| Morien |
Hey all,
I've been having some difficulty in obtaining a panel that I want without spending heaps. (I was looking for the nView Z115 and Z215 but neither are readily available to Australia) So I am now considering getting an LCD monitor and ripping the backlight out, or getting an electritian to do it. But I noticed these replacement lcd panels (see pic) and wondered if they could be connected into a computer and used like that. Could they? If not, what else would be needed? If so, what else would be needed? ... :xeye:
Yeah, so if anyone could help, that'd be great.
Thanks |
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| uvodee |
| What is your panel type Morien? |
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| Mario007 |
| Morien that looks like a laptop display and without an expensive several hundred dollar driver board it will not work :(. |
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| Tinker |
"Morien that looks like a laptop display and without an expensive several hundred dollar driver board it will not work"
Yup....:(
Or else we all would be using them. Imagine 1280x1024 32bit color display poly STN (super twisted nematic) which gives way superior contrast as it goes beyond 90o twist like TN and gives a more absolute black as th e result. Not to mention the poly which makes it more transmisive in the pasive stage----ahhhhhhhhhh ewwwwwwww eeeeeee.:D I'm making myself drool, but anyhow its missing what tells the lcd grids to turn on or off as to twist and pass light throught the second polarizer sheet. PC screens and tft are multiplex which is run by ics to control the banks simultaniously. These avg. lcd's are TN (twisted nematic). The LC (liquid crystal) twists the light as to pass second polarizing filter. When its not twisted you get black. Variences between and 3 sub pixels (Red green blue) make up for all the colors. 0v is twisted as to pass light, like how you cn see through panel when its off....The avg. start to twist at 1v and go to 5v max before saturation of color into next pixel from what I understand. Its quite complicated and driver boards arent interchangable between dif. lcd's. This is why they are $.
Hope that helped explain why that isnt what you want. Know if it had all the driver boards you would still need to do some hacking as laptop panels connection is a ribbon. You would need to seperate all the signals and I dont think they are the same as a CRT vga mon. So that would make for some rewiring also. Its really not worth the problems. Its actually easier to get the hole mon. But the there is the $ and if you mess up $ waisted and then again most cant have the nacklight removed or its chip on glass type lcd which is like imposible to use for this. All in all not a risk I'm taking.:bawling: |
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| Morien |
awww :bawling:
Hmmm, is it possible to get an old cheap laptop, and get it to show a signal being sent in? like plug a desktop computer in and it displays what that displays?
Thanks for the replies |
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| Tinker |
| Sure you could do that. If the laptop had the power (cpu mhz) and ram enuff to run tv/dvd video. Then the desktop could serve it the data through a ethernet or seriel connection. I would recomend ethernet myself, like 100mbps. Thats what I got here between my pc's and I can serve movies to the other, dvd at that with no frame loss. Plus my main pc has a tv tuner card so the other pc can do it all too. That would be the harder route though. And I think it would cost as much $ to get a decent lappy as it would to get a used lcd mon. A 15" lcd mon. used isnt that much in comparison. Can prob. get one used for about $150 or so. New around here the 15" lcd's arent that much but it varys greatly place to place. Best of all these lcd's are getting cheaper every day. Only 1/4th of the panels produced are good enuff to be used. The rest are "recycled". CRT's even have a lower success rate thus the expense. So the good panels have to make up for all the flops by raising the cost....LCD's are getting better at manufac. and quality which passes the savings on to us. Lots of new fab methods being tried out. Sooner or later ones gonna drop the market price on these lcds significantly. |
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| moses |
| Most backlights are removable via bending some metal tabs, or are simply glued/taped on. There is no way to hook it up with a controller, being that it needs a huge amount of data. For an example, a 640x480x12 LCD would need exactly that multipled, probably 60 times per second(depending on LCD, they are usually 60). If it is a split panel, then it will need the top half of the panel and the bottom half sent at the time, which makes for a even more complex controller. A few people have successfully created CLPD/FGPA logic for contolling LCD. OpenCores.Org has a full VGA controller with Analog and LCD output for free. www.earthlcd.com has some controllers, I believe for < $250 that will work with a large majority of TFT panels. |
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| Tinker |
| For $250 you should just get another LCD mon and tear it apart. About the same cost and you KNOW the controler will work. When I was saying about backlights I dont mean normal LCD tv's and such. I ment lcd pc mon.s. Most of those are dang near impossible to get apart and if you do they are very frail. The ribbons are usually to short and some are chip on glass, where the controler chip is embeded in the glass. So you cant change the backlight on those chip on glass ones. Its a chance you take untill you find a model that works, then stick with it.;) |
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| the whiner |
I know there were many discussions about this, but I am still convinced it is possible to connect laptop’s LCD screen to desktop PC!
How?
I don’t know, but this could be the ways to do it:
1. To buy special controller to do the job (200-300$, too much).
2. To buy sage s9330 display processor or something like that (I don’t know the price, but probably still too much $’s).
3. I’m not sure, but if there are some CRT monitors that convert analog signal to digital, maybe it is possible to take such electronics (from broken monitor) and to use it as A/D converter.
4. Maybe it is possible to take digital signal from desktop’s video card, somewhere between GPU and digital/analog converter, and to lead it to LCD! I THINK IT WOULD BE THE MOST PROMISING AND CHEAPEST WAY TO DO IT!
Also, in first three ways there would be D/A and A/D conversion, and significant lost in signal, but in fourth way connection would be completely digital. |
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| the whiner |
Why should you mess with it?
1. I bought broken laptop for 50$, I sold HD, CD-ROM and adapter for 100$, and now I have LCD and 50$ :)
2. Laptop’s LCD have much better specs than projection panel (which costs >200$)
3. Laptop’s LCD have polarisers etc., and it is much easier to build lighting device for it than for projection panel. If you look at laptop’s LCD, you will see that lighting tube is placed at one side of it, and screen is lighted evenly all over its surface, without hotspots etc. So, i think it could be lighted even with fluorescent light, without need to use reflectors, fresnels, etc!
4. Even if you are not making projector with such screen, this way you can get LCD desktop monitor for free!
I don’t have such knowledge in electronics to do this myself, so help is needed here!
Also, if you have pinouts or datasheets of video cards and laptop LCD’s, feel free to share them ! |
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| Tinker |
| The polarizers in a laptop are no dif then a portable lcd tv. Prob. is they dont convert the polarity just reflect it, well the film does. Then the lcd polarizers which they all have (wouldnt work without!) absorb the wrong polarity making heat and dimmer pic. The reason a laptop is lit from side but apears evenly lit is also like lcd tv's. They use a prism film and light pipe to spread the light evenly. Does about the same as a fres. just side to front not front to back... So the polarization not only takes a polarity reflective film to work, but also relys on a sealed tight, close reflector also, as it uses the reflector to bounce the beam around untill light polarity changes. Then the film passes it. This is called light recycling.;) |
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| uvodee |
I alos found
www.guadrangleproducts.com
they seem to have a large amount of different sets to hook up panels (you know the one that were on ebay for 1 penny ( the nec nl6448ac33-18 and the sharp LQ10D32A... both look very similar anyway i bought them form some misses on Ebay some months ago.
I am gonna call quadrangle in the morning and find out how much of my arm and leg they charge for the set. |
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| remp |
Just thinking out loud about how to interface a lcd panel with no driver board to a video card. As many know there are hundreds of panels available cheap without driver boards. Good specs too.
Some video cards put out analogue only most of us I guess, but some put out analogue and digital to prepare the way for full digital between the computer and the monitor when ever that happens.
I read this somewhere but all thats required assuming you have a video board which puts out dvi then all you need to hook up to a LCD panel with no driver is a compatible "receiver board".
Assuming this is true you have a video card doing most of the heavy duty digital work, puts that out on the dvi outlet and you find a receiver that mates with the LCD panel so the video card and the LCD can communicate
Sorry if I pinching somebody here's info. Dont mean to.
Be worth checking how much for a video card with DVI included
If thats at all reasonable
Next step look into receiver boards and what panels they support
and how much they cost.
Its a round a bout way to get an LCD panel but worth investigating because ebay projection panels are starting to get very expensive. |
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| uvodee |
is DVI like a superior of inferior DVIx or is this something completely different
i have something that uses DVIx as i downloaded some months ago software to copy dvd's and the result is vcd (still very good) and one of the softwre steps was DVIx .... |
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| uvodee |
Well DVI out can be foudn on some later Radeon and ATI video cards...
is that what you think could do the trick? |
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| uvodee |
| A video card with DVI out can be bought : US$70 for the radeon 7000, $100 for the Radeon 7500 and $160 for the Radeon 8500 Pro with a stunning 275 mhz video processtime and 64 mb ddr |
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| remp |
uvodee
Thats amazing processing power. Not too expensive either.
Point is all LCD's work on digital signals.
The projection panels we buy have an analogue front end so we can hook them up to an analogue source such as video in which is analogue, or connect them to our computer which is usually analogue. Then the panel changes the analogue info into digital.
