JPH03138553A - Humidity measuring instrument - Google Patents

Abstract

PURPOSE:To facilitate the replacement of a humidity detecting element and to reduce the cost by providing a humidity detecting element and a reference humidity information storage means storing information on the reference humidity of the detecting element on a replaceable unit. CONSTITUTION:The resistance variation type humidity detecting element 2 and an element correction information circuit 3 are provided in the unit 1 which is replaceable from the measuring instrument. A CPU 9 calculates humidity according to the resistance value Rx of the humidity detecting element 2 and element correction information R0(Ta) which is set to the resistance value of relative humidity (RH) 60% (reference humidity) and the calculated humidity Hx is displayed 10. Namely, the unit 1 is replaced with new one to not only mounts a new humidity detecting element 2, but also provide new reference humidity information corresponding to the new element 2, so that the circuit in the instrument need not be readjusted. Consequently, the replacement of the humidity detecting element is facilitated and the cost is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a humidity measuring device using a humidity detection element that converts humidity into an electrical signal.

(B) Conventional technology The electrical characteristic values (resistance value, capacitance value, etc.) of the humidity detection element change depending on the humidity of the atmosphere.

For example, to explain one type of humidity detection element whose resistance value changes, a ruthenium oxide (RuO□) electrode is formed on a ceramic plate, and L i N b O Forms a moisture-sensitive film based on lead borosilicate. This moisture-sensitive membrane is porous and adsorbs moisture in the atmosphere, and forms an electrolyte with the adsorbed moisture and Li ions.

Therefore, the higher the humidity, the more water is adsorbed, the more electrolyte is formed, and the resistance value of the moisture-sensitive membrane decreases.

FIG. 6 is a block diagram illustrating the configuration of a humidity measuring device using this humidity detecting element. The AC signal from the oscillation circuit section 32 is applied to the humidity detection element 41 in the element drive circuit section 33. The signal output from the element drive circuit section 33 is rectified by a rectifier circuit section 34 and further logarithmically compressed by a logarithmic compression circuit 35. The temperature correction circuit 36 performs temperature correction on the logarithmically compressed signal based on the temperature detected by the temperature detection element 37.

The signal output from the sensor section A is converted into a digital signal by an analog/digital (A/D) converter 38 and taken into a display circuit section 39. The display circuit section 39 displays the obtained humidity on the display 40.

(c) Problems to be Solved by the Invention In the above-mentioned humidity detecting element, dust and mist are adsorbed to the moisture-sensitive film, which prevents moisture adsorption and deteriorates the performance. Furthermore, when dew condensation occurs on the moisture-sensitive membrane and water droplets flow away from the moisture-sensitive membrane, ions in the moisture-sensitive membrane are lost, resulting in a significant deterioration of performance. Therefore, it is necessary to replace the humidity detection element with a new one every six months to a year.

However, it is currently difficult to manufacture a humidity detection element with uniform characteristics over a wide humidity measurement range. Therefore, if you select humidity sensing elements with uniform characteristics, the yield will drop significantly.
There was a problem in that the price of the humidity detection element was rising.

Therefore, it is conceivable that the variation in the humidity detection element is allowed to some extent, and the compatibility of the humidity detection element itself is impaired, and that the variation is corrected exclusively by adjusting the circuit within the sensor section A. However, this adjustment requires a humidity generation tank and a hygrometer for calibration, and is not something that ordinary users can easily perform. Therefore, it is necessary to request the manufacturer to recalibrate the humidity detection element when replacing it, or to replace the sensor section A itself with a new one, which ends up being expensive.

The present invention has been made in view of the above, and relates to a humidity measuring device that allows humidity detecting elements to be replaced easily and at low cost.

(d) Means and operation for solving the problems In order to solve the above problems, the humidity measuring device of the present invention includes a temperature detection element and a reference humidity information storage that stores information at a reference humidity of the humidity detection element. and means on a replaceable unit, and humidity calculating means for calculating humidity based on the signal of the humidity detecting element and information stored in the reference humidity information storage means.

