Image sensor, control method thereof, and storage medium

Abstract

The invention provides an image sensor, a control method thereof and a storage medium, and the image sensor comprises a photoelectric conversion circuit which comprises a first photoelectric conversion sub-circuit; the signal output circuit comprises a floating diffusion node, a first overflow circuit and a second overflow circuit; the controller is used for controlling the first photoelectric conversion sub-circuit and the first overflow circuit to be switched on and the second overflow circuit to be switched off, and the barrier height of the first photoelectric conversion sub-circuit and the barrier height of the first overflow circuit meet a preset condition, so that the first photoelectric conversion sub-circuit, the floating diffusion node and the first overflow circuit form an overflow path; according to the invention, after the first photoelectric conversion sub-circuit is fully loaded, redundant charges are transmitted through the overflow passage, the overflow passage capable of accommodating the redundant charges is formed, the charge accommodating range is enlarged, the detection range of a pixel structure in the image sensor for high-intensity light is enlarged, and thus 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 first photoelectric conversion sub-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, which includes a first photoelectric conversion sub-circuit; a signal output circuit, which 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 floating diffusion node, and the other end of the first overflow circuit is grounded; a controller, which is used to control the first photoelectric conversion sub-circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and the barrier heights of the first photoelectric conversion sub-circuit and the first overflow circuit meet preset conditions, so that the first photoelectric conversion sub-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 first photoelectric conversion sub-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 first photoelectric conversion sub-circuit and the barrier height of the first overflow circuit meet preset conditions, the charge in the first photoelectric conversion sub-circuit can be transmitted to the floating diffusion node and the first overflow circuit to form an overflow path composed of the first photoelectric conversion circuit, the floating diffusion node and the first overflow circuit, and the excess charge in the first photoelectric conversion sub-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 first photoelectric conversion sub-circuit includes: a first photodiode, the anode of the first photodiode is grounded; a first transfer transistor, the source of the first transfer transistor is connected to the cathode of the first photodiode, and the drain of the first transfer transistor is connected to the floating diffusion node, for turning on or off the overflow path between the first photodiode and the first overflow circuit.

[0011] In some embodiments, the first overflow circuit includes: a first overflow capacitor, one end of which is grounded; three conversion gain control transistors, the drains of which are connected to the floating diffusion node, and the sources of which are connected to the other end of the first overflow capacitor.

[0012] In some embodiments, the barrier heights of the first photoelectric conversion sub-circuit and the first overflow circuit meet preset conditions, including: the barrier height of the first transfer transistor exceeds the barrier height of the three conversion gain control transistors.

[0013] In some embodiments, the second overflow circuit includes: a dual conversion gain control transistor, a source of the dual conversion gain control transistor is connected to the floating diffusion node; 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.

[0014] In some embodiments, the photoelectric conversion circuit further includes: at least one second photoelectric conversion sub-circuit.

[0015] In some embodiments, the second photoelectric conversion subcircuit includes: a second photodiode, the anode of the second photodiode is grounded; a second transfer transistor, the source of the second transfer transistor is connected to the cathode of the second photodiode, and the drain of the second transfer transistor is connected to the floating diffusion node.

[0016] In some embodiments, when controlling the second overflow circuit to be turned off, the controller is further used to: control the second transfer transistor to be turned off.

[0017] In some embodiments, after controlling the first photoelectric conversion sub-circuit and the first overflow circuit to be turned on, the controller is also used to: control the first transmission transistor and the three conversion gain control transistors to be turned off, and after the first transmission transistor and the three conversion gain control transistors are turned off, control the dual conversion gain control transistor to be turned on, so as to obtain a first reset signal of the photoelectric conversion circuit under medium conversion gain.

[0018] In some embodiments, after obtaining the first 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 the first reset signal of the photoelectric conversion circuit at a high conversion gain.

[0019] In some embodiments, after obtaining the first reset signal of the photoelectric conversion circuit under high conversion gain, the controller is also used to: control the first transfer transistor to be turned on, so as to control the first transfer transistor to be turned off when the charge in the first photodiode is transferred to the floating diffusion node, so as to obtain the first valid signal of the photoelectric conversion circuit under high conversion gain.

[0020] In some embodiments, after obtaining the first valid signal of the photoelectric conversion circuit under high conversion gain, the controller is also used to: control the dual conversion gain control transistor to be turned on and the first transfer transistor to be turned on, so as to control the first transfer transistor to be turned off when the charge in the first photodiode is transferred to the floating diffusion node and the second overflow capacitor, so as to obtain the first valid signal of the photoelectric conversion circuit under medium conversion gain.

