Patent ID: 8537294

Claim:
An automatic darkening filter apparatus comprising: a switchable shutter capable of assuming a dark state, a light state, and at least one intermediate state; and, a shutter control system operatively connected to the shutter and capable of detecting at least high input and low input and changes therebetween, wherein the shutter control system is configured to: switch the shutter from a dark state to an intermediate state if a change from high input to low input is detected; maintain the shutter in the intermediate state for a predetermined period of time T 1 of at least about 100 milliseconds if low input continues to be detected during period of time T 1 ; switch the shutter from the intermediate state to a light state at the end of period of time T 1 if low input is detected at the end of period of time T 1 ; switch the shutter to a dark state if a change from low input to high input is detected; maintain the shutter in the dark state if high input continues to be detected.