CN217335685U

CN217335685U - Image sensor pixel, pixel circuit and image sensor

Info

Publication number: CN217335685U
Application number: CN202220881390.8U
Authority: CN
Inventors: 杨靖; 衡佳伟; 任冠京
Original assignee: SmartSens Technology Shanghai Co Ltd
Current assignee: SmartSens Technology Shanghai Co Ltd
Priority date: 2022-04-14
Filing date: 2022-04-14
Publication date: 2022-08-30
Anticipated expiration: 2032-04-14

Abstract

The utility model provides an image sensor pixel, pixel circuit and image sensor, the first pixel in the image sensor pixel acquires first light signal, the second pixel acquires the second light signal; the second pixels are positioned at the set positions of the first pixels so that the first pixels and the second pixels are arranged in a periodic array; the first pixel and the second pixel at the corresponding set position form a pixel unit of an image sensor pixel; the sensitivity of the first photoelectric conversion element in the first pixel is greater than the sensitivity of the second photoelectric conversion element in the second pixel, and the second pixel further comprises an adjusting capacitor, wherein two ends of the adjusting capacitor are coupled to a second floating diffusion point of the second pixel and a control signal so as to adjust the potential of the second floating diffusion point based on the control signal. The utility model discloses a design can effectively adjust the unsteady diffusion zone potential of pixel, can also avoid the scintillation that pulsed light source caused when having high dynamic range to improve the imaging quality of image.

Description

Image sensor pixel, pixel circuit and image sensor

Technical Field

The utility model relates to an image technology especially relates to an image sensor pixel, pixel circuit and image sensor.

Background

The image sensor is an important component constituting the digital camera. Depending on the device, the device can be classified into two categories, CCD (charge coupled device) and CMOS (metal oxide semiconductor device). With the continuous development of CMOS integrated circuit manufacturing processes, especially CMOS image sensor design and manufacturing processes, CMOS image sensors have gradually replaced CCD image sensors as mainstream. Compared with the CMOS image sensor, the CMOS image sensor has the advantages of higher industrial integration level, lower power and the like. Existing standard image sensors have a limited dynamic range of approximately 60dB to 70 dB. However, the dynamic range of real world luminance is much larger. Natural scenes typically span a range of 90dB and above. In addition, in the pixel structure of the conventional image sensor, it is difficult to effectively control the potential at the floating diffusion region.

The LED light source has long service life, high stability, low energy consumption, no pollution, and flexible application, and can form different light color combinations and shapes, so that the LED light source is widely applied to various road lighting and traffic indication devices. However, the LED lamp is generally driven by a pulse signal, and therefore, the LED lamp flickers at a certain operating frequency, which causes an unstable light source and a phenomenon of alternating light and dark. At present, the frequency of the LED light source flickering is usually between 90Hz and 270Hz, and human eyes can only perceive the flickering of the LED light source at the highest 70Hz, so the human eyes cannot perceive the flickering of the LED light source. However, with the rapid development of new energy vehicles and internet of things (IOT) technologies, image sensors gradually begin to assist and even replace human eyes to collect information, and the exposure time of conventional CMOS image sensors is shorter than the operating frequency of LED light sources, so that the flickering phenomenon of LED light sources can be easily captured.

The vehicle-mounted CMOS image sensor can provide information such as target speed, distance, appearance shape and the like for a driver, due to the flickering phenomenon of the LED light source, if exposure time is staggered with the opening time of the LED light source, the CMOS image sensor can output a flickering image, missing or even wrong road condition or identification information can be provided, and further wrong judgment of a system is caused, and driving safety is influenced.

In order to inhibit the flickering phenomenon of the LED light source, the exposure time of the CMOS image sensor is actively increased in a part of application scenes, and the exposure time is made to be larger than the flickering frequency of the LED light source. For a 90Hz LED light source, at least 11ms of long exposure time is needed, which can cause signals to quickly reach a saturation state, reduce the dynamic range of the CMOS image sensor and even cause an overexposure phenomenon, and influence the final imaging quality. In addition, some techniques perform multiple sampling during a long exposure period to prevent overexposure, but this method has a relatively strict requirement on the sampling period, which easily causes the loss of sampling information, and thus cannot completely solve the problem of LED light source flicker.

It should be noted that the above background description is only for the convenience of clear and complete description of the technical solutions of the present application and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the present application.

SUMMERY OF THE UTILITY MODEL

In view of the above-mentioned shortcomings of the prior art, the present invention provides an image sensor pixel, a pixel circuit and an image sensor, which are used for solving the problem of flickering of the LED light source in the prior art.

To achieve the above and other related objects, the present invention provides an image sensor pixel, which includes a first pixel array and a second pixel array;

the first pixel array includes a plurality of first pixels that acquire first light signals;

the second pixel array comprises a plurality of second pixels with the same number as the first pixels, and the second pixels acquire second optical signals;

the second pixels are positioned at the set positions of the first pixels, so that the first pixels and the second pixels are arranged in a periodic array; the first pixel and the second pixel at the set position corresponding to the first pixel form a pixel unit of the image sensor pixel;

the sensitivity of a first photoelectric conversion element in the first pixel is greater than the sensitivity of a second photoelectric conversion element in the second pixel; the second pixel further comprises an adjusting capacitor, one end of the adjusting capacitor is coupled to a second floating diffusion point of the second pixel, and the other end of the adjusting capacitor is connected with a control signal so as to adjust the potential of the second floating diffusion point based on the control signal.

Preferably, the first pixel includes a first photodetecting unit and a first analog output unit; wherein:

the first photoelectric detection unit comprises the first photoelectric conversion element to receive the first optical signal and convert the first optical signal into a first image signal, and an output end of the first photoelectric detection unit is coupled to a first floating diffusion point and used for transferring the first image signal to the first floating diffusion point; an input terminal of the first analog output unit is coupled to the first floating diffusion point for generating a first analog output signal of the first image signal in a quantization mode when the first one of the image sensor pixels is selectively read out;

the second pixel comprises a second photoelectric detection unit and a second analog output unit; wherein:

the second photoelectric detection unit comprises a second photoelectric conversion element to receive the second optical signal and convert the second optical signal into a second image signal, and an output end of the second photoelectric detection unit is coupled to a second floating diffusion point and used for transferring the second image signal to the second floating diffusion point; the input terminal of the second analog output unit is coupled to the second floating diffusion point for generating a second analog output signal of the second image signal in a quantization mode when the second one of the image sensor pixels is selectively read out.

Preferably, the second pixel further includes a second reset unit; one end of the second reset unit is connected with a working power supply, and the other end of the second reset unit is coupled to the second floating diffusion point;

and/or the second photodetecting unit comprises a second transfer transistor and the second photoelectric conversion element; the second photoelectric conversion element is coupled to the second floating diffusion point through the second transfer transistor;

and/or the second analog output unit comprises a second source follower transistor and a second selection transistor; a gate of the second source follower transistor is coupled to the second floating diffusion point for transferring the second image signal from the gate of the second source follower transistor to the source of the second source follower transistor; an input terminal of the second selection transistor is coupled to a source of the second source follower transistor, and an output terminal of the second selection transistor generates the second analog output signal of the second image signal in the quantization mode when the second pixel is selectively read out.

