Pixel array, image sensor, and self-checking method of image sensor

Abstract

The present application relates to a pixel array, an image sensor and a self-checking method of the image sensor, comprising a photosensitive pixel region, a first reference pixel region and / or a second reference pixel region; the photosensitive pixel region comprises M rows of N columns of pixels arranged in an array; the first reference pixel region comprises n columns of first reference pixels arranged correspondingly to the N columns of pixels of the photosensitive pixel region; and the second reference pixel region comprises m rows of second reference pixels arranged correspondingly to the M rows of pixels of the photosensitive pixel region.The present application sets the first reference pixel region corresponding to the columns of the photosensitive pixel array and / or the second reference pixel region corresponding to the rows of the photosensitive pixel array, and obtains the output signals of the reference pixels in the first reference pixel region and / or the second reference pixel region when obtaining each frame of image data of the photosensitive pixel array, so that the real-time self-checking function of the readout circuit and / or the control circuit in the image sensor can be realized, the safety performance of the image sensor is improved, and the product competitiveness is improved.

Description

Technical Field

[0001] This invention relates to the field of image sensor technology, and in particular to a pixel array, an image sensor, and a self-testing method for the image sensor. Background Technology

[0002] Image sensors are widely used in various electronic devices to capture and identify image information of people or scenes, such as video surveillance systems, smartphones, digital cameras, drones, AI, and facial recognition. An image sensor is a semiconductor-based sensor that generates an electrical signal in response to light. As a crucial component of digital cameras, it converts incident light signals into electrical charge signals, then into voltage or current signals, and finally outputs the converted electrical signal.

[0003] As the automotive industry becomes increasingly intelligent, more and more image sensors are being used in vehicles. To ensure the safety of the entire vehicle system, especially for vehicles equipped with driver assistance technologies, image sensors, as core electronic components, need to meet higher safety performance requirements.

[0004] Existing image sensors lack self-testing capabilities, failing to meet the requirements for functional failure and diagnostic coverage. When applied to automotive systems, the lack of self-testing functionality in image sensors could potentially lead to serious safety incidents. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a pixel array, an image sensor, and a self-testing method for the image sensor, which can realize the real-time self-testing function of the readout circuit and / or control circuit in the image sensor, verify the correctness of the image signal output by the image sensor in real time, improve the safety performance of the image sensor, and enhance product competitiveness.

[0006] To achieve the above objectives, embodiments of the present invention provide a pixel array, which, as one implementation, comprises:

[0007] The photosensitive pixel area includes M rows and N columns of pixels arranged in an array. The pixels are used to output pixel data through a readout circuit under the control of the control circuit to obtain an image signal.

[0008] The first reference pixel region includes n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region; each first reference pixel is used to receive a corresponding first input signal and output a corresponding first output signal through the readout circuit, so as to determine whether the state of the readout circuit is normal based on the first input signal and the first output signal, wherein n is less than or equal to N, and n and N are natural numbers greater than 0; and / or,

[0009] The second reference pixel region includes m rows of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region; each second reference pixel is used to receive a corresponding second input signal and, under the control of the control circuit, outputs a corresponding second output signal through the readout circuit, so as to determine whether the state of the control circuit is normal based on the second input signal and the second output signal, wherein m is less than or equal to M, and m and M are natural numbers greater than 0.

[0010] In one embodiment, the first reference pixel region includes at least two rows and n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region; and / or, the second reference pixel region includes at least two rows and m columns of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region.

[0011] In one embodiment, the first reference pixel region further includes at least one first clamping voltage line for providing the first input signal to each of the first reference pixels; wherein the number of the first clamping voltage lines is less than or equal to the number of the first reference pixels; and / or, the second reference pixel region further includes at least one second clamping voltage line for providing the second input signal to each of the second reference pixels; wherein the number of the second clamping voltage lines is less than or equal to the number of the second reference pixels.

[0012] In one implementation, first reference pixels in the same row that share the same readout sub-circuit are connected to different first clamping voltage lines; and / or

[0013] Second reference pixels in the same column that share the same control sub-circuit are connected to different second clamping voltage lines.

[0014] In one implementation, the first reference pixel is physically connected to the selected first clamping voltage line; or, the first reference pixel is electrically connected to the corresponding first clamping voltage line via a first switching element; and / or,

[0015] The second reference pixel is physically connected to the selected second clamping voltage line; or, the second reference pixel is electrically connected to the corresponding second clamping voltage line through a second switching element.

[0016] In one implementation, the first reference pixel has the same structure as the second reference pixel.

[0017] In one embodiment, the first reference pixel includes: a first pixel selection transistor and a first source follower transistor; and / or, the second reference pixel includes: a second pixel selection transistor and a second source follower transistor;

[0018] Wherein, the gate of the first source follower transistor receives the corresponding first input signal, the drain of the first source follower transistor is coupled to the first power supply voltage, and the source of the first source follower transistor is coupled to the drain of the first pixel selection transistor; the gate of the first pixel selection transistor receives the pixel selection signal, and the source of the first pixel selection transistor is coupled to the corresponding column line, so as to output the corresponding first output signal through the readout circuit.

[0019] The gate of the second source follower transistor receives the corresponding second input signal, the drain of the second source follower transistor is coupled to the second power supply voltage, and the source of the second source follower transistor is coupled to the drain of the second pixel selection transistor; the gate of the second pixel selection transistor receives the pixel selection signal, and the source of the second pixel selection transistor is coupled to the corresponding column line, so as to output the corresponding second output signal through the readout circuit.

