GB856798A - Improvements in or relating to slide mountings for pre-mounted transparencies - Google Patents

Abstract

856,798. Transparency mounts. PERROT, A. July 31, 1959 [May 1, 1959], No. 26286/59. Class 98(2) A slide mounting for a framed transparency 1 consists of two transparent plates 7, 11 which fit together with the transparency between them, the first plate 7 having a first recess 8 which receives the transparency, and a second recess 9 centrally of the first recess so that a flange 10 is formed between the two recesses; the second plate 11 has a raised portion 13 forming a flange corresponding to the flange 10, so that in the assembled position the transparency itself is gripped between the two flanges only. The transparency 1 is held marginally in cardboard frames 2, 3, which in the assembled position (Fig. 4) are firmly held in recessed portions of plates 7, 11, which are made of transparent plastic. The flanges 10, 13 on the respective lower and upper plates 7, 11 are rectangular, and grip the actual transparency 1 firmly round a narrow peripheral portion only. The small clearance between the transparency 1 and the plates 7, 11 allows slight movement of the transparency without impairing the sharpness of the projected image, and avoids the formation of Newton's rings or other interference patterns. The assembly is finally enclosed in a pair of tray-shaped metallic masks 19, 20, which may be fixed in position by the apparatus described in Specification 773,114