Development of the Solar-Powered Movement with Annual Rate of ±1 Second

Abstract

  CITIZEN has developed solar-powered movement with a target accuracy of ±1 second per year. First, we examined a standard of ±1 second per year with reference to "JIS B 7025," which has established accuracy standards. In addition to the two items of "aging" and "temperature characteristics", four additional items of "humidity characteristics," "attitude difference," "power supply voltage characteristics," and "adjustment error" were added to set the target accuracy and aimed to achieve it. The target accuracy of ±1 second per year was achieved by employing a new AT-cut quartz oscillator, temperature compensation using a higher-order polynomial, and other technologies. In addition, by reducing power consumption through technologies such as dynamic frequency divider circuits, we have developed the Cal.0100 as a solar-powered movement that can operate for more than six months in the dark when the battery is fully charged.