Time delay integral image sensor

Abstract

The invention provides a time delay integral image sensor, which comprises an effective TDI array, a plurality of reference TDI arrays and an image processing unit, and is characterized in that the effective TDI array comprises a plurality of effective TDI sub-arrays, each effective TDI sub-array corresponds to one reference TDI array, and each reference TDI array corresponds to one effective TDI sub-array. The output end of each reference TDI subarray is aligned with the output end of the corresponding effective TDI subarray, exposure and integration can be carried out on the same imaging point at the same time, and n + 1 output signals are output together; and the image processing unit is used for performing weighting processing on each output signal and forming a corresponding image based on the weighted output signals. Therefore, the crosstalk in the output signal can be eliminated or reduced on the premise of not influencing other performances of the time delay integral image sensor, so that the performance of the time delay integral image sensor is improved, and the image quality is further improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a time-delayed integration image sensor. Background Art

[0002] Crosstalk is a major parameter affecting image quality in image sensors. It typically originates from two main sources: optical crosstalk, which occurs when incident light passes through a corresponding photosensitive cell in a TDI (Time Delayed and Integration) image sensor and strikes an adjacent photosensitive cell, causing crosstalk. Electrical crosstalk, on the other hand, occurs when photogenerated electrons diffuse into adjacent photosensitive cells, causing crosstalk. TDI (Time Delayed and Integration) technology, by accumulating multiple exposures of the same target, offers the advantage of significantly improving the sensitivity and signal-to-noise ratio of an imaging system. TDI technology requires a strict match between the image motion speed and the device scanning speed. Since TDI sensors operate by amplifying the signal by accumulating pixel exposure values ​​row by row, any crosstalk from external light sources or adjacent pixels can be continuously collected and added to the final output signal. Currently, a common method to reduce crosstalk is to add a metal barrier between adjacent photosensitive cells. However, although this method can effectively suppress crosstalk in other types of area array sensors, due to the special working principle of TDI sensors, metal blocking gratings cannot effectively reduce their crosstalk problems. Summary of the Invention

[0003] An object of the present invention is to provide a time-delayed integration image sensor to eliminate or reduce crosstalk in output signals.

[0004] To achieve the above object, the present invention provides a time delay integration image sensor, comprising an effective TDI array, a plurality of reference TDI arrays and an image processing unit;

[0005] The effective TDI array includes a plurality of effective TDI sub-arrays, each of the effective TDI sub-arrays has the same cumulative level, and each of the effective TDI sub-arrays corresponds to one reference TDI array;

[0006] Each of the reference TDI arrays includes n reference TDI subarrays, and the output end of each reference TDI subarray is aligned with the output end of the corresponding effective TDI subarray, so as to simultaneously expose and integrate the same imaging point and jointly output n+1 output signals, where n represents the number of the reference TDI subarrays in each reference TDI array, and n≥1;

[0007] The image processing unit is used to perform weighted processing on each of the output signals and form a corresponding image based on the weighted output signals.

[0008] Optionally, in the time delay integration image sensor, the time delay integration image sensor further includes a semiconductor substrate, and the effective TDI array and all reference TDI arrays are formed in the semiconductor substrate.

[0009] Optionally, in the time-delayed integration image sensor, the effective TDI subarray and the reference TDI subarray both include multiple pixel units, the arrangement of the pixel units of the effective TDI subarray is the same as the arrangement of the pixel units of each corresponding reference TDI subarray, and the structure of the pixel units of the effective TDI subarray is the same as the structure of the pixel units of each corresponding reference TDI subarray.

[0010] Optionally, in the time-delayed integration image sensor, pixel units of the effective TDI subarray and the corresponding reference TDI subarray correspond to and are aligned with each other.

[0011] Optionally, in the time delayed integration image sensor, a scanning direction of the effective TDI subarray is the same as a scanning direction of the reference TDI array.

[0012] Optionally, in the time-delayed integration image sensor, the image processing unit performs the weighted processing by setting a weighting factor for each of the output signals, and different output signals have different weighting factors.

[0013] Optionally, in the time-delayed integration image sensor, the weighting factor, the accumulation level of each reference TDI subarray, and the number of reference TDI subarrays in each reference TDI array are set according to a preset signal-to-noise ratio.

[0014] Optionally, in the time-delayed integration image sensor, the accumulation levels of each reference TDI sub-array in the reference TDI array are different.

