JP2009246731A - Pixel correcting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the miniaturization of a thermal imagery camera by a method without accommodating a pixel correcting device. <P>SOLUTION: The pixel correcting device for the thermal imagery camera includes: a detachable uniform heater plate which covers the lens of the thermal imagery camera; a mounting unit provided on the uniform heater plate and the main body of the thermal imagery camera in order to mount the uniform heater plate on the thermal imagery camera body; a temperature sensor provided so as to be in contact with the uniform heater plate or in the vicinity of the same to measure the temperature of the uniform heater plate; a converting unit for converting each of the temperature information measured by respective pixels of the infrared lay imaging element and the temperature information of the uniform heater plate measured by the temperature sensor into digital amounts; and an operating unit positioned in the thermal imagery camera body to convert the digital amounts into the measuring temperature of respective pixels and the measuring temperature of the uniform thermal plate, thereafter to obtain a difference between the measuring temperatures of respective pixels and the measuring temperature of the uniform thermal plate, and to calculate a correction coefficient necessary for the correction of the pixel having varieties in sensitivity based on the difference to perform correction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to pixel correction for a small thermal image camera.

  Regarding a thermal image camera using an infrared imaging device, a thermal image displayed as a measurement result is composed of measurement temperatures of a large number of imaging pixels. In theory, if an object having the same temperature is displayed, all pixels have a uniform measurement temperature. However, because pixels with varying sensitivity are mixed in this pixel, even when measuring an object with the same temperature, a difference occurs in the measured temperature of each pixel, resulting in a decrease in the accuracy of the thermal image. To do. For this reason, it has been conventionally performed to correct an error between the measured temperature measured on the soaking plate and the measured temperature of each pixel by calculation.

  As this method, for example, a shutter that can be opened and closed instantaneously at the position of the aperture stop of the optical system and a temperature sensor that measures the temperature of the shutter are provided. As the shutter used here, a lens shutter common in the photographic industry can be diverted.

JP-A-10-115557 (page 4)

  However, in the thermal image camera described above, the shutter and the mechanism for controlling opening and closing thereof are installed in the thermal image camera body. In a small thermal image camera, storing a shutter serving as a soaking plate in the main body hinders downsizing of the camera and increases costs.

  An object of the present invention is to solve the problem of such a conventional configuration, and to achieve pixel correction by a heat equalizing plate easily and inexpensively even in a small thermal image camera. It is what.

  In order to achieve the above-described object, the pixel correction apparatus for a small thermal image camera according to claim 1 is detachable to cover the lens of the thermal image camera in the pixel correction apparatus for a thermal image camera using an infrared imaging device. In order to attach the soaking plate and the soaking plate to the thermal image camera body, the soaking plate and the mounting portion provided on the thermal imaging camera body, and in contact with or near the soaking plate A temperature sensor that measures the temperature of the heat equalizing plate, temperature information measured by each pixel of the infrared imaging device, and the temperature equalizing plate measured by the temperature sensor. After converting the temperature information into digital quantities, respectively, in the thermal image camera body, similarly to the conversion unit for converting the digital information, the digital quantities are calculated into the measurement temperature of each pixel and the measurement temperature of the soaking plate, Each pixel And a calculation unit for calculating a correction coefficient necessary for correcting a pixel having a variation in sensitivity based on the difference between the measurement temperature and the measurement temperature of the heat equalizing plate, and performing correction. To do.

  According to the present invention, since the heat equalizing plate is manually detachable without being housed in the thermal image camera body, the thermal image camera can be downsized and a complicated mechanism can be omitted. Can do.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic side sectional view of a thermal image camera employing a pixel correction apparatus according to the present invention, FIG. 2 (a) is a schematic enlarged sectional view of a temperature sensor and a conversion unit, and FIG. 2 (b) is a temperature sensor. FIG. 3 is a schematic enlarged cross-sectional view when the converter and the converter are electrically connected, FIG. 3 is a flow chart in which temperature information is processed in the calculator, and FIG. 4 is another embodiment of the present invention.

