Digital projection systems are often referred to as “LCD projectors” even when they're not actually using LCD technology. There are two main types of machines for projecting computer images onto a screen: LCD projectors and DLP projectors. Though not substantial, the differences between these technologies are important to recognize when comparing similarly priced models.

LCD (Liquid Crystal Display)
LCD projectors operate by shining light through transparent LCD cells. In older thin film transistor (TFT) displays, transistors controlled each cell, changing their polarity to produce the appropriate color. More common now are advanced polysilicon LCDs, which use three separate color panels (red, green, and blue) to produce the desired color. In both types, the combination of light shining through the LCD cells produces the desired image.

DLP (Digital Light Processing)
Developed by Texas Instruments in 1996, DLP projection systems produce images by reflecting light against hundreds of tiny mirrors known as digital micromirror devices (DMD). Each mirror, representing one pixel, is individually powered by electronics that adjust the angle of the mirror according to the color being displayed. That, along with the fact they are leading the weight loss trend in the projector market, makes them very appealing for presentations. DLP projectors also handle video images extremely well.

LCD vs. DLP
There is no easy answer to this question of what type of technology to purchase. LCD projections systems tend to produce more highly saturated colors and sharper images, while some DLP projectors offer deeper blacks and higher contrast. Depending on the resolution and size of your image, you may find LCD screens too pixilated, meaning that you notice each individual point of light. However if you tend to display very detailed images, you may find the softness of DLP projectors to be a problem.

DLP projection systems were initially more expensive than similar LCD models, but that difference has largely disappeared. We recommend that you compare two projectors with the same brightness and resolution to see which type of projection is best for you.

LCOS projectors
Liquid crystal on silicon (LCOS) technology uses liquid crystals to control the path of light to micro mirrors. By combining elements of DLP and LCD projectors, LCOS projectors are able to create very high-resolution images with excellent color saturation.