Abstract: A protective welding lens assembly for use as the eyepiece of a welding helmet. The lens assembly utilizes a liquid crystal light shutter together with an electrical circuit adapted to change the light shutter from a uniform light-transmitting condition to a uniform, approximately opaque condition of very small light transmission solely in response to light energy emitted by an electric welding arc without the use of any connecting wires. Two light sensing devices are employed, one of which responds to visible light only and the other of which responds to infrared wave energy only. In order to change the light shutter from a light-transmitting to an opaque condition, both the visible and infrared wave energies from the arc must be sensed. This prevents a condition wherein the light shutter will remain opaque, even after the welding arc is extinguished, due to emission of infrared wave energy from a still-hot weld bead.

Abstract: A liquid crystal welding lens assembly for use as the eyepiece of a welding helmet in which the light transmission of the lens assembly is no greater than 0.01% during the existence of a welding arc. This is achieved with the use of at least two liquid crystal light shutters and three polarizers alternately arranged in tandem.