GLOSSARY

The DMD chip (Digital Micromirror Device) is an impressive chip which was developed in 1987 by Dr. Larry Hornbeck (TI) and is registered under the brand DLP. It contains an unbelievably large number of micro-mirrors – almost a type of "micro-mirror field" – which act as light switches. They reflect the light of the projection lamp. The size of the micro-mirrors is about 14 micrometres and they are capable of see-sawing within about 16 microseconds. The see-sawing is caused by the effect of electrostatic fields.


The mirrors are tilted about 10 degrees in both directions. Under the mirror is a memory cell which is directed in one of the two directions depending on the current charge. The longer the mirror reflects the light, the higher the brightness. The image becomes darker when the opposite occurs and the light is only reflected for a short period of time.


A tiny piece of the micro-mirror field. Each mirror is 5 times smaller than a human hair. ( Photo: Texas Instruments)

Because of the low level of control on the light, which is directed using a special lense, the contrast values of 2,500:1 and more are convincing. One of the manufacturer’s main targets is to reduce scattered light in order to achieve even higher contrast values.



DMD chips are largely used for DLP projectors and back projection screens. However, DMD chips also play a role in 3D displays, scientific, medical and industrial applications such as the marking out of watermarks, engraving or security in the form of scanning faces.