GB616874A - Improvements in or relating to optical apparatus for the projection of transparent documents - Google Patents

Abstract

616,874. Optical-projection apparatus. STANDARD TELEPHONES & CABLES, Ltd. March 15, 1946, No. 8189. Convention date, June 8, 1943. [Class 97 (i)] Transparent documents which may be in the form of kinematograph films are projected by an apparatus which comprises an apertured housing containing a stationary light source, and a unit, rotatable on the housing, which comprises a document carrier slidable at rightangles to the axis of rotation of the unit and an optical system, the axis of which coincides with the axis of rotation of the unit and passes through the housing aperture and the light source, comprising a condensing lens in or over the housing aperture and between the light source and the document carrier and a focusing lens on its side of the carrier and remote from the condensing lens. As shown in Fig. 4, a housing 23 is apertured at 39 and 41 and contains a lamp 36 carried on the housing by a socket 34 which is mounted for rotational and axial adjustment on a pin 33 and below which is disposed a reflector 35. Light from the lamp passes through a condenser 29 which is carried by a disc 25 rotatably mounted about the axis of the condenser in the grooves of four pulleys 26 on the housing 23. An arm 30 on the disc supports a lens 31 with its axis coinciding with that of the condenser 29, while a plate 27 is held on the disc with its centre line parallel to a diameter thereof. Slidable on this plate is a carriage 19 which may be located in any one position thereon by notches with which a spring catch co-operates. Grooves 17, 18 in the carriage 19 slidably accommodate a carrier for a film. This carrier comprises a centrally apertured platen 1, Fig. 3, supporting a frame 2 bearing a shaft 8 for a transparent plate 6 which in its closed position presses the film onto another transparent plate clamped on the platen 1, a catch 11 serving to keep the plates in their correct position; the rim 14 of the platen 1 is notched so that a spring latch on the carriage 19 may serve to hold the carrier in the desired position. A film holder for use with a roll film and slidable in carriage 19 is also described, the film holder comprising wind-off and take-up spools mounted on either side of two glass plates between which the film is threaded, spring pressure being applied to the upper plate. A mirror may be mounted above the lens 31 to reflect the light onto a screen, which may be formed within a hinged lid for the apparatus. In the Specification as open to inspection under Sect. 91 abutments are arranged to prevent the carrier from sliding off the carriage 19 and also to prevent the latter from sliding off the plate 27. This subject-matter does not appear in the Specification as accepted.