How does a projector work? Easily explained

With a projector, you can project high-resolution images on the wall in large format. But how does a projector actually work? We explain how the image of a projector is created.

This is how an LCD projector works

Nowadays, DLP and LCD projectors in particular can be found on the market. The two models differ in how they work. You can find out how an LCD projector works in the following points.

• LCD means "liquid crystal display". With this technique, the image is composed of light rays of different colors.
• Light rays in the colors red, blue and green are thrown from a lamp onto a mirror system.
• The individual mirrors are translucent at individual points. So the three colors are directed in one direction.
• Each of the three beams of light next goes through small LCD displays that work like a slide. With their liquid crystals, they only let light through where the respective color is needed.
• The filtered light rays now meet mirrors that bundle all three colors into an image that is projected onto the wall through the lens.

How the DLP projector works

• DLP stands for Digital Light Processing. In DLP projectors, colorless light is colored through a filter.
• The light is projected from the lamp onto a rotating "color wheel". This color wheel is round and tart-shaped in different colors (blue, red, green).
• The colored light beam hits a DMD chip. This chip is provided with many tiny and movable mirrors. With each color change due to the rotating color wheel, the mirrors are aligned so that the colored light is directed to the desired location.
• Thanks to the rapid color changes, the brain assembles the colors that are actually projected one after the other into an image.

Projector technology: advantages and disadvantages of the two technologies

Both projector technologies have their advantages and disadvantages.

• With LCD technology, colors can be graded from light to dark by controlling the light transmission of the LCD displays. This creates an image with finely graded color transitions.
• The disadvantage of the technology is that LCDs cannot be rotated completely without light. This is where DLP projectors score, because the mirror technology can generate a higher contrast.
• The disadvantage of the DLP technology is the so-called rainbow effect: Since the colors are not projected at the same time, but one after the other, the three primary colors can flash in the eye of the beholder when the image moves - i.e. in videos.
• LCD projectors are therefore more suitable for moving pictures than DLP devices. The DLP projectors are more suitable for presentations with rich contrasts or for slideshows.