An infrared thermometer

Abstract

The present invention relates to an infrared thermometer, which includes a housing and an infrared thermopile sensor. A temperature measurement window is provided on the housing. It further includes an air inlet channel, an air return channel, and a hollow constant temperature cavity. The constant temperature cavity is arranged inside the housing and corresponds to the temperature measurement window. The infrared thermopile sensor is arranged inside the constant temperature cavity. An air inlet and an air return port are respectively provided on the cavity wall of the constant temperature cavity. The air inlet channel and the air return channel are respectively arranged inside the housing and outside the constant temperature cavity. One end of the air inlet channel is arranged on the air inlet, and one end of the air return channel is arranged on the air return port. A unidirectional air flow cycle is formed between the other end of the air inlet channel and the other end of the air return channel. The infrared thermometer of the present invention can reduce or eliminate the influence of factors such as low temperature environment on the thermometer itself and is applicable to low temperature environment conditions.

Description

Technical Field

[0001] The present invention relates to a body temperature detection device, and particularly to an infrared thermometer. Background Art

[0002] Currently, the general requirement for the operating environment temperature of infrared temperature measurement products is 16°C to 35°C. In the cold winter, the instrument is prone to serious deviation or even unable to display when used outdoors for a long time.

[0003] Currently, the commonly used infrared sensor in infrared thermometers is a thermopile infrared sensor, which has mature technology and moderate cost. As one of the main variables in the infrared-body temperature calculation formula of the sensor, the ambient temperature determines that it has certain requirements for the operating environment temperature, generally within the range of 16°C to 35°C.

[0004] The influence of the ambient temperature is the influence on the temperature of the thermopile sensor itself. The purpose of placing the thermometer in a specific environment for a period of time before use is to make the temperature of the sensor itself reach equilibrium with the ambient temperature. This temperature is measured by a thermistor built into the thermopile sensor and then transmitted to the infrared sensor for ambient temperature correction.

[0005] At the same time, the thermopile sensor is also easily affected by external thermal radiation pollution, such as the body temperature of the operator, the radiation heat source of other or the object being measured, and ambient temperature fluctuations, resulting in temperature drift in the measured value. These factors all make the infrared thermometer inapplicable to low-temperature environments. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: to provide an infrared thermometer that can eliminate the influence of ambient temperature and other non-related thermal radiation on the infrared thermopile sensor, so that the infrared thermometer is applicable to low-temperature environments.

[0007] To solve the above technical problem, the technical solution adopted by the present invention is:

[0008] An infrared thermometer, comprising a housing and an infrared thermopile sensor. A temperature measurement window is provided on the housing. It further includes an air intake channel, an air return channel, and a hollow constant temperature cavity. The constant temperature cavity is arranged inside the housing and corresponds to the temperature measurement window. The infrared thermopile sensor is arranged inside the constant temperature cavity. An air intake port and an air return port are respectively provided on the cavity wall of the constant temperature cavity. The air intake channel and the air return channel are respectively arranged inside the housing and outside the constant temperature cavity. One end of the air intake channel is arranged on the air intake port, and one end of the air return channel is arranged on the air return port. A unidirectional air flow circulation is formed between the other end of the air intake channel and the other end of the air return channel.

[0009] The beneficial effects of the present invention are as follows:

[0010] Through the design of the above-mentioned constant-temperature cavity, the infrared thermopile sensor is arranged in the constant-temperature cavity, and the constant temperature of the infrared thermopile sensor is controlled (controlled at 25 °C) through the constant-temperature cavity, reducing or eliminating the influence of factors such as low-temperature environment on the thermometer, and further making the infrared thermometer applicable to low-temperature environments. Description of the Drawings

[0011] Figure 1 It is a schematic diagram of the overall structural connection of the infrared thermometer according to the embodiment of the present invention.

[0012] Label Description:

[0013] 1. Housing; 2. Infrared thermopile sensor; 3. Air intake channel; 4. Air return channel; 5. Constant-temperature cavity; 6. Temperature control unit; 7. Heating element; 8. Thermistor; 9. Collector; 10. Signal amplifier; 11. Processor; 12. Temperature sensor; 13. Air filter; 14. Fan; 15. Temperature measurement window; 16. Filter; 17. Air supplement channel. Detailed Embodiments

[0014] To describe in detail the technical content, achieved objectives and effects of the present invention, the following is described in conjunction with the embodiments and accompanied by the drawings.

[0015] The most crucial concept of the present invention is: arranging the infrared thermopile sensor in the constant-temperature cavity and proposing a simplified algorithm for infrared radiation-body temperature that does not require environmental temperature correction for it.

