A new application of ferroelectric liquid crystals: fast electrooptic helmet visors for pulsed welding applications
Résumé
The use of automatically operating shutters for welding is since long a recognized application of liquid crystals with an important market. With the advent and success of the new pulsed welding technique the conventional welding helmets based on nematic liquid crystals are facing difficulties because the nematics are not responding fast enough to stroboscopically follow the changing intensity of the arc during pulsed welding. Ferroelectric liquid crystals (FLCs) here offer new possibilities. Our new FLC-based visor, with a switching time of about 200 microseconds, blocks the high light intensity during the sparks and opens the visor between pulse sparks. This new type of FLC visor thus significantly increases the visibility of the object under work compared to traditional nematic liquid crystal helmet visors, where the relaxation (several milliseconds) is too slow to open the visor between pulses