By Sergey Sekaev
Never let it be said that PalmPower doesn't show you all the funky solutions. In this unusual article, Sergey Sekaev shows how the Graffiti writing area operates and how you can make simple repairs. Be forewarned, however: there's no guarantee this somewhat radical solution will fix your PalmPilot and it definitely voids your warranty. You're on their own if you decide to try this one out.
Does the "spurious digital ink" in the alphanumeric area of your PalmPilot's screen cause Graffiti recognition degradation?
Many owners of PalmPilot encountered this problem. They had to send their devices to 3Com for the replacement.
I tried to find an alternative solution to this purely mechanical problem and eventually found an effective method of "spurious digital ink" elimination. I've used it for more than two months on my PalmPilot Personal with no recognition degradation.
First of all, we should consider the internal structure of PalmPilot's screen to understand the mechanism of the problem.
What is the layout of the PalmPilot's touch-sensitive screen?
The main input element is implemented in a glass plate having the contacts grid with the one-pixel-width step. The electrically conductive plastic membrane (not glass!) is placed on top of it and separated from the sheet of glass by means of non-conductive liquid. The membrane is equidistant from the contacts plate all over the screen. When the stylus presses the membrane some contacts short-circuit and PalmPilot determines the contact's positions.
FIGURE A
These are membrane positions and screen layers. (click for larger image)
How the membrane is worn out during the long term usage
When writing, the stylus is pressing the membrane and in the long run the membrane deforms, (i.e., it bends toward the contacts plate). In addition, the stylus scratches plastic membrane. The more intensively used, the more scratches and more deformations.
When the stylus presses nearby the deformed area, more than the usual number of contacts is short-circuited. It leads to the "spurious digital ink" for Graffiti symbols.
How to get rid of deformation
It seems you cannot eliminate the deformation completely. However, you can compensate it by applying force in an opposite direction, as shown in Figure A.
Membrane lifting will help you return it in the original state. It can be done by the means of usual adhesive tape or scotch, used as shown in Figure B.
How should tape be applied?
First, attach the Scotch tape to the screen borders over the alphanumeric entry area of the PalmPilot from left to right. The tape should be applied gently, but with some tension enough to lift the membrane. Then, press the tape by your finger against the most deformed area of the screen. As usual it is the most scratched spot on the alphanumeric zone. The tape resiliency will help lifting the membrane.
