Microdisplay describes a group made up of HDTV display formats types. The HD Guru explains how they work and describes the differences between the three competing microdisplay technologies.
What is it?
A Microdisplay is a device or chip smaller than a 1 inch diagonal found inside all lamp- driven projection HDTVs. The device(s) creates all of the picture elements. Light is either transmitted through (LCD), or reflected off the device (DLP, LCoS) and then sent through projection lenses onto a special optical screen for viewing. When you look at microdisplay rear projection TV you are looking at a magnified view of the image produced by the device(s).
The Three Types of Microdisplays and How They Work
The three types of microdisplays are LCD, DLP and LCoS. Each creates images differently.
LCD is a transmissive technology, meaning that light travels through the chip to form an image, and then bounces off a mirror and onto a screen. Each picture element uses microscopic crystals suspended within a solution. A drive transistor around each pixel sends varying voltage levels to its adjacent sub-pixel. A voltage increase or decrease causes the tiny crystals to rotate. Polarizing the projection lamp’s light, it is then split it into the three primary colors (Red, Blue and Green), with each color beam then passing through its own LCD chip. As the light passes, each pixel acts like a tiny shutter, allowing the light to either pass or be absorbed. The three colored light beams then recombine to form a full color image, which is then projected onto the screen. LCD rear projectors today are only available in the 720p format (720 progressively scanned lines) with a resolution of 1280 x 720. LCD RPTV is a mature and proven technology that’s been available for five years.
DLP is a reflective technology utilizing between 900,000+ and 1,000,000+ microscopic mirrors housed within a single tiny chip. Each independently functioning hinged mirror can pivot up and down, and thus reflect different amounts of light. Current DLP chips contain either 1280 x 720 (720p) or 960 x1080 mirrored pixels. An optical shifting technique allows the 960×1080 chip to project 1920 x 1080 pixels on the screen. DLP’s mirrors are spaced closer together than LCD’s pixels, producing greater “active area†within the chip. The amount of “active area†within the chip, relative to its overall size, is called its “fill factor.†DLP’s “fill factor†is higher than LCD’s.
All DLP RPTVs use a color wheel placed in the light path after it has been reflected off the DLP chip, to create a full color image from a single chip. Color wheels today include 3 to 6 color elements. All have red, blue and green primary segments, with the more sophisticated ones adding cyan, magenta and yellow. The spinning color wheel, powered by a tiny, high speed electric motor creates a full color image on the screen, using a process know as sequential color.
Early versions of DLP suffered from what’s called the “rainbow effect,†which caused some viewers to occasionally see the coherent color image break up into quick flashes of red, blue and green stripes. Higher speed wheels and six color segments have virtually eliminated this problem for the vast majority of viewers. DLP “light engines†introduced in 2006 utilizing red, blue and green light emitting diodes (LEDs) capable of high speed operation, eliminate both the color wheel and expensive bulbs. DLP is also a mature RPTV technology, available for more than five years.
LCoS ( Liquid Crystal on Silicon), combines aspects of LCD and DLP. Like LCD, the LCoS chip utilizes microscopic crystals and polarized light as well three chips to create a full color image. However, unlike LCD, which passes light through the crystal, the LCoS chip’s crystal layer is mounted on a reflective layer, behind which are the switching transistors, allowing the individual pixels to be placed closer together than either LCD or DLP and giving LCoS better “fill factor†than either DLP or LCD.
Two LCoS variants, DiLA, or Digital Image Amplifier (JVC) and SXRD, or Silicon Crystal Reflective Display (Sony) are currently manufactured. DiLA chips are available in projectors with resolutions of 1280 x 720 (720p) and 1920 x 1080 91080p) full HD. Sony’s SXRD RPTV are available only in full HD 1920 x 1080 (1080p) resolution.
LCoS is a relatively new display technology. JVC’s current three chip DiLA is less than three years old, while Sony’s SXRD is less than two years old. The HD Guru strongly recommends purchasing an extended warranty on any display device with a core technology less than three years old. Otherwise you are assuming the high risk of problems often associated with an unproven technology.
Microdisplay technology allows designers to make slimmer projectors. Current projectors have depths from around 20†to down to 10†with screen sizes ranging from 42†–73â€Â.
DLP rear projectors are available from Mitsubishi, RCA, Samsung, Toshiba, Zenith and Nuvision. LCD rear projectors are available from Sony and Hitachi. LCoS is only available from JVC and Sony.
Coming Soon: The HD Guru Picks the Top Microdisplay Rear Projectors
Copyright 2006 HD Guru (SM) All rights reserved
Can anyone tell me what actually causes the blue dots on the screen when the light engine starts going bad on a rear projection tv. Is it a defect or contamination in the lenses, filters, and mirrors or is it in the electronics? I have a sony grand wega and I am seeing a very large amount of customers experiencing the same problem with the large cluster of blue dots. Some talk about dust contamination. I’ve taken the unit apart and only cleaned a few of the lenses I didn’t remove every mirror and lense but this did nothing. I’ve priced replacement units but before I replace it I’d like to understand what is going on with the “blue dots”.
