Patent GB-758353-A (GB)
Title: Improvements in or relating to control of the iris aperture size in photographic cameras
IPC: G03B9/08
Filed: 1953-04-28
Abstract: 758,353. Iris diaphragm control. VINTEN, C., and VINTEN, Ltd., W. March 25, 1954 [April 28, 1953], No. 11774/53. Classes 97 (1) and 98 (1). An iris diaphragm electric control system for use in a photographic camera comprises an iris mechanism for varying the aperture size, a reversible electric motor for moving such iris mechanism, a series of aperture selection brushes arranged in spaced relationship and each corresponding to a desired aperture size, a pair of motor control brushes in spaced relationship to said series and each connected to a motor terminal, an arcuate commutating member divided into two insulated portions and arranged so as always to establish connections between a motor control brush and the aperture selection brushes corresponding to aperture sizes other than that momentarily occupied by the iris mechanism, and switch means arranged at a position remote from the iris mechanism and adapted to connect a source of electrical energy selectively to any one of said selection brushes, one of a pair of sets of parts consisting of the motor control and aperture selection brushes on the one hand and the commutating member on the other hand being stationary and the other set being connected to the iris mechanism to move therewith. As shown, the toothed wheel 79 on the iris ring 80 is driven through worm reduction gearing 78 by a reversible electric motor 77. The iris ring 80 carries a commutator 81 which rotates therewith and is divided into two semicircles by insulators 82, 83. A fixed cylindrical portion 90, extending forward from the lens cone 91, carries a set of four rings 92, 93, 94 and 95 which are rotatable on the cylinder 90 for purposes of presetting the required apertures and are thereafter locked by a clamp 110. The rings carry pairs of iris contacts 96, 97; 98, 99; 100, 101 and 102, 103 respectively, the contacts of each pair being arranged diametrically opposite each other on each ring. These iris contacts carry brushes which make contact with the commutator 81. The contacts 102, 103 are connected to the motor 77 and, in any position of the commutator, each makes contact with one segment of the commutator. The other contacts are connected to a remote control switch 84 which comprises two segments' 85, 86 which, in all positions are connected to a source 87 of D.C. The switch can be turned by the operator so that the projections on the segments 85, 86 can contact any of the pairs of contacts 104, 105; 106, 107 or 108, 109 at will. In the position shown in Fig. 4, the iris diaphragm is set for maximum aperture with the switch 84 on contacts 108, 109 and their corresponding contacts 100, 101 over the insulators 82, 83. If switch 84 is moved so that the segments 85, 86 are connected to contacts 106, 107, energy is supplied via contacts 98, 99 and the commutator segments to motor contacts 102, 103. The motor then rotates the diaphragm ring until the insulators 82, 83 come under the contacts 98, 99, when the current will be cut off. The diaphragm is now set at the second largest stop. If the switch 84 is now returned to its former position as shown in Fig. 4, current is supplied to the motor through contacts 100, 101 in the opposite direction and the diaphragm is opened again. Alternatively, if the switch 84 is moved so that segments 85, 86 are connected to contacts 104, 105, current is supplied to the motor through contacts 96, 97 and the diaphragm is closed further. In a modification, rings 92, 93 and 94 carry only one contact each and the switch 84 has only one segment. The other mains terminal is' connected direct to a middle contact on the motor, the two outer motor contacts being connected to brushes 102, 103 on ring 95 as before. The Provisional Specification refers to mechanical connections between the remote control and the camera, such as Bowden wires or hydraulic or pneumatic connections. Reference is also made to driving the iris through a ratchet mechanism to an extent dependent on the number of impulses received from a transmitter controlled by the operator. Specifications 758,354 and 758,378 are referred to.