Pixel circuit, image sensor, and electronic device

Abstract

The invention provides a pixel circuit, an image sensor and electronic equipment. The pixel circuit comprises a photodiode; the first transmission unit is used for controlling connection and disconnection between the photodiode and the first floating diffusion node, so that the first floating diffusion node generates a first photosensitive signal; the second transmission unit is used for controlling connection and disconnection between the photodiode and a second floating diffusion node, so that the second floating diffusion node generates a second photosensitive signal; wherein the first photosensitive signal is configured to be converted into an image signal, and the second photosensitive signal is configured to be converted into a flicker signal. The image sensor and the Flicker sensor are fused, so that the cost of the camera system is reduced, and the phenomenon that the detected flicker frequency of the flicker light source is different from the flicker frequency of the flicker light source received by the image sensor can be avoided.

Description

Technical Field

[0001] The present application relates to the field of camera technology, and in particular to a pixel circuit, an image sensor and an electronic device. Background Art

[0002] At present, there may be a phenomenon of flickering light source when the camera module is taking pictures. For example, the flickering light source may include the ambient light in the scene (such as AC fluorescent lamp), and for another example, the flickering light source may include the photographed object itself (such as a computer screen). In order to prevent the camera module from being affected by the flickering light source, it is usually necessary to set a sensor (Flicker sensor) for detecting the flickering frequency of the flickering light source. After detecting the flickering frequency of the flickering light source, the camera module is guided to set a reasonable exposure time according to the flickering frequency of the flickering light source, thereby avoiding the shooting process from being affected by the flickering light source.

[0003] However, in the related art, the Flicker sensor is usually separated from the image sensor, which leads to a large difference in the field of view of the Flicker sensor and the image sensor during shooting. As a result, the flicker frequency of the flicker light source detected by the Flicker sensor is actually different from the flicker frequency of the flicker light source received by the image sensor. Ultimately, after changing the exposure time of the camera module, the camera module is still affected by the flicker light source. Summary of the invention

[0004] The present application provides a pixel circuit, an image sensor and an electronic device to solve the above technical problems.

[0005] In a first aspect, the present application provides a pixel circuit, comprising:

[0006] Photodiode, a photodiode is used to sense light and generate photocurrent;

[0007] A first transmission unit, the first transmission unit is used to control the conduction and cutoff between the photodiode and the first floating diffusion node, so that the first floating diffusion node generates a first light-sensing signal related to the light intensity based on the photocurrent;

[0008] A second transmission unit, the second transmission unit is used to control the conduction and cutoff between the photodiode and the second floating diffusion node, so that the second floating diffusion node generates a second light-sensing signal related to the light intensity based on the photocurrent;

[0009] The first photosensitive signal is configured to be converted into an image signal, and the second photosensitive signal is configured to be converted into a flickering signal.

[0010] In some embodiments, the first light-sensing signal and the second light-sensing signal are not generated at the same time.

[0011] In some embodiments, during the process in which the first transmission unit controls the photodiode and the first floating diffusion node to be turned on to generate the first light-sensing signal, the second transmission unit controls the photodiode and the second floating diffusion node to be turned off;

[0012] In the process that the second transmission unit controls the photodiode and the second floating diffusion node to be turned on to generate the second light sensing signal, the first transmission unit controls the photodiode and the first floating diffusion node to be turned off.

[0013] In some embodiments, the pixel circuit further includes a first output unit;

[0014] The first output unit is used to output an image signal according to a first light-sensing signal of the first floating diffusion node, and the second light-sensing signal is read by an external amplifying circuit to output a flickering signal.

[0015] In some embodiments, the pixel circuit further includes a first output unit and a second output unit;

[0016] The first output unit is used to output an image signal according to a first light-sensing signal of a first floating diffusion node, and the second output unit is used to output a flicker signal according to a second light-sensing signal of a second floating diffusion node.

[0017] In some embodiments, during the process in which the second transmission unit controls the photodiode and the second floating diffusion node to conduct to generate the second light-sensing signal, the first output unit outputs the image signal according to the first light-sensing signal of the first floating diffusion node;

[0018] In the process that the first transmission unit controls the photodiode and the first floating diffusion node to be turned on to generate the first light sensing signal, the second output unit outputs the flicker signal according to the second light sensing signal of the second floating diffusion node.

[0019] In some embodiments, during the process in which the first output unit outputs an image signal according to the first photosensitive signal of the first floating diffusion node, the second transmission unit controls the conduction between the photodiode and the second floating diffusion node to generate a second photosensitive signal, and the second output unit outputs a flashing signal according to the second photosensitive signal of the second floating diffusion node.

[0020] In some embodiments, before the first output unit outputs the image signal according to the first light-sensing signal of the first floating diffusion node, the first transmission unit intermittently conducts the photodiode and the first floating diffusion node, and the second transmission unit intermittently conducts the photodiode and the second floating diffusion node;

[0021] After the second transmission unit conducts the photodiode and the second floating diffusion node each time, the second output unit outputs a flickering signal according to the second light-sensing signal of the second floating diffusion node.

[0022] In some embodiments, when the first transmission unit controls the photodiode and the first floating diffusion node to conduct to generate the first light sensing signal for odd or even times, the second output unit outputs the flickering signal according to the second light sensing signal of the second floating diffusion node.

[0023] In some embodiments, the first transmission unit includes a first transistor and the second transmission unit includes a second transistor;

[0024] A first terminal of the first transistor is connected to the photodiode, and a second terminal of the first transistor is connected to the first floating diffusion node;

[0025] A second end of the second transistor is connected to the photodiode, and a second end of the second transistor is connected to the second floating diffusion node;

[0026] The control end of the first transistor is used to access a first control signal, and the control end of the second transistor is used to access a second control signal.

