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Backlight Brightness - which has best view from distance

falz

New member
Hello,

I picked up a CFAH2004A-YMC-JP (4x20, yellow/green text, black bacground) for a project to make an xbox into a non-ugly stereo component. I receeived it yesterday and it works great. However, the LCD goes behind a tinted "window" and it dims so that it can barely be viewed from any reasonable distance.

Does anyone know what would be the BRIGHTEST and MOST VIEWABLE LCD of the parallel LCD's with HD44780? I'd prefer to have the text be the only part that's "lit", but perhaps the inverse ones are more legible?

Here's a few pix of the current one, if anyone's curious:

Here's the LCD in action, without bezel on:


Here's the case, but this is prior to the LCD being in place:


I did take a few pix with the LCD behind it, but the camera couldnt pick it up really. Full pix and info are here if anyone's truly curious:

http://falz.net/xbox_stereo_component_with_lcd

--falz
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CF Tech

Administrator
How much current are you driving through the backlight? (Or: What is your backlight power source and how big is the current limiting resistor?)

The yellow array backlights like you have are typically the brightest. Is the panel a filter? If you put a white light behind the panel, does it just look like a dimmer white, or is it some other color?
 

falz

New member
The specs say this wants 280mA to 560mA at 4.2-4.6 volts.

My (possibly poor!) calculations are that ideally I need a 2.8Ohm resistor to get me to 4.2V, 280mA. The power source I'm using is 5v, I used a 2.2Ohm resistor, as it was all that I could find locally.

If I did my math correct, I could go as low as a 1.4-ish Ohm resistor- I'm hesitant to do this since, as earlier- I'm not much of an electronics guy, except fiddling and soldering and such. Perhaps this will give it a bit more light?

The panel in front of it is colorized- I can try the flashlight trick, but it's effectively the color of the window over an IR reciver that a typeical TV or stereo component would have.

Thanks
--falz
 

cmgp

New member
I' currently building a media center also but I'm trying to install 2 40x4 screens in mine, I'm building my own case but I'm short on time right now I' thinking of going the lazy route buy a media center case and mod the hell out of it I would like to known did you have trouble fitting that LCD in that case? or was it an easy fit?
 

CF Tech

Administrator
The backlight sounds right.

It could be that the lens just does not let the yellow light through well. Maybe cut a window in it ?
 

falz

New member
cmgp said:
I' currently building a media center also but I'm trying to install 2 40x4 screens in mine, I'm building my own case but I'm short on time right now I' thinking of going the lazy route buy a media center case and mod the hell out of it I would like to known did you have trouble fitting that LCD in that case? or was it an easy fit?
LCD was about 1/4" too wide- it was fairly simple to cut a bit out in the existing hole. I used a tin snips to cut a few portions, then bent it back with a pliers, and drilled a few holes that line up with the holes in the PCB for the LCD and it worked like a charm.

The LCD in this case could also be twice as high, if such a thing existed. If you wanted to go all out, you *probably* could fit two 4x20 LCD's high, if it were the type that the PCB didn't extend any higher/lower than the screen.

CF Tech said:
The backlight sounds right.

It could be that the lens just does not let the yellow light through well. Maybe cut a window in it ?
I'd like to avoid cutting it, as I'll make it.. ugly. Is it correct that in the specs for the LCD- it shows a range for mA- if I give this more juice (mA) will it get brighter? Say, if I were to use a 1.5Ohm resistor instead of a 2.2?

--falz
 
You can increase the current to the backlight, which will decrease the lifetime a lot, but that probably won't help any. The plastic filter for IR sensors is designed to block most of the visible spectrum. The only way you can succeed is to change the plastic to a neutral gray type, that looks similar to the original, but that is not wavelength specific.
 

falz

New member
Thanks for the info. I'm fairly sure that the company that made this case (and plastic) made it with the intention of having an LCD behind it- They sell their own LCD to put there that's the correct size.

Are there any "larger font" character LCD's that anyone knows of? Same thing, but "bigger"?

--falz
 
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