GB385761A - Improvements in color screen control - Google Patents

Abstract

385,761. Lantern screens. KLIEGL, J. H., 321, West 50th Street, New York, U.S.A. Jan. 22, 1932, No. 1971. [Class 75 (iv).] Colour screens for use with spot lights are moved into their operative positions by a control mechanism comprising magnetic control apparatus, which, when energized, moves the screen against the action of a spring. The action is such that the initial moving force is considerably greater than the maximum resistance encountered, and the screen is thereafter moved to its operative position by a smaller force. A series of screens 14 is mounted each on a concentric shaft 18, 20, 22, 24, and normally held in inoperative position by torque springs 42 and counterweights 28. The plungers 32 of four solenoids 30 are connected by links 34 to crank arms 36, one on each concentric shaft. The circuit is shown diagrammatically in Fig. 6. Each shaft carries a non- conducting collar 46 with conducting sections 50 out of contact with each other. When it is desired to move a screen into its operative position, the corresponding contact 54 is closed by depressing a key 52. The greater part of the current from a source 56 passes through a conductor 58, solenoid 30, spring blade 66, section 50, blade 68, and conductor 70, a smaller part passing through a conductor 60 and resistance 62. The solenoid plunger moves and begins to rotate its appropriate shaft, whentherotation has proceeded sufficiently for the section 50 to be in contact with one only of the spring blades, the loop 70 is cut out and, owing to the resistance 62, a reduced current passes through the solenoid. The effect is that the movement of the screen is started vigorously and continued gently. Padded rods to act as buffers for the screens are disposed at the limits of their movement.