JPH0698340B2 - Power supply for oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a vibrator power supply for vibrating a ceramic vibrator of an ultrasonic motor, for example.

(Prior Art) As a conventional power source for a vibrator of this type, for example, the configuration shown in FIG. 5 is adopted.

In the oscillator power supply shown in FIG. 5, the positive electrode of the DC power supply 1 is connected to the center of the primary winding 3 of the transformer 2, and one winding portion 4 of the primary winding 3 is connected to the first transistor. 5 is connected to the negative electrode of the DC power supply 1 via the collector-emitter of 5, and the other winding portion 6 of the primary winding 3 is connected to the negative electrode of the DC power supply 1 via the collector-emitter of the second transistor 7. ing.

The DC power supply 1 is connected to a generating circuit 8 whose oscillation frequency fi is determined in advance, and the output terminals of the oscillation circuit 8 are connected to the bases of the first transistor 5 and the second transistor 7, respectively. .

A ceramic oscillator 10 is connected to the secondary winding 9 of the transformer 2.

Then, a voltage is applied from the DC power supply 1 to the oscillation circuit 8, and the oscillation circuit 8 alternately supplies a current to the base of the first transistor 5 and the base of the second transistor 7. Due to the alternately supplied currents, currents alternately flow through the one winding portion 4 and the other winding portion 6, and an AC output is performed. At this time, the oscillation frequency fo peculiar to the ceramic oscillator 10, the inductance L of the inverter circuit, the ceramic oscillator 10
Resonance frequency with the capacitance C of , The gap or the number of turns of the transformer 2 is set in advance, the oscillation frequency fi of the oscillation circuit 8 is also combined with the oscillation frequency fo and the electrical resonance frequency fE, and the inverter circuit is set in the state of fo = fE = fi. To operate. And the secondary winding 9
The ceramic vibrator 10 is vibrated by the current induced in the.
That is, the ceramic oscillator 10 is oscillated by the separately excited inverter circuit.

(Problems to be Solved by the Invention) However, the oscillation frequency fi of the inverter circuit is adjusted to the electrical resonance frequency fE and the oscillation frequency fo shown in FIG. 3 by adjusting the gap or the number of turns of the transformer 2 at a certain temperature. In accordance with the above, as shown in FIG. 4, the capacitance C of the ceramic vibrator 10 largely changes depending on the temperature and the amount of vibration changes, so that the oscillation frequency fi of the inverter circuit and the electrical resonance frequency fE of the circuit are changed. It quickly collapses due to temperature and becomes a capacitive or inductive load, increasing the heat generation of the first and second transistors 5 and 7 as switching elements,
It has the problem of being destroyed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a power supply for a vibrator that constantly matches the electrical resonance frequency of the circuit with the oscillation frequency of the inverter circuit and does not heat or destroy the switching element. The purpose is to

[Structure of Invention]

(Means for Solving Problems) The present invention converts a direct current of a direct current power supply into an alternating current by a self-excited inverter circuit that changes an oscillation frequency of a switching element based on an output, and a ceramic connected to the inverter circuit. In a power supply for a vibrator that vibrates the vibrator, the vibration amount of the inductance element and the ceramic vibrator, which is provided in the inverter circuit and whose inductance is variable, is detected as a voltage value, and the voltage value of the detected vibration amount is detected. Is compared with a reference voltage value and outputs based on the difference between these voltage values, and power is supplied to the inductance element based on the output from the comparison circuit to change the inductance of the inductance element to perform the switching. And a variable DC power supply for changing the oscillation frequency of the element.

(Operation) The present invention converts the direct current of a direct current power supply into an alternating current in an inverter circuit to oscillate the ceramic vibrator at a constant frequency, detects the vibration amount of the ceramic vibrator as a voltage value, and detects the voltage value of this vibration amount. The reference voltage value is compared with the comparison circuit to output based on the difference between the reference value, and the DC variable power supply changes the inductance of the inductance element based on this output to correct the inductance of the inductance element and oscillate the inverter circuit. Since the frequency is adjusted to the oscillation frequency of the ceramic oscillator and the electrical resonance frequency is always adjusted to the oscillation frequency of the ceramic oscillator, the load on the switching element of the inverter circuit can be reduced.

(Embodiment) An embodiment of the vibrator power supply of the present invention will be described below with reference to FIG.

In FIG. 1, 11 is a driving DC power supply, and a self-excited inverter circuit 12 is connected to this DC power supply 11.

