Projectors: Turn it off or leave it on? (1 Viewer)

[DanThomas]

I'm trying to figure out how most people use their projectors. When you're going to stop watching for a while, then come back and watch again, what do you do? Do you turn off the PJ or leave it on?

Maybe it depends on how long before you intend to watch again. So what do you do if you're going to watch again in 1 hour? 2 hours? 3 hours?

And if your PJ has a "soft power-down" mode, do you use it or just hit the "off" switch? Again, this might depend on how long you expect it to be before you watch again.

So let me know what you do!

-Dan

 

[Leo Kerr]

My experience tells me that cycling the power to the projector is one of the hardest things on it.

If I'm stepping away for

 

[Tim Glover]

If I get a phone call that is important and might take a little time, I will turn the pj off. I wait about an hour before I turn it back on though. I keep my on low power mode too.

I use the "shutter" feature if I need to step away for a minute. This prevents any burn in.

 

[Evan M.]

Just curious but do you have a CRT FP?

As for how to shut it down.......Do exactly what Leo says.

 

[Tim Glover]

No, it's an LCD.

 

[DanThomas]

I've read elsewhere that each hit on the lamp is like 2 hours of usage. If this is true, then you should probably only turn it off if it's going to be longer than 2 hours.

 

[Evan M.]

A lot also depends on the FP and the bulb that is in it. My 4805 bulb has lasted longest from other users doing the "one hour rule" as mentioned. Other may vary a bit depending on the watage and such.





You can't get burn in with digital FP like an LCD. You can degrade the pannels but not get burn in.

 

[Leo Kerr]

...to which point, the LCD shutter is probably just blacking out all three panels, rather than pulling a mechanical shutter. If that is the case, then the shutter will 'age' the panel faster than a white screen.

I've heard that a lamp-strike is like 1 - 5 hours of lamp usage. I've also heard that one might want to assume a ballast for a lamp has a finite number of strikes in it.

These are excellent rules of thumb, but I have no idea if they really mean anything or not. Which is why I sort of compromised on the hour-rule.

(Actually, for me, it's generally pretty obvious: if I/we aren't back in ten minutes, chances are good that we're scrubbed for the rest of the night.)

Leo

 

[DanThomas]

My PJ (InFocus 4805) has an option that will turn itself off after a 20-30 minutes of no signal. I've enabled that option, although I don't make much use of it. I mostly did it so if someone else shuts off the equipment and forgets to turn off the PJ, it won't stay on all night... Anyway, in your case if your PJ has that option then it might be worth using?

Just a thought.

-Dan

 

[Tim Glover]

I didn't know that. That's good to know. I always thought that it would. Thanks for that tip Evan. Now I can rest easier when the phone rings.

 

[Evan M.]

LOL!! No problem.....
As far as I know only CRT will give you burn-in issues......somebody please correct me if I am wrong....

 

[frankinG]

Evan is exactly correct about crt devices being the only current display technology to have any 'burn in' issues.

LCD can leave 'temporary ghosting' because of the static charge being applied to the lcd panels at a sustained constant voltage. This generaly will be seen for all lcd displayes with a contant image being displayed for 'prolonged' periods of at least a few hours to a few days. This 'temporary ghosting' disapears after resumed regular moving images continue.

The technological explanation of this phenomenon is the different temperatures on different parts of the lcd panel which causes the 'menronic fluid' which is the organic part of the liquid crystal material makeup. Scince voltage at different levels are applied to specific areas of the panels, there will be different rates of expansion because of heat buildup. Of course as the still image changes, the extra heat, which is actually measured in the thousands of millivolts, gets cooled by the resumed voltage fluctuations across the panels. The voltage 'excites' the crystals, which is what makes the 'image' you see on the screen when the light passes through them.

D5 LCD, which our sales team has already seen first hand in japan is a 'substantial' improvement over earlier designs from what we have been told.

We have had LCD presentation projectors at our company that were run 6 to 8 hours a days for years and never experienced any panel degradation.

This was also on projectors that had still images on them for business presentations.

The bulbs in some of them had so many hours on them, that no one even knew just how long the run time was. Seems that constant running time on the bulbs was extending there life span well beyond the norm.So from these experiences I would say that constant use of the bulb would be better than constantly turning them on and off.

Hope this helps.

20'x14' dedicated theater
Panasonic PT-AE 700U projector
Draper onyx m1300 106" tension screen
Anthem avm 30 pre-pro
Rotel rb 1095 5 channel amp
Rotel rb 1080 2 channel amp
Paradigm reference speaker system
HTPC 1 to 1 pixel mapped (soon to be replaced by denon 3910)BETTER!

 

[Evan M.]

EXCELLENT info and explanation frankinG!!



I have heard this from other people too. I always thought that the "independent study" that Texas Instruments did when trying to convince people that LCD's will degrade over time while DLP's won't was pretty lame. Will an LCD panel eventually degrade.....yes (name me a technology that doesn't degrade over time).......but when that happens is ultimately up to the user and how careLESS or careFUL they are. Like anything else....take care of your equipment and take appropriate measures and an LCD will last just as long as a DLP. I would NEVER choose DLP over an LCD because of the chance of panel degradation.
FrankinG, am I correct when I hear that supposedly IF an LCD panel degrades the blue panel is usually the first to go? If so, why exactly is that??

