GB697999A - Improvements in or relating to apparatus for coating tubular fluorescent lamps - Google Patents

Abstract

<PICT:0697999/III/1> Apparatus for coating the interior of tubular electric discharge lamp envelopes with fluorescent material suspended in a liquid, comprises means for holding a tubular envelope inclined both to the horizontal and vertical, means for introducing a quantity of the suspension into the higher end of the tube, and means for rotating the tube about its axis whilst the suspension flows down the tube. Tubes 1 are carried on a continuously moving conveyer 2 consisting of two endless belts 3 carrying between them a plurality of vertical wooden battens 4, having metal brackets 7 on which the lower ends of the tubes rest, and spring clips 8 which grip the tubes near their top ends. At the coating stage the top of a tube is withdrawn from the clip 8 and the tube laid on rubber rollers 11, one of which is driven by a motor (not shown). A third roller 12 is lowered about a pivot rod 15 to hold the tube in position, and the tube rotated about its axis. Coating suspension is contained in a constant head reservoir 9, to which it is fed by a pump as described in Specification 697,998. A valve is opened for a suitable time to allow the suspension to flow through a flexible pipe 10 and a discharge tube 16 into the rotating tube 1, which is thus evenly coated. Excess suspension drains into a trough 5. As the coating proceeds the rollers supporting the tube 1 and the discharge tube 16 move with the conveyer. When the coating is completed the flow of suspension stops, the tube is stopped rotating, the roller 12 is raised, and the tube replaced in the vertical position in the conveyer. The rollers and the discharge tube 16 then return to their original position. The operations may be performed mechanically or manually.