[0027] In some embodiments, the first output unit includes a first reset transistor, a first amplifying transistor, and a first output transistor;

[0028] A first end of the first reset transistor is connected to the power supply end, a second end of the first reset transistor is connected to the first floating diffusion node, and a control end of the first reset transistor is used to access a first reset signal;

[0029] A first terminal of the first amplifying transistor is connected to a power supply terminal, a control terminal of the first amplifying transistor is connected to a first floating diffusion node, and a second terminal of the first amplifying transistor is connected to a first terminal of the first output transistor;

[0030] The control end of the first output transistor is used to receive the first scanning signal, and the second end of the first output transistor is used to output the image signal.

[0031] In some embodiments, the second output unit includes a second reset transistor, a second amplifying transistor, and a second output transistor;

[0032] A first end of the second reset transistor is connected to the power supply end, a second end of the second reset transistor is connected to the second floating diffusion node, and a control end of the second reset transistor is used to access a second reset signal;

[0033] A first terminal of the second amplifying transistor is connected to the power supply terminal, a control terminal of the second amplifying transistor is connected to the second floating diffusion node, and a second terminal of the second amplifying transistor is connected to the first terminal of the second output transistor;

[0034] The control end of the second output transistor is used for receiving the second scanning signal, and the second end of the second output transistor is used for outputting the flashing signal.

[0035] In a second aspect, the present application provides an image sensor comprising a plurality of pixel regions arranged in an array, wherein at least one pixel region comprises the pixel circuit as described in the first aspect.

[0036] In a third aspect, the present application provides an electronic device comprising the image sensor as described in the second aspect.

[0037] The present application controls the conduction and cutoff between the photodiode and the first floating diffusion node through the first transmission unit, so that the first floating diffusion node can generate a first photosensitive signal related to the light intensity based on the photogenerated current; at the same time, the conduction and cutoff between the photodiode and the second floating diffusion node can be controlled by the second transmission unit, so that the second floating diffusion node can generate a second photosensitive signal related to the light intensity based on the photogenerated current; because the first photosensitive signal is configured to be converted into an image signal and the second photosensitive signal is configured to be converted into a flicker signal, the image signal can be used to obtain image information, and the flickering frequency of the flickering light source can be detected by using the flicker signal, thereby realizing the fusion of the image sensor and the Flicker sensor, which is not only conducive to reducing the cost of the camera system, but also when the image sensor including the pixel circuit of the present application captures an image, the flickering frequency of the flickering light source, that is, the flickering frequency of the flickering light source in the shooting scene, is detected, and the phenomenon that the flickering frequency of the flickering light source detected by the Flicker sensor is different from the flickering frequency of the flickering light source received by the image sensor due to the separation of the Flicker sensor and the image sensor can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 is a schematic diagram of a camera module provided in an embodiment of the present application;

[0040] Figure 2 is a schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0041] Figure 3 is another schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0042] Figure 4 is another schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0043] Figure 5is another schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0044] Figure 6 is another schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0045] Figure 7 is another schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0046] Figure 8 is another schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0047] Fig. 9 is another schematic diagram of a pixel circuit provided in an embodiment of the present application;

[0048] Fig.10 This is a sequential schematic diagram of exposure and reading of a pixel circuit provided in an embodiment of the present application;

[0049] Fig.11 is another sequential schematic diagram of exposure and reading of a pixel circuit provided in an embodiment of the present application;

[0050] Fig.12 is another sequential schematic diagram of exposure and reading of a pixel circuit provided in an embodiment of the present application;

[0051] Fig.13 This is another sequential schematic diagram of exposure and reading of a pixel circuit provided in an embodiment of the present application.

[0052] Among them, 10 is a first transmission unit, 20 is a second transmission unit, 30 is a first output unit, and 40 is a second output unit;

[0053] Photodiode PD, first floating diffusion node FD1, second floating diffusion node FD2, first light sensing signal VPD1, second light sensing signal VPD2;

[0054] A first transistor M1, a second transistor M2, a first reset transistor Ms1, a first amplifying transistor Ma1, a first output transistor Mo1, a second reset transistor Ms2, a second amplifying transistor Ma2, and a second output transistor Mo2;

[0055] A first control signal TX1, a second control signal TX2, a first reset signal RST1, a second reset signal RST2, a first scan signal SD2, and a second scan signal SD2. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0057] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0058] In this application, the word "exemplary" is used to mean "serving as an example, illustration, or illustration." Any embodiment described in this application as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is given to enable any person skilled in the art to implement and use the invention. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the invention can be implemented without using these specific details. In other instances, well-known structures and processes are not elaborated in detail to avoid obscuring the description of the invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0059] The embodiments of the present application provide a pixel circuit, an image sensor, and an electronic device, which are described in detail below.

[0060] First, see Figure 1 , Figure 1 A schematic diagram of a camera module in an embodiment of the present application is shown, wherein the camera module includes a plurality of pixel circuits 100 arranged in an array, a row scanning circuit 200, a column reading circuit 300 and an image processor 400.

[0061] Specifically, each pixel circuit 100 can sense light reflected or emitted by an object (i.e., a target to be photographed) and generate an image signal, or generate an image signal and a flicker signal, so that the image processor 400 generates a frame of image based on the image signal and determines the flickering frequency of the flickering light source based on the flickering signal.

