US 7,247,970 B2Granted

Drive method for piezoelectric actuator, drive apparatus for piezoelectric actuator, electronic device, control program for drive apparatus for piezoelectric actuator, and recording medium

AssigneeSeiko Epson Corporation

InventorsJun Matsuzaki, Takashi Kawaguchi, Reiko Nagahama

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Abstract

A frequency of a drive signal supplied to a piezoelectric element is swept within a specific range, a detection signal indicating the vibrating state of a vibrating member is detected, and the sweep speed of the drive signal frequency supplied to the piezoelectric element is controlled based on this detection signal. Thus, even if nonuniformities occur in the drive frequency of the piezoelectric element due to fluctuations in the surrounding temperature or the load, such nonuniformities can be overcome without any adjustments, and the piezoelectric element can be reliably driven. Also, since the sweep speed of the drive signal frequency is at a high speed when the vibrating member is in a non-drive state, needless drive signal output time during which the piezoelectric element cannot be driven can be reduced, needless power consumption can be curtailed, and nonuniformities in the drive speed of the driven object can also be reduced.

Claims19

Dependent claims

A drive method for a piezoelectric actuator comprising:

preparing a frequency control device of a piezoelectric actuator and said piezoelectric actuator, said piezoelectric actuator having
a vibrating body being vibrated by the application of a drive signal with a specific frequency to a piezoelectric element, and
a contact section being provided on said vibrating body and pressed against a driven object, and
said frequency control device having
a first variable frequency oscillator being configured to output a clock signal and to vary a clock signal frequency,
a voltage adjustment circuit having an up-down counter to input said clock signal outputted from said first variable frequency oscillator, and a digital/analog converter to set a voltage value of output voltage on the basis of a counter value of said up-down counter,
a second variable frequency oscillator being configured to vary an output signal frequency by voltage outputted from said voltage adjustment circuit, and
a control circuit, said control circuit having
a sweep direction control unit to select a sweep direction by switching clock signal input to up input or down input of said up-down counter,
a sweep speed control unit to control sweep speed by varying said clock signal frequency outputted from said first variable frequency oscillator, and
a frequency resolution control unit to control frequency resolution by setting the bit number of said up-down counter;
supplying said drive signal to said piezoelectric element at a frequency being swept within a specific range;
detecting a detection signal indicating a vibrating state of said vibrating body;
and
controlling a sweep speed of said frequency of said drive signal supplied to said piezoelectric element based on said detection signal.

12 more elements

A drive apparatus comprising:

a piezoelectric actuator having a piezoelectric element, said piezoelectric element having
a vibrating body being configured to be vibrated by the application of a drive signal with a specific frequency of a drive signal frequency to said piezoelectric element, and
a contact section being provided on said vibrating body and pressed against a driven object within a specific range;
a frequency control device being configured to sweep said drive signal frequency of said drive signal being supplied to said piezoelectric element, said frequency control device being configured to detect a detection signal indicating a vibrating state of said vibrating body, and to control a sweep speed of said drive signal frequency being supplied to said piezoelectric element on the basis of said detection signal, said frequency control device having
a first variable frequency oscillator being configured to output a clock signal and being configured to vary a clock signal frequency,
a voltage adjustment circuit having an up-down counter to input said clock signal outputted from said first variable frequency oscillator, and a digital/analog converter to set a voltage value of output voltage on the basis of a counter value of said up-down counter,
a second variable frequency oscillator being configured to vary an output signal frequency by voltage outputted from said voltage adjustment circuit, and
a control circuit, said control circuit having
a sweep direction control unit being configured to select a sweep direction by switching clock signal input to up input or down input of said up-down counter,
a sweep speed control unit being configured to control sweep speed by varying said clock signal frequency outputted from said first variable frequency oscillator, and
a frequency resolution control unit being configured to control frequency resolution by setting the bit number of said up-down counter.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/171,183Filed 1 Jul 2005
Priority: JP 2004-1967412 Jul 2004
Published: US 2006/0001330 A15 Jan 2006
Granted: 24 Jul 2007
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H02N 2/004
Using longitudinal or radial modes combined with bending modes: rectangular vibrators
H02N 2/101
Producing rotary motion, e.g. rotary motors: using intermittent driving, e.g. step motors
H02N 2/103
Producing rotary motion, e.g. rotary motors: by pressing one or more vibrators against the rotor
H02N 2/142
Drive circuits; Control arrangements or methods: small signal circuits; Means for controlling position or derived quantities, e.g. speed, torque,…