JPS599724Y2 - Ultrasonic atomizer - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ultrasonic atomizer that atomizes liquid using ultrasonic waves generated by applying an oscillation voltage to a piezoelectric vibrator. An object of the present invention is to provide an ultrasonic atomization device that prevents excessive inrush current from flowing through a vibrator or the like.

Recently, demand for ultrasonic atomizers has been increasing as atomizers and humidifiers for chemical liquids and the like.

The ultrasonic atomizer drives a piezoelectric vibrator 2 attached to the bottom of the liquid 1 to be atomized by an oscillation circuit 3, as shown in Fig. 1 a, l), and directs ultrasonic waves 4 onto the liquid surface. The liquid 1 is atomized into fine particles by radiating the liquid 1.

As shown in FIG. 1a, when the driving oscillation circuit 3 of the vibrator 2 starts, the liquid level 6 is horizontal, and the first ultrasonic wave 4 emitted from the vibrator 2 is completely absorbed by the horizontal liquid level 6. It is reflected and becomes a reflected ultrasonic wave 5, which excites the piezoelectric vibrator 2 in the opposite direction.

If the reflected ultrasonic wave 5 generated at the moment of the start of this operation has large energy, a large so-called inrush current will be generated in the vibrator 2 by the reflected ultrasonic wave 5.
This will accelerate the deterioration of the vibrator 2.

On the other hand, once the atomization operation starts and a water column 7 is formed on the water surface 6 as shown in FIG. Since the water surface 6 is wavy, the reflection of the ultrasonic wave 4 on the liquid surface becomes diffuse reflection 8, and even if the energy of the ultrasonic wave 4 emitted from the vibrator 2 is large, it hardly affects the vibrator 2.

As described above, the vibrator 2 of the ultrasonic atomizer shown in FIG.
If the energy of the ultrasonic waves 4 emitted from the transducer 4 is made very weak initially, no inrush current will be generated due to the reflected ultrasonic waves 5, and deterioration of the transducer 2 can be prevented.

The above phenomenon will be explained in detail with reference to FIG. 2, which shows an oscillation circuit of a conventional ultrasonic atomizer, and FIG. 3, which shows voltage waveforms at various parts of the circuit.

In FIG. 2, 9 is an input terminal, 10 to 13 are diodes that connect the single-phase full-wave rectifier circuit, and 14 is a capacitor connected between the output terminal 15 of the full-wave rectifier circuit and the ground.
16.17 is also a resistor connected between the output terminal 15 and the ground, 18 is a transistor 19, and a capacitor 20.
, 21, 22, a resistor 23, and a vibrator 2. The vibrator 2 emits ultrasonic waves into the liquid to atomize the liquid, as described above.

Reference numerals 24 and 25 denote a switch and a variable resistor connected in series between the connection point of the resistors 16 and 17 and the input terminal of the oscillation circuit 18, and the variable resistor 25 serves to adjust the amount of atomization.

26 is a chalk koi nore. and oscillation circuit 18
By turning on the switch 24, oscillation is started and atomization operation is performed.

Note that the capacitor 14 has a small capacitance of about 0.02 μF, and is provided for the purpose of removing noise from the oscillation output.

In the circuit of the ultrasonic atomizer having the above configuration, a single-phase AC voltage as shown in FIG. It is converted to the full-wave rectified voltage shown in b.

This voltage appears at the output terminal 15 of the circuit and is applied to the bias resistor 1
6.17 and becomes the bias voltage of the oscillation circuit 18.

Now, in the above state, turn on the operation switch 24,
If the time is around the time tz shown in FIG. 3b (when the voltage waveform phase angle is an integer multiple of 0° or 180°), only a small voltage appears at the output terminal 15 of the circuit.

Therefore, the oscillation output of the transducer 2 in FIG. 2 is small at first, and therefore the ultrasonic wave 4 emitted from the transducer 2 in FIG.
The energy of the reflected ultrasonic wave 5 reflected by the horizontal surface 6 becomes small, and no inrush current is generated in the vibrator 2.

However, the time during which the operation switch 17 was turned on is
(when the phase angle of the voltage waveform is 90° or 90°)
(odd multiple of '), in Figure 1,
Because ultrasonic waves 4 with high energy are emitted first,
The reflected ultrasonic wave 5 with strong energy hits the vibrator 2 and generates a large rush current.

As shown in FIG. 1b, once the atomization operation starts and a water column 7 is formed on the water surface 6, the ultrasonic wave 4 is subjected to effects such as diffuse reflection on the liquid surface 6, causing an inrush current to the transducer 2. will not occur.

The present invention was developed taking the above points into consideration, and includes a full-wave rectifier circuit that performs full-wave rectification of single-phase alternating current, and a phase angle that changes when the output voltage of the full-wave rectifier circuit is input and the operation switch is turned on. a full-wave rectified voltage control circuit that outputs a full-wave rectified voltage starting at an integral multiple of 0° or 180°; and an oscillation circuit that vibrates a piezoelectric vibrator using the output voltage of the full-wave rectified voltage control circuit as a bias voltage. The present invention provides an ultrasonic atomization device comprising:

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 4 is a circuit diagram of an ultrasonic atomizer according to an embodiment of the present invention.

