Best strategy for minimizing display aging?

[mathog]

What is the best strategy for minimizing display aging - both of the CCFL's and the electrolytic capacitors? (With specific reasons why.)

Certainly minimizing power consumption is best done by letting the screen saver blank the display on an inactive machine, so that the display will then drop into standby mode. However, I'm pretty sure that the display does this is mandated by EU and US power consumption guidelines, probably without any consideration at all of the resulting effect on the lifetime of the display. Hypothetically, starting a CCFL might age either the tube or the associated electrolytic capacitors in the power supply equivalent to 4 hours of steady use (this is a made up number just to illustrate the problem). In which case it would be better to leave the display on through the whole workday and not blank it when it is inactive, if that blanking happens 9 times a day, because 12 hours wear (4 startup +8 hours steady state) is less than ~47 hours wear (4 + 4*9 startup + 7 hours steady state) when allowed to blank. Conversely, if there is no startup penalty it becomes 8 hours vs. 7 hours, which is slight advantage to the blanked mode, with the biggest advantage to blanking being that the monitor will not accidentally be left on all night.

Beyond the blanking issue, the simplest assumption would be that the lowest acceptable brightness would be preferred, since it reduces heat and currents. Is that assumption valid? It could well be that CCFL's or their associated circuitry are actually most long lived at, say, 80% of maximum brightness.

[PlainBill]

Re: Best strategy for minimizing display aging?

What is the best strategy for minimizing display aging - both of the CCFL's and the electrolytic capacitors? (With specific reasons why.)

Certainly minimizing power consumption is best done by letting the screen saver blank the display on an inactive machine, so that the display will then drop into standby mode. However, I'm pretty sure that the display does this is mandated by EU and US power consumption guidelines, probably without any consideration at all of the resulting effect on the lifetime of the display. Hypothetically, starting a CCFL might age either the tube or the associated electrolytic capacitors in the power supply equivalent to 4 hours of steady use (this is a made up number just to illustrate the problem). In which case it would be better to leave the display on through the whole workday and not blank it when it is inactive, if that blanking happens 9 times a day, because 12 hours wear (4 startup +8 hours steady state) is less than ~47 hours wear (4 + 4*9 startup + 7 hours steady state) when allowed to blank. Conversely, if there is no startup penalty it becomes 8 hours vs. 7 hours, which is slight advantage to the blanked mode, with the biggest advantage to blanking being that the monitor will not accidentally be left on all night.

Beyond the blanking issue, the simplest assumption would be that the lowest acceptable brightness would be preferred, since it reduces heat and currents. Is that assumption valid? It could well be that CCFL's or their associated circuitry are actually most long lived at, say, 80% of maximum brightness.

1. Run the display at minimum acceptable brightness.
2. Set the computer to blank the display after the minimum acceptable period of inactivity.
3. Turn the monitor off at a power strip when it isn't going to be used.

PlainBill

[mathog]

Re: Best strategy for minimizing display aging?

1. Run the display at minimum acceptable brightness.
2. Set the computer to blank the display after the minimum acceptable period of inactivity.
3. Turn the monitor off at a power strip when it isn't going to be used.

Sure, but why, and can we prove it, or are we just guessing?

Letting the Devil advocate...

(3) is the simplest of these: when a display is "off" it isn't really, and those parts of the circuit which are running will be aging. Also since it is all plugged in the entire device is exposed to spikes and other problems on the power line. So it will cause less wear and be safer to physically remove the power.

(1) is only "best" if we are sure that the wear on the CCFL tube is proportional to the current through it (or some other function such that wear at i+delta(i) is more than at i). That seems reasonable, but I do not recall having seen any test data to support it. Plus one can imagine scenarios where the CCFL tube was designed to run at a certain range of temperatures, and running it too dim might run it too cool, which could result in excessive wear of some part leading to failure of the entire component. For instance, maybe one electrode will wear too fast if the tube is too cool.

