KR102236109B1 - black body system for calibration of infrared detector installed on satellite - Google Patents

Abstract

Disclosed is a black body system for calibration of an infrared sensor installed on a satellite. The black body system comprises a black body unit and a thermal control unit. A thermoelectric element is installed between one side of a black body or a black body module and one side of a heat pipe of the thermal control unit. The low-temperature point of the thermoelectric element is brought into thermal contact with the black body. The high-temperature point of the thermoelectric element is brought into thermal contact with the heat pipe. Thus, the black body can be operated at the temperature lower than the temperature of the radiator of the thermal control unit. According to the present invention, the temperature of the surface of the black body can be adjusted to the temperature lower than the temperature of an existing radiator, and thus it can be checked whether the infrared sensor has an abnormality in a temperature range wider than an existing one, and the infrared sensor can be calibrated. Therefore, the black body system can ensure the accuracy of the infrared sensor in the wider temperature range and can obtain a higher-quality image in securing an image by using the infrared sensor.

Description

Black body system for calibration of infrared detector installed on satellite

The present invention relates to a blackbody system for calibrating an infrared sensor, and more particularly, it is installed on a satellite to enable calibration work to ensure the accuracy of an infrared sensor installed on a satellite, and overcomes the limitations of the existing temperature information provision range and installs stability. It relates to a blackbody system that can increase the.

In the satellite electrooptic-infrared (EO/IR) payload, high-performance IR (infrared) optical sensors (hereinafter simply referred to as "infrared rays") for night photography are applied. In the infrared sensor, the sensor output characteristics change for the same radiant energy during the mission period, which directly affects the image quality deterioration.

Therefore, in order to obtain a high-quality image of an infrared sensor, periodic calibration of the sensor is required, and a blackbody system that provides both a light source and a temperature standard is applied to the payload as a device for calibrating such infrared sensor output characteristics.

The blackbody system is an infrared sensor calibration device that provides a precise blackbody surface and temperature reference with radiation efficiency close to 100%, and this blackbody system must provide the required temperature range required for infrared sensor calibration for calibration.

1 shows a blackbody system according to the prior art (Korean Patent Application No. 10-2019-0042915).

Referring to FIG. 1, in the blackbody system according to the prior art, a blackbody unit 100 and a heat control unit 200 may be assembled and configured, and there is a column at the rear of the blackbody unit 100 that provides a reference value to the infrared sensor. The control unit 200 is disposed, so that when mounted on a satellite, calibration work for securing the accuracy of the infrared sensor is made possible. The blackbody unit 100 includes a blackbody module 130, a support segment 140, a baffle 110, a first flange 120 and a second flange 150.

The blackbody module 130 is generally formed in a dumbbell shape. On one side, the black body 131 is disposed so as to face the front surface of the infrared sensor to radiate infrared rays that change according to temperature changes to the front surface. In addition, a rod-shaped heat sink 132 is coupled to the rear surface of the black body 131 in a standing state, and a connection plate 133 on the other side of the heat sink 132 is formed on the other side.

In such a blackbody system according to the prior art, the temperature range in which the surface temperature of the blackbody can be lowered is determined according to the lowered temperature of the radiator and the radiant heat inside the payload. On the other hand, there is a temperature range in which the radiator can be lowered depending on the storage temperature, operating temperature, and optical interference inside the payload. Therefore, the blackbody surface temperature can only be higher than the lowerable temperature of the radiator, and in the temperature range below this temperature, it is impossible to accurately check and correct whether the function of the infrared sensor is operating normally.

In addition, in the prior art, the length of the heat pipe and the shape of the pipe are determined according to the position of the blackbody unit and the position of the radiator to be mounted on the outer panel of the payload. Heat pipes with longer lengths act as structural weaknesses and cause many problems when exposed to thermal elasticity, launch vibration, and shock environments as they go through a wide temperature range that includes high and low temperatures due to extreme launch environments and space operating environments. It can be, and a lot of difficulties come when designing to alleviate these problems.