[0062] The row scanning circuit 200 is connected to each row of pixel circuits 100 through row scanning lines to control each row of pixel circuits 100. For example, the row scanning circuit 200 can control whether each row of pixel circuits 100 outputs an image signal and / or a flicker signal through the row scanning lines; for another example, the row scanning circuit 200 can control whether each row of pixel circuits 100 is exposed through the row scanning lines; for another example, the row scanning circuit 200 can control whether each row of pixel circuits is reset through the row scanning lines.

[0063] The column reading circuit 300 is connected to a plurality of columns of pixels through column reading lines to read the image signal and flicker signal output by each row of pixel circuits. For example, when the row scanning circuit 200 controls the pixel circuits in the Nth row to output an image signal, the column reading circuit 300 reads the image signal output by each column of the pixel circuits in the Nth row through the column reading lines; for another example, when the row scanning circuit 200 controls the pixel circuits in the N+1th row to output an image signal, the column reading circuit 300 reads the image signal output by each column of the pixel circuits in the N+1th row through the column reading lines.

[0064] Exemplarily, the column reading circuit 300 may include an amplifier circuit, an analog-to-digital converter (ADC), a latch circuit or a buffer circuit for temporarily storing digital signals, etc. The image signal or the flicker signal can be amplified by the amplifier circuit, and the analog-to-digital converter can convert the amplified image signal or flicker signal into a digital signal, and the digital signal can be temporarily stored by the latch circuit or the buffer circuit to facilitate the image processor 400 to process the digital signal.

[0065] The image processor 400 may perform signal processing on the image data output from the column reading circuit 300, and may output the signal-processed data to a display device or the like, or may store the signal-processed data in a storage device such as a memory. In some embodiments of the present application, after the image processor 400 determines the flickering frequency of the flickering light source according to the flickering signal, the image processor 400 may control the row scanning circuit 200 to change the exposure time of the pixel circuit 100.

[0066] The following is an introduction to the pixel circuit of the present application. Figure 2 , Figure 2 A schematic diagram of a pixel circuit in an embodiment of the present application is shown, wherein the pixel circuit includes a photodiode PD, a first transmission unit 10 , a second transmission unit 20 , a first output unit 30 and a second output unit 40 .

[0067] Specifically, the photodiode PD is used to sense light (eg, light reflected or emitted by a photographic target) and generate a photocurrent, so that the first floating diffusion node FD1 and the second floating diffusion node FD2 generate corresponding light-sensing signals through the photocurrent.

[0068] The first transmission unit 10 is used to control the conduction and cutoff between the photodiode PD and the first floating diffusion node FD1, so that the first floating diffusion node FD1 generates a first photosensitive signal VPD1 related to the light intensity based on the photocurrent; the second transmission unit 20 is used to control the conduction and cutoff between the photodiode PD and the second floating diffusion node FD2, so that the second floating diffusion node FD2 generates a second photosensitive signal VPD2 related to the light intensity based on the photocurrent. Exemplarily, the first transmission unit 10 and the first transmission unit 10 may include but are not limited to transistors with switching functions such as MOS tubes, triodes, and JEFT tubes, so as to control the conduction and cutoff between the photodiode PD and the corresponding floating diffusion node through the transistor.

[0069] As an example, see Figure 3 , Figure 3 Another schematic diagram of the pixel circuit in an embodiment of the present application is shown, wherein the first transmission unit 10 includes a first transistor M1, and the second transmission unit 20 includes a second transistor M2; the first end of the first transistor M1 is connected to the photodiode PD, and the second end of the first transistor M1 is connected to the first floating diffusion node FD1; the second end of the second transistor M2 is connected to the photodiode PD, and the second end of the second transistor M2 is connected to the second floating diffusion node FD2; wherein the control end of the first transistor M1 is used to access the first control signal TX1, and the control end of the second transistor M2 is used to access the second control signal TX2.

[0070] For example, taking the first transistor M1 and the second transistor M2 as NMOS tubes, when the first control signal TX1 is at a high level and the second control signal TX2 is at a low level, the first transistor M1 is turned on and the second transistor M2 is turned off, so that the photodiode PD and the first floating diffusion node FD1 are turned on, so that the first floating diffusion node FD1 generates a first photosensitive signal VPD1 related to the light intensity based on the photogenerated current; conversely, when the first control signal TX1 is at a low level and the second control signal TX2 is at a high level, the first transistor M1 is turned off and the second transistor M2 is turned on, so that the photodiode PD and the second floating diffusion node FD2 are turned on, so that the second floating diffusion node FD2 generates a second photosensitive signal VPD2 related to the light intensity based on the photogenerated current.

[0071] In the embodiment of the present application, the present application controls the conduction and cutoff between the photodiode PD and the first floating diffusion node FD1 through the first transmission unit 10, so that the first floating diffusion node FD1 can generate a first photosensitive signal VPD1 related to the light intensity based on the photogenerated current; at the same time, the conduction and cutoff between the photodiode PD and the second floating diffusion node FD2 can be controlled by the second transmission unit 20, so that the second floating diffusion node FD2 can generate a second photosensitive signal VPD2 related to the light intensity based on the photogenerated current; because the first photosensitive signal is configured to be converted into an image signal and the second photosensitive signal is configured to be converted into a flicker signal, the image signal can be used to obtain image information, and the flicker signal can be used to detect the flicker frequency of the flicker light source, thereby realizing the fusion of the image sensor and the Flicker sensor, which is not only conducive to reducing the cost of the camera system, but also when the image sensor including the pixel circuit of the present application collects an image, the flicker frequency of the flicker light source, that is, the flicker frequency of the flicker light source in the shooting scene, is detected, and the phenomenon that the flicker frequency of the flicker light source detected by the Flicker sensor is different from the flicker frequency of the flicker light source received by the image sensor due to the separation of the Flicker sensor and the image sensor can be avoided.

