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Constant Velocity Character Deflection System

IP.com Disclosure Number: IPCOM000079342D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Ambrico, LE: AUTHOR

Abstract

At input terminals 3 and 4, the circuit of the drawing receives binary signals representing a desired deflection on a cathode-ray tube, and at output terminal 5 it produces a ramp voltage having a fixed slope and a duration that is established by the input signals. The fixed slope of the voltage ramp moves the beam with a constant velocity and thus maintains constant-screen intensity.

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Constant Velocity Character Deflection System

At input terminals 3 and 4, the circuit of the drawing receives binary signals representing a desired deflection on a cathode-ray tube, and at output terminal 5 it produces a ramp voltage having a fixed slope and a duration that is established by the input signals. The fixed slope of the voltage ramp moves the beam with a constant velocity and thus maintains constant-screen intensity.

The transistors associated with inputs 3, 4 and a transistor 6 produce voltage steps at collector terminal 9, with changes in the combinations of input signals. A network of resistors and capacitors 12 sets or resets a latch 13, according to the polarity of a voltage step at collector terminal 9. Thus, output 14 of latch 13 identifies whether a positive or a negative voltage change has occurred at collector terminal 9.

Transistors 15 and 16 and the associated resistors and base terminal reference voltage sources form current sources, for charging a capacitor 17 in a selected polarity. Transistors 19 and 20 form switches for the current sources. Latch output terminal 14 is connected to turn on one or the other of transistors 19, 20 and the associated current-source transistors 15, 16, according to the intended direction of beam motion and the associated polarity of the voltage step at the collector terminal 9. As capacitor 17 is charged, a voltage ramp of the selected polarity and of a fixed slope is formed at output terminal 5.

A network...