Abstract: Disclosed is a solid state wristwatch having a digital light emitting diode display and a low battery voltage circuit for actuating the display to indicate the approach of battery failure. The battery voltage sensing circuit draws power only when the display is energized and causes one of the display stations to blink. It comprises a silicon band gap reference voltage circuit for comparing the battery voltage with a reference voltage that is independent of temperature and battery voltage variations.

Abstract: Disclosed is a solid state wristwatch having an active electro-optical display in the form of light emitting diodes. The display is mounted on one sloping side of a groove in a circular module frame and comprises a ceramic substrate having the display on one side and a large scale integrated circuit on the other. The angular orientation of the display coincides with the axis of an angularly oriented viewing window constructed so that the watch case shades at least part of the display. Viewing under bright daylight is enhanced and through ambient light responsive control of current to the display, battery energy under most viewing conditions is conserved.