Patent GB-184202-A (GB)
Title: A method of and means for registering telephone calls
IPC: H04M15/30
Filed: 1921-02-04
Abstract: 184,202. Kinnard, E. H., and Clark, W. Feb. 4, 1921. Coin-freed systems; meters and metering systems.-In means for registering telephone calls, mechanism working in conjunction with a subscriber's instrument is advanced a number of steps by the exchange, the zeroizing of this mechanism by the calling subscriber serving to effect registration of the call and also to establish the speaking connection. In one arrangement, Figs. 1, 3 and 4, the exchange operator, after making the connection, sends a number of booster impulses corresponding to the character of the called line, which cause the armature 3 of a marginal relay 2, in series with the calling subscriber's transmitter, to step round a ratchet wheel 8 loosely mounted on a spindle 10. A bevel wheel 9 fast with the wheel 8 is geared to a second bevel wheel 13 fast with a second ratchet wheel 14 by means of a bevel pinion 11 carried on a member 12 mounted on the shaft 10. The member 12 also carries a light drum 31 which shows through a window in the casing the number of units of charge to be registered. The subscriber then zeroizes the instrument step by step by depressing the lever 25 on the rock shaft 24 a number of times until the drum 31 has returned to zero, each depression causing a pawl 27 on the arm 26 to step round the ratchet wheel 14,. thus registering the call on a counter 30 operated through gearing 28, 29. A contact member 15 on the shaft 10 normally closing contacts 16 in the receiver circuit, allows them to separate when the mechanism is operated by exchange, only closing them again to complete the speaking circuit when the instrument has been zeroized and the call registered. Means at the exchange for sending the booster impulses comprises a key 46, Fig. 4, which short-circuits the impedance coils 41, to connect the battery 40 directly to the subscriber's line 42, 43. A pilot lamp relay 47 may indicate to the operator when the registration has been effected, and the key 46 may also be in circuit with an exchange recording instrument. A condenser is shunted across the electromagnet 2 to prevent its operation by ringing currents. If the subscriber replaces his receiver without zeroizing his instrument, this operation may be effected and the call registered, by means of a heart-shaped cam 17 mounted on the spindle 10 and operated by a lever 18 linked with the receiver hook. A stop on the lever 18 engaging with a pin on an arm 23 on the shaft 24, normally prevents the operation of the lever 25. To prevent more than the required number of operations of the lever 25, a cam 118 spring-pressed against a stop 119 on the contact member 15 engages with an arm 120 on the shaft 24 when the member 15 is in its zero position. In a second arrangement, Figs. 7, 10 and 11, a charge wheel 70, Fig. 7, at the exchange, having finger holes 72, an index ring 73 bearing consecutive numbers, and a finger stop 96, is set by the operator to a position corresponding to the number of units of charge for the called line, and is held set by spring pawls 97. The wheel carried on a sleeve loosely mounted on a spindle is connected through a spiral spring to a disc fixed to the same spindle, this disc having attached to it an escapement wheel 83 and an annular plate 89 provided with an inwardly-directed flange in which is an insulating segment 92, the plate 89 being insulated from the other parts by a circular washer. When the wheel 70 is set, the spiral spring is tensioned, but is prevented from driving the escapement wheel 83 by the pawl 84 which is connected by a link 88 to the armature 77 of an electromagnet 76. Brushes 93 fixed to the wheel 70 engage with the insulating segment 92 when the instrument is at zero, but are in conducting connection when the wheel is set. The wheel also carries slip rings 94, with which brushes 95 on the index ring 73 continually engage. Fig. 11 shows the exchange connections. When the called subscriber replies, a supervisory relay 109 is energized to complete a circuit from the central battery 101 through the brushes 95, slip rings 94 and brushes 93 now in conducting connection to operate a reversing relay 108. The reversal of the current in the subscriber's induction coil 65 causes a pivoted consequent-pole permanent magnet 66 to move over, thus causing an attached cam to close a contact 69. A circuit is now completed from earth through battery 101, electromagn et 76, line 102<a>, coil 65, contact 69, electromagnet 55 to earth. The energization of the magnet 55 at the subscriber's apparatus, Fig. 10, causes a rotatable flag member 53, normally held up by a bell-crank lever 61a engaging the armature 56, to drop into visible position before a window in the casing to notify the subscriber that registration must be effected, whilst at the same time the springs 55<a> short-circuit the receiver 110. The subscriber then depresses a spring-pressed lever, thereby operating a counter 52, opening normally-closed contacts 117 in the earth-circuit of the magnet 55, and, by means of a pin 62 on a disc 63, restoring the flag 53 to invisible position. De-energization of the magnet 76 by the opening of the contacts 117 allows the wheel 83 to move round one step under the control of its spring and the pawl 84. If the charge wheel has been set for more than one unit, the magnet 55 is again energized, the flag 53 reappears, and the subscriber continues operating his lever until the charge wheel 70 is zeroized, the circuit o:' the reversing relay being then permanently broken at the insulation 92, and the call fully reg stered on the counter 52. In order to prevent the registration of a call when the called line is engaged, the casing 75 containing the electromagnet 76, its armature 77 and the pawl 84, may be pivoted to the main casing 74, being held in position by the leaf spring 116. The withdrawal of the cord plug 105 from the wanted line may, by its weight, cause the casing 75 to rock about its pivots 114, thus freeing the pawl 84 and allowing the number wheel to be zeroized. Alternatively the casing 75 may be mounted on a cover which overlaps the charge-wheel rim, the removal of the cover causing the zeroizing of the wheel. In telephone call boxes, the hand lever may be actuated by coins instead of by hand. One Provisional Specification describes a modification of the arrangement shown in Figs. 1 and 3 in which the marginal relay operates a spring-retarded ratchet wheel having a contact arm which closes the line circuit when in its zero position, but opens it when otherwise; the subscriber's press-stud operates an anchor or like escapement for restoring the ratchet wheel, the stud at the same time operating an adjacent counter. After a predetermined time, the exchange may again break in, operating the marginal relay and causing a further registration. In an alternative arrangement, the ratchet wheel may rotate the counter. To avoid ringing a subscriber who has left his call and not replaced his receiver, the ratchet wheel may be provided with a second contact arm which requires several impulses to bring it into circuit for restoring the line. Another Provisional Specification describes a modification in which the charge wheel consists of a pivoted wheel provided with figures, and having a metal contact sector near its periphery, whilst adjacent to the wheel and on the same axis is a switch arm having a pointer attached, moving over the sector.