Patent GB-626672-A (GB)
Title: Means for registering a telephone number or message in the absence of the called subscriber
IPC: H04M1/57
Filed: 1946-11-08
Abstract: 626,672. Substation equipment. HINTON, F. G. F., and PLANER, F. E. Nov. 8, 1946, No. 33223. [Class 40 (iv)] [Also in Group XL (b)] A printed record of the number of a calling party, or of other information, is made in the absence of the called party by apparatus responsive to pulses transmitted by the calling party. The pulses may be produced by operation of the impulse transmitter of an automatic telephone set or by sharp sounds made adjacent the transmitter at the calling end. The message recording apparatus comprises a pulse reshaping circuit, a pulse amplifier, a series of relays and timing devices and a printing mechanism which records characters upon a paper strip. As shown in Fig. 1, a change-over switch 1 connects to the line 2 either a telephone set 3 or the recording apparatus. In the latter case ringing current passes through an impedance network 3a, 3b equivalent to the normal bell circuit and over rectifier bridge 5 to operate a relay 4 which connects to the A.C. mains 7 a synchronous motor 8 and the primary winding of a transformer 11. The motor 8 drives cams 9, 10 which time the call and the sequence of operations, and the transformer supplies power to operate the relays, printing mechanism and a valve amplifier. After a short interval during which the caller hears normal ringing tone, cam 9 closes contacts 18<SP>1</SP> to complete a D.C. path through transformer 19 to answer the call and completes the circuit from the A.C. mains against the release of relay 4. Relay 36 operates intermittently upon establishment of the supply over transformer 11 and the voltage fluctuations produced cause a tone to be heard by the calling party. The tone is cut-off at contacts 13 by the operation of cam 10 which at the same instant at contacts 20 connects the input circuit of a pulse amplifier to the transformer 19. The received pulses are applied to a pulse reshaping circuit 22 and drive the grid of the valve 24 positive, thereby operating relay 25, type wheel setting relay 27 and slugged relay 32. The wiper 30 engages the segment 31 when the type wheel is rotated from its normal position and a circuit is thereby prepared over conductor 34 for a printing and paper strip feed magnet 15 which prints when it is energized by the release of relay 32 at the end of a pulse train. Relay 36 then operates and disconnects magnet 15 which advances the paper strip on its release, and completes a self-interrupter circuit for magnet 27 which steps the type wheel to normal. Relay 36 then falls back and all relays are ready for a succeeding train of pulses. As the cam 10 approaches completion of one revolution, contact 13 again closes and reconnects a selfinterrupted circuit for the relay 36 producing a tone which warns the calling party that the time for receiving messages has elapsed, the apparatus finally being returned to normal at the end of one revolution by the cam 9. Spacing between recordings of successive calls is produced by the operation of the establishment of the supply by relay 4. Where there is intermittent ringing current the relay 4 would operate a number of times and in order to give ringing tone to the caller for a relatively long period, the embodiment of Fig. 2 (not shown) may be used in which the relay 15 operates only once in response to ringing current to avoid wastage of paper strip. In a further modification, Fig. 3 (not shown), the starting and operating circuits differ in some details but have the same general effect as the embodiment of Fig. 2. The printing mechanism comprises a spool 54, Fig. 4, for paper strip, a feeding roller 56 mounted upon a plate 52, and a type wheel 65 mounted upon a shaft passing through the plate. The operating magnets 15, 27, Fig. 7, having armatures 63, 70, are mounted behind the plate and a backplate 52a carries the segment 31, the wiper 30 being secured to an insulated extension of the shaft 66. The printing hammer 64 is pivoted at a point to the rear of plate 52, being engaged by the armature 63. The armature 63 also engages a bell-crank lever 61 which carries the operating pawl 59 of the paper feed mechanism. In the embodiment of Fig. 10, the magnet 15 is slow to operate and is arranged to be normally operated. The magnet 27 energizes at each pulse stepping the type wheel 65, the voltage drop produced across a resistance causing magnet 15 to release and stay released during the pulse train. At the end of the pulse train the magnet 15 reoperates, the printing hammer engages the type and then lifts clear due to the toggle action of the link 77 and at the end of the stroke the pawl 69 is disengaged by the arm 63a, allowing the type wheel to be returned by a spring 76. In the embodiment of Fig. 11 (not shown), a further arrangement is employed in which the type wheel is returned to normal by a spring. In a further embodiment, Fig. 12 (not shown), the call is terminated within a pre-determined time of any cessation of received pulses, the timing operations being entirely dependent upon a relay which is slow to operate and slow to release.