Patent GB-190310236-A (GB)
Title: Improvements relating to Telephone Systems
Inventor: ANDRIANO ALBERT KOCH
Filed: 1903-05-05
Granted: 1904-07-05
Abstract: 10,236. Lake, H. H., [Andriano, A. K.]. May 5. Telephone s y s - tems ; telephones ; telephone c a l l s. -Relates to intercommunication systems, in which the primary circuit of the station calling up is broken until a complete circuit is obtained between the two stations, a buzzer sounding in the receiver of any station attempting to communicate with either of the two stations which are talking. The primary circuit at the calling-instrument is also broken until the desired circuit is obtained. Both wall and table telephones are described. Fig. 1 shows an instrument in which the receiver arm q cannot close the usual automatic switch contacts 2, 3 until the electromagnet 12 in the calling- circuit has been energized, whereupon its armature-lever 9 is attracted, the pin 10 at its lower end slips underneath the narrow extremity of a locking-lever 4, and the spring 6 pushes this lever downwards and away from the contact spring, which, normally, it so displaces that, were the arm q to rise, it would not bridge the contacts 2, 3. When the switch arm g is moved off its home contact c on to one of the line contacts c', the ratchet-wheel g', the pin 7 on the pawl p, and the tail of the lever 4 cooperate to lift the lever, displace.the contact 2, and allow the pin 10 to lock the parts in this position until the ringing- circuit is completed, the conditions for which are that, at the calling-station, the arm g should be at the desired contact and the key x depressed, while at the station called, the arm g must be upon its home contact. The circuit can be traced in Fig. 13, where station A is calling station B, and from the ringing-battery k, the current passes through the return battery-wire v, the contacts 39, 18 at station A, electromagnet 12, and switch arm g to the line-wire w, and at station B by a similar reversed path to the key contact 19, and thence by the leads 21, 20 and hook-operated contacts 23, 22 now closed to the ball t and common return wire w<1>. The contact arm g is, by means of the lever 48, spring 50, and the rack shown, locked on its home contact until freed by the finger 51 when the receiver is removed from its hook and the arm q rises; and, upon replacing the receiver, the descent of the pivoted arm 78 trips the pawl p and allows the switch arm to be returned to the same position by a spring. Fig. 12 shows a modified instrument adapted for an individual return-wire system, in which the selecting-switch has two arms g, r, which make contact with the two line-wires, and the electromagnet 12<1> controls, through the lever 4 and locking-lever 9, the contacts 2<1>, 3<1>, which are distinct from the automatic switch contacts d, e. The electromagnet is put in or out of the ringing-circuit by an arm 27, which is brought against the surface 28 as the receiver arm falls, and against the surface 29 as it rises, so that the ringing-key must be pressed before the receiver is removed. If, however, the ringing-circuit is energized while the receiver is off, the circuit is completed through the bracket of the electromagnet, the locking-lever, and the stop 36, which parts co-operate as an interrupter producing a buzzing sound, which, by suitable wiring, is heard in the receiver and indicates that the station for which the contact arm is set is in operation. When the lever 4 is against the contact 2<1> the contacts 41, 42 are closed ; there is then connection between the atop 36 and the secondary of the induction coil, whereby the receiver and transmitter are useless after the arm g is moved from its home contact, until a ringing- circuit is obtained. In the table telephone, Fig. 10, the switch arm is rotated over circularlyarranged contacts by means of a spindle 68 and gearing. When the locking-lever 9<a> is attracted to the magnet 12<b>, the pin 10<a> drops into the notch 13 of the lever 4<a>, and the springs 2<b>, 3<b> close the primary circuit, this circuit being closed and the switch arm locked on its home contact while the receiver is on its hook. For this purpose, pivoted dogs 52, 64, Fig. 9, are spring- pressed against the spur-wheel 67, and controlled by linkwork from the receiver, which depresses or releases a plate 56 having a slot actuating the tail 55 of a lever 54 controlling the dogs. Latches 81, 82 on the bottom plate hold the pawls out of gear during the return movement of the switch, but are thrown out of gear by pins when the home contact is reached. Similar means to those used in the wall instrument are provided for breaking the primary-circuit contacts upon replacing the receiver ; and, to prevent moving the switch arm to "cut-in " without previously obtaining a ringing-circuit, the linkwork, operated by the hooked lever 74, displaces the lever 4<a>. A dialplate 86 and sight-opening are provided for determining the line contact when setting.