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

Abstract

The application discloses an image signal readout circuit, an image signal reading method and an electronic device, and belongs to the technical field of electronics. The readout circuit comprises a voltage adjusting module, a first end of the voltage adjusting module being connected with output ends of at least two pixel units; a reset analysis module, the reset analysis module being connected with a second end of the voltage adjusting module, and the reset analysis module being used for controlling the voltage adjusting module to adjust the voltage output to the output end of the pixel unit in the case that the absolute value of the difference between a 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 value; a reference voltage module, used for outputting a reference voltage; a switch module, used for controlling the on-off of the reference voltage module or the pixel unit; and a measurement module, used for measuring the output voltage of the pixel unit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronics, and particularly relates to an image signal readout circuit, an image signal reading method and an electronic device. BACKGROUND

[0002] In a shooting process, electronic devices such as mobile phones usually need to perform noise reduction processing to ensure image quality. A common method in the industry is to use noise reduction algorithms in the back end of an 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. To improve the noise reduction effect, an artificial intelligence (Artificial Intelligence, AI) noise reduction technology is proposed, that is, noise reduction is performed in the front end raw domain. However, the premise of AI noise reduction is to accurately calculate the noise floor. The noise floor state of a CMOS image sensor (CMOS Image Sensor, CIS) changes with factors such as camera opening time, environmental temperature, and mobile phone temperature, which makes it difficult for AI noise reduction to obtain accurate noise floor, thereby resulting in poor noise reduction effect and affecting image quality. SUMMARY

[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 stable photoelectric signals of pixel output, and further ensure high-quality images with low noise and high signal-to-noise ratio.

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

[0005] a voltage adjustment module, a first end of the voltage adjustment module being connected with output ends of at least two pixel units;

[0006] a reset analysis module, the reset analysis module being connected with a second end of the voltage adjustment module, and the reset analysis module being configured to control the voltage adjustment module to adjust a voltage output to the output end of the pixel unit in a case where an absolute value of a difference between a first reset voltage value output by the pixel unit and a reset voltage average value of pixels in a readout region is greater than a reference threshold value; wherein the readout region is a square region centered on a pixel where the pixel unit is located, the square region including n rows of pixels and n columns of pixels, and n is an integer greater than 1;

[0007] a reference voltage module, configured to output a reference voltage;

[0008] a switch module, a first switching end of the switch module being connected with the output end of the pixel unit, and a second switching end of the switch module being connected with the reference voltage module, and the switch module being configured to control the reference voltage module or the pixel unit to be turned on or turned off.

[0009] a measurement module connected with the fixed end of the switch module, the measurement module being configured to measure an 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 according to the first aspect, wherein an output end of the pixel unit is connected with a first end of the voltage adjustment module in the readout circuit; and the pixel unit is configured 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 according to the second aspect.

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

[0013] In a fifth aspect, an embodiment of the present application provides an image signal reading method, executed by the electronic device according to the fourth aspect, and the method comprises the steps of:

[0014] In a case where the switch module is switched from the reference voltage module to the pixel unit, the reset analysis module acquires a first reset voltage value output by the pixel unit, and reads reset voltage values of pixels in a readout region, the readout region being a square region with the pixel in which the pixel unit is located as a center, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1;

[0015] The reset analysis module determines a reset voltage mean value of the pixels in the readout region according to the reset voltage values of the pixels in the readout region;

[0016] In a case where an absolute value of a difference between the first reset voltage value output by the pixel unit and the reset voltage mean value exceeds a reference threshold value, the reset analysis module controls the voltage adjustment module to adjust a voltage output to the output end of the pixel unit;

[0017] The measurement module measures the voltage output by the output end 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, the memory storing programs or instructions executable on the processor, and the programs or instructions are executed by the processor to implement the steps of the method according to the fourth aspect.

[0019] In a seventh aspect, an embodiment of the present application provides a readable storage medium, the readable storage medium storing programs or instructions, and the programs or instructions are executed by a processor to implement the steps of the method according to the fourth aspect.

[0020] In an eighth aspect, an embodiment of the present application provides a chip, comprising a processor and a communication interface, the communication interface being coupled with the processor, and the processor being configured to run programs or instructions to implement the method in the fourth aspect.

