Patent GB-191028368-A (GB)
Title: Improvements in or relating to Telephone Call Recorders.
Inventor: BOULT ALFRED JULIUS
IPC: H04M15/28
Filed: 1910-12-06
Granted: 1911-08-31
Abstract: 28,368. Boult, A. J., [Mills, H. S.]. Dec. 6. Meters and metering systems.-The register of a sub-station call-enumerator is advanced a unit by lifting the receiver from its hook, and if the linecurrent is afterwards momentarily interrupted, the call is permanently registered, but if the receiver is hung up again without previous interruption of the line current the register moves back a step to its previous indication. The current-interruption may be caused by the insertion of the operator's answering-plug, or by auxiliary switches, so that only out-going calls are registered. Means are provided for preventing alternating ringing-current at the called station from having the effect of current interruptions, and for preventing, and if necessary cancelling, the registration of ineffective calls. The essential parts of the apparatus, except the actuating-magnet and certain auxiliary armatures thereof, are shown in Fig. 4 in their relative positions ready for assemblage. All the parts except the armature 23 are assembled concentrically on the oscillating-shaft 2 of counting- mechanism 1 of ordinary type. The shaft 2 carries a ratchet-wheel 16, which can be stepped forward by a pawl 13 co-operating with a detent 26, and can be permitted to turn backward in the manner of an escapement under control of the pawl 13 and a pin 14. To effect this double junction, the plate 10 carrying the pawl 13 and pin 14 is pinned pivotally on a sleeve 4 in such away as to partake of the rotational movements of the sleeve, but so as to be capable also of a rocking motion against a spring 15 on an axis at right-angles to the shaft 2. The backward turning power is provided by a spring 21 acting on a loose friction collar 18 pressed against a washer 17 by a spring 19, the pressure of which is adjustable by a screw-secured stop 20. The friction collar 18 keeps the spring 21 wound up sufficiently to effect several backward steps. The actuating-magnet is connected in the line circuit, and has three spring-controlled armatures. The main armature 23, Fig. 4, normally rests against a stop 24, Fig. 2, and is so adjusted that the current normally flowing during a conversation is strong enough to hold it in its depressed or attracted position but is not strong enough to bring it into that position. A second armature is normally held back against a magnetic extension 31, Fig. 2, of the core, but is repelled therefrom, owing to effects due to its magnetic lag, when alternating current passes, and is then attracted towards the main pole-pieces and strikes the lever 32, Fig. 4. A third armature 36, Figs. 8 and 12, is attracted only by special strong currents and engages a spring arm 35 on the rocking-plate 10. The operation of the device is as follows. When the telephone is lifted to give a call, the switchhook rises, and, through a link 8, rocks the sleeve 4 and the plate 10, so that the pawl 13 advances the ratchet-wheel 16 a step and adds a unit to the indication of the counter 1. The lowest ratchettooth, passing over the detent 26, depresses the armature 23, which is then held down by the line current. If the telephone is hung up again before the central operator answers, the ratchet-wheel 16 moves back with the pawl 13 and the counter 1 returns to its previous indication. But if the operator answers, and so causes, automatically or otherwise, a momentary break in the line-circuit, the magnet is de-energized and releases the armature 23, which lifts the detent 26 into engagement with the ratchet-wheel 16, so that the call remains recorded after the telephone is hung up. If the called subscriber should take down his receiver while alternating ringing-current is on his line, a call would be recorded also on his counter. To prevent this, the second armature, actuated only by alternating current, is arranged to strike a lever 32 so as to shift a pivoted plate 25 carrying the detent 26 until the detent is out of the path of the ratchet-wheel 16. Under these circumstances therefore, the call does not remain recorded. When the called subscriber hangs up, an arm 29 of the sleeve 4 engages a cam or extension 28 of the plate 25 and returns the detent 26 to its normal position. If the called subscriber is busy, the operator throws a heavy current on to the calling line, so as to actuate the third armature 36, which, as shown in Fig. 8, moves the detent 26 aside from .the ratchet-wheel 16, and so prevents the call from remaining recorded. By means of further heavy currents, the operator can step back the ratchetwheel 16 so as to cancel one or more ineffective calls which may have been recorded. The first actuation of the armature 36 carries the spring arm 35 off the notched rest 34, as shown in Fig. 8, so that, at every subsequent actuation, a different face of the armature 36 engages the spring-arm 35, and, as shown in Fig. 12, rocks the plate 10, so that the ratchet-wheel 16 turns back a step in the manner of an escapement under control of the pawl 13 and pin 14. In every case, the parts return to normal when the telephone is hung up.