Image sensor, image output method, and photoelectron device

Abstract

The present invention provides an image sensor and its image output method, a photoelectron device. The image sensor includes a plurality of pixels, each pixel includes a photoelectric detection circuit, a signal reading circuit, a floating diffusion node, an integration capacitor, a transmission circuit, a self-adaptive power supply and a signal processing circuit, the floating diffusion node integrates the photoelectric charge in the integration capacitor to obtain an integration voltage, the signal processing circuit generates a logarithmic voltage and a logarithmic current, after the floating diffusion node receives the photoelectric charge, the target voltage is much smaller than the reference voltage, the node current of the floating diffusion node is a photocurrent corresponding to the photoelectric charge, the node voltage is an integration voltage, when the target voltage increases and approaches the reference voltage, the node current of the floating diffusion node becomes a logarithmic current, the node voltage becomes a logarithmic voltage, and finally the signal reading circuit outputs a corresponding image signal according to the node voltage (integration voltage or logarithmic voltage). The present invention has two different operation forms, integration and logarithm, which can better adapt to a changing environment.

Description

[Technical Field]

[0001] The present invention relates to the technical field of photosensitive elements, and in particular to an image sensor and its image output method, and an optoelectronic device. [Background technology]

[0002] An image sensor converts a light signal incident on a photosensitive surface into a corresponding electrical signal through photoelectric conversion, and outputs a corresponding image based on the converted electrical signal. This is widely applied in various optoelectronic devices such as digital cameras, video cameras, video recorders, facsimiles, image scanners, and digital televisions. In related technologies, the operation of image sensors is often too simple, and they are unable to adapt well to environmental changes between weak and strong light, which can seriously affect the image quality of the image sensor. Therefore, there is a need to improve the structure of existing image sensors. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention provides an image sensor and its image output method, and an optoelectronic device, in order to solve the problem that the operation mode of the image sensor in the prior art is too simple. [Means for solving the problem]

[0004] In order to solve the above technical problems in the prior art, a first embodiment of the present invention provides an image sensor, the image sensor including a pixel array consisting of a plurality of pixels, each pixel including a floating diffusion node, an integrating capacitor, a photoelectric detection circuit, a signal reading circuit, a self-adaptive power supply, a transmitting circuit, and a signal processing circuit, the photoelectric detection circuit is connected to the floating diffusion node via the transmitting circuit, the floating diffusion node is grounded via the integrating capacitor, the floating diffusion node and the integrating capacitor are connected to the signal reading circuit, and the self-adaptive power supply is connected to the floating diffusion node via the signal processing circuit. Specifically, the photoelectric detection circuit photoelectrically converts incident light to obtain corresponding photoelectric charges. The transmitting circuit transmits the photoelectric charges to the floating diffusion node. The signal processing circuit generates a logarithmic voltage and a logarithmic current (the logarithmic voltage and the logarithmic current have a logarithmic relationship). The floating diffusion node integrates the photocharges in an integration capacitor to obtain a corresponding integrated voltage. After the floating diffusion node receives the photocharges, if the difference between the target voltage (the self-adaptive voltage of the self-adaptive power supply minus the node voltage of the floating diffusion node) and the reference voltage is greater than a preset threshold and the logarithmic current is smaller than the photocurrent corresponding to the photocharges, the node current of the floating diffusion node becomes the photocurrent corresponding to the photocharges, the node voltage becomes the integrated voltage, and the target voltage increases with time. If the target voltage increases and the difference between the target voltage and the reference voltage becomes less than the preset threshold, the logarithmic current becomes larger than the photocurrent corresponding to the photocharges and flows into the floating diffusion node, causing the node current to become a logarithmic current and the node voltage to become a logarithmic voltage. A signal reading circuit provides an image sensor that outputs a corresponding image signal based on the node voltage.

[0005] A second aspect of the present invention is an image output method for an image sensor, the image sensor including a pixel array consisting of a plurality of pixels, each pixel including a floating diffusion node, an integrating capacitor, a photoelectric detection circuit, a signal reading circuit, a self-adaptive power supply, a transmitting circuit, and a signal processing circuit, the photoelectric detection circuit is connected to the floating diffusion node via the transmitting circuit, the floating diffusion node is grounded via the integrating capacitor, the floating diffusion node and the integrating capacitor are connected to the signal reading circuit, and the self-adaptive power supply is connected to the floating diffusion node via the signal processing circuit. Specifically, the photoelectric detection circuit photoelectrically converts incident light to obtain corresponding photoelectric charges. The transmitting circuit transmits the photoelectric charges to the floating diffusion node. The signal processing circuit generates a logarithmic voltage and a logarithmic current (the logarithmic voltage and the logarithmic current have a logarithmic relationship). The floating diffusion node integrates the photocharges in an integration capacitor to obtain a corresponding integrated voltage. After the floating diffusion node receives the photocharges, if the difference between the target voltage (the self-adaptive voltage of the self-adaptive power supply minus the node voltage of the floating diffusion node) and the reference voltage is greater than a preset threshold and the logarithmic current is smaller than the photocurrent corresponding to the photocharges, the node current of the floating diffusion node becomes the photocurrent corresponding to the photocharges, the node voltage becomes the integrated voltage, and the target voltage increases with time. If the target voltage increases and the difference from the reference voltage becomes less than the preset threshold, the logarithmic current becomes larger than the photocurrent corresponding to the photocharges and flows into the floating diffusion node, causing the node current to become a logarithmic current and the node voltage to become a logarithmic voltage. A signal reading circuit outputs a corresponding image signal based on the node voltage, providing an image output method.