[0020] In one implementation, the number of the first source follower transistors is at least two, and each of the first source follower transistors is connected in parallel.

[0021] And / or, the number of the second source follower transistors is at least two, and each of the second source follower transistors is connected in parallel.

[0022] Based on the same inventive concept, the present invention provides an image sensor, which, as one embodiment, includes: the pixel array described in any of the above embodiments.

[0023] In one embodiment, the image sensor includes the readout circuit and the control circuit; wherein,

[0024] The control circuit includes a pixel driving circuit, which outputs a pixel selection signal to select any pixel in the pixel array for output; the readout circuit reads the data of the pixel selected by the pixel selection signal.

[0025] Based on the same inventive concept, the present invention also provides a self-testing method for an image sensor, applied to the image sensor described in any of the above embodiments. As one embodiment, the method includes:

[0026] When the first output signal and the first input signal do not conform to a preset correspondence, the readout circuit is determined to be in an abnormal state.

[0027] And / or, when the second output signal and the second input signal do not conform to a preset correspondence, the control circuit is determined to be in an abnormal state.

[0028] As one implementation, the method further includes:

[0029] When the first output signal and the first input signal do not have a preset correspondence, the pixel address corresponding to the first output signal is output;

[0030] And / or, when the second output signal and the second input signal do not conform to a preset correspondence, the pixel row address corresponding to the second output signal is output.

[0031] As one implementation, the method further includes:

[0032] If the first output signal and the first input signal do not conform to a preset correspondence, it is further determined whether the first output signal exceeds a preset range. If it is within the preset range, it is determined that there is a connection error between the readout sub-circuits.

[0033] In one implementation, the preset range is greater than or equal to a first preset value and less than or equal to a second preset value; wherein,

[0034] The first preset value is greater than or equal to A and less than or equal to B, where A is the difference between the value of the first output signal in the preset correspondence and 1 / 4 of the value of the first output signal in the preset correspondence, and B is the difference between the value of the first output signal in the preset correspondence and 1 / 8 of the value of the first output signal in the preset correspondence.

[0035] The second preset value is greater than or equal to C and less than or equal to D, where C is the sum of the value of the first output signal in the preset correspondence and 1 / 8 of the value of the first output signal in the preset correspondence, and D is the sum of the value of the first output signal in the preset correspondence and 1 / 4 of the value of the first output signal in the preset correspondence.

[0036] In summary, the pixel array provided in this embodiment of the invention includes: a photosensitive pixel region, a first reference pixel region, and / or a second reference pixel region; the photosensitive pixel region includes M rows and N columns of pixels arranged in an array, used to output pixel data through a readout circuit to obtain an image signal under the control of a control circuit; the first reference pixel region includes n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region, each first reference pixel being used to receive a corresponding first input signal and output a corresponding first output signal through the readout circuit, so as to determine whether the readout circuit is in normal condition based on the first input signal and the first output signal; the second reference pixel region includes m rows of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region, each second reference pixel being used to receive a corresponding second input signal and output a corresponding second output signal through the readout circuit under the control of the control circuit, so as to determine whether the control circuit is in normal condition based on the second input signal and the second output signal. This invention, based on the pixel array of existing image sensors, sets a first reference pixel region corresponding to the columns of the photosensitive pixel array and / or a second reference pixel region corresponding to the rows of the photosensitive pixel array. When acquiring each frame of image data from the photosensitive pixel array, the output signals of the reference pixels within the first and / or second reference pixel regions are acquired to perform fault detection in the readout circuit and / or control circuit, thereby determining the accuracy of the acquired image data. Therefore, this invention can realize real-time self-testing of the readout circuit and / or control circuit in the image sensor, verifying the correctness of the image signal output by the image sensor in real time, improving the safety performance of the image sensor, and enhancing product competitiveness.

[0037] The image sensor and image sensor self-testing method provided by this invention belong to the same inventive concept as the pixel array provided by this invention, and therefore have the same beneficial effects. Attached Figure Description

[0038] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0039] Figure 1 This is a schematic diagram of the structure of an existing image sensor.

[0040] Figure 2 This is a schematic diagram of the structure and connection relationship of a pixel array provided in an embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the structure of a first reference pixel provided in an embodiment of the present invention.

[0042] Figure 4 A schematic diagram of the structure of a first reference pixel provided for another embodiment of the present invention.

[0043] Figure 5 This is a schematic diagram of the structure and connection relationship of a pixel array provided in another embodiment of the present invention.

[0044] Figure 6 This is a schematic diagram of the structure and connection relationship of a pixel array provided in another embodiment of the present invention.

[0045] Figure 7 This is a schematic diagram of the self-test process of an image sensor provided in an embodiment of the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the protection scope of the present invention.

[0047] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects, but are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0048] In this document, the term "connected" or "connected" to another element, port, component, or part can be understood as a direct electrical connection or an indirect electrical connection with the presence of an intermediate element. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0049] First, an image sensor includes multiple functional circuits, each of which can affect the accuracy of the image signal output by the image sensor. For example, an error in the readout circuit will cause the image sensor to output an incorrect image signal, and an error in a related circuit in the control circuit, such as the circuit related to the output pixel selection signal, will also cause the image sensor to output an incorrect image signal. Therefore, this application provides corresponding embodiments from different perspectives to realize the self-testing function of different functional circuits of the image sensor, and can further detect which specific sub-circuit in the functional circuit has an error, such as an error in the readout sub-circuit corresponding to a column of pixels, or an error in the control sub-circuit corresponding to a row of pixels, etc.

