Title:
質量測定方法および質量測定用圧電振動片の励振回路並びに質量測定装置
Document Type and Number:
Japanese Patent JP4181579
Kind Code:
B2
Abstract:
The present invention is directed to reliably perform a mass measurement. A mass measurement apparatus (10) has an excitation circuit (14) to forcibly excite a piezoelectric vibration reed (12). The excitation circuit (14) comprises a PLL circuit (20). In the PLL circuit (20), a voltage controlled oscillation circuit (24) outputs an excitation signal. The excitation signal is supplied to the piezoelectric vibration reed (12) and a phase comparator (26) via a distributor (22). The phase comparator (26) outputs a signal corresponding to a phase difference between an output signal of the piezoelectric vibration reed (12) and the excitation signal. The signal is passed through a loop filter (28) to be converted to a direct-current voltage and supplied to the voltage controlled oscillator (24) as a control voltage. The voltage controlled oscillator (24) has an oscillation frequency varying in accordance with the control voltage, outputs the excitation signal with no phase difference with respect to the output signal of the piezoelectric vibration reed (12), and causes the piezoelectric vibration reed (12) to resonate. A signal processing unit (16) counts the output frequency of the voltage controlled oscillator (24) and calculates the resonance frequency of the piezoelectric vibration reed (12).
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Inventors:
Yoshihiro Kobayashi
Application Number:
JP2005504085A
Publication Date:
November 19, 2008
Filing Date:
March 24, 2004
Export Citation:
Assignee:
Seiko Epson Corporation
International Classes:
G01G3/16; G01N5/02; G01N11/16
Domestic Patent References:
| JP6308009A | ||||
| JP5223721A | ||||
| JP6241972A | ||||
| JP10132646A |
Attorney, Agent or Firm:
Masahiko Ueyanagi
Kazuhiko Miyasaka
Kazuhiko Miyasaka