[cromaclearcrt]

This might be of interest,
A patent design for projectors to use up to four lamps rays together to provide a single light source using direct view 15 inch LCD displays like we are using.

The design talks about using 1mm arc commercial lamps (expensive!) however Elken is currently testing a DIY 1mm arc lamp.

The Pdf also talks about a/g removal and methods of increasing contrast.


http://www.freepaten...om/6924849.html

Once your on that page.. view the detailed patent design and see the design drawings
by clicking on:

"View PDF Images" (just below "Publication Date:") it will open the pdf within the browser, you then can save a copy to your machine for viewing later.


Never really delved into looking at patents, Me2's talk of patenting his ideas got me looking.
Found another patent that talks about using LED's as an auxillary light source together with the main light source to compensate for the lack of RED in our lamps and WHITE LED's so that the Projector can be watched instantly when power is applied !

This post has been edited by cromaclearcrt: 27 August 2006 - 02:16 AM

[PLJack]

Sounds very interesting. Unfortunately I can't read the PDF file. Downloads at 5K. Hmm....

[cromaclearcrt]

PLJack

Sorry ...it appears that you cant link directly to the PDF, apologies i should have checked first.

I will edit the first thread...so now just goto the html link

http://www.freepaten...om/6924849.html then on that page click on the link that says

"View PDF Images" (just below "Publication Date:") it will open the pdf within the browser, you then can save a copy to your machine for viewing later.

Cheers

PLJack, on Aug 27 2006, 05:07 AM, said:

Sounds very interesting. Unfortunately I can't read the PDF file. Downloads at 5K. Hmm....

This post has been edited by cromaclearcrt: 27 August 2006 - 01:53 AM

[SIMUL8R]

cromaclearcrt, on Aug 26 2006, 06:44 PM, said:

PLJack

Sorry ...it appears that you cant link directly to the PDF, apologies i should have checked first.

I will edit the first thread...so now just goto the html link

http://www.freepaten...om/6924849.html then on that page click on the link that says

"View PDF Images" (just below "Publication Date:") it will open the pdf within the browser, you then can save a copy to your machine for viewing later.

Cheers

There is still no PDF to save at your corrected link.

[tgreenwood]

That's strange, the pdf link worked fine for me.

On the HTML page, the pdf link is there, and works. Wait, let me check something...........
Well, that's interesting....... I just checked and the pdf link works in IE but doesn't work in Mozilla Firefox.

Tgreenwood

[cromaclearcrt]

Seems that the website is a tad flaky..for me it works in both Firefox and after a couple of refreshes in IE (after clearing browser cache.)


I tried uploading the pdf but error says something about not having the right permissions..?!


SIM, PLJack and anyone having trouble getting this to work PM ur email and I will send it ..no worries

Cheers

[johnzo1995]

Why dont you guys try USPTO website. I alreadly checked the patent its pretty cool.

6924849

[cromaclearcrt]

Johnzo,

Thanks for the alternate link...for all if you use Johnzo's link you will have to install a TIFF
plugin to your browser to view the detail and the design drawings. I used:

http://www.alternatiff.com

To view the the orgiinal patent (includes all the drawings) click "Images"

johnzo1995, on Aug 28 2006, 02:14 PM, said:

Why dont you guys try USPTO website. I alreadly checked the patent its pretty cool.

6924849

This post has been edited by cromaclearcrt: 28 August 2006 - 11:03 AM

[paladin]

Here's the patent zipped up.
 Patent.zip (231.52K)
Number of downloads: 546

[cromaclearcrt]

Thanks Paladin !

paladin, on Aug 28 2006, 09:12 PM, said:

Here's the patent zipped up.
attachment

[paladin]

cromaclearcrt, on Aug 28 2006, 06:16 AM, said:

Thanks Paladin !

No problem, mods have a higher upload limit.

Croma,

That is an outstanding find!! Aside from the multiple lamp design, which appears to be difficult to implement, there are other things
mentioned I've never seen anywhere else. Such as purposely sending light through the LCD panel at a small angle to maximize
contrast and use of a polarization rotator to improve corner brightness.

I am pinning this thread.