(2) is only "best" if we can show that the startup phase does not wear the CCFL tubes or other electronics disproportionately. This one, I think, is most likely to be wrong, since turning on these circuits involves thermal changes (always bad) and nonsteady state currents (often bad). There are studies that thermally cycling some circuits wears them faster than just leaving them on. For instance (there were many others to choose from):

http://www3.interscience.wiley.com/j...3E3.0.CO%3B2-A

Which contains this observation from a test:

The damage evolution in the solder joints is shown in Plate 4. The microcracks are initiated at the
right inner corner of the solder joint, Plate 4(b), and the damage evolves along the gull wing lead,
Plate 4(c), until the left solder fillet domain is reached, Plate 4(d). Then the damage evolution is
locally diffuse, Plate 4(e) and (f ). The solder joint is totally broken after about 5000 cycles.

Of course that test was quite extreme, cycling up and down between -20C and 100C on a 3 hour cycle. That is typical in accelerated aging tests.

[smason]

Re: Best strategy for minimizing display aging?

Here's something annoying I have noticed on my computers.
Set power settings to turn off the display after 15 minutes.
Set screen saver to 30 minutes blank, require password on wake. I need this to keep riff-raff out.

So 15 minutes of no activity, screen goes off.
15 minutes later screen saver kicks in , blank screen with backlights on.
Backlights stay on forever.
How effed up is that?

[PlainBill]

Re: Best strategy for minimizing display aging?

Sure, but why, and can we prove it, or are we just guessing?

Letting the Devil advocate...

(3) is the simplest of these: when a display is "off" it isn't really, and those parts of the circuit which are running will be aging. Also since it is all plugged in the entire device is exposed to spikes and other problems on the power line. So it will cause less wear and be safer to physically remove the power.

(1) is only "best" if we are sure that the wear on the CCFL tube is proportional to the current through it (or some other function such that wear at i+delta(i) is more than at i). That seems reasonable, but I do not recall having seen any test data to support it. Plus one can imagine scenarios where the CCFL tube was designed to run at a certain range of temperatures, and running it too dim might run it too cool, which could result in excessive wear of some part leading to failure of the entire component. For instance, maybe one electrode will wear too fast if the tube is too cool.

(2) is only "best" if we can show that the startup phase does not wear the CCFL tubes or other electronics disproportionately. This one, I think, is most likely to be wrong, since turning on these circuits involves thermal changes (always bad) and nonsteady state currents (often bad). There are studies that thermally cycling some circuits wears them faster than just leaving them on. For instance (there were many others to choose from):

http://www3.interscience.wiley.com/j...3E3.0.CO%3B2-A

Which contains this observation from a test:

Of course that test was quite extreme, cycling up and down between -20C and 100C on a 3 hour cycle. That is typical in accelerated aging tests.

I suggest you reread my suggestion #3, then restate your objection. It may have escaped you, but if a monitor is turned off by a power strip IT ISN'T DRAWING ANY ELECTRICITY!!!

PlainBill

[mathog]

Re: Best strategy for minimizing display aging?

I suggest you reread my suggestion #3, then restate your objection. It may have escaped you, but if a monitor is turned off by a power strip IT ISN'T DRAWING ANY ELECTRICITY!!!

I wasn't objecting to (3), I was agreeing with it and explaining why.

I think (1) and (2) are probably best too. The problem being that for those I can think of scenarios where they could actually result in decreased display life.

[mathog]

Re: Best strategy for minimizing display aging?

Here's something annoying I have noticed on my computers.
Set power settings to turn off the display after 15 minutes.
Set screen saver to 30 minutes blank, require password on wake. I need this to keep riff-raff out.

So 15 minutes of no activity, screen goes off.
15 minutes later screen saver kicks in , blank screen with backlights on.
Backlights stay on forever.
How effed up is that?

What OS? On Windows XP if the power scheme is set to "minimal power management" and 15 mins, and the Screen saver is set to 10 minutes, then the screen saver will comes on for 5 minutes, and then the monitor blanks. The screen saver isn't set to require a password though. Try making your screen saver time shorter than the blanking time, and keep the password requirement.