Telephone answering system and apparatus including improved ring responsive circuitry for selectively connecting and isolating the system from the telephone line

Claim 1

In a telephone answering system for responding to telephone messages received over a telephone line and which comprises an announcement storage means and a message storage means and respective associated transducers, and which further comprises first and second means for driving said announcement storage means and said message storage means respectively relative to said transducers for producing a recorded announcement on the telephone line from the announcement storage means during a first time interval in response to an incoming telephone call from a calling party, and for subsequently recording a message from the calling party on said message storage means during a second time interval, and which further includes first control circuit means for activating said announcement storage driving means in response to said incoming telephone call to produce said recorded announcement for transmission over the telephone line to the calling party during the first time interval, second control circuit means coupled to said announcement storage means for activating said message storage driving means at the termination of the announcement so as to initiate the recording of the aforesaid message from the calling party on the message storage means, a transformer having a first, a second and a third winding, and an audio-amplifier having its output connected to the second transformer winding and its input connected to the third transformer winding, means controllably coupling the input of the audio-amplifier to said announcement storage means for introducing the announcement thereon to the telephone line during said first time interval, and means controllably coupling the output of the audio-amplifier to said message storage means for introducing the message received over the telephone line from the calling party to said message storage means during the second time interval; the combination of a ring signal sensing circuit, a relay having normally-open contacts and normally-closed contacts, and further having an energizing coil connected to said ring signal sensing circuit to be actuated thereby to close the normally-open contacts thereof and connect said first winding of said transformer to the telephone line in response to a ring signal received over the line and introduced to said ring sensing circuit, capacitive means coupling said ring sensing circuit through the normally-closed contacts of said relay to the telephone line and presenting relatively low impedance to said ring signal to pass said ring signal to said ring sensing circuit so as to cause said ring sensing circuit to actuate said relay in response to said ring signal; third control circuit means responsive to a change in signal level on the telephone line for controlling said relay to open said normally-open contacts thereof and disconnect said first winding of said transformer from the telephone line and thereby isolate said audioamplifier from the telephone line should communication with the calling party be interrupted during the first or second time interval; capacitive means directly coupling said third control circuit means to said first winding of said transformer and to said normally-open contacts of said relay; and circuit means connected to said first control circuit means and to said third control circuit means to deactivate said ring sensing circuit for the duration of said first time interval whenever said third control circuit means is activated during said first time interval.