[0050] Therefore, before describing specific embodiments of the present invention, a general description of the relevant functional circuits in existing image sensors will be provided first. Please refer to... Figure 1 , Figure 1 This is a schematic diagram of the structure of an existing image sensor. Figure 1 As shown, the image sensor 10 may include a pixel array 11, and a control circuit 12 and a readout circuit 13 coupled to the pixel array 11. The control circuit 12 is configured to drive the pixel array 11 and generate an image signal. The control circuit 12 includes multiple control sub-circuits, each for driving at least one row of pixels. The readout circuit 13 is configured to read out the image signal generated by the pixel array 11, convert it into a digital signal, and output it, for example, a binary digital signal. Similarly, the readout circuit 13 includes multiple readout sub-circuits, each for reading out at least one column of pixels.

[0051] Specifically, pixel array 11 may include multiple pixels arranged in an array along multiple row lines and multiple column lines. Pixels may include photoelectric conversion elements configured to generate charge in response to incident light, such as photodiodes, phototransistors, pinned photodiodes, etc. Control circuitry 12 may include a row decoder and a row driver with the required timing circuitry. Readout circuitry 13 may include a column decoder and a column driver with the required timing circuitry. Control circuitry 12 and readout circuitry 13 are also coupled to status register 14. After each pixel acquires its image signal or image charge, the image signal is read out by readout circuitry 13 according to the readout mode set in status register 14 and then transmitted to functional logic unit 15. Functional logic unit 15 may store image data or process image data according to subsequent image effects (e.g., cropping, rotating, red-eye removal, brightness adjustment, contrast adjustment, or other methods), and may also perform other data processing as needed.

[0052] The readout circuit 13 may include amplifier circuits, analog-to-digital converter circuits, etc. The status register 14 may include a digitally programmable selection system to determine the readout mode. The readout circuit 13 may read the image signal row by row along the readout column lines, or may use other techniques (not shown) to read the image signal, such as serial readout or fully parallel readout of all pixels. Each row in the pixel array may correspond to a row driving unit (which may be part of a control sub-circuit), which is configured to output multiple signals to the identified pixel or pixel row. For example, if the image sensor 10 includes one thousand rows of pixels, one thousand row driving units may be configured, and the multiple control signals include pixel selection signals, row reset signals, and transmission signals. Upon receiving these signals, the pixel array 11 may perform various functions on the identified pixels, transferring the charge of one or more pixels in the identified pixel row.

[0053] As described above, failure of any functional circuit will cause the image sensor to output an incorrect image. This invention improves existing image sensors to achieve self-testing functions for the readout and control circuits. Specific embodiments of this invention are described in detail below.

[0054] Example 1

[0055] Please refer to the reference. Figure 1 and Figure 2 , Figure 2 This is a schematic diagram illustrating the structure and connection relationships of a pixel array according to an embodiment of the present invention. Figure 2 As shown, the pixel array 11a includes a photosensitive pixel region 110 and a first reference pixel region 111. The photosensitive pixel region 110 includes M rows and N columns of pixels arranged in an array (i.e., Figure 1 The pixel array 11 is used to output pixel data through the readout circuit 13 under the control of the control circuit 12 to obtain the image signal.

[0056] The first reference pixel region 111 includes n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region 110. Each first reference pixel is used to receive a corresponding first input signal and output a corresponding first output signal through the readout circuit 13, so as to determine whether the state of the readout circuit 13 is normal based on the first input signal and the first output signal. Here, n is less than or equal to N, and n and N are natural numbers greater than 0.

[0057] Specifically, the first reference pixel region 111 includes n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region 110. Each column of first reference pixels in the first reference pixel region outputs signals through the same readout sub-circuit as the corresponding column of pixels in the photosensitive pixel region. This readout sub-circuit may include the column-level ADC (Analog to Digital Converter) in the readout circuit 13 corresponding to each column of pixels, i.e., the components in the readout circuit 13 corresponding to each column of pixels. It is worth noting that the output signal from each column of first reference pixels in the first reference pixel region to the corresponding column of pixels in the photosensitive pixel region through the same readout sub-circuit does not only include one readout sub-circuit per column of pixels, but also multiple columns of pixels corresponding to the same readout sub-circuit.

[0058] The number of pixel columns n in the first reference pixel region 111 can be less than or equal to the number of pixel columns N in the photosensitive pixel region 110. Preferably, n equals N, which means that the function of the readout sub-circuit corresponding to each column of photosensitive pixels can be tested using different signals.

[0059] For example, by encoding the signal of each column of first reference pixels, a unique row code can be predetermined. That is, the input signal of each first reference pixel in a row is encoded. For example, n columns of first reference pixels in a row form an n-bit ary a number (the readout circuit 13 converts the analog signal into a digital signal), and the corresponding n-bit ary a number is pre-stored in the image sensor. For the first reference pixel, when the image sensor reads out the signal, the first output signal of the first reference pixel is also read out and compared with the pre-stored ary a number (for example, it can represent the preset output signal corresponding to the first reference pixel under the selected first clamping voltage) to determine whether the readout circuit 13 is in normal condition. Once it is determined that it does not correspond to the pre-stored ary a number (that is, the first input signal and the first output signal of the first reference pixel do not correspond), the address of the pixel that has erred (column address) can be output, and the erroneous readout sub-circuit can be identified.

