3LCD
Encyclopedia
3LCD is the name and brand of a major LCD projection
color image generation technology used in modern digital projectors. 3LCD technology was pioneered and refined by Japanese imaging company Epson in the 1980s and was first licensed for use in projectors in 1988. In January 1989, Epson launched its first 3LCD projector, the VPJ-700.
Although Epson still owns 3LCD technology, it is marketed by an affiliated organization simply named after the technology:"3LCD". The organization is a consortium of projector manufacturers that have licensed 3LCD technology to be used in their products. To date, about 40 different projector brands worldwide have adopted 3LCD technology.
According to electronics industry research company Pacific Media Associates, projectors using 3LCD technology comprised about 51% of the world's digital projector market in 2009 .
3LCD technology gets its name from the three LCD panel chips used in its image generation engine.
A projector using 3LCD technology works by first splitting the white light from the lamp into its three primary colours of red, green and blue by passing the lamp light through special dichroic filter
/ reflector assemblies called “dichroic mirrors.” Each dichroic mirror only allows specific colored wavelengths of light
to pass through while reflecting the rest away. In this way, the white light is split into its three primary color beams and each is directed toward, and subsequently through its own LCD panel.
Image Generation at the LCDs:
The three LCD panels of the projector are the elements that receive the electronic signals to create the image which is to be projected. Each pixel
on an LCD is covered by liquid crystals. By changing the electrical charge given to the liquid crystals, each pixel on an LCD can be darkened until it is totally opaque (for full black), lightened until it is totally transparent (allowing all the lamp light to pass through for full white), or shaded in varying degrees of translucence (for different shades of gray). This is similar to how a digital watch’s characters appear bold and black on its LCD when its battery is new, but start to fade gradually as its battery weakens. In this way, the brightness level on every pixel for each primary color can be very precisely controlled to produce the final pixel's specific color and brightness level required on the screen.
Color Image Recombination and Projection:
After each colored light is filtered through its individual LCD panel, the beams are recombined in a dichroic prism that forms the final image which is then reflected out through the lens.
) and to a much lesser extent, LCOS projection technology.
LCD projector
An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector...
color image generation technology used in modern digital projectors. 3LCD technology was pioneered and refined by Japanese imaging company Epson in the 1980s and was first licensed for use in projectors in 1988. In January 1989, Epson launched its first 3LCD projector, the VPJ-700.
Although Epson still owns 3LCD technology, it is marketed by an affiliated organization simply named after the technology:"3LCD". The organization is a consortium of projector manufacturers that have licensed 3LCD technology to be used in their products. To date, about 40 different projector brands worldwide have adopted 3LCD technology.
According to electronics industry research company Pacific Media Associates, projectors using 3LCD technology comprised about 51% of the world's digital projector market in 2009 .
3LCD technology gets its name from the three LCD panel chips used in its image generation engine.
How 3LCD technology works
Creating Colours from White Light:A projector using 3LCD technology works by first splitting the white light from the lamp into its three primary colours of red, green and blue by passing the lamp light through special dichroic filter
Dichroic filter
A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color of light that they...
/ reflector assemblies called “dichroic mirrors.” Each dichroic mirror only allows specific colored wavelengths of light
Dominant wavelength
In color science, the dominant wavelength and complementary wavelength are ways of describing non-spectral light mixtures in terms of the spectral light that evokes an identical perception of hue....
to pass through while reflecting the rest away. In this way, the white light is split into its three primary color beams and each is directed toward, and subsequently through its own LCD panel.
Image Generation at the LCDs:
The three LCD panels of the projector are the elements that receive the electronic signals to create the image which is to be projected. Each pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
on an LCD is covered by liquid crystals. By changing the electrical charge given to the liquid crystals, each pixel on an LCD can be darkened until it is totally opaque (for full black), lightened until it is totally transparent (allowing all the lamp light to pass through for full white), or shaded in varying degrees of translucence (for different shades of gray). This is similar to how a digital watch’s characters appear bold and black on its LCD when its battery is new, but start to fade gradually as its battery weakens. In this way, the brightness level on every pixel for each primary color can be very precisely controlled to produce the final pixel's specific color and brightness level required on the screen.
Color Image Recombination and Projection:
After each colored light is filtered through its individual LCD panel, the beams are recombined in a dichroic prism that forms the final image which is then reflected out through the lens.
Competition
For mainstream projectors, the competitors to 3LCD technology are single-chip DLP technology (developed by Texas InstrumentsTexas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
) and to a much lesser extent, LCOS projection technology.
Advantages
Proponents of 3LCD projection technology claim that it has the following advantages over it closest competing technologies:- 3LCD projectors are able to produce brighter colors compared to those using single-chip DLP technology. This is because 3LCD projectors mix and project the light beams from all three colours to form each individual pixel's color, while single-chip DLP projectors create colors by projecting them in sequence one at a time and rely on human color perception to mix and interpret the correct colors for each pixel.
- The way a single-chip DLP projector works sometimes causes viewers to see a "rainbow" or "color breakup" effect where false colors are briefly perceived when either the image or the observer's eye is in motion. As all three primary colors are displayed all the time by 3LCD projectors, they do not suffer from this effect.
- 3LCD projectors are able to display finer image gradations by giving each pixel on the projected image a smooth variation in brightness levels. This is because the liquid crystals for each pixel on an LCD panel can be given fine levels of opacity by varying the electrical charge. On the other hand, a single-chip DLP projector has a single mirror reflecting the lamp light to the lens on its DMD chip for each pixel. It varies the brightness of each pixel by vibrating the mirror between its on or off state in varying frequencies and relies on human perception to interpret the brightness of each pixel.
- 3LCD projectors typically use less power compared to a single-chip DLP projectors of the same brightness rating.
- 3LCD projectors are typically more affordable than those using LCOS or 3-chip DLP technologies.
Disadvantages
- Older 3LCD projectors with large pixel pitches usually have a "screen doorScreen-door effectThe screen-door effect or fixed-pattern noise is a visual artifact of the projection technology used in digital projectors, where the fine lines separating the projector's pixels become visible in the projected image...
" effect - 3LCD projectors are typically more costly than single-chip DLP ones of similar specifications.
- Single-chip DLP projectors typically have higher contrast ratios compared to older 3LCD models of similar price or brightness rating.
- The LCD panels and dichroic mirrors in 3LCD projectors may degrade with time, causing color shifts, unevenness of illumination, and reduction of contrast. The single DMD chip in single-chip DLP projectors tend to have a longer life span.
- The smallest single-chip DLP projectors are smaller than the smallest 3LCD projector models.
- Current LCOS projector models typically deliver sharper images at higher resolutions than 3LCD projectors.
External links
- 3LCD web site
- 3LCD demo video
- Internal structure of a 3LCD projector
- 3LCD technology explanation and brief history on Epson web site
- A Comparison of 3LCD and DLP projection technologies by projector review and information web site, ProjectorCentral.com
- How Single-chip DLP technology (3LCD technology's closest competitor) works