[0072] In some embodiments of the present application, see Figure 4 , Figure 4 Another schematic diagram of the pixel circuit in the embodiment of the present application is shown, wherein the pixel circuit 100 further includes a first output unit 30; the first output unit 30 is used to output an image signal according to the first photosensitive signal VPD1 of the first floating diffusion node FDA, and the second photosensitive signal VPD2 is output by an external amplification circuit 1 (for example Figure 1 For example, the first output unit 30 can amplify the first light-sensing signal VPD1 and output it as an image signal, and the external amplifier circuit 1 can amplify the second light-sensing signal VPD2 and output it as a flicker signal.

[0073] As an example, see Figure 5 , Figure 5 Another schematic diagram of the pixel circuit in the embodiment of the present application is shown, wherein the external amplifier circuit 1 includes an operational amplifier OP and an integrating capacitor CI, the non-inverting input terminal of the operational amplifier OP is connected to the reference voltage Vref, the operational amplifier OP and the integrating capacitor CI form an integrator, so when the second transistor M2 is turned on, the integrator can integrate the photocurrent of the photodiode PD, and can output a flashing signal when the second transistor M2 is turned off.

[0074] The first output unit 30 includes a first reset transistor Ms1, a first amplifying transistor Ma1 and a first output transistor Mo1; a first end of the first reset transistor Ms1 is connected to a power supply end, a second end of the first reset transistor Ms1 is connected to a first floating diffusion node FD1, and a control end of the first reset transistor Ms1 is used to access a first reset signal RST1; a first end of the first amplifying transistor Ma1 is connected to a power supply end, a control end of the first amplifying transistor Ma1 is connected to a first floating diffusion node FD1, and a second end of the first amplifying transistor Ma1 is connected to a first end of the first output transistor Mo1; a control end of the first output transistor Mo1 is used to access a first scanning signal SD2, and a second end of the first output transistor Mo1 is used to output an image signal.

[0075] Taking the first reset transistor Ms1, the first amplifying transistor Ma1 and the first output transistor Mo1 as PMOS tubes as an example, when the first reset signal RST1 is at a low level and the first scanning signal SD2 is at a high level, the first reset transistor Ms1 is turned on and the first output transistor Mo1 is turned off, so the power supply voltage VDD resets and charges the first floating diffusion node FD1 to the voltage VDD; and after the first floating diffusion node FD1 generates a first photosensitivity signal VPD1 related to the light intensity based on the photogenerated current, when the first reset signal RST1 is at a high level and the first scanning signal SD2 is at a low level, the first reset transistor Ms1 is turned off and the first output transistor Mo1 is turned on, and since the impedance of the first amplifying transistor Ma1 is controlled by the first photosensitivity signal VPD1, the second end of the first amplifying transistor Ma1 can output a voltage signal related to the size of the first photosensitivity signal VPD1, and finally after the first output transistor Mo1 is turned on, the second end of the first output transistor Mo1 outputs an image signal.

[0076] In some embodiments of the present application, see Figure 6 , Figure 6 Another schematic diagram of a pixel circuit in an embodiment of the present application is shown, wherein the pixel circuit further includes a first output unit 30 and a second output unit 40, the first output unit 30 is used to output an image signal according to a first photosensitive signal VPD1 of a first floating diffusion node FD1, and the second output unit 40 is used to output a flicker signal according to a second photosensitive signal VPD2 of a second floating diffusion node FD2. In some embodiments of the present application, the first output unit 30 can amplify the first photosensitive signal VPD1 and output it as an image signal, and the second output unit 40 can amplify the second photosensitive signal VPD2 and output it as a flicker signal. In other embodiments of the present application, the first output unit 30 can directly output the first photosensitive signal VPD1 as an image signal, and the second output unit 40 can directly output the second photosensitive signal VPD2 as a flicker signal.

[0077] As an example, see Figure 7 , Figure 7 Another schematic diagram of the pixel circuit in the embodiment of the present application is shown, wherein the first output unit 30 includes a first reset transistor Ms1, a first amplifying transistor Ma1 and a first output transistor Mo1; the first end of the first reset transistor Ms1 is connected to the power supply end, the second end of the first reset transistor Ms1 is connected to the first floating diffusion node FD1, and the control end of the first reset transistor Ms1 is used to access the first reset signal RST1; the first end of the first amplifying transistor Ma1 is connected to the power supply end, the control end of the first amplifying transistor Ma1 is connected to the first floating diffusion node FD1, and the second end of the first amplifying transistor Ma1 is connected to the first end of the first output transistor Mo1; the control end of the first output transistor Mo1 is used to access the first scanning signal SD2, and the second end of the first output transistor Mo1 is used to output the image signal.