[0015] Optionally, in the time delay integration image sensor, the weighting factor and the cumulative series of the n reference TDI sub-arrays satisfy the following relationship:

[0016]

[0017] Wherein, K0 represents the weighting factor of the output signal of the effective TDI subarray; M0 represents the cumulative level of the effective TDI subarray; M iIt represents the accumulated level of the i-th reference TDI subarray corresponding to the effective TDI subarray; Ki represents the weighting factor of the output signal of the i-th reference TDI subarray; i represents the serial number of the reference TDI subarray.

[0018] Optionally, in the time delay integration image sensor, the weighting factor and the cumulative series of the n reference TDI sub-arrays satisfy the following relationship:

[0019]

[0020] Wherein, K0 represents the weighting factor of the output signal of the effective TDI subarray; M0 represents the cumulative level of the effective TDI subarray; M i K represents the cumulative level of the i-th reference TDI sub-array corresponding to the effective TDI sub-array; i It represents the weighting factor of the output signal of the i-th reference TDI subarray; i represents the serial number of the reference TDI subarray.

[0021] In the time-delayed integration image sensor provided by the present invention, the time-delayed integration image sensor includes an effective TDI array, multiple reference TDI arrays, and an image processing unit. The effective TDI array includes multiple effective TDI subarrays, each of which corresponds to a reference TDI array. The output end of each reference TDI subarray is aligned with the output end of the corresponding effective TDI subarray, so that the same imaging point can be simultaneously exposed and integrated and n+1 output signals can be output together. The image processing unit is used to perform weighted processing on each output signal and form a corresponding image based on the weighted output signal. In this way, crosstalk in the output signal can be eliminated or reduced without affecting other performance of the time-delayed integration image sensor, thereby improving the performance of the time-delayed integration image sensor and further improving image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a schematic diagram of the principles of an effective TDI array and multiple reference TDI arrays in a time delay integration image sensor according to an embodiment of the present invention;

[0023] Figure 2 is a schematic cross-sectional structural diagram of a semiconductor substrate in a time-delayed integration image sensor according to an embodiment of the present invention;

[0024] Figure 3 1 is a schematic diagram showing the principle of an effective TDI array in a time delay integration image sensor according to an embodiment of the present invention when in a working state;

[0025] The description of the accompanying drawings is as follows:

[0026] 10 - substrate; 100 - active TDI array; 100a - active TDI sub-array; 101 - pixel unit; 200 - reference TDI array; 200a - reference TDI sub-array. DETAILED DESCRIPTION

[0027] The following is a further detailed description of the time-delayed integration image sensor proposed by the present invention, with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0028] Figure 1 4 is a schematic diagram of the principles of an effective TDI array and multiple reference TDI arrays in a time delay integration image sensor according to an embodiment of the present invention. Figure 2 FIG is a schematic cross-sectional view of a semiconductor substrate in a time-delayed integration image sensor according to an embodiment of the present invention. Figure 1 Combined with Figure 2 As shown, this embodiment provides a time delay integration image sensor, including an effective TDI array 100, a plurality of reference TDI arrays 200 and an image processing unit (not shown).

[0029] In this embodiment, the effective TDI array 100 can perform multiple exposures and integrations on the same imaging point, thereby accumulating more photons, enhancing signal strength, and reducing noise, thereby improving the signal-to-noise ratio (SNR) of the image. The effective TDI array 100 includes multiple effective TDI sub-arrays 100a, each of which has the same accumulation level. This ensures signal consistency and stability during the integration process. Furthermore, each effective TDI sub-array 100a can accumulate signals at the same accumulation level when acquiring image data, thereby improving the signal-to-noise ratio (SNR) and image clarity. A time-delayed integration image sensor can include at least one effective TDI array 100.

[0030] like Figure 1 As shown, each of the effective TDI sub-arrays 100 a corresponds to one of the reference TDI arrays 200 . The reference TDI array 200 is used to provide a reference signal to calibrate the output signal of the effective TDI array 100 , thereby eliminating or reducing crosstalk in the output signal.

[0031] like Figure 2 As shown, the time delay integration image sensor further includes a semiconductor substrate 10 , in which the effective TDI array 100 and all reference TDI arrays 200 are formed.

[0032] In this embodiment, each reference TDI array 200 includes n reference TDI sub-arrays 200a. Each effective TDI sub-array 100a in the same effective TDI array 100 corresponds to the same number of reference TDI sub-arrays 200a, ensuring that the output signals of all reference TDI arrays 200 corresponding to the same effective TDI array 100 are consistent. The number of reference TDI sub-arrays 200a corresponding to the effective TDI sub-arrays 100a in different effective TDI arrays 100 can be different, or the number of reference TDI sub-arrays 200a corresponding to the effective TDI sub-arrays 100a in different effective TDI arrays 100 can be the same.

