Patent GB-179510-A (GB)
Abstract: 179,510. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Willis, B. D.). May 3, 1921, [Convention date]. Addition to 163,807. Automatic and semi-automatic exchange systems and apparatus.-Relates to call indicators for indicating the number of the wanted line, as described in the parent Specification, in which an automatic subscriber is connected over an idle trunk 76, 78, Fig. 2, to an operator's cord circuit O at the manual exchange, an automatic switch C<1>, Fig. 3, associated with the cord circuit O, then selecting an idle register set R<1> - - R<4>, Fig. 4, which responds to dialling impulses to store the wanted number, and subsequently transfers it to a lamp indicator V. According to the present invention, when a register set is taken into use, a timing switch P, Fig. 3, is set in operaticn, and after a given time-interval causes the stored number to be transferred to the indicator V, although through some fault the whole number may not have been registered, unnecessary holding up of the equipment thus being prevented. Means are also described whereby, it the lamp L<7> (which indicates to the operator the cord circuit in use by the subscriber whose wanted number is displayed) is burnt out or disconnected, the supervisory lamp L<8> is lighted in its stead. Release of a register set can only be effected by the manual operator after the stored number has been transferred to the lamp indicator, thereby preventing an operator from clearing her position of accumulated calls. Selection and preparation of an idle register at the manual exchange. A calling automatic subscriber's line is extended in the usual manner over a line switch to a first selector, which responds to the first series of impulses and extends connection to an idle cord circuit O, Fig. 2, at the wanted manual exchange. On the response of the line relay 104, a slow-acting relay 103 is energized, which completes a circuit for the line relay 202 of the associated rotary switch C<1>, which operates in known manner to find an idle register set. The energization of the switching relay 201, when an idle register set is found, energizes a relay 235 of a master switch MS, a circuit being thereby completed for the stepping magnet 272 of the timing switch P over armature 240, and a circuit being prepared at armature 241 for the stepping magnet 301 of the first register switch R<1>, Fig. 4. Setting of register by dialling impulses. The second series of impulses sent by the calling subscriber de-energize the line relay 104 and operate the stepping magnet 301 of the first register switch R' (over a circuit G<5>, 116, 152, 220, 236, 260, 286), which is rotated a corresponding number of steps. When the slow-acting series relay 236 falls back on the cessation of these impulses, a circuit is completed for the stepping magnet 259 of the master switch MS, which advances its wipers a step, thereby transferring the impulse circuit to the stepping magnet 321 of the second register switch R<2> over the conductor 287. The switch R<2> is now stepped round in accordance with the impulses of the third digit, and the operating circuit is transferred by the master switch MS to the third register R<3>, which is then set by the fourth digit. In a similar manner the register R<4> is operated to store the fifth and last digit of the wanted number, and -after the cessation of these impulses the wipers of the master switch MS are moved to their fifth contacts. Earth is thereby connected to the conductor 291 over the wiper 255 and the relay 238 is energized. Transfer of wanted number to the lamp indicator V by the transfer switch CCS, Fig. 2. Relay 238 completes a circuit over the conductor 284 for a supervisory lamp L<1>, Fig. 2, and for a relay 162 of a rotary switch CCS, the bank contacts of which are connected to conductors 171 - - 176 associated with all the register sets at the position. On the response of the relay 162 a circuit is closed for the slow-release relay 161, and the wiper 164 is connected to a point midway between the stepping relay 163 and the switching relay 160. The bank contacts are normally grounded at the registers, but when a register is ready to transfer a number, ground is removed from the corresponding bank contacts at armature 248 of relay 238, Fig. 3. So long as the wiper 164 engages grounded contacts it will be rotated after the manner of a line switch, but on arriving at the first ungrounded contact the switching relay 160 will be energized and rotation arrested. Assuming this is a contact connected to conductor 171 associated with the register under consideration, on the response of the switching relay 160, the circuit of relay 161 is broken, but before this relay relapses, the transfer relay 239, Fig. 3, of the register set is energized in a circuit G<3>, 170, 166, 164, 171, 248, and locks up over conductor 291. Relay 239 grounds conductor 281, thereby closing parallel circuits for relays 