Image sensor on-orbit life prolonging device and method based on optimal working temperature zone

Abstract

The invention relates to an image sensor on-orbit life prolonging device and method based on an optimal working temperature area. The device comprises a temperature control system, an image sensor driving plate, a semiconductor chilling plate and a heat conduction silica gel pad. The semiconductor chilling plate is connected with the temperature control system and the image sensor driving plate; the image sensor is connected with the temperature control system and the image sensor driving board; the semiconductor chilling plate and the image sensor are tightly attached through a heat conduction silica gel pad. The method comprises the following steps: determining the performance parameter drift condition of the image sensor under different radiation damage doses by utilizing an irradiation ground simulation test; determining the optimal working temperature areas of the image sensors with different damages; determining the radiation damage dose of the in-orbit operation time through an orbit radiation environment model; determining a relation curve between the on-orbit operation time and the optimal working temperature zone; and setting the working environment temperature under different on-orbit operation time, and adjusting the working environment temperature of the image sensor according to the working environment temperature.

Description

Technical Field

[0001] The present invention relates to the fields of in-orbit life extension and radiation hardening of image sensors, and specifically relates to an in-orbit life extension device and method for an image sensor based on an optimal operating temperature range. Background Art

[0002] The basic principle of an image sensor is to convert incident photons into electrons through the photoelectric effect, and finally generate an image after charge accumulation, transfer, signal processing, and digitization. In the aerospace field, image sensors, as the core key components of important payloads such as earth remote sensing cameras, space monitoring cameras, and star sensors, are widely used in tasks such as spacecraft attitude control, navigation, and scientific observation. However, high-energy particles existing in the space radiation environment can cause the performance of image sensors to degrade rapidly, specifically manifested as an increase in dark current, an increase in noise, pixel failure, etc. Aerospace practices at home and abroad have shown that the performance degradation caused by the permanent damage of the core load image sensor under space radiation is the main reason for the in-orbit performance degradation and shortened life of optical satellites.

[0003] Currently, radiation hardening technologies include shielding layer hardening, radiation-resistant manufacturing process hardening for chips, and circuit software design hardening. Since the focal plane of an image sensor requires photon incidence, it is difficult to implement the shielding layer hardening technology that traditionally uses high-density materials to block devices. As an advanced and complex integrated circuit chip design, the manufacturing process of an image sensor is complex, and it is difficult to use radiation-resistant processes such as SOI for hardening. Circuit software design hardening corrects abnormal data through data processing means, cannot truly solve the problem of increased noise in the original data caused by the performance degradation of the image sensor itself, and there is a hidden danger of over-processing data. There are also some patents related to the field of radiation hardening of image sensors, but none of them involve the field of in-orbit life extension of image sensors.

[0004] Patent CN 115951935 A discloses a register configuration control system suitable for radiation-resistant image sensors. Through circuit software design hardening, it uses a large target surface image sensor to control the partition control of registers and a triple modular redundancy control module for the register code table, and the gap control of the register group layout design to achieve single-event upset resistance of the large target surface image sensor. Circuit software design hardening mainly focuses on post-acquisition data processing, and for single-event effects, it cannot truly solve the problem of increased noise in the original data caused by the performance degradation of the image sensor itself, and over-processing of data will bring hidden dangers to data authenticity.

[0005] Patent CN 114266436 A discloses a method for on-orbit health assessment of star sensors, as well as a storage medium and an electronic device. By establishing an on-orbit health assessment system, it calibrates and assesses nominal on-orbit abnormal states, and sets health weight coefficients and severity levels. This patent only realizes the detection of the on-orbit state of star sensors and does not achieve the on-orbit life extension of aerospace image sensors.

[0006] Patent CN 108924393 B (a heat dissipation structure for a large-format image sensor) and Patent CN 110108272 B (a thermal design method for a star sensor with stable temperature) achieve the temperature control of aerospace image sensors through mechanical structure design, and there is no design to achieve the on-orbit life extension of devices by controlling the working environment temperature. Summary of the Invention

[0007] The purpose of the present invention is to provide an on-orbit life extension device and method for an image sensor based on the optimal operating temperature range, so as to solve the problems that the on-orbit performance of optical satellites degrades and the service life is shortened due to the performance degradation of image sensors in the space radiation environment.

