Anyone using Vacuum Flurecent Displays?

[Art]

Hi Guys,
I got two of these yesterday, and it looks like I'm getting a couple more soon.
My only concern with using them in a project is their tendency to fade with time.

Having a few backup units helps though.



This isn't mine, but a project of the guy who did a trade with me.
it's driven with an Atmel chip.
Mine are single line, 40 char displays that are driven with the same back-end (HD44780),
and share the same pinout as parallel LCD displays, making them PicBasic compatible!
I can't wait to use one.



Art.

[Dave]

Art, Are those Nixies or Numetron's behind the Flurecent display? I built a driver for a NIXIE display clock project quite a few years back and it gave me a flash back..... Oh the warm glow of plasma....

Dave Purola,
N8NTA

[Art]

They look like either valves or nixies, but it doesn't look like they are being well looked after.
As I said though, this isn't my stuff, I just got the same displays.

[BobK]

Hi Art,

I used some 4x20 VFD displays several years ago that I got from Rentron.
Worked great on my project. I think I bought some spares for future
replacement. I also bought some 4x20 Blue LCD's as a backup. I did
read about the potential problems that arise over time. I personally see
see it several times a week on my job as an alarm service tech. We have
alot of early Radionics panels that used VFD displays that have lost their
brightness.

What I did on my project was to use mesages that moved around the display
so that the same message didn't stay in the same place for more than
a few seconds. Seems to have done the job. But I do expect to have to
replace them at some point. That's how you make money in the service
business. I believe you can adjust the intensity through software so that
they aren't as bright which might help keep them going longer. You can
probably put an LDR into your micro and let it adjust the brightness
depending on the ambient light around your display.

HTH,

BobK

[Art]

Unfortunately I don't know how to change the brightness.
Pin3, which is usually the contrast adjustment for this pinout,
is instead used to reset the display. I don't know why you'd want to do that.

There probably is provision to change it, and I just don't know about it.
Google certainly didn't help where a datasheet is concerned.

[Ioannis]

I like the color of these VFD's and the brightness too.

But for sure they fade with the usage. I have a HP Printer on my desk that you can hardly see what the display shows in complete darkness!

And it cannot be replaced with LCD as it is completely different pin-out...

So now I prefer to use the Blue LCD's an am quite happy about it. My customers too!

Ioannis

[Art]

Hi again Guys,
I finally got around to making a test circuit for it.



There are no datasheets or anything to be found with a Google search,
so if anyone finds this as a result of their search it might be useful to
give the screen brightness commands here.

Pretty simple really, 0x28 is the command for brightness, and that is followed
by a data byte from 0 - 3, 3 being the lowest brightness setting so:

LCDOUT $FE,$28,3 ' set VFD to lowest brightness setting

You'll see I move the display around on the screen as suggested to avoid burning any pixels,
particularly with a time & date display.. the year 2010 is going to stick around on the
display for a whole year before changing, so that would ruin it pretty quickly.

Cheers, Art.