More specifically, for example, the heat pipe may be formed to extend a considerable length compared to its diameter due to surrounding circumstances, but it is not affected by factors such as vibration, shock, and thermal elasticity according to a wide temperature range in the launch environment and space environment. As a result, it has a problem that installation stability, durability, and operation reliability with the elements it encounters are liable to be deteriorated.

In addition, the overall blackbody system is sensitive to heat, so it has a structural limitation that it is difficult to casing, so that the components are easy to be installed on the satellite as it is without any special protective equipment. For this reason, installing a blackbody system on a satellite was a tricky task requiring a number of mechanical and mechanical engineers to perform precise assembly and installation in the presence of experts of the blackbody system.

Korean Patent Application No. 10-2019-0042915 Korean Patent Registration No. 10-1702433

The present invention has been conceived to solve the problems of the conventional blackbody system as described above, and an object of the present invention is to provide a blackbody system that enables calibration work for securing the accuracy of a satellite-mounted infrared sensor in a maximum temperature range. .

The present invention is to provide a blackbody system capable of checking and calibrating the accuracy of an infrared sensor even in a lower temperature range by lowering the temperature of the blackbody surface below the lowerable temperature of a radiator provided in a thermal control unit thermally connected thereto. The purpose.

An object of the present invention is to provide a blackbody system capable of providing various temperature information and accurate temperature calibration by increasing the radiation efficiency on the surface of a blackbody to close to 1 in general, and providing a temperature sensor on the rear surface.

According to an aspect of the present invention, it is an object of the present invention to provide a blackbody system having a means for minimizing heat loss due to the radiator when the blackbody is not operated depending on the situation in the middle of a blackbody unit with a heater installed on one side and a heat control unit. It is done.

In addition, according to another aspect of the present invention, the present invention has a configuration capable of securing a stable function and increasing durability by supplementing parts that are susceptible to thermal elasticity, shock, and vibration in a blackbody system in which a plurality of parts are thermally connected. It aims to provide a blackbody system.

In order to achieve the above object, the present invention provides a blackbody system for calibrating an infrared sensor mounted on a satellite comprising a blackbody unit and a heat control unit. The element is installed and the low temperature point of the thermoelectric element is in thermal contact with the black body (hereinafter, it will be interpreted in a broader sense including the black body module), and the high temperature point of the thermoelectric element is in thermal contact with the heat pipe so that the black body is a thermal control unit. It is characterized in that it can be operated at a lower temperature than that of the radiator.

The present invention may be provided with an additional heat control element capable of controlling the heat flow between the black body and the heat control unit by being installed around the thermoelectric element itself or the thermoelectric element.

In the present invention, the heat control unit may be configured such that at least one of the intermediate portions of the heat pipe formed longer than the width is supported by a support structure installed inside the satellite or on the payload.

According to the present invention, since the temperature of the blackbody surface can be operated at a temperature equal to or lower than the conventional radiator (heat sink), it is possible to check and correct the error of the infrared sensor in a wider temperature range than before. Accordingly, compared to the conventional blackbody system, accuracy of the infrared sensor can be secured in a wider temperature range in terms of low temperature, and higher quality images can be obtained when securing an image using the infrared sensor as a whole.

In addition, according to an aspect of the present invention, in the conventional blackbody system, a lot of constant power was used to maintain the temperature to prevent optical interference of the module inside the payload due to the low temperature of the blackbody radiation surface. By arranging a thermoelectric element with high thermal resistance between them and using a heater installed on one side of the black body, it is possible to reduce heater heat loss and minimize heater power consumption when temperature information is not provided in relation to the thermoelectric element operation unit. It is done.

In addition, according to another aspect of the present invention, by supporting the middle of the heat pipe formed thin and long by other elements in the heat control unit through a separate support structure, the installation stability is increased throughout the blackbody system, and the heat pipe and this It is possible to suppress the damage or deterioration of the function of the coupling structure between the connected surrounding elements under the influence of vibration, shock, and thermal expansion applied thereto.

