GB476436A - Improvements in or relating to means for discharging electricity from materials and mechanism - Google Patents

Abstract

476,436. Discharging electricity from fabrics &c. CHADFIELD, C. R. A. June 8, 1936, Nos. 16028 and 16029. Divided application. [Class 35] [Also in Group XL] An apparatus for discharging electricity from materials or machinery comprises a casing 33 having an air inlet 38 and an outlet 37 with means, e.g. an electrically driven fan 40, for causing a stream of air to flow through the casing and containing a spark gap 41a having zinc or cadmium electrodes 41 for ionizing the air included in an electric circuit through which flows a high-frequency high-potential alternating current. The casing, which is portable, contains a transformer or induction coil 34, the secondary winding of which is shunted by a low-value capacity 42 of about À002 microfarad and connected to the electrodes in series with a low-value inductance, e.g. a single turn of copper tape 43. A grid 49 within the outlet may be biassed so that only positively or negatively charged particles can emerge, and the biassing potential may be derived from a rectifier fed from an auxiliary secondary winding on the transformer. In a modification, for de - electrifying photographic apparatus mounted on an aircraft, the camera is contained in a casing through which air from the ionizing apparatus is conducted. The air flow is obtained by the use of a funnel open in the direction of travel of the aircraft or the funnel may be replaced by a pump or fan driven by a wind motor ; alternatively, the pump may be arranged at the outlet of the camera housing to draw air through the system. The air pipes are preferably coiled to act as light baffles and the air entering the casing 33 may be filtered.