Not sure,, about that,,, anything and everything is possible,, just how practicle is it on large LCD and fress like ours,,,, DAZZZLER is the master of optic puzzles,, he can puzzle over it, whilst trying to get to sleep,,, he likes chewing on impossible problems heheheheh,,,

DAZZZLER

I gotta ask after Elkens named you ! hope u dont mind..would most appreciate ur sharing of wisdom with this.
could their be a future of possibles with using the lenslets ? ..hmm wot a question at this stage..Id understand if u said u didnt know.

sling has suggested light source-->lenslet lenses-->fresnel/LCD panel
(I hope I got that right sling..)

Whats ur thoughts about lenslets and slings idea.

Thanks

I don't know

Couldn't resist
To the best of my knowledge the fisheye lens pairs work using collimated light so I don’t think they would be practical with our diverging source. If we were to use parabolic reflectors then that’s another story.
Your suggestion for using an integrator to hide the fresnel shadows produced by a 1mm arc would work but again it would need to be collimated first.

DJ

Yep... a parabolic reflector would probably be needed. Anyone have ideas on where to get that?

Thanks for your thoughts...'I dont know' is my answer as well...

Sling the parabolic reflector question..u could buy commercial lamps with the reflector built in...hey maybe not as stupid as it sounds...what about using a blown commercial lamp..could we reuse the reflector..we then need a DIY lamp to fit..?!?

Still cant get over how would we get the spread of light from the lenslet to the panel..I keep thinking of a 5" rectangular spread of light from the lenslet ....
....is it diverging ?...enuff to fill the 15" panel..can you get diverging lenslets ?!?
oops ...I should say Im refering to slings idea.

Cheers

Parabolic reflectors... DIY

http://freespace.virgin.net/ljmayes.mal/var/parabola.htm

Could we build our parabolic reflector to exactly the dimensions we need ?

Probably.
The biggest issue with parabolics or ellipticals is the dark spot created by the lack of reflector where the lamp penetrates the reflector.
I'm considering a parabolic myself at the moment. but I haven't found a diy friendly way of blending the spot out yet.

DJ

DAZZZLA,

Could Lenslets be the answer for the dark spot ?

However Im assuming your parabolic idea is for 15" panel ... ?

Big Parabolic Reflector/Light Source---->15 " LCD panel
No Fresnel or other lens before LCD.

.....hmmm do they make lenslets big enough to cover a 15" capable parabolic I wonder ?

or is your parabolic idea to use a smaller parabolic then diverge to fill the 15" or use a smaller LCD.

At the moment Im thinking the lenslets would work with 5" LCD
Parabolic Reflector/Light Source---->Lenslets (Light Integrator) 5 " LCD panel without any other lens before the LCD.

Any thoughts..Cheers

Ive been looking at parabolics..some objects that are naturally parabola's are:

Satellite Dishes
Umbrellas
Woks....yes Woks...(not the ones with a flat base)..
Some cooling fan covers
Other cooking items like sieves etc...
Light reflectors.

Or you could make your own from the shapes above or from many DIY methods available.

My pick if I were to use one would be the Wok, they come in at around 300-450mm Diameter.
Somehow have to make the internal surface very reflective...mylar...alu foil maybe ?!

Questions in my mind are:
What is the optimum depth for a full size parabola (to cover 15") LCD Panel ?
What diameter is optimum..obviously the reflected light has to cover 15 inches of LCD panel but then you are losing light around the rectangular shape of the LCD....so how to reduce the losses
A commercial reflector is sort of square shaped, meaning the light rays exit the commercial reflector to roughly the same shape as the LCD Panel....
Wouldnt we need the same...
This makes me wonder can we reduce the losses around the frame from a circular shaped parabola reflector.

Perhaps you get a larger diameter than needed and cut into the edges to make a square/rectangle somehow ?!

Now if you sort this out you then need to get over the shadow or dark spot created by the lamp itself...perhaps you could use a regular size lens array which sits in line with the lamp...if a full size lens array is not available....

Anyone care to comment...? DAZZZLA ?

I have some ideas but that’s all they are at the moment. Need more thinking time on the void problem .

DJ

Is there a reason you can't cut a hole in the back of the reflector so that the "image/shadow" of the lamp passes out the back of the reflector?

Edmund Scientific's (www.scientificsonline.com) has 3 different Parabolic Reflectors made from .040 inch thick "precision polished" aluminum. The sizes, focal lengths, & prices are 12" - 3" - $30; 18" - 4.5" - $43; and 24" - 6" - $60. They have center holes. Seems to me the 18" diameter could be squared off with out too much difficulty; 40 mil aluminjum shouldn't bee too hard to cut. The trick is to do it neatly without distorting the whole thing.

Is there a source for the arc lamps mentioned? Would they be a better option for a light source for a LL Pj?

Hi Jamie

I think that the Edmunds reflectors were tried..not sure of the results I think they were not deep enuff or some issue...anyone remember ?

The arc lamps used in the patent design are regular commercial projector lamps..expensive !

The parabolics from Edmunds were tryed, and the person failed miserably, it didn't work at all. This was because the T15 lightbulb was in the way for the reflector and it created shadows on the screen. And I think someone drilled a hole through a parabollic reflector and stuck a T15 through, that didn't work either, same problem shadows.

You can use the light efficient commercial units for your light setups, and it CAN be cheap, go to www.diypro.us and you will be lead to hundreds of bulbs you can buy from YWH for around 40-80$. This is only the bulb though, no reflector, so you will need to buy a used projector off Ebay, WITH the bulb still in it.

You dont mean Lucky_Me ?..Cant be he did say he managed to get an even light in the end and may revisit the parabolic reflector at some later date.

I agree YWH has cheap bulbs but I dont have commercial PJ's to use to make a light engine for a DIY PJ..sorta not makes sense..though it would surely work as per the patent design.

One way spoken about before is the use of an offset parabolic reflector..takes the lamp source out of the reflected light path (no lamp shadow)..

I understand no-one has tried..yet.

It would take some calculation to figure a design and then make it work..someone from the diyaudio forum (I keep mentioning) suggested using an offset parabolic sat dish..lined with alu foil..the lamp replacing the LNB...
but you would have to have another reflector behind the lamp source...trying to align this all to make it work would be tricky...and bulky.

Another suggestion is to use a deep Parabola to lessen the loss of rays not normally reflected in a shallow parabolic reflector...however I guess this only makes it more efficient..

Then of course the elliptical reflector seems another possibility to capture as many rays as possible.

I like the idea of a parabola even with possible shadow issues..one would think that there would be a sweet spot where that shadow would be less..also ways to make it better ...use as small an arc lamp as possible.

All this might make it usable.

only one problem..not many parabolas out in the world that could be of use as a DIY reflector to try...

Actually using a small arc would make the void more defined.

DJ

Me2! also tried the Edmund parabolic and gave up on it.

OK Im getting back to what this thread was about with this post..the patent to use multiple light sources.

Just a quick recap clarity systems is the owner of the patent.. the company produce large Rear Projection Displays for all kinds of gov/business needs.

This patent is for the stackable 67" rear pro dispaly using a single 15inch LCD panel.
Essentially you could think of the product as a 67" inch RPTV..though no tuner..

Ive found some more info on this display which the patent refers..it may shed a little more light .....first though it looks like clarity have dropped their 4 x 100watt UHP lamp design in favour of 2 x 200w UHP lamp design..see the pictures...though the light engine looks essentially unchanged..(as patent) and looks remarkably like "mikyd1954" idea.

The pictures follow the light engine thru to screen and for anyone who has read the patent pdf which this thread is about will immediatley recognise the components used..

Maybe whats of interest is the small size light source is expanded to fill the 15inch LCD through a "proprietory relay lens"

The first objects that the rays meet from the lamps I believe are the two lenslets to even the rays.