[0021] In some embodiments, after obtaining the first valid signal of the photoelectric conversion circuit under medium conversion gain, the controller is also used to: control the three conversion gain control transistors and the first transfer transistor to be turned on, so as to control the first transfer transistor to be turned off when the charge in the first photodiode is transferred to the floating diffusion node, the first overflow capacitor and the second overflow capacitor, so as to obtain the first valid signal of the photoelectric conversion circuit under low conversion gain.

[0022] 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 one end of the second overflow capacitor.

[0023] In some embodiments, after obtaining the first valid signal of the photoelectric conversion circuit under low conversion gain, the controller is also used to: control the reset transistor to be turned on, so as to control the reset transistor to be turned off after the first photodiode, the floating diffusion node, the first overflow capacitor and the second overflow capacitor are reset, so as to obtain the second reset signal of the photoelectric conversion circuit under low conversion gain.

[0024] In some embodiments, after obtaining the second reset signal of the photoelectric conversion circuit at low conversion gain, the controller is further used to: control the dual conversion gain control transistor to be turned on to obtain the second reset signal of the photoelectric conversion circuit at medium conversion gain.

[0025] In some embodiments, after obtaining the second 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 the second reset signal of the photoelectric conversion circuit at a high conversion gain.

[0026] In some embodiments, after obtaining a second reset signal of the photoelectric conversion circuit at a high conversion gain, the controller is also used to: control the second transfer transistor to be turned on, so as to control the second transfer transistor to be turned off when the charge in the second photodiode is transferred to the floating diffusion node, so as to obtain a second valid signal of the photoelectric conversion circuit at a high conversion gain.

[0027] In some embodiments, after obtaining the second valid signal of the photoelectric conversion circuit under high conversion gain, the controller is also used to: control the dual conversion gain control transistor and the second transfer transistor to be turned on, so as to control the second transfer transistor to be turned off when the charge in the second photodiode is transferred to the floating diffusion node and the second overflow capacitor, so as to obtain the second valid signal of the photoelectric conversion circuit under medium conversion gain.

[0028] 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.

[0029] In some embodiments, when controlling the first photoelectric conversion sub-circuit and the first overflow circuit to be turned on, the controller is specifically used to: control the first photoelectric conversion sub-circuit and the first overflow circuit to be turned on to a preset opening.

[0030] 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, a first overflow circuit and a second overflow circuit, one end of the first overflow circuit is connected to the floating diffusion node, and the other end of the first overflow circuit is grounded, the control method of the image sensor includes: controlling the first photoelectric conversion sub-circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and the barrier height of the first photoelectric conversion sub-circuit and the first overflow circuit meets a preset condition, so that the first photoelectric conversion sub-circuit, the floating diffusion node and the first overflow circuit form an overflow path.

[0031] According to the control method of the image sensor of the embodiment of the present invention, by controlling the first photoelectric conversion sub-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 first photoelectric conversion sub-circuit and the barrier height of the first overflow circuit meet the preset conditions, the charge in the first photoelectric conversion sub-circuit can be transmitted to the floating diffusion node and the first overflow circuit to form an overflow path composed of the first photoelectric conversion circuit, the floating diffusion node and the first overflow circuit, and the excess charge in the first photoelectric conversion sub-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.

[0032] 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.

[0033] 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

[0034] 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:

[0035] Figure 1 is a circuit diagram of an image sensor of related art;

[0036] Figure 2 is a schematic diagram of a pixel structure of an image sensor of related technology;

[0037] Figure 3 It is a schematic diagram of a data reading method of an image sensor in the related art;

[0038] Figure 4 is a circuit diagram of an image sensor according to an embodiment of the present invention;

[0039] Figure 5 is a timing diagram of an image sensor according to an embodiment of the present invention;

[0040] Figure 6 is an equivalent potential diagram of an image sensor according to a specific embodiment of the present invention;

[0041] Figure 7 is an equivalent potential diagram of an image sensor according to another specific embodiment of the present invention.

[0042] Reference numerals:

[0043] Image sensor 10;

[0044] Photoelectric conversion circuit 1; signal output circuit 2;

[0045] A first photoelectric conversion sub-circuit 11; a second photoelectric conversion sub-circuit 12;

[0046] A first overflow circuit 21; a second overflow circuit 22. DETAILED DESCRIPTION

[0047] 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.