[0006] A third aspect of the present invention provides an optoelectronic device including the image sensor according to the first aspect of the present invention. [Effects of the Invention]

[0007] As can be seen from the above, compared with the prior art, the present invention has the following advantages: the image sensor includes a pixel array consisting of a plurality of pixels, and each pixel includes a floating diffusion node, an integrating capacitor, a photoelectric detection circuit, a signal reading circuit, a transmitting circuit, a self-adaptive power supply, and a signal processing circuit. In practical application, the photoelectric detection circuit converts incident light into electrical signals to obtain corresponding photoelectric charges; the transmitting circuit transmits the photoelectric charges to the floating diffusion node; after the floating diffusion node receives the photoelectric charges, the floating diffusion node integrates the photoelectric charges in the integrating capacitor to obtain a corresponding integrated voltage; and the signal processing circuit generates a logarithmic voltage and a logarithmic current; after the floating diffusion node receives the photoelectric charges, the difference between the target voltage and the reference voltage is greater than a preset threshold, which indicates that the target voltage is much smaller than the reference voltage. In this case, the logarithmic current is smaller than the photocurrent corresponding to the photocharges, meaning that the logarithmic current does not flow into the floating diffusion node. Therefore, the node current of the floating diffusion node becomes a photocurrent corresponding to the photocharges, and the node voltage becomes an integrated voltage. However, as time increases, the target voltage also increases. When the target voltage increases and the difference between the target voltage and the reference voltage becomes equal to or less than a preset threshold, the logarithmic current increases and becomes greater than the photocurrent corresponding to the photocharges, and the logarithmic current flows into the floating diffusion node. As a result, the node current of the floating diffusion node becomes a logarithmic current, and the node voltage becomes a logarithmic voltage. Finally, the signal readout circuit outputs a corresponding image signal based on the node voltage (i.e., the integrated voltage or logarithmic voltage). From this process, the following can be seen: The image sensor of the present invention has not only a single operating mode, but also two different operating modes: an integrated mode (the node voltage is an integrated voltage, and the signal readout circuit outputs a corresponding image signal based on the integrated voltage) and a logarithmic mode (the node voltage is a logarithmic voltage, and the signal readout circuit outputs a corresponding image signal based on the logarithmic voltage). This allows the image sensor to adapt to changing environments and improves the image quality of the image sensor. Taking an environment where there is a change between weak light and strong light as an example, after the floating diffusion node receives the photocharges, the light intensity of the incident light is still weak. In this case, the target voltage is much smaller than the reference voltage, and the operation mode of the image sensor is an integral mode. Its dark light sensitivity is also improved by integrating the photocharges, thereby improving the signal-to-noise ratio of the image sensor in a weak light environment and ensuring low noise characteristics.Then, as the light intensity of the incident light gradually increases over time, the target voltage also gradually increases, and when the light intensity of the incident light becomes strong, the target voltage becomes very close to the reference voltage. At this time, the image sensor operates in a logarithmic mode, and the logarithmic voltage in the logarithmic mode increases the voltage that can be generated by the full well charge of the photoelectric detection circuit, thereby expanding the dynamic range of the image sensor in a strong light environment. In this way, even in environments that vary between weak and strong light, the image sensor's various operating modes can achieve both low noise in weak light environments and a high dynamic range in strong light environments, allowing the image sensor to produce high-quality images in both environments. [Brief explanation of the drawings]

[0008] In order to more clearly explain the technical solutions of the related art or embodiments of the present invention, the following briefly introduces drawings necessary for describing the related art or embodiments of the present invention. It is obvious that the drawings included in the following description are only some embodiments of the present invention, not all embodiments. Those skilled in the art can derive other drawings based on these drawings without any creative efforts. [Figure 1] FIG. 2 is a first module block diagram of a pixel in an image sensor provided by an embodiment of the present invention; [Figure 2] FIG. 2 is a second type of module block diagram of a pixel in an image sensor provided by an embodiment of the present invention; [Figure 3] FIG. 2 is a conceptual diagram of a circuit configuration of a pixel in an image sensor provided by an embodiment of the present invention. [Figure 4] FIG. 2 is an equivalent circuit diagram of a floating diffusion node provided by an embodiment of the present invention. [Figure 5] 4 is a timing diagram of an image sensor provided by an embodiment of the present invention. [Figure 6] 2 is a flowchart of an image output method provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] In order to make the objectives, technical solutions, and advantages of the present invention clearer and easier to understand, the present invention will be described in detail and completely below in combination with the embodiments of the present invention and corresponding drawings. Here, the same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions. It should be noted that the embodiments of the present invention described below are for the purpose of illustrating the present invention and do not limit the present invention. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are included within the scope of protection of the present invention. In addition, the technical features related to the embodiments of the present invention described below may be combined as long as they are not mutually contradictory.

[0010] An image sensor is a device that converts incident light onto a self-photosensitive surface into a corresponding electrical signal. Examples of image sensors include complementary metal oxide semiconductor (CMOS) image sensors and dynamic vision sensors (DVS). CMOS image sensors are active pixel sensors (APS), and DVS are event-based vision sensors (EVS). Related technologies often have overly simple operating modes for image sensors, making them unable to adapt to changing light conditions between weak and strong light, which can seriously affect the image quality of the image sensor. Therefore, an embodiment of the present invention provides an image sensor applicable to optoelectronic devices. Optoelectronic devices are devices that convert incident light into a corresponding electrical signal, such as those used in digital cameras, video cameras, video recorders, facsimiles, image scanners, and digital televisions.

