With video projectors, we are witnessing a clash of clans worthy of Star Wars or Lord of the Rings saga.  On the one side, we have products based on DLP technology and on the other there are the LCDs.  The two differ in their functioning and rendering.  DLP fans prefer its depth in black colors and the total absence of afterglow.  And those who favor LCDs like the larger images (from the same distance) and are sensitive to the rainbow effect of DLPs (instead of assimilating colors some users will see occasional flashes of red, green and blue).  Seen from the inside of these devices, here are the differences :

DLP : Digital Light Processing. This system is based on three elements : a light source, color wheel, and DMD (Digital Micromirror Device) chip.  The color wheel is divided into three colors (red, green and blue) and by spinning it divides the white light of the lamp.  These color fragments are then reflected by mirrors on the DMD chip, whose position varies by +/- 10% towards the projection lens.  Your eye then reconstructs the colors of the final image by fusing all of the colors reflected by the mirrors.  For example, when these mirrors rapidly reflect red and yellow, you will see green.  The number of mirrors in the chip is equal to the resolution of the projector.  For example, a resolution of 1280 x 720 equals 921,600 mirrors.

LCD: Liquid Crystal Display. This system is comprised of a lamp, two prisms and three LCD panels.  The first prism is in charge of separating the light the lamp emits into the three components of red, green and blue.  Thanks to a series of mirrors, light rays each hit an LCD panel which depending on the position of its cells may or may not let the light through.  A last prism placed between the panels recombines the three light beams and sends the image through a projection lens.

The lamp issue

Projectors have one consumable that needs to be replaced, the lamp.  After an average of 2,000 hours, it has to be changed and this can cost between 200 to 600 €.   2,000 hours doesn’t seem like much, but if we calculate three (2 hour)  movies per week, this means replacement once every six years.  If you are a real gaming buff and want to connect your game console, daily use of two hours will result in changing a new lamp after three years.   After that, for the daily news or your favorite television series, having a normal TV on hand is a good idea.