JPS6325819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic atomization device that vibrates a vibrator at a high frequency and uses the vibrator to emit ultrasonic waves into a liquid to atomize the liquid. An object of the present invention is to provide an ultrasonic atomization device that can prevent parts constituting a vibrator and a circuit from being destroyed when the liquid to be used runs out.

What is an ultrasonic atomizer? A piezoelectric vibrator attached to the bottom of the liquid to be atomized is driven by an oscillation circuit, and ultrasonic waves are emitted above the liquid surface to atomize the liquid into fine particles. It is something that makes you Recently, demand for such ultrasonic atomization devices has been increasing for use in humidification and atomization of chemical solutions.

FIG. 1 shows a circuit of the main parts of a conventional ultrasonic atomizer, and FIG. 2 shows power waveforms at various points in this circuit. In Fig. 1, 1a and 1b are single-phase AC power input terminals, 2a, 2b, 2c, and 2d are diodes that constitute a rectifier circuit, 3 is a capacitor for noise removal, 4 is an output terminal of the rectifier circuit, and 5 is a rectifier circuit. 6 is a voltage dividing resistor that applies a bias voltage to the base of transistor 7. 8, 9, and 10 are capacitors, 11 is a resistor, and 12 is a vibrator, which constitute a Colpitts oscillation circuit. 13 is a chiyoke coil, 1
4 is the collector terminal of the transistor 7.

In the circuit with the above configuration, an AC voltage shown in FIG. 2a is applied between power input terminals 1a and 1b,
This applied AC voltage is applied to the diodes 2a, 2
Figure 2b is an oscillation circuit composed of b, 2c, and 2d.
It is full-wave rectified as follows. In other words, capacitor 3 has a small capacitance of about 0.02μF, and is provided for the purpose of removing noise from the output side, and the full-wave rectified waveform voltage shown in Figure 2b is applied to point 4 of the circuit. It appears as it is. In addition, the circuit portion 14 includes a transistor 7, capacitors 8, 9,
10, a resistor 11, and a vibrator 12. The voltage waveform shown in FIG. 2c appears when the high frequency voltage generated by the oscillation circuit is modified by the power supply voltage shown in FIG. 2b. The vibrator 12 performs high frequency vibration as shown in FIG. 2c and emits ultrasonic waves into the liquid.

In the conventional ultrasonic atomizer described above, as long as there is a liquid to be atomized, the vibrator 12 is immersed in this liquid, and the vibrator 12 is cooled by this liquid. However, when the liquid to be atomized runs out, the vibrator 12 is exposed to the air, and the vibrator 12 becomes extremely hot, resulting in its destruction.

The present invention eliminates the above-mentioned conventional drawbacks by immediately stopping the atomizing operation when the liquid to be atomized runs out, thereby preventing the destruction of the vibrator and the circuit components that occur following the destruction of the vibrator. The present invention provides an ultrasonic atomizer equipped with a protection circuit that prevents damage to the ultrasonic atomizer.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 3 is a circuit diagram of an ultrasonic atomization device which is an embodiment of the present invention. In FIG. 3, the circuit other than the broken line part 15 is the same as the circuit of the conventional ultrasonic atomizer shown in FIG. 1, so the circuit other than the broken line part 15 in FIG. They are numbered.

The broken line portion 15 in FIG. 3 is a protection circuit, and 1
6 and 17 are resistors for dividing the collector voltage of the oscillation transistor 7, 18 and 19 are transistors, and 20, 21, and 22 are resistors, and these constitute a differential amplifier circuit.

23 and 24 are a resistor and a semi-fixed resistor, respectively, for dividing the power supply voltage of the output terminal 4 of the rectifier circuit and applying it to the base of the transistor 19. 2
5, 26, and 27 are diodes, resistors, and capacitors, and constitute a smoothing circuit that converts the power supply voltage appearing at the output terminal 4 of the rectifier circuit into an almost perfect DC voltage. 28 and 29 are transistors, 30 is a resistor provided between the collector of the transistor 18 and the base of the transistor 28, 31 is a resistor provided on the collector side of the transistor 28, and 32 is a resistor provided between the collector of the transistor 28 and the base of the transistor 29. This is the resistance provided.
33 is the base terminal of the transistor 18;
4 is the base terminal of the transistor 19.