In the inverter circuit 12, the positive electrode of the DC power supply 11 is connected to the center of the primary winding 14 of the transformer 13 as an inductance element, and one winding portion 15 of the primary winding 14 serves as a first switching element. Collector of transistor 16
It is connected to the negative electrode of the DC power supply 11 via the emitter, and from the other winding part 17 of the primary winding 14 of the transformer 13 to the collector of the second transistor 18 as a switching element.
It is connected to the negative electrode of the DC power supply 11 via the emitter.

In addition, starting resistors 19 and 20 for starting the inverter circuit 12 are connected from the positive electrode of the DC power supply 11 to the bases of the first transistor 16 and the second transistor 18, respectively. Further, the first and second transistors 1
6, 18 are electric resonance frequencies set by the inductance L of the secondary winding 21 of the transformer 13 and the capacitance C of the ceramic vibrator 22. Winding for switching element of transformer 13 to operate at
One end of 23 is connected to the base of the first transistor 16 and the other end is connected to the base of the second transistor 18.

The ceramic vibrator 22 is connected to the secondary winding 21 of the transformer 13 of the inverter circuit 12. At this time,
Inductance L of secondary winding 21 and ceramic oscillator
The gap of the transformer 13 or the number of turns of the secondary winding 21 is adjusted so that the electrical resonance frequency fE defined by the capacitance C of 22 becomes equal to the intrinsic oscillation frequency fo of the ceramic vibrator 22.

Further, the ceramic oscillator 22 is connected with a comparison circuit 25 that captures the vibration amount of the ceramic oscillator 22 as a voltage, has a reference voltage, and compares it with the voltage that captures the vibration amount of the ceramic oscillator 22. The comparison circuit 25 includes a correction DC power supply 26 whose voltage is changed by the output of the comparison circuit 25.
Are connected.

The correction DC power supply 26 is used for the correction winding 2 of the transformer 13.
7. The correction winding 27 is connected in series with an inductor 28 that removes the AC component, and these forms a correction circuit 29.

Next, the operation of the above embodiment will be described.

First, when a voltage is applied to the inverter circuit 12 from the DC power supply 11, the first resistor 19 or the first resistor 20 is used to drive the first voltage.
Base of transistor 16 or second transistor 18 of
A base current is made to flow to the base of, and one of the transistors 16 and 18 is turned on. For example, if the first transistor 16 is first turned on, a current flows from the DC power supply 11 through the path of the first transistor 16 of the one winding portion 15.

Then, when the first transistor 16 is turned on, a voltage is induced in the secondary winding 21, and a voltage is induced at the electrical resonance frequency fE determined by the inductance L of the secondary winding 21 and the capacitance C of the ceramic vibrator 22. The secondary side circuit of the device 13 is oscillated.

When the direction of the current of the secondary side circuit is reversed, a current flows through the switching element winding 23 in the direction of the base of the second transistor 18, and the second transistor 18 turns on and the first transistor 18 turns on. Transistor 16 turns off. Therefore, the current flowing in the path of the DC power supply 11, one winding section 15, and the first transistor 16 flows in the path of the DC power supply 11, the other winding section 17, and the second transistor 18.

Therefore, the directions of the voltages induced in the secondary winding 21 are opposite, and the first transistor 16 and the second transistor 18 are repeatedly turned on and off at the electrical resonance frequency fE. That is, the electrical resonance frequency determined by the inductance L of the secondary winding 21 and the capacitance C of the ceramic vibrator 22. Then, a current is caused to flow alternately from the switching element winding 23 to the base of the first transistor 16 and the base of the second transistor 18 to alternately turn on the first transistor 16 and the second transistor 18, and AC is induced in the secondary winding 21 of 12 and the inductance L of the secondary winding 21 of the transformer 13 and the capacitance C of the ceramic vibrator 22 are always
Ceramic resonator 22 with an electrical resonance frequency fE determined by
To oscillate.

Further, when the ceramic oscillator 22 is vibrating at the electrical resonance frequency fE determined by the inductance L of the secondary winding 21 and the capacitance C of the ceramic oscillator 22, the comparison circuit 25 compares the vibration amount as a voltage, for example. The difference between the oscillation frequency fo and the actual frequency is calculated by comparing with the reference voltage in the circuit 25, and the comparison circuit 25 controls the correction DC power supply 26 according to the difference and adjusts the DC current flowing in the correction winding 27. To do.

Then, by changing the magnetic field strength of the correction winding 27, the transformer 13
Even if the capacitance C of the ceramic oscillator 22 changes due to the temperature change by correcting the inductance L of the electrical oscillator, the electrical resonance frequency fE is always the oscillation frequency fo peculiar to the ceramic oscillator 22 or the vibration amount necessary for practical use. So that

Next, another embodiment of the vibrator power source will be described with reference to FIG.