I have a Mitsubishi WS 52527 (52″ LCD RPTV) that is less than 3 years old. I changed the bulb about three months ago. Recently, I noticed a sound coming out of the tv, kind of like the sound of a computer hard drive. The sound is not a constant pitch noise but varies. It goes away for a second during channel changes. Does anyone know what is causing this noise? I thought it might be the color wheel going out but this unit is LCD so there is no color wheel in it. Any advice would be greatly appreciated.
Don
Hey, great article HDGURU. Wish I had run across it before all of the hours of extensive research I’ve been doing. (Most of it before the post was made). At least it matches my conclusions, so that makes me feel better.
Since christmas I’ve enjoyed my 65″ Mitsu diamond without reservation as long as the PS3 or my PC is selected. DirecTV is better than fiber optic delivered cable to date. But Blu-ray and all 1080P content make this DLP purchase, also recessed into the wall, a no brainer. Disposalable income shortage, not cheapness, was final deal maker.
Spent about 6 to 7 hours shopping and doing my homework. For my basement DIY home theatre this best bang for the buck
Every single dlp hdtv set changes when you move around, period. the best one is sony sxrd or jvc hd-ila, all of them do…just your way of saying you were to cheap to buy the plasma! don’t give me that the pictur is just as good as crap!
Quick question. I’m about to buy a 50″ Panasonic TH50PX60U and I saw what I thought was the same tv at Costco for $400 less. But…the model number is TH50PX6U.
What are the differences and are they significant enough to matter?
Also, the Panasonic 50″ 600U is supposed to be a better tv but at Costco they say the tv comes without speakers and a stand? Is that correct?
thanks again for your great website. Don
I bought a Toshiba 56HMX96 56 inch DLP for Christmas and I absolutely love this TV. I went to all the big name stores and viewed dozens of TV’s. I finally subscribed to Consumer Reports for 1 month and found that the TV was rated very high (much higher than the Sonys). I have Comcast hooked up to it now but I continue to have problems with their equipment so my wife and I are going back to Direct TV. Thanks for a very good article and I really recommend this TV
OK. What I really have is a Question:
Pretend that I am a 7 year old child;
When I look at a TV screen (Standard) I see
hundreds of tiny dots red blue and green
about 20 lines accross and 20 down or 400 of each color,
1200 Total per square inch. I call this
(please forgive me if my technobable is wrong)
a standard “Dot Matrix” screen ?!
Now I have been looking in electronics stores
Circut C, “Fr, TheGoodG and BestB.at every kind
of HD TV and I have found only a few (4 units)that
do NOT have this “Dot Matrix” with as few more
as 22lines of res or 1450 psi to 24 lines of res
or 1728 Psi as a Student of neurophysiology
I can tell you that at ’6 to ’10 away beyond 1,100 grains Psi the human eye can no longer distinguish a difference if the difference is less than 2,000 grains Psi. So, if you have a TV that has less
than 3,000 grains (grid dots,Squares,Rectangles)
Psi then your eye wether you believe it or not
does NOT know the difference.The Color IS brighter but the detail is Exactly the same!
Here is my question: What is the difference in
technology, between the so called HD units that have a countable grid screen with a picture that is STILL broken up into visible tiny squares VS. the units that have NO visible
grid or “Dot Matrix” ??
Any help would be great Thank you!
Ben.
Continuous color has triads of red blue green , currently these are CRT direct view, Plasma, and LCD flat . Coming soon sequential color LCD (no more red blue green triad). DLP rear projection currently has sequential color as well.
The HD GuruÂÂ
I am sorry to ask, but does anyone notices the “Silk Screen Effect” on these sets? That along with the bulb issue are reasons I would not purchase a DLP, LCD, LoCos RP set.
Jeff,
Just curious. What comments did you find misleading?
I have a 50 inch Samsung DLP. It is awesome. The picture this set can display is just as good if not better than plasma or LCD at a fraction of the cost. I’ve had to replace the bulb once in 2 years but other than that, I prefer it over any other technology. Samsung also has a new slimline DLP that is extremely skinny and looks fantastic as well. In my opinion, DLP is the way to go when purchasing an HDTV.
I read over the comments and such and find it a bit misleading.
I recently purchased a samsung 61″ Widescreen DLP® HDTV with 1080p Resolution ( http://www.samsung.com/Products/TV/DLPTV/HLS6187WXXAA.asp )
very nice television. I went into the store to get a plasma and left with the DLP, the picture quality was far better then any plasma they had, colors do not change when looking at it from any angle. I have a HD-DVD player connected to the TV via HDMI and HD through directTV, again, connected via an HDMI cable… I am very impressed and would buy it again.
A 65″ display explains much too me. Once you move above 55″ you can begin to see differences in the technologies, and that I agree. The compression of signals by the content providers is truly apparent. Talks about secrets that are not revealed, is the compromises that cable companies make in the delivery of the signal. Forget that often they do not broadcast in HD even on the HD channels, many times they reduce the bandwidth resulting in less than a capable delivery of content.
I do not know what blue ray or HD-DVD has to offer nor HDMI 1.3 and remain skeptical about any significant improvement for quite some time.
