Updated projection screen science
December 28, 2017
Over the past few years, the science of projection screens has made several major advances. Research and development of new methods and solutions have made the process of choosing a projection screen much different than it was just a few years ago.
To help architects and AV consultants keep up, Draper has released an updated version of our class on projection screen technology. Projection Screens 301: Updated Science of Projection Screens (PS301) contains the latest information on specifying the right screen solution.
The course objective is to provide a clear understanding of the various factors to consider when choosing a projection screen.
Among the factors taken into consideration are:
- Content/Use of system
- Seating Configuration
- Ambient Light Levels
- Room Dimensions
One of the biggest updates in screen science has been the ability to deal with ambient light conditions.
In the past, the majority of viewing surfaces had mostly diffuse reflection. These typically matte materials are best for extremely wide off-axis viewing, blending, and short throw projection. They reflect as much projected light as possible out to viewers at all angles. While this is great for spaces with low or no ambient light, if there is ambient light it will also be reflected out to viewers at all angles, “washing out” the image.
For a time, screen companies tackled ambient light with grey screens. While a grey tint can help improve contrast and absorb unwanted stray light scatter, it isn’t a true ALR solution. Many grey screens are diffusive, so they are still reflecting ambient light to the viewers.
ALR surfaces are specular reflective. They reflect the projection light back to the viewers, but reflect off-axis ambient light away from the viewers. Most ambient light hits the surface and reflects at an opposite angle of incidence. For example, off-axis light at 65 degrees will mostly bounce 65 degrees in the opposite direction. The amount of light it reflects away from the viewer is dependent on the amount of reflective properties in the surface’s formulation. The more specular reflective in performance, the better the ALR properties. However, this typically reduces off axis viewing performance. For instance, Draper offers screen surfaces that reflect 60%, 73%, and 82% of ambient light.
PS301 also covers contrast. Image contrast affects how well you can read, which means it affects detail and resolution. Low contrast reduces image detail and resolution, while high contrast increases detail and resolution. Image contrast is even more critical when the application involves high resolution graphics, medical imaging, control rooms, and CAD applications.
System contrast is an average of measurements of black at different locations on the screen, compared to white at different locations on the screen. This is measured in the existing lighting conditions of the application. Ambient light will affect the measurement of black. When measuring system contrast an ANSI checkerboard pattern is used.
Other subjects covered and updated include gain, hotspotting, throw distance, sizes, formats, and solution design using online calculators.
Updated Science of Projection Screens earns one AIA learning unit for architects, or one learning unit toward CTS renewal for those in the AV industry.
To learn more about all of Draper’s continuing education offerings, and to register for in-house presentations, click here.
Company: Draper, Inc.
Product: Projection Screens
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