Title:
PHYSICAL QUANTITY SENSOR
Document Type and Number:
WIPO Patent Application WO/2005/012920
Kind Code:
A1
Abstract:
Two piezoelectric oscillators (Sa, Sb) are provided such that a stress is applied reversely by a physical quantity, e.g. an acceleration. A current/voltage conversion-signal summing circuit (11) converts current signals flowing through two piezoelectric oscillators (Sa, Sb) into voltage signals. A voltage amplification-amplitude limiting circuit (12) amplifies the sum signal of these two voltage signals and limits the amplitude thereof. A phase difference/voltage conversion circuit (15) detects the phase difference between the sum signal and a feedback voltage signal (Vosc) being fed to a speed detection element (10). A phase shift circuit (16) controls the feedback voltage signal to have a specified phase. A filter circuit (17) suppresses the frequency components in unwanted frequency bands higher than the oscillation frequency. Temperature stability is enhanced by increasing the resistances of resistors (Rla, RLb) thereby increasing the damping ratio, abnormal oscillation is prevented by the filter circuit (17) and variation in the characteristics is suppressed by a phase control circuit (20).
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Inventors:
YAMASHITA MUNEHARU (JP)
Application Number:
PCT/JP2004/007248
Publication Date:
February 10, 2005
Filing Date:
May 27, 2004
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
YAMASHITA MUNEHARU (JP)
YAMASHITA MUNEHARU (JP)
International Classes:
G01C19/56; G01C19/5776; G01L1/16; G01P15/09; G01P15/097; G01P15/10; H01L41/08; (IPC1-7): G01P15/09; G01P15/00; G01P3/44; G01L1/10
Foreign References:
| EP1324052A2 | 2003-07-02 | |||
| JPS6250630A | 1987-03-05 |
Attorney, Agent or Firm:
Komori, Hisao (Noninbashi Chuo-k, Osaka-shi Osaka 11, JP)
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