Drive apparatus of piezoelectric actuator, electronic apparatus, drive method of electronic apparatus, drive control program of electronic apparatus, and medium

• US 20070278976A1
• Filed: 03/10/2005
• Published: 12/06/2007
• Est. Priority Date: 03/10/2004
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Kawaguchi, Takashi, Sawada, Akihiro, Yamazaki, Yutaka, Okeya, Makoto
• Granted Patent: US 7,675,218 B2
• Time in Patent Office: Days
• US Class Current: 318/116
• CPC Class Codes: G04C 17/005 by discs by drums G04C17/0075
• CPC Class Codes: G04C 3/12 driven by piezoelectric means; driven by magneto-strictive means
• CPC Class Codes: H02N 2/004 Rectangular vibrators
• CPC Class Codes: H02N 2/062 Small signal circuits; Means for controlling position or derived quantities, e.g. for removing hysteresis
• CPC Class Codes: H02N 2/103 by pressing one or more vibrators against the rotor
• CPC Class Codes: H02N 2/142 Small signal circuits; Means for controlling position or derived quantities, e.g. speed, torque, starting, stopping, reversing
• CPC Class Codes: H10N 30/202 using longitudinal or thickness displacement combined with bending, shear or torsion displacement

Abstract

An electronic device comprising a power source, a piezoelectric actuator A, and a drive control apparatus 100 for controlling the driving of the piezoelectric actuator, wherein the drive control apparatus 100 is provided with a drive circuit 111 for supplying a drive signal SDR to the piezoelectric element of the vibrating body 12, a phase difference detection means 120 for detecting the phase difference indicating the vibration state of the vibrating body 12, a comparison voltage setting circuit 133 for correcting the target phase difference to be the target for the vibration state, and a drive frequency setting means 140 for comparing the phase difference with the target phase difference; and the piezoelectric actuator A can be driven with high efficiency independent of the drive voltage by modifying the drive frequency of the drive signal SDR so that the phase difference approaches the target phase difference based on the results of the above comparison.

Claims

1. A drive apparatus for driving a piezoelectric actuator having a vibrating body that vibrates due to application of a drive signal having a prescribed drive frequency to a piezoelectric element, said piezoelectric actuator drive apparatus comprising:

driving means for supplying said drive signal to the piezoelectric element of said vibrating body;

vibration state detection means for detecting a value that indicates said vibration state of said vibrating body;

target value setting means for setting said target value to be said target for said vibration state;

correction means for correcting at least one of said value indicating said vibration state and said target value based on at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said value indicating said vibration state;

comparison means for comparing said value indicating said vibration state with said target value; and

control means for modifying said drive frequency of said drive signal so that said value indicating said vibration state approaches said target value based on said results of comparison by said comparison means.

2. The drive apparatus according to claim 1, wherein:

said vibration state detection means comprises phase difference detection means for detecting said phase difference between said drive signal and a detection signal obtained from a vibration detection electrode mounted on said piezoelectric element, or said phase difference among a plurality of detection signals;

said target value setting means sets said target value to be said target for said phase difference;

said correction means comprises voltage detection means for detecting at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said detection signal; and

phase difference modifying means for modifying said target phase difference based on said voltage value of said voltage detection signal; and

said comparison means compares said phase difference with said modified target phase difference.

3. The piezoelectric actuator drive apparatus according to claim 1, wherein:

said vibration state detection means comprises phase difference detection means for detecting said phase difference between said drive signal and a detection signal obtained from a vibration detection electrode mounted on said piezoelectric element, or said phase difference among a plurality of detection signals;

said target value setting means sets said target value to be said target for said phase difference;

said correction means comprises voltage detection means for detecting at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said detection signal; and

phase difference shifting means for shifting said phase difference based on said voltage value of said detection signal; and

said comparison means compares said shifted phase difference with said target phase difference.

4. The piezoelectric actuator drive apparatus according to claim 1, wherein:

said correction means comprises phase difference shifting means for shifting said phase difference of said detection signal based on at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said detection signal obtained from said vibration detection electrode mounted on said piezoelectric element;

said vibration state detection means comprises phase difference detection means for detecting said phase difference between said drive signal and said phase-shifted detection signal;

said target value setting means sets said target phase difference to be said target for said phase difference; and

said comparison means compares said phase difference with said target phase difference.

5. The piezoelectric actuator drive apparatus according to claim 4, wherein said phase shifting means comprises a nonlinear element.

6. The piezoelectric actuator drive apparatus according to claim 5, wherein said nonlinear element comprises a diode.

7. The piezoelectric actuator drive apparatus according to claim 6, wherein said diode comprises a parasitic diode of a MOS transistor.