[0060] It is worth mentioning that each first reference pixel in the first reference pixel region 111 also requires corresponding control sub-circuit control and is read out by the readout circuit 13. Therefore, each first reference pixel is configured with a corresponding pixel address. Furthermore, the hardware also includes corresponding row lines and corresponding control sub-circuit control. The control sub-circuit control for the first reference pixel region 111 can be integrated into the existing control circuit 12 or set up separately.

[0061] It should be noted that the judgment module can determine whether the state of the readout circuit 13 is normal based on the first input signal and the first output signal. The judgment module can be integrated into the functional logic unit 15.

[0062] In one embodiment, the first reference pixel region 111 includes two rows and n columns of first reference pixels that correspond to the N columns of pixels in the photosensitive pixel region 110.

[0063] Specifically, for cost and self-test accuracy considerations, the first reference pixel area 111 in this embodiment includes two rows and n columns of first reference pixels to avoid errors in a single row of first reference pixels causing misjudgments in the self-test of the corresponding readout circuit 13. That is, when the first output signal of the two rows of first reference pixels corresponding to each column of pixels in the photosensitive pixel area 110 does not correspond to the corresponding first input signal, the corresponding readout sub-circuit is determined to be faulty.

[0064] In one embodiment, the first pixel region 111 further includes at least one first clamping voltage line for providing a first input signal for each first reference pixel; wherein the number of first clamping voltage lines is less than or equal to the number of first reference pixels.

[0065] Specifically, clamping voltage lines are used to connect to the first reference pixel and provide it with a first input signal. Depending on the encoding method, for example, setting different codes for each first reference pixel in the same row, i.e., setting different first input signals, the number of first clamping voltage lines required is equal to the number of first reference pixels in a column.

[0066] In one embodiment, first reference pixels in the same row that share the same readout sub-circuit are connected to different first clamping voltage lines.

[0067] Specifically, by connecting the first reference pixels in the same row that share the same readout sub-circuit to different first clamping voltage lines, different clamping voltages can be used to detect the same readout sub-circuit.

[0068] In one embodiment, the first reference pixel is physically connected to the selected first clamping voltage line; or, the first reference pixel is electrically connected to the corresponding first clamping voltage line through a first switching element.

[0069] Specifically, when the voltage on the first clamping voltage line is variable, the first reference pixel is physically connected to the selected first clamping voltage line, enabling the switching of multiple first input signals. When the voltage on the first clamping voltage line is fixed, the first reference pixel can be electrically connected to the corresponding first clamping voltage line via a first switching element to switch between different first input signals. Furthermore, the first switching element allows for more flexible matching between the reference pixel and the clamping voltage line.

[0070] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a first reference pixel provided in an embodiment of the present invention. Figure 3 As shown, the first reference pixel includes: a first source follower transistor SF and a first pixel selection transistor RS. Wherein,

[0071] The gate of the first source follower transistor SF is used to receive the first input signal, the drain of the first source follower transistor SF is coupled to the first power supply voltage VDD, and the source of the first source follower transistor SF is coupled to the drain of the first pixel selection transistor RS.

[0072] The gate of the first pixel selection transistor RS receives the pixel selection signal output by the control circuit 12, and the source of the first pixel selection transistor RS is coupled to the corresponding column line for outputting the first output signal through the readout circuit 13.

[0073] Please refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of a first reference pixel provided in another embodiment of the present invention. Figure 4 As shown, the first reference pixel includes: at least two first source follower transistors (SF1 and SF2) and a first pixel selection transistor RS, wherein the at least two first source follower transistors are connected in parallel.

[0074] Specifically, the gate of the first source follower transistor (SF1 and SF2) receives the corresponding first input signal, the drain of the first source follower transistor (SF1 and SF2) is coupled to the first power supply voltage VDD, and the source of the first source follower transistor (SF1 and SF2) is coupled to the drain of the first pixel selection transistor RS; the gate of the first pixel selection transistor RS receives the pixel selection signal output by the control circuit 12, and the source of the first pixel selection transistor RS is coupled to the corresponding column line so as to output the corresponding first output signal through the readout circuit 13.

[0075] In this embodiment, the first reference pixel can switch between different first input signals through hardware. For example, if the gate of the first source transistor SF1 receives a corresponding first input signal of 3V and the gate of the second source transistor SF2 receives a corresponding first input signal of 4V, then different input signals can be set for the first reference pixel.

[0076] In one embodiment, the first reference pixel includes at least two first source follower transistors and at least two pixel select transistors, wherein the number of first source follower transistors is the same as the number of pixel select transistors, and each source follower transistor is configured to correspond one-to-one with each pixel select transistor.

[0077] For details, please refer to Figure 4 This implementation method is in Figure 4 Add another pixel selection transistor RS2 (not shown) to make each first reference pixel have multiple independent output paths, namely SF1-RS1-column line, SF2-RS2 (not shown)-column line.

