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Cathode Ray Tube Deflection Circuit

IP.com Disclosure Number: IPCOM000097367D
Original Publication Date: 1962-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Lamoureux, WR: AUTHOR

Abstract

This circuit is a current driver for a cathode ray tube (CRT) deflection coil. It is responsive to CRT beam-positioning signals of both high and low frequency notwithstanding that the circuit contains a single deflection amplifier responsive to only low frequency beam-positioning signals.

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Cathode Ray Tube Deflection Circuit

This circuit is a current driver for a cathode ray tube (CRT) deflection coil. It is responsive to CRT beam-positioning signals of both high and low frequency notwithstanding that the circuit contains a single deflection amplifier responsive to only low frequency beam-positioning signals.

The circuit has a deflection coil C connected between resistor R which in turn is connected to a source of positive potential + V, transistor T1 connected to a source of negative potential -V and transistor T2 connected in a grounded base configuration. Connected in parallel with C is an input circuit comprising transistor T3, resistor R2 and deflection amplifier A, which is responsive only to low frequency variations. Therefore, only low frequency beam-positioning signals applied to the base of transistor T3 are amplified and reflected as current variations in coil C.

To achieve sensitivity to high frequency beam-positioning signals, transistor switching circuitry comprising transistor T4 is connected in series with parallel- connected transistors T5 and T6, this circuit being connected in parallel with coil C and T2.

Like T2, T4 functions as a voltage buffer to provide a high impedance output such that the current at the collector is substantially independent of the voltage. When T2 and T3 are switched on, thus rendering the high frequency portion of the circuit conductive, a portion of the constant current through the C circuit is shunted t...