LCD panels

[yander26]

Originally posted by DragonzTeeth
Hello yander26,

If you dont mind, could you tell us what the measurement of the OHP stage is or the measurement of the LCD active area.

I'm not having any issues here by going out and getting a KOGi monitor from CompUSA here locally and then getting an OHP.

I'd like to be able to utilze the HTPC and some gaming with a Radeon 8500 attached to it so I'd like to go with the LCD monitor idea if its working for you.

How many lumens is it putting out? If you dont mind me asking...read all the threads but maybe missed your info.

thanks,

DragonzTeeth

I am at work, so I don't know the exact dimensions, I know they are around 12" square for the projector area, the LCD was a little over 11" H and 8 or 9" V I will measure them tonight and post them for you. As for the brightness I don't have a way of measuring this, it is much brighter than I was expecting, viewable with my room lights on, although a bit washed out. I really wasn't expecting much from this setup as my overhead is an old 3M projector with a halogen bulb. My real plan is to remove some of the optics from this projector and build it into my own box with my own bulb. I bought my monitor from Best Buy as opposed to CompUSA because CompUSA charges a 15% restocking fee as soon as you open the box, with Best Buy I figured if I couldn't use it, I could put it together again and return it.

Now that I have had time to experiment with this setup a bit and project it on a proper screen, I have run into an optical problem. I am finding that the top of the image is much darker than the bottom. I would think optically top and bottom should be the same, but I guess not. I am sure it has nothing to do with the extended area of the overhead as the image only extends in the horizontal which looks fine. My guess is it has to do with the mirrors and polarization path length differences, but I am not sure yet. I did find an adjustment for the centering of the light but it made no difference. The overhead looks uniform with out the LCD on it, and the LCD looks uniform when I look at it sitting on the overhead. I will experiment with it more tonight, if anyone has experienced this problem before, any input would be appreciated.

[DragonzTeeth]

Hey yander26,

thanks alot for the feedback... I understand about the Best Buy purchase. Ours around here do not have the
14in anymore at any of the stores but CompUSA still does.

Sorry , can't help you with the optics part of it, wish I could right now. Probably won't be able to get
OHP and LCD til after Xmas , you know how that holiday shopping gets in the way...

Thanks again for the feedback, appreciate it.

Dragonzteeth

[remp]

Dragonzteeth


Sorry everyone for this. If you feel the links I put up are not
productive to this forum or thread let me know and I will not intrude anymore.

They are productive and very important. We are little fellows playing in a very big field. Others have teams of highly paid engineers with PHD and big biudgets and software tools to make designs possible. All we have is our determination and our ingenuity to make a small hole in the system and try and burrow in. We have to be patient and observant and clever as we can be.

We have a small platform now. You and the other guys have found good things that work. Thats why I tried to bring it together on one page as a recap. I do find it difficult to keep reading and rereading the posts and keep them in mind so I did try to colate them so we could see how we are doing, and more importantly others reading this can see we have made some good progress. and hopefully join us Any solutions or part solution not on the recap list please let me know. We need every scrap of info. We have to look at a hundred possibilities to find one that is on the money.

I have sent an email to Morein telling him about progress. It's his thread and we have to respect that.

Something you might find useful.
Every Taiwanese/Chinese/Japanese/Korean supplier I have ever emailed always come back with polite useful information. Makes sense. They are interested in business. One off, 10 off, or a thousand they want the business. I usually get a perfect English reply within 2 working days and a comprehensive product .PDF document attached.

[remp]

Yandrr26

Now that I have had time to experiment with this setup a bit and project it on a proper screen, I have run into an optical problem. I am finding that the top of the image is much darker than the bottom. I would think optically top and bottom should be the same, but I guess not

If you turn the panel right around so the bottom is at the top will prove if its the panel or the optics.

If it is the optics we can think about what might be wrong if you like. I have a 10 inch projection panel on a OHP and no problems with overall brightness. With no panel on the OHP the light on the wall is also good same overall. Overall focus is good. Only thing I have is a very very small hot spot in the center which is not noticable, only if I look really critically.

The only thing I can think of right now is some of the light from the panel is falling outside the projection lens collection area and ending up on the ceiling.

[Connor]

Been following this thread for a few days now and Lemming and I have been discussing the use of the Epia M motherboard for the driving of our Flatscreens, over on www.sudhian.com.

As for the monitors mentioned on Monday, I happen to have 22 of these in my office atm. Not badged as unisys but Keycorp (an australian company) model K57h.

