CN113329194B - Image sensor for extracting instant motion and method thereof - Google Patents
Image sensor for extracting instant motion and method thereof Download PDFInfo
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Abstract
The present application relates to the field of sensor technologies, and in particular, to an image sensor and a method for extracting instantaneous motion. The sensor comprises an interframe differential pixel, wherein the interframe differential pixel comprises a photosensitive differential unit, a reset unit and an output unit, the photosensitive differential unit comprises a photodiode, a capacitor and a first transistor, one end of the photodiode is connected with a power supply, the other end of the photodiode is connected with a grid end of the first transistor, the grid end is defined as a photo-generated charge storage node, a source electrode of the first transistor is connected with the power supply, a drain electrode of the first transistor is connected with an upper polar plate of the capacitor, and the photodiode is used for receiving an incident light signal on the pixel, converting the incident light signal into photo-generated charge and storing the photo-generated charge in the photo-generated charge storage node. According to the image sensor, the complex functional modules are not added in the pixels, data are selectively output in the pixel array signal reading circuit, the image data transmission quantity, the image processing delay and the resource consumption can be effectively reduced, and the image processing efficiency is further improved.
Description
Technical Field
The present application relates to the field of sensor technology, and more particularly, to an image sensor and method for extracting instantaneous motion.
Background
In recent years, image sensing and processing systems have been widely used in production and life. In the mainstream image sensing and processing system, the image signal generated by the image sensor needs to be completely output to the image processing system for calculation.
However, as the imaging quality of the image sensor is improved, the amount of raw image data generated by the image sensor is increased, which puts a great strain on data transmission and processing. Meanwhile, the high-speed and low-power image processing is increasingly required in the fields of edge computing, internet of things and the like, and a more efficient image sensing and processing system is required.
Therefore, the present application proposes an image sensor and a method thereof for extracting instantaneous motion, which use the basic structure and the photoelectric characteristics of the pixels to complete the photosensitive and instantaneous signal difference calculation in the pixels, and selectively output the data in the pixel array signal readout circuit, so as to at least partially solve the above technical problems.
Disclosure of Invention
The method still buffers the original pixel signals during calculation, can completely reserve meaningful image information, and avoids excessive simplification of data; the invention utilizes the basic electrical characteristics of the pixel instead of the functional circuit to generate a calculation result, the calculation result and the original signal are generated simultaneously, and compared with the calculation circuit, the calculation delay is not generated; the invention does not add complex functional modules in the pixel or peripheral circuit, and the hardware realization cost is low.
To achieve the above technical object, the present application provides an image sensor for extracting instantaneous motion, including inter-frame differential pixels, the inter-frame differential pixels including:
the photosensitive differential unit comprises a photodiode, a capacitor and a first transistor, wherein one end of the photodiode is connected with a power supply, the other end of the photodiode is connected with a grid end of the first transistor, the end is defined as a photoproduction charge storage node, a source electrode of the first transistor is connected with the power supply, a drain electrode of the first transistor is connected with an upper electrode plate of the capacitor, the photodiode is used for receiving an incident light signal on a pixel and converting the incident light signal into photoproduction charge to be stored in the photoproduction charge storage node, the upper electrode plate of the capacitor is used for caching an original pixel signal, and the lower electrode plate of the capacitor is used for generating and caching a pixel interframe differential signal;
the reset unit comprises a second transistor, a third transistor and a fourth transistor, wherein the source electrode of the second transistor is connected with a photo-generated charge storage node of the photosensitive differential unit, the drain electrode of the second transistor is grounded, the grid electrode of the second transistor is connected with a first trigger power supply, the source electrode of the third transistor is connected with the upper polar plate of a capacitor in the photosensitive differential unit, the drain electrode of the third transistor is grounded, the grid electrode of the third transistor is connected with a second trigger power supply, and the source electrode of the fourth transistor is connected with the lower polar plate of the capacitor, the drain electrode of the fourth transistor is grounded, and the grid electrode of the fourth transistor is connected with a third trigger power supply;
and the output unit comprises a fifth transistor, a sixth transistor and a seventh transistor, wherein the source electrode of the fifth transistor is connected with a power supply, the grid electrode of the fifth transistor is connected with the row address decoder, the drain electrode of the fifth transistor is connected with the source electrodes of the sixth transistor and the seventh transistor, the grid electrode of the sixth transistor is connected with the upper polar plate of the capacitor, the drain electrode of the sixth transistor is used as an original pixel signal to be output, the grid electrode of the seventh transistor is connected with the lower polar plate of the capacitor, and the drain electrode of the seventh transistor is used as a pixel inter-frame differential signal to be output.
