Monostable switching circuit

Claim 2

A monostable switching circuit for use with a load and a source of operating potential to control current flow through the load, comprising: a bistable electronic switch having a conduction path for connection in circuit with the load and the source of operating potential, said switch having a control terminal responsive to a first polarity trigger signal for placing the path in a first conductive state and responsive to a second polarity trigger signal for placing the path in a second conductive state; means for applying said first polarity trigger signal to said control terminal; and circuit means responsive to an externally supplied control signal and to the conductive state of said path for producing and applying said second polarity trigger signal to said control terminal a predetermined time, which is a function of the value of said externally supplied control signal and is substantially independent of said current flow through said load, after application of said first polarity trigger signal.

Claim 3

The switching circuit recited in claim 1 wherein said bistable electronic switch comprises a gate controlled thyristor switch having anode, cathode and gate terminals, the anode-to-cathode conduction path thereof for connection in series circuit with said load, said gate terminal for receiving said first and second polarity trigger signals and controlling the conductive state of said anode-to-cathode conduction path in accordance therewith said anode terminal being coupled to said circuit means for providing a feedback signal thereto representative of said conductive state of said path.

Claim 4

The switching circuit recited in claim 1 wherein said circuit means comprises: a capacitor; means for applying a charging current to said capacitor in response to said externally supplied control signal, said charging current being in a sense to produce a voltage at the capacitor of said second polarity; threshold conduction means responsive to said second Polarity voltage for forming said second polarity trigger signal in response thereto when said second polarity voltage is of a threshold value and applying said second polarity trigger signal to said control terminal; and further means coupled to said capacitor for continuously providing a discharge path for said capacitor of substantially negligible impedance when said conduction path is in one of said conductive states, said further means effectively opening said discharge path when said conduction path is in the other of its conductive states.

Claim 5

The combination recited in claim 3 wherein said further means comprises: a diode coupled between one end of said conduction path and said capacitor, said diode poled to discharge the capacitor when said conduction path is in said second conductive state.

Claim 6

The combination recited in claim 3 wherein said further means comprises: switch means connected across said capacitor, said switch means being responsive to said second conductive state of said conduction path for discharging said capacitor and to said first conductive state of said conduction path for enabling charging of said capacitor.

Claim 7

The combination recited in claim 3 wherein said threshold conduction means comprises a thyristor having a conduction path connected between said capacitor and said control terminal, the thyristor conduction path being rendered conductive in response to a potential thereacross of said threshold voltage and remaining conductive thereafter for a current flow therethrough of greater than a minimum value.

Claim 8

A monostable switching circuit for controlling current through a load, comprising: a gate controlled switch having a conduction path for connection in series with the load, said switch having a gate terminal responsive to a first polarity trigger signal for placing the path in a first conductive state and responsive to a second polarity trigger signal for placing the path in a second conductive state; means for applying the first polarity trigger signal to said gate terminal for placing said path in said first conductive state; a capacitor; means for applying a charging current to the capacitor in response to an externally supplied control signal in a sense to produce a signal of said second polarity, said charging current being independent of current flow through said switch; threshold conduction means coupled between the capacitor and said gate terminal for conducting the second polarity trigger signal therebetween when the capacitor voltage exceeds a threshold value; and means responsive to the conductive state of the path for discharging the capacitor when the path is in said second conductive state and for enabling charging of said capacitor when said path is in said first conductive state.

Claim 9

A monostable switching circuit for controlling current through a load, comprising: a gate controlled switch having a conduction path for connection in series with the load, said switch having a gate terminal responsive to a first polarity trigger signal for placing the path in a first conductive state and responsive to a second polarity trigger signal for placing the path in a second conductive state; means for applying the first polarity trigger signal to said gate terminal for placing said path in said first conductive state; a capacitor; means for applying a charging current to the capacitor in response to an externally supplied control signal in a sense to produce a signal of said second polarity, said charging current being independent of current flow through said switch; threshold conduction means coupled between the capacitor and said gate terminal for conducting the second polarity trigger signal therebetween when the capacitor voltage exceeds a threshold value; and means responsive to the conductive state of the path for discharging the capacitor when the path is in said second conductive state and for enabling charging of said capacitor when said path is in said first conductive state.

Claim 10

The circuit recited in claim 7 wherein said means responsive to the conductive state of the path comprises: a diode coupled between said capacitor and one end of said conduction path, said diode being poled to discharge said capacitor when said conduction path is in a selected one of said conductive states.

Claim 11

The circuit recited in claim 7 wherein said means responsive to the conductive state of the path comprises a further switch coupled across said capacitor, said further switch being responsive to a selected one of said conductive states of said conduction path for discharging said capacitor.

