JPH08278203A - Infrared ray radiation thermometer - Google Patents

Abstract

PURPOSE: To correct a measuring error caused by giving and receiving of radiation energy between a lens and a sensor, and provide an infrared ray radiation thermometer wherein accurate temperature measuring can be always performed. CONSTITUTION: A lens 12 for collecting an infrared ray emitted from an object 11 of which temperature is measured, an infrared ray sensor 13 for converting the infrared ray into an electrical signal, and an operation means 14 for converting the electrical signal into a temperature unit are provided. Furthermore, a lens temperature measuring means 15 for measuring the temperature of the lens 12, a sensor temperature-measuring means 16 for measuring the temperature of the infrared ray sensor 13, a correction means 17 for making a correction signal according to both the temperature-measuring means 15, 16, a conversion means 18 for converting into a temperature signal by using the signals of the operation means 14 and the correction means 17, and an output means 19 for outputting and showing the temperature signal are equipped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared radiation thermometer which uses infrared rays to measure temperature in a non-contact manner, and more particularly to an infrared radiation thermometer having improved accuracy and stability during temperature measurement.

[0002]

2. Description of the Related Art In the field of temperature measurement, an infrared radiation thermometer capable of making non-contact measurement is widely used, but it has been found that a considerably large error occurs depending on the measurement conditions. This error is caused by a portable infrared radiation thermometer, especially when the temperature difference between the ambient temperature and the temperature measurement object is large,
It appears remarkably when it is used under the condition that the ambient temperature changes significantly.

Explaining with reference to FIG. 9, for example, an infrared radiation thermometer is left in a place of a certain ambient temperature for a long time, and the infrared radiation thermometer is made to adapt to the temperature, and the temperature is higher than the ambient temperature. When trying to measure the temperature of the temperature measuring object 1 having a much higher temperature, T _L = T _S in the initial state where there is no temperature difference between the temperature T _{L of the} lens 2 and the temperature T _{S of the} sensor 3, There is no radiation from 2 itself to the sensor 3, and the energy incident on the sensor 3 is only E _T radiated from the temperature measurement target 1.

However, when the lens 2 is directed toward the temperature measurement target 1, the lens 2 close to the temperature measurement target 1 is first affected by the radiant heat from the temperature measurement target 1 over time. When heated, T _L > T _S , and as a result, the energy E _L is emitted from the lens 2 having a high temperature toward the sensor 3 having a low temperature, and the energy incident on the sensor 3 is
It becomes E _T + E _L , and E _L becomes a factor of error.

After that, with the passage of time, the heat of the lens 2 is conducted through the case 4 to the sensor 3 as indicated by an arrow H, and when T _L = T _S again, the radiant energy from the lens 2 disappears. The energy incident on the sensor 3 is only E _T from the temperature measurement target 1. Further, for example, when the temperature is measured by moving from a place where the room temperature is 40 ° C. to a place where the temperature is 25 ° C., as shown in FIG. It was confirmed by the experiment of the present invention that a large measurement error occurs.

As described above, the measurement conditions change due to various factors such as the ambient temperature, the temperature of the temperature measurement object, the partial temperature difference of the infrared radiation thermometer, and the passage of time. Therefore, accurate measurement of temperature cannot be performed due to various measurement errors.

[0007]

Therefore, an infrared detecting device for correcting the error due to the temperature change of such a lens is proposed in Japanese Patent Laid-Open No. 2-196933. However, in this device, since the absolute temperature of the Fresnel lens is measured and corrected, the relative temperature between the sensor and the sensor cannot be specified, and especially in a measurement environment where the ambient temperature changes drastically, There was a problem that an error due to radiant energy could not be corrected and accurate temperature measurement could not be performed.

In view of the above problems, the present invention provides an infrared radiation thermometer capable of correcting a measurement error caused by the transfer of radiant energy between a lens and a sensor and always performing accurate temperature measurement. It is intended.

