AV and Multimedia Related Thread, Guidelines for Projector Quality in Technical; ...
2nd February 2011, 11:37 AM #1
Guidelines for Projector Quality
We've now got to the stage at our school where we have to justify every single expenditure in writing (due to the budget cuts).
We've got a situation whereby we have a number of projectors which are approximately 8/9 years old and they are getting to a point whereby just replacing a bulb won't fix the problems that they have (in addition the bulb prices on these particular projectors are
over £200 each! so buying a new projector would only cost us a low percentage more).
What I'm looking for is some sort of guideline that talks about how good the image should be that is projected. For example, should the image be visible without having to turn off the classroom lights? In all classrooms with this particular projector, unless you turn off all lights you cannot see the image, which I am sure must be straining the eyes of the people looking at it.
Anything anyone can suggest on that will be very gratefully received as always.
14th February 2011, 04:18 PM #2
- Rep Power
I think its hard to buy a projector that won't be up to scratch re. brightness...
Look for education models which often have better warranties, pricing & lamp life. It can be a good idea to overspecify and run in eco mode which increases lamp life, and reduces running costs. The Casio lampless models might also be an option although they are more expensive, they are supposed to run for 20,000 hours.
BECTA standards did require a minimum resolution of VGA. I have heard that there are issues with projectors being "too bright" for the classroom with a consequent risk of damaging pupils eyes which is why many education models won't exceed 2200 lumens (which is bright enough for a lights on presentation anyway).
Here's an example of an education only model spec which seems to offer a 3 year lamp warranty and 5000 hour lamp life... as I say there are a range of similar models from all the main manufactuers, it just happened to be this one I found 1st..
Epson EBX8LAMP Projector
The EB-X8 offers not just a stylish new design but great performance as well. Thanks to its friendly design and portable weight you can easily go anywhere and use the projector very easily. With its wide connectivity you can broaden your multimedia experience. Its exceptional value is complemented by an outstanding 5000 hours long-life lamp offering you extra peace of mind. The EB-X8 is definitely your preferred partner for business presentations.
Brightness (Normal) 2500 ANSI Lumens
Brightness (Eco) 1960 ANSI Lumens
Lamp Life 5000 Hours
Native resolution XGA
Aspect Ratio 4:3
Contrast Ratio 2000:1
Lens Throw Ratio 1.48-1.77:1
Horizontal Keystone 0. Degrees
Vertical Keystone -30 to +30 Degrees
RGB ports quantity 1
DVI-I ports quantity 1 HDMI
Monitor Re-Drive Yes
USB Control Yes
USB Memory Stick Yes
RS232 connection No
Wireless compliancy No
Network Capability No
Carry Case Full
Feature 3 Year Lamp Warranty
Dimensions W x D x H 228 x 77 x 295 mm
Weight 2.3 Kg
Warranty 3 Year De Re Install Swap Out and 3 Year Lamp Warranty
15th February 2011, 12:17 PM #3
In a hall situation i would recomend a projector of 3000 lumens or above, this will give you a good image on a 10 ft diag screen size, but all is dependent on available light, so with out seeing it it is difficult. But based on my experiance in schools and site unseen the above is a fair guide. Epson EB824H would fit this situation at around £600 or the later EB825H slightly more depending on where you get it and both with 3 year on site cover including lamp.
In practice in hall use i have found them to be a fit and forget install i have never had to go back to one yet, and i have never had a faulty one.
15th February 2011, 12:42 PM #4
Our hall projector is 4500 Lumens and can be seen with the lights on, but is much improved with lights off. That's on a 4m screen in a hall more or less made of windows though!
As far as classrooms are concerned, the new Casios at 2500 lumens are bright enough to be seen with lights on, which is obviously better if students are taking notes while the projector is on. The one we currently have installed is in a Science room with large windows though, so I'd say 2500 to be the top end of requirements.
It's worth arguing for the LED ones if you want to cut running costs down. I did a quick comparison yesterday before ordering 3 more LED projectors and a projector of equivalent brightness (Epson EB X9 2500 Lumens XGA Projector | Ebuyer.com), although half the price initially, would cost 50% more over the 20,000 hours due to cost of bulbs*. The likelihood is that bulbs will increase in price as they are produced in less volume, and they tend to degrade in quality/brightness as they age unlike the LED projectors (at least, that's my understanding of it)
* Cost of Casio new: £700
Lifespan: 20,000 hours
Cost of Epson new: £340
Lifespan: 4,000 hours per bulb
Bulb cost: £170
TCO over 20k hours: £340 + 4x£170 = £1020
Even in eco mode, at 5,000 hours per bulb (but with less brightness), TCO is £850.
15th February 2011, 02:09 PM #5
Thanks for the replies....think I've not got my message across particularly clearly.
We have a number of aging projectors which are beginning to lose quality to the extent that the rooms have to be in near total darkness to allow people to see the image clearly and I'm trying to justify having the projectors replaced (the bulbs cost as much as a new projector so it makes more sense to buy new). Are there guidelines that say, if the quality of a projector is so poor that all lights have to be turned off, that it si harmful and the whole unit should be replaced? Or is it perfectly acceptable to have staff/students sat in near total darkness to view a projected image?
15th February 2011, 03:23 PM #6
If they are expected to take notes or otherwise work whilst the projected image is on, I would say it is unacceptable to ask them to do this in darkness. Don't know of anything formal off the top of my head but I suspect HSE would have something to say on it, perhaps under the Visual Display regs - they certainly talk about screens in direct light etc. so I imagine they would talk about difference between ambient light and screen.
One would always hope that common sense would say that students can't be expected to work in the dark, anyway. Perhaps your LEA (if appropriate) can offer advice on the topic, something with a little mroe weight and formality?
15th February 2011, 07:18 PM #7
Think it would only take a teacher to claim health and safety risks (or your own risk assessment) to make it a replacement issue, especially if they claim it is affecting their sight (squinting?), or if lights out would hinder evacuation in the event of a fire.
Originally Posted by Iain.Faulkner
Of course, there is a practical difference between darkness and complete darkness, one might be acceptable, the other probably not.
Not sure that display screen equipement regs come into play (as it refers to backlit devices such as LCDs or CRTs) though you could certainly draw parallels and make a case based on them.
17th February 2011, 12:33 PM #8
As an engineer i wuold recomend replacement if the brightness AT SCREEN is less than 150 Lumens with lights off, a projector MUST be usable with lights on but you cant get a true reading with lights on.
Just out of interest the rcomended (BECTOR) brightness (at lens) is 1500 for a class (joke), but 2500 (at lens) in practice is the norm.
as you increase the screen size the brightness reduces so a 3mtr hall screen wuold need at least 3000L as long as it is not all glass sided.
Oh and for info LED units DO get less bright with age its called half life it means how many years till it is half as bright, so a figure of 6 would mean in 6 years it will be only half as bright as it was when you bought it, problem with LED Laser projectors (casio) is two units provide the light, LED and Laser and they have a different half life so the colour will also change with age as well.
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