JPH084356B2 - Ultrasonic vibration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an ultrasonic vibration device for converting an alternating-current electrical signal into ultrasonic vibration with extremely high efficiency.

[Prior Art] Conventionally, in an ultrasonic vibration device, a resonator is pressed against an electromechanical conversion element such as a piezoelectric element, an electrostrictive element, or a magnetostrictive element, and a large amplitude ultrasonic vibration is obtained by utilizing the resonance action. There is. Therefore, the ultrasonic vibrating device has two resonances, that is, an electric resonance system including an electric signal generating unit that gives an AC electric signal and an electromechanical conversion element, and a mechanical resonance system including an electromechanical conversion element and a resonator. It is understood as a collection of systems. It is clear that the ultrasonic vibration can be obtained most efficiently when the two resonance systems have the same resonance frequency. However, due to the temperature characteristics and the aging characteristics of the constituent parts of the ultrasonic vibration device, the resonance of each resonance system can be achieved. The frequency may shift. Therefore, conventionally, in order to generate ultrasonic vibration with high efficiency,
For example, the frequency of the AC electric signal supplied to the electromechanical conversion element is feedback-controlled so that the output vibration amplitude becomes maximum.

[Problems to be Solved by the Invention] However, even the ultrasonic vibrating device as described above is not yet sufficient, and has the following problems.

As described above, there are essentially two resonance systems in the ultrasonic vibration device. However, the conventional ultrasonic vibration device controls only the frequency of the alternating electric signal which is a single parameter. Therefore, even if the output amplitude is maximized within the above control range, the electrical resonance system and the mechanical resonance system individually deviate greatly from the resonance state, and it is no longer possible to obtain the maximum efficiency before.

The present invention has been made to solve the above-mentioned problems, and controls the electric resonance system and the mechanical resonance system of an ultrasonic vibration device to be in independent resonance states, and always obtains ultrasonic vibration with maximum efficiency. It is an object of the present invention to provide an excellent ultrasonic vibration device that can be used.

Configuration of the Invention [Means for Solving the Problems] An ultrasonic vibration device of the present invention for solving the above problems is an alternating current generated by an electric signal generating means C1 as shown in the basic configuration diagram of FIG. In the ultrasonic vibrating device in which the resonator C3 is pressed against the electromechanical conversion element C2 that excites vibration by applying an electric signal, and a large amplitude vibration is obtained by utilizing the resonance action, the electromechanical conversion element C2 And a monitoring means C4 for monitoring a mechanical vibration state including the resonator C3, and a control means for controlling the frequency of the AC electric signal so as to be in a mechanical resonance state according to the result of monitoring by the monitoring means C4. C5 and the electromechanical conversion element C2
And a matching circuit C6 connected between the electric signal generating means C1 and matching the electric resonance frequency including the electromechanical conversion element C2 with the frequency of the controlled alternating electric signal. And

[Operation] In the ultrasonic vibration device of the present invention, the control means C5 matches the AC frequency of the electric signal generation means C1 with the mechanical resonance state based on the monitoring result of the monitoring means C4, and further, the matching circuit C6.
By the action of the electromechanical conversion element at the above mechanical resonance frequency
The electrical resonance system centering on C2 resonates.

[Examples] Hereinafter, examples will be described to more specifically describe the present invention.

FIG. 2 is a schematic configuration block diagram showing the configuration of the ultrasonic vibration device of the embodiment. The ultrasonic vibrator 1 has a cylindrical structure in which elastic resonators 1B are pressure-bonded to the upper and lower surfaces of a disk-shaped piezoelectric element 1A, which is a type of electromechanical transducer. When an electric signal is applied between the upper and lower surfaces of this piezoelectric element 1A, an expansion and contraction action in the thickness direction proportional to the signal appears, which is the resonator 1B.
When it resonates with, a large amplitude ultrasonic vibration is obtained. Furthermore,
The ultrasonic transducer 1 is provided with an annular detection piezoelectric element 1C, and the piezoelectric element 1A is loosely fitted around the center hole of the piezoelectric element 1C and mechanically generated by the ultrasonic transducer 1. It outputs an electric signal proportional to the vibration.

The frequency of the AC signal applied to the piezoelectric element 1A is determined by an oscillator (voltage control variable frequency oscillator) 3 whose output frequency can be adjusted according to the value of the voltage applied to the input terminal. The AC signal is amplified by the amplifier 5, and then supplied to the piezoelectric element 1A via the constant resistor 7 and the matching circuit 9. Here, the matching circuit 9 is composed of a variable reactance circuit, and based on a control signal from the reactance control circuit 11, the reactance can be changed / adjusted to an arbitrary value of customer quantity or inductiveness.