[0078] In summary, the pixel array provided in this embodiment can be used to realize the real-time self-test function of the readout circuit in the image sensor, to check whether the image signal output by the image sensor is correct in real time, thereby improving the security performance of the image sensor and enhancing product competitiveness.

[0079] Example 2

[0080] Please refer to the reference. Figure 1 and Figure 5 , Figure 5 This is a schematic diagram illustrating the structure and connection relationships of a pixel array according to another embodiment of the present invention. Figure 5 As shown, the pixel array 11b includes a photosensitive pixel region 110 and a second reference pixel region 112. The photosensitive pixel region 110 includes M rows and N columns of pixels arranged in an array, used to output pixel data through a readout circuit 13 to obtain an image signal under the control of the control circuit 12. The second reference pixel region 112 includes m rows of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region 110. Each second reference pixel is used to receive a corresponding second input signal and, under the control of the control circuit 12, outputs a corresponding second output signal through the readout circuit 13, so as to determine whether the state of the control circuit 12 is normal based on the second input signal and the second output signal, wherein m is less than or equal to M, and m and M are natural numbers greater than 0.

[0081] Specifically, the second reference pixel region 112 includes m rows of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region 110. That is, each row of second reference pixels in the second reference pixel region 112 is selected from pixels in the same row of the photosensitive pixel region 110 via the same row line and the same pixel selection signal. The pixels are then read out by their respective readout sub-circuits via their corresponding column lines. These readout sub-circuits may include column-level ADCs corresponding to each column of pixels in the readout circuit 13, i.e., components in the readout circuit 13 corresponding to each column of pixels. The pixel selection signal is output to the corresponding row line by the row driver in the control circuit 12.

[0082] The number of pixel rows m in the second reference pixel region 112 can be less than or equal to the number of pixel rows M in the photosensitive pixel region 110. Preferably, m equals M, meaning that the pixel selection signal of each row of pixels can be checked. For example, by encoding each row of second reference pixels, a unique column code can be predetermined, that is, the input signal of each second reference pixel is encoded, such that m rows of second reference pixels in a column form an m-bit α-ary number (the readout circuit 13 converts the analog signal into a digital signal), and the corresponding m-bit α-ary number is pre-stored in the image sensor. For the second reference pixel, when the image sensor reads out the image signal, the second output signal of the second reference pixel is also read out. This is compared with a pre-stored 'a'-ary number (for example, which can represent the preset output signal corresponding to the second reference pixel under the selected second clamping voltage) to determine whether the control circuit 12 is functioning correctly (specifically, whether the pixel selection signal of the current row is normal). If it is determined that the signal does not correspond to the pre-stored 'a'-ary number (i.e., the second input signal and the second output signal of the second reference pixel do not correspond), the address of the erroneous pixel (row address) can be output, thus identifying the row driving circuit that is malfunctioning. For example, when the second pixel region consists of M rows of second reference pixels, each row of the photosensitive pixel array has a corresponding second reference pixel, which is selected using the same pixel selection signal. When the second output signal of the second reference pixel does not correspond to the second input signal, it indicates that the pixel selection signal is incorrect, and similarly, it can be determined that the image signal output by the simultaneously selected pixels in the photosensitive pixel array is incorrect.

[0083] It is worth mentioning that each second reference pixel in the second reference pixel region 112 is also read out by the readout circuit 13 under the control of the control circuit 12, so each second reference pixel is configured with a corresponding pixel address. Furthermore, the hardware also includes corresponding column lines and corresponding readout sub-circuits in the readout circuit 13.

[0084] It should be noted that the judgment module can determine whether the state of the control circuit 12 is normal based on the second input signal and the second output signal, and the judgment module can determine whether the state of the readout circuit 13 is normal based on the second input signal and the second output signal. This judgment module can be integrated into the functional logic unit 15.

[0085] In one embodiment, the second reference pixel region 112 includes two columns of m rows of second reference pixels that are disposed corresponding to the M rows of pixels in the photosensitive pixel region 110.

[0086] Specifically, for cost and self-test accuracy considerations, the second reference pixel region 112 in this embodiment includes two columns and m rows of second reference pixels to avoid errors in a single column of second reference pixels causing misjudgments in the self-test of the corresponding control circuit 12 (row drive circuit). That is, when the second output signals of the two columns of second reference pixels corresponding to each row of pixels in the photosensitive pixel region 110 do not correspond to the corresponding second input signals, the corresponding control circuit 12 (row drive circuit) is determined to be abnormal.

[0087] In one embodiment, the second pixel region further includes at least one second clamping voltage line for providing a second input signal for each second reference pixel; wherein the number of second clamping voltage lines is less than or equal to the number of second reference pixels.

[0088] Specifically, clamping voltage lines are used to connect to the second reference pixels, providing them with a second input signal. Depending on the encoding method, for example, setting different codes for each second reference pixel in the same column (i.e., setting different second input signals), the number of second clamping voltage lines required is equal to the number of second reference pixels in a column. In other embodiments, the input voltage on the second clamping voltage lines can also be changed, thus allowing a column of second reference pixels to receive a second input voltage through a single second clamping voltage line. Furthermore, for each second reference pixel, if each second reference pixel is encoded, and there are *a* second clamping voltage lines with fixed input voltages, then each second reference pixel will have *a* corresponding values ​​when quantized by the readout circuit 13. There are various data encoding methods here, which will not be described in detail.