[0008] To achieve the above purpose, the present invention provides an on-orbit life extension device for an image sensor based on the optimal operating temperature range, including a temperature control system, an image sensor drive board, a semiconductor refrigeration chip, a thermal conductive silicone pad, and a camera cover plate; the thermal conductive silicone pad is arranged between the semiconductor refrigeration chip and the image sensor, the thermal conductive silicone pad is closely attached to the surface of the image sensor, and the semiconductor refrigeration chip is closely attached to the thermal conductive silicone pad; the semiconductor refrigeration chip is connected to the temperature control system and the image sensor drive board through a control line; the image sensor is connected to the temperature control system and the image sensor drive board through pins; the image sensor is placed on the camera cover plate, and the temperature control system and the image sensor drive board are fixedly connected to the camera cover plate.

[0009] For the above on-orbit life extension device for an image sensor based on the optimal operating temperature range, the thermal conductive silicone pad is closely attached to the area of the surface of the image sensor where pins are arranged except for the pins and the side surface of the image sensor; the semiconductor refrigeration chip has a "day" - shaped structure and is closely attached to the area of the surface of the image sensor where pins are arranged except for the pins and the side surface of the image sensor.

[0010] Another technical solution provided by the present invention is a method for on-orbit life extension of an image sensor based on the optimal operating temperature range, which uses the above-mentioned device for on-orbit life extension of an image sensor; the method includes: 1) determining the performance degradation degree and performance parameter drift of the image sensor under different radiation damage doses by using an irradiation ground simulation test; 2) for the image sensors with different degrees of irradiation damage obtained from the irradiation ground simulation test, determining the temperature at which the performance parameters are restored to the allowable range before irradiation, and defining this temperature as the optimal operating temperature range corresponding to this degree of irradiation damage; 3) determining the cumulative situation of the radiation damage dose during the on-orbit operation time of this orbit through an orbital radiation environment model; 4) according to steps 1) to 3), determining the relationship curve between the on-orbit operation time of this orbit and the optimal operating temperature range of the image sensor; 5) according to the relationship curve between the on-orbit operation time and the optimal operating temperature range of the image sensor obtained in step 4), setting the working environment temperature of the image sensor at different on-orbit operation times, and accordingly adjusting the working environment temperature of the image sensor through a temperature control system to effectively inhibit the performance degradation and performance parameter drift of the image sensor caused by the space irradiation environment, and realizing the correction and recovery of the performance of the image sensor; 6) performing image comparison through on-orbit calibration at regular intervals to determine the actual performance degradation degree and performance parameter drift of the image sensor, and accordingly further adjusting the working environment temperature of the image sensor through the temperature control system to realize more accurate correction and recovery of the performance parameters of the image sensor.

[0011] In the above-mentioned method for on-orbit life extension of an image sensor based on the optimal operating temperature range, the performance parameters include dark current and full well capacity.

[0012] In the above-mentioned method for on-orbit life extension of an image sensor based on the optimal operating temperature range, in step 2), by maintaining the consistency of the performance parameters of the image sensor during operation, the consistency of the process of collecting original images can be ensured, which is beneficial to ensuring the effectiveness of subsequent image processing algorithms.

[0013] In the above-mentioned method for on-orbit life extension of an image sensor based on the optimal operating temperature range, in step 5), the working environment temperature of the image sensor at different on-orbit operation times set according to the relationship curve between the on-orbit operation time and the optimal operating temperature range of the image sensor is input into the temperature control system in advance; a temperature sensor is arranged inside the image sensor to collect the temperature of the image sensor in real time and send it to the temperature control system, and the temperature control system controls the operation of the semiconductor refrigeration chip by using PID control technology according to the set working environment temperature and the actual temperature of the image sensor, so that the temperature of the image sensor is consistent with the set working environment temperature.

[0014] The above-mentioned method for on-orbit life extension of an image sensor based on the optimal operating temperature range, wherein, in step 6), if it is found through image comparison that the performance of the image sensor has deteriorated, the operating environment temperature of the image sensor is gradually reduced by fine-tuning until the performance parameters of the image sensor are corrected and restored.

