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Instruction of disabled men in motion picture projection, an elementary text book (1919)

Page scan 00029 from Instruction of disabled men in motion picture projection, an elementary text book

Record Details:

Title:
Instruction of disabled men in motion picture projection, an elementary text book
Date:
1919
Publisher:
New York, The Red cross institute for crippled and disabled men
Volume:
Instruction of disabled men in motion picture projection, an elementary text book
Leaf #:
00029
Language:
English
Subjects:
Motion picture projection, People with disabilities -- Rehabilitation
Collection:
Books
Format:
Books
Contributor:
University of California Libraries
Sponsor:
MSN
Coordinator:
Media History Digital Library
Date Added:
July 19, 2022
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14 MOTION PICTURE PROJECTION WORKING PRINCIPLE OF ELEMENTARY PROJECTION MACHINE By turning the operating crank A, counter clockwise, the main shaft J5, is driven through the 4 to 1 reduction chain drive D, a steady turning motion being caused by the fly wheel (7, this in turn operates the upper steady feed sprocket E, through the 4 to 1 reduction gear F, thus the teeth of E sprocket which mesh with the per- forations in the film, feed the film at a constant rate, the film being held against E by pressure roller G. A film loop or length of loose film is thus maintained between E and the steady drum H. The film is fed past the film gate intermittently by the intermittent sprocket I, operated by the Geneva movement K, the latter producing a quick quarter turn of /, followed by a relatively long rest during which the main shaft B makes one revolution. The barrel shutter Z, by a 2 to 1 gear with the main shaft and'proper timing, operates to cut off the light rays from the screen during each movement of the intermittent sprocket I, and to admit the light during the intervals that I remains stationary. The synchronous operation of the intermittent sprocket and the shutter is very clearly shown in the diagram. A lower steady feed sprocket M, which operates at the same speed as the upper sprocket E, maintains a lower feed film loop N, and feeds the film to the lower reel 0. Because of the increasing diameter of the roll of film due to winding the film on reel 0, the velocity of rota-