Nowadays beamers re used not only for presentations, demonstrations and lessons, but also as handy “multi-talents” at home, for example, instead of a TV-set. These projectors are especially handy when showing a movie on a projection screen to a small group of people. Movie-night lovers can experience a real cinema feeling.
At work or education facilities, the projectors are still used for reflecting a PC, notebook or another multimedia terminal device onto a large screen.
There are many various models and types ranging from functional high-performance stationary projectors up to mobile small gadgets for presentations or home-cinema systems.
DLP Beamer: Digital Light Processing
In the event of a DLP projector, a DMD (digital micro-mirror device) is used as an image converter. This is an integrated circuit that provides a tilting micro-mirror for each image point. The micro-mirrors are controlled by electrical pulses. The mirrors can only accept two states: ON or OFF.
Source: http://www.hcinema.de/farbrad.htm
For this kind of image formation, the brightness gradations can only be achieved by very fast switching-over of the tilting micro-mirrors.
The DMD device can project all three primary colours one by one, with the aid of a rapidly rotating colour wheel. Current DLP video projectors use six or seven colour segments in a single colour wheel. High-performance DLP projectors are still used in cinemas.
Advantages of the DLP beamers:
- High speed
- No after-glowing of the image
- No burning-in of still images
- Higher contrast than on an LCD beamer
- Almost no pixel artefacts
- Less sensitive to dust, because the optics is encapsulated
Disadvantages of the DLP beamers:
- If the colour wheel does not run fast enough, it may be a rainbow effect
- Individual colours might flicker
- Higher noise emission by the colour wheel and fan
- Optimal image resolution depends on the type of the installed mirror matrix
LED Beamer: Light Emitting Diode
In these video projectors, the image is still generated by a DLP element or, in newer models, by a LCD (Liquid Crystal Display). LEDs are used just as sources of light. In this type of beamers, the colours themselves are generated by a sequential flashing of each individual LED.
A LED beamer is an ideal solution for mobile use, for example, a visual support or illustration of a business speech. In this case, the light wave length is between 540 and 610 nanometres.
Advantages of the LED beamers:
- Higher energy efficiency
- Lighter construction, since active cooling is not a must
- Due to the low energy consumption, it can also be operated with a battery
- Noise emission is significantly lower, because there is one wheel less
Disadvantages of the LED beamers:
- LCD as an imaging device can only achieve a satisfactory pictorial quality with a fixed resolution
- The total light output is lower
- In the case of luminous flux reduction, the image continuously darkens. This loss of brightness can only be compensated by adaptive increase of current
- Rainbow effect, because the basic colours are projected one by one
LDT Beamers: Laser Display Technology
Laser beamers initiate formation of images by a laser beam rapidly deflected and modulated. With a LTD beamer, the image is written on the large screen line by line.
Source: https://www.professional-system.de/basics/laser-beamer-mit-laser-in-die-zukunft/
As a result, the projector achieves a much better image quality. A special scanner with a facet mirror provides for formation of lines, whereas the tiling mirror initiates the next line feed.
The modulated laser beam can determine the correct brightness and colour for each image point. Appropriate security mechanisms ensure a trouble-free operation, so that the operator is not afraid of the laser.
Advantages of the LDT beamers:
- Large contrast range
- High light output is possible
- Long service life of the light source
- Basic colours are mixed to an overall image
Disadvantages of the LDT beamers:
- High purchase price
- In the case of high performance laser projectors, there is a danger for eyes without personal protection equipment
- Speckle patterns may occur
We recommend different beamers and technologies, depending on the type or place of use.You can hardly find a beamer suitable for each situation and at each location.
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