Projector

A projector is a device designed to render images on a screen and horizontal or vertical surfaces.

Types of projectors for digital images

LCD projector

1 - Projection lamp

2 - Condenser

3 - Lenses

4 - Display

5 - Lens

6 - Luminous flux to the screen

It is constructed like a film projector, only it has a color liquid crystal display inside, instead of film, as in modern displays.

Disadvantages: you can see pixels; the display can burn out due to the bright image.

3LCD projector

1 - Projection lamp

2 - mirrors

3 - LCD monitor

4 - Three channels prism

5 - Display

The system of mirrors divides the luminous flux into three channels (RGB), each of which appears on a different LCD panel. Then the processed light stream is merged into a single image in the three channels prism and displayed on the screen through a lens.

Although the technology is more expensive, this kind of projector no longer shows pixels, and the picture looks saturated.

Compared to an LCD projector, the 3LCD also has a higher noise level because it is necessary to cool three screens instead of one.

LCoS projector

1 - Projection lamp

2 - Mirrors

3 - LCoS panel

4 - Reflecting mirror

5 - Polarizing filters

6 - Prism

LCoS technology may also be called D-ILA, HD-ILA, and SXRD.

It is an improved technology of 3LCD, where a reflective layer has been added behind the liquid crystal layer, so light is reflected and transmitted through the liquid crystal twice upon entering into the display.

The technology has increased the contrast and clarity of the image, but these types of projectors are expensive.

DLP (Digital Light Processing) projector

1 - Projection lamp

2 - Condenser lens

3 - Color wheel

4 - Aspherical lens

5 - DLP chip

6 - lens

7 - Screen

It is called DLP because of the digital light processing. It has one DMD (Digital micromirror device) instead of three LCD screens. The display consists of millions of micromirrors. Each of these mirrors is made of aluminum alloy and can be tilted to one of two positions, differing by 20 degrees. The first position is responsible for white, the second for black. When the position of the mirrors changes rapidly, the pixels on the screen flicker, but the human eye is not able to notice the flicker of the pixels at this speed. The output image is grayed out (because of the rapid change in white and black). However, DLP projectors pass light through a special color wheel to produce a color image.

This disk rotates quickly and paints the pixels one by one.

DLP technology outputs a rich black color on the screen, no grid of pixels is visible, and the mirrors don't burn out because they don't require extensive cooling. That means they are less noisy. Also, these projectors are more compact and portable. However, DLP projectors are less bright than 3LCD projectors.

The older versions of these projectors have a disadvantage: the "rainbow" effect in dynamic and high-contrast scenes. This is related to the rotating color disk. Modern DLP projectors have an increased rotation speed, so the "rainbow" effect disappears.

Moreover, there is a technology of three-matrix DLP projectors that are not inferior to LCD projectors.