1 is a perspective view showing an example of a conventional blackbody system;
2 is a perspective view showing an embodiment of the blackbody system of the present invention;
3 is a perspective view showing an embodiment of the blackbody system of the present invention as viewed from the other side;
4 is a cross-sectional view showing a side cross-sectional view of a blackbody unit according to an embodiment of the blackbody system of the present invention.

Hereinafter, the present invention will be described in more detail through specific examples with reference to the drawings.

2 and 3, the blackbody system of the present invention largely includes a blackbody unit and a heat control unit.

Fig. 4 is a side cross-sectional view showing a coupling relationship between each element constituting a blackbody unit and a thermoelectric element coupled to the blackbody unit and a pressing plate.

Referring to FIG. 4 together, the blackbody unit includes a blackbody 330 in an approximately circular plate shape, a blackbody heater 340 installed on the side of the blackbody, and these blackbody 330 and the blackbody heater 340 around the side. A flange 320 is installed to be wrapped around and fixed to the black body, and a cylindrical baffle 310 is installed to extend forward on the flange 320 and installed to surround the front of the radiating surface of the black body. A connector 370 for fixing the blackbody unit in the satellite may be installed on one side of the flange 320.

The blackbody 330 is disposed so that its front surface faces the infrared sensor installed on the satellite, and radiates infrared rays that change according to temperature changes toward the infrared sensor toward the front surface. The front surface of the blackbody can be coated and painted with a high emissivity to obtain a radiation efficiency close to 1 required for calibration work of an infrared sensor, and can be processed into a concentric groove shape.

The blackbody heater 340 heats the blackbody to make the surface of the blackbody a desired temperature from low temperature to high temperature when calibrating the infrared sensor. The heater heats the blackbody and makes the blackbody's temperature higher than the satellite's internal temperature. Therefore, it is possible to correct the relationship between the amount of infrared radiation emitted from the black body heated to the reference temperature range and the amount of infrared radiation actually detected at that temperature. Here, it is shown that the black heater is installed on the side of the black body, but it is also possible to install the heater on the rear surface of the black body. However, at this time, since the thermoelectric element is installed on the rear surface of the black body, it is preferable to set the heater and the thermoelectric element so that there is no conflict in consideration of the mutual relationship between the thermoelectric element and the heater.

In addition to the simple circular plate shape, the blackbody 330 may be a dumbbell-shaped blackbody module or another type of blackbody module in which a rod-shaped heat sink is installed in the middle and a connection plate connected to the heat sink is installed in the middle. May be. In this case, the connection plate may have a shape and configuration capable of increasing thermal contact efficiency with the thermoelectric element, facilitating thermal contact coupling, and may have a separate connector means. However, here, a simple circular plate type is adopted to reduce the thermal resistance and increase the heat transfer effect with the thermoelectric element. However, by increasing the heat capacity by making the circular plate slightly thicker, the entire radiation surface can radiate infrared rays at a uniform temperature even when heated by the surrounding heater, and the temperature change rate by the thermoelectric element can be buffered and controlled. It is desirable.

In addition, a plurality of temperature sensors (not shown) may be attached to the black body 330 based on the center on the rear surface of the black body so as to simulate the temperature and temperature distribution of the radiating surface. It is preferable that the temperature sensor is arranged regularly at regular intervals in the radial direction at a location that varies from the center to the center. The installation of such a temperature sensor can be made to provide precise temperature information according to an error in the calibration and measurement equipment of the infrared sensor.

Preferably, the temperature sensor is composed of a first temperature sensor and a second temperature sensor attached to different radii along a concentric circle of the rear surface of the black body, and the temperature measurement value of the first temperature sensor and the second temperature sensor is applied. It may be configured to calibrate the entire temperature of the rear surface of the blackbody to a representative temperature by applying a weight.

In order to prevent heat from leaking from the black body 330 to the periphery, a heat insulating member 325 is preferably used between the side of the black body and the flange 320 on the outside thereof.

