Electronic apparatus with ultrasonic motor as driving source

An electronic watch having an ultrasonic motor as a driving source for driving a calendar display mechanism, a battery for driving the ultrasonic motor, and a battery residual capacity display device for displaying a residual capacity of the battery, wherein the battery residual capacity display device comprises:

• a display unit for displaying the residual capacity of the battery;
• a revolution speed detector for detecting a revolution speed of the ultrasonic motor;
• a memory for storing comparison data;
• and
• a control circuit for comparing the detected revolution speed with the comparison data and for controlling the display unit to display the residual capacity of the battery on the basis of the comparison result.

An electronic timepiece comprising:

• a first display mechanism for displaying at least one of a current time and date;
• a second display mechanism for displaying residual battery capacity;
• a drive mechanism having a battery and a motor for driving the first and second display mechanisms;
• a motor speed detector for detecting a rotating speed of the motor;
• and a control circuit for calculating the residual battery life based on the detected rotating speed of the motor and comparison data representing a relationship between the detected rotating speed and the residual battery life.