Polarity responsive circuit for telephone systems

Claim 2

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a plurality of unidirectional conducting means, mode control means for connecting said unidirectional condUcting means between the input and output terminals to establish at said output terminals a DC voltage having a fixed polarity when said mode control means is in a first operative state and for connecting said unidirectional conducting means between the input and output terminals to establish an AC voltage at said output terminals when said mode control means is in a second operative state, a plurality of controllable switching means, means for connecting said controllable switching means in series with respective unidirectional conducting means, means for controlling the conduction of said controllable switching means in accordance with the voltage at the input terminals, AC voltage sensing means, means for connecting said sensing means to the input terminals and means for connecting said sensing means to said mode control means to control the operative state of said mode control means in accordance with the presence and absence of AC ringing voltage at said input terminals.

Claim 3

A polarity responsive switching circuit as set forth in claim 1 in which said means for connecting said sensing means to the input terminals includes first and second sensing leads, a voltage divider, means for connecting said voltage divider across the input terminals, and means for connecting said sensing leads between ground and said voltage divider.

Claim 4

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a rectifying circuit having AC input means and DC output means and including a plurality of unidirectional conducting means, means for connecting the AC input means of said rectifying circuit to the input terminals of the switching circuit, means for connecting the DC output means of said rectifying circuit to the output terminals of said switching circuit, a plurality of controllable switching means each having a power circuit and a control circuit, means for connecting the power circuits of said controllable switching means in series with respective unidirectional conducting means, means for connecting the control circuits of said controllable switching means to the input terminals of the switching circuit to control the conduction of said controllable switching means in accordance with the polarity of the voltage at said input terminals, said controllable switching means serving to prevent the uncontrolled conduction of said unidirectional conducting means when a source of DC voltage is connected in series with the output terminals of the switching circuit.

Claim 5

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a rectifying circuit having AC input means and DC output means and including a plurality of unidirectional conducting means, means for connecting the AC input means of said rectifying circuit to the input terminals of the switching circuit, means for connecting the DC output means of said rectifying circuit to the output terminals of said switching circuit, a plurality of controllable switching means each having a power circuit and a control circuit, means for connecting the power circuits of said controllable switching means in series with respective unidirectional conducting means, means for connecting the control circuits of said controllable switching means to the input terminals of the switching circuit to control the conduction of said controllable switching means in accordance with the polarity of the voltage at said input terminals, said controllable switching means serving to prevent the uncontrolled conduction of said unidirectional conducting means when a source of DC voltage is connected in series with the output terminals of the switching circuit.

Claim 6

A polarity responsive switching circuit as set forth in claim 3 in which said means for connecting said control circuits to the input terminals includes resistance means and means for connecting said control circuits between the input terminals through said resistance means.

Claim 7

A polarity responsive switching circuit as set forth in claim 4 including means for connecting said resistance means to ground.

Claim 8

A polarity responsive switching circuit as set forth in claim 3 including ringing voltage sensing means, means for bypassing said rectifying circuit, means for connecting said bypassing means between the input and output terminals of the switching circuit, means for connecting said sensing means in bypass control relationship to said bypassing means and means for connecting said sensing means to the input terminals of the switching circuit.

Claim 9

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a rectifying circuit having AC input means and DC output means and including a plurality of unidirectional conducting means, means for connecting the AC input means of said rectifying circuit to the input terminals of the switching circuit, means for connecting the DC output means of said rectifying network to the output terminals of the switching circuit, a plurality of controllable switching means each having first and second power terminals and a control terminal, mEans for connecting the power terminals of said switching means in series with respective unidirectional conducting means, the power terminals of each of said switching means being disposed between the respective unidirectional conducting means and a predetermined one of the input terminals of the switching circuit, means for connecting the control terminal of each of said switching means to the other input terminal of the switching circuit, said switching means being arranged to control the flow of current through said unidirectional conducting means in accordance with the voltage at said input terminals.

Claim 10

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a rectifying circuit having AC input means and DC output means and including a plurality of unidirectional conducting means, means for connecting the AC input means of said rectifying circuit to the input terminals of the switching circuit, means for connecting the DC output means of said rectifying network to the output terminals of the switching circuit, a plurality of controllable switching means each having first and second power terminals and a control terminal, mEans for connecting the power terminals of said switching means in series with respective unidirectional conducting means, the power terminals of each of said switching means being disposed between the respective unidirectional conducting means and a predetermined one of the input terminals of the switching circuit, means for connecting the control terminal of each of said switching means to the other input terminal of the switching circuit, said switching means being arranged to control the flow of current through said unidirectional conducting means in accordance with the voltage at said input terminals.

Claim 11

A polarity responsive switching circuit as set forth in claim 7 in which each of said controllable switching means includes trigger current conducting means having a power circuit and a control circuit, latching current conducting means having a power circuit and a control circuit, means for connecting the control circuit of said trigger current conducting means in series with the power circuit of said latching current conducting means between said first and second power terminals, means for connecting the control circuit of said latching current conducting means in series with the power circuit of said trigger current conducting means between said first and second power terminals and means for connecting the control circuit of said trigger current conducting means to said control terminal.

