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

• US 7,675,218 B2
• Filed: 03/10/2005
• Issued: 03/09/2010
• Est. Priority Date: 03/10/2004
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yamazaki, Yutaka, Kawaguchi, Takashi, Okeya, Makoto, Sawada, Akihiro
• Primary Examiner(s): Benson; Walter
• Assistant Examiner(s): Gordon; Bryan P
• Application Number:
  US11/076,065
• Publication Number:
  US 20070278976A1
• Time in Patent Office: 1,825 Days
• Field of Search: 310/317
• US Class Current: 310/317
• 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 piezoelectric actuator 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 driving a driven member, said piezoelectric actuator drive apparatus comprising:

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

vibration state detection signal outputting means for outputting a vibration state detection signal that indicates vibration state of said vibrating body;

phase correcting means for correcting a phase of said vibration state detection signal to corrected phase, on the basis of voltage of said vibration state detection signal;

phase difference detection means for detecting phase difference between said phase of drive signal and said corrected phase;

comparison means for comparing said phase difference with a target phase difference which is a target to optimize said vibration state at which the vibrating body is efficiently driven; and

control means for controlling said phase difference to approach said target phase difference by changing said drive frequency.

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

said phase correcting means includes a capacitor or a parasitic capacitance of an MOS transistor and at least one of a diode, a parasitic diode of an MOS transistor and an off-state transistor, and

said phase correcting means corrects said phase of the vibration state detection signal to a corrected phase when a voltage of said vibration state detection signal is more than a threshold voltage of at least said one of said diode, said parasitic diode of said MOS transistor, and said off-state transistor after being used.