Patent ID: 8599323

Claim:
An apparatus for annunciating low-voltage in a battery supplying electricity to an auto-darkening optical filter system ( 10 ) for a welding helmet (not shown), the auto-darkening optical filter system ( 10 ) comprising: an optical band-pass filter ( 110 ); an LCD shutter ( 210 ) in series with the band-pass filter ( 110 ); a cover glass ( 410 ) covering the LCD shutter ( 210 ) and the band-pass filter ( 110 ); an optical sensor ( 510 ) for detecting light intensity proximate the cover glass ( 410 ); an LCD driver ( 310 ) electrically connected to the optical sensor ( 510 ) and the LCD shutter ( 210 ) and operable to apply a variable shuttering voltage to the LCD shutter ( 210 ) to cause the LCD shutter ( 210 ) to increase its opacity in response to increasing light intensity detected by the optical sensor ( 510 ); and battery terminals ( 305 ) adapted to electrically connect the battery to power the LCD driver ( 310 ); and characterized by: a low-voltage detection module ( 320 ) operable to generate a warning signal in response to detecting low-voltage at the battery terminals ( 305 ); and a low-voltage annunciation module ( 330 ), operable to announce a battery low-voltage condition in response to the warning signal by applying an annunciating voltage to the LCD shutter ( 210 ) to cause the LCD shutter ( 210 ) to change its opacity.