Patent GB-191207100-A (GB)
Title: Improvements in or relating to Telephone Systems.
Inventor: MELLINGER EDWARD ARTHUR
IPC: H04M3/12
Filed: 1912-03-22
Granted: 1913-03-25
Abstract: 7100. Mellinger, E. A. March 22. Time-controlling systems.-In an automatic or manual exchange system, mechanism for limiting the length of conversation between two subscribers is brought into operation when the called subscriber answers, this mechanism, after a certain time, automatically releasing the connexion in an automatic system, or giving the clearing signals in a manual system. A warning- signal is transmitted to the subscribers shortly before the end of the time interval. The invention is described as applied to a two-wire automatic exchange system, and also to an incoming junction of a manual system. Automatic exchange systems. - The two-wire system, in connexion with which the invention is described, is provided with line and master switches operating substantially as described in Specification 1419/10, and with group selectors substantially identical with that described in Specification 1298/10. Connector. As soon as connexion is made by a group selector I, Fig. 2, with a connector H serving the wanted line, the line relay 95 is energized over the contacts of the reversing- relay 135 and the calling line. The relay 95 energizes the slow-release relay 102, which earths the test lead 106 over the contact of a relay 105. The ' tens ' selecting-impulses are repeated by the relay 95 over contacts 107, 108, slow-release relav 109, vertical magnet 110, and side-switch arm 111 to the battery. The magnet 110 raises the wipers to the desired level, and the relay 109 controls the private magnet 114, which, as soon as the impulses cease, moves the side-switch into its second position, in which the final set of selecting-impulses is repeated to the rotary magnet 115, thus moving the wipers to the contacts of the desired line. Busy test and busy signal. If the desired line is engaged, its test lead 125 is earthed, and maintains a circuit for the private magnet 114 over contact 113, relay 162, contacts 161, 160, and side-switch arm 123 to the earthed test lead. The private magnet keeps the side-switch locked in its second position. The relay 162 (1) by closing contact 164 shifts the holding-ground on the private magnet from the test lead to the ground G", and (2) connects the busy generator O<2> to the calling line. The connexion is released when the calling subscriber replaces his receiver. Supply and control of ringing-current. If the required subscriber is disengaged, the sideswitch moves into its third position, thus energizing the cut-off winding of the called subscriber's line-switch. The ringing-relay 131 is intermittently energized to connect the generator Q to the called line by current through the interrupter 132, normal contact of relay 139, relay 131, and side-switch arm 111 to the battery. When the called subscriber answers, the reversing-relay 135 is energized by current passing over the contacts of the private magnet 114 to the called station. The reversal of current in the calling line may be used to operate a meter, or to control supervisory signals. The relay 135 also energizes a relay 139, which disconnects the ringing-relay 131 and locks up over its contacts 142, 141, 140. Normal release. If the calling subscriber replaces his receiver first, the relay 95 permanently opens the circuit of the release relay 102, which energizes the release magnet 144 and opens at a contact 103 the holding-circuit of the release relays of the group selectors. If the called subscriber hangs up first, the back-bridge relay 135 de-energizes, but, as the relay 139 remains locked, a circuit is closed for the relay 105, which interrupts the holding-circuit of the release-relays of the group selectors. As soon as the selectors are released, the relay 95 is deenergized and effects the release of the connectors. Automatic release by time-controlling apparatus. As soon as the relay 139 is energized by the response of the called subscriber, a circuit is completed through the stepping and detent magnets 46, 47 of the ratchet mechanism L, which is rotated by the interruption of the current supplied to the magnet 46. When a cam 44 has nearly completed its rotation, a projection 47<a> closes a contact 155, thus connecting a special warning-signal generator O<3> to the subscribers. Shortly after, the projection 47<a> closes a contact 159 in the circuit of the release magnet 144, thus releasing the connexion. Signal lamps 150, 158 indicate the position of the cam 44 to the exchange attendant. Exchange systems. - Fig. 4 shows the invention applied to a keyless-ringing incoming junction - circuit from a common battery exchange. When the B-operator has tested the required line, she inserts the plug P in the jack J, thus energizing a relay 202, which disconnects the operator's testing-apparatus T. When the A-operator inserts her plug P<1> in the allotted jack J<1>, current flows through the supervisory relay 204, high-resistance winding 206 of a relay 207, and the coil 209 to the battery. The resistance of the winding 206 prevents the excitation of the relay 204, so that the lamp 210 continues to glow. The relay 207 completes a circuit for the ringing-relay 218, passing from ground G<17> through the relays 201, 202, contacts 211, 213, 214, 216 (the last two contacts forming a short-circuit round the relay 217), and relay 218 to the battery. The relay 218 is thus put in parallel with the lamp 203, which is thereby extinguished. The relay 218 connects the ringing-generator 219, through an interrupter 220, tripping-relay 215, and contacts 221, 222 to the called line, and thence over contact 223 and coil 224 to the battery. When the called subscriber replies, the relay 215 is energized over the interrupter 220 and ground G<20>, and removes the short-circuit around the relay 217, which energizes and connects its winding to the battery B<3>, thus shortcircuiting the relay 218, so as to cut off the ringing-current and connect the calling-plug to the repeater coils. A circuit is also completed through the called station for the relay 225, which by means of its 'armature- 228 brings the low-resistance winding 232 of the relay 207 into parallel with the high-resistance winding 206, thus increasing the current in the junction circuit sufficiently to energize the supervisory relay 204, which shunts out the lamp 210 so as to indicate to the A-operator that the called subscriber has answered. The relay 225 by attracting its armature .229 also supplies current through a supervisory lamp 237 to the stepping and detent magnets 233, 235 of the time-controlling ratchet mechanism, which is rotated by the interruption of the current supplied to the magnet 233. When the cam 239 has nearly completed its revolution, a projection 240 closes a contact 241, thus connecting a warning-signal generator O<3> to the talking circuit. A short time after, the projection 240 opens a contact 231 in the circuit of the low-resistance winding 232 of the relay 207. The decrease in the current over the junction circuit de-energizes the relay 204, thus lighting up the supervisory lamp 210. When the A-operator removes her plug P<1>, the relay 207 de-energizes and opens the circuit of the relay 217, which removes the short-circuit round the supervisory lamp 203. Trunk calls. In the case of trunk calls, the subscribers may be given the option of using the connexion for a further interval of time after the expiration of the first interval, the operator giving the subscribers this option after she has received a warning-signal by her lamp that the interval has nearly expired. Systems for transmitting music; coin-freed systems.-The invention may be used in systems for the distribution of music &c. wherein a charge is made for the use of the line far a certain specified time. The connexion may be completed after the insertion of one or more coins by the calling subscriber.