A video card with digital out can communicate directly with the digital input of a lcd that has no analogue driver board so step one sounds ok.
Now we need a "receiver card which takes the digital from the video card and makes it suitable for the LCD panel. Thats the bit we don't know about at present. The receiver card. |
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| remp |
I did a google search for lcd receiver
Many lcd's with tv receivers but two links which help along the way.
Here is a link showing an IBM LCD panel with a receiver mounted
on the back of an LCD panel. Its nothing special just a line drawing showing a box stuck on the back of an LCD. First time I have seen anything like a receiver.
www.pc.ibm.com/qtechinfo/ MIGR-4KCPEG.html?up=unknownuser
This link is asking for some transmitter/receiver boards. Maybe that person could be contacted by email for more info. Might have some transmitter/receiver boards for sale. Or perhaps help with some information.
www.eio.com/public/lcd.1998/0645.html
It is possible we need a bit more than a video card with digital out. This last link talks about a transmitter board as well as a receiver board.
Since I don't know very much at all about driving a LCD that has no driver board its a bit hard to undrstand the information but one thing is for sure, There are good panels to be had, you can buy a ready made driver board for $200 - $250. What we need is to find a cheaper way to do it. |
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| remp |
Google search lcd transmitter receiver
This showed a number of sites describing connecting to an LCD panel using a transmitter board and a receiver board and describes the better pix quality. Ie digital operation rght through
This link has a starter kit.
www.siimage.com/products/display.asp |
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| moses |
No, there is no way to hook up a controllerless LCD with a DVI port. Not without a lot of electronics. As for pinouts, I can probably get them for you, but they won't do you anygood. You will have probably 4 or 8 data bits, a frame start, a data latch pulse, and a data shift pulse. Plus your grounds, driving voltage, and occasionsally a LCD off pin. There is no way just to hook it up to a parallel, seriel, or ISA expansion slot, as it requires too much bandwidth. Specifically it requires the horizontal resolution times the verticale resolution time the color depth. Just for an example 320x200x8, QVGA. Most of your LCD's require that this data be transmitted 60 times a second. So you have, just for that little baby screen, 30Mb/s. There isn't a way of taking a "digital" signal to drive the LCD directly off of most video cards, as most video chipsets don't provide the nessacary(sp) lines to drive a LCD. If you have a older Chips and Technogoly video card, you might be able to drive a LCD off of it. However your LCD configuration data is generally stored with the video BIOS, and you would have to find a way to hack the BIOS to the point where it would work with your specific LCD.
DiVX( or rather DiVX ;-)) is a high compression lossy video codec based off of MPEG4. It isn't made to copy DVDs, it just often is used in copies because of it's extremely efficient copies. It can very easily exceed VCD quality(which is a terrible MPEG1 compression). DVI is a digital video interface, that can provide both analog and digital video, depending on which DVI interface you have. It doesn't generate LCD timing signals. |
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| Tinker |
| quote: | Originally posted by uvodee
Well DVI out can be foudn on some later Radeon and ATI video cards...
is that what you think could do the trick? |
ATI radeon 7500 (bought bro. one so I know) $75.00
ATI radeon 8500LE $95.00
ATI radeon 9700 $399.00 (newest radeon)
All can be bought at www.newegg.com CC/Cashies check/MO payment accepted....somebody have a ati radeon? All the models I listed have dvi/multi mon. suport. So you can see what is on mon. and projector at same time. Can be in two dif rooms this way! For those who dont know DVI is the lcd mon hookup on these cards which is pure digital. Reg. crt mon.s are analouge. |
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| Tinker |
| quote: | Originally posted by moses
No, there is no way to hook up a controllerless LCD with a DVI port. Not without a lot of electronics. As for pinouts, I can probably get them for you, but they won't do you anygood. You will have probably 4 or 8 data bits, a frame start, a data latch pulse, and a data shift pulse. Plus your grounds, driving voltage, and occasionsally a LCD off pin. There is no way just to hook it up to a parallel, seriel, or ISA expansion slot, as it requires too much bandwidth. Specifically it requires the horizontal resolution times the verticale resolution time the color depth. Just for an example 320x200x8, QVGA. Most of your LCD's require that this data be transmitted 60 times a second. So you have, just for that little baby screen, 30Mb/s. There isn't a way of taking a "digital" signal to drive the LCD directly off of most video cards, as most video chipsets don't provide the nessacary(sp) lines to drive a LCD. If you have a older Chips and Technogoly video card, you might be able to drive a LCD off of it. However your LCD configuration data is generally stored with the video BIOS, and you would have to find a way to hack the BIOS to the point where it would work with your specific LCD.
DiVX( or rather DiVX ;-)) is a high compression lossy video codec based off of MPEG4. It isn't made to copy DVDs, it just often is used in copies because of it's extremely efficient copies. It can very easily exceed VCD quality(which is a terrible MPEG1 compression). DVI is a digital video interface, that can provide both analog and digital video, depending on which DVI interface you have. It doesn't generate LCD timing signals. |
Makes sense! I mean there is still nothing telling the panels Liquid crystals to twist/untwist bending light thorugh polarizers. Without this no pic. Also the lcd mon.'s have controler boards so they have to have them. Nice catch there moses! |
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| remp |
Moses
Good stuff about the compression etc but in the
Google search lcd transmitter receiver
I can across several sites describing new transmit receive single chips that provide all the timing needed and can run fast enough to not need any compression at all.
Surely the digital interface starting to appear on some video cards is exactly designed for driving lcd or what is it there for.
My read of the situation is this.
Inside your computer its all mostly digital. Then the output to a monitor is changed to analogue. That D to A process causes some degradation of the video. Whether it be a CRT monitor or and LCD monitor it only accepts analogue.
That is because the huge amount of digital data cannot be sent over a 10 foot video connecting cable. I think thats the reason also for compatibility with existing monitor technology
But things are changing. The newer video cards have a special output socket so if you plug in a standard analogue monitor you get analogue but if you plug in a digital only lcd connector into the same output socket you get digital data.
This technology was mooted several years ago but stalled for various reasons. Possibly the difficulties in transmitting such high amounts of data over the monitor cable. Also CRT monitors are still readily available and cheap and good so there is no good reason to change to a more expensive LCD monitor unless you need the real estate on your desk or you want the "supposedly" better monitor performance with a good LCD and a digital connection.
No one is going to buy crap so the digital performance will have to offer good solid advantages or users will stay with what they can buy off the shelf today namely analogue monitors.
So my thinking is if the digital output on a video card is there, it must be there for a good reason and if its purpose is to drive a LCD panel how can we take advantage of that to drive LCD panels that have no driver board. But may need a receiver board of some sort.
This link from National semiconductors has a good explaination and its dated 1996.
www.national.com/news/1996/9611/dm96006ldr.html
This link explains something about dvi
www.datapro.net/dvi.html
Maybe I am on the wrong track |
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| uvodee |
one guy in my local comtputerstore Infotech , manned for 90 pct with funny Korean guys, asked me if i could leave the NEC lcd screen so he could figure it out 'after hours' .
he would not charge me for anything except when he comes up with the hardware ofcourse. however i told him that $200 would be too much!
i will check tomorrow evening and see if they found the way to connect the NEC via a Radeon or ATI.
if not so be it , i can still get a set at earthlcd. |
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| remp |
Continueing my laymans investigation into laptop lcd panels and can we use them, I have found out some things.
If you damage your laptop LCD screen you or your computer technician locates an exact replacement, removes the old lcd fits the new lcd and connects the high speed link to join the video to the lcd.
The point about this is the replacement is simple. All the electronics that need to be on the replacement lcd are already fitted.
I think this is correct. I do not know for sure because I have not replaced a laptop screen but various information on the net indicate it is true.
If this is correct then several possibilities to use laptop lcd's become a little closer.
(1) Every internet article about laptop lcd's say the row and column drivers are fitted during manufacture
(2) All laptops use a high speed transmitter/receiver combination to transfer digital information to the laptop LCD.
(3) I think the receiver is also fitted during manufacture but not 100 percent sure about that.
The laptop lcd now contains a lot of parts
At the laptop end there is always a high speed transmitter driven by the main video processor section.
One could say that all that is needed is the transmitter portion and a cable to have a working LCD but its not that easy.
There has been in the past non standard specification for laptop connection to laptop lcd so the FPD (flat panel transmitter/receiver combination may be a proprietry type specified by the laptop manufacturer.
That does not help us much
In 1999 a group of computer manufactureres got together and established a standard for driving digital LCD panels.
This is the DVI standard.
It is not mandatory but the idea is to get all manufacturers to use it so any computer can drive any digital LCD panel. And also presently available analogue LCD monitors and regular analogue CRT and also the new digital CRT's.
Different cables are used. The whole idea is to standardise the connector on the computer, to standardise the high speed link and most important for us to standardise the LCD receiver specs.
