JPS63125100A - Ultrasonic oscillator - Google Patents

Abstract

PURPOSE:To transform an electric input to an ultrasonic oscillation of a constant oscillation frequency with a high efficiency by disposing a separate electric/mechanic transforming element for changing an application force in application mechanism for applying the electric/mechanic transforming element and a resonator. CONSTITUTION:An ultrasonic oscillator 2 is applied to a driving piezoelectric element 4 and elastic members 6, 8 according to the fastening force of a bolt 10 passing on the central axis of the driving piezoelectric element 4 and a nut 12 screwed thereto and a driving plate 14 abuts against the elastic member 6 through an insulating plate 16. On the other surface of the driving piezoelectric element 4, a controlling piezoelectric element 20 on which a controlling electrode plate 18 is tightly closely mounted is interposed between the elastic member 8 and the plate 18. The bot fastening force can be arbitrarily changed according to the extension of the controlling piezoelectric element 20 and the resonance frequency of the ultrasonic oscillator 2 can be varied according to a voltage impressed from a direct current power source 36. Accordingly, the direct current voltage is controlled to make the mechanical resonance frequency of the ultrasonic oscillator 2 coincide with the alternating current frequency from a direct current power source 36, namely, an electric frequency and the ultrasonic oscillation can be excited with high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Field of Industrial Application] The present invention relates to an ultrasonic imager that can generate ultrasonic imaging with high efficiency.

[Prior Art] Conventionally, electromechanical transducers using electrostrictive elements, magnetostrictive elements, or piezoelectric elements have been used to convert electrical signals into mechanical vibrations and generate ultrasonic vibrations. There is. The ultrasonic transducer has a resonator attached to these electromechanical transducers, and is configured to obtain ultrasonic imaging with a large amplitude.

In the above ultrasonic transducer, if an electrical input that matches the mechanical resonance frequency of the transducer is applied to the electromechanical transducer, ultrasonic imaging with extremely high efficiency can be obtained. When the mechanical resonance frequency fluctuates due to temperature fluctuations or changes over time, the efficiency rapidly decreases in proportion to the resonance sharpness Q). Therefore, conventional ultrasonic imagers often use feedback control in which the amplitude of the ultrasonic transducer is detected and the frequency of the electrical input is fed back so that the amplitude is maximized.

[Problems to be Solved by the Invention] However, even with the above-mentioned ultrasonic transducer, it is still not sufficient and has the following problems.

In other words, in the case where the fluctuation of the resonant frequency of the ultrasonic transducer is adjusted by the frequency of the electrical input, the vibration frequency of the ultrasonic wave generated by the ultrasonic transducer is not always fixed, but changes within a certain range. Become.

This makes it impossible to obtain ultrasonic vibrations of a predetermined frequency in a system in which a plurality of ultrasonic transducers work together, such as a traveling wave ultrasonic motor.

The present invention has been made to solve the above problems, and is an excellent ultrasonic wave in which the vibration frequency of ultrasonic waves is always constant, and which can convert applied electrical input into ultrasonic vibrations with high efficiency. Its purpose is to provide a sound wave transducer.

Configuration of the Invention [Means for Solving the Problems] The configuration of the ultrasonic sensor of the present invention for solving the above problems includes an electromechanical transducer that is excited to vibrate by applying an electric signal. In an ultrasonic sensor that obtains large-amplitude ultrasonic vibration by utilizing the resonance effect of the resonator, the resonator is crimped with a predetermined crimping force using a crimping mechanism. The present invention is characterized in that another electromechanical transducer element that changes the pressing force is disposed in the crimping mechanism that crimps the resonator.

[Function] In the ultrasonic transducer of the present invention, another electromechanical transducer is present in the crimping mechanism that crimps the electromechanical transducer and the resonator, and by applying a desired electrical signal to this, The pressing force can be controlled.

[Example] Hereinafter, in order to explain the present invention more specifically, an example will be given and explained.

FIG. 1 is a partially cutaway perspective view of an ultrasonic transducer 2 according to an embodiment, and is an explanatory diagram in which the driving electric circuit is briefly illustrated. As is clear from the figure, the ultrasonic transducer 2 of this embodiment has a bolt-fastened Langevin type structure, in which both sides of the driving piezoelectric element 4 on a disk in the center are sandwiched between thick elastic bodies 6.8. , a bolt 10 passing through these central axes and the bolt 1
Tightening with the nut 12 screwed into the drive piezoelectric element 4 and the elastic bodies 6 and 8 is performed by force. Driving electrode plate 14 for giving electrical signals to the driving piezoelectric element 4
is electrically and closely attached to the upper surface of the driving piezoelectric element 4,
In addition, in order to electrically insulate the elastic body 6, the elastic body 6 is
is in contact with.

On the other hand, a control electrode plate 18 is provided on the other side of the driving piezoelectric element 4.
A control piezoelectric element 20 which is electrically and tightly attached is interposed between the elastic body 8 and the elastic body 8 .

In other words, the ultrasonic transducer of this embodiment has no difference from a normal bolt-fastened Langevin type ultrasonic transducer except for the above-mentioned control piezoelectric element 20. This is a normal configuration in which an AC drive power source 30 is connected via a matching circuit 32 to a drive electrode plate 14 that transmits information efficiently.

A DC voltage is applied to the control piezoelectric element 20, which is unique to the ultrasonic sensor 2 of the embodiment, from a variable voltage DC power supply 36 connected to the control electrode plate 18.

