JPH0426898Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a controller that controls the absolute humidity in a humidity chamber, and is particularly applicable to high temperature and high humidity (for example, when the ambient temperature is 60°C or higher and the set humidity is Absolute humidity 140g/ ^m3
The present invention relates to an absolute humidity controller for the humidity chamber described above.

In order to maintain the quality of fast foods such as hamburgers for a relatively short period of time, there is a demand for processing them in a high temperature and high humidity atmosphere.

Such high temperatures and high humidity, especially when the ambient temperature is 60℃
The above contributes to the realization of an absolute humidity controller that can accurately control the absolute humidity to a set value in a constant humidity chamber with an absolute humidity of 140 g/m ³ or more.

[Conventional technology]

Humidity sensors used in general living environment humidity include resistance-type humidity sensors that utilize changes in electrical properties due to moisture absorption of materials such as organic polymer membranes, metal oxide ceramics, and electrolyte-based lithium chloride. In addition to sensors and capacitive humidity sensors, there are wet and dry bulb humidity sensors that use heat-sensitive elements such as platinum thermometers, thermocouples, and thermistors as temperature sensors.

Resistive humidity sensors and capacitive humidity sensors are often used in environments with living environment temperatures, but when used in environments with high temperatures and high humidity, there are issues with reproducibility, stability, responsiveness, compatibility, etc. Due to problems, it is hardly used. Wet and dry bulb type humidity sensors are also used in cases of high temperature and high humidity, but because the wet bulb uses gauze and water, errors may occur due to dirt on the gauze or water stains on the surface of the wet bulb. Easy,
It requires careful handling and is troublesome to maintain.

On the other hand, thermal conduction absolute humidity sensors that use heat-sensitive elements such as thermistors utilize changes in the thermal conductivity of gases depending on the amount of water vapor in the atmosphere.
Extremely stable even when used in high temperature and high humidity environments.

FIG. 2 shows a basic circuit for detecting absolute humidity (g/m ³ ) using a heat conduction type humidity sensor. In the same figure, Th ₁ is a humidity sensing element with a humidity sensing thermistor housed in a metal tube with a ventilation hole in the tube wall and a hermetically sealed lead terminal at the bottom, and Th ₂ is the same as Th ₁ . This is a temperature compensating element that houses a thermistor with the same characteristics inside, but has no ventilation holes in the tube wall and is kept completely dry inside. R ₁ is a fixed resistor, R _V is a variable resistor, and these together with thermistors Th ₁ and Th ₂ constitute a bridge circuit as shown. variable resistance
R _V is for zero point adjustment of the bridge circuit. Also R _S
is a current limiting resistor provided between the bridge circuit and the DC power supply E, and V ₁ and V ₂ are output terminals.

Figure 3 shows the bridge output voltage (mV) when absolute humidity is measured using the humidity sensor shown in Figure 2 at ambient temperatures of 10°C, 20°C, 30°C, and 40°C.
- This is an example of an absolute humidity (g/m ³ ) characteristic curve.

As an example, when the ambient temperature is 60℃ or higher, the absolute humidity
When the absolute humidity is 140 g/m ³ or more, the electrical output characteristics of the bridge that detects the absolute humidity become a parabola with the maximum value at the point of 140 g/m ³ as shown in Figure 4, and the same For bridge output voltage
There are two absolute humidity values: one below 140 g/m ³ and one above 140 g/m ³ .
For this reason, conventional humidity controllers used in humidity chambers with living environment temperatures cannot control humidity over such a range.

For example, if the ambient temperature is 100℃, the output voltage (mV) of the above absolute humidity sensor has a maximum value at the absolute humidity of 140g/ ^m3 , and after this point the output voltage decreases. Descending, absolute humidity 345g/
Above ^m3 , the output voltage takes a negative value.
This phenomenon was experimentally discovered by the inventors. [April 3, 1980, Japan Society of Applied Physics (University of Yamanashi) "Measurement of Humidity", July 1980, No. 20
Annual SICE Academic Lecture (Tohoku University “Output Characteristics of Humidity Sensors”) Figure 5 shows the sensor output voltage (mV) versus absolute humidity (g/m ³ ) at an ambient temperature of 100°C.
6 is a diagram showing absolute humidity (g/m ³ ) - absolute humidity sensor output voltage (mV) at 100°C.
It is a figure showing the characteristic curve of.

