GB721699A - Improvements relating to screen holders for photo-lithographic equipment - Google Patents

Abstract

721,699. Photomechanical half-tone or line screen holders. PICTORIAL MACHINERY, Ltd. March 30, 1953 [April 22, 1952], No. 10145/52. Class 98 (2). An upright frame carries rollers peripherally grooved so as to hold a rectangular or a circular screen and permit rotation of the latter, the rollers being mounted for relative movement therebetween in the plane of the frame for adjustment of their spacing so that they can accommodate screens of different sizes. In Fig. 1, the frame 11 with side members 12, 13 and cross members 14, 15 is bridged by horizontal bars 16, 17 of which the latter is adjustable downwardly and the former upwardly in vertical channels 43 shown in dotted lines in the side members 12, 13 ; bar 17 being provided with clamping nuts 55, and bar 16 with plungers shown at 48, to engage notches 49 in the lower parts of the channels 43, for the purpose of retention of the bars in adjusted positions. The rollers 32 are mounted on slides 18 slidable along the bars 16, 17 and provided with clamp" ing screws 24, the rollers having circumferential grooves with a channel portion to accommodate the corresponding bending of a square screen and which channel portion terminates in a V-recess to accommodate the corresponding V-shaped binding of a circular screen, which screens are shown, respectively, in chain lines 56, 57. Figs. 2-9 (not shown), illustrate details concerning clamping of the bars 16, 17 in the channels 43, attachment of the rollers to the slides 18 and clamping of the latter on the bars, and the fitting of the two types of screens, square and circular, into the grooves of the rollers. The frame may carry an arrow or other form of marker for cooperation with angular markings at the rim of the circular screen so as to set the latter to give the required screen angles,