Further, the image sensor further includes a signal selection processing module, which includes:
the negative input end of the voltage comparator is connected with a reference voltage, and the positive input end of the voltage comparator is connected with the pixel inter-frame differential signal output;
a first input end of the data selector is connected with the output end of the voltage comparator, and a second input end of the data selector is connected with the original pixel signal output;
when the output end of the voltage comparator outputs a high level, the data selector outputs an original pixel signal, and when the output end of the voltage comparator outputs a zero level, the data selector outputs a zero level;
and the analog-to-digital converter is connected with the output end of the data selector and is used for performing analog-to-digital conversion on the signal output by the data selector.
Preferably, the number of the photodiodes is one, the number of the capacitors is one, and the photodiodes can be replaced by inductive couplers.
Preferably, the reference voltage is provided by an external circuit.
The second aspect of the present invention provides a method for extracting instantaneous motion by using the above image sensor, comprising the following steps:
the inter-frame differential pixel provides an original pixel signal output and a pixel inter-frame differential signal output to finish the light sensing and instant inter-frame differential calculation;
connecting a negative input end of a voltage comparator with a reference voltage, and connecting a positive input end of the voltage comparator with the pixel interframe differential signal output;
connecting a first input end of a data selector with an output end of the voltage comparator, and connecting a second input end of the data selector with the original pixel signal output;
when the output end of the voltage comparator outputs a high level, the data selector outputs an original pixel signal, and when the output end of the voltage comparator outputs a zero level, the data selector outputs a zero level;
and connecting an analog-to-digital converter with the output end of the data selector, and performing analog-to-digital conversion on the signal output by the data selector.
Specifically, the inter-frame difference pixels have different photosensitive periods, the different photosensitive periods all include a reset stage, an exposure stage and a reading stage to complete photosensitive and instant signal difference calculation, the different photosensitive periods are 0 or n, and n is greater than or equal to 1.
Further, in the 0 th photosensitive cycle, in the reset phase, the reset unit resets the photo-generated charge storage node and the capacitor upper and lower electrode plates; in the exposure phase, the photosensitive differential unit stores the generated photo-generated charges in a photo-generated charge storage node; in the reading stage, a pulse voltage is applied to charge the capacitor, a pixel signal is obtained at the upper plate of the capacitor, the signal voltage is read out through the output unit, then the reset unit resets the upper plate and the lower plate of the capacitor, a pulse voltage is applied again, and the signal voltage is obtained at the upper plate of the capacitor again.
Further, in the nth photosensitive cycle, the reset stage floats the lower plate of the capacitor, the reset unit resets the upper plate of the capacitor, and when the upper plate is reset, a signal voltage of- α Vn-1 is obtained on the lower plate, wherein α is a differential gain and is used for representing the signal gain from the upper plate to the lower plate; in the exposure phase, the photosensitive differential unit stores the generated photo-generated charges in a photo-generated charge storage node; in the reading-out stage, when the voltage of the upper plate of the capacitor is charged to the signal voltage Vn after the exposure is finished, alpha (Vn-Vn-1) is obtained when the voltage at the lower plate of the capacitor rises so as to obtain the difference value between the pixel signal and the last exposure signal.
