JPH0421098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an automatic control device for a humidifier that automatically adjusts the humidity of an atmosphere to be humidified, such as a room.

[Technical background of the invention]

As a conventional automatic control device of this type,
-35696 publication is known. In this publication, a thermistor for detecting room temperature is connected to the circuit that supplies bias voltage to the oscillation transistor of the oscillation circuit that drives the ultrasonic transducer, and the thermistor detects whether the room temperature increases or decreases. In other words, as the relative humidity decreases or increases, the humidifier output is automatically controlled by continuously increasing or decreasing the oscillation output supplied from the oscillation circuit to the ultrasonic transducer. This is what I did.

[Problems with background technology]

However, since the humidifier output is controlled in response to changes in room temperature, the system disclosed in this publication has poor responsiveness, and since the humidifier output is continuously changed, the humidity ripple is large.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to control the output of a humidifier by changing it in stages using a humidity sensor having humidity-electrical resistance characteristics, thereby achieving excellent responsiveness. Another object of the present invention is to provide an automatic control device for a humidifier that can suppress humidity ripple to a small level.

[Summary of the invention]

The present invention provides a humidity sensor that is installed to detect atmospheric humidity and whose electrical resistance value changes depending on the humidity, and a humidity sensor that converts the electrical resistance value of the humidity sensor into a voltage, and whose humidity-output voltage characteristic is on the low humidity side. A humidity detection circuit that is set so that the rate of change increases as it goes toward the high humidity side, a humidity setting circuit that outputs the desired humidity as a voltage, and both outputs of the humidity detection circuit and humidity setting circuit. A voltage difference detection circuit that outputs a voltage difference, a reference voltage generation circuit that generates desired multiple levels of reference voltage, and multiple levels of reference voltages generated from this reference voltage generation circuit and an output voltage from the voltage difference detection circuit. at least two voltage comparator circuits that respectively compare the oscillation output of the oscillation circuit, and a circuit that increases or decreases the base current for the oscillation transistor in steps based on the outputs from these voltage comparison circuits, thereby changing the oscillation output of the oscillation circuit in steps. The humidifier output is automatically controlled so that the output of the humidifier is changed stepwise in accordance with changes in the oscillation output of the oscillation circuit.

[Embodiments of the invention]

Hereinafter, an embodiment in which the present invention is applied to an ultrasonic humidifier will be described with reference to the drawings.

In FIG. 1, a fan motor 1 is provided to discharge mist generated in response to the driving of an ultrasonic vibrator 2 to the outside of the ultrasonic humidifier. A power switch 4 is connected therebetween. A primary coil 5a of a step-down transformer 5 is connected in parallel with the fan motor 1, and a secondary coil 5b of the step-down transformer 5 is a total coil composed of four diodes 6 connected in a bridge as shown in the figure. It is connected to lines L ₁ and L ₂ via a wave rectifier circuit 7 . Therefore, a DC voltage with a high potential on the line _L1 side appears between the lines _L1 and _L2 , and the smoothing capacitor 8 is connected between the lines _L1 and _L2 .
A well-known configuration for driving the ultrasonic transducer 2
The LC oscillation circuit 9 is provided so as to be supplied with power from between the line _L1 and the line _L2 , and the connection relationship of this LC oscillation circuit 9 will be explained below. That is, in the NPN type transistor 10 for oscillation, its collector is connected to the line via the chiyoke coil 11.
It is connected to L ₁ and the emitter is connected to the line
A capacitor ₁₂ and a variable resistor 13 for setting the oscillation output are connected in parallel between the base and the line _L2 . Further, a capacitor 14 is connected between the collector and the emitter of the transistor 10, and a capacitor 15 and the ultrasonic vibrator 2 are connected in series between the collector and the base of the transistor 10. The ultrasonic vibrator 2 is disposed at the bottom of a water tank (not shown) of the ultrasonic humidifier, and is designed to generate ultrasonic waves and atomize the water in the water tank when excited by the LC oscillation circuit 9. It is composed of