[0015] The above-mentioned method for on-orbit life extension of an image sensor based on the optimal operating temperature range, wherein, in step 6), based on the star map or ground marks, the actual performance degradation degree and performance parameter drift of the image sensor are determined through historical image comparison in the same position and pose; or based on the on-orbit calibration method of radiation calibration for historical image comparison to determine the actual performance degradation degree and performance parameter drift of the image sensor.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0017] 1) By means of the control strategy in the optimal operating temperature range, the on-orbit life of the image sensor and the optical satellite can be significantly extended, ensuring the continuous and stable operation of the spacecraft in the space environment, and providing stronger support for deep space exploration and long-term on-orbit missions;

[0018] 2) It overcomes the disadvantages of the traditional static radiation hardening technology for devices and their software, which is complex in device design, expensive in manufacturing cost, and difficult to actually implement. The present invention realizes on-orbit life extension for the dynamic performance guarantee strategy during the long-term use of devices, with low cost, strong feasibility, and can reduce noise and improve performance from the source of data acquisition;

[0019] 3) The on-orbit life extension device of the present invention increases the fitting area between the semiconductor refrigeration sheet and the image sensor through targeted fitting design, with a simple structure and effectively improves the temperature control ability; by controlling the temperature, the consistency of image acquisition by the image sensor in different regions of the space environment (such as under sunlight and in the earth's shadow) is ensured;

[0020] 4) The on-orbit life extension device and method of the image sensor based on the optimal operating temperature range of the present invention can be extended to cover the anti-radiation hardening requirements of all star sensors, space cameras, and even various optoelectronic products for space applications. By effectively suppressing the performance degradation of the sensor in the corresponding low-temperature environment, the performance of the device itself can be fully exploited, improving mission reliability, reducing maintenance costs, and supporting long-term missions, and having good prospects for popularization and application. Description of the Drawings

[0021] The on-orbit life extension device and method of the image sensor based on the optimal operating temperature range of the present invention are given by the following embodiments and drawings.

[0022] Figure 1 It is a graph showing the dark current of the image sensor changing with temperature.

[0023] Figure 2It is the light response curve graph of the image sensor at different temperatures.

[0024] Figure 3 It is the graph of the full well capacity of the image sensor changing with temperature.

[0025] Figure 4 It is the explosion diagram of the on-orbit life extension device of the image sensor based on the optimal working temperature range in the embodiment of the present invention.

[0026] Figure 5 It is the structure diagram after the assembly between the thermoelectric cooler and the image sensor in the embodiment of the present invention.

[0027] Figure 6 It is the flow chart of the on-orbit life extension method of the image sensor based on the optimal working temperature range in the embodiment of the present invention.

[0028] Figure 7 It is the relationship curve graph between the on-orbit operation time and the optimal working temperature range of the image sensor on a certain orbit in the embodiment of the present invention. Specific embodiments

[0029] The following will combine Figures 1 to 7 to further describe in detail the on-orbit life extension device and method of the image sensor based on the optimal working temperature range of the present invention.

[0030] The performance of the image sensor is closely related to the working environment temperature. Low-temperature operation can reduce dark current noise and increase the full well capacity, which can alleviate the influence of the performance degradation of the image sensor.

[0031] Dark current is the current formed by electrons that are spontaneously generated due to the existence of various defects (interface defects and bulk defects) in the pixel under the condition of no light and are absorbed by the photodiode. The unit of pixel dark current is e / pixel / s. When the temperature is relatively low, as the temperature increases, the dark current increases slowly; when the temperature is relatively high, the dark current increases rapidly with the temperature, as shown in Figure 1 . The pixel dark current is mainly composed of the following three parts: the reverse bias current J gen of the P-N junction in the body, the substrate diffusion current J diff , and the surface generation recombination current J surf . When the ambient temperature is T, the total dark current J d can be expressed as:

[0032]

[0033] In the above formula, the three terms respectively represent the reverse bias current J gen of the P-N junction in the body, the substrate diffusion current J diff , and the surface generation recombination current J surf , where W is the depletion layer width, q is the charge, and n iis the intrinsic carrier concentration, τ g is the carrier generation lifetime, D n is the electron diffusion coefficient, and S0 is the surface generation rate. Since at low temperatures J surf >>J gen >>J diff , so at low temperatures the surface generation recombination current dominates, and the surface generation recombination current is proportional to T 3 / 2 , so the dark current does not increase very quickly with increasing temperature at this time; when the temperature is higher, the substrate diffusion current J diff increases sharply, exceeding the reverse bias current J of the in-body P-N junction gen and the surface generation recombination current J surf becomes the main source of the dark current and dominates. This is because the substrate diffusion current J diff has a high temperature dependence and is proportional to T 3 . Therefore, when the temperature drops, the dark current of the device also decreases, thereby reducing the obtained image noise and suppressing a part of the hot pixels.