Preferably, the first pixel further comprises a first reset unit, one end of the first reset unit is connected with an operating power supply, and the other end of the first reset unit is coupled to the first floating diffusion point;

and/or the first photoelectric detection unit comprises a first transmission transistor and the first photoelectric conversion element; the first photoelectric conversion element is coupled to the first floating diffusion point through the first transfer transistor;

and/or the first analog output unit comprises a first source follower transistor and a first selection transistor; a gate of the first source follower transistor is coupled to the first floating diffusion for transferring the first image signal from the gate of the first source follower transistor to the source of the first source follower transistor; an input terminal of the first selection transistor is coupled to a source terminal of the first source follower transistor, and an output terminal of the first selection transistor generates the first analog output signal of the first image signal in the quantization mode when the first pixel is selectively read out.

Preferably, the first pixel further includes a gain control unit coupled between the first floating diffusion and the first reset unit, the gain control unit includes a gain control transistor and a gain control capacitor, the gain control transistor is connected between the first floating diffusion and the first reset unit, the gain control capacitor is coupled between the gain control transistor and the first reset unit, and a gate of the gain control transistor receives a gain control command.

Preferably, the second pixel further includes a memory cell having one end coupled to the second floating diffusion point and the other end grounded.

Preferably, the pixel unit includes at least one of the first pixels including one of the first photoelectric conversion elements, the pixel unit includes one of the second pixels including one of the second photoelectric conversion elements;

an area of the first photoelectric conversion element is larger than an area of the second photoelectric conversion element; alternatively, a light-shielding film is provided between the second photoelectric conversion element and incident light.

Preferably, when the second pixel generates the second analog output signal, different control potentials are provided based on the control signal in different control stages to adjust the potential of the second floating diffusion point based on the adjustment capacitance; the control phase comprises an image information transmission phase, an image information quantization phase, a reset phase and a reset signal quantization phase.

Preferably, the second optical signal is an optical signal of a pulsed light source; the exposure time of the second pixel is longer than the flicker period of the pulse light source.

In order to achieve the above and other related objects, the present invention further provides a pixel circuit based on the above image sensor pixel, wherein the pixel circuit comprises a plurality of pixel circuit units corresponding to the pixel units, and each pixel circuit unit comprises a first pixel circuit corresponding to the first pixel and a second pixel circuit corresponding to the second pixel.

To achieve the above and other related objects, the present invention also provides an image sensor including the image sensor pixel as described above; alternatively, the image sensor employs the pixel circuit described above.

Preferably, the image sensor further includes a digital output unit; the input end of the digital output unit receives a first analog output signal and a second analog output signal generated by the image sensor pixel, and the reference input end of the digital output unit receives a ramp signal; the digital output unit generates a first digital signal of the first analog output signal according to the first analog output signal and the ramp signal, and generates a second digital signal of the second analog output signal according to the second analog output signal and the ramp signal.

Preferably, the image sensor further comprises a control unit including a latch unit and a driving unit;

the latch unit receives an exposure row address signal, an exposure row control signal, a read control signal and a read row address signal to generate a latch address signal;

the input end of the driving unit is connected with the output end of the latch unit, and the driving unit sends control signals to the first pixel and/or the second pixel based on the latch address signal, the exposure row control signal, the reading control signal and the reading row address signal so as to control the on-off state of the corresponding component.

Preferably, in the process of controlling the first pixel by the control unit, the transmission transistor and the reset transistor of the idle row are controlled to be turned on, and the reset transistor of the exposure row is controlled to be turned on; and/or controlling the signal transmission transistor and the reset transistor of the idle row to be conducted and controlling the reset transistor of the exposure row to be switched off in the control process of the second pixel.

As described above, the image sensor pixel, the pixel circuit, the image sensor and the control method of the present invention have the following advantages:

the utility model can effectively realize the adjustment of the electric potential of the corresponding floating diffusion region by adjusting the capacitance; in addition, in a scene with a pulse light source, for example, a scene with an LED light source, the photodiode corresponding to the second pixel exposes the LED light source, and the sensitivity of the photodiode corresponding to the second pixel is low, so that the exposure time can be effectively prolonged to ensure the capture of a complete LED pulse, for example, for a long exposure period of 11ms, the overexposure is not easy to occur. The photodiode corresponding to the first pixel is responsible for shooting a conventional scene, has high sensitivity, can clearly image even in dark light, and guarantees the dynamic range of the CMOS image sensor. The image sensor is ensured to have a high dynamic range, and meanwhile flicker caused by the LED light source can be avoided.

Drawings

Fig. 1 is a schematic diagram illustrating an array layout of image sensor pixels according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of an analog output circuit of a pixel circuit according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a digital output circuit of a pixel circuit according to an embodiment of the present invention.

Fig. 4 is a timing diagram illustrating the signal readout quantization of the first pixel circuit according to an embodiment of the present invention.

Fig. 5 is a schematic structural diagram of a control module according to an embodiment of the present invention.

Fig. 6 is a timing diagram illustrating signal readout quantization of a second pixel circuit according to an embodiment of the present invention.

Element number description: 11. a first photoelectric detection module; 12. a first analog output module; 13. a gain control module; 21. a second photoelectric detection module; 22. and the second analog output module.

Detailed Description

The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can be implemented or applied by other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to fig. 1-6. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the invention in a schematic manner, and only the components related to the invention are shown in the drawings rather than being drawn according to the number, shape and size of the components in actual implementation, and the form, quantity and proportion of the components in actual implementation may be changed at will, and the layout of the components may be more complicated.

In order to achieve the above object, the present invention adjusts the layout of the pixels by adding the second pixel array on the basis of the first pixel array in the layout of the conventional pixel array, and the second pixels of the second pixel array are located in the gaps of the second pixels of the first pixel array, thereby forming the layout of the second pixels arranged alternately. The second pixel can be used for acquiring a pulse light source signal, for example, a photodiode corresponding to the second pixel exposes an LED light source, and the sensitivity of the photodiode corresponding to the second pixel is low, so that the exposure time can be effectively prolonged to ensure the capture of a complete LED pulse, and for example, for a long exposure period of 11ms, the overexposure condition is not easy to occur. The photodiode corresponding to the first pixel is responsible for shooting a conventional scene, has high sensitivity, can clearly image even in dark light, and guarantees the dynamic range of the CMOS image sensor.

Based on this technical concept, the utility model provides an image sensor pixel, pixel circuit, image sensor and control method to it is right through following embodiment the utility model discloses a technical scheme carries out detailed introduction.

The first embodiment is as follows:

the utility model provides an image sensor pixel includes first pixel array and second pixel array;

the sensitivity of the first photoelectric conversion element in the first pixel is greater than the sensitivity of the second photoelectric conversion element in the second pixel.

