Patent GB-295409-A (GB)
Title: Improvements in line-finder arrangements for automatic telephone exchanges and other remote control systems
IPC: H04Q3/00
Filed: 1927-03-10
Abstract: 295,409. Baron, H., (Representative of Aldendorff, F.). March 10, 1927. Automatic exchange systems. - Unidirectional call-finders are associated with a starting circuit over contacts closed only when a finder is in the " ready " position, i.e. on the first terminals of the bank, one disengaged finder setting itself in this position and others in consecutive " waiting " positions at the end of the bank. On a call arriving the " ready " finder starts and the foremost " waiting " finder moves to the " ready " position. In a modification the disengaged finders distribute themselves on the first terminals of different sub-groups of lines, and a call is served by the finder (if there be one) standing on the sub-group in which the call occurs. Fig. 1 shows ten 100-point finders A1 - - - A10, of the type described in Specification 254,373, A1 standing in the ready position k1 and A2 - - - A10 in waiting positions k92 - - - k100. Contacts S1 - - - S10 are closed only when the respective finders are in position k1. When a line relay LR pulls up, relay R1 of the finder A1 is energized in series with relay 83 over contact S1 and starting wire SW. Relay 83 locks itself and cuts out relay 81. Relay R1 locks itself and energizes the finder magnet M1 over brush b3 and contacts such as 5 of non-calling lines. When the calling line is reached, cut-off relay 6 is energized over brush b4 in series with relay C1, which unlocks the main winding of R1 but closes a circuit through its weak left-hand winding to keep only the contact 20 closed. Meanwhile R1 has connected battery to a " moving-on " circuit 27, so that if a finder A2 is standing in the last waiting position k100 its magnet M2 is energized in series with relay f1 and moves it to the ready position k1. Contact S2 is now closed but relay R2 cannot be energized by the same call because relay dr in the circuit 27 cuts a resistance drs into the starting circuit as long as R1 remains energized. Helay f1 locks itself but is unlocked when R1 relapses. The next call is answered by the finder A2. Since now there is no finder in the position k100 a high-resistance relay re is energized (instead of f1) over the circuit 27 and locks itself and energizes f2 in series with the magnet of the finder A3. On this finder moving forward, the relay f2 relapses and closes at 28 a circuit for moving the finder from k100 to k1. If a call arrives when the last two waiting positions k99, k100 are both unoccupied, the relay re energizes a relay ga to close a circuit 70 for the magnets of all disengaged finders to advance them until one arrives in the position k99, whence it proceeds as before to k1. If a call arrives when there is no finder in position k1, relay 81 is energized in the starting circuit Instead of 83 (since no S contact is closed) and closes circuit 70 until a finder reaches position k1. When the finder A1 is released by deenergization of relay C1 a circuit is momentarily closed over contact 20 for magnet M1, which locks itself over 17, 24, 14 to the brush b2. The terminals wiped by this brush are connected to battery over b2, 14, 24, 16 of a disengaged finder if such a finder is at rest upon them, so that the finder A1 moves forward until it reaches an unoccupied position. Positions k1 - - - k91 count as a single position for this purpose, their b1 terminals being commoned as shown at 26, so that a released finder generally goes right forward to a waiting position. Fig. 3 shows how a pair of relays f, re may be provided for each waiting position to ensure that the foremost waiting finder is advanced when the ready position falls vacant. On the closure of the moving-on circuit 27, relay f1 is energized in series with magnet M1 if there is a finder in the first waiting position, but otherwise the high-resistance relay re1 is energized and closes a similar " feeling " circuit for the next position, and so on. Modification with sub-groups. Fig. 2 shows an arrangement of 12 finders, of which, supposing them all to be disengaged, ten stand on the first terminals of sub-groups g10 - - - g00 and two stand on the last two sets of terminals w1, w2. A call in the second sub-group g20 energizes relay g2 to connect the starting circuit SW over the bank-strip zb and brush ab to the starting relay Rb of the finder standing on the first terminals of the sub-group. If there is no finder in that position, relay 81 is energized as in Fig. 1 and closes circuit 70 to advance all disengaged finders until one arrives in the calling sub-group. At each call the circuit 27 is closed to move a finder out of the waiting position w1 or w2, this finder setting itself to the first unoccupied sub-group. The bank-strip 26, Fig. 1, is divided into strips da, db etc. for each sub-group. The brushes, aa, ab etc. and bank-strips za, zb etc. may be replaced by shaft contacts as in Fig. 1.