[0034] The full well capacity refers to the maximum number of electrons that a pixel can accommodate, with the unit of e - , which characterizes the maximum signal that the device can respond to and is one of the most basic performance parameters of the image sensor. It is determined by factors such as the physical size of the pixel structure, the voltage applied to the gate, and the doping concentration of the device. The full well capacity also indirectly determines performance parameters such as the dynamic range and signal-to-noise ratio of the image sensor. Increasing the full well capacity can also drive the improvement of these parameters. From the light response curve of the image sensor (such as Figure 2 ), it can be seen that by reducing the operating temperature, the full well capacity of the device can be increased (such as Figure 3 ), expanding the acquisition signal range and improving the signal-to-noise ratio of the obtained image.

[0035] Figure 4 Shown is the explosion diagram of the in-orbit life extension device of the image sensor based on the optimal operating temperature range according to the embodiment of the present invention; Figure 5 Shown is the structural diagram after the assembly between the thermoelectric cooler and the image sensor in the embodiment of the present invention.

[0036] Referring to Figure 4 and Figure 5 , the in-orbit life extension device of the image sensor based on the optimal operating temperature range in this embodiment includes a temperature control system and an image sensor driving board 1, a thermoelectric cooler 2, a thermal conductive silicone pad 3, and a camera cover 5;

[0037] The thermal conductive silicone pad 3 is disposed between the thermoelectric cooler 2 and the image sensor 4. The thermal conductive silicone pad 3 is closely attached to the surface of the image sensor 4, and the thermoelectric cooler 2 is closely attached to the thermal conductive silicone pad 3;

[0038] The semiconductor refrigeration chip 2 is connected to the temperature control system and the image sensor driving board 1 through a control line;

[0039] The image sensor 4 is connected to the temperature control system and the image sensor driving board 1 through a pin 41;

[0040] The image sensor 4 is placed on the camera cover plate 5, and the temperature control system and the image sensor driving board 1 are fixedly connected to the camera cover plate 5.

[0041] The surface of the image sensor 4 where the pins are arranged is facing upward and placed inside the camera cover plate 5; the area other than the pins on the surface of the image sensor 4 where the pins are arranged and the side surface of the image sensor are tightly attached to the heat-conducting silica gel pad 3; the semiconductor refrigeration chip 2 has a "day" - shaped structure and is tightly attached to the area other than the pins on the surface of the image sensor 4 where the pins are arranged and the side surface of the image sensor, and the heat-conducting silica gel pad 3 is placed between the semiconductor refrigeration chip 2 and the image sensor 4. Through the adaptation design of the semiconductor refrigeration chip with the image sensor package, it is possible to fit as completely as possible the remaining area of the image sensor except for the pixel focal plane and the pins, improving the refrigeration efficiency.

[0042] Figure 6 The following shows the flowchart of the method for extending the on-orbit life of an image sensor based on the optimal operating temperature range in an embodiment of the present invention.

[0043] See Figure 6 , the method for extending the on-orbit life of an image sensor based on the optimal operating temperature range in this embodiment includes:

[0044] 1) Using the irradiation ground simulation test to determine the performance degradation degree and the drift of performance parameters of the image sensor under different radiation damage doses;

[0045] The performance parameters are, for example, dark current and full well capacity;

[0046] 2) For the image sensors with different degrees of irradiation damage obtained from the irradiation ground simulation test, determine the temperature at which their performance parameters return to the allowable range before irradiation, and define this temperature as the optimal operating temperature range corresponding to this degree of irradiation damage;

[0047] For an image sensor, the lower the working environmental temperature, the more effectively it can suppress dark current and thermal pixels, reduce the noise and dead pixels in the captured images, and also improve the pixel full well capacity and signal-to-noise ratio. However, the lower the required working environmental temperature, the higher the requirements for the temperature control device of the image sensor, and the higher the power consumption of the temperature control device. Since the overall power supply capacity on a spacecraft is limited, the device cannot always operate at the lowest environmental temperature that the temperature control device can achieve. In addition, there is a boundary diminishing effect in the performance of the image sensor. After the captured images can meet its positioning needs, it is unnecessary to continue to improve the device performance. Therefore, the environmental temperature at which the performance parameters of the image sensor are restored to the pre-irradiation level can be used as the optimal working temperature range for the device in its current irradiated damage state, so as to meet the needs in terms of performance and minimize power consumption.