[PLJack]

What a PITA PDF! Good grief.
For those of you having as hard a time as I did, I've attached an image of the juicy bit.
Looks very interesting.

Patent No: US6,924,849 B1


BTW, never drag a PDF into Photoshop. The conversion nearly took down my PC.

[elken2004]

That PDF makes for excellent reading,, and it has confirmed several points that I have suspected for a long time..

[Sling_Blade]

Uhg... my head hurts from reading that but ugly PDF. Anyway... here are some interesting things I pulled away from it. For those of you who don't want to read, these are my cliff's notes =P

The first part of the paper discusses using multiple projectors for a bigger display, and how the projectors can be constructed to make them easily "stackable". Not much of an application for us... we're sticking with 1 projector.

Figure 10 shows an LCD sandwiched between two fresnels "having centers that are offset to direct light rays through the LCD panel at an optimal ray angle for achieving a peak contrast ratio from the LCD panel". The angel shown in the picture is 5% off of normal. I think this could be achieved with a very slight split design lens shift. I've never heard that LCDs look better having light comming into them at a slight angle. Latter in the paper they say that the exact angle needed is particular to the LCD construction, and that it is determined by emperical measurement.

Has anyone ever observed this? If this were true this would mean that unsplit designs would have better contrast near the edges. I suppose it is possible this is true... it just hasn't been noticed because our lighting is rarely even. One thing they don't mention is the distortion created by a split design from the fresnels or how they plan to get around that. They also talk about why having small light sources close together is better... again to control the angle that the light hits the LCD to improve contrast.

The method explained for removing layers from the LCD sounds much more envasive than what is currently being done at LL. In addition to what LL members have removed, they remove a "Wide Viewing Angle" film (which I haven't heard of) that they say reduces contrast in order to increase viewing angle. They take pretty much every layer apart. From what I gather, the ONLY thing used from the original LCD is the TFT and liquid crystal layer, and the polarizing layers (although they say they are removed... and unless they can do this without damaging they'd have to use new ones). A "Wide band rotator" layer is added... more on that in a sec. Also... they mount the LCD "backwards" so that the "black mask" in the liquid crystal layer blocks "unintentional photoconducting". I assume they mean it keeps unwanted light from passing through =P

Apparently a "Wide band rotator" is designed to turn the horizontally polarized light from the light source, to diagonally polarized light for the first polarizer, then after it passes through the 2nd polarizer it rotates it back to be horizontally polarized again. Apparently most projectors diagonally polarize their light. This appears to mostly be to help their multi-screen technology. The distortions they say it can cause appears to be most visible when trying to match the edges of multiple diagonally polarized projectors. I haven't heard of anyone complaing about diagonal polarization here... so I don't think we need to worry about "Wide band rotators"

The light source is suggested to be 4 120W Philips UHP100 bulbs. These are made for rear projection TVs I think... they're expensive. However, the paper states that any lamps having 1mm to 7mm arc gaps are suitable. Through the use of parabolic reflectors and a "pinwheel mirror" the paper claims that the light is very collimated. (+-3 degrees). The pinwheel mirror is 4 mirrors, each with 1 corner touching the rest, and resting at a 45 degree angle. This can effectively place the 4 light source's focal points very close to each other. The goal is NOT to have each light light a different portion of the screen, but rather for all 4 light sources to light the entire screen. Another benifit to the pinwheel is that the "light bundle" is now in a generally rectangular shape now.

After this the light is shot through two "lenslet arrays". I wasn't familiar with this term but I found a good paper on it:

http://www.zemax.com...rojector-Optics

Note this paper says a 11x9 array is optimal.

If we can find a cheap source of lenslet arrays... (which I wouldn't think hard) we should certainly be able to greatly improve our "ROX".

[DAZZZLA]

Sling_Blade, on Aug 29 2006, 01:50 PM, said:

Figure 10 shows an LCD sandwiched between two fresnels "having centers that are offset to direct light rays through the LCD panel at an optimal ray angle for achieving a peak contrast ratio from the LCD panel". The angel shown in the picture is 5% off of normal. I think this could be achieved with a very slight split design lens shift. I've never heard that LCDs look better having light comming into them at a slight angle. Latter in the paper they say that the exact angle needed is particular to the LCD construction, and that it is determined by emperical measurement.