As is well known, the piezoelectric element 12 has an expansion and contraction action proportional to the applied voltage, and if a DC voltage is applied, the control piezoelectric element 20 will expand or contract in proportion to the applied voltage value, causing an overflow. The bolt tightening force when viewed from the entire sound wave vibrator 2 can be changed arbitrarily. This means that the resonant frequency of the ultrasonic vibrator 2 can be varied by the voltage applied from the DC power source 36, and the resonant frequency of the ultrasonic vibrator 2 can be controlled by the voltage value of the DC power source 36. Therefore, by controlling the DC voltage to match the mechanical resonance frequency of the ultrasonic vibrator 2 with the AC frequency, ie, the electrical frequency, of the driving power source 30, highly efficient excitation of ultrasonic vibration is achieved.

Note that in the above embodiment, the control piezoelectric element 20 is arranged approximately at the center of the ultrasound sensor 2, but this is because the control piezoelectric element 20 is arranged near the node of the ultrasound sensor 2. This is because even a slight expansion or contraction of the control piezoelectric element 20 causes a large change in the resonance frequency. Therefore, without being limited to the configuration of this embodiment, the arrangement position of the control piezoelectric element 20 in the crimping mechanism may be changed in consideration of the piezoelectric effect of the control piezoelectric element 20, the control range of the resonance frequency, the control accuracy, etc. Alternatively, it may be modified as appropriate, such as by arranging a plurality of them in parallel. Furthermore, the element used for the electromechanical transducer is not limited to a piezoelectric element, and may be realized in various forms without departing from the gist of the present invention, such as using an electrostrictive or magnetostrictive element.

FIG. 2 shows an application example in which a traveling wave ultrasonic motor is constructed using a plurality of ultrasonic sensors 2 whose mechanical resonance frequencies can be controlled as in the above embodiment.

The drive piezoelectric elements 4A and 4B arranged in the two ultrasonic transducers 2A and 2B are powered by the same drive power source 30.
However, one driving piezoelectric element 4B is configured so that an electric signal having a phase difference of 90' with respect to the electric signal of the power supply 30 is inputted by a phase shifter 40. Electric signals having a phase difference of 90 degrees are sent to an amplifier 42A.

42B and matching circuits 32A, 32B to drive piezoelectric elements 4A, 4B, and the voltage and current of the supplied electric signals are further transmitted to resonance detection circuits 50Ai 50B.
The resonance condition is detected by the two ultrasonic imagers 2A based on the outputs of the resonance detection circuits 50A and 50B.
, 2B, the voltages of the DC power supplies 36A, 36B applied to the control piezoelectric elements 2OA, 20B are controlled. Since the resonance detection circuits 50A and 50B both have the same configuration, only the resonance detection circuit 50A is shown in detail in the figure. As is well known, an electrical resonance state is a state in which the actance in the circuit is zero and the voltage and current are in phase. Therefore, the resonance detection circuits 50A and 50B are driven by the driving piezoelectric element 2A,
The input electrical signal of 2B is picked up from both ends of the constant resistor R, and a current waveform is generated by a differential amplifier 51 that amplifies the potential difference between both ends, and a voltage waveform is generated by a differential amplifier 52 that amplifies the potential from the ground at either end. is being detected. and,
The phase comparator 53 compares the phases of the output waveforms of the difference amplifiers 51 and 52 to detect the amount of deviation from the electrical resonance state. Control the potential. Thereby, the ultrasonic transducers 2A and 2B are feedback-controlled to have a resonance frequency that matches the frequency of the driving power source 30, and highly efficient ultrasonic wave generation is performed. As mentioned above, the electric signal phases of the ultrasonic transducers 2A and 2B, which are each driven with the same frequency and with high efficiency, are shifted by 90 degrees from each other. If the stator 60 is arranged at a distance of 1/4 wavelength of the characteristic traveling wave and the stator 60 is excited, a clockwise traveling wave can be generated as shown in the figure. Therefore, a rotational movement force in the opposite direction to the traveling wave is generated in the rotor 70 which is brought into contact with the stator 60 at a constant pressure, thereby forming a traveling wave ultrasonic motor.

As described above, according to the ultrasonic transducer of this embodiment, the frequency of the generated ultrasonic imaging is always stable at a constant value, which makes it possible to use a system in which multiple tubes of ultrasonic transducers work together. Can be easily constructed.

Effects of the Invention As described in detail with reference to examples, the ultrasonic sensor of the present invention is capable of creating a highly efficient resonance state at a predetermined frequency, and is capable of producing a multi-tube ultrasonic sensor. It is an excellent ultrasonic sensor with a wide range of applications, as it can be used in conjunction with other devices and can be easily used for loads with a constant resonance frequency.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing the basic configuration of an ultrasonic sensor of the present invention, and FIG. 2 is a schematic diagram of the configuration of an ultrasonic motor using the ultrasonic transducer of the same embodiment.

Claims (1)

[Claims] A resonator is crimped with a predetermined crimping force using a crimping mechanism against an electromechanical transducer whose vibrations are excited by the application of an electric signal, and the resonance effect of the resonator is utilized. The ultrasonic transducer that obtains large amplitude ultrasonic vibrations is characterized in that another electromechanical transducer that changes the pressing force is disposed in a crimping mechanism that crimps the electromechanical transducer and the resonator. Ultrasonic transducer.