LSB digital value will be obtained, which will result in us getting a light signal electron value of 800-200=600LSB, which is inconsistent with the actual 500LSB.

[0096] If A2 (the Reset average value of 16×16=256 pixels, 210LSB) is used instead of A1, then when the Reset voltage value A1 of the pixel changes under extreme conditions such as high temperature, A2 changes very little, allowing the current pixel to be as close as possible to the measurements in step one and step three, and the read light signal electronic value will also be as close as possible to the actual value.

[0097] Often, high pixel temperatures appear in clusters, so the reset analysis module 12 refers to the average reset voltage of the 16×16 pixel arrays around the current pixel. When the reset voltage of the current pixel exceeds ±5% of the average, the average replaces the reset value of the current pixel.

[0098] In this way, the reading circuit can make the CIS pixels stably output the true photosensitivity signal value, and also achieve the effects of noise reduction and bad pixel removal.

[0099] The image signal readout circuit in the embodiment of the present application includes: a voltage regulating module, a first end of which is connected to the output ends of at least two pixel units; a reset analysis module, which is connected to the second end of the voltage regulating module, and is used to control the voltage regulating module to adjust the voltage output to the output end of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the average reset voltage of the pixels in the readout area is greater than a reference threshold; wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1; a reference voltage module, which is used to output a reference voltage; a switch module, a first switching end of the switch module is connected to the output end of the pixel unit, and a second switching end of the switch module is connected to the reference voltage module, and the switch module is used to control the on and off of the reference voltage module or the pixel unit; a measurement module, which is connected to the fixed end of the switch module, and is used to measure the output voltage of the pixel unit. In this way, by designing an improved readout circuit, the real-time reset voltage of the pixel is compared with the average reset voltage of the surrounding pixels, and the pixel reset voltage is adjusted when the difference is large, thereby ensuring that the pixel outputs a stable photoelectric signal, thereby ensuring the acquisition of high-quality images with low noise and high signal-to-noise ratio.

[0100] The embodiment of the present application also provides an image sensor, comprising the above-mentioned at least two pixel units and the above-mentioned image signal readout circuit, wherein the output end of the pixel unit is connected to the first end of the voltage regulating module in the image signal readout circuit; the pixel unit is used to output a reset voltage signal or a pixel voltage signal. The image sensor can implement each process implemented by the above-mentioned image signal readout circuit embodiment and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0101] The embodiment of the present application also provides a camera module, including the above-mentioned image sensor. The camera module can implement each process implemented by the above-mentioned image signal readout circuit embodiment and can achieve the same technical effect, which will not be described here to avoid repetition.

[0102] The embodiment of the present application also provides an electronic device, including the above-mentioned camera module. The electronic device can implement each process implemented by the above-mentioned image signal readout circuit embodiment and can achieve the same technical effect, which will not be described here to avoid repetition.

[0103] See also Figure 5 , Figure 5 The flowchart of the image signal reading method provided in the embodiment of the present application is executed by the above electronic device, such as Figure 5 As shown, the method comprises the following steps:

[0104] Step 501: When the switch module switches from the reference voltage module to the pixel unit, the reset analysis module obtains a first reset voltage value output by the pixel unit, and reads the reset voltage value of the pixel in a readout area, wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, where n is an integer greater than 1.

[0105] Step 502: The reset analysis module determines an average reset voltage of pixels in the readout area according to reset voltage values ​​of pixels in the readout area;

[0106] Step 503: When the absolute value of the difference between the first reset voltage value output by the pixel unit and the reset voltage average value exceeds a reference threshold, the reset analysis module controls the voltage regulation module to regulate the voltage output to the output terminal of the pixel unit.

[0107] Step 504: The measuring module measures the voltage outputted by the output terminal of the pixel unit.

