LED backlight mod.

Has anyone here swapped the CFL for LED's on their toughbook screen? I just pulled apart a dead screen I had to see if it was possible and it sure looks like it. I'll be doing it on my new CF-72 when it gets here. It should give me a lot better brightness and longer battery life.

The CFL is at the bottem edge of the screen, and about the diameter of 14 awg wire. There is at least 1/4" of unused space below the display, so I'm going to drill a bunch of 3 mm holes for T1 LED's in the metal rail, insert the led's and probably hold them in place with GOOP, and then build my own controller.

What do you think. Anyone else done this? Worth it?

 

Sounds interesting and good! I mean u will be the first here with such a hack ( I had no time ;-) ).Which type of LED and how many will u use? Have u ever seen the hardware of an real LED-backlight? I would mean, the mainproblem are the lenses, which are normale on this LEDs and that the light is the same on every place on the screen...

 

I just went to this site today by accident. See if it will help:

http://spritesmods.com/?art=ledbl

 

After searching google a bit it does not seem to be a very popular thing to do.

I would love to swap out my ccfl for a set of new super bright leds.

I know that the newest TB's are using LED backlighting now which is a great idea.

-James

 

That’s the rumour James,but I have not seen a review to confirm
The cf-30 states 1000nit, now I find it hard to believe that the specs are identical to the old model
I would think that the leds would be off a little , for instance 950nits or 1050nits
But the cf-19 max on the old model was 540nit and now its 1000 so I don’t know for sure
And the battery capacity seems to be higher , now that would lead me to believe that they have switched to leds, as they are more efficient

I was hoping that Rob would get in touch with his friend at Panasonic to get some review models and report back to us


Alex

 

Well i read that the GETAC v100 tablet is using LEDs and it is claimed to have 1000nit touchscreen.

I would hope that panny follows this and uses LEDs as the last longer are brighter and most of all tougher. \

I hope the new batteries are compatible with the MK1 and MK2

-James

 

I'm thinking of using 48 LED's, and sandblasting the lens end to give a more diffused light. I'll have 12 sets of 4 in series and it will draw somewhere around 200-250 mA. Not sure what the CFL inverter draws, I'll have to measure it.

 

if u do so with goups of leds u should try an multiplexer, maybe 6-channel. so u can decrease the current.

 

If you do end up trying this please let us know how it turns out.

-James

 

I would think that if they changed the MK-3 to LED that the screen dimensions would be different. Meaning the thickness and all that. It doesn't appear to be the case. I am sure the reviews will start hitting pretty soon, they are more than likely doing them now.

 

I've experimented some with the 5mm T1 white LEDs and the 3mm minis; there are a few issues. while you can achieve adequate brightness for small displays (like the 7" display in my OBDII programmer) from a single edge of the LCD panel, larger displays are hard to get adequate brightness at the top edge of the display from a single strip of such LEDs. I suspect the issue lies within the inherent heat dissipation characteristics of the package; 5mm will dissipate less than .1W safely, while the 3mm minis dissipate about half that before melting down. This is probably why people who design & implement these professionally:

http://www.insyncperipherals.com/index.html

use high efficiency (read uber-expensive) ceramic-case SMD LED like these:

http://www.ledtronics.com/Products/cat3.aspx?P=C542D546

http://www.kingbrightusa.com/lobbymid-high.asp

The other issue I had with the T1s is fundamental to the design; the lens-end shape created a tendency of the light to be concentrated in columns no matter how closely I packed them together. I believe this is another reason for the different case design; better light diffusion.

As an aside; I found that after all was said & done, my little LED upgrade on my programmer, which, while bright enough and useable, was not nearly as uniform as the original screen. The fix was acceptable to me however; they wanted $400 for a replacement display, and the custom size of the CCFL I replaced made a generic CCFL unavailable. It only cost me $45 all told, with several revisions and then creating a driver circuit parallelling several blocks of LEDS across a 7805 SMD regulator IC. As for the efficiency... well, once done, it drew about 25% less current than the original CCFL & Inverter; I wasn't that impressed, and it made negligible difference in battery life.

My other experiments with full-size LCDs were dismal failures; all due to the same issue of not being able to get adequate illumination from the bottom edge of the screen to the top; newer LCDs use a CCFL at top & bottom for better brightness, so they may lend themselves to hobbyist-type upgrades like this.

Good luck,

mnem
No, Marcus. You can't eat mommy's mouse...