Further, in a readout stage of the nth photosensitive cycle, the original signal and the inter-frame differential signal of the pixel are respectively read out, then the reset unit resets the upper plate and the lower plate of the capacitor, and the signal voltage Vn is obtained at the upper plate of the capacitor again by applying the pulse voltage again.
The beneficial effect of this application does: the image sensor for extracting the instant motion and the method thereof still buffer original pixel signals during calculation, can completely reserve meaningful image information, and avoid excessive simplification of data; the method utilizes the basic electrical characteristics of the pixels instead of the functional circuit to generate a calculation result, the calculation result and an original signal are generated simultaneously, and no calculation delay is generated compared with the calculation circuit; according to the method, no complex functional module is added in the pixel or the peripheral circuit, and the hardware implementation cost is low. In a word, the invention utilizes the basic structure and the photoelectric characteristic of the pixel to complete the light sensing and the instant signal difference calculation in the pixel, extracts the instant motion, and selectively outputs the data in the pixel array signal reading circuit, thereby effectively reducing the transmission quantity of the image data, the delay of the image processing and the resource consumption, and further improving the image processing efficiency.
Drawings
Fig. 1 shows an inter-frame differential pixel circuit diagram of an image sensor implemented in embodiment 1 of the present application;
fig. 2 is a schematic diagram showing a signal selection processing block of an image sensor implemented in embodiment 1 of the present application;
fig. 3 shows a pixel timing chart of an image sensor implemented in embodiment 1 of the present application;
fig. 4 is a diagram showing an effect of an image sensor implemented in embodiment 1 of the present application;
fig. 5 is a schematic flow chart of a method for extracting instantaneous motion by using the image sensor in embodiment 2 of the present application.
Detailed Description
Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present application. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present application. It will be apparent to one skilled in the art that the present application may be practiced without one or more of these details. In other instances, well-known features of the art have not been described in order to avoid obscuring the present application.
It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the application. As used herein, the singular is intended to include the plural unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Exemplary embodiments according to the present application will now be described in more detail with reference to the accompanying drawings. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to only the embodiments set forth herein. The figures are not drawn to scale, wherein certain details may be exaggerated and omitted for clarity. The shapes of various regions, layers, and relative sizes and positional relationships therebetween shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, as actually required.
Example 1:
the present embodiment implements an image sensor for extracting instantaneous motion, as shown in fig. 1, including inter-frame differential pixels including:
the photosensitive differential unit comprises a photodiode, a capacitor and a transistor T1, wherein one end of the photodiode is connected with a power supply, the other end of the photodiode is connected with a gate end of the transistor T1, the end is defined as a photo-generated charge storage node pd, a source electrode of the transistor T1 is connected with the power supply, and a drain electrode of the transistor T1 is connected with an upper electrode plate of the capacitor;
the reset unit comprises a transistor T2, a transistor T3 and a transistor T4, wherein the source of the transistor T2 is connected with a photo-generated charge storage node pd of the photosensitive differential unit, the drain of the transistor T is grounded, and the gate of the transistor T2 is connected with a trigger power supply Vrst0, the source of the transistor T3 is connected with the upper electrode plate C1 of a capacitor, the drain of the transistor T is grounded, the gate of the transistor T3 is connected with a trigger power supply Vrst1, and the source of the transistor T4 is connected with the lower electrode plate C2 of the capacitor, the drain of the transistor T is grounded, and the gate of the transistor T4 is connected with a trigger power supply Vrst 2;
the output unit comprises a transistor T5, a transistor T6 and a transistor T7, wherein the source of the transistor T5 is connected with a power supply Vdd, the gate of the transistor T5 is connected with a row address decoder Vnow, the drain of the transistor T5 is connected with the sources of the transistor T6 and the transistor T7, the gate of the transistor T6 is connected with the upper plate C1 of a capacitor, the drain of the transistor T6 is used as an original pixel signal output Vout0, the gate of the transistor T7 is connected with the lower plate C2 of the capacitor, and the drain of the transistor T7 is used as a pixel inter-frame differential signal output Vout 1.
