JPH10274564A - Non-cooled infrared two-dimensional sensor camera with shading correcting function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically make a shading correction including the influence of a lens in a short time without an operator needing to set a uniform plane heat source manually in an infrared camera. SOLUTION: A shutter 2 easily opened/closed in an instant by a shutter controller 3 is provided in the optical pupil position of a combination lens 1. Thermal image data at the time of closing the shutter 2 is story in a shading memory 8, and a subtracter 7 subtracts stored shading memory data from the thermal image data at the time of photographing the infrared image of the external work in the opened state of the shutter 2 every corresponding picture element, and outputs the result to a frame memory 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the field of techniques for correcting shading in an infrared camera using an infrared two-dimensional sensor.

[0002]

2. Description of the Related Art In an infrared camera, the amount of infrared energy incident on a two-dimensional sensor due to stray light in a camera housing irrespective of an object to be measured increases from a central portion to a peripheral portion when an environmental temperature is high. In contrast, when the environmental temperature is low, a phenomenon (temperature gradient) called so-called shading occurs in which the amount of energy decreases from the center to the periphery when the environmental temperature is low. This is particularly noticeable in uncooled infrared cameras. If there is such a temperature gradient in a place where there should not be a temperature gradient, accurate temperature measurement cannot be performed from an infrared image. Therefore, an operation for correcting the influence of the shading has been performed.

The first method is to manually place a surface heat source having a uniform temperature in front of the lens or cover the lens so that the output of each pixel of the infrared two-dimensional sensor becomes uniform. Had been corrected. The second method is a method in which a plate, which is a uniform surface heat source, is inserted between the lens and the infrared two-dimensional sensor by mechanical driving to perform correction.

[0004]

However, in the first method, there is a problem that it takes a long time for correction because the surface heat source is set manually, and in the second method, it is caused by the presence of a lens. There is a problem that the influence of shading cannot be corrected.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to eliminate the need for a camera operator to manually set a uniform planar heat source, and to correct the effects of shading by a lens in a short time. An object of the present invention is to provide an uncooled infrared two-dimensional sensor camera with a shading correction function that can be performed.

[0006]

In order to achieve the above object, an uncooled infrared ray 2 with a shading correction function according to the present invention is provided.
The dimensional sensor camera is characterized by having the following components. (A) Combination lens for forming an infrared image having a built-in shutter at the optical pupil position. (B) Shutter controller for controlling opening and closing of the shutter. (C) Two-dimensional sensor on which an infrared image is formed by the combination lens. D) an A / D converter that converts an analog electric signal output by pixel scanning to the two-dimensional sensor into a digital signal for each pixel; (e) an output signal of the A / D converter is used as an input signal at one input terminal A subtractor for performing subtraction with a signal input to the other input terminal. (F) After storing the output of the A / D converter when the shutter is closed for one frame, and then after opening the shutter, Are read out in such a manner that the stored signal is made coincident with the pixel position of the signal input to one input terminal of the subtractor, and the shading memo is input to the other input terminal of the subtractor. (G) a frame memory for storing an output of said subtractor with each screen

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention uses a combination lens having a built-in shutter which can be easily opened and closed from the outside at an optical pupil position, and closes the shutter to block infrared rays through the lens. Pixel scanning of the infrared two-dimensional sensor under the influence of shading due to stray light is performed, and the obtained signal is stored in a shading memory for each pixel. An image is formed on a dimensional sensor, pixel scanning is performed on the image, a signal for each pixel is taken out, and a signal of a corresponding pixel stored in a shading memory is read from this signal for each pixel, and the signal is sent to a subtractor. In this case, the effect of shading is removed by subtraction.

