Pixel circuit, image sensor, camera module, equipment and control method

Abstract

The invention discloses a pixel circuit, an image sensor, a camera module, equipment and a control method, and relates to the technical field of electronics, the pixel circuit comprises a photodiode, an output module and at least two shunt modules; the photodiode is electrically connected with the output module and each shunt module; the total current converted by the photodiode is equal to the sum of the first partial current and the second partial current; the first partial current is the partial current input by the photodiode to the output module, and the second partial current is the partial current input by the shunt module conducted by the photodiode; the output module is used for converting the first partial current into voltage and outputting the voltage; wherein the number of the conducted shunt modules is in positive correlation with the current value of the total current.

Description

Technical Field

[0001] The present application belongs to the field of electronic technology, and specifically relates to a pixel circuit, an image sensor, a camera module, a device and a control method. Background Art

[0002] An image sensor is a device that converts optical images into electronic signals, and pixel circuits are the basic units that make up an image sensor.

[0003] In the related art, the total current converted by the photodiode in the pixel circuit is converted into a voltage and output, and then undergoes analog-to-digital conversion, that is, conversion of analog signals to digital signals, to form pixel image data. It should be noted that the output voltage of the pixel circuit is positively correlated with the brightness of the pixel image.

[0004] However, when the light intensity increases, the total current converted by the photodiode in the pixel circuit increases, and the voltage output according to the converted total current increases, causing the pixel image to be too bright and the details to be blurred, and the clarity of the pixel image to decrease. Summary of the invention

[0005] The embodiments of the present application provide a pixel circuit, an image sensor, a camera module, a device and a control method to prevent the pixel image from being too bright and improve the clarity of the pixel image.

[0006] In a first aspect, an embodiment of the present application provides a pixel circuit, comprising: a photodiode, an output module, and at least two shunt modules;

[0007] The photodiode is electrically connected to the output module and each shunt module; the total current converted by the photodiode is equal to the sum of the first shunt current and the second shunt current; the first shunt current is the shunt current input by the photodiode to the output module, and the second shunt current is the shunt current input by the photodiode to the conducted shunt module; the output module is used to convert the first shunt current into a voltage and output it;

[0008] The number of the conducting shunt modules is positively correlated with the current value of the total current.

[0009] In a second aspect, an embodiment of the present application further provides an image sensor, comprising the pixel circuit as described in the first aspect.

[0010] In a third aspect, an embodiment of the present application further provides a camera module, comprising the image sensor as described in the second aspect.

[0011] In a fourth aspect, an embodiment of the present application further provides an electronic device, comprising the camera module as described in the third aspect.

[0012] In a fifth aspect, an embodiment of the present application further provides a pixel circuit control method, which is performed by the electronic device according to the fourth aspect, and the method includes:

[0013] Obtaining a voltage value of a cathode of the photodiode;

[0014] Controlling a shunt module that matches the voltage value of the cathode to be turned on;

[0015] The number of the shunt modules that match the voltage value of the cathode is negatively correlated with the voltage value of the cathode.

[0016] In the embodiment of the present application, since the total current converted by the photodiode is equal to the sum of the first partial current obtained by the output module and the second partial current obtained by each conductive shunt module, the more shunt modules are turned on, the smaller the first partial current obtained by the output module and the smaller the output voltage. Since the number of conductive shunt modules is positively correlated with the current value of the total current converted by the photodiode, when the total converted current increases, the number of conductive shunt modules increases, thereby reducing the first partial current obtained by the output module. Therefore, the increase in output voltage caused by the increase in total current can be reduced. Compared with the related art, it avoids the pixel image from being too bright and improves the clarity of the pixel image. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of a pixel circuit provided by some embodiments of the present application;

[0018] Figure 2 is a specific structural schematic diagram of a pixel circuit provided in some embodiments of the present application;

[0019] Figure 3 is a schematic diagram of an image sensor provided by some embodiments of the present application;

[0020] Figure 4 is a schematic diagram of collecting images provided by some embodiments of the present application;

[0021] Figure 5 are two curve schematic diagrams of pixel circuits provided in some embodiments of the present application;

[0022] Figure 6 is a schematic diagram of an electronic device provided by some embodiments of the present application;

[0023] Figure 7 This is a step flow chart of a method for controlling a pixel circuit provided in some embodiments of the present application.

[0024] Description of reference numerals:

[0025] 10-photodiode; 20-output module; 21-output submodule; 30-shunt module; Q1-first switch device; Q2-second switch device; Q3-third switch device; Q4-reset switch device; Q5-select switch device; C1-first capacitor; C2-second capacitor. DETAILED DESCRIPTION

[0026] 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.

[0027] 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 data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, 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.

[0028] Reference Figure 1 An embodiment of the present application provides a pixel circuit, including a photodiode 10, an output module 20 and at least two shunt modules 30; the photodiode 10 is electrically connected to the output module 20 and each shunt module 30; the total current converted by the photodiode 10 is equal to the sum of the first shunt current and the second shunt current; the first shunt current is the shunt current input by the photodiode 10 to the output module 20, and the second shunt current is the shunt current input by the photodiode 10 to the turned-on shunt module 30; the output module 20 is used to convert the first shunt current into a voltage and output it; wherein the number of the turned-on shunt modules 30 is positively correlated with the current value of the total current.

[0029] It should be noted that the output module 20 is connected in parallel with each current dividing module 30 ; the output voltage output by the output module 20 is the voltage generated by the first current dividing conversion.

[0030] The photodiode 10 is used to convert an optical signal into an electrical signal, and the electrical signal is a signal of the total current converted by the photodiode 10. When the photodiode 10 is exposed, the photodiode 10 operates in a reverse biased state; the total current converted by the photodiode 10 is the current generated by the photodiode 10 converting the optical signal, and the total current converted by the photodiode 10 is positively correlated with the light intensity to which the photodiode 10 is exposed; the total current converted by the photodiode 10 includes photocurrent and dark current, and the photocurrent is an effective signal, and the photocurrent is related to the sensitivity and exposure time; the dark current is noise, which is affected by the semiconductor process, temperature and exposure time.

