• CRT projectors using cathode ray tubes. This typically involves a blue, a green, and a red tube. Extremely high maintenance is required (unlike projectors that use lamps). Maintenance costs are very high in price. You are better off in buying a  middle of the line DLP or LCD projector for the cost of maintenance, although it is seen most often in very expensive (over $10,000) fixed systems.
   
• LCD projector 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 micro fabricated light valves called a Digital Micro mirror Device (DMD). The single and two DMD versions use rotating color wheels in time with the mirror refreshes to modulate color. The most common problem with the single or two "chip" varieties is a visible "rainbow" visible to some people when they move their eyes. Systems with 3 DMDs never have this problem. More recent projectors with higher speed (2x or 4x) and otherwise optimized color wheels have minimized this artifact.
   
• LCOS projector using Liquid crystal on silicon.
   
• D-ILA JVC's Direct-Drive Image Light Amplifier.

The current dominant technology for expensive (over $5,000) portable digital projectors is Texas Instruments' DLP technology, with LCD projectors dominating the less expensive (under $2,500) market segment. This is due mainly to the high quality of systems using 3 separate color wheels, which greatly increases the cost. DLP systems currently cannot be produced inexpensively enough to compete widely in the budget market ($800). DLP High intensity CRT devices are suitable only for fixed installations.