[0011] 1 is a module block diagram of a first type of pixel in an image sensor provided by an embodiment of the present invention. In some embodiments, the image sensor 100 includes a pixel array of a plurality of pixels, each of which includes a floating diffusion node FD, an integration capacitor C, a photoelectric detection circuit 110, a signal readout circuit 140, a self-adaptive power supply Vada , a transmitting circuit 120, and a signal processing circuit 130. The photoelectric detection circuit 110 is connected to a floating diffusion node FD via the transmitting circuit 120, and the floating diffusion node FD is grounded via an integrating capacitor C. The floating diffusion node FD and the integrating capacitor C are respectively connected to a signal reading circuit 140, and the self-adaptive power supply Vada is connected to the floating diffusion node FD via the signal processing circuit 130. In this specification, the self-adaptive power supply V ada The target voltage is defined as the voltage obtained by subtracting the node voltage of the floating diffusion node FD from the reference voltage.

[0012] In practical application, the photoelectric detection circuit 110 photoelectrically converts incident light to obtain a corresponding photocurrent, and then integrates the obtained photocurrent to obtain a corresponding photocharge. The transmitting circuit 120 transmits the photocharges accumulated by the photoelectric detection circuit 110 to the floating diffusion node FD. When the floating diffusion node FD receives the photocharges, it integrates the photocharges into the integrating capacitor C (equivalent to discharging the integrating capacitor C to the floating diffusion node FD) to obtain a corresponding integrated voltage. At the same time, the signal processing circuit 130 generates a logarithmic voltage and a logarithmic current. After the floating diffusion node FD receives the photocharges, the difference between the target voltage and the reference voltage is greater than a preset threshold, indicating that the target voltage is much smaller than the reference voltage. In this case, the logarithmic current is smaller than the photocurrent corresponding to the photocharges, i.e., the logarithmic current does not flow into the floating diffusion node FD. Therefore, the node current of the floating diffusion node FD becomes a photocurrent corresponding to the photocharges, and the node voltage becomes an integrated voltage. However, as time increases, the target voltage also increases. When the target voltage increases and the difference with the reference voltage becomes equal to or less than a preset threshold, the logarithmic current increases and becomes larger than the photocurrent corresponding to the photocharges, and the logarithmic current flows into the floating diffusion node FD. As a result, the node current of the floating diffusion node FD becomes a logarithmic current, and the node voltage becomes a logarithmic voltage. Finally, the signal reading circuit 140 outputs a corresponding image signal based on the node voltage (i.e., the integrated voltage or logarithmic voltage). From this process, the following can be understood. The image sensor according to the embodiment of the present invention has not only a single operating mode, but also two different operating modes, namely, an integral mode (the node voltage is an integral voltage, and the signal reading circuit 140 outputs a corresponding image signal based on the integral voltage) and a logarithmic mode (the node voltage is a logarithmic voltage, and the signal reading circuit 140 outputs a corresponding image signal based on the logarithmic voltage), thereby enabling the image sensor to adapt to a changing environment and improving the image quality of the image sensor.

[0013] For example, in an environment where light intensity varies between low and high levels, after the floating diffusion node FD receives the photocharges, the incident light intensity is still low. In this case, the target voltage is much smaller than the reference voltage, and the image sensor operates in an integral mode. The dark light sensitivity is also improved by integrating the photocharges, thereby improving the signal-to-noise ratio and ensuring low noise characteristics of the image sensor in low-light environments. As the incident light intensity gradually increases over time, the target voltage also gradually increases. When the incident light intensity becomes high, the target voltage becomes very close to the reference voltage. At this time, the image sensor operates in a logarithmic mode. The logarithmic voltage in the logarithmic mode increases the voltage that the photoelectric detection circuit 110 can generate a full well charge, thereby expanding the dynamic range of the image sensor in high-light environments. Thus, in embodiments of the present invention, the image sensor's various operating modes enable the image sensor to achieve both low noise in low-light environments and a high dynamic range in high-light environments, even in environments where light intensity varies between low and high levels. This enables the image sensor to capture high-quality images in both low-light and high-light environments.

[0014] Further, please refer to the second type module block diagram of the pixel in the image sensor provided by the embodiment of the present invention shown in Figure 2. The pixel includes a floating diffusion node FD, an integration capacitor C, a photoelectric detection circuit 110, a signal reading circuit 140, a transmitting circuit 120, a self-adaptive power supply V ada In addition to the signal processing circuit 130, the image sensor further includes a control circuit 150, which is connected to the transmitting circuit 120, the signal processing circuit 130 and the signal reading circuit 140, and is used to control the transmitting circuit 120, the signal processing circuit 130 and the signal reading circuit 140, mainly to control the operating states of the electronic elements in each circuit, and to generate a corresponding image according to the image signal output by the signal reading circuit 140.

[0015] 3, the circuit configuration diagram of a pixel in an image sensor provided by an embodiment of the present invention, the transmitting circuit 120 includes a transmitting transistor T0, a first end of which is connected to the photoelectric detection circuit 110, a second end of which is connected to the control circuit 150, and a third end of which is connected to a floating diffusion node FD. In practical application, the transmitting transistor T0 can be turned on or off based on timing requirements under the control of the control circuit 150, and the floating diffusion node FD receives the photocharges accumulated by the photoelectric detection circuit 110 through the transmitting transistor T0 only when the transmitting transistor T0 is turned on.