[0031] The shunt module 30 is used to shunt the total current converted by the photodiode 10 when the shunt module 30 is turned on, so as to reduce the first shunt current obtained by the output module 20 .

[0032] For example, the pixel circuit includes a photodiode 10, an output module 20 and two shunt modules 30. When the current value of the total current converted by the photodiode 10 is a first value, the first shunt module 30 is turned on, and the sum of the current value of the first shunt current F1 and the current value of the second shunt current F2 is equal to the first value; wherein the first shunt current F1 is the shunt current input by the photodiode 10 to the output module 20, and the second shunt current F2 is the shunt current input by the photodiode 10 to the first shunt module 30 that is turned on.

[0033] When the current value of the total current converted by the photodiode 10 is the second value, the two shunt modules 30 are both turned on, and the sum of the current value of the first shunt current F3, the current value of the second shunt current F4 and the current value of the second shunt current F5 is equal to the second value; wherein the first value is less than the second value, the first shunt current F3 is the shunt current input by the photodiode 10 to the output module 20, the second shunt current F4 is the shunt current input by the photodiode 10 to the first shunt module 30 that is turned on, and the second shunt current F5 is the shunt current input by the photodiode 10 to the second shunt module 30 that is turned on.

[0034] In the embodiment of the present application, since the total current converted by the photodiode is equal to the sum of the first partial current obtained by the output module and the second partial current obtained by each conductive shunt module, the more shunt modules are turned on, the smaller the first partial current obtained by the output module and the smaller the output voltage. Since the number of conductive shunt modules is positively correlated with the current value of the total current converted by the photodiode, when the total converted current increases, the number of conductive shunt modules increases, thereby reducing the first partial current obtained by the output module. Therefore, the increase in output voltage caused by the increase in total current can be reduced. Compared with the related art, it avoids the pixel image from being too bright and improves the clarity of the pixel image.

[0035] When the total converted current decreases, the number of the shunt modules 30 that are turned on decreases, so that the first shunt current obtained by the output module 20 increases, and the output voltage increases, ensuring that the image of the pixel in a dark light environment has good brightness, avoiding the brightness of the pixel image in a dark light environment being too low and the details being blurred, and ensuring that the image of the pixel has good clarity in a dark light environment.

[0036] Optional, see Figure 2 In some embodiments, each of the shunt modules 30 includes a first switch device Q1, a second switch device Q2 and a first capacitor C1; the anode of the photodiode 10 is grounded, and the cathode of the photodiode 10 is electrically connected to the input end of the output module 20 and the first end of each of the first switch devices Q1 respectively; in the shunt module 30, the second end of the first switch device Q1 is electrically connected to the first end of the first capacitor C1, and the control end of the first switch device Q1 is used to receive a control signal; the first end of the second switch device Q2 is used to be electrically connected to an external power supply, the second end of the second switch device Q2 is grounded, and the control end of the second switch device Q2 is electrically connected to the first end of the first capacitor C1; the second end of the first capacitor C1 is grounded.

[0037] It should be noted that the on and off of the first switching device Q1 is controlled by a control signal. Specifically, when a control signal of a first level is input to the first switching device Q1, the first switching device Q1 is turned on; when a control signal of a second level is input to the first switching device Q1, the first switching device Q1 is turned off; wherein the first level is opposite to the second level.

[0038] When the first switch device Q1 is turned on, the shunt module 30 is turned on; when the first switch device Q1 is turned off, the shunt module 30 is turned off; the first capacitor C1 is used to store the charge converted by the photodiode 10 when the first switch device Q1 is turned on.

[0039] Each first switching device Q1 has a corresponding control signal input terminal 41 of the pixel circuit. The control terminal of the first switching device Q1 is electrically connected to the control signal input terminal 41 of the pixel circuit. The control signal input terminal 41 of the pixel circuit is used to receive the control signal of the first switching device Q1.

[0040] In some embodiments of the present application, when the total converted current increases, the first switching device Q1 is turned on by inputting a first-level control signal, so that the number of turned-on first switching devices Q1 increases, and then the number of turned-on shunt modules 30 increases, so that the first shunt current obtained by the output module 20 decreases, so as to reduce the increase in the output voltage caused by the increase in the total current. Compared with the related art, it avoids the pixel image from being too bright, improves the clarity of the pixel image, and ensures that the pixel image has good clarity in a bright light environment.

[0041] Optionally, in some embodiments, each of the first switching devices Q1 has a corresponding conduction parameter, and the conduction parameter is the difference between the voltage value of the control signal of the first switching device Q1 and the conduction threshold of the first switching device Q1; the conduction parameters of at least some of the first switching devices Q1 are different; when the voltage value of the cathode of the photodiode 10 is less than the conduction parameter of the first switching device Q1, the first switching device Q1 is turned on; when the voltage value of the cathode of the photodiode 10 is greater than the conduction parameter of the first switching device Q1, the first switching device Q1 is turned off.

[0042] In some embodiments of the present application, by setting the voltage value of the control signal of the first switching device Q1, the difference between the voltage value of the control signal of the first switching device Q1 and the conduction threshold of the first switching device Q1 can be made greater than the voltage value of the cathode of the photodiode 10, thereby realizing the conduction of the first switching device Q1; by setting the voltage value of the control signal of the first switching device Q1, the difference between the voltage value of the control signal of the first switching device Q1 and the conduction threshold of the first switching device Q1 can be made less than the voltage value of the cathode of the photodiode 10, thereby realizing the disconnection of the first switching device Q1.

[0043] For example, the first switch device Q1 and the second switch device Q2 are both NMOS tubes, which are negative channel metal-oxide-semiconductor tubes (Negative channel-Metal-Oxide-Semiconductor); in the shunt module 30, the gate of the first switch device Q1 is used to receive a control signal, the drain of the first switch device Q1 is electrically connected to the cathode of the photodiode 10, and the source of the first switch device Q1 is electrically connected to the first end of the first capacitor C1; the first end of the first capacitor C1 is electrically connected to the gate of the second switch device Q2, and the second end of the first capacitor C1 is grounded; the drain of the second switch device Q2 is electrically connected to the external power supply, and the source of the second switch device Q2 is grounded.

