Abstract:
A power supply circuit (14) for a liquid crystal welding lens (10) or shutter develops a relatively low voltage AC signal for driving or powering the liquid crystal shutter (10) to the clear state and two relatively higher or larger magnitude AC electrical signals for initially driving the shutter (10) to the dark state and then for maintaining the shutter (10) in the dark state; a variable frequency circuit (61) for varying the frequency of the driving signal to the shutter (10) to minimize power usage in the dark state and to avoid flicker in the clear state; and power saving and battery level indicator features are included.
Abstract:
A welding helmet includes a shield (2) and a lens (5) which has both a rapid driven to dark state during which eye (10) protection is provided during welding, a clear state during which maximum clarity is provided for viewing through the lens (5) when welding is not occurring, and a fail state that provides a dark condition for eye (10) protection, for example, if lens power were to fail during welding.
Abstract:
A welding helmet (60) includes a shield (62) and a lens (68) including a first polarizer (14') and a first analyzer (16') in optical series having transmissive axes oriented substantially operationally orthogonal to one another; and, a second polarizer (14'') and a second analyzer (16'') in optical series having transmissive axes oriented substantially operationally orthogonal to one another; the second polarizer (14'') and the first analyzer (16') being in optical series and having their transmissive axes oriented substantially at 45 degrees to one another to improve extinction of light incident on said lens (68) at all angles.
Abstract:
A sensor circuit (18) for detecting light hazards or bright light sources that will cause discomfort. The sensor circuit (18) includes a pair of detector circuits (200, 201), each of which includes a sensitivity feedback circuit (221) an a comparator circuit (22), which are electrically connected together via lines (202, 203) to inputs of a NAND gate (204). The sensor and sensor electronics provide a wide sensitivity range, which is fully automatically adjustable, and which has the ability to detect points source of light. The sensor further has the ability to distinguish low power stable light generated from a small welding arc from bright ambient light or even direct sunlight.