[0078] Taking the first reset transistor Ms1, the first amplifying transistor Ma1 and the first output transistor Mo1 as PMOS tubes as an example, when the first reset signal RST1 is at a low level and the first scanning signal SD2 is at a high level, the first reset transistor Ms1 is turned on and the first output transistor Mo1 is turned off, so the power supply voltage VDD resets and charges the first floating diffusion node FD1 to the voltage VDD; and after the first floating diffusion node FD1 generates a first photosensitivity signal VPD1 related to the light intensity based on the photogenerated current, when the first reset signal RST1 is at a high level and the first scanning signal SD2 is at a low level, the first reset transistor Ms1 is turned off and the first output transistor Mo1 is turned on, and since the impedance of the first amplifying transistor Ma1 is controlled by the first photosensitivity signal VPD1, the second end of the first amplifying transistor Ma1 can output a voltage signal related to the size of the first photosensitivity signal VPD1, and finally after the first output transistor Mo1 is turned on, the second end of the first output transistor Mo1 outputs an image signal.

[0079] Likewise, continue to refer to Figure 7, wherein the second output unit 40 includes a second reset transistor Ms2, a second amplifying transistor Ma2 and a second output transistor Mo2; a first end of the second reset transistor Ms2 is connected to the power supply end, a second end of the second reset transistor Ms2 is connected to the second floating diffusion node FD2, and a control end of the second reset transistor Ms2 is used to access the second reset signal RST2; a first end of the second amplifying transistor Ma2 is connected to the power supply end, a control end of the second amplifying transistor Ma2 is connected to the second floating diffusion node FD2, and a second end of the second amplifying transistor Ma2 is connected to the first end of the second output transistor Mo2; the control end of the second output transistor Mo2 is used to access the second scanning signal SD2, and a second end of the second output transistor Mo2 is used to output a flashing signal.

[0080] Taking the second reset transistor Ms2, the second amplifying transistor Ma2 and the second output transistor Mo2 as PMOS tubes as an example, when the second reset signal RST2 is at a low level and the second scanning signal SD2 is at a high level, the second reset transistor Ms2 is turned on and the second output transistor Mo2 is turned off, so the power supply voltage VDD resets and charges the second floating diffusion node FD2 to the voltage VDD; and after the second floating diffusion node FD2 generates a second photosensitivity signal VPD2 related to the light intensity based on the photogenerated current, when the second reset signal RST2 is at a high level and the second scanning signal SD2 is at a low level, the second reset transistor Ms2 is turned off and the second output transistor Mo2 is turned on, and since the impedance of the second amplifying transistor Ma2 is controlled by the second photosensitivity signal VPD2, the second end of the second amplifying transistor Ma2 can output a voltage signal related to the size of the second photosensitivity signal VPD2, and finally after the second output transistor Mo2 is turned on, the second end of the second output transistor Mo2 outputs a flashing signal.

[0081] It should be noted that the first light sensing signal VPD1 and the second light sensing signal VPD2 may be voltage signals or current signals flowing through corresponding floating diffusion nodes. Figure 5 For example, a capacitor is connected in series between the first floating diffusion node FD1 and the ground terminal. When the first transmission unit 10 turns on the photodiode PD and the first floating diffusion node FD1, the photocurrent of the photodiode PD consumes the charge of the capacitor, so that the first floating diffusion node FD1 can generate a first photosensitive signal VPD1 which is a voltage signal based on the photocurrent; and when the second transmission unit 20 turns on the photodiode PD and the second floating diffusion node FD2, the second floating diffusion node FD2 outputs the photocurrent signal as the second photosensitive signal VPD2 to the integrator composed of the operational amplifier OP and the integrating capacitor CI, so that the integrator can integrate the second photosensitive signal VPD2 which is a current signal, and finally output the flashing signal when the second transistor M2 is turned off.

[0082] For example, Figure 7 For example, a capacitor is connected in series between the first floating diffusion node FD1 and the ground terminal, and a capacitor is connected in series between the second floating diffusion node FD2 and the ground terminal. After resetting, the capacitor is charged to the power supply voltage VDD, and the voltage of the first floating diffusion node FD1 and the second floating diffusion node FD2 is the power supply voltage VDD. When the first transmission unit 10 turns on the photodiode PD and the first floating diffusion node FD1, the photocurrent of the photodiode PD consumes the charge of the capacitor, so that the first floating diffusion node FD1 can generate a first photosensitive signal VPD1 related to the light intensity based on the photocurrent; similarly, when the second transmission unit 20 turns on the photodiode PD and the second floating diffusion node FD2, the photocurrent of the photodiode PD consumes the charge of the capacitor, so that the second floating diffusion node FD2 can generate a second photosensitive signal VPD2 related to the light intensity based on the photocurrent.

[0083] Those skilled in the art can understand that Figure 7 The capacitor in the circuit can also be replaced by other equivalent capacitor devices that can temporarily store charge. For example, when the source and drain of the MOS tube are short-circuited, the substrate metal plate and the gate metal plate of the MOS tube can be used as equivalent capacitors. Figure 2 The capacitor in.

[0084] It is worth noting that the above contents about the first output unit 30 and the second output unit 40 are only exemplary embodiments of the present application. Those skilled in the art can make equivalent modified designs for the first output unit 30 and the second output unit 40 under the guidance of the present application. For example, see Figure 8 , Figure 8 Another schematic diagram of the pixel circuit in the embodiment of the present application is shown. The second output unit 40 can use the second output transistor Mo2 to directly output the second light-sensing signal VPD2 as a flashing signal. For another example, refer to Fig. 9 , Fig. 9 Another schematic diagram of a pixel circuit in an embodiment of the present application is shown. Figure 5 The difference is, Figure 5 Adapted to the rolling shutter exposure mode of the image sensor, the first transmission unit 10 also includes a transistor M3 and a storage capacitor C0. The transistor M3 is controlled by a control signal TX3. When the first transistor M1 is turned on and the transistor M3 is turned off, the storage capacitor C0 temporarily stores the photogenerated charges. When the first transistor M1 is turned off and the transistor M3 is turned on, the temporarily stored photogenerated charges are transferred to the first floating diffusion node FD1 and a first photosensitive signal VP1 is generated to adapt to the global exposure mode of the image sensor.

