Improvements in or relating to telephone exchange systems

Abstract

Abstract 389,613. Manual exchange systems. ERICSSON TELEPHONES, Ltd., 67, Kingsway, London, WILMAN, C. W. and TRAPP, C. C., Ericsson Telephone Works, Beeston, Nottingham. Jan. 21, 1932, No. 1861. [Class 40 (iv).] An exchange adapted to be worked by a blind operator is characterized by the feature that whenever a line requires attention, a buzzer is sounded and the number of the line is exhibited on a panel in a tangible manner, e.g. in Braille characters. A high-note buzzer indicates a calling condition, while a low-note buzzer indicates a clearing condition. Construction of indicator, Figs. 1 and 2. For each digit to be indicated there are provided four pins 19 adapted to be projected from the panel 11 to form Braille characters by magnets 14. Fig. 3 shows the connections for operating the magnets controlling one set of pins in various combinations by the application of potential to a single wire. A rotary switch DM, Fig. 6, takes up a position characteristic of the line and controls the appropriate magnets for the tens and units digits over separate banks. As an alternative, the switch or a pair of switches may rotate drums bearing the characters into the appropriate position under an aperture in the panel. Operation. When a subscriber calls, the common line relay SA energizes, and closes a circuit for stepping the switch DM into engagement with the line, whereupon relay H energizes, connecting up the high-note buzzer HB and completing circuits for indicating the number of the line. The operator plugs into the calling line, and line relay A energizes ; relay H falls back and removes the number from the panel. On plugging into the wanted line, common sleeve relay SC energizes and the switch DM steps into engagement with this line, whereupon relay H energizes, connecting up the lownote buzzer LB and closing circuits for the indicator. The operator can thus check the number before ringing. Relay D energizes upon reply and disconnects relays SC, H. Release by either party causes the operation. of the corresponding sleeve relay SB or SC, whereupon the low-note buzzer LB gives the clearing signal and the number of the line is indicated. It will be seen that, since relay SB disconnects relays SA, SC and relay SA disconnects relay SC, clearing signals from calling lines have first preference, then calling signals and lastly clearing and checking signals from called lines. A modification using individual' line relays is described.

Inventors

No inventors recorded.

Bibliographic Details