Video Projector

• A video projector takes a video signal and projects the corresponding image on a projection screen using a lens system.
• • All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other inconsistencies through manual settings.
• • Video projectors are widely used for conference room presentations, classroom training, and home theatre applications.
• • Common display resolutions for a portable projector include SVGA (800×600 pixels), XGA (1024×768 pixels), 720p (1280×720 pixels), and 1080p (1920×1080 pixels
• Projection technologies
• • CRT projector using cathode ray tubes. This typically involves a blue, a green, and a red tube. Minimal maintenance is required (unlike projectors that use expensive lamps which must be periodically replaced after they burn out). This is the oldest system and falling out of favor largely because of the bulky cabinet. However, it does provide the largest screen size for a given cost. This also covers three tube home models, which, while bulky, can be moved
• • LCD projector[3] using LCD light gates. This is the simplest system, making it one of the most common and affordable for home theaters and business use. Its most common problem is a visible “screen door” or pixelation effect, although recent advances have minimized this.
• • DLP projector using Texas Instruments’ DLP technology. This uses one, two, or three microfabricated light valves called digital micromirror devices (DMDs). The single- and double-DMD versions use rotating color wheels in time with the mirror refreshes to modulate color. The most common problem with the single- or two-DMD varieties is a visible “rainbow” which some people perceive when moving their eyes. More recent projectors with higher speed (2x or 4x) and otherwise optimised color wheels have lessened this artifact. Systems with 3 DMDs never have this problem, as they display each primary color simultaneously.
• • LCOS projector using Liquid crystal on silicon.
• • D-ILA JVC’s Direct-drive Image Light Amplifier based on LCOS technology.
• • LED Use an array of Light Emitting Diodes as the light source, negating the need for lamp replacement.