Patent GB-190108356-A (GB)
Title: Improvements in or relating to Photographic Shutters
Inventor: BOULT ALFRED JULIUS
Filed: 1901-04-23
Granted: 1901-07-06
Abstract: 8356. Boult, A. J., [Bausch & Lomb Optical Co.]. April 23. Shutters.-The shutter, which is adapted for instantaneous or time exposure, is enclosed in a casing consisting of a plate 1 provided with a central aperture, and having a rearwardly - extending rim 2 to which a cover-plate may be attached. The shutter may consist of two perforated leaves 4, 5, Fig. 2, pivoted at opposite ends to levers 7, which are pivoted upon a supporting-plate. To one of the levers is pivoted an arm 9 having attached to its free end a spring 11, which is carried around a disc 12 and is secured to a pin 13 on a pivoted device 14, by the rotation of which the shutters are operated. When the parts are in the position shown in Fig. 2, the shutter is closed. If then the device 14 is rotated so that the pin 13, Fig. 2, is moved to the left, the pin will depress the arm 9 without operating the shutter until it engages with a shoulder 15 on the arm. If, now, the device 14 is released. the pin 13 pushes the arm 9 to effect the exposure, and finally escapes from it into the position shown in Fig. 2. The device 14, Fig. 6, has a pin 16 with which a hook or shoulder on a pawl 20 engages to rotate the device. The pawl is pivoted to an arm 18, which is pivoted to the frame, and is operated by a pin 29 on a pivoted arm 28, which may be operated by a pneumatic piston 30. The arm 18 is also connected by a link 32 with a pivoted lever 33 having a finger extension 35, by which the shutter may be operated by hand instead of by the piston 30. The device 14 has, besides the pin 16, a pin 17 on which a nose 23 on the pawl 20 rides, Fig. 9, to disengage the pawl from the pin 16, thus permitting the return of the spring-actuated device 14. To regulate the time of exposure, a crank lever 41, Fig. 3, pivoted to a bridge 40 in front of the device 14, is connected at one end to a dashpot arrangement, consisting in the present case of two cylinders 42, 43, and the lever has a fork at the other end in which engages a pin 51 of an index 48, Fig. 5, which moves over an indicator giving the times of exposure &c. The pin is sufficiently long to engage in a hood or guide 45 on the device 14, so that, when the device 14 is actuated, the pin 51, and thus the lever 41 and dash-pot device, will be also actuated, the retardation due to the dash-pot depending on the leverage and on whether the pin 51 engages with the forked arm near the extreme end, or further down. To give a long exposure, which is terminated by actuating the finger-piece 35, or piston, a second time, or which continues while pressure is exerted on the operating bulb or handle, a pivoted detaining member 64 is used, having a point 62, a projection 63, and an inclined edge, one or other of which is adapted to engage with a nose 60 on the device 14 according to the position of the detaining member, the exposure continuing until the device 14 is completely freed from the detaining member. The detaining member is controlled by a pivoted arm 70, operated by the pin 51, and having an inclined edge 74, which normally engages with a projection 67 on the detaining member and holds it out of the path of the nose 60, and it is operated by a spring, and by a pin 37 on an extension of the lever 33, the pin engaging with a hook or shoulder 66 on the detaining member.