JPH0450938Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a piezoelectric vibrator excitation circuit of an ultrasonic liquid atomizer, particularly a variable resistor drawn out from an automatic oscillation circuit whose surroundings are electromagnetically shielded. This invention relates to an improvement of a piezoelectric vibrator excitation circuit that adjusts the oscillation output using a piezoelectric vibrator.

[Prior Art] Ultrasonic liquid atomization devices using piezoelectric vibrators have been well known and are widely used in ultrasonic humidifiers and various other industrial fields.

Usually, such an ultrasonic liquid atomization device has a built-in piezoelectric vibrator excitation circuit that has an automatic oscillation circuit that drives a piezoelectric vibrator and a variable resistor that adjusts the oscillation output of this automatic oscillation circuit. The atomization output is controlled by adjusting the resistance value of the resistor.

However, since such devices require power ranging from several watts to several tens of watts to obtain atomizing output, noise radiation from the automatic oscillation circuit to the outside poses a major problem.

Therefore, such conventional automatic oscillator circuits were usually housed within an electromagnetic shielding enclosure to control the noise radiation.

[Problems to be solved by the invention] However, in such an ultrasonic liquid atomization device.
For convenient operation by the user, a variable resistor for adjusting the atomization output is attached to the main body case of the device. For this reason, the lead wire connecting the variable resistor and the automatic oscillation circuit tends to be long.

Therefore, even if only the automatic oscillation circuit is electromagnetically shielded, there is a problem in that high frequency current flows into the lead wire, and noise radio waves are radiated from the lead wire to the outside.

In addition, as a technology related to this invention,
12619 is known.

This technology is characterized in that a filter circuit is inserted into the base bias circuit of an oscillation transistor provided in an automatic oscillation circuit, and the variable resistor is connected to the base of the oscillation transistor via the filter circuit. It is something.

In this way, the high frequency current flowing from the automatic oscillator circuit to the variable resistor is controlled by the filter circuit, so it is possible to reduce the radiation of noise radio waves from the variable resistor lead wire, and the lead wire can be made a certain length. can do.

However, this conventional technique uses a filter, and does not use a photocoupler like the present invention, and the basic configurations of the two are clearly different.

[Purpose of the invention] The present invention has been made in view of such conventional problems, and its purpose is to control the leakage of high frequency current from an electromagnetically shielded automatic oscillation circuit to a variable resistor, and to To provide a piezoelectric vibrator excitation circuit for an ultrasonic liquid atomizer, which prevents radiation of noise radio waves from a lead wire for a variable resistor and allows smooth adjustment of excitation output using the variable resistor.

[Means for Solving the Problems] To achieve the above object, the present invention provides an automatic oscillation circuit that drives a piezoelectric vibrator for generating ultrasonic waves of an ultrasonic liquid atomization device and whose periphery is electromagnetically shielded. and a variable resistor that adjusts the oscillation output drawn externally from this automatic oscillation circuit, the light emitting side is connected to the variable resistor, the light receiving side is connected to the automatic oscillation circuit, and the variable resistor and automatic oscillation circuit are connected optically. It is characterized in that it includes a photo coupler that is connected to the photocoupler.

[Function] As described above, according to the present invention, by electrically isolating between the variable resistor and the automatic oscillation circuit using a photo coupler, leakage of high frequency current from the automatic oscillation circuit is suppressed, and the variable resistor and automatic oscillation circuit are electrically separated. It is possible to prevent the radiation of noise radio waves from the dexterous lead wire.

[Example] Next, a preferred example of the present invention will be described based on the drawings.

FIG. 1 shows a preferred embodiment of the piezoelectric vibrator excitation circuit according to the present invention. It includes an oscillation circuit 12 and a variable resistor 14 that adjusts the oscillation output extracted from the automatic oscillation circuit 12 to the outside.

The automatic oscillation circuit 12 of this embodiment is formed as a collector-grounded Colpitts automatic oscillation circuit, and is housed in an electromagnetic shielding case so as not to radiate radio noise to the outside.

Here, the collector grounded type Coltspit automatic oscillation circuit 10 has power input terminals 16a and 16b.
The AC power input from the oscillator 22 is converted into DC power using the rectifier circuit 18, smoothed through the capacitor 20, and then supplied to the oscillation section 22.

This oscillation section 22 connects the collector and emitter of the oscillation transistor 24 to the positive and negative sides of the rectifier circuit 18, respectively, and connects coils 26 and 28 in series between the emitter and the negative side of the rectifier circuit 18. It is inserted.

Further, a piezoelectric vibrator 10 of an ultrasonic liquid atomization device is connected between the collector and base of the transistor 24.

