LCD Video Projector Basics

3LCD Video Projector Technology Illustration
3LCD Video Projector Technology Illustration. Images provided by 3LCD and Robert Silva

What LCD Technology Is

LCD stands for "Liquid Crystal Display". LCD technology has been with us for several decades and is used in a variety video display applications, including panel displays on electronic instruments and consumer electronics devices, as well as digital signage. Perhaps the most familiar use to consumers is there use in TVs.

In TVs, LCD chips are arranged across a screen surface, and using a backlight (most common type is LED), LCD TVs are able to display images.

Depending on the TV's display resolution, the number of LCD chips used can number in the millions (each LCD chip represents a pixel).

LCD Use In Video Projection

However, in addition to TVs, LCD Technology is used in many video projectors. However, instead of a large number of LCD chips placed across a screen surface, a video projector utilizes 3 specially designed LCD Chips to create and project images on an external screen. The three LCD chips each contain the same number of pixels that equals the display resolution of the projector.


One type of LCD video projection technology use in video projectors is referred to as 3LCD (not to be confused with 3D).

In this method, a light source (usually a lamp) sends out white light into a 3-Dichroic Mirror assembly that splits the white light into separate red, green, and blue light beams, which in turn, pass through an LCD chip assembly that consists of three chips (one designated for each primary color).

The three colors are then combined using a prism, passed through a lens assembly and then projected onto a screen or wall.

3LCD Variants: LCOS, SXRD, and D-ILA

Although 3LCD technology is one of the most commonly used technology used in used video projectors (along with DLP), there are some LCD-based variants.

LCOS(Liquid Crystal on Silicon), D-ILA (Digital Imaging Light Amplification - used by JVC), and SXRD (Silicon Crystal Reflective Display - used by Sony), combine some of the characteristics of both 3LCD and DLP technology.

What all three variants have in common is that instead of light passing through the LCD chips to create images as in 3LCD technology, light is actually bounced off the surface of the LCD chips to create images. As a result, when it come to the light path, LCOS/SXRD/D-ILA are referred to as "reflective" technologies, whereas 3LCD is referred to as a "transmissive" technology.

3LCD/LCOS Advantages

One of the key advantages of the LCD/LCOS family of video projection technologies is that both white and color output capability is the same. This contrasts with DLP technology which, although has the capability of producing excellent color and black levels, cannot output both white and color light at the same level in cases where the projector utilizes a color wheel.

In most DLP projectors (especially for home use) the white light has to pass through a color wheel that contains Red, Green, and Blue segments, which reduces the amount of light coming out the other end. On the other hand, DLP projectors that utilize non-color wheel technology (such as LED or Laser/LED Hybrid light sources or 3-chip models) can produce the same level of white and color output.

For more details, read my article: Video Projectors and Color Brightness

LCD/LCOS Disadvantages

An LCD projector can often times exhibit what is called "the screen door effect"". Since the screen is made up of individual pixels, the pixels can be visible on a large screen, thus giving the appearance of viewing the image through a "screen door".

The reason for this is that the pixels are separated by black (non-lit) borders. As you increase the size of the projected image (or decrease the resolution on same size screen) the individual pixel borders are more likely to become visible, thus giving the appearance of viewing the image through a "screen door". To eliminate this effect, manufacturers use various technologies to decrease the visibility of the non-lit pixel borders.

On the other hand, for LCD-based video projectors that have high-resolution display capability (1080p or higher) this effect is not visible, since the pixels are smaller and the borders thinner, unless you are very close to the screen, and the screen is very large.

Another issue that can come up (although very rarely) is Pixel burnout. Since an LCD chip is made up of a panel of individual pixels, if one pixel burns out it displays an annoying black or white dot on the projected image. Individual pixels cannot be repaired, if one or more pixels burn out, the entire chip has to be replaced.

More Info

Examples of LCD-based video projectors for home theater use include:

Epson Home Cinema 2045 3LCD Video Projector - Buy From Amazon

Sony VPL-HW45ES SXRD Video Projector - Buy From Amazon

For more suggestions, check out our listing of Best LCD Video Projectors and The 5 Best Cheap Video Projectors (includes both DLP and LCD types).

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