[0048] In the relevant technology, the high dynamic range required for autonomous driving scenarios is generally more than 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 the opposite 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 mode. Although it can improve the dynamic range of the image sensor to a certain extent, it cannot meet the performance of suppressing LED flicker.

[0049] like Figure 2 As shown in the figure, the image sensor adopts a 4-pixel cell structure, of which 3 pixel cells are used as LPD (Large Pixel Diode), and the other sub-pixel cell is used as SPD (Small Pixel Diode) by combining light absorption attenuation film and other methods to reduce the pixel light absorption sensitivity. In general, the optical absorption attenuation ratio of LPD and SPD is 1:10+, which is not limited here. The HDR performance is formed by combining the sensitivity ratio of LPD / SPD with the empirical time ratio, while avoiding the problem of too low SNR (SIGNAL-NOISE RATIO).

[0050] like Figure 3 As shown, the image sensor in the prior art adopts a long-short splicing exposure method in the timing design, that is, the SPD performs two exposures within the time of one exposure of the LPD, so that the SPD does not have an overflow function during the exposure. At the same time, the timing operation is complex, and the timing makes the LFM coverage range of the image sensor not fully cover the entire dynamic range, wherein the 1st LPD long exposure is mainly used to obtain darker signals, and the 2nd LPD long exposure is mainly used to obtain ultra-strong light signals; the 3rd SPD long exposure and the 4th LPD short exposure are mainly used to obtain medium light intensity signals, which mainly depends on the long-short exposure time ratio of the LPD and the LPD / SPD optical sensitivity ratio. Usually, the SPD and LPD sensitivity ratio is about 1:10+, and the LPD long-short exposure time ratio is about 1:50+.

[0051] Combine the following Figure 4-Figure 7 An image sensor 10 according to an embodiment of the present invention will be described.

[0052] like Figure 4As 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 photoelectric conversion circuit 1 includes a first photoelectric conversion sub-circuit 11; 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,

[0053] 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 floating diffusion node FD1, and the other end of the first overflow circuit 21 is grounded; the controller is used to control the first photoelectric conversion sub-circuit 11 and the first overflow circuit 21 to be turned on and the second overflow circuit 22 to be turned off and the barrier height of the first photoelectric conversion sub-circuit 11 and the first overflow circuit 21 meets the preset conditions, so that the first photoelectric conversion sub-circuit 11, the floating diffusion node FD1 and the first overflow circuit 21 form an overflow path.

[0054] In an embodiment, Figure 5-Figure 7 As shown, after the photoelectric conversion circuit 1 is exposed, the controller controls the first photoelectric conversion sub-circuit 11 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 first photoelectric conversion sub-circuit 11 and the barrier height of the first overflow circuit 21 meet the preset conditions, for example, the barrier height of the first photoelectric conversion sub-circuit 11 is greater than the barrier height of the first overflow circuit 21, and the charge in the first photoelectric conversion sub-circuit 11 can be transferred to the first overflow circuit 21 to form an integration stage, so that the first photoelectric conversion sub-circuit 11, the floating diffusion node FD1 and the first overflow circuit 21 form an overflow path, and the first photoelectric conversion sub-circuit 11 and the first overflow circuit 21 are connected through the floating diffusion node FD1, and the excess charge in the first photoelectric conversion sub-circuit 11 after full load is transferred 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.

[0055] According to the image sensor 10 of the embodiment of the present invention, by controlling the first photoelectric conversion sub-circuit 11 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 first photoelectric conversion sub-circuit 11 and the barrier height of the first overflow circuit 21 meet the preset conditions, the charge in the first photoelectric conversion sub-circuit 11 can be transmitted to the floating diffusion node FD1 and the first overflow circuit 21, forming an overflow path composed of the first photoelectric conversion sub-circuit 11, the floating diffusion node FD1 and the first overflow circuit 21, and the excess charge after the first photoelectric conversion sub-circuit 11 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.

[0056] In some embodiments, Figure 4 As shown, the first photoelectric conversion sub-circuit 11 includes: a first photodiode PD4 and a first transfer transistor TX4, wherein the anode of the first photodiode PD4 is grounded; the source of the first transfer transistor TX4 is connected to the cathode of the first photodiode PD4, and the drain of the first transfer transistor TX4 is connected to the floating diffusion node FD1, which is used to turn on or off the overflow path between the first photodiode PD4 and the first overflow circuit 21. When the controller controls the first photoelectric conversion sub-circuit 11 to be turned on, it is specifically used to: control the first photoelectric conversion sub-circuit 11 to be turned on to a preset opening.