I do know that at 65″ you should be able to see an improvement from 1080p, when content is available. The upconversion schemes are in my view a gimick.
I HAVE A 42″PLASMA W/ DIRECT HD & MY HDMI CABLE WONT WORK UNTIL DIRECT TECHS GET THEIR BUGS WORKRD OUT. THEY FAILED TO TELL ME THAT UPON INSTALLATION & I SHOPED FOR HDMI CABLES & BOUGHT MINE @ WAL-MART FOR $32.00
About the article on “what retailers don’t tell you about Microdisplay Rear Projection”
According to the Texas Instruments site
http://www.dlp.com/dlp_technology/dlp_technology_overview.asp
There are 2 million (actually 2073600) mirrors on teh 1080 DLP chip. One for each pixel location.
This blows me away!!!
I can’t wait for the 3DLP projection systems to get into a price range I can afford:)Imagine 35 Trillion colors????
Great articles, by the way.
Keep up the good work
Richard
I bought myself a brand new JVC HD-ILA 52G887 720p for Christmas and I have to tell you that I have been thoroughly pleased with the performance. Having owned a DLP unit since 2004 and recently selling it, I find that the picture is much better than anything that I have seen, including some 1080p units.
Happy new year everyone!
HD Guru – Keep up the good work!
lee: My eyes are about 10 feet 5 inches from my Sharp Aquos 65 inch LCD. Because of the pixel density (1920X1080)I could sit closer. The problem I have found is when I get up from a seated position,a rear projection TV picture fades,color shifts and darkens. This is unacceptable to me. I want to see an image that does not shift no matter where I am in the room. (Just like CRT) When I go to evaluate new panels,rear projection,I choose a high quality store with a closed off viewing,living room enviroment. Even with todays best rear projection,the image fades when I stand up.
I have Direct tv and find that HDnet has the highest quality Hd content I’ve seen except for blue-ray which is just amazing. I asked a Direct tv tech. why HDnet looks so good,he said HBO and the rest are compressed to a factor of 8. HDnet by a factor of 19 and Sony Blue-ray uncompressed to a factor of 47. The higher being the best.
I like Sony despite some recent problems. They are inovators. Putting aside thier great specs,they consistantly design the best looking products in this writers opinion. Thier new LCD XBR3′s have that beautiful floating glass,piano black laquer,brushed metal design that I find iresistable. It’s subjective,but I think of these panels as high tech sculpture. It’s nice when they look great both off and on.
Bang & Olefson also makes great looking panels,but very pricey.
I have both a new Plasma and RPTV which sounds frivolus but put one in my basement and one in my family room.
Sitting so close to any very large TV (except a tube) is a mistake and you will detect flaws regardless if it is LCD, Plasma or RPTV.
The Plasma was a gift from a client a month after I bought the SONY RPTV. Perhaps its a matter of taste, but I like the picture of the RPTV better. Having said that, all of the new sets out there are very good, including the Vizo Plasma. Looking at sets side by side is misleading, too many variables to account for. My ultimate decision came down to what I thought would be most reliable in the long term. I suspect SONY will be around.
The SONY by the way is 15″ deep and I have it recessed in a wall. When it is on no once can tell if its a RP or Plasma or LCD.
My biggest complaint is the lack of HD content available. Few broadcasts in 720p or 1080i and nothing in 1080p. Also annoying that all squeeze the bandwidth at times.
Hopefully the quality of the delivery will improve in the upcoming year.
lee: I agree with everything you said. Rear projection has made significant improvements in picture quality like the 70 inch Sony SXRD. The picture looks stunning from a distance. It’s ony when one walks up to the set,that the picture drops off and for me that is a problem.I also feel rear projection is like looking throuh a filter. As previously stated,I don’t like the mechanical tech. of DLP Good news that they are eliminating the color wheel. My previous Pioneer rear projection (with the cobwebs) was a newer design.Only 17 inches thick. Yes HD guru is very knowledgable.
The new generation of rear projection TV’s are signficantly different then those large box’s of the past. The research and data suggests all produce an exceptional picture.
The question with all TV’s is how they will be viewed which sounds obvious but that often gets lost in the analysis. The so called drop off of picture or angle is really not an issue, since you view your TV from a stationary position.
With DLP there is basically 2 failure mechanisms, the spinning color wheel and the bulb. With the other RPTV it is basically the bulb. The replacement of that is blown way out of proportion since it is maybe every 2 years, but with a new one your set is performing as if it were brand new.
The differences in the pictures of the technologies is almost impossible to detect. If you don’t want to hang your set on a wall RPTV should be given strong consideration.
As with all TV’s room lighting needs to be considered as does distance from the set.
This site is very useful and would recommend that before you purchase any expensive TV you read everything you can to understand fact from hype.
The HD Guru does a very good job.
There is just something about vibrating mirrors and spinning wheel mechanical devices that turn me off. Harks back to the invention of color TV with the spinning wheel. NTSC. Never the same color.
I’ll take direct view. I have yet to see a rear projection where the image doses not drop off when you walk around it. I had a rear projection once and dust and cobwebs formed inside the cabinet on the mirror. I could see visable shadows moving from small wind currents.
Very good explanation of the designs.