JPS62129727A - radiant energy imager - Google Patents

Abstract

PURPOSE:To obtain a correct thermal image without being affected by emissivity, by utilizing an image data obtained using two kinds of wavelengths. CONSTITUTION:To obtain an energy Wlambda1 with a wavelength lambda1 and an energy Wlambda2 with a wavelength lambda2, a filter 1 is switched to store the energies with the wavelength lambda1 and lambda2 transmitted through the filter 1 into frame memories 4a and 4b respectively. Then, a processing is done with a comparison operational unit 5 at each pixel of the memories 4a and 4b and from the results thereof, the energies are converted into correct temperatures at a temperature converter section 6. After written into a frame memory 8, the processed data is read out through a control of a microcomputer 12 and fed to a monitoring unit 10 through a processing unit 9 to be displayed. This assures a correct thermal image even when the emissivity is not even over the entire surface of an object.

Description

[Detailed Description of the Invention] Industrial Application Field] This invention captures images of radiation emitted from various parts of an object, particularly infrared rays, and creates a temperature distribution image (hereinafter referred to as a thermal image) of the object from the imaging results. The present invention relates to a radiant energy imaging device that obtains a radiant energy imager.

[Conventional technology]

It has been known that radiation such as infrared rays is emitted from the frowning surface of an object depending on the temperature of the object.

By capturing this infrared rays and displaying a thermal image,
Since the temperature distribution of the object can be known, this measurement method can instantaneously obtain temperature distribution over a wide range without contact. For this reason, it is effectively used in places where contact methods cannot be used.

[Problem that the invention seeks to solve]

However, the amount of energy radiated is determined by the emissivity of the surface of the object, and this emissivity is not uniform over the entire measurement surface, which has been a source of error.

[Means for solving problems]

In order to solve these drawbacks, the present invention uses imaging data obtained using two types of wavelengths to process thermal images so that they are not affected by emissivity.

[Effect]

The ratio between data captured at a certain wavelength and data captured at a different wavelength is determined, and based on the results, a thermal image showing accurate temperature across the entire screen is obtained.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a filter, 2 is a camera head, 3 is a changeover switch, 4a is an nbfd frame memory, 5 is a comparison calculation unit, and 6 is a temperature control unit. Conversion section, 7 is comparison temperature table, 8
1 is a frame memo IJ, 9 is a display processing section, 10 is a monitor section, 11 is a filter switching section, and 12 is a microcomputer.

Filter 1 is a bandpass filter that allows only a specific wavelength component of infrared energy emitted from an object to enter camera head 2. 2fi! wavelength λ1. λ
2 is selected according to a restriction signal supplied from the filter switching section 11. The camera head 2 is configured to take an image of the infrared rays supplied through the filter 1, convert it into a digital signal, and send it out. The switch 3 and the frame memo 'J4a, 4b are designed so that the selected side is determined in synchronization with the wavelength selection of the filter 10. Comparison calculation section 5 is a frame memo! The ratio of the signals supplied from 74B and 4b is determined and the value is supplied to the temperature conversion section 6.

The operation of the device thus constructed is as follows. The filter switching unit 11 is a microcomputer 12
The filter J17 is controlled in accordance with the data supplied from the filter 1, and the transmission wavelength of the filter 1 is alternately selected. As a result,
Infrared rays of wavelengths λl and λ2 are alternately imaged by the camera head 2, converted into digital signals, and supplied to the changeover switch 3.

The changeover switch 3 is switched in synchronization with the wavelength switching of the filter 1, and alternately supplies data of the wavelength λ1 to the frame memory 4a and data of the wavelength λ2 to the frame memory 4b. The data supplied to the frame memories 4a, 4b are stored at locations determined by the address data supplied from the microcomputer 12. The stored data is then supplied to the comparison calculation unit 5, and the data ratio for each pixel is determined.

The data obtained by the comparison calculation section 5 is supplied to the temperature conversion section 6, where it is compared with the data written in advance in the comparison temperature table 7, and the data supplied to the temperature conversion section 6 is converted into a temperature signal. Output. This processing is performed for all pixels in the frame memories 4a and 4b, and the processed data is written into the frame memory 8.

Thereafter, the data written in the 71/-memory 8 is read out under the control of the microcomputer 12, and is supplied to the monitor section 10 via the display processing section 9 and displayed.

Next, the reason why the thermal image obtained in this way represents an accurate energy distribution will be explained.

Infrared radiation of a certain wavelength λ emitted from an object
λ is the following (where C++C2 is a constant and T is the absolute temperature)
1) It is expressed by the formula.

However, the actual object is the same warm and warped material, but
The infrared light emitted by the infrared chamber: ji differs depending on the clothing condition, etc.
If the degree of this radiation is defined as emissivity ε, then equation (1) becomes the following (
2) It can be expressed as follows.

Self C, /λ.

wλ= go-(e-1)-'I'”
"<2) λ5 Here, the radiation energy at wavelength λ1.λ2 is as follows (3)
.

It can be expressed by equation (4). − Taking this ratio gives the following equation (5).

Since equation (5) does not include the emissivity ε, the accurate absolute temperature T can be determined from this value.

The device in Fig. 1 has energy W,i of wavelength λ1 and wavelength λ
In order to obtain the energy Wλ2 of 2, the filter 1 is switched, and the energy of the wavelength λl transmitted through the filter 1 and the energy of the wavelength λ2 are stored in the frame memories 4a and 4b, respectively, and the pixels of the frame memories 4a and 4b are At each time, the comparison calculation section 5 processes the equation (5), and based on the result, the temperature conversion section 6 converts it into an accurate temperature. Therefore, even if the emissivity ε is not uniform over the entire surface of the object, an accurate thermal image can be obtained because equation (5) does not include the term of the emissivity ε.

As shown in FIG. 2, the filter 1 consists of two elmmen Ha,
This can be realized by rotating 1b around axis 1c or making the two elements collapsible. Further, in the embodiment, the filter 1 is placed in front of the camera head 2, but it may be placed anywhere up to the front stage of the detector inside the camera head. Note that the transmission wavelength of filter 1 is λl.

λ2 must be selected within the wavelength band sensitive to the detector in the camera head. Also, from the change characteristics of emissivity with respect to the temperature of the object, the transmission wavelength λ! , λ2, it is necessary to select wavelengths as close as possible to AM.

〔Effect of the invention〕

As explained above, this invention has the effect of obtaining an accurate thermal image without being affected by emissivity, since the ratio of infrared energy that has passed through filters having different transmission wavelengths is calculated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a plan view of the filter. 1...filter, 2...camera head. 3...Selector switch, 4a, 4b, 8...Frame memory, 5...Comparison performance. part, 6...temperature conversion part, 7...comparison temperature table, 9...display processing part, 10...monitor part. 11... Filter switching section, 12... Microcomputer.

Claims (1)

[Claims] In a radiant energy imaging device that images radiation emitted from an object and obtains a radiant energy distribution image from the imaging results, a first memory stores an imaging result of a certain wavelength and an imaging result of a wavelength different from that wavelength is stored. A radiant energy imaging device comprising: a second memory; and a temperature calculation section that calculates the true temperature of an object from the ratio of the imaging results of the first and second memories.