JPH062416U - Absolute humidity controller - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] The maximum value of the output voltage of the absolute humidity sensor forcibly humidified is compared with the maximum value of the output voltage that the absolute humidity sensor should have, and the error is eliminated. Achieve high-precision control of the thermostatic chamber with humidity. [Composition] When the temperature of the atmosphere is higher than the specified temperature and the set value of the humidity to be controlled is higher than the specified humidity, the humidity is forcibly humidified at the start of use and the absolute humidity reaches the maximum value. The point where it occurs is exceeded, and the maximum value of the output voltage of the absolute humidity sensor 1 at that time is held in the maximum value detection hold (or storage) circuit 4 or stored in a memory. This value is compared with the maximum value of the output voltage from the reference maximum value output circuit 5 which should be originally possessed by the absolute humidity sensor, the difference is obtained, and the value is stored. Next time the actual control operation is started, the output of the absolute humidity sensor is actually
The above values are input to the humidity signal correction circuit 7 for correction,
The output of the corrected result is compared with the reference of the set value to perform control.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

The present invention relates to an absolute humidity controller, specifically, an absolute humidity controller for controlling the humidity of a constant humidity chamber by the absolute humidity, and particularly, the temperature is 60 ° C. or more and the set humidity is 130 g / m ³ The above absolute humidity controller is concerned.

[0002]

[Prior art]

 The applicant of the present application has already proposed a temperature control device that realizes a highly accurate constant temperature and humidity chamber by independently controlling the constant temperature and humidity chamber by using a temperature sensor and an absolute humidity sensor. Kaihei 1-259406 gazette: hereinafter referred to as Prior Art I).

The applicant of the present invention further proposed an absolute humidity controller (Publication No. 2-32113 of Utility Model Publication: hereinafter referred to as Prior Art II).

In these prior arts, the humidity region is determined by the combination of the control output state (ON or OFF) and the absolute temperature sensor output state, and the control operation is determined based on the result. Was configured into. This will be explained briefly.

FIG. 2 shows an example in which the characteristics of bridge output voltage Vm (mV) -absolute humidity (g / m ³ ) in an absolute humidity detection circuit (not shown) are measured up to a saturated state at each temperature. It is a thing.

In FIG. 2, in an atmosphere of less than 62 ° C., the curve from the atmosphere of zero humidity to the saturated state has a parabolic rise curve. However, in an atmosphere of 62 ° C or higher, there is a maximum value in the vicinity of absolute humidity of 140 g / m ³ , and when the absolute humidity further increases, the output voltage reversely decreases, and when the absolute humidity is 345 g / m ³ or more, The polarity of voltage is reversed.

As described above, in the prior arts I and II, when the ambient temperature is higher than or equal to the specific temperature and the absolute humidity is higher than or equal to the specific humidity, the electrical output characteristic of the bridge for detecting the absolute humidity is the specific temperature. It has a parabolic shape with a maximum at the point of absolute humidity, and for the bridge output voltage of the same heat conduction type humidity sensor, there are two absolute values in the I region below the maximum and the II region above the maximum. It is to solve the problem that the humidity value exists and it is not possible to control the humidity in the II area.Therefore, it is required that the absolute humidity set above the specified temperature be in the II area. We have provided an absolute humidity controller that can accurately control absolute humidity in such a constant humidity chamber.

[0008]

[Problems to be solved by the device]

 The fate of a humidity sensor that uses heat conduction to detect humidity, but the output of the humidity sensor may be affected by the mixture of various gases that affect heat conduction and changes in pressure. In addition, since the water molecules have a strong polarity, the thermal conductivity of humid air shows a unique change due to changes in humidity (Reference: ALEXANDER L. LINDSAY AND LEROY A. BROMLEY; Thermal Conductivity of Gas Mixtures, University of Ca lifornia, Berkeley, Calif., Industrial and Engineering Chemistry, vol.42, No.8), the maximum value of the thermal conductivity exists when the mole fraction of water vapor changes. Therefore, the output of the absolute humidity sensor also has a maximum value, and before and after the maximum point, not only the change in the output when the humidity changes becomes small (the sensitivity as a humidity sensor becomes low), but also the maximum point. In between, the output of the sensor changes from an increasing function to a decreasing function. Therefore, it is, of course, necessary to determine in which area the humidity is, but when the output of the sensor is affected by the mixture of various gases and the change in pressure, the maximum value is obtained. Before and after absolute humidity, there is a strong tendency to have a large effect on the reading of absolute humidity. The present invention seeks to minimize the influence of this environment on the sensor in order to reduce the error caused by this.

[0009]

[Means for Solving the Problems]

 Means for solving the above problems are as follows. 1) When the temperature of the atmosphere is above a specific temperature and the set value of the humidity to be controlled is above the specified humidity, the humidity is forcibly humidified at the start of use and the absolute humidity reaches the maximum value. The output voltage of the absolute humidity sensor at that time is electrically held or stored in a memory so that it exceeds the point where it occurs. This value is compared with the maximum value of the output voltage that the absolute humidity sensor should have, and the difference is calculated and the value is stored.

2) Next, when the actual control operation is started, the output of the absolute humidity sensor is actually corrected using the value obtained in 1), and the output of the corrected result is compared with the reference of the set value. And control it.

