LCD Backlight Upgrade

**jcdillin** · 10-07-2005, 06:09 AM

Originally Posted by greenman100

do you have any pics of how the CCFL assembly looks in one of our LCDs? the furthest I've had one apart is to the controller/LCD, not he LCD/cclf

From Here

http://www.jcdsystems.net/hitachi.html

**Scouse Monkey** · 10-07-2005, 06:22 AM

eurgh

I cant be arsed reading all these posts as I know it all already and I have a feeling it is repeating everything.

Our new approach is essentially the same as the one employed in direct backlighting as opposed to edge lit backlighting.

We came up with out designs prettty much independantly from any design guides as there are none! True, Jerry had a direct lit display he took apart but it wasnt until wuite far into the porject that i eventually managed to find a diagram of a direct lit screen using as 'heater element' tube like ours and a description of all the parts in the screen. What was funny is that it had a part that we didnt know commercially existed that we had already designed. This is an additional layer to the diffuser to assist with the diffusion of the direct lighting (

).

The only ommission we have made from a traditional dirct lit screen is a heater element under the CCFL to warm the tube in cold conditions. I dount we need this as people just need to warm their cars up if the screen in cold. Adding it would be a major headache due to safety circuits etc etc. We can also have an easier solution added to the inverters that increases the current flow to the tubes for the 1st few minutes to warm them. This increased current will shorten the tube life so it is not maintained for long. We can instigate this using an external temp sensor or button etc etc if the final inverters support it.

We have now found inverters that will power our 1st tube design but I was never happy with the high voltages.

The new design does use more tubes than we need BUT this allows us to run under spec which gives us less heat, more reliability, lower voltages than the current backlighting and softer light distribution.

Inverter cross talk is a major problem and also as the inverters are going to be add on modules now (not int he back of the case) then we are also going encapsulated for safety. Ultimately this will probably end up being safer than the existing setup of having an open inverter in the case!

The inverter will also have its own power supply with remote on off the screen power. The screen can then be powered off your PCs PSU and will only need about 4W on the 12V line and the inverter will be taking between 5-30W depending on brightness through its own PSU.

EDIT: good posting by JCD and TC btw - you guys have more patience than me at the moment.

**Scouse Monkey** · 10-07-2005, 06:26 AM

check my new sig!

**jcdillin** · 10-07-2005, 06:28 AM

But if anyone has some free time, I do need some help finding some connectors and silicone wire for to wire up this next batch of tubes. The first set we purchased came with high voltage wire but it was crap and I want to source my own.

**Scouse Monkey** · 10-07-2005, 07:55 AM

Jerry:

bwhahaha I never thought I would get to use those two on you! haha got you!

**turbocad6** · 10-07-2005, 08:53 AM

I have used wire from a hobby store designed for rc cars..... it seems silicone like & I had to extend a ccfl on a 10" install once, did over 20" no problem..... worked like a charm...... a bit heavier gauge, but worth looking into maybe?

**turbocad6** · 10-07-2005, 08:55 AM

these rc car electronic speed controls & radio recievers are highly suceptical to rfi... I think thats why the wire is so well insulated....

**turbocad6** · 10-07-2005, 08:58 AM

I used a connector that is also for rc car battery disconect..... I was surprised it didn't arc, but it worked fine with my one tube back then......its a really good plastic that seperates the spades.... don't know if you may need something like that though...

**Scouse Monkey** · 10-07-2005, 09:24 AM

i used to race RC cars too.

The wire is silicone multistrand. I think the silicone was used as it was more felxible than anythign else and could take a fair bit of abuse. We need something much thinner as it is hard to solder thick wire to the thin end of a CCFL in our space constraints. Maybe the cheap cars have thin wires but then i suspect they are normal insulation not silicone as flexibility is not a problem. I think we need to find some proper quality HV wire. I might look out for an old flourescent light fitting in a skip. As for the connectors i think digikey is gonna be the best bet. Come to think of it i think they do HV wire too. will have a look in a bit.

**jcdillin** · 10-07-2005, 11:35 AM

Originally Posted by Scouse Monkey

Jerry:

bwhahaha I never thought I would get to use those two on you! haha got you!

harharhar, thats a funny one, I meant that as more of I dont have time to look myself and if someone wants to help out with the project and find some wire.