[0033] like Figure 1 As shown, the effective TDI subarray 100a and the reference TDI subarray 200a both include a plurality of pixel units 101. The arrangement of the pixel units 101 of the effective TDI subarray 100a is the same as the arrangement of the pixel units 101 of each corresponding reference TDI subarray 200a, and the structure of the pixel units of the effective TDI subarray 100a is the same as the structure of the pixel units of each corresponding reference TDI subarray 200a, so that the structure of the pixel units of the effective TDI subarray 100a matches the structure of the pixel units of the reference TDI subarray 200a.

[0034] Specifically, the pixel units 101 of the reference TDI subarray 200a and the effective TDI subarray 100a are the same in size, shape, position and spacing, so that the reference TDI subarray 200a can be basically consistent with the effective TDI subarray 100a in image processing, signal acquisition or data transmission.

[0035] Figure 3 FIG. 1 is a schematic diagram showing the principle of the effective TDI array in the time delay integration image sensor of an embodiment of the present invention when it is in working state. Figure 3 As shown, the scanning direction X of the reference TDI subarray is the same as the scanning direction X of the effective TDI subarray 100a. That is, when the effective TDI subarray 100a scans along a predetermined direction, all reference TDI subarrays 200a corresponding to the effective TDI subarray 100a also scan along the exact same direction, ensuring consistency during signal acquisition. Furthermore, the scanning direction X of the reference TDI subarray and the scanning direction X of the effective TDI subarray 100a are both the same as the direction of motion of the object.

[0036] Since the scanning direction X of the reference TDI subarray is the same as the scanning direction X of the effective TDI subarray 100a, the effective TDI subarray 100a and the reference TDI subarray 200a can simultaneously capture information of the same object, thereby avoiding distortion or misalignment of the subsequent image formed due to different scanning directions X. Figure 1 As shown, the reference TDI sub-array 200a and the effective TDI sub-array 100a can simultaneously capture information of object A, object B, and object C.

[0037] In this embodiment, the pixel units 101 of the effective TDI subarray 100a and the corresponding reference TDI subarray 200a correspond to and are aligned with each other. The output terminal out of each reference TDI subarray 200a is aligned with the output terminal out of the corresponding effective TDI subarray 100a, so that the same imaging point is simultaneously exposed and integrated and n+1 output signals are jointly output. That is, n reference TDI subarrays 200a each output n output signals, and the effective TDI subarray 100a each outputs one output signal, where n represents the number of reference TDI subarrays in each reference TDI array, and n≥1.

[0038] Specifically, when the time-delayed integration image sensor is in operation, the reference TDI subarray 200a and the effective TDI subarray 100a are simultaneously exposed and integrate at the same imaging point. During the integration process, the pixel units 101 of the reference TDI subarray 200a and the effective TDI subarray 100a accumulate signals according to their respective accumulation levels to enhance the signal and suppress noise.

[0039] like Figure 1 As shown, after exposure and integration are complete, the output terminal out of the reference TDI subarray 200a and the output terminal out of the corresponding effective TDI subarray simultaneously output signals. Because the output terminal out of each reference TDI subarray 200a is aligned with the output terminal out of the corresponding effective TDI subarray, the output signals can be output simultaneously. The output signals can reflect the light intensity distribution and changes at the same imaging point.

[0040] like Figure 1 As shown, the accumulation levels of the n reference TDI sub-arrays 200a are different. Here, it should be noted that, Figure 1The objects A, B, and C in the reference TDI subarray 200a are merely examples illustrating different accumulation levels for the reference TDI subarray 200a. While ensuring that the accumulation levels for each reference TDI subarray 200a are different, the accumulation level for each reference TDI subarray 200a can be adjusted. The accumulation level for each reference TDI subarray 200a can be set based on a preset signal-to-noise ratio to improve the signal-to-noise ratio.

[0041] In this embodiment, the accumulation levels of the n reference TDI sub-arrays 200a are M1, M2, M3...M n Therefore, the output terminal out of the effective TDI sub-array 100a and the output terminal out of the corresponding reference array 200 will have n+1 output signals when outputting, where n≥1, and n represents the number of all reference TDI sub-arrays 200a in the reference array 200 corresponding to one effective TDI sub-array 100a.

