JPH03215720A - Infrared thermometer - Google Patents

Abstract

PURPOSE:To improve the inconvenience of handling and to measure temperature continuously and accurately by providing an object infrared sensor which receives infrared rays from an object and an infrared sensor for temperature calibration which receives infrared rays from a standard black body. CONSTITUTION:One infrared sensor 11 is arranged opposite to the object across an infrared-ray incidence window 15 and the other infrared sensor 12 is set opposite to the reference black body 13 which is held at specific temperature by the heater 14 to detect reference temperature. The outputs of the infrared sensors 11 and 12 are switched by a switch circuit 20 which is controlled by a CPU 23 and passed through an amplifying and detecting circuit 21 to obtain an output level V1 with the infrared rays from the object and an output level V2 with the infrared rays from the standard black body 13. The output levels V1 and V2 are converted 22 into digital data, which are stored 25. Then the CPU 23 determines the measured temperature of the object from the value (V1-V2) according to a control program which is stored 24 by using a value stored in a conversion table 24a in a ROM 24 previously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an infrared thermometer that measures the temperature of an object by detecting infrared rays emitted from the object.

[Prior Art] In conventional infrared thermometers, in order to accurately measure the temperature of an object by detecting infrared rays from the object, a temperature probe section containing an infrared sensor is installed as a standard at the beginning of each measurement. The temperature of the infrared sensor is calibrated by facing the black body, which is an infrared generator.

That is, an infrared thermometer includes an infrared sensor that receives infrared rays from an object, a #1 width detection circuit that receives the output of this sensor and increases f1 width, and a temperature display section that converts this amplified output into a temperature value and outputs it for display. However, when trying to accurately read the temperature of an object with this infrared thermometer, a problem arises due to characteristic drift of the infrared sensor and amplification detection circuit.

This characteristic drift makes it impossible to perform accurate measurements. Therefore, in order to solve this problem, Fig. 4 (a) and (b)
), a part of the main body of the measuring unit includes a blackbody, which is a standard infrared temperature reference, and controls the heater to maintain a constant temperature with high precision. FIG. 5 shows a flowchart of a conventional measurement procedure.

In this conventional infrared thermometer, when measuring the temperature of a certain object, the probe section containing the infrared sensor must first be connected to the temperature calibration black body in the measuring section body, as shown in Figure 4(b). The infrared sensor and the amplification detection circuit are then calibrated for temperature (step S52). After performing this calibration, wait until the probe (infrared sensor) is directed toward the object (step S53). The temperature of the object is measured (step S54). When measuring the temperature of an object, in order to accurately measure the temperature, it is necessary to calibrate the temperature of the infrared sensor and the amplification detection circuit, and then complete the measurement within a certain period of time. This is because if the measurement takes longer than this time, error factors due to characteristic drift will appear, and accurate measurement cannot be guaranteed.

Therefore, it is checked whether the measurement is completed within a certain period of time, for example, within 30 seconds (step S55). If the measurement is completed within a certain period of time, the measurement result is displayed (step S56), but if it is not completed, the measurement is determined to be impossible (step S57) and the measurement is started again. [Problems to be solved by the invention] As described above, in conventional infrared thermometers, temperature calibration is always performed at the beginning of each measurement (it takes about 30 seconds for the detection system to stabilize after receiving infrared radiation from a black body). When starting a measurement after this calibration, it is necessary to finish the measurement quickly (within about 30 seconds) without spending much time on the measurement.

As mentioned above, various restrictions must be placed on measurement procedures and handling.

[Problems to be Solved by the Invention] The present invention provides an infrared thermometer that eliminates the above-mentioned conventional drawbacks, improves inconvenience in handling, and enables continuous and accurate temperature measurement. be.

[Means for solving the problem] In order to solve this problem, the infrared thermometer of the present invention has the following features:
An infrared thermometer that measures temperature by detecting infrared rays emitted from an object includes an object infrared sensor that receives infrared rays from the object, a temperature calibration infrared sensor that receives infrared rays from a standard black body, and both of the above. and a housing chamber that covers the sensor and creates the same ambient temperature environment.

Here, the infrared rays from the standard blackbody are supplied to the temperature calibration infrared sensor via an optical fiber.

[Function] In this configuration, an infrared sensor for measuring an object and an infrared sensor for measuring a temperature reference black body are housed in the same housing in the temperature measuring probe, and the temperature is measured by detecting infrared rays from the object. In addition, by constantly detecting the infrared rays from the temperature reference blackbody in parallel, the temperature of the infrared sensor and the amplification detection circuit section can be constantly calibrated, so that highly accurate infrared detection temperature measurement can be performed continuously and at any time.

[Example] Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1A is a diagram showing the configuration of the infrared thermometer of this embodiment.

First, two infrared sensors 11 and 12 with well-matched characteristics are placed back-to-back in close contact within the infrared detection probe 10. One infrared sensor 11 is made to face the object via an infrared incidence window 15. Another infrared sensor 1
2 is arranged to face a reference black body 13 which is set at a predetermined temperature by a heater 14 to detect a reference temperature.

