LCD backlight replacements/repairs

http://www.palmtoppaper.com/ptphtml/47/47c00007.htm

Looks like its been done before on the HP palmtops! Maybe I should just get in touch with Hal and see if the supplier of the enhancement in this paper has any idea for transflective polarizer for DSTN screens!

ok, i understand you. i've never seen a T3 but i saw ppc's (the evil ppcs, yes!) and they're quite readable in sunlight so i know what you mean...

like you, i never knew there were notebooks with (d)stn, until i read about them some months ago i've seen only tft ones

WOW!

oh, i'm reading the article now... it's just the famous backlight issue.. i heard they never were quite successful and stopped doing this... but still it might be worth asking them...

ya ... well, I did find out that the polarizers for TFT and DSTN are *different* ...

The LCD used in the Vadem CLIO is a Sharp LCD. So maybe I might just try to see if there is a replacement TFT transflective LCD for it!

But meanwhile I'm waiting for followup replies from a few manufacturers and suppliers of transflective polarizer film. A few local ones and one from Japan! Will keep you folks posted.

oh the other thing I figured out is that, the glare from the surface is actually causing most of the unreadability issue. It means that the backlight is fighting with the glare. ok, guess its kinda like *duh* ... but it means that modding the polarizer layer to transflective type is just part of the solution. The surface (release layer) need to be modded to be anti-glare as well.

I'm just amazed at how the few polarizer films actually work together to evenly spread the thin backlight for a uniform *back*light.

At the moment, the only thing that is certain is that the CCFL in the backlight can be (fairly) easily replaced.

The Jornada 700 series use Hitachi SX16H003 or SX16H004 if it's useful for finding a replacement ;-)

I'm not sure if I read correctly, but the tech specs of the SHARP DSTN LCD in the Vadem CLIO has a brightness rating of 41~60cd/m2 whereas the newer CCFLs I found online are typically rated with 38000 ~ 46000cd/m2. Even some low brightness CCFLs are 6500cd/m2 ... someone tell me I read the tech specs wrong ...

... or it means that the backlight of the Vadem CLIO was designed to be highly dimmed ...

has anyone got this to work / done this themselves? id love to see the results if possible. my lcd gets a grainy sort of effect going on it, anyone else have this issue (ive got a mp780) ?

also ive been thining about getting one of those antiglare filters (like this one http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1111256&CatId=165 ) and cutting it down and somehow fitting it in to the casing. any suggestions?

Edited by no-success 2005-06-10 11:16 PM

As I suspected, such filters are *GLASS* based and not film based. Wonder how you will cut it down and fit into the already tight LCD panel?



I'm going to receive a CCFL tube today and some polarizer films sometime next week. Will update and let you know how things work out.

any new news?

Going to town to run an errand today and hope to receive the transflective polarizer thingie.

Got a sample CCFL the other day and fitted it into the CLIO DSTN screen. Its shining like a flash light right now. Apparently the inverter can supply the 5mArms current needed although the factory CCFL only draws 2.4mArms.

ZE BAD
Yes, it drains the battery like a running tap so now the original batt runs for 2 hrs on end! ... Guess either I find a CCFL with 2.4mArms or else I'll have to revert back to the original CCFL. Or maybe a refurbed batt will bring the batt life back to 8 hours?

ZE BRIGHT
Batt aside, the screen is now (almost) as bright as the TFT LCD on the desk. Its more viewable in the sunlight as well. Downside is that the brightness control is now like bright, bright & bright. ie no doing anything. I'm not sure whether the inverter is doing a voltage drop or current drop to change the brightness. Seems to me that its doing a voltage drop thingie, and hence is not really changing the brightness a tad!

If I receive the polarizers, will update with the results.

oh, I'll see if I can take some snaps with the webcam later. You judge for yourself if the screen is bright. Who knows ... I might be fooling myself! (but the battery drain is definite! )

Edited by Snappy! 2005-06-16 2:14 PM

Hi all,

Updates at hand:

First, the bad news ...

not all the films were in stock, so one of the piece is on back order.

Some what good news ... the screen does look nice and bright with the new polarizer thingie. ... At first I didn't know the films had protective films and it looked ok. With the protective films removed, the screen looked pretty good.

And the ugly ... 3M sent me 2 identical TBEF films. Not sure if I should use only one, I put both in. I'm no LCD genius here, so through the trial, I found that putting two in gives a boggling moire effect on the screen! ... I will need to check with 3M on the status or correct usage!

In direct sunlight, the glare is just too offensive to see any difference from the previous test I did. If I can get 3M to send me samples for removing the glare, we might come to something.

I'll revert to the old CCFL and see if it is still brighter than the original brightness. Will update later.

oh, I'll post pictures later, if not tomorrow morning.

Have you tried reversing and or rotating the film as the moire could be caused by the incorrect photon patch through the various layers?

erm, ya, I thought of that, and tested it outside of the panel and could see the patterns change. Unfortunately, this to me may mean that precision orientation handling is required, something which I am unable to do on such precision. ... and besides, having cut it down to size to fit into the panel, it (the film) no longer go any other direction and the remaining piece of the film is too small.

oh, here's the pix ... not stellar ... I changed back to the old CCFL, 'cos the newer one was really confusing the battery with its higher amp, and also shortening batt life.

CLIO1 - 100% brightness
CLIO2 - 50% brightness
CLIO3 - 0% brightness









Attachments
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CLIO1.JPG (21KB - 31 downloads)
CLIO2.JPG (21KB - 28 downloads)
CLIO3.JPG (21KB - 26 downloads)

btw, the auto lighting control of the webcam seem to make the 3 images look similar. ... but notice the difference in lightness of the (same) hand in the three pictures.

ok, 3M sent me the final set of DBEF-M polarizer film (don't ask me what the acronym meant! )

Here's two pictures. I cut a small piece and insert into the LCD panel this time, instead of a whole sheet, so that I can get a comparison.

The first picture shows the LCD face on, and one cannot really tell from the pics, but in real life, the square looks like a somewhat brighter patch! ... don't know how they do it, something to do with recycling P2 lights into P1 lights and sending them out.

The 2nd picture is taken from an angle, and this shows how the film somehow makes the screen viewable even from an angle!

Direct sunlight viewing is still out, as I soldered back the old CCFL tube. If they send me the top-layer anti-glare film, I'll try it out and maybe it might improve things for outdoor viewing.







Attachments
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clio4.JPG (23KB - 16 downloads)
CLIO5.JPG (22KB - 18 downloads)