Browse Prior Art Database

Write and Erase Pulses with Opposite Polarities

IP.com Disclosure Number: IPCOM000052209D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Beidl, JR: AUTHOR [+3]

Abstract

On high resolution AC plasma display panels where the resolution exceed 30-50 picture elements/inch, the wall charge produced during sustain spreads along the conductors beyond the imaginary midpoint between adjacent cells. This is especially true if the chamber gap is excessive for the line width and pitch. When a single cell is erased (worst case), a small amount of wall charge is left between cells that cannot be erased by repetitive erase cycles. With this residual wall charge in place, the cell will turn ON when adjacent cells are written just as if it had been selected. The dielectric cross-talk of the adjacent write pulses, combined with the residual wall charge, will turn the cell ON.

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Write and Erase Pulses with Opposite Polarities

On high resolution AC plasma display panels where the resolution exceed 30-50 picture elements/inch, the wall charge produced during sustain spreads along the conductors beyond the imaginary midpoint between adjacent cells. This is especially true if the chamber gap is excessive for the line width and pitch. When a single cell is erased (worst case), a small amount of wall charge is left between cells that cannot be erased by repetitive erase cycles. With this residual wall charge in place, the cell will turn ON when adjacent cells are written just as if it had been selected. The dielectric cross-talk of the adjacent write pulses, combined with the residual wall charge, will turn the cell ON.

Fig. 1 illustrates one conventional set of sustain, write, and erase waveforms used on a plasma panel, where the polarity of the write and erase signals, shown here as positive, are the same. The sustain alternation, just prior to the erase pulse, has a negative polarity and therefore produces a positive wall charge. If the erase pulse is adjusted to an under-erase level, the residual wall charge will have a positive polarity. When the adjacent cells are written, the write pulse dielectric cross-talk will also have a positive polarity, and combine with the positive residual wall charge to turn the erased cell ON.

The solution to this problem is to reverse the polarity of the erase signal, as shown by the waveforms of Fig. 2, wi...