nima - 07 May 2008 02:08 PM

I’m using a 37” LCD HDTV I bought from CostCo.  It’s an OEM using LG.Phillips chipset and other OEM components.

There is a big difference between LCD’s that are for computers and televisions.  Basically, once you go over around 21”, they using a different backlighting system.

15-19” LCD monitors use reflected light from a light-guide as the backlight, while big screens use rails of CCFL (around 11-12) direcly behind the screen.

Tear-down of 37” was, of course, much more difficult than the 19” I took apart.

ya, ive seen the rails of CCFLs...did you have any trouble with the ribbon/circuit boards being too short to get outside of the visible area? What are you doing for a backlight now?

No, the ribbon and cables do not interfere with the screen, they are long enough to be moved out of the way.

I am using the existing CCFL backlight: I just want to compensate for light-loss.

I’ll post pics of tear-down and preliminary prototype when i get the time

nima - 07 May 2008 02:18 PM

No, the ribbon and cables do not interfere with the screen, they are long enough to be moved out of the way.

I am using the existing CCFL backlight: I just want to compensate for light-loss.

I’ll post pics of tear-down and preliminary prototype when i get the time

hmm, so ur camera is shooting up through the ccfl rails? Wouldnt they block blobs?

no, the camera is placed on top of the CCFL rails

nima - 07 May 2008 03:38 PM

no, the camera is placed on top of the CCFL rails

oh interesting, yea id love to see some diagrams or something if ya can get it to work well.

I just want to come back on back light, I know the miror protection screen is cheap and offer a good effect like 2 way miror, Its cheap material but I dont know where to buy a big size.

EDIT: not for backlighting but to improve contrast

fifaille - 10 May 2008 02:30 AM

I just want to come back on back light, I know the miror protection screen is cheap and offer a good effect like 2 way miror, Its cheap material but I dont know where to buy a big size.

EDIT: not for backlighting but to improve contrast

I have a 12"x12" 2 way mirror im going to try to see if that improves contrast/brightness.

try searching google for acrylic 2-way mirror
they are cheaper to produce and sell than glass

At last I have had time to run some tests and take photos (There is tape everywhere because I used to test it as a diffuser but it’s pretty hard to remove so...) : the first one is just the screen + the backlight ; on the second one a diffuser is added between the screen and the backlight ; 3rd = 2nd + fresnel ; 4th = 3rd + a piece of the white opaque sheet (as you can see there it’s white) ; 5th = backlight turned off + the diffuser (tracing paper) ; 6th = what comes with the screen minus the fresnel.

Just ask if you want a specific photo, I’ll be glad to do it.

I really don’t know how to continue, the quality of the screen is too bad with the actual backlight and I can’t afford a new one. I think I’m gonna end up with a multitouch pad since I want to adapt multitouch on a jukebox.

I can see Its not very prety I just have a question for my project, on my screen the link between sides LCD and the “power” is too short how to do you can see on this pictures the problem…
Its a 15’ screen and I follow the Nima’s directives. I keep acrilyc with dots but I take away the white coat and a difuser, I have to take away another diffuser cause transparency isn’t good for me.

to improve backligthing, I keep the screen frame,
I think trying two layers of 2 way mirors acrilyc one like silver just behind the group of lcd, lens, difuse, light and another (black) I find in the home store, window row,…
like the 2nd picture, for the moment I have a good result for now but I will try an assemblage like the draw to have a good backlight and sensor.

fifaille - 13 May 2008 03:33 PM

I can see Its not very prety I just have a question for my project, on my screen the link between sides LCD and the “power” is too short how to do you can see on this pictures the problem…
Its a 15’ screen and I follow the Nima’s directives. I keep acrilyc with dots but I take away the white coat and a difuser, I have to take away another diffuser cause transparency isn’t good for me.

to improve backligthing, I keep the screen frame,
I think trying two layers of 2 way mirors acrilyc one like silver just behind the group of lcd, lens, difuse, light and another (black) I find in the home store, window row,…
like the 2nd picture, for the moment I have a good result for now but I will try an assemblage like the draw to have a good backlight and sensor.

Unfortunately it looks like you picked an LCD that is not optimal for this kind of work. Over at the lumenlabs community they call this “FFC Issues” which means the ribbon is too short to move out of the path of the LCD screen. They have a database over there that lists LCDs and if they have FFC issues or not, you are looking one without FFC problems, check it out here:

http://www.baseportal.com/cgi-bin/baseportal.pl?htx=/Lumenlab/main

you might be able to find extenders.

count how many pins the cable has, then measure the “pitch” in mm.  pitch is the distance between pins.

then search digikey
if digikey fails, then its tougher because manufacturers of flat cables don’t sell small quantities.... but it’s not imposibble

thank you for your answer, I will have to find what I need for this screen.

fifaille - 13 May 2008 11:22 PM

thank you for your answer, I will have to find what I need for this screen.

just be careful, those ribbons are insanely fragile.

Dear friends. I just got a 42” LCD TV. and I am going to take it apart later, Wish me good luck ... I would record the steps and share with you all.