Welcome, class, to Projector Anatomy 201. To get the most out of this short course, you should be familiar with the basic facts about projectors––what they do and where you can use them. If you’re not, please attend the introductory Projector Basics class down the hallway.

In order to explain the topic adequately, we will be splitting an archetypal digital projector from stem to sternum (so to speak). We’ll talk about each of the major “organ” systems in detail, as we delve into its inner structure. Those of you who actually own projectors may find this process a little disturbing. That’s entirely natural––you’ve come to think of your projector as a reliable friend, bringing you laughs, tears, and thrills in equal measure. But it exists only as a conduit for the moving picture––what you should ultimately care most about.

You have no doubt noticed that digital projectors come in many shapes and sizes. New variations appear every year, and on occasion, an entirely new species is discovered. Most are small and compact, but some challenge CRT projectors in massiveness. Despite these obvious outward differences, they all share the same fundamental structure and work in the same basic way. As we explore the anatomy of this creature, we will go into more detail, where significant differences do in fact exist.

KNEE BONE'S CONNECTED...
A projector has only one purpose in life––to expel light focused into an image onto a diffusely reflective external surface (the screen). In order to do that, it needs to be fed, at a minimum, a video signal (or signals) and power. Most of its internal structure is devoted to processing the video signals and making use of the power to, primarily, produce light. It takes many “organs” or systems to do this, and they must be adequately supported and interconnected.

We can see this structure by removing the projector’s “skins” or covers. In some species, these are made of metal, typically aluminum or, where weight is very important, a magnesium alloy. Many species use plastic, often coated on the inside surface with a copper spray to suppress radiation of radio frequencies (required by the FCC). The styling of projector skins has evolved to make them desirable to human beings, a classic example of selective adaptation. But the covers are more than cosmetic––they ensure that the cooling system directs air where it belongs; more about that later. Inside the skins, there is a metal frame that mechanically supports the major components like a skeleton. Between the components, a multitude of harnesses connect them together, spreading like arteries and veins in a biological organism.

Digital projectors typically contain very little empty space; they are no larger than needed. While this can make them look very complicated, we can make sense of their structure by examining each of the major systems in turn. Let’s begin where the video signals enter the projector.

continue