Die richtige Wahl der Leinwand

As long as we live in an imperfect world, we will always be faced with presentation problems, such as ambient light, limited room configurations and budget restrictions. All of these problems need a solution. As the educational leader in our industry, Da-Lite is always searching for ways to present solutions. That is why we developed "Guide to Selecting Front Projection Screens."

Da-Lite offers a wide array of screens, each with a choice of projection surfaces. Selecting the right combination to meet your needs is important for optimum results. This manual will guide you through the selection process step-by-step to select the right screen fabric for any application and projection method. Da-Lite makes it easy by giving you all the information you need to fully understand the requirements of your individual application followed by an exclusive decision matrix that actually recommends the right fabric by answering a few easy questions.

The screen fabric recommendations contained in this manual are based on Da-Lite's years of experience as the leader in projection technology. These recommendations take into account all major projection methods and applications such as home theater. You can expect Da-Lite to add to these recommendations in the future as technology and more options become available.

Although the thought of choosing the right front projection fabric may seem intimidating, it's actually a straightforward process. Da-Lite makes it easy with its unique matrix approach used in this manual. Please keep in mind that it may be preferable to use rear projection technology depending on your application.

There are three basic steps in selecting the right screen fabric:

After you have selected the screen fabric, you'll need to choose a screen product by considering the required physical characteristics of the screen such as size, operation (i.e. fixed frame, manual roll-up or electric roll-up), and mounting (i.e. ceiling mounted, wall mounted or floor mounted). Da-Lite offers the largest selection of screen models in the world. Consult any authorized Da-Lite dealer for additional information or contact us directly for the name of the dealer nearest you.

Refer to the section on screen fabric descriptions for further definition of screen fabrics and their properties. Also, consult the glossary for terms commonly used when discussing projection screens and uses in this manual.

Take a projector, put a screen in front of it, turn down the lights and you have a presentation. If only it was that simple. Unfortunately, there are many other considerations, both physical and environmental that affect the quality and viewabilty of a presentation. We call these Presentation Media applications.

Today's typical Presentation Media applications fall into the following four distinct categories - Each with its own unique requirements and problems. The optimum viewing solution demands the projection surface fully address these requirements and problems.

If your particular application is not described here exactly, consider the relevancy of problems and special situations identified in other applications as a guide to using the selection crtieria list. Choose the application that best describes your situation.

This growing application brings the realism of the "cinema" home. You'll find a wide spectrum involved in this application from video enthusiasts who build dedicated home theater rooms to movie fans that convert their living rooms or dens into mini-theaters.

Consider these characteristics and problems typically found in Home Theater applications:

Home Theater Characteristics

• Typically this application uses some type of video projection but could include some slide projection. Popular today are LCD and DLP projectors combined with surround sound audio equipment.
• The application objective is to attain the highest degree of visual and audio realism. The desire is to make the audio-video experience as close as possible to the feeling experienced at a modern-day cinema.

Special Problems or Situations

Typically, you'll find most home theaters have one or more of the following problems.

• Lighting conditions may not always be controllable. For example, windows, skylights and entry ways can allow stray or direct light into the room, negatively affecting image quality.
• Screen surface could be easily soiled or damaged by children, pets, etc.
• May require wide or narrow angle of view depending on room configuration.
• Screen surface must remain taut to maintain resolution and eliminate disturbing shadows when projecting with video devices like LCD, DLP and CRT based video projectors.
• Could possibly require a variety of projection aspect ratios i.e. HDTV, letterbox, standard broadcast television.

This classic application is a key communication method in today's hectic business world. Communicating effectively in mass enables companies to get employees up to speed quickly. Likewise, in the educational setting, educators are finding an emphasis on visual communication is not only favored by students but as importantly, is far more effective in sharing information and concepts.

Although business and educational settings are worlds apart, their Presentation Media characteristics and problems are common.

Classroom and Business Training Characteristics

• Any setting where a medium size group of people are seated around an instructor using presentation media as the focal point for communicating ideas or information.
• Generally, participants take notes and refer to additional reference materials requiring higher ambient lighting.
• Interaction and eye contact between the instructor and the student is vital in teaching and maintaining audience interest.

The cornerstone of business is the "meeting." Without meetings, vital information is slow to be communicated. The result is quick paralysis of an organization. The better the ability to communicate clearly, quickly and effectively, the better the results.

In this application, you'll find a wide array of room configurations. Established meeting rooms with built-in presentation capabilities are ideal but not as typical as standard rooms outfitted with portable projection devices with screens made to fit. Either way, the physical and environmental characteristics of both have similar objectives.

Business/Boardroom Style Meeting Characteristics

• Any group meeting where the main emphasis is imparting information and not for the express purpose of interacting with the audience during the presentation.
• Typically, these presentations are made in rooms designed or earmarked for presenting. Lighting and ideal seating arrangements can be controlled.
• Although this application generally involves smaller groups, the size of the audience can vary greatly, limited only by the physical size of the room.
• A wide range of projection media are typically used alone or in combination - including standard video, PowerPoint, Word and data projection.

