Laser trimming monolithic crystal filters to frequency
Patent 4642505 Issued on February 10, 1987. Estimated Expiration Date: 
March 5, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 5, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3535778 3683213 3766616 3781577 3913195 Process for automatically adjusting the frequency of piezoelectric resonators in the form of bars or plates Removal of thin films from substrates by laser induced explosion Frequency adjusting a piezoelectric device by lasering Process for cutting or shaping of a substrate by laser Laser trim protection process InventorAssigneeApplicationNo. 06/585967 filed on 03/05/1984US Classes:310/312, Adding or subtracting mass29/25.35, PIEZOELECTRIC DEVICE MAKING310/320, Piezoelectric slab having different resonant frequencies at different areas310/365, Electrode arrangement310/366More than twoExaminersPrimary: Budd, Mark O.Attorney, Agent or FirmInternational ClassesH03H 3/00 (20060101)H03H 3/04 (20060101) AbstractAn improved method of adjusting piezoelectric devices to frequency by particularized laser trimming is disclosed. The laser removes a single contiguous area in the center of the electrodes to appropriately increase the individual resonator frequency without significantly degrading the filter "Q". In an AT-cut monolithic crystal filter, the particularized laser trimmed area can be positioned such on the face of the electrodes to simultaneously control frequency and bandwidth. This method can be substituted for the more cumbersome process of frequency adjustment by vapor deposition to provide a rapid inexpensive technique for monolithic crystal filter manufacture.Other References
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