As an example, the second light signal is a light signal of a pulsed light source, e.g., an LED light source signal; the exposure time of the second pixel is longer than the flicker period of the pulse light source.

The utility model discloses an image sensor pixel's new layout mode, because the sensitivity of first photoelectric conversion element is greater than second photoelectric conversion element's in the second pixel sensitivity in the first pixel, consequently in long exposure process, the electric charge of the photoelectric conversion element that the second pixel corresponds can reveal to its second floating diffusion point, and the parasitic capacitance of second floating diffusion point is great, conversion gain is lower, consequently, can follow the control process when the pixel reads out, effectively prolong the flash cycle of the exposure time of second pixel in order to cover the LED light source completely, ensure the seizure of LED pulse promptly, simultaneously to 11 ms's long exposure cycle, the difficult condition that appears overexposure. The first photoelectric conversion element is responsible for shooting of a conventional scene, has high sensitivity, can clearly image even under dark light, and guarantees the dynamic range of the CMOS image sensor.

In addition, the second pixel further comprises an adjusting capacitor, one end of the adjusting capacitor is coupled to the second floating diffusion point, and the other end of the adjusting capacitor is connected with a control signal so as to adjust the potential of the second floating diffusion point based on the control signal.

The utility model can indirectly adjust the potential of the second floating diffusion point by adjusting the capacitance and the control signal connected with the capacitance, and particularly, when the second pixel generates the second analog output signal, different control potentials are provided based on the control signal in different control stages so as to adjust the potential of the second floating diffusion point based on the adjustment capacitance; the control stage may include an image information transmission stage, an image information quantization stage, a reset stage, and a reset signal quantization stage, and may be one or more of the stages. Therefore, the charge transfer of the second photoelectric conversion element to the second floating diffusion point and the operating state of the second source follower transistor at the time of signal readout can be improved.

In an embodiment of the present invention, a deep trench is disposed on a silicon substrate of the image sensor pixel for isolating the first pixel and the second pixel; the deep trench isolation technology is adopted in the silicon substrate, so that charge can be prevented from leaking from the first pixel to the second pixel photodiode, and the phenomenon of halo (Blooming) can be inhibited.

In an embodiment of the present invention, an area of the first photoelectric conversion element is larger than an area of the second photoelectric conversion element; the utility model discloses a sensitivity that the area that sets up first photoelectric conversion element in the first pixel and second photoelectric conversion element in the second pixel realizes first photoelectric conversion element in the first pixel is greater than the sensitivity of second photoelectric conversion element in the second pixel. In another embodiment, a light-shielding film may be provided between the second photoelectric conversion element and the incident light, thereby reducing the sensitivity of the second photoelectric conversion element. The light shielding film may be designed to have a conventional light shielding structure, for example, a light shielding material layer, a metal gate, or the like may be provided between the photoelectric conversion element and the incident light.

In a preferred embodiment of the present invention, the first pixel includes a first photoelectric detection unit and a first analog output unit; wherein: the first photoelectric detection unit comprises the first photoelectric conversion element to receive the first optical signal and convert the first optical signal into a first image signal, and an output end of the first photoelectric detection unit is coupled to a first floating diffusion point and used for transferring the first image signal to the first floating diffusion point; an input terminal of the first analog output unit is coupled to the first floating diffusion point for generating a first analog output signal of the first image signal in a quantization mode when the first one of the image sensor pixels is selectively read out;

the second pixel comprises a second photoelectric detection unit and a second analog output unit; wherein: the second photoelectric detection unit comprises a second photoelectric conversion element to receive the second optical signal and convert the second optical signal into a second image signal, and an output end of the second photoelectric detection unit is coupled to a second floating diffusion point and used for transferring the second image signal to the second floating diffusion point; the input terminal of the second analog output unit is coupled to the second floating diffusion point for generating a second analog output signal of the second image signal in a quantization mode when the second one of the image sensor pixels is selectively read out.

The utility model realizes the conversion of the first optical signal into the first image signal through the first photoelectric detection unit of the first pixel, and outputs the corresponding first analog output signal through the first analog output unit; and the second photoelectric detection unit of the second pixel is used for converting the second optical signal into a second image signal and outputting a corresponding second analog output signal through the second analog output unit.

In a preferred embodiment of the present invention, the first pixel further includes a first reset unit, one end of the first reset unit is connected to a working power supply, and the other end of the first reset unit is coupled to the first floating diffusion point;

the utility model discloses a first reset unit when reseing to first pixel, can empty the photoproduction charge in the idle state pixel line to play anti-halation's effect, also can reset the zero clearing before the quantization is read out, thereby improve the accuracy of the quantization result that analog output signal read out.

Specifically, the first photodetecting unit includes a first transfer transistor and the first photoelectric conversion element; the first photoelectric conversion element is coupled to the first floating diffusion point through the first transfer transistor;

specifically, the first analog output unit includes a first source follower transistor and a first selection transistor; a gate of the first source follower transistor is coupled to the first floating diffusion for transferring the first image signal from the gate of the first source follower transistor to the source of the first source follower transistor; an input terminal of the first selection transistor is coupled to a source terminal of the first source follower transistor, and an output terminal of the first selection transistor generates the first analog output signal of the first image signal in the quantization mode when the first pixel is selectively read out.

In an embodiment of the present invention, the first pixel further includes a gain control unit, the coupling is connected to the first floating diffusion point and between the first reset units, the gain control unit includes a gain control transistor and a gain control capacitor, the gain control transistor is connected to the first floating diffusion point and between the first reset units, the coupling of the gain control capacitor is connected to the gain control transistor and between the first reset units, the gate of the gain control transistor receives a gain control command.

The utility model discloses under gain control unit's effect, can work under low conversion gain mode or high conversion gain mode in the first pixel, thereby realize promoting sensitivity through improving conversion gain under the low light intensity condition, under the strong light condition, promote charge storage capacity through great gain control electric capacity to improve CMOS image sensor's dynamic range.

Here, it should be noted that: the first pixel array can adopt a common or shared pixel structure, and the shared pixel structure is a multiplied by b, the utility model discloses do not do the restriction to the structure of first pixel array.

In another preferred embodiment of the present invention, one of the pixel units includes at least one of the first pixels, the first pixels include one of the first photoelectric conversion elements, the pixel unit includes one of the first pixels, and the second pixels include one of the second photoelectric conversion elements; when a plurality of first photoelectric conversion elements are included, the plurality of first photoelectric conversion elements in the first pixel share one floating diffusion point, which can reduce the number of transistors in a pixel unit. That is, in a pixel unit constituted by the first pixel and the second pixel, that is, in a pixel array formed by the first pixel and the second pixel, the ratio of the second photoelectric conversion element to the first photoelectric conversion element may be 1:1, 2:1, 4:1, or the like.

