Patent Number: 6,310,834

Title: Electronic apparatus with ultrasonic motor as driving source

Abstract: Residual battery capacity is calculated in an electronic apparatus having an ultrasonic motor driven by a battery based on the revolution speed of the ultrasonic motor. This permits residual capacity to be calculated extremely close to actual battery life with a simplified circuit structure. An electronic watch having an ultrasonic motor as a driving source of a calendar display mechanism is provided with a residual battery capacity display device having a revolution speed detector for detecting a revolution speed of the ultrasonic motor, a memory for storing comparison representing a relationship between detected revolution speed and battery life, and a CPU for determining residual battery life based on the detected revolution speed and the comparison data. An alarm is generated when the battery life is over.

Inventors: Nosaka; Naokatsu (Chiba, JP)

Assignee: Seiko Instruments Inc.

International Classification: G04C 10/00 (20060101); G04C 3/00 (20060101); G04C 10/04 (20060101); G04C 3/12 (20060101); G04B 009/00 ()

Expiration Date: 10/30/2018