Deflection system for cathode-ray tubes

Claim 2

A deflection system For a cathode-ray tube comprising: a deflection coil connected across a pair of voltage supply terminals, a current amplifier between one end of said coil and one of the supply terminals to vary the current in said coil, means for applying a controlling input signal to said current amplifier whereby the current in said coil is varied, an energy-storing inductor connected in series with said coil and the other of the supply terminals, a further current amplifier connected to said one of supply terminal and to said coil remote from the connection with the first said current amplifier, and a control circuit responsive to the potential at the said one end of said coil to control the conduction of said further current amplifier, whereby an increase in current through the first said current amplifier resulting in the potential at the said one end of said coil passing beyond a predetermined level is detected by said circuit which then causes said further current amplifier to conduct less strongly.

Claim 3

A deflection system according to claim 1, wherein said coil has a center tap which is connected through the inductor to said other supply terminal.

Claim 4

A deflection system according to claim 2, wherein there are two current amplifiers connected respectively between the two opposite ends of said coil and the said one of the supply terminals.

Claim 5

A deflection system according to claim 3, wherein separate control circuits, individual to each of said two current amplifiers, are connected to said further amplifier to control the same in response to the potentials at the two opposite ends of said coil.

Claim 6

A deflection system according to claim 3, wherein a single control circuit is connected through an ''''OR'''' gate to said further amplifier to control the same, whereby both the potentials at the two opposite ends of said coil are applied to the single control circuit.

Claim 7

A deflection system according to claim 1, further including a switching regulator circuit connected between said inductor and said other supply terminal, whereby the switching regulator circuit passes current from the voltage supply to said inductor, when energy is withdrawn therefrom.

Claim 8

A deflection system according to claim 6, wherein said switching regulator circuit comprises a resistor, a switching transistor, and a switching control circuit responsive to changes in potential drop across said resistor, said switching transistor being connected between said resistor and said other supply terminal.

Claim 9

A deflection system according to claim 7, wherein a shunt diode is provided to supply current to said inductor until said switching transistor switches on, said shunt diode being connected between the said one supply terminal and the supply side of said resistor.

Claim 10

A deflection system according to claim 1, wherein the current amplifiers are junction transistors.

Claim 11

A deflection system for a cathode-ray tube comprising: a deflection coil connected from a center tapping thereof to a first of two supply terminals, two junction transistor current amplifiers connected between the ends of said coil and a second of said two supply terminals, means for applying a controlling input signal to said two junction transistors whereby the current in said coil is varied, an energy-storing inductor connected in series with said center tapping and said first supply terminal, a further junction transistor current amplifier connected between said second supply terminal and said center tapping, a control circuit responsive to the collector potentials of said two junction transistors which is connected to the base of said further junction transistor to reduce the conduction thereof when either of said collector potentials crosses a threshold value, whereby an increase in current through either of said two junction transistors resulting in the potential at the respective end of said coil passing beyond said threshold value is detected by said control ciRcuit which then causes said further current amplifier to conduct less strongly.

Claim 12

A deflection system for a cathode-ray tube comprising: a deflection coil connected from a center tapping thereof to a first of two supply terminals, two junction transistor current amplifiers connected between the ends of said coil and a second of said two supply terminals, means for applying a controlling input signal to said two junction transistors whereby the current in said coil is varied, an energy-storing inductor connected in series with said center tapping and said first supply terminal, a further junction transistor current amplifier connected between said second supply terminal and said center tapping, a control circuit responsive to the collector potentials of said two junction transistors which is connected to the base of said further junction transistor to reduce the conduction thereof when either of said collector potentials crosses a threshold value, whereby an increase in current through either of said two junction transistors resulting in the potential at the respective end of said coil passing beyond said threshold value is detected by said control ciRcuit which then causes said further current amplifier to conduct less strongly.

Claim 13

A deflection system according to claim 10, further including a switching regulator circuit connected between said inductor and said other supply terminal, whereby the switching regulator circuit passes current from the voltage supply to said inductor, when energy is withdrawn therefrom.

Claim 14

A deflection system according to claim 11, wherein said switching regulator circuit comprises a resistor, a switching transistor, a switching control circuit responsive to changes in potential drop across said resistor, said switching transistor being connected between said resistor and said first supply terminal, and a shunt diode connected between said second supply terminal and the supply side of said resistor whereby said diode supplies current to said inductor until said switching transistor switches on.