In such a circuit configuration, it is assumed that there is now a sufficient amount of liquid to be atomized, and the vibrator 12 is immersed in this liquid and is operating normally. At this time, the semi-fixed resistor 24 is adjusted so that the base voltage of the transistor 19, which is a voltage obtained by dividing the power supply voltage of the oscillation circuit appearing at the output terminal 4, is lowered from the base voltage of the transistor 18, which is a voltage obtained by dividing the oscillation voltage. Set it high. Transistors 18 and 19 constitute a differential amplifier circuit, and when set in this way, transistor 18 is off and transistor 18 is off.
The collector voltage of is at a high level. Therefore, the base current of transistor 28 does not flow and transistor 28 is off. Therefore, the collector voltage of the transistor 28 is zero, the transistor 29 is off, and a normal bias voltage is applied to the base of the oscillating transistor 7 from the output terminal 4, so that the oscillating operation continues as specified.

Next, when there is no more liquid to atomize, the vibrator 12 is exposed to the air and the collector voltage of the oscillating transistor 7 increases, so that the base voltage of the transistor 18 becomes higher than the base voltage of the transistor 19. Become.

Therefore, transistor 18 is turned on, and the base current of transistor 28 flows through transistor 28.
turns on. When the transistor 28 is turned on, the base current of the transistor 29 flows and the transistor 2
9 turns on.

When the transistor 29 is turned on, the base bias of the oscillation transistor 7 becomes zero, the transistor 7 is turned off, and the oscillation operation is stopped.

4a to 4d show voltage waveforms at various locations in the circuit of FIG. 3. FIG. Figure 4a shows the voltage waveform at the output terminal 4 of the rectifier circuit, with diodes 2a,
It represents the output voltage of the rectifier circuit composed of 2b, 2c, and 2d.

FIG. 4b shows a voltage waveform at the base terminal 33 of the transistor 18 when there is a liquid to be atomized, and represents the voltage obtained by dividing the collector voltage of the oscillating transistor 7 by the resistors 16 and 17.
FIG. 4c shows the voltage waveform at point 33 of the circuit as in FIG. 4b, but in the case where there is no liquid to be atomized.

FIG. 4d shows a voltage waveform at the base terminal of the transistor 19, and represents the voltage obtained by dividing the output voltage of the rectifier circuit shown in FIG. 4a by the resistor 23 and the semi-fixed resistor 24.

FIG. 5 is a diagram in which the voltage waveforms b, c, and d of FIG. 4 are superimposed and the magnitudes of the voltages are compared. The voltage of c when there is no liquid to be atomized is the highest, the next largest is the voltage of d which is the divided voltage of the power supply voltage of the oscillation circuit, and the voltage of b when there is liquid to be atomized is the smallest. . voltage of b and voltage of c or b
The magnitude of the voltage d and the voltage d are compared to start or stop the atomization operation. In case b, normal atomization operation is performed, and in case c, atomization operation is stopped.

As described above, when the liquid to be atomized runs out, the atomizing operation of the ultrasonic atomizer can be stopped to prevent damage to the vibrator and circuit components.

Next, another embodiment of the present invention is shown in FIG. The circuit configuration shown in the figure has a structure in which a broken line portion 35 is added to the circuit configuration shown in FIG. 3 showing the first embodiment. Broken line part 35
Other than that, it is the same as Fig. 3.

In the figure, 36 is a thyristor, 37 is a resistor provided on the anode side of the thyristor 36,
38 is a transistor, 39 is a resistor provided between the base of the transistor 38 and the anode of the thyristor 36, and 40 is a resistor provided on the collector side of the transistor 38.

A feature of FIG. 6 is that the output of the transistor 28 is received by the thyristor 36.

In the above configuration, when the liquid to be atomized runs out and the vibrator 12 is exposed to the air, the collector voltage of the transistor 7 increases and the transistor 18 is turned on.
is also turned on, and the gate voltage of the thyristor 36 rises due to the rise in the collector voltage of the transistor 28.
Thyristor 36 is turned on. Then thyristor 3
Since the anode voltage of transistor 6 becomes zero, transistor 38 is turned off, the collector voltage of transistor 38 increases, and transistor 29 is turned on. Therefore, the base bias of transistor 7 becomes zero and the oscillation operation stops.

The advantage of the above embodiment is that since a thyristor is used in the switching circuit, once the oscillation operation stops, it continues in that state, making the operation more reliable.

FIG. 7 shows yet another embodiment. The circuit configuration in the same figure is the transistor 19 and resistors 21 and 2 in FIG.
2 is removed, the emitter side of the transistor 18 is connected to one side of the semi-fixed resistor 24, a resistor 41 is connected between the gate of the thyristor 36 and the ground, and a resistor 4 is connected between the gate of the thyristor 36 and the collector of the transistor 28.
2 are connected to each other.