In one example, the first photoelectric conversion element and the second photoelectric conversion element are both photodiodes, and the pitch of the first pixel is 3 times that of the second pixel. Alternatively, the areas of the respective second photoelectric conversion elements in one pixel unit are equal. Of course, the size of the first pixel and the second pixel and the area of each photodiode can be set according to actual requirements and are not limited to the above examples.

Specifically, as shown in the schematic diagram of the array layout mode of the image sensor pixels in fig. 1, the first pixel array explains the scheme by taking a 2 × 1 shared pixel structure as an example:

the first photo-detection unit of the first pixel includes two photodiodes, i.e., a first photodiode and a second photo-conversion element, which share a first floating diffusion point, so that the number of transistors in the pixel unit can be reduced to maximize a Fill Factor (FF) and a Full Well Capacity (FWC), and the larger FWC enables an image sensor having a better dynamic range and signal-to-noise ratio. There are some gaps in four corners of the photodiode in the first pixel, in the embodiment of the present invention, the second pixel is filled in the upper left corner of the first pixel by using the gaps, so that the utilization rate of the chip can be effectively improved and the area of the first pixel is not increased obviously; therefore, the upper left corner is the set position.

A plurality of the pixel units form pixel rows and pixel columns of a pixel array; the second pixels of the non-edge pixel rows and the edge pixel columns are positioned in the centers of four adjacent first pixels, and the four second pixels are positioned in the four corner gaps of one first pixel; the four adjacent first pixels are respectively a first pixel and a second pixel of an adjacent pixel row, wherein the first pixel and the second pixel are positioned in an adjacent pixel column.

In a preferred embodiment of the present invention, the second pixel further includes a second reset unit; one end of the second reset unit is connected with a working power supply, and the other end of the second reset unit is coupled to the second floating diffusion point;

the utility model discloses a second when the unit that resets the second pixel, can empty the photoproduction charge in the idle state pixel line to play anti-halation's effect, also can reset the zero clearing before the quantization reads out, thereby improve the accuracy of the quantization result that analog output signal read out.

Specifically, the second photodetecting unit includes a second transfer transistor and the second photoelectric conversion element; the second photoelectric conversion element is coupled to the second floating diffusion point through the second transfer transistor;

specifically, the second analog output unit includes a second source follower transistor and a second selection transistor; a gate of the second source follower transistor is coupled to the second floating diffusion point for transferring the second image signal from the gate of the second source follower transistor to the source of the second source follower transistor; an input terminal of the second selection transistor is coupled to a source of the second source follower transistor, and an output terminal of the second selection transistor generates the second analog output signal of the second image signal in the quantization mode when the second pixel is selectively read out.

In an embodiment of the present invention, the second pixel further includes a storage unit, one end of the storage unit is coupled to the second floating diffusion point, and the other end is grounded. The storage unit is specifically a parasitic capacitor and is used for storing the charge amount of the second floating diffusion point. Of course, the storage capacitor may be a device capacitor, and may receive the electric charge generated by the second photoelectric conversion element.

Example two:

the utility model discloses still provide a pixel circuit, pixel circuit is based on the image sensor pixel in embodiment one. The present embodiment focuses on the description of the pixel circuit: the pixel circuit of the present invention includes an analog output circuit as shown in fig. 2, the analog output circuit includes a first pixel circuit and a second pixel circuit;

the first pixel circuit corresponds to the first pixel, and the first pixel circuit comprises a first photoelectric detection module 11, a gain control module 13 and a first analog output module 12; the first photo-detection module 11 receives the first optical signal and converts the first optical signal into a first image signal, and the output terminal is coupled to the first floating diffusion point, for transferring the first image signal to the first floating diffusion point FD 1; the gain control module 13 is coupled to the first floating diffusion point for controlling the quantization mode of the first image signal; an input terminal of the first analog output module 12 is coupled to the first floating diffusion point FD1 for generating a first analog output signal of the first image signal in quantization mode when a first pixel of the image sensor pixels is selected for readout;

the second pixel circuit is used for processing a second pixel, and the second pixel circuit comprises a second photoelectric detection module 21 and a second analog output module 22; the second photo-detection module 21 receives the second optical signal and converts the second optical signal into a second image signal, and the output terminal is coupled to the second floating diffusion point, so as to transfer the second image signal to the second floating diffusion point FD 2; an input of the second analog output module 22 is coupled to the second floating diffusion point FD2 for generating a second analog output signal of the second image signal in quantization mode when a second one of the image sensor pixels is selected for readout.

The utility model discloses a provide pixel circuit matching pixel structure's new layout mode, the realization is read out first light signal and second light signal respectively through first pixel circuit's first analog output module and second pixel circuit's second analog output module. And based on that the sensitivity of the first photoelectric conversion element in the first pixel is greater than that of the second photoelectric conversion element in the second pixel, the charges of the photoelectric conversion element corresponding to the second pixel can leak to the second floating diffusion point of the photoelectric conversion element in the long exposure process, the parasitic capacitance of the second floating diffusion point is large, and the conversion gain is low, so that the exposure time of the second pixel can be effectively prolonged to completely cover the flash period of the pulse (LED) light source in the control process of subsequent pixel reading.

Specifically, the first photodetection module 11 of the first pixel includes two first photoelectric conversion elements, i.e., the first photodiode PD1 and the second photodiode PD2, and the first photodiode PD1 and the second photodiode PD2 share the same first floating diffusion point FD1, so that the number of transistors in the pixel unit can be reduced to maximize a Fill Factor (FF) and a Full Well Capacity (FWC), and the larger FWC enables the image sensor to have a better dynamic range and signal-to-noise ratio. The four corners of the photodiode in the first pixel are provided with partial gaps, and the second pixel is filled in the upper left corner of the first pixel by utilizing the partial gaps, so that the utilization rate of a chip can be effectively improved, and the area of the first pixel cannot be obviously increased. Wherein, the upper left corner is the set position.

In the embodiment of the present invention, the analog output circuit of the pixel circuit includes a first pixel circuit and a second pixel circuit, and the first optical signal and the second optical signal are read out through the first analog output module of the first pixel circuit and the second analog output module of the second pixel circuit respectively, so the output of the first analog output module and the output of the second analog output module are the output of the analog output circuit. As another embodiment, an analog output circuit of a pixel circuit includes a first pixel transfer circuit, a second pixel transfer circuit, and an analog output circuit; at this time, the first pixel circuit includes a first photo-detection module 11 and a gain control module 13, and the second pixel circuit includes a second photo-detection module 21; the input end of the analog output circuit is connected to the output end of the first photoelectric detection module 11 and the output end of the second photoelectric detection module 21, that is, the two photoelectric signals are controlled to be read out through one analog output circuit, so that only one output end of the analog output circuit is provided. Whether there is one or two outputs of the analog output, the first analog output signal and the second analog output signal are read out in a serial or parallel manner and input onto the column bus.