[0009]

The infrared radiation thermometer of the present invention for achieving the above object comprises a lens for condensing infrared rays emitted from a temperature measuring object and an infrared sensor for converting the infrared rays into an electric signal. And a calculating means for converting the electric signal into a unit of temperature, a lens temperature measuring means for measuring the temperature of the lens, a sensor temperature measuring means for measuring the temperature of the infrared sensor, and these temperature measuring means. Correction means for producing a correction signal by means of the above, conversion means for converting into a temperature signal using the signals of the calculation means and the correction means, and outputting this temperature signal
The output means for displaying is provided.

Further, it is preferable to use a thermopile for the infrared sensor, an optical convex lens for the lens, and a thermocouple for the lens temperature measuring means and the sensor temperature measuring means for more accurate temperature measurement. In this case, it is more preferable to provide a cold junction sensor on the thermopile and a cold junction compensating means for performing compensation based on the output signal of the cold junction sensor. It is also possible to switch the signals of the thermopile, the lens temperature measuring means, the sensor temperature measuring means, and the cold junction sensor by the input switching means, and perform the conversion processing and the correction processing by the software of the microcomputer.

[0011]

[Operation] Since the infrared radiation thermometer of the present invention has the above-mentioned configuration, the infrared radiation thermometer between the temperature of the lens detected by the lens temperature measuring means and the temperature of the sensor detected by the sensor temperature measuring means is From the temperature difference, the transfer of radiant energy between the lens and the sensor can be known, so it is possible to determine only the radiant energy that is incident on the sensor from the temperature measurement target, and even in a temperature measurement environment where the ambient temperature changes significantly Accurate temperature measurement is always possible.

When a thermopile is used for the infrared sensor, an optical convex lens is used for the lens, and a thermocouple is used for the lens temperature measuring means and the sensor temperature measuring means, the optical field characteristic of the lens is good, The temperature measurement range of the sensor is wide and it has excellent durability. Further, when a cold junction sensor is provided in the thermopile and a cold junction compensating means for compensating based on the output signal of the cold junction sensor is provided, the cold junction temperature can be calibrated and a more accurate temperature measurement can be performed. it can.

Further, when the signals of the thermopile, the lens temperature measuring means, the sensor temperature measuring means and the cold junction sensor are switched by the input switching means, and the conversion processing and the correction processing are performed by the software of the microcomputer, the conversion means and the correction are performed. The means can be simplified, and the device can be downsized.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. Example 1 of the present invention has a schematic structure as shown in FIG. 1, and includes a lens 12 that collects infrared rays emitted from the temperature measurement target 11, and an infrared sensor 13 that photoelectrically converts the collected infrared rays. According to the voltage output from the infrared sensor 13, in addition to the calculating means 14 for converting into a unit of temperature, a lens
Lens temperature measuring means 15 for detecting the temperature of 12 and infrared sensor 13
A sensor temperature measuring means 16 for detecting the temperature of the lens 12 and an electric signal corresponding to a temperature difference between the lens 12 and the infrared sensor 13 are generated based on signals output from the lens temperature measuring means 15 and the sensor temperature measuring means 16. The correction means 17 is included. And
Based on the output signals of the calculation means 14 and the correction means 17, the error-corrected temperature measurement value is output by the conversion means 18 as a temperature signal, and output by the output means 19 so that it can be visually or auditorily recognized. ·Is displayed.

As described above, the radiation of energy generated between the lens 12 and the infrared sensor 13 is compensated as an error due to the difference between the temperature of the lens 12 and the temperature of the infrared sensor 13, and the infrared sensor 13 measures through the lens 12. Since the temperature can be corrected, the temperature can be measured extremely accurately under any condition. Next, FIG.
And Example 2 of the present invention whose schematic structure is shown in FIG. 3 is applied to a portable infrared radiation thermometer which measures an absolute temperature with a resolution of 0.1 ° C. in a measurement range of −50 ° C. to + 500 ° C. . Inside the main body case 20, an inner case 21 having an optical Ge convex lens 12 and an infrared sensor (thermopile in this embodiment) 13 having high durability and good optical field characteristic is attached, and further, this thermopile is mounted. A cold junction sensor 22 for detecting the cold junction temperature of 13, a lens temperature measuring means (first thermocouple) 15 for detecting the temperature of the lens 12, and a sensor temperature measuring means (second for the thermopile 13). thermocouple)
16 and 16 are connected to the circuit board 23.