Also needed is the bios values determining important settings to drive a particular panel but the latest idea is the LCD panel stores all that information itself and it tells the computer video board how to send the information. This is to allow hot swapping of LCD monitors so hopefully bios is not involved.
So all this means if you can get your hands on a late model LCD panel it should have a DVI compliant receiver and you should be able to drive it directly from your DVI computer port.
No driver board required.
That is a simplified scenario. In real life it is very unlikely to be like that because even late model laptop LCD may claim compliance with DVI but for economy some essential parts may be missing. Secondly even if the laptop LCD is exactly compliant and it does work when connected to a DVI computer port there is no guaranteeing the PC board that contains the FPD receiver and "other stuff" can be moved out of the way to allow projection.
The essential part of this investigation is to show that a laptop LCD probably has a receiver already built in and could be made to work if "somebody" could supply a stand alone FPD transmitter. Perhaps one that is driven by a DVI computer output. This might be OK for the hot swap LCDs but of course in a laptop hot swappping is not used so we are stuck with the same old problem of driving a cheap laptop LCD without connecting directly to the motherboard. Several manufacturers do supply IC's and built up transmitter/receiver combinations. Panel link is one. Silicon image also.
It is interesting to note these LCD transmitter receiver IC's are dirt cheap. $8 -$10 dollars in quantities of a thousand but free samples are usually available.
I have to confirm if all cheap surplus laptop LCD's have a receiver built in and what standards were/are used.
Acknowledement.
The attached drawing was copied from Silicon Image website. |
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| Tinker |
| Good stuff there remp! Very interesting especially the part about it having its own row column drivers! Thats very important. This mean it is of the "chip on glass" tech I have mentioned a couple of times. The driver chip should be on the glass substrate. Wether it would interfere with our projection purposes I dont know...keep looking thats some great info so far!:D |
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| remp |
Tinker.
Thax for that. Row and column drivers seem to be always along one side and top or bottom edge and not in the way for projection. Its the rest of the electronics that could be in the way. Anyone got a surplus laptop LCD to pull apart and have a look ??
Further delving with
Google fpd transmitter receiver
and
Google fpd asic
Several articles show that prior to 1991 everyone used their own means of connecting a laptop to the LCD panel and at that time they used ECL ( emitter coupled logic ) which can run up to 1000 mhz. That speed was ok for low resolution graphics such as cga ega and hercules with not much colour.
Then came VGA panels. ECL was right on the borderline of transfering data so National semiconductors developed a new system similar to ECL but using small voltage swings about 0.3 volts and differential operation. Differential operation allowed the same current that went to the panel to come back to the computer on the negative leg and they could run the thing with twisted pairs instead of expensive co-axial wires. This was highly important since all wires to the LCD have to go through the laptop hinge. The fewer expensive wires the better.
They claimed the low voltage swings and the differential operation allowed data transfer that created next to no radiated noise, and could be used up to XGA resolution at 24 bit colour.
The National system was adopted by most other manufacturers and is still the most common by far method of connecting a laptop to a laptop LCD screen. With continual improvements it can now drive any resolution and size laptop LCD
National today according to dollar business surveys have 81 percent of laptop to LCD business so the message for us is if you buy a surplus laptop LCD chances are very high it will be designed for the National semiconductors standard.
Unfortunately the National semiconductor system is slightly different from the new DVI standard. Would'nt you know it, but there is probably a lot of politics involved.
Anyway National semiconductor equiped laptop LCD's look promising and hopefully can be identified by the chip numbers.
Am trying to find out what more is on a panel apart from the row column drivers.
You would think a surplus laptop LCD would have all the IC's already fitted so it could be plugged straight into a Laptop. Of the correct model.
If thats the case all we are looking for is a National FPD (flat panel display) transmitter and a convertor that allows the National transmitter to be plugged into a DVI port.
I am also seeing that many Video cards have digital socket or pc connection points already on the board. That could be very handy.
Also a bare PCI card can get access to the video digital lines inside a PC. Its not that simple but the possibility is there. |
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| moses |
| Graphical LCD panels will almost always have the row/column drivers on the edge, or SoG(silicon on glass) on very modern panels, other wise they would block light from the backlight. ECL logic is a very very old implementation for digital logic. All modern LCD controllers are just CMOS. I've managed to display a image on a philips QVGA mono screen via a XPLA3 CPLD, just a static image and some VHDL. Generally all LCDs have the same set of inputs: Data(1-16 bits, generally), a frame start, data shift, and data latch. If you have a passive split panel(which would be worthless for video, most likely) you would have to seperate panels more or less, requiring two seperate controllers. Your DVI-D connectors are just a high speed serial bus, they won't drive a LCD with out a chip to interface to the row/column drivers. If you wanna drive a LCD panel, just buy a controller. If you're feeling insane, then try the VGA controller off of opencores.org or find a old CHiPs and Technogoly PCI/ISA card as all of the 65xxx chips could drive LCDs, including TFTs. Afterword you would need to hack the video BIOS by finding one intended for a LCD panel, then changing the controller interface data within the video BIOS. |
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| remp |
The question I was most interested in an answer was
Is the high speed link receiver built into a laptop LCD. ?
People who would know that are people who supply replacement laptop LCD's
Here is a link to a replacement company
www.buylcds.com/REPLACEM.HTM
And here is their text I was very interested to see.
**************
Replacing the screen
Before attempting any replacement carefully compare the new screen with the screen you removed from your Laptop. Perform a close scrutiny to be sure the new screen is a clone of the old one, or the vendor has assured you that the new screen is a proper substitute for the old.
Connect the data connector, then the backlight connector and position the display in the top cover, retaining it loosely with a couple of screws.
Reconnect the power, replace the battery and turn on the computer. If everything has been done correctly, you should now have a visible display.
If the display is satisfactory, power down, remove the cord and the battery, and reverse the above procedure, making sure to replace and properly tighten all screws.
***************
There is no mention about taking parts off the original LCD. Just plug in the data connector and backlight connector.
So it seems laptop lcd's designed to replace faulty ones have the receiver built in and also the row and column drivers and the timing electronics.
But what about laptop LCD's from surplus outlets. They may not have all the electronics fitted. |
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| remp |
Google LVDS
The major supplier of the connection system between a laptop computer and its LCD screen seems to be the the National Semiconductor LVDS system.
LVDS = Low Voltage Differential Signalling
This system is in two main catagories
FPD-link = Laptop to Laptop LCD = short distance < 30cm (12 inches)
LDI = Lvds Display Interface = connection to a desktop LCD display <3 m (10 feet)
Both systems have a transmitter, a connecting cable and a receiver on the LCD.
The advantage of the LVDS system according to the National description
is only 4 twisted pairs are needed to transmit 24 bit colour and clock to a LCD panel which could otherwise need 50 or more wires.
To see if surplus laptop LCD's have a receiver built into the LCD I found out a number of companies offer LVDS test sets.
This is extracted from a test supplier document
This document is a test guide and it is recommended to be used when performing a functional test of a LVDS Transmitter-2xxxx (LVDS transmitter 2 pixel/clock) module and or LVDS cables for these modules. These LVDS modules are able to drive TFT displays 5v or 3.3v 1 pixel/clock or 2 pixels per clock up to 1280 x 1024 up to 24 bit colours.
.................The receivers are normally intergrated in the display................etc.
Several others said the same.
It seems a resonable assumption that receivers are fitted into Laptop LCD's
If you can get hold of a good laptop LCD and it has a 20 pin connector chances are very high it has a LVDS receiver built in.
If the lcd panel is cheap its worth thinking about how to drive it.
You need an LVDS transmitter (if it is an LVDS system) and you need to enter setting details in the computer bios.
Those two requirements are not very easy.
On a laptop the bios details are easy for the manufacturer because they know all about the LCD they are fitting.
We dont.
You could borrow a laptop, try and find the bios details, go out and buy an identical LCD screen find a suitable transmitter and hope it all works.
There is another way. Several manufacturers supply PCI graphics boards which include an LVDS transmitter and the lcd settings can be set on the board by dip switches independant of the main computer bios.
A quick search showed a few such graphics boards at about $250 - $300 dollars.
At that sort of price there is no advantage over a regular controller for about the same money.
Ebay projection panels are getting expensive. Good ones such as Sharp QA 2500 have been listed at $500.
The thing is actually very simple because an LVDS transmitter is only one chip. Its very cheap. It needs Cmos TTL from you regular video card. And it needs to know what LCD is connected. BIOS settings.
How can it get it. Is there a feature plug on a graphics board that outputs graphics digital Cmos TTL. ?
That would be handy because then we only need to find a simple LVDS board.
That still leaves the BIOS problem.
I have seen a computer board that plugs into your computer, takes in DVI, converts it to LVDS and outputs data to an LCD. No BIOS needed. No prices.
What I am looking for is a simple solution to a complex problem at around
$100 for a decent laptop LCD Maybe a good laptop panel is not that cheap. I have seen some at $10 dollars TFT colour and some at $300. If good ones are too expensive it's not worth finding out how to drive them.
