Patent GB-1322181-A (GB)
Title: Message taking devices testing of apparatus
IPC: H04M1/65
Filed: 1969-08-14
Abstract: 1322181 Substation apparatus N G WALLACE 10 Nov 1970 [14 Aug 1969 16 June 1970] 40761/69 and 29186/70 Heading H4K In a telephone answering and message taking device adapted to print dialled digits on a record medium, of the type in which an indexing means operated once for each dialled digit increments the record medium and causes a digit to be printed, the indexing means also responds to incoming ringing pulses before the call is answered and increments a cam until it closes a switch connecting an impedance across the line. In one form as described a subscriber requiring automatic answering service switches the answering device into the telephone line to replace his normal substation. This switching could however be effected automatically if the subscriber fails to respond before a predetermined number of rings. Alternatively the answering device could be the sole termination of a subscriber's line. In the event of an incoming call (assuming the answering device to be already connected to the line) each burst of ringing tone is detected by a transistor circuit and triggers a monostable oscillator to produce a square wave pulse. Each pulse operates an " A " relay and a " B " relay (of an " A ", " B " and " C " relay arrangement). Each operation of the B relay energizes on release of that relay a magnet 12 displacing a shaft 13 to the left against the action of a spring 14. A pawl 7 carried by the shaft and a non-return pawl 8 rotate by one tooth at a time a ratchet wheel 6 coupled to a drive roller 4 and a cam 20. With each displacement of the shaft 13 the drive roller 4 co-operating with a pinch roll 5 advances a paper tape 3 and an abutment 18 operates a print hammer 15. After a predetermined revolution of the wheel 6 the cam 20 operates microswitches N1, N2 which connect a 1K resistor across the telephone line to simulate lifting the handset, enables a transistor oscillator which generates a tone which is transmitted to the caller as a request for him to dial a message and enables a transistor/capacitor timer which times out if no message is received and resets the apparatus. If a dialled message is received, the A relay operates for each impulse stepping a type wheel 8 co-operating with a print roller 11 by one step. When an interdigit pause is reached the B relay operates the magnet 12 as for tone signals causing the print hammer 15 to print the setting of the type wheel 9 on the paper tape and the drive roller 4 to advance the tape for the next digit. The " C " relay releases during each interdigit pause and when the magnet 12 has operated and released a half wave rectified 24 V A.C. signal is applied to the printer to reset the print wheel for the next digit. The printer is stated to be of known type. Special service.-The exchange could be provided with equipment to which a caller could gain access by dialling a special number, which is arranged to convert dial pulses into ultrasonic pulses which could be transmitted over an engaged subscriber line and operate a printer at the substation via a suitable demodulator without interfering with the existing call.