Mini projectors, also known as mini beamers, are mains-powered mini projectors measuring approximately 15 x 10 x 5 cm. Even smaller versions, the size of a cell phone or a pack of cigarettes, are called microprojectors or microbeamers and are battery-powered. Sometimes they are also called pico projectors. The smallest of them weigh only around 100 g.
The micro-projectors use the well-known projection technologies, light-emitting diodes, Digital Light Processing( DLP), micro- LED displays or Liquid Crystal on Silicon( LCoS). In addition to the well-known DLP projection technology with millions of small micro mirrors, an alternative for micro projectors is the micromechanical method with only one gimbaled micro mirror. Since this has an extremely low mass, the light beams from the three lasers with red, green and blue can be deflected line by line across the projection surface at the repetition rate of a normal television image. The light beams from the red, green and blue lasers are deflected by the micromirror and projected onto the projection surface.
If mini projectors are powered by batteries, these tiny devices can only deliver a fraction of the luminous flux of conventional projectors. Most of them have a luminous flux of 10 to 15 lumens, in contrast to the 2,000 lumens of normal projectors. With this relatively low luminous flux, a projection surface of about 1 m can be illuminated. The resolution of miniprojectors varies, for example, DLP miniprojectors working with the electronic mirror bring it to half the VGA resolution with 480 x 320 pixels, LCoS miniprojectors to the full VGA format.
Miniprojector technology is also intended for embedded use in small mobile devices. Smartphones and cell phones. This category of devices is referred to as Projector Phones. For Projector Phones there are special projector developments, which work with only one mirror, which is swiveled in two axes. This allows the projection image to be built up pixel by pixel and line by line.
Mini projectors are equipped with lithium-ion batteries and use powerful power LEDs. In battery mode, they can be operated for about 2 hours.