On the other hand, a constant voltage circuit 18 consisting of a series circuit of a resistor 16 and a Zener diode 17 with the polarity shown is connected between the lines _L1 and _L2 , and therefore the line _L3 is connected to both terminals of the Zener diode 17. A constant DC voltage is output between L2 and _L2 .
A square wave generation circuit 19 is connected between lines _L3 and _L2 , and this square wave generation circuit 19 will be explained below. i.e. lines L ₃ and L ₂
Resistors 20 and 21 and a diode 22 of the illustrated polarity are connected in series between them, and a circuit for dividing the output voltage of the constant voltage circuit 18 is configured by these.
The positive input terminal (+) of the operational amplifier 23 is connected to the line L 2 via the time constant capacitor 24 and the diode 22, and is also connected to the line L ₂ through the resistor 2.
5, and the positive input terminal (+) is connected to the line L ₃ through a resistor 26 and a diode 22.
connected to line L ₂ via. Further, a resistor 27 is connected between the output terminal and the negative input terminal (-) of the operational amplifier 23, and
A resistor 28 is connected between the output terminal of No. 3 and the positive input terminal (+). Then, the above-mentioned operational amplifier 23, capacitor 24, resistors 25, 26,
Reference numerals 27 and 28 form a square wave oscillator 29 of a well-known configuration, and this square wave oscillator 29 outputs a square wave voltage Va having the waveform shown in FIG. 4a.
Furthermore, in the square wave generation circuit 19, the square wave voltage Va is applied to the negative input terminal (-) of an operational amplifier 30 that acts as an inverting circuit, and the positive input terminal (+) of this operational amplifier 30 is A constant DC voltage is input from the common connection point of the resistors 20 and 21. Therefore, the operational amplifier 30 outputs an inverted square wave voltage Vb as shown in FIG. and 32 (output terminal and negative input terminal of the operational amplifier 30) will output a square wave AC voltage.

An electrical resistance humidity sensor 33, output correction resistors 34 and 35, and a thermistor 36 are connected in series between the output terminals 31 and 32 in FIG. 1 so that the square wave AC voltage is applied. Further, an output correction resistor 37 is connected in parallel with the series circuit of the humidity sensor 33 and the resistor 34, and a resistor 38 is connected in parallel with the thermistor 36. The humidity sensor 33 is arranged to sense the atmospheric humidity around the ultrasonic humidifier, and an example of its specific configuration is shown in FIG. That is, the humidity sensor 33 has a porous ceramic sintered body 40 disposed in a case 39 having a ventilation net 39a on the circumferential side thereof, and a ceramic porous sintered body 40 pulled out from both opposing sides of the porous sintered body 40. Lead wires 41, 41 to terminals 42, 42
The terminals 42, 42 are connected to each other due to the water molecule adsorption phenomenon of the porous sintered body 40.
The decrease in resistance value between the two corresponds to the atmospheric humidity. Therefore, the detection terminal 43 (resistor 34
The atmospheric humidity can be detected based on the voltage change characteristics of Further, the equivalent circuit of this humidity sensor 33 corresponds to a parallel connection of a resistance component R ₀ that changes depending on the atmospheric humidity and a unique capacitor component C ₀ as shown in FIG.
The thermistor 36 connected in series to the humidity sensor 33 is for correcting the output voltage characteristics of the humidity sensor 33 (i.e., the output voltage characteristics from the detection terminal 43) according to the ambient humidity. A resistor 38 is provided for characteristic matching of the thermistor 36. Note that 44 is a noise prevention capacitor connected between the detection terminal 43 and the line _L2 . 45 is an operational amplifier for output conversion;
This constitutes a humidity detection circuit 46 together with the resistors 34, 35, 37, 38 and thermistor 36, and its positive input terminal (+) is connected to the output terminal, and its negative input terminal (-) is connected to the detection terminal 43. The output terminal is connected to an intermediate terminal 48 via a resistor 47. The intermediate terminal 48 is connected to the output terminal 32 via a diode 49 with the polarity shown, and is also connected to an output terminal 51 via a diode 50 with the polarity shown, and the output terminal 51 is connected to a smoothing capacitor. 52 to line _L2 .

Now, 53 is a humidity setting circuit, which is constructed by connecting a series circuit of a resistor 54, a variable resistor 55, and a resistor 56 between the lines _L3 and _L2 .
The desired set humidity PHa (fifth
(see figure)). Reference numeral 57 denotes an operational amplifier constituting the voltage difference detection circuit 58, the positive input terminal (+) of which is connected to the output terminal 51 via a resistor 59 and to the line _L2 via a resistor 60.
The negative input terminal (-) is connected to the sliding terminal 55 of the variable resistor 55 via the resistor 61.
a and to an output terminal via a resistor 62, and the output terminal is connected to line _L2 via a resistor 63.

