Image sensor, control method thereof, and storage medium

Abstract

The invention provides an image sensor, a control method thereof and a storage medium. The image sensor comprises a photoelectric conversion circuit; the signal output circuit comprises a floating diffusion node, a first overflow circuit and a second overflow circuit, and the controller is used for controlling the photoelectric conversion circuit and the first overflow circuit to be switched on, the second overflow circuit to be switched off and the potential barrier height of the photoelectric conversion circuit and the potential barrier height of the first overflow circuit to meet a preset condition. According to the invention, redundant charges after the photoelectric conversion circuit is fully loaded are transmitted through the overflow passage, the overflow passage capable of accommodating the redundant charges is formed, the charge accommodating range is enlarged, and the charge storage capacity is improved. And the detection range of the pixel structure in the image sensor on high-intensity light is enlarged, so that the dynamic range is effectively enlarged.

Description

Technical Field

[0001] The present invention relates to the technical field of image sensors, and in particular to an image sensor and a control method and a storage medium thereof. Background Art

[0002] Vehicle CIS (CMOS image sensor) faces four major technical challenges: high dynamic range, namely HDR (Head-up-Display) range, suppression of LED (Light Emitting Diode) flicker, low light sensitivity and extreme environmental conditions.

[0003] In related technologies, such as Figure 1 As shown in the figure, taking the dual conversion gain circuit as an example, the dynamic range of the image sensor is improved based on the dual conversion gain control transistor DCG and a larger overflow capacitor and a long and short exposure timing operation method. Although the dynamic range is improved to a certain extent, the improvement range is limited and it is difficult to meet the more stringent requirements of autonomous driving scenarios for high dynamic range and linear frequency modulation. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0005] To this end, an object of the present invention is to provide an image sensor, which transmits excess charge after the photoelectric conversion circuit is fully loaded through an overflow path, thereby forming an overflow path that can accommodate the excess charge. While increasing the charge accommodation range, it also increases the detection range of the pixel structure in the image sensor to high-intensity light, thereby effectively increasing the dynamic range.

[0006] Therefore, a second objective of the present invention is to provide a control method for an image sensor.

[0007] To this end, a third object of the present invention is to provide a non-transitory computer-readable storage medium.

[0008] In order to achieve the above-mentioned purpose, an embodiment of the first aspect of the present invention proposes an image sensor, which includes: a photoelectric conversion circuit; a signal output circuit, the signal output circuit includes a floating diffusion node, a first overflow circuit and a second overflow circuit, one end of the first overflow circuit is connected to the first end of the photoelectric conversion circuit, and the other end of the first overflow circuit is grounded; a controller, which is used to control the photoelectric conversion circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and when the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet preset conditions, the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit form an overflow path.

[0009] According to the image sensor of the embodiment of the present invention, by controlling the photoelectric conversion circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and when the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet the preset conditions, the charge in the photoelectric conversion circuit can be transmitted to the floating diffusion node and the first overflow circuit to form an overflow path composed of the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit, and the excess charge in the photoelectric conversion circuit after being fully loaded is transmitted through the overflow path to form an overflow path that can accommodate the excess charge. While improving the charge accommodation range, the detection range of the pixel structure in the image sensor to high-intensity light is improved, thereby effectively improving the dynamic range.

[0010] In some embodiments, the signal output circuit further includes: a reset transistor, a drain of the reset transistor is connected to a power supply voltage, and a source of the reset transistor is connected to the floating diffusion node.

[0011] In some embodiments, the first overflow circuit includes: a three-conversion gain control transistor FCG, the drain of which is connected to the first end of the photoelectric conversion circuit; a first overflow capacitor FD3, one end of which is connected to the source of the three-conversion gain control transistor, and the other end of which is grounded.

[0012] In some embodiments, after the first overflow circuit is turned on for a first preset time period, the controller is further used to: control the first overflow circuit to be turned off.

[0013] In some embodiments, the second overflow circuit includes: a dual conversion gain control transistor DCG, the source of which is connected to the source of the reset transistor; a second overflow capacitor FD2, one end of which is connected to the drain of the dual conversion gain control transistor, and the other end of which is grounded.

[0014] In some embodiments, after controlling the first overflow circuit to turn off, the controller is also used to: control the reset transistor and the dual conversion gain control transistor to turn on, so as to obtain a reset signal of the photoelectric conversion circuit under medium conversion gain when the floating diffusion node and the second overflow capacitor are reset.

[0015] In some embodiments, after obtaining a reset signal of the photoelectric conversion circuit at a medium conversion gain, the controller is further used to: control the dual conversion gain control transistor to turn off to obtain a reset signal of the photoelectric conversion circuit at a high conversion gain.