Claim 12

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a plurality of unidirectional conducting means, mode control means for connecting said unidirectional conducting means to one another to establish a bridge rectifying circuit when said mode control means is in a first operative state and for connecting said unidirectional conducting means to one another to establish a plurality of pairs of inverse parallel connected unidirectional conducting means when said mode control means is in a second operative state, means for connecting said bridge rectifying circuit to said input and output terminals to provide a unidirectional DC voltage at said output terminals when said mode control means is in said first state, means for connecting said inverse parallel connected pairs of unidirectional conducting means to said input and output terminals to provide paths for the flow of AC current therebetween when said mode control means is in said second state, a plurality of controllable switching means, means for connecting said switching means in series with respective unidirectional conducting means, means for connecting said switching means in polarity responsive relationship to said input terminals, AC voltage sensing means for establishing the first operative state of said mode control means in the absence of an AC voltage between said input terminals and for establishing the second operative state of said mode control means in the presence of an AC voltage between said input terminals, and means for connecting said AC voltage sensing means to said input terminals.

Claim 13

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a plurality of unidirectional conducting means, mode control means for connecting said unidirectional conducting means to one another to establish a bridge rectifying circuit when said mode control means is in a first operative state and for connecting said unidirectional conducting means to one another to establish a plurality of pairs of inverse parallel connected unidirectional conducting means when said mode control means is in a second operative state, means for connecting said bridge rectifying circuit to said input and output terminals to provide a unidirectional DC voltage at said output terminals when said mode control means is in said first state, means for connecting said inverse parallel connected pairs of unidirectional conducting means to said input and output terminals to provide paths for the flow of AC current therebetween when said mode control means is in said second state, a plurality of controllable switching means, means for connecting said switching means in series with respective unidirectional conducting means, means for connecting said switching means in polarity responsive relationship to said input terminals, AC voltage sensing means for establishing the first operative state of said mode control means in the absence of an AC voltage between said input terminals and for establishing the second operative state of said mode control means in the presence of an AC voltage between said input terminals, and means for connecting said AC voltage sensing means to said input terminals.

Claim 14

In a polarity responsive switching circuit having a first and a second input terminal and a first and a second output terminal, in combination, first controllable switching means for conducting current from said first input terminal to said first output terminal, second controllable switching means for conducting current from said second output terminal to said second input terminal, third controllable switching means for conducting current from said second input terminal to said first output terminal, fourth controllable switching means for conducting current from said second output terminal to said first input terminal, a plurality of unidirectional conducting means, means for connecting said unidirectional conducting means in series with respective switching means, means for energizing said first and second switching means when said first input terminal is positive from said second input terminal and for energizing said third and fourth swItching means when said second input terminal is positive from said first input terminal.

Claim 15

In a polarity responsive switching circuit having a first and a second input terminal and a first and a second output terminal, in combination, first controllable switching means for conducting current from said first input terminal to said first output terminal, second controllable switching means for conducting current from said second output terminal to said second input terminal, third controllable switching means for conducting current from said second input terminal to said first output terminal, fourth controllable switching means for conducting current from said second output terminal to said first input terminal, a plurality of unidirectional conducting means, means for connecting said unidirectional conducting means in series with respective switching means, means for energizing said first and second switching means when said first input terminal is positive from said second input terminal and for energizing said third and fourth swItching means when said second input terminal is positive from said first input terminal.

Claim 16

A polarity responsive switching circuit as set forth in claim 10 including means for bypassing AC current between said first input terminal and said first output terminal and for bypassing AC current between said second input terminal and said second output terminal, ringing voltage sensing means, means for connecting said sensing means in bypass control relationship to said bypassing means and means for connecting said sensing means to said input terminals.

Claim 17

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a plurality of unidirectional conducting means, means for connecting one terminal of each of said unidirectional conducting means to one of said output terminals, predetermined ones of said last named connecting means including off-on conducting means, a plurality of controllable switching means for connecting the other terminal of each of said unidirectional conducting means to one of said input terminals, actuator means for controlling the conductivity of said off-on conducting means, sensing means for controlling said actuator means in accordance with the presence of an AC voltage at said input terminals, means for connecting said sensing means to said input terminals, said unidirectional conducting means providing a unidirectional DC voltage at said output terminal means when said off-on conducting means is in a first operative state in the absence of AC voltage at said input terminals, and providing an AC voltage at said output terminal means when said off-on conducting means is in a second operative state, in the presence of AC voltage at said input terminals, means for energizing predetermined ones of said switching means when the voltage between said input terminals has one polarity and for energizing predetermined other ones of said switching means when the voltage between said input terminals reverses polarity.

Claim 18

In a polarity responsive switching circuit having a pair of input terminals and a pair of output terminals, in combination, a plurality of unidirectional conducting means, means for connecting one terminal of each of said unidirectional conducting means to one of said output terminals, predetermined ones of said last named connecting means including off-on conducting means, a plurality of controllable switching means for connecting the other terminal of each of said unidirectional conducting means to one of said input terminals, actuator means for controlling the conductivity of said off-on conducting means, sensing means for controlling said actuator means in accordance with the presence of an AC voltage at said input terminals, means for connecting said sensing means to said input terminals, said unidirectional conducting means providing a unidirectional DC voltage at said output terminal means when said off-on conducting means is in a first operative state in the absence of AC voltage at said input terminals, and providing an AC voltage at said output terminal means when said off-on conducting means is in a second operative state, in the presence of AC voltage at said input terminals, means for energizing predetermined ones of said switching means when the voltage between said input terminals has one polarity and for energizing predetermined other ones of said switching means when the voltage between said input terminals reverses polarity.