Patent GB-229572-A (GB)
Title: Improvements in and relating to picture projectors
IPC: G03B1/22
Filed: 1924-07-30
Abstract: 229,572. Alexander, A. E., (Bray Screen Products, Inc.). July 30, 1924. Optical-projection apparatus. - Apparatus for projecting from a film strip comprises a lamp house which is supported on a standard and itself carries film delivering and receiving devices and a film guide having a hinged member carrying the projecting tube. As shown the lamp housed is pivotally mounted on a standard 11 and comprises two hemispherical portions 13, 14 hinged together, the portion 13 having a tubular lamp holder 24 extending at an angle to the optical axis so that adjustment of the lamp 12 therein varies its distance from the condenser 23. The portion 14 has a covered ventilating opening 19 and an axially adjustable reflector 21. A plate 26 forming part of the film guide is secured to projections 25 so as to be spaced from the lamp house and has pairs of flanges 27, 28 carrying spools 50. The plate 26 has an exposure aperture 29, and a plate 32, hinged at 34 to a lug 31 and held by a spring, has a corresponding aperture 36 covered by a piece of glass 37 which prevents the film from bulging. The plate 32 carries the lens tube 43 on lugs 45 and also fingers 40, 41 at its two upper corners and at one of the lower corners to hold the margins of the film against the plate 26. The other lower corner carries a shoe 42 of channel section which is pressed against the film by a spring 79 and covers a slot 73 in the plate 26 accommodating the claws of a feed arm 75. The upper spool is rotatably carried between the flanges 27 by a leaf spring 52 on one side carrying a projection entering the spool and by a spindle 54 on the other side having an operating knob 55. The lower spool is similarly carried by a spring 52 on one side, and on the other side by a spindle 57, Fig. 10, having a knob 58 and longitudinally movable within a sleeve 56 rotatably carried by the flange 28. A spring-pressed ball 59 engages one of two grooves in the spindle 57 to hold the spindle in or out of engagement with the spool, and a pin 63 on the spindle enters a recess in the sleeve 56 when the spindle engages the spool. A ratchet wheel 61 rotatable on the sleeve 56 is held friction tight by a spring 62 to form a friction clutch. The lower spool may thus be rotated positively by the knob 58 or through the friction cltuch by means of the ratchet wheel 61. The film is fed past the aperture 29 by the feed arm 75 which is pivoted to a strip 64, Figs. 2 and 7, slidably held on the plate 26 by pins 65 and slots and movable downwardly by a finger piece 66 against the action of a spring 67. The upper claw of the arm 75 engages the top of the slot 73 when the arm is in its uppermost position and causes the arm to turn against the action of a spring 77 and disengage the claws from the film. The strip 64 has a slotted lug 68 engaging a pin 69 on an arm 70 which is rotatable round the axis of the lower spool and carries a pawl engaging the ratchet wheel 61. The film is fed downwardly by pressing the finger piece 66 and may be rewound by turning the knob 55. In a modification, a toothed roller on a shaft having a cranked end is provided at the top of the plate 32 to enable the film to be fed upwardly, the roller &c. being additional to or replacing the fingers 40. Further, the spools may be dispensed with, the film being inserted as a loose coil in an upper receiver in the form of a cylinder having an opening adjacent to the plate 26. The film may be wound loosely into a similar lower receiver, and both receivers may have hinged covers provided with reinforcing rods at their free edges.