[0016] In some embodiments, the photoelectric conversion circuit includes: a photodiode, the anode of which is grounded; a transfer transistor, the source of which is connected to the cathode of the photodiode, and the drain of which is connected to the first end of the floating diffusion node, for turning on or off the overflow path between the photodiode and the first overflow circuit.

[0017] In some embodiments, after obtaining a reset signal of the photoelectric conversion circuit at a high conversion gain, the controller is further used to: control the transfer transistor to be turned on so that when the charge in the photodiode is transferred to the floating diffusion node, control the transfer transistor to be turned off so as to obtain a valid signal of the photoelectric conversion circuit at a high conversion gain.

[0018] In some embodiments, after obtaining a valid signal of the photoelectric conversion circuit under a high conversion gain, the controller is further used to: control the transfer transistor and the dual conversion gain control transistor to be turned on, so that when the charge in the photodiode is transferred to the floating diffusion node and the second overflow capacitor, the transfer transistor is controlled to be turned off, so as to obtain a valid signal of the photoelectric conversion circuit under a medium conversion gain.

[0019] In some embodiments, after obtaining a valid signal of the photoelectric conversion circuit under a medium conversion gain, the controller is further used to: control the transfer transistor, the dual conversion gain control transistor, and the triple conversion gain control transistor to be turned on, so as to control the transfer transistor to be turned off when the charge in the photodiode is transferred to the floating diffusion node, the first overflow capacitor, and the second overflow capacitor, so as to obtain a valid signal of the photoelectric conversion circuit under a low conversion gain.

[0020] In some embodiments, after obtaining a valid signal of the photoelectric conversion circuit at a low conversion gain, the controller is also used to: control the reset transistor, the transfer transistor, the three-conversion gain control transistor and the dual-conversion gain control transistor to be turned on, so as to control the transfer transistor to be turned off when the floating diffusion node, the first overflow capacitor and the second overflow capacitor are reset, so as to obtain a reset signal of the photoelectric conversion circuit at a low conversion gain.

[0021] In some embodiments, the signal output circuit also includes: an amplifying transistor, the drain of which is connected to the power supply voltage, and the gate of which is connected to the floating diffusion node; a row selecting transistor, the source of which is connected to the source of the amplifying transistor, and the drain of which is connected to the signal reading circuit.

[0022] In some embodiments, after obtaining a reset signal of the photoelectric conversion circuit at a low conversion gain, the controller is also used to: control the photoelectric conversion circuit and the first overflow circuit to be turned on for a second preset time length, wherein the second preset time length is less than the first preset time length.

[0023] In some embodiments, when controlling the photoelectric conversion circuit to be turned on, the controller is further used to: control the reset transistor to be turned on to reset the floating diffusion node, the first overflow capacitor and the second overflow capacitor.

[0024] In some embodiments, when controlling the photoelectric conversion circuit to be turned on, the controller is specifically used to: control the photoelectric conversion circuit to be turned on to a preset opening.

[0025] In some embodiments, the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet a preset condition, including: the barrier height of the transfer transistor is greater than the barrier height of the first overflow circuit.

[0026] In order to achieve the above-mentioned purpose, an embodiment of the second aspect of the present invention proposes a control method of an image sensor, and the control method of the image sensor is used for the image sensor described in the above-mentioned embodiment, the image sensor includes a photoelectric conversion circuit, a signal output circuit and a controller, the signal output circuit includes a floating diffusion node and an overflow circuit, one end of the overflow circuit is connected to the first end of the photoelectric conversion circuit, and the other end of the overflow circuit is grounded, the control method of the image sensor includes: when the photoelectric conversion circuit and the first overflow circuit are controlled to be turned on and the second overflow circuit is turned off, and when the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet preset conditions, the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit form an overflow path.

[0027] According to the control method of the image sensor of the embodiment of the present invention, by controlling the photoelectric conversion circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and when the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet the preset conditions, the charge in the photoelectric conversion circuit can be transmitted to the floating diffusion node and the first overflow circuit to form an overflow path composed of the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit, and the excess charge in the photoelectric conversion circuit after being fully loaded is transmitted through the overflow path to form an overflow path that can accommodate the excess charge. While improving the charge accommodation range, the detection range of the pixel structure in the image sensor to high-intensity light is improved, thereby effectively improving the dynamic range.

[0028] In order to achieve the above-mentioned purpose, an embodiment of the third aspect of the present invention proposes a non-temporary computer-readable storage medium, on which a control program of an image sensor is stored. When the control program of the image sensor is executed by a processor, the control method of the image sensor described in the above-mentioned embodiment is implemented.