On the rear surface of the black body, a thermoelectric element (Peltier element: 350) constituting a characteristic part of the present invention is installed in an approximately circular plate shape.

In order to stably install the thermoelectric element 350, a thermoelectric element support segment may be used. In this case, the support segment may be coupled to the flange 320 through a coupling means such as a screw. However, when the coupling means is used, heat leaks from the thermoelectric element 350 to the flange 320 by using an insulation shim (shim 365) with thermal insulation and buffering properties, and external shocks and vibrations are transmitted to the thermoelectric element. It is desirable to suppress it.

In the thermoelectric element 350, a heat resistance layer having an insulating property and low thermal conductivity is interposed between the front side of the thermoelectric element 350 in contact with the rear surface of the black body 330 and the rear side of the opposite side thereof. These sides are made of different materials selected to form a thermoelectric element, and when direct current flows through two connecting portions electrically connecting these two sides, one side forms a high temperature side and the other side forms a low temperature side. To form a thermoelectric element, the two connecting portions may be made of different thermoelectric element materials, such as an n-type semiconductor and a p-type semiconductor material, and one side is electrically separated between the two connecting portions to allow direct current to flow. Since the configuration of such a thermoelectric element is well known in the art, further detailed description will be omitted.

One side of the thermal control unit can be used as a medium for transferring heat by contacting the rear side of the thermoelectric element 350, and the pressing plate 360 serves to press the thermoelectric element to the rear surface of the black body, and one side is attached to the pressing plate 360. A heat pipe 380 that is connected and the other side is connected to the radiator side, and a radiator that discharges heat received from the heat pipe 380 to the outside is provided.

The pressing plate 360 may form a plurality of screw connections between the flange 320 of the blackbody unit and the peripheral portion in order to press the thermoelectric element 350 to the rear surface of the blackbody. At this time, in order to prevent the heat of the pressing plate 360 in thermal contact with the thermoelectric element and the heat pipe 380 from leaking to the flange 320, a double structure of an insulating shim (365) may be employed in the screw connection. have.

Even if the pressing plate closes the thermoelectric element to the rear surface of the black body by screwing, these elements are formed as separate elements and are in contact with the surface. In order to increase the heat conduction efficiency of the contact surface, these contact surfaces have a liquid heat medium or thermal conductivity. Other ductile heat medium or connection plates that are excellent and can increase the effective contact area with each element may be provided.

Here, the radiator is a heat dissipation flange 390 that is widely formed to handle heat dissipation to the outside while in contact with the heat pipe 380 on the one hand, a radiator heater 400 installed on the heat dissipation flange 390, and a connector for installing the radiator. It can be made with 410.

Since the heat pipe 380 is formed to have a very long length compared to the width or diameter, structurally, it may be vulnerable to the force exerted on the connection structure due to vibration, shock from external force, and thermal expansion, so here the heat pipe is supported in the middle position of the heat pipe. A separate support structure 500 is provided for this. In addition, in order to ensure the stability of the function of the heat pipe 380, it is preferable to install a plurality of heat pipes in parallel in case one heat pipe has a problem.

The support structure 500 may be installed on a satellite body or a satellite mount other than the blackbody system. Of course, the blackbody unit and the thermal control unit can also be installed on a satellite or satellite mount through connectors installed on each. In this configuration, since both ends of the heat pipe are fixed to the pressing plate 360 and the heat dissipation flange 390 of the radiator, the intermediate portion thereof is fixed and supported by the support structure 500, so that it resists shock, vibration, and thermal expansion caused by external force. Thus, it can be stably fixed and supported, and thus can perform a given function stably.

