Patent GB-425322-A (GB)
Title: A change-over, masking and colour-flooding device for use in conjunction with optical projectors
IPC: G03B21/50
Filed: 1933-09-27
Abstract: 425,322. Kinematograph projection. CRICKS, R. H., 159, Wardour Street, London. Sept. 27, 1933, No. 26586. [Class 97 (i)] Pairs of coupled shutters sliding horizontally are provided in front of each of two or more projectors and may be used for effecting change-over, or for preventing the projection of images on to screen curtains, their speed of movement being variable to secure approximately synchronous movement with the curtains ; the shutters may also permit the use of rotatable colour screens in one projector to colour the image projected by another projector. Each pair of shutters may be movable between horizontal slides 3A, 3B on a housing 1 to cover an aperture 5 therein, and each housing may be adjustably mounted by means of bent rods 57 over a port in the projection room in front of each projector. Pins 6, 7 on the shutters project through slots 1<A>, 1B in the housing, and engage arms 8, 9, which are mounted on pivots 10, 11 and are connected by a link 12 to a lever 13 pivoted at 14 and movable by a knob 15 to open and close the shutters. The shutter may be moved, alternatively, and at a variable speed, by an electric or spring motor through a wheel 23 carrying a pin 23<A> connected by a link 22 with the lever 13. The motor drives a gear meshing with a gear 27, Fig. 4, on a shaft 26 carrying a gear 25 slidable into mesh with the gear 23. The gear 25 is moved by a slider 30 on a spindle 37 movable axially against the action of a spring by manual pressure on a button 29. The spindle 37 has a groove 37B engaged, when the gears are in mesh, by a spring-turned pivoted arm 35, Fig. 2, to hold the spindle in position, and the arm 35 has a tail which is engaged by one of two pins 38A on the wheel 23, when the wheel has rotated sufficiently to open or close the shutters ; such engagement trips the arm 35, releases the spindle 37, and breaks the driving connection to the shutters. A brake lever for the motor is engaged and operated by the button 29, and means is provided for preventing the wheel 23 from resting in a dead centre position. A Bowden wire 18 connects the levers 13 associated with each projector, and ensures that, for change-over, one pair of shutters opens as the other closes. The motor may embody a speed regulating device enabling the speed of movement of the shutters to be adjusted to approximate to that necessary to prevent projection on to the screen curtains as they open or close at the beginning or end of the film run. Sector-shaped colour screen holders 42, 43, both normally hanging from a spindle 45 so as to free the aperture 5, carry sectors of various colours, and extend over angles such that they may form a complete circle with overlap ; they may be rotated in front of one projector while a title, &c., is being shown by the other projector. The holders 42, 43 are respectively secured to a flange 44, Fig. 5, fixed to the spindle 45, and to a flange 46 fixed to a sleeve 47 loose on the spindle, and are rotatable from the shaft 26 by a sliding gear 51 and gears 50, 53. A spindle 54 movable axially against the action of a spring by manual pressure on a button 52 carries a slider 59 which moves the gear 51. The gear 50 is completely toothed so that the holder 42 begins to rotate when the button is first pressed, but the gear 53 has teeth cut away to prevent rotations of the holder 43 until projections 44, 46A, on the flanges come into engagement ; this engagement occurs when the holders extend over a complete circle, and the movement of the holder 43, initiated by it, is continued through the gear 53 when its teeth engage the gear 51. The spindle 54 moves through the large end of a key-hole slot 20B in an arm 20 pivoted at 20<A> normally preventing its movement, and a groove 54<A> therein, when the gears 51, 50 are in mesh, permits turning of the arm 20 about its pivot ; the Bowden wire 18 passes over a pulley 19 on the arm 20. When the gears 50, 51 are in mesh, the knob 15 may be depressed to open the shutters, such movement being permitted, although the shutters of the other projector are also open, by rotation of the arm 20 under the pull of the wire 18. When the knob 15 is raised to close the shutters and terminate the projection through the colour screens, the arm 20 resumes its normal position under the pull of a spring 21, thus freeing the spindle 54, stopping the rotation of the shutters, and permitting their return to their normal positions. Means for inserting a long focus positive or negative lens or a mask in the beam may be provided.