1430183-A is referenced by 13 patents.
1430183 Automatic control of light intensity welding masks AGA A B 15 March 1973 [27 March 1972] 12605/73 Headings G2J and G3R The intensity of light passing through a variable light transmitting region is regulated to a desired level by a control circuit including a photo-electric element, detecting the light passing through the region, and an oscillator responsive to the element to vary the voltage applied to the region and thus vary the transmission characteristics of that region. The oscillator may include a transistor 10 with multicoil transformer 9 or an operational amplifier with associated resistive-capacitive components. The region 8, e.g. a liquid crystal or a depolarizer with crossed polarizers, may be used in a protective welding screen, goggles or helmet.