JPH0210258A - Humidity measuring apparatus - Google Patents

Abstract

PURPOSE:To correct the temperature characteristics of the output of a humidity sensor with relatively few data indicating temperature characteristics by writing relative humidity data at various humidities of the humidity sensor and at various temperatures in a ROM in a matrix pattern beforehand. CONSTITUTION:A ROM 6 has an address corresponding to the intersection of an abscissa where temperature T of a temperature sensor2 is set at a 20 deg.C interval and an ordinate where output voltage H of a humidity sensor 1 is set at a 100mV interval. Relative humidity is written at each address. Namely, the relative humidifies at a plurality of typical points, e.g. points A-D, on the temperature characteristic curves shown in Figure (b) are written in the ROM 6 (Figure b) beforehand. A microcomputer 5 has an address specifying function for reading in the ROM 6. When the detected temperature T and the voltage H agree with the axes, the data of the address of the intersection are read, and the measured value is obtained. When the agreed address is not present, four points comprising the points A-D shown in Figure (b) are sequentially connected with straight lines. The relative humidity F at an actually measured point P included in the region surrounded by the lines is obtained by and determined by the approximation with a straight line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a humidity measuring device having temperature characteristic correction means for a humidity sensor.

[Prior art] In order to correct the temperature characteristics of a humidity sensor, the temperature characteristic line of the humidity sensor is written in advance in a ROM (read only memory), and this is used to correct the output of the humidity sensor. To determine the relative humidity, for example, Japanese Patent Application Laid-Open No. 61-2
It is disclosed in Japanese Patent No. 96248.

[Problems to be Solved by the Invention] However, it has been difficult to express a function indicating a temperature characteristic line with a simple mathematical formula. Furthermore, in order to perform highly accurate measurements, many functions (temperature characteristic lines) must be written in the ROM, which increases the capacity of the ROM and inevitably increases the cost of the measuring device.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a humidity measuring device that can correct the temperature characteristics of the output of a humidity sensor using a relatively small amount of data indicating temperature characteristics.

[Means for Solving the Problems] The present invention for achieving the above object includes a humidity sensor, a temperature sensor disposed near the humidity sensor, various outputs of the humidity sensor, and various outputs of the temperature sensor. and a memory in which relative humidity data corresponding to the output of the humidity sensor and the temperature sensor are written in advance at addresses specified by the humidity sensor output and the temperature sensor output, and a memory in which relative humidity data corresponding to the output of the humidity sensor and the temperature sensor are obtained from the humidity sensor and the temperature sensor placed in the atmosphere to be measured. If there is an address in the memory that corresponds to the measurement end humidity sensor output and the measurement temperature sensor output, the data at this address is read out and output as a relative humidity measurement value, and the measurement end humidity sensor output and the measurement temperature sensor output are If there is no address in the memory that corresponds to the temperature sensor output, the two humidity sensor outputs are values above and below the measurement end humidity sensor output, and are values that allow specifying the memory address. Determine neighboring values, and determine two temperature sensor output neighboring values that are upper and lower values near the temperature sensor output at the time of measurement and values that can specify the address of the memory, and Data indicating relative humidity is read from four addresses of the memory based on the humidity sensor output neighborhood value and the two temperature sensor output neighborhood values, and these four data, the measurement end humidity sensor output, and the measurement temperature sensor The present invention relates to a humidity measuring device comprising: an output; and a data processing device configured to approximately calculate the relative humidity of the atmosphere to be measured based on the output.

In addition, to explain the correspondence between the present invention and the embodiment, the four specified addresses are points A, B, and C1D of the embodiment,
The memory is a ROM 6, and the data processing device is a microcomputer 5 and an A/D converter 3.4.

[Operation] Data corresponding to all outputs of the humidity sensor and all temperatures are not written in the memory in the above invention, but the data processing device reads data at four points near the measurement point from the memory and calculates the data by calculation. Determine the relative humidity at the measurement point. Therefore, it is possible to perform corrections on a large number of points with less data in memory.