[0029] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0031] Figure 1 is a schematic diagram of the structure of an image sensor of related technology;

[0032] Figure 2 is a structural block diagram of an image sensor according to an embodiment of the present invention;

[0033] Figure 3 is a timing diagram of an image sensor according to an embodiment of the present invention;

[0034] Figure 4 is an equivalent potential diagram of an image sensor according to an embodiment of the present invention.

[0035] Reference numerals:

[0036] Image sensor 10;

[0037] Photoelectric conversion circuit 1; signal output circuit 2;

[0038] A first overflow circuit 21; a second overflow circuit 22. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. Embodiments of the present invention are described in detail below.

[0040] In the relevant technology, the high dynamic range required for autonomous driving scenarios generally exceeds 120dB, usually between 120dB-140dB, such as driving from a dark basement to the outdoors facing the strong sunlight, and sensing pedestrians under the shade of trees at night under the illumination of oncoming high-beam headlights. These all require image sensors to have a high dynamic range. For LED signs and traffic lights, image sensors sometimes fail to capture signals due to frequency asynchrony. This is not a problem for the driver's eyes, but it is a big challenge for machine vision. At this time, the image sensor is required to suppress LED flicker. In addition, most existing technologies use a long and short exposure timing operation method. Although it can improve the dynamic range of the image sensor to a certain extent, it cannot meet the performance of suppressing LED flicker.

[0041] Combine the following Figure 2-Figure 4 An image sensor 10 according to an embodiment of the present invention will be described.

[0042] like Figure 2 As shown, the image sensor 10 of the embodiment of the present invention includes: a photoelectric conversion circuit 1, a signal output circuit 2 and a controller (not shown in the figure), the signal output circuit 2 includes a floating diffusion node, for example, FD1, a first overflow circuit 21 and a second overflow circuit 22, wherein:

[0043] The floating diffusion node FD1 is used to store the charge corresponding to the electrical signal obtained by the photoelectric conversion circuit 1 converting the incident light; one end of the first overflow circuit 21 is connected to the first end of the photoelectric conversion circuit 1, and the other end of the first overflow circuit 21 is grounded; the controller is used to control the photoelectric conversion circuit 1 and the first overflow circuit 21 to be turned on and the second overflow circuit 22 to be turned off, and when the barrier height of the photoelectric conversion circuit 1 and the barrier height of the first overflow circuit 21 meet the preset conditions, the photoelectric conversion circuit 1, the floating diffusion node FD1 and the first overflow circuit 21 form an overflow path.

[0044] In an embodiment, Figure 3 and Figure 4As shown, after the photoelectric conversion circuit 1 is exposed, the controller controls the photoelectric conversion circuit 1 and the first overflow circuit 21 to be turned on, connecting the overflow path between the photoelectric conversion circuit 1 and the first overflow circuit 21, and the second overflow circuit 22 is turned off, so that the second overflow circuit 22 does not participate in the overflow process, and the barrier height of the photoelectric conversion circuit 1 and the barrier height of the first overflow circuit 21 meet the preset conditions, for example, the barrier height of the photoelectric conversion circuit 1 is greater than the barrier height of the first overflow circuit 21, the charge in the photoelectric conversion circuit 1 can be transmitted to the first overflow circuit 21, forming an integration stage, so that the photoelectric conversion circuit 1, the floating diffusion node FD1 and the first overflow circuit 21 form an overflow path, the photoelectric conversion circuit 1 and the first overflow circuit 21 are connected through the floating diffusion node FD1, and the excess charge in the photoelectric conversion circuit 1 after full load is transmitted to the first overflow circuit 21, which can accommodate more charges, expand the light detection range of the image sensor 10, such as high-intensity light, and effectively improve the dynamic range.

[0045] According to the image sensor 10 of the embodiment of the present invention, by controlling the photoelectric conversion circuit 1 and the first overflow circuit 21 to be turned on and the second overflow circuit 22 to be turned off, and when the barrier height of the photoelectric conversion circuit 1 and the barrier height of the first overflow circuit 21 meet the preset conditions, the charge in the photoelectric conversion circuit 1 can be transmitted to the floating diffusion node FD1 and the first overflow circuit 21, forming an overflow path composed of the photoelectric conversion circuit 1, the floating diffusion node FD1 and the first overflow circuit 21, and the excess charge after the photoelectric conversion circuit 1 is fully loaded is transmitted through the overflow path to form an overflow path that can accommodate the excess charge. While improving the charge accommodation range, the detection range of the pixel structure in the image sensor 10 to high-intensity light is improved, thereby effectively improving the dynamic range.

[0046] In some embodiments, Figure 2 As shown, the signal output circuit 2 also includes: a reset transistor, for example, denoted as RST, the drain of the reset transistor RST is connected to the power supply voltage VDDP, the source of the reset transistor RST is connected to the floating diffusion node FD1, and the connection between the floating diffusion node FD1 and the power supply voltage VDDP is turned on or off by the reset transistor RST.