Specifically, the first photodetection module 11 includes a first transfer transistor (M11 and M12) and two first photoelectric conversion elements (PD1 and PD 2); the first photoelectric conversion elements (PD1 and PD2) are coupled to the first floating diffusion point FD1 through the first transfer transistors (M11 and M12);

specifically, the first analog output module 12 includes a first source follower transistor SF1 and a first select transistor RS 1; a gate of the first source follower transistor SF1 is coupled to the first floating diffusion point FD1 for transferring the first image signal from the gate of the first source follower transistor SF1 to the source of the first source follower transistor SF 1; an input terminal of the first selection transistor RS1 is coupled to the source of the first source follower transistor SF1, and an output terminal of the first selection transistor RS1 generates the first analog output signal of the first image signal in the quantization mode when the first pixel is selectively read out.

Specifically, the second photodetection module 21 includes a second transfer transistor M3 and the second photoelectric conversion element PD 3; the second photoelectric conversion element PD3 is coupled to the second floating diffusion point FD2 through the second transfer transistor M3;

specifically, the second analog output module 22 includes a second source follower transistor SF2 and a second select transistor RS 2; a gate of the second source follower transistor SF2 is coupled to the second floating diffusion point FD2 for transferring the second image signal from the gate of the second source follower transistor SF2 to the source of the second source follower transistor SF 2; an input terminal of the second selection transistor RS2 is coupled to the source of the second source follower transistor SF2, and an output terminal of the second selection transistor RS2 generates the second analog output signal of the second image signal in the quantization mode when the second pixel is selectively read out.

In the embodiment of the present invention, the first pixel circuit further includes a gain control module 13, a first reset module and a first parasitic capacitor C _FD1 The first reset module has one end connected to a working power supply and the other end coupled to the first floating diffusion point FD 1; the gain control module 13 is coupled between the first reset module and the first floating diffusion point FD1, and includes a gain control transistor and a gain control capacitor; the first parasitic capacitance C _FD1 Is coupled to the first floating diffusion point FD1, and the other end is grounded; specifically, the first reset module includes a first reset transistor M1, the gate of the first reset transistor M1 receives a reset command, the source of the first reset transistor M1 is connected to the operating power VDD, and the drain of the first reset transistor M1 is connected to the source of the gain control transistor M0 and the gain control capacitor C _dcg One terminal, gain control capacitor C _dcg The other end of the second switch is grounded; the drain of the gain control transistor M0 is connected to the first floating diffusion point FD 1.

In an embodiment of the present invention, the second pixel circuit further includes a second reset module and a second parasitic capacitor C _FD2 (ii) a One end of the second reset module is connected with a working power supply, and the other end of the second reset module is coupled and connected to the second floating diffusion point FD 2; the second parasitic capacitance C _FD2 One end is coupled to the second floating diffusion point FD2, and the other end is grounded; specifically, the second reset module includes a second reset transistor M2, a gate of the second reset transistor M2 receives a reset command, a source of the second reset transistor M2 is connected to the operating power VDD, and a drain of the second reset transistor M2 is connected to the second floating diffusion point FD 2.

In the embodiment of the present invention, the long exposure time improves the second pixel circuitThe difficulty of the read-out quantization of the two analog output signals, in order to ensure the linearity of the analog output signal output by the second pixel circuit, the second pixel circuit further comprises a regulating capacitor C _ref Said regulating capacitance C _ref One end is coupled and connected to the second floating diffusion point FD2, and the other end is connected to a control signal vref; the control signal provides potential voltages of three gears for providing potential voltages of different gears to adjust the potential of the second floating diffusion point when the second pixel module is selected to be read out.

The utility model discloses second floating diffusion point FD2 department at second pixel circuit has added and has adjusted electric capacity C _ref By adjusting the capacitance C _ref The lower plate can provide potential voltage control signals vref of different gears, so that the potential of the second floating diffusion point FD2 can be indirectly adjusted, specifically, when the second pixel circuit is selected to read out the second analog output signal, different control potentials are provided by control signals in different control stages, and the potential of the second floating diffusion point is adjusted by adjusting a capacitor; the control stage comprises an image information transmission stage, an image information quantization stage, a reset stage and a reset signal quantization stage. Therefore, the utility model discloses increased and to have improved the charge transfer and the signal of second light conversion element to the floating diffusion point of second after the regulation electric capacity and read out the operating condition of second source electrode follower transistor, can restrain the halo phenomenon effectively simultaneously.

The utility model discloses first source electrode follower transistor SF1 among the first pixel circuit can cushion output pixel's reset signal V in proper order _rst And an exposure signal V _sig The two signals are fully correlated, and therefore, a Correlated Double Sampling (CDS) operation can be performed at the time of readout, reducing Fixed Pattern Noise (FPN) and kTC noise; during long exposure (e.g., 11ms) of the second pixel circuit, photo-generated charges of the second photo-element PD3 leak to the second floating diffusion point FD2, so that the second pixel circuit cannot perform Correlated Double Sampling (CDS) operation; to improve the read-out quantization efficiency of pixel signals, the quantization reset signal V is reduced _rst And an exposure signal V _sig Time interval of (2), second pixel circuitWill read out the exposure signal V first _sig Reading out reset signal V after reset _rst Correlated double sampling in a non-true sense may be taken.

The pixel circuit of the present invention further includes a digital output circuit as shown in fig. 3, the digital output circuit includes a comparator, a counter and a memory; an analog input end of the comparator receives an analog output signal output by the pixel circuit, the analog output signal is a first analog output signal or a second analog output signal, a reference input end of the comparator receives a ramp signal and is used for comparing the analog output signal with the ramp signal to obtain a comparison result, and a digital quantization result corresponding to the analog output signal is generated based on the comparison result; the counter is configured to generate a count value with respect to time; the memory is configured to store a count value in the counter as the digital quantization result based on a comparison result.

Specifically, an analog input terminal Vinn of the comparator is connected to an output terminal vpixel of the analog output circuit, a reference input terminal Vinp of the comparator receives a ramp signal vramp,

the analog input terminal Vinp of the comparator is connected with the positive output terminal Vop1 of the first stage of the comparator through a first zero clearing switch lcg _ cmp _ az1, and the analog input terminal Vinn of the comparator is connected with the negative output terminal Von1 of the first stage of the comparator through a second zero clearing switch lcg _ cmp _ az 2. Closing a first zero clearing switch lcg _ cmp _ az1 and a second zero clearing switch lcg _ cmp _ az2, and enabling a first-stage positive output end Vop1 to be short-circuited with a reference input end of a first comparator and a first-stage negative output end Von1 to be short-circuited with an analog input end of the first comparator to realize resetting and zero clearing; then, the first clear switch lcg _ cmp _ az1 and the second clear switch lcg _ cmp _ az2 are turned off, the analog output signal and the ramp signal are compared, when the ramp signal falls to overlap with the analog output signal, the comparator jumps to output zero, the count value of the counter at the time of the jump of the output voltage is stored in a memory, and the count value based on the first comparison result or the second comparison result is used as the digital quantization result Dout.

