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.