Has anyone ever observed this? If this were true this would mean that unsplit designs would have better contrast near the edges. I suppose it is possible this is true... it just hasn't been noticed because our lighting is rarely even. One thing they don't mention is the distortion created by a split design from the fresnels or how they plan to get around that. They also talk about why having small light sources close together is better... again to control the angle that the light hits the LCD to improve contrast.

I’ve seen this mentioned before but on another forum. You can see this affect if you look at a LCD monitor from below the normal view height. The screen gets a lot dimmer at the top. I think this was a big problem with allot of older LCDs.

Quote

The method explained for removing layers from the LCD sounds much more envasive than what is currently being done at LL. In addition to what LL members have removed, they remove a "Wide Viewing Angle" film (which I haven't heard of) that they say reduces contrast in order to increase viewing angle. They take pretty much every layer apart. From what I gather, the ONLY thing used from the original LCD is the TFT and liquid crystal layer, and the polarizing layers (although they say they are removed... and unless they can do this without damaging they'd have to use new ones). A "Wide band rotator" layer is added... more on that in a sec. Also... they mount the LCD "backwards" so that the "black mask" in the liquid crystal layer blocks "unintentional photoconducting". I assume they mean it keeps unwanted light from passing through =P

The Wide Viewing Angle film they mention is I believe Anti-Glare.
There has been some testing done by DIYers for the best direction for light to travel though the LCD. From what I’ve read and from my own experience you would be hard pressed to see any difference. Photoconduction refers to the transistors used in the LCD produce electrical current when light falls onto them so the mask is there to shield them from light. I remember on another forum someone talked to the designer of the SGI LCD and designer said that it wouldn’t make much difference which way the light travelled. Again I haven’t observed any ill effects, although it could be possible.

Quote

Apparently a "Wide band rotator" is designed to turn the horizontally polarized light from the light source, to diagonally polarised light for the first polariser, then after it passes through the 2nd polarizer it rotates it back to be horizontally polarized again. Apparently most projectors diagonally polarize their light. This appears to mostly be to help their multi-screen technology. The distortions they say it can cause appears to be most visible when trying to match the edges of multiple diagonally polarized projectors. I haven't heard of anyone complaing about diagonal polarization here... so I don't think we need to worry about "Wide band rotators"

I think they have actually removed both polarisers and placed new ones, horizontally and vertically orientated, into the rotators for fine adjustments. This they say helps with multiple stacked projectors.


DJ

[cromaclearcrt]

Guys I know that PDF is quite detailed but Ive found some more of potentially of use patent designs:

Instant-on projector
http://www.freepaten...om/6988806.html


Single-path color video projection systems employing reflective liquid crystal display devices
http://www.freepaten...com/6839095.htm


Achieving color balance in image projection systems by injecting compensating light in a controlled amount
http://www.freepaten...om/6698892.html


Illumination systems employing corrective optics for use in reduced
etendue color video projection systems
http://www.freepaten...om/7055967.html


Cheers

This post has been edited by cromaclearcrt: 29 August 2006 - 09:52 AM

[Sling_Blade]

DAZZZLA, on Aug 29 2006, 07:22 AM, said:

I’ve seen this mentioned before but on another forum. You can see this affect if you look at a LCD monitor from below the normal view height. The screen gets a lot dimmer at the top. I think this was a big problem with allot of older LCDs.

Well... I think this is related to the "Wide Viewing Angle" film now that I think of it. If it remains on the panel, you wouldn't see this effect be nearly as pronounced. What you are talking about sounds exactly like what the Wide Viewing Angle film is suppose to prevent. This must be how manufactuers have improved LCD viewing angle.

DAZZZLA, on Aug 29 2006, 07:22 AM, said:

The Wide Viewing Angle film they mention is I believe Anti-Glare.

No I don't think this is the case. They claim the WVA film is in the Liquid Crystal layer. They claim the Anti-glare film is on the polarizer. They speak of the two as completely seperate.

DAZZZLA, on Aug 29 2006, 07:22 AM, said:

There has been some testing done by DIYers for the best direction for light to travel though the LCD. From what I’ve read and from my own experience you would be hard pressed to see any difference. Photoconduction refers to the transistors used in the LCD produce electrical current when light falls onto them so the mask is there to shield them from light. I remember on another forum someone talked to the designer of the SGI LCD and designer said that it wouldn’t make much difference which way the light travelled. Again I haven’t observed any ill effects, although it could be possible.

Ya I hadn't heard this either... maybe this was a problem with the LCDs this inventor was using?

DAZZZLA, on Aug 29 2006, 07:22 AM, said:

I think they have actually removed both polarisers and placed new ones, horizontally and vertically orientated, into the rotators for fine adjustments. This they say helps with multiple stacked projectors.

I agree this is probably not something of much interest for us (unless someone wants to use multiple projectors). My understanding however was that LCDs normally diagonally polarize light, each side in the opposite diagonal direction. The WBRs were designed to produce horizontally polarized light. However I did re-read what they said and they did mention having to replace one of the polarizers. I don't think it's polarizing direction is any different though... obviously this would not work with the original polarizer if they did. They say:

"Light propagating through substrates 96[TFT] and 98[Liquid Crystal Layer] is typically diagonally polarized. WBR 118 receives horizontally polarized light from the light source 70 and delivers through polarizer 120 diagonally polarized light to substrate 98. Likewise, WBR 114 receives diagonally polarized light from polarizer 102 and delivers horizontally polarized light to substrate 116. "

Anyway great find on the patent. It wouldn't surprise me if some here had already thought of some of these ideas, but seeing it in a patent really gives the idea weight as something viable. Way to go =P

This post has been edited by Sling_Blade: 29 August 2006 - 01:14 PM

[samuraijack]

cromaclearcrt, on Aug 29 2006, 04:41 AM, said:

Guys I know that PDF is quite detailed but Ive found some more of potentially of use patent designs:

Instant-on projector
http://www.freepaten...om/6988806.html
Single-path color video projection systems employing reflective liquid crystal display devices
http://www.freepaten...com/6839095.htm
Achieving color balance in image projection systems by injecting compensating light in a controlled amount
http://www.freepaten...om/6698892.html
Illumination systems employing corrective optics for use in reduced
etendue color video projection systems
http://www.freepaten...om/7055967.html
Cheers

Alright. I donloaded and read that PDF. It IS butt ugly. Fascinating read though. Im thinking the angle of the light might have something to do with the transistor alignment. I think I heard elken speak about this before in difference in the twist paterns etc. I suppose its possible that certain layout patterns might allow more light through at certain angles, but you have to wonder if it damages the clarity in any way.
The light engine is interesting. They say it is designed to cover the whole LCD from each light source, but it looks like it was adressing 1/4 of the panel. Has anyone done a raytrace for this?

I cant tlook at that drawing without thinking of a VW air cooled engine.

[Sling_Blade]

samuraijack, on Aug 29 2006, 01:06 PM, said:

They say it is designed to cover the whole LCD from each light source, but it looks like it was adressing 1/4 of the panel. Has anyone done a raytrace for this?

No this isn't the case. The reason for using small arc lamps with the pinwheel reflector is to effectively place these light sources so close together, relative to the huge size of the LCD screen, that they act like a single source. The diffusing lenslet arrays further evens out the light from the different sources.

[samuraijack]

Sling_Blade, on Aug 29 2006, 10:19 AM, said:

No this isn't the case. The reason for using small arc lamps with the pinwheel reflector is to effectively place these light sources so close together, relative to the huge size of the LCD screen, that they act like a single source. The diffusing lenslet arrays further evens out the light from the different sources.

I know thats not the case but if you look at the design, it SEEMS ( Im stressing the word SEEMS here...)to look like it would cover a 1/4 of the panel. Im just wondering about the accuracy of the drawings. I was kinda hoping someone would raytrace this one to see how it behaves.

Any takers?

[samuraijack]

samuraijack, on Aug 29 2006, 10:48 AM, said:

I know thats not the case but if you look at the design, it SEEMS ( Im stressing the word SEEMS here...)to look like it would cover a 1/4 of the panel. Im just wondering about the accuracy of the drawings. I was kinda hoping someone would raytrace this one to see how it behaves.

Any takers?

Never mind I did a really rough simlation and it actually works out pretty nice. I was surprised at the spread across the panel. VERY interesting. Makes the design array I was working on look quite a bit less efficient.

[paladin]

Mirror 172 seems too short to capture all light coming down from output lenslet 170. And the diameter of lenses 174 and 176 seems
too small to capture all light from mirror 172 if it were larger. I think the lens diameters should match the size of lenslet 170.

[DAZZZLA]

I’m with SJ on the ¼ screen illumination. I drew up a rough raytrace in Raytrace last night but Raytrace doesn’t have a fisheye lens so I simulated one. It was way too tedious to see exactly what was going on so I read up a bit more about integrators. From what I could gather the fisheye lens adjusts for the arc length so that the ray angles from either ends of the arc seem to be coming from the centre of the arc.
It seems to me that it is basically four collimated beams reflected from four individual mirrors angled so that each beam illuminates ¼ of the total. The pair of fisheye lenses (integrator) then smooths the individual beams as well as smooths the transition between them to form one seamless total. The advantage of using four individual beams as opposed to just one is that the light evenness that a fisheye lens adds to a one beam set up can be further enhanced by splitting it into four.
Some of the ideas in the pdf seam a bit vague. One thing I noticed is that the integrator doesn’t seem to have all three components, two fisheye lenses and another plain lens, so maybe there is something I’m missing.

DJ

edit:
Hang on. Maybe the third component of the integrator is the ashperical lens 174. Now I’ll have to draw another trace to see if it overlays all four beams.

[samuraijack]

DAZZZLA, on Aug 29 2006, 11:43 AM, said:

I’m with SJ on the ¼ screen illumination. I drew up a rough raytrace in Raytrace last night but Raytrace doesn’t have a fisheye lens so I simulated one. It was way too tedious to see exactly what was going on so I read up a bit more about integrators. From what I could gather the fisheye lens adjusts for the arc length so that the ray angles from either ends of the arc seem to be coming from the centre of the arc.
It seems to me that it is basically four collimated beams reflected from four individual mirrors angled so that each beam illuminates ¼ of the total. The pair of fisheye lenses (integrator) then smooths the individual beams as well as smooths the transition between them to form one seamless total. The advantage of using four individual beams as opposed to just one is that the light evenness that a fisheye lens adds to a one beam set up can be further enhanced by splitting it into four.
Some of the ideas in the pdf seam a bit vague. One thing I noticed is that the integrator doesn’t seem to have all three components, two fisheye lenses and another plain lens, so maybe there is something I’m missing.

DJ

edit:
Hang on. Maybe the third component of the integrator is the ashperical lens 174. Now I’ll have to draw another trace to see if it overlays all four beams.

Seems like the actual drawing and the theory dont quite mesh together. His description definitely says they are 4 sections of collimated light moving into a "lenslet array" ( Im thinking thats a mild fresnel?)
So Im not sure how thats supposed to cover the whole LCD. But he is talking about a rectangle of light thats only 5 inches across. Page 10, second column, line 15.

Still its got my noodle goin...

[Sling_Blade]

For those of you confused about the lenslet array like I was when I first read the patent, I highly suggest the zemax article I posted. Page 4 of the article in particular. It looks like a fantastic way to distribute the light.

Those still puzzled by how the 4 light sources can light the whole screen, I would think of it in this manner. Lets say I have 2 flashlights. I tape them together and then shine them on a book right in front of the two flashlights. There are two circles right? Now lets say I shine it on a brick wall 30 feet away. Now it is more or less 1 circle right? The same principle is what the patent is trying to achieve by using very small arc lamps, placed very close to each other with the use of mirrors. Since the arc lengths are 1mm, and the LCD is many times that size, the light sources behave more or less like one by the time they hit the LCD.

My understanding is that the collimating lens and relay lens are in place to keep the light path narrow by refocusing the light. I don't think we need this. I think we could achieve the same evenness results by having a parabolic reflector on a light, then 2 lenslets, then our rear fresnel. Basically, the lenslets are replacing the job of the precondensor lens most people have been using.

This post has been edited by Sling_Blade: 29 August 2006 - 06:40 PM