[0047] In an embodiment, Figure 3 and Figure 4 As shown, before exposing the photoelectric conversion circuit 1, the controller controls the reset transistor RST in the signal output circuit 2 to be turned on, clears the charges in the photoelectric conversion circuit 1 and the signal output circuit 2, so as to reset the floating diffusion node FD1, the first overflow circuit 21 and the second overflow circuit 22; and the controller can also control the reset transistor RST in the signal output circuit 2 to be turned off, so as to disconnect the connection loop between the floating diffusion node FD1 and the power supply voltage VDDP.

[0048] In some embodiments, Figure 2 As shown, the first overflow circuit 21 includes: three conversion gain control transistors, for example, denoted as FCG, and a first overflow capacitor, for example, denoted as FD3, wherein the drain of the three conversion gain control transistors FCG is connected to the first end of the photoelectric conversion circuit 1; one end of the first overflow capacitor FD3 is connected to the source of the three conversion gain control transistors FCG, and the other end of the first overflow capacitor FD3 is grounded.

[0049] In an embodiment, Figure 3 and Figure 4 As shown, when the controller controls the first overflow circuit 21 to be turned on for the first preset time, the three conversion gain control transistors FCG in the first overflow circuit 21 are controlled to be turned on for the first preset time, for example, from the time T0 to the time T1, to form an integration stage, so that the photoelectric conversion circuit 1, the floating diffusion node FD1 and the first overflow capacitor FD3 form an overflow path, and the charge obtained by the photoelectric conversion circuit 1 is transferred to the first overflow capacitor FD3 in the first overflow circuit 21.

[0050] In some embodiments, after the first overflow circuit 21 is turned on for a first preset time period, the controller is further used to: control the first overflow circuit 21 to be turned off.

[0051] In an embodiment, Figure 3 and Figure 4 As shown, after the first overflow circuit 21 is turned on, its on-time is recorded. When the on-time reaches a first preset time, such as T1, it is considered that the integration phase is over, and the controller controls the three conversion gain control transistors FCG in the first overflow circuit 21 to turn off, the overflow process ends, and the data reading process starts.

[0052] In some embodiments, Figure 2 As shown, the second overflow circuit 22 includes: a dual conversion gain control transistor, for example, denoted as DCG, and a second overflow capacitor, for example, denoted as FD2, wherein the source of the dual conversion gain control transistor DCG is connected to the source of the reset transistor RST; one end of the second overflow capacitor FD2 is connected to the drain of the dual conversion gain control transistor DCG, and the other end of the second overflow capacitor FD2 is grounded.

[0053] In an embodiment, Figure 3 and Figure 4 As shown, when the controller controls the second overflow circuit 22 to be turned off, the dual conversion gain control transistor DCG in the second overflow circuit 22 is controlled to be turned off, so that the second overflow capacitor FD2 in the second overflow circuit 22 does not participate in the overflow process, ensuring that the excess charge in the photoelectric conversion circuit 1 will not overflow to the second overflow capacitor FD2 in the second overflow circuit 22 after being fully loaded.

[0054] In some embodiments, after controlling the first overflow circuit 21 to turn off, the controller is also used to: control the reset transistor RST and the dual conversion gain control transistor DCG to turn on, so as to obtain a reset signal of the photoelectric conversion circuit 1 under medium conversion gain when the floating diffusion node FD1 and the second overflow capacitor FD2 complete reset.

[0055] In an embodiment, Figure 3 and Figure 4 As shown, after controlling the first overflow circuit 21 to turn off, the controller controls the reset transistor RST and the dual conversion gain control transistor DCG to turn on at time T2, resets the floating diffusion node FD1 and the second overflow capacitor FD2, and clears the noise signal in the integration stage, so as to obtain the reset signal of the photoelectric conversion circuit 1 under the medium conversion gain, for example, recorded as MCG_SHR, when the floating diffusion node FD1 and the second overflow capacitor FD2 are reset.

[0056] In some embodiments, after obtaining the reset signal of the photoelectric conversion circuit 1 at a medium conversion gain, the controller is further used to: control the dual conversion gain control transistor DCG to turn off to obtain the reset signal of the photoelectric conversion circuit 1 at a high conversion gain.

[0057] In an embodiment, Figure 3 and Figure 4 As shown, after obtaining the reset signal MCG_SHR of the photoelectric conversion circuit 1 under the medium conversion gain, the controller controls the dual conversion gain control transistor DCG to turn off at time T3 to obtain the reset signal of the photoelectric conversion circuit 1 under the high conversion gain, for example, recorded as HCG_SHR.

