| 摘要 |
PROBLEM TO BE SOLVED: To provide an individual information detecting apparatus which meets a demand for increasing a frequency of an element driving signal, and is low-cost and has high productivity. SOLUTION: Each of reflectors 43A-43C on a piezoelectric substrate 41 is composed of a pair of comb-like electrodes which cross each other in a half wavelength pitch of a surface acoustic wave, and connected via selectors 50A-50C for short-circuiting or opening these electrodes. In the case of reflecting the surface acoustic wave excited by a transmitting/receiving electrode 42 in each of the reflectors 43A-43C, when the electrodes are short-circuited, only reflection using an acoustic addition effect appears. When the electrodes are opened, on the other hand, reflection using both the acoustic addition effect and a re-excitation effect appears, so that a reflected signal stronger than that in a state of short-circuiting the electrodes can be obtained. On the basis of the strength of the reflected signal depending on a state of connecting the electrodes, a response signal from a surface acoustic wave element 24 is encoded. Thus, the reflectors can be constituted at lower cost than a comb-like double electrode structure. COPYRIGHT: (C)2005,JPO&NCIPI
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