[0108] Optionally, the voltage regulating module includes a first voltage regulating unit and a second voltage regulating unit; a first end of the first voltage regulating unit is connected to the output end of the pixel unit, a second end of the first voltage regulating unit is connected to the reset analysis module, a first end of the second voltage regulating unit is connected to the output end of the pixel unit, and a second end of the second voltage regulating unit is connected to the reset analysis module;

[0109] The step 503 includes:

[0110] The reset analysis module controls the first voltage adjustment unit to be turned on to output a first voltage to the output terminal of the pixel unit, when the absolute value of the difference between the first reset voltage value and the reset voltage average value exceeds a reference threshold and the first reset voltage value is less than the reset voltage average value; wherein the first voltage is the reset voltage average value;

[0111] When the absolute value of the difference between the first reset voltage value and the reset voltage average value exceeds the reference threshold and the first reset voltage value is greater than the reset voltage average value, the reset analysis module controls the second voltage adjustment unit to be turned on to output a second voltage to the output end of the pixel unit, wherein the second voltage is less than the first reset voltage value.

[0112] Optionally, the first voltage regulating unit includes a first triode, and the second voltage regulating unit includes a second triode and a variable resistor; the first end of the reset analysis module is connected to the power supply voltage, the second end of the reset analysis module is connected to the first end and the second end of the first triode, the third end of the first triode is connected to the output end of the pixel unit, the third end of the reset analysis module is connected to the first end of the second triode and the control end of the variable resistor, the second end of the second triode is connected to the first end of the variable resistor, the second end of the variable resistor is grounded, and the third end of the second triode is connected to the output end of the pixel unit;

[0113] The controlling the first voltage regulating unit to be turned on to output the first voltage to the output terminal of the pixel unit includes:

[0114] Controlling the first transistor to be in an on state, and controlling the second transistor to be in an off state, to output the first voltage to the output terminal of the pixel unit;

[0115] The controlling the second voltage regulating unit to be turned on to output the second voltage to the output terminal of the pixel unit includes:

[0116] The second transistor is controlled to be in an on state, the first transistor is controlled to be in an off state, and the resistance value of the variable resistor is adjusted to control the output of the second voltage to the output end of the pixel unit.

[0117] It should be noted that this embodiment is Figure 1 The specific implementation of the image signal reading method embodiment corresponding to the illustrated embodiment can refer to the relevant introduction in the aforementioned embodiment, and will not be described again here to avoid repetition.

[0118] In the image signal reading method of the embodiment of the present application, when the switch module switches from the reference voltage module to the pixel unit, the reset analysis module obtains the first reset voltage value output by the pixel unit, and reads the reset voltage value of the pixel in the readout area, the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1; the reset analysis module determines the reset voltage mean of the pixels in the readout area according to the reset voltage value of the pixels in the readout area; when the absolute value of the difference between the first reset voltage value output by the pixel unit and the reset voltage mean exceeds the reference threshold, the reset analysis module controls the voltage adjustment module to adjust the voltage output to the output end of the pixel unit; the measurement module measures the voltage output from the output end of the pixel unit. In this way, by using the improved readout circuit, the real-time reset voltage of the pixel is read and compared with the reset voltage mean of the surrounding pixels, and the reset voltage of the pixel is adjusted when the difference is large, so as to ensure that the pixel outputs a stable photoelectric signal, thereby ensuring the acquisition of a high-quality image with low noise and high signal-to-noise ratio.

[0119] Alternatively, if Figure 6 As shown, the embodiment of the present application also provides an electronic device 600, including a processor 601 and a memory 602, and the memory 602 stores a program or instruction that can be executed on the processor 601. When the program or instruction is executed by the processor 601, the various steps of the above-mentioned image signal reading method embodiment are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0120] It should be noted that the electronic devices in the embodiments of the present application include the mobile electronic devices and non-mobile electronic devices mentioned above.

[0121] Figure 7 A schematic diagram of the hardware structure of an electronic device to implement an embodiment of the present application.

[0122] The electronic device 700 includes but is not limited to: a radio frequency unit 701, a network module 702, an audio output unit 703, an input unit 704, a sensor 705, a display unit 706, a user input unit 707, an interface unit 708, a memory 709, and a processor 710, wherein the sensor 705 may refer to a distance sensor, a gravity sensor, an acceleration sensor, a gyroscope sensor, a temperature sensor, etc. The electronic device also includes a camera module 711, and the camera module 711 includes an image sensor 7111, and the image sensor 7111 includes at least two pixel units and Figure 1 The image signal readout circuit shown in the figure, the pixel unit is used to output a reset voltage signal or a pixel voltage signal, and the image signal readout circuit includes:

[0123] A voltage regulating module, wherein a first terminal of the voltage regulating module is connected to output terminals of at least two pixel units;

[0124] a reset analysis module, the reset analysis module being connected to the second end of the voltage regulation module, and the reset analysis module being used to control the voltage regulation module to regulate the voltage output to the output end of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the average reset voltage value of the pixels in the readout area is greater than a reference threshold; wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1;

[0125] A reference voltage module, used for outputting a reference voltage;

[0126] A switch module, wherein a first switch end of the switch module is connected to an output end of the pixel unit, a second switch end of the switch module is connected to the reference voltage module, and the switch module is used to control the on / off of the reference voltage module or the pixel unit;

[0127] A measuring module is connected to the fixed end of the switch module, and is used to measure the output voltage of the pixel unit.

[0128] Those skilled in the art will appreciate that the electronic device 700 may also include a power source (such as a battery) for supplying power to each component, and the power source may be logically connected to the processor 710 through a power management system, thereby implementing functions such as managing charging, discharging, and power consumption management through the power management system. Figure 7 The electronic device structure shown in the figure does not constitute a limitation on the electronic device. The electronic device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently, which will not be described in detail here.

[0129] The processor 710 is used for:

[0130] In the case where the switch module switches from the reference voltage module to the pixel unit, a first reset voltage value output by the pixel unit is obtained through a reset analysis module, and reset voltage values ​​of pixels in a readout area are read, wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, where n is an integer greater than 1;

[0131] Determining a reset voltage average of pixels in the readout area according to reset voltage values ​​of pixels in the readout area by a reset analysis module;

[0132] When the absolute value of the difference between the first reset voltage value output by the pixel unit and the reset voltage average value exceeds a reference threshold, controlling the voltage regulating module to regulate the voltage output to the output terminal of the pixel unit through the reset analysis module;

[0133] The voltage outputted by the output terminal of the pixel unit is measured by the measuring module.

[0134] Optionally, the voltage regulating module includes a first voltage regulating unit and a second voltage regulating unit, a first end of the first voltage regulating unit is connected to the output end of the pixel unit, a second end of the first voltage regulating unit is connected to the reset analysis module, a first end of the second voltage regulating unit is connected to the output end of the pixel unit, and a second end of the second voltage regulating unit is connected to the reset analysis module;

[0135] The processor 710 is further configured to:

[0136] When the absolute value of the difference between the first reset voltage value and the reset voltage average exceeds a reference threshold and the first reset voltage value is less than the reset voltage average, the reset analysis module controls the first voltage adjustment unit to be turned on to output a first voltage to an output terminal of the pixel unit, wherein the first voltage is the reset voltage average;

[0137] When the absolute value of the difference between the first reset voltage value and the reset voltage average exceeds the reference threshold, and the first reset voltage value is greater than the reset voltage average, the reset analysis module controls the second voltage adjustment unit to be turned on to output a second voltage to the output end of the pixel unit, wherein the second voltage is less than the first reset voltage value.

[0138] Optionally, the first voltage regulating unit includes a first triode, and the second voltage regulating unit includes a second triode and a variable resistor; the first end of the reset analysis module is connected to the power supply voltage, the second end of the reset analysis module is connected to the first end and the second end of the first triode, the third end of the first triode is connected to the output end of the pixel unit, the third end of the reset analysis module is connected to the first end of the second triode and the control end of the variable resistor, the second end of the second triode is connected to the first end of the variable resistor, the second end of the variable resistor is grounded, and the third end of the second triode is connected to the output end of the pixel unit;

[0139] The processor 710 is further configured to:

[0140] Controlling the first transistor to be in an on state and controlling the second transistor to be in an off state through the reset analysis module, and outputting the first voltage to the output terminal of the pixel unit;

[0141] The reset analysis module controls the second transistor to be in a cut-off state, controls the first transistor to be in a conducting state, and adjusts the resistance value of the variable resistor to control the output of the second voltage to the output end of the pixel unit.

[0142] Optionally, the measurement module includes an integrator, a comparator, an AND gate and a counter connected in series in sequence.