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

[0022] In the embodiment of the present application, the image signal readout circuit comprises: a voltage adjustment module, a first end of the voltage adjustment module being connected with output ends of at least two pixel units; a reset analysis module, a second end of the voltage adjustment module being connected with the reset analysis module, the reset analysis module being configured to control the voltage adjustment module to adjust the voltage output to the output end of the pixel unit in a case where an absolute value of a difference between a first reset voltage value output by the pixel unit and a reset voltage average of pixels in a readout region is greater than a reference threshold value; wherein the readout region is a square region with the pixel in which the pixel unit is located as a center, the square region comprising n rows of pixels and n columns of pixels, n being an integer greater than 1; a reference voltage module, configured to output a reference voltage; a switch module, a first switching end of the switch module being connected with the output end of the pixel unit, a second switching end of the switch module being connected with the reference voltage module, the switch module being configured to control the reference voltage module or the pixel unit to be turned on or turned off; and a measurement module, the measurement module being connected with a fixed end of the switch module, the measurement module being configured to measure the output voltage of the pixel unit. In this way, by designing the improved readout circuit, the real-time reset voltage of the pixel is compared with the reset voltage average 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 stable photoelectric signals, and then to ensure that a high-quality image with low noise and high signal-to-noise ratio is obtained. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

[0026] Figure 4 FIG. 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 is a hardware structural diagram of an electronic device provided by some embodiments of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present application.

[0031] The terms “first”, “second”, and the like 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 can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by “first”, “second”, etc. are generally a category and do not limit the number of objects, for example, the first object can be one or more. In addition, “and / or” in the specification and claims indicates at least one of the connected objects, and the character “ / ” generally indicates that the front and rear associated objects are in an “or” relationship.

[0032] To make the embodiments of the present application clearer, the related technical knowledge involved in the embodiments of the present application will be introduced as follows:

[0033] The camera module of an electronic device such as a mobile phone is composed of a lens, a focusing motor, a complementary metal-oxide-semiconductor (CMOS) photosensitive sensor, an analog-to-digital converter (ADC), an image processor ISP, a memory, and the like. The approximate principle of shooting is that when the camera is aligned with the scene to take a picture, light passes through the lens and is irradiated onto the sensor. The sensor converts the light signal into an analog signal, and then performs digital signal conversion through the analog-to-digital converter. Finally, the image processor ISP generates image information and stores it on the mobile phone.

[0034] Camera Sensor is the core of the camera and the most critical technology in the camera. Sensor is divided into two types, one is the widely used Charge-coupled Device (CCD), and the other is CMOS device. Compared with traditional cameras, traditional cameras use "film" as their carrier for recording information, while the "film" of digital cameras is their imaging photosensitive elements. The photosensitive element is the "film" that does not need to be replaced and is integrated with the camera.

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

[0036] Camera Lens is the most important component in the camera, because its quality directly affects the quality of the captured image. The lens can be divided into two categories: zoom and fixed focus. Among them, the zoom lens is the lens whose focal length and viewing angle can be changed, that is, it can be pushed and pulled; the fixed focus lens is the lens whose focal length cannot be changed, only one focal length, or only one viewing angle.

[0037] CMOS Camera Module is the mainstream camera module currently used in mobile phones, mainly composed of Lens, Voice Coil Motor, IR Filter, CMOS, Digital Signal Processor (DSP), and Flexible Printed Circuit (FPC).

[0038] Among them, the Lens group is used for light collection and focusing. The Lens is fixed by the Voice Coil Motor, and the upper and lower ends of the Voice Coil Motor are linked with the spring. When focusing, the motor generates electromagnetic force through power supply, and the force finally balances with the spring force. The position of the motor can be controlled by the size of the power supply, and then the motor and Lens are pushed to the focus position. The light of the scene projected into the module is projected to the IR filter, which filters unnecessary light projected to the sensor to prevent the sensor from producing false colors / waves, thereby improving its effective resolution and color restoration. The light after the IR filter can be perceived by the pixels on the image sensor and converted into photoelectricity.

[0039] At present, the camera of mobile electronic devices such as mobile phones has more and more shooting functions, and consumers also have higher and higher requirements for the shooting experience of mobile phones, which is a great challenge to the function, performance and effect of mobile phone cameras.

[0040] The purpose of the present application is to design a new type of image signal readout circuit and image sensor, which contains a conventional pixel unit, and is matched with a new type of image signal readout circuit with noise reduction function. The AI noise reduction can accurately obtain the noise floor state of the CIS in real time, improve the AI noise reduction effect, and realize stable photoelectric signal output of each pixel to obtain high-quality images with low noise and high signal-to-noise ratio, while eliminating sensor fixed pattern noise and improving the final image quality.

[0041] The image signal readout circuit and image signal reading method provided by the embodiments of the present application will be described in detail below in combination with the drawings, specific embodiments and application scenarios.