Special Problems or Situations

• A variety of projection methods (i.e. video, overhead or slide) may be used on the same screen, requiring a screen surface that addresses the needs of all without severely compromising the image quality of any one method.
• Depending on the projection method and room size, image brightness may suffer.
• The audience is typically closer to the screen than optimally recommended, dramatically exaggerating the viewing angle for some audience members.

Presentations to a large group of people can be an exciting and impressive Presentation Media application. Yet, it is in this application more than any other, that selecting the right screen is critical to satisfying all audience members with a quality image.

In this application, you'll find auditoriums with built-in permanent projection booths, large multi-purpose rooms (like hotel banquet/function rooms) where flexibility requires portable projection methods and impromptu or infrequent presentations in large areas not specifically designed for presentations (typically found in businesses).

Auditorium/Large Group Meeting Characteristics

• Typically large numbers of seated or in some cases, standing audience members where room size usually dictates a wide viewing angle.
• Very limited interaction between presenter and the audience, if any.
• The need for a large image size requires a projection method/source with substantial lumen output.

Special Problems or Situations

• Depending on seating position, image quality may not be ideal due to wide angle and/or distance from screen.
• Although film projection is generally used with high lumen output, multiple (stacked) video projectors may also be used to accomplish higher light output.

Selecting the Right Front Projection Screen Surface

Da-Lite Screen has identified seven basic criteria for selecting the right screen surface. Each criteria is designed to provide characteristics a screen must possess to meet the application's objectives as discussed earlier in this manual.

These Presentation Media criteria are as follows:

CRITERIA #1 - PROJECTION METHOD

Determine the primary type of projection method to be employed. If multiple projection methods are to be used equally, determine which one has the most demanding requirement and use that as your selection criteria. For example, in the case of an application requiring a front projection screen to display multiple projection methods, use the method with the most demanding requirements.

VIDEO

CRT Technology - A video projection system using three-tube projectors (one for red, green and blue) with a fixed focal length and are usually lower in light output. Alignment of the three tubes is critical for best resolution and color rendition.

LCD Technology - This technology uses a conventional light source, usually a halide arc lamp, to project an image by passing light through three internal liquid crystal displays-one each for red, green and blue. Each image is then combined by a series of mirrors into a single image.

DLP Technology - This technology is based on the Digital Micromirror DeviceT (DMDT) which uses over 500,000 microscopic mirrors on the SVGA chip to reflect images on screen.

D-ILA Technology - In this technology, light is reflected off a mirror surface located under the LCD pixel layer. This reflective process results in higher brightness and contrast levels.

LCOS Technology - LCOS devices have crystals coated over the surface of a silicon chip, which is coated with a reflective surface. Polarizers are located in the light path both before and after the light bounces off of the chip.

35MM Slide Transparency - One of the most popular methods of displaying single-frame photography. Like other portable film projection methods the slide's continuous tone properties and the projector's high light output (varying from 1000 to 6000 lumens), provide an excellent image-showing fine detail and exceptional color rendition.

Part A - Determine whether or not light conditions are controllable to minimize ambient light when needed
-Controlled light assures no substantial stray light is allowed to enter the room that would increase ambient light levels to a point where the projected image is affected.

Part B - Determine if uncontrolled light is directed at the screen causing the projected image to "washout".
An example is uncontrolled light from sources such as ceiling lights directed on to the surface of the screen.

CRITERIA #3- DISPLAY BRIGHTNESS

Use the following simple formula to determine the brightness (in foot-lamberts) of your display.

Determine if the seating area will require audience members to view the projected image from a narrow (Figure 1) versus a wider (Figure 2) angle of more than 30 degrees from either side of the center of the screen. If the room configuration (i.e. is more wide than deep) forces audience members to view the projected image from an angle greater than 30 degrees, a screen fabric providing a greater viewing angle is required.

Determine if the projected image is one or more of the following:

a) Conventional video images - Generally speaking this is an image that does not contain very fine detail, so resolution is not as critical.

b) Continuous tone images - Found in all slide film projection methods. Provides the best image in terms of resolution and color reproduction.

c) Digital or pixelized data with fine detail, (i.e. textual information as found in LCD and DLP video projection devices) require higher resolution to project characters with clarity.

Determine if the projector will be placed perpendicular to screen center.

Whenever the projector and the audience are on opposite sides of the normal and require a higher gain screen, use a screen that is reflective. (Figure 1). Whenever the projector and the audience are on the same side of the normal and require a higher gain, use a screen that is retro-reflective. (Figure 2).

Determine if the screen surface will be subjected to one of the following

Potential soiling or damage from inadvertent or constant handling. Typical situations are in high traffic areas where people may accidentally touch the screen surface or in public or educational settings where the screen surface could be abused. Potential soiling can happen in settings where there is a problem with airborne debris and dust.