[0016] 3, the signal processing circuit 130 includes a reset branch circuit 132 and a logarithmic branch circuit 131. The reset branch circuit 132 and the logarithmic branch circuit 131 are respectively connected to the floating diffusion node FD, and the reset branch circuit 132 and the logarithmic branch circuit 131 are respectively connected to the control circuit 150, and the self-adaptive power supply V adais connected to the floating diffusion node FD through the logarithmic branch circuit 131. In practical application, before the floating diffusion node FD receives the photocharges accumulated by the photoelectric detection circuit 110, the reset branch circuit 132 can reset the node voltage of the floating diffusion node FD under the control of the control circuit 150. After the reset process of the reset branch circuit 132 is completed, the floating diffusion node FD receives the photocharges from the photoelectric detection circuit 110 through the transmitting circuit 120. After the floating diffusion node FD receives the photocharges, the logarithmic branch circuit 131 generates a logarithmic current and a logarithmic voltage, which have a logarithmic relationship. The logarithmic voltage increases with time, and the magnitude of the logarithmic current is positively correlated with the magnitude of the logarithmic voltage. In this embodiment, after the floating diffusion node FD receives the photocharges accumulated by the photoelectric detection circuit 110, the logarithmic current is smaller than the photocurrent corresponding to the photocharges (the target voltage is much smaller than the reference voltage). In this case, the logarithmic current does not flow into the floating diffusion node FD. That is, the node current of the floating diffusion node FD is a photocurrent corresponding to the photocharges, and the node voltage is an integrated voltage. The signal reading circuit 140 outputs a corresponding image signal based on the integrated voltage, and the pixel operates in the integrated mode. However, as time increases, the logarithmic voltage increases, and because the magnitude of the logarithmic current is positively correlated with the magnitude of the logarithmic voltage, the logarithmic current also increases. Therefore, when the logarithmic current increases and becomes larger than the photocurrent corresponding to the photocharges (i.e., the target voltage approaches the reference voltage), the logarithmic current flows into the floating diffusion node FD, the node current of the floating diffusion node FD becomes a logarithmic current, and the node voltage becomes a logarithmic voltage. The signal reading circuit 140 outputs a corresponding image signal based on the logarithmic voltage, and the pixel operates in the logarithmic mode.

[0017] 3, in some embodiments of this embodiment, the logarithmic branch circuit 131 includes a reset transistor T5 and a first switch transistor T2. The gate and drain of the reset transistor T5 are connected to the self-adaptive power supply V ada, the source of the reset transistor T5 is connected to the drain of the first switch transistor T2, the gate of the first switch transistor T2 is connected to the control circuit 150, and the source of the first switch transistor T2 is connected to the floating diffusion node FD. In practical application, the first switch transistor T2 is turned on under the control of the control circuit 150 after the floating diffusion node FD receives the photoelectric charge accumulated by the photoelectric detection circuit 110 (i.e., after the reset branch circuit 132 completes the reset process for the floating diffusion node FD). The reset transistor T5 generates a logarithmic current and a logarithmic voltage after the floating diffusion node FD receives the photoelectric charge accumulated by the photoelectric detection circuit 110. In these embodiments, there is a logarithmic relationship between the drain-source voltage and the drain-source voltage-current of the reset transistor T5. Therefore, the logarithmic current is the drain-source current, the logarithmic voltage is the drain-source voltage, and the reference voltage is the threshold voltage of the reset transistor T5.

[0018] In some embodiments of this embodiment, referring to FIG. 3, the reset branch circuit 132 is connected to a reset power supply V rst and a second switch transistor T1. The drain of the second switch transistor T1 is connected to a reset power supply V rst , the gate of the second switch transistor T1 is connected to the control circuit 150, and the source of the second switch transistor T1 is connected to the floating diffusion node FD. In practical application, before the floating diffusion node FD receives the photoelectric charges accumulated by the photoelectric detection circuit 110, the second switch transistor T1 can be turned on under the control of the control circuit 150, and only when the second switch transistor T1 is turned on, the reset power supply V rst can reset the node voltage of the floating diffusion node FD to its own voltage.

[0019] In this embodiment, after the floating diffusion node FD receives the photocharges accumulated by the photoelectric detection circuit 110, the difference between the target voltage and the reference voltage is initially greater than a preset threshold (i.e., the target voltage is initially much smaller than the reference voltage). At this time, the logarithmic current is smaller than the photocurrent corresponding to the photocharges (i.e., no logarithmic current flows into the floating diffusion node FD). Therefore, the node current of the floating diffusion node FD is the photocurrent corresponding to the photocharges, and the node voltage is an integrated voltage. The signal reading circuit 140 outputs a corresponding image signal based on this integrated voltage, and the image sensor is in an integrated mode. Subsequently, as time passes, the target voltage gradually increases. When the target voltage increases and the difference with the reference voltage becomes less than the preset threshold (i.e., the target voltage is no longer much smaller than the reference voltage but approaches the reference voltage), the logarithmic current increases and becomes larger than the photocurrent corresponding to the photocharges, and the logarithmic current flows into the floating diffusion node FD. Therefore, the node current of the floating diffusion node FD becomes a logarithmic current, and the node voltage becomes a logarithmic voltage, and the signal reading circuit 140 outputs a corresponding image signal based on this logarithmic voltage, and the image sensor becomes a logarithmic form. Note that the target voltage is the self-adaptive power supply V ada Since the self-adaptive voltage of the self-adaptive power supply V ada By rationally setting the voltage, the image sensor can self-adaptively convert between integral and logarithmic forms, better adapt to changing environments, and improve the image quality of the image sensor. The voltage setting of the self-adaptive power supply Vada, which determines the conversion between integral and logarithmic forms of the image sensor, is preferably set to simultaneously achieve effective voltage conversion of the full well charge of the photoelectric detection circuit 110 and switch on photocurrent detection. In environments with changes between weak and strong light, it is preferable to set it to simultaneously achieve low noise characteristics in weak light environments and a high dynamic range in strong light environments.

