Patent GB-154726-A (GB)
Title: Method of and apparatus for operating synchronous telegraph systems
IPC: H04L25/49
Filed: 1919-09-08
Abstract: 154,726. O'Dell, A. E., (Western Union Telegraph Co.). Sept. 8, 1919. Type-printing telegraphs.-In a type-printing telegraph system of the kind in which combinations of positive and negative current impulses are sent to line by means of a perforated-strip transmitter, means are provided for suppressing successive current impulses of like polarity, thereby reducing the static charge upon the line. The strip transmitter operates in conjunction with a set of relays and a rotary distributor so arranged that the strip is fed to set up a signal during the sending of the last two impulses of the preceding signal. A condenser limits the length of the signal impulses and constitutes the means for suppressing successive impulses of like polarity. Transmitter. The movable contacts t, Fig. 1, of the strip transmitter T normally engage a set of contacts connected to the negative pole of a battery 10, and are adapted to be moved into engagement with a set of contacts 1, 2, 3, 4, and 5 connected to the positive pole of a battery 12 in accordance with the perforations of the strip. The contacts t adapted to engage contacts 1, 2, and 3 are connected directly to the segments 1', 2<1>, and 3<1> of the ring R<1> of a rotary distributor D, while the contacts t adapted to engage contacts 4 and 5 are connected to the armatures of an overlap relay OT. The armatures of the relay OT control the circuits of the operating windings 18, 18<1> of two relays OR provided with holding windings 23, 23<1> connected in series with resistances 24, 24<1> respectively. The tongues 19, 19<1> of the relays OR move between a pair of fixed contacts connected to the positive and negative poles of batteries 20 and 21. The tongues 19 and 19<1> are connected to the segments 4<1> and 5<1> of the ring R'. The contact segments of the ring R' are connected to a ring R<3> by means of a brush BR and the ring R<3> is connected to a sending relay SR which controls the circuits of the operating windings of a transmitting relay TR. The windings of the relay TR are energized from batteries 28, 28<1> and their circuits contain a condenser C which limits the duration of current flow in the relay windings and consequently the duration of operation of their armatures which connect the signalling battery 30 to line. The rotary distributor D comprises a second segmental ring R<2> having its segments 2<a> connected to the winding of the relay OT through a lead 15, and segments 4a connected to the tape-feed magnet TM through a lead 15<1>. The ring R<2> is connected to a grounded ring R<4> by means of a brush BR<1>. Receiver. The cable relav CR. Fig. 1, controls the windings 41, 45 of a polarized relay LR the tongue 42 of which connects a battery 43 to the ring R' of a distributor D' when positive impulses are received by the relay CR. The ring R' is connected to a segmental ring R<5> by means of a brush BR<2>. The segments 1<11>, 2", 3<11>, 4" and 5<11> of the ring R<5> are connected to the operating windings of selecting relays r', r<2>, r<3>, r<4> and r<5> in order that these relays may be energized when positive impulses are received by the relay CR. The distributor D<1> is provided with a segmented ring R<6> one segment of which is connected to a clear-out relay. The ring R<6> is connected to a grounded ring R<8> by means of a brush BR<3>. Operation. In transmitting a character the signal impulses of which are two positive followed by three negative impulses, the strip ST, Fig. 2, is punched as shown under the letter A so that when passed through the transmitter two movable contacts t, Fig. 1, are operated to engage the front contacts 1 and 2, thereby connecting the segments 1', 2<1> of the ring R' to the positive pole of the battery 12, while the segment 3<1> remains connected to the negative pole of the battery 10. When the brush BR engages contact segment 1<1> a positive impulse is sent to the relay SR thereby causing its tongue to engage its right-hand contact. to energize the magnet of the relay TR from the battery 28<1> in series with the condenser C. When the condenser C is fully charged the armature of the + magnet of the relay TR is released, thereby terminating the positive impulse sent to line from the battery 30 and grounding the line at the back contact of the relay. The energization of the cable relay CR at the receiving station by a positive impulse causes the tongue of this relay to close the circuit of the operating winding 41 of the polarized relay LR, thereby connecting the ring R' of the distributor D<1> to the battery 43 and consequently energizing the selecting relay r<1> which locks up over its front contact. The ring R' remains connected to the battery 43 until a negative impulse is sent to line. During the latter part of the period of contact of the brush BR with the segment 1<1> the brush BR' engages the contact segments 2a of the ring R<2> to energize the winding of the relay OT. The armatures of the relay OT are attracted to connect the two lower contacts t to the operating windings 18, 18' of the relays OR, and since in this case the contacts t are connected to the nagative pole of the battery 10 the tongues 19, 19<1> of the relays OR are moved to the left to connect the negative pole of the battery 21 to the segments 4<1>, 5<1> of the ring R'. The tongues 19, 19<1> are held in their operated positions by windings 23, 23' connected in series with resistances 24, 24<1> respectively after the brush BR' has left the segments 2a of the ring R<2>. When the brush BR engages segment 2' of the ring R' the relay SR is again operated to close the circuit of the + magnet of the relay TR, but since the condenser C is fully charged the + magnet is not operated and consequently the battery 30 is not connected to line. Since the battery 43 is connected to the ring R' by the previous positive impulse, the selecting relay r<2> is energized when the brush BR<2> engages the segment 2<11>. When the brush BR engages segment 3<1> a negative impulse is sent to relay SR, and since the condenser C is charged positively the - magnet of the relay TR is energized to send a negative impulse to line from the battery 30. The cable relay CR is operated to energize the winding 45 of the relay LR, thereby disconnecting the battery 43 from the ring R' so that when the brush BR<2> engages segment 3" the relay r<3> is not energized. When the brush BR engages segment 4 the relay SR is connected to the negative pole of the battery 21, but since the condenser C is fully charged the - magnet of the relay TR is not energized. At this point the brush BR<1> engages contact segments 4a to energize the tape-feed magnet TM, the segments 4<1> and 5' being held in connexion with the battery 21 by means of the relays OR. Similarly, no impulse is sent to line when the brush BR engages segment 5'. The holding circuits of the operated relays r<1> - - r<5> are broken by a relay CR' which is energized when the brush BR<3> engages a segment of the ring R<6>.