[0016] Please refer to Figure 1 , an infrared thermometer, including a housing and an infrared thermopile sensor, a temperature measurement window is provided on the housing, and it further includes an air intake channel, an air return channel and a hollow constant-temperature cavity. The constant-temperature cavity is arranged in the housing and corresponds to the temperature measurement window. The infrared thermopile sensor is arranged in the constant-temperature cavity. An air inlet and an air return port are respectively provided on the cavity wall of the constant-temperature cavity. The air intake channel and the air return channel are respectively arranged in the housing and outside the constant-temperature cavity. One end of the air intake channel is arranged on the air inlet, one end of the air return channel is arranged on the air return port, and a one-way air flow cycle is formed between the other end of the air intake channel and the other end of the air return channel.

[0017] From the above description, the beneficial effects of the present invention are as follows:

[0018] Through the design of the above-mentioned constant-temperature cavity, the infrared thermopile sensor is arranged in the constant-temperature cavity, and the constant temperature of the infrared thermopile sensor is controlled (controlled at 25 °C) through the constant-temperature cavity, reducing or eliminating the influence of factors such as low-temperature environment on the thermometer, without the need to correct the environmental temperature parameters of the sensor, improving the stability and applicability of the device, and further making the infrared thermometer applicable to low-temperature environments.

[0019] Furthermore, it further includes a temperature control unit and a heating element. The temperature control unit is electrically connected to the heating element, and the heating element is disposed on the air intake passage.

[0020] As can be seen from the above description, as a specific structural example of constant temperature control, the above temperature control unit and heating element can be designed. The air on the air intake passage flows through the heating element, and the temperature control unit controls the heating element to heat the passing air. The air heated to the required temperature flows into the constant temperature cavity from the air intake port, and then flows to the return air passage through the return air port, forming a one-way air flow cycle. Furthermore, the constant temperature cavity and the temperature control unit form a cycle to ensure that the temperature in the cavity is stably controlled at the required temperature (25 °C).

[0021] Furthermore, it further includes a thermistor, a heat collector, a signal amplifier, and a processor. The thermistor and the heat collector are respectively disposed in the constant temperature cavity. The thermistor is disposed on the attachment base plate of the heat collector and is close to the heat collector. The thermistor is electrically connected to the temperature control unit; the signal amplifier and the processor are respectively disposed in the housing and outside the constant temperature cavity, and the heat collector is electrically connected to the processor via the signal amplifier.

[0022] Furthermore, it further includes a temperature sensor. The temperature sensor is disposed outside the housing and is electrically connected to the processor.

[0023] As can be seen from the above description, as a specific structural example, the thermistor is placed on the attachment base plate of the heat collector, as close as possible to the heat collector, for monitoring the ambient temperature in the constant temperature cavity and feeding it back to the temperature control unit. The heat collector converts the received infrared radiation energy through the signal amplifier for A / D conversion and then transmits it to the processor for processing. The temperature sensor disposed outside the housing is used to measure the actual ambient temperature of the measured human body and transmit the measured ambient temperature to the single-chip microcomputer for processing.

[0024] Furthermore, the processor is a single-chip microcomputer.

[0025] As can be seen from the above description, as a specific structural example, the processor is a single-chip microcomputer.

[0026] Furthermore, the material of the constant temperature cavity is a heat-insulating material.

[0027] As can be seen from the above description, as a specific structural example, the material of the constant temperature cavity is a heat-insulating material to avoid heat exchange with the outside.

[0028] Furthermore, it further includes an air filter. The air filter is disposed on the air intake passage, and the air filter and the heating element are arranged in sequence along the air intake direction.

[0029] As can be seen from the above description, as a specific structural example, an air filter can be added to filter out dust in the air so that it meets certain cleanliness requirements and then enters the constant-temperature cavity.

[0030] Furthermore, it also includes a fan. The air outlet of the fan is connected to the other end of the intake passage, and the other end of the return air passage is connected to the air return port of the fan, forming a one-way air flow circulation through the fan.

[0031] Furthermore, an air supplement passage is provided on the fan, and a valve is provided on the air supplement passage.

[0032] As can be seen from the above description, as a specific structural example, the above fan can be designed to achieve a one-way air flow circulation. The air supplement passage is used to make up for the leakage air volume of the entire air flow circulation system.

[0033] Furthermore, a filter film is provided on the cavity wall of the constant-temperature cavity, and the filter film is arranged corresponding to the temperature measurement window.