[0044] Optionally, in some embodiments, the output module 20 includes a second capacitor C2 and an output sub-module 21; the anode of the photodiode 10 is grounded, and the cathode of the photodiode 10 is electrically connected to the first end of the second capacitor C2 and the input end of each shunt module 30, respectively; the input end of the output sub-module 21 is electrically connected to the first end of the second capacitor C2, and the output sub-module 21 is used to convert and output the voltage of the second capacitor C2; the second end of the second capacitor C2 is grounded.

[0045] It should be noted that the second capacitor C2 is used to store the charges converted by the photodiode 10 .

[0046] In some embodiments of the present application, the first partial current is obtained through the output module 20, the second capacitor C2 is charged by the first partial current, and the voltage of the second capacitor C2 is converted and output through the output submodule 21 to achieve voltage output of the pixel circuit.

[0047] Optionally, in some embodiments, the output submodule 21 includes a third switching device Q3 and a selection switch device Q5; the first end of the third switching device Q3 is electrically connected to an external power supply, and the second end of the third switching device Q3 is electrically connected to the first end of the selection switch device Q5; the control end of the selection switch device Q5 is used to receive a pixel row selection signal, and the second end of the selection switch device Q5 is used to output a voltage converted from the voltage of the second capacitor C2.

[0048] It should be noted that the third switching device Q3 is used to convert the voltage of the second capacitor C2 and output the voltage after the voltage of the second capacitor C2 is converted; the selection switch device is used to be turned on when the control end of the selection switch device Q5 obtains the pixel row selection signal, and outputs the voltage after the voltage of the second capacitor C2 is converted through the second end of the selection switch device Q5.

[0049] In some embodiments of the present application, a first partial current is obtained through the output module 20, and the second capacitor C2 is charged by the first partial current. When the difference between the voltage value of the second capacitor C2 and the voltage value of the second end of the third switch device Q3 is greater than the turn-on threshold of the third switch device Q3, the third switch device Q3 is turned on. When the control end of the selection switch device Q5 obtains a pixel row selection signal, the selection switch device Q5 is turned on, and the voltage converted from the voltage of the second capacitor C2 is output through the second end of the selection switch device Q5 to realize the voltage output of the pixel circuit; wherein, the voltage value of the second capacitor C2 is the voltage value of the gate of the third switch device Q3.

[0050] Optionally, in some embodiments, the third switch device Q3 and the selection switch device Q5 are both transistors.

[0051] It should be noted that the control end of the selection switch device Q5 is electrically connected to the pixel row selection signal input end 43 of the pixel circuit, and the pixel row selection signal input end 43 is used to receive the pixel row selection signal; the second end of the selection switch device Q5 is electrically connected to the output end 44 of the pixel circuit, and the voltage value VOUT between the output end 44 of the pixel circuit and the ground is the voltage value of the output voltage of the pixel circuit, and the voltage value VOUT between the output end 44 of the pixel circuit and the ground is also the voltage value output by the second end of the selection switch device Q5.

[0052] Specifically, the third switch device Q3 and the selection switch device Q5 are both NMOS tubes, the first end of the second capacitor C2 is electrically connected to the gate of the third switch device Q3, the drain of the third switch device Q3 is electrically connected to the external power supply, and the source of the third switch device Q3 is electrically connected to the drain of the selection switch device Q5; the source of the selection switch device Q5 is electrically connected to the output terminal 44 of the pixel circuit, and the gate of the selection switch device Q5 is electrically connected to the pixel row selection signal input terminal 43.

[0053] In some embodiments of the present application, since the third switch device Q3 and the selection switch device Q5 are both transistors, when the difference between the voltage value of the second capacitor C2 and the voltage value of the second end of the third switch device Q3 is greater than the turn-on threshold of the third switch device Q3, the third switch device Q3 is turned on, and when the control end of the selection switch device Q5 obtains the pixel row selection signal, the selection switch device Q5 is turned on, and the voltage converted from the voltage of the second capacitor C2 is output through the second end of the selection switch device Q5 to realize the voltage output of the pixel circuit; wherein, the voltage value of the second capacitor C2 is the voltage value of the gate of the third switch device Q3.

[0054] In some embodiments, the second end of the second switching device Q2 is electrically connected to the first end of the selection switching device Q5. When the first switching device Q1 is turned on, the first capacitor C1 is charged by the second branch current, and the voltage of the first capacitor C1 increases. When the difference between the voltage value of the first capacitor C1 and the voltage value of the second end of the second switching device Q2 is greater than the turn-on threshold of the second switching device Q2, the second switching device Q2 is turned on, and the second end of the second switching device Q2 can serve as a redundant structure for the second end of the third switching device Q3, that is, when the selection switching device Q5 is turned on and the third switching device Q3 is abnormally disconnected, so that the second end of the third switching device Q3 has no output, the voltage output by the second end of the second switching device Q2 can be used as the output voltage of the pixel circuit.

[0055] The model of the second switch device Q2 is the same as the model of the third switch device Q3, and the voltage value outputted by the second end of the second switch device Q2 is equal to the voltage value outputted by the second end of the third switch device Q3.

[0056] Optionally, in some embodiments, the pixel circuit further includes a reset switch device Q4; a first end of the reset switch device Q4 is used to be electrically connected to the external power supply, a second end of the reset switch device Q4 is respectively electrically connected to the first end of each first switch device Q1, and a control end of the reset switch device Q4 is used to receive a reset signal.

[0057] It should be noted that the control end of the reset switch device Q4 is electrically connected to the reset signal input end 42 of the pixel circuit, and the reset signal input end 42 is used to receive the reset signal of the reset switch device Q4.

[0058] The second end of the reset switch device Q4 is also electrically connected to the first end of the second capacitor C2.