The LCD panels are Samsung Ones, and their Spec is on www.LCDSpecifications.com Model No LTM121SI-T01 the unisys claim to
be a smaller Screen size but the case design etc are all the same as ours.

the interface cable between the card and the Panel is LVDS, you can tell this by looking at the card. At the External connector are two National Semiconductors chips very small, running the part number through the search engine at www.national.com shows these to be LVDS line drivers.

I would really like to know if anyone else has got these working with any other LVDS output drivers, what results they had and what the pinout for those drivers was.

If anyone is interested in using the Epia-M motheboard to drive their LCD project the current news is that VIA are currently designing the LVDS module
to connect to their TTL output port. noone knows at this time what the specification of that output device will be. At the moment pricing looks set to be around 150Gbp and the very earliest models are shipping without the TTL port fitted, as of Today-ish. The Epia M runs on an embedded C3 processor which doesn't have a great FPU so Games'll suck a bit. But with Savage Twister Graphics and built in DVD decoding it should be an amazing home cinema/presentation machine. Which is why a lot of us are interested in building our own projectors.

[remp]

Yander26

I am sure the whole groups resources are at your disposal to help solve the light problem.

With prices coming down for late model LCD monitors this is an important panel solution offering much better performance than Ebay 10 - 15 year old projection panels. Better resolution, better clarity, better contrast, computer drive built in. And you can see it in operation before modifying for projection use.


--------------------------------------------------------------------------------
Originally posted by Smoke Eater
Is the main difference between the LDS270M and the ARV462 the fact that one is a PCI card and the other is "self-contained" and doesn't need to be operated with a computer? Are both capable of driving the high-end panels? Whoops, I see that the ARV is capable of UXGA while the LDS only mentions up to SXVA. Still, they both seem impressive.....especially when compared to my VGA panel I'm using now. I see Zardoz heading down the LDS path with Remp leaning towards the ARV route, any thoughts from you fellows as to why one route over the other? Or is it just a matter of preference (or resolution)?

Sorry for delay in reply.
Yes thats the main difference. The LDS270M is a PCI video card while the ARV-462 and ARV-468 are self contained units. that can receive analogue or digital input from a computer, and S-video and composite video and drive a good range of panels.

The ARV-468 is a state of the art self contained unit that would solve all problems but at $256 USD plus freight from Taiwan it is just too expensive except for those who want and can afford the best.

Zardoz had another application in mind which he explained so he chose the LDS270M video card.

I should also mention that with either the LDS270M video card or the ARV-468 self contained unit you still have to use a compatible panel not just any panel. It has to be a panel that accepts the LVDS signals or the TTL signals and one the controllers can connect to. The manufacturer gives a list of compatible panels.

Since I am still dedicated to finding the best deal for affordable money, it will be interesting to see if Zardoz's video card can drive a cheap laptop LCD.

[remp]

Connor

Can you tell us how many pins on the LVDS connector. Is it 20. ?

[Connor]

I counted them as being around 40,
the wiring on the Graphics card shows
about 20 pins being used, some of these
appear to be voltage lines for driving the
backlight.

The connector itself is a D shape commonly
used for SCSII signalling (if fact I think LVDS is
used a lot more for signalling as scsii standard
rather than as the LCD standard it was concieved as )

As for the TTL outptut on the Epia board, it is a 40 pin
Hirose output. It matches the Hirose used inside my
laptop, but I can't confirm yet what signalling the laptop
screen uses. (It's a Sharp LM64C389 not on www.lcdspecifications.com)

[yander26]

Originally posted by DragonzTeeth
Hello yander26,

If you dont mind, could you tell us what the measurement of the OHP stage is or the measurement of the LCD active area.

Ok, here are the real dimensions, the overhead area is 11 1/2" X 11 1/2" The active area of the LCD panel is 11 3/8" X 8 1/2" a very tight fit, but it works. Thanks for the sugestions on the light remp, that was one of the things I was going to try. I solved the problem though, it was just that the fresnel lense wasn't sitting correct, since I didn't glue it after I cut the plastic. I put the fresnel lense on top of the glass to test this, and it worked fine. The picture looks good now, so I think I will build this into a box as I planed.

[yander26]

It seems I was wrong about solving my optical problem, the problem of the screen being dark on the top does lie in the panel. I thought I had solved this, because I had a image that was very light colored, and the effect doesn't show up then. I fliped the LCD around, and to my dismay it was the bottom that was dark. You can only see the effect when you have a uniform dark colored image, such as a blue windows desktop that I had. For some reason the panel is dark on the top, not sure why they did this, as the origional light came from the bottom. The effect isn't that bad if you adjust the brightness and contrast, but is still noticable on a dark screen if your looking for it. Not sure how to fix this, other than adjust your light source to give more light to the top. I am hopeing it won't be noticable with movies.