On the other hand, 64 is a control circuit, which will be described below. That is, 65 and 66 are lines L ₁ and L ₂
A bias resistor connected in series between
The common connection point is connected to the sliding terminal 13a of the variable resistor 13 via a diode 67 of the polarity shown. 68 and 69 are NPN type transistors, each emitter is connected to line _L2 , and the collector of transistor 68 is connected to resistor 7.
0 to the common connection point of resistors 65 and 66, and the collector of transistor 69 is directly connected to resistor 6
5 and 66 common connection points. 71
and 72 is an operational amplifier serving as a voltage comparison circuit;
Each negative input terminal (-) is connected to the output terminal of the operational amplifier 57, and resistors 73 and 74 are connected between each positive input terminal (+) and the output terminal, respectively. The output terminal is connected to the transistor 68 via resistors 75 and 76.
and 69 bases, respectively. 77
is a reference voltage generation circuit, which is connected to lines L ₃ ,
The common connection point of the resistors 78 and 79 is connected to the positive input terminal (+) of the operational amplifier 71, and the common connection point of the resistors 79 _and 80 is connected to the positive input terminal (+) of the operational amplifier 71. is connected to the positive input terminal (+) of the operational amplifier 72.

Next, the operation of this embodiment will be explained.

When the power switch 4 is turned on, the fan motor 1 is energized and driven by the AC power supply 3, and a DC voltage is output between the lines _L1 and _L2 , and further, the fan motor 1 is outputted between the lines _L1 and _L2. A constant DC voltage is output during this period. Therefore, the voltage divided by the resistors 65 and 66 causes the diode 67 and the variable resistor 1 to
A base current flows into the transistor 10 through the transistor 3, and the LC oscillation circuit 9 starts to perform an oscillation operation, and accordingly, the ultrasonic vibrator 2 is driven to perform humidification operation. In this case, resistors 65 and 6
When the base current flows through the transistor 10 due to the divided voltage of 6, the LC oscillation circuit 9 performs oscillation operation at maximum output, and therefore, the amount of humidification by the ultrasonic vibrator 2 is large and strong humidification operation is performed. It will be done. Also, by outputting a DC constant voltage between lines L ₃ and L ₂ , the square wave generation circuit 1
9 is driven to output a square wave AC voltage between its output terminals 31 and 32 based on the square wave voltages Va and Vb, and this square wave AC voltage is applied to the humidity sensor 33, resistors 34 and 35, and thermistor 36. applied to the series circuit. Then, as shown in FIG. Given. In this case, since the diode 49 is cut off when the square wave voltage Va is output to the output terminal 32, the detection voltage Vc is output to the intermediate terminal 48 only during the output period of this square wave voltage Va, and the As shown in FIG. 4d, the intermediate terminal 48 has an intermediate output voltage.
Vd is generated. Further, this intermediate output voltage Vd is smoothed by a smoothing capacitor 52 via a diode 50, so that a DC output voltage Ve is outputted to the output terminal 51 as shown in FIG. 4e. become. In this case, this output voltage Ve is
As shown in Figure 5, where humidity RH (%) is plotted on the horizontal axis, it exhibits a curved shape that gradually decreases from the low humidity side to the high humidity side, and from the low humidity side to the high humidity side. Therefore, the rate of change is set to a characteristic that increases sequentially, and this setting is applied to the humidity sensor 3.
Output correction resistor 34, connected in parallel to 3
This is done by appropriately selecting the resistance values of 5 and 37. On the other hand, in the humidity setting circuit 53, by operating the sliding terminal 55a of the variable resistor 55 as desired, the reference voltage Vf, for example, the reference voltage Vf ₂ (set humidity RH ₁ ) on the low humidity side or the reference voltage on the high humidity side The operational amplifier 57 which outputs the voltage Vf ₁ (set humidity RH ₂ ) and is supplied with the output voltage Ve and the reference voltage Vf ₂ or Vf ₁ outputs the voltage difference (Ve−Vf ₂ ) or (Ve− Vf ₁ ), which is output by the operational amplifiers 71 and 72.
It will be applied to the negative input terminal (-) of Then, in the reference voltage generation circuit 77,
A reference voltage Vg is output to the common connection point of resistors 78 and 79, and a reference voltage Vh is output to the common connection point of resistors 79 and 80, and these reference voltages Vg and Vh (Vg>Vh) are connected to the operational amplifier. Since the operational amplifiers 71 and 72 are connected to the positive input terminals (+) of 71 and 72, respectively, the difference voltage (Ve-Vf ₂ ) or (Ve-Vf ₁ ) and the reference voltage
Compare Vg and Vh respectively. In this case, when the humidity of the humidified atmosphere such as indoors is low, the electrical resistance value of the humidity sensor 33 is high, and therefore the output voltage Ve
is large and the differential voltage (Ve−Vf ₂ ) or (Ve−Vf ₁ )
is also large, (Ve−Vf ₂ )>Vg, Vh or (Ve−
There is a relationship of Vf ₁ )>Vg, Vh, so that the output signals of the operational amplifiers 71 and 72 are at a low level. As a result, the atmospheric humidity gradually increases due to the strong humidification operation as described above, and the output voltage Ve gradually _decreases. (Ve−
Vf ₁ ) becomes smaller than the reference voltage Vg (in Figure 5, at output voltage Vf ₂ ' and humidity RH ₁ ' or output voltage Vf ₁ ' and humidity RH ₂ ', (Vf ₂ ' - Vf ₂ ) =
The relationship is (Vf ₁ ′−Vf ₁ ). ), the output signal of the operational amplifier 71 becomes high level and the transistor 68
is turned on, and as a result, the resistor 70 is connected in parallel to the resistor 66. Therefore, the divided voltage generated at the common connection point of the resistors 65, 66, and 70 becomes smaller, and the base current of the transistor 10 decreases accordingly.
The oscillation output of the ultrasonic vibrator 2 becomes small, the amount of humidification by the ultrasonic transducer 2 decreases, and the operation is switched to a weak humidification operation. After that, when the atmospheric humidity further increases and the differential voltage (Ve-Vf ₂ ) or (Ve-Vf ₁ ) becomes approximately zero, that is, the atmospheric humidity becomes approximately the set humidity RH ₁ or RH ₂ , and the output voltage Ve becomes the reference voltage. When it becomes approximately equal to Vf ₂ or Vf ₁ , the output signal of the operational amplifier 72 becomes high level and the transistor 69 is turned on. Therefore, the resistor 66 is shorted and the base current does not flow through the transistor 10, and the LC The oscillation circuit 9 stops its oscillation operation, thereby stopping the humidifying operation. Thereafter, when the atmospheric humidity becomes lower than the set humidity RH ₁ or RH ₂ , the above-described operation is repeated.

