| abstract |
1,203,357. Moulds for lenticular sheets. RLM RESEARCH CORP. 13 Dec., 1968, No. 59382/68. Heading B5A. A mould for forming a lenticular sheet for use in integral photography is produced in apparatus comprising upper and lower relatively movable platens 10, 12 between which is a pair of flat plates 14, 16, Fig. 2, a uniformly perforated metal sheet 22, 24 on the lower plate, a plurality of metal balls 26 of larger diameter than the perforations and less than the distance between them, each of the balls resting in one of the perforations, the plates being limited in relative movement so as to produce a sheet 28 of plastics resin uniformly embossed by the balls. The perforated metal sheet 22, 24 may comprise a copper layer 22 having a nickel layer 24 electrodeposited thereon, the perforations being of uniform size and in a regular pattern. The plastics resin is preferably a fluorocarbon resin and may be cemented to slab 16. The embossed sheet 28 may be used as a mould for a lenticular sheet formed, e.g. from a clear, curable liquid resin, e.g. a polyester of refractive index 1À56, by inverting the sheet 28 and slab 16 and placing them into further moulding apparatus, the other face of the mould 50, Fig. 6, being a heavy glass sheet. A reinforcing apertured metal sheet 40, 42 similar to sheet 22, 24 may be embedded in the lenticular sheet 56 which is produced by injecting the resin, e.g. polyester, e.g. in a plurality of stages to avoid shrink marks. |