Patent GB-190702485-A (GB)
Title: Improvements in or relating to Focal Plane Shutters or other Roller Blind Shutters for Photographic Purposes.
Inventor: ADAMS ARTHUR LEWIS
Filed: 1907-01-31
Granted: 1907-10-31
Abstract: 2485. Adams, A. L. Jan. 31. Shutters. - Relates to focal-plane .roller-blind shutters such as are described in Specifications No. 1332, A.D. 1902, No. 12,003, A.D. 1904, and No. 19,817, A.D. 1905, or other roller-blind shutters in which two blinds pass during either exposure or resetting from a closed position at one fixed point to a closed position at another fixed point independent of the size of the exposing aperture, the aperture being made on the release of the shutter by the lower blind travelling a distance equal to the exposing aperture before the upper blind starts its movement. According to the present invention, the two blinds are so connected during the exposure that it is impossible for the space between them to vary. The upper blind is attached to a top roller 1, Fig. 5, and is connected by tapes to a bottom spring roller 2. The lower blind is attached to a bottom spring roller 4, and is connected by tapes to a top roller 3. The rollers 1, 3 are geared by pinions g<1>, g<3>, and intermediate pinions IG<1>, Fig. 3, and IG<3>, Fig. 5, mounted on a common axis, to two toothed wheels G<1>, G<3> mounted on a common axis A. The upper blind is held in the " set" position by the engagement of a stud M on a pivoted catch N on the wheel G' with a fixed stop 0, Fig. 3, and the lower blind is held in the " set " position by the engagement of a stud j, Fig. 5, on the wheel IG<3> with a release trigger J. When this trigger is released, the lower blind first moves until a stud S3 carried by the wheel G<3> pushes back the catch N and comes against a stud S<2> fixed to the wheel G<1>. The two blinds with their accompanying gear wheels then travel together; and they are locked in definite relative position by the engagement of the stud S<3> between the stud S<2> and a spring catch P fixed to the wheel G<1> and adapted to rise behind the stud S<3>. When the lower blind has completed its travel, the parts are in the position shown in Fig. 5. In this position, the stud S<3> is liberated from the catch P, so that the upper blind can continue its movement until the stud S<2> on the wheel G<1> encounters a stud S<1> on the wheel G<3>. The liberation of the stud S<3> from the catch P may be effected by mounting the wheel G<3> on a screwed part B, Fig. 5a, of the spindle A so that the stud is carried out of reach of the catch by the screwing back of the wheel G<3>. Instead of the screw B being used, the stud S<1>, Fig. 5, may be arranged to effect the release of the stud S<3>. In order to provide for regulating the -exposure, the stud S<3> is fixed to a spring-pressed disk D, which can be shifted so as to place the stud S<3> in any one of a number of holes in the wheel G<3> at different distances from the stud S<1>. A pointer R indicates the adjustment. The shutter is re-set by turning back the wheels G3, G<1> by means of a milled head C. Any suitable means may be employed for effecting a prolonged exposure. According to the Provisional Specification, pneumatic means may be employed consisting of a dash-pot connected to the lower blind and arranged at a certain point to release the upper blind; or the dash pot may be combined with a spring and arranged to act on both of the blind releases at suitable intervals. One or more of the top toothed wheels of the blind mechanism may be connected to the dash-pot or any.of its parts, but preferably the dash-pot and its spring are not connected to the blind mechanism, but are arranged so that they are released simultaneously with the release of the lower blind and at a certain point of their travel cause the release of the upper blind.