[0057] In an embodiment, Figure 5 and Figure 6 As shown, after the photoelectric conversion circuit 1 is exposed, the first photodiode PD4 in the first photoelectric conversion sub-circuit 11 converts the received light into electric charges, and the first transfer transistor TX4 turns on or off the overflow path between the photodiode PD and the first overflow circuit 21. When the controller controls the first photoelectric conversion sub-circuit 11 to be turned on, the first transfer transistor TX4 in the first photoelectric conversion sub-circuit 11 is controlled to be turned on to a preset opening, that is, the first photoelectric conversion sub-circuit 11 is not completely turned off, so as to transfer the charge in the first photodiode PD4 to the floating diffusion node FD1.

[0058] In some embodiments, Figure 4 As shown, the first overflow circuit 21 includes: a first overflow capacitor, for example, denoted as FD3 and three conversion gain control transistors, for example, denoted as FCG, wherein one end of the first overflow capacitor FD3 is grounded; the drain of the three conversion gain control transistors FCG is connected to the floating diffusion node FD1, and the source of the three conversion gain control transistors FCG is connected to the other end of the first overflow capacitor FD3. When the controller controls the first overflow circuit 21 to be turned on, it is specifically used to: control the first overflow circuit 21 to be turned on to a preset opening.

[0059] In the embodiment, when the controller controls the first overflow circuit 21 to be turned on, the three conversion gain control transistors FCG in the first overflow circuit 21 are controlled to be turned on to a preset opening, that is, the first overflow circuit 21 is not completely turned off. Since the capacitance of the first overflow capacitor FD3 is relatively large, the detection range of the SPD for high-intensity light is further expanded, thereby improving the dynamic range of the image sensor 10.

[0060] In some embodiments, the barrier heights of the first photoelectric conversion subcircuit 11 and the first overflow circuit 21 meet preset conditions, including: the barrier height of the first transmission transistor TX4 in the first photoelectric conversion subcircuit 11 exceeds the barrier height of the three conversion gain control transistor FCG in the first overflow circuit 21.

[0061] In some embodiments, Figure 4 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 floating diffusion node FD1; 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.

[0062] In an embodiment, Figure 5-Figure 7 As shown, when the controller controls the second overflow circuit 22 to turn off, the dual conversion gain control transistor DCG in the second overflow circuit 22 is controlled to turn 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 after it is fully loaded.

[0063] In some embodiments, the photoelectric conversion circuit 1 further includes: at least one second photoelectric conversion sub-circuit 12, such as Figure 4 As shown, the photoelectric conversion circuit 1 further includes three second photoelectric conversion sub-circuits 12 .

[0064] In some embodiments, Figure 4 As shown, the second photoelectric conversion sub-circuit 12 includes: a second photodiode PD3 and a second transfer transistor TX3, wherein the anode of the second photodiode PD3 is grounded; the source of the second transfer transistor TX3 is connected to the cathode of the second photodiode PD3, and the drain of the second transfer transistor TX3 is connected to the floating diffusion node FD1.

[0065] Or the second photoelectric conversion sub-circuit 12 includes: a second photodiode PD2 and a second transfer transistor TX2, wherein the anode of the second photodiode PD2 is grounded; the source of the second transfer transistor TX2 is connected to the cathode of the second photodiode PD2, and the drain of the second transfer transistor TX2 is connected to the floating diffusion node FD1.

[0066] Or the second photoelectric conversion sub-circuit 12 includes: a second photodiode PD1 and a second transfer transistor TX1, wherein the anode of the second photodiode PD1 is grounded; the source of the second transfer transistor TX1 is connected to the cathode of the second photodiode PD1, and the drain of the second transfer transistor TX1 is connected to the floating diffusion node FD1.

[0067] The following description will be made by taking the second photoelectric conversion sub-circuit 12 including the second photodiode PD3 and the second transmission transistor TX3 as an example.

[0068] In some embodiments, when controlling the second overflow circuit 22 to be turned off, the controller is further configured to: control the second transmission transistor TX3 to be turned off.

[0069] In an embodiment, Figure 5-Figure 7 As shown, after the photodiode PD in the photoelectric conversion circuit 1 is exposed, the controller controls the second transfer transistor TX3 of the second photoelectric conversion sub-circuit 12 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 first photodiode PD4 will not overflow to the second overflow capacitor FD2 after it is fully loaded.

