Projector Technology Explained Part I

Over the last few years, projection technology has exploded! From the early days of CRT projectors using similar tubes to those in televisions and generating 100 lumens, to projectors that can cover the face of a building, the advances have never stopped coming. Today’s market has a variety of technologies, and most people are still trying to figure out what it is that they are shopping for when they look at the options. In the next few posts I will give a quick run-down of the differences, and what to consider when choosing a projector.

Please keep in mind that this is not an exhaustive discussion of the details, but more an overview to give the average person an understanding of the basics of the technology.

First off, consider the environment. A dark room is very different from a room with full sunlight and the projector will have to be selected to handle that difference. The brighter the room, the brighter the projected image you will need to compete with that light. If you simply shop for price you are going to be very unhappy in the end, if the projector can’t handle the brightness of the space. A screen with direct sunlight is not going to compete no matter what projector you put on that screen. Shadows across the screen will also create a distraction, so having a dimmer area with even lighting (or darkness) over the screen will always yield your best results.

Next, consider your resolution. For those who are not aware of what all of those number refer to, every video image is made up of tiny dots called pixels. When a manufacturer lists resolution they are referring to the number of pixels. These counts are shown by the number of rows and columns. That means that a video image that is listed as 1024×768 will have 1,024 columns and 768 rows. This concept stays the same no matter how large or small the numbers become.

There is a never ending stream of these number combinations that keep coming to the market, but one of the things to watch is the aspect ratio. This is another method of communicating the resolution, but is more a reference to how many units wide, compared to how many units high. So if your TV screen is 16” wide, it will also be 9” high. The irony of this is that many manufacturers (especially with TVs) refer to the diagonal measurement from top corner to the opposite bottom corner, rather than to the actual horizontal and vertical dimensions. With most equipment you can still look into the specifications and find the actual height and width, but since consumers like simplicity they are sold by diagonal measurement.

If you go shopping for a TV today you are likely to only find 16:9 models at your local store. The older technology of 4×3 has all but vanished from the consumer market, but projectors are still sold in 4:3 as well as other aspect ratios. The 4:3 projectors are typically cheaper, but remember that if you buy a 4:3 projector and send it a 16:9 signal then the available image space is going to be cropped to meet the actual image. What this equates to is the loss of the use of pixels, affecting the actual displayed revolution as well as the brightness. The same is true if you send a 4:3 signal to a 16:9 projector, so the best results that will result in the best bang for your buck is going to come from a projector that matches the signal that you are going to use and the aspect ratio of your screen.

In the next few posts I will explain more about resolution and aspect ratio, and how those relate to formats such as XGA, WXGA or HD formats. We will also discuss the differences in how these images are projected, and how blended image technology has expanded the ability to create even wider or taller images by combining projected images.