Originally Posted by lf82me
He proceeds to say the some sets are pretty bad but stated an allowable tolerance figure of .7 - 1.0 that is passable.
The limit we have been using (from Samsung) is one quarter inch. You need to contact Samsung if your bowing is greater than that amount. What unit of measure goes with .7 to 1.0 range?
Here is some information that I've saved.
It may be the screen, although as I mentioned in a previous post, the technician I last showed it to said it is the the way the light engine passes light through the lens and then reflects off the mirror.
That is a major cause of pincushion in all RPTV sets. It's made worse by the short distance between the thumb nail sized chip creating the image, and the very large screen on which it's projected.
Noone ever did get a final answer in this forum on what the issue is and if there is a full solution
I've tried to provide the "final" answer several times.
If it is the screen, I don't think it matters when it was built. I haven't heard anyone say that later build screens were any different than earlier build ones.
A warped screen can cause pincushion effect but it's the mount not the screen itself.
The third possible cause of pincushion is the way the light engine is mounted in relation to the screen. The mount relationship is different for every individual RPTV set.
I've seen pincushion on the high end German Loewe 55" Articos DLP sets. The cases, mounts and screens were aligned better than any set you are likely to see in mass distribution. The lenses used were also higher quality than any of the mass distribution RPTV sets available. None of that overcame the problem of taking an image from a tiny chip to a large screen in a short distance.
Other companies may be reducing pincushion better than Samsung has been able to so far. Mitsubishi may not be one of them because there is pincushion discussion going on now in their owners threads.
Because it's caused by the nature of RPTV devices and comes from more than one source, an after the fact fix is very hard to come by. The new thinner cases will probably cause the problem to get worse. A lense correction is possible but way too expensive for todays mass market.
My 2004 HLP case is not quite as shallow as the same sized HLS sets and it may be a bit more ridged. It has a much wider bezel. When I measure the bowing on the horizontal edges of a 4x3 image I get about 1/16" on one side and at the most 1/8" on the other side. As cases get lighter, thinner, and narrower it's going to be harder to get those results. Still, with compensating errors, it's possible to find sets with imperceptible pincushion bowing.
There are claims that Sony RPTV sets don't have this problem. I can't say for sure, but if Sony can do it then Samsung and Mitsubishi should also be able to make the bowing disappear before all 4x3 images are gone for good.