Browse Prior Art Database

Switching Regulator System for Plasma Display

IP.com Disclosure Number: IPCOM000049742D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Martin, WJ: AUTHOR

Abstract

This article describes a voltage regulator especially useful in a plasma display device. The regulator has a pulse width modulated switch which is synchronized in its operation with the sustain drive load of the plasma panel such that the load current changes are anticipated by the regulator. This results in improved regulation including significant reduction of the effects of ripple voltages.

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Switching Regulator System for Plasma Display

This article describes a voltage regulator especially useful in a plasma display device. The regulator has a pulse width modulated switch which is synchronized in its operation with the sustain drive load of the plasma panel such that the load current changes are anticipated by the regulator. This results in improved regulation including significant reduction of the effects of ripple voltages.

The maintenance of the display in a plasma (gas) panel of the kind shown in U.S. Patent 4,097,856 requires the constant application of a pulsating current sustain signal which places a potential across the gas cells formed between orthogonally related sustain grids on the opposite sides of the panel. Since this potential must be high enough to maintain the wall charge in operative cells while not high enough to commence operation of unlighted cells, the requirement of voltage regulation and freedom from random ripple can be stringent for such a supply.

Fig. 1 shows the power supply, with the sustain load of the gas panel as its load, and Fig. 2 shows the operation of the regulator in relation to the load imposed upon it by the gas panel sustain circuits.

An unregulated DC input is applied to terminals 10, 12 from which energy is delivered via switching regulator 14 to the load 16 which comprises the sustain load of a gas panel. The load 16 is pulsed at a rapid (typically 40 KHz) rate by the associated Display Control 26. The illustrated regulator 14 is of the kind which consists of a transistor switch S in series with the load 16 through the primary 18 of a transformer T. Primary 18 and a capacitor 20, across load 16, act as an L-C filter. A second output path for 14 consists of secondary 22 of T in series with a diode D poled to conduct during fly-back of T when S is off. Switch S in regulator 14 is under the control of a pulse-width modulator PWM which compares a feed-back signal 24 to a ramp generated within PWM to vary the ON time of S to provide the desired regulation. The ramp in PWM is under the control of synchronizing circuit SYNC which also operates via the display control 26 to time, via line 28, the sustain drivers (not shown) in load 16.

Fig. 2 illustrates the interrelated operation of these circuits. Sync circuit SYNC acts as a clock operative to initiate the control ramp 30 in pulse-width modulator PWM periodi...