JPS637339B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature and humidity measuring device that measures temperature and humidity.

Conventionally, temperature and humidity measuring devices simply measure and display dry bulb temperature and wet bulb temperature, and it is extremely inconvenient that relative humidity must be determined using a conversion table.
In addition, to directly indicate relative humidity, it is necessary to measure the dry bulb temperature and wet bulb temperature with a temperature/humidity detector, and then calculate and display the relative humidity with a temperature/humidity converter, which increases the number of devices. However, there are disadvantages in that it requires a lot of wiring, requires a large storage space, and is complicated and expensive. Furthermore, when measuring temperature and humidity using a thermocouple or the like, any variation in precision between two inputs directly results in a calculation error, making it difficult to measure and display with high precision.

In view of the above points, an object of the present invention is to provide a temperature/humidity measuring device capable of measuring temperature/humidity with high accuracy using one device.

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 11 and 12 are input terminals to which thermocouples are connected and dry bulb temperature input signals and wet bulb temperature input signals are supplied, and 2 is input terminal 1.
1, 12 is an input switch that takes out the input signal supplied by switching switches 21, 22 such as reed relays; 3 is a reference junction compensator that superimposes a compensation voltage on the signal taken out by the input switch 2; 4 is an amplifier that amplifies the output of the reference junction compensator 3, 5 is an A-D converter that converts the output of the amplifier 4 into a digital signal, 6 is a central processing unit such as a microcomputer that performs arithmetic processing, etc., and 7 is an amplifier that amplifies the output of the reference junction compensator 3; A-
A storage device that stores the output of the D converter and the processing program of the central processing unit 6; 8 is a display device that digitally displays temperature and humidity;
Further, S is a short-circuit switch provided on the input side of the amplifier 4. Note that the input terminals 11 and 12 other than the input switch 2 and the reference junction compensator 3 are connected by a thermocouple or a compensation lead wire.

Note that thermocouples generally have a temperature measuring junction and input terminal 1.
Although the thermoelectromotive force corresponding to the temperature difference between the reference junctions 1 and 12 (room temperature) can be extracted, the voltage output of the input terminals 11 and 12 is insufficient for the room temperature.

In order to add the compensation voltage for room temperature and obtain an electromotive force from 0° C., the compensation voltage is superimposed on the input signal by the reference junction compensator 3.

The input signals ei ₁ , which are supplied to the input terminals 11 and 12 by opening the short circuit switch S and sequentially opening and closing the changeover switches 21 and 22 of the input changeover device 2
ei ₂ is taken in, a compensation voltage Eo is superimposed on it by the reference junction compensator 3, and it is amplified by the amplifier 4.
It is converted into a digital signal by the AD converter 5 and stored in the memory 7 by the central processing unit 6.

At this time, if the amplification degree of the amplifier 5 is A and the drift voltage is △e, then the input signal stored in the memory 7
The signals ei _{1 ′} and ei _{2 ′} converted into digital signals by the AD converter 5 of ei ₁ and ei ₂ are expressed by the following equations.

ei ₁ ′=(ei ₁ +Eo+△e)A ……(1) ei ₂ ′=(ei ₂ +Eo+△e)A ……(2) Also, the short-circuit switch S is also The reference voltage eo is expressed by the following equation:
is stored in the storage device 7.

eo=△eA...(3) The central processing unit 6 always performs an operation to subtract equation (3) from equations (1) and (2), and obtains a drift-compensated signal eo ₁ = ei ₁ ′−eo= (ei ₁ +Eo+△e)A −△eA=(ei ₁ +Eo)A …(4) eo ₂ =ei ₂ ′−eo=(ei ₂ +Eo+△e)A −△eA=(ei ₂ +Eo)A ...(5) is obtained. Furthermore, the central processing unit 6 generates the correct drift-compensated dry bulb temperature signals shown in (4) and (5).
For eo ₁ and wet bulb temperature signal eo ₂ , since the input signal is a thermocouple input, the output of the A-D converter 5 has a non-linear relationship with respect to temperature, so a linearization calculation is performed to make it have a linear relationship with temperature. are applied to set T _D and T _W , relative humidity is calculated according to Pernter's equation shown below, and the temperature and relative humidity H are indicated on the display 8.

H=e/es×100(%RH) ……(6) e=ew−AP(1+T _W /C)(T _D −T _W )
...(7) where H: relative humidity e: saturated water vapor pressure of air ew: saturated water vapor pressure at wet bulb temperature es: saturated water vapor pressure at dry bulb temperature T _W : wet bulb temperature T _D : dry bulb temperature P: air Pressures A and C: constants determined by wind speed, etc. As described above, the present invention compensates and amplifies the dry bulb temperature signal and wet bulb temperature signal taken in by the input switch using the reference junction compensator. The signal is D-converted and stored in the memory, and the difference between the signal obtained by closing the short-circuit switch installed on the input side of the amplifier is calculated, and after linearization, the relative humidity calculation is performed by the central processing unit. It is a temperature and humidity measuring device.

Therefore, a dry bulb temperature signal and a wet bulb temperature signal can be directly inputted with one device, and a display of dry bulb temperature and relative humidity can be easily obtained. In addition, by providing a short-circuit switch, amplifier drift is removed, and since the input signal from the thermocouple is directly switched, only one reference junction compensator is required, and there is no error between input signals, allowing for highly accurate temperature and Can measure humidity. Moreover, since it is a digital type using a central processing unit, high speed and high accuracy measurement is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. 11, 12...Input terminal, 2...Input switch, 2
1, 22...Switchover switch, 3...Reference junction compensator,
4...Amplifier, 5...A-D converter, 6...Central processing unit, 7...Storage device, S...Switch for short circuit.

Claims (1)

[Claims] 1. An input terminal to which a dry bulb temperature input signal and a wet bulb temperature input signal are supplied, an input switch that sequentially switches and outputs the input signals supplied to this input terminal with a changeover switch, and this input A reference junction compensator that superimposes a compensation voltage on the signal taken out by the switch, an amplifier that amplifies this compensated signal, an A-D converter that converts the output of this amplifier into a digital signal, and this A- a memory that stores the output of the D converter; a shorting switch provided on the input side of the amplifier; and a difference between the input signal value stored in the memory and the signal value when the shorting switch is closed. A temperature/humidity measuring device comprising: a central processing unit that performs calculation and linearization, and then calculates relative humidity from the dry bulb and wet bulb temperature values. 2. The temperature and humidity measuring device according to claim 1, further comprising: a display device for displaying the dry bulb temperature value and the calculated relative humidity value.