[The problem that the idea aims to solve]

One of the purposes of this invention is that, conventionally, when the ambient temperature is above a certain temperature and the absolute humidity is above a certain humidity, the electrical output characteristics of the bridge that detects absolute humidity reach a peak at the point of a certain absolute humidity. The bridge output voltage of the same thermal conduction type humidity sensor has a parabolic shape with a value of 2.
The objective is to solve the problem that there are two absolute humidity values and it is not possible to control the humidity in the area. An object of the present invention is to provide an absolute humidity controller that can correctly control the absolute humidity in a constant humidity chamber such as the above.

Another object of the present invention is to provide an absolute humidity controller having a function of preventing malfunctions due to a drop in humidity when the door of the humidity chamber is opened during humidity control in the humidity chamber. be.

Another object of the present invention is to provide an absolute humidity controller having a function of preventing malfunctions due to unstable voltage output of the humidity sensing element when the power is turned on.

[Means to solve the problem]

_The absolute humidity controller 2 of _the present invention, as shown in the embodiment of FIG.
In the absolute humidity controller 2 of the humidity chamber 13, which includes a humidity sensing element 1 that measures absolute humidity based on changes in thermal conductivity of the atmosphere, a comparison control circuit 7 and a forced humidification signal generation circuit are provided. 11, 12, a humidifier drive circuit 8, and a humidifier 3.

The comparison control circuit 7 generates a humidification signal when the output of the humidity sensing element 1 exceeds a set value.

The forced humidification signal generating circuits 11 and 12 enter a holding state when the power is turned on, generate a forced humidification signal, and are released from the holding state in response to the humidification signal.

The humidifier drive circuit 8 generates a humidifier drive signal based on the logical sum of the humidification signal and the forced humidification signal.

The humidifier 3 humidifies the inside of the constant humidity tank 13 in response to this humidifier drive signal.

Further, the absolute humidity controller 2 of the present invention is set in the above-mentioned holding state when the forced humidification signal generating circuits 11 and 12 open the door of the humidity tank 13.

Further, in the absolute humidity controller 2 of the present invention, the forced humidification signal generating circuits 11 and 12 are prohibited from releasing the holding state by the humidification signal for a certain period of time when the power is turned on.

Therefore, the configuration of the present invention is as shown below. That is, the present invention consists of a heat-sensitive element (Th ₁ ) that comes into contact with the atmosphere and a heat-sensitive element (Th ₂ ) that does not come into contact with the atmosphere.
In the absolute humidity controller 2 of the humidity chamber 13, which is equipped with a humidity sensing element 1 that measures absolute humidity based on changes in the thermal conductivity of the atmosphere, the output of the humidity sensing element 1 exceeds a set value. a comparison control circuit 7 that generates a humidification signal when the humidification occurs; forced humidification signal generation circuits 11 and 12 that enter into a holding state when the power is turned on, generate a forced humidification signal, and are released by the humidification signal; A humidifier drive circuit 8 that generates a humidifier drive signal based on the logical sum of the signal and the forced humidification signal, and a humidifier 3 that humidifies the inside of the humidity chamber 13 in accordance with the humidifier drive signal. , _a bridge (humidity signal _conversion amplifier circuit 5, FIG. ) has a parabolic electrical output characteristic with a maximum value at a specific absolute humidity point (Figure 4), and for the same bridge output voltage, there is a region below the maximum value and a region above the maximum value. Two absolute humidity values (A, B, fourth
), and the absolute humidity of the constant humidity chamber 13 is controlled such that the set absolute humidity (B, C, D, FIG. 4) is within the above range at the specific temperature or higher. Alternatively, when the door of the humidity chamber 13 is opened from the forced humidification signal generation circuits 11 and 12, the humidity chamber 13 is set in the holding state, and the humidity chamber is activated during humidity control. It has a structure as an absolute humidity controller 2 characterized by preventing malfunction due to a drop in humidity when the door 13 is opened, or alternatively, when the forced humidification signal generation circuits 11 and 12 are powered on. The absolute humidity controller 2 is configured such that release by the humidification signal is prohibited for a certain period of time to prevent malfunction due to unstable voltage output of the humidity sensing element when the power is turned on.

