Projector Technologies

Wednesday 15 November 2017 at 05:35 am.

Projectors use different technologies to project the image in a clear manner. Some of the basic technologies are:

Digital light processing (DLP) is a rear screen projection technology that uses many mirrors (micro size) to reflect and display the image. The mirrors are embedded on a semi conductor in the form of arrays where each one of them may denote one pixel. There are basically two types of DLP technologies viz. the single chip technology which uses a color wheel or collection of individual beams of basic light to produce color, the three chip technology which uses a prism to deflect light and produce a ‘rainbow effect’. The lamps used are that of metal halide with a lamp counter indicating the life left. Modern projectors with this technology use LEDs thereby eradicating the usage of the color wheel. DLP projectors are widespread where Real Time Picture or 3 Dimensional pictures are required.

LCD is a flat panel with arrays of liquid sandwiched between layers of surfaces including the polarizer, electrodes, glass substrate and works by allowing the light to pass through the same exciting certain areas which then produce a coherent image. The LCD technology used in projectors utilizes a prism that separates the input beam of light into basic color zones which then fall on the LCD to open or block the individual pixel. The throw ratio is defined as the ratio of distance from the screen and screen width. They are lighter in size and compact to use involving metal halide bulbs. Thus they can be used to project images on a flat screen.

It is a hybrid of the LCD and DLP technologies, while it uses the liquid crystal effect applied to mirror substrate for reflecting the light which is then allowed or blocked by the liquid crystal leading to formation of the image. This technology is sans any spinning color wheels and produces an image that is clear and of a superior quality than the LCD or DLP images. LCOS uses three chips that channelize the basic colors to the image. They are compact and can produce quality of higher resolution. One of the major disadvantages is inferior contrast performance when compared to the other two technologies which are around 500:1 to 800:1. Lower lamp life and complexities involved in replacing the lamps are other factors that make LCOS not preferred.

Other technologies
Some other technologies that have been upgraded to suit the technological growth include the OLED (Organic LED) which uses emissive technology where in the screen by itself emits light and is not dependent on any other sources for the same. Enhanced color retention, high luminescence rendered and picture clarity are some of the characteristics. Similar technologies involve the 3D technology where the pictures are given a 3rd dimension using the existing DLP projection technique. Holographic images are also catching up with the race where images are projected in such a manner that they seem to float in the thin air. Different blends of the available technologies are used to give the best output that is ‘the best’ in all forms.

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