[0042] Please refer to Figure 1 , Figure 1 The structure diagram of the image signal readout circuit provided by the embodiments of the present application is shown in Figure 1 , which includes:

[0043] The first end of the voltage regulation module 11 is connected with the output end of the at least two pixel units 20;

[0044] The reset analysis module 12 is connected with 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 in the case that the absolute value of the difference between the first reset voltage value output by the pixel unit 20 and the average reset voltage of the pixels in the readout area exceeds the reference threshold value; wherein the readout area is a square area with the pixel of the pixel unit 20 as the center, and the square area includes n rows of pixels and n columns of pixels, and n is an integer greater than 1;

[0045] The reference voltage module 13 is used to output a reference voltage;

[0046] The first switching end of the switch module 14 is connected with the output end of the pixel unit 20, and the second switching end of the switch module 14 is connected with 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 measurement module 15 is connected with the fixed end of the switch module 14, and the measurement module 15 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. Specifically, the substrate voltage signal of the FD is output to the readout circuit through the SF (source follower) and Rsel (row selector) to be quantized into a digital value V1.

[0054] Then, charge transfer occurs. Specifically, after the PD is exposed to light for a specified period of time, the TG is activated, completely transferring the charge from the PD to the FD for readout. The mechanism here is similar to the charge transfer in CCDs. The voltage of the FD decreases 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, the image sensor works very unstable, pixel output is prone to jump, such as high temperature environment, generally after the camera is turned on for a period of time, the CIS will continue to accumulate heat, resulting in temperature drift of semiconductor devices PD and triode, unstable work. Or in the night environment, the light is very weak, the sensor is often in long exposure mode, the pixel work will also be very unstable when the exposure is too long. At this time, the output value of the pixel will jump, resulting in poor consistency of the whole picture, that is, the noise will deteriorate, and the difference between multiple frames will also become larger, producing snowflake noise. The processing of the back-end ISP adds high digital gain, which will aggravate this phenomenon.

[0057] The generation principle is as shown in Figure 3 The process is as follows:

[0058] In the working process of the pixel circuit as shown in Figure 2 , the reset signal of the pixel output is first measured by the readout circuit, that is, the time t1 when the reference voltage drops to the reset voltage, forming a digital value D1.

[0059] Then let the electrical signal in the PD transfer to the FD, reset the reference voltage in the readout circuit, and measure the image signal + reset signal of the pixel output again, and get the digital value D2.

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

[0061] But often in extreme environments, such as high temperature and long exposure as mentioned above, the pixel works unstable, resulting in large fluctuation of the reset signal, and then leading to inaccurate D1, so even if the light signal is very stable, the D_signal we get will also be unstable.

[0062] For the above phenomenon, the improved image signal readout circuit is proposed in the embodiment of the present application as shown in Figure 1 :

[0063] Among them, the reset analysis module 12 (also called Reset Analysis mode, abbreviated as RSM) and the voltage regulation module 11 are the core modules of the readout circuit, mainly through these two modules to adjust and correct the large fluctuation of the reset voltage output by the pixel unit 20 in the high temperature, long exposure and other shooting environments.

[0064] Specifically, the reset analysis module 12 can monitor the reset voltage of each pixel unit 20 in real time, and record the reset voltage data of the pixels around the pixel where the currently monitored pixel unit 20 is located, such as the reset voltage data of 16x16 pixels above, below, left and right of the pixel as the center. That is, in some embodiments, the readout area described above 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 recorded reset voltage data of the 16x16 pixels around it to determine whether the stability of the reset voltage of the current pixel is normal, that is, whether it deviates too much 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, adjust the reset voltage of the current pixel through the voltage adjustment module 11 to return it to a normal state, that is, a state where it is basically consistent with the average reset voltage of the surrounding pixels. Finally, the adjusted reset voltage of the current pixel can be measured through the measurement module 15 to obtain a relatively stable D1 value.

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

[0067] As shown in Figure 1 The resistance R and the capacitance C in the integrator are the integration constants of the integration circuit, and 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, and the comparator is used to compare Uc and ground (0V) and output Uo to the AND gate and the 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 a digital value D. In this way, the measurement of the output voltage signal of the pixel unit 20 can be realized by simple circuit devices.

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

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

[0070] The voltage regulating module 11 can be a regulating unit including different regulating tendencies, such as respectively regulating up and regulating down the output voltage of the output end of the pixel unit 20, which can be implemented by using a switching device or a voltage dividing module.

[0071] Optionally, the voltage regulating module 11 includes a first voltage regulating unit and a second voltage regulating unit, a first end of the first voltage regulating unit is connected with the output end of the pixel unit 20, a second end of the first voltage regulating unit is connected with the reset analyzing module 12, a first end of the second voltage regulating unit is connected with the output end of the pixel unit 20, and a second end of the second voltage regulating unit is connected with the reset analyzing module 12.