[0011]

[Action]

 By using the above means, it is possible to remove the error of the absolute humidity sensor caused by the mixing of gas, the change of atmospheric pressure and other factors, and realize the control of the constant humidity chamber with absolute humidity with high accuracy. it can.

[0012]

【Example】

FIG. 1 shows an embodiment according to the present invention. In the figure, 1 is an absolute humidity sensor using heat conduction, and the whole surrounded by the broken line 2 is the absolute humidity controller according to the present invention. 3 is a humidity signal conversion / amplification circuit that amplifies the humidity sensor signal and outputs it (including a linearization function if necessary), and 4 detects the maximum value of the humidity sensor output at the start of use. Then, the circuit 5 which holds or stores the value and supplies the signal to the subtraction circuit 6 supplies the reference output V _max.STD for the _maximum value when the absolute humidity sensor is used in a normal state. _{Reference numeral} 6 is a circuit, and 6 is a circuit which subtracts the output of the circuit 4 from the output of the circuit 5 and outputs the result (Δv = V _max.STD −v _max ). Reference numeral 7 is a humidity signal correction circuit for adding the correction signal from 6 to the output of the absolute humidity sensor from 3, and supplies the signal v _D + ΔV corrected to 10. Reference numeral 8 is a setter of this absolute humidity controller, and 9 is a circuit for generating a reference voltage corresponding to the absolute humidity set in the setter of 8. Reference numeral 10 is a part in charge of control of this circuit. A comparison circuit that controls signals by comparing signals from 7 and 9 and a circuit that actually controls the humidifier by the output of the comparison circuit. This is a forced humidification control circuit for performing forced humidification at the start of use. Reference numeral 11 indicates a control output such as humidification.

As described above, FIG. 2 is a diagram showing the characteristics of the output voltage of the humidity signal converting / amplifying circuit 3 and the absolute humidity.

FIG. 3 is a diagram showing the reference output characteristic of the absolute humidity sensor and the output characteristic due to the shift of the zero point.

In FIG. 3, reference numeral 12 is a reference output characteristic of the absolute humidity sensor at an arbitrary temperature t ° C. Reference numeral 13 in FIG. 3 shows the output characteristic of the measured value due to the mixing of gases other than air and water vapor, the change in atmospheric pressure, and the zero point shift caused by other causes.

When an error of | Δv | occurs at the maximum point of the output voltage due to the zero point shift of the absolute humidity sensor, the output voltage of the absolute humidity shifts by | Δv | in the vertical direction of the output axis with respect to the reference value. .

The output voltage has a maximum value at an absolute humidity of 140 g / m ³ , and the saturated absolute humidity is 141 g / m ³ when the atmospheric temperature is 62 ° C. Therefore, the output error at the maximum point is detected at an arbitrary temperature of 62 ° C. or higher, and is calculated by the subtraction circuit 6 in FIG. 1 to correct the error.

By configuring the entire control device in this manner, the humidity can be controlled with high accuracy over a wide humidity range up to a high humidity location, excluding the influence of the absolute humidity sensor due to various causes. Can be controlled.

[0019]

[Effect of device]

 By carrying out the present invention, there is a slight shift of the zero point that may occur in the absolute humidity sensor due to bad environmental conditions, and influence on the fluctuations of various gases (except air and water vapor) and atmospheric pressure mixed in the atmosphere. Since it is possible to eliminate the error caused by the shift of the zero point of the sensor, the humidity can be controlled accurately over a wide range of humidity. This makes it possible to meet the demands of various industries, which have become increasingly severe in recent years.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing characteristics of an output voltage of a humidity signal converting / amplifying circuit 3 and absolute humidity.

FIG. 3 is a diagram showing a reference output characteristic of an absolute humidity sensor and an output characteristic due to a shift of a zero point.

[Explanation of symbols]

1 Absolute Humidity Sensor 2 Absolute Humidity Controller 3 Humidity Signal Conversion / Amplification Circuit 4 Maximum Value Detection Hold (or Memory) Circuit 5 Reference Maximum Value Output Circuit (V _max.STD ) 6 Subtraction Circuit 7 Addition Circuit (Humidity Signal Correction Circuit) 8 Setting circuit based on absolute humidity 9 Reference voltage generation circuit for absolute humidity set value 10 Comparison circuit + humidification control circuit and forced humidification circuit 11 Control output for humidification 12 Standard output characteristic at arbitrary temperature t ° C 13 Measured value due to deviation of zero point Output characteristics

Claims (1)

[Scope of utility model registration request] 1. A structure in which two heat-sensitive elements maintained at a temperature considerably higher than the ambient temperature are used, one of which is in contact with the atmosphere and the other of which is not in contact with the atmosphere, In an absolute humidity controller for a humidity chamber that uses a humidity sensor that measures the absolute humidity by using the temperature change of the thermosensitive element due to the change of the thermal conductivity of gas, if the temperature of the humidity chamber to be controlled is higher than a specified temperature. If the absolute humidity is equal to or higher than a specific absolute humidity, measure the maximum value of the absolute humidity sensor output before starting use, and hold or store the value in a memory. An absolute humidity controller, characterized in that the accuracy of humidity control is improved by automatically correcting the output of the absolute humidity sensor using this result.