$100 for the means to drive it. Guess.
I think half the problem is looking promising because all laptop LCD's appear to have a receiver of one standard or other built in. There are 4 competing systems. The most popular by far seems to be the National LVDS system.
The other half of the problem how to drive the laptop LCD is still a long way from being solved. But its getting slowly closer. |
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| stoko |
check out pdf files on:
www.lcdspecifications.com
my questions are:
1. can we wire some of those lcds directly on video card, somewhere between GPU and vga out, before D/A conversion?
2. can we build some CHEAP adapter, which would convert dvi signals to lcd signals such as those on pinouts?
as i understand dvi is some sort of serial connector. can those serial data be converted to parallel? |
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| remp |
stoko
Good link.
The whole problem with trying to even think about using surplus laptop LCd's because ebay is getting expensive is we have to try and figure out how they are connected to the laptop. What technology is involved and how it works and most importantly how can we identify panels that might be useful.
So far the only clue I have found is if the LCD has a 20 pin connector it's most likely using a LVDS connection system.
The LVDS system comes in two flavours
FPD-link for short links like inside a laptop
LDI for connection to a desktop mounted LCD.
The transmitter and receiver combinations are different for FPD-link and LDI link.
The max distance they say the FPD-link will go is from a laptop video card or motherboard to the hinge and then to the laptop LCD. They say 30 cm (12 inches).
Thats not a lot of use because for projection work you might have your computer several meters away from the LCD.
But I bet you could probably get away with 60cm (2 feet) specially on the lower resolution panels.
Still not really any good is it. You need at least 1 meter (3 feet) and 2 meter ( 6 feet ) would be better.
The options with laptop LCD's seem to be
(1) Find a LVDS LCD (20 pin connector)
(2) Find a video board that can fit close to the LCD that puts out LVDS
(3) Feed analogue into the board from either VGA, composite video or s-video.
Exactly similar to the controllers from Earthlink.
I have found several analogue boards around the $100 dollar mark. I have not yet investigated this in detail.
But now at least I know that no bare LCD panel takes in analogue, they are all digital.
Feeding them with digital is not easy
Digital would be best quality
Analogue is still ok for average use
Might be a lot easier to find an analogue board
Easier for cable length
Analogue or digital its still going to cost
The LCD panel
The controller
And if you buy an analogue controller from Earthlink or similar you have to specify the panel.
Another thing I have found out is specifying the panel does not seem all that difficult.
Assume the LVDS serial link is streaming red blue and green to the LCD. Starting at row one column one, for NTSC after 52 microseconds, the setup says hold the data steam because we now have a sync pulse. The data stream is halted for 12 micoseconds then resumes.
Meanwhile the row and column drivers have repositioned at row 2 column one all ready to start displaying the next line of data.
So what the BIOS function is doing is providing the sync pulse timing for NTSC or PAL or SECAM and the wait time between active display. These are very critical but its not hard to do.
I am not sure if its done at the transmitter end to halt data flow or at the LCD end under the Timing control IC but basically all it does is count clock pulses and knows when data should be displayed.
Also many video cards output one pixel per clock pulse or two pixels per clock pulse. The panel needs to know that information.
Also some video cards fill the frame buffer and wait until that is displayed before adding more info. Some video cards fill the frame buffer continously as fast as they can.
Thats another thing the panel needs to know.
So the bios tells the computer and LCD what to do and when to do it. Very similar to when you install a new printer or modem.
I will now start looking for an analogue board that can be fitted close to a LVDS laptop LCD and see how I get on. |
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| stoko |
can anybody find schematics/diagram/pinout for any laptop so we could see how the laptop is connected to LCD?
also, can anybody find schematics/diagram/pinout for any graphics processor, so we could see is it producing same or similar signals as those LCDs requires!
maybe that way we could connect LCDs directly to GPU, withot any interface!
can anybody post abut this in the main thread! those guys probably dont know about what is going on here, and we would need all the help as possible!
i would do it myself, but my english is too bad, and i couldnt explain it to them properly! |
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| stoko |
about LVDS, it would be probably hard to find LCD with it!
but there are thousands broken laptops with good screens, and you can get them for few $
and on the back of all laptop LCDs there are written the manufacturer and the model of LCD! |
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| remp |
stoko
about LVDS, it would be probably hard to find LCD with it!
I think most laptop LCD's would be LVDS. Or a similar serial system.
They have to have a simple cheap method to get the data from the laptop through the hinge to the laptop with a very small number of wires. LVDS does that
TTL would need a lot of wires and radiate a lot of noise.
From what I can gather most laptops use either LVDS or another system very similar. A LVDS panel should have a 20 pin connector. TTL panel would have a connector with a lot more pins up to 50 or so.
http://www.idparts.com/
This link that you posted has a video of a guy removing an LCD from a laptop. If you look carefully it shows what looks like a 20 pin connector to the LCD. |
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| stoko |
quote from:
http://www.techwarelabs.com/communi...?t=1313&start=0
"Hi. electrical engineer & college proffesor here.
Working on the same project. here is the deal. tou CAN use a laptop screen on a standard PC. Configuring it to work with you analog VGA card is possible, but VERY VERY impracticle. here is what I reccomend for cost efficiency and ease. I know you want to keep it cheap.
if you dont have a main board yet (or if you do and have all the parts and pieces, IE chip, memory, etc) purchase a EBC 552 pc card. everything is built in including a TFT controller. then its just an issue of making a connector and matching the pins. these cards are made for AMD, Pentium, and VIA Cyrix, so you can buy the to match the CPU and memory you already have. they go for about 100$. kind of expensive, but its the closest
to plug and play as it gets. you'll easily spend 100 in parts and pieces to make a standart VGA card work....and you might end up burning something up.
I'm curious...what kind of interface are you going to use?? mouse, keyboard?
good luck.
voodoosi@hotmail.com
let me know how it works out " |
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| zardoz |
I dont know if these are of any value to anyone...if you can see anything usefull that I'm just looking right past please let me know. I want to build a projector..not stuck on any idea or the other yet. I'm a computer tech by trade but havent done any DIY in this particullar realm. I have a possibillity of getting a beat up old CRT pj from a guy I know...pretty sure the blue is toast ... any thoughts on CRT pj's in general ( off topic I know...perhaps a new thread?)
http://www.lcdspecifications.com/
http://www.nexcom.com/product/ebc/index.htm
Zardoz |
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| zardoz |
I got an email from Nexcom today... make of it what you will.
prices, for the EBC-562, 563 and 569 as we discussed. I will follow up with our engineers in Taiwan to get any LCD screen compatibility list we may have available for these products, and get this information to you later on this week:
EBC-562 $399.00
EBC 563R $302.00
EBC 569 $339.00 All prices US bucks FOB Freemont CA plus whatever taxes.
If one of these little boards can enable a DIY'er to try a number of used laptop panels till you find the one that works best then it might be worth the expense.. or is this a great deal? and we're all going to rush out and buy one? If these are a good or great piece of kit what are thoughts on a bulk buy... cheaper by the dozen as they say...
For now tho the search goes on
Zardoz |
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| Morien |
Mmmmmm,
now we're cooking with gas. Thanks for all the replies everybody.
But just think, 1280x1024 res, 32bit colour, easily and inexpensivley replacement of broken LCDs, still will end up with a large projector, but for what a result! I know that people have previously disregarded the possibility of DIY HDTV projectors, but this is close enough.
Now I'm awaiting the compatibility list. Yay! |
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| Lifter |
Hopefully I can clear up any confusion about LCD transmission standards. 3 years ago I installed a panel in my car's sun visor. It was a 6.5" color screen I got for $30 and I spent 6 months researching this stuff.
Regular digital LCD systems supposedly can't be more that 18" of cable lenth. I have a sheilded external cable in my setup and it works up to about 7 feet (long enough to reach my trunk where the PC is). Most companies that sell flat panel cables use the centronics 50 pin connector (same as SCSI 2) on one end, and the small weird looking plug on the other (the plug that connects to the back of a bare LCD- different for different models). But some places also use this odd 44 pin external plug. That's what I'm using for my visor (I found the connecters at Fry's electronics). Earth LCD sells controllers that support both.
Now as far as LVDS (Low Voltage Differential System, I believe) goes, there is LVDS technology, and there WAS an attempt at a standard simply called "LVDS". It was used in military wearable computers, hospital equipment, etc. The LVDS standard is dead, but LVDS technology is used in all consumer level digital flat panel systems that require the monitor to be away from the computer (store bought LCD monitors, plasma TVs, etc.). LVDS technology allows a digital signal to travel much further than the 18" limit on regular FP transmission systems (10 meters I believe). LVDS tech is also used for some SCSI harddrive systems (the SCSI system called "LVD" uses the same connecter as the old LVDS flat panel standard). DVI is the current LVDS tech standard, and pretty much THE standard for flat panels now. If you buy a Matrox or ATI card w/ a digital flat panel connecter (29 pin), it's a DVI transmitter. Some of these cards don't have the connector, but they have the capability built in, so all you have to buy is a daughtercard for it. If you buy a NEC 61" plasma TV (meaning your rich), it has a DVI reciever. Another standard was made my Silicon Image, called PanelLink, but I think Silicon Image uses DVI now.
