Technical Aspects of Crystal Wrist Watches

Abstract

In recent years, electronic watches using crystals have been increasing in popularity. The main attraction is their high precision. The crystal-regulated electronic watch was developed through the use of highly stable crystal units and new IC techniques. We will feature the present status of crystal-regulated electronic watches in two installments.In t h i s i s s u e , the crystal units employed in these watches will be discribed, and in the next issue, watches incorporating such units will be discussed.

The aging of bulk acoustic wave resonators, filters and oscillators

“…Hydrogen and helium are notorious for their permeation through metals and glasses, respectively. Even if the permeating gases do not adsorb onto the resonator, if a significant pressure increase occurs, the frequency will change due to the changing hydrostatic pressure in the enclosure [ 11,121. When a significant amount of gas leaks into a vacuum sealed resonator, aging can be caused by electrical and mechanical effects caused by changes in the package shape (sometimes called "oil canning," when the package changes with atmospheric pressure changes).…”