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Suppression of Horizontal Deflection Current Ringing

IP.com Disclosure Number: IPCOM000038874D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Palmucci, C: AUTHOR [+2]

Abstract

This article describes damping of ringing in a high-frequency flyback (.5-5 microseconds) resonant circuit for use in the horizontal deflection circuit of a cathode ray tube (CRT) display. In the circuit of Fig. 1, a potential is applied across a horizontal deflection yoke winding 10 in series with an inductor 12 by conduction of a high voltage transistor 14 under the control of a square-wave signal source 16. Thus, when the transistor 14 is turned on current flows through the deflection yoke 10. When transistor 14 is turned off by the pulse square wave applied to it by control 16, a flyback cycle is initiated. During this time, the energy in deflection yoke 10 is transferred into a flyback capacitor 18 as seen at 20 (Figs. (Image Omitted) 2A and 2B).

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Suppression of Horizontal Deflection Current Ringing

This article describes damping of ringing in a high-frequency flyback (.5-5 microseconds) resonant circuit for use in the horizontal deflection circuit of a cathode ray tube (CRT) display. In the circuit of Fig. 1, a potential is applied across a horizontal deflection yoke winding 10 in series with an inductor 12 by conduction of a high voltage transistor 14 under the control of a square-wave signal source 16. Thus, when the transistor 14 is turned on current flows through the deflection yoke 10. When transistor 14 is turned off by the pulse square wave applied to it by control 16, a flyback cycle is initiated. During this time, the energy in deflection yoke 10 is transferred into a flyback capacitor 18 as seen at 20 (Figs.

(Image Omitted)

2A and 2B). Immediately after horizontal flyback, the usual damper diode 22 goes into conduction. It is this turn-on transient that initiates the yoke ringing, seen at 24 (Fig. 2A). The tendency for the deflection yoke winding to oscillate and ring comes about because of the high Q of the yoke. The yoke ringing is seen at the left vertical edge of the raster as several alternate light and dark vertical bars on the screen of a high resolution display monitor. The object of circuit 25 of Fig. 1 is to dampen out this ringing in the most efficient manner. This function is accomplished as can be seen at 24 vs 20' in the yoke current waveforms of Figs. 2A and 2B, respectively, befo...