"bright spots" in LCD RPTV's

[pbarach1]

Several times I have noticed in bright white picture areas on LCD rear projection TV's that I am seeing a bright spot that looks like an illuminated window screen. Most recently, I saw this on the otherwise excellent Sony 60" SXRD set. So is this the result of a poorly adjusted set, or is this a result of the way the picture is generated in a microdisplay TV?

 

[BMXTRIX]

Rear projection works by focussing a lamp through the imaging chip - either LCoS, LCD, or DLP, then using lenses, it takes that image and expands it from a 1" spot to fill your big screen.

The screen difuses the light and scatters it. The better of a job it does to scatter the light, the more difficult it is to see that 1" spot of light behind the screen. If the screen was clear, you would not see an image, but would see a sharp point of light - like looking into a flashlight bulb or a car headlight.

This bright spot is called a hotspot. Hotspotting is caused by imperfect diffusion in the screen, which is the case with every rear projection setup that I am aware of. It should be very minor, but it is almost always a bit noticable.

 

[pbarach1]

This bright spot is called a hotspot. Hotspotting is caused by imperfect diffusion in the screen, which is the case with every rear projection setup that I am aware of. It should be very minor, but it is almost always a bit noticable.

Thanks for explaining this so clearly! For me, this is not minor, but extremely noticeable. So your answer has me convinced that I should not consider any RPTV's, and therefore I'm considering LCD sets (especially JVC's 40" unit with native 1080 resolution) as well as plasma.

 

[mtrycrafts]

Thanks for explaining this so clearly! For me, this is not minor, but extremely noticeable. So your answer has me convinced that I should not consider any RPTV's, and therefore I'm considering LCD sets (especially JVC's 40" unit with native 1080 resolution) as well as plasma.

Where did you notice this, at a store, or at homes after the TV was professionally calibrated by an ISF certified calibrator?

If it was on a showroom floor, they are way over driven in every respect to catch the customers eye who is misinformed what it should look like. So, if this is the case, you may be unfairly passing it up.

 

[pbarach1]

Where did you notice this, at a store, or at homes after the TV was professionally calibrated by an ISF certified calibrator?QUOTE]

At a store (local high-end store), and I don't know ifd the set had been calibrated or not. Does this "hotspotting" phenomenon go away when the set is calibrated properly, or is it a characteristic of RPTV's, as my first respondent said??

 

[Hi Ho]

Hotspotting is an inherent problem in RPTV's but, as BMXTRIX said, a well designed and good quality set would show minimal hotspotting. A defective or improperly calibrated set can worsen the problem.

 

[BMXTRIX]

The real thing to do is to discuss it with a salesman at any store on a model that you otherwise like. The salesman should be able to work with you to minimize the hotspotting right on the showroom floor. Bring brightness levels down a bit and see if the final result is something you like a bit more.

Personally? Plasmas in the 50" range are available for under $3,000 right now... I like things that hang on my wall. For my 'big screen' I went with a front projector and a nice screen that basically has no hotspotting at all.

 

[mtrycrafts]

Where did you notice this, at a store, or at homes after the TV was professionally calibrated by an ISF certified calibrator?QUOTE]

At a store (local high-end store), and I don't know ifd the set had been calibrated or not. Does this "hotspotting" phenomenon go away when the set is calibrated properly, or is it a characteristic of RPTV's, as my first respondent said??

If you have a calibration disc, take it with you and see how badly it is pushed and see if you can zero sharpness at the minimum and as was mentioned reduce brightness and if there is a color temp, use the medium scales. Most of the time they are at max and everything else is way out of proper range. But, bright showrooms is not conducive to calibrated sets.