[Effect]

The absolute humidity controller 2 of the present invention detects water vapor in the atmosphere by using heat-sensitive elements (Th ₁ , Th ₂ ) heated by passing current as a component of a bridge circuit for absolute humidity detection (5, Fig. 2). An output level holding circuit 11 and a forced humidification circuit 12 which measure absolute humidity by the bridge circuit output voltage and maintain the absolute humidity at a desired value by utilizing changes in thermal conductivity of gas determined by the amount of gas. By controlling the humidifier 3 and performing humidification by the forced humidification signal generation circuits 11 and 12 composed of There is.

〔Example〕

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention, and illustrates a case where a thermistor is used as the heat-sensitive element.

In FIG. 1, reference numeral 1 denotes a humidity sensing element, which is installed inside a humidity chamber 13. 2 is an absolute humidity controller of the present invention. 3 is a humidifier and is provided in a constant humidity tank. 4 is a door reset switch.

The humidity sensing element 1 has a structure in which a thermistor Th ₁ (humidity sensing element) and thermistor Th ₂ (temperature compensating element) as shown in FIG. 2 are attached to a substrate and integrated.

In the absolute humidity controller 2, the humidity signal conversion and amplification circuit 5 is equipped with a fixed resistor _R1 and a variable resistor _RV for zero point adjustment, which constitute a bridge circuit shown in FIG. The electrical signal corresponding to the absolute humidity generated by the humidity sensor section is amplified and then output.

The humidity setting section 6 has a setting device made of, for example, a variable resistor, and generates an electric signal corresponding to the humidity to be set.

The comparison control circuit 7 compares the electrical signal of the humidity measurement value of the humidity signal conversion amplification circuit 5 with the electrical signal of the humidity setting value of the humidity setting section 6, and turns on or off depending on the magnitude of the measurement value and the setting value. Outputs a signal that turns off.

The humidifier drive circuit 8 has an OR circuit at its input, and receives the ON signal from the comparison control circuit 7 and the control humidification circuit 1.
A humidification control signal is output to the humidifier 3 in response to the ON signal from the humidifier 2.

In the humidifier 3, an internal power supply circuit operates according to the humidification control signal to drive the humidifier and humidify the inside of the constant humidity tank.

A power supply circuit 9 supplies necessary power to each part of the controller 2.

The timer circuit 10 generates a signal that is turned on for a certain period of time (for example, several seconds) in response to a signal from the power supply circuit 9 when the power is turned on.

The output level holding circuit 11 is set by the signal from the timer circuit 10 or the signal from the door reset switch 4, and reset by the ON signal from the comparison control circuit 7.

The forced humidification circuit 12 generates a signal that is turned on by the set output signal of the output level holding circuit 11.

The door reset switch 4 is linked to the door of the humidity chamber 13 and is turned on when the door is opened.

The absolute humidity controller 2 of the present invention performs control operations in the range of the output characteristics shown in FIG. 4, that is, for example, in the range of absolute humidity of 140 g/m ³ or more. The operation of the absolute humidity controller 2 of the present invention will be explained below.

As mentioned above, the thermal conduction type absolute humidity sensor has output characteristics for absolute humidity as shown in Figure 4, but since the signal obtained from the sensor is only the output voltage, for example, the output voltage e ₁ At this time, it is impossible to determine whether the absolute humidity is Ag/m ³ or Bg/m ³ .