Example three:

to achieve the above technical object, the present invention also provides an image sensor, which includes the image sensor pixels as described above; alternatively, the image sensor employs the pixel circuit described above.

The image sensor of the utility model also comprises a digital output unit; the input end of the digital output unit receives the first analog output signal and the second analog output signal generated by the image sensor pixel, and the reference input end of the digital output unit receives a ramp signal; the digital output unit generates a first digital signal of the first analog output signal according to the first analog output signal and the ramp signal, and generates a second digital signal of the second analog output signal according to the second analog output signal and the ramp signal.

The utility model discloses image sensor's digital output unit carries out digital quantization to the analog output signal of image sensor pixel or pixel circuit output to the digital signal that output analog output signal corresponds.

Specifically, the readout process of the first pixel circuit:

in auto-zero (AZ) stage, the reset signal V of the first pixel circuit is output after the first reset transistor is turned on to complete the reset of the first pixel circuit _rst (ii) a Then closing the zero clearing switches (cmp _ az1 and cmp _ az2) to complete self-reset of the comparator; while the counter needs to be reset. In quantization reset V _rst Stage, the ramp signal vramp begins to fall; setting a signal count _ en of the counter to be high level, and starting to count down by the counter; ramp signal vramp and reset signal V _rst Is coupled to the input ends Vinp and Vinn of the comparator through a capacitor, when Vinp and Vinn are equal, the output of the comparator is inverted from high level to low level, the counter stops counting down, and the digital code value at the moment represents the reset signal V _rst Voltage of (d); when the quantization of the reset signal is finished, the ramp signal vramp returns to the reference state.

In the photo-electronic reading stage, the transfer transistors (TX _ e or/and TX _ o) are controlled to be turned on, all photo-generated charges are transferred from the first photoelectric conversion element to the first floating diffusion point, and then the exposure signal V is buffered by the first source follower transistor _sig . At the quantization exposure V _sig Stage, ramp signal vramp falls again; setting a signal count _ en of the counter to be high level, and starting to count up by the counter; ramp signal vramp and exposure signal V _sig Through the capacitive coupling to the input ends Vinp and Vinn of the comparator, when Vinp and Vinn are overlapped, the comparator is turned over, the counter is triggered to stop counting up, the memory latches the digital code value at the moment, and the code value represents the exposure signal V _sig And a reset signal V _rst I.e. the digital quantization result of the first analog-to-digital signal output by the first pixel circuit.

In the pixel array, for a pixel row in an idle state, the transmission transistor and the reset transistor are continuously turned on to empty photo-generated charges in the corresponding pixel row (the pixel unit in an idle state also receives light), so that an anti-halo (anti-blooming) effect is achieved; meanwhile, the control unit ensures that the transmission transistor in the first pixel circuit maintains a high-level conducting state in an idle state, and the reset transistor is also in a conducting state, so that the halo phenomenon is effectively prevented.

In the pixel array, for a pixel row in idle state (non-reset, non-exposure, non-readout state), the transfer transistor and the reset transistor will be turned on continuously to empty the photo-generated charge in the corresponding pixel row (the pixel cells in idle state will also receive light), thereby acting as anti-blooming.

FIG. 5 is a block diagram of the tx/rst driver, which includes latch units (latches) and gate drivers. The latch unit outputs a latch address signal lat _ tx _ addb to the gate driver according to an exposure row address signal sp _ add, a read row address signal rp _ add, an exposure control signal sp _ tx, a read control signal rp _ tx, and an enable signal lat _ en, thereby controlling the gate driver to output a gate transmission control signal tx. the tx driver ensures that the transmission transistor of the pixel maintains a high-level conducting state in an idle state, and the reset transistor is also in a conducting state, so that the Blooming phenomenon is effectively prevented.

Specifically, the readout process of the second pixel circuit:

before the readout quantization stage begins, the second transfer transistor M3 and the second reset transistor M2 are turned on continuously to empty the charges of the second photoelectric conversion element PD3 and the second floating diffusion point FD2 in the second pixel circuit, so as to perform an anti-halo function; then, the second transfer transistor M3 and the second reset transistor M2 are turned off, the second photoelectric conversion element PD3 starts exposure, and after the exposure is finished, the analog output signal reading quantization stage of the second pixel circuit is started, at this time, the second selection transistor RS2 is at a high level, and the second selection transistor RS2 is turned on.

In the read-out photoelectron/clear stage, the second transfer transistor M3 is closed, the photo-generated charges are completely transferred from the second photoelectric conversion element PD3 to the second floating diffusion point FD2, and the exposure signal V is _sig Buffered onto the column bus via a second source follower transistor SF 2; the resetting of the comparator and the counter is completed simultaneously.

In quantizing the exposure signal V _sig Stage, the ramp signal vramp starts to fall; setting a signal count _ en of the counter to be high level, and starting to count down by the counter; ramp signal vramp and exposure signal V _sig The input end Vinp and Vinn are coupled to the comparator through the capacitor, when Vinp and Vinn are equal, the output of the comparator is turned from a high level to a low level, and the counter stops counting down; when exposure signal V _sig After the quantization is finished, the ramp signal vramp returns to the reference state.

In the FD reset phase, the second reset transistor RST2 is controlled to be turned on, the reset of the second floating diffusion point FD2 is completed, and then the second source follower transistor SF2 buffers the reset signal V _rst . In quantizing reset signal V _rst Stage, ramp signal vramp falls again; setting a signal count _ en of the counter to be high level, and starting to count up by the counter; ramp signal vramp and reset signal V _rst Through capacitive coupling to the inputs Vinp and Vinn of the comparator, when Vinp and Vinn overlap, the comparator flips, triggers the counter to stop counting up, the memory latches the digital code value at that time, which is also representative of the exposure signal V _sig And a reset signal V _rst I.e. digital quantization of the second analog output signal output by the second pixel circuitAnd (6) obtaining the result.

In order to better control the image sensor, the image sensor of the present invention further includes a control unit as shown in fig. 5, wherein the control unit includes a latch unit and a driving unit; the latch unit receives an exposure row address signal, an exposure row control signal, a read control signal and a read row address signal to generate a latch address signal; the input end of the driving unit is connected with the output end of the latch unit, and the driving unit sends control signals to the first pixel and/or the second pixel based on the latch address signal, the exposure row control signal, the reading control signal and the reading row address signal so as to control the on-off state of the corresponding component.

Specifically, in the process of controlling the first pixel based on the control unit, the transmission transistor and the reset transistor of the idle row are controlled to be conducted, and the reset transistor of the exposure row is controlled to be conducted; and in the control process of the second pixel, controlling the conduction of the signal transmission transistor and the reset transistor of the idle row and controlling the turn-off of the reset transistor of the exposure row.