[0048] By maintaining the consistency of the performance parameters of the image sensor during operation, the consistency of the process of capturing the original images can be ensured, which is beneficial to ensuring the effectiveness of subsequent image processing algorithms.

[0049] 3) Through orbital radiation environment models such as AP8 and AP9, determine the cumulative radiation damage dose during the on-orbit operation time of this orbit.

[0050] 4) According to steps 1) to 3), determine the relationship curve between the on-orbit operation time of this orbit and the optimal working temperature range of the image sensor.

[0051] In this embodiment, the relationship curve between the on-orbit operation time of a certain orbit and the optimal working temperature range of the image sensor is as Figure 7 shown;

[0052] 5) According to the relationship curve between the on-orbit operation time and the optimal working temperature range of the image sensor obtained in step 4), set the working environmental temperature of the image sensor at different on-orbit operation times. Accordingly, adjust the working environmental temperature of the image sensor through the temperature control system to effectively suppress the performance degradation and performance parameter drift of the image sensor caused by the space radiation environment, and realize the correction and recovery of the performance of the image sensor.

[0053] The working environmental temperature of the image sensor at different on-orbit operation times set according to the relationship curve between the on-orbit operation time and the optimal working temperature range of the image sensor is input into the temperature control system in advance. A temperature sensor is installed inside the image sensor to collect the temperature of the image sensor in real time and send it to the temperature control system. The temperature control system uses PID control technology to control the operation of the semiconductor refrigeration chip according to the set working environmental temperature and the actual temperature of the image sensor, so that the temperature of the image sensor is consistent with the set working environmental temperature.

[0054] 6) Compare images through on-orbit calibration at regular intervals to determine the actual performance degradation degree and performance parameter drift of the image sensor. Based on this, further adjust the working environment temperature of the image sensor through the temperature control system to achieve more accurate correction and recovery of the performance parameters of the image sensor;

[0055] The actual performance degradation degree and performance parameter drift of the image sensor can be determined by comparing historical images in the same position and pose based on star maps or ground signs; it can also be determined by comparing historical images based on the on-orbit calibration method of radiometric calibration, and the radiometric calibration is a star with known radiation characteristics or a target with known radiation characteristics;

[0056] If image comparison finds that the performance of the image sensor has degraded, the working environment temperature of the image sensor can be gradually reduced through fine-tuning until the performance parameters of the image sensor are corrected and recovered.

[0057] When the performance of the image sensor decreases due to the space radiation environment, the present invention suppresses the dark current noise in the device by operating at low temperature, improves the signal-to-noise ratio of the acquired images, fully exploits the life potential of the device, realizes on-orbit life extension, and effectively solves the problems of on-orbit performance degradation and shortened life of optical satellites.

[0058] The present invention effectively suppresses the performance degradation of the image sensor through the corresponding low-temperature environment, fully exploits the performance of the device itself, realizes on-orbit life extension of the spacecraft, improves mission reliability, reduces maintenance costs, adapts to extreme environments, and supports long-term missions, thereby ensuring the continuous and stable operation of the spacecraft in the space environment and providing stronger support for deep space exploration and long-term on-orbit missions.

Claims

1. An on-orbit life extension device for an image sensor based on the optimal operating temperature range, characterized in that, It includes a temperature control system, an image sensor drive board, a thermoelectric cooler, a thermal conductive silicone pad, and a camera cover plate; The thermal conductive silicone pad is arranged between the thermoelectric cooler and the image sensor. The thermal conductive silicone pad is closely attached to the surface of the image sensor, and the thermoelectric cooler is closely attached to the thermal conductive silicone pad; The thermoelectric cooler is connected to the temperature control system and the image sensor drive board through a control line; The image sensor is connected to the temperature control system and the image sensor drive board through pins; The image sensor is placed on the camera cover plate, and the temperature control system and the image sensor drive board are fixedly connected to the camera cover plate.

