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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon Jan 04, 2010 5:23 am Post subject: |
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| garyfritz wrote: | | macgyver655 wrote: | | There is more then 1 mirror per pixel. |
Nuh-uh. I can't find an authoritative source that explicitly says 1 mirror per pixel, but that dlp.com site I cited earlier says DLP chips contain "up to 2 million hinge-mounted microscopic mirrors." 1920*1080 = 2,073,600. Google "dlp mirror per pixel" and you'll find plenty of non-authoritative sites that say it's one mirror per pixel.
| Quote: | | OH, I remember now. This is the difference between brightness and contrast. How long its on is brightness and a group is for contrast. |
No, one mirror = one pixel. How long determines brightness, but there's nothing about contrast. The pixel is just on from 0% to 100% brightness.
As far as I know there's nothing in the DLP implementation that groups pixels. You may be thinking about the dithering effects that are visible with DLPs in low-light areas? That comes from adjacent mirrors flipping on at different times, if I understand right. |
Gary. You have to realize that in my mind I have almost every style of display devices just jostling around. And were talking of having had hands on experience. Its possible I'm confusing the group LED dimming in the local dimming LCD flat panel, with the DMD. I guess the point is and I dont mean this sarcastically but I dont care. All I know is if the DMD fails I have to replace it. Again Gary, I dont mean that in a bad way. 
I'm actually more interested in the G90 sitting in front of me here in the motorhome thinking about having to put the tubes in and fire it up.
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Mon Jan 04, 2010 5:27 am Post subject: |
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No problem, Mac. I'm certain you've forgotten 10x more about display technology than I'll ever know. That happens when you stuff several craploads of knowledge between your ears. But since you DID forget a point here, I didn't want it to confuse anybody else. 
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Mon Jan 04, 2010 5:27 am Post subject: |
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I'm confused....
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CRT.
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macgyver655
Joined: 22 Aug 2007
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| Posted: Mon Jan 04, 2010 5:28 am Post subject: |
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| garyfritz wrote: | | No problem, Mac. I'm certain you've forgotten 10x more about display technology than I'll ever know. That happens when you stuff several craploads of knowledge between your ears. But since you DID forget a point here, I didn't want it to confuse anybody else. |
That's fine Gary. Sometimes my head just hurts..... 
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macgyver655
Joined: 22 Aug 2007
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| Posted: Mon Jan 04, 2010 5:29 am Post subject: |
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| AnalogRocks wrote: | | I'm confused.... |
About what?
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AnalogRocks
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Joined: 08 Mar 2006
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Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Mon Jan 04, 2010 5:31 am Post subject: |
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| macgyver655 wrote: | | AnalogRocks wrote: | | I'm confused.... |
About what? |
Where I put my drink.....
never mind, carry on
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macgyver655
Joined: 22 Aug 2007
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| Posted: Mon Jan 04, 2010 5:32 am Post subject: |
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| AnalogRocks wrote: | | macgyver655 wrote: | | AnalogRocks wrote: | | I'm confused.... |
About what? |
Where I put my drink.....
never mind, carry on |
LOL. I'm pretty much done....
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon Jan 04, 2010 5:33 am Post subject: |
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Actually I'm tempted to go look up my DLP training manual but I just dont feel like reading....
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AnalogRocks
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Joined: 08 Mar 2006
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Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Mon Jan 04, 2010 5:35 am Post subject: |
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| macgyver655 wrote: |
I'm actually more interested in the G90 sitting in front of me here in the motorhome thinking about having to put the tubes in and fire it up. |
NOW we're talkin'
How's one of those work? Please provide detailed instruction.
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macgyver655
Joined: 22 Aug 2007
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| Posted: Mon Jan 04, 2010 5:39 am Post subject: |
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| AnalogRocks wrote: | | macgyver655 wrote: |
I'm actually more interested in the G90 sitting in front of me here in the motorhome thinking about having to put the tubes in and fire it up. |
NOW we're talkin'
How's one of those work? Please provide detailed instruction. |
I actually thought there would be more comments on the pictures I posted..... 
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macgyver655
Joined: 22 Aug 2007
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| Posted: Mon Jan 04, 2010 5:53 am Post subject: |
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| ecrabb wrote: | | macgyver655 wrote: | | I do not wish to get into every specific operation of every minuet operation of the projector. Everyone can search for specific info. I really dont have time to get to involved with this. Sorry. |
No problem, Mac. I'm just saying... As far as I know, for anything recent/current, there's a mirror on the DMD array for each pixel on screen. So, for a 1080p projector, the DMD has an array of 1920x1080 mirrors on the DMD, or exactly 2,073,600 mirrors. Or, in a 3-chip machine, 3 separate DMD's, with 2,073,600 mirrors each.
