Control arrangement for hands-free telephone operation

Claim 2

A station control arrangement for a loudspeaker-microphone assembly to automatically engage an incoming call connection in response to the receipt of ringing signals at a called station comprising means responsive to the detection of said signals for generating an enabling signal, means operative for connecting said assembly to the call connection associated with said ringing signals, a semiconductor switching device activated by said enabling signal for connecting a first portion of an operating circuit path to said connecting means, means under control of the called station for establishing a remainder portion of said operating circuit path to operate said connecting means, and means for holding said switching device in an activated state for the duration of said call connection.

Claim 3

The invention recited in claim 1 further including a telephone set having switchhook contacts whose operative state indicate the off-hook and on-hook status of said set, and said contacts being connected to said establishing means for releasing said connecting means when the switchhook status is off-hook.

Claim 4

The invention recited in claim 2 wherein said establishing means comprises a transistor switching element having a collector, base and emitter, said collector being in series connection with said connecting means, said emitter being connected to ground, and said transistor base being connected to said swithhook contacts which control the conductive state of said element and thereby the remainder portion of said operating circuit path.

Claim 5

The invention set forth in claim 1 further including a warning tone generator capable of producing a distinctive audible signal via said assembly, and means under control of said connecting means for connecting said generator to said call connection for a predetermined period following the operation of said connecting means.

Claim 6

The invention set forth in claim 1 wherein said switching device is a PNPN transistor device having a base electrode for activating said device and two emitter electrodes having a low impedance path therebetween when said device is activated, said first portion of said circuit path comprising said emitter electrodes one of which connects to said connecting means and the other one of which connects to said holding means, and said base electrode is connected to said generating means.

Claim 7

The invention set forth in claim 1 further including a common circuit comprising means for controlling the connection of a plurality of speaker-microphone assemblies to said call connection, individual telephone sets associated with each one of said assemblies being connectable to said call connection, means for determining a connection of at least two of said telephone sets to said call connection, and means controlled by said determining means for de-activating said switching device when at least two sets are connected to said call connection.

Claim 8

The invention set forth in claim 6 wherein said de-activating means is connected in series relation with said holding means, and includes devices for momentarily opening a first portion of said operating circuit path.

Claim 9

In a communication arrangement, a plurality of key stations each including a telephone set and a hands-free communicating assembly which incorporates a microphone and loudspeaker, a dial selective intercom system connected to each of said stations having a common transmission path for interconnecting said stations, said system including a station signaling circuit responsive to dialed digits for selectively alerting any one of said stations to a call connection, a control circuit associated with each station being responsive to said signaling circuit for connecting a communicating assembly at a called on of said stations to said transmission path, said control circuit being characterized by a semiconductor switching device activated by said signaling circuit and maintained in an activated state by the supervisory state of a calling one of said stations, and said device is effective to de-activate said assembly when the set at the called station is off-hook and to subsequently re-activate said assembly when said set at the called station is on-hook.

Claim 10

In a communication arrangement, a plurality of key stations each including a telephone set and a hands-free communicating assembly which incorporates a microphone and loudspeaker, a dial selective intercom system connected to each of said stations having a common transmission path for interconnecting said stations, said system including a station signaling circuit responsive to dialed digits for selectively alerting any one of said stations to a call connection, a control circuit associated with each station being responsive to said signaling circuit for connecting a communicating assembly at a called on of said stations to said transmission path, said control circuit being characterized by a semiconductor switching device activated by said signaling circuit and maintained in an activated state by the supervisory state of a calling one of said stations, and said device is effective to de-activate said assembly when the set at the called station is off-hook and to subsequently re-activate said assembly when said set at the called station is on-hook.

Claim 11

In an intercom telephone system having an intercom cable, a station control arrangement for a station equipped with a telephone set, hands-free loudspeaker and microphone device comprising means responsive to detection of a ringing signal for generating an enabling signal, semiconductive memory switch means connected to said generating means and initially enabled by said signal, means operative exclusively when said switch means is enabled for connecting said lougspeaker and microphone device to the intercom cable, first circuit means enabled when the telephone set is on-hook both for holding said memory switch means enabled in the absence of said signal as well as for maintaining the operative state of said connecting means, and means effective when said telephone state is off-hook for rendering said connecting means inoperative while said memory switch means is held enabled.

Claim 12

In an intercom telephone system having an intercom cable, a station control arrangement for a station equipped with a telephone set, hands-free loudspeaker and microphone device comprising means responsive to detection of a ringing signal for generating an enabling signal, semiconductive memory switch means connected to said generating means and initially enabled by said signal, means operative exclusively when said switch means is enabled for connecting said lougspeaker and microphone device to the intercom cable, first circuit means enabled when the telephone set is on-hook both for holding said memory switch means enabled in the absence of said signal as well as for maintaining the operative state of said connecting means, and means effective when said telephone state is off-hook for rendering said connecting means inoperative while said memory switch means is held enabled.

Claim 13

An intercom telephone system having an intercom cable, a plurality of stations, at least certain of said stations including a telephone set and hands-free microphone and loudspeaker devices, a plurality of hands-free control circuits, one said control circuit being associated with each of said stations including hands-free microphone and loudspeaker devices, and a station common circuit connected to all said control circuits, each of said control circuits including means responsive to detection of a ringing signal designating the associated station for generating an enabling signal, semiconductive memory switch means connected to said generating means to be enabled by said enabling signal, means operative foor connecting the loudspeaker and microphone devices of said associated station to said intercom cable, first circuit means including second switch means enabled when the associated telephone set is on-hook for maintaining said memory switch means enabled, said first circuit means including said connecting means, and second circuit means for maintaining said memory switch means enabled when said associated telephone set is off-hook, said second circuit means being distinct from said second switch means and said connecting means; and said station common circuit including means responsive to the presence of a call on said intercom cable for connecting a further enabling signal to said semiconductive memory switch means of all of said control circuits.

Claim 14

An intercom telephone system having an intercom cable, a plurality of stations, at least certain of said stations including a telephone set and hands-free microphone and loudspeaker devices, a plurality of hands-free control circuits, one said control circuit being associated with each of said stations including hands-free microphone and loudspeaker devices, and a station common circuit connected to all said control circuits, each of said control circuits including means responsive to detection of a ringing signal designating the associated station for generating an enabling signal, semiconductive memory switch means connected to said generating means to be enabled by said enabling signal, means operative foor connecting the loudspeaker and microphone devices of said associated station to said intercom cable, first circuit means including second switch means enabled when the associated telephone set is on-hook for maintaining said memory switch means enabled, said first circuit means including said connecting means, and second circuit means for maintaining said memory switch means enabled when said associated telephone set is off-hook, said second circuit means being distinct from said second switch means and said connecting means; and said station common circuit including means responsive to the presence of a call on said intercom cable for connecting a further enabling signal to said semiconductive memory switch means of all of said control circuits.

Claim 15

An intercom telephone system in accordance with claim 10 wherein said station common circuit further includes second semiconductive memory switch means, means responsive to a broadcast signal for enabling said second semiconductive memory switch means, and means responsive to enabling said second semiconductive memory switch means and any station priorly in hands-free operation having its telephone set go off-hook for momentarily removing said further enabling signal from said semiconductive memory switch means of all of said control circuits.

Claim 16

An intercom telephone system in accordance with claim 11 wherein said momentary removing means includes means for detecting the off-hook status of a telephone set of a station priorly in hands-free operation, a relay connected to said second semiconductive memory switch means, means connected to said detecting means for inhibiting conduction through said relay, and contact means of said relay interrupting said further enabling signal.