Anyways, there is no bare LCD that "uses LVDS" or anything else for that matter. You can find LCD monitors or Plasma TVs that have an LVDS reciever built into them, but no bare LCDs use it, nor any other long range system (because laptops don't need it).
Here's the deal. You have a nice LCD panel. Great. In most case you'd need a backlight inverter, but since this is for projection, you don't. You do need a custom made INTERNAL cable that plugs into the panel on one end, and has some standard plug on the other end (earth LCD and quadrangle sells these). Then you need a controller card (usually $150 and up). If the source and destination are close, you can buy a custom EXTERNAL cable from earth LCD.
But if it's more than 5 feet or so away, you need a long range transmission system (LVDS technology). You'll have to find a company that will sell you a DVI reciever that can somehow connect to your custom made INTERNAL or EXTERNAL cable. Basically, if you can get a reciever that has a Centronics 50 pin connection, then you just tell Earth LCD the pinout and they'll make the cable for you. And if you go this route, you don't necessarily have to buy a controller card or a transmitter because many standard video cards support DVI. Problem is, I don't know who sells DVI recievers in individual quantities. But it's been a while since I looked.
I'm sure many of you have researched this stuff, and there's not much new here for you, but I hope I helped somebody. |
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| Lifter |
| quote: | Originally posted by zardoz
I got an email from Nexcom today... make of it what you will.
prices, for the EBC-562, 563 and 569 as we discussed. I will follow up with our engineers in Taiwan to get any LCD screen compatibility list we may have available for these products, and get this information to you later on this week:
EBC-562 $399.00
EBC 563R $302.00
EBC 569 $339.00 All prices US bucks FOB Freemont CA plus whatever taxes.
If one of these little boards can enable a DIY'er to try a number of used laptop panels till you find the one that works best then it might be worth the expense.. or is this a great deal? and we're all going to rush out and buy one? If these are a good or great piece of kit what are thoughts on a bulk buy... cheaper by the dozen as they say...
For now tho the search goes on
Zardoz |
Hate to burst your bubble, but those are just single board computers. Tons of companies sell them. Advantech is a big one. Anyways, all it says is that it supports a DVI interface. Not a big deal. Many popular video cards have that already like Matrox and ATI. My computer I'm on right now (FIC Sabre) has one, as well as the transmitter and 29 pin connecter. And just cause it supports DVI, it still won't work on any laptop panel. You'd need a DVI reciever and a different custom made cable to connect the reciever to the LCD. And that's for ONE individual LCD. You'd have to re-configure the cable or buy a different one for each LCD you try. In fact, that Nexcom board doesn't even have a transmitter built in. It says it "allows external TMDS transmitter (DVI) for advanced panel interfaces". That probably means they sell an addon card that contains a transmitter on it. But you can already get that for regular PC's. My old Voodoo card has one. No need to spend the dough on a SBC.
Point is, don't buy one. By itself it won't enable you to try one LCD, let alone many. And even if you buy the reciever and the cables, you don't need that motherboard- you can just use a normal video card that supports DVI. |
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| Morien |
POP!
There goes my bubble... I think.
I'm not really knowledgable with this, but with that information in account, will it be possible to plug an LCD panel from a Laptop into a Desktop PC and use it as a panel for projection? What will I need specifically for this? Distance between LCD and PC isn't really an issue as I can get them as close as possible. Also, I will only really be using one LCD panel (recomendations?) and sticking with it, so it doesn't really matter about the compatibility of LCDs.
My design (been modified since my last if any of you remember seeing it) is attached, sorry for the crudeness of it.
As you can see I'm making a self-contained projector-htpc (home theatre personal computer) unit, which is even more bulky I know, but still easily mobile. The reason for it's height is so that I can just have it floor-standing at the wanted height to project the image.
Is my design doable? If the distance between LCD and PC is still too great, I can attach a side unit which will hold the PC in line with the LCD requiring only 5" of wire along with the subwoofer, reciever, etc. |
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| zardoz |
as I said... the search goes on.....
The design looks good Morien... was it you that was going to dummy it up to look like a grandfather clock?
Zardoz |
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| Morien |
nah that wasnt me.
I was also thinking of adding a second lcd to it, just a display controlled by the computer for dvd, and stuff. Also thinking of having it display the current temperatures inside the computer part and projector part. I can find out easily how to do the computer part, but not too sure about the projector part. Also trying to find if i can control the power to the light (make it go on or off) via the computer. |
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| zardoz |
The list of panels as they apply to Nexcom boards..... still unsure of what use this will be.....I will contact nexcom this coming week to ask about what other material's will be required.....(if this works as it looks like it might)
Zardoz
1. C&T-69000/69030 VGA LCD/Panel support list
TFT LCD :
Hitachi TX30D01VC1CAA
Hitachi TX31D02VC1CAA
Hitachi LMG9970ZWCC
Hitachi LMG9972ZWCC
Samsung LT121-103
Samsung LT121S1-105
Samsung LT133X1-104
Samsung LT141X2-126
Samsung LTM150XH-L01
Samsung LT150X1-151
Sharp LQ64D341
Sharp LQ10D42
Sharp LQ12S41
Sharp LM12S40
Sharp LM12S402
Sharp LM12S41
Sharp LM12S49
Sharp LM12S4P
Sharp LQ12S56A
Sharp LQ12S41
Sharp LQ14X01
Sharp LQ14X03E
Sharp LQ15X01W
Sharp LQ15X01DG11
Sharp LQ64D341
Sharp LM15X80
Sharp L214X03E
Prime View P64CV1
Prime View P64CV2
NEC NL8060BC31-01
NEC NL8060BC31-17
NEC NL8060BC31-09
NEC NL8060B26-17
NEC NL8060AC26-04
NEC NL10276AC30-04R
NEC NL6448AC33-18
NEC NL6448AC33-29
Toshiba LTM12C016
Toshiba LTM12C275A
Toshiba LTM08C343S
Toshiba LTM10C209H
Toshiba LTM12C289
Hosiden HID1506-010100
LG LM151X2
LG LB121S1-A2
LG LM151X4-A3
LG LP064V1
LG LQ150V1DG11
Matsushita EDMGRA5KAF
Fujitsu FLC31SVC6S
Optrex DMF-50714NCU-FW
Sanyo LM-GK53-22NTX
Philips HLD1506-010-130SE
LVDS LCD
NEC LCD NL6448AC33-18.
Samsung LTM150XH-L01
Samsung LTM10C306L
2. VIA VT 8606 VGA LCD/Panel support list
Toshiba LTM10C209A
Toshiba LTM12C275A
LG LB121S1-A2
UNIPAC UB104S01
Sanyo TM150XG-22L03
Samsung LTN121X1-L01
------ The End ------ |
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| fungus |
If someone had a working laptop with an USB port.
Then it would be possible to connect a TV tuner to it.
Do you guys think using this for a projection setup could work?
My main concern is luminosity. A laptop LCD is very different than a projection LCD, so I wonder if it can be done (without disassembling the laptop of course).
Please tell me someone already did this and got good results :) |
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| zardoz |
Hi folks: I found this site just now......it has a TON of info....hope you find it interesting/helpfull. Again..if you see something that looks like THE ANSWER! please pass on your findings to the rest of us.....
http://www.eio.com/datashet.htm
Zardoz |
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| stoko |
lifter!
if you have video card that has connector for external DVI transmitter, then you can hook up laptop LCD directly to it!
you just need pinout for LCD and that connector!
it gives all the signals that you need! |
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| Smoke Eater |
| Curiousity got the best of me and I took a perfectly good Toshiba laptop and dismantled it far enough to expose the lcd screen. It actually dismantled pretty quickly and easily. I then shot light (from just an inexpensive spot light) through the 12 inch lcd into a page magnifier held close to the lcd (which actually is pretty close to the same size) and focused that with my planoconvex lense......ladies and gentlemen, we have GOT to figure out how to make these laptop screens work for us! There seems to be so much potential there. My laptop screen is 800x600 res. and it made a very pretty picture on the wall. Unfortunetly, my wife came in and caught me with my laptop in pieces and made me put it all back together LOL! I know this has been mentioned before, but can't we just "gut" an older laptop and use it to power the lcd screen? What functions/parts are necessary in using an old laptop as a "portal" through which to say run a tv tuner card through to the lcd panel? If the card "overlays" the screen, do we need lots of processing power or ram? (mine is an older 380 mhz AMD with 32meg of ram so it can't take much) Do we need the keyboard and all the drives (hard and floppy) to be in working order to display things? Sigh..... |
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| stoko |
can anybody post here some diagrams/pinouts for those video cards with connector for external dvi doughter board?
i think that is the simplest and the cheapest way to do it!
and there wouldn`t be any A/D or D/A conversion, which means the best possible quality of the picture! |
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| stoko |
| same thing with doughter card! |
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| stoko |
and just doughter card!
take it off and connect LCD!!! |
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| stoko |
| is anyone willing to search the web for some PDFs with schemes/diagrams/pinouts of those wideo cards? |
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| zardoz |
Found this today....follow the links to get DVI pinout info... also panellink specs.
