Full trunkage intercommunication system with page adaptor

Claim 2

A complete trunkage intercommunication system comprising a plurality of stations, each station including: a. a handset including a transmitter and receiver; b. a signal-receiving circuit; c. a signal-sending circuit; d. selection means for selecting the signal-receiving circuit of a second station; e. a signal device in said signal-receiving circuit operable by electrical signals received by the signal-receiving circuit of another station; f. control means effective when said signal-sending circuit is connected to a signal-receiving circuit of said second station to prevent said signal-receiving circuit from being selected by the selecting circuit of a third station; and g. a page unit connected to each of said stations remote therefrom and actuable by said selection circuit, said page unit when actuated enabling said signal sending circuit to page all other stations whose control circuits are not operative, through the receivers of said other stations.

Claim 3

The unit defined in claim 1 wherein said signal-receiving circuit includes a first and second path, an oscillator stage and said signal device in said first path, said receiver in said second path, and said signal-sending circuit includes a self-latching relay, said selection means being effective when manually operated to establish a circuit from a source of potential through the first path of said selected signal-receiving circuit and to a source of reference potential only if the called station is not connected to a third station, whereupon said self-latching relay of the calling station is energized.

Claim 4

The system defined in claim 1 wherein said page unit includes a switch actuable by said selection means to connect said signal-sending circuit to said speakers in all inactive ones of said plurality of stations, a constant current source in said station, and means connecting said constant current source to said page unit switch, when said page unit is actuated by said selecting means, to maintain said switch in its actuated condition.

Claim 5

The system defined in claim 1 wherein said page unit includes a relay switch and a normally nonconducting transistor said selection means providing a signal to trigger said relay into conduction when said page unit is selected, said station supplying a steady state voltage sufficient to keep said transistor conducting until the page is completed.

Claim 6

The system defined in claim 1 wherein said selection means includes a terminal associated with each other station of said system, a terminal for said page unit, and a signal-receiving terminal, means connecting each of the other of said terminals to the signal-receiving terminal of the station with which they are associated, and means connecting said signal-sending circuit of said first station to the signal-receiving terminal of said second station.

Claim 7

A complete trunkage intercommunication system consisting of a plurality of stations, each station including a handset and handset cradle, a switch means associated with the handset cradle, means for initiating a call signal to a selected one of the other stations of the system when said handset switch means is actuated, means to receive and indicate receipt of a call signal from another station, means associated with said handset cradle switch means to prevent effective receipt of a call signal from a second station when a station has been called by another station and to permit the called station and the calling station to communicate; and a circuit for permitting a called station to communicate with a calling station without actuation of said switch associated with said handset cradle of the called station including: a. a first circuit branch for receiving a call signal from a calling station in parallel with the normal call signal-receiving circuitry Of the called station; b. first switch means in said first circuit branch actuated when a first call signal is received; c. transmitter-receiver means connected to said first switch means and actuated thereby to be placed in the transmit condition when said first switch means is actuated; d. a second circuit branch connected to said first circuit branch by said first switch means when said first switch means is actuated; and e. second switch means in said second circuit branch connected to said transmitter-receiver, said second switch means being actuated by a second call signal after said first switch means is actuated, to place said transmitter-receiver in the receive condition for the duration of said second call signal.

Claim 8

A complete trunkage intercommunication system consisting of a plurality of stations, each station including a handset and handset cradle, a switch means associated with the handset cradle, means for initiating a call signal to a selected one of the other stations of the system when said handset switch means is actuated, means to receive and indicate receipt of a call signal from another station, means associated with said handset cradle switch means to prevent effective receipt of a call signal from a second station when a station has been called by another station and to permit the called station and the calling station to communicate; and a circuit for permitting a called station to communicate with a calling station without actuation of said switch associated with said handset cradle of the called station including: a. a first circuit branch for receiving a call signal from a calling station in parallel with the normal call signal-receiving circuitry Of the called station; b. first switch means in said first circuit branch actuated when a first call signal is received; c. transmitter-receiver means connected to said first switch means and actuated thereby to be placed in the transmit condition when said first switch means is actuated; d. a second circuit branch connected to said first circuit branch by said first switch means when said first switch means is actuated; and e. second switch means in said second circuit branch connected to said transmitter-receiver, said second switch means being actuated by a second call signal after said first switch means is actuated, to place said transmitter-receiver in the receive condition for the duration of said second call signal.

Claim 9

The unit defined in claim 6 wherein said circuit further includes delay means in said first circuit branch to delay actuation of said first switch means for a chosen time after receipt of said call signal.

Claim 10

The unit defined in claim 6 wherein said circuit is connected to said station through said switch means associated with said handset cradle only when said handset is in the handset cradle.

Claim 11

The unit defined in claim 6 wherein said second switch means is actuated by a signal having a voltage magnitude less than the magnitude of a call signal produced by a station when such station is not communicating with another station.

Claim 12

The unit defined in claim 6 wherein lifting of said handset will disconnect said circuit through actuation of said switch means associated with said handset cradle, said circuit being arranged and selected so that the signal level required for actuation will prevent reconnection when said switch associated with said handset cradle is returned to its normal condition unless a subsequent call is completed to said station.