The transfer transistor cannot completely isolate the second photoelectric conversion element and the second floating diffusion point during exposure, charges in the second photoelectric conversion element can continuously leak to the second floating diffusion point, and if the reset transistor is in an on state, the charges generated by exposure of the second photoelectric conversion element can be directly cleared, so that the second reset transistor needs to be turned off by using the control unit during exposure. The latch unit of the control unit also controls the gate driver to output the gate transfer control signal according to the exposure row address signal, the exposure row control signal, the read row address signal, and the output latch address signal to the gate driver.

In order to completely cover the flickering period of the LED light source, the second pixel circuit needs a long exposure time of 11ms, and in order to reduce the influence of the long exposure time on the pixel signal reading, the exposure signal V is read out firstly in the process of the second pixel signal reading quantization _sig Then reading out the reset signal V _rst The method (1).

Example four:

in order to achieve the above and other related objects, the present invention further provides a control method of the image sensor, which includes the steps of, as shown in fig. 4 and 6, quantizing timing diagrams for reading out signals of the first pixel circuit and reading out signals of the second pixel circuit, and the control method of the image sensor at least includes the steps of:

reading out information of the first pixel specifically includes:

resetting a storage area in the first pixel, and quantizing to obtain a first reset signal;

transmitting image information corresponding to the first optical signal acquired by the first pixel, and quantizing to obtain a first image signal;

reading out information of the second pixel specifically includes:

transmitting image information corresponding to the second optical signal acquired by the second pixel, and quantizing to obtain a second image signal;

and obtaining a first actual image signal corresponding to the first pixel based on the first reset signal and the first image signal, and obtaining a second actual image signal corresponding to the second pixel based on the second image signal.

In a preferred embodiment of the present invention, the reading out of the information of the second pixel further includes resetting a storage region in the second pixel, quantizing the storage region to obtain a second reset signal, and obtaining the second actual image signal based on the second reset signal and the second image signal. In the process of reading out the information of the second pixel, acquiring the second image signal first, and then acquiring the second reset signal; in the control process of the image sensor, the first pixel and the second pixel are read out in a serial or parallel mode, and information of the first pixel can be acquired first, and then information of the second pixel can be acquired; or the information of the second pixel can be acquired first, and then the information of the first pixel can be acquired; the two can also be acquired simultaneously in a parallel manner.

Specifically, the readout process of the first pixel circuit:

in auto-zero (AZ) stage, the reset signal V of the first pixel circuit is output after the first reset transistor is turned on to complete the reset of the first pixel circuit _rst (ii) a Then closing the zero clearing switches (cmp _ az1 and cmp _ az2) to complete self-reset of the comparator; while the counter needs to be reset. In quantization reset V _rst Stage, the ramp signal vramp starts to fall; setting a signal count _ en of the counter to be high level, and starting to count down by the counter; ramp signal vramp and reset signal V _rst Is coupled to the input ends Vinp and Vinn of the comparator through a capacitor, when Vinp and Vinn are equal, the output of the comparator is inverted from high level to low level, the counter stops counting down, and the digital code value at the moment represents the reset signal V _rst Voltage of (d); when the quantization of the reset signal is finished, the ramp signal vramp returns to the reference state.

In the reading out optoelectronic stage, the transfer transistors (TX _ e or/and TX _ o) are controlled to be turned on, all photo-generated charges are transferred from the first photoelectric conversion element to the first floating diffusion point, and then the exposure signal V is buffered by the first source follower transistor _sig . At the quantization exposure V _sig Stage, ramp signal vramp falls again; setting a signal count _ en of the counter to be high level, and starting to count up by the counter; ramp signal vramp and exposure signal V _sig Through the capacitive coupling to the input ends Vinp and Vinn of the comparator, when Vinp and Vinn are overlapped, the comparator is turned over, the counter is triggered to stop counting up, the memory latches the digital code value at the moment, and the code value represents the exposure signal V _sig And a reset signal V _rst I.e. the digital quantization result of the first analog-to-digital signal output by the first pixel circuit.

In the pixel array, for a pixel row in an idle state, the transmission transistor and the reset transistor are continuously turned on to empty photo-generated charges in the corresponding pixel row (the pixel unit in an idle state also receives light), so that an anti-halo (anti-blooming) effect is achieved; meanwhile, the control unit ensures that the transmission transistor in the first pixel circuit maintains a high-level conducting state in an idle state, and the reset transistor is also in a conducting state, so that the halo Blooming phenomenon is effectively prevented.

Specifically, the readout process of the second pixel circuit:

before the quantization phase starts, the state is in an idle state, and at this time, the second transfer transistor M3 and the second reset transistor M2 are continuously turned on to empty the charges of the second photoelectric conversion element PD3 and the second floating diffusion point FD2 in the second pixel circuit, so as to play a role of anti-blooming; then, the second transfer transistor M3 and the second reset transistor M2 are turned off, the second photoelectric conversion element PD3 starts exposure, and after the exposure is finished, the analog output signal reading quantization stage of the second pixel circuit is started, at this time, the second selection transistor RS2 is at a high level, and the second selection transistor RS2 is turned on.

In quantizing the exposure signal V _sig Stage, the ramp signal vramp begins to fall; setting a signal count _ en of the counter to be high level, and starting to count down by the counter; ramp signal vramp and exposure signal V _sig The input end Vinp and Vinn are coupled to the comparator through the capacitor, when Vinp and Vinn are equal, the output of the comparator is turned from a high level to a low level, and the counter stops counting down; when exposure signal V _sig After the quantization is finished, the ramp signal vramp returns to the reference state.

In the FD reset phase, the second reset transistor RST2 is controlled to be turned on, the reset of the second floating diffusion point FD2 is completed, and then the second source follower transistor SF2 buffers the reset signal V _rst . In quantizing reset signal V _rst Stage, ramp signal vramp falls again; setting a signal count _ en of the counter to be high level, and starting to count up by the counter; ramp signal vramp and reset signal V _rst By capacitively coupling to the inputs Vinp and Vinn of the comparator, when Vinp and Vinn overlap, the comparator flips, triggering the counter to stop counting up, the memory latches thisA digital code value of time, which code value likewise represents the exposure signal V _sig And a reset signal V _rst I.e. the second pixel circuit outputs a digital quantization of the second analog output signal.

It should be noted that, in one example, the exposure signal V is quantized _sig And a reset signal V _rst While controlling the capacitance C _ref The lower polar plate has the same potential, namely, the potentials provided by the control signals in the image information quantization stage and the reset signal quantization stage are consistent, so that the ADC output digital code can correctly reflect the charge quantity generated by PD exposure.

As a further preferred embodiment of the present invention, when the adjustment capacitor is present, the control method further includes:

providing different control potentials based on the control signal in different control stages to adjust the potential of the second floating diffusion point based on the adjustment capacitance while the second pixel generates the second analog output signal; the control phase comprises an image information transmission phase, an image information quantization phase, a reset phase and a reset signal quantization phase.