[0085] It should be noted that each transistor used in the embodiments of the present application can be a MOS tube, a JEFT tube or a triode and other transistors with a switching function. At the same time, the first electrode / first end of each transistor used in the embodiments of the present application is one of the source and the drain (or the emitter and the collector), and the second electrode / second end of each transistor is the other of the source and the drain (or the emitter and the collector). The control end of each transistor can refer to the gate / base, etc. Exemplarily, when the transistor is a P-type transistor, the first electrode / first end of the transistor is the source, and the second electrode / second end is the drain; Exemplarily, when the transistor is an N-type transistor, the first electrode / first end of the transistor is the drain, and the second electrode / second end is the source.

[0086] In some embodiments of the present application, the first photosensitive signal VPD1 and the second photosensitive signal VPD2 are not generated at the same time. That is, the photodiode PD is not simultaneously connected to the first floating diffusion node FD1 and the second floating diffusion node FD2, so as to avoid the photodiode PD being simultaneously connected to the first floating diffusion node FD1 and the second floating diffusion node FD2, which causes the first floating diffusion node FD1 and the second floating diffusion node FD2 to fail to accurately generate a photosensitive voltage related to the light intensity, and ultimately generate an erroneous image signal and / or a flicker signal.

[0087] In some embodiments of the present application, during the process in which the first transmission unit 10 controls the photodiode PD and the first floating diffusion node FD1 to be turned on to generate the first light-sensitive signal VPD1, the second transmission unit 20 controls the photodiode PD and the second floating diffusion node FD2 to be turned off; during the process in which the second transmission unit 20 controls the photodiode PD and the second floating diffusion node FD2 to be turned on to generate the second light-sensitive signal VPD2, the first transmission unit 10 controls the photodiode PD and the first floating diffusion node FD1 to be turned off.

[0088] That is to say, in the above embodiment, the photodiode PD is not simultaneously turned on to the first floating diffusion node FD1 and the second floating diffusion node FD2. Therefore, when the first transmission unit 10 controls the photodiode PD and the first floating diffusion node FD1 to be turned on, the first floating diffusion node FD1 can accurately collect the first photosensitive signal VPD1 related to the light intensity; and when the second transmission unit 20 controls the photodiode PD and the second floating diffusion node FD2 to be turned on, the second floating diffusion node FD2 can accurately collect the second photosensitive signal VPD2 related to the light intensity, thereby avoiding the phenomenon that the photodiode PD is simultaneously turned on to the first floating diffusion node FD1 and the second floating diffusion node FD2, resulting in the first floating diffusion node FD1 and the second floating diffusion node FD2 being unable to accurately collect the photosensitive voltage related to the light intensity.

[0089] As an example, see Fig.10 , Fig.10 A sequential schematic diagram of exposure and reading of the pixel circuit in an embodiment of the present application is shown, wherein the first transmission unit 10 controls the photodiode PD and the first floating diffusion node FD1 to be turned on corresponding to the image exposure stage, and the first output unit 30 outputs an image signal corresponding to the image reading stage according to the first photosensitivity signal VPD1 of the first floating diffusion node FD1; the second transmission unit 20 controls the photodiode PD and the second floating diffusion node FD2 to be turned on corresponding to the flashing exposure stage, and the second output unit 40 outputs a flashing signal corresponding to the flashing reading stage according to the second photosensitivity signal VPD2 of the second floating diffusion node FD2.

[0090] exist Fig.10 In the process of the first transmission unit 10 controlling the photodiode PD and the first floating diffusion node FD1 to be turned on to generate the first photosensitivity signal VPD1 (i.e., the image exposure stage), the second output unit 40 outputs a flashing signal according to the second photosensitivity signal VPD2 of the second floating diffusion node FD2 (i.e., the flashing reading stage); and in the process of the second transmission unit 20 controlling the photodiode PD and the second floating diffusion node FD2 to be turned on to generate the second photosensitivity signal VPD2 (i.e., the flashing exposure stage), the first output unit 30 outputs an image signal according to the first photosensitivity signal VPD1 of the first floating diffusion node FD1 (i.e., the image reading stage).

[0091] It can be seen that in the above embodiment, the image exposure stage and the flashing exposure stage are executed alternately, and the image reading stage and the flashing reading stage are also executed alternately, and the flashing exposure and flashing reading of the flashing light source will not affect the image exposure duration and the image reading duration, thereby achieving the purpose of simultaneously acquiring accurate image signals and flashing signals.

[0092] As another example, see Fig.11 , Fig.11 Another sequential schematic diagram of exposure and reading of the pixel circuit in an embodiment of the present application is shown, wherein, in the process of the first output unit 30 outputting an image signal according to the first photosensitive signal VPD1 of the first floating diffusion node FD1 (i.e., the image reading stage), the second transmission unit 20 controls the conduction between the photodiode PD and the second floating diffusion node FD2 to generate a second photosensitive signal VPD2 (i.e., the flashing exposure stage), and the second output unit 40 outputs a flashing signal according to the second photosensitive signal VPD2 of the second floating diffusion node FD2 (i.e., the flashing reading stage).