[0143] It should be understood that in the embodiment of the present application, the input unit 704 may include a graphics processor (Graphics Processing Unit, GPU) 7041 and a microphone 7042, and the graphics processor 7041 processes the image data of the static picture or video obtained by the image capture device (such as a camera) in the video capture mode or the image capture mode. The display unit 706 may include a display panel 7061, and the display panel 7061 may be configured in the form of a liquid crystal display, an organic light emitting diode, etc. The user input unit 707 includes a touch panel 7071 and at least one of other input devices 7072. The touch panel 7071 is also called a touch screen. The touch panel 7071 may include two parts: a touch detection device and a touch controller. Other input devices 7072 may include, but are not limited to, a physical keyboard, function keys (such as volume control keys, switch keys, etc.), a trackball, a mouse, and a joystick, which will not be repeated here.

[0144] The memory 709 can be used to store software programs and various data. The memory 709 may mainly include a first storage area for storing programs or instructions and a second storage area for storing data, wherein the first storage area may store an operating system, an application program or instructions required for at least one function (such as a sound playback function, an image playback function, etc.), etc. In addition, the memory 709 may include a volatile memory or a non-volatile memory, or the memory 709 may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), a synchronous dynamic random access memory (SDRAM), a double data rate synchronous dynamic random access memory (DDRSDRAM), an enhanced synchronous dynamic random access memory (ESDRAM), a synchronous link dynamic random access memory (SLDRAM) and a direct memory bus random access memory (DRRAM). The memory 709 in the embodiment of the present application includes but is not limited to these and any other suitable types of memory.

[0145] The processor 710 may include one or more processing units; optionally, the processor 710 integrates an application processor and a modem processor, wherein the application processor mainly processes operations related to an operating system, a user interface, and application programs, and the modem processor mainly processes wireless communication signals, such as a baseband processor. It is understandable that the modem processor may not be integrated into the processor 710.

[0146] An embodiment of the present application also provides a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, each process of the above-mentioned image signal reading method embodiment is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0147] The processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk.

[0148] An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned image signal reading method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0149] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0150] An embodiment of the present application provides a computer program product, which is stored in a storage medium. The program product is executed by at least one processor to implement the various processes of the above-mentioned image signal reading method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0151] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0152] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, a disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0153] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. An image signal readout circuit, characterized in that: include: A voltage regulating module, wherein a first terminal of the voltage regulating module is connected to output terminals of at least two pixel units; a reset analysis module, the reset analysis module being connected to the second end of the voltage regulation module, and the reset analysis module being used to control the voltage regulation module to regulate the voltage output to the output end of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the average reset voltage value of the pixels in the readout area is greater than a reference threshold; wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1; A reference voltage module, used for outputting a reference voltage; A switch module, wherein a first switch end of the switch module is connected to an output end of the pixel unit, a second switch end of the switch module is connected to the reference voltage module, and the switch module is used to control the on / off of the reference voltage module or the pixel unit; A measuring module is connected to the fixed end of the switch module, and is used to measure the output voltage of the pixel unit.

2. The image signal readout circuit according to claim 1, characterized in that: The voltage regulating module comprises a first voltage regulating unit and a second voltage regulating unit, wherein a first end of the first voltage regulating unit is connected to an output end of the pixel unit, a second end of the first voltage regulating unit is connected to the reset analysis module, a first end of the second voltage regulating unit is connected to an output end of the pixel unit, and a second end of the second voltage regulating unit is connected to the reset analysis module; Wherein, the reset analysis module is used for: When the absolute value of the difference between the first reset voltage value and the reset voltage average is greater than a reference threshold, and the first reset voltage value is less than the reset voltage average, the first voltage regulating unit is controlled to be turned on to output a first voltage to an output terminal of the pixel unit, wherein the first voltage is the reset voltage average; When the absolute value of the difference between the first reset voltage value and the reset voltage average is greater than a reference threshold, and the first reset voltage value is greater than the reset voltage average, the second voltage adjustment unit is controlled to be turned on to output a second voltage to the output end of the pixel unit, wherein the second voltage is less than the first reset voltage value.