[0059] In some embodiments of the present application, when the reset switch device Q4 is turned on and the first switch device Q1 is turned on, the charge of the first capacitor C1 flows to the external power supply. Therefore, the first capacitor C1 can be reset by the reset switch device Q4, that is, the charge of the first capacitor C1 is zero, and the voltage value of the first capacitor C1 is zero at this time; when the reset switch device Q4 is turned on, the charge of the second capacitor C2 flows to the external power supply. Therefore, the second capacitor C2 can be reset by the reset switch device Q4, that is, the charge of the second capacitor C2 is zero, and the voltage value of the second capacitor C2 is zero at this time.

[0060] Optionally, in some embodiments, the reset switch device Q4, the first switch device Q1 and the second switch device Q2 are all transistors.

[0061] Specifically, the reset switch device Q4, each first switch device Q1 and each second switch device are NMOS tubes.

[0062] In some embodiments of the present application, since the reset switch device Q4 is a transistor, the reset switch device Q4 can be turned on and off by the control end of the reset switch device Q4; since the first switch device Q1 is a transistor, the first switch device Q1 can be turned on and off by the control end of the first switch device Q1; since the second switch device Q2 is a transistor, the first switch device Q1 can be turned on and off by the control end of the second switch device Q2.

[0063] Specifically, in some embodiments, the reset switch device Q4, each first switch device Q1, each second switch device Q2, the third switch device Q3 and the selection switch device Q5 are all NMOS tubes. In the shunt module 30, the gate of the first switch device Q1 is used to receive the control signal, the drain of the first switch device Q1 is electrically connected to the cathode of the photodiode 10, and the source of the first switch device Q1 is electrically connected to the first end of the first capacitor C1; the first end of the first capacitor C1 is electrically connected to the gate of the second switch device Q2, and the second end of the first capacitor C1 is grounded; the drain of the second switch device Q2 is electrically connected to the external power supply, and the source of the second switch device Q2 is grounded; the first end of the second capacitor C2 is electrically connected to the third switch device Q3; the second end of the second capacitor C2 ... second capacitor C1 is grounded; the second end of the second capacitor C2 is electrically connected to the gate of the second switch device Q2, and the second end of the second capacitor C2 is grounded; the second end of the second capacitor C2 is electrically connected to the gate of the second switch device Q2, and the second end of the second capacitor C2 is grounded; the second end of the second capacitor C2 is electrically connected to the gate of the second switch device Q2, and the second end of the second capacitor C2 is grounded; the second end of the second capacitor C2 is electrically connected to the gate of the second switch device Q2, and the second end of the second capacitor C2 is grounded; the second end of the second capacitor C2 is electrically connected to the gate of the second switch device Q2, and the second The gate of the switching device Q3 is electrically connected, the drain of the third switching device Q3 is electrically connected to the external power supply, and the source of the third switching device Q3 is electrically connected to the drain of the selection switching device Q5; the source of the selection switching device Q5 is electrically connected to the output terminal 44 of the pixel circuit, and the gate of the selection switching device Q5 is electrically connected to the pixel row selection signal input terminal 43; the drain of the reset switching device Q4 is electrically connected to the external power supply, the source of the reset switching device Q4 is electrically connected to the drain of each first switching device Q1 and the first end of the second capacitor C2, and the gate of the reset switching device Q4 is used to receive a reset signal; the cathode of the photodiode 10 is electrically connected to the drain of each first switching device Q1 and the first end of the second capacitor C2.

[0064] In some embodiments, the output voltage value of the pixel circuit is calculated by formula (1):

[0065]

[0066] Where V is the output voltage value of the pixel circuit, U s is the voltage value outputted by the source of the third switch device Q3, w is the gain factor of the third switch device Q3, U g is the gate voltage of the third switching device Q3, U c is the voltage value of the second capacitor C2, q is the charge of the second capacitor C2, c is the total capacitance value obtained by adding the capacitance value of the first capacitor C1 and the capacitance value of the second capacitor C2 in each conductive shunt module 30, i is the current value of the total current converted by the photodiode 10, and t is the exposure time.

[0067] It should be noted that the amplification factor w of the third switch device Q3 is usually less than 1; ideally, the amplification factor w of the third switch device Q3 is 1, the third switch device Q3 is equivalent to a voltage follower, and the amplification factor w of the third switch device Q3 is the gain factor of the third switch device Q3.

[0068] The more modules of the conducting shunt modules 30 are, the larger the total capacitance value c is, and the smaller the output voltage value V of the pixel circuit is. Therefore, the number of modules of the conducting shunt modules 30 is negatively correlated with the output voltage value V of the pixel circuit.

[0069] In some embodiments, the reset switch device Q4, each first switch device Q1, each second switch device Q2, the third switch device Q3 and the selection switch device Q5 are all NMOS tubes. In the shunt module 30, the gate of the first switch device Q1 is used to receive the control signal, the source of the first switch device Q1 is electrically connected to the cathode of the photodiode 10, the drain of the first switch device Q1 is electrically connected to the first end of the first capacitor C1; the first end of the first capacitor C1 is electrically connected to the gate of the second switch device Q2, and the second end of the first capacitor C1 is grounded; the drain of the second switch device Q2 is electrically connected to the external power supply, and the source of the second switch device Q2 is grounded; the first end of the second capacitor C2 is electrically connected to the third switch device Q3. The gate of the reset switch device Q4 is electrically connected to the external power supply, the drain of the third switch device Q3 is electrically connected to the external power supply, and the source of the third switch device Q3 is electrically connected to the drain of the selection switch device Q5; the source of the selection switch device Q5 is electrically connected to the output terminal 44 of the pixel circuit, and the gate of the selection switch device Q5 is electrically connected to the pixel row selection signal input terminal 43; the drain of the reset switch device Q4 is electrically connected to the external power supply, the source of the reset switch device Q4 is electrically connected to the drain of each first switch device Q1 and the first end of the second capacitor C2, and the gate of the reset switch device Q4 is used to receive a reset signal; the cathode of the photodiode 10 is electrically connected to the drain of each first switch device Q1 and the first end of the second capacitor C2.

[0070] It should be noted that, when the NMOS tube is turned on, the current may flow from the drain of the NMOS tube to the source of the NMOS tube, or the current may flow from the source of the NMOS tube to the drain of the NMOS tube.

