Archive for August, 2006

Hanging Projection Screens

Friday, August 18th, 2006

If you’ve ever been in a high school classroom, chances are that you have come across a hanging projection screen. These are the most popular types of projection screens in high schools because they are the easiest to use, and easiest to store.

A hanging projection screen is one that is placed on the wall or ceiling at the front of the classroom. When the teacher wants to use the screen all he or she has to do is pull it down from the housing in which it sits. This makes it quite easy for any teacher to get their projection screen into place without having to go through too much of a hassle.

Another benefit of a hanging projection screen is that it is out of site when it is not being used. Not only does this free up space in the classroom, but it can also help to keep the screen clean when it is not being used as a teaching device. When a hanging projection screen is pulled up it will not be visible, therefore it can stay clean.

In addition, hanging projection screens are usually used on the same wall as the blackboard or dry erase board. If they were not able to be moved the rest of the wall would be pretty much useless.

Not every hanging projection screen can be rolled up and down, but the majority of them can. Keep your eyes open the next time you are in a classroom; the chances are that you will see a hanging projection screen.

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Big Screen Technology Buying Guide

Saturday, August 5th, 2006

If you are a TV lover and have spent any time at all walking past the displays of big screen TV’s in your local stores, I can fully understand what happens — your remote control finger starts to twitch, your rear end starts to long for that comfortable spot in your favorite recliner, and you have a sudden urge to take your shoes off. At least that’s what happens to me. I admit it, I am a TV junkie. Not that I spend a lot of time in front of the TV but when I am there, I require quality, and the more quality in video and audio, the happier I am.

But with the technology available today to the consumer, the choices almost boggle the mind. And Joe Average doesn’t follow the technology closely enough to be able to understand which technology is best for his needs. In fact, Joe’s only gauge of quality is the unit’s price tag, which is probably about the LEAST reliable gauge of them all. So let’s take a quick look at the various technologies available for big screen TV so that you better understand what you are looking AT, as well as understanding what you are shopping FOR.

Regular tube TV: Yes, depending on your budget, this needs to be mentioned as a viable option, although unless you’ve been living in a cave for the past 50 years, there is little new that you need to know about it. It’s a TV, plain and simple. Tube TV’s are typically limited to about 36 inch pictures, with a couple top-end brands even getting to the 40 inch mark. The picture is good, and most of today’s upper-end sets also allow the viewing of HDTV on the same unit. My only word of caution here is that I cannot recommend a set that has a built-in VCR and/or DVD player. The built-in units are typically not high quality with limited functionality, and for the additional money you would pay for such a combo unit, you can get an external VCR or DVD player for far less money.

Now on to the big stuff. But first, since I already mentioned it, a word about HDTV. HDTV is great, providing an incredible picture quality, provided of course that you have the screen that can display that quality. With HDTV, without getting all techie about it, the digital signal contains much more information, and the picture is created in PROGRESSIVE mode rather than INTERLACED mode, meaning that the ENTIRE picture is refreshed with every scan instead of just every other line as is done with interlaced.

I would also recommend a unit with the wide aspect ratio, like 16:9 or sometimes 16:10. This is the ratio of width versus height of the display, and the wide aspect ratio is the one you see when you go to the movie theatre. You can still watch broadcasts on the wide aspect ratio that are designed for the old traditional 4:3 aspect ratio, but it is much harder to watch something designed for 16:9 on a 4:3 display.

Another word of warning: there are big screen units that cannot do HDTV but they can do EDTV. Be aware that these are not the same. In fact, with the next step (SDTV) right around the corner, I don’t see a long lifespan for EDTV. EDTV provides better quality than standard analog TV, but not as sharp and crisp as HDTV.

The different types of big screen TVs are discussed below.

Plasma TV

Advantages: long life (30,000 to 40,000 hours from brand names, significantly less with noname brands), very bright - up to 4-5 times a standard TV, viewing angle is huge - you can be 75-80 degrees off center and still see a clear picture, instant-on feature - there is virtually no warm-up time required, small footprint - since these units are very thin and could even be wall-mounted.

Disadvantages: possible burn-in or “image retention” if the same image is left displayed on the screen for an extended period of time (although when used as a TV this is probably not a concern), can be very pricey at the largest sizes possible (currently around a 50 inch display), very few have a tuner/amplifier built in so you will be required to get an external tuner, pixel failure - where a single pixel just remains white all the time although this is much more common on noname brands and may (check!) be covered under your warranty.

LCD TV

Advantages: Great brightness levels, also very thin and could be mounted on the wall, long life (about 40,000 hours on brand names, substantially less on noname brands), viewing angle is about 45 to 50 degrees from straight on.

Disadvantages: Ghosting - where there may be “artifacts” left on the display during a fast-action movie scene because the LCD cannot keep up with it that fast, viewing angle is not as good as plasma, very expensive technology today, not as good at reproducing accurate color as plasma.

DLP Rear Projection

Advantages: Low purchase cost although this is typically offset by higher operating costs. At the sizes above 42 inches, the DLP big screen is approximately the same price as plasma.

Disadvantages: high operational cost (the single bulb in the projector can cost upwards of $300 to replace), large footprint - you will need to allocate about 15-18 inches from the wall to accommodate the unit, not wall-mountable, poor viewing angle - not much more than 20-25 degrees from straight on, gradually decreasing bulb brightness over time which means your picture is not as sharp or bright.

Understanding the various display technologies available should help you, but keep in mind that this is not the whole story. Also know that as technology advances, prices will continue to fall and there may be more options in the future. There are many other factors to be considered which are discussed at my web sites below. But at least now you have a good feel for the type of technology that will work with both your desires and your budget.

Jon Arnold is an author and computer engineer who maintains various web sites to provide tips and information on a variety of topics. More info on this topic can be found at his Home Theatre Web Site site at http://jag-info-resources.com/home-theatre/

Article Source: http://EzineArticles.com/?expert=Jon_Arnold

Video Projector Screens

Saturday, August 5th, 2006

A projector is an apparatus for presenting an enlarged image on a screen from a transparency such as a photographic slide or a film. In a motion picture projector, each frame is held stationary at an illuminated aperture for a brief period, and then advanced by an intermittent sprocket or reciprocating claw, the light being cut off by a rotating shutter during the movement. One should have a clear idea about video projectors before buying video projector screens.

Video projectors have become common and captured the market throughout the world. They are especially common in schools and colleges where it becomes necessary to show videos and films (especially in film schools and institutes), or any place where people need to show films on a regular basis at a cheap rate to a large number of people.

There is a wide range of video projector screens available in the market. One can buy the kind of video projector screen one wants depending on the kind of surface. The surfaces vary from smooth to rough, and minutely undulated ones. However, before considering any video projector screens, one should consider the following elements: resolution, brightness or reflectivity, contrast, color accuracy, and build quality.

Some of the white (or gray) video projection screens can bring about a difference in resolution, or image detail. There should be a rating to indicate its inherent reflectivity, on which the brightness of the image depends. Contrast of the image is also dependent to great extent on the video projection screen. A screen should not reflect any color other than that of the projector itself.

Projector Screens provides detailed information on Projector Screens, Video Projector Screens, Home Theater Projector Screens, Electric Projector Screens and more. Projector Screens is affiliated with Large Format Flatbed Scanners.

Article Source: http://EzineArticles.com/?expert=Jennifer_Bailey