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i want a ppt on nano projectors for the seminar of final year
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Abstract
Micro-projection is looked at as a bit of a holy grail for mobile devices. The ability to project a decent-sized image from a tiny device solves the problem of tiny screen sizes on portable video and image players we're already seeing lots of in mobile phones and PDAs as well as standalone units. A reasonable micro projector could transform the portable video experience from 'lean forward and squint' to 'sit back and watch,' making mobile visual content infinitely more sharable and social in the process - not to mention the obvious business applications.
Nano projector
There are two types of conventional projectors: digital light processing (DLP) projectors and liquid crystal display (LCD) projectors. DLP projectors use a special optical semiconductor called a digital micro-mirror device (DMD). This chip, which was invented in 1987 by Texas Instruments, is a precise light switch that enables light to be modulated digitally via millions of microscopic mirrors. The mirrors are capable of switching on and off thousands of times per second and are used to create a picture comprised of millions of pixels.
LCD projectors use a number of small LCD panels (the same technology used for displays) through which light is passed. As the light passes through the LCD panels, individual pixels can be opened or closed to control the passage of light. This activity modulates the light and produces the image that is projected onto the screen. Both DLP and LCD types use a conventional light source (a special, usually expensive light bulb). To make the projector more powerful, more energy is required, translating to a larger device that produces more heat and thus requires active cooling (which again takes up space, requires energy, and has a tendency to break down). Although some improvements have been made in recent years, these problems put lower limits on the size of projectors based on conventional DLP/LCD technology.
It became apparent in recent years that there is a growing market base for a small, light, and relatively inexpensive projector that could be carried along with a laptop, cellphone, or pocket PC to easily present pictures, movie clips, and presentations. Since, as mentioned above, heat and power consumption limitations plague existing DLP/LCD technology, a new technology was needed. Enter Explay, with a radically different way of projecting an image. Instead of using a conventional light source to produce a picture, it set out to develop a laser-based light source for its device. In a conventional projector, only about 15% of the energy is ultimately transferred to the projected image. (Most of the energy is lost as heat, which is why projectors are usually so hot to the touch and require active cooling.) Laser light is much more focused, allowing for a much more efficient way of producing an image. It also requires less energy and thus produces far less heat, eliminating the need for active cooling and so dramatically reducing the size of the projector.
References:
http://gizmaggo/7338/
http://thefutureofthingsarticles/48/smallest-projector-in-the-world.html