[0058] In some embodiments, Figure 2 As shown, the photoelectric conversion circuit 1 includes: a photodiode, for example, denoted as PD, and a transmission diode, for example, denoted as TX, wherein the anode of the photodiode PD is grounded; the source of the transmission transistor TX is connected to the cathode of the photodiode PD, and the drain of the transmission transistor TX is connected to the first end of the floating diffusion node FD1, which is used to turn on or off the overflow path between the photodiode PD and the first overflow circuit 21. When the controller controls the photoelectric conversion circuit 1 to be turned on, it is specifically used to: control the photoelectric conversion circuit 1 to be turned on to a preset opening.

[0059] In an embodiment, Figure 3 and Figure 4As shown, after the photoelectric conversion circuit 1 is exposed, the photodiode PD in the photoelectric conversion circuit 1 converts the received light into electric charges, and the transfer transistor TX turns on or off the overflow path between the photodiode PD and the first overflow circuit 21. When the controller controls the photoelectric conversion circuit 1 to be turned on, the transfer transistor TX in the photoelectric conversion circuit 1 is controlled to be turned on to a preset opening, that is, the photoelectric conversion circuit 1 is not completely turned off, so as to transfer the charge in the photodiode PD to the floating diffusion node FD1; when the controller controls the photoelectric conversion circuit 1 to be turned off, the transfer transistor TX in the photoelectric conversion circuit 1 is controlled to be turned off, so as to disconnect the overflow path between the photodiode PD and the first overflow circuit 21.

[0060] In some embodiments, after obtaining the reset signal of the photoelectric conversion circuit 1 under high conversion gain, the controller is also used to: control the transfer transistor TX to be turned on, so that when the charge in the photodiode PD is transferred to the floating diffusion node FD1, the transfer transistor TX is controlled to be turned off, so as to obtain the effective signal of the photoelectric conversion circuit 1 under high conversion gain.

[0061] In an embodiment, Figure 3 and Figure 4 As shown, after obtaining the reset signal HCG_SHR of the photoelectric conversion circuit 1 under high conversion gain, the controller controls the transfer transistor TX to be turned on at time T4, and the charge in the photodiode PD begins to be transmitted to the floating diffusion node FD1, so that when the charge in the photodiode PD is transmitted to the floating diffusion node FD1, the transfer transistor TX is controlled to be turned off to obtain the effective signal of the photoelectric conversion circuit 1 under high conversion gain, for example, recorded as HCG_SHS.

[0062] In some embodiments, after obtaining the effective signal of the photoelectric conversion circuit 1 under high conversion gain, the controller is also used to: control the transfer transistor TX and the dual conversion gain control transistor DCG to be turned on, so as to control the transfer transistor TX to be turned off when the charge in the photodiode PD is transferred to the floating diffusion node FD1 and the second overflow capacitor FD2, so as to obtain the effective signal of the photoelectric conversion circuit 1 under medium conversion gain.

[0063] In an embodiment, Figure 3 and Figure 4 As shown, after obtaining the effective signal HCG_SHS of the photoelectric conversion circuit 1 under high conversion gain, the controller controls the transfer transistor TX and the dual conversion gain control transistor DCG to be turned on at time T5, and the charge in the photodiode PD begins to be transmitted to the floating diffusion node FD1 and the second overflow capacitor FD2. When the charge in the photodiode PD is transmitted to the floating diffusion node FD1 and the second overflow capacitor FD2, the transfer transistor TX is controlled to be turned off to obtain the effective signal of the photoelectric conversion circuit 1 under medium conversion gain, for example, recorded as MCG_SHS.

[0064] In some embodiments, after obtaining the effective signal of the photoelectric conversion circuit 1 under medium conversion gain, the controller is also used to: control the transfer transistor TX, the dual conversion gain control transistor DCG and the triple conversion gain control transistor FCG to be turned on, so as to control the transfer transistor TX to be turned off when the charge in the photodiode PD is transferred to the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, so as to obtain the effective signal of the photoelectric conversion circuit 1 under low conversion gain.

[0065] In an embodiment, Figure 3 and Figure 4 As shown, after obtaining the effective signal MCG_SHS of the photoelectric conversion circuit 1 under the medium conversion gain, the controller controls the transmission transistor TX, the dual conversion gain control transistor DCG and the triple conversion gain control transistor FCG to be turned on at time T6, and the charge in the photodiode PD begins to be transmitted to the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, and when the charge in the photodiode PD is transmitted to the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, the transmission transistor TX is controlled to be turned off to obtain the effective signal of the photoelectric conversion circuit 1 under the low conversion gain, for example, recorded as LCG_SHS.

