| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter element as a single unit having a band elimination function. SOLUTION: The filter element is provided with: a vibration section 16 held in midair via a beam 16 by a pair of supporting members 15; an input terminal 11; and an output terminal 12 disposed oppositely to the vibration portion 16 with a predetermined space. The vibration portion 16 is composed of a single structure, and vibrates based on a resonance mode caused by torsional vibration and a resonance mode caused by flexure vibration when an AC signal is applied to the input electrode 11. The resonance mode caused by the torsional vibration has a resonance frequency f<SB>1</SB>and a reverse resonance frequency f<SB>2</SB>of a frequency larger than the resonance frequency f<SB>1</SB>, and the resonance mode caused by the flexure vibration has a resonance frequency f<SB>3</SB>of a frequency larger than the resonance frequency f<SB>1</SB>and a reverse resonance frequency f<SB>4</SB>of a frequency smaller than the resonance frequency f<SB>3</SB>and larger than the resonance frequency f<SB>1</SB>. COPYRIGHT: (C)2009,JPO&INPIT
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