[0070] In some embodiments, after controlling the first photoelectric conversion sub-circuit 11 and the first overflow circuit 21 to be turned on, the controller is also used to: control the first transmission transistor TX4 and the three conversion gain control transistor FCG to be turned off, and after the first transmission transistor TX4 and the three conversion gain control transistor FCG are turned off, control the dual conversion gain control transistor DCG to be turned on, so as to obtain the first reset signal of the photoelectric conversion circuit 1 under the medium conversion gain.

[0071] In an embodiment, Figure 5-Figure 7 As shown, after controlling the first photoelectric conversion sub-circuit 11 and the first overflow circuit 21 to be turned on, for example, from time T0 to time T1, it is considered that the integration stage is over, and the controller controls the first transfer transistor TX4 and the three conversion gain control transistors FCG to be turned off. Since the capacitance of the first overflow capacitor FD3 is much larger than the sum of the floating diffusion node FD1 and the second overflow capacitor FD2, at the moment when the three conversion gain control transistors FCG are turned off, most of the overflow charges are transferred to the first overflow capacitor FD3, and there are only a small amount of charges in the floating diffusion node FD1 and the second overflow capacitor FD2.

[0072] After the first transmission transistor TX4 and the three conversion gain control transistor FCG are turned off, the dual conversion gain control transistor DCG in the second overflow circuit 22 is controlled to be turned on to obtain a first reset signal of the photoelectric conversion circuit 1 at a medium conversion gain, for example, MCG_SHR.

[0073] In some embodiments, after obtaining the first 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 first reset signal of the photoelectric conversion circuit 1 at a high conversion gain.

[0074] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the first reset signal 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 T2 to obtain the first reset signal of the photoelectric conversion circuit 1 under the high conversion gain, for example, recorded as HCG_SHR.

[0075] In some embodiments, after obtaining the first reset signal of the photoelectric conversion circuit 1 under high conversion gain, the controller is also used to: control the first transfer transistor TX4 to be turned on, so as to control the first transfer transistor TX4 to be turned off when the charge in the first photodiode PD4 is transferred to the floating diffusion node FD1, so as to obtain the first valid signal of the photoelectric conversion circuit 1 under high conversion gain.

[0076] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the first reset signal of the photoelectric conversion circuit 1 under high conversion gain, the controller controls the first transfer transistor TX4 to be turned on at time T3, and the charge in the first photodiode PD4 begins to be transmitted to the floating diffusion node FD1, so that when the charge in the first photodiode PD4 is transmitted to the floating diffusion node FD1, the first transfer transistor TX4 is controlled to be turned off to obtain the first valid signal of the photoelectric conversion circuit 1 under high conversion gain, for example, recorded as HCG_SHS.

[0077] In some embodiments, after obtaining the first valid signal of the photoelectric conversion circuit 1 under high conversion gain, the controller is also used to: control the dual conversion gain control transistor DCG to be turned on and the first transfer transistor TX4 to be turned on, so as to control the first transfer transistor TX4 to be turned off when the charge in the first photodiode PD4 is transferred to the floating diffusion node FD1 and the second overflow capacitor FD2, so as to obtain the first valid signal of the photoelectric conversion circuit 1 under medium conversion gain.

[0078] In an embodiment, Figure 5-Figure 7As shown, after obtaining the first valid signal of the photoelectric conversion circuit 1 under high conversion gain, the controller controls the dual conversion gain control transistor DCG to be turned on and the first transfer transistor TX4 to be turned on at time T4, and the residual charge in the first photodiode PD4 begins to be transmitted to the floating diffusion node FD1 and the second overflow capacitor FD2, so that when the charge in the first photodiode PD4 is transferred to the floating diffusion node FD1 and the second overflow capacitor FD2, the first transfer transistor TX4 is controlled to be turned off, so as to obtain the first valid signal of the photoelectric conversion circuit 1 under medium conversion gain, for example, recorded as MCG_SHS.

[0079] In some embodiments, after obtaining the first valid signal of the photoelectric conversion circuit 1 under medium conversion gain, the controller is also used to: control the three conversion gain control transistors FCG to be turned on and the first transfer transistor TX4 to be turned on, so as to control the first transfer transistor TX4 to be turned off when the charge in the first photodiode PD4 is transferred to the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, so as to obtain the first valid signal of the photoelectric conversion circuit 1 under low conversion gain.

