Projection screens

The screen plays a major part in the quality of the displayed image.

Projection screens are installations consisting of blank surface and a support structure used for displaying a projected image for the view of an audience. Projection screens may be permanently installed as in a movie theater, painted on the wall, semi-permanent or mobile, as in a conference room or other non-dedicated viewing space.

Rigid wall-mounted screens maintain their geometry perfectly just like the big movie screens, which makes them suitable for applications that demand exact reproduction of image geometry. Such screens are often used in home theaters, along with the pull-down screens.

Pull-down screens (also known as Manual Wall Screens) are often used in spaces where a permanently installed screen would require too much space. These commonly use painted fabric that is rolled in the screen case when not used, making them less obtrusive when the screen is not in use.

Electric screens can be wall mounted, ceiling mounted or ceiling recessed. These are often larger screens, though electric screens are available for home theater use as well. Electric screens are similar to pull-down screens, but instead of the screen being pulled down manually, an electric motor raises and lowers the screen. Electric screens are usually raised or lowered using either a remote control or wall-mounted switch, although some projectors are equipped with an interface that connects to the screen and automatically lowers the screen when the projector is switched on and raises it when the projector is switched off.

Projection screen overview (surface contrast/brightness)

Typ D (matte white diffusion screen cloths)

Suitable for most applications particularly where light conditions are controllable. It evenly distributes light over a wide viewing area while colours remain bright and life-like, with no shifts in hue.

 

Typ S (Datalux Reflective screen fabrics)

Datalux fabric has been specially developed for projection applications where a higher reflection value and wider viewing angle are desirable. Accordingly, Datalux fabric is extremely suitable for video and data projection. Also ideal for use in conjunction with ceiling mounted projectors where the maximum advantage will be noticed.

 

Typ B (High Power Retro-reflectiv)

Retro-reflective screen fabric primarily reflects the projected light back towards the projector. Accordingly, it is highly suitable for applications where the projector is at table height, and is ideal for smaller presentations with fewer people in the room. Not recommended for ceiling mounted projectors as the light rays are bounced back along the exact path from where they came from.

For rear projection semi transparent projects screen made out of fabric, foils or plastic disks are use. Rear projection screens also have the benefit that people are less likely to walk between the projector and the screen, casting shadows over the image. Rear projection screens tend to be considerably more expensive than front projection screens.

Screen Size ans aspect ratio

The applications for which the projector will be used, together with the configuration of the presentation room and the amount of ambient light, affect the choice of fabric for the projection screen.

Generally when choosing the aspect ratio of your screen its worth taking into account the aspect ratio of your projector. If your projector is natively 4:3 match this with a 4:3 screen. This will give you the best effect filling all available screen space and optimising the projected image. As a general rule, 4:3 and 1:1 ratio screens are best suited to either business/data presentations or for watching tv. 16:9 ratio screens are best suited to DVD's or "widescreen" broadcasts/material.

Ambient light is the greatest consideration. If you're on the move and don't know what level of ambient light you're likely to encounter when you set up your projector, opt for a high brightness projector (2000 ANSI lumens or higher).

Screen size. The minimal distance should be calculated screenwidth x 2 (VPmin). The bigger the image you're projecting, the less concentrated your projector's brightness is going to be on each square inch of the screen. An average screen size is about 200cm wide. If you start going bigger than that, consider upping your brightness accordingly.

Frame
A black frame increases the optical contrast and shows the picture more straight. For home cinema, a projection screen with a black frame and an aspect ration of 16:9 is the optimum.

Maintenance (cleaning)
Projection screen have a are very sensitive surface. Only expensive products have a washable surface and can be cleaned. Therefore plastic-coated screens are ideal.

Gain

One of the most often quoted properties in a home theater screen is the gain. This is a measure of reflectivity of light compared to a screen coated with magnesium carbonate or titanium dioxide, when the measurement is taken for light targeted and reflected perpendicular to the screen. Titanium dioxide is a bright white colour, but greater gains can be accomplished with materials that reflect more of the light parallel to projection axis and less off-axis.

Frequently quoted gain levels of various materials range from 0.8 of light grey matte screens to 2.5 of the more highly reflective glass bead screens, some manufacturers claiming even higher numbers for their products.

Buying tipps

• Der linke- und rechte Seitenrand kann sehr oft schon nach innen gewölbt sein, gerade bei günstigen Leinwänden ist darauf zu achten. Durch starken Wölbungen können Konvergenzfehler auftreten.
• Check the backside of your screen. Non-plastic screens can easily get crumpled and are not recommended.
• Solid screen material works best. High quality material can cost up to 2000 Euro.