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Old 04-15-2007, 09:46 AM
hposter hposter is offline
Join Date: Mar 2005
Location: Northeastern NJ
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Color Wheels are STILL alive!

While scanning the BBC News site, I discovered this little treasure:

". . . The brainchild of Texas Instruments, Digital Light Processing (DLP) first appeared 20 years ago. The key to DLP in a video projector are optical semiconductors covered in millions of tiny mirrors. . .

There is one drawback to DLP. For a chip to produce colour images, a spinning wheel fitted with coloured filters is placed in front of it. . . "

Seems I heard something about spinning wheels to see color, and it didin't start 20 years ago! Where's Colortel when you need them?


BBC story:
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Old 04-15-2007, 10:13 AM
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KentTeffeteller KentTeffeteller is offline
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Join Date: Feb 2006
Location: Athens, TN
Posts: 587

DLP and the color wheel! How early 1950's. CBS Color TV used a spinning color wheel. The more things change, the more they stay the same!
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Old 04-15-2007, 04:40 PM
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rca2000 rca2000 is offline
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I have pointed this put MANY times!!

Single-chip DLP sets are MUCH like the old "vibrating mirror" sets that were experimented with about 70 years or so ago. Add color with a color wheel--and Voila!! You have a "old wine in a new bottle" device!!

Think abut it...A bunch of tiny mirrors vibrate back and forth to produce the picture...color addded with a color wheel..a vapor lamp provides the light...

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Old 04-16-2007, 12:46 AM
Geoff Bourquin Geoff Bourquin is offline
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Join Date: Nov 2005
Location: Northwest Washington State
Posts: 365
I just replaced one....

I just replaced the color wheel on a set that only has about 500 hours on it. When the set was cold, the motor in the wheel sounded like a big electric drill that had gotten bound up. It would quiet down after a while. This seems to be a common problem. That and the lamps burn out after 4000 to 8000 hours. And when that $300 lamp burns out, the customer chews my butt, not the sales person who didn't tell them that using the TV to listen to the digital music channels was a bad idea.
The longest lamp life I have encountered is about 7500 hours, but I know a guy who replaced one that lasted about 10000. I've seen a bunch that died at about 4000 hours.
DLP is an amazing technology, but it does have a few weak spots. I'm looking forward to seeing how the solutions work out.
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Old 04-16-2007, 09:38 PM
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Chad Hauris Chad Hauris is offline
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For a projection lamp that's really pretty good as far as the number of hours you get even if it is $300...the 1000 watt projection lamps like you'd use in a Bell and Howell film projector are only rated for 25 hour life and are pretty expensive.
Chad Hauris
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Old 04-16-2007, 10:13 PM
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RCAkid RCAkid is offline
Respect the tube!
Join Date: Jan 2007
Location: Oklahoma City, OK
Posts: 213
I have a DLP set and it would be nice if there was a more definite life to the bulbs.

On the note of the B&H projector bulbs. Yes, they are only rated for 25 hours but as a person who has 4 of these projectors and transfers a lot of film to dvd, they usually go for better than 100 plus full 1600 foot reels (I quit keeping track after that). That can translate into 100 plus hours and since the bulbs are only about 30 bucks or so, I keep extras on hand. But those are 500 watt bulbs so there may be a significant difference from the 1000 watt lamps.

Likewise in my family's old Kodak 8mm movie projector that uses a 500 watt bulb and rated for 15 hours. That bugger was about $50. I put that bulb in the projector in 1982 and snapped up two more new ones that my school was throwing away at the time. Up until about 1997, I would look at the home movies every year. We have roughly 12-14 hours of footage and that bulb is still in the projector and it still works and I am still waiting to use the spare bulbs. Go figure.

I really like the HD picture on my DLP set but it has been squirrely. After moving the set from my office to my home, I had to re-seat the lamp as the set would shut down without warning just after turning it on. It was suggested to re-seat the lamp and it has worked perfectly since. I worry about the colorwheel though and I am waiting for the colorwheel motor to crap out and goodness only knows how long the bulb will last.

I guess the manufacturer just figures the average time the bulb will last and then drops it by 500 or 1000 hours. I don't know, but it is frustrating and I would love to be able to get into the service programming for my Samsung and see just how many hours are on the thing.
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