Privacy and seizure control circuit for a remote station dictating system

Claim 2

A remote unit for controlling a central mechanism of a system of the type having a plurality of remote units connected to at least one common terminal at the central mechanism, the remote unit comprising at least one control circuit, first electronic switch means connected in series between the control circuit and the common terminal, means at said central mechanism for supplying a first biasing voltage to said first electronic switch means to thereby selectively bias the first electronic switch means into its conductive state, means responsive to the conductive state of the first electronic switch means for supplying a second biasing voltage to maintain the first electronic switch means in its conductive state, means at said central mechanism responsive to the conductive state of the first electronic switch to disable the means for supplying the first biasing voltage when the first electronic switch means becomes conductive, and means for selectively disabling the means for supplying the second biasing voltage.

Claim 3

A remote unit as recited in claim 1 wherein the first electronic switch means includes a first semiconductor devIce having a first electrode, a second electrode and a first control electrode, the means for applying the first biasing voltage includes a first voltage source of a predetermined polarity, means for applying the first biasing voltage to the first electrode, first resistance means connected between the first electrode and the first control electrode and means connecting the first control electrode to the common terminal, the means for supplying the second bias voltage includes a second semiconductor device having a third electrode, a fourth electrode, and a second control electrode, a second voltage source having a polarity opposite to that of the first voltage source, second resistance means connected between the second electrode and the second voltage source, the second control electrode being connected to the second electrode, the third electrode being connected to the second resistance means and the fourth electrode being connected to the first control electrode, and the means for selectively disabling the means for supplying the second biasing voltage includes a switch connected in series between the first electrode and the common terminal.

Claim 4

In a dictating station of a record/playback system of the type having a plurality of dictating stations, all of the dictating stations being connected to at least one common terminal at a record/playback unit and each dictating station having at least one circuit for selectively controlling the record/playback unit, a privacy and seizure circuit comprising first electronic switch means connected in series circuit between the control circuit and the common terminal, first means at said record/playback unit for selectively applying a first bias voltage of a predetermined polarity to the first electronic switch means to make it become substantially conductive, second means at said record/playback unit for supplying a second bias voltage of the opposite polarity, second electronic switch means responsive to the conductive state of the first electronic switch means and supplied with the second bias voltage for supplying the second bias voltage to the first electronic switch means to maintain it in its substantially conductive state when the first electronic switch means is made substantially conductive by the first bias means, and means at said record/playback unit responsive to the conductivity of said first electronic switch means for removing said first bias voltage from said first electronic switch means.

Claim 5

In a dictating station of a record/playback system of the type having a plurality of dictating stations, all of the dictating stations being connected to at least one common terminal at a record/playback unit and each dictating station having at least one circuit for selectively controlling the record/playback unit, a privacy and seizure circuit comprising first electronic switch means connected in series circuit between the control circuit and the common terminal, first means at said record/playback unit for selectively applying a first bias voltage of a predetermined polarity to the first electronic switch means to make it become substantially conductive, second means at said record/playback unit for supplying a second bias voltage of the opposite polarity, second electronic switch means responsive to the conductive state of the first electronic switch means and supplied with the second bias voltage for supplying the second bias voltage to the first electronic switch means to maintain it in its substantially conductive state when the first electronic switch means is made substantially conductive by the first bias means, and means at said record/playback unit responsive to the conductivity of said first electronic switch means for removing said first bias voltage from said first electronic switch means.

Claim 6

A privacy and seizure control circuit for a dictating station as recited in claim 3 further comprising a first diode, a first, a second, and a third resistor and a third switch means having two terminals, wherein the first electronic switch means includes a first transistor of one conductivity type having collector and emitter electrodes one of which is connected to one terminal of the third switch means, its base electrode connected through the first resistor to the common terminal, and the other of its collector and emitter electrodes connected to one lead of the second resistor, the third resistor being connected between the base electrode of the first transistor and the one terminal of the third switch, wherein the second bias means includes a voltage source connected to the other lead of the second resistor, and wherein the second electronic switch means includes a second transistor of a conductivity type opposite to that of the first transistor and having collector and emitter electrodes one of which is connected to the base electrode of the first transistor and the other of its collector and emitter electrodes connected to the voltage source of the second bias means, and its base electrode connected to the of the collector and emitter electrodes of the first transistor which is connected to the second resistor, the first diode being connected between the other terminal of the third switch means and the common terminal with its polarity oriented such that current which passes through the first transistor and Third switch means is passed through the first diode of the common terminal, the first bias means including a first bias voltage source which is connected to the terminal of the third switch means which is connected to the first diode.

