Driving apparatus for piezoelectric ceramic elements

Claim 2

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said amplifier comprising an input transformer connected to the output of said phase detector, a transistor connected to the output of sAid transformer, an output transformer connected to the output of said transistor and means for connecting the driving electrodes of said piezoelectric ceramic element across the output of said output transformer.

Claim 3

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said driving apparatus including a three winding transformer, a first winding thereof comprising said phase detector, a second winding comprising said phase shifter and a third winding being utilized as an output winding and connected to said amplifier, said phase shifter further including a capacitor connected to said second winding.

Claim 4

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said driving apparatus including a three winding transformer, a first winding thereof comprising said phase detector, a second winding comprising said phase shifter and a third winding being utilized as an output winding and connected to said amplifier, said phase shifter further including a capacitor connected to said second winding.

Claim 5

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said phase detector comprising an emitter grounded type transistor, the base electrode thereof being connected directly to the driving electrode of said ceramic element and the collector electrode being utilized to derive an output and connected to said phase shifter.

Claim 6

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said phase detector comprising an emitter grounded type transistor, the base electrode thereof being connected directly to the driving electrode of said ceramic element and the collector electrode being utilized to derive an output and connected to said phase shifter.

Claim 7

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said phase detector comprising a base grounded type transistor, the emitter electrode thereof being connected directly to the driving electrode of said ceramic element and the collector electrode being utilized to derive out an output and connected to said phase shifter.

Claim 8

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said phase detector comprising a base grounded type transistor, the emitter electrode thereof being connected directly to the driving electrode of said ceramic element and the collector electrode being utilized to derive out an output and connected to said phase shifter.

Claim 9

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase sHifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said driving apparatus including a transformer whose secondary winding is connected to said amplifier and whose primary winding is provided with an intermediate top, said phase detector comprising one portion of said primary winding between said intermediate top and one end of said primary winding, said phase shifter comprising the other portion of said primary winding and a capacitor connected thereto.

Claim 10

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase sHifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said driving apparatus including a transformer whose secondary winding is connected to said amplifier and whose primary winding is provided with an intermediate top, said phase detector comprising one portion of said primary winding between said intermediate top and one end of said primary winding, said phase shifter comprising the other portion of said primary winding and a capacitor connected thereto.

Claim 11

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said phase shifter having a center frequency which shifts in response to temperature variations in the environment of said apparatus to compensate for the effect of said temperature variations on the resonance frequency of said piezoelectric ceramic element.

Claim 12

Driving apparatus for driving a piezoelectric ceramic element including a pair of driving electrodes wherein a driving voltage is impressed across said driving electrodes for resonating said piezoelectric ceramic element at the natural frequency thereof, said driving apparatus comprising a phase detector connected to one of said driving electrodes for detecting the phase of the current flowing through said ceramic element as a voltage phase, an amplifier connected to the other driving electrode for supplying thereto a driving voltage, and a phase shifter to positively feed back the output from said phase detector to said amplifier for coinciding the voltage phase and the current phase of said ceramic element so as to drive said ceramic member at the most suitable driving frequency, said phase shifter having a center frequency which shifts in response to temperature variations in the environment of said apparatus to compensate for the effect of said temperature variations on the resonance frequency of said piezoelectric ceramic element.

Claim 13

The driving apparatus as recited in claim 6 wherein said phase shifter comprises a resonance circuit including a capacitor and an inductor connected thereto, the resonant frequency of said resonance circuit varying substantially in accordance with the effect of said temperature variations on said capacitor.

Claim 14

The driving apparatus as recited in claim 6 wherein said phase shifter comprises a resonance circuit including a capacitor and an inductor connected thereto, the resonant frequency of said resonance circuit varying in dependence on the effect of said temperature variations on said inductor.