 

[frankinG]

When I had my previous sony G70 crt projector, there was over 16,000 hours on the tubes and the green tube actually was starting to go first. This of course was a crt device which really does not apply here.

Yes, the blue panel is the one to degrade first. Just how long will it take? Well I am sure that by the time it does, you will be a much older person who had already upgraded a few times.

I asked a tech who works on projector color management at our company about the chemical nature of LCD tints and this was his response:

Blue is the color most used in producing 'other' colors. So the blue panel is being subjected to the most voltage time. Kind of like having 3 people all running but the distances they have to go are all different.

In actual fact, the panels are really just the 'shutter system' or the mechanical part of the system for light control. The 'polarizers' are the color or colorizing devices. The blue panel is really a generic term for the combination of the two.

The polarizer in the blue spectrum will actually fade the fastest over time, but it will take a really long time.

Blue filters are used the most by cinematographers for that 'cold look'. A prime example of this is used in the movie 'Assault on precinct 13' and the first 10 minutes of 'Hellboy'. You will probably know automatically what the 'look' is just by these scenes. These cinematography techniques are the most commonly used. Blue, Blue, Blue. This panel is the most commonly used of the 3. It is subjected to the most 'light time' which like the effects of ultra violet light on our bodies,will fade colored objects.

Blue pigment is chemically unstable in its makeup compared to other colors. Not to say that it falls apart or anything like that, but some colors fade or degrade faster than others.

These are just a few reasons and there may be more.

It is safe to say that a color wheel in a dlp projector would have to be changed long befor an lcd panel would.

I am actually a big fan of DLP but I just cannot watch for extended viewing times. Darn it!

 

[DanThomas]

I'm starting to think this is true also, at least from the anecdotal evidence I've read.

-Dan

 

[Leo Kerr]

Evan,

the TI test you refer to was kind of brutal.

That said, in our experience at work, most LCD projectors are not designed for heavy duty-cycle work, and we were told by the un-named manufacturer that our warrantee was invalid, because we were 'abusing the projector.'

Our abuse consisted of running them for ~9 hours/day without breaks. In all cases, they were well ventalated. We had polarizers decay, and we had the optical prism block begin to delaminate.

So for that reason, all projectors we've purchased since then have been either 1 or 3 chip DLP units. And I've been nothing but pleased with the 3-chip 5 and 6k-lumen projectors. We're getting 1750 +/- 250 hours out of each lamp, and the image color and contrast are just like new.

Our LCDs would show signs of degredation at about 3000-4000 hours, and be junk by 6000 hours.

Leo Kerr

 

[frankinG]

I am not sure if there is a difference between manufacturers but the salesman I bought my projector from has a panasonic PT-AE 500U and he has been through 2 bulbs. Each bulb lasted over 4000 hours. He is now on to the third with no problems with the projector itself even after 9000 hours. So it seems that maybe type A is better than type B, but who really knows.

Like I had previously mentioned, we have numerous LCD units that are many years old and are still in perfect operational condition. Many of these are very high lumen projectors that run almost all day.

I guess everyone has different experiences with their projector life but personally if I could not get at least 5 years out of a specific manufacturers products I would be quite surprised.

 

[Ralph P.]

Greetings,

I am currently on my second LCD front projector. My first was a Sony HS10 that had 1600 hours of use when I sold it. At 800 hours on the first lamp I replaced it and kept it as a spare after I purchased a new lamp. When I sold the unit the lamp had a little over 800 hours on it.

My current unit is a Sony HS51. I got it in April and the lamp has around 460 hours on it. I average around 100 hours a month. The lamp is usually struck twice a day. Once in the morning ( I am up early and will watch the unit in the AM for roughly 1 hour or so ) and once in the evening ( family TV time for 2.5 hours or so ).

This is the same pattern I used with my HS10 as well. Once my lamp reaches 600 to 700 hours I will pick up a new lamp. The original will become a spare.

I plan on having the HS51 for longer than I had the HS10 ( had that a year and a half ) so I will see how long a lamp lasts with my pattern or use.

 

[Evan M.]

Ralph, why do you "replace" a lamp after only 600-700hrs?? Do you experience a large amount of brightness loss at that time? I am familiar with the Sony products but do not own any. I have not heard of anyone buying a new bulb on a FP after every 600 hours unless there is a large loss of brightness or something is wrong (defect). If you are experiencing a large brightness loss after 600 hours to the point where you need a new bulb you might want to think about a different FP because as far as I know that is pretty strange. I do know that the Panasonic 700 experiences a drop in brightness after about 500hrs but I don't think it is large enough to go out and buy a new bulb. I am not sure on what the bulbs cost but at the amount you watch and replace that is 2 new bulbs a year when you can probably get by with using less then 1 a year.

 

[Ralph P.]

Greetings,

Evan, I don't buy one every 600 to 700 hours. I only do it initially and that is done so that I have a spare in the event of a problem. I install the new lamp because of the 90 day warranty issue. After this initial shift I will keep the lamp that is in the projector until it needs replacement.

I had no brightness problems with my HS10 and so far have none with the HS51.