3. The image signal readout circuit according to claim 2, characterized in that: The first voltage regulating unit includes a first triode, and the second voltage regulating unit includes a second triode and a variable resistor; The first end of the reset analysis module is connected to the power supply voltage, the second end of the reset analysis module is connected to the first end and the second end of the first triode, the third end of the first triode is connected to the output end of the pixel unit, the third end of the reset analysis module is connected to the first end of the second triode and the control end of the variable resistor, the second end of the second triode is connected to the first end of the variable resistor, the second end of the variable resistor is grounded, and the third end of the second triode is connected to the output end of the pixel unit; The reset analysis module is used for: When the absolute value of the difference between the first reset voltage value and the reset voltage average value is greater than a reference threshold value, and the first reset voltage value is less than the reset voltage average value, the first transistor is controlled to be in an on state, and the second transistor is controlled to be in an off state, so as to output the first voltage to the output terminal of the pixel unit; When the absolute value of the difference between the first reset voltage value and the reset voltage average is greater than a reference threshold, and the first reset voltage value is greater than the reset voltage average, the second transistor is controlled to be in an on state, and the first transistor is controlled to be in an off state, and the second voltage is controlled to be output to the output end of the pixel unit by adjusting the resistance value of the variable resistor.

4. The image signal readout circuit according to any one of claims 1 to 3, characterized in that: The measuring module comprises an integrator, a comparator, an AND gate and a counter which are connected in series in sequence.

5. An image sensor, characterized in that: The invention comprises at least two pixel units and the image signal readout circuit according to any one of claims 1 to 4, wherein the output end of the pixel unit is connected to the first end of a voltage regulating module in the image signal readout circuit; and the pixel unit is used to output a reset voltage signal or a pixel voltage signal.

6. A camera module, characterized in that: Comprising the image sensor as claimed in claim 5.

7. An electronic device, characterized in that: Includes the camera module described in claim 6.

8. A method for reading an image signal, executed by the electronic device according to claim 7, characterized in that: The method comprises: In the case where the switch module switches from the reference voltage module to the pixel unit, the reset analysis module obtains a first reset voltage value output by the pixel unit, and reads a reset voltage value of a pixel in a readout area, wherein the readout area is a square area centered on the pixel where the pixel unit is located, and the square area includes n rows of pixels and n columns of pixels, where n is an integer greater than 1; The reset analysis module determines a reset voltage average of pixels in the readout area according to reset voltage values ​​of pixels in the readout area; The reset analysis module controls the voltage regulation module to regulate the voltage output to the output terminal of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the reset voltage average value is greater than a reference threshold; The measuring module measures the voltage outputted by the output terminal of the pixel unit.

9. The method according to claim 8, characterized in that The voltage regulating module includes a first voltage regulating unit and a second voltage regulating unit; The reset analysis module controls the voltage regulation module to regulate the voltage output to the output terminal of the pixel unit when the absolute value of the difference between the first reset voltage value output by the pixel unit and the reset voltage average value is greater than a reference threshold value, including: The reset analysis module controls the first voltage adjustment unit to be turned on to output a first voltage to the output terminal of the pixel unit, when the absolute value of the difference between the first reset voltage value and the reset voltage average value is greater than a reference threshold value and the first reset voltage value is less than the reset voltage average value; wherein the first voltage is the reset voltage average value; The reset analysis module controls the second voltage adjustment unit to be turned on to output a second voltage to the output end of the pixel unit when the absolute value of the difference between the first reset voltage value and the reset voltage average value is greater than a reference threshold and the first reset voltage value is greater than the reset voltage average value. The second voltage is less than the first reset voltage value.

10. The method according to claim 9, characterized in that The first voltage regulating unit includes a first triode, and the second voltage regulating unit includes a second triode and a variable resistor; The controlling the first voltage regulating unit to be turned on to output the first voltage to the output terminal of the pixel unit includes: Controlling the first transistor to be in an on state, and controlling the second transistor to be in an off state, to output the first voltage to the output terminal of the pixel unit; The controlling the second voltage regulating unit to be turned on to output the second voltage to the output terminal of the pixel unit includes: The second transistor is controlled to be in an on state, the first transistor is controlled to be in an off state, and the resistance value of the variable resistor is adjusted to control the output of the second voltage to the output end of the pixel unit.

11. An electronic device, characterized in that: The method comprises a processor and a memory, wherein the memory stores a program or instruction that can be run on the processor, and when the program or instruction is executed by the processor, the steps of the image signal reading method according to any one of claims 8 to 10 are implemented.

Images