JPH0523119U - Heat dissipation type absolute humidity sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a highly accurate heat dissipation type absolute humidity sensor by increasing the temperature change of the thermistor due to the change of absolute humidity more than ever before. [Structure] The heat dissipation type absolute humidity sensor of the present invention is characterized by having vibrators (5a, 5b) for vibrating the thermistors (1, 2).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat-dissipating absolute humidity sensor for detecting the amount of water vapor in an atmosphere such as an air conditioner, a dehumidifier, a cooker, and a greenhouse.

[0002]

[Prior Art]

 In recent years, there is an increasing demand for detection control of humidity (either relative humidity or absolute humidity) in air conditioners, dehumidifiers, cookers, cultivation houses and the like. To meet this demand, various types of humidity sensors have been announced.

The conventional heat dissipation type absolute humidity sensor shown in FIG. 5 includes a thermistor 1 (resistance value R _HT ) and thermistor 2 (resistance value R _T ), fixed resistances R ₁ , R ₂ , R ₃ , R. ₄ by Ri to form a Wheatstone bridge as shown in FIG. 4 to be used. However, the temperature-resistance characteristics of R _T and R _HT must be the same, and the resistance values of R ₂ and R ₃ must also be the same. Referring to FIG. 5, the thermistor 2 is enclosed in a dry atmosphere by an outer frame 6a, and the thermistor 1 is exposed to the outer air by an outer frame 6b having a hole 6b-1. At this time, the voltage V _IN applied to the thermistors 1 and 2 causes the thermistors 1 and 2 to self-heat and become higher than the ambient temperature. The temperature of the thermistors 1 and 2 is determined by the difference between the electric power applied to the thermistors 1 and 2 and the heat dissipation of the thermistors 1 and 2. When water vapor is contained in the outside air, the heat dissipation becomes larger than that in the case where water vapor is not contained, so that the temperature of the thermistor 1 becomes lower than that of the thermistor 2. Therefore, a potential difference V _OUT is generated across the fixed resistor R ₃ . This phenomenon can be used to detect the absolute humidity in the atmosphere.

[0004]

[Problems to be solved by the device]

 However, the temperature change of the thermistor 1 due to the change of the absolute humidity in the air is very small, and the accuracy is not good.

Therefore, a technical problem of the present invention is to obtain a heat dissipation type absolute humidity sensor which increases the temperature change of the thermistor due to the change of absolute humidity in the air and has high accuracy.

[0006]

[Means for Solving the Problems]

 According to the present invention, by detecting the temperature difference between one thermistor for temperature detection sealed in an atmosphere containing no water vapor and the other thermistor for detecting the temperature of air containing water vapor, In a heat dissipation type absolute humidity sensor for detecting absolute humidity in air, there is provided a heat dissipation type absolute humidity sensor characterized by having a vibrator for vibrating the thermistor.

[0007]

[Action]

 When the thermistor vibrates by attaching the thermistor to the oscillator, the efficiency of cooling the thermistor by air increases. As a result, the temperature change of the thermistor due to the change of absolute humidity in the air becomes large.

[0008]

【Example】

 A heat dissipation type absolute humidity sensor according to an embodiment of the present invention will be described with reference to the drawings. The heat dissipation type absolute humidity sensor of the present invention has a piezoelectric vibrator 5 that vibrates the thermistors 1 and 2. 2 and 3, a plate-shaped piezoelectric material 9 is attached below a plate-shaped spring material 8 such as SUS304 with an adhesive 11. Electrodes 12 and 12 are provided on the upper surface and the lower surface of the piezoelectric material 9, respectively. When an AC voltage is applied to the electrodes 12, 12, the piezoelectric material 9 expands and contracts in the thickness direction and the direction perpendicular to the thickness direction. Therefore, the leaf spring material 8 flexurally vibrates in the thickness direction.

One end of each of the piezoelectric vibrators 5a and 5b is fixed by the terminal fixing members 3, 3, 3 and 3, and hooks 10 and 10 for fixing the thermistors 1 and 2 are respectively attached to the surfaces of the plate-shaped spring material 8 at the other ends. The thermistor 1 and the thermistor 2 are fixed to the hooks 10 and 10. After that, the piezoelectric vibrator 5a with the thermistor 2 fixed is fixed in the outer frame 6a sealed in dry air, and the piezoelectric vibrator 5b with the thermistor 1 fixed has a hole 6b-2 so that the piezoelectric vibrator 5b is exposed to the outside air. It is fixed in the frame 6b. As described above, the diffusion type absolute humidity sensor of the present invention is obtained.

The cooling efficiency of the thermistors 1 and 2 is related to the amount of gas molecules contacting the thermistors 1 and 2 per unit time and the amount of heat taken by the gas molecules from the thermistors 1 and 2. It is considered that the temperature of the thermistor 1 becomes lower than that of the thermistor 2 when the amount of water vapor increases because the amount of heat taken by the thermistor 1 is larger than that of the gas molecules in the outside air.

Further, even if the amount of water vapor in the outside air is the same, if the amount of water vapor contacting the thermistor 1 per unit time is large, the cooling efficiency of the thermistor 1 is high. For this reason, when the thermistor 1 is vibrated by the piezoelectric vibrator 5b, the amount of water vapor contacting the thermistor 1 increases, so that the cooling efficiency of the thermistor 1 increases. Similarly, the thermistor 2 is vibrated by the piezoelectric vibrator 5a, and the temperature change of the thermistor due to a change in absolute humidity in the air can be detected by increasing it.

[0012]

[Effect of the device]

 As described above, according to the present invention, the temperature change of the thermistor due to the change of the absolute humidity becomes larger than that of the conventional one, and there is an effect that a highly accurate heat dissipation type absolute humidity sensor can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of a heat dissipation type absolute humidity sensor of the present invention.

FIG. 2 is an external view of a piezoelectric vibrator 5 to which a thermistor 1 (or thermistor 2) is fixed.

FIG. 3 is a cross-sectional view of a piezoelectric vibrator 5.

FIG. 4 is a circuit when a heat dissipation type absolute humidity sensor is used.

FIG. 5 is a schematic diagram of a conventional heat dissipation type absolute humidity sensor.

[Explanation of symbols]

1 Thermistor 2 Thermistor 3 Terminal fixing material 4 Terminal 5 Piezoelectric vibrator 6 Outer frame 7 Lead solid wire 8 Plate spring material 9 Piezoelectric material 10 Hook 11 Adhesive 12 Electrode V _IN Applied voltage V _OUT Output voltage R _HT Thermistor 1 Resistance R _T thermistor 2 resistance R ₁ , R ₂ , R ₃ , R ₄ fixed resistance

Claims (1)

[Scope of utility model registration request] 1. In the air, by detecting a temperature difference between one thermistor for temperature detection sealed in an atmosphere not containing water vapor and the other thermistor for detecting the temperature of air containing water vapor. A heat-dissipating absolute humidity sensor for detecting absolute humidity, comprising a vibrator for vibrating the thermistor.