Abstract: A timepiece has movable indicator hands for the analog display of current time. An ambient state, such as ambient light intensity, presence of a person in a room, or infrared radiation is sensed. Whether or not time indication is necessary is determined depending on the ambient state. If it is determined that the ambient state indicates that time indication is not necessary, then the movement of the indicator hands is stopped to conserve energy and reduce noise. When the ambient state indicates that time indication is necessary, the position of the indicator hands is adjusted from a stop position to a position indicative of current time.

Abstract: An alarm clock has an ambient light detector for controlling the illumination of a time displaying section. An alarm time which is selected by a user is stored in a memory. An alarm set switch is used to switch between alarm-on and alarm-off conditions. A photosensor detects the ambient light surrounding the alarm clock. The illumination of the displaying section is controlled so that the displaying section is illuminated only when the current time is within a predetermined time zone before the alarm time set by the user, the alarm set switch is in the alarm-on condition and the detected ambient light is below a predetermined level. The illumination of the displaying section is also controlled so that the display is illuminated while an alarm sound is being generated.