| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a measured value such as pneumatic pressure, while reducing an influence of a factor such as a temperature of a tire. SOLUTION: A transponder 10 is provided with an antenna 11, a modulating and demodulating device (diode) 12 for modulating and demodulating a signal transceived to/from a controller, a resonator 14 for pressure having the first piezoelectric single crystal resonator 17a and a pressure sensor, and having a resonance frequency varied in response to a change of the pneumatic pressure of the tire, and a resonator 16 for a reference having the second piezoelectric single crystal resonator 17b and a capacitor 21, and having a resonance frequency not affected by the change of the pneumatic pressure of the tire, the first piezoelectric single crystal resonator 17a and the second piezoelectric single crystal resonator 17b are integrally formed on one single crystal piece 17, and the controller transmits signals for resonating the resonators for the pressure and the reference, receives signals modulated by resonance frequencies for the resonators for the pressure and the reference, and calculates the measured values in response to the resonance frequencies of both resonators extracted from the signals. COPYRIGHT: (C)2008,JPO&INPIT
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