[0080] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the first valid signal of the photoelectric conversion circuit 1 under the medium conversion gain, the controller controls the three conversion gain control transistors FCG to be turned on and the first transfer transistor TX4 to be turned on at time T5, and the residual charge in the first photodiode PD4 begins to be transmitted to the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, so that when the charge in the first photodiode PD4 is transmitted to the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2, the first transfer transistor TX4 is controlled to be turned off, so as to obtain the first valid signal of the photoelectric conversion circuit 1 under the low conversion gain, for example, recorded as LCG_SHS.

[0081] In some embodiments, Figure 4 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 one end of the second overflow capacitor FD2, and the connection between the second overflow capacitor FD2 and the power supply voltage VDDP is turned on or off by the reset transistor RST.

[0082] In an embodiment, before exposing the photoelectric conversion circuit 1, the controller controls the reset tube RST in the signal output circuit 2 to turn on, clearing the charges in the photoelectric conversion circuit 1 and the signal output circuit 2 to reset the floating diffusion node FD1, the first overflow circuit 21 and the second overflow circuit 22.

[0083] In some embodiments, after obtaining the first valid signal of the photoelectric conversion circuit 1 under low conversion gain, the controller is also used to: control the reset transistor RST to be turned on, so as to control the reset transistor RST to be turned off after the first photodiode PD4, the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2 are reset, so as to obtain the second reset signal of the photoelectric conversion circuit 1 under low conversion gain.

[0084] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the first valid signal of the photoelectric conversion circuit 1 under low conversion gain, the controller controls the reset transistor RST to turn on at time T6, and resets the first photodiode PD4, the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2. After the first photodiode PD4, the floating diffusion node FD1, the first overflow capacitor FD3 and the second overflow capacitor FD2 are reset, the reset transistor RST is controlled to be turned off to obtain the second reset signal of the photoelectric conversion circuit 1 under low conversion gain, for example, recorded as LCG_SHR.

[0085] In some embodiments, after obtaining the second reset signal of the photoelectric conversion circuit 1 at low conversion gain, the controller is further used to: control the dual conversion gain control transistor DCG to be turned on to obtain the second reset signal of the photoelectric conversion circuit 1 at medium conversion gain.

[0086] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the second reset signal of the photoelectric conversion circuit 1 at low conversion gain, the controller controls the dual conversion gain control transistor DCG to turn on at time T7 to obtain the second reset signal of the photoelectric conversion circuit 1 at medium conversion gain, for example, recorded as MCG_SHR.

[0087] In some embodiments, after obtaining the second 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 second reset signal of the photoelectric conversion circuit 1 at a high conversion gain.

[0088] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the second reset signal 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 T8 to obtain the second reset signal of the photoelectric conversion circuit 1 under the high conversion gain, for example, recorded as HCG_SHR.

[0089] In some embodiments, after obtaining the second reset signal of the photoelectric conversion circuit 1 under high conversion gain, the controller is also used to: control the second transfer transistor TX3 to be turned on, so that when the charge in the second photodiode PD3 is transferred to the floating diffusion node FD1, the second transfer transistor TX3 is controlled to be turned off, so as to obtain the second valid signal of the photoelectric conversion circuit 1 under high conversion gain.

[0090] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the second reset signal of the photoelectric conversion circuit 1 under high conversion gain, the controller controls the second transfer transistor TX3 to be turned on at time T9, and the charge in the second photodiode PD3 begins to be transmitted to the floating diffusion node FD1, so that when the charge in the second photodiode PD3 is transmitted to the floating diffusion node FD1, the second transfer transistor TX3 is controlled to be turned off to obtain the second valid signal of the photoelectric conversion circuit 1 under high conversion gain, for example, recorded as HCG_SHS.

[0091] In some embodiments, after obtaining the second valid signal of the photoelectric conversion circuit 1 under high conversion gain, the controller is also used to: control the dual conversion gain control transistor DCG and the second transfer transistor TX3 to be turned on, so that when the charge in the second photodiode PD3 is transferred to the floating diffusion node FD1 and the second overflow capacitor FD2, the second transfer transistor TX3 is controlled to be turned off, so as to obtain the second valid signal of the photoelectric conversion circuit 1 under medium conversion gain.

[0092] In an embodiment, Figure 5-Figure 7 As shown, after obtaining the second valid signal of the photoelectric conversion circuit 1 under high conversion gain, the controller controls the dual conversion gain control transistor DCG to be turned on and the second transfer transistor TX3 to be turned on at time T10, and the charge in the second photodiode PD3 begins to be transmitted to the floating diffusion node FD1 and the second overflow capacitor FD2, so that when the charge in the second photodiode PD3 is transmitted to the floating diffusion node FD1 and the second overflow capacitor FD2, the second transfer transistor TX3 is controlled to be turned off, so as to obtain the second valid signal of the photoelectric conversion circuit 1 under medium conversion gain, for example, recorded as MCG_SHS.