[0042] like Figure 3 As shown, the effective TDI subarray 100a scans the target object along the scanning direction. During the scanning process, each pixel unit 101 of the effective TDI subarray 100a exposes and integrates the passing objects A, B, and C in turn. As the TDI image sensor or the target object moves, the integration of the effective TDI subarray 100a also varies. The pixel units 101 of the effective TDI subarray 100a will gradually capture the image information of objects A, B, and C at their respective different transit times t0, t0+T, and t0+2T. Furthermore, when the TDI image sensor is in operation, the effective signal generated at each transit time is denoted as A, the noise is denoted as δ, and the crosstalk generated is denoted as T. Since TDI image sensors are generally used in conditions with low light intensity and very short transit times, the noise δ is the square root of the effective signal A. Therefore, after signal accumulation, the output signal is read using the coherent double sampling method, and the intensity of the output signal of each effective TDI subarray 100a is obtained as:

[0043]

[0044] Wherein, represents the intensity of the output signal of the effective TDI sub-array 100a; M0 represents the cumulative level of the effective TDI sub-array 100a; A represents the effective signal generated by each transit time; δ represents the noise; and T represents the crosstalk.

[0045] In this embodiment, because TDI (Time Delay and Integration) sensors are often used in low-light environments, where light signals are extremely weak and photon transit times are typically very short, the signal strength received by the effective TDI subarray 100a is relatively low, while the noise is relatively high. This is because, given a limited number of photons, noise is primarily caused by the randomness of photon arrival, i.e., fluctuations in the number of photons. As signal strength decreases, this randomness becomes more pronounced, resulting in a relatively high noise level.

[0046] By exposing and integrating the same imaging point multiple times, the effective TDI subarray 100a accumulates more photons, thereby enhancing the signal and relatively reducing noise. However, noise still exists. Therefore, after signal accumulation in the effective TDI subarray 100a, a coherent double sampling readout method is used to further extract the effective signal and suppress noise. Specifically, the coherent double sampling readout method first reads the signal values ​​at two different time points (usually a reset point and an integration point), then calculates the difference between them, thereby eliminating noise unrelated to the pixel units 101 of the effective TDI subarray 100a.

[0047] For the reference TDI array 200, each reference TDI sub-array 200a in the reference TDI array 200 has a different accumulation level, and thus reads out different data (i.e., output signals with different intensities). The intensity of the output signal of each reference TDI sub-array 200a is: For example, if the accumulation level of the first reference TDI subarray is 9, then The accumulation level of the second reference TDI subarray is 4, then The cumulative level of the third reference TDI subarray is 1, then V3=A+δ; where V n It is represented by the output signal strength of the nth reference TDI sub-array; M n represents the accumulated level of the nth reference TDI subarray; A represents the effective signal generated at each transit time; δ represents the noise; T represents the crosstalk; n represents the serial number of the reference TDI subarray 200a, n≥1; V1 represents the intensity of the output signal of the first reference TDI subarray; V2 represents the intensity of the output signal of the second reference TDI subarray; V3 represents the intensity of the output signal of the third reference TDI subarray.

[0048] Therefore, the output terminal out of each reference TDI sub-array 200 a in the reference TDI array 200 and the output terminal out of the corresponding effective TDI sub-array 100 a will have n+1 output signals when outputting.

[0049] In this embodiment, the image processing unit is configured to perform weighted processing on each of the output signals and to form a corresponding image based on the weighted output signals. The image processing unit implements the weighted processing by assigning a weighting factor to each of the output signals, with different weighting factors being applied to different output signals. This eliminates or reduces crosstalk in the output signals without affecting other performance characteristics of the time-delayed integration image sensor, thereby improving the performance of the time-delayed integration image sensor and, consequently, enhancing image quality.

[0050] In this embodiment, the weighting factor and the number of the reference TDI sub-arrays 200a in each reference TDI array 200 may be set according to a preset signal-to-noise ratio to eliminate or reduce crosstalk in the output signal, especially optical crosstalk in the output signal.

[0051] In this embodiment, the weighting factor and the cumulative number of the n reference TDI subarrays satisfy the following first relationship to eliminate or reduce crosstalk. The first relationship is specifically as follows:

[0052]

[0053] Wherein, K0 represents the weighting factor of the output signal of the effective TDI subarray; M0 represents the cumulative level of the effective TDI subarray; M i K represents the cumulative level of the i-th reference TDI sub-array corresponding to the effective TDI sub-array; i It represents the weighting factor of the output signal of the i-th reference TDI subarray; i represents the serial number of the reference TDI subarray.

