Projectors: What Are They?

The best projectors play movies, games, sports and much more.

In the simplest terms, a projector is a device which uses a series of chips, lenses, color wheels and various other gadgets and gizmos to take a beam of light and turn it into our favorite movies and TV shows in glorious high definition detail.

Many of us use a home theatre projector, but how do they work?

It wasn’t always like that, though. The consumer projectors of today barely even resemble the original concept, invented in 1894 by Charles Francis Jenkins. These original models worked by blasting light through celluloid film, and stringing together the images and sounds using techniques that seem downright primitive by now.

Modern projectors are considerably more complex both in design and implementation, utilizing several different core technologies to provide a range of options to the prospective buyer.

Related: 5 of the Best Home Theater Projectors for 2018

How Do Home Projectors Work?

So how do projectors work?

Well, before we can explain how a projector does what it does, it’s imperative first to know the three major types of home theater projectors you’ll find on shelves in 2018. First there are LCD (liquid crystal display) projectors, which use polarized light shone through three liquid crystal panels (one for each primary color), a prism, a lamp, and a filter to create your image, which then is “projected” (hence the name), through the lens.

how does an lcd-projector work
The inside of an LCD projector.

In a LCD projector, the first panel displays the image, which is split up into its primary colors through a series of dichroic mirrors. Once the light is separated, it’s then passed through another LCD panel (second of three), which recombines the colors by separating the light into a spectra depending on what you want reflected and what’s allowed to get through. Each panel shines a different color; either red green or blue, and sends them the through the final LCD panel which bends the light depending on the level of electrical current.

Finally, the last dichroic mirror combines the red, green, and blue images into the complete picture, which is magnified by a the onboard lens and shone onto your home theater’s screen.

DLP, or Digital Light Processing projectors on the other hand rely on what’s known as a DMD chip. These “Digital Micromirror Devices” string together millions of tiny little mirrors on a single chip, each measuring less than a 1/5th of a human hair across.

Working in unison, DMD chips use the mosaic effect to display one color on each mirror, which got there after being shone through through a rapidly spinning color wheel which alternates between all three. Each mirror represents one pixel (over 2 millions mirrors on a 1920 x 1080 projector, for example). If viewed up close wouldn’t look like anything, but once viewed from far away (or magnified by a giant lens), they create a complete picture of what you’re supposed to be looking at.

Related: Optoma HD28DSE Projector Review

Last, there’s LCoS, the newest of the bunch. Short for Liquid Crystal on Silicon, this technology is both the most expensive and most complex style of projector to manufacture. So complex, in fact, explaining how it actually works takes up a couple thousand words on its own, but for the sake of this guide we’ll break it down to the basics.

  1. It’s sort of a hybrid between DLP DMD and 3-chip LCD technology
  2. Many owners agree that the color reproduction and clarity on LCoS projectors is far superior to that of either of its predecessors
  3. That said, it can also suffer from motion blur issues where DLP might otherwise not.

What Does “Throw” Mean?

No matter how the image gets created in the projector, all three styles inevitably push light through a lens as the final part of its journey.

How far the light has to go in order to create a certain sized image is called the “throw” distance, separated into three categories: short-throw, long-throw, and extra short-throw.

Most projectors you’ll find out there use a long-throw lens, which is smaller and creates a narrower depth of field in its image. This means you can use it to create larger images, but you need a lot of available distance between the screen or wall in order to get there.

Short Throw vs. Long Throw
The shorter the “throw” of a lens, the less distance the light has to travel to create the same size image.

Short-throw lenses are larger and create a shallow depth of field, which means you can replicate the same size image often from only half the distance as a long throw.

Lastly there are ultra short-throw projectors. These models are considerably more expensive, but can also display images upwards of 100″ across from less than a foot and a half away. If you’re in a box-sized apartment or just want to set up an epic pillow fort, the increased cost (expect to spend no less than $1,000 for an ultra short-throw) might be worth it, but otherwise you’re better off going with a regular short-throw instead.

Related: Short Throw vs. Long Throw: What’s the Difference?

LCD vs. DLP vs. LCoS

Like any home theater product, whether it’s an LCD, DLP, or LCoS projector, there are going to be benefits and drawbacks to using each particular technology. Some are more expensive than others, and have different optimal use scenarios depending on the type of media you consume most.

If you’re a gamer and need the fastest response times possible, LCoS projectors will blow the competition clean out of the water. If you’re more interested in richer colors on a budget, DLP is a good choice, while LCD projectors can be brighter than the sun if you really start to crank up the lumens.

Wrap Up

Projector technology has come a long way since Charles Francis Jenkins first gathered his friends and family around the first projector over a century ago, but this method of movie-enjoyment is still one of the best ways you can get the full-sized theater experience from the comfort of your own couch.

Inch-for-inch, all projectors are still a bargain compared to what you’d pay for a LED or plasma screen of a similar size. As long as you’ve got the room to set them up, projectors can be one of the best (and most bombastic) ways to enjoy your favorite Hollywood blockbusters at home.

Chris Stobing

Chris Stobing is a writer and blogger from the heart of Silicon Valley. Raised around tech from birth, he's had an interest in PC hardware and networking technology for years, and has come to Gadget Review to contribute his knowledge on both.

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