How do projectors work?

If you have ever gone to the cinema to watch a movie, you must have marvelled at the appealing image that a projector can produce. But how is a projector able to deliver such a high-quality display?

A projector processes the input image/video and uses an inbuilt system to provide an enhanced output on a big screen. Generally, the costlier the projector, the better its output.

There are many different projectors with varying prices, image qualities, display sizes, and more. Understanding how projectors work is helpful when shopping for your dream projector.

Our guide will walk you through everything you need to know about the working principles of all sorts of projectors in the market. So, let’s begin!

What is a projector?

A projector is an optical device that projects an image onto a surface by shining light through a lens or laser. This surface could be a wall, a white sheet, or, preferably, a projection screen.

This definition explains the core of a projector and how it works. There are many types of projectors, like LCD, LED, DLP, etc., and each one functions differently. But the fundamental principle is the same: light is passed through a lens or a laser to display an image on a surface.

Let’s look at the different projectors, including how they work and what sets one apart from the other.

Types of projectors

Five different technologies are featured in projectors, namely LCD, DLP, LCoS, laser, and LED. These five technologies have further subdivisions. Below, we have taken a rundown of each one of them.

LCD

Liquid Crystal Display (LCD) is the oldest projector technology still in use.

LCD projectors consist of three panels, each of which is made up of liquid crystal and glass. These projectors have three regular mirrors and two dichroic mirrors as well.

When you turn on the projector to say, watch a movie, light passes through the dichroic mirrors and splits into the following colours: red, green, and blue.

The colours mentioned above are reflected into separate LCD panels to form a single, colourful image on the projection screen.

DLP

Digital Light Processing (DLP) is relatively newer in town. They are based on digital micromirror devices (DMD).

A DMD is a chip containing nearly 2 million tiny mirrors. The electric circuit decides the orientation of each mirror. The higher the number of tiny mirrors in a chip, the higher the pixels.

So, what happens is that the colour wheel causes the incoming white light to split into red, blue, and green, or RGB light, after which the split light is reflected onto the tiny mirrors in the chip.

The tiny mirrors, then, in a fraction of a second, blend the colours according to the video source data and pass it through the lens to project the image onto the screen.

DLP projectors come in two variants: 1-chip DLP and 3 Chip DLP.

1 Chip DLP

1-chip DLP projectors are typically purchased for home use. They process the RGB light sequentially, one after the other, using a high-speed rotating colour wheel.

3 Chip DLP

Unlike their 1-chip counterparts, these projectors process individual beams of RGB light simultaneously and produce high-quality, bright images.

3 chip DLP projectors are ideal for streaming movies in cinema theatres.

LCOS

Liquid Crystal on Silicon (LCoS) is the latest projector technology into the market. Designed with silicon, these projectors are a blend of LCD and DLP projectors.

LCoS projectors work by splitting a beam of light into red, blue, and green using dichroic mirrors. The split light is then passed through various filters before it reaches a microdevice.

Here, the filtered lights are merged through a prism and shown onto the screen through a lens.

D-ILA

A Digital Direct Drive – Image Light Amplifier (D-ILA) projector is a variation of LCoS.

D-ILA is a reflective technology that allows the splitting of light into three primary colours, which are then reflected off an LCD panel with a reflective layer. This means a colour wheel is unnecessary; thus, rainbow artefacts, such as in the case of 1 chip DLP, are avoided.

The reflective nature of this technology also has another benefit: the gaps between pixels are not that obvious.

Furthermore, the light path in these projectors is completely sealed, so there are no dust blobs either.

SXRD

Silicon X-Tal Reflective Display (SXRD) is another variation of LCoS.

Similar to D-ILA, SXRD is naturally reflective, so it enjoys related benefits, such as no rainbow artefacts and dust blobs.

However, in the case of this technology, blacks are not as good as D-ILA.

Laser

As the name suggests, laser projectors use a laser as a light source to produce an image.

What happens is that the light source is deflected off of a chip, and then magnified and focused by lenses to project an image on your screen. Unlike a standard projector, this projector uses laser light in primary colours, producing less wasted light. There are three lasers, one for each primary colour.

RGB

RGB projector, also called direct laser projector, is a type of laser projector.

It uses a laser of each primary colour – red, green, and blue – and combines them in different proportions to reproduce millions of shades and hues. The output is mixed, processed by the projector’s DMD, and finally passed through the lens to be displayed on the screen as an image.

Laser Phosphor

Unlike RGB, a laser phosphor projector uses only one of three primary colours, mostly blue. The choice of blue colour can be attributed to the high density, power efficiency, as well as cost-effectiveness of this colour.

The blue light from the laser shines onto a spinning yellow phosphor wheel. The phosphor absorbs the blue light and radiates a bright yellow light. This yellow light is then captured and split into primary colours using a colour wheel. These primary colours can then be used to produce the coloured images on the screen.

RB Laser

RB laser is another type of laser projector.

These projectors are a cheaper alternative to RGB projectors and generally offer a better colour gamut coverage than laser phosphor projectors.

An RB laser projector contains an auto-brightness control that adjusts power as the projector ages; thus, a constant brightness is maintained throughout the projector’s life.

LED

LED projectors use light-emitting diodes (LED) instead of traditional lamps to produce light.

Unlike lamp-based projectors, an LED projector uses a combination of red, green and blue LED bulbs to create a white light which is then filtered through the lens to produce an image on the screen.

These projectors have lower power consumption, deliver better colours, and generate less heat than LCD and DLP projectors. On top of that, they have almost zero maintenance costs.

However, LED projectors have limited brightness, so they are not recommended if your surroundings have a lot of ambient light.

Frequently Asked Questions

Why use a projector instead of a TV?

There are various reasons why one should choose a projector over a TV.

For one, a projector reflects light while a TV emits light and reflected light is more comfortable for viewing. Similarly, the larger images produced by projectors are less straining to the eyes.

Is buying a projector worth it?

Yes, it is worth it. A projector gives you a much larger image size for less money. A larger size is best suited to you if you want to watch 4K content.

Can you watch TV on a projector?

Yes, you can surely use your projector for your everyday TV watching. It may lead to a much better experience than most larger TVs at a lower price.

Summary

To sum it all up, different projectors work in different ways. What matters is your preference and how much you can pay.

Lamp-based projectors, like LCDs and DLPs, are most widely used worldwide, but if you have some money to play with and want a more durable and eco-friendly projector, laser or LED projectors are your go-to options.