Patent GB-1414089-A (GB)
Title: Camera shutter mechanism
IPC: G03B9/14
Filed: 1973-07-04
Abstract: 1414089 Camera shutter mechanism SEIKO KOKI KK 4 July 1973 [4 July 1972]  31819/73 Heading G2A A camera shutter mechanism comprises a blade operating lever (1) which is rotatable between open and closed positions, a holding lever (4), the blade operating lever and holding lever being mounted for rotation about a first pivot (3), a driving member (5) which is mounted on the blade operating lever for rotation about a second pivot (la) which is spaced from the first pivot, an abutment member (6), the driving member having a first abutment portion (5b) which is engageable with the holding lever, and a second abutment portion (5c) which is engageable with the abutment member, releasable retaining means (preferably comprising an electromagnet (10), for releasably retaining the holding lever in a position in which there is engagement between the first abutment portion and the holding lever, setting means (11) for moving the driving member into and releasably holding it in a set position, and resilient means (8) which urge the driving member to move from the set position and in a blade opening direction, the arrangement being such that when the holding lever is held by the retaining means, and the driving member is moved in the blade opening direction by the resilient means, the driving member is pivoted about the first abutment portion so as to move the second pivot and hence the blade operating lever into the open position, and when the holding lever is thereafter released by the retaining means, the driving member is pivoted about the second abutment portion so as to move the second pivot and hence the blade operating lever into the closed position, the first pivot, first abutment portion, second pivot, and abutment member being momentarily successively arranged on a straight line during opening and closing movement of the blade operating lever.  The mechanism is set by moving arm (11a) of setting lever (11) by setting means (not shown) to effect clockwise rotation of setting lever (11) about pivot (12) and because of engagement between arm (11b) and abutment pin (5a) the clockwise rotation causes counter-clockwise rotation of driving member (5) about pivot (la), tensioning spring (8), until abutment pin (5b) contacts cam surface (4c), see Fig. 2, causing holding lever (4) to rotate clockwise about pivot (3) and thus move movable magnetic part (9) into contact with electromagnet (10). The movement of driving member (5) brings its abutment projection (5c) into engagement with arm (17) of release lever (15) so that the latter holds driving member (5) in the set state. To effect an exposure release lever (15) is manually released from driving member (5) by moving lever (15) clockwise enabling driving member (5) to be rapidly rotated clockwise about pivot (la) by spring (8) and causing energization of electromagnet (10) so that movable magnetic part (9) is attracted thereto. Consequently, rotation of driving member (5) is stopped once abutment pin (5b) contacts abutment surface (4b) and driving member (5) rotates clockwise, about 5b-4b engagement as fulcrum, with respect to pivot (3), causing pivot (la) to move from the upper end of slot (16) to the lower end thereof and corresponding pivotal movement of blade operating lever (1) about pivot (3). Pin (1b) moves from the upper ends of slots (2b) to the lower ends thereof whereby shutter blades (2) move into the fully open position, Fig. 3 (not shown). The aperture (2a) is closed when current ceases to flow through coil (10a) de-energizing electromagnet (10) which no longer attracts part (9), driving member (5) rotates clockwise under spring (8) using engagement of projection (5c) and pin (6) as fulcrum, abutment pin (5b) forces abutment surface (4b) to move counter-clockwise moving part (9) away from electromagnet (10) and disposing driving member (5) as in Fig. 1 (not shown) which moves pivot (1a) to the upper end of slot (16) and pin (1b) to the upper ends of slots (2b) to close shutter blades (2), see Fig. 1. (not shown).