[0071] For example, the pixel circuit in the image sensor includes a photodiode 10, an output module 20 and two shunt modules 30; each shunt module 30 includes a first switch device Q1, a second switch device Q2 and a first capacitor C1, the output module 20 includes a second capacitor C2, an output submodule 21, and the output submodule 21 includes a third switch device Q3 and a selection switch device Q5; each first switch device Q1, each second switch device Q2, the third switch device Q3 and the selection switch device Q5 are NMOS tubes; wherein, in each shunt module 30, the gate of the first switch device Q1 is used to receive a control signal, the source of the first switch device Q1 is electrically connected to the cathode of the photodiode 10, and the drain of the first switch device Q1 is electrically connected to the first end of the first capacitor C1.

[0072] By setting the voltage value of the control signal, a first difference value obtained by subtracting the conduction threshold value of the first switching device Q1 from the gate voltage value of the first switching device Q1 in the first shunt module 30 is greater than a second difference value obtained by subtracting the conduction threshold value of the first switching device Q1 in the second shunt module 30 from the gate voltage value of the first switching device Q1 in the second shunt module 30.

[0073] When the voltage value of the cathode of the photodiode 10 is the first voltage value, wherein the voltage value of the cathode of the photodiode 10 is the voltage value of the source of the first switch device Q1, the first voltage value is greater than the first difference and the first voltage value is greater than the second difference, the first switch device Q1 in the first shunt module 30 and the first switch device Q1 in the second shunt module 30 are both disconnected, and the output voltage value of the pixel circuit is calculated by formula (2):

[0074]

[0075] Among them, V a is the output voltage value of the pixel circuit, w is the amplification factor of the third switch device Q3, i a is the current value of the total current converted by the photodiode 10 in the pixel circuit, t is the exposure time, and c1 is the capacitance value of the second capacitor C2.

[0076] When the light intensity of the image collected by the pixel circuit increases, the current value of the total current converted by the photodiode 10 increases, and the voltage value of the cathode of the photodiode 10 decreases from the first voltage value to the second voltage value. The second voltage value is less than the first difference and the second voltage value is greater than the second difference. Then, the first switch device Q1 in the first shunt module 30 is turned on, and the first switch device Q1 in the second shunt module 30 is turned off. At this time, the output voltage value of the pixel circuit is calculated by formula (3):

[0077]

[0078] Among them, V b is the output voltage value of the pixel circuit, w is the amplification factor of the third switch device Q3, i b is the current value of the total current converted by the photodiode 10 in the pixel circuit, t is the exposure time, c1 is the capacitance value of the second capacitor C2, and c2 is the capacitance value of the first capacitor C1 in the first shunt module 30.

[0079] When the illumination intensity of the image collected by the pixel circuit further increases, the current value of the total current converted by the photodiode 10 further increases, and the voltage value of the cathode of the photodiode 10 decreases from the second voltage value to the third voltage value, and the third voltage value is less than the first difference and the third voltage value is less than the second difference, then the first switch device Q1 in the first shunt module 30 and the first switch device Q1 in the second shunt module 30 are both turned on, and the output voltage value of the pixel circuit is calculated by formula (4):

[0080]

[0081] Among them, V c is the output voltage value of the pixel circuit, w is the amplification factor of the third switch device Q3, i c is the current value of the total current converted by the photodiode 10 in the pixel circuit, t is the exposure time, c1 is the capacitance value of the second capacitor C2, c2 is the capacitance value of the first capacitor C1 in the first shunt module 30, and c3 is the capacitance value of the first capacitor C1 in the second shunt module 30.

[0082] In some embodiments, the type of the second switch device Q2 is the same as the type of the third switch device Q3, and the source of the second switch device Q2 is electrically connected to the drain of the selection switch device Q5; when the first switch device Q1 is turned on, the first capacitor C1 is charged by the second branch current, and when the difference between the voltage value of the first capacitor C1 and the voltage value of the source of the second switch device Q2 is greater than the turn-on threshold of the second switch device Q2, the second switch device Q2 is turned on, and at this time, the voltage value output by the source of the second switch device Q2 is equal to the product of the amplification factor of the second switch device Q2 and the voltage value of the gate of the second switch device Q2; since the type of the second switch device Q2 is the same as the type of the third switch device Q3, the amplification factor of the second switch device Q2 is equal to the amplification factor of the third switch device Q3; since the turned-on shunt module 30 The first capacitor C1 is connected in parallel with the second capacitor C2, and the voltage value of the first capacitor C1 in the conducting shunt module 30 is equal to the voltage value of the second capacitor C2. Therefore, the voltage value output by the source of the second switch device Q2 in the conducting shunt module 30 is equal to the voltage value output by the source of the third switch device Q3. The source of the second switch device Q2 in the conducting shunt module 30 can be used as a redundant structure of the source of the third switch device Q3. When the selection switch device Q5 is turned on and the third switch device Q3 is abnormally disconnected, so that the source of the third switch device Q3 has no output, the voltage output by the source of the second switch device Q2 can be used as the output voltage of the pixel circuit; wherein, the voltage value of the first capacitor C1 is the voltage value of the gate of the second switch device Q2, and the gate of the second switch device Q2 is the voltage value of the first capacitor C1.

[0083] An embodiment of the present application also provides an image sensor, comprising the aforementioned pixel circuit.

[0084] The specific implementation process of the pixel circuit in the image sensor is similar to the specific implementation process of the aforementioned pixel circuit, which will not be repeated here.

[0085] Reference Figure 3 In some embodiments, the image sensor includes a plurality of pixel column modules A1, each pixel column module A1 includes a plurality of pixel circuits A11, a column amplifier A12 and a column analog-to-digital converter (ADC) A13; in the pixel column module A1, the input end of the column amplifier A12 is electrically connected to the output end of each pixel circuit A11, and the output end of the column amplifier A12 is electrically connected to the input end of the column analog-to-digital converter A13; each pixel of the image is exposed and read out row by row, and the voltage signal output from the output end of the pixel circuit A11 is amplified by the column amplifier A12, and the column amplifier A12 outputs the amplified voltage signal, and the column analog-to-digital converter A13 converts the amplified voltage signal into a digital signal and outputs it.