[0066] In some embodiments, after obtaining the valid signal of the photoelectric conversion circuit 1 under low conversion gain, the controller is also used to: control the reset transistor RST, the transfer transistor TX, the three conversion gain control transistor FCG and the dual conversion gain control transistor DCG to be turned on, so as to control the transfer transistor TX to be turned off when the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2 are reset, so as to obtain the reset signal of the photoelectric conversion circuit 1 under low conversion gain.

[0067] In an embodiment, Figure 3 and Figure 4 As shown, after obtaining the effective signal LCG_SHS of the photoelectric conversion circuit 1 at low conversion gain, the controller controls the reset transistor RST, the transmission transistor TX, the three conversion gain control transistor FCG and the dual conversion gain control transistor DCG to be turned on at time T7, and resets the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, so that when the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2 are reset, the transmission transistor TX is controlled to be turned off, so as to obtain the reset signal of the photoelectric conversion circuit 1 at low conversion gain, for example, recorded as LCG_SHR.

[0068] In some embodiments, Figure 2As shown, the signal output circuit 2 also includes: an amplifier transistor, for example, denoted as SF, and a row selection transistor, for example, denoted as RS, wherein the drain of the amplifier transistor SF is connected to the power supply voltage VDDP, and the gate of the amplifier transistor SF is connected to the floating diffusion node FD1; the source of the row selection transistor RS is connected to the source of the amplifier transistor SF, and the drain of the row selection transistor RS is connected to the signal reading circuit (not marked in the figure).

[0069] In some embodiments, after obtaining a reset signal of the photoelectric conversion circuit 1 at a low conversion gain, the controller is further used to: control the photoelectric conversion circuit 1 and the first overflow circuit 21 to be turned on for a second preset time length, wherein the second preset time length is less than the first preset time length.

[0070] In an embodiment, Figure 3 and Figure 4 As shown, after obtaining the reset signal LCG_SHR of the photoelectric conversion circuit 1 under low conversion gain, the controller controls the photoelectric conversion circuit 1 and the first overflow circuit 21 to be turned on for a second preset time, wherein the second preset time is less than the first preset time, wherein the ratio of the second preset time to the first preset time can be adjusted according to the dynamic range and signal-to-noise ratio requirements, and the dynamic range is further improved by splicing the original longer exposure time, namely the first preset time, into a shorter exposure time, namely the second preset time.

[0071] In some embodiments, when the photoelectric conversion circuit 1 is controlled to be turned on, the controller is further used to: control the reset transistor RST to be turned on, so as to reset the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2.

[0072] In an embodiment, Figure 3 and Figure 4 As shown, before exposing the photodiode PD in the photoelectric conversion circuit 1, the controller controls the reset tube RST in the signal output circuit 2 to be turned on to reset the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, thereby improving the accuracy of the reset voltage and signal voltage collected subsequently, and starting to expose the photodiode PD in the photoelectric conversion circuit 1.

[0073] In some embodiments, controlling the second overflow circuit 22 to be turned off includes: controlling the dual conversion gain control transistor DCG to be turned off.

[0074] In an embodiment, Figure 3 and Figure 4As shown, after the photodiode PD in the photoelectric conversion circuit 1 is exposed, the controller controls the dual conversion gain control transistor DCG in the second overflow circuit 22 to be turned off, so that the second overflow capacitor FD2 in the second overflow circuit 22 does not participate in the overflow process, ensuring that the excess charge in the photodiode PD will not overflow to the second overflow capacitor FD2 after it is fully loaded.

[0075] In some embodiments, the barrier height of the photoelectric conversion circuit 1 and the barrier height of the first overflow circuit 21 meet preset conditions, including: the barrier height of the transmission transistor TX in the photoelectric conversion circuit 1 is greater than the barrier height of the three conversion gain control transistor FCG in the first overflow circuit 21.

[0076] The present invention improves the dynamic range of the image sensor 10 while improving the signal-to-noise ratio, thereby suppressing LED flicker.

[0077] According to the image sensor 10 of the embodiment of the present invention, by controlling the photoelectric conversion circuit 1 and the first overflow circuit 21 to be turned on and the second overflow circuit 22 to be turned off, and when the barrier height of the photoelectric conversion circuit 1 and the barrier height of the first overflow circuit 21 meet the preset conditions, the charge in the photoelectric conversion circuit 1 can be transmitted to the floating diffusion node FD1 and the first overflow circuit 21, forming an overflow path composed of the photoelectric conversion circuit 1, the floating diffusion node FD1 and the first overflow circuit 21, and the excess charge after the photoelectric conversion circuit 1 is fully loaded is transmitted through the overflow path to form an overflow path that can accommodate the excess charge. While improving the charge accommodation range, the detection range of the pixel structure in the image sensor 10 to high-intensity light is improved, thereby effectively improving the dynamic range.

[0078] The following is an example of the control method of the image sensor according to the embodiment of the present invention.