Looking at the process of performing the infrared sensor inspection in this embodiment, when it is necessary to operate the black body at a temperature below the temperature of the radiator, the side of the thermoelectric element in contact with the rear surface of the black body by flowing a direct current to the thermoelectric element is the low-temperature side or the heat absorbing surface. And the opposite side of the thermoelectric element is the high temperature side or the heating side. By adjusting the amount of direct current, the temperature of the blackbody can be controlled within the temperature range below the radiator temperature. At this time, heat from the heating surface of the thermoelectric element may be transferred to the radiator of the radiator through the pressing plate and the heat pipe when a heat pipe is used to radiate heat to the outside. Therefore, it is possible to prevent the heat of the thermoelectric element from affecting the low temperature side of the thermoelectric element. A non-conductive material with high heat resistance and high electrical resistance is installed between the heating surface and the heat absorbing surface of the thermoelectric element, so that the heat of the heating surface also increases the temperature of the black body radiating surface, lowers the black body cooling efficiency of the thermoelectric element, and provides more for cooling. It can suppress the use of electric energy.

When performing inspection and calibration of the infrared sensor in the range above the minimum temperature of the radiator, the temperature of the blackbody radiating surface can be adjusted by appropriately using the heater of the blackbody unit.

The temperature of the blackbody radiating surface is measured using a temperature sensor on the rear of the blackbody, and the result is fed back with a controller that supplies electricity to a heater or thermoelectric element to properly adjust the temperature on the low-temperature side of the heater or thermoelectric element. You can adjust the temperature.

When operating a thermoelectric element between the blackbody unit and the thermal control unit, it operates as a thermoelectric element by passing current to the thermoelectric element by providing temperature information from the blackbody temperature sensor. When the temperature is raised, the heat resistance of the heat resistance body between the heating side (heating part) and the heat absorbing side (cooling part) of the thermoelectric element is used to suppress the heat from escaping from the black body to the radiator through the heat pipe and attached to the side of the black body. Heater can be controlled to increase thermal efficiency by maintaining the temperature of the blackbody radiating surface with minimum power.

On the other hand, if there is a separate support structure at an intermediate position in addition to both ends of the heat pipe as in this sealing example, it is less necessary to secure the rigidity of the structure supported at both ends as compared to the case without the support structure. Therefore, for example, when designing the configuration from the connection member of the heat pipe to be coupled with the presser plate to the heat sink of the radiator, the design of relatively low rigidity is possible to reduce the design difficulty, and the design of the maze shape to avoid thermal elasticity applied to the connection is possible. It is possible, and it is possible to reduce the cost of manufacturing and maintenance according to the wide range of member selection.

The low rigidity of the support structure at both ends gives room to adopt a support structure with excellent buffering properties instead of a support structure with high rigidity. It may be possible to minimize the direct impact.

Although described above with reference to the illustrated embodiment of the present invention, this is only exemplary, and various modifications may be made therefrom by those of ordinary skill in the art, and all or part of the above-described embodiments. It will be appreciated that may be optionally combined and configured. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

310: baffle 320: flange
325: heat insulation member 330: black body
340: blackbody heater 350: thermoelectric element
360: pressure plate 365: insulation shim
370, 410: connector 380: heat pipe
390: heat dissipation flange 400: radiator heater
500: support structure

Claims (4)

In the satellite-mounted infrared sensor calibration blackbody system comprising a blackbody unit and a thermal control unit,
A thermoelectric element is installed between one side of the blackbody of the blackbody unit and one side of the heat pipe of the thermal control unit, and the low temperature side of the thermoelectric element is in thermal contact with the blackbody, and the high temperature side of the thermoelectric element is connected to the heat pipe. The black body is made to operate at a lower temperature than the radiator of the heat control unit by making it in thermal contact with,
An additional heat control element is provided that is installed around the thermoelectric element itself or around the thermoelectric element to control heat flow between the blackbody and the heat control unit,
The additional thermal control element is a black body system for calibrating an infrared sensor mounted on a satellite, characterized in that the thermal resistance body is installed between the low temperature side and the high temperature side of the thermoelectric element. delete delete The method of claim 1,
A blackbody system for calibrating an infrared sensor mounted on a satellite, further comprising a support structure installed inside a satellite or on a satellite mount to support at least one of the heat pipes of the heat control unit.

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