December 2006 Volume 4 Issue 1 Rs 100 Your world of technology is about to change. Here is what these visionaries predict about the future of hardware, software and the Internet 34 Best Products Annual Graphics Meltdown! Quad Scorcher great gadgets, certiﬁed Nvidia G80 vs ATI 1950 XTX Exclusive! Intel’s newest 36 by our Test Center 68 CrossFire. Any bets? 66 desktop processor 94 Spyware be Gone Magic with your Digicam Lenovo ThinkPad X60 Ultra-portable goodness 8 deﬁnitive tools to safeguard Get up to 48 megapixels from your 43 your computer 120 own camera! 156 Win prizes worth Rs. 1.25 Lakhs! Also available in Bangladesh,Nepal, Bhutan, Sri Lanka, UAE HARDWARE INFOGRAPHICS Image Projectors Projectors are not restricted to conference rooms anymore. A look inside to see what makes them tick BY ASHUTOSH DESAI B y deﬁnition, a projector is an optical device that projects an enlarged image onto a screen. LCD Projectors LCD Panels Each LCD panel blocks The projector is provided with an differing amounts of light. An input signal—which could be video Dichroic Mirrors LCD panel measures 0.9-inch from a computer or a DVD player. A lamp acts as the light source in the LCD projector. in size. Such a small area This video signal is processed into This light is split up into the primary colors – Red, contains 786,000 pixels (for an image that is projected onto Blue and Green. This is done with ‘dichroic mirrors’. a regular XGA projector). the screen. Before understanding Dichroic mirrors selectively reﬂect certain There are three LCD panels. projectors treat a video signal to wavelengths of light. This is because the mirrors Therefore over 2 million pixels light up a screen with an image, let’s are placed at an angle to the incident light. The Red can be controlled to produce simplify the process. A projector dichroic mirror reﬂects Blue-Green wavelengths an output. consists of a circuit that converts of light. In this manner, the mirrors reﬂect light and incoming video signal to digital—if the direct the RGB channels towards their respective input is analog. The resulting digital LCD panels. signal is sent to another part of the projector known as the ‘light engine’. This is where a light source directs Microﬁne Grid a beam towards a color splitting Since the pixels are packed so closely, there is bound to be some ‘mixing’. component, goes through color ﬁlters To prevent this, a microﬁne grid is used to absorb some of the incident light and complex optical elements. to prevent the pixels from ‘bleeding’ light into their neighbors. This results Different methods and technologies in a good quality image but with lower intensity. The grid also produces a are used to transform this video signal ‘screen door effect’. When the image is sharpened, the pixels become more into light. visible and appear to be within boxes. There are two types of projectors that are used extensively today. They are either ‘transmissive’ or ‘reﬂective’. R,G,B LCD From these names one can gain an Panels understanding on the method used Dichroic to treat light within a projector. Combiner Cube Mirror A transmissive projector contains components that allow light to pass through it. These components might use CRT or LCD technology Mirror to form the ﬁnal image Here only the LCD projector will be explained Dichroic Mirror in detail as it has grown more (B) popular due to its portable nature. Dichroic Mirror A reﬂective projector makes use of Dichroic Mirror (G) tiny movable, mirror-like components (R) to reﬂect light in the device. The reﬂective projector usually uses DLP technology to form the ﬁnal Micro Lens Array image. Projectors that use LCOS To prevent the screen door effect, a micro lens array is placed technology use both transmissive before the microﬁne grid. This lens array ensures that the light as well as reﬂective techniques to falling on the LCD panel is transmitted with almost the same form an image on the screen. intensity through the grid, reducing this effect. 108 | INTELLIGENT COMPUTING CHIP | DECEMBER 2006 INFOGRAPHICS HARDWARE DLP Projectors Digital Micromirror Device (DMD) A Digital Light Processing projector uses some sophisticated electronics. It is ﬁ tted with a Digital Micromirror Device (DMD), which is a chip. A DMD is made up of tiny (microscopic) mirrors that can tilt in two directions so as to reﬂect light incident on it (devices that have microscopic mechanical systems built into them are known as micro-electricomechanical systems). These tiny mirrors move in a particular direction to either allow light to reﬂect or not. This leads to the typical ‘On/Off’ situation. The DMD gets its instructions for positioning each mirror – there can be more than two million of them – from the digital video signal. Information relayed to each mirror changes over a Color Wheel thousand times every second. The light reﬂected The light source in a DLP projector shines light through optical elements by the mirror (depending on whether it is on or off) that converge a beam onto a spinning color wheel. The color wheel (usually produces 1024 shades of gray. made up of four segments – R, G, B and a clear portion) splits the beam into red, green and blue. The ﬁltered light once again goes through another set of optics to ﬁnally reach the DMD chip. This ﬁltering and the reﬂecting micro- mirrors are synchronized perfectly to produce the right shade. This setup does not produce the ‘screen door effect’ but is affected by something known as a ‘rainbow effect’. This is removed in high-end DLP projectors that have three DMDs – one for each color channel. Newer projectors also have 6 or 7-segment color wheels, where the primary colors are repeated. This way Processor the image reproduction is closer to the input signal and also reduces a faint multi-colored rainbow from appearing on the projector screen. DLP Circuit Memory Board Projection Lens DMD Shaping Lens Color Wheel Condensing Lens Light Source | DECEMBER 2006 INTELLIGENT COMPUTING CHIP | 109
"Chip Magazine - December 2006 Issue"