In the figure, the part surrounded by a broken line 27 is the main part in one embodiment of the present invention, and shows a full-wave rectification voltage control circuit 27.

Also, since the parts outside the broken line 27 are the same as those in FIG. 2 showing the conventional example, the parts outside the broken line 27 in FIG. 4 are given the same numbers as in FIG. 2.

Further, FIGS. 5a to 5f show voltage waveforms at various locations in FIG. 4 during operation of the ultrasonic atomizer.

First, in FIG. 4, diodes 10, 11, 12 .
The connection point between bias resistors 28 and 29 connected to the output terminal 15 of the full-wave rectifier circuit constructed by 13 is connected to the base of a transistor 30.

Further, a diode 31, a resistor 32, and an operation switch 33 are connected in series between the collector of this transistor 30 and the full-wave rectifier output terminal 15, and the collector of the transistor 30 is connected to the gate of a thyristor 34 via a resistor 35. has been done.

The anode of this thyristor 34 is connected to the base of a transistor 36, and the collector and emitter of the transistor 36 are connected to both ends of the bias resistor 17 of the oscillation circuit 18.

Further, the cathode of the diode 31 is grounded via a capacitor 37 and connected to the thyristor 3 via a resistor 38.
4 anode.

39 is a resistor connected between the gate of the thyristor 34 and the ground.

5a is a single-phase AC voltage waveform supplied to terminal 9 from an AC power source, b is a voltage waveform at output terminal 15 of the full-wave rectifier circuit, C is an input voltage waveform to the base of transistor 30,
d is the voltage waveform at the collector of the transistor 30, e is the voltage waveform at the anode of the thyristor 34, and f is the voltage waveform at the bias point 40 of the oscillation circuit 18.

Next, to explain the operation, the terminal 9 in FIG.
An AC input voltage shown in FIG. 5A is applied, and a full-wave rectified output voltage shown in FIG.

The voltage waveform applied to the base of the transistor 30 is the fifth
This is diagram C.

Now, if the operating switch 33 is turned on at time t1 in FIG. 5, the base voltage of the transistor 30 is at a high level as shown in FIG. is t
At 1 o'clock it is zero as shown in Figure 5d.

Therefore, the gate voltage of the thyristor 34 is zero and the thyristor 34 is off, and the anode voltage of the thyristor 34 is at a high level as shown in FIG. 5e, and the transistor 36 is turned on.

Therefore, the bias voltage at the input terminal 40 of the oscillation circuit is zero at time t1, as shown in FIG. 5f, and the operation of the oscillation circuit remains stopped.

At time t2 shown in FIG. 5C when the base voltage of the transistor 30 has decreased, the collector voltage of the transistor 30 becomes high as shown in FIG. 5D, and the high-level collector voltage of the transistor 30 is applied to the gate of the thyristor 34. , the thyristor 34 is turned on.

Then, the anode voltage of the thyristor 34 becomes zero as shown in FIG. 5e, and the transistor 36 is turned off.

Then, the bias voltage of the oscillation circuit becomes a normal value as shown in FIG. 5f, and the oscillation circuit starts a predetermined operation.

Once the thyristor 34 is turned on at time t2, it always remains on, and the oscillation circuit maintains normal operation.

In this way, in the ultrasonic atomizer according to one embodiment of the present invention, when the oscillation circuit is operated, the bias voltage of the oscillation circuit starts from almost zero volts, so the rush current due to the reflection of ultrasonic waves is generated at the moment the operation switch is turned on. It is unlikely that this will occur and the deterioration of the vibrator will be accelerated.

In this embodiment, the bias voltage of the oscillation circuit starts from approximately zero volts by using the circuit shown in the broken line portion 27 in FIG. 4, but this is not limited to the circuit of this embodiment. Any rotation may be used as long as the operation is started when the phase angle of the full-wave rectified bias voltage waveform of the oscillation circuit is O° or an integral multiple of 180° when the oscillation circuit is turned on.

As explained above, the present invention is useful from the point of view of circuit protection of an ultrasonic atomization device.

[Brief explanation of drawings]

Figure 1 a, l) is a sectional view of the ultrasonic atomizer during operation, Figure 2 is a circuit diagram of a conventional ultrasonic atomizer, and Figure 3 a
, b are voltage waveform diagrams at various points in the circuit of Fig. 2, and Fig. 4
The figure is a circuit diagram of the ultrasonic atomization circuit in the present invention, Figure 5a
-f is a diagram of voltage waveforms at various points in the circuit of FIG. 27...Transistor, 33...Operation switch, 34...Thyristor, 36...
...Transistor.

Claims (1)

[Scope of utility model registration request] A full-wave rectifier circuit that performs full-wave rectification of single-phase alternating current, and a full-wave rectified voltage that starts when the phase angle is an integral multiple of 0° or 180° when the operation switch is turned on using the output voltage of the full-wave rectifying circuit as input. An ultrasonic atomizer comprising: a full-wave rectified voltage control circuit that outputs a voltage; and an oscillation circuit that uses the output voltage of the full-wave rectified voltage control circuit as a bias voltage to vibrate a piezoelectric vibrator.