Patent GB-247243-A (GB)
Title: Improvements in automatic telephone exchange mechanism
IPC: H01H67/24
Filed: 1924-09-10
Abstract: 247,243. Watts, A. Sept. 10, 1924. Automatic and semiautomatic exchange systems and apparatus. - Connecting apparatus comprises vertical line conductors A, Fig. 1, for each subscriber and horizontal link conductors B, which are allotted for use in turn by means of a switch M. Connection is made at a point of intersection by a twinplug C, Fig. 3, passing through the line conductors A and making contact in its advanced position with springs D in contact with the link conductors B. The plug C is held by the springs D, and is released at the end of the conversation by a longitudinal movement of the conductors by means of a magnet F. Auxiliary vertical and horizontal conductors J, K are provided. The line relay of the calling subscriber closes a circuit 2J through a magnet H which operates the plug C corresponding to the allotted link B. The circuit 2J also includes a magnet which advances the allotting switch M one step, and the plug C closes a circuit O for the cut-off relay P. The calling subscriber is now connected over the link B to a feed circuit and thence to an automatic switch R, which responds to dialled impulses to connect ground to a selected terminal. To make connection between the link and the called subscriber's line, a row of magnets Q is provided, carried by a frame which is lowered opposite the link in use under control of a circuit closed when any magnet operates. Means are provided for raising the frame when the bottom of the connecting apparatus is reached. The magnets Q are connected to the terminals of the switch R, and control the plugs C as shown in Fig. 3. A ringing and supervisory circuit may be associated with the link B. In an alternative arrangement for connecting the calling subscriber's line to the link B, the magnets H, Fig. 4, in a vertical row are connected in series, and the armatures 2G which control the plugs C are carried on horizontal rails 3G which are moved into operative position in turn by the allotting switch M. The auxiliary conductors K are dispensed with. The Provisional Specification also describes an arrangement employing auxiliary vertical and horizontal bars of soft iron to which magnetic potentials are applied to set up sufficient magnetic flux at the junction to operate the connecting plug thereat. Fig. 5 shows a system adapted for inter-exchange working in which the connecting apparatus is duplicated 4B, 3B for connecting up the calling and called lines, the latter connection being made under control of an operator, so that the travelling frame carrying the magnets Q is dispensed with. The calling line 2A is connected to a link B (not shown) in the section 4B as in Fig. 1, and hence to the operator's position. The operator is provided with a controller 2N by which she may connect the link B to the next idle link in the section 3B at the same or at another exchange, and with keyboards 3K, 4K for controlling the marking switch 2E at the same or at another exchange to connect ground to the marking wire 2D corresponding to the wanted line. If this line is idle, the cut-off relay P is inoperative, and a relay 6D energizes, causing the magnet H to operate and connect the line to the allotted link. If this line is busy, the cut-off relay P has moved the contact 5D, so that a relay 2H energizes and causes a magnet 4H to operate and connect a busy signal over the allotted link to the calling subscriber. For a large system, the controllers 2N and keyboards 3K, 4K may be located at a central exchange.