The photodiode is used for converting an incident light signal received by the pixel into an electric signal. The capacitor is used for carrying out differential calculation and buffering on the pixel signals. The transistors T2, T3, and T4 are used to reset the photo-generated charge storage node pd (where the photodiode is connected to the gate of T1), C1 (the top plate of the capacitor), and C2 (the bottom plate of the capacitor) in the pixel, respectively. Transistor T1 is used to couple the signal from the photo-generated charge storage node to a capacitor. The transistor T5 is used to enable row selection of the pixel. The transistor T6 and the transistor T7 serve as source followers for outputting the pixel signal to the column stage.
The image sensor further includes a signal selection processing module, as shown in fig. 2, the signal selection processing module includes:
the negative (-) input end of the voltage comparator is connected with a reference voltage, the positive (+) input end of the voltage comparator is connected with the pixel interframe differential signal output Vout1, the reference voltage is provided through an external circuit, and a specific threshold value is set according to the exposure condition and the light intensity condition of an actual scene;
a data selector having a first input connected to the output of the voltage comparator and a second input connected to the original pixel signal output, Vout 0;
the data selector outputs Vout0 when the output terminal of the voltage comparator outputs a high level, and outputs a zero level when the output terminal of the voltage comparator outputs a zero level;
and the analog-to-digital converter is connected with the output end of the data selector and is used for performing analog-to-digital conversion on the signal output by the data selector.
Further, the inter-frame differential pixels have different photosensitive periods, and the different photosensitive periods all comprise a reset stage, an exposure stage and a readout stage so as to complete photosensitive and instant signal differential calculation.
Specifically, the different photosensitive periods are 0 or n, wherein n is more than or equal to 1.
The pixel photodetection and signal calculation are mainly divided into three processes of reset, exposure, and readout, and the timing chart is shown in fig. 3. Since it is necessary to calculate the signal difference between the current exposure and the last exposure in the pixel, the operation of the pixel in the first photosensitive period and the subsequent photosensitive period is different, which is described in detail below.
For the 0 th sensing period:
a reset phase, resetting Vpd and Vc 1;
an exposure phase, wherein the photodiode generates photo-generated charges so as to change the voltage value of pd;
in the readout phase, a pulse voltage is applied to the power supply Vd, and the transistor T1 charges the capacitor under the control of the gate terminal voltage Vpd, so that the signal voltage V0 is obtained at C1. And V0 is read out through transistor T6. C1 and C2 are then reset, a pulse voltage is applied at the power supply Vd, and the signal voltage V0 is again obtained at C1.
For the nth sensing period (n > ═ 1)
In the reset phase, Vc2 is floated, Vc1 and Vpd are reset, Vc2 also drops when Vc1 is reset, and a signal voltage of-alpha Vn-1 can be obtained on C2, wherein alpha is defined as differential gain and is used for representing the signal gain of a signal from C1 to C2;
an exposure phase, wherein the photodiode generates photo-generated charges so as to change the voltage value of pd;
in the readout stage, when the voltage of C1 is charged to the signal voltage Vn after the exposure is finished, the voltage at C2 is also increased to obtain α (Vn-1), which is the difference between the pixel signal and the last exposure signal. Then in the readout phase, the original signal and the inter-frame differential signal of the pixel are read out from Vout0 and Vout1, respectively. C1 and C2 are then reset, a pulse voltage is applied at vd, and the signal voltage Vn is again obtained at C1.
Therefore, in the nth photosensitive cycle (n > < 1), the pixel can generate and output the original signal corresponding to the current exposure and the signal difference between the current exposure and the last exposure, and the photoelectric sensing and the real-time calculation can be simultaneously completed in the pixel, and the real-time motion extraction effect graph is shown in fig. 4.
