What to to about the tap bug

Re: Troubleshooting -- HF
Posted by HF , 04/06/2000, 09:28:20 Reply Top Forum

What to to about the tap bug
Q: I get wrong letters and unwanted capitals like ddLooOdKOLEE instead of dddddddddddd.

This is no software bug but a problem some digitizers have. Really.

FitalyStamp has been tested by many users on numerous machines, and this phenomenon is definetely a hardware problem.

The good news is that part of it can be cured by yourself. As a service, Textware Solutions provides some information about it for FitalyStamp users. Here is a brief and very simple explanation of what happens and what you can do about it.

The Hardware Tap Bug

As you may have noticed the digitizer screen is soft. Why? There is a thin, nearly invisible gel layer on the glass, and when you tap or write on the screen, the stylus tip deforms this gel at one spot. This place can be read out by the digitizer electronics, and this is how the device gets to know where you are writing.

In reality things are more complicated. For example there is another thin plastic layer above the gel. A second layer is between the gel and the glass, and so the gel can move between the plastic like the filling of a sandwich when pressed.

Now comes the problem: Unfortunately the gel layer can be damaged by heavy tapping or writing. Also the plastic layer tends to get little scars and dents, and all this can lead to misunderstandings of your input.

"I never noticed problems with graffity, so why should I have a damaged screen?"

Numerous people have a worn out screen not knowing it. All they notice is that sometimes graffity does not work as it should, e.g. you get an L instead of an I and so on. Most people then blame themselves for not having written with the appropriate accuracy.

"My PDA is just new, so it can not been worn out".

There seem to be a number of devices that have this problem right from the start. Verify the hardware problem as described below, and in the case no curing method helps ask the vendor for a replacement of the screen.

If you are experiencing garbled letter output please do the following:

1. Try to verify that it is a hardware problem. Methods will be described below.

2. Try to cure it. There are several ways to do this.

Verifying the hardware tap bug

You need a program that visualizes your tapping and writing.

Chris Crawford provides a freeware tool called GrafAid on his site.

A commercial product is TealEcho.

Install one of these programs and watch what they show when you tap systematically on every spot of the relevant parts of the screen. The monitoring software should show only dots. If you see streaks or lines, then your digitizer has the hardware tap bug.

Note that your taps should have the firmness and the speed as they normally have. Also vary the pressure. There are users that learnt to avoid the tap bug by careful tapping.

How to cure the tap bug

The following information, as parts of the above, are an excerpt of Tony Jest's Tap Bug site.

Note that all advice is offered for you to use at your own risk. Textware Solutions will in no way be responsible for any damage on your screen.

    1. Prevention

    This should be main aim to any new PDA users. The Palm V is known to be more damageble than the PalmPilot, so be careful. Search the tips of your styli for hidden edges. Also you should protect the graffity zone at least. Note that the FitalyStamp itself provides protection of the surface.

    2. Gel Massage

    This techniqe aims at redistributing the gel more uniformly. Use the back of your thumbnail to stroke the screen in straight lines ending at its Graffiti input area. Use firm but not excessive pressure. Do not use the edge of your thumbnail, but stroke with the nail as flat to the screen as possible.

    You will have to repeat this from time to time.

    3. Tape Bandage

    See the Tap Bug site.

    4. Gel stretching by spacer

    One of the FitalyStamp users, Bryan Bertoglio, writes:

    "Simply put some kind of spacer between the screen and the case next to the graffiti area on either side. I have used index cards, or 20# stock folded in half and trimmed. If done carefully, it won't even be visible and will stretch the laminate sufficiently to eliminate the taps->lines phenomena."

    5. Screen reflexing

    See the Tap Bug site.

    6. Hold stylus higher

    7. Do not use too many hacks

    8. Exchange on warranty

    Tony Jest writes on his site:

    "Many people have reported to the PalmPilot newsgroup alt.comp.sys.palmtops.pilot that this problem is fixed by 3Com under warranty. A very few (presumably people who are writing a lot of Graffiti and/or with too much pressure) even talk of needing a screen replacement every 3 months. So, if you are still in the guarantee period your luck may be in! Note that once you get a new screen you may well be amazed at how little pressure you actually need to use on the stylus. Keep the pressure light and you should ensure a long life for your new screen!"

    9. Paid exchange of the screen

    Tony Jest:

    "Everything does have a finite life. Even though we would like things to last forever, in the real world they don't. My advice can help you to extend the life of your screen, but it is only putting off the day that the final option, getting a new screen fitted, becomes the only effective way forward."

We hope that these explanations will help you solve your digitizer problem and enjoy an untroubled use of FitalyStamp!


Tony Jest's Tap bug site with a lot of information and more links

Alan Jay Weiner's history of tap bug site, with more information on how the screen works.

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