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Author Topic: Yellow splotches on the screen? Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 11-23-2011 01:06 AM                        Good questions - I don't know. I think Dominic has it though - when the light engine is allowed to overheat enough, the optical coatings get scorched. On a Sony, perhaps it's the blue channel that gets the hottest and therefore gets scorched first. As for the whole imager/prism surface discoloring at the same rate - in theory I suppose that can happen. But if a lamp isn't aligned just right, the distribution of light and heat within the optical patch will not be even. Any overheating or scorching that would occur would not be evenly distributed across the output field, hence the splotches. That's my guess anyway.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 11-23-2011 09:03 AM                     Has to do with energy content at the blue side of the spectrum, I guess. Or spectral weakness of that specific coating. As it occurs local, I assume it has to originate near the imager, otherwise it would have to extend more over the whole screen. Local damage due to local contamination could also be a possible reason. Or, no real damage, but 'just' contamination. I have no idea wether the pictures shown indicate the 'weakness' of Sonys SXRD Technology as it has been mentioned by a lot of Sony sceptics in the forum. I can say, though, that I have seen similiar effects on a burnt LCD consumer projector, where the blue panel or polarizers seem to have been 'burnt' by extended usage, resulting in a picture with centered yellow blotching. Would be interesting to know: - bulb type (power) - type of machine (220/320) - age - typical day schedule, like 2 or 5 screenings a day, 3D, etc. - Carsten  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-25-2011 09:23 AM                     Paul is right. Something with the blue. I've had bad integrator rods.(cracked) before on Christie's and that affects all three colors. It might be a coolant leak on the light engine... Mark  |  IP: Logged Dominic Espinosa Phenomenal Film Handler Posts: 1172 From: California, U.S.A. Registered: Jan 2004 posted 11-28-2011 04:33 PM                     Silly Mark, what coolant? All air cooled, baby! Youknow...like an old Volkswagen The blue prism is in the middle of the pro assembly so its. Probably not proximity. Im going with intensity of light at that end of the spectrum. More often what I see is the coating bubbles up in the middle/it gets popcorn oil on the underside of the prisms and in the lrd, especially the Fresnel lens. That seems to introduce a nice yellow hue to the right and bottom, of the screen.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-28-2011 06:39 PM                     Depends on the projector. If it's a Barco then it is probably a coolant leak since nothing else could contaminate the prism. The Series 2 NEC blue DMD is also in a slight downward position... hard to get to so you align red and green to it. Popcorn oil is certainly a possibility and just switching brands can often alleviate that mess!! Could also be a booger from the last tech that happened to sneeze while standing looking down in the projector...  |  IP: Logged Jonathan Althaus Master Film Handler Posts: 435 From: Bedford, TX Registered: Dec 2008 posted 11-29-2011 10:32 AM                     Color splotches (on a Barco) like that could be caused by ICP or CCB  |  IP: Logged Mark Uhde Film Handler Posts: 9 From: Kalispell, MT USA Registered: Jul 2009 posted 11-29-2011 12:34 PM                        Well, my experience isn't in cinema (I joined this forum to read the overlapping areas), it's in concert/lighting/theatre tech. Here's what I can say: Yellowing is a problem with LCD. Which is what, at the end of the day, Sony SXRD projectors are. Fancy, modern, LCD units. Texas Instruments refers to this as "color decay" and here is their page on it: http://www.dlp.com/projector/dlp-advantages/picture-reliability.aspx It was my big concern when the local cinemas here in my town chose Sony projectors for digital cinema that the day would come when show after show was noticeably yellow and they will do nothing about it. LCD proponents will try to claim that larger projectors are better-cooled and don't have this problem. They do, it may take longer to show up - but they do. They'll try to claim LCoS (like Sony's projectors) don't have this problem. They do, Sony settled a lawsuit over their SXRD TV's having this problem. Will the SXRD digital cinema projectors prove to do the exact same thing LCDs have always done (turn yellow)? I don't doubt it one bit. Is your picture an example of that? Eh, maybe. But it looks more "splotchy" - burnt out LCD panels tend to look much more evenly degraded, worst around the center - not the bottom edge. Still, it's an issue worth at least considering as a possibility.