First, based on FIG. 1, a schematic side sectional view of a thermal image camera employing a pixel correction apparatus according to the present invention will be described. A heat equalizing plate 1 that is a black body and is a reference heat source for correction includes a mounting portion 2 at the periphery thereof. This mounting portion is composed of, for example, a cylinder 2a, a locking projection 2b, and a locking recess 2c. The cylinder 2a is provided on the peripheral edge of the heat equalizing plate 1, and a locking projection 2b is fixed to at least one point of the cylinder 2a. On the other hand, the locking recess 2c is provided at a position corresponding to the locking projection 2b of the thermal image camera body 3, and the heat equalizing plate 1 has the locking projection 2b inserted into the locking recess 2c. Thus, the thermal imaging camera body 3 is mounted while covering the lens 4.
A temperature measuring unit of a temperature sensor 5 such as a thermistor for measuring the temperature of the soaking plate 1 is built in or near the soaking plate 1. In the thermal image camera body 3, a conversion unit 6 is provided for receiving the temperature information of the soaking plate 1 measured by the temperature sensor 5 and converting the temperature information, which is an electrical signal, into a digital quantity. . The digital amount converted by the conversion unit 6 is transmitted to the calculation unit 7, where the measured temperature is calculated based on the digital amount. On the other hand, temperature information, which is an electrical signal measured by each pixel of an FPA (Focal Plane Array) 8, is similarly converted into a digital quantity by the converter 6, and the measured temperature is calculated by the calculator 7 based on this digital quantity. . In the calculation unit 7, the measured temperature of each pixel is compared with the measured temperature of the soaking plate 1.

  Next, based on FIG. 2, the case where the temperature sensor 5, the conversion part 6, and both are electrically connected is demonstrated. As shown in FIG. 2A and the temperature sensor 5, the temperature sensor 5 is disposed in or near the heat equalizing plate 1, and transmits temperature information of the heat equalizing plate 1 to the thermal image camera body 3. The transmission part 5a extends outside from the end of the locking projection 2b. Here, the soaking plate 1 is installed so as to completely cover the lens 4 provided in the thermal image camera body 3 as described above. At this time, as shown in FIG. 2 (b), positioning is performed so that the locking projection 2 b and the transmission portion 5 a are inserted into the locking recess 2 c and the conversion unit 6 provided in the thermal image camera body 3. When the transmission unit 5a is inserted into the conversion unit 6, the temperature information of the soaking plate 1 is converted into a digital quantity, and then transmitted to the calculation unit 7 provided inside the thermal image camera body 3 via the wiring 9a. Is done.

Next, based on FIG. 3, how each pixel is corrected will be described based on a flowchart. When imaging is performed with the soaking plate 1 covering the lens 4 (S301), since the temperature of the soaking plate 1 is constant, each pixel in the FPA 8 should have the same measurement temperature. However, in reality, there are pixels with variations in sensitivity, and the measurement temperature is not always the same. Therefore, first, the digital information converted by the conversion unit 6 as temperature information measured by each pixel is transmitted to the calculation unit 7 via the wiring 9b (S302).
On the other hand, the temperature sensor 5 measures the temperature of the soaking plate 1. Since the temperature information measured here is an electrical signal, it is converted into a digital quantity by the converter 6 (S303). This digital quantity is transmitted to the arithmetic unit 7 through the wiring 9a (S304). As a result, the calculation unit 7 receives the digital amount of the temperature information of each pixel and the digital information of the temperature information of the soaking plate 1 and calculates the two digital amounts to derive the measured temperature. (S305).