[0093] That is to say, in the above-mentioned embodiment, during the image reading stage, flash exposure can be performed first so that the second floating diffusion node FD2 generates a second photosensitive signal VPD2, and then a flash signal can be output according to the second photosensitive signal VPD2 of the second floating diffusion node FD2, so that flash exposure and flash signal output can be performed during the image reading stage. Since the flash exposure stage and the image exposure stage do not overlap on the time axis, the flash exposure of the flash light source will not affect the image exposure, so that an accurate image signal can be obtained.

[0094] In some embodiments of the present application, before the first output unit 30 outputs an image signal according to the first photosensitivity signal VPD1 of the first floating diffusion node FD1, the first transmission unit 10 intermittently turns on the photodiode PD and the first floating diffusion node FD1, and the second transmission unit 20 intermittently turns on the photodiode PD and the second floating diffusion node FD2; after each time the second transmission unit 20 turns on the photodiode PD and the second floating diffusion node FD2, the second output unit 40 outputs a flashing signal according to the second photosensitivity signal VPD2 of the second floating diffusion node FD2.

[0095] For example, see Fig.12 , Fig.12 Another sequential schematic diagram of the exposure and reading of the pixel circuit in the embodiment of the present application is shown, wherein, within the working time of a frame of image, the first transmission unit 10 intermittently turns on the photodiode PD and the first floating diffusion node FD1, and the second transmission unit 20 intermittently turns on the photodiode PD and the second floating diffusion node FD2, so there are image exposure stage 1, image exposure stage 2...image exposure stage n, and flashing exposure is performed between any two image exposure stages. Therefore, after completing image exposure stage 1, image exposure stage 2...image exposure stage n, the first output unit 30 can output an image signal according to the first photosensitive signal VPD1 of the first floating diffusion node FD1, and after completing each flashing exposure stage, the second output unit 40 can output a flashing signal according to the second photosensitive signal VPD2 of the second floating diffusion node FD2 in the next image exposure stage.

[0096] It can be seen that in the above embodiment, since the first transmission unit 10 intermittently turns on the photodiode PD and the first floating diffusion node FD1, the second transmission unit 20 intermittently turns on the photodiode PD and the second floating diffusion node FD2, and the first transmission unit 10 and the second transmission unit 20 are not turned on at the same time, it is not only possible to simultaneously obtain accurate image signals and flicker signals, but also possible to increase the frequency of flicker exposure and flicker reading, thereby detecting flicker light sources with higher flicker frequencies.

[0097] In some embodiments of the present application, when the first transmission unit 10 controls the photodiode PD and the first floating diffusion node FD1 to be turned on for odd or even times to generate the first photosensitive signal VPD1, the second output unit 40 outputs a flashing signal according to the second photosensitive signal VPD2 of the second floating diffusion node FD2.

[0098] For example, see Fig.13 , Fig.13 Another sequential schematic diagram of exposure and reading of the pixel circuit in an embodiment of the present application is shown, wherein in the i-th frame image reading stage and the i+1-th frame image reading stage, the second transmission unit 20 controls the photodiode PD and the second floating diffusion node FD2 to be turned on to generate the second photosensitive signal VPD2, and in the i+2-th frame image exposure stage, the second output unit 40 outputs a flickering signal according to the second photosensitive signal VPD2. Assuming that i is an odd number, in the process of the odd number of times the first transmission unit 10 controls the photodiode PD and the first floating diffusion node FD1 to be turned on to generate the first photosensitive signal VPD1, the second output unit 40 outputs a flickering signal according to the second photosensitive signal VPD2 of the second floating diffusion node FD2; assuming that i is an even number, in the process of the even number of times the first transmission unit 10 controls the photodiode PD and the first floating diffusion node FD1 to be turned on to generate the first photosensitive signal VPD1, the second output unit 40 outputs a flickering signal according to the second photosensitive signal VPD2 of the second floating diffusion node FD2.

[0099] It can be seen that in the above embodiment, flashing exposure is performed in the first two image reading stages to ensure the flashing exposure duration, which can not only avoid the influence of the flashing exposure of the flashing light source on the image exposure, but also output a flashing signal once every two image working durations, thereby ensuring the image exposure duration and the flashing exposure duration at the same time to obtain accurate image signals and flashing signals respectively.

[0100] It is worth noting that the above content about the pixel circuit is intended to clearly illustrate the implementation verification process of the present application. Those skilled in the art can make equivalent modified designs under the guidance of the present application. For example, a flashing signal can be output once every three frames of image working time.

[0101] Furthermore, in order to better implement the pixel circuit in the embodiment of the present application, on the basis of the pixel circuit, the present application also provides an image sensor, the image sensor includes a plurality of pixel areas arranged in an array, at least one pixel area includes the pixel circuit as described in any of the above embodiments. Since the image sensor in the embodiment of the present application is provided with the pixel circuit of the above embodiment, it has all the beneficial effects of the above pixel circuit, which will not be described in detail here.

[0102] Furthermore, in order to better implement the image sensor in the embodiment of the present application, on the basis of the image sensor, the present application also provides an electronic device, the electronic device including the image sensor as in any of the above embodiments. Since the image sensor of the electronic device in the embodiment of the present application is provided with the pixel circuit of the above embodiment, it has all the beneficial effects of the above pixel circuit, which will not be described in detail here.

[0103] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0104] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0105] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0106] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0107] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0108] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this application is hereby incorporated by reference in its entirety, except for application history documents that are inconsistent with or conflicting with the content of this application, and documents that limit the broadest scope of the claims of this application (currently or later attached to this application). It should be noted that if the descriptions, definitions, and / or use of terms in the accompanying materials of this application are inconsistent or conflicting with the content described in this application, the descriptions, definitions, and / or use of terms in this application shall prevail.

