Sony KDS-R60XBR2 60" SXRD RPTV Addendum 1: The Green Blob

Addendum 1: The Green Blob

Some first generation SXRD rear projection sets suffered from extremely poor screen uniformity, which on a full white screen, caused the center to appear greenish while the edges appeared bluish. Owners called this the "green blob" effect. Some very discerning owners that I know had their sets replaced three times while others had the light engine replaced that many times or more in an effort to get a "perfect" set. Having calibratedmany of these sets both before and after repairs, let me address this issue.

First, some sets did have a real problem. It often got worse over time and was temperature variable as well, but it was difficult to see in normal viewing. Using lower (Warm) color temperatures made it more apparent. The worst-case measurements I made showed 7000K in center screen and over 10,000K in the corners. Sony seems to have solved it this fall, since recent replacement light engines I've seen have been fairly uniform and none of this year's sets I've seen (this review sample included) have had a significant problem. Perfect uniformity in any LCoS set, however, is something you probably won't see. That said, let's talk about the screen itself and how it can give the false impression of a uniformity problem.

I've said before that the screen is the weakest part of the best rear projection sets, yet it's the very thing that allows them to be used effectively in brightly lit rooms. Sony has achieved a remarkable viewing angle with their screen and it's degrading effect on the HD picture is less obvious than most, but this seems to come at a price. When looking at a full white or gray screen, if you don't view a particular section of the screen "head-on" it will appear slightly bluish compared to whatever section you are viewing "head-on." This means, if you're up close looking at the center, those parts at the extremes will look bluish and by comparison, the eye often incorrectly perceives the part not bluish as too greenish. While this might cause some to think they've got a defective light engine, it's most often just a screen artifact. No other set I've seen exhibits this illusion quite so much, but then, no other RPTV screen matches the Sony screen in some other aspects either. At a reasonable viewing distance (12' or more), this isn't an issue.