The control signal output from the reactance control circuit 11 is
It is determined based on the phase difference between the voltage and the current of the output electric signal of the amplifier 5. That is, both detection results of the differential amplifier 13 for detecting the current waveform from the potential difference across the constant resistor 7 and the differential amplifier 15 for detecting the voltage waveform from the potential at one end of the constant resistor 7 are phased. Phase comparator to compare 17
The output is used as an input signal, and the control signal is output to the matching circuit 9 so that the input signal becomes zero. As is well known, the electrical resonance state is a condition under which the current flowing in the circuit and the voltage source voltage are in phase, in other words, the condition that the reactance component of the combined impedance of the network becomes zero. Therefore, the reactance control circuit 11 outputs a control signal to the matching circuit 9 so as to have a predetermined reactance value that cancels the reactance amount of the electrical equivalent circuit centered on the piezoelectric element 1A of the ultrasonic transducer 1 and outputs the matching circuit. By the action of 9, the electrical resonance state of the ultrasonic transducer 1 is always determined by the oscillation frequency of the oscillator 3.

On the other hand, the oscillation frequency of the oscillator 3 is feedback-controlled by the following electric circuit so as to match the mechanical resonance frequency of the ultrasonic transducer 1. The mechanical resonance state is when the force input to the mechanical system and the velocity, which is the differential amount of the displacement generated in the mechanical system by the force, have the same phase. Therefore, the output of the detection piezoelectric element 1C proportional to the applied voltage applied to the piezoelectric element 1A corresponding to the force input to the mechanical system of the ultrasonic transducer 1 and the mechanical moving speed of the ultrasonic transducer 1 The voltage and the voltage are amplified using the differential amplifiers 21 and 23, respectively, and the output is amplified by the phase comparison circuit 2
Use 5 to compare the phases. Therefore, this phase comparison circuit 25
The output signal of has the property of increasing in proportion to the deviation from the mechanical resonance state, and the frequency control circuit 27 using this signal as an input generates the mechanical resonance state in which the input value becomes zero. A control voltage for changing the oscillation frequency of the oscillator 3 is output to the oscillator 3. That is, even if a mechanical resonance system is formed, a unique feedback control circuit is configured by the above-mentioned electric circuits, and even if each component of the ultrasonic vibration element 1 changes due to temperature change, aging change, or the like. The ultrasonic transducer 1 is always driven at the oscillation frequency that satisfies the mechanical resonance state.

According to the ultrasonic vibration device of this embodiment configured as described above, the two resonance systems, the electrical resonance system and the mechanical resonance system, which are essentially present in the ultrasonic vibration device, are independently feedback controlled. And always operates in resonance. Therefore, the energy conversion of the electric machine is always achieved with the maximum efficiency of the ultrasonic vibration device, and strong ultrasonic vibration can be obtained with low power consumption. In other words, since there is no unnecessary energy loss, it can be said that this is an extremely excellent ultrasonic vibrating device that simultaneously solves the downsizing of the ultrasonic vibrating device and thermal problems.

Although the piezoelectric element is used as the electromechanical conversion element in the above-described embodiment, an electrostrictive element or a magnetostrictive element may be used instead of the piezoelectric element, and the electromechanical transducer may be realized in various modes without departing from the scope of the present invention. Good.

EFFECTS OF THE INVENTION As described in detail with reference to the examples above, according to the ultrasonic vibration device of the present invention, both the electric resonance system and the mechanical resonance system are independently feedback-controlled, and they are always resonant. It is possible to operate under the conditions. Therefore, the ultrasonic vibrating device always operates at the highest efficiency, and various problems such as downsizing of the device and reduction of heat generation can be solved simultaneously.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention, and FIG. 2 is a schematic configuration block diagram of an ultrasonic vibration device which is an embodiment thereof. C1 ... electrical signal generating means C2 ... electromechanical converting means C3 ... resonator, C4 ... monitoring means C5 ... controlling means, 1 ... ultrasonic transducer 3 ... oscillator, 9 ... matching circuit

Claims (1)

[Claims] Claim: What is claimed is: 1. A resonator is pressed against an electromechanical conversion element that excites vibration when an AC electric signal generated by an electric signal generating means is applied, and the resonance action is utilized to obtain vibration of large amplitude. In a sound wave vibrating device, a monitor means for monitoring a mechanical vibration state including the electromechanical conversion element and the resonator, and the alternating electrical signal so as to be in a mechanical resonance state according to a result of monitoring by the monitoring means. And a control means for controlling the frequency of the electromechanical conversion element, which is connected between the electromechanical conversion element and the electric signal generating means, and has an electric resonance frequency including the electromechanical conversion element that matches the frequency of the controlled AC electric signal. An ultrasonic vibrating device comprising: a matching circuit and a matching circuit.