Mercury vapour HV discharge lamp - is of cold cathode type and gives blue light for use in aerodrome approach lighting

摘要

An electrical high voltage discharge lamp emits coloured light which complies with the requirements of aerodrome approach lighting. It avoids the use of filament lamps with filters to give the required blue light. The lamp, has a tubular glass envelope (1) with a fluorescent powder layer (3) on the inside face. It has a mercury liquid drop (4) and cold cathode discharge electrodes (2,2'). The lamp is filled with neon gas before sealing of the tail (6). The neon gas is at a pressure of 4 to 10 torr. The lamp may be straight or curved.