2. The on-orbit life extension device for an image sensor based on the optimal operating temperature range according to claim 1, wherein The thermal conductive silicone pad is closely attached to the area of the surface of the image sensor where the pins are arranged except for the pins and the side surface of the image sensor.

3. The on-orbit life extension device for an image sensor based on the optimal operating temperature range according to claim 2, wherein The thermoelectric cooler is in a shape of a Chinese character 'Ri' and is closely attached to the area of the surface of the image sensor where the pins are arranged except for the pins and the side surface of the image sensor.

4. The on-orbit life extension device for an image sensor based on the optimal operating temperature range according to claim 1, characterized in that The temperature control system in the temperature control system and the power supply drive board uses PID control technology to control the operation of the thermoelectric cooler, so that the image sensor works in the optimal operating temperature range.

5. An on-orbit life extension method for an image sensor based on the optimal operating temperature range, characterized in that An in-orbit life extension device for an image sensor based on the optimal operating temperature range as described in any one of claims 1 to 4 is adopted; the method includes: 1) Using a ground simulation test of irradiation to determine the performance degradation degree and the drift of performance parameters of the image sensor under different radiation damage doses; 2) For the image sensors with different degrees of irradiation damage obtained from the ground simulation test of irradiation, determine the temperature at which its performance parameters return to the allowable range before irradiation, and set this temperature as the optimal operating temperature range corresponding to this degree of irradiation damage; 3) Determine the cumulative situation of the radiation damage dose during the in-orbit operation time of this orbit through an orbital radiation environment model; 4) According to steps 1) to 3), determine the relationship curve between the in-orbit operation time of this orbit and the optimal operating temperature range of the image sensor; 5) According to the relationship curve between the in-orbit operation time and the optimal operating temperature range of the image sensor obtained in step 4), set the working environment temperature of the image sensor under different in-orbit operation times, and accordingly adjust the working environment temperature of the image sensor through the temperature control system, effectively suppressing the performance degradation and the drift of performance parameters of the image sensor caused by the space irradiation environment, and realizing the correction and recovery of the performance of the image sensor; 6) Conduct image comparison through in-orbit calibration at regular intervals to determine the actual performance degradation degree and the drift of performance parameters of the image sensor, and accordingly further adjust the working environment temperature of the image sensor through the temperature control system to realize more accurate correction and recovery of the performance parameters of the image sensor.

6. The method for on-orbit life extension of an image sensor based on the optimal operating temperature range according to claim 5, wherein The performance parameters include dark current and full well capacity.

7. The method for on-orbit life extension of an image sensor based on the optimal operating temperature range according to claim 5, wherein In step 2), by maintaining the consistency of the performance parameters of the image sensor during operation, the consistency of the process of collecting original images can be ensured, which is beneficial to ensuring the effectiveness of subsequent image processing algorithms.

8. The method for on-orbit life extension of an image sensor based on the optimal operating temperature range according to claim 5, wherein In step 5), the operating ambient temperature of the image sensor at different on-orbit operating times set according to the relationship curve between the on-orbit operating time and the optimal operating temperature range of the image sensor is input into the temperature control system in advance; a temperature sensor is installed inside the image sensor to collect the temperature of the image sensor in real time and send it to the temperature control system. The temperature control system uses PID control technology to control the operation of the semiconductor refrigeration chip based on the set operating ambient temperature and the actual temperature of the image sensor, so that the temperature of the image sensor is consistent with the set operating ambient temperature.

9. The method for on-orbit life extension of an image sensor based on the optimal operating temperature range according to claim 5, wherein In step 6), if it is found through image comparison that the performance of the image sensor has degraded, the operating ambient temperature of the image sensor is gradually reduced through fine-tuning until the performance parameters of the image sensor are corrected and restored.

10. The method for on-orbit life extension of an image sensor based on the optimal operating temperature range as claimed in claim 5, wherein In step 6), based on the star map or ground signs, the actual performance degradation degree and performance parameter drift of the image sensor are determined through comparison of historical images in the same position and posture. Or, based on the on-orbit calibration method of radiometric calibration, historical images are compared to determine the actual performance degradation degree and performance parameter drift of the image sensor.

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