On this circuit board 23, the cold junction compensating means 24, the calculating means 14, the converting means 18, and the correcting means 17 shown in FIG.
Are mounted, and the display unit 25 exposed to the outside of the main body case 20 is also integrally mounted. A battery 26 is housed in the grip portion 20a of the main body case 20, and power is supplied to the circuit board 23. In the present embodiment, as shown in FIG.
It is attached to the inner side of the inner case 21. Then, the thermocouple wire 28 is taken out from the wiring hole 27 opened on the side surface of the inner case 21 and wired to the circuit board 23. In addition, the second thermocouple 16 is a thermopile 13
In order to measure the temperature of the thermopile 13, it is attached to the back side of the closed end 21a of the inner case 21 where the temperature becomes substantially the same as that of the thermopile 13. The first thermocouple 15 and the second thermocouple 16 are
Both have the structure shown in FIG. 5, and the ends of both thermocouple wires 28, which are the temperature-measuring contacts, are in contact with the surface of the center of the contact plate 29, which is 1.5 mm square by 0.05 mm thick. It has been fixed.

As these thermocouples, chromel-
Alumel, chromel-constantan, iron-constantan, copper-constantan, platinum rhodium-platinum and the like can be appropriately selected and used. According to this embodiment, the signal photoelectrically converted by the thermopile 13 is compensated by the cold junction sensor 22 and the cold junction compensating means 24, and
Since the error correction due to the temperature difference between the lens 12 and the thermopile 13 is performed by the first thermocouple 15 and the second thermocouple 16, the measurement error becomes extremely small as shown in FIG.
It can be seen that a significant improvement was seen compared to the conventional example shown in FIG.

Next, a third embodiment shown in FIG. 7 is a modification of the above-mentioned second embodiment, in which the cold junction compensating means 24 and the computing means of FIG.
Instead of 14, correction means 17 and conversion means 18, input switching means 30, A / D conversion means 31, and microcomputer 32 are used to simplify the apparatus. In addition, as shown in FIG. 8, a first thermocouple for measuring the temperature of the lens 12 is used.
15 is disposed on the front side of the lens 12, that is, on the side close to the temperature measurement target 11, and the second thermocouple 16 and the cold junction sensor 22 for measuring the temperature of the thermopile 13 are integrated with the thermopile 13. It is fixed to.

In the case of this embodiment, the input switching means 30 is operated by a command from the microcomputer 32, and the thermopile 13, the cold junction sensor 22, and the
Data is taken from the lens temperature measuring means (first thermocouple) 15 and the sensor temperature measuring means (second thermocouple) 16, and A /
The D conversion means 31 converts it into a digital signal corresponding to the measured temperature, the microcomputer 32 performs data processing, and an output means such as a display or a speaker.
Notify the measurer of the measured temperature through 19.

Also in the case of this embodiment, since the correction can be performed based on the temperature of the lens 12 and the relative temperature of the infrared sensor (thermopile) 13, accurate temperature measurement is always possible without being influenced by the environment to be measured. Becomes

[0021]

The infrared radiation thermometer of the present invention has a lens for condensing infrared rays radiated from an object to be measured, an infrared sensor for converting the infrared rays into an electric signal, and the electric signal for converting into a unit of temperature. Calculating means, lens temperature measuring means for measuring the temperature of the lens, sensor temperature measuring means for measuring the temperature of the infrared sensor, correction means for generating a correction signal by these temperature measuring means, and the calculation Since the conversion means for converting the temperature signal using the signals of the measuring means and the correcting means and the output means for outputting and displaying the temperature signal are provided, the temperature of the lens detected by the lens temperature measuring means and the sensor temperature measuring From the temperature difference between the temperature of the sensor and the temperature of the sensor detected by the means, the transfer of radiant energy between the lens and the sensor can be known, and only the radiant energy that is incident on the sensor from the temperature measurement object can be determined. It can be, even in the temperature measuring environment, such as ambient temperature changes significantly, it is always accurate temperature measurement.