In the humidity measuring device of the present invention, the reference humidity information for correcting variations in characteristics of the humidity detecting element is integrated with the humidity detecting element. If this unit is replaced with a new one, not only will the humidity detection element be new, but the reference humidity information will also be changed to correspond to the new humidity detection element, and there is no need to readjust the circuit within the humidity measurement device.

Therefore, variations in humidity detection elements can be tolerated to some extent, and the yield can be improved and the price can be reduced. In addition, the humidity detection element can be easily replaced by simply replacing the unit with a new one, and can be easily performed by general users, which also reduces the cost of replacing the humidity detection element.

(E) Example (Example 1) A first example of the present invention will be described below based on FIGS. 1 to 3.

FIG. 1 is a block diagram illustrating the circuit configuration of the humidity measuring device according to this embodiment. The unit 1 is provided to be replaceable with respect to the humidity measuring device, for example, via a card edge type connector or the like. In this unit 1, a variable resistance humidity detection element 2 and an element correction information circuit 3 are provided.

The element correction information circuit 3 is a series-parallel circuit of a temperature-sensitive resistance element RT, a fixed resistor RI, and a variable resistor ■8, and the combined resistance value (element correction information) RO (T-) at a temperature T is as follows. It is expressed by equation (1).

R6(T,) is the relative humidity (R) of the humidity detection element RX.
H) The resistance value is set to 60% (reference humidity). The reference humidity resistance value of the humidity detection element 2 depends on the temperature, as shown in FIG.

Therefore, in order to cope with this temperature dependence, a temperature sensitive resistance element RT is used in the element correction information circuit 3.

In addition, since the resistance value of the reference humidity differs for each humidity detection element RX, R8 (T
Adjust so that a) becomes the resistance value of each humidity detection element RX at the reference humidity. Note that this adjustment will be performed by the manufacturer, and the adjusted unit 1 will be shipped.

The oscillation circuit section 4, the element drive circuit section 5, and the rectifier circuit section 6 are the same as those of the conventional one. The humidity detection element RX and the element correction information circuit 3 are connected to an element drive circuit section 5 that is switched by a switch SW. An analog switch or a mechanical switch is used as the switch SW, and is controlled by the switch switching control circuit section 8.

The output of the rectifier circuit section 6 is digitally converted by an A/D converter 7 and taken into the CPU 9. The CPU 9 inputs the resistance value RX of the humidity detection element 2 and element correction information R8 (T,
) has a function to calculate humidity based on Also, C
In addition to the switch changeover control circuit section 8, a display 10 and a memory 11 are connected to the PU9. The display 10 is for displaying the calculated humidity HX, and the memory 11 is for storing the operating program of the CPU 9, the fetched element correction information R8(T,), and the like.

Next, the operation of this practical humidity measuring device will be explained with reference also to FIG.

First, the CPU 9 determines whether it is the sampling timing, that is, the timing to measure humidity [step (hereinafter referred to as ST) (2)]. If the determination is NO, the process waits here, and if the determination is YES, the process branches to Sr1. Note that the above-mentioned sampling timing is appropriately set according to the purpose of measurement.

In Sr1, it is determined whether it is the timing to take in the element correction information (correction data) RO. This element correction information R8 acquisition timing is normally set longer than the sampling timing, and the element correction information R8 is acquired once every several humidity measurements.
is being incorporated. Of course, the element correction information R8 may be always taken in when measuring humidity.
The design can be changed as appropriate.

If the determination of Sr1 is YES, the process branches to Sr1, and if the determination is NO, the process branches to Sr1. Proceeding with the explanation assuming that the determination of Sr1 is YES, in Sr1, the switch changeover control circuit unit 8 switches the switch S based on the signal from the CPU 9.
Switch W to the element correction information circuit section 3 side. In Sr8, the CPU 9 receives element correction information R8 (T
3) and stores this R8 (T3) in the memory 11 in Sr1.

