Patent GB-190815548-A (GB)
Title: Improvements in and connected with Photographic Shutters.
Inventor: WHITEHEAD FRANK PHILIP
Filed: 1908-07-22
Granted: 1909-07-22
Abstract: 15,548. Whitehead, F. P., and Giles, W. F., [trading as Whitehead & Co., F.]. July 22. Shutters.-Relates to improvements in the shutters described in Specifications No. 22,134, A.D. 1904, and No. 28,174, A.D. 1906. Two blinds are used. The blind rollers are normally disconnected and are geared together by intermediate gearing, carried on a movable piece, only when the shutter is in action. The winding-wheel is fitted with studs and stops for bulb exposures, one of the studs on the winding-wheel automatically positioning a movable stop when the shutter is wound up to a full aperture, which engages another stud on the winding-wheel in open position. One of the blinds may be arranged as a self-capping blind. Modifications are described in which this blind can be used alone ; or it may be used under a weak tension, just sufficient to return it to recover the shutter ; or the roller of the capping-blind may be automatically disengaged from the spring roller of the second blind as soon as it has uncovered the exposure aperture. In one modification, the intermediate wheel E, Fig. 1, is mounted on a plate F turning on the same axis as the roller D carrying the eapping-blind. The wheel E is normally disconnected from the spring roller C carrying the second blind, thereby allowing the capping-blind to be drawn up by a spring on the roller A. A pawl can be fitted to engage the wheel E to hold the blind for exposure. The winding-wheel K winds the upper roller B of the sbutter blind to give an adjustable slit. When the slit equals the full aperture, the pin N comes in contact with the outside curved end P<3> of the lever P, and tilts it to the dotted position where it is held by a pin p<7> which springs over a fixed pin P<6>. In this position the lever P catches a second pin O for a bulb exposure. The shutter is released by tilting the lever H, which first actuates the plate F and puts the rollers C, D in gear, and then releases the pawl M. A spring I tends to release the lever Hand disconnect the roller E. The e capping-blind is then drawn up by the spring in the roller A to close the aperture. In a modified construction, Fig. 3, there is a train of gearing between the winding-wteel K and the roller B, and a sliding plate P is used. The intermediate wheel E, mounted on the plate F, turns about the roller C. A release lever M engages a ratchet-wheel on the roller B. For bulb exposures, the wheel K is wound until there is a full aperture between the blinds; the pin N then engages under the stop P<3> and raises the plate P, thereby putting a stop O<1> in the path of another stop O on the wheel K. To release the shutter, the plate F is tilted over by moving a pin F', which puts the rollers C, D into gear, and moves a pin F3 under a ledge p<3> of the plate P to hold it in its raised position before the slotted release lever T is raised sufficiently far to release the retaining pawl M. In order to allow the capping-blind to be used by itself, a winding-drum F, Fig. 9. is fitted on the intermediate wheel E, and the blind is drawn down by a cord G, a pivoted lever H, and a pneumatic teat. Or, alternatively, with the construction illustrated in Fig. 3, a spring gear-wheel G, Fig. 6, is mounted on an angle-lever B. The spring is wound-up by the winding-key I, and is held by the friction between the centre stud A and the arm B. The wheel G engages the roller D just as it is released from the retaining-pawl F. When it is desired to keep the capping-blind only under weak tension, just sufficient to draw it back to close the aperture, additional gearing A', A, Fig. 10, is fitted between the roller A and the winding- roller K, and is mounted on a pivoted angle-lever S<1>. The wheels are normally kept in gear by the spring M<2>, and are disengaged by the lever S<2> before the wheel K is released from the retaining-pawl. In another modification for shortening the tapes of the capping-blind, the capping-roller D, Fig. 8, is automatically disengaged as soon as the capping- blind uncovers the aperture. The spindle D<1> of the gear is mounted in the bushes V, V<1> of the roller and can slide transversely. The end D<2> screws into a fixed bearing D<3>, the screws being adjusted so that as the roller runs down, the wheel D is moved outwards sufficiently to disengage from the connecting-wheel E. According to Provisional Specification, instead of mounting the spring for the capping-blind in the roller A, the tapes of the capping-blind may pass over a small jockey roller to a spring roller in another part of the camera or casing.