MASS MEASURING METHOD, CIRCUIT FOR EXCITING PIEZOELECTRIC VIBRATORY PIECE FOR MASS MEASUREMENT, AND MASS MEASURING INSTRUMENT

Title:

MASS MEASURING METHOD, CIRCUIT FOR EXCITING PIEZOELECTRIC VIBRATORY PIECE FOR MASS MEASUREMENT, AND MASS MEASURING INSTRUMENT

Document Type and Number:

WIPO Patent Application WO/2004/085976

Kind Code:

A1

Abstract:

Mass measurement is accurately carried out. A mass measuring instrument (10) has an exciting circuit (14) for forcedly exciting a piezoelectric vibratory piece (12). The exciting circuit (14) has a PLL circuit (20). The PLL circuit (20) has a voltage-controlled oscillating circuit (24) that outputs an exciting signal. The exciting signal is fed to the piezoelectric vibratory piece (12) and a phase comparator (26) through a distributor (22). The phase comparator (26) output a signal corresponding to the phase difference between the output signal of the piezoelectric vibratory piece (12) and the exciting signal. The signal is passed through a loop filter (28) to be converted to a DC voltage and given to a voltage-controlled oscillator (24) as a control voltage. The voltage-controlled oscillator (24) oscillates at a frequency varying with the control voltage and outputs an exciting signal with no phase difference with the output signal of the piezoelectric vibratory piece (12) so as to resonate the piezoelectric vibratory piece (12). A signal processing section (16) counts the output frequency of the voltage-controlled oscillator (24) to determine the resonance frequency of the piezoelectric vibratory piece (12).

Inventors:

KOBAYASHI YOSHIHIRO

Application Number:

PCT/JP2004/004103

Publication Date:

October 07, 2004

Filing Date:

March 24, 2004

Export Citation:

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Assignee:

SEIKO EPSON CORP (JP)

International Classes:

G01G3/16; G01N5/02; G01N11/16; (IPC1-7): G01G3/16; G01N5/02

Foreign References:

JPH06308009A	1994-11-04
JPH05223721A	1993-08-31
JPH06241972A	1994-09-02
JPH10132646A	1998-05-22

Other References: