How Does An Lcd Projector Work?
A projector is basically an apparatus for projecting slides or films on to a screen. In a conventional projector which is used for projection of films, light from a carbon arc lamp is passed through a rotating shutter which controls the flow of film frames. The shutter lets light through only if the film is in the right position. The images are thrown onto a screen or a plain surface in rapid succession creating an illusion of movement. Although the principle of projection is the same, an LCD projector differs from the conventional projector. An LCD projector is capable of projecting video, images or computer data. onto a screen or other flat surface. How does it work? An LCD projector instead of a carbon arc lamp uses a Metal Halide lamp as the light source to send light through three LCD panels, namely polarizer, LCD panel and analyzer - one each for red, green, and blue components of the video signals. As the polarized light passes through the panels the individual pixels are made to allow light to pass through or closed to block the polarized light. The projected image is a combination of open and closed pixels, producing various shades and colors. The use of Metal Halide lamps in LCD projectors is not without reason. Their output encompasses a broad range of colors and they are capable of producing considerably large amount of light within a small area. The quality of the image from an LCD projector is dependent on the projection surface and is found that blank white or grey surface display the best image. To improve image quality, dedicated projection screens are also used. Color of the projected image is dependent on the projection surface as well as projector quality. Natural color tones are best displayed on a white or grey surface. However white screens throw up a problem if the projected image contains dark or black images. Though color problems can be sorted out through adjustment of the projector settings, a compromise has to be made somewhere between choosing a white screen or a dark screen depending on the presentation. There is a limit on the number of hours an LCD projector can work effectively. This limit lies between 8 and 10 hours. Beyond this length of time, the quality of the image tends to suffer and the deterioration may be permanent. As already seen , the light from the metal halide lamp passes through the LCD panels consisting of chips on to the screen, In this process, the heat from the halide lamp is transmitted to the LCD chips causing the deterioration which results in skewing of colors, contrast, and picture quality. Here are a few terms connected with LCD projectors explained: LCD Projector resolution is available in four denominations SVGA (800 x 600) XGA (1024 x 768) SXGA (1280 x 1024) UXGA (1600 x 1200) SVGA resolution is sufficient for PowerPoint presentations and to display numerical data it is better to have XGA. However it may be noted that if you go in for a higher resolution, the price is higher. LCD Projector Brightness is rated according to ANSI lumens rating. The higher the rating the b brighter the LCD projector's light output. Projectors of 1000-2000 lumens may be enough for business or classroom projections and projectors of 2000-3000 lumens are ideal for conference rooms. LCD Projector Contrast is the ratio between the brightest and darkest areas of the image. Go in for LCD projectors with contrast ratios of 400:1 or higher. This way you can ensure that the graphics and video images are clear. |