[0020] To understand the self-adaptation principle of this embodiment more clearly, please refer to the equivalent circuit diagram of the floating diffusion node provided by this embodiment of the present invention shown in Figure 4. In this diagram, the reset transistor T5 is replaced by an equivalent nonlinear resistance R, which is I r =I s* exp(V log / nU T ) can be explained as follows. r represents the current through the equivalent nonlinear resistance R, and V log represents the drain-source voltage (i.e., logarithmic voltage) of the reset transistor T5, n is a rational number greater than 0, and U T and I s After the floating diffusion node FD receives the photocharge accumulated by the photodetection circuit 110, V log In this case, the resistance value of the equivalent nonlinear resistance R is very large, and the resistance value of the equivalent nonlinear resistance R is V log It decreases rapidly as V increases. FD (node ​​voltage of floating diffusion node FD) is V rst (Reset power supply V rst After the transmitting transistor T0 is turned on, V ada -V FD (i.e., the target voltage, V ada is the self-adaptive power supply V ada represents the voltage at T (the threshold voltage of the reset transistor T5, i.e., the reference voltage), the integration capacitor C exhibits a linear discharge and the pixel operates in the integration mode. Then, with increasing time, V ada -V FD V T , the drain-source voltage of the reset transistor T5 will cover the previous integrated voltage (i.e., a logarithmic current flows into the floating diffusion node FD, and the node voltage of the floating diffusion node FD becomes a logarithmic voltage. In this case, the pixel no longer outputs the corresponding image signal at the integrated voltage, but at the logarithmic voltage), and the pixel operates in a logarithmic mode, finally reaching V FD The value of is determined by the voltage drop across the equivalent nonlinear resistance R.

[0021] Further, referring to the timing chart of the image sensor shown in FIG. 5, at time t1, the control circuit 150 controls the transmitting transistor T0 to be turned off by the control signal TX, controls the second switch transistor T1 to be turned on by the control signal SW1, and controls the first switch transistor T2 to be turned off by the control signal SW2, in order to turn the node voltage of the floating diffusion node FD to V rst At time t2, the control circuit 150 controls the second switch transistor T1 to be turned off by the control signal SW1, controls the first switch transistor T2 to be turned on by the control signal SW2, and controls the transmitting transistor T0 to be turned on by the control signal TX. In this case, the node voltage of the floating diffusion node FD is determined by the integrated voltage, i.e., Vada-V within the region I. FD is very small, and thus negative, and the equivalent nonlinear resistance R of the reset transistor T5 is very large, the circuit exhibits a nearly linear discharge mode, and the pixel operates in an integral regime. log gradually increases, and the equivalent nonlinear resistance R of the reset transistor T5 gradually decreases. The node voltage of the floating diffusion node FD is determined not only by the discharge of the integrating capacitor C but also by the logarithmic relationship consisting of the drain-source voltage and drain-source current of the reset transistor T5. In this case, the pixel operates in a logarithmic mode, and is regarded as an APS pixel with a high dynamic range and as the front-end circuit of the EVS. The node voltage is related only to the magnitude of the current photocurrent, and is unrelated to the accumulation of photocurrent by the photodetection circuit 110 during the exposure time, i.e., not to the integration voltage. In Figure 5, I PD represents the intensity of the incident light (i.e., the magnitude of the incident photocurrent), and I PD1 I PD2 Larger than I PD2 I PD3 Larger than I PD3 I PD4Q1, Q2, and Q_FW all represent uniform charges, while Q_FW represents the full well charge of the photoelectric detection circuit 110. The magnitude of the incident photocurrent represents the brightness or darkness of the environment, and when the difference between the brightness and darkness of the environment is large, the embodiment of the present invention can clearly distinguish them (e.g., 501 and 502 in FIG. 5 ). Even when the difference between the brightness and darkness of the environment is small, the embodiment of the present invention can distinguish them, so that the image sensor corresponds to a dark environment in an integral form and a bright environment in a logarithmic form.

[0022] 3 , as an example, the signal read circuit 140 includes an APS read branch circuit 142, an EVS read branch circuit 143, and a drive branch circuit 141. The APS read branch circuit 142 and the EVS read branch circuit 143 are respectively connected to the floating diffusion node FD via the drive branch circuit 141, and the APS read branch circuit 142 and the EVS read branch circuit 143 are respectively connected to the control circuit 150. In practical application, the drive branch circuit 141 buffers the potential of the floating diffusion node FD for outputting the node voltage to the APS read branch circuit 142 and the EVS read branch circuit 143. Then, the APS read branch circuit 142 outputs a corresponding grayscale signal based on the node voltage from the drive branch circuit 141, and the EVS read branch circuit 143 can output a corresponding event signal based on the difference between the node voltage from the drive branch circuit 141 and a preset voltage. In this case, the difference between the node voltage and the preset voltage is to indicate the change (i.e., increase, decrease, or no change) of the intensity of the incident light, for example, whether the difference between the node voltage and the preset voltage is greater than 0, less than 0, or equal to 0 determines the change in the intensity of the incident light, which is the basis for obtaining.