Providing at least a first control potential, a second control potential, and a third control potential that sequentially decrease potentials based on the control signal, wherein:

the image information transmission phase has the first control potential, the image information quantization phase, the reset phase and the reset signal quantization phase all have a second control potential, and the exposure phase has a third control potential;

or the image information transmission stage and the image information quantization stage have the first control potential, the reset stage and the reset signal quantization stage have a second control potential, and the exposure stage has a third control potential;

or the reset phase has the first control potential, the image information transmission phase, the image information quantization phase and the reset signal quantization phase all have a second control potential, and the exposure phase has a third control potential.

In particular, the capacitance C is adjusted _ref The control signal for the lower plate connection provides three types of control potentials, a first control potential vref1, a second control potential vref2 and a third control potential vref3 for selection.

With respect to the first control potential vref1, in the phase of reading out PD electrons/AZ, the potential of the second floating diffusion point FD2 of the second pixel circuit rises up by vref _ H to completely transfer the electrons in the second photoelectric conversion element PD3 to the second floating diffusion point FD2, and the exposure signal V is quantized _sig And a reset signal V _rst While, the capacitance C will be adjusted _ref The potential of the lower plate is maintained at vref _ L.

For the second control potential vref2, the exposure signal V is quantized _sig And a reset signal V _rst While, the capacitance C will be adjusted _ref The potential of the lower plate is maintained at vref _ H, and in the stage of resetting the first floating diffusion point FD1, since the potential of the second floating diffusion point FD2 is high when the reset operation is performed, in order to prevent the second source follower transistor SF2 from entering the linear region, the potential of the second floating diffusion point FD2 is lowered to vref _ L.

For the third control potential vref3, in quantizing the exposure signal V _sig And a reset signal V _rst While, the capacitance C will be adjusted _ref The lower plate is maintained at vref _ L instead of vref _ H, mainly to lower the potential of the second floating diffusion FD2, prevent the second source follower transistor SF2 from entering the linear region, and optimize the photo-response non-uniformity (PRNU).

The utility model discloses a photodiode that first pixel corresponds is responsible for the shooting of conventional scene, the photodiode that the second pixel corresponds exposes the LED light source, and the photodiode sensitivity that the second pixel corresponds is lower, consequently can effectively prolong exposure time to ensure the seizure of complete LED pulse, to the long exposure cycle of 11ms, the difficult condition that appears overexposure simultaneously. Because the first pixel has higher sensitivity, the image can be clearly formed even under dark light, and the dynamic range of the CMOS image sensor is ensured. The image sensor is ensured to have a high dynamic range, and meanwhile flicker caused by the LED light source can be avoided.

In addition, by adjusting the capacitance C _ref The lower plate can provide potential voltage control signals vref of different gears, the potential of the second floating diffusion point FD2 can be indirectly adjusted, the charge transfer from the second light conversion element to the second floating diffusion point and the working state of the second source follower transistor during signal reading can be improved, and meanwhile, the halo phenomenon can be effectively inhibited.

To sum up, the utility model provides an image sensor pixel, pixel circuit, image sensor and control method can also avoid the scintillation that the LED light source caused when guaranteeing that image sensor has high dynamic range to improve imaging quality. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. An image sensor pixel comprising a first pixel array and a second pixel array;

the second pixel array includes a plurality of second pixels that acquire second light signals;

the second pixels are positioned at the set positions of the first pixels, so that the first pixels and the second pixels are arranged in a periodic array; the first pixel and the second pixel at the corresponding set position form a pixel unit of the image sensor pixel;

the sensitivity of a first photoelectric conversion element in the first pixel is greater than the sensitivity of a second photoelectric conversion element in the second pixel; the second pixel further comprises an adjusting capacitor, one end of the adjusting capacitor is coupled to the second floating diffusion point of the second pixel, and the other end of the adjusting capacitor is connected with a control signal so as to adjust the potential of the second floating diffusion point based on the control signal.

2. The image sensor pixel of claim 1, wherein the first pixel comprises a first photo-detection unit and a first analog output unit; wherein:

the second photoelectric detection unit comprises the second photoelectric conversion element to receive the second optical signal and convert the second optical signal into a second image signal, and an output end of the second photoelectric detection unit is coupled to the second floating diffusion point and used for transferring the second image signal to the second floating diffusion point; the input terminal of the second analog output unit is coupled to the second floating diffusion point for generating a second analog output signal of the second image signal in a quantization mode when the second one of the image sensor pixels is selectively read out.

3. The image sensor pixel of claim 2, wherein the second pixel further comprises a second reset unit; one end of the second reset unit is connected with a working power supply, and the other end of the second reset unit is coupled to the second floating diffusion point;

4. The image sensor pixel of claim 2, wherein the first pixel further comprises a first reset unit having one end connected to an operating power supply and another end coupled to the first floating diffusion point;

and/or the first photodetecting unit comprises a first transfer transistor and the first photoelectric conversion element; the first photoelectric conversion element is coupled to the first floating diffusion point through the first transfer transistor;

5. The image sensor pixel of claim 4, wherein the first pixel further comprises a gain control unit coupled between the first floating diffusion and the first reset unit, the gain control unit comprising a gain control transistor and a gain control capacitor, the gain control transistor being coupled between the first floating diffusion and the first reset unit, the gain control capacitor being coupled between the gain control transistor and the first reset unit, a gate of the gain control transistor receiving a gain control command.

6. The image sensor pixel of claim 2, wherein the second pixel further comprises a memory cell coupled to the second floating diffusion point at one end and to ground at another end.

7. The image sensor pixel of claim 2, wherein the pixel unit includes at least one of the first pixels including one of the first photoelectric conversion elements, the pixel unit includes one of the second pixels including one of the second photoelectric conversion elements;

8. The image sensor pixel of claim 2, wherein different control potentials are provided based on the control signal at different control stages to adjust the potential of the second floating diffusion point based on the adjustment capacitance when the second pixel generates the second analog output signal; the control phase comprises an image information transmission phase, an image information quantization phase, a reset phase and a reset signal quantization phase.

9. The image sensor pixel of any one of claims 1-8, wherein the second light signal is a light signal of a pulsed light source; the exposure time of the second pixel is longer than the flicker period of the pulse light source.

10. A pixel circuit based on the pixel of the image sensor as claimed in any one of claims 1 to 9, wherein the plurality of pixel circuits includes a pixel circuit unit corresponding to the pixel unit, the pixel circuit unit including a first pixel circuit corresponding to the first pixel and a second pixel circuit corresponding to the second pixel.

11. An image sensor, characterized in that the image sensor comprises an image sensor pixel according to any one of claims 1-9; alternatively, the image sensor employs the pixel circuit according to claim 10.

12. The image sensor of claim 11, wherein the image sensor further comprises a digital output unit; the input end of the digital output unit receives a first analog output signal and a second analog output signal generated by the image sensor pixel, and the reference input end of the digital output unit receives a ramp signal; the digital output unit generates a first digital signal of the first analog output signal according to the first analog output signal and the ramp signal, and generates a second digital signal of the second analog output signal according to the second analog output signal and the ramp signal.

13. The image sensor according to claim 11, further comprising a control unit including a latch unit and a driving unit;