Patent GB-650245-A (GB)
Title: Electromechanical code translating apparatus
IPC: H03M5/00
Filed: 1948-11-02
Abstract: 650,245. Automatic exchange equipment. WESTERN ELECTRIC CO., Inc. Nov. 2, 1948, No. 28414. Convention date, Nov. 4, 1947. [Class 40 (iv)] [Also in Group XL (b)] A code translator such as is used to effect interconnection between different automatic telephone exchanges, comprises a stack of perforated cards having marginal projections whereby they may be selectively displaced to provide a distinctive pattern of openings through which light is projected on to the sensitive elements arranged behind the perforations. In the described embodiment twenty input circuits are arranged in four groups of five for operation on a two-out-of-five system for translating to seventy-five output circuits. Each card such as 61 is provided with a group of standard perforations 59 and a distinctive group of elongated perforations 185, Fig. 9, so that when a selected card is displaced downwardly, all the normally aligned perforations except those corresponding to the elongated perforations are blocked by the opaque portions of the selected card. Light from a source 40 (Fig. 1) is directed through all the perforations and a number of photo-cells 147 are aligned with the standard perforations to detect light passing through the distinctive perforations in the selected card. The cards are made of magnetic material and supported in the stack by vertically-movable code bars 105 engaging the eight marginal projections, two such as 88, 90 co-operating with each group of five code bars. Electromagnets 37 below the assembly cause the projections to adhere to the code bars and induce like poles along the edges of the cards so that electromagnetic repulsion provides an operating clearance, thereby facilitating the displacement of a selected card. Further electromagnets 38 with slidable polepieces 117 above the stack assist in return of the cards to normal position and removal of a selected card as described hereafter. The code bars are normally held up by saw-tooth cams 109 on spring-biassed selector bars, e.g. 100b, which are movable by electromagnets, e.g. 10b, to allow the code bars to drep. This movement also operates contacts 18 .. 21. The magnets and contacts are shown in their actual position at the lower right-hand side of Fig. 1, and also schematically in the circuit at the top of Fig. 1. Normal operation (two-out-of-five system). When a four-figure code is received the sender (not shown) will ground two out of each group of five lines to energize two relays 10 . . . 13 in each group. Assume the first digit grounds lines 15b, 15c to energize magnets 10b, 10c, making a circuit from ground over contacts 16, 18, 20, 23, 17 as shown in heavy lines, and also withdraws two selector bars. The further digits will cause six more selector bars to be moved, and also complete a circuit through relay 140 and lower electromagnets 37 to battery 39, thereby causing a selected card to drop, and energizing the photo-cells 147 over the upper contacts of relay 140 and de-energizing the upper electromagnet over its lower contacts. The photo-cells control relays forming the output register through gas-discharge tubes. When the input register is released the selector magnets 10 . . . 13, relay 140, and lower magnets 37 are de-energized, the release of 140 causing the re-energization of the upper magnets 38 so that the card is rapidly restored to the stack. Removing a card. To remove a card from the pack it is first selected by sending the code as described above so that the card drops. The hand lever 113 is then operated to lower the upper magnet poles 117, which by their movement operated an insulated switch-arm 43 to energize the upper magnets from battery 54, de-energize the lower magnets, and finally energize the ejector magnet 45, which operating through links 48 rapidly raises an ejector-bar 50 running across middle of the bottom of the stack. This shoots the selected card through the stack so that it adheres to the polepieces 117 by which it may be raised up clear of the guidebars 52 and removed sideways by hand.