When the calculation unit 7 calculates the measurement temperature of each pixel and the measurement temperature of the soaking plate 1, the calculation unit 7 compares the measurement temperature of each pixel with the measurement temperature of the soaking plate 1. A correction coefficient for matching the two temperatures is calculated (S305).
For example, in the case of a normal pixel, if the measured temperature of the soaking plate 1 is 20 degrees, the measured temperature of each pixel is also 20 degrees, and the correction coefficient is derived as 1. However, in a pixel having a variation in sensitivity, for example, even if the measurement temperature of the soaking plate 1 is 20 degrees, the measurement temperature of the pixel may show 25 degrees, for example. In such a case, a correction coefficient is obtained so that a measurement object whose surface temperature is 20 degrees is accurately measured as 20 degrees during actual measurement. Further, for example, the same applies to the case where the measurement temperature of a pixel having a variation in sensitivity indicates 16 degrees. The correction coefficient derived in this way is stored in the storage device (S306), and the pixel is corrected by correcting the measurement temperature of each pixel in the FPA 8 at the next measurement target imaging (S307).

  Finally, another embodiment of the present invention will be described with reference to FIG. In this example, the mounting portion 2 is formed of a cylinder 2a, a locking projection 2b, and a locking recess 2c. However, as shown in this figure, the cylinder 2a is omitted, and at least one locking projection 2b and The structure formed from the latching recessed part 2c corresponding to this may be sufficient.

In the embodiment shown in each figure, the cylindrical projection 2b is provided on the cylinder 2a, and the latching recess 2c is provided on the thermal image camera body 3. However, the soaking plate 1 is mounted on the thermal camera body 3. However, the present invention is not limited to this as long as it can achieve the purpose of doing so.
Moreover, although the structure which the conducting wire of the temperature sensor 5 extends from the inside of the mounting part 2 is shown, if the temperature measuring part is located in the heat equalizing plate or in the vicinity thereof, the conductor does not pass through the mounting part 2. There may be.
Further, in this example, the temperature information of each pixel of the FPA 8 is first converted into a digital quantity. However, the information from the temperature sensor 5 may be processed first.

  As described above, by using the pixel correction apparatus according to the present invention, it is possible to easily perform correction of pixels at any time, and it is possible to maintain the size of a small camera because a shutter and its opening / closing function are not incorporated.

  As mentioned above, although the best form in this invention was demonstrated, this invention is not limited with the description and drawing by this form. That is, it is a matter of course that all other forms, examples, operation techniques, and the like made by those skilled in the art based on this form are included in the scope of the present invention.

FIG. 1 is a schematic side sectional view of a thermal image camera employing a pixel correction apparatus according to the present invention. 2A is an enlarged schematic cross-sectional view of the temperature sensor and the reading unit, and FIG. 2B is an enlarged schematic cross-sectional view when the temperature sensor and the reading unit are in contact with each other. FIG. 3 is a flowchart in which temperature information is processed in the calculation unit. FIG. 4 shows another embodiment of the present invention.

Explanation of symbols

1 soaking plate 2 mounting part (2a cylinder, 2b locking projection, 2c locking recess)
3 Thermal Image Camera Body 4 Lens 5 Temperature Sensor 5a Transmission Unit 6 Conversion Unit 7 Calculation Unit 8 FPA (Focal Plane Array)
9a, 9b wiring

Claims (1)

In a pixel correction apparatus according to a thermal image camera using an infrared imaging device,
A removable soaking plate covering the lens of the thermal imaging camera;
In order to attach the soaking plate to the thermal image camera body, the soaking plate and a mounting part provided in the thermal image camera body,
A temperature sensor that is provided in contact with or near the soaking plate and measures the temperature of the soaking plate;
A conversion unit for converting the temperature information measured by each pixel of the infrared imaging element and the temperature information of the heat equalization plate measured by the temperature sensor into digital quantities, located in the thermal image camera body;
Similarly, it is located in the thermal image camera body, and after calculating the digital quantity to the measurement temperature of each pixel and the measurement temperature of the soaking plate, the measurement temperature of each pixel and the measurement temperature of the soaking plate are calculated. A pixel correction device for a thermal image camera, comprising: a calculation unit that calculates a correction coefficient necessary for correcting a pixel having a variation in sensitivity from the difference, and calculates a correction coefficient.

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