JPH0334684Y2 - - Google Patents

Description

[Detailed explanation of the idea] Industrial applications The present invention relates to a humidifier.

BACKGROUND ART In a conventional humidifier, as shown in FIG. 4, for example, an alternating current voltage must be applied to a humidity sensor 1, and the effective value of the voltage must also be kept small. A circuit 4 that amplifies the signal detected by the humidity sensor 1, a display circuit 5 that uses the amplified signal to display humidity using a light emitting element, etc.
A DC power supply of around 10V is required. Therefore, in the conventional circuit for detecting and displaying humidity, the AC voltage obtained from the secondary coil 12 of the power transformer 3 is rectified, and the oscillation circuit 2 generates a low voltage as shown in FIG. It was a humidifier that applied an alternating current voltage to the humidity sensor 1.

Problems to be Solved by the Invention However, the conventional humidifier requires an oscillation circuit 2 as shown in FIG. 4, which poses the problem of increasing the cost of the circuit used in the humidifier.

Measures to solve the problem: Connect two Zener diodes and a resistor in series with each other with opposite polarity to the secondary coil of the power transformer, and connect a humidity sensor and a resistor to both ends of the two Zener diodes. This is a humidity detection circuit that connects the series circuits in parallel.

Function: Without using an oscillator circuit, the AC voltage of the secondary coil of the power transformer taken out to supply the amplifier circuit and display circuit is lowered and the commercial frequency voltage is directly applied to the humidity sensor. , the price of circuits used in humidifiers has become cheaper.

Example An embodiment of the present invention will be explained with reference to the drawings.

A Zener diode 8 connected in series with opposite polarity is connected to both end points of the secondary coil 12 of the power transformer 3 via a resistor 7.
The resistor 7 controls the current flowing through the Zener diode 8. The Zener diode 8 connected with the opposite polarity is used to create a constant voltage, and the voltage applied between points is as shown in Figure 2, and the voltage applied between the points of the secondary coil 12 is as shown in Fig. 2. The voltage is lower than the voltage. A capacitor 9 and a resistor 1 are connected between the points.
Humidity sensor 1 and resistor 11 connected in parallel with 0
are connected in series, and these form a circuit connected in parallel with the Zener diode 8. Then, the voltage applied to the resistor 11 from the point is extracted as a detection signal. The capacitor 9 is connected to prevent direct current generated anywhere in the circuit from reaching the humidity sensor 1. In addition, between the points, there is an amplifier circuit 4 for amplifying the detection signal taken out from the points.
A rectifier circuit 6 is connected for supplying DC power to a display circuit 5 that uses the amplified signal to cause a light emitting element or the like to emit light.

The operation of the above configuration will be explained next.

A constant voltage with a low waveform value as shown in FIG. 2 is applied between the points, and as the humidity changes, the resistance value of the humidity sensor 1 changes, so the voltage applied to the resistor 11, that is, the point - The effective value of the voltage between the points changes as shown in FIG. The point-to-point voltage that has changed due to the humidity is amplified by an amplifier circuit 4, and the humidity is displayed by a display circuit 5 using a light emitting element or the like.

Effects of the invention As mentioned above, in the circuit of the invention, the AC voltage applied to the humidity sensor is not obtained from the oscillator but directly from the secondary coil of the power transformer.
The price of the entire circuit can be reduced.

In addition, the voltage applied to the humidity sensor is kept constant by a Zener diode, so even if the power supply voltage fluctuates, a voltage higher than the maximum rating will not be applied to the humidity sensor, which protects the humidity sensor. It is a very useful thing.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a humidifier showing an embodiment of the present invention. FIG. 2 shows a voltage waveform diagram applied between points, and FIG. 3 shows a characteristic diagram of changes in voltage at points due to humidity. FIG. 4 shows a circuit diagram of a conventional humidifier, and FIG. 5 shows a diagram of voltage waveforms occurring at points. 1...Humidity sensor, 3...Power transformer, 4
...Amplification circuit, 5...Display circuit, 6...Rectifier circuit, 7, 11...Resistor, 8...Zener diode, 12...Secondary side coil.

Claims (1)

[Scope of utility model registration request] Two Zener diodes 8 and a resistor 7, each having opposite polarity and connected in series, are connected in series to the secondary coil 12 of the power transformer 3, and a humidity sensor 1 is connected to both ends of the two Zener diodes 8.
and a resistor 11 are connected in parallel, and a humidity detection circuit extracts a voltage obtained from a point where the humidity sensor 1 and the resistor 11 are connected as a detection voltage of the humidity sensor 1, and the power supply A rectifier circuit 6 is connected to the secondary coil 12 of the transformer 3, and an amplifier circuit 4 that amplifies the detection voltage obtained from the humidity detection circuit is connected to both ends of the rectifier circuit 6, and the magnitude of the output voltage of the amplifier circuit 4. A humidifier characterized in that a display circuit 5 is connected to display the current humidity.