[0086] In some embodiments, the pixel circuit in the image sensor includes a photodiode 10, an output module 20 and two shunt modules 30; each shunt module 30 includes a first switch device Q1, a second switch device Q2 and a first capacitor C1, the output module 20 includes a second capacitor C2, an output sub-module 21, and the output sub-module 21 includes a third switch device Q3 and a selection switch device Q5; each first switch device Q1, each second switch device Q2, the third switch device Q3 and the selection switch device Q5 are NMOS tubes.

[0087] For example, refer to Figure 4 , the brightness of image B1 is greater than that of image B2, and the brightness of image B2 is greater than that of image B3, then the light intensity at b1 in image B1 is greater than the light intensity at b2 in image B2, and the light intensity at b3 in image B3 is greater than the light intensity at b3 in image B3.

[0088] In the image sensor, in the pixel circuit of the image at b1 in the collected image B1, both shunt modules 30 are turned on, and the output voltage value of the pixel circuit of the image at b1 is calculated by formula (5):

[0089]

[0090] Among them, V1 is the output voltage value of the pixel circuit for collecting the image at b1, w is the amplification factor of the third switching device Q3, i1 is the current value of the total current converted by the photodiode 10 in the pixel circuit for collecting the image at b1, t is the exposure time, c1 is the capacitance value of the second capacitor C2, c2 is the capacitance value of the first capacitor C1 in the first shunt module 30, c3 is the capacitance value of the first capacitor C1 in the second shunt module 30, and K1 is the capacitance gain coefficient of the pixel circuit for collecting the image at b1.

[0091] In the image sensor, in the pixel circuit of the image at b2 in the captured image B2, the first shunt module 30 is turned on and the second shunt module 30 is turned off. Then, the output voltage value of the pixel circuit of the image at b2 is calculated by formula (6):

[0092]

[0093] Among them, V2 is the output voltage value of the pixel circuit of the image collected at b2, w is the amplification factor of the third switching device Q3, i2 is the current value of the total current converted by the photodiode 10 in the pixel circuit of the image collected at b2, t is the exposure time, c1 is the capacitance value of the second capacitor C2, c2 is the capacitance value of the first capacitor C1 in the first shunt module 30, and K2 is the capacitance gain coefficient of the pixel circuit of the image collected at b2.

[0094] In the image sensor, in the pixel circuit of the image at b3 in the captured image B3, the first shunt module 30 and the second shunt module 30 are both disconnected, and the output voltage value of the pixel circuit of the image at b3 is calculated by formula (7):

[0095]

[0096] Among them, V3 is the output voltage value of the pixel circuit for collecting the image at b3, w is the amplification factor of the third switching device Q3, i3 is the current value of the total current converted by the photodiode 10 in the pixel circuit for collecting the image at b3, t is the exposure time, c1 is the capacitance value of the second capacitor C2, and K3 is the capacitance gain coefficient of the pixel circuit for collecting the image at b3.

[0097] Since the light intensity at b1 in image B1 is greater than the light intensity at b2 in image B2, and the light intensity at b3 in image B3 is greater than the light intensity at b3 in image B3, i1 is greater than i2, i2 is greater than i3; K1 is less than K2, and K2 is less than K3.

[0098] Figure 5(a) is a curve showing the relationship between the capacitance gain coefficient K and the light intensity I of the pixel circuit. The light intensity of image B1 is greater than the light intensity I2, the light intensity of image B2 is greater than the light intensity I1 and less than or equal to the light intensity I2, and the light intensity of image B2 is less than or equal to the light intensity I1. L1 is a curve showing the relationship between the capacitance gain coefficient K and the light intensity I of the pixel circuit for capturing image B3. L2 is a curve showing the relationship between the capacitance gain coefficient K and the light intensity I of the pixel circuit for capturing image B2. L3 is a curve showing the relationship between the capacitance gain coefficient K and the light intensity I of the pixel circuit for capturing image B1. The capacitance gain coefficient of the pixel circuit for capturing image B1 is K1, the capacitance gain coefficient of the pixel circuit for capturing image B2 is K2, and the capacitance gain coefficient of the pixel circuit for capturing image B3 is K3.

[0099] Figure 5 (b) is a curve showing the relationship between the output voltage value V of the pixel circuit and the light intensity I. The light intensity of image B1 is greater than the light intensity I2, the light intensity of image B2 is greater than the light intensity I1 and less than or equal to the light intensity I2, and the light intensity of image B2 is less than or equal to the light intensity I1. Curve L4 is a curve showing the relationship between the output voltage value V of the pixel circuit provided in the embodiment of the present application and the light intensity I. Curve L5 is a curve showing the relationship between the output voltage value V of the pixel circuit in the related art and the light intensity I. In the range of light intensity I1 to light intensity I4, the output voltage value of the pixel circuit provided in the embodiment of the present application is less than that of the pixel circuit in the related art. The output voltage value of the circuit, for example, at the light intensity I3, the output voltage value Vx of the pixel circuit provided in the embodiment of the present application is less than the output voltage value Vy of the pixel circuit in the related art. Since the output voltage of the pixel circuit is positively correlated with the brightness of the pixel image, in a bright light environment, the brightness of the pixel image converted by the output voltage value of the pixel circuit provided in the embodiment of the present application is lower than the brightness of the pixel image converted by the output voltage value of the pixel circuit in the related art. Therefore, the pixel image converted by the output voltage value of the pixel circuit provided in the embodiment of the present application is clearer than the pixel image converted by the output voltage value of the pixel circuit in the related art.

[0100] Therefore, the embodiment of the present application can adaptively adjust the value of K, thereby achieving high-gain conversion under low illumination, and automatically switch to low-gain mode under high-brightness environment, thereby realizing a dynamic adjustment function, that is, the lower the illumination, the higher the conversion gain, and the more details in the dark, and the higher the illumination, the lower the conversion gain, and the highlight details are retained as much as possible, thereby realizing an adaptive HDR function, and only needs to read out the data once, retaining the details of the dark and highlight areas, and realizing high dynamic imaging; wherein, illumination is the intensity of light.

