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How does a projector work?

Projectors have begun to replace home TVs for quite some time. But so far, they are far from so common. Both because of the high cost and because of the more complex installation process. And also because of the need to create specific lighting conditions for them. But if you want to get a picture with a large diagonal, you will have to spend much more on a TV.

In this article, we’ll walk you through how the most popular types of projectors (DLP, LCD, and LED) work. And then give you some helpful tips for choosing the type of projector that’s right for you.

In short:

-DLP technology (Digital Light Processing) for projection of an image on a large screen uses a tiny “monitor” and a lot of micromirrors;

 -LCD technology (Liquid Crystal Display) – technology of light output from metal halide lamps through a specific prism;

 -LED technology (Light Emitting Diode) is similar to LCD. But instead of lamps, organic light-emitting diodes are used here.

How different types of projectors work

DLP Projectors

The primary part of any DLP projector is its DLP chip, also called DMD (Digital Micromirror Device). It consists of several microscopic mirrors (up to millions), the thickness of which can be as little as a fifth of the thickness of a human hair.

Each of these mirrors is electronically controlled and can independently approach or move away from the light source. That is how bright or dark pixels appear in a picture.

The colored light DMD receives from a lamp in the projector. It passes through a very fast rotating wheel with red, green, and blue sections. In the end, light is passed through the lens and eventually hits the projection screen.

A DLP projector with three chips can display up to 35 trillion (!) Different shades – much more than the human eye can discern. In such a projector, the light from the lamp is separated by a prism. And each color is passed through a separate DLP chip. Then the three parts of the picture are combined and fed to the lens.

DLP models with three chips use in high-end home theater projectors, commercial projectors, and general cinema projectors.

The most commonly used light source in DLP projectors is xenon arc lamps with high internal gas pressure. High-power LEDs and lasers use in compact models.

LCD projectors

At the heart of LCD projectors are essentially the same LCD displays used in televisions or computer monitors. The system combines three liquid crystal screens, and the picture is created in several stages. The source emits white light that passes through three specially shaped mirrors that only reflect waves in specific wavelength ranges.

Here, these mirrors reflect red, blue, and green light. Each of the three colors is then fed to the LCD panel, which, in turn, receives an electrical current and displays the pixels to create a picture.

Finally, the picture combines in a prism, and through the lens enters the projection screen. Such projectors can provide a display of 16.7 million different shades – noticeably less than top-end DLPs. But for home viewing of movies and TV shows, this, in general, is not critical.

The light source in LCD models is usually metal halide lamps. It has an ideal color temperature and Wide Spectrum. They are also relatively small.

LED projectors

The main difference between LED projectors from DLP and LCD is the type of light source. Instead of traditional lamps, they use a combination of three Powerful red, green and blue LEDs.

Thanks to LEDs, these projectors consume much less energy and do not heat up too much. LEDs also take up much less space than metal halide or xenon lamps, so LED projectors are usually smaller than their DLP and LCD counterparts.

The rest of the LED models work the same way – the light from their LEDs either hits the DLP chip or passes through the LCD screens. Precision LED allows for near-perfect white light reproduction.

Quick Tips for Choosing a Projector Type

DLP benefits

-Portability: DLP models are often small in size and easy to transport than 3LCD. DLP with LEDs or lasers are even more convenient to carry and can often connect to mobile devices;

-Higher contrast: scenes with dark areas DLP-projector will display better than LCD, and the movie looks more impressive on it;

-Less noticeable pixels: from a regular distance, it will be more difficult to distinguish individual points in an image supplied from a DLP projector;

-Reliability: DLP has fewer parts in the structure, and in which case, it is easier to repair them. And in dusty rooms, they will last longer.

Disadvantages of DLP

-Rainbow effect: in old DLP and entry-level DLP projectors, multi-colored moire may appear in the picture if you look away from it or look at it from a certain angle. This effect can also be observed around bright objects in the scene;

-Light leakage: gray picture borders can lead to excess light. It is reflected from the edges of the mirrors on the DLP chip. You can avoid it by installing black frames around the projection screen.

LCD advantages

-the best picture quality is due to accurate color reproduction. DLP models in the RGB wheel may have extra areas that reduce the saturation of the image;

 -increased sharpness: at the same resolution, the picture from the LCD projector will be slightly sharper;

 -Higher lamp efficiency: with the same power, the picture of an LCD projector will be brighter than that of DLP.

Disadvantages of LCD

– “Screen door effect” – more visible pixels and, when approaching the screen, their borders;

 -not such a high contrast;

 -big sizes;

 – The deterioration of picture quality with the use of the projector. Some parts of the structure will affect the color balance and contrast over time;

 – “dead” pixels: some dots on LCD panels inside can either turn off permanently or “get stuck” in one position, which, of course, negatively affects the image.

What about LED?

Projectors that use LEDs are more reliable and more compact than those that use bulbs. At the same time, they are more expensive, but they should also regularly serve in the same conditions of use much longer – 10 thousand hours or even more. There is no need to worry about repairing and replacing lamps.

In addition, the noticeably lower operating temperature of LED projectors prevents manufacturers from using relatively noisy cooling systems. It makes the projector itself even more compact and more enjoyable to use.

Finally, LED projectors just get started faster. They don’t need to warm up (and cool down) the lamps inside.

The main disadvantage of LEDs is not that high brightness. At the same time, at home with blackout curtains, this will not be an obstacle. In general, their price remains the main obstacle on the way to LEDs. 

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Written by HackerVibes

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