Key telephone intercom circuit

Claim 2

A key telephone arrangement for operation with a first and second key telephone set comprising a nonlocking pickup key associated with said first set adapted to furnish all call functions relating to the extension of an intercom connection between said sets, means responsive during a first operation of said key for energizing a signal at said second set for the duration of said key depression, means responsive to said energizing means when said key is depressed for establishing said intercom connection between said sets, and means operative when said key is restored to its non-operated state for transferring the control of said establishing means from said energizing means to a circuit responsive to a second operation of said key, and said circuit being responsive to said second operation of said key for releasing said establishing means to terminate said intercom connection.

Claim 3

The invention in accordance with claim 1 further comprising a speakerphone associated with said first set, means included in said energizing means for enabling said speakerphone upon the operation of said establishing means, and means for maintaining said speakerphone in its enabled state responsive to said first set remaining in an on-hook state, said maintaining means including means for disabling said speakerphone upon said second operation of said key.

Claim 4

The invention in accordance with claim 2 further comprising means responsive to said first set being changed to an off-hook state during said intercom connection for disabling said maintaining means.

Claim 5

A key telephone arrangement for providing an intercom connection between a first key telephone set equipped with a speakerphone and a second key telephone set comprising a nonlocking intercom key on said first set, a first operation of said key causing the establishment of said intercom connection and a second operation of said key causing the termination of said intercom connection, and a bistable relay circuit associated with said first set, said relay circuit normally being in a first state and changing to a second state responsive to a first operation of said keY, and said relay circuit being returned to said first state responsive to a second operation of said key, said relay circuit comprising a first relay means being operated in response to and for the duration of a first operation of said key, said first relay means including first contact means for energizing said speakerphone upon said first set being on-hook at the time of said first operation of said key, and second contact means for energizing a signal at said second set indicating said intercom call.

Claim 6

A key telephone arrangement for providing an intercom connection between a first key telephone set equipped with a speakerphone and a second key telephone set comprising a nonlocking intercom key on said first set, a first operation of said key causing the establishment of said intercom connection and a second operation of said key causing the termination of said intercom connection, and a bistable relay circuit associated with said first set, said relay circuit normally being in a first state and changing to a second state responsive to a first operation of said keY, and said relay circuit being returned to said first state responsive to a second operation of said key, said relay circuit comprising a first relay means being operated in response to and for the duration of a first operation of said key, said first relay means including first contact means for energizing said speakerphone upon said first set being on-hook at the time of said first operation of said key, and second contact means for energizing a signal at said second set indicating said intercom call.

Claim 7

The invention in accordance with claim 4 wherein said relay circuit further comprises second relay means operated in response to said first key operation, said second relay means including third contact means for establishing a talking path between said sets.

Claim 8

The invention in accordance with claim 5 wherein said relay circuit comprises third relay means operated in response to said second relay means being operated and said first relay means being released following said first operation of said key, said third relay means remaining operated until said key is released following said second operation of said key, and said third relay means including fourth contact means for preventing the energization of said signal upon said second operation of said key.

Claim 9

The invention in accordance with claim 6 wherein said second relay means further comprises fifth contact means for energizing a visual signal at said first and said second sets indicating the establishment of said intercom call.

Claim 10

The invention in accordance with claim 7 wherein said first relay means comprises sixth contact means for deenergizing said speakerphone upon said second operation of said key to terminate said intercom call.

Claim 11

The invention in accordance with claim 8 further comprising means at said first set responsive to said first set being taken off-hook prior to establishment of said intercom call for blocking said second contact means from energizing said speakerphone, and for deenergizing said speakerphone when said first set is taken off-hook during said intercom call.

Claim 12

A key telephone arrangement for connection to a first telephone set equipped with a nonlocking key and a speakerphone and to a second telephone set for providing an intercom connection between said sets, said arrangement comprising first relay means operated in response to a first depression of said key to cause establishment of said intercom connection and operated in response to a second depression of said key to cause termination of said intercom connection, said first relay means including first contact means for sending a signal to said second set indicating said intercom connection, second contact means causing said speakerphone to be energized responsive to said first telephone set being in an on-hook condition, and third contact means closed when said first relay means are released following said first depression of said key to maintain said speakerphone in its energized condition, second relay means operated by said second contact means and including fourth contact means for holding said second relay means operated after said first relay means are released following said first depression of said key, fifth contact means for establishing a talking path between said telephone sets, sixth contact means jointly responsive with said second contact means to complete an energizing path for said speakerphone, and seventh contact means causing said first contact means to be locked out so that said signal is not sent to said second set in response to said second depression of said key, and third relay means operated jointly responsive to said first relay means being released and said second relay means being operated during said second depression of said key and including eighth contact means for opening said speakerphone energizing path to block energization of said speakerphone by said second contact means upon said second depression of said key, and ninth contact means causing said third Relay means to be released upon the release of said key following said second depression thereof.

Claim 13

A key telephone arrangement for connection to a first telephone set equipped with a nonlocking key and a speakerphone and to a second telephone set for providing an intercom connection between said sets, said arrangement comprising first relay means operated in response to a first depression of said key to cause establishment of said intercom connection and operated in response to a second depression of said key to cause termination of said intercom connection, said first relay means including first contact means for sending a signal to said second set indicating said intercom connection, second contact means causing said speakerphone to be energized responsive to said first telephone set being in an on-hook condition, and third contact means closed when said first relay means are released following said first depression of said key to maintain said speakerphone in its energized condition, second relay means operated by said second contact means and including fourth contact means for holding said second relay means operated after said first relay means are released following said first depression of said key, fifth contact means for establishing a talking path between said telephone sets, sixth contact means jointly responsive with said second contact means to complete an energizing path for said speakerphone, and seventh contact means causing said first contact means to be locked out so that said signal is not sent to said second set in response to said second depression of said key, and third relay means operated jointly responsive to said first relay means being released and said second relay means being operated during said second depression of said key and including eighth contact means for opening said speakerphone energizing path to block energization of said speakerphone by said second contact means upon said second depression of said key, and ninth contact means causing said third Relay means to be released upon the release of said key following said second depression thereof.