When the process of Sr1 is completed or the determination of Sr1 is No, the process advances to Sr1. In Sr1, the switch switching control circuit unit 8 switches the switch SW to the humidity detection element 2 side based on a signal from the CPU 9.

In Sr1, humidity data Rx of the humidity detection element 2 is taken in, and in Sr5, humidity HX is calculated.

Humidity HX is calculated based on the following equation (2).

Here, Ho is the reference humidity (60% RH), and K is a constant.

In Sr1, the CPU 9 displays the calculated humidity HX on the display 10.
to be displayed. When the process of Sr1 is completed, the process returns to STI.

When the humidity detection element 2 deteriorates, the entire unit 1 is replaced with a new one. At this time, since the compatibility accuracy of unit 1 is ensured, there is no need to sort out the units, and there is no need to adjust the circuit inside the humidity measuring device after replacement, allowing the user to easily replace the humidity sensing element. be able to.

<Example 2> A second example of the present invention will be described based on FIGS. 4 and 5.

FIG. 4 is a block diagram of the humidity measuring device according to this embodiment. In this FIG. 4, an oscillation circuit section 24, an element drive circuit section 25, a rectifier circuit section 26, an A/D converter 27, and a display 30 are the same as those in the first embodiment (FIG. 1). It is.

The unit 21 is replaceably attached to the humidity measuring device via a connector (not shown). The unit 21 includes a variable resistance humidity detection element 22, a temperature sensitive resistance element R7,
An element correction information circuit 23 is provided. The element correction information circuit 23 is a series circuit of a fixed resistor R1 and a variable resistor ■8, and the combined resistance value Ro (=R+ +V
The variable resistor VR is adjusted so that R) is equal to the resistance value of the humidity detection element 22 at the reference temperature and reference humidity (for example, 25° C., 160% RH).

The humidity detection element 22, the temperature-sensitive resistance element RT, and the element correction information circuit 23 are connected to the element drive circuit section 25 via switches SWI, SW2, and SW3, respectively. switch sw
, sw2, and sw are controlled by the switch changeover control circuit section 28.

The CPU 29 has a function of correcting the temperature of the element correction information R8 taken in from the A/D converter 27 based on the temperature data RT also taken in, and corrects the humidity using the temperature-corrected element correction information R0 and the humidity data RX taken in. It has a function to calculate HX. The memory 30 is the CPU 29
In addition to the operation program, the captured element correction information R8
and temperature data, etc.

In the humidity measuring device of this embodiment, unlike the first embodiment, the temperature correction of the element correction information R8 is performed on the CPU 29 side. This is because if the specifications of the humidity detection element differ, the characteristics will also differ greatly, and the element correction information circuit 3 of the first embodiment
This is because there are cases in which temperature dependence cannot be approximated with a simple circuit such as .

Next, the operation of the humidity measuring device according to the embodiment will be explained with reference to FIG.

First, the CPU 29 determines whether it is sampling timing or not. If YES, the CPU 29 branches to 5T12; if NO, the process waits here. At 5T12, the CPU 29 further determines whether it is time to take in the temperature data, and if YES, the process branches to 5T13, and if NO, the process branches to 5T16.

At 5T13, the switch changeover control circuit unit 28 turns on only the switch SW2 in response to a command signal from the CPU 29. As a result, only the temperature-sensitive resistance element R7 is connected to the element drive circuit section 25. The CPU 29 converts the temperature data RT into A
/D converter 27 (ST14) and stores it in memory 31 (ST15).

At 5T16, it is determined whether it is time to take in element correction information (correction data). If this determination is YES, the process branches to 5T17, and if NO, the process branches to 5T20. 5T
At step 17, the switch changeover control circuit unit 28 turns on only SW3 in response to a command signal from the CPU 29. As a result, only the correction information circuit 23 is connected to the element drive circuit section 25.

