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The Dell Latitude XT / N-Trig Gridding Issue – Another Perspective



Yesterday, I posted about my disappointment with the grid issue on my Latitude XT Tablet PC. Steve Seto, a Tablet PC MVP and frequent GBM Contributing Writer, has penned this counter-point article on the whole gridding issue. His insights are quite helpful given that he is also a Latitude XT owner. He offers another view point in bringing some good balance to this issue.

Steve Seto

Rob has raised the issue of visible “gridding” on the screen of the Dell Latitude XT. It bothers him a lot. By contrast, it doesn’t bother me at all, and I thought that another perspective about this might be helpful to our community.

I want to begin by saying that I have nothing to do with N-trig or Dell and I wouldn’t recognize Len Englehardt if I bumped into him at the mall. What I bring to this discussion is almost 40 years of engineering experience, some significant part of which was devoted to conductive coatings on transparencies. For this reason, I think I understand some of what N-trig had to cope with when they designed their DuoSense digitizer. However, this discussion is based solely on my experience.

To be as brief as possible, there are at least a few technologies that one could consider if one wanted to make a pen- and touch-sensitive screen. Some of them would allow you to have a completely clear LCD screen (for example, think of a lattice-work of infrared beams immediately above the surface of the screen), but may have failings that make them unsuitable for mobile tablet use; too bulky, too heavy, overcome by sunlight, too energy-hungry… I could go on.

So the set of practical technologies that one has to choose from are somewhat more limited. One obvious approach is to integrate a sensing grid into the tablet display. If you want touch, that sensing grid probably needs to go over the front of the screen… and that means the design needs to consider relative transparency. How are you going to see through the sensing grid to see the LCD screen beneath?

Well, you can use a grid of very fine wires. Some bank ATM touch screens use this approach. But the wires are relatively easy to see and probably wouldn’t be acceptable to folks like us. Instead of wires, how about a conductive coating that’s transparent? You can do that, too! But the practical materials that are available, such as gold, enhanced gold and indium-tin oxide (ITO), all involve various compromises. First, none of them are truly transparent; just relatively transparent. Second, each of them introduces some degree of color change to the transmitted (and reflected) light. Gold, for example imparts a vague green tinge to transmitted light. And then there are a bunch of other issues like durability and compatibility that we’ll skip over. The point is, there are compromises involved in the technologies that we all love.

The bottom line is that if you choose a technical approach as described above, it is unrealistic to expect that it will be completely invisible. The best you can do is to make the visual issues as minimal as you can. I think that’s what Dell and N-trig have attempted to do, and I think they’ve been pretty successful. The gridding on the XT is visible. But the user can adjust the screen brightness to minimize this visibility, and that’s a reasonable design compromise. In the meantime, technology will continue to move on, and maybe Wacom or someone will figure out a better way, but for now N-trig is here and real and from an engineer’s point of view, I think they have done a good job.

Of course, beauty is ultimately in the eye of the beholder. This screen grid issue is simply one more factor that you should consider if you are interested in products that incorporate the DuoSense digitizer.

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