Zardoz |
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| zardoz |
Update...I just brought home a Radeon 8500LE SVGA,S-Video aannd DVI. Also in my travels I found a Sharp LM64C353 LCD panel. It's identified as having a Compaq spare's ID DSPLY PNL,CSTN, 10.4
This vid card is new aannd under warranty sooo.... just to find the panel pinouts... allready have the Radeon's.....hmmmm
It's all good ! till the magic smoke comes out! ~L~ |
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| Mario007 |
| Just recently bought an used IBM docking station I for my thinkpad 765xd. Got manuals and everything which was cool. But the most pertinent thing to the lcd panels is it has two VGA connectors. One is standard laptop video out to external monitor another is a 15 connector that the manual says is for inputting external computer input. It is designed to have one pin missing. If anyone could find a pinout of this cable I would test it and report back. |
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| Lifter |
| quote: | Originally posted by stoko
lifter!
if you have video card that has connector for external DVI transmitter, then you can hook up laptop LCD directly to it!
you just need pinout for LCD and that connector!
it gives all the signals that you need! |
Not true. You can't just connect a DVI cable to a panel. It's like hooking up Firewire to a USB port. It won't work. Completely different signals. I'm sure some of the signals like V-sync are the same, but that's it. There's also auxilury signals to consider, like on/off, brightness and contrast controls, etc.
Think of it this way. Think of the flat panel cable/connecter inside a laptop as CAT-5 cable for networking. Now think of DVI as your phone line w/ DSL. You can't just splice some wires and hook up the network cable from your PC's nic card directly to the phone jack. You need the DSL modem. Think of a DVI reciever as the DSL modem. Make sense?
I haven't worked with this stuff in 3 years, so I guess it's possible that some newer laptops have DVI systems in them. But I highly doubt it. There is absolutely no reason for it and it would be a complete waste of money. Why have DVI in a laptop when the panel's connecter is inches away from the motherboard? The whole purpose of DVI is for long distance transmissions (like a desktop monitor). If laptop panels all used DVI, they'd all be interchangable- and that's obviously not the case. The daughtercard of the video card you posted is the DVI transmitter. You need a DVI reciever on the panel's end. I really wish it was possible to easily hook up a laptop LCD to a PC w/o extra hardware. Unfortunatly it isn't. The cheapest route to go, if you can find one, is to buy a digital to analog VGA converter for the specific panel. Lots of places make them for many different models. |
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| Lifter |
| quote: | Originally posted by fungus
If someone had a working laptop with an USB port.
Then it would be possible to connect a TV tuner to it.
Do you guys think using this for a projection setup could work?
My main concern is luminosity. A laptop LCD is very different than a projection LCD, so I wonder if it can be done (without disassembling the laptop of course).
Please tell me someone already did this and got good results :) |
Are you sure there are USB TV tuners? USB is 12mbit, and that's not nearly enough bandwith for video. Maybe USB 2.0. |
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| Smoke Eater |
| The local Office Depot's new advertisement has a MicroTek 15" lcd monitor with a resolution of 1024x768 XGA for sale for $279.99 (including rebates). My thought is, are lcd monitors coming down in price to where us trying to "piece" together receiver cards/lcd screens/etc.... isn't going to be worth the trouble? If they come down a little more, maybe it will just be better to buy the monitor and dismantle it to expose the lcd screen instead? I wonder what our "breakeven point" should be? If we can build one for less than say $150? Or if it takes us $200 to put one together, would it be worth a little extra to get the monitor? Just some questions on my mind..... |
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| moltenrock |
Hey Guys,
I was just wondering if anyone could help me out? I just recently acquired this panel from someone and it's just the bare panel with no backlight (pic). There is a long 30-pin ribbon cable coming off the side of the board connected to the panel, but I have no idea what I am supposed to connect this cable to. I even know all the pin-outs for the cable, but I still have no idea what I need to do to it so that I can enable it to play video. If anyone would be kind enough to help me out, I would greatly appreciate it!
Thanks! |
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| iilsley |
Is this panel worth looking @
http://www.overstock.com/cgi-bin/d2...E&PROD_ID=48219
TM5800 5.8-inch Active Matrix LCD Monitor
Perfect for any portable display application, the TM5800 LCD monitor offers a high-resolution, full-color display. Use it with a portable DVD or VCD player for entertainment in your car. It's great for GPS applications. Save a bundle on this display today! |
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| Lifter |
SmokeEater - Personally I don't think it's worth it at this point. You could find a good deal and only have to spend $200 or so on the panel and all the parts to make it work. But why bother when prices are getting as low as $280? Making a bare LCD work on a PC is a serious pain in the *** and not worth $80. Just my opinion.
moltenrock - read my posts. All LCD models have different connecters with different pinouts. That 30 pin ribbon is useless because it was made for the motherboard of whatever laptop it came out of- and nothing else. Find where the ribbon connects to. Then you'll have to find a controller card and a custom cable that is made for that panel, or an board that converts it to analog VGA.
iisley - What makes you think that panel is high resolution? It's a video LCD that only has a composite input, so the highest resolution it'd be is 640x480, and I highly doubt it's even that high considering the fact that it's so small and meant for TV viewing. It's not a horrible deal for what it is, but I'm sure it's worthless for a projector. |
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| Lifter |
| quote: | Originally posted by remp
stoko
Good link.
The whole problem with trying to even think about using surplus laptop LCd's because ebay is getting expensive is we have to try and figure out how they are connected to the laptop. What technology is involved and how it works and most importantly how can we identify panels that might be useful.
So far the only clue I have found is if the LCD has a 20 pin connector it's most likely using a LVDS connection system.
The LVDS system comes in two flavours
FPD-link for short links like inside a laptop
LDI for connection to a desktop mounted LCD.
The transmitter and receiver combinations are different for FPD-link and LDI link.
The max distance they say the FPD-link will go is from a laptop video card or motherboard to the hinge and then to the laptop LCD. They say 30 cm (12 inches).
Thats not a lot of use because for projection work you might have your computer several meters away from the LCD.
But I bet you could probably get away with 60cm (2 feet) specially on the lower resolution panels.
Still not really any good is it. You need at least 1 meter (3 feet) and 2 meter ( 6 feet ) would be better.
The options with laptop LCD's seem to be
(1) Find a LVDS LCD (20 pin connector)
(2) Find a video board that can fit close to the LCD that puts out LVDS
(3) Feed analogue into the board from either VGA, composite video or s-video.
Exactly similar to the controllers from Earthlink.
I have found several analogue boards around the $100 dollar mark. I have not yet investigated this in detail.
But now at least I know that no bare LCD panel takes in analogue, they are all digital.
Feeding them with digital is not easy
Digital would be best quality
Analogue is still ok for average use
Might be a lot easier to find an analogue board
Easier for cable length
Analogue or digital its still going to cost
The LCD panel
The controller
And if you buy an analogue controller from Earthlink or similar you have to specify the panel.
Another thing I have found out is specifying the panel does not seem all that difficult.
Assume the LVDS serial link is streaming red blue and green to the LCD. Starting at row one column one, for NTSC after 52 microseconds, the setup says hold the data steam because we now have a sync pulse. The data stream is halted for 12 micoseconds then resumes.
Meanwhile the row and column drivers have repositioned at row 2 column one all ready to start displaying the next line of data.
So what the BIOS function is doing is providing the sync pulse timing for NTSC or PAL or SECAM and the wait time between active display. These are very critical but its not hard to do.
I am not sure if its done at the transmitter end to halt data flow or at the LCD end under the Timing control IC but basically all it does is count clock pulses and knows when data should be displayed.
Also many video cards output one pixel per clock pulse or two pixels per clock pulse. The panel needs to know that information.
Also some video cards fill the frame buffer and wait until that is displayed before adding more info. Some video cards fill the frame buffer continously as fast as they can.
Thats another thing the panel needs to know.
So the bios tells the computer and LCD what to do and when to do it. Very similar to when you install a new printer or modem.