[0101] An embodiment of the present application also provides a camera module, comprising the image sensor as described above.

[0102] The specific implementation process of the pixel circuit in the camera module is similar to the specific implementation process of the aforementioned pixel circuit, which will not be repeated here.

[0103] It should be noted that the camera module (CCM) is an important tool for obtaining visual information, which is usually composed of a lens, an infrared cut filter, an image sensor and a voice coil motor (VCM).

[0104] Among them, the image sensor is the core device of CCM. There are two types of mainstream image sensors: one is the charge-coupled device (CCD) component; the other is the complementary metal-oxide-semiconductor (CMOS) device. Similar to the film of a traditional camera, the core function of the image sensor is to sense light, that is, to convert the detected light signal into a digital signal that is easy to transmit and process.

[0105] In some embodiments, the image sensor is a CMOS image sensor (CIS). Compared with CCD devices, CMOS has lower cost and power consumption, and a more flexible reading method. The working mechanism of CIS is as follows: the photodiodes 10 (pixels) arranged in an array sense the light signal and convert it into an electrical signal, which is then converted into a digital signal matrix through an amplifier and an analog-to-digital converter. The digital signal matrix is ​​the image data, and the image data is then compressed and stored through an image signal processor (ISP).

[0106] The lens is another core component in the CCM. Its function is to converge the light in the field of view onto the imaging plane. Its optical quality directly affects the imaging quality. From the perspective of information transmission, the design level of the lens determines the transmission of high-frequency information reaching the image plane, which directly affects the imaging clarity of the module; from the perspective of energy transmission, the lens structure determines the intensity and distribution of light reaching the CIS, which directly affects the signal-to-noise ratio performance of the CIS.

[0107] Based on the above devices, the workflow of CCM is as follows: First, VCM drives the lens to focus, focusing the light carrying visual information through the lens, and filtering out the infrared band invisible to the human eye through the infrared cut-off filter, imaging to the image sensor. The photodiode 10 converts the optical signal into an electrical signal, forms a digital signal matrix through amplification and digital-to-analog conversion, that is, the raw domain image (Raw Image), which is then compressed and stored in the memory after being processed by the ISP module.

[0108] The dynamic range (DR) of imaging refers to the ability of the CIS image to simultaneously reflect the highlights and shadows. Therefore, a larger full well capacity (FWC) and lower read noise are conducive to high dynamic range (HDR) imaging. When the dynamic range of the CIS is smaller than the dynamic range of the image scene, overexposure of bright areas or loss of details in dark areas will occur, affecting the image quality. Compared with the related art, the pixel circuit provided in the embodiment of the present application can avoid the image of the pixel from being too bright, improve the clarity of the image of the pixel, and ensure that the image of the pixel in a bright light environment has good clarity. Therefore, the image sensor in the camera module provided in the embodiment of the present application has a better dynamic range of imaging, that is, the image sensor in the camera module provided in the embodiment of the present application has a high dynamic range.

[0109] Reference Figure 6 , an embodiment of the present application further provides an electronic device 200, comprising the camera module 201 as described above.

[0110] The specific implementation method of the camera module 201 in the electronic device 200 is similar to the above, and will not be repeated here.

[0111] It should be noted that the electronic device disclosed in the embodiments of the present application may be a smart phone, a tablet computer, an e-book reader, a wearable device (such as a smart watch), an electronic game console, etc. The embodiments of the present application do not limit the specific types of electronic devices.

[0112] In some related technologies, multiple frames are captured based on different exposure strategies, and then an algorithm is used to fuse a high-dynamic image. However, the multi-frame fusion method is only suitable for static environments, and it is easy to produce ghost images in complex and changing scenes, affecting the image quality. In addition, when shooting multiple frames, in order to retain the highlight details as much as possible, the exposure time of the shortest exposure frame is very short, which will cause flickering stripes (banding) when shooting LED light sources;

[0113] In other related technologies, two frames of images are output for the same pixel, namely, a low-gain image and a high-gain image, wherein the low-gain image is a shorter exposure image, and the high-gain image is a longer exposure image. Finally, the two frames of images are fused into a high-dynamic image through a fusion algorithm. However, since the pixel signal needs to be read multiple times, the readout time and data volume increase, thereby reducing the frame rate and increasing power consumption.

[0114] In the embodiment of the present application, since the total current converted by the photodiode is equal to the sum of the first partial current obtained by the output module and the second partial current obtained by each conductive shunt module, the more shunt modules are turned on, the smaller the first partial current obtained by the output module, and the smaller the output voltage. Since the number of conductive shunt modules is positively correlated with the current value of the total current converted by the photodiode, when the total converted current increases, the number of conductive shunt modules increases, so that the first partial current obtained by the output module decreases. Therefore, the increase in output voltage caused by the increase in total current can be reduced. Compared with the related art, the pixel image is prevented from being too bright and the clarity of the pixel image is improved. In addition, through the embodiment of the present application, ghost images that are easily generated in complex and changeable scenes due to the fusion of multi-frame image algorithms into high-dynamic images can be avoided, and there is no problem of reduced frame rate and increased power consumption due to multiple readings of pixel signals. In addition, the embodiment of the present application can realize adaptive HDR function, and its readout circuit is simpler than traditional DCG technology.

[0115] To summarize, in the embodiment of the present application, since the total current converted by the photodiode is equal to the sum of the first partial current obtained by the output module and the second partial current obtained by each conductive shunt module, the more shunt modules are turned on, the smaller the first partial current obtained by the output module, and the smaller the output voltage. Since the number of conductive shunt modules is positively correlated with the current value of the total current converted by the photodiode, when the total converted current increases, the number of conductive shunt modules increases, thereby reducing the first partial current obtained by the output module. Therefore, the increase in output voltage caused by the increase in total current can be reduced. Compared with the related art, it avoids the pixel image from being too bright and improves the clarity of the pixel image.

[0116] Figure 7 is a flowchart of a pixel circuit control method provided by an embodiment of the present application. The pixel circuit control method is executed by the electronic device as described above. Figure 7 As shown, the method may include:

[0117] Step 101: Obtain the voltage value of the cathode of the photodiode.