The outputs from the infrared sensors 11 and 12 are switched by a switch circuit controlled by the CPU 23 and passed through the amplification detection circuit 21, respectively, to obtain an output level v1 by the infrared rays from the object, and by the infrared rays from the reference black body 13. The output level v2 is obtained. The output level v,,V2 is A
/D converter 22 converts it into digital data and stores it in RAM.
25.

According to the control program stored in the ROM 24, the CP023 determines the measured temperature of the object based on the value of (vI-V2) stored in advance in the conversion table 24a of the ROM 24.

The measured temperature is displayed on a display unit 26 made of liquid crystal or the like.

FIG. IB shows an example of the conversion table 24a. Here, it is assumed that the temperature of the reference black body is maintained at 37.0°C. Note that the conversion table may be provided in the RAM 25 and created or written before measurement.

FIG. 2 is a diagram showing the configuration of the probe section of another embodiment.

If the probe becomes thicker by placing the reference black body inside the probe, the reference black body 13 is placed outside the probe 10' and the thermal radiation from the reference black body 13 is guided into the probe 10' through the optical fiber 16. , an infrared signal is input to the reference black body thermal radiation detection sensor l2. This allows the probe to be made thinner and smaller, allowing it to be handled in narrow spaces.

FIG. 3 is a flowchart showing the processing procedure of the infrared thermometer of this embodiment.

First, at the time of starting measurement, the process waits for the measurement interval time (0.5 sec in this example) to elapse in step S31. If the elapsed time has elapsed, the process advances to step S32, and both infrared sensors 11
, 12 is input, the difference (v1-V2) is calculated in step S33, and the temperature is determined based on the conversion table 24a in step S34. After the temperature determination is completed, the measured value is displayed in step S35, and it is determined in step S36 whether or not the measurement is continuous. If the measurement is continuous, the process returns to step S31 and steps S31 to S36 are repeated.

When using the probes shown in Figures IA and 2 above, the two infrared sensors 11 and 12 have the same characteristics, so there is very little difference in sensor output even when the ambient temperature around the sensor changes. Or, even if there is a difference, the temperature can be measured with sufficient measurement accuracy by correction. According to this sensor system, one of the reference black body thermal radiation detection sensors 12 always receives radiation from the reference black body, so a thermal radiation signal corresponding to the reference black body temperature is always incorporated into this temperature measurement system. ing.

For this reason, short measurement periods (e.g. 0.5 to lsec)
Since the reference calibration value is taken in once every time, this temperature measurement system can be considered to be constantly calibrated. Therefore, unlike conventional thermometers, it is not necessary to perform temperature calibration at the beginning of every measurement period (for example, about 1 minute), and it is possible to continuously measure temperature.

As explained above, if the infrared thermometer of this embodiment is used, temperature calibration is always performed, so highly accurate temperature measurement is possible at any time, and temperature measurement can be performed continuously. Temperature measurement can be performed without the troublesome work required with conventional thermometers, which always requires temperature calibration in between.

[Effects of the Invention] According to the present invention, it is possible to provide an infrared thermometer that improves the inconvenience in handling and enables continuous and accurate temperature measurement. In other words, with conventional infrared thermometers, it was necessary to calibrate the infrared sensor and temperature measurement circuit using a reference blackbody radiation source after each temperature measurement was completed, but with the infrared thermometer of the present invention, the infrared sensor and temperature measurement circuit always need to be calibrated using a reference blackbody radiation source. Since temperature calibration is performed using a reference blackbody radiation source, one temperature measurement can be immediately followed by the next one.

[Brief explanation of drawings]

Figure 1A is a diagram showing the configuration of the infrared thermometer of this embodiment, Figure IB is a diagram showing the conversion table of this embodiment, and Figure 2 is a diagram showing the configuration of the probe section of the infrared thermometer of another embodiment. Figure 3 is a flowchart showing the temperature measurement procedure of the infrared thermometer of this embodiment, Figures 4 (a) and (b) are diagrams showing temperature measurement using a conventional infrared thermometer, and Figure 5 is a flowchart showing the temperature measurement procedure of the infrared thermometer of this embodiment. It is a flowchart which shows the temperature measurement procedure of an infrared thermometer. In the figure, 10.10'--Probe, 11--Infrared sensor for object, 12--Infrared sensor for reference temperature detection, 13--Black body, 14--Heater, 15-- Infrared transmission window, 16... Optical fiber, 20... Switch circuit, 2l... Amplification detection circuit, 22... A/D converter, 2 3-CPU, 24-ROM, 24a...
- Conversion table, 25... RAM, 26... Display section. Figure 3

Claims (2)

[Claims] (1) In an infrared thermometer that measures temperature by detecting infrared rays emitted from an object, there are two types: an infrared sensor for the object that receives infrared rays from the object, and an infrared sensor for temperature calibration that receives infrared rays from a standard black body. , and a housing chamber that covers both the sensors and creates the same ambient temperature environment. (2) The infrared thermometer according to claim 1, wherein the infrared rays from the standard black body are supplied to the temperature calibration infrared sensor via an optical fiber.