Projectors - The Basics
For really large screen sizes, at a more affordable price point, and to achieve the big cinema / theater experience, the front projection system is the way to go. The two main components of the front projection system consists of a video projector and a screen.
NOTE of CAUTION: You should always survey your room before buying the projector (room dimensions, projector placement, screen placement, ambient light, etc.), and always refer to projector specs (e.g. throw ratio, keystone correction, lens shift, etc...) before purchasing/mounting the screen.
Video Projectors are either of a transmissive type (LCD) or a reflective type (DLP/DMD and LCOS).
In a transmissive LCD type of projector, 3 LCD panels (red, green, and blue) produce the pixels and a lamp is used for the backlight, which shines through the panels, combined with a prism (creates single image from separate red/green/blue images), travels through optics and then projected onto the screen.
In a reflective type of projector, a lamp produces white light which is reflected off of the chip producing the pixels (DLP or LCOS chip/panel), travels through optics and then projected onto the screen. In the case of DLP (Digital Light Processing) developed by Texas Instruments, it is a DMD (Digital Micromirror Device), in which a color wheel is used to produce red, green, and blue from the white light lamp which then reflects off of the micro-mirrors through the optics and onto the screen. (In high-end/expensive DLP projectors 3 DLP chips are used, one each for red, green, and blue, in which case a color wheel is not required). An LCOS (Liquid Crystal on Silicon) projector is similar to DLP, with the pixels being produced by light reflecting off of the liquid crystal pixels.
- LCD HD Projectors
LCD (Liquid Crystal Display) Projectors - The LCD projector uses the liquid crystal substance to create the pixels (RGB - red, green, and blue) that make up the picture. The projector has three LCD panels which separately reproduce the red/green/blue pixels, a lamp for backlighting, and a prism for combining the separate red/green/blue images into a single image. The backlight is what provides the brightness for the projector and allows you to see the pixels.
Pros:
- Good price/performance in HD projector market
- Brightness (higher brightness than DLP)
- No "rainbow" artifacts (see DLP below)
- Lower power
- Typically more adaptable to variations in throw distances and angles
Cons:
- Susceptible to dust video artifact (dust can get in the system and appear on the screen)
- "Screen Door" effect (pixilation)
- DLP HD Projectors
DLP (Digital Light Processing) projectors uses micro-mirrors to create the pixels (RGB - red, green, and blue) that make up the picture. DLP projectors typically use one DLP chip (high-end/expensive units use three), an RGB color wheel spins to separately create red, green, and blue images.
Pros:
- Higher contrast ratio (deeper black levels) than LCD
Cons: - LCOS HD Projectors
LCOS (Liquid Crystal on Silicon) is similar to DLP, however uses liquid crystal on silicon to create the reflective points for each pixel. Also, typically uses 3 LCOS panels (vs. single panel / color wheel system).
Pros:
- Higher Contrast Ratio (producing deeper blacks)
- Three panel LCOS projectors at reasonable cost points.
Cons:
- Higher Power (higher power consumption than LCD)
- Brightness (typically not as bright as LCD)
- "Rainbow effect"
- Higher Power (higher power consumption than LCD)
- Brightness (typically not as bright as LCD)