[0023] In some embodiments of this embodiment, the driving branch circuit 141 includes a driving transistor T3 and a driving power supply V dd The gate of the driving transistor T3 is connected to the floating diffusion node FD, and the drain is connected to the driving power supply V dd, and the source of the drive transistor T3 is connected to the APS read branch circuit 142 and the EVS read branch circuit 143. The drive transistor T3 corresponds to a source follower amplifier, and by buffering the potential of the floating diffusion node FD, it is possible to output the node voltage to the APS read branch circuit 142 and the EVS read branch circuit 143. In some embodiments of this embodiment, the APS read branch circuit 142 includes a select transistor T4 and an APS read unit 1421. The drain of the select transistor T4 is connected to the drive branch circuit 141, the gate of the select transistor T4 is connected to the control circuit 150, the source of the select transistor T4 is connected to the APS read unit 1421, and the APS read unit 1421 is connected to the control circuit 150. In practical application, the selection transistor T4 receives the node voltage output from the driving branch circuit 141 and can be turned on or off based on timing requirements under the control of the control circuit 150. Only when the selection transistor T4 is turned on, the APS reading unit 1421 receives the node voltage transmitted through the selection transistor T4. Then, the APS reading unit 1421 outputs a corresponding grayscale signal according to the received node voltage.

[0024] In this embodiment, the signal reading circuit 140 has the function of simultaneously reading out the APS signal and the EVS signal. In this case, the image sensor can simultaneously output the APS image and the EVS image. However, in other embodiments, the signal reading circuit 140 may have the function of outputting only one type of image signal, for example, the APS signal or the EVS signal. If the signal reading circuit 140 has the function of outputting only the APS signal, it may include only the drive branch circuit 141 and the APS read branch circuit 142. In this case, the operation processes of the drive branch circuit 141 and the APS read branch circuit 142 are as described above, and therefore, a description thereof will be omitted. If the signal reading circuit 140 has the function of outputting only the EVS signal, it may include only the drive branch circuit 141 and the EVS read branch circuit 143. In this case, the operation processes of the drive branch circuit 141 and the EVS read branch circuit 143 are as described above, and therefore, a description thereof will be omitted.

[0025] The above examples are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can flexibly configure the present invention based on the examples to suit actual applications. The photoelectric detection circuit 110 may include, but is not limited to, a photodiode, a phototransistor, a clamp diode, or other elements commonly used in the art for achieving photoelectric conversion. In the above examples, the photoelectric detection circuit 110, the control circuit 150, the APS reading branch circuit 142, and the EVS reading branch circuit 143 may be provided one for each pixel in the pixel array, or may be provided as a single circuit shared by all pixels in the pixel array, or may be provided as multiple circuits shared by all pixels in the same array unit in the pixel array. The pixel array may be divided into multiple array units, each of which may include a predetermined number of pixels. For example, each column of pixels in the pixel array may constitute one array unit, or each row of pixels in the pixel array may constitute one array unit. The exposure of the image sensor 100 may be global exposure or rolling shutter exposure. Different exposure methods have different timings for turning on / off each transistor in a pixel, but these can be specifically set according to actual needs, and therefore will not be described in this embodiment.

[0026] 6 is a flowchart of an image output method provided by an embodiment of the present invention. The image output method is implemented by the image sensor 100 provided by an embodiment of the present invention. In some embodiments, the image output method includes: Step 601: The photoelectric detection circuit 110 performs photoelectric conversion on the incident light to obtain corresponding photoelectric charges; Step 602: The transmitting circuit 120 transmits the photocharges to the floating diffusion node FD; Step 603: The signal processing circuit 130 generates a logarithmic voltage and a logarithmic current that exhibit a logarithmic relationship; Step 604: The floating diffusion node FD integrates the photocharges into the integrating capacitor C to obtain a corresponding integrated voltage. After the floating diffusion node FD receives the photocharges, it adjusts the target voltage (i.e., the self-adaptive power supply V ada When the difference between the reference voltage (the node voltage obtained by subtracting the floating diffusion node FD from the adaptive voltage) is greater than a preset threshold and the logarithmic current is smaller than the photocurrent corresponding to the photocharge, the node current of the floating diffusion node FD becomes the photocurrent corresponding to the photocharge, the node voltage of the floating diffusion node FD becomes the integrated voltage, and the target voltage increases with time. When the target voltage increases and the difference from the reference voltage becomes less than the preset threshold, the logarithmic current becomes larger than the photocurrent corresponding to the photocharge and flows into the floating diffusion node FD, so the node current of the floating diffusion node FD becomes a logarithmic current and the node voltage becomes a logarithmic voltage; Step 605: The signal reading circuit 140 outputs a corresponding image signal based on the node voltage of the floating diffusion node FD. The details of the image output method are the same as those in the related description of the image sensor 100, and therefore will not be described here.

[0027] An embodiment of the present invention provides an image sensor and an image output method thereof. The image sensor has two different operation modes, an integral mode and a logarithmic mode. In the embodiment of the present invention, a self-adaptive power supply V ada By rationally setting the voltage, the image sensor can self-adaptively convert between integral and logarithmic forms, thereby better adapting to changing environments and improving the image quality of the image sensor. In changing environments, such as environments that change between weak and strong light, embodiments of the present invention use multiple operating modes of the image sensor to balance the integral characteristics of the APS and the current and voltage characteristics of the EVS front-end circuit, thereby outputting node voltages from small to large photocurrents relatively accurately, achieving both low noise in weak light environments and a high dynamic range in strong light environments, ultimately improving the image quality of the image sensor.