[0089] In one embodiment, second reference pixels in the same column of second reference pixels that share the same control sub-circuit are connected to different second clamping voltage lines.

[0090] Specifically, by connecting the second reference pixels in the same column of second reference pixels that share the same control sub-circuit to different second clamping voltage lines, different clamping voltages can be used to detect the same control sub-circuit.

[0091] In one embodiment, the second reference pixel is physically connected to the selected second clamping voltage line; or, the second reference pixel is electrically connected to the corresponding second clamping voltage line via a second switching element.

[0092] Specifically, when the voltage on the second clamping voltage line is variable, the second reference pixel is physically connected to the selected second clamping voltage line, enabling the switching of various second input signals. When the voltage on the second clamping voltage line is fixed, the second reference pixel can be electrically connected to the corresponding second clamping voltage line via a second switching element to switch between different second input signals. Furthermore, the second switching element allows for more flexible matching between the reference pixel and the clamping voltage line.

[0093] In one embodiment, the structure of the second reference pixel is the same as that of the first reference pixel. The second reference pixel includes: a second source follower transistor and a second pixel selection transistor.

[0094] The gate of the second source follower transistor is used to receive the second input signal, the drain of the second source follower transistor is coupled to the second power supply voltage, and the source of the second source follower transistor is coupled to the drain of the second pixel selection transistor.

[0095] The gate of the second pixel selection transistor receives the pixel selection signal output by the control circuit, and the source of the second pixel selection transistor is coupled to the corresponding column line for outputting a second output signal through the readout circuit.

[0096] In one embodiment, the second reference pixel includes at least two second source follower transistors and a second pixel selection transistor, wherein the at least two second source follower transistors are connected in parallel.

[0097] Specifically, the gate of the second source follower transistor receives the corresponding second input signal, the drain of the second source follower transistor is coupled to the second power supply voltage, and the source of the second source follower transistor is coupled to the drain of the second pixel selection transistor; the gate of the second pixel selection transistor receives the pixel selection signal output by the control circuit, and the source of the second pixel selection transistor is coupled to the corresponding column line, so as to output the corresponding second output signal through the readout circuit.

[0098] For details regarding the specific structure of the second reference pixel not described herein, please refer to the various implementations of the first reference pixel and their accompanying drawings in the first embodiment. This embodiment will not repeat these details.

[0099] In this embodiment, the second reference pixel can be switched between different second input signals via hardware.

[0100] In summary, the pixel array provided in this embodiment can be used to realize the real-time self-test function of the control circuit in the image sensor, to check whether the image signal output by the image sensor is correct in real time, to improve the safety performance of the image sensor, and to enhance product competitiveness.

[0101] Example 3

[0102] Please refer to Figure 6 , Figure 6 This is a schematic diagram illustrating the structure and connection relationships of a pixel array provided in another embodiment of the present invention. Figure 6 As shown, the pixel array 11c includes: a photosensitive pixel region 110, a first reference pixel region 111, and a second reference pixel region 112.

[0103] The photosensitive pixel area 110 includes M rows and N columns of pixels arranged in an array (that is... Figure 1 The pixel array 101 in the control circuit 12 is used to output pixel data through the readout circuit 13 to obtain an image signal under the control of the control circuit 12.

[0104] The first reference pixel region 111 includes n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region 110. Each first reference pixel is used to receive a corresponding first input signal and output a corresponding first output signal through the readout circuit 13, so that the judgment module can determine whether the state of the readout circuit 13 is normal based on the first input signal and the first output signal. Here, n is less than or equal to N, and n and N are natural numbers greater than 0.

[0105] The second reference pixel region 112 includes m rows of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region 110. Each second reference pixel is used to receive a corresponding second input signal and, under the control of the control circuit 12, outputs a corresponding second output signal through the readout circuit 13. This signal is used by the judgment module to determine whether the state of the control circuit 12 is normal based on the second input signal and the second output signal. Here, m is less than or equal to M, and m and M are natural numbers greater than 0.

[0106] This embodiment includes both a first reference pixel region 111 and a second reference pixel region 112. For a detailed description, please refer to the foregoing embodiment, which will not be repeated here.

[0107] The pixel array provided in this embodiment can be used to realize the real-time self-test function of the control circuit and readout circuit in the image sensor, and to check in real time whether the image signal output by the image sensor is correct, thereby improving the safety performance of the image sensor and enhancing product competitiveness.

[0108] Example 4

[0109] Based on the same inventive concept, please refer to Figure 2This embodiment provides an image sensor, including: a pixel array (11a, 11b or 11c) according to any of the above embodiments.

[0110] Specifically, the pixel array includes a first reference pixel region and / or a second reference pixel region for determining whether the readout circuit 12 and / or the control circuit 13 are functioning correctly.

[0111] In one embodiment, the image sensor further includes a control circuit 12 and a readout circuit 13; the control circuit 12 includes a pixel driving circuit, which outputs a pixel selection signal to select any row in the pixel array for output; the readout circuit 13 reads the data of the pixel selected by the pixel selection signal.

[0112] In one embodiment, the image sensor further includes a judgment module, used to determine whether the state of the readout circuit 13 is normal based on the first input signal and the first output signal, and / or to determine whether the state of the control circuit 12 is normal based on the second input signal and the second output signal.

[0113] For other specific details, please refer to the aforementioned embodiments, which will not be repeated here.

