Microprocessor based automatically dimmable eye protection device with interruption prevention

Abstract

An auto darkening eye protection device comprising a shutter assembly adjustable between a clear state and a dark state and a control circuit. The control circuit is provided with a microcontroller, a delivery circuit, a sensing circuit and a weld detect circuit. The microcontroller is switchable between a sleep mode and a wake-up mode. The delivery circuit outputs a dark state drive signal to the shutter assembly to switch the shutter assembly from the clear state to the dark state upon enablement of the delivery circuit. The sensing circuit senses the occurrence of a welding arc and provides an output indicative of the occurrence of the welding arc. The weld detect circuit receives the output of the sensing circuit. The weld detect circuit enables a dark state drive signal to be delivered to the shutter assembly by the delivery circuit, and a signal to be delivered to the microcontroller to switch the microcontroller from the sleep mode to the wake-up mode whereby the shutter assembly is switched to the dark state without the aid of the microcontroller. The microcontroller can compensate for a startup of the microcontroller which was not caused by user power-up by bypassing at least one of a plurality of initialization and calibration routines for the auto darkening eye protection device. The microcontroller also includes a protective casing disposed generally thereabout to substantially prevent electromagnetic fields from interfering with the operation of the microcontroller.