According to this embodiment, the following effects can be obtained. In other words, since the atmospheric humidity is detected as a change in electrical resistance value using the electrical resistance type humidity sensor 33, the responsiveness is improved compared to the case where the humidifier output is controlled according to the change in room temperature detected by a conventional thermistor. is good. Further, the humidity detection circuit 4 based on humidity detection by the humidity sensor 33
_{The difference} voltage _{( Ve}
−Vf ₂ ) or (Ve−Vf ₁ ) is detected by the differential voltage detection circuit 58, and the LC oscillation circuit 9 is adjusted according to the magnitude of the differential voltage (Ve−Vf ₂ ) or (Ve−Vf ₁ ). The oscillation output is controlled in two steps, and the system automatically switches to two steps: strong humidification operation and weak humidification operation, so that when the atmospheric humidity approaches the set humidity, weak humidification operation is always activated. This makes it possible to perform adjustment control with less humidity ripple.
Furthermore, as mentioned above, the atmospheric humidity is the set humidity.
When RH approaches ₁ or ₂ , strong humidification operation switches to weak humidification operation, so the user knows that the atmospheric humidity is low due to strong humidification operation and switches to weak humidification operation. This allows you to know when the atmospheric humidity has increased to near the set humidity, which is extremely convenient for use. In addition, the humidity RH-output voltage Ve characteristic of the humidity detection circuit 46 is set so that the rate of change increases successively from the low humidity side to the high humidity side, as shown in FIG. Therefore, the weak humidification operation period Tb ₁ (Ta ₁ is the strong humidification period) when the low humidity setting is set to RH 1 is greater than the weak humidification operation period Tb ₂ (Ta _{2 is} the strong humidification period) when the high humidity setting is set to RH ₂ . operation period)
is smaller (Tb ₁ > Tb ₂ ). Therefore, if the setting is on the high humidity side that requires a large amount of humidification, strong humidification operation will be performed until the atmospheric humidity approaches the set humidity. By doing so, the atmospheric humidity can be quickly brought to the set humidity. Then, the humidity of the humidity detection circuit 46 as shown in FIG.
Since the RH-output voltage Ve characteristic can be obtained with a simple configuration by appropriately selecting the resistance values of the output correction resistors 34, 35, and 37 connected directly and in parallel to the humidity sensor 33, manufacturing is easy.