Claim 12

In combination: first and second circuit points, the first for connection to a load, the second for connection to a source of reference potential a gate controlled switch having an anode-to-cathode conduction path with anode and cathode terminals at the ends thereof, the anode terminal being connected to said first circuit point, the cathode terminal being connected to said second circuit point, said switch having a gate terminal, said gate terminal being responsive to a first polarity trigger signal for placing the anode-to-cathode path of said switch in a fIrst conductive state and responsive to a second polarity trigger signal for placing the anode to cathode path in a second conductive state; means for applying said first polarity trigger signal to said gate terminal for placing said path in said first conductive state; a capacitor having two terminals, one of said terminals connected to said second circuit point; charging means coupled to the other terminal of said capacitor for supplying a charging current thereto in accordance with an externally supplied control signal and in a sense to charge said capacitor to a voltage of said second polarity; threshold conduction means coupled between said other plate of said capacitor and said gate terminal for forming said second polarity trigger pulse when said voltage exceeds a threshold value and applying said second polarity trigger pulse to said gate terminal; means connected to said anode terminal and responsive to the conductive state of said anode-to-cathode path for discharging said capacitor when the path is in said second conductive state and for enabling charging of said capacitor by said charging means when said path is in said first conductive state.

Claim 13

In combination: first and second circuit points, the first for connection to a load, the second for connection to a source of reference potential a gate controlled switch having an anode-to-cathode conduction path with anode and cathode terminals at the ends thereof, the anode terminal being connected to said first circuit point, the cathode terminal being connected to said second circuit point, said switch having a gate terminal, said gate terminal being responsive to a first polarity trigger signal for placing the anode-to-cathode path of said switch in a fIrst conductive state and responsive to a second polarity trigger signal for placing the anode to cathode path in a second conductive state; means for applying said first polarity trigger signal to said gate terminal for placing said path in said first conductive state; a capacitor having two terminals, one of said terminals connected to said second circuit point; charging means coupled to the other terminal of said capacitor for supplying a charging current thereto in accordance with an externally supplied control signal and in a sense to charge said capacitor to a voltage of said second polarity; threshold conduction means coupled between said other plate of said capacitor and said gate terminal for forming said second polarity trigger pulse when said voltage exceeds a threshold value and applying said second polarity trigger pulse to said gate terminal; means connected to said anode terminal and responsive to the conductive state of said anode-to-cathode path for discharging said capacitor when the path is in said second conductive state and for enabling charging of said capacitor by said charging means when said path is in said first conductive state.

Claim 14

The combination recited in claim 10 wherein said means responsive to the conductive state of said anode-to-cathode path comprises a diode coupled at the anode thereof to said other terminal and at the cathode thereof to said anode terminal of said gate controlled switch.

Claim 15

The combination recited in claim 10 wherein said means responsive to the conductive state of said anode-to-cathode path comprises a transistor switch connected across said capacitor, said switch being responsive to a selected one of said conductive states of said anode-to-cathode conduction path for discharging said capacitor.

Claim 16

In combination; a bistable circuit element having a conduction path connected between a point of reference potential and a second circuit point and control electrode means for controlling the conductivity of said path, said bistable circuit normally assuming one of its stable states; means for applying a trigger signal to said control electrode means for switching said circuit element to its other stable state; charge storage means; further means coupled to said charge storage means for continuously providing a discharge path for said charge storage means of substantially negligible impedance when said bistable circuit element is in said one of its stable states, said further means effectively opening said discharge path when said bistable circuit element is in said other stable state; means responsive to the voltage present at said second circuit point when said bistable circuit element is switched to its second state for causing said charge storage means to charge in accordance with an externally supplied control signal; and means responsive to the voltage at said charge storage means reaching a given level for applying a trigger signal to said control electrode means for switching said circuit element back to its initial state.

Claim 17

In combination; a bistable circuit element having a conduction path connected between a point of reference potential and a second circuit point and control electrode means for controlling the conductivity of said path, said bistable circuit normally assuming one of its stable states; means for applying a trigger signal to said control electrode means for switching said circuit element to its other stable state; charge storage means; further means coupled to said charge storage means for continuously providing a discharge path for said charge storage means of substantially negligible impedance when said bistable circuit element is in said one of its stable states, said further means effectively opening said discharge path when said bistable circuit element is in said other stable state; means responsive to the voltage present at said second circuit point when said bistable circuit element is switched to its second state for causing said charge storage means to charge in accordance with an externally supplied control signal; and means responsive to the voltage at said charge storage means reaching a given level for applying a trigger signal to said control electrode means for switching said circuit element back to its initial state.

Claim 18

The combination recited in claim 13 wherein said bistable circuit elements comprise a gate controlled switch having anode, cathode and gate terminals, said anode terminal being connected to said second circuit point, said cathode being connected to said point of reference potential and said gate terminal corresponding to said control means for receiving said trigger signals.

Claim 19

The combination recited in claim 13 wherein said means responsive to the voltage present at said second circuit point comprises: a control terminal for receiving said externally supplied control signal; means coupled between said control terminal and said charge storage means for conducting a charging current therebetween; and wherein said further means comprises: a diode connected between said charge storage means and said second circuit point, said diode being poled to conduct a current therebetween when said bistable circuit element is in said one of its stable states.

Claim 20

The combination recited in claim 13 wherein said means responsive to the voltage present at said second circuit point comprises a control terminal for receiving said externally supplied control signal; means coupled between said control terminal and said charge storage means for conducting a charging current therebetween; and wherein said further means comprises: switch means having a conduction path and a control electrode, said conduction path being connected between said point of reference potential and said charge storage means, said control electrode being coupled to said second circuit point, said conduction path being normally conductive when said bistable circuit element is in said one of its stable states.