As shown in fig. 2, an array structure of motion-extracting pixels is shown, the pixels output an original exposure signal Vout0 and an inter-frame differential signal Vout1 in each sensing period, Vout1 is compared with a reference voltage Vth after being output, and the comparison result is input to the data selector together with Vout 0. When Vout1> Vth, it is considered that an action is detected on the pixel, and the data selector outputs Vout0, and the analog-to-digital converter performs a complete analog-to-digital conversion on Vout 0; when vout1< ═ Vth, it is considered that no motion is detected at the pixel, and the data selector outputs zero level, the analog-to-digital converter can perform fast analog-to-digital conversion to the zero level, thereby reducing the time and power consumption required for analog-to-digital conversion. Fig. 4 shows the result of preprocessing the image by the motion extraction image sensor, and as shown in fig. 4, after the preprocessing of the motion extraction, the image information of the pedestrian in the picture is retained and the background information is deleted. In the subsequent image identification processing process, the reserved image information is processed between the processors, so that the transmission quantity and the calculation quantity of data are greatly reduced, and the operating efficiency of the system is improved.
Example 2:
in this embodiment, a method for extracting instantaneous motion by using the image sensor is implemented, and as shown in fig. 5, the following steps are specifically performed:
s1, the inter-frame differential pixel provides an original pixel signal output Vout0 and a pixel inter-frame differential signal output Vout1, and light sensing and instant signal differential calculation are completed;
s2, connecting the negative input end of a voltage comparator with a reference voltage, and connecting the positive input end of the voltage comparator with the pixel inter-frame differential signal output Vout 1;
s3, connecting the first input terminal of the data selector with the output terminal of the voltage comparator, and connecting the second input terminal of the data selector with the original pixel signal output Vout 0;
s4, when the output end of the voltage comparator outputs high level, the data selector outputs Vout0, when the output end of the voltage comparator outputs zero level, the data selector outputs zero level;
and S5, connecting an analog-to-digital converter with the output end of the data selector, and performing analog-to-digital conversion on the signal output by the data selector.
Specifically, the inter-frame difference pixels have different photosensitive periods, the different photosensitive periods all include a reset stage, an exposure stage and a reading stage to complete photosensitive and instant signal difference calculation, the different photosensitive periods are 0 or n, and n is greater than or equal to 1.
Specifically, in the 0 th photosensitive cycle, in the reset phase, the reset unit resets the photo-generated charge storage node and the capacitor upper and lower electrode plates; in the exposure phase, the photosensitive differential unit generates photo-generated charges and stores the photo-generated charges in a photo-generated charge storage node; in the reading stage, a pulse voltage is applied to charge the capacitor, a signal voltage V0 is obtained at the upper plate of the capacitor, V0 is read out through the output unit, then the reset unit resets the upper plate and the lower plate of the capacitor, a pulse voltage is applied again, and a signal voltage V0 is obtained at the upper plate of the capacitor again.
In the nth photosensitive cycle, the lower plate of the capacitor is floated in the reset stage, the reset unit resets the upper plate of the capacitor, and when the upper plate is reset, a signal voltage of-alpha Vn-1 is obtained on the lower plate, wherein alpha is defined as differential gain and is used for representing the signal gain from the upper plate to the lower plate; in the exposure phase, the photosensitive differential unit generates photo-generated charges and stores the photo-generated charges in a photo-generated charge storage node; in the reading-out stage, when the voltage of the upper plate of the capacitor is charged to the signal voltage Vn after the exposure is finished, alpha (Vn-Vn-1) is obtained when the voltage at the lower plate of the capacitor is increased so as to obtain the difference value between the pixel signal and the last exposure signal.
