Patent GB-1473631-A (GB)
Title: Automatic telephone dialing apparatus
IPC: H04M1/276
Filed: 1975-01-13
Abstract: 1473631 Repertory diallers SI-LING TSAO 13 Jan 1975 [24 Jan 1974 6 Nov 1974] 1387/75 Heading H4K In a repertory dialler having a storage medium for a plurality of numbers, all the first digits are stored in a first region of the medium, the second and subsequent digits being similarly stored. In the embodiment the storage medium may be a magnetic tape a magnetic drum or a magnetic disc having the capacity to store 256 numbers associated with a keyboard 12. A digit may be stored as a 2 out of 7 frequency bursts, as a number of cycles of an AC signal or as a number of impulses. Signalling to the exchange may be by a 2 out of 7 frequency signalling or by decadic signalling. Storage of numbers.-In all the embodiments a first length of magnetic medium is used as the first region and successive lengths are respectively used for the second and subsequent regions. Two different methods can be used to define the position within each region at which a digit of a number is stored, the position being the same within each region for a particular number, and both make use of the fact that the complete recording medium is scanned from end to end for each number to be recorded or played back. In a mechanical arrangement (Fig. 5), depression of a key with which a number to be stored is to be associatedmarks one of the wires 63. In the record mode a record button is depressed and the first digit of the number is keyed to engage a clutch drive, coupling the recording medium to a motor. As the recording medium rotates the contact arm 66A scans the wires 63 and when a marked wire is scanned a one shot multivibrator 71 is operated to gate the output of two of a series of seven oscillators to the recording head when all the contacts have been scanned the motor drive is disengaged and the second digit is keyed and is likewise stored. The second arrangement makes use of uniformly spaced reference impulses recorded along a track parallel to the digit storage track. The keyboard, Fig. 6, comprises wires 90B linking all the keys of a row and on further wires not shown, extending through holes 88 to link all the keys of a column. Depression of a key depresses the row wire 90B at 89 to slide member 98 upwards, this member being notched such that a combination of the wires 100B-100E are moved upwards to latch corresponding row identity contacts (Fig. 6d, not shown). A similar arrangement associated with the column wires operates a further combination of four column identity contacts, thereby giving the binary identity of the key operated. When the recording medium is scanned a playback head supplies the reference impulses to a binary counter (Fig. 7, not shown) coupled via the row and column identity contacts to a gate such that when the binary counter reading corresponds to the binary identity of the depressed key a gate is enabled to permit a keyed digit to be recorded.  If the digits are to be transmitted to the exchange using decadic signalling a D.C. button is operated before entering the number to cause a reference signal to be stored in combination with each dual frequency digit signal. Signalling to the exchange.-Depression of one of the repertory buttons causes the tape medium to move past the replay head and each digit signal associated with that key is gated off the medium in turn in a similar manner to that in which they were recorded except that the recording medium is run continuously. Referring to Fig. 3 each digit signal is supplied to a discriminator circuit 29 comprising eight tank circuits, one for each of the seven digit frequencies and the other for the D.C. signalling reference signal. Assuming no D.C. reference signal is stored, the outputs of the seven tank circuits are fed to respective amplifiers, fullwave rectifiers and clippers to convert them to two D.C. impulses which are then differentiated and detected and used to trigger two out of seven oscillators 34 to supply the tone to the line. If, however, the D.C. reference signal is detected the oscillators 34 are disabled via bi-stable multivibrator 31, and the recording medium is halted. The outputs from the tank circuits 29 are then used in conjunction with a binary counter (Fig. 8, not shown) to cause an appropriate number of clock pulses to operate relay 43 to signal the digit in decadic form to the exchange, a 500 ms one shot multivibrator providing a suitable interdigital pause. The recording medium is set in motion again at the end of the pause. The Specification also describes in detail the circuitry necessary for storing and signalling information where the digits are stored as a number of cycles of an A.C. signal or as a number of impulses.