Fluorescent LCD backlight lamp life turnon-off lcd monitor screenblank/screensaver???

[mike]

Just got a flat-panel LCD monitor.
I'm wondering what I should do to maximize backlight life.
The fluorescent backlight will wear out if I leave it running all the time.
But it's my understanding that the worst/most stressful thing you can do
to a fluorescent lamp it to turn it on.

Is there a screen blank (lamp turnoff) strategy that makes significant
life improvement over not worrying about it?

Thanks, mike
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[PeteS]

In that wonderful LCD monitor you got there is a backlight inverter
(producing around 600 - 1500Vac). One of the pins very commonly found
on it is 'Sleep' which is used for exactly what you would want to do.
Without knowing what model it is and where it's connected, it's hard to
comment further

Cheers

PeteS

 

[mike]

In that wonderful LCD monitor you got there is a backlight inverter
(producing around 600 - 1500Vac). One of the pins very commonly found
on it is 'Sleep' which is used for exactly what you would want to do.
Without knowing what model it is and where it's connected, it's hard to
comment further

Cheers

PeteS

The question is/was NOT HOW to turn it off.
The question is/was, "does turning it on/off improve the overall tube life?"
And What's the tradeoff between leaving it running vs turning it on/off
a lot.
There's gotta be a peak somewhere on that curve. It's probablly broad,
but...
mike

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[PeteS]

Well, we do LCD displays (industrial types, but the same type of
screen - TFT-LCD) and we put the backlight in sleep mode after a
programmable time (usually 30 sec to 1 min) of no touch/mouse activity.

We have a number of units that are still going strong after 3 years.

For the best scoop, go check out the info on the webistes of the LCD
manfacturers.

Some names are Sharp, Kyocera and TDK (well, they are the ones I use)

Cheers

PeteS

 

[Roger Johansson]

The question is/was, "does turning it on/off improve the overall tube
life?" And What's the tradeoff between leaving it running vs turning
it on/off a lot.

I see no reason why it would hurt the tube to turn it on and off.

In fact most fluoroscent tubes are turned on and off 50/60 times
a second, as they are driven by mains AC power.

The mechanisms for aging in fluoroscent tubes are usually that the
fosforent layer which transform the ultraviolet light into visible
light is being used up. So it should be good for the lifetime to turn
it off whenever it is not needed.

The OP is maybe thinking about common incandescent light bulbs, which
take a beating every time they are turned on and off. But fluoroscent
tubes do not work like that.

 

[mike]

mike wrote:




I see no reason why it would hurt the tube to turn it on and off.

I'm always skeptical when a sentence starts off, "I see no reason
why..." Can you point me to some measurement data or vendor proclamations?

In fact most fluoroscent tubes are turned on and off 50/60 times
a second, as they are driven by mains AC power.

That's different. The electrodes are hot and if there's mercury in
there it's vaporized etc. Not the same as striking a cold tube.

Maybe it doesn't matter...that's what I'm asking.

The mechanisms for aging in fluoroscent tubes are usually that the
fosforent layer which transform the ultraviolet light into visible
light is being used up. So it should be good for the lifetime to turn
it off whenever it is not needed.

Interesting. I've NEVER seen a fluorescent that died cause the phosphor
got used up. It's ALWAYS been a problem starting...rather not starting.
I've converted most of my home lighting to CF. The ones that fail the
most often are the ones that get switched the most...but I think that's
electronic ballast failure...maybe not relevant data.

The OP is maybe thinking about common incandescent light bulbs, which
take a beating every time they are turned on and off. But fluoroscent
tubes do not work like that.

No, if I'd been thinking about incandescent I wouldn't have used the
word fluorescent.

Didn't mention it, but the backlight inverter also takes a beating every
time it turns on. That may be higher failure mode yet.

mike



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[Roger Johansson]

I'm always skeptical when a sentence starts off, "I see no reason
why..." Can you point me to some measurement data or vendor
proclamations?

No, I am not working and I am not paid to work.
The "I see no reason why..." means that I try to help because nobody
else did, and I know something about fluoroscents, but if you want
really good, certified answers you turn to somebody else.

That's different. The electrodes are hot and if there's mercury in
there it's vaporized etc. Not the same as striking a cold tube.

There is vaporized mercury also without the heating. The heating just
helps it vaporize more, at the ends of the tube.
That makes it easier to start the current, with lower voltage demands.

Maybe it doesn't matter...that's what I'm asking.

I don't think it matters, but maybe somebody else has a better answer.

Interesting. I've NEVER seen a fluorescent that died cause the
phosphor got used up. It's ALWAYS been a problem starting...rather

I talked about ageing, not sudden death. Sudden problems are very
seldom caused by the tube, but rather by the ignition/driver circuit.
The igniter, if one is used, takes a beating every time you turn on the
tube.

In smaller tubes and backlighters I don't think they use the common
heaters, but rather electronic solutions, and often in smaller
tubes there is no need for a heater, you just start the current
through the tube, with a high voltage peak.

not starting. I've converted most of my home lighting to CF. The
ones that fail the most often are the ones that get switched the
most...but I think that's electronic ballast failure...maybe not
relevant data.

Does changing the tube solve the problem in those cases?
If so the tubes are worn out somehow. If you need to change the circuit
the problem lies there.

Didn't mention it, but the backlight inverter also takes a beating
every time it turns on.

How do you know that?

 

[mike]

mike wrote:




No, I am not working and I am not paid to work.
The "I see no reason why..." means that I try to help because nobody
else did, and I know something about fluoroscents, but if you want
really good, certified answers you turn to somebody else.




There is vaporized mercury also without the heating. The heating just
helps it vaporize more, at the ends of the tube.
That makes it easier to start the current, with lower voltage demands.




I don't think it matters, but maybe somebody else has a better answer.




I talked about ageing, not sudden death. Sudden problems are very
seldom caused by the tube, but rather by the ignition/driver circuit.
The igniter, if one is used, takes a beating every time you turn on the
tube.

In smaller tubes and backlighters I don't think they use the common
heaters, but rather electronic solutions, and often in smaller
tubes there is no need for a heater, you just start the current
through the tube, with a high voltage peak.




Does changing the tube solve the problem in those cases?
If so the tubes are worn out somehow. If you need to change the circuit
the problem lies there.




How do you know that?

It takes more voltage to strike the lamp than to run it.
Higher voltage = more stress???
mike



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[Roger Johansson]

Do you know the answer to that question?
That would give both me and you the answer we are looking for.

It takes more voltage to strike the lamp than to run it.
Higher voltage = more stress???

Not for the tube, as far as I can understand.