[0079] The control method of the image sensor of the embodiment of the present invention is used for the image sensor of the above embodiment, and the image sensor includes: a photoelectric conversion circuit, a signal output circuit and a controller, the signal output circuit includes a floating diffusion node FD1 and an overflow circuit, one end of the overflow circuit is connected to the first end of the photoelectric conversion circuit, and the other end of the overflow circuit is grounded. Among them, the floating diffusion node FD1 is used to store the charge corresponding to the electrical signal obtained by the photoelectric conversion circuit 1 converting the incident light; the overflow circuit includes a first overflow circuit and a second overflow circuit, one end of the first overflow circuit is connected to the first end of the photoelectric conversion circuit, and the other end of the first overflow circuit is grounded.

[0080] The control method of the image sensor of the embodiment of the present invention includes: controlling the photoelectric conversion circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and when the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet preset conditions, the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit form an overflow path.

[0081] In an embodiment, after the photoelectric conversion circuit is exposed, the controller controls the photoelectric conversion circuit and the first overflow circuit to be turned on, connecting the overflow path between the photoelectric conversion circuit and the first overflow circuit, and the second overflow circuit is turned off, so that the second overflow circuit does not participate in the overflow process, and the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet preset conditions, for example, the barrier height of the photoelectric conversion circuit is greater than the barrier height of the first overflow circuit, the charge in the photoelectric conversion circuit can be transmitted to the first overflow circuit to form an integration stage, so that the photoelectric conversion circuit, the floating diffusion node FD1 and the first overflow circuit form an overflow path, and the photoelectric conversion circuit and the first overflow circuit are connected by the floating diffusion node FD1, and the excess charge in the photoelectric conversion circuit after being fully loaded is transmitted to the first overflow circuit, which can accommodate more charge, expand the light detection range of the image sensor, such as high-intensity light, and effectively improve the dynamic range.

[0082] According to the control method of the image sensor of the embodiment of the present invention, by controlling the photoelectric conversion circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and when the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet the preset conditions, the charge in the photoelectric conversion circuit can be transmitted to the floating diffusion node and the first overflow circuit to form an overflow path composed of the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit, and the excess charge in the photoelectric conversion circuit after being fully loaded is transmitted through the overflow path to form an overflow path that can accommodate the excess charge. While improving the charge accommodation range, the detection range of the pixel structure in the image sensor to high-intensity light is improved, thereby effectively improving the dynamic range.

[0083] The following describes a non-transitory computer-readable storage medium according to an embodiment of the present invention.

[0084] The non-transitory computer-readable storage medium of the embodiment of the present invention stores a control program for the image sensor. When the control program for the image sensor is executed by a processor, the control method for the image sensor of the above embodiment is implemented.

[0085] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0087] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0088] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An image sensor, characterized in that: include: Photoelectric conversion circuit; a signal output circuit, the signal output circuit comprising a floating diffusion node, a first overflow circuit and a second overflow circuit, one end of the first overflow circuit is connected to the first end of the photoelectric conversion circuit, and the other end of the first overflow circuit is grounded; A controller is used to control the photoelectric conversion circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and when the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet preset conditions, the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit form an overflow path.

2. The image sensor according to claim 1, characterized in that The signal output circuit also includes: A reset transistor, wherein a drain of the reset transistor is connected to a power supply voltage, and a source of the reset transistor is connected to the floating diffusion node.

3. The image sensor according to claim 1 or 2, characterized in that: The first overflow circuit comprises: three conversion gain control transistors, wherein the drain of the three conversion gain control transistors is connected to the first end of the photoelectric conversion circuit; A first overflow capacitor, one end of the first overflow capacitor is connected to the source of the three conversion gain control transistors, and the other end of the first overflow capacitor is grounded.

4. The image sensor according to claim 1 or 3, characterized in that: After the first overflow circuit is turned on for a first preset time period, the controller is further used to control the first overflow circuit to be turned off.

5. The image sensor according to claim 4, characterized in that: The second overflow circuit comprises: a dual conversion gain control transistor, wherein a source of the dual conversion gain control transistor is connected to a source of the reset transistor; A second overflow capacitor, one end of the second overflow capacitor is connected to the drain of the dual conversion gain control transistor, and the other end of the second overflow capacitor is grounded.

6. The image sensor according to claim 5, characterized in that After controlling the first overflow circuit to be turned off, the controller is further configured to: The reset transistor and the dual conversion gain control transistor are controlled to be turned on, so as to obtain a reset signal of the photoelectric conversion circuit under a medium conversion gain when the floating diffusion node and the second overflow capacitor are reset.