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-30-2011 04:50 PM                     Because the light passes through the Sony imagers instead of bouncing off like on DLP the Sony imagers eventually become cooked and turn brownish in color. The green which passes ~54% of the light fails first since it is running the hottest. This is why Sony projectors are very limited on screen size capability. About 40 foot wide max. There is nothing that Sony has been able to do except replace the imagers as they fail. Mark  |  IP: Logged Mark Uhde Film Handler Posts: 9 From: Kalispell, MT USA Registered: Jul 2009 posted 12-01-2011 01:08 AM                        Mark, the LCoS (SXRD) panels actually are reflective, they're a reflective version of LCD. Still, they're subject to the same type of degradation LCD is, though supposedly less so. Are you sure Sony's seeing green panels fail first typically? That would be quite unusual. Blue panels usually fail first in LCDs (which is all SXRD really is, a reflective LCD) due to the energy of the blue light, and the blue materials not being as durable. Thus yellowing (red + green = yellow. If green failed first, you'd get purple splotches. Which is rare for panel/polarizer failure). However, like I said, the first image doesn't look like TYPICAL blue panel burn spots. Just the ramblings of a stage and concert guy... who has a passionate dislike for LCD projection in any form because when they get old the projectors invariably look like junk. Which lots of rental gear does. I was disappointed when our local cinema multiplex chose to use Sony SXRD projectors. Not because of how they look now, but because I can imagine them being yellowed and ugly in five years and them doing nothing about it.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-01-2011 05:37 AM                     Yea, technician friends that repair them always replace the green first. It is because it is dealing with a higher percentage of the light hence it gets cooked faster. BTW: I was told the light passed through them which is why Sony can actually do decent blacks... Yea, your local cinema will regret installing the Sony's sooner then they probably want to admit. Aside from the self consuming imagers Sony absolutely sucks as a company. Mark  |  IP: Logged Ron Funderburg Jedi Master Film Handler Posts: 814 From: Chickasha, Oklahoma, USA Registered: Nov 2007 posted 12-01-2011 09:13 AM                        I was going to make a smart ass comment but decided I wouldn't. How strange I must be tired!  |  IP: Logged Mark Uhde Film Handler Posts: 9 From: Kalispell, MT USA Registered: Jul 2009 posted 12-06-2011 02:42 AM                        Mark, oddly enough in addition to keeping the imager cooler, one of the benefits to LCoS vs transmissive LCD is better contrast. I find it amazing how little about the underlying technology some techs can know. Second, as to the green panels failing first (so they're failing to a purple color?), Sony has to be doing something really, seriously wrong in their design. Blue light contains the most energy in the visible spectrum. Thus, it destroys the blue panel first. I can't imagine what Sony could be doing WRONG with their green panels that they'd fail first despite simple physics demonstrating the blue should die first. Sony is using an inorganic material in part of the panel, combined with the reflective design, it's supposed to last longer than traditional LCDs - http://www.sony.net/SonyInfo/News/Press_Archive/200302/03-008E/ But it doesn't look like it's working. I ALWAYS recommend DLP. I've seen far too many LCD projectors die far too young in my life (you see some low-end conference and home DLP projectors die of shattered color wheels, but it's much rarer than blue panel failure in LCD units)  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 12-06-2011 11:25 AM                     The projectors with the highest contrast so far are LCoS projectors from JVC and Sony. Whereas most DLPs max out around 2000-3000. Sonys contrast specs for their SXRD projectors is on par with those for DLP, if not higher. Although I would like so see comparable measurements for sequential (on/off) and ANSI contrast for both type of machines. It is amazing how little we actually know about real life performance for digital cinema projection systems, be it projectors or 3D systems. The black level or current DLP machines don't impress me, they are only acceptable with a decent amount of ambient light level. However, there are cinemas with a very nice low level of safety lights where this flaw of the current breed of projectors really annoys me. - Carsten  |  IP: Logged Mark Uhde Film Handler Posts: 9 From: Kalispell, MT USA Registered: Jul 2009 posted 12-07-2011 01:17 AM                        Carsten, both SXRD and DLP exceed the contrast ratio of movie film. That's one of the things I LOVE about D-Cinema, better contrast. I must say that, personal opinion, I prefer the TI DLP setups I've seen to Sony's SXRD. Granted, the ONLY SXRD I've seen is here in Kalispell. One multiplex does not define a technology. I've talked with one of their upper management guys, and they've made significant improvements. The switch to in-server ghostbusting helped their Real-D performance a ton, for example (Real-D was a horrible mess on the SXRD setup here before that, whereas I've never found it too objectionable at DLP Cinema theaters). Still, I've only seen Dolby 3D once, but I was so much more impressed by it, the difference is astonishing. That's one of the biggest differences between you guys' work, and mine. You care about contrast ratio, I don't. Under stage lights, I couldn't care less what the contrast ratio of the image is. Just how bright I can get it. Still, traditional transmissive (not reflective LCoS) LCD projectors stink for contrast ratio - that's why they're never used for digital cinema. Anyways long rant for the end point being that from everything I've ever seen, DLP is a vastly superior technology to LCD/LCoS. The only benefit I can see to LCD is cost. LCD is far cheaper than DLP (for three-chip DLP). Single-chip DLP (not used in cinema ever) is less efficient and some people find the color flashing to be objectionable. When does TI's patent expire again?  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 12-07-2011 03:21 AM                    quote: Mark Uhde both SXRD and DLP exceed the contrast ratio of movie film. I know some people here who would take issue with this comment.  |  IP: Logged

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