Patent GB-1060787-A (GB)
Title: Improvements in and relating to telephone answering machines
Inventor: PAL GEORGE
IPC: H04M1/652
Filed: 1964-09-23
Abstract: 1,060,787. Telephone answering machines. ROBOPHONE Ltd. Sept. 23, 1965. [Sept. 23, 1964], No. 38801/64. Heading H4K. A telephone answering machine which responds to a predetermined sequence of pulses transmitted over the telephone line and replays the stored messages, records a marker signal in the memory on the occurrence of the interrogation signal to indicate, on replay, the point at which the machine should switch back to the waiting condition. During replay the reception of further incoming calls is prevented and the machine may be provided with means whereby if the interrogating caller hangs up during replay the replay is speeded up to reduce the time the machine is unavailable for further calls. In the Figure a ringing signal on lines 9 is detected and a line connection circuit 12 connects a warning announcement from replay device 16 to the line 11. At the end of the warning announcement the line circuit 12 connects the line 11 via the record amplifier 14 to the record head 8 and starts the tape or wire recorder drive motor 5 to allow the caller's message to be recorded. If the caller wishes to interrogate the machine he transmits a predetermined signal, of four groups of pulses, during the time allocated for recording a message. The pulse groups are received by the pulse group detector 15, the first group being fed to counter 22A. After the first group'a gap of 1¢ seconds causes the count stored in 22A to be compared in comparator 23A with a count previously set up by the owner on switch 24A. If the count received is correct, the second group of pulses is fed to the counter 22B which operates in a similar way to enable the following counter. If the received group is incorrect all the preceding counters are reset so that only if the four groups are transmitted correctly does the comparator 23D produce an output. Each comparison operation enables the oscillator 26 for a short time to transmit to the caller a signal indicating the completion of a code group, the signal not differentiating between a correct and an incorrect group. At the end of the correct interrogation signal the oscillator 26 is enabled for a longer period and this signal is recorded on the tape or wire and operates motor reversing switch 6 to drive the recorder motor back to the start of the tape or wire at high speed preparatory to replay, the record amplifier being disabled meanwhile. When the start is reached the transport motor is again reversed and the tape or wire replayed to the line via the amplifier 18 &c. When the oscillator signal recorded on the tape is replayed it is detected by tuned amplifier 17 and causes the line circuit to operate to disconnect the equipment from the line and put the machine in a condition to receive further calls, in addition the motor reverse switch is momentarily operated to back space the tape or wire to a position before the recorded oscillator signal so that it is wiped out by the following recorded message. A circuit is also provided which if the caller hangs up or is otherwise disconnected during the replay, the machine is prevented from responding to further calls until the tape has reached to recorded marker signal and this circuit may also increase the motor speed, so that the machine is unavailable for a shorter period of time, the tuning of the amplifier 17 being adjusted, so that it responds to the speeded up version of the marker signal.