Now, let us assume that the output voltage corresponding to the humidity set point to be controlled in the characteristics shown in Fig. 4 is e _1. In order to control the humidity only in the range of , the output from the humidity sensor must be lower than the set point e ₁ . It is necessary to control the humidifier to turn off when the humidity is low, that is, when the humidity is higher than Bg/m ³ .

However, when the power is first turned on, the humidity inside the humidity chamber 13 is low, and the absolute humidity is in the Ag/
m ³ or less, and the humidity sensor output is smaller than the set value e ₁ . Since the comparison control circuit 7 generates a signal to turn off the humidifier 3 when the measured value is smaller than the set value, the humidifier 3 does not operate, and therefore the humidity in the humidity chamber 13 ^reaches Bg/m3. You can't make it reach you.

Therefore, the output level holding circuit 11 is set by the signal from the timer circuit 10 when the power is turned on, and the output of the forced humidification circuit 12 is turned on by the set output signal. As a result, the humidifier drive circuit 8 outputs a humidification control signal, and the humidifier 3 operates to perform humidification.

Humidification progresses and the humidity inside the humidity tank 13 increases, causing A.
When g/m exceeds ³ and the sensor output becomes greater than e ₁ ,
Comparison control circuit 7 generates an on signal. As a result, the humidifier drive circuit 8 continues to output the ON signal, the output level holding circuit 11 is reset, and the output of the forced humidification circuit 12 is turned OFF.
The humidifier drive circuit 8 operates only by the signal from the comparison control circuit 7.

The humidifier 3 continues the humidifying operation, and the humidity further increases and enters a region where the sensor output decreases as the humidity increases. If humidification is continued and Bg/m ³ is exceeded, the sensor output becomes smaller than the set value e ₁ and the output signal of the comparison control circuit 7 is turned off, so the humidifier 3 is stopped and the increase in humidity is stopped.

In this state, when the humidity gradually decreases and becomes less than Bg/m ³ , the sensor output becomes larger than the set value e ₁ , and the comparison control circuit 7 again generates an output signal to turn on, and humidification is performed.

Through on-off control that repeats such operations, the humidity in the humidity chamber 13 is maintained at Bg/m ³ corresponding to the set voltage e ₁ .

Also, point C where the humidity set point is in the range but very close to 345 g/m ³ (humidity sensor output voltage e ₂ ), or point D where the humidity is higher than 345 g/m ³ (humidity sensor output voltage has a negative sign) The control operation will be explained assuming that e ₃ ) with .

In this case, since the output voltage of the humidity sensor is higher than the set voltage e ₂ (or e ₃ ) in a room temperature atmosphere, the forced humidification circuit is released from the beginning, that is, the control operation is performed in the area, and the output of the humidity sensor is If the voltage is higher than the set voltage, humidification will continue, and as a result, the inside of the humidity chamber 13 will be humidified from the beginning, and the humidity will gradually increase, increasing from region to region. When the humidification progresses and the output voltage of the humidity sensor becomes equal to the set voltage e ₂ (or e ₃ ), the humidification is turned off and a control operation is performed at the set value Cg/m ³ (or Dg/m ³ ) to reduce the humidity. It will be kept at the set value. The other points are the same as in the case where the Bg/m ³ point is used as the set point, which has already been explained.

In addition, if the door of the humidity tank 13 is opened,
The humidity inside the humidity chamber 13 drops rapidly. If the humidity is now lower than Ag/ ^m3 , the output signal of the comparison control circuit 7 will be turned off because the sensor output will be lower than _e1 , so the humidifier 3 cannot be operated and the humidity will continue to decrease. becomes. In order to avoid such a situation, it is necessary to restart the forced humidification circuit 12. Therefore, the door-opening output level holding circuit 11 is set by the door reset switch 4 interlocked with the door of the humidity chamber 13, and the forced humidification circuit 12 generates an ON output signal. As a result, the humidifier drive circuit 8 puts the humidifier 3 into operation, and forced humidification to Bg/m ³ is performed again.