That is, the collector voltage of the oscillating transistor 7 is connected to the base of the transistor 18 by connecting the resistors 16 and 17.
A voltage divided by 18 is applied, while transistor 18
A voltage obtained by dividing the voltage appearing at the output terminal 4 by a resistor 23 and a semi-fixed resistor 24 is applied to the emitter.

With this circuit configuration, the magnitude of the oscillation voltage and the magnitude of the power supply voltage are compared. That is, when there is a liquid to be atomized and the vibrator 12 is immersed in this liquid, the emitter voltage of the transistor 18 is higher than the base voltage of the transistor 18.
8 is off. Therefore, transistor 28
is off, thyristor 26 is off, transistor 3
8 is on, transistor 29 is off, the bias of transistor 7 is at a normal value, and a specified oscillation is performed.

Next, when there is no more liquid to atomize and the vibrator 12 is exposed to the air, the base voltage of the transistor 18 becomes higher than the emitter voltage, and the transistor 18 is turned on. Then, since the base current of the transistor 28 flows, the transistor 28 is turned on, the gate voltage of the thyristor 36 increases and the thyristor 36 is turned on, the base voltage of the transistor 38 is decreased, and the transistor 38 is turned off. Therefore, the transistor 29 is turned on, the base bias of the oscillating transistor 7 becomes zero, and the operation of the transistor 7 is stopped.

In the case of this embodiment, the divided voltage of the collector voltage of the oscillation transistor 7 is applied to the emitter of the transistor 18, and the divided voltage of the power supply voltage is applied to the emitter of the transistor 18.
Even if the input signal is input to the base of 8, it is possible to perform the same operation as described above by changing the configuration of the subsequent switching circuit.

As explained above, the ultrasonic atomizer of the present invention can be realized by simply adding a simple protection circuit to the basic circuit of a conventional ultrasonic atomizer.
When the liquid to be atomized runs out, the atomizing operation can be stopped to prevent damage to the vibrator and other parts of the circuit.

[Brief explanation of the drawing]

Figure 1 is a basic circuit diagram of a conventional ultrasonic atomizer.
Figures 2a, b, and c are voltage waveform diagrams at various points in the circuit of Figure 1, Figure 3 is a circuit diagram of an ultrasonic atomization device in an embodiment of the present invention, and Figures 4a, b, and c. ，
d and FIG. 5 are voltage waveform diagrams at various points in the circuit of FIG. 3, FIG. 6 is a circuit diagram of an ultrasonic atomizer according to another embodiment of the present invention, and FIG. 7 is a diagram of still another embodiment of the present invention. It is a circuit diagram of an ultrasonic atomization device in an example. 1a, 1b...Single-phase AC power input terminal, 2a,
2b, 2c, 2d...diode, 7...transistor, 8,9,10...capacitor, 11...
Resistor, 12... Vibrator, 15... Protection circuit, 1
6, 17...Resistor, 18, 19...Transistor, 23...Resistor, 24...Semi-fixed resistor.

Claims (1)

[Claims] 1. An ultrasonic atomizer comprising a rectifying circuit that rectifies single-phase alternating current, and an oscillating circuit that uses the output voltage of the rectifying circuit as a power supply voltage, the ultrasonic atomizing device comprising: The magnitude of the divided voltage obtained by dividing the collector voltage of the oscillation transistor to be oscillated by a resistor is compared with the divided voltage obtained by dividing the above power supply voltage by a resistor, and the divided voltage obtained by dividing the above power supply voltage by a resistor is used to generate the above oscillation. 1. An ultrasonic atomization device characterized by comprising a protection circuit that lowers the base bias voltage of the oscillation transistor to turn it off when the collector voltage of the oscillation transistor is higher than a divided voltage obtained by dividing the voltage of the oscillation transistor by a resistor. 2. The protection circuit has one transistor whose base input voltage is a divided voltage obtained by dividing the collector voltage of the oscillation transistor by a resistor, and the other transistor whose base input voltage is a divided voltage obtained by dividing the power supply voltage by a resistor. 2. The ultrasonic atomization device according to claim 1, comprising a differential amplifier circuit. 3. The protection circuit uses one of the divided voltages obtained by dividing the collector voltage of the oscillation transistor by a resistor and the divided voltage by dividing the power supply voltage by a resistor as a base input and the other divided voltage as an emitter input. The ultrasonic atomization device according to claim 1, comprising a transistor.