JPS6113135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for an ultrasonic humidifier that prevents thermal destruction due to dry firing of an atomizing vibrator that generates ultrasonic waves or deterioration of heat dissipation.

As is well known, ultrasonic humidifiers have a vibrator for atomization that generates ultrasonic waves placed in a water tank, but when used for a long period of time, more scale accumulates on the surface of the vibrator than on other parts. If this phenomenon is recognized as a fact and this accumulation occurs, the vibrator, which has been cooled by water, may have poor heat dissipation and may be thermally destroyed. Furthermore, if bubbles adhere to the surface of the vibrator or the water in the tank runs out, so that the vibrator is left in a so-called empty state, there is a risk of thermal destruction as well.

The present invention has been made to eliminate the above-mentioned drawbacks, and its purpose is to cut off and maintain the resonator current when the temperature of the resonator increases abnormally, to protect the resonator from thermal destruction, and to prevent the abnormal state from occurring. There is a protection device for ultrasonic humidifier that can be informed.

Each embodiment of the present invention will be described below with reference to the drawings in which common parts are denoted by the same reference numerals. Now, referring to the first embodiment shown in FIGS. 1 and 2, 1 and 2 are AC power supply terminals, one of which is connected to the AC input terminal of a full-wave rectifier circuit 4 via a power switch 3. . This full-wave rectifier circuit 4 is composed of diodes 5 to 8, a smoothing capacitor 9 is connected between the DC output terminals, and one DC bus bar 11 is connected to one DC output terminal via a high-frequency cutting coil 10. Then, the other DC bus 12 is connected to the other DC output terminal. Reference numeral 13 denotes an oscillation transistor whose collector is connected to one DC bus 11 and whose emitter is connected to the DC bus 12 through a parallel circuit of a resistor 14 and a capacitor 15. The oscillation transistor 13 constitutes a self-excited Colpitts type oscillation circuit 19 with the equivalent inductance of the oscillation capacitors 16 and 17 and the atomization vibrator 18, and for this reason,
One oscillation capacitor 16 is connected to the linear bus bar 11,1
The other oscillation capacitor 17 is connected between the base of the oscillation transistor 13 and the DC bus 12. 20 is an output transformer that couples the oscillation transistor 13 and the vibrator 18;
One end of the primary winding 21 is connected to the DC bus 11, the other end is connected to the base of the oscillation transistor 13 via the coupling capacitor 22, and the vibrator 18 is connected to the secondary winding 23 of the output transformer 20. Connecting. Here, as shown in FIG. 1, the vibrator 18 is placed at the bottom of the water tank 24 of the humidifier.
It is designed to atomize the water 25 inside. Also,
On the outer bottom surface of the vibrator 18, there is a temperature sensing element, such as a positive characteristic thermistor 26, for detecting the temperature of the vibrator 18.
has been set up. Again in FIG. 2, 27 is a temperature detection circuit including the thermistor 26, 28 is a current suppression circuit that receives the detection output of the temperature detection circuit 27 as input and suppresses an increase in the current of the vibrator 18, that is, the vibrator current, and 29 is a A stop circuit that cuts off the vibrator current in response to the amount of current suppression due to the action of the current suppression circuit 28 reaching a predetermined value, and includes a display circuit 30 that displays the operating status of the stop circuit 29. I'm letting you do it. Now, one end of the thermistor 26 is connected to the DC bus 12, and the other end is connected to the positive DC output terminal of the full-wave rectifier circuit 4 via the resistor 31. Further, a parallel circuit of a capacitor 32 and a potentiometer 33 is connected in parallel with the thermistor 26. The sliding terminal of this potentiometer 33 is connected to the base of one transistor 34 in the current suppression circuit 28 via a resistor 35, and a parallel circuit of a capacitor 36 and a resistor 37 is connected between the base and the DC bus 12. Connect. The emitter of the transistor 34 is directly connected to the DC bus 12,
The collector is connected to a common line 39 via a resistor 38, the base of the other transistor 40 is connected to the collector of the transistor 34, the emitter is connected to the common line 39, and the collector is connected to a parallel circuit of a resistor 41 and a capacitor 42. It is connected to the DC bus 12 via. The stop circuit 29 has a thyristor 43 connected in the forward direction between the common line 39 and the DC bus 12, the gate of which is connected to the DC bus 12 via a resistor 44, and a constant voltage conduction element 45 such as a Zener diode. is connected to the collector of transistor 40 via. Further, a resistor 46 is connected between the common line 39 and the DC bus 11, a capacitor 47 is connected between the common line 39 and the DC bus 12, and the common line 39 is connected to an oscillating transistor through a resistor 48. Connect to the base of 13. The display circuit 30 has a transistor 50 whose collector is connected to the DC bus 12 via a neon lamp indicator 49, whose base is connected to the common line 39 via a resistor 51, and whose emitter is connected via a resistor 52. Connect the collector to the DC bus 12, and connect the collector to the resistor 5.
3 to the DC bus 11.

Next, the operation of the above configuration will be explained. Now, when the power switch 3 is turned on and AC power is applied to the wave rectifier circuit 4, DC power is applied between the DC buses 11 and 12, and therefore the oscillation transistor 13,
The Colpitts-type oscillation circuit 19, whose basic configuration is the equivalent inductance of the oscillation capacitors 16, 17 and the vibrator 18, starts oscillating, and its frequency depends on the equivalent inductance of the oscillation capacitors 16, 17 and the vibrator 18. Furthermore, the amplitude of the vibrator current, and therefore the current value, is determined by the voltage division ratio between the equivalent resistance of the current suppression circuit 28 and the resistor 46 when viewed from between the base of the oscillation transistor 13 and the DC bus 12. The value depends on the base bias voltage of the transistor 13. As described above, the vibrator 18 is driven by the oscillation circuit 19, emits ultrasonic waves to the water 25 in the water tank 24, atomizes the water, and humidifies the room. Now, in the above operating state, the temperature of the vibrator 18 is always detected by the thermistor 26 with positive characteristics, and therefore,
A voltage depending on the temperature of the vibrator 18 is generated in the potentiometer 33 as a detection output, and this is generated in the resistor 33.
5 to the base of one transistor 34 in the current suppression circuit 28 to determine the value of the collector current of the other transistor 40. Therefore, water scale is now deposited on the surface of the vibrator 18,
Alternatively, the vibrator 18 may become empty due to the adhesion of bubbles or the lack of water in the tank.
As the temperature increases, the voltage between the terminals of the thermistor 26 and the potentiometer 83 increases, which causes the collector voltage of the transistor 34 to drop, causing the emitter voltage of the other transistor 40 and the common line 39 to decrease. Since the voltage drops and the base bias voltage of the oscillation transistor 13 is lowered, an increase in the vibrator current is suppressed, and the vibrator 18 continues to be driven in a state where the temperature rise is suppressed. During such a vibrator current suppression action, if the vibrator 18 reaches an abnormal temperature rise state that further increases its vibrator current, that is, the vibrator 18 is suppressed by the vibrator current suppression by the current suppression circuit 28. When the state reaches a state where protection cannot be achieved by the action, the resonator current is about to become extremely large, and the collector current of the transistor 40 increases due to the increase in the amount of suppression associated with this, so the terminal voltage of the resistor 41 increases. Constant voltage conduction element 4
When the constant voltage conduction element 45 becomes conductive, the thyristor 43 receives the gate signal and turns on. Therefore, the potential of the common line 39 drops to approximately the potential of the DC bus 12, the oscillation transistor 13 is turned off, the driving of the vibrator 18 is stopped, and the vibrator 18 is protected from thermal damage. At the same time, as the potential of the common line 39 drops, the transistor 50, which had been in the on state,
turns off, the indicator lamp 49 lights up,
It is notified that the stop circuit 30 has been activated, that is, the driving of the vibrator 18 has been stopped due to a protective action. This allows the user to know whether it is necessary to clean the vibrator 18 or replenish water. According to this embodiment, after the thyristor 43 is turned on, it automatically maintains this state until the power is cut off, so a special self-holding circuit is not required and the configuration is simplified. Furthermore, since it is determined by the constant voltage conduction element 45 provided in the gate circuit of the thyristor 43 that the amount of suppression of the vibrator current by the current suppression circuit 29 has reached a predetermined value, variations in the start of operation of the thyristor 43 are prevented. This can be prevented from occurring.

In the second embodiment shown in FIG. 3, another thyristor 54 is provided in place of the thyristor 43 in FIG. While connecting to the positive DC output terminal of the wave rectifier circuit 4, a relay contact 56 is connected between the positive DC output terminal and the DC bus 11 on the receiving/closing side contact piece (c-b).
The fixed contact piece a between the normally open side contact pieces (c-a) is connected to the DC bus 12 via a resistor 57 and an indicator lamp 49. In this second embodiment, when the thyristor 54 is turned on by the same action as in the case of FIG. is turned off and cuts off the DC power supply of the oscillation circuit 19, and at the same time the contact piece (ca) is turned on and the indicator lamp 49 is turned on.
is lit. As a modification of the second embodiment, although not shown, a relay contact may be provided in series with the vibrator 18 to directly cut off the vibrator current.

As described above, the present invention can protect the vibrator from thermal destruction by cutting off and holding the vibrator current when the temperature of the vibrator rises abnormally due to dry firing or poor heat dissipation. It is possible to provide a protection device for an ultrasonic humidifier that can notify a user of the condition.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the arrangement of a vibrator and thermistor in a first embodiment of the present invention, and FIGS. 2 and 3 are wiring diagrams showing the first and second embodiments, respectively. In the figure, 13 is an oscillation transistor, 16 and 1
7 is an oscillation capacitor, 18 is a vibrator, 19 is an oscillation circuit, 26 is a thermistor, 27 is a temperature detection circuit, 28 is a current suppression circuit, 29 is a stop circuit, 30
1 is a display circuit, 43 and 54 are thyristors, 55 is a relay coil (switch device), and 56 is a relay contact (switch device).

Claims (1)

[Claims] 1. An oscillation circuit that drives an atomizing vibrator, a temperature detection circuit that detects the temperature of the vibrator, and an output that flows to the vibrator in response to the detection output of this temperature detection circuit reaching a predetermined value. A protection device for an ultrasonic humidifier, comprising a stop circuit that cuts off a vibrator current and maintains the cut off state, and a display circuit that displays the cut off state of the vibrator current by the stop circuit.