In the above embodiment, the humidity of the humidity detection circuit 46 is -
Although the output voltage characteristics are set as shown in FIG. 5, the characteristics may be such that the output voltage has a slope opposite to that shown in FIG. 5, that is, the output voltage increases sequentially from the low humidity side to the high humidity side.

Further, in the above embodiment, the control circuit 64 is used to switch between two stages of strong humidification operation and weak humidification operation, but if additional circuits each consisting of a combination of a transistor 68, a resistor 70, and an operational amplifier 71 are arranged in parallel, three stages can be performed.
It is possible to switch to multiple stages.

〔Effect of the invention〕

As explained above, the automatic control device for a humidifier of the present invention uses an electric resistance type humidity sensor that changes the electric resistance value according to the humidity, and a humidity detection circuit based on the humidity detection of the humidity sensor. Since the humidifier output is changed in stages according to the voltage difference between the output voltage and the reference voltage from the humidity setting circuit that provides the set humidity, it is possible to perform control with good responsiveness and little humidity ripple. I can,
Furthermore, it is extremely convenient to use because it is possible to know the level of atmospheric humidity based on the state of the humidifier output.Moreover, the humidity-output voltage characteristic of the humidity detection circuit can be changed from the low humidity side to the high humidity side. Since the humidity setting circuit is set so that the rate of change is large, the atmospheric humidity can be quickly adjusted to the set humidity even when the humidity setting circuit is set to the high humidity side. It is.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an overall electrical connection diagram, FIG. 2 is a schematic longitudinal sectional view of the humidity sensor, FIG. 3 is an equivalent circuit diagram of the humidity sensor, and FIG. 4 A to e are output voltage waveform diagrams of each part for explaining the operation, and FIG. 5 is a humidity-output voltage characteristic diagram for explaining the operation. In the drawing, 1 is a fan motor, 2 is an ultrasonic vibrator, 9 is an LC oscillation circuit, 13 is a variable resistor, 19 is a square wave generation circuit, 33 is a humidity sensor, 46 is a humidity detection circuit, 53 is a humidity setting circuit, 58 is a voltage difference detection circuit, and 64 is a control circuit.

Claims (1)

[Scope of Claims] 1. An ultrasonic vibrator that is provided in an aquarium and, when driven, irradiates ultrasonic waves to the water in the aquarium to atomize it, and an oscillation device that includes an oscillation transistor and drives the ultrasonic vibrator. In a humidifier equipped with a circuit and a fan motor that discharges mist generated by driving the ultrasonic vibrator to the outside, the humidifier is provided to detect atmospheric humidity and whose electrical resistance value changes according to the humidity. A sensor, and a humidity detection circuit that converts the electrical resistance value of the humidity sensor into a voltage, and the humidity-output voltage characteristic is set such that the rate of change increases from the low humidity side to the high humidity side. , a humidity setting circuit that outputs the desired humidity as a voltage, a voltage difference detection circuit that outputs the difference in output voltage between the humidity detection circuit and the humidity setting circuit, and a reference voltage generator that generates desired multiple levels of reference voltage. a circuit, at least two voltage comparison circuits that respectively compare the plurality of reference voltages generated from the reference voltage generation circuit and the output voltage from the voltage difference detection circuit; An automatic control device for a humidifier, comprising: a circuit that increases or decreases a base current for the oscillation transistor in a stepwise manner to change an oscillation output of the oscillation circuit in a stepwise manner. 2. The automatic humidifier according to claim 1, wherein the temperature-output voltage characteristic of the humidity detection circuit is set by an output correction resistor connected directly and in parallel to the humidity sensor. Control device.