[0072] The reset analyzing module 12 is configured to:

[0073] In a case where 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 voltage regulating unit is controlled to be turned on, and the reset voltage average value is output to the output end of the pixel unit 20 as the first voltage.

[0074] In a case where 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 voltage regulating unit is controlled to be turned on, and the second voltage less than the first reset voltage value is output to the output end of the pixel unit 20.

[0075] In some embodiments, the two voltage regulating units can be used to respectively cope with the cases where the current pixel's Reset voltage is too large and too small, specifically, when the current monitored pixel's Reset voltage exceeds the average value of the Reset voltages of the surrounding pixels by a reference threshold value, such as ±5% of the average value of the Reset voltages of the surrounding pixels, it is further determined whether the current pixel's Reset voltage is greater than or less than the average value of the Reset voltages of the surrounding pixels.

[0076] In a case where the current pixel's Reset voltage is less than the average value of the Reset voltages of the surrounding pixels, the first voltage regulating unit is controlled to be turned on, the average value of the Reset voltages is input to the first voltage regulating unit, and the average value of the Reset voltages is input to the output end of the pixel unit 20 through the first voltage regulating unit.

[0077] In a case that the Reset voltage of the current pixel is greater than the average value of the Reset voltages of the surrounding pixels, the second voltage adjusting unit is controlled to be turned on, and the Reset voltage of the current pixel is connected to the output end of the pixel unit 20 after being divided by the second voltage adjusting unit; the voltage dividing scheme can be determined according to the difference between the Reset voltage of the current pixel and the average value of the Reset voltages, so as to ensure that the Reset voltage of the current pixel is reduced to a value close to the average value of the Reset voltages.

[0078] In this way, the Reset voltage of the current pixel can be adjusted by different voltage adjusting units according to the deviation of the Reset voltage of the current pixel from the average value of the Reset voltages of the surrounding pixels, so as to ensure the stability of the Reset voltage output by the current pixel, and the accuracy of the adjustment of the pixel Reset voltage can be ensured.

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

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

[0081] The reset analysis module 12 is configured to:

[0082] In a case that the absolute value of the difference between the first Reset voltage value and the average value of the Reset voltages exceeds the reference threshold value, and the first Reset voltage value is less than the average value of the Reset voltages, the first transistor T1 is controlled to be in the turned-on state, the second transistor T2 is controlled to be in the turned-off state, and the first voltage is output to the output end of the pixel unit 20.

[0083] In a case that the absolute value of the difference between the first Reset voltage value and the average value of the Reset voltages exceeds the reference threshold value, and the first Reset voltage value is greater than the average value of the Reset voltages, the second transistor T2 is controlled to be in the turned-on state, the first transistor T1 is controlled to be in the turned-off state, and the second voltage is 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', and the specific connection relationship is as shown in 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 conduction and cutoff states of the transistors in the two voltage regulating units and the variable resistor R'.

[0085] Specifically, when the average of the Reset voltages of the surrounding pixels is larger, the first transistor T1 can be controlled to be in a conduction state, and the second transistor T2 can be controlled to be in a cutoff state. Specifically, an enable signal can be output to the emitter of the first transistor T1 to make the emitter voltage higher than the base voltage, so as to form a forward bias state of the emitter junction, thereby making the first transistor T1 in a conduction state, and the average of the Reset voltages is input to the first transistor T1, and the source of the first transistor T1 is connected to the Reset line of the pixel unit 20.

[0086] When the average of the Reset voltages of the surrounding pixels is smaller, the second transistor T2 can be controlled to be in a conduction state, and the first transistor T1 can be controlled to be in a cutoff state. Specifically, an enable signal can be output to the base of the second transistor T2 to make the base voltage higher than the emitter voltage, so as to form a reverse bias state of the emitter junction, thereby making the second transistor T2 in a conduction state, and the variable resistor R' is adjusted to reduce the current output voltage of the pixel unit 20 through the voltage division of the variable resistor R'.

[0087] In this way, the deviation of the Reset voltage of the current pixel relative to the average of the Reset voltages of the surrounding pixels can be adjusted by simply controlling the transistors and the variable resistor, so as to ensure the stability of the Reset voltage output by the current pixel, and the scheme is simple and easy to implement.