[0093] In some embodiments, Figure 4 As 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).

[0094] The image sensor 10 of the embodiment of the present invention only needs one exposure time to meet the requirements of high dynamic range and linear frequency modulation. At the same time, the timing operation is simple, and the timing makes the LFM coverage range of the image sensor meet the full coverage of the entire dynamic range, so that the entire dynamic range can satisfy the suppression of LED flicker.

[0095] According to the image sensor 10 of the embodiment of the present invention, by controlling the first photoelectric conversion sub-circuit 11 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 first photoelectric conversion sub-circuit 11 and the barrier height of the first overflow circuit 21 meet the preset conditions, the charge in the first photoelectric conversion sub-circuit 11 can be transmitted to the floating diffusion node FD1 and the first overflow circuit 21, forming an overflow path composed of the first photoelectric conversion sub-circuit 11, the floating diffusion node FD1 and the first overflow circuit 21, and the excess charge after the first photoelectric conversion sub-circuit 11 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.

[0096] The following is an example of the control method of the image sensor according to the embodiment of the present invention.

[0097] The control method of the image sensor of the embodiment of the present invention is used for the image sensor of the above 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, a signal output circuit and a second overflow circuit. One end of the signal output circuit is connected to the floating diffusion node, and the other end of the signal output circuit is grounded.

[0098] The control method of the image sensor of the embodiment of the present invention includes: controlling the first photoelectric conversion sub-circuit and the signal output circuit to be turned on and the second overflow circuit to be turned off, and the barrier height of the first photoelectric conversion sub-circuit and the first overflow circuit meets a preset condition, so that the first photoelectric conversion sub-circuit, the floating diffusion node and the signal output circuit form an overflow path.

[0099] According to the control method of the image sensor of the embodiment of the present invention, by controlling the first photoelectric conversion sub-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 first photoelectric conversion sub-circuit and the barrier height of the first overflow circuit meet the preset conditions, the charge in the first photoelectric conversion sub-circuit can be transmitted to the floating diffusion node and the first overflow circuit to form an overflow path composed of the first photoelectric conversion circuit, the floating diffusion node and the first overflow circuit, and the excess charge in the first photoelectric conversion sub-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.

[0100] The following describes a non-transitory computer-readable storage medium according to an embodiment of the present invention.

[0101] The non-transitory computer-readable storage medium of the embodiment of the present invention stores a control program of the image sensor. When the control program of the image sensor is executed by a processor, the control method of the image sensor of the above embodiment is implemented.

[0102] 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.

[0103] 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: A photoelectric conversion circuit, the photoelectric conversion circuit comprising a first photoelectric conversion sub-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 floating diffusion node, and the other end of the first overflow circuit is grounded; A controller is used to control the first photoelectric conversion sub-circuit and the first overflow circuit to be turned on and the second overflow circuit to be turned off, and the barrier heights of the first photoelectric conversion sub-circuit and the first overflow circuit meet preset conditions, so that the first photoelectric conversion sub-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 first photoelectric conversion subcircuit comprises: a first photodiode, wherein an anode of the first photodiode is grounded; A first transfer transistor, wherein the source of the first transfer transistor is connected to the cathode of the first photodiode, the drain of the first transfer transistor is connected to the floating diffusion node, and is used to turn on or off an overflow path between the first photodiode and the first overflow circuit.

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

4. The image sensor according to claim 3, characterized in that: The barrier heights of the first photoelectric conversion sub-circuit and the first overflow circuit meet preset conditions, including: the barrier height of the first transfer transistor exceeds the barrier height of the three conversion gain control transistors.

5. The image sensor according to claim 1, characterized in that The second overflow circuit comprises: a dual conversion gain control transistor, the source of the dual conversion gain control transistor being connected to the floating diffusion node; 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 The photoelectric conversion circuit further includes: at least one second photoelectric conversion sub-circuit.

7. The image sensor according to claim 6, characterized in that: The second photoelectric conversion subcircuit comprises: a second photodiode, wherein an anode of the second photodiode is grounded; A second transfer transistor, a source of the second transfer transistor is connected to the cathode of the second photodiode, and a drain of the second transfer transistor is connected to the floating diffusion node.

8. The image sensor according to claim 7, characterized in that: When controlling the second overflow circuit to be turned off, the controller is further used to: control the second transmission transistor to be turned off.