Pixel brightness is modulated by binary pulse width on the DMD mirrors. Real contrast (both on/off and ansi) is a fixed parameter, a combination of bulb brightness and light engine and lens design/performance. We'll leave things like image processing and variable iris out of the discussion for sake of simplicity.
SC |
This is why I also dont comment much when someone has a resolution question. As a repair guy, these specifics dont really matter. If there is an issue with some mirrors not turning on, I dont care which mirrors should be on in a certain location, my only concern is which failed part do I need to find and replace.
So this is why the specific operation of the DMD doesn't concern me...... But the light path does as does the function of the devices in the light path, but not specific function, just general. Color wheel RPM? doesn't matter to me. Is it spinning or shattered, does matter. Is a lens or mirror dislodged? Matters... how does the lens refract? Doesn't matter.
It still seems to be in the back of my head about the group mirror issue but I cant confirm without doing some reading so I can only say I am unsure on that issue. But I usually remember correctly, thats what bugs me.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Mon Jan 04, 2010 6:21 am Post subject: |
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Thanks for the Lesson Mac, good basic info here.
And for me it kinda helps me understand why I think DLP displays look flat or one dimensional to me with no depth. its the mirrors reflecting the light, they are perfectly flat. Now this is just my own Theory , with a CRT the phosphor has a bit of depth to it on the inside of the tube face. so its possible that there is an intensity variance in the light and also distance of the light to the optics due to that slight thickness which can give the effect of an image with more depth and dimensionality more so than the light being collected by the optics off a perfectly flat mirror.
I myself and others just think CRTS have more depth to images, does my theory hold any water or is it just totally wrong?
Athanasios
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macgyver655
Joined: 22 Aug 2007
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| Posted: Mon Jan 04, 2010 6:28 am Post subject: |
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Ah, I found my brain malfunction. I knew I remembered something about the group mirror issue. Had to do some reading though so now I have a headache......
Quote:
The minimum of a partial update is data transfer for one DMD line and the rest of one block of mirrors. The maximum switching rate for such a partial update is in the range of 50 kHz ??
The DMD is updated in two independent steps:
i)New data is written into the SRAM cells under each DMD mirror.
ii)The mirror states (off/on == +12/-12) are then updated according to the new data in the SRAM cells; this mirror reset operation is applied to a horizontal array mirrors in a block (phased reset) or to the whole array simultaneously (global reset).
So it is during the update process that a group or block of mirrors are reset. I knew it was a group for something.
Now I feel better. I just had the file in the wrong drawer in my head.....
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macgyver655
Joined: 22 Aug 2007
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| Posted: Mon Jan 04, 2010 6:33 am Post subject: |
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| Nashou66 wrote: | Thanks for the Lesson Mac, good basic info here.
And for me it kinda helps me understand why I think DLP displays look flat or one dimensional to me with no depth. its the mirrors reflecting the light, they are perfectly flat. Now this is just my own Theory , with a CRT the phosphor has a bit of depth to it on the inside of the tube face. so its possible that there is an intensity variance in the light and also distance of the light to the optics due to that slight thickness which can give the effect of an image with more depth and dimensionality more so than the light being collected by the optics off a perfectly flat mirror.
I myself and others just think CRTS have more depth to images, does my theory hold any water or is it just totally wrong?
Athanasios |
I have yet to watch anything that has an enjoyable picture to watch other then CRT.
I have an LCD here in the motorhome and I dont mind watching it, of course I'm not real picky, but I immediately notice a difference when I see a CRT based display. Plasma is ok but I still notice the CRT quality difference.
I'll be a die hard to the end.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Mon Jan 04, 2010 6:37 am Post subject: |
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| macgyver655 wrote: | | Nashou66 wrote: | Thanks for the Lesson Mac, good basic info here.
And for me it kinda helps me understand why I think DLP displays look flat or one dimensional to me with no depth. its the mirrors reflecting the light, they are perfectly flat. Now this is just my own Theory , with a CRT the phosphor has a bit of depth to it on the inside of the tube face. so its possible that there is an intensity variance in the light and also distance of the light to the optics due to that slight thickness which can give the effect of an image with more depth and dimensionality more so than the light being collected by the optics off a perfectly flat mirror.
I myself and others just think CRTS have more depth to images, does my theory hold any water or is it just totally wrong?
