No matter whether you find yourself sitting in the Corporate Conference Room working your way through another Presentation schedule or a classroom being caught in the web of the next Science Project being shown or lounging at home watching another blockbuster, LCD projectors rule the roost. Developed in 1984 by Gene Dolgoff, it remains the most well-frequented projection technology in 21st century with a global visibility, thanks to Sony and Epson, along with Digital Light Processing (DLP) Projectors.
Film Projection has come along way since motion pictures first uplifted their curtains with the maiden concepts of Projectors visualised by Charles Francis Jenkins in 1894. Initially they were nothing more than a series of photographs through which light was thrown and that light when it passes through an imaging lens cast the larger version of the tiny film rolls on the blank screen or the wall in front stringing together images and sound in the process. Thus life was breathed into motion pictures and since then there has been no looking back.
How do the Projectors function?
- LCD (Liquid Crystal Display) Projectors of today however are far more evolved and make those earliest projectors seem an anachronism. They are far more complex in their technique they employ to provide the customers a range of options, depending on their budget, preference and requirement.
Mechanism: A strong beam of polarized light is made to pass through thousands of dynamic pixels ( In digital terminology, a pixel is a portmanteau word formed by the conjunction of pix (picture) and el(element), which is the smallest controllable element of a picture that can be addressed). Three such Projectors are used and the light splits the pixels into three different hues(one for each primary colour) which then travels through the three separate projectors before combining in the final prism to render a clear, vibrant, precise image on the screen.
Drawback: This option is generally the least expensive of the lot with a single chip LCD Projector available on an economical budget while the 3 chip one offers better result for viewing movies. However, they are high maintenance and offer less options for colour contrast.
- DLP (Digital Light Processing Projector) make use of the DMD chip which are ‘Digital Micro mirror device’s, each one collating millions of tiny microscopic mirrors on a single chip where each chip is finer than 1/5th width of human hair.
Mechanism: It uses a spinning colour wheel to create an image wherein each mirror represents 1 pixel of a particular colour. So if there’re are 2 million mirrors , the entire image is first dispersed in that many pixels and later magnified by a giant lens, the final picture crops up on the screen resulting in a razor sharp image which requires no filters and has a lightning fast response time.
Drawback: However the life span of a DLP projector is 2000-2500 hours only and cases of colour ghosting / banding have been frequently reported.
- LcoS , is the latest tech on the block , short for Liquid Crystal on Silicon and the most expensive and developed style in use.
Mechanism: This one is a hybrid between the LCD and DLP projection technique as this is too is reflective but instead of mirrors as used in DLP, this makes use of liquid crystals wedged between a thin film Transistor (TFT) and a reflective silicon back plate. The light which passes through a polarizing layer in the RGB( Red, Blue , Green) Channel creating three separate sub-pixels of colour are reflected on the semi-conductor back plate of silicon wherein the liquid crystals modulate the entry and closure of the gates , thus regulating the amount of light that passes , leading to the creation of the final image.
Drawback: The colour reproduction and clarity is of supreme quality, however motion blur issues can be a constraint for the viewing experience.