Patent GB-175763-A (GB)
Title: Means for recording telephone calls
IPC: H04M1/57
Filed: 1920-11-24
Abstract: 175,763. Wood, A. W. Nov. 24, 1920. Index type-wheel machines; hammer-compression arrangements; letter-spacing mechanism.- The vibration of the bell-hammer of a telephone calling-apparatus actuates mechanism which, if the telephone is unattended, may either simply record the fact that a call has been made, or may also print the caller's telephone number upon a paper strip. A full ringing-period of, say, three seconds is recorded by a printed zero; alternatively, the caller's number is registered by means of a series of rings of varying duration controlled either from the exchange or directly by the calling subscriber. As the bell-hammer c vibrates, a stop i thereon forces a piston-rod g horizontally over to the left, the piston-end m moving freely forward in a dash-pot or cylinder l. A one-way valve n retards the return of the rod g under the pull of a spring j. So long, therefore, as the bell continues to ring, the rod is maintained fully over to the left. This releases a driving-pawl b and holding-pawl f from the stop i and allows them to come into contact with a ratchet-wheel c<3>, so that each subsequent stroke of the bell-hammer rotates this wheel, together with a concentric drum d carrying peripheral printing-numbers d<1>, until the desired numeral is located above a printing-block r, which is then released by a cam 10 mounted on a pinion v to effect the printing. The paper strip is carried on a spool p mounted on a gear-wheel u. A weight t tensions the paper and tends to rotate the gea,rwheel u. This rotation is normally prevented by the engagement of the lower end of the rod x, Fig. 3, with a stop w on the axle of the pinion v. As the piston-rod g moves over to the left, a cam o passes over a pivoted arm y without raising the rod x; but on its backward movement, when the bell has stopped ringing, it lifts both the arm y and rod x bodily so as to release the stop w. This enables the pinion v to rotate and effect the printing-operation, and also feeds a fresh portion of the paper strip from the spool p. At the end of each ringing period, the stop o raises pawls b, f from contact with the wheel c<3>, and the printing-drum swings back to zero under the influence of a spring e. The correct duration of each ringing-period required to print a given numeral is controlled by means of a similar recorder at the operating station, connected in parallel with the subscriber's instrument as shown in Fig. 4. The index is set to the required numeral and the bell is rung until a spring-controlled pin on the operator's dial automatically breaks contact. The subscriber's recorder being in synchronism thereupon prints the selected number. According to the first Provisional Specification, the bell-hammer may actuate a pencil or needle to make a visual record in Morse code upon a paper strip which may be unwound by means of clock-work controlled by Geneva-stop mechanism. According to the second Provisional Specification, the printing- drum may be rotated by clock-work, and the printing-block is brought into contact with the selected numeral by means of planet-gearing.