[0109] The above is a detailed introduction to a pixel circuit, an image sensor and an electronic device provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A pixel circuit, characterized in that: include: A photodiode, the photodiode is used to sense light and generate photocurrent; a first transmission unit, the first transmission unit being used to control conduction and cutoff between the photodiode and the first floating diffusion node, so that the first floating diffusion node generates a first light-sensing signal related to light intensity based on the photo-generated current; a second transmission unit, the second transmission unit being used to control the conduction and cutoff between the photodiode and the second floating diffusion node, so that the second floating diffusion node generates a second light-sensing signal related to light intensity based on the photo-generated current; The first photosensitive signal is configured to be converted into an image signal, and the second photosensitive signal is configured to be converted into a flickering signal.

2. The pixel circuit according to claim 1, wherein: The first light-sensing signal and the second light-sensing signal are not generated at the same time.

3. The pixel circuit according to claim 1, wherein: In the process that the first transmission unit controls the photodiode and the first floating diffusion node to be turned on to generate the first light-sensing signal, the second transmission unit controls the photodiode and the second floating diffusion node to be turned off; In the process that the second transmission unit controls the photodiode and the second floating diffusion node to be turned on to generate the second light-sensing signal, the first transmission unit controls the photodiode and the first floating diffusion node to be turned off.

4. The pixel circuit according to claim 3, characterized in that: The pixel circuit further includes a first output unit; The first output unit is used to output the image signal according to the first light-sensing signal of the first floating diffusion node, and the second light-sensing signal is read by an external amplifying circuit to output the flickering signal.

5. The pixel circuit according to claim 3, characterized in that: The pixel circuit further includes a first output unit and a second output unit; The first output unit is used to output an image signal according to the first light-sensing signal of the first floating diffusion node, and the second output unit is used to output a flicker signal according to the second light-sensing signal of the second floating diffusion node.

6. The pixel circuit according to claim 5, characterized in that: In the process that the second transmission unit controls the photodiode and the second floating diffusion node to be turned on to generate the second light-sensing signal, the first output unit outputs the image signal according to the first light-sensing signal of the first floating diffusion node; In the process that the first transmission unit controls the photodiode and the first floating diffusion node to be turned on to generate the first light-sensing signal, the second output unit outputs the flashing signal according to the second light-sensing signal of the second floating diffusion node.

7. The pixel circuit according to claim 5, characterized in that: During the process in which the first output unit outputs the image signal according to the first photosensitive signal of the first floating diffusion node, the second transmission unit controls the conduction between the photodiode and the second floating diffusion node to generate the second photosensitive signal, and the second output unit outputs the flashing signal according to the second photosensitive signal of the second floating diffusion node.

8. The pixel circuit according to claim 5, characterized in that: Before the first output unit outputs the image signal according to the first light-sensing signal of the first floating diffusion node, the first transmission unit intermittently conducts the photodiode and the first floating diffusion node, and the second transmission unit intermittently conducts the photodiode and the second floating diffusion node; After the second transmission unit turns on the photodiode and the second floating diffusion node each time, the second output unit outputs the flashing signal according to the second light-sensing signal of the second floating diffusion node.

9. The pixel circuit according to claim 5, characterized in that: In the process that the first transmission unit controls the photodiode and the first floating diffusion node to be turned on for odd or even times to generate the first light-sensing signal, the second output unit outputs a flickering signal according to the second light-sensing signal of the second floating diffusion node.

10. The pixel circuit according to claim 5, characterized in that: The first transmission unit includes a first transistor, and the second transmission unit includes a second transistor; A first terminal of the first transistor is connected to the photodiode, and a second terminal of the first transistor is connected to the first floating diffusion node; The second end of the second transistor is connected to the photodiode, and the second end of the second transistor is connected to the second floating diffusion node; The control end of the first transistor is used to access a first control signal, and the control end of the second transistor is used to access a second control signal.

11. The pixel circuit according to claim 10, characterized in that: The first output unit includes a first reset transistor, a first amplifying transistor and a first output transistor; A first end of the first reset transistor is connected to a power supply end, a second end of the first reset transistor is connected to the first floating diffusion node, and a control end of the first reset transistor is used to access a first reset signal; The first end of the first amplifying transistor is connected to the power supply end, the control end of the first amplifying transistor is connected to the first floating diffusion node, and the second end of the first amplifying transistor is connected to the first end of the first output transistor; The control end of the first output transistor is used to receive the first scanning signal, and the second end of the first output transistor is used to output the image signal.

12. The pixel circuit according to claim 10, wherein: The second output unit includes a second reset transistor, a second amplifying transistor and a second output transistor; A first terminal of the second reset transistor is connected to a power supply terminal, a second terminal of the second reset transistor is connected to the second floating diffusion node, and a control terminal of the second reset transistor is used to access a second reset signal; The first terminal of the second amplifying transistor is connected to the power supply terminal, the control terminal of the second amplifying transistor is connected to the second floating diffusion node, and the second terminal of the second amplifying transistor is connected to the first terminal of the second output transistor; The control end of the second output transistor is used to receive the second scanning signal, and the second end of the second output transistor is used to output the flashing signal.

13. An image sensor, characterized in that: The invention comprises a plurality of pixel regions arranged in an array, and at least one pixel region comprises a pixel circuit as claimed in any one of claims 1 to 12.

14. An electronic device, characterized in that: Comprising the image sensor as claimed in claim 13.

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