[0028] The steps of a method or algorithm described in the embodiments disclosed herein may be embodied directly in hardware, in software modules executed by a processor, or in a combination of both. The software modules may be located in Random Access Memory (RAM), memory, Read Only Memory (ROM), Programmable ROM, Electrically Erasable Programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0029] The above embodiments may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, they may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions of the present invention may be generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer program instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wire (such as coaxial cable, optical fiber, or digital subscriber line) or wirelessly (such as infrared, radio, or microwave). The computer-readable storage medium may be any available medium accessible by a computer, or may be a data storage device, such as a server or data center, that includes one or more available media. The available medium may be a magnetic medium (floppy disk, hard disk, magnetic tape), an optical medium (DVD), or a semiconductor medium (eg, a solid state disk), etc.

[0030] It should be noted that the embodiments of the present invention are described in a progressive manner, with each embodiment being described in turn by focusing on the differences between the other embodiments, and that it is sufficient to refer to each other for identical or similar parts of the embodiments. The product embodiments are similar to the method embodiments, and therefore the description is simplified, and reference should be made to the method embodiments for relevant parts.

[0031] Additionally, the use of relational terms such as "first" and "second" herein is merely intended to distinguish one entity or operation from another and does not necessarily require or imply an actual relationship or order between those entities or operations. Furthermore, the terms "comprise," "include," or other variations thereof are intended to be non-exclusively inclusive, and a process, method, article, or apparatus that includes a set of elements includes not only those elements but also other elements not expressly listed, as well as elements inherent in the process, method, article, or apparatus. Where further limitations exist, elements defined by "comprising" do not preclude the presence of additional identical elements in a process, method, article, or apparatus that includes the elements.

[0032] The above description of the embodiments will enable those skilled in the art to realize or utilize the teachings of the present invention. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined in the teachings of the present invention may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments disclosed herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. An image sensor including a pixel array of a plurality of pixels, The pixel includes a floating diffusion node, an integration capacitor, a photoelectric detection circuit, a signal reading circuit, a self-adaptive power supply, a transmitting circuit and a signal processing circuit; the photoelectric detection circuit is connected to the floating diffusion node through the transmitting circuit, the floating diffusion node is grounded through the integrating capacitor, the floating diffusion node and the integrating capacitor are respectively connected to the signal reading circuit, the signal processing circuit includes a logarithmic branch circuit, and the self-adaptive power supply is connected to the floating diffusion node through the logarithmic branch circuit; the photoelectric detection circuit converts incident light into an electric charge corresponding to the incident light; the transmitting circuit transmits the photocharges to the floating diffusion node; the logarithmic branch circuit generates a logarithmic voltage and a logarithmic current that are in a logarithmic relationship, the logarithmic voltage increasing with time, and the magnitude of the logarithmic current and the magnitude of the logarithmic voltage being positively correlated; The floating diffusion node integrates the photocharges in the integrating capacitor to obtain a corresponding integrated voltage. After the floating diffusion node receives the photocharges, if the logarithmic current is smaller than the photocurrent corresponding to the photocharges, the node current of the floating diffusion node becomes the photocurrent corresponding to the photocharges, and the node voltage of the floating diffusion node becomes the integrated voltage. With the increase of time, if the logarithmic current increases and becomes larger than the photocurrent corresponding to the photocharges, the logarithmic current flows into the floating diffusion node, causing the node current to become the logarithmic current, and the node voltage to become the logarithmic voltage. The logarithmic current being smaller than the photocurrent corresponding to the photocharges indicates that the difference between the target voltage and the reference voltage is greater than a preset threshold value. The target voltage is the self-adaptive voltage of the self-adaptive power supply minus the node voltage. The reference voltage is equal to the threshold voltage of the logarithmic branch circuit. The logarithmic current being larger than the photocurrent corresponding to the photocharges indicates that the difference between the target voltage and the reference voltage is equal to or smaller than the preset threshold value. The signal reading circuit outputs a corresponding image signal based on the node voltage.

2. the pixel further includes a control circuit; 2. The image sensor of claim 1, wherein the control circuit is connected to the transmitting circuit, the signal processing circuit, and the signal reading circuit, and the control circuit is used to control the transmitting circuit, the signal processing circuit, and the signal reading circuit, and to generate a corresponding image based on the image signal.

3. the signal processing circuit includes a reset branch circuit; the reset branch circuit is connected to the floating diffusion node and the control circuit; 3. The image sensor of claim 2, wherein the reset branch circuit resets the node voltage under the control of the control circuit before the floating diffusion node receives the photocharge.

4. the logarithmic branch circuit includes a reset transistor and a first switch transistor, a gate and a drain of the reset transistor are connected to the self-adaptive power supply, a source of the reset transistor is connected to the drain of the first switch transistor, a gate of the first switch transistor is connected to the control circuit, and a source of the first switch transistor is connected to the floating diffusion node; the first switch transistor is brought into a conductive state under the control of the control circuit when the floating diffusion node receives the photocharge; 4. The image sensor of claim 3, wherein the reset transistor generates the logarithmic voltage and the logarithmic current, the drain-source voltage and the drain-source current of the reset transistor exhibit a logarithmic relationship, the logarithmic voltage becomes the drain-source voltage, the logarithmic current becomes the drain-source current, and the reference voltage becomes a threshold voltage of the reset transistor.