9. The image sensor according to claim 3 or 8, characterized in that: After controlling the first photoelectric conversion sub-circuit and the first overflow circuit to be turned on, the controller is further used to: The first transmission transistor and the three conversion gain control transistors are controlled to be turned off, and after the first transmission transistor and the three conversion gain control transistors are turned off, the dual conversion gain control transistor is controlled to be turned on to obtain a first reset signal of the photoelectric conversion circuit under a medium conversion gain.

10. The image sensor according to claim 9, characterized in that: After obtaining the first reset signal of the photoelectric conversion circuit under the medium conversion gain, the controller is further used to: control the dual conversion gain control transistor to turn off to obtain the first reset signal of the photoelectric conversion circuit under the high conversion gain.

11. The image sensor according to claim 10, characterized in that: After obtaining the first reset signal of the photoelectric conversion circuit under the high conversion gain, the controller is further used for: The first transfer transistor is controlled to be turned on, so that when the charge in the first photodiode is transferred to the floating diffusion node, the first transfer transistor is controlled to be turned off, so as to obtain a first effective signal of the photoelectric conversion circuit under a high conversion gain.

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

13. The image sensor according to claim 12, characterized in that: After acquiring the first valid signal of the photoelectric conversion circuit at the medium conversion gain, the controller is further used for: The three conversion gain control transistors and the first transfer transistor are controlled to be turned on, so that when the charge in the first photodiode is transferred to the floating diffusion node, the first overflow capacitor and the second overflow capacitor, the first transfer transistor is controlled to be turned off to obtain a first effective signal of the photoelectric conversion circuit under low conversion gain.

14. The image sensor according to claim 7 or 13, 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 one end of the second overflow capacitor.

15. The image sensor according to claim 14, characterized in that: After acquiring the first valid signal of the photoelectric conversion circuit at the low conversion gain, the controller is further used for: The reset transistor is controlled to be turned on, so as to obtain a second reset signal of the photoelectric conversion circuit at a low conversion gain after the first photodiode, the floating diffusion node, the first overflow capacitor and the second overflow capacitor are reset.

16. The image sensor according to claim 15, characterized in that After obtaining the second reset signal of the photoelectric conversion circuit at the low conversion gain, the controller is further used for: The dual conversion gain control transistor is controlled to be turned on to obtain a second reset signal of the photoelectric conversion circuit under a medium conversion gain.

17. The image sensor according to claim 16, characterized in that: After obtaining the second reset signal of the photoelectric conversion circuit at the medium conversion gain, the controller is further used for: The dual conversion gain control transistor is controlled to be turned off to obtain a second reset signal of the photoelectric conversion circuit under high conversion gain.

18. The image sensor according to claim 17, characterized in that: After obtaining the second reset signal of the photoelectric conversion circuit under the high conversion gain, the controller is further used for: The second transfer transistor is controlled to be turned on, so that when the charge in the second photodiode is transferred to the floating diffusion node, the second transfer transistor is controlled to be turned off, so as to obtain a second effective signal of the photoelectric conversion circuit under high conversion gain.

19. The image sensor according to claim 18, characterized in that After acquiring the second valid signal of the photoelectric conversion circuit under the high conversion gain, the controller is further used for: The dual conversion gain control transistor and the second transfer transistor are controlled to be turned on, so that when the charge in the second photodiode is transferred to the floating diffusion node and the second overflow capacitor, the second transfer transistor is controlled to be turned off to obtain a second effective signal of the photoelectric conversion circuit under medium conversion gain.

20. The image sensor according to claim 1, 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.

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

22. A method for controlling an image sensor, characterized in that: For the image sensor according to any one of claims 1 to 21, the image sensor comprises a photoelectric conversion circuit, a signal output circuit and a controller, the signal output circuit comprises a floating diffusion node, a first overflow circuit and a second overflow circuit, one end of the first overflow circuit is connected to the floating diffusion node, and the other end of the first overflow circuit is grounded, the control method comprises: The first photoelectric conversion subcircuit and the first overflow circuit are controlled to be turned on and the second overflow circuit is turned off, and the barrier heights of the first photoelectric conversion subcircuit and the first overflow circuit meet preset conditions, so that the first photoelectric conversion subcircuit, the floating diffusion node and the first overflow circuit form an overflow path.

23. A non-transitory computer-readable storage medium, characterized in that: The computer-readable storage medium stores a control program for the image sensor, and when the control program for the image sensor is executed by the processor, the control method for the image sensor according to claim 22 is implemented.

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