[0118] The implementation method of this step is similar to the above implementation process and will not be repeated here.

[0119] Specifically, the voltage value of the cathode of the photodiode is collected by a voltage collection module in the electronic device, and the voltage value of the cathode is acquired by a processor in the electronic device.

[0120] Step 202: Control a shunt module that matches the voltage value of the cathode to be turned on.

[0121] The number of the shunt modules that match the voltage value of the cathode is negatively correlated with the voltage value of the cathode.

[0122] The implementation method of this step is similar to the above implementation process and will not be repeated here.

[0123] Specifically, the processor in the electronic device controls the shunt module that matches the voltage value of the cathode to be turned on.

[0124] It should be noted that, when the conduction parameter of the first switching device in the shunt module is greater than the voltage value of the cathode of the photodiode, the shunt module is determined to match the voltage value of the cathode. Therefore, in the shunt module that matches the voltage value of the cathode, the conduction parameter of the first switching device is greater than the voltage value of the cathode of the photodiode, that is, the difference between the voltage value of the control signal of the first switching device and the conduction threshold of the first switching device is greater than the voltage value of the cathode of the photodiode.

[0125] In an embodiment of the present application, by obtaining the voltage value of the cathode of the photodiode, and then controlling the shunt module matching the voltage value of the cathode to be turned on, since the number of shunt modules matching the voltage value of the cathode is negatively correlated with the voltage value of the cathode, and the voltage value of the cathode is negatively correlated with the total current value converted by the photodiode, when the total converted current increases, the voltage value of the cathode decreases, and the number of shunt modules that are turned on increases, thereby reducing the first branch current obtained by the output module. Therefore, the increase in output voltage caused by the increase in total current can be reduced. Compared with the related art, it avoids the pixel image from being too bright and improves the clarity of the pixel image.

[0126] 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.

[0127] 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.

[0128] 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. A pixel circuit, characterized in that: include: A photodiode (10), an output module (20) and at least two current splitting modules (30); The photodiode (10) is electrically connected to the output module (20) and each current shunt module (30); the total current converted by the photodiode (10) is equal to the sum of a first current shunt and a second current shunt; the first current shunt is the current shunt input by the photodiode (10) to the output module (20), and the second current shunt is the current shunt input by the photodiode (10) to the conducting current shunt module (30); the output module (20) is used to convert the first current shunt into a voltage and output it; The number of the conducting shunt modules (30) is positively correlated with the current value of the total current.

2. The pixel circuit according to claim 1, characterized in that: Each of the current shunt modules (30) comprises a first switch device (Q1), a second switch device (Q2) and a first capacitor (C1); The anode of the photodiode (10) is grounded, and the cathode of the photodiode (10) is electrically connected to the input end of the output module (20) and the first end of each of the first switching devices (Q1) respectively; In the shunt module (30), the second end of the first switch device (Q1) is electrically connected to the first end of the first capacitor (C1), and the control end of the first switch device (Q1) is used to receive a control signal; the first end of the second switch device (Q2) is used to electrically connect to an external power supply, the second end of the second switch device (Q2) is grounded, the control end of the second switch device (Q2) is electrically connected to the first end of the first capacitor (C1); and the second end of the first capacitor (C1) is grounded.

3. The pixel circuit according to claim 2, characterized in that: Each first switch device (Q1) has a corresponding conduction parameter, wherein the conduction parameter is a difference between a voltage value of a control signal of the first switch device (Q1) and a conduction threshold of the first switch device (Q1); At least some of the first switching devices (Q1) have different conduction parameters; When the voltage value at the cathode of the photodiode (10) is less than the conduction parameter of the first switch device (Q1), the first switch device (Q1) is turned on; when the voltage value at the cathode of the photodiode (10) is greater than the conduction parameter of the first switch device (Q1), the first switch device (Q1) is turned off.

4. The pixel circuit according to claim 2, characterized in that: The pixel circuit also includes a reset switch device (Q4); The first end of the reset switch device (Q4) is used to be electrically connected to the external power supply, the second end of the reset switch device (Q4) is respectively electrically connected to the first end of each first switch device (Q1), and the control end of the reset switch device (Q4) is used to receive a reset signal.

5. The pixel circuit according to claim 4, characterized in that: The reset switch device (Q4), the first switch device (Q1) and the second switch device (Q2) are all transistors.

6. The pixel circuit according to claim 1, characterized in that: The output module (20) comprises a second capacitor (C2) and an output submodule (21); The anode of the photodiode (10) is grounded, and the cathode of the photodiode (10) is electrically connected to the first end of the second capacitor (C2) and the input end of each shunt module (30) respectively; The input end of the output submodule (21) is electrically connected to the first end of the second capacitor (C2), and the output submodule (21) is used to convert and output the voltage of the second capacitor (C2); A second end of the second capacitor (C2) is grounded.

7. The pixel circuit according to claim 6, characterized in that: The output submodule (21) comprises a third switch device (Q3) and a selection switch device (Q5); A first end of the third switch device (Q3) is electrically connected to an external power source, and a second end of the third switch device (Q3) is electrically connected to a first end of the selection switch device (Q5); The control end of the selection switch device (Q5) is used to receive a pixel row selection signal, and the second end of the selection switch device (Q5) is used to output a voltage converted from the voltage of the second capacitor (C2).

8. The pixel circuit according to claim 7, characterized in that: The third switch device (Q3) and the selection switch device (Q5) are both transistors.

9. An image sensor, characterized in that: The method comprises the pixel circuit as claimed in any one of claims 1 to 8.

10. A camera module, characterized in that: Comprising the image sensor as claimed in claim 9.

11. An electronic device, characterized in that: Comprising the camera module as claimed in claim 10.

12. A pixel circuit control method, executed by the electronic device according to claim 11, characterized in that: The method comprises: Obtaining a voltage value of a cathode of the photodiode; Controlling a shunt module that matches the voltage value of the cathode to be turned on; The number of the shunt modules that match the voltage value of the cathode is negatively correlated with the voltage value of the cathode.

Images