KR-20260065492-A - Blackbody system for calibration of thermal imaging cameras

KR20260065492AKR 20260065492 AKR20260065492 AKR 20260065492AKR-20260065492-A

Abstract

A black body system (100) for correcting a thermal imaging camera according to one embodiment of the present invention comprises a lower body plate (2), a front support (3), a heat block plate (4), a black body source (5), an electric module (6), a heat sink (7), a fan cover (8), a PWM DC fan (9), an upper cover (10), a handle (11), a rear cover (12), an air duct (13), a terminal block (14), and a temperature sensor (15). The PWM DC fan (9) is operated in a PID control manner and is characterized by operating to vary the speed of the fan in proportion to the radiant heat of the black body source (5).

Inventors

정승부

Assignees

정승부

Dates

Publication Date: 20260508
Application Date: 20250814
Priority Date: 20241101

Claims (8)

Plate-shaped lower body plate; A front support member in the form of a frame, which is erected and installed on the front of the lower body plate and has an opening; A frame-shaped heat block plate having an opening, which is installed upright on the front of the lower body plate and positioned on the rear of the front support member; A plate-shaped black body source coupled to the rear surface of the heat block plate to block the opening of the heat block plate; A plurality of electric modules coupled to the rear of the blackbody source to control the temperature of the blackbody source; A heat sink coupled to the rear of the above electric module; An upper cover installed parallel to the lower body plate on the upper part of the heat block plate; and A blackbody system for correcting a thermal imaging camera, comprising a rear cover installed upright on the rear of the lower body plate and the upper cover and spaced apart from the heat sink.
In paragraph 1, A blackbody system for thermal imaging camera correction, wherein the blackbody source is exposed to the outside through the opening of the front support and the opening of the thermal block plate.
In paragraph 1, A fan cover installed between the heat sink and the rear cover; and A blackbody system for thermal imaging camera calibration, further comprising a plurality of PWM DC fans installed on the fan cover.
In paragraph 3, Air duct installed on the rear cover above; A terminal block that provides power to the above electric module; and A blackbody system for thermal imaging camera calibration, further comprising a temperature sensor for sensing the temperature of the blackbody source.
In paragraph 1, The above blackbody source is made of a material with an emissivity of 1 and radiates heat to provide a reference temperature required for thermal imaging camera calibration, a blackbody system for thermal imaging camera calibration.
In paragraph 1, The above electric module is a blackbody system for thermal imaging camera correction that uses a Peltier element to heat or cool the blackbody source to precisely control the temperature.
In paragraph 3, A blackbody system for thermal imaging camera calibration, wherein the above-mentioned PWM DC fan operates using a PID control method and the fan speed is automatically adjusted in proportion to the radiant heat of the above-mentioned blackbody source.
In paragraph 4, A blackbody system for thermal imaging camera correction, wherein the temperature sensor includes an RTD sensor to measure the temperature of the blackbody source, automatically adjusts the temperature data through an automatic tuning function, and reduces the temperature error by setting a compensation value for each temperature range.

Description

Blackbody system for calibration of thermal imaging cameras The present invention relates to a black body system for correcting a thermal imaging camera. Conventionally, a black body source (10) as shown in FIG. 1 has been used to test a thermal imaging camera and perform temperature correction. A black body source is an object that emits nearly 100% of its energy, as its emissivity is approximately 1. Inside the thermal camera (20), there is a detector (30) that detects the black body source (10). The detector (30) is a sensor array composed of numerous detection sensors; for example, one detector is a sensor array consisting of 320 sensors in the width × 240 sensors in the height, i.e., 76,800 sensors, and such an array is commonly called a Focal Plane Array (FPA). However, each sensor constituting the sensor array exhibits slight variations in performance due to errors in the manufacturing process and other factors. In particular, thermal detectors show a very significant phenomenon (non-uniformity in performance); the performance differences between sensors are so great that when actual electronic circuits are constructed to display images, the resulting images are almost unrecognizable. In order to achieve nearly constant performance through a process of prior compensation and correction of these characteristics, equipment is required to compensate for the differing performance of each sensor in a thermal imaging camera using ambient temperature and the temperature of a blackbody source. Figure 2 schematically illustrates an example of the performance characteristics exhibited by each sensor of the sensor array according to the temperature rise. In the graph of Figure 2, the vertical axis of the coordinates represents gain and the horizontal axis represents time, and as an example, a gain graph for three sensors is shown. As time passes and the temperature rises, the gain of the sensor increases, but as shown, the response to the temperature increase is not uniform across all sensors and each sensor responds slightly differently. Therefore, it is necessary to make corrections for all sensors constituting the sensor array so that all sensors have a consistent value at a specific temperature, and to do this, each sensor must be temperature corrected so that, for example, at time t1 (i.e. at a specific temperature corresponding to time t1), all sensors have a specific value (P). However, while it would be ideal if this temperature compensation could be completed in a single step, the reality is different. This is because sensor performance variations differ not only depending on the temperature of the blackbody source but also on the ambient temperature. In other words, each sensor exhibits different nonlinearities depending on the ambient temperature of the thermal camera and the temperature of the blackbody source. Therefore, to actually test a thermal imaging camera, the camera must be tested while continuously varying the blackbody source temperature and the ambient temperature. For example, the ambient temperature is set to 10 degrees, and the blackbody source temperature is continuously increased to 0 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, etc., and a thermal image of the blackbody source at each temperature is captured with a thermal camera. Then, the ambient temperature is raised to 20 degrees, and the thermal camera is tested again by continuously increasing the blackbody source temperature to 0 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, etc. Then, the ambient temperature is raised to 30 degrees, and the thermal camera is tested again by continuously increasing the blackbody source temperature from 0 degrees. This process must be repeated whenever the ambient temperature reaches 40 degrees, 50 degrees, etc. However, the problem with this test is that the stabilization time for the blackbody source is quite long. The purpose of the blackbody source is to obtain reference values for the thermal camera, so if the temperature accuracy of the blackbody source decreases, the accuracy of the thermal camera also decreases. Accordingly, the accuracy of the blackbody source is preferably within 10 mK, more preferably within 1 mK, and even more preferably within 0.1 mK. Of course, the temperature stability of the blackbody source is required to have an accuracy approximately 10 times greater than the basic performance, i.e., the temperature resolution, of the detector of the camera. For example, if the temperature resolution of the detector (30) is, say, 100 mK, the temperature of the blackbody source can be stabilized within the range where the accuracy of the blackbody source is 10 mK, but if the temperature resolution of the detector (30) is, say, 10 mK, the temperature of the blackbody source must be stabilized with a higher accuracy, i.e., an accuracy of 1 mK. However, when increasing the blackbody source temperature from 10 degrees to 20 degrees for testing a thermal im