[0088] It should be noted that, in the case where the absolute value of the difference between the first reset voltage value and the average of the reset voltages does not exceed the reference threshold, the output end of the pixel unit outputs the first reset voltage value. That is, in the case where the Reset voltage of the current pixel is not much different from the average of the Reset voltages of the surrounding pixels, it is indicated that the stability of the Reset voltage of the current pixel is normal, and no adjustment is needed, so as to keep the current output and then measure by the measurement module 15.

[0089] For example, when the pixel is in a high-temperature state, during a certain exposure period, the carriers and dark current in the PD and other semiconductor devices will flow into Figure 2The FD shown, resulting in the reading of the pixel Reset voltage (assuming 2.2V, the reference voltage is 2.5V, every 0.1v reading is 20 digital value, from 2.5V down to 2.2V, the voltage difference is 0.3V, then the Reset reading digital value is 60), lower than normal (2.4V, normal Reset reading digital value should be 20), and read the PD image data, assuming the Reset state back to normal, then the readout circuit will produce errors when reading the image signal, assuming a pure image signal is 2V, the total voltage is 0.4V after filling the FD, the reading digital value is 420. Then the actual reading of the image signal is 420-60 = 360, as Figure 4 The Reset signal variation will result in the final image signal reading error, as shown by the thin lines marked with serial numbers ① and ②.

[0090] The overall operation process of the image signal readout circuit in the embodiment of the application will be described in detail as follows:

[0091] Step one, the pixel unit 20 transmits the Reset voltage value A1 of the FD, and the reset analysis module 12 judges. If the Reset voltage value of the FD at this time and the average value of the pixel Reset voltage of the 16x16 region stored in the reset analysis module 12 differ by more than ±5%, the Reset voltage value A1 of the FD is discarded.

[0092] Step two, the reset analysis module 12 outputs the average value A2 of the pixel Reset voltage of the 16x16 region stored in itself to S1, and the measurement module 15 measures to obtain D2. Among them, the average value A2 of the pixel Reset voltage of the 16x16 region stored in the reset analysis module 12 is the average value of the Reset voltage of the 16x16 = 256 pixels around the current pixel.

[0093] Step three, after the electron transfer of the PD into the FD, the pixel unit transmits the total voltage A3 in the FD to S1, and measures to obtain D3.

[0094] Step four, 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 electron of the FD), because in a high temperature environment, A1 changes in the entire pixel reading process, such as Figure 4As shown, the fluctuation range of the line corresponding to serial number 1 and the line corresponding to serial number 2 is A1, and the corresponding D1 (digital value of the residual electrons of the FD) in the figure is also a variable value. The line corresponding to serial number 1 represents that the read Reset signal is too large, and at this time, the measured D1 is smaller than the true value. The line corresponding to serial number 2 represents that the read Reset signal is too small, and at this time, the measured D1 is larger than the true value. Assuming that the light signal electron value is 500LSB (LSB is the unit of digital value), the voltage value of the residual electrons of the FD A1 is 200LSB in the first step of measurement, and the voltage of the residual electrons of the FD changes in the third step of measurement, and the measured digital value becomes 300LSB. Then, in the third step, a digital value of 800LSB is obtained, which leads to an obtained light signal electron value of 800-200=600LSB, which is inconsistent with the actual 500LSB.

[0096] If A2 (Reset average value of 16x16=256 pixels, 210LSB) is used instead of A1, when the Reset voltage value A1 of the pixel changes under extreme conditions such as high temperature, A2 changes very little, so that the current pixel measured in the first step and the third step is as close as possible, and the read light signal electron value is also as close as possible to the actual value.

[0097] Usually, the pixel high temperature appears in patches, so the reset analysis module 12 will refer to the average Reset voltage of the 16x16 pixel array around the current pixel, and when the Reset voltage of the current pixel exceeds the average value by ±5%, the average value will be used instead of the Reset value of the current pixel.

[0098] In this way, the read circuit can achieve stable output of the true light signal value of the CIS pixel, 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 comprises: a voltage adjustment module, a first end of the voltage adjustment module being connected with output ends of at least two pixel units; a reset analysis module, a second end of the voltage adjustment module being connected with the reset analysis module, the reset analysis module being configured to control the voltage adjustment module to adjust the voltage output to the output end of the pixel unit in the case that an absolute value of a difference between a first reset voltage value output by the pixel unit and a reset voltage average value of pixels in a readout region is greater than a reference threshold value; wherein the readout region is a square region with the pixel in which the pixel unit is located as a center, the square region comprising n rows of pixels and n columns of pixels, n being an integer greater than 1; a reference voltage module, configured to output a reference voltage; a switch module, a first switching end of the switch module being connected with the output end of the pixel unit, a second switching end of the switch module being connected with the reference voltage module, the switch module being configured to control the reference voltage module or the pixel unit to be turned on or turned off; and a measurement module, the measurement module being connected with a fixed end of the switch module, the measurement module being configured to measure the output voltage of the pixel unit. In this way, by designing the improved readout circuit, the reset voltage of the pixel is compared with the reset voltage average value of the surrounding pixels in real time, and the reset voltage of the pixel is adjusted when the difference is large, so as to ensure that the pixel outputs stable photoelectric signals, and then ensure that a high-quality image with low noise and high signal-to-noise ratio is acquired.