When a thermopile is used for the infrared sensor, an optical convex lens is used for the lens, and a thermocouple is used for the lens temperature measuring means and the sensor temperature measuring means, the optical field characteristic of the lens is good, It is possible to provide an infrared radiation thermometer having a wide temperature measurement range of the sensor and excellent durability. Further, when a cold junction sensor is provided in the thermopile and a cold junction compensating means for compensating based on the output signal of the cold junction sensor is provided, calibration by the cold junction temperature can be performed, and more accurate temperature measurement can be performed. it can.

Further, when the signals of the thermopile, the lens temperature measuring means, the sensor temperature measuring means, and the cold junction sensor are switched by the input switching means and the conversion processing and the correction processing are performed by the software of the microcomputer, the conversion means and the correction are performed. The means can be simplified, and the device can be downsized.

[Brief description of drawings]

FIG. 1 is a block diagram of an infrared radiation thermometer according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an infrared radiation thermometer according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of the infrared radiation thermometer of FIG.

FIG. 4 is an enlarged sectional view of a sensor portion of the infrared radiation thermometer of FIG.

FIG. 5 is a perspective view of a thermocouple for measuring the temperature of the lens and the infrared sensor of FIG.

FIG. 6 is a characteristic diagram showing a measurement error by the infrared radiation thermometer of FIG.

FIG. 7 is a block diagram of an infrared radiation thermometer according to a third embodiment of the present invention.

8 is an enlarged sectional view of a sensor portion of the infrared radiation thermometer of FIG.

FIG. 9 is an enlarged sectional view of a sensor portion of a conventional infrared radiation thermometer.

10 is a characteristic diagram showing a measurement error by the infrared radiation thermometer of FIG. 9.

[Explanation of symbols]

 11 Temperature measurement target 12 Lens 13 Infrared sensor (thermopile) 14 Calculation means 15 Lens temperature measurement means (first thermocouple) 16 Sensor temperature measurement means (second thermocouple) 17 Correction means 18 Conversion means 19 Output means 22 Cold Contact sensor 24 Cold junction compensation means 30 Input switching means 32 Microcomputer

Claims (4)

[Claims] 1. A lens for condensing infrared rays emitted from a temperature measuring object, an infrared sensor for converting the infrared rays into an electric signal, a calculation means for converting the electric signal into a unit of temperature, and a temperature of the lens. A lens temperature measuring means for measuring the temperature of the infrared sensor, a sensor temperature measuring means for measuring the temperature of the infrared sensor, a correcting means for generating a correction signal by these temperature measuring means, and a signal of the calculating means and the correcting means. An infrared radiation thermometer equipped with a conversion means for converting the temperature signal and an output means for outputting and displaying the temperature signal. 2. The infrared radiation according to claim 1, wherein a thermopile is used for the infrared sensor, an optical convex lens is used for the lens, and a thermocouple is used for the lens temperature measuring means and the sensor temperature measuring means. thermometer. 3. The infrared radiation thermometer according to claim 2, wherein the thermopile is provided with a cold junction sensor, and cold junction compensation means for compensating based on an output signal of the cold junction sensor is provided. . 4. The thermopile, lens temperature measuring means, sensor temperature measuring means, and cold junction sensor signals are switched by an input switching means, and conversion processing and correction processing are performed by software of a microcomputer. Infrared radiation thermometer described in.