About Multi-Aspect Ratio Screens
Not so long ago choosing a projection screen for a home theater room was a simple affair. For starters there were only a few different screen materials to choose from and only one aspect ratio. It was the Academy Standard aspect ratio which we now call 4:3. The only real screen-related issues that installers had to contend with during the design process, then, was how large one wanted the screen and whether or not the customer wanted an electric rolldown or fixed model.
BOY have things changed since then. Today we have four major manufacturers of home theater screens and each company offers not only a multitude of different screen materials but dozens of screen housing configurations. Not only that each one of these models is usually available in several aspect ratios. Now things are getting complicated. Fortunately, the major home theater screen manufacturers came to the rescue with multiple aspect ratio screens a few years ago. These unique screens allow the home owner to switch the shape of the viewing surface to match the aspect ratio of the video source being viewed. The problem is that these multiple aspect screens are somewhat complex and many people are unsure how to integrate them into home theater control systems. The object of this article is make this interfacing and control issue easier to understand. The bottom line is that these things arent really that complex. Once you have the basics, they easily installed and programmed.
Lets look at the types of multiple aspect ratio screens that are currently being offered. First there are fixed models that are designed to mount on the wall or some other type of support surface. These screens switch aspect ratios by moving masking panels in from the top and bottom, in from the left and right sides, or both as Stewarts Ultimate 4 way screen, from all four sides. For those that need the screen surface to retract, all four of the major manufacturers offer electric rolldown models that lower dual masking panels on the left and right sides. These screens typically have a main screen surafce that is a wide aspect ratio ( usually 1.85:1 or 16:9) and the masking panels extend to mask the surface down to a 4:3 ratio. Since this articles focus is on the control of these screens, however, we wont go into a complete dissertation of the different models but refer you to the different models as reference on the navigation bar on the left.
In order to understand the finer points of multiple aspect ratio control, lets take a look at control system that Vutec supplies with their Vision XVM4 screen. The Vision XVM4 screen is one of the models that rolls down a large widescreen surface and for 4:3 use extends left and right masking panels. This action requires just two internal electric motors; one for the main screen and one for the two masking panels. The various aspect ratios that this screen can be configured as are all a function of where these two motors move the surfaces to.
Controlling the Vision XVM4 screen is typically done in one of two ways. The most common way is via a wall mounted control panel. As our diagram illustrates, this control pad has six buttons on it. On the left side there are three buttons, one to raise the screen, one to lower the screen and one to stop it when it is in motion. By using all three of these buttons, one can adjust the screen for a multiplicity of aspect ratios. On the right side are three Preset buttons, each one of these can be programmed for for a specific aspect ratio. In our diagram, we show the three buttons programmed for 4:3, 16:9 and 2.35. Wall-mounted control panel installations are popular because they are easy to use and instantly understandable for the home owne.
The Vutec Vision XVM4 screen can also be controlled by third party home automation systems. These systems, such as Crestron and AMX control systems, can interface with the Vutec Screen Controller Module via a six conductor cable. This cable is commonly available from many distributors and is inexpensive. Typically the Crestron or AMX control system is programmed to close relays and that interface with the controller module. This interface control method is often referred to as contact closure, and, as the diagram illustrates, is pretty simple to understand and troubleshoot.
Connecting AC power to the screen and controller module is nothing special involving just standard AC electrical connection techniques. Experienced installers will have no trouble with this part but do-it-yourselfers may want to leave this step of the installation to a licensed electrician.
After the screen is fully installed and wired, one goes about the procedure of adjusting the screen for different aspect ratios. The documentation that Vutec supplies with their screen assemblies is excellent and covers this procedure in great detail. It is not complicated but requires a fair amount of time trying out different video sources (VHS, DVD, satellite, etc.) and adjusting the screen system so the masking panels are correctly aligned. Do this part at night after the kids are asleep so you dont go out of your mind with questions like why are there so many aspect ratios anyway, Daddy? and can we watch Barney in widescreen now?.