[0100] The embodiment of the present application further provides an image sensor comprising the at least two pixel units and the image signal readout circuit, wherein the output end of the pixel unit is connected with the first end of the voltage adjustment module in the image signal readout circuit; and the pixel unit is configured to output a reset voltage signal or a pixel voltage signal. The image sensor can realize each process realized by the image signal readout circuit and achieve the same technical effects. To avoid repetition, details are not described herein again.

[0101] The embodiment of the present application further provides a camera module comprising the image sensor. The camera module can realize each process realized by the image signal readout circuit and achieve the same technical effects. To avoid repetition, details are not described herein again.

[0102] The embodiment of the present application further provides an electronic device comprising the camera module. The electronic device can realize each process realized by the image signal readout circuit and achieve the same technical effects. To avoid repetition, details are not described herein again.

[0103] Please refer to Figure 5 , Figure 5 The flowchart of the image signal reading method provided by the embodiment of the present application is executed by the electronic device, as shown in Figure 5 , the method comprises the following steps:

[0104] In a case where the switch module switches from the reference voltage module to the pixel unit, the reset analysis module acquires a first reset voltage value output by the pixel unit and reads reset voltage values of pixels in a readout region, the readout region being a square region centered on a pixel in which the pixel unit is located, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1;

[0105] In a case where the switch module switches from the reference voltage module to the pixel unit, the reset analysis module acquires a first reset voltage value output by the pixel unit and reads reset voltage values of pixels in a readout region, the readout region being a square region centered on a pixel in which the pixel unit is located, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1;

[0106] In a case where the switch module switches from the reference voltage module to the pixel unit, the reset analysis module acquires a first reset voltage value output by the pixel unit and reads reset voltage values of pixels in a readout region, the readout region being a square region centered on a pixel in which the pixel unit is located, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1;

[0107] In a case where the switch module switches from the reference voltage module to the pixel unit, the reset analysis module acquires a first reset voltage value output by the pixel unit and reads reset voltage values of pixels in a readout region, the readout region being a square region centered on a pixel in which the pixel unit is located, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1;

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

[0109] The step 503 includes:

[0110] In a case where the absolute value of the difference between the first reset voltage value and the reset voltage average exceeds the reference threshold value 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 the output end of the pixel unit, wherein the first voltage is the reset voltage average.

[0111] In a case where the absolute value of the difference between the first reset voltage value and the reset voltage average exceeds the reference threshold value 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.

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

[0113] The control of the first voltage regulating unit to be turned on and the output of the first voltage to the output end of the pixel unit comprises:

[0114] The control of the first triode to be in a turned-on state and the control of the second triode to be in a turned-off state, and the output of the first voltage to the output end of the pixel unit;

[0115] The control of the second voltage regulating unit to be turned on and the output of the second voltage to the output end of the pixel unit comprises:

[0116] The control of the second triode to be in a turned-on state and the control of the first triode to be in a turned-off state, and the adjustment of the resistance value of the variable resistor, and the control of the output of the second voltage to the output end of the pixel unit.

[0117] It should be noted that the embodiment is an image signal reading method embodiment corresponding to the embodiment shown in Figure 1 The specific implementation of the embodiment can be referred to the related description in the foregoing embodiment, and details are not described herein again to avoid repetition.

[0118] The image signal reading method in the embodiment of the application, in a case where the switch module is switched from the reference voltage module to the pixel unit, the reset analysis module acquires a first reset voltage value output by the pixel unit, and reads reset voltage values of pixels in a readout region, the readout region being a square region with the pixel in which the pixel unit is located as a center, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1; the reset analysis module determines a reset voltage mean value of the pixels in the readout region according to the reset voltage values of the pixels in the readout region; in a case where an absolute value of a difference between the first reset voltage value output by the pixel unit and the reset voltage mean value exceeds a reference threshold value, the reset analysis module controls the voltage adjustment module to adjust a voltage output to an output end of the pixel unit; and the measurement module measures the voltage output by the output end of the pixel unit. In this way, by using the improved readout circuit, the reset voltage of the pixel is read in real time and compared with the reset voltage mean value of the surrounding pixels, and the reset voltage of the pixel is adjusted when the difference is large, so that the stable photoelectric signal of the pixel is ensured, and then the high-quality image with low noise and high signal-to-noise ratio is ensured.