8. The piezoelectric actuator drive apparatus according to claim 5, wherein said nonlinear element comprises an off-state transistor.

9. The piezoelectric actuator drive apparatus according to claim 2, wherein said phase difference detection means comprises a waveform shaping circuit for shaping said waveforms of said drive signal and said detection signal;

and a phase difference voltage conversion circuit for detecting said phase difference of said signals thus shaped, and converting said phase difference thus detected to a voltage.

10. The piezoelectric actuator drive apparatus according to claim 1, wherein:

said vibration state detection means comprises voltage detection means for detecting said voltage of said detection signal obtained from said vibration detection electrode mounted on said piezoelectric element;

said target value setting means sets said target voltage to be said target voltage of said detection signal;

said correction means comprises voltage modifying means for modifying at least one of said voltage of said detection signal and said target voltage based on at least one of said power source voltage and said drive voltage of said piezoelectric actuator; and

said comparison means compares said voltage of said detection signal with target voltage.

11. The piezoelectric actuator drive apparatus according to claim 1, wherein:

said vibration state detection means comprises current detection means for detecting said current of said detection signal obtained from said vibration detection electrode mounted on said piezoelectric element;

said target value setting means sets said target current to be said target current of said detection signal;

said correction means has a current modifying means for modifying at least one of said current of said detection signal and said target current based on at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said detection signal; and

said comparison means compares said current of said detection signal with said target current.

12. The piezoelectric actuator drive apparatus according to claim 1, wherein:

said vibration state detection means comprises current detection means for detecting said current of said drive signal;

said target value setting means sets said target current to be said target current of said drive signal;

said correction means comprises current modifying means for modifying at least one of said current of said drive signal and said target current based on at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said detection signal obtained from said vibration detection electrode mounted on said piezoelectric element; and

said comparison means compares said current of said detection signal with said target current.

13. The piezoelectric actuator drive apparatus according to claim 1, wherein:

said comparison means comprises computation means for computing said results of comparing said value indicating said vibration state with said target value; and

said control means modifies said drive frequency of said drive signal based on said computed information computed by said computation means.

14. An electronic device, comprising:

a power source; and

a driving apparatus for driving, to which electrical power is supplied by said power source;

wherein said electronic device further comprises a driving component for driving a piezoelectric actuator having a vibrating body that vibrates due to said application of a drive signal having a prescribed drive frequency to a piezoelectric element, said piezoelectric actuator driving component comprising;

driving means for supplying said drive signal to said piezoelectric element of said vibrating body;

vibration state detection means for detecting a value that indicates said vibration state of said vibrating body;

target value setting means for setting said target value to be said target for said vibration state;

correction means for correcting at least one of said value indicating said vibration state and said target value based on at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said value indicating said vibration state;

comparison means for comparing said value indicating said vibration state with said target value; and

control means for modifying said drive frequency of said drive signal so that said value indicating said vibration state approaches said target value based on said results of comparison by said comparison means.

15. An electronic device driving method for driving an electronic device provided with a piezoelectric actuator having a vibrating body that vibrates due to said application of a drive signal having a prescribed drive frequency to a piezoelectric element;

driving means for supplying said drive signal to said piezoelectric element of said vibrating body; and

a power source, said electronic device driving method comprising;

a vibration state detection step for detecting said value indicating said vibration state of said vibrating body;

a target value setting step for setting a target value to be said target for said vibration state;

a correction step for correcting at least one of said value indicating said vibration state and said target value based on at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said value indicating said vibration state;

a comparison step for comparing said value indicating said vibration state with said target value; and

a control step for modifying said drive frequency of said drive signal based on said results of comparison in said comparison step so that said value indicating said vibration state approaches said target value.

16. An electronic device drive control program whereby a computer built into an electronic device provided with a piezoelectric actuator having a vibrating body that vibrates due to said application of a drive signal having a prescribed drive frequency to a piezoelectric element, and further provided with a drive apparatus having driving means for supplying said drive signal to said piezoelectric element of the vibrating body, and a power source, is caused to function as at least one of:

driving means for supplying said drive signal to said piezoelectric element of said vibrating body;

vibration state detection means for detecting a value that indicates said vibration state of said vibrating body;

target value setting means for setting said target value to be said target for said vibration state;

correction means for correcting at least one of said value indicating said vibration state and said target value based on at least one of said power source voltage, said drive voltage of said piezoelectric actuator, and said voltage value of said value indicating said vibration state;

comparison means for comparing said value indicating said vibration state with said target value; and

control means for modifying said drive frequency of said drive signal so that said value indicating said vibration state approaches said target value based on said results of comparison by said comparison means.

17. A storage medium in which said electronic device drive control program according to claim 16 is recorded so as to be readable by a computer.