Welder's protective helmet light screen - has electromagnetic control for two relatively movable grid supports in visor area

摘要

A mask or helmet for welding or cutting operations comprises a visor with an area with two relatively adjustable grid supports (66, 67) movement of which is controlled electromagnetically according to light intensity and/or the type of light, for darkening or rendering transparent at least parts of the visor. The grid supports consist of visible light-transmitting material, and the darkening areas (grid strips) consist of visible light-absorbing material. In the visor region there are photoelectric elements producing a signal according to light intensity for controlling a circuit for actuating electromagnetic control elements. A test circuit is used to produce pulses which allow discrimination between standby and non-standby conditions of the control circuit.