Camera for intermittent observation of molten weld pool - where high speed camera shutter is formed by electro=optic ceramic disk made transparent by voltage pulses

摘要

During an arc welding process, a controllable welding transformer (6) is used for periodic interruption of the welding current. A camera is aligned on the molten weld pool, and has a shutter (12) which is synchronised with transformer (6). Shutter (12) is either an electro-optic ceramic disk, or a Kerr cell, the transparency of which is influenced by a voltage. The pref. appts. includes an electro-optic ceramic disk (12); and a phototransistor (13) used as an opto electric transducer is located between the weld pool and disk (12). The phototransistor (13) triggers a square-wave generator (15) which provides pulses making disk (12) transparent when the welding pulses provided by transformer (6) approach zero voltage. The invention improves and simplifies the camera appts. described in 2651878.