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IP.com Disclosure Number: IPCOM000006291D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2001-Dec-20

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Hiroyuki Kanda


Crystal oscillators are often used in portable com- munication electronic equipment such as pagers. Due to the nature of use of pagers, the crystal oscillator must be protected from mechanical shock caused by the pager being dropped, thrown, etc. Previously, the crystal oscil- lators were placed on the unit's Printed Circuit (PC) board and epoxied into place. The problem generated by this method was only the sides were epoxied down. The bottom of the crystal oscillator was touching the PC board. When a pager using this method is dropped, the waves from the shock pass through the pager hous- ing and into the PC board. The PC board begins to vibrate from the shock thus beating against the bottom of the crystal oscillator. The resulting shock waves may have magnitudes of up to twice the magnitude of the shock waves in the pager housing. A natural result is failure of the crystal oscillator.