The embodiment shown in FIG. 2 comprises an inverter circuit 31 using one switching element. This inverter circuit 31 has a starting resistor 32 at the positive electrode of the DC power supply 11 and the base of a transistor 33 as a switching element. Then
Furthermore, the positive electrode of the DC power supply 11 is connected to the primary winding 35 of the transformer 34 via the collector / emitter of the transistor 33, and is connected to the negative electrode of the DC power supply 11. The emitter of the transistor 33 is connected to the base of the transistor 33 from the switching element winding 36 through the capacitor 37.

Furthermore, a capacitor 40 for resonance frequency adjustment is connected in parallel with the ceramic vibrator 22.

The operation of the above embodiment will be described.

First, when power is supplied from the DC power supply 11 to the inverter circuit 31, a base current is given to the base of the transistor 33 via the starting resistor 32, and a current flows through the path of the transistor 33, the primary winding 35, and the DC power supply 11. At this time, the secondary winding 21
The circuit on the secondary side of the transformer 34 resonates at the electrical resonance frequency fE due to the inductance L of the capacitor and the capacitance C of the ceramic vibrator 22 and the capacitor 40. And the secondary winding 21
When the direction of the current flowing in the switch is reversed, the voltage of the switching element winding 36 is reverse biased with respect to the transistor 33, turning off the transistor 33. In this way, the transistor 33 is turned on and off according to the electrical resonance frequency fE on the secondary side of the transformer 34 to be converted into an AC voltage, and the ceramic vibrator 22 is oscillated by this AC voltage.

Also, for example, the inductance L of the secondary winding 21 at room temperature
If the capacitor C cannot resonate with the capacitance C of the ceramic vibrator 22, a capacitor having an appropriate capacitance C
If 40 is used, the electrical resonance frequency fE and the ceramic resonator 22
The oscillation frequency fo of is the same.

Then, the capacitance C of the ceramic vibrator 22 changes due to, for example, a temperature change, and the electrical resonance frequency is changed.
If fE is different from the oscillation frequency fo, the correction winding 27 is excited by the correction DC power supply 26 and the inductance L of the secondary winding 21 is changed to change the electrical resonance frequency fE and the oscillation frequency fo. And match.

In the embodiment shown in FIG. 1, a multivibrator type inverter circuit 12 using two switching elements,
In the embodiment shown in FIG. 2, a blocking type inverter circuit 31 using one switching element is used.
Either type of inverter circuit can be used.

〔The invention's effect〕

According to the vibrator power supply of the present invention, the amount of vibration of the ceramic vibrator is detected as a voltage value and compared by the comparison circuit, and an output based on the difference from the reference voltage value is performed. Since the inductance of the inductance element is changed with, the inductance of the inductance element is corrected, the oscillation frequency of the inverter circuit is matched with the oscillation frequency of the ceramic oscillator, and the electrical resonance frequency is always matched with the oscillation frequency of the ceramic oscillator. Even if the capacitance of the ceramic vibrator changes with temperature, the ceramic vibrator can always have a required vibration amount, heat generation of the switching element can be suppressed, and destruction of the switching element can be prevented.

[Brief description of drawings]

1 is a circuit diagram showing an embodiment of a vibrator power supply of the present invention, FIG. 2 is a circuit diagram showing a vibrator power supply of another embodiment of the same as above, and FIG. 3 is a frequency and vibration of a ceramic vibrator. FIG. 4 is a relational diagram of temperature and capacitance of the ceramic oscillator, and FIG. 5 is a circuit diagram of a conventional oscillator power supply. 11 …… DC power supply, 12 …… Inverter circuit, 13 …… Transformer as inductance element, 16,18,33 …… Transistor as switching element, 22 …… Ceramic vibrator, 25 …… Comparison circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-65418 (JP, A) Actual opening 57-39685 (JP, U) Actual opening 63-4191 (JP, U)

Claims (1)

[Claims] 1. A vibrator power supply for converting a direct current of a direct current power supply into an alternating current by a self-excited inverter circuit that changes an oscillation frequency of a switching element based on an output and vibrating a ceramic vibrator connected to the inverter circuit. In, an inductance element provided in the inverter circuit, the inductance of which is variable, and a vibration amount of the ceramic vibrator is detected as a voltage value,
A comparison circuit that compares the voltage value of the detected vibration amount with a reference voltage value and outputs based on the difference between these voltage values, and power is supplied to the inductance element based on the output from this comparison circuit to And a variable DC power supply for changing the oscillation frequency of the switching element by changing the inductance of the element.