[Example] Next, a humidity measuring device according to an example of the present invention will be described with reference to FIGS. 1 to 3.

As shown in FIG.
A humidity sensor 1 including an element made of JO/TiO2/5i02 material, a temperature sensor 2 placed near the humidity sensor 1, and an A/D converter 3 for converting the outputs of these into digital signals. .4, a microcomputer 5 that calculates relative humidity based on a predetermined program in response to the output of the A/D converter 3.4, and a matrix of various temperatures of the humidity sensor 1 and relative humidity data at various temperatures. It consists of a ROM 6 written in advance.

FIG. 2 shows the address structure of the ROM 6, where the horizontal axis shows the temperature T of the temperature sensor 2 set at 10°C intervals,
The output voltage H of the humidity sensor 1 has addresses corresponding to the intersections with the vertical axis set at 100 mV intervals, and the relative humidity is written at each address. In FIG. 2, the temperature T and the humidity sensor output voltage I are set at equal intervals, but they can be set at various intervals.

Temperature 20°C and humidity sensor output voltage 30 in Figure 2
Data of relative humidity 36% is written to the address corresponding to the intersection A with 0 mV, and data of relative humidity 2 is written to the address corresponding to the intersection B of the temperature 30°C and the humidity sensor output voltage 300 mV.
9% data is written, relative humidity data of 53% is written to the address corresponding to the intersection C between the temperature 20°C and the humidity sensor output voltage 400mV, and the relative humidity data 53% is written at the address corresponding to the intersection C between the temperature 20°C and the humidity sensor output voltage 300mV. Data for a relative humidity of 45% is written at the address corresponding to the intersection d. Data indicating relative humidity is similarly written in other addresses that are blank in FIG. As a result, the relative humidity at a plurality of representative locations on the temperature characteristic curve shown in FIG. 3 is written in advance in the ROM 6.

The microcomputer 5 has a read address designation function for the ROM 6, and also has an arithmetic function for calculating the relative humidity corresponding to the temperature and humidity sensor output voltage which are not written in the ROM 6 by linear interpolation calculation.

Addressing of ROM6 is based on temperature T detected by temperature sensor 2 and humidity sensor output voltage H detected by humidity sensor.
Determined based on. If the detected temperature T and the humidity sensor output voltage H match the horizontal and vertical axes in Figure 2, the data at the address at the intersection is read out and the measured value (relative humidity) is Become.

On the other hand, if there is no matching address, four addresses in the vicinity are specified.For example, if the temperature T is 26°C and the humidity sensor output voltage is 320mV, Temperatures around 26° C. (20° C. and 30° C.) are selected, and humidity sensor output voltages (300 mV and 400 mV) above and below 320 mV on the vertical axis of FIG. 2 are selected. Then, the two selected temperatures (20°C
530℃) and two selected humidity sensor output voltages (3
00mV, 400mV) are read addresses, and 4 data (36%, 29%) are read addresses.
%, 53%, 45%) are read out. Then, among the four data, the data (
36%) is taken as A in the interpolation calculation formula, and the higher temperature (30
The data (29%) corresponding to the intersection of the lower temperature (20 °C) and the lower humidity sensor output voltage (300 mV) is used as B in the interpolation calculation formula, and the lower temperature (20 °C) and the higher humidity sensor output voltage (300 mV) are 400 mV) and the data corresponding to the intersection (53%
) is taken as C in the interpolation calculation formula, and the higher temperature (30°C)
The data (45%) corresponding to the intersection of the higher humidity sensor output voltage (400 mV) is set as D of the interpolation calculation formula. Arithmetic formula for performing linear interpolation in the microcomputer 5 % Formula % However, in the above formula, a is the difference between the actual measurement value T of the temperature sensor 2 and the temperature corresponding to the address A. For example, if the actual measurement value T is 2
In the case of 6°C, 26°C-20'C=6°C. b is the difference between the measured output voltage [-1 of the humidity sensor 1 and the humidity sensor output voltage corresponding to the address A. For example, if the measured value H is 320 mV, 320 mV - 300 mV = 20
mV. When the actual measurement value of the temperature sensor 2 is 26° C. and the actual measurement value of the humidity sensor 1 is 320 mV, each part is substituted into the above equation as follows.