303, 323, 343, 363, Fig. 4, which earth the common strips in the upper banks of the registers R<1> - - R<4> and close circuits for lamps in the indicator V corresponding to the selected contacts of the registers R<1> - - R<4>. The registers R<1> - - R<4> are provided with extra banks and wipers, the banks being wired to the lamps of a spare indicator, so that if the indicator V develops a fault, by depression of a key K the spare one may be brought into operation. Relay 239 also (1) connects the grounded lead 291 to conductor 171 to hold relay 160 energized and the switch CCS stationarv until the call concerned is disposed of, and (2) energizes a cord signal lamp L' over conductor 150 and relay 102. Completion of call by operator and release of register set. On observing the wanted number the operator will test in the usual manner, and if the wanted subscriber is idle, insert the plug of the cord circuit, indicated by the lamp L<7>, into the jack J of the wanted line. The response of a sleeve relay 109 energizes relay 107 and completes a ringing circuit from the generator GEN. Relay 107 disconnects the signal lamp L<7>, and energizes a relay 101 over the grounded conductor 150 and armature 124, thereby disconnecting ground from conductor 151 and deenergizing relays 201, 235 of the switch C', Fig. 3. Relapse of relay 201 restores switch C<1>, whilst the de-energization of relay 235 grounds the conductor 280 and completes circuits for the release magnets 271, 258, 302, 322, 342, and 362 of the line switch P, the master switch MS, and the register switches R<1> - - R<4>. Release of the master switch MS is followed by the relapse of relays 238, 239, and disconnection of the lamp L'. Thus the register set cannot be released by the operator until the wanted number has been transferred to the indicator V, since release is effected by the relay 101, the circuit of which cannot be completed until the conductor 150 is grounded by the response of the transfer relay 239. If no other calls are waiting, relay 162 of the transfer switch CCS also falls away, but if calls are waiting on other register sets, relay 162 remains energized over another lamp similar to L<1>, and the contact engaged by wiper 164 now being grounded over conductor 171, the switch CCS rotates as previously described to engage the first contact associated with a register set waiting to transfer a call. When the called subscriber answers, the ring cut-off relay 108 energizes and locks itself up by the removal of a shortcircuit across its upper winding, completing at armature 126 a talking circuit in which current is supplied over the feed :relay 106. This relay first energizes over its lower winding, the upper being normally short-circuited to keep it out of the ringing circuit, but on its response the shortcircuit is removed and both winding are included in the battery feed circuit. Premature disconnection by operator; final release. If the operator should withdraw the plug before the calling party hangs up a flashing circuit is completed for the lamp L<7> from the interrupter I. When, however, the calling subsciiber hangs up, de-energization of the line relay 104 and series relay 103 restores the preceding automatic switches in well-known manner. Relay 103 closes a circuit for supervisory lamp L<8>, and the subsequent relapse of relay 100 grounds the release conductor 77 to render the trunk busy pending release by the operator. When the operator removes the plug. relays 109, 108, and 107 are de-energized and the lamp L<8> extinguished. Operation of time switch P to transfer " mutilated " calls. On the energization of relay 235 when the register set is taken into use, a circuit is completed for the stepping magnet 272 of the time-switch P, which is then rotated one step each time the common conductor 270 is grounded by the clock mechanism T. say every second. After the expiration of a definite period, say ten seconds, the relay 238 is energized over wiper 274 and in.tiates the transfer operation, as previously described. Normally the relay 238 is energized by grounding of the conductor 291 by the wiper 255 of the master switch MS, on the cessation of the fifth series of impulses, so that if for any reason the full complement of digits is not received or sent the transfer is held up. By the operation of the switch P the " mutilated " number is transferred to the call indicator aftera definite time interval and the call may then be extended to a complaint operator for attention. Alternative use of supervisory lamp L<8> as a cord signal lamp. The circuit of the proper cord signal lamp L' extends over the relav 102, from the armature 114 of which a branch circuit extends to the supervisory lamn L<8>. If there is nothing wrong with the circuit of the lamp L<7>, the relay 102 energizes in series with it and disconnects the lamp L<8>, but if the circuit of the lamp L' is open at any point, the relay 102 will remain iners and the lamp L<8