The timer circuit 10 turns on when the power is turned on and sets the output level holding circuit 11.
Since the humidity sensor outputs a transient large output regardless of humidity for a short period of time until the operation stabilizes when the power is turned on, the timer circuit 10 outputs a large output for a short period of time (several seconds) until the operation stabilizes when the power is turned on.
An output signal that turns on is generated to prevent the output level holding circuit 11 from being reset by the sensor output.

[Effect of idea]

As explained above, according to the absolute humidity controller of the present invention, it is possible to easily control the absolute humidity of the area inside the humidity chamber using the heat conduction type humidity sensor.

It is possible to prevent malfunctions caused by opening the door of the humidity chamber and malfunctions caused by transient high output when the power is turned on.

Therefore, there is a reduction in reliability, maintenance, and
This eliminates troubles such as inconvenience in handling, and makes it possible to easily and stably control absolute humidity under high temperature and high humidity conditions.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an absolute humidity controller as an embodiment of the present invention, Fig. 2 is a diagram showing a basic circuit for detecting absolute humidity using a thermal conduction humidity sensor, and Fig. 3 The figure is a diagram illustrating the bridge output voltage (mV) vs. absolute humidity (g/m ³ ) characteristic curve when measuring absolute humidity with the humidity sensor shown in Figure 2, and Figure 4 shows the output characteristics of the absolute humidity sensor. Figure 5 is a diagram showing the value of sensor output voltage (mV) versus absolute humidity (g/m ³ ) at an ambient temperature of 100°C, and Figure 6 is a diagram showing the absolute humidity (g/m ³ ) at an ambient temperature of 100°C. - A diagram showing a characteristic curve of the sensor output voltage (mV). 1...Moisture sensing element, 2...Absolute humidity controller, 3...
...humidifier, 4...door reset switch, 5...
Humidity signal conversion amplifier circuit, 6... Humidity setting section, 7...
... Comparison control circuit, 8 ... Humidifier drive circuit, 9 ...
Power supply circuit, 10...Timer circuit, 11...Output level holding circuit, 12...Forced humidification circuit, 13...
Humidity chamber, Th ₁ ... Humidity detection element, Th ₂ ... Temperature compensation element, R ₁ ... Fixed resistance, R _S ... Current control resistor, R _V ... Variable resistance, E ... DC power supply.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A permanent device equipped with a moisture-sensitive element that measures absolute humidity based on changes in the thermal conductivity of the atmosphere, including a heat-sensitive element that comes into contact with the atmosphere and a heat-sensitive element that does not come into contact with the atmosphere. An absolute humidity controller for a humidity tank includes a comparison control circuit that generates a humidification signal when the output of the humidity sensing element exceeds a set value, and a comparator control circuit that generates a humidification signal when the power is turned on and generates a forced humidification signal. a forced humidification signal generation circuit that is canceled by the signal; a humidifier drive circuit that generates a humidifier drive signal based on a logical sum of the humidification signal and the forced humidification signal; and a humidifier that humidifies the inside of the humidity chamber according to the temperature, and detects absolute humidity when the ambient temperature is above a certain temperature and the absolute humidity is above a certain temperature. has a parabolic shape with a maximum value at a specific absolute humidity point, and for the same bridge output voltage, has two absolute humidity values in an area below the maximum value and an area above the maximum value, An absolute humidity controller that controls the absolute humidity of a humidity chamber whose set absolute humidity is within the range above the specific temperature. (2) The forced humidification signal generating circuit enters the holding state when the door of the humidity tank is opened, thereby preventing malfunctions due to a drop in humidity when the door of the humidity tank is opened during humidity control. Claim 1
Absolute humidity controller as described in section. (3) Claim characterized in that the forced humidification signal generation circuit is prohibited from being released by the humidification signal for a certain period of time when the power is turned on, thereby preventing malfunctions due to unstable voltage output of the moisture sensing element when the power is turned on. 1st
Absolute humidity controller as described in section.