GB1432727A - Shutter system for a motion picture camera - Google Patents

Abstract

1432727 Cinematographic shutters ELMO CO Ltd 5 Feb 1974 [6 Feb 1973] 05331/74 Heading G2E A shutter system for a cine camera comprises three sector blades driven in synchronism about a common axis, each adjacent pair of blades being coupled by a lost-motion device to permit limited relative angular displacement, the driving means comprising a motor connected to the first blade by a fixed gear train and to the third blade by a gear train including a cog capable of planetary motion about a second cog, the angular displacement between the blades being caused by a lever producing this planetary motion. The shutter drive is transmitted from a motor 14 through gear wheels 15 to 19'to a wheel 12 integral with the third blade 5 and through gear wheels 15, 16 to a wheel 13 connected to the boss 3. The transmission ratios are the same therefore wheels 12 and 13, and hence blades 1 and 5 are rotated at the same speed. When the shutter aperture is at a maximum, Fig. 1, blade 4 is driven due to a tab 8 thereon engaging a tab 6 on blade 1. To close the aperture e.g. for fade-out filming, a control lever 20, which is connected to the shafts of gear wheels 18, 19 by link work, is rotated about shaft 2 and moves wheels 18, 19, relative to wheels 12, 21 causing wheel 12 to rotate relative to wheel 13 without interrupting the gear train from motor 14. Blade 5 thus rotates clockwise relative to blades 1 and 4 until a tab 10 on blade 5 engages tab 9 on blade 4 causing blade 4 to rotate relative to blade 1 until finally tab 8 on blade 4 engages tab 7 on blade 1 when the shutter is fully closed. For fade-in filming the above process is simply reversed. In an alternative embodiment the blades entrain each other by pin and slot connections.