I will now start looking for an analogue board that can be fitted close to a LVDS laptop LCD and see how I get on. |
Sorry I didn't read your posts before. Sounds like your doing the same exact research I did 3 years ago when I put an LCD screen in my car. Anyways remp, connecting a laptop display to a PC is not that difficult or expensive if you can find these 2 things: An analog controller, and a cable to connect that controller to the panel in question. Then all you need is VGA. I don't know why some many people here think using a laptop panel is a bad idea. As we've both stated, standard flat panel link is not supposed to work for more that a foot (although I got mine to work 8 feet away w/ a shielded cable). Don't worry about LVDS, Panellink, or DVI. I know DVI is tempting because major brand name graphics cards support it, but it's too much money and nobody will sell you a reciever board for it unless you order in bulk. And finding or making a custom cable to connect the reciever to the panel is also going to be extremely difficult. It is possible, but kind of pointless. You don't lose any noticable quality by coverting it to analog VGA. If your source is less than 8 feet away, get a shielded FPD cable from earthlcd.com like I did w/ my car. If you need to go further, just go the analog VGA route.
The real question is this. Can the back of a laptop LCD easily be removed to make it transparent? And if so, what kind of cooling is needed if it's sitting on top of an overhead projector? |
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| Smoke Eater |
Lifter: I've taken apart my toshiba laptop to expose the lcd screen (much to my spouse's dismay) and it actually came apart quite effortlessly. I probably had it apart and suitable for a projector application in less than 10 minutes (working carefully so as not to destroy a perfectly good laptop). I know its only one model and design, but I would imagine there can't be too many different designs of lcds for laptops? I could see one possible problem with using monitors instead of laptop lcds, though. Laptop's are made to be very "thin" through the lid/screen area so that the lid is not very bulky and heavy. They seemed to allow extra length ribbon connectors on mine to move the circuit boards to a more favorable place. The monitors that I have looked at seem to be thicker and I wonder if the parts are "stacked" a little more than the laptops resulting in shorter ribbons which would make it more difficult to move whatever boards there are out of the way. Has anyone out there dismantled one of the larger monitors?
I'm also interested in the analogue board route. Can a board like that be had for less than $100 or so? Is there a brand name to look for? (EDIT: Saw your other post about the kit) |
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| zardoz |
I have further identified my Sharp LM64C353, it is actually a Kyocera part number KCS6448JSTT X6. It has 31 pins on the connector, the backlight and related gear came off easily. The pinout diagram for the LCD shows 7 pins are ground...leaving 24 pins ... the same number of pins on a DVI-D video card connector. The screen has one pin as "no connect" so does the card. The trouble is the card pinout has terms like pin 9 TMDS data 1- .....the LCD doesnt :( Am I closer? or still just spinning wheels.....if so at least the LCD was cheap as dirt ~LOL~
Any pinout wizzards out there?
Zardoz |
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| Lifter |
| quote: | Originally posted by zardoz
I have further identified my Sharp LM64C353, it is actually a Kyocera part number KCS6448JSTT X6. It has 31 pins on the connector, the backlight and related gear came off easily. The pinout diagram for the LCD shows 7 pins are ground...leaving 24 pins ... the same number of pins on a DVI-D video card connector. The screen has one pin as "no connect" so does the card. The trouble is the card pinout has terms like pin 9 TMDS data 1- .....the LCD doesnt :( Am I closer? or still just spinning wheels.....if so at least the LCD was cheap as dirt ~LOL~
Any pinout wizzards out there?
Zardoz |
Arrrggghhh. I said this like three times already. Why don't you read some of my posts. Your panel, as is, will not plug into a DVI video card and work. End of story. No ifs ands or buts. Wonder why pinout signals are called different things on the DVI card and the LCD? Because they are different. TMDS are LVDS encoded digital signals for long distance applications. That's what DVI is fore. Panellink and LDI do the same thing as DVI, just different formats. DVI is the current accepted standard. But your LCD does not have a DVI reciever on it. Why? because your laptop's motherboard is only inches away from it. Your panel will only accept non-encoded digital video signals (r1,r2,b1,b2,g1,g2, v-sync, etc.). That's a wonderful coincidence that it has the same amount of pins, but my my keyboard connecter has the same amount of pins as an S-Video connecter. Doesn't mean I can use it to hook up a DVD player. Come to think of it, DVI connecters use 29 pins, not 24.
Now all this doesn't mean your panel is worthless, or that you can't get it to work with a PC. You just have to buy some extra hardware for it to work. You need one of three things:
1) A digital flat panel controller card. This is basically the same thing that's on your laptop motherboard, but in the form of a PCI card. They cost anywhere from $100-$300. These are not the same thing that's on ATI cards. No video cards that can be bought in a computer store will do what these things do. They are not meant to work for more than 18 inches away from the panel or so. I've gotten one to work 8 feet away using a shielded cable that I got from Earth LCD 3 years ago. Something to think about.
2) An analog flat panel controller board. This converts the flat panel signals into analog vga signals. This allows you to hook up the panel to any 15 pin VGA card. They too are in the $100-$300 range. This is the route I would go.
3) Buy a DVI reciever board and connect it to your panel. This will give you long distance w/o any signal degradation you'd get if you went route #2. However, if you have a TV tuner card, or a DVD decoder card that requires a VGA loop through, you're screwed. Also, I don't know where you can buy just one.
Now whichever of the 3 routes you choose, you still need an internal ribbon cable to connect the controller/board to the panel. This cable will have to be cutom made to match the pinouts from the controller/board to your specific panel. The one that came with the laptop will NOT work. Many times the seller of the controller/board will give you the cable you need if you give them the pinouts of you panel. Sometimes, they'll have a list of "supported panels", and if your is one of them, you just tell them that and they'll have a cable already made for it. Many of these companies do not sell individual units to end users. They don't list their prices either, and you have to fill out a form for a quote. They're trying to land contracts from companies who make desktop LCD monitors. Earth LCD is the only place I know of that is completely made for end users. They'll make any cable you want for any panel they can get the pinout for. They sell digital and analog controllers, but they do not, however, sell DVI reciever boards as of yet. |
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| stoko |
if anyone is still interested in this, read this pdf:
http://www.conexant.com/servlets/Do....pdf?FileId=325
it is datasheet about conexant bt868 tv encoder!
that chip takes the same signal from the board as the signal that is needed for LCD (3x6 or 3x8 bits of RGB etc.)!
so, i think that you could hook up LCD to any video card that has such or similar chip! |
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| zardoz |
Lifter...thanks so much for clearing up my obvious error in assuming that I may at some point in time or another stumble across a reasonable sollution to this project. And by all means thank you for stopping me from plugging my keyboard into my S video port. WHEW! that was a close one
I would like to point out that DVI-D has indeed 24 pins (even if it wont work) http://www.ati.com/support/connecto...tsfordvi-d.html
You are correct though DVI-I has 29 pins http://www.ati.com/support/connecto...tsfordvi-i.html
I do however thank you for your explanation of the sollutions you have found, once I waded through the sarcasm I did in fact learn a thing or two.
It seems that the multitude of hours I have available havent yet educated me sufficiently to the task at hand. So that being said I think I'll abandon the laptop screen idea (for now) as I am a technician... not an electronic's engineer.
.....do we have any people here with a degree in electronics?
Zardoz |
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| jvisaria |
| you will in about six months |
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| zardoz |
I agree remp! I think if we can get a lap top panel to work we will be able to do this project with some style. As I said I'm just a retired army mechanic turned computer tech....if you can give me a reasonable idea of what to look for I have nothing better to do with my time than to look.
have I posted this one yet? http://www.unigraf.fi/PAGES/testeq/viatmds.htm
Again to all concerned...if I post a dead end or one that has been explored and defeated just ignore it......ya never know I might just stumble on the answer for you. And if I do (find an answer) please let us all know.. cuz I might not recognize it ;)
Zardoz |
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| Smoke Eater |
| Thanks for going to all this trouble and effort, it is appreciated by those of us that can't or don't have the knowledge in the field. Nothing is really impossible...it may be impractical, or it may not be practical YET, but just think of all we can learn on the journey. I'm not much help with this part of things...but if you need something taken apart just let me know :D Thanks for sharing. |
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| remp |
Thanks for the thumbs up guys. The way I look at it, it certainly is a bit of a difficult problem but the laptop can communicate with its LCD so if we figure out how that happens we might be succesful.
I keep remembering what Stoko said and I hope he is right that you can get not bad LCD screens from broken laptops for a few dollars.
I should tell you guys I am no expert on this. Just another DIY person but I sure am interested if we can get a MUCH better LCD for not a lot of money
Smoke eater.
You took apart your laptop LCD didn't you. Could you do it again and see what sort of cable you got from the motherboard up to the LCD.
If it has an LVDS connector it should be a 20 pin. No other wires to the LCD apart from maybe a couple of wires for the backlight and maybe for power but its the 20 pin connector I am interested in.
Zardoz
You posted the link I was looking for about the Advantech PCM-3540r/t LVDS transmitter receiver. Good on you.
Anyone have access to several broken Laptops. Doesnt matter even if the screen is broken.
Zardoz maybe you could go around all the service depts in your area. See if you can pick up any broken laptops.
We need to be convinced the LVDS system is a goer. Since I do not have access to any in my area you might. Stoko gave a link to a video that shows how to take an LCD panel out of a laptop. I mentioned about it in my last or second last post. Have a look, shows you how to do it.
