GB834448A - Improvements in and relating to optical projectors - Google Patents

Abstract

834,448. Optical-projection apparatus. PROJECTION OPTICS CO. Inc. Nov. 19, 1956 [June 21, 1956], No. 35276/56. Class 97(1) A projector comprises a projection head having two openings over which may be alternatively mounted a board carrying an adjustable lens, a plane reflector in the head providing a bent optical path between the openings, and support means for adjustably supporting said projection head on a light box having a source of artificial light for illuminating the object to be imaged. As shown in Fig. 6 the projection head comprises a casing, having a handle 106, secured to collars 40 sliding on columns 18. An external knob 48, Fig. 3, operates a shaft 45 which drives through helical gearing 47, 49. A shaft 51 which drives through worm gearing 53, 55 a transverse shaft 43 carrying pinions engaging racks 38 on the columns. The mirror 90 is pivoted at 92 and held by a spring 96 against an adjusting screw 94.The lower wall of the casing is formed by a panel 84 secured by fastenings 88 and carrying a mounting tube 76, with clamping device 82, for a lens 74. The front of the casing is closed by a transparent plate 102. The lens may alternatively be secured at the front of the casing, according to the focal length used and the range of focal lengths which can be accommodated may be increased by providing mounting panels with different mounting arrangements. Fig. 3 shows the projection head forming part of an episcopic projector. The supporting columns are carried in a base 116 the inclination of which may be adjusted by appropriately clamping by screws 142, downwardly urged spring plungers in tubes 138. A lamphouse 26 is carried on collars 22 and connected to the projection head by a bellows 32. The enlarged end of the lamphouse contains the lamp and concave reflector and other inclined reflectors surround an opening in the bottom of the lamphouse to direct light downwardly through it. An object may be held against this opening by a platform 126 carried on spring loaded links 128, 130. Cooling air from a blower 64 flows over the object, past the lamp out through louvres 72. A small pivotally mounted projector 145 projects a spot of light which may be used to indicate a desired point in the projected picture. In another arrangement the base 116 is dispensed with and the lamphouse 26 placed directly on the object to be projected. An alternative lamphouse for projecting transparent objects has a transparent illuminated upper surface.