[0119] Optionally, as shown in Figure 6 The embodiment of the application also provides an electronic device 600, including a processor 601 and a memory 602, the memory 602 has a program or instruction which can run on the processor 601, the program or instruction is executed by the processor 601 to realize each step of the above-mentioned image signal reading method embodiment, and the same technical effect can be achieved, to avoid repetition, which will not be repeated here.

[0120] It should be noted that the electronic device in the embodiment of the application includes the mobile electronic device and the non-mobile electronic device described above.

[0121] Figure 7 To realize the hardware structure of the electronic device in the embodiment of the 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, etc., wherein the sensor 705 can be a distance sensor, a gravity sensor, an acceleration sensor, a gyroscope sensor, a temperature sensor, etc., the electronic device further includes a camera module 711, the camera module 711 includes an image sensor 7111, the image sensor 7111 includes at least two pixel units and Figure 1 The image signal readout circuit shown in the image signal readout circuit, the pixel unit is used to output a reset voltage signal or a pixel voltage signal, the image signal readout circuit includes:

[0123] a voltage regulation module, a first end of the voltage regulation module being connected with output ends of the at least two pixel units;

[0124] a reset analysis module, a second end of the voltage regulation module being connected with the reset analysis module, the reset analysis module being configured to control the voltage regulation module to adjust the voltage output to the output end of the pixel unit in a case where an absolute value of a difference between a first reset voltage value output by the pixel unit and a reset voltage average of pixels in a readout region is greater than a reference threshold value, the readout region being a square region centered on a pixel in which the pixel unit is located, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1;

[0125] a reference voltage module configured to output a reference voltage;

[0126] a switch module, a first switching end of the switch module being connected with the output end of the pixel unit, a second switching end of the switch module being connected with the reference voltage module, the switch module being configured to control the reference voltage module or the pixel unit to be turned on or turned off;

[0127] a measurement module, the measurement module being connected with a fixed end of the switch module, the measurement module being configured to measure an output voltage of the pixel unit.

[0128] Those skilled in the art can understand that the electronic device 700 can further include a power supply (such as a battery) for supplying power to each component, and the power supply can be logically connected with the processor 710 through a power management system, so as to realize functions such as management of charging, discharging, and power consumption management through the power management system. Figure 7 The electronic device structure shown in the foregoing embodiments does not constitute a limitation on the electronic device, and the electronic device can include more or fewer components than those shown, or combine certain components, or have a different arrangement of components, which will not be described here again.

[0129] The processor 710 is configured to:

[0130] In a case where the switch module is switched from the reference voltage module to the pixel unit, the reset analysis module is configured to acquire a first reset voltage value output by the pixel unit, and read reset voltage values of pixels in a readout region, the readout region being a square region centered on a pixel in which the pixel unit is located, the square region including n rows of pixels and n columns of pixels, n being an integer greater than 1;

[0131] The reset analysis module is configured to determine a reset voltage average of the pixels in the readout region according to the reset voltage values of the pixels in the readout region;

[0132] In a case where an absolute value of a difference between the first reset voltage value output by the pixel unit and the reset voltage average value exceeds a reference threshold value, the reset analysis module controls the voltage adjustment module to adjust the voltage output to the output end of the pixel unit.

[0133] The measurement module measures the voltage output to the output end of the pixel unit.

[0134] Optionally, the voltage adjustment module comprises a first voltage adjustment unit and a second voltage adjustment unit, a first end of the first voltage adjustment unit is connected with the output end of the pixel unit, a second end of the first voltage adjustment unit is connected with the reset analysis module, a first end of the second voltage adjustment unit is connected with the output end of the pixel unit, and a second end of the second voltage adjustment unit is connected with the reset analysis module.

[0135] The processor 710 is further configured to:

[0136] In a case where 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 reset analysis module controls the first voltage adjustment unit to be turned on to output a first voltage to the output end of the pixel unit, wherein the first voltage is the reset voltage average value.

[0137] In a case where 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 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 adjustment unit comprises a first triode, the second voltage adjustment unit comprises a second triode and a variable resistor, a first end of the reset analysis module is connected with a power supply voltage, a second end of the reset analysis module is connected with a first end and a second end of the first triode, a third end of the first triode is connected with the output end of the pixel unit, a third end of the reset analysis module is connected with a first end of the second triode and a control end of the variable resistor, a second end of the second triode is connected with a first end of the variable resistor, a second end of the variable resistor is grounded, and a third end of the second triode is connected with the output end of the pixel unit.