Furthermore, a capacitor 30 is connected between the connection point P of the coils 26 and 28 and the base of the transistor 24.
However, a capacitor 32 is connected between the connection point P and the collector of the transistor 24, respectively.

Here, the coil 32 and capacitor 32 function as a parallel resonant circuit.

The characteristic feature of the present invention is that the collector grounded type Colpitts automatic oscillation circuit 12 formed in this way is
and the variable resistor 14 are connected via a photocoupler 40 to prevent leakage of high frequency current from the automatic oscillation circuit 12 to the variable resistor 14.

Here, the photo coupler 40 has its light emitting element 42 connected to the variable resistor 14 side,
The light receiving element 44 is connected to the automatic oscillation circuit 12 side.

In this embodiment, the light emitting element 42 is formed using a lamp, and one end of the light emitting element 42 is connected to the connecting terminal 3.
4a, and the other end is connected to the positive side of the rectifier circuit 18.

Further, in this embodiment, the light receiving element 44 is
One end thereof is connected to the positive side of the rectifier circuit 18, and the other end is connected to the collector of the transistor 24 via a resistor 36.

The variable resistor 14 of the embodiment is attached and fixed to the main body case of the ultrasonic liquid atomizer for easy operation by the user, and the lead wires 50a, 50b are connected to the connection terminals 34a, 34b of the automatic oscillation circuit 12.
connected via.

Therefore, when the user adjusts the variable resistor 14, the amount of light from the light emitting element 42 changes according to the resistance value, the resistance value of the light receiving element 44 is determined, and the base bias current of the transistor 24 is set to an arbitrary value. can be controlled.

By the way, as is well known, the oscillation output of the common collector type Colpitts automatic oscillation circuit 10 is generated by the transistor 2.
It is controlled to a value according to the base bias current of No. 4.

Therefore, according to the present invention, by adjusting the resistance value of the light receiving element 44 using the variable resistor 14, the oscillation output of the automatic oscillation circuit 12, that is, the atomization output of the piezoelectric vibrator 10 for generating ultrasonic waves can be adjusted to a desired value. can be controlled to the value of

Next, the operation of the present invention as described above will be explained.

Since the Colpitts automatic oscillation circuit 10 of this embodiment is of a collector-grounded type, the high-frequency potential on the collector side is zero.

Further, in the circuit of this embodiment, the positive side of the automatic oscillation circuit 12 and the side of the variable resistor 14 are electrically separated using the photocoupler 40.

Therefore, when driving the ultrasonic liquid atomizer,
Even if a high frequency current flows within the automatic oscillation circuit 12, the photocoupler 40 reliably prevents this high frequency current from leaking to the variable resistor 14 side.

In this way, according to the present invention, of the current flowing from the automatic oscillation circuit 12 toward the variable resistor 14, only the high-frequency current is cut off by the photocoupler 40, so that the lead wire 50a for the variable resistor 14 is , 50b are long to some extent, the radiation of noise radio waves from the lead wires 50a, 50b can be effectively controlled.

In the above embodiments, a lamp and a Cds were used as the light emitting element 42 and the light receiving element 44, but the present invention is not limited thereto, and for example, an LED and a Cds can also be used.

[Effects of the invention] As explained above, according to the invention, leakage of high-frequency current from the automatic oscillation circuit side can be prevented by electrically separating the variable resistor and the automatic oscillation circuit using a photo coupler. It is possible to prevent noise radio waves from being radiated from the variable resistor lead wire to the outside.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing a preferred embodiment of the piezoelectric vibrator excitation circuit of the ultrasonic liquid atomization device according to the present invention. 10... vibrator, 12... automatic oscillation circuit, 14
...Variable resistor, 24...Transistor, 40...
...photo cutter, 42... light emitting element, 44...
Light receiving element.

Claims (1)

[Claims for Utility Model Registration] 1. An automatic oscillation circuit that drives a piezoelectric vibrator for generating ultrasonic waves of an ultrasonic liquid atomization device and whose periphery is electromagnetically shielded; The variable resistor includes a variable resistor that adjusts the oscillation output, and a photocoupler whose light emitting side is connected to the variable resistor and whose light receiving side is connected to the automatic oscillation circuit, and which optically connects the variable resistor and the automatic oscillation circuit. 1. A piezoelectric vibrator excitation circuit for an ultrasonic liquid atomizer, characterized in that the piezoelectric vibrator excitation circuit is formed so as to prevent noise radiation due to high-frequency current by electrically separating the circuit and the automatic oscillation circuit. 2. The automatic oscillation circuit is formed using a common collector type Colpittz automatic oscillation circuit, and the photocoupler has a light receiving element connected to the base bias circuit of a transistor of the collector common type Colpittz automatic oscillation circuit. A piezoelectric vibrator excitation circuit of the ultrasonic liquid atomization device according to item 1.