7. The image sensor according to claim 6, characterized in that: After obtaining a reset signal of the photoelectric conversion circuit at a medium conversion gain, the controller is further used to: The dual conversion gain control transistor is controlled to be turned off to obtain a reset signal of the photoelectric conversion circuit under a high conversion gain.

8. The image sensor according to claim 1 or 7, characterized in that: The photoelectric conversion circuit comprises: A photodiode, wherein the anode of the photodiode is grounded; A transfer transistor, wherein the source of the transfer transistor is connected to the cathode of the photodiode, and the drain of the transfer transistor is connected to the first end of the floating diffusion node, and is used to turn on or off the overflow path between the photodiode and the first overflow circuit.

9. The image sensor according to claim 8, characterized in that: After obtaining a reset signal of the photoelectric conversion circuit under a high conversion gain, the controller is further used to: The transfer transistor is controlled to be turned on, so that when the charge in the photodiode is transferred to the floating diffusion node, the transfer transistor is controlled to be turned off, so as to obtain a valid signal of the photoelectric conversion circuit under a high conversion gain.

10. The image sensor according to claim 9, characterized in that: After obtaining the effective signal of the photoelectric conversion circuit under high conversion gain, the controller is further used for: The transfer transistor and the dual conversion gain control transistor are controlled to be turned on, so that when the charge in the photodiode is transferred to the floating diffusion node and the second overflow capacitor, the transfer transistor is controlled to be turned off to obtain a valid signal of the photoelectric conversion circuit under a medium conversion gain.

11. The image sensor according to claim 10, characterized in that: After obtaining the effective signal of the photoelectric conversion circuit at the medium conversion gain, the controller is further used for: The transfer transistor, the dual conversion gain control transistor and the triple conversion gain control transistor are controlled to be turned on, so that when the charge in the photodiode is transferred to the floating diffusion node, the first overflow capacitor and the second overflow capacitor, the transfer transistor is controlled to be turned off to obtain a valid signal of the photoelectric conversion circuit at a low conversion gain.

12. The image sensor according to claim 11, characterized in that: After obtaining the effective signal of the photoelectric conversion circuit at the low conversion gain, the controller is further used for: The reset transistor, the transfer transistor, the three-conversion gain control transistor and the dual-conversion gain control transistor are controlled to be turned on, so as to control the transfer transistor to be turned off when the floating diffusion node, the first overflow capacitor and the second overflow capacitor are reset, so as to obtain a reset signal of the photoelectric conversion circuit under low conversion gain.

13. The image sensor according to claim 1 or 12, characterized in that: The signal output circuit also includes: an amplifying transistor, wherein a drain of the amplifying transistor is connected to a power supply voltage, and a gate of the amplifying transistor is connected to the floating diffusion node; A row selection transistor, wherein a source of the row selection transistor is connected to a source of the amplifying transistor, and a drain of the row selection transistor is connected to a signal reading circuit.

14. The image sensor according to claim 13, characterized in that: After obtaining a reset signal of the photoelectric conversion circuit at a low conversion gain, the controller is further used to: The photoelectric conversion circuit and the first overflow circuit are controlled to be turned on for a second preset time period, wherein the second preset time period is shorter than the first preset time period.

15. The image sensor according to claim 5, characterized in that: When controlling the photoelectric conversion circuit to be turned on, the controller is further used for: The reset transistor is controlled to be turned on to reset the floating diffusion node, the first overflow capacitor and the second overflow capacitor.

16. The image sensor according to claim 1, characterized in that When controlling the photoelectric conversion circuit to be turned on, the controller is specifically used to: control the photoelectric conversion circuit to be turned on to a preset opening.

17. The image sensor according to claim 8, characterized in that The potential barrier height of the photoelectric conversion circuit and the potential barrier height of the first overflow circuit meet a preset condition, including: A barrier height of the transfer transistor is greater than a barrier height of the first overflow circuit.

18. A method for controlling an image sensor, characterized in that: Used in the image sensor according to any one of claims 1 to 17, the image sensor comprising a photoelectric conversion circuit, a signal output circuit and a controller, the signal output circuit comprising a floating diffusion node and an overflow circuit, one end of the overflow circuit is connected to the first end of the photoelectric conversion circuit, and the other end of the overflow circuit is grounded, the control method comprising: When the photoelectric conversion circuit and the first overflow circuit are controlled to be turned on and the second overflow circuit is turned off and the barrier height of the photoelectric conversion circuit and the barrier height of the first overflow circuit meet preset conditions, the photoelectric conversion circuit, the floating diffusion node and the first overflow circuit form an overflow path.

19. A non-transitory computer-readable storage medium, characterized in that: The computer-readable storage medium stores a control program of the image sensor, and when the control program of the image sensor is executed by the processor, the control method of the image sensor according to claim 18 is implemented.

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