Claim 7

A privacy and seizure control circuit for a dictating station as recited in claim 4 further comprising means responsive to the flow of current from the second bias means through the first transistor for disabling the first biasing means.

Claim 8

In a record/playback system of the type having a plurality of remote dictating stations connected to at least one common terminal at a central record/playback unit, each remote dictating station including at least on separate circuit for controlling the record/playback unit, a privacy and seizure control circuit comprising in each remote dictating station a first switch connected between the control circuit of each dictating station and the common terminal, second electronic switch means connected between the first switch and the control circuit, first bias means within the central record/playback unit for applying a first bias voltage of a predetermined polarity through the first switch to the second electronic switch means to make it substantially conductuve, second bias means within the central record/playback unit for supplying to the second electronic switch means a second bias voltage of polarity opposite to that of the first bias voltage to maintain it in a substantially conductive state, third electronic switch means responsive to the conductive state of the second electronic switch means and connected between the second bias means and the second electronic switch means for supplying the second bias voltage to the second electronic switch means when the second electronic switch means is made conductive by being connected through the closing of the first switch to the first bias means.

Claim 9

In a record/playback system of the type having a plurality of remote dictating stations connected to at least one common terminal at a central record/playback unit, each remote dictating station including at least on separate circuit for controlling the record/playback unit, a privacy and seizure control circuit comprising in each remote dictating station a first switch connected between the control circuit of each dictating station and the common terminal, second electronic switch means connected between the first switch and the control circuit, first bias means within the central record/playback unit for applying a first bias voltage of a predetermined polarity through the first switch to the second electronic switch means to make it substantially conductuve, second bias means within the central record/playback unit for supplying to the second electronic switch means a second bias voltage of polarity opposite to that of the first bias voltage to maintain it in a substantially conductive state, third electronic switch means responsive to the conductive state of the second electronic switch means and connected between the second bias means and the second electronic switch means for supplying the second bias voltage to the second electronic switch means when the second electronic switch means is made conductive by being connected through the closing of the first switch to the first bias means.

Claim 10

A privacy and seizure control circuit for a record/playback system as recited in claim 6 and further comprising, in the central record/playback unit, fourth electronic switch means responsive to the flow of current from the second bias means to the second electronic switch means for activating the central record/playback unit and for disabling the first bias means as long as the second electronic switch is in its conductive state.

Claim 11

A dictating system having a central record/playback unit and a plurality of remote dictating stations, each of said dictating stations being connected to said central unit, apparatus for permitting a single dictating station to seize said central unit, comprising first biasing means at said central unit for extending a first bias voltage simultaneously to all of said remote dictating stations; second biasing means at said central unit for extending a second bias voltage simultaneously to all of said remote dictating stations; an electronic switch at each of said dictating stations and adapted to respond to said first bias voltage to be rendered conductive; selective means at each of said dictating stations, each selective means being responsive to the actuation of its associated dictating station to supply said first bias voltage to said electronic switch; and means at said central unit responsive to the conductivity of an electronic switch to simultaneously remove the first bias voltage extended to all of said dictating stations and to extend the second bias voltage to all of said dictating stations, said second bias voltage maintaining said conductive electronic switch in its conductive state and preventing the remaining dictating stations from being rendered conductive.

Claim 12

A dictating system having a central record/playback unit and a plurality of remote dictating stations, each of said dictating stations being connected to said central unit, apparatus for permitting a single dictating station to seize said central unit, comprising first biasing means at said central unit for extending a first bias voltage simultaneously to all of said remote dictating stations; second biasing means at said central unit for extending a second bias voltage simultaneously to all of said remote dictating stations; an electronic switch at each of said dictating stations and adapted to respond to said first bias voltage to be rendered conductive; selective means at each of said dictating stations, each selective means being responsive to the actuation of its associated dictating station to supply said first bias voltage to said electronic switch; and means at said central unit responsive to the conductivity of an electronic switch to simultaneously remove the first bias voltage extended to all of said dictating stations and to extend the second bias voltage to all of said dictating stations, said second bias voltage maintaining said conductive electronic switch in its conductive state and preventing the remaining dictating stations from being rendered conductive.