What Does Automatic Darkening Welding Filter Mean?
An automatic darkening welding filter contains a shutter module that is operated electronically. This module contains ultraviolet (UV) and infra red (IR) filters. The UV and IR filters do not need electricity to operate. The liquid crystal light valve, though, is operated electrically.
Safeopedia Explains Automatic Darkening Welding Filter
The liquid crystal (LC) light valve is operated electrically. When the voltage is applied, the crystals re-orient themselves, which are separated by two separate sheets of glass. When the bright light from the welding operation strikes the light valve, the control module darkens the LC valve shutter. The liquid crystal is not sensitive to light itself, and it does not change the shade independently. It depends on the control circuit to change the tint of it.