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Wall Visions
Taking Advantage of Your Built-in, Invisible Screen
So now you've decided that it's time for a big screen setup in the home. You've been won over by reasonably priced projectors, high quality DVD movies, and even higher quality high definition programming. The immediate reaction is that this means something big, something that dominates a room, something that will obviously still be there when it's not being used. Sure, there are complicated, and expensive, ways to drop projectors and screens down from the ceiling, but for the average home owner these aren't really options. But there is one option that can be both remarkably efficient and effective, and even elegant in its simplicity - Wall Visions!
Think about it. If you use your wall as a screen for your front projector, when the system is off, there is no screen! When the system is on, the screen can be as big as the available wall area. Of course there are downsides, and of course this isn't for everyone. Read on, and we'll go into a few of the advantages and disadvantages, and you can decide for yourself if such a system
might be right for you.
Why Use Front Projection?
Front projection is necessary in order to achieve the larger image sizes, and even some moderate image sizes, with reasonably small hardware size. When most people consider a large screen display they will go for a large CRT, a flat screen display (plasma or LCD), or a rear projection display (CRT, LCD, LCoS or DLP). These displays can all be very good, and continually improve, but they are all physically large - in some cases significantly larger than the image they create. More importantly, they are also limited in maximum image size. How big an image is needed for an involving "theater" type experience? The screen width should be more than one half the viewing distance, particularly for high definition sources. This means that if you sit 10 feet away, the screen should be more than 5 feet wide. This is easily achieved with front projection, and with reasonable cost and small hardware size.
About Projection Screens
So just what is a projection "screen" anyway? Is it some special magical device that makes a picture when a projector is directed towards it? No, not really, a screen is simply a flat surface that is illuminated with light, including desired light from a projector as well as unintentional light from other sources, and that light is reflected back into the room, including to the viewers. As anyone who has used any type of projector knows, when you point the projector at almost any object, you see the projected image. If you aim the projector at a bookcase, you still see an image, but of course you won't want to watch it for long. But when you point it at a white wall, suddenly the image can become not only very
pleasant to watch, but under the correct conditions it will be excellent.
A way to understand what a screen does is to first think of a
screen as being made up of several million tiny squares, each
perhaps the size of a grain of rice. Now turn your
attention to any one square, and see what happens when light
falls on that square. Any incident light, both from the
projector and from other room sources, will light up each tiny
square and the square will reflect that light pretty much
equally in all directions. The brightness of any square
will thus depend upon how much light falls on it - if the
projector throws a lot of light in that direction, it will
appear "white". But if the projector throws little or no
light at a given square, it will appear dark. Your eye then puts
all the squares (some light, some dark, some colored, etc.)
together to see the complete image! Note that since all the squares lie in the same plane, they don't light each other up, at least directly.
Why Use a Conventional Projection Screen?
What are the advantages of a
conventional projection screen over a white wall? With a quality manufactured viewing screen you will get a flat, clean, viewing surface, with some chosen "gain" characteristics, and with a pretty border or frame. It can be installed on a wall, can drop down from the ceiling, can be angled in a corner, can be tilted, and can even be perforated with small holes so a center channel speaker can be placed behind. You can get motorized panels for the sides to change the screen shape to match the projected image. It can be shaded gray, instead of white, in order to appear darker to the normal room light. It can also be made to selectively take the projector light and preferentially send more of that light to the viewing audience rather than the ceiling and floor - this results in "gain". Gain can both make the projected image appear brighter, and make the ambient light from other parts of the room "wash-out" the image less.
We should also note that projection screens also have their limitations. If they get dirty, they can be difficult to clean without damaging the screen. If they have "gain" the corners may appear dimmer than the center, and with digital projectors you may see some "sparkle". If they are not stretched uniformly, they may not appear flat. And perhaps most of all, when the projector is off the screen is still there!
Wall Screen Characteristics
When you use your existing wall as a screen, the "screen" quality takes on the quality of your wall. If your wall is flat, smooth, white, and low gloss, it will make at least an acceptable screen in almost all reduced light applications. On the other hand, if your wall is colored, dirty, or is uneven, the projected image will have these same characteristics. What the "wall screen" won't have are screen borders to "frame" the picture,
and it won't have special "gain" characteristics to make the whites appear brighter and the blacks to appear blacker. But it will cost a lot less, and it will totally disappear when the projector is off, which can be a powerful advantage. You can also easily change the size of your picture by using the
projection lens zoom control, or by moving the projector closer or further back.
Not that, if desired, you can also enhance your wall screen by using paints that are made specifically for this use, and you can paint a black "frame" or border around the picture area. But, of course, while this kind of customization can also save some money compared to purchasing a screen, when the projector is off the screen no longer "disappears".
Is a Wall Screen for You?
Of course only you can decide. What we can tell you is that using a wall as a screen can be very effective in displaying large screen entertainment, yet simply be a wall when the system is off. We know of many projector owners who purchased their projector before buying a screen, tried it on a white (or off-white) wall, and were simply blown away by the image. Most would go on to purchase screens (most thinking it would get even better), but
a few would stay with the wall projection only. The choice is up to you. We hope we have introduced you to a concept that may bring a wonderful balance between a truly large screen, involving theater environment and a natural, uncluttered setting for your normal every day living activities.
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