[0114] In summary, the image sensor provided in this embodiment can realize the real-time self-test function of the readout circuit and / or control circuit, and verify in real time whether the image signal output by the image sensor is correct, thereby improving the safety performance of the image sensor and enhancing product competitiveness.

[0115] Example 5

[0116] Based on the same inventive concept, this embodiment provides a self-testing method for an image sensor, applicable to an image sensor in any of the above embodiments, the method comprising:

[0117] When the first output signal and the first input signal do not match the preset correspondence, the readout circuit is determined to be in an abnormal state.

[0118] And / or, when the second output signal and the second input signal do not conform to a preset correspondence, the control circuit is determined to be in an abnormal state.

[0119] Specifically, abnormal status can include two situations: one is that the readout sub-circuit itself has a problem; the other is that the readout sub-circuits are not the problem, but are connected incorrectly to each other, such as two adjacent readout sub-circuits being cross-connected with their corresponding columns.

[0120] In one embodiment, the method further includes:

[0121] When the first output signal and the first input signal do not match a preset correspondence, the pixel column address corresponding to the first output signal is output.

[0122] And / or, when the second output signal and the second input signal do not conform to a preset correspondence, output the pixel row address corresponding to the second output signal.

[0123] Specifically, for a better understanding of this technical solution, please refer to... Figure 7 , Figure 7 This is a schematic diagram of the self-test process of an image sensor provided in an embodiment of the present invention.

[0124] like Figure 7 As shown, after the image sensor is powered on, it begins pixel exposure. Then, it reads the signals from the pixels within the pixel array. Finally, it compares and determines the input and output signals of the first reference pixel and / or the second reference pixel.

[0125] If the input and output signals of the first and / or second reference pixels correspond correctly, the readout circuit and / or control circuit are considered to be functioning normally. If the input and output signals of the first and / or second reference pixels correspond incorrectly, the readout circuit and / or control circuit are considered to be functioning abnormally, and the address of the erroneous column or row is output. An alarm signal may also be output further.

[0126] In one embodiment, the method further includes:

[0127] If the first output signal and the first input signal do not conform to the preset correspondence, it is further determined whether the first output signal exceeds the preset range. If it is within the preset range, it is determined that the connection between the readout sub-circuits is incorrect.

[0128] Specifically, if the first output signal does not exceed the preset range, that is, the output deviation is relatively small, it can be determined that there is a problem with the connection between the readout sub-circuits. If it exceeds this preset range, it may be a problem with the connection or a problem with the readout sub-circuit itself.

[0129] In one embodiment, the preset range is greater than or equal to a first preset value and less than or equal to a second preset value; wherein,

[0130] The first preset value is greater than or equal to A and less than or equal to B, where A is the difference between the value of the first output signal in the preset correspondence and 1 / 4 of the value of the first output signal in the preset correspondence, and B is the difference between the value of the first output signal in the preset correspondence and 1 / 8 of the value of the first output signal in the preset correspondence; that is, for example, it can be set between a preset first output signal based on the first input signal and 1 / 8 to 1 / 4 of the preset first output signal.

[0131] The second preset value is greater than or equal to C and less than or equal to D, where C is the sum of the value of the first output signal in the preset correspondence and 1 / 8 of the value of the first output signal in the preset correspondence, and D is the sum of the value of the first output signal in the preset correspondence and 1 / 4 of the value of the first output signal in the preset correspondence. That is, for example, it can be set between the preset first output signal based on the first input signal and 1 / 8 to 1 / 4 of the preset first output signal.

[0132] Specifically, for example, if the first input signal of one of the first reference pixels is 2V, the first output signal in the preset correspondence should be 4V. Then, A is 4 - 4 * (1 / 4) = 3, B is 4 - 4 * (1 / 8) = 3.5, C is 4 + 4 * (1 / 8) = 4.5, and D is 4 + 4 * (1 / 4) = 5. That is, the preset range is from (3~3.5) to (4.5~5). In other words, the lower limit of the preset range is 3~3.5, and the upper limit is (4.5~5).

[0133] It should be noted that for any parts of this method embodiment that are not described or explained in detail, please refer to the description of the foregoing embodiments, and will not be repeated here.

[0134] In summary, the image sensor self-testing method provided in this embodiment can realize the real-time self-testing function of the readout circuit and / or control circuit, and verify in real time whether the image signal output by the image sensor is correct, thereby improving the safety performance of the image sensor and enhancing product competitiveness.

[0135] In the description of this specification, references to terms such as "an embodiment," "a implementation," "an example," or "a specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment, manner, or example is included in at least one embodiment, implementation, or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment, implementation, or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments, implementations, or examples described in this specification.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