Athanasios |
I have yet to watch anything that has an enjoyable picture to watch other then CRT.
I have an LCD here in the motorhome and I dont mind watching it, of course I'm not real picky, but I immediately notice a difference when I see a CRT based display. Plasma is ok but I still notice the CRT quality difference.
I'll be a die hard to the end. |
Nashou
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Mon Jan 04, 2010 8:24 am Post subject: |
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OK, whether it's leds or a colour wheel, with sequencial colours the rainbow problem is still there - as far as I can figure.
Unless they are doing a much faster sequence of colours with the leds, but the leds will take some time to turn off, so there will be limits..
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garyfritz
Joined: 08 Apr 2006
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Location: Fort Collins, CO
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| Posted: Mon Jan 04, 2010 2:17 pm Post subject: |
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They DO switch the LEDs much faster than color wheels. Given that most people don't see rainbows with current wheels, I'm sure 99.99% of the people won't see them with LEDs. There may still be a few of us hyper-sensitive types who notice it, but even then it will be MUCH less noticeable because the rainbows will be "smaller."
I can't remember how fast the switch them. I remember being surprised that it wasn't any higher -- it was maybe 2-3x faster than current wheels, or less. Obviously they weren't too concerned about totally getting rid of rainbows for that last 0.001%.
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dturco
Joined: 06 Feb 2009
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Location: Eastern Shore Maryland
TV/Projector: Runco DLP VX-3000i Marquee 9500 parts doner
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| Posted: Mon Jan 04, 2010 2:38 pm Post subject: |
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That looks awesome, like air condition coils for cooling. Very cool
I'm sure that diagram is missing a whole lot of items but it looks straight forward.
Oh and I am sitting 1 row back in the Class. I'm not the back row slacker, or the front row brownnoser, I just want to learn.
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tse
Joined: 03 May 2006
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Location: Sweatbucket, Fl.
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| Posted: Tue Jan 05, 2010 1:53 am Post subject: |
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There is one mirror on the DMD for each pixel. The mirrors are pulse width modulated to control the light from each mirror/pixel. Less "on" time makes a darker pixel, more "on" time makes a brighter pixel.
The DMD is configured for the red image, the red LED comes on the light reflects out the lens. The red LED turns off and the DMD sets up the green image then the green LED turns on. Continue for blue. This way you get full color with one DMD. Simple and few parts. Drawback is any one LED is only on for 1/3 of the time. 2/3 of the time it is not producing any light.
Three DMD devices would let you run the LEDs pretty much all the time which could triple the light output. Much more complex optics, imagine converging the three colors.
The LEDs in the current projectors run at the equivalent of a color wheel spinning 20 revolutions per picture frame. It's supposed to eliminate the rainbows and I have to say that I don't see any.
The LEDs have a much wider color gammut than CRTs. The colors are very intense. Deep, deep reds and greens. Makes a CRT look very pastel.
It is a very nice looking projector. The LEDs beat the crap out of arc lamps. You can turn them on and off. You don't have to worry about warm up or cool down. I'm sure they will get brighter with more development and will probably obsolete arc lamps for home type projectors.
Scott
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macgyver655
Joined: 22 Aug 2007
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| Posted: Tue Jan 05, 2010 2:13 am Post subject: |
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| tse wrote: | There is one mirror on the DMD for each pixel. The mirrors are pulse width modulated to control the light from each mirror/pixel. Less "on" time makes a darker pixel, more "on" time makes a brighter pixel.
The DMD is configured for the red image, the red LED comes on the light reflects out the lens. The red LED turns off and the DMD sets up the green image then the green LED turns on. Continue for blue. This way you get full color with one DMD. Simple and few parts. Drawback is any one LED is only on for 1/3 of the time. 2/3 of the time it is not producing any light.
Three DMD devices would let you run the LEDs pretty much all the time which could triple the light output. Much more complex optics, imagine converging the three colors.
The LEDs in the current projectors run at the equivalent of a color wheel spinning 20 revolutions per picture frame. It's supposed to eliminate the rainbows and I have to say that I don't see any.
The LEDs have a much wider color gammut than CRTs. The colors are very intense. Deep, deep reds and greens. Makes a CRT look very pastel.
It is a very nice looking projector. The LEDs beat the crap out of arc lamps. You can turn them on and off. You don't have to worry about warm up or cool down. I'm sure they will get brighter with more development and will probably obsolete arc lamps for home type projectors.
Scott |
Got any pics of the inside of that one? Are they using similar LED cooling?
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