[0139] The processor 710 is further configured to:

[0140] The reset analysis module controls the first triode to be in a conducting state and controls the second triode to be in a cut-off state, and outputs the first voltage to the output end of the pixel unit;

[0141] The reset analysis module controls the second triode to be in a cut-off state and controls the first triode 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 comprises an integrator, a comparator, an AND gate and a counter connected in series.

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

[0144] The memory 709 can be used to store software programs and various data. The memory 709 can mainly include a first storage area storing programs or instructions and a second storage area storing data, wherein the first storage area can store an operating system, application programs or instructions required by at least one function (such as a sound playing function, an image playing function, etc.), etc. In addition, the memory 709 can include a volatile memory or a non-volatile memory, or the memory 709 can include both a volatile memory and a non-volatile memory. The non-volatile memory can be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically EPROM (EEPROM), or a flash memory. The volatile memory can be a Random Access Memory (RAM), a Static RAM (SRAM), a Dynamic RAM (DRAM), a Synchronous DRAM (SDRAM), a Double Data Rate SDRAM (DDR SDRAM), an Enhanced SDRAM (ESDRAM), a Synch link DRAM (SLDRAM), and a Direct Rambus RAM (DRRAM). The memory 709 in the embodiments of the present application includes but is not limited to these and any other suitable types of memory.

[0145] The processor 710 can 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 an application program, and the modem processor mainly processes wireless communication signals, such as a baseband processor. It can be understood that the above-mentioned modem processor can also not be integrated into the processor 710.

[0146] The embodiments of the present application also provide a readable storage medium, the readable storage medium stores programs or instructions, the programs or instructions are executed by a processor to realize each process of the above-mentioned image signal reading method embodiments, and the same technical effects can be achieved. To avoid repetition, details are not described here.

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

[0148] The embodiment of the present application further provides a chip, which comprises a processor and a communication interface, the communication interface is coupled with the processor, the processor is used for running programs or instructions to realize the processes of the above image signal reading method embodiments and achieve the same technical effects. To avoid repetition, details are not described herein.

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

[0150] The 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 realize the processes of the above image signal reading method embodiments and achieve the same technical effects. To avoid repetition, details are not described herein.

[0151] It should be noted that in this document, the term "comprising" or "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the method and device in the embodiment of the present application is not limited to the order of performing the functions as shown or discussed, but can also include performing the functions in a substantially simultaneous manner or in a reverse order, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to some examples can be combined in other examples.

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

[0153] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative and not restrictive. Those skilled in the art can make many forms under the inspiration of the present application without departing from the scope of the present application and the scope protected by the claims.

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 connected to the second end of the voltage regulation module, the reset analysis module being configured to control 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 average reset voltage value of the pixels in a 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, the square area including n rows of pixels and n columns of pixels, where n is an integer greater than 1; A reference voltage module, used for outputting a reference voltage; a switch module, wherein a first switching end of the switch module is connected to the output end of the pixel unit, 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 / 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, wherein: The voltage regulating module 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 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; 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, controlling the first voltage regulating unit to be turned on to output a first voltage to the 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, wherein: The first voltage regulating unit includes a first transistor, and the second voltage regulating unit includes a second transistor and a variable resistor; A first end of the reset analysis module is connected to a power supply voltage, a second end of the reset analysis module is connected to a first end and a second end of the first triode, a third end of the first triode is connected to an output end of the pixel unit, a third end of the reset analysis module is connected to a first end of the second triode and a control end of the variable resistor, a second end of the second triode is connected to a first end of the variable resistor, a second end of the variable resistor is grounded, and a third end of the second triode is connected to the output end of the pixel unit; The reset analysis module is used for: When an absolute value of a 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, 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 an 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, wherein: The measurement module includes 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 device 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 the voltage regulation 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 according to claim 5.

7. An electronic device, characterized in that: Including 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: 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 reset voltage values ​​of pixels in a readout area, where 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 an average reset voltage value of pixels in the readout area based on the reset voltage values ​​of the 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 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 is greater than a reference threshold, including: The reset analysis module controls the first voltage adjustment unit to be turned on and 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 and the first reset voltage value is less than the reset voltage average value. The first voltage is the reset voltage average value. The reset analysis module controls the second voltage adjustment unit to be turned on and 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 is greater than a reference threshold and the first reset voltage value is greater than the reset voltage average, wherein 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 transistor, and the second voltage regulating unit includes a second transistor 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