Low voltage battery indicator for a solid state watch
AssigneeTime Computer, Inc.
InventorsJohn M. Bergey, Arthur H. O'Connor
Life of this patent
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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.
Claims8
A solid state wristwatch comprising a source of constant frequency electrical signals, a frequency divider coupled to said source, an electro-optical digital display of light emitting diodes, a display actuator coupling said divider to said display, a battery, a manually operated demand switch for coupling said battery to said display when said display is to be energized, a low voltage circuit coupled to said display for indicating on said display when the battery is approaching the end of its useful life, means responsive to operation of said demand switch for coupling said battery to said low voltage circuit whereby said low voltage circuit draws energy from said battery only when said display is energized, said low voltage circuit comprising a band-gap voltage reference circuit for producing a reference voltage, and a comparator for comparing said reference voltage with a voltage from said battery.
Dependencies are inferred from the claim text.