The CPU 29 takes in the correction data R8 from the A/D converter 27 (ST18) and stores it in the memory 31 (ST18).
T19).

In Sr10, the two-switch switching control circuit 28 turns on only SW1 in response to a command signal from the CPU 29, and connects the humidity detection element 22 to the element drive circuit section 25. C.P.
U29 takes in humidity data RX from A/D converter 21 (ST21) and calculates humidity HX (ST22).
.

To calculate the humidity HX, temperature data R is stored in the memory 31.
7 and correction data R8, and temperature correction is performed on the correction data R0. This temperature correction is generally Ro (T,)
−f (R,,R,), and this function f
is determined according to the characteristics of the humidity detection element 22.

Next, the temperature corrected R,(T,) and the humidity data R,
The humidity HX (χRH) is calculated by applying the following equation (3) to

In equation (3), Ho is the standard humidity (here 60% R
H), K is a constant.

Finally, the CPU 29 displays the calculated humidity Hx on the display 3.
5T28) and return to STI determination. When the humidity detection element 22 deteriorates, the entire unit 21 is replaced with a new one, as in the first embodiment.

Although the first and second embodiments described above both use a variable resistance type humidity detection element, it is also possible to use a capacitance type humidity detection element, and the design may be changed as appropriate. It is possible.

(f) As described in detail of the invention, the humidity measuring device of the present invention has a humidity detecting element and a reference humidity information storage means that stores information regarding the reference humidity of the humidity detecting element, which are replaceable. Since it is provided on the unit and also includes a humidity calculation means for calculating humidity based on the signal of this humidity detection element and the information stored in the reference humidity information, the compatibility accuracy of the unit is ensured. . Therefore, there is an advantage that general users can easily replace the humidity detection element without having to make any adjustments when replacing the unit 7). Furthermore, since variations in the humidity detection element are allowed to some extent, the yield can be improved and the price of the humidity detection element can be lowered.

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining the configuration of a humidity measuring device according to a first embodiment of the present invention, FIG. 2 is a flow diagram explaining the operation of the humidity measuring device, and FIG. 3 is a humidity detecting device. A diagram showing an example of the characteristics of the element, FIG. 4 is a block diagram explaining the configuration of the humidity measuring device according to the second embodiment, and FIG. 5 is a diagram showing an example of the characteristics of the element.
A flow diagram explaining the operation of the humidity measuring device, FIG. 6, is as follows.
FIG. 2 is a block diagram illustrating the configuration of a conventional humidity measuring device. 1/21: Unit, 2/22: Humidity detection element, 3/2
3: Element correction information circuit, 9/29: CPU.

Claims (3)

[Claims] (1) A humidity detection element and a reference humidity information storage means that stores information regarding the reference humidity of this humidity detection element,
A humidity measuring device comprising: a humidity calculating means provided on a replaceable unit and calculating humidity based on a signal from the humidity detecting element and information stored in the reference humidity information storage means. (2) The humidity detection element has a resistance value that changes depending on the humidity, and the reference humidity information storage means is composed of a series-parallel circuit of a temperature-sensitive resistance element, a variable resistor, and a fixed resistor, and 2. The humidity measuring device according to claim 1, wherein the humidity information storage means takes a resistance value according to a temperature at a reference humidity of the humidity detecting element. (3) The humidity detection element has a resistance value that changes depending on the humidity, and the reference humidity information storage means includes a series-parallel circuit of a variable resistor and a fixed resistor, and The resistance value of the humidity detection element is taken, and the unit is equipped with a temperature sensing element together with the humidity detection element and the reference humidity information storage means, and the resistance value of the reference humidity information storage means is determined based on the signal from the temperature sensing element. 2. The humidity measuring device according to claim 1, wherein said humidity calculating means includes a temperature correcting means for temperature correction.