JPS62135280A - Drive power supply for ultrasonic motor - Google Patents

Abstract

PURPOSE:To decrease the number of parts, and to improve reliability while reducing cost by feeding input AC voltage having two or more of different phase driving a piezoelectric body from a single-phase high-frequency power supply. CONSTITUTION:Sine waves outputted from an oscillator 10 are amplified by an amplifier 12, and transmitted to an electrode A group intact while being sent to an electrode B group through an inductance 17. An inductance 18 is connected between a ground E and the electrode B group at that time. The inductances 17 and 18 match an electrostatic capacity section in a motor containing a piezoelectric body with a resistance section in terms of currents entering the electrode B group, and displace phase.

Description

DETAILED DESCRIPTION OF THE INVENTION Although the present applicant has disclosed an ultrasonic motor and a surface wave motor device that utilize bending vibration (a-sonic vibration) of a piezoelectric body, the present invention is not limited to this invention.

The present invention relates to an ultrasonic motor drive power source that drives the ultrasonic motor.

Conventionally, a two-phase high frequency AC power source has been used as a drive power source for an ultrasonic motor, but the present invention shows the following.
i J6 condolence 1tsu L-μm y L,
+ -1-11゛Since the one-phase phase shifter and amplifier at the ton source are no longer required, it becomes lighter and more compact, and the number of parts for heavy crude oil is reduced, improving reliability and reducing its price. becomes cheaper.

741: The operating principle and embodiments of the drive power supply according to the invention will be described in detail with reference to the drawings.

FIG. 1 is a partial sectional view of the ultrasonic motor, and FIG. 2 is a diagram showing the polarization direction of the piezoelectric body and the arrangement of electrodes.

90＠A high J8 wave voltage of two circuits out of phase is applied to each end ia, b of the piezoelectric body 2 in the stator 3, and the piezoelectric body 2 is excited. A bending traveling wave, which is a combination of a transverse wave and a longitudinal wave, is generated on one end surface 1a, and the rotor that is in pressure contact with the one end surface 1a is driven to rotate. The pitch of the piezoelectric body is set as the local wavelength of the bending wave, and the polarization is performed alternately in the thickness direction of the piezoelectric body 2, as shown in FIG. Next, the radio wavelength position of the bending wave is shifted, and polarization is similarly performed alternately in the thickness direction.

The pressure that was polarized is
are grouped into two electrode groups A and B, terminals a and b, respectively.
is connected to.

Next, FIG. 3 shows a conventional ultrasonic motor drive circuit, in which a power supply section 13 includes an oscillator 1O and an amplifier 12. It consists of a phase shifter 11. One circuit amplifies a high frequency voltage, for example, VoSinω, output from one oscillator (Vo: voltage, ω: angular frequency, t: time) with an amplifier 12, and
Then, the other circuit shifts the phase of the output voltage from the oscillator by 906 through the phase shifter 11, and then amplifies the VoCasω by the wave intensifier 12 and applies it to the electrode IfB. Note that E is ground.

Further, the inductance 14 in FIG. 3 is a power factor improving inductance for canceling the reactive current flowing through the piezoelectric material in the stator by LC resonance.

FIG. 4 shows an ultrasonic motor drive circuit showing one embodiment of the present invention.

This figure 4 shows, for example, the VoSin output from the oscillator.
ωtlJQ is amplified by an intensifier (1) 12, one of which is directly input to the electrode group A, and the other is input to the electrode B group via an inductance 17.

At that time, an inductance of 18
Connect.

Here, the inductance 17 and the inductance 18 are used to shift the phase of the current entering group B by matching the capacitance and resistance inside the motor including the piezoelectric body.

16 in FIG. 4 is an inductance for power factor improvement or
It is capacitance.

To explain in more detail, the equivalent circuit of the ultrasonic motor shown in FIG. 4 can generally be regarded as a circuit in which an equal dynamic resistance R and an equivalent capacitance C shown in FIG. 5 are coupled in parallel.

Next, a high frequency alternating current i (j pressure VoSi
Apply nωt. At this time, the current that removes the resistance is 1
2. Assuming that the current flowing through the capacitance is 1G, the current flowing through the inductance 18 is IL and the current flowing through the inductance 17 is io, and the voltage between A-8 is t3, the 'I forward pressure applied to the electrode group A is p-1 = Vo Sin
It is ωt.

Here, the phase of the voltage applied to group B is shifted by 90@
To make = VoCosωt, death l = death 2 + death 3 ■. =ir +i, +iL death3=jωLot.

For each relationship (L+...inductance 18; Lo...inductance 17).

11, 1 2 ltc+1L11 death 31=ff
It can be seen that it is sufficient to find each constant that satisfies the following.

In addition, when the load applied to the ultrasonic motor 15 changes, in order to maintain the phase balance and each voltage between the two phases of the two legs, inductances 7 and 18 are used as uf variable inductances. Furthermore, if the piezoelectric body is thick, the current due to the resistance inside the motor is higher than the current due to the capacitance 1-1, so the inductance 18 can be replaced with a capacitance. Furthermore, it goes without saying that the direction of rotation of the motor can be changed by inserting a changeover switch (not shown) between the motor and the power supply section.

As explained above, the present invention has an increase of 11] compared to the conventional art.
One device and a phase shifter are eliminated, making it cheaper, fewer parts, and more reliable.

This is an extremely useful invention as it provides a light-sewn, compact circuit.

[Brief explanation of drawings]

Figure 1 shows 1. Partial cross-sectional view of TFL wave motor: fS2
The diagrams show the polarization direction of the piezoelectric body of the ultrasonic motor and the arrangement of the upper pole, FIG. 3 is a conventional ultrasonic motor drive circuit, and FIG. 4 is an ultrasonic motor showing an embodiment of the present invention. An explanatory diagram of the river drive circuit and FIG. 5 are explanatory diagrams showing an internal equivalent circuit of the ultrasonic motor. 1... E1 N ring, 1a... End face of elastic ring, 2... Piezoelectric body, 3... Stator, 4...
... Rotor, 5 ... 1 depression, 6 ... Pressure member (spring), 7 ... Bearing, 10 ... Oscillator, 11
. . . Transfer device, 12 . . . Multiplier, 13 . . . capacitance. 17... Inductance (Lo), 18... Inductance (L+). 19...High frequency power supply part, a, b...electrode, E...ground, A, B...electrode group, R...equivalent resistance, 01...storm wavelength,
C...Equivalent capacitance, 02...1 wavelength Figure 1 Figure 2

Claims (1)

[Claims] The piezoelectric body is driven by an ultrasonic motor equipped with an elastic body that generates a bending wave that is a combination of transverse waves and longitudinal waves, a stator made of a piezoelectric body fixed to the elastic body, and a rotor that presses into contact with the stator. A drive power source for an ultrasonic motor, characterized in that input AC voltages of two or more different phases are supplied from a single-phase high-frequency power source.