Abstract A multi-line key telephone system comprising a plurality of telephone stations each of which has access to a plurality of telephone lines. Individual line-holding circuits are provided, which are connected to or connectable with any one of the individual line circuits and any one of the individual telephone station circuits. Each holding circuit has a resistive coil in series with a reed switch with an equivalent resistance exceeding the resistance of any one telephone station circuit. In parallel to the reed switch in each holding circuit is a circuit path which goes through the respective telephone line key, a common hold key, and the hook switch. In each station operation of the hook switch and depression of a selected line key connects the telephone circuit to a selected telephone line. Subsequently operation of the common hold key electrically completes the said circuit path and so shorts the reed switch, releases the said line key, and then energizes the coil to lock the holding circuit across the said telephone line. Further connection of any telephone circuit to the telephone line sufficiently de-energizes the coil to release the reed switch and disconnect the holding circuit from the telephone line.
In a key telephone set adapted to be connected to a plurality of telephone lines, said telephone set having a telephone circuit, a hook switch, and a plurality of interlocking keys including line keys, one for each telephone line, and a common hold key; a plurality of hold circuits, each one associated with a respective telephone line, each hold circuit comprising: a. a current-actuable holding bridge having an operate current and a release current; the impedance of said bridge being greater than the impedance of the telephone circuit, b. means responsive to the momentary operation of the hold key for connecting the bridge across its associated telephone line, and c. means responsive to the subsequent operation of a line key associated with said telephone line for connecting the telephone circuit across said bridge thereby causing the current through the bridge to decrease to an amount less than said release current and the bridge to be released from the telephone line.
Claim 2
Dependent Claim
160 words
In a key telephone set adapted to be connected to a plurality of telephone lines, said telephone set having a telephone circuit, a hook switch, and a plurality of interlocking keys including line keys, one for each telephone line, and a common hold key; a plurality of hold circuits, each one associated with a respective telephone line, each hold circuit comprising: a. a current-actuable holding bridge having an operate current and a release current; the impedance of said bridge being greater than the impedance of the telephone circuit, b. means responsive to the momentary operation of the hold key for connecting the bridge across its associated telephone line, and c. means responsive to the subsequent operation of a line key associated with said telephone line for connecting the telephone circuit across said bridge thereby causing the current through the bridge to decrease to an amount less than said release current and the bridge to be released from the telephone line.
Claim 3
Dependent Claim
174 words
A holding circuit as defined in claim 1 wherein the holding bridge comprises a relay coil in series with a make contact operable thereby and wherein the hold key comprises a transfer switch of the make-before-break type having center, make and break contacts, the free end of the relay coil being connected to one side of the associated telephone line and connectable through a first make contact of the associated line key and a first make contact of the hook switch to one side of the telephone circuit, the free side of the relay coil make contact being connected to the other side of the incoming telephone line and connectable through a second make contact of the line key, a second make contact of the hook switch and the center and break contact of the transfer switch to the other side of the telephone circuit, the junction of the coil and its associated make contact being connectable through a third make contact of the line key to the make contact of the transfer switch.
Claim 4
Dependent Claim
20 words
A holding circuit as defined in claim 2 wherein said relay coil and associated make contact comprise a reed relay.