Feb
28
Screen Gain 101
Filed Under Front Projection | Leave a Comment
If you’re new to the front-projection world, at some point in your research, shopping or browsing you’ll stumble on the term “screen gain”. You’ll want to know what this is and how it applies to different rooms and projectors before proceeding down the front-projection path to home theater nirvana. Screen gain is the measure of how reflective the screen material is, or in the broader sense, how much light the screen reflects back into the room and ultimately to your eyes.
Typical screens are rated at gains from 1.0 (neutral gain) to 1.2, 1.3 and beyond. There are even some negative gain screens designated as 0.8 and alike. Generally speaking however all you have to remember is that a 1.3 gain screen should appear brighter than a 1.0 gain screen, at least from the same manufacturer. Although rare there are cases where one manufacturers 1.0 gain screen could appear brighter than another’s 1.2.
I generally advise my clients to stay away from the ultra high-gain screens if they have the ability to control the light in the room, i.e. make it completely dark. Typically the low-gain screens present less off-axis viewing irregularities and in many cases just plain look better than their high-gain counterparts, when paired with a bright enough projector. Of course if you can’t control the light in your room at all times of the day, a high-gain and or high-contrast gray screen may be just what the doctor ordered.
Feb
26
Digital Light Processing (DLP)
Filed Under Front Projection, Terminology | Leave a Comment
In order to discuss the different display technologies effectively (at a later date) we’ll need to define some of them upfront. I could have started with LCD, plasma, D-ILA, SXRD or any number of others but I wanted to start with DLP (Digital Light Processing) as its one of the most common front projection technologies in use and well, front projection is just plain cool. DLP was developed by Dr. Larry Hornbeck at Texas Instruments in the late eighties but believe it or not front-projection wasn’t one of the first implementations. It (DLP) was actually used to fuse red dyes (text and images) onto airlines tickets.
DLP uses millions of moving micro-mirrors to create the images we see on-screen, the mirrors are fixed to a chip called a Digital Micromirror Device (DMD) which is illuminated by the projectors lamp (gross oversimplification). The technology is known for its accurate colors, sharp images and often better than average contrast ratio.
DLP’s create color by focusing the light path through a color-wheel; multiple “colors” are projected by varying the speed of the color wheel. Early DLP’s were prone to smear colors (known as rainbow effect) due to the slow speed of color-wheel but this was all but eliminated in recent models by higher-speed, multi-segmented color wheels.
3-chip DLP projectors eliminate the color smearing problem altogether with the use of one DMD per primary color, i.e. red, green and blue. 3-chip DLP’s are quite expensive when compared to their single-chip counterparts but are generally perceived as superior in all regards.
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