[0034] In practical applications, the influence of the ambient temperature on the infrared thermometer includes two parts. One is the influence on the temperature sensing performance of the infrared sensor itself, and the other is the influence on the infrared radiation of the surface of the measured human body.

[0035] The suitable temperature for the infrared thermopile sensor is 16°C to 35°C, preferably 25°C. Therefore, the temperature of the constant-temperature cavity is controlled by the temperature control unit to be stable at 25°C ± 0.3°C. The thermistor has high stability of its parameters under the condition of 25°C, and only the nominal value under the condition of 25°C needs to be calibrated. For the infrared thermometer of the present invention, the temperature of the infrared thermopile sensor itself is designed to be controlled at 25°C. Further, a standard black body is adopted to perform calibration at different ambient temperatures to obtain the influence of different ambient temperatures on the measured black body, and a polynomial fitting is performed on the output curve of the sensor to obtain the corresponding correction coefficient, and there is no need to compensate for the ambient temperature anymore. Further, combined with Planck's law, for an object with temperature T obj The radiation power per unit area of which at all wavelengths can be expressed as: P obj = kεT obj ;

[0036] Where: k is the Boltzmann constant, ε is the emissivity of the object, and ε ∈ [0, 1].

[0037] The sensitivity coefficient β of the infrared thermopile sensor under the condition of 25°C 25 , which is determined by the sensitivity of the sensor itself under the condition of 25°C and is a constant.

[0038] The fitting curve of the influence of the ambient temperature where the measured human body is located on the result measured by the sensor, and its coefficient is expressed as δ en, this coefficient can be combined with the ambient temperature T measured by the thermocouple sensor at the housing en The fitting curve is obtained. By placing a standard black body in an environmental test chamber and conducting a series of ambient temperature experiments, the influence function relationship of this coefficient can be determined in advance.

[0039] Therefore, in this design, the output voltage of the infrared thermopile sensor can be simplified to the relationship between the measured human body radiation temperature and the ambient temperature: U = β 25 δ en P obj = β 25 δ en kεT obj = φ(T en )T obj . φ is a function of ambient temperature.

[0040] Please refer to Figure 1 , Example 1 of the present invention is as follows:

[0041] The infrared thermometer in this embodiment is an infrared forehead thermometer, which includes a housing 1, an infrared thermopile sensor 2, an air intake channel 3, an air return channel 4, a constant temperature cavity 5, a temperature control unit 6, a heating element 7, a thermistor 8, a collector 9, a signal amplifier 10, a processor 11, a temperature sensor 12, an air filter 13 and a fan 14. The processor in this embodiment is a single-chip microcomputer, and the temperature sensor in this embodiment selects a thermocouple temperature sensor.

[0042] A temperature measurement window 15 is provided on the housing 1. The air intake channel 3, the air return channel 4, the constant temperature cavity 5, the temperature control unit 6, the heating element 7, the signal amplifier 10, the processor 11, the air filter 13 and the fan 14 are all arranged inside the housing 1. A filter 16 is provided on the cavity wall of the constant temperature cavity 5, and the filter 16 is arranged corresponding to the temperature measurement window 15.

[0043] The infrared thermopile sensor 2, the thermistor 8 and the collector 9 are all arranged inside the constant temperature cavity 5. An air inlet and an air return port are respectively provided on the cavity wall of the constant temperature cavity 5. The air intake channel 3 and the air return channel 4 are located outside the constant temperature cavity 5. One end of the air intake channel 3 is arranged on the air inlet, one end of the air return channel 4 is arranged on the air return port, the other end of the air intake channel 3 is connected to the air outlet of the fan 14, and the other end of the air return channel 4 is connected to the air return port of the fan 14, forming a unidirectional air flow cycle through the fan 14.

[0044] This embodiment provides a constant temperature environment for the infrared thermopile sensor. Air comes out of the air outlet of the fan 14 and enters the air filter 13. After filtering out the dust in the air to meet certain cleanliness requirements, it enters the temperature control unit 6. The temperature control unit 6 controls the heating element 7 to heat the passing air. Under the adjustment and control of the heating element 7 and the temperature control unit 6, the incoming air is kept constant at 25°C ± 0.3°C, and then enters the constant temperature cavity 5 where the infrared thermopile sensor is located, and then returns to the fan 14 through the air return port for collection and circulation to form a closed loop.

[0045] The thermistor 8 is placed on the attachment bottom plate of the collector 9 as close as possible to the collector 9, and is used to monitor the environmental temperature in the constant temperature cavity 5 and feedback it to the temperature control unit 6.