Claims

1. A pixel array, characterized in that, include: The photosensitive pixel area includes M rows and N columns of pixels arranged in an array. The pixels are used to output pixel data through a readout circuit under the control of the control circuit to obtain an image signal. The first reference pixel region includes n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region; each first reference pixel is used to receive a corresponding first input signal and output a corresponding first output signal through the readout circuit, so as to determine whether the readout circuit is in normal condition based on the first input signal and the first output signal, wherein n is less than or equal to N, and n and N are natural numbers greater than 0. The first reference pixel region also includes at least one first clamping voltage line for providing the first input signal to each first reference pixel, and the number of first clamping voltage lines is less than or equal to the number of first reference pixels. The control circuit of the pixel array includes... A control sub-circuit corresponding to the first reference pixel in the first reference pixel region, wherein the first reference pixel is used to output a corresponding first output signal through the readout circuit under the control of the control sub-circuit to support the determination of whether the readout circuit is in normal condition. The first reference pixel is physically connected to the selected first clamping voltage line, or the first reference pixel is electrically connected to the corresponding first clamping voltage line through a first switching element. When there are first reference pixels in the same row that share the same readout sub-circuit in the readout circuit, the first reference pixels sharing the same readout sub-circuit are connected to different first clamping voltage lines; and / or, The second reference pixel region includes m rows of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region. Each second reference pixel receives a corresponding second input signal and, under the control of the control circuit, outputs a corresponding second output signal through the readout circuit. This output signal is used to determine whether the control circuit is functioning correctly based on the second input signal and the second output signal. Here, m is less than or equal to M, and m and M are natural numbers greater than 0. The second reference pixel region also includes at least one second clamping voltage line for providing the second input signal to each second reference pixel. The number of second clamping voltage lines is less than or equal to the number of second reference pixels. The readout circuit includes a readout sub-circuit corresponding to the second reference pixel in the second reference pixel region. The second reference pixel is used to output a corresponding second output signal through the readout sub-circuit under the control of the control circuit to support the determination of whether the state of the control circuit is normal. The second reference pixel is physically connected to the selected second clamping voltage line, or the second reference pixel is electrically connected to the corresponding second clamping voltage line through a second switching element. When there are second reference pixels in the same column that share the same control sub-circuit in the control circuit, the second reference pixels that share the same control sub-circuit are connected to different second clamping voltage lines.

2. The pixel array according to claim 1, characterized in that, The first reference pixel region includes at least two rows and n columns of first reference pixels corresponding to the N columns of pixels in the photosensitive pixel region; and / or, the second reference pixel region includes at least two rows and m columns of second reference pixels corresponding to the M rows of pixels in the photosensitive pixel region.

3. The pixel array according to claim 1, characterized in that, The first reference pixel has the same structure as the second reference pixel.

4. The pixel array according to any one of claims 1-3, characterized in that, The first reference pixel includes: a first pixel selection transistor and a first source follower transistor; and / or, the second reference pixel includes: a second pixel selection transistor and a second source follower transistor; Wherein, the gate of the first source follower transistor receives the corresponding first input signal, the drain of the first source follower transistor is coupled to the first power supply voltage, and the source of the first source follower transistor is coupled to the drain of the first pixel selection transistor; the gate of the first pixel selection transistor receives the pixel selection signal, and the source of the first pixel selection transistor is coupled to the corresponding column line, so as to output the corresponding first output signal through the readout circuit. The gate of the second source follower transistor receives the corresponding second input signal, the drain of the second source follower transistor is coupled to the second power supply voltage, and the source of the second source follower transistor is coupled to the drain of the second pixel selection transistor; the gate of the second pixel selection transistor receives the pixel selection signal, and the source of the second pixel selection transistor is coupled to the corresponding column line, so as to output the corresponding second output signal through the readout circuit.

5. The pixel array according to claim 4, characterized in that, The number of first source follower transistors is at least two, and each of the first source follower transistors is connected in parallel; and / or, the number of second source follower transistors is at least two, and each of the second source follower transistors is connected in parallel.

6. An image sensor, characterized in that, include: The pixel array as described in any one of claims 1-5.

7. The image sensor according to claim 6, characterized in that, The image sensor includes the readout circuit and the control circuit; wherein... The control circuit includes a pixel driving circuit, which outputs a pixel selection signal to select any pixel in the pixel array for output; the readout circuit reads the data of the pixel selected by the pixel selection signal.

8. A self-testing method for an image sensor, applied to the image sensor as described in any one of claims 6-7, characterized in that, include: When the first output signal and the first input signal do not conform to a preset correspondence, the readout circuit is determined to be in an abnormal state. And / or, when the second output signal and the second input signal do not conform to a preset correspondence, the control circuit is determined to be in an abnormal state.

9. The self-testing method for an image sensor according to claim 8, characterized in that, Also includes: When the first output signal and the first input signal do not have a preset correspondence, the pixel column address corresponding to the first output signal is output; And / or, when the second output signal and the second input signal do not conform to a preset correspondence, the pixel row address corresponding to the second output signal is output.

10. The self-testing method for an image sensor according to claim 9, characterized in that, Also includes: If the first output signal and the first input signal do not conform to a preset correspondence, it is further determined whether the first output signal exceeds a preset range. If it is within the preset range, it is determined that there is a connection error between the readout sub-circuits.

11. The self-testing method for an image sensor according to claim 10, characterized in that, The preset range is greater than or equal to a first preset value and less than or equal to a second preset value; wherein, The first preset value is greater than or equal to A and less than or equal to B, where A is the difference between the value of the first output signal in the preset correspondence and 1 / 4 of the value of the first output signal in the preset correspondence, and B is the difference between the value of the first output signal in the preset correspondence and 1 / 8 of the value of the first output signal in the preset correspondence. The second preset value is greater than or equal to C and less than or equal to D, where C is the sum of the value of the first output signal in the preset correspondence and 1 / 8 of the value of the first output signal in the preset correspondence, and D is the sum of the value of the first output signal in the preset correspondence and 1 / 4 of the value of the first output signal in the preset correspondence.

Images