5. the reset branch circuit includes a reset power supply and a second switch transistor, the drain of the second switch transistor is connected to the reset power supply, the gate of the second switch transistor is connected to the control circuit, and the source of the second switch transistor is connected to the floating diffusion node; the second switch transistor is brought into a conductive state under the control of the control circuit before the floating diffusion node receives the photocharges; 4. The image sensor of claim 3, wherein the reset power supply resets the node voltage to a voltage of the reset power supply when the second switch transistor is in a conductive state.

6. the signal read circuit includes a drive branch circuit and an EVS read branch circuit, the EVS read branch circuit is connected to the floating diffusion node via the drive branch circuit, and the EVS read branch circuit is connected to the control circuit; the drive subcircuit buffers the potential of the floating diffusion node to output the node voltage to the EVS read subcircuit; 3. The image sensor of claim 2, wherein the EVS read subcircuit outputs a corresponding event signal based on a difference between the node voltage and a preset voltage.

7. the signal read circuit includes a drive branch circuit and an APS read branch circuit, the APS read branch circuit is connected to the floating diffusion node via the drive branch circuit, and the APS read branch circuit is connected to the control circuit; the driver branch circuit buffers the potential of the floating diffusion node to output the node voltage to the APS read branch circuit; 3. The image sensor of claim 2, wherein the APS readout subcircuit outputs a corresponding grayscale signal based on the node voltage.

8. the signal read circuit includes a drive branch circuit, an APS read branch circuit, and an EVS read branch circuit, the APS read branch circuit and the EVS read branch circuit are respectively connected to the floating diffusion node via the drive branch circuit, and the APS read branch circuit and the EVS read branch circuit are respectively connected to the control circuit; the drive branch circuit buffers the potential of the floating diffusion node to output the node voltage to the APS read branch circuit and the EVS read branch circuit; the APS read subcircuit outputs a corresponding grayscale signal based on the node voltage; 3. The image sensor of claim 2, wherein the EVS read subcircuit outputs a corresponding event signal based on a difference between the node voltage and a preset voltage.

9. the driving branch circuit includes a driving transistor and a driving power supply; a gate of the drive transistor connected to the floating diffusion node, a drain of the drive transistor connected to the drive power supply, and a source of the drive transistor connected to the APS read branch circuit and the EVS read branch circuit; 9. The image sensor of claim 8, wherein the drive transistor buffers the potential of the floating diffusion node to output the node voltage.

10. the APS read branch circuit includes a selection transistor and an APS read unit; The drain of the selection transistor is connected to the driving branch circuit, the gate of the selection transistor is connected to the control circuit, the source of the selection transistor is connected to the APS reading unit, and the APS reading unit is connected to the control circuit; The selection transistor receives the node voltage output from the driving branch circuit, and is turned on or off according to timing requirements by the control circuit; when the selection transistor is turned on, the APS reading unit receives the node voltage transmitted through the selection transistor; The image sensor of claim 7 , wherein the APS reading unit outputs a corresponding grayscale signal based on the node voltage.

11. the transmitting circuit includes a transmitting transistor, a first end of the transmitting transistor is connected to the photoelectric detection circuit, a second end of the transmitting transistor is connected to the control circuit, and a third end of the transmitting transistor is connected to the floating diffusion node; 3. The image sensor of claim 2, wherein the transmitting transistor is turned on or off based on timing requirements under the control of the control circuit, and when the transmitting transistor is turned on, the floating diffusion node receives the photocharges transmitted through the transmitting transistor.

12. 1. An image output method for use with an image sensor, the image sensor including a pixel array of a plurality of pixels; The pixel includes a signal processing circuit, a signal reading circuit, a floating diffusion node, an integration capacitor, a photoelectric detection circuit, a self-adaptive power supply and a transmitting circuit; the photoelectric detection circuit is connected to the floating diffusion node through the transmitting circuit, the floating diffusion node is grounded through the integrating capacitor, the floating diffusion node and the integrating capacitor are respectively connected to the signal reading circuit, the signal processing circuit includes a logarithmic branch circuit, and the self-adaptive power supply is connected to the floating diffusion node through the logarithmic branch circuit; The image output method includes: the photoelectric detection circuit converts incident light into an electric charge corresponding to the incident light; the transmitting circuit transmits the photocharges to the floating diffusion node; the logarithmic branch circuit generates a logarithmic voltage and a logarithmic current in a logarithmic relationship, the logarithmic voltage increasing with increasing time, and the magnitude of the logarithmic current and the magnitude of the logarithmic voltage being positively correlated; The floating diffusion node integrates the photocharges in the integrating capacitor to obtain a corresponding integrated voltage. After the floating diffusion node receives the photocharges, the logarithmic current is smaller than the photocurrent corresponding to the photocharges, thereby causing the node current of the floating diffusion node to become the photocurrent corresponding to the photocharges, and the node voltage of the floating diffusion node to become the integrated voltage. With the increase of time, when the logarithmic current increases and becomes larger than the photocurrent corresponding to the photocharges, the logarithmic current flows into the floating diffusion node, thereby causing the node current to become the logarithmic current, and the node voltage to become the logarithmic voltage. The logarithmic current being smaller than the photocurrent corresponding to the photocharges indicates that the difference between the target voltage and the reference voltage is greater than a predetermined threshold, and the target voltage is the self-adaptive voltage of the self-adaptive power supply minus the node voltage, and the reference voltage is equal to the threshold voltage of the logarithmic branch circuit. The logarithmic current being larger than the photocurrent corresponding to the photocharges indicates that the difference between the target voltage and the reference voltage is equal to or smaller than the predetermined threshold. The signal reading circuit outputs a corresponding image signal based on the node voltage.

13. An optoelectronic device comprising an image sensor according to any one of claims 1 to 11.

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