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AC Plasma Display: Linear Erase Technique With Compatible Write

IP.com Disclosure Number: IPCOM000087826D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 5 page(s) / 117K

Publishing Venue

IBM

Related People

Schlig, ES: AUTHOR [+2]

Abstract

As shown in Fig. 1, the classical voltage-controlled erase techniques use erase pulses of amplitude V(E) which is less than sustain amplitude V(S). As shown in Fig. 2, the erase firing occurs at a peak gas voltage for which the slope of the voltage transfer curve is very steep, so the effectiveness is critically dependent on the tolerance of V(E) and V(EP).

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AC Plasma Display: Linear Erase Technique With Compatible Write

As shown in Fig. 1, the classical voltage-controlled erase techniques use erase pulses of amplitude V(E) which is less than sustain amplitude V(S). As shown in Fig. 2, the erase firing occurs at a peak gas voltage for which the slope of the voltage transfer curve is very steep, so the effectiveness is critically dependent on the tolerance of V(E) and V(EP).

Pulse-width control of erase pulses of amplitude V(E) greater than V(S) is also known. Firing is initiated on the unity-slope part of the transfer curve above the sustain point in such a case. However, the pulses terminate before the voltage transfer is complete so the change in wall voltage is the same as in the classical case. Although the pulse amplitude is less critical than before, the pulse width and shape are quite critical.

This article teaches a new erase technique which uses pulses larger than V(S) and so produces firings on the unity-slope part of the transfer curve, yet also uses sufficient pulse width so the firings are complete and the pulse width is noncritical. Since the transfer curve is relatively shallow and the voltage transferred is virtually equal to the peak gas voltage, the pulse amplitude is less critical to the effectiveness f the erase operation than in the classical case. In addition, it is shown that a pulse of exactly the same amplitude and shape as the erase pulse becomes a write pulse when it is followed directly by a sustain of opposite polarity.

As shown in Fig. 3, the nominal linear erase pulse amplitude is approximately twice the sustain peak amplitude. When the cell is initially "on," the erase pulse causes the initial voltage across the gas to reach 3 V(S) (approximately), compared to approximately 2 V(S) in the case of sustain. In this voltage range, the residual gas voltage is usually less than 5 volts after the firing and nearly independent of the initial gas voltage. (It is shown as zero for simplicity in the diagrams.) Thus, when the erase pulse returns to ground level (a -2V(S) change) the initial gas voltage goes to -2 V(S) and a firing occurs, reducing the gas voltage and thereby the wall voltage to approximately zero. The cell is now erased, and the sustain signal resumes.

When the cell is initially off, the...