[0054] Alternatively, the weighting factor and the cumulative number of the n reference TDI subarrays satisfy the following second relationship, so as to improve the signal-to-noise ratio while eliminating or reducing crosstalk in the output signal. The specific relationship is as follows:

[0055]

[0056] Wherein, K0 represents the weighting factor of the output signal of the effective TDI subarray; M0 represents the cumulative level of the effective TDI subarray; M i K represents the cumulative level of the i-th reference TDI sub-array corresponding to the effective TDI sub-array; i It represents the weighting factor of the output signal of the i-th reference TDI subarray; i represents the serial number of the reference TDI subarray.

[0057] In summary, the time-delayed integration image sensor provided by the present invention includes an effective TDI array, multiple reference TDI arrays, and an image processing unit. The effective TDI array includes multiple effective TDI sub-arrays, each of which corresponds to a reference TDI array. The output end of each reference TDI sub-array is aligned with the output end of the corresponding effective TDI sub-array, and the same imaging point can be exposed and integrated simultaneously and n+1 output signals can be output together. The image processing unit is used to perform weighted processing on each output signal and form a corresponding image based on the weighted output signal. In this way, crosstalk in the output signal can be eliminated or reduced without affecting other performance of the time-delayed integration image sensor, thereby improving the performance of the time-delayed integration image sensor and further improving image quality.

[0058] Furthermore, it should be recognized that although the present invention has been disclosed above with reference to preferred embodiments, the above embodiments are not intended to limit the present invention. Any person skilled in the art can utilize the above disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent variations, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A time-delayed integration image sensor, characterized in that: including an effective TDI array, a plurality of reference TDI arrays, and an image processing unit; The effective TDI array includes a plurality of effective TDI sub-arrays, each of the effective TDI sub-arrays has the same cumulative level, and each of the effective TDI sub-arrays corresponds to one reference TDI array; Each of the reference TDI arrays includes n reference TDI subarrays, and the output end of each reference TDI subarray is aligned with the output end of the corresponding effective TDI subarray, so as to simultaneously expose and integrate the same imaging point and jointly output n+1 output signals, where n represents the number of the reference TDI subarrays in each reference TDI array, and n≥1; The image processing unit is used to perform weighted processing on each of the output signals and form a corresponding image based on the weighted output signals.

2. The time-delayed integration image sensor according to claim 1, wherein The time delay integration image sensor further includes a semiconductor substrate, in which the effective TDI array and all reference TDI arrays are formed.

3. The time-delayed integration image sensor according to claim 1, wherein: The effective TDI subarray and the reference TDI subarray both include a plurality of pixel units, the arrangement of the pixel units of the effective TDI subarray is the same as the arrangement of the pixel units of each corresponding reference TDI subarray, and the structure of the pixel units of the effective TDI subarray is the same as the structure of the pixel units of each corresponding reference TDI subarray.

4. The time-delayed integration image sensor according to claim 3, wherein: The pixel units of the effective TDI sub-array and the corresponding reference TDI sub-array correspond to and are aligned with each other.

5. The time-delayed integration image sensor according to claim 1, wherein: The scanning direction of the effective TDI sub-array is the same as the scanning direction of the reference TDI array.

6. The time-delayed integration image sensor according to claim 1, wherein: The image processing unit performs the weighted processing by setting a weighting factor for each of the output signals, and different output signals have different weighting factors.

7. The time-delayed integration image sensor according to claim 6, wherein: The weighting factor, the accumulation level of each reference TDI subarray, and the number of the reference TDI subarrays in each reference TDI array are set according to a preset signal-to-noise ratio.

8. The time-delayed integration image sensor according to claim 7, wherein: The accumulation levels of each of the reference TDI sub-arrays in the reference TDI array are different.

9. The time-delayed integration image sensor according to claim 8, wherein: The weighting factor and the cumulative number of the n reference TDI subarrays satisfy the following relationship: Wherein, K0 represents the weighting factor of the output signal of the effective TDI subarray; M0 represents the cumulative level of the effective TDI subarray; M i K is represented by the accumulated level of the i-th reference TDI sub-array corresponding to the effective TDI sub-array; i It represents the weighting factor of the output signal of the i-th reference TDI subarray; i represents the serial number of the reference TDI subarray.

10. The time-delayed integration image sensor according to claim 8, wherein: The weighting factor and the cumulative number of the n reference TDI subarrays satisfy the following relationship: Among them, K0 represents the weighting factor of the output signal of the effective TDI subarray; M0 represents the cumulative level of the effective TDI subarray; Mi represents the cumulative level of the i-th reference TDI subarray corresponding to the effective TDI subarray; Ki represents the weighting factor of the output signal of the i-th reference TDI subarray; i represents the serial number of the reference TDI subarray.

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