F= (((53-36) x6/10+361((4
5-29) x6/10+291) x20/100
11 <45-29) x6/10+291 Then, this calculation is executed to obtain the relative humidity F4012%. The above calculation formula connects the four points A, B, C, and D in Figure 3 in order with straight lines, and calculates the relative value of the actual JIq point P included in the area surrounded by these four straight lines. Humidity F
It has been decided to obtain it by linear approximation.

Four addresses are determined in exactly the same way at the other points explained by taking a certain point as an example, and similar calculations are performed.

This embodiment has the following effects.

(1) Various humidity sensor outputs at various temperatures can be corrected with less data, that is, with less capacity of the ROM 6. Therefore, the cost of the humidity measuring device can be reduced.

(2) Not only the temperature compensation of the humidity sensor 1 but also the temperature coefficient of other parts such as the circuit board are included in the a1q constant time.
These temperature corrections can also be performed at the same time.

(3) Functions related to the temperature characteristics of humidity sensor 1 are stored in ROM.
Since the humidity sensor 1 is not an input method, it is possible to use a humidity sensor 1 with poor linearity.

[Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(1) One A/D converter may be used for the humidity sensor 1 and the temperature sensor 2 in a time-sharing manner.

(2) A circuit (not shown) for writing temperature-corrected data of the humidity sensor 1 into the ROM 6 may be formed integrally with the circuit shown in FIG.

(3) The address of ROM6 shown in FIG. 2 is an example,
The temperature interval and humidity sensor output voltage interval can be varied. Further, the temperature interval and humidity sensor output voltage interval in the most important temperature and humidity sensor output voltage range may be narrower than in other ranges.

(4) The formula for the interpolation calculation does not have to be the same as the example.
For example, instead of using point A among the four points A, B, C, and D as a reference, for example, D
An arithmetic expression based on points may also be used.

(5) The ROM 6 may be built into the microcomputer 5.

[Effects of the Invention] As described above, the present invention provides a humidity measuring device that is capable of temperature correction of humidity sensors at many points with a small memory capacity and that can easily provide necessary data to the memory. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a humidity measuring device according to an embodiment of the present invention, FIG. 2 is a diagram showing the principle of the ROM address and data writing in FIG. 1, and FIG. 3 is a diagram showing the ROM in FIG. 2. FIG. 3 is a diagram for explaining the relationship between the data of the humidity sensor and the temperature characteristics of the humidity sensor. 1... Humidity sensor 2°... Temperature sensor 3.4... A/D converter 5... Microcomputer 6... ROM Figure 1

Claims (1)

[Claims] [1] A humidity sensor, a temperature sensor disposed near the humidity sensor, and relative humidity data corresponding to various outputs of the humidity sensor and various outputs of the temperature sensor. A memory written in advance at an address specified by the humidity sensor output and temperature sensor output, and the humidity sensor output at the time of measurement obtained from the humidity sensor and the temperature sensor placed in the atmosphere to be measured and the time of measurement. If there is an address in the memory that corresponds to the temperature sensor output, the data at this address is read and output as a relative humidity measurement value, and the address corresponding to the measurement humidity sensor output and the measurement temperature sensor output is If it is not in the memory, determine two neighboring values of the humidity sensor output, which are upper and lower values near the humidity sensor output at the time of measurement, and values that can specify an address in the memory, and Determine two temperature sensor output neighborhood values, which are values above and below the neighborhood of the humidity sensor output, as well as values that can specify the address of the memory, and determine the two humidity sensor output neighborhood values and the two Data indicating relative humidity is read from the four addresses of the memory based on the temperature sensor output neighborhood value, and the measured atmosphere is read based on the four data, the humidity sensor output at the time of measurement, and the temperature sensor output at the time of measurement. 1. A humidity measuring device comprising: a data processing device configured to approximate the relative humidity of the area by calculation.