DIY Video Projector Part II - Page 12 - diyAudio
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Old 4th July 2002, 12:01 AM   #111
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Hello,


I've been interested in all of the great ideas going on in these threads. I have not fully committed myself to it but I am thinking about it. I have 2 broken Toshiba 510CDT laptops that I am willing to experiment with. Just one problem, they have a 12" viewable screen area. Any suggestions?


I have been looking for light sources and found some cheap stage lighting equipment. The Followspot lights may be something. Please take a look.


http://www.performingartssupply.com

Pages 23 & 24 of their catalog.



Hey Mike, Altman makes a large assortment of lens. Don't know exactly where to buy them but take a look.

http://www.altmanltg.com

http://www.altmanltg.com/parts/pdf/lensglas.pdf
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Old 4th July 2002, 12:21 AM   #112
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i dont no if those light will work, but if u can find one that the bulb puts out 40,000 -60,000 lumens and last more than 3000 hr and the bulb replacement is less than $100 buck with a glass fresnel lens it just might workout, but ive never messed around with stuff like that so i would sujest reading the web or talk to people or etc.
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Old 4th July 2002, 01:23 AM   #113
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biteon,
you are correct, projection lenses/objectives don't need to have the diameter of panels size. This is indeed bulls**t which has been over and over transported through several threads. If this was true there wouln't have been neither working commercial big panel projectors nor OHP/panel projectors !!
There's only one mandatory condition: Focal lenght of objective has to be minimal diagonal size of the panel ! Better more.
And another point: The use of only a single lens as projection lens will always end in poor results due to spherical abberations !! It isn't possible to focus image's center AND corners properly with only a single lens. It will only work good with correcting elements, doublets, triplets...
Some guys should correct their website informations about this, espacially for newbies!!!!

xblocker
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Old 4th July 2002, 01:24 AM   #114
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Default ?

Does the LCD need to be an LCD Module like the ones from www.partsexpress.com or can it be, for instance, a mobile LCD monitor that i just disassemble?

here is the LCD i plan on using:

http://shop.store.yahoo.com/besttoys2/tm7001s.html
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Old 4th July 2002, 01:45 AM   #115
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Hey,

How about lighting a mirror backed LCD from the front so the light is filtered twice through the same pixel [if possible] then sent to the screen via a focal lens.
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Old 4th July 2002, 01:55 AM   #116
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1.Transmitting the panel twice means a double loss of light!
2. The mirror will offset the transmitted pixel in relation to angle of incidence.
No good!

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Old 4th July 2002, 02:07 AM   #117
Duo is offline Duo  Canada
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When you use two or more lenses to get the edges focused, how does that work? Can both lenses be the same kind of lens?
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Old 4th July 2002, 02:25 AM   #118
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Hey,


What I'm talking about is an L-shaped projector but where the mirror would normally go there would be an LCD display with a reflective backing which would send the video light down through a couple of lens for focus, then to the screen.


Just thinking.
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Old 4th July 2002, 02:41 AM   #119
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Duo,
mostly after the first convex lense there's a concave lens cemented, followed by a third which is convex again. This is a common setup.
But there are also simpler objectives which use 2 convex meniscus lenses, my first OHP had this setup. If using more than one lens the formula goes like this: 1/f=1/f1+1/f2....+1/fn

This all has already been discussed in the 1. thread....

*_if_i_know,
are there any color LCDs without backlite but refexive foil built in?
If yes, it could work, but poorly, because you have no condensor, which collimates the lightbeam, like a fresnel mirror does.

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Old 4th July 2002, 03:14 AM   #120
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Well, I'm not sure.

But I was researching and found a review of a projector, which stated that image quality, and efficiency of light was gained by reflecting the light off of the LCD. Of course it did not include any details of how this was done.

Oh it did state that micro-mirrors were used.



--- Probably each pixel area with its own concave mirror
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