grating light valve (projector) (GLV)
Grating Light Valve (GLV) is a microsystem technology for displays and projectors developed by the US company Silicon Light Machines. Technologically, there are similarities with Digital Light Processing( DLP), with the difference that Grating Light Valves do not move micromirrors, but tiny metal strips.
In principle, Grating Light Valves work with diffraction gratings in which the light is refracted accordingly. The micrometer-small metal strips - about 5 µm wide and 20 µm long - are controlled by electrostatic fields generated by CMOS circuits mounted under the metal strips. As soon as an electrostatic field is applied, the metal strips bend, causing a different refraction of light. Light hitting the metal strips either benefits the projection via a lens system or not. In this case, the pixel remains dark. A pixel is formed by six metal bands, every second of which can be controlled.
The Grating Light Valve itself is an array of many pixels arranged side by side in a line. The number of pixels corresponds to the image resolution in vertical direction. The brightness can be varied via the switching speed of the metal bands, which allows different gradations of gray and color tones to be produced.
According to the previous description, only a single vertical line of many pixels is displayed. Only by the horizontal displacement over a scanning mirror the representation is projected over the entire representation width. As far as color representation is concerned, there are various approaches to solving this problem. For example, the colors can be generated by color filters, or as sequential color representations via differently colored lasers, or via coordinated diffraction of the reflected light.
GLV technology is characterized by high brightness and good contrast values of 3,000 :1. It has a high resolution and has the advantage that the entire GLV line can be manufactured cost-effectively in terms of production technology.