In the readout stage of the nth photosensitive cycle, the original signal of the pixel and the pixel interframe differential signal are respectively read out, then the reset unit resets the upper plate and the lower plate of the capacitor, and the signal voltage Vn is obtained at the upper plate of the capacitor again through pulse voltage.
In the above embodiments, the photodiode of the light sensing portion may be replaced with other light sensing elements, such as an inductive coupling device; the specific structure in the pixel can be adjusted, for example, two photodiodes can be set to be exposed to light respectively to calculate the signal difference, or the number and specific connection relationship of the transistors can be adjusted to realize the same function; selective readout of data can be achieved in other ways, such as by adjusting the row-column scan to filter out image information based on pixel calculations; three-dimensional stacking + backside illumination may also be used, and those skilled in the art can change or replace the three-dimensional stacking + backside illumination within the technical scope of the present disclosure.
Furthermore, various component embodiments of the present application may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functions of some or all of the components in the creation apparatus of a virtual machine according to embodiments of the present application. The present application may also be embodied as apparatus or device programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present application may be stored on a computer device and readable medium, or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.
The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. An image sensor for extracting instantaneous motion, comprising inter-frame differential pixels, the inter-frame differential pixels comprising:
the photosensitive differential unit comprises a photodiode, a capacitor and a first transistor, wherein one end of the photodiode is connected with a power supply, the other end of the photodiode is connected with a grid end of the first transistor, the other end of the photodiode is defined as a photo-generated charge storage node, a source electrode of the first transistor is connected with the power supply, a drain electrode of the first transistor is connected with an upper polar plate of the capacitor, and the photodiode is used for receiving an incident light signal on a pixel, converting the incident light signal into photo-generated charge and storing the photo-generated charge in the photo-generated charge storage node;
the reset unit comprises a second transistor, a third transistor and a fourth transistor, wherein the source electrode of the second transistor is connected with a photo-generated charge storage node of the photosensitive differential unit, the drain electrode of the second transistor is grounded, the grid electrode of the second transistor is connected with a first trigger power supply, the source electrode of the third transistor is connected with the upper polar plate of a capacitor in the photosensitive differential unit, the drain electrode of the third transistor is grounded, the grid electrode of the third transistor is connected with a second trigger power supply, and the source electrode of the fourth transistor is connected with the lower polar plate of the capacitor, the drain electrode of the fourth transistor is grounded, and the grid electrode of the fourth transistor is connected with a third trigger power supply;
the output unit comprises a fifth transistor, a sixth transistor and a seventh transistor, wherein the source electrode of the fifth transistor is connected with a power supply, the grid electrode of the fifth transistor is connected with a row address decoder, the drain electrode of the fifth transistor is connected with the source electrodes of the sixth transistor and the seventh transistor, the grid electrode of the sixth transistor is connected with the upper polar plate of the capacitor, the drain electrode of the sixth transistor is used as an original pixel signal to be output, the grid electrode of the seventh transistor is connected with the lower polar plate of the capacitor, and the drain electrode of the seventh transistor is used as a pixel inter-frame differential signal to be output;
wherein the reset unit is configured to reset an upper plate of the capacitor, and the upper plate obtains-alphaV on a lower plate when being resetn-1Wherein alpha represents the signal gain from the upper plate to the lower plate of the signal, and the upper plate voltage of the capacitor is charged to the signal voltage V after the exposure is finishednWhen the voltage at the lower plate of the capacitor rises, alpha (V) is obtainedn-Vn-1) To obtain the difference between the pixel signal and the last exposure signal.
2. The image sensor of claim 1, further comprising a signal selection processing module, the signal selection processing module comprising:
the negative input end of the voltage comparator is connected with a reference voltage, and the positive input end of the voltage comparator is connected with the pixel inter-frame differential signal output;
a first input end of the data selector is connected with the output end of the voltage comparator, and a second input end of the data selector is connected with the original pixel signal output;
when the output end of the voltage comparator outputs a high level, the data selector outputs an original pixel signal, and when the output end of the voltage comparator outputs a zero level, the data selector outputs a zero level;
and the analog-to-digital converter is connected with the output end of the data selector and is used for performing analog-to-digital conversion on the signal output by the data selector.
