JPH0456934B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an infrared imaging device that detects infrared rays emitted from each part of an object and displays the temperature distribution of the object as a visible image. .

[Conventional technology]

Infrared imaging equipment optically scans a specific field of view of an object, detects the amount of infrared radiation emitted from the object's surface according to its surface temperature, converts this into an electrical signal, and then processes the image. It is used to obtain thermal images.

Since this type of infrared imaging device is calibrated using a black body, which is a reference standard for the relationship between temperature and the amount of infrared radiation, it is possible to measure the absolute temperature distribution of the object.

[Problem that the invention seeks to solve]

However, depending on the object, it may be necessary to insert an object between the camera head and the object for measurement. For example, when observing an object inside a furnace surrounded by fire bricks, etc., an observation window is opened in the furnace, a special infrared window material is fitted into the window, and the object is observed through the infrared window material. Furthermore, when observing the surface temperature of special objects such as glass and plastic, these objects not only emit infrared rays themselves, but also transmit infrared rays emitted from the background, so it is necessary to remove the transmitted infrared rays. . Therefore, temperature measurement cannot be performed unless a special optical filter is installed in front of the camera head that takes into account the infrared wavelength characteristics of these objects.

When such an inclusion such as a window or a filter is inserted, as shown in FIG. is before and after inclusion 5
Decrease from W1 to W2. Therefore, the temperature of the object observed by an infrared imaging device appears lower than its true temperature. That is, conventional infrared imaging devices cannot observe the true temperature distribution of an object.

[Means for solving problems]

The present invention has been made in view of the above problems, and it converts an analog thermal image signal outputted from a camera section into a digital thermal image signal using an A/D converter based on an appropriate reference voltage. This is an infrared imaging device that stores thermal images in a frame memory and then reads them again to display a thermal image on a display. A storage means that stores in advance a plurality of types of temperature tables representing the relationship between the voltage amount of the electric signal output by the camera section, and a specified temperature table is selected from the storage means, and the selected temperature table and The device is equipped with a microprocessor that calculates the reference voltage value of the A/D converter from separately specified observed temperature conditions.

[Effect]

By appropriately selecting a temperature table depending on the inclusion during measurement, the reference voltage value of the infrared imaging device is changed.

〔Example〕

Hereinafter, the present invention will be explained in detail together with examples.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The camera section 1 consists of an optical scanning mechanism, a condensing lens, an infrared detector, and a synchronization signal generator, and scans the object and each part, converts the amount of infrared radiation emitted from the surface into an electrical signal, and converts the signal into an electric signal. It is output to the A/D converter 22 as an analog thermal image signal. At the same time, a synchronization signal S is output.

The A/D converter 22 converts the analog thermal image signal from the camera section 1 into a digital quantity with a predetermined number of bits in synchronization with the synchronization signal S also from the camera section 1. Note that a reference voltage for digital conversion is provided from a microprocessor 26, which will be described later.

The frame memory 23 stores the thermal image signal converted into a digital quantity by the A/D converter 22 at a predetermined address based on the synchronization signal from the camera section 1.

The display processor 24 reads out the digital thermal image signal stored in the frame memory 23 at a scanning rate suitable for the display 3, and also processes the coloring of the thermal image on the display 3 and adds a temperature scale, color scale, temperature table name, etc. It performs information display processing, and constitutes the thermal image signal processing section 2 together with the A/D converter 22 and frame memory 23.

The display unit 3 consists of a color monitor TV, and the temperature distribution of the object is displayed in up to 16 colors, and the observer can see the same color as the image of the object on the color scale displayed on the same screen. The absolute temperature of the object can be determined from the numbers on the temperature scale, which is displayed in parallel with the color scale.

The microprocessor 26 selects one from a plurality of temperature tables stored in the ROM 27 based on a command from the operation panel 28, and uses the selected temperature table and the observed temperature conditions (separately instructed from the operation panel 28). A/D converter 2
2 digital conversion reference voltage is generated. Further, in order to display on the display 3 which temperature table is selected, the display processor 24 is informed of the temperature table name.

The temperature table is a digital value obtained by converting the relationship between the amount of infrared rays emitted from the object, that is, the temperature, and the amount of voltage converted by the detector built in the camera section 1.

FIG. 2 shows an example of the relationship between the temperature of the object and the amount of voltage converted by the detector built into the camera unit 1. A solid line 30 represents the relationship between the temperature of the object (black body reference) and the output voltage from the detector of the camera section 1 when there is no intervening material such as a window material or a filter between the object and the camera section 1. As is clear from the figure, this relationship is not linear. Maximum voltage of output
Vz is determined by the characteristics of the voltage amplifier added after the detector. One of the temperature tables stored in the ROM 27 contains a voltage value Va, which is obtained by dividing this maximum voltage Vz by a predetermined number of bits.
Values obtained by digitally converting Vb, Vc, ..., Vz and temperatures corresponding to the voltage values Va, Vb, Vc, ..., Vz
The digitally converted values of Ta, Tb, Tc, ...Tz are stored in table format.