As described above, the shutter is closed and stored in the shading memory, that is, the updating of the shading memory may be automatically performed at predetermined intervals, or may be performed in response to the passage of time. It may be performed when the temperature change exceeds a predetermined value. This may be performed by the operator's observation or automatically.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the infrared camera according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the infrared camera of the present invention. A shutter 2 is provided at a position of an optical pupil of a combination lens 1 for condensing infrared rays from the outside. The shutter 2 is opened and closed by a shutter controller 3. When the shutter 2 is open, the collected infrared light forms an image on the surface of the infrared two-dimensional sensor 4. From the infrared two-dimensional sensor, an electric signal corresponding to the infrared intensity is extracted for each pixel by a fixed scan (for example, raster scan). The extracted infrared image signal is amplified by the amplifier 5 to a level necessary for the subsequent processing. The amplified signal is converted by the A / D converter 6 into a digital signal having a bit number that satisfies the required gradation. The obtained digital signal is input to one input terminal of a subtractor 7 for reducing the influence of shading, and is output to the frame memory 9 in a form in which the influence of shading has been removed.

On the other hand, the shading memory 8 includes a subtractor 7
Are connected so that the output of the subtractor 7 can be read out and input to the other input terminal of the subtractor 7. The effect is that the output of the A / D converter 6 when the shutter 2 is closed is stored in the shading memory 8 via the subtracter 7 for one screen. At this time, since the reading from the shading memory 8 is not performed and no signal is input to the other input terminal of the subtractor 7, the subtractor 7 does not perform the subtraction and the input from the A / D converter 6 is output as it is and the shading memory is output. 8 is stored for each pixel. Thus, the stored data is shading thermal image data caused by stray light in the lens and the housing after the shutter 2.

On the other hand, the thermal image formed on the infrared two-dimensional sensor 4 when the shutter 2 is opened and the infrared rays from the outside are condensed is obtained by adding the infrared rays from the outside and the shading. It is in the state. Therefore, to obtain a thermal image using only infrared rays from the outside world,
The shading thermal image should be subtracted from the thermal image formed on the infrared two-dimensional sensor.

Therefore, the data stored in the shading memory 8 stored when the shutter 2 is closed is read out and input to the other input terminal of the subtracter 7, and the corresponding data is input from the A / D converter 6. By reducing for each pixel, it is possible to obtain thermal image data using only infrared rays from the outside, from which the influence of shading has been removed.

The thermal image data obtained in this way is stored in the frame memory 9 to prepare for a later processing stage.
Note that the operation of the shutter controller 3 and the operation of storing and reading the data in and from the shading memory 8 are linked using a CPU.

[0014]

As described above, the infrared two-dimensional sensor camera with the shading correction function of the present invention can be opened and closed at the position of the optical pupil of the combination lens for condensing infrared rays by external control by the shutter controller. A shutter that can be instantly and easily provided is provided, thermal image data when the shutter is closed is stored in a shading memory, and thermal image data formed when an infrared image of the outside world is taken with the shutter opened is stored. Since the shading data that was set is reduced for each pixel,
There is no need for the camera operator to manually set a uniform flat heat source or put a cap on the lens, and the effects of shading, including the effects of the lens behind the shutter, are automatically reduced in a short time. There is an advantage that correction can be made to

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an embodiment of an uncooled infrared two-dimensional sensor camera with a shading correction function according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combination lens 2 Shutter 3 Shutter controller 4 Infrared two-dimensional sensor 5 Amplifier 6 A / D converter 7 Subtractor 8 Shading memory 9 Frame memory 10 CPU bus

Claims (1)

[Claims] 1. An uncooled infrared two-dimensional sensor camera having a shading correction function, comprising: (A) Combination lens for forming an infrared image having a built-in shutter at the optical pupil position. (B) Shutter controller for controlling opening and closing of the shutter. (C) Two-dimensional sensor on which an infrared image is formed by the combination lens. D) an A / D converter that converts an analog electric signal output by pixel scanning with respect to the two-dimensional sensor into a digital signal for each pixel; (e) an output signal of the A / D converter is used as an input signal at one input terminal A subtractor for performing subtraction with a signal input to the other input terminal. (F) After storing the output of the A / D converter when the shutter is closed for one frame, and then after opening the shutter, Is read out in such a manner that the stored signal matches the pixel position of the signal input to one input terminal of the subtractor, and the shading memo is input to the other input terminal of the subtractor. (G) a frame memory for storing an output of said subtractor with each screen