3. The image sensor for extracting instantaneous motion of claim 2, wherein the photosensitive differential unit has one photodiode and one capacitor.
4. The image sensor of claim 3, wherein the photodiode is further replaced with an inductive coupler.
5. The image sensor of claim 2, wherein the reference voltage is provided by an external circuit.
6. A method for extracting instantaneous motion by using the image sensor of any one of claims 1 to 5, comprising the steps of:
the inter-frame differential pixel provides an original pixel signal output and a pixel inter-frame differential signal output to finish the light sensing and instant inter-frame differential calculation;
connecting a negative input end of a voltage comparator with a reference voltage, and connecting a positive input end of the voltage comparator with the pixel interframe differential signal output;
connecting a first input end of a data selector with an output end of the voltage comparator, and connecting a second input end of the data selector with the original pixel signal output;
when the output end of the voltage comparator outputs a high level, the data selector outputs an original pixel signal, and when the output end of the voltage comparator outputs a zero level, the data selector outputs a zero level;
and connecting an analog-to-digital converter with the output end of the data selector, and performing analog-to-digital conversion on the signal output by the data selector.
7. The method of claim 6, wherein the inter-frame differential pixels have different exposure periods, the different exposure periods each include a reset phase, an exposure phase and a readout phase to complete exposure and real-time signal differential calculations, the different exposure periods are 0 or n, wherein n is greater than or equal to 1.
8. The method of claim 7, wherein in the 0 th sensing period, the reset unit resets the photogenerated charge storage node and the upper and lower plates of the capacitor during the reset phase; in the exposure phase, the photosensitive differential unit stores the generated photo-generated charges in a photo-generated charge storage node; in the reading stage, a pulse voltage is applied to charge the capacitor, a pixel signal is obtained at the upper plate of the capacitor, the voltage corresponding to the pixel signal is read out through the output unit, then the reset unit resets the upper plate and the lower plate of the capacitor, a pulse voltage is applied again, and the voltage corresponding to the pixel signal is obtained at the upper plate of the capacitor again.
9. The method of claim 7, wherein in the nth sensing period, the reset phase floats the lower plate of the capacitor, the reset unit resets the upper plate of the capacitor, and the upper plate gets- α V on the lower plate when resetn-1Wherein α is a differential gain, which is used to represent the signal gain of the signal from the top plate to the bottom plate; in the exposure phase, the photosensitive differential unit stores the generated photo-generated charges in a photo-generated charge storage node; in the reading stage, the upper plate voltage of the capacitor is charged to the signal voltage V after the exposure is finishednWhen the voltage at the lower plate of the capacitor rises, alpha (V) is obtainedn-Vn-1) To obtain the difference between the pixel signal and the last exposure signal.
10. The method according to claim 9, wherein in the readout phase of the nth photosensitive cycle, the original signal and the inter-frame differential signal of the pixel are respectively read out, and then the reset unit resets the upper plate and the lower plate of the capacitor, and the signal voltage V is obtained at the upper plate of the capacitor again by applying the pulse voltage againn。
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| US5602585A (en) * | 1994-12-22 | 1997-02-11 | Lucent Technologies Inc. | Method and system for camera with motion detection |
| CN101800837A (en) * | 2009-02-05 | 2010-08-11 | 香港科技大学 | Improve the apparatus and method of the cmos image sensor dynamic range and the linearity |
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| US5602585A (en) * | 1994-12-22 | 1997-02-11 | Lucent Technologies Inc. | Method and system for camera with motion detection |
| CN101800837A (en) * | 2009-02-05 | 2010-08-11 | 香港科技大学 | Improve the apparatus and method of the cmos image sensor dynamic range and the linearity |
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