WELDING HELMET WITH HYBRID LENS SYSTEM AND LOW POWER CONSUMPTION CONTROL CIRCUIT THEREFOR

摘要

A lens assembly (24) and associated control circuit (30) which provide an auto-darkening feature for a welding helmet (20) is comprised of a twisted neumatic lens (26) and a surface mode lens (28), each of which are separately electrically actuated to achieve a user's preselected shade. The control circuit (30) has a preprogrammed microprocessor for controlling the actuation of the filters (26, 28), and has a control scheme that minimizes the power consumption of the lens assembly to prolong battery life. The control scheme includes actuating the higher energy using filter separately and for at least the darkest shade at a different frequency than the lower energy using filter. The digital control circuitry includes digital potentiometers to permit the microprocessor to run a calibration routine to set the shade settings for the actual filters used.