I still have to wonder about the lossiness of the configuration overwhelming the use of two light sources. Before the light even gets to the LCD, it has gone through a prism (thick glass mirror combo), two polarizers, a precondensor and a "proprietary relay lens". Certainly, this is not a "times 2" configuration from a light standpoint, is it? Seems also that any space saving for miniturization purposes leaves the lightgate still equivalent to a stick shaped single bulb of higher power.

But, maybe I just don't get it.

weldonjb

hehe you are entitled to your say and you said it..

Im thinking from your comments that you think a single lamp is better....
My thoughts are ..the company came up with this design for more than one reason:

it's brighter to have more than one lamp..not 2x..I agree
redundancy ..1 lamp fails they dont get called out..
third the design is such that brightness is even across the display...crucial as these displays are stacked to produce mega size displays.
lastly the wide angle lens before screen minimizes the length of the light path to screen..enabling the rear pro display to be small form factor...remember they stack.

btw Im not sure if that is a prism..if you look at the patent, mirrors are used. Post #70 pic seems to back that up.

Croma, you are very correct. I was being myopic about DIY projector issues. heh I would bet this is a very good solution for a commercial, stacked multiscreen display. I was more focused on stealing the idea for my projector! LOL That, and thinking what an image would look like using AZ's megawatt style lighting x2. Dropped into mathematical Mr. Spock mode, sorry.

Of course, there is another factor. With the "normal" approach of using a spherical reflector to get the light to pass back through the arc, you lose a good bit of light that is not within either the arc of the fresnel forward or backward. That is about two thirds of the light in the absence of a precondensor.

This solution uses a parabolic reflector, and therefore probably utilizes 3/4 of the total light output of each bulb (though more of the light must reflect against a surface with loss). I wonder if the gain from the greater light usage would balance out the extra loss from the various extra lensing/mirroring? Hmmm

Thanks for the pic. I can see now how the two separate lamps are mixed so that they both illuminate the LCD. Looking at the original patent the mirrors reflected all of the collimated beams to illuminate sections of the LCD. But this new design only reflects half the beam to the LCD and the other half continues on to the other parabolic reflector where it is then returned to illuminate the other half, Very nice. If we could find a couple of reasonable parabolas we may have a shot at something DIY friendly. As for using this method for our diverging light engine I don’t think is would work. I see they’ve also added a polarizing recycler

edit:
Actually I shouldn’t call it a polarizing recycler, it’s more of a polarizing converter.

Perhaps a couple of car driving lights could be used for the reflectors. I can get some reasonable ray light reflectors but they aren’t very deep so they may not collect enough of the arc. By keeping it big makes for easier adjustments. Hmmm

maybe we could even combine two different types of lamp to obtain that magic RGB mix

DAZZZLA

Great you saw more than I did looking at the pics...the way they recycle the light between the 2 reflectors..neat.

When you say it wont work for a diverging light engine ..do you mean a 'twin lamp diverging light engine ' ? like trying to use elliptical reflectors ?

The designers approach means we could use smaller ..perhaps more findable parabolas...(hopefully cheaper)!

OK..can you help explain how the 'polarizing recycler' works and what it is.

Older car headlamps are more likely to be uniformly parabolic, perhaps deep enough..perhaps cheap enough (if not for a classic)

no problemo the thread is for discussing.
Im hoping that more knowledge can be gleamed from the design that may be used to take us a bit further, it certainly though isnt suggesting we all go out and copy the design instead lets see what is possible... lets see what we can use from it.

Cheers

hey...just searching the new google patent engine...most cool.... heres a dual lamp system...very similar to what paladin proposed a few weeks ago in my plog
http://www.google.com/patents?vid=USPAT550...le+lamp#PPP2,M1
off in search of more goodness

Here's a retail DLP unit from projectionDesigns that uses dual lamps to raise the brightness...

And Here is a link to a review of it that gets into some depth about the design and performance.

The unit retails for $24,995 right now. That includes a video processor that scales everything up to 1080p.