If you do get any, pull them apart and check the cable from motherboard to LCD. Should be a 20 pin connector.
I have not looked at your link yet but will do soon.
What I think is a reasonable way of investigation is to first read all I can about how laptops talk to the LCD. Done that and it seems the LVDS system is a very commonly used system. Next step is to see if that is true by sampling a few broken laptop LCD and see if they have the LVDS 20 pin connection.
If that turns out to be true, we have some good info on how the laptop communicates with the LCD. If we do actually get an LVDS lcd, and a transmitter from Advantech there is still the unsolved problem of connecting the transmitter to a PC video card and how to handle the BIOS.
So we are waiting now for confirmation that a good number of laptops use a 20 pin connector to connect to the laptop lcd. |
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| remp |
Originally posted by Zardoz
have I posted this one yet? http://www.unigraf.fi/PAGES/testeq/viatmds.htm
Dont think so.
It is a link to various test equipment for testing LCD panels in service shops/manufacture and research. Other video test gear available as well.
One of the features is it/they comes with a disk with various common LCD timing parameters supplied and one can edit and save these for non standard LCD's. Pretty useful. I think this test gear would not be cheap. If one was on Ebay for $5 snap it up. |
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| remp |
Could somebody who understands Russian please have a look at this link.
It shows a picture of a video card with some words in English. It seems to have the usual CRT monitor output and also a LVDS output. Maybe a list of outputs and if they mention a price in US dollars would be good. Looks like a PCI card. Thanks
www.icn.ru/i/a.nsf/nm/20-0/$FILE/icos_v20.pdf |
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| remp |
Google lvds lcd shows a number of interesting links.
This one
http://www.mite.cz/etxlvds-en/etxlvds-en.html
Shows a picture of a small computer board with an LVDS driver built in driving an LCD panel.
Note the connecting cable with a small number of wires.
This type of system from this company or similar is interesting. If it is cheap enough worth looking at because they may have bios settings for a number of different panels.
I cannot imagine one can get a small size computer board with a good quality video card at a low price. It may be possible but I dont know at present so I have been thinking someone must have a box that takes VGA from a pc and puts out LVDS for not too much money. The box should have the ability to configure for different panels. Using VGA from a PC is a backward step away from full digital but as an interum solution it is good enough.
The link is almost what we want but not quite. |
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| Smoke Eater |
| Remp, I still have mine apart, but just started a 24 hour shift at the fire station, I'll get home in the morning and get you the info about the ribbon. There is just one flat ribbon cable to the screen (not including the backlight connections), but I can't tell you for sure about the pin count until tomorrow. If need be, I'll take a photo of it and post it. |
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| TriggerHappy |
Hey guys,
I've been reading this thread w/ great interest as this is exactly the kind of setup i want to run in my car...
But from what i see it can be a really complicated process because of the required controllers for the lcd panels...
I did however come by this link
Mp3Car
The third item down is a 6.4" lcd display that takes composite input...
My question regarding that is look at the adapter that is used to convert from composite to direct lcd input, its tiny...Now i know that just because its tiny dont mean it aint expensive, but perhaps that's all we need? |
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| uvodee |
youo are right but......... the screen you are looking at is a 5.6 or 7" screen it is not the same as a 10.x screen
then you need some 'larger' conversionboard
jest my 2 cents
however , i think there is an easy solution out there that suits us fine i just haven't found it yet! |
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| remp |
TriggerHappy
Thanks for the link Mp3car. That 3rd item down the board shown is not the bit that converts analogue to the panel, its the control panel with the knobs for brightness tint analogue input.
Sorry thats not what we are looking for but the item should be good for your application.
Zardoz
That link you posted looks interesting. Complete video card with LVDS output and lcd size/type support right on the board.
http://www.spectrah.com/LD-S270.htm
Smoke Eater
Forgot to mention when handling your lcd panel good idea to be very careful to keep fingers away from delicate electronic parts because its most likely Cmos and damaged by static electricity. See if you can ground yourself like they do in service shops.
TriggerHappy makes a good point about controllers being complicated. We are trying to use laptop lcd's that might be avaliable at cheap prices. No one else has figured out how to use surplus laptop lcd's so they have low resale value. Thats good for us. Its only half the story though. Even if we find a way to drive a laptop lcd it is not much use if there are electronics in the way for projection. |
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| remp |
Zardoz
Your Sharp LM64C353 is a 10.4 inch LCD originally for Compaq laptop. It is a DSTN x 2 panel which means its no use for full motion video. Thats probably why it was dirt cheap. The 31 pin connector uses TMDS signalling which is similar to LVDS but different. Sorry. Good info though because now we know a 31 pin connector is most likely TMDS. |
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| zardoz |
Yes once I found the kyocera part number it was easy to track it to an old compaq laptop....end of a short but intense hope ~L~
On to bigger and better things! I have been to ALL of the service shops that I could find in town plus all of my supplier's (as I said I'm a A+ tech...but this field is past my realm of expertise) tech rooms...and from what I've seen all the laptop screens have had a single ribbon connector.
Now I hadnt at that point in my quest for a projector resorted to counting pins....I will be now... but my point is all of the "worthy" screens I have seen have had a single ribbon connector with what looks like it should be 20 pins...they've all been kinda scary thin ya know what I mean? On the other hand every LCD monitor I have seen has used TWO ribbon connectors....the monitors that I have seen apart looked tough to seperate the electronics from the screen. The laptop panels that I have seen off didnt look too bad.. that is to say the backlight gear comes off easily...but at least one had a "sub card" that was attached with an even smaller and short and scarier ribbon (back to the backside of the LCD itself). Most however looked to have unemcumbered view of the entire LCD front or back.
The prices I found locally for screens was decent I think if I knew for a fact I could drive them.. the most expensive I found was off a Dell laptop....model unknown.....15 inchs of gorgeous! $150.00 canadian if I knew I could drive it I'd have it now...
My plan is to buy one of these spectra cards if they are less than $300.00 canadian(and they will push the screen I want) then put together a microATX machine...one of the cheap and dirty VIA/Cyrix all in one boards....mount the stuff in either a projector box and a micro ATX box (but this brings on data/transmit distance issues as I understand it) or a projector with the computer built into it. OK the projector with it's own dedicated computer with DVD drive and associated crap built in it is! Well that was a simple problem at least. ~LOL~
Via board complete with 800 mhz processor $120.00
stick of ram 256 meg flavour $47.00
16X DVD drive $72.00
TV tuner card $65
20 gig HD $100.00
that sweetheart of a screen I saw for $150.00
power supply $35.00
keyboard and mouse $18.00
Spectra card...assuming it works....$$$...????
frezzies and projection lenses? (didnt care to look till I knew I could do it in style)
Getting more expensive......are we passing the point of vanishing returns?
Zardoz |
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| remp |
Zardoz
I think a lot will hinge on the price of the video card with LVDS output that you posted. Lot of the things you have on your list you need anyway.
Start counting pins if you can. LVDS should be 20 pin hirose connector. Whats that panel you like got. 15 inch is getting a bit large to put on an OHP unless you have other lighting plans.
There is an interesting new thread here about a guy (maddog) who stripped his laptop and put the lcd on an OHP. He says its much better than what he had before. He has a problem with needing a longer flex cable. Maybe someone can help him out. |
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| zardoz |
The Dell panel I fell for was a cable about 8 inchs long, and it did not look to have had more than 20 pins....of course it did have the CCFL wires on it, as for it's size I dont mind...I have hopes of putting together a dedicated projector with a metal halide lighting system
(that is to say scrapping the OHP alltogether)...after all if it can be put in one package......full multimedia....DVD... USB ports...lan connections...modem...crt...5.1 surround... just connect a set of surround speakers....wireless keyboard and mouse(extra$100.00) plug in your modem or high speed net connection... aim at the appropriate surface and distance...
I can see watching movies without having to do all this line doubler stuff, power DVD works great, I can see classroom potential...boardroom...of course video games...hehe....kick *** lan party stuff...video dances ...karaoke(if thats your thing..)
BTW I'm building a 24 foot geodisic dome....thats where this is going to live ;)
Zardoz |
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| remp |
Zardos
I am interested in your geodisic dome. Could you email me please.
Thanx. |
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| Smoke Eater |
| Got home this morning to look at the laptop, found out it has a 41(?) pin connector. (I hope that's right, it was early in the morning after a 24 hour shift and those little things are hard to count!) Thought this was strange as you were expecting 20 pins. Found my laptop manual and found out the screen is DSTN and not TFT. That is probably the difference, don't you think? I can attach a photo of it later if you need one. |
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| remp |
Smoke Eater
Thanks for that. Yes that the difference. DSTN LCD'S are a lot slower than TFT and often had the screen driven in two halves because they could not get the speed with one frame at a time. If you see DSTN x 2 thats what it means. Thanks for the info. |
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