When there is an inclusion such as a window material or a filter between the object and the camera section 1, the relationship between the temperature of the object (blackbody reference) and the output voltage from the detector of the camera section 1 will depend on the inclusion. different. Solid line 31,3 in Figure 3
2 and 33 show the relationship in such a case. Note that the solid line 30 in the figure corresponds to the solid line 30 in FIG. 2.

Temperature tables #1, #2, #3, and #4 stored in the ROM 27 are tables in which the relationships represented by solid lines 30 to 33 in FIG. 3 are stored, respectively.

Observation temperature conditions refer to conditions that determine the temperature range to be observed, and specifically refer to the lower limit of the observation temperature range and temperature resolution. The temperature range that can be detected by the camera unit 1 (detection temperature range) is wide, therefore,
Each temperature table stores the relationship between temperature and voltage so as to cover the entire detected temperature range.

Assuming, for example, a 16-color display as in this embodiment, the reference voltage value in the A/D converter 22 must have at least 15 levels, which can be selected by specifying the lower limit of the observed temperature range and the temperature resolution. Select the corresponding 15 levels of reference voltage values from the temperature table. For example, set the lower limit of the observed temperature range to
If 100℃ and temperature resolution is 1℃, 116 from 100℃
It is possible to observe temperatures down to ℃.

Next, the operation of this embodiment will be explained.

First, on the operation panel 28, a temperature table is selected and observed temperature conditions are set. Now, assuming that there is no inclusion between the object and the camera unit 1, temperature table #1 will be selected.

Next, specify the observation temperature conditions. Now, when the lower limit of the observation temperature range is specified as T0 and the temperature analysis capability is specified as S1 on the operation panel 28, this command is input to the microprocessor 26, and the value is stored in the ROM 2.
Digital voltage values V0 to V16 corresponding to each temperature are calculated and sent to the A/D converter 22.

Note that if the lower limit value of the observation temperature range and temperature resolution specified from the operation panel 28 do not match the temperature value in the temperature table stored in the ROM 27, the temperature values in the temperature table located above and below the temperature value are Based on the interpolation method, which calculates the temperature value between two points by linear approximation, the reference voltage is determined and output.

The A/D converter 22 digitally converts the analog thermal image signal from the camera unit 1 using the voltage values V0 to V16 as a reference. That is, the observed temperature range is digitally converted in 16 steps (4 bits) from temperature T0 to T16. At this time, the thermal image signal is
The image is digitized at a frequency that determines the number of horizontal pixels in one scanning line based on the scanning synchronization signal from .

The digitized thermal image signal is stored in the frame memory 2.
After being written to the address specified by 3, the display processor 24 reads out the data at the scanning rate of the monitor TV, which is the display 3, and performs display processing, as well as the selected temperature table number, temperature scale, Color scale display processing is performed, and a pseudo color thermal image, temperature table number, etc. are displayed on the monitor television.

If there is an inclusion such as a window material or a filter between the object to be measured and the camera unit 1, accurate temperature measurement can be achieved by appropriately selecting temperature tables #2 to #4 prepared in advance according to the inclusion. Can be done.

In this embodiment, four types of temperature tables are stored in advance, but it goes without saying that two or more types may be used.

Further, in this embodiment, a color monitor television is used as the display device, but a monochrome monitor television may also be used.

Furthermore, although it is a 16-part display, it goes without saying that it is not necessarily limited to this number.

〔Effect of the invention〕

As explained above, according to the infrared imaging device of the present invention, a temperature table representing the relationship between the temperature of the object and the voltage amount of the electric signal output by the camera section is interposed between the object and the camera section. Multiple types of temperature tables are stored in advance depending on the presence and type of inclusions, and the reference voltage value of the infrared imaging device is changed by appropriately selecting these temperature tables depending on the inclusions during measurement. Optimal observations can be made regardless of the situation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Figures 2 and 3 are graphs showing the relationship between the temperature of the object and the voltage of the electrical signal output by the camera unit 1, and Figure 4 is a state diagram showing how infrared rays are absorbed by inclusions. It is. 1... Camera section, 2... Thermal image signal processing section, 3...
...Display device, 4...Object, 5...Inclusion, 22...
...A/D converter, 23...Frame memory, 24
...Display processor, 26...Microprocessor,
27...ROM, 28...operation panel.

Claims (1)

[Claims] 1 A camera unit that scans an object and converts the amount of infrared radiation emitted from its surface into an electrical signal and outputs it as an analog thermal image signal, and converts the analog thermal image signal into a digital signal based on an appropriate reference voltage. An A/D converter that converts the digital thermal image signal into a thermal image signal, a frame memory that stores the digital thermal image signal as temperature data for each pixel, and a frame memory that stores the temperature data for each pixel stored in the frame memory at an appropriate scanning rate. A display processor that reads out a thermal image, a display that displays a thermal image based on the signal from the display processor, and a display that displays the temperature of the object and the temperature of the object depending on the presence or absence and type of an inclusion interposed between the object and the camera section. A storage means that stores in advance a plurality of types of temperature tables representing the relationship with the voltage amount of the electric signal output by the camera section, and a specified temperature table is selected from the storage means, and the selected temperature table and a separate temperature table are stored. An infrared imaging device comprising: a microprocessor that calculates a reference voltage value of the A/D converter from specified observed temperature conditions.