Development of Low-Frequency Radio Controlled Watch

Abstract

A radio controlled watch, that receives time codes on long-wave standard frequency and sets the time automatically, has been developed. The radio controlled watch developed thistime is of a multi-station receiving type that receives some standard frequencies by a switching operation. The watch is of an analog display type being equipped with 4 motors. The multi-station receiving type radio controlled Watch of this kind is the first one in the world. This paper reports the following three major points, excluding the receiving circuit. (1) Multi-station receiving system This watch is designed to receive three standard frequencies from Japan, U.K., and Germany by switching channels. For station selection, a mechanical contact point selects a mode and switches the capacitance. (2) Antenna system built in case A new case structure has been developed to install a very small bar-antenna inside a case. The built-in antenna inside the case permits use of a metal band. (3) Discontinuity of hand position after battery change Before battery change, the content of hand position counter is stored in an IC to dispense with hand positioning operation after battery change.