[0046] The collector 9 converts the received infrared radiation energy through A / D conversion and then transmits it to the single-chip microcomputer for processing.

[0047] The (thermocouple) temperature sensor 12 is installed on the housing 1 and is used to measure the actual environmental temperature where the human body to be measured is located, and transmit the measured environmental temperature to the single-chip microcomputer for processing.

[0048] An air supplement channel 17 is also provided on the fan 14, and a valve can be set on the air supplement channel 17 as needed to make up for the leaked air volume of the system.

[0049] The constant temperature cavity 5 is encapsulated with heat-insulating materials to avoid heat exchange with the outside world.

[0050] The processor 11 selects a single-chip microcomputer, and can be controlled through the buttons on the single-chip microcomputer, and the body temperature can be displayed through the single-chip microcomputer.

[0051] The intake channel 3, the return air channel 4, the constant temperature cavity 5, the temperature control unit 6, the heating element 7, the signal amplifier 10, the processor 11, the air filter 13 and the fan 14 can be fixed in the housing 1 by existing fixing methods, and the fixing of the infrared thermopile sensor 2 in the constant temperature cavity 5 can also be carried out by existing fixing methods, which will not be elaborated here.

[0052] This embodiment provides a stable, constant temperature and clean operating environment for the infrared thermopile sensor, overcomes the influence of the environmental temperature on the infrared thermopile sensor, enables the infrared thermometer to be used at a lower environmental temperature, and maintains high stability and accuracy.

[0053] At the same time, combined with the sensitivity coefficient β of the infrared thermopile sensor under the condition of 25°C 25 and the influence coefficient δ of the environmental temperature on the radiation of the human body surface temperature en , the output characteristic formula U = φ(T en )T obj ;

[0054] The design of the present invention is of great significance for expanding the environmental conditions for the use of infrared thermometers and improving the stability and accuracy of temperature measurement.

[0055] In summary, the infrared thermometer provided by the present invention can reduce or eliminate the influence of factors such as low-temperature environment on the thermometer and is applicable to low-temperature environments.

[0056] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in the related technical field, shall be equally included in the patent protection scope of the present invention.

Claims

1. An infrared thermometer, the infrared thermometer being an infrared forehead thermometer, comprising a housing, an infrared thermopile sensor, a temperature control unit, a heating element, a thermistor, a collector, a signal amplifier, a processor and a blower. A temperature measurement window is provided on the housing, and it is characterized in that, It further includes an air intake channel, a gas return channel, and a hollow constant temperature cavity. The constant temperature cavity is arranged inside the housing and corresponds to the temperature measurement window. The infrared thermopile sensor is arranged inside the constant temperature cavity. An air inlet and a gas return port are respectively arranged on the cavity wall of the constant temperature cavity. The air intake channel and the gas return channel are respectively arranged inside the housing and outside the constant temperature cavity. One end of the air intake channel is arranged on the air inlet, and one end of the gas return channel is arranged on the gas return port. A unidirectional air flow circulation is formed between the other end of the air intake channel and the other end of the gas return channel; The thermistor and the collector are respectively arranged inside the constant temperature cavity. The thermistor is arranged on the attachment bottom plate of the collector and is close to the collector. The thermistor is point-connected to the temperature control unit; The signal amplifier and the processor are respectively arranged inside the housing and outside the constant temperature cavity. The collector is electrically connected to the processor via the signal amplifier; The collector converts the received infrared radiation energy through A / D conversion and then transmits it to the processor for processing; The air outlet of the blower is connected to the other end of the air intake channel, and the other end of the gas return channel is connected to the air return port of the blower, forming a unidirectional air flow circulation through the blower; A gas supplement channel is arranged on the blower, and a valve is arranged on the gas supplement channel; The temperature control unit is electrically connected to the heating element, and the heating element is arranged on the air intake channel.

2. The infrared thermometer according to claim 1, characterized in that, It further includes a temperature sensor, which is arranged outside the housing and is electrically connected to the processor.

3. The infrared thermometer according to claim 1, characterized in that, The processor is a single-chip microcomputer.

4. The infrared thermometer according to claim 1, characterized in that, The material of the constant temperature cavity is a heat-insulating material.

5. The infrared thermometer according to claim 1, characterized in that, It further includes an air filter, which is arranged on the air intake channel, and the air filter and the heating element are arranged in sequence along the air intake direction.

6. The infrared thermometer according to claim 1, characterized in that, A filter film is arranged on the cavity wall of the constant temperature cavity, and the filter film corresponds to the temperature measurement window.

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