DLP Technology

Digital Light Processing Technology

It is information age. Computers, faxes, modems, pagers, and cellular phones surround us. All these products rely on digital technology. More recent advances have resulted in digital cameras, digital camcorders, digital satellite systems and, digital video disk players. Majority of video displays are based on the old analog cathode ray tube which converts the digital video and graphic data into analog before it is viewed. Digital Light Processing technology is the new digital display technology that provides a completely digital video information structure.

Digital Light Processing technology uses an optical semiconductor to manipulate light digitally. Dr. Larry Hornbeck originally developed this revolutionary display solution at Texas Instruments in 1987. This technology is being used to deliver the best picture across a broad range of products, including large screen digital televisions, projectors for business, home, professional venue and digital cinema. Texas Instruments are the primary manufacturers of Digital Light Processing technology. Many licensees who market products based on Texas Instrument?s chipsets are using it.

The Digital Light Processing technology projection system has microscopically small mirrors laid out in a matrix on an optical thumbnail size semiconductor light switch. This semiconductor is known as a Digital Micromirror Device or Digital Light Processing Chip. Each mirror represents one pixel in the projected image. Thus, the number of mirrors are responsible for the resolution of the projected image. These mirrors are mounted on a hinge structure so that it can be individually tilted back and forth, either towards the light source (on) or away from it (off). The mirrors are electronically tilted at speeds greater than 1,000 times per second. This results is varying the intensity of the light being reflected out through the lens, leading to shades of gray in addition to white and black. This technology can reflect pixels in up to 1,024 shades of gray to convert the video or graphic signal into a highly detailed grayscale image.

There are two primary methods by which Digital Light Processing technology projection system creates a color image: 1) Single-Chip Digital Light Processing Projection System and, 2) Three-Chip Digital Light Processing Projection System. Single Chip Digital Light Processing Projection System is used in televisions, home theater systems and business projectors. The process basically makes use of four main components: the Digital Micromirror Device also known as the Digital Light Processing chip, color wheel, light source, and optics. The color wheel is placed between the lamp and the Digital Micromirror Device. The lamp produces the light, which passes through the color wheel filter and further into the Digital Micromirror Device. This device switches its mirrors on or off in relation to the color reflecting off them, producing an image. The white light is thus, filtered into three primary colors: red, green, and blue; which are reflected through the optics. Projectors for cinemas and large venue displays, which require very high image quality and high brightness make use of the ?Three Chip Projection System?, to produce stunning moving or still images. The difference in the Three Chip Projection System is that, a prism is used to split light from the lamp, and each primary color (red, green, and blue) is further routed through individual Digital Micromirror Device, then recombined and rerouted out through the lens. Single-Chip Digital Light Processing System is capable of displaying 16.7 million (24-bit) colors, whereas Three-Chip Digital Light Processing System can display up to 35 trillion colors.

Advantages

Digital Light Processing technology brings more light from the lamp to the screen, resulting in brighter and effective presentations. The exact mirror image of an input video or graphic signal is produced, resulting in sharper picture. The images produced are virtually seamless. The picture appears seamless because the mirrors have very tiny spaces between them, one-micrometer gaps, to be exact. Machines using this technology are smaller and compact, for example Digital Light Processing projectors are small and light, thus making them versatile for use in conference rooms, living rooms and classrooms. They have a muted pixel structure when viewed from a typical viewing distance. The screen door effect is no more a problem. Rather than looking at an image as if it were behind a screen door, the viewer sees a seamless, digitally generated and projected image. Televisions using this technology are smaller, thinner, and lighter. Thus, these also fit well on to tabletop stands and are available in popular 40, 50, and 61-inch models.

Digital Light Processing systems are inherently reliable. They are subjected to a series of environmental and regulatory tests to stimulate thermal shock, temperature, mechanical shock, vibration, moisture resistance, and acceleration conditions.

Also, since Digital Light Processing technology uses a mirror and light, the backlight bulb is replaceable. In certain machines, the Digital Light Processing is configured in such a way that even a layperson can easily replace the burned-out bulbs. This results in potentially longer life of the machine.

Weakness

The only weakness that can be pointed out with this technology is the Rainbow Effect, which is unique to the Single Chip Digital Light Processing Projection System. The Rainbow Effect is defined as ?brief flashes of perceived red, blue, and green shadows?. Since the Single Chip Digital Light Processing projection system uses a color wheel, at any given instant in time, the image on the screen is either red, or green, or blue. The technology relies upon the eyes not being able to detect the rapid changes from one to the other. However, sometimes as the eye moves across the projected image, these separate colors become visible, resulting in a perceived "rainbow". The rapid sequencing of color has also resulted in reported complaints of eyestrain and headaches amongst viewers.

In order to overcome this problem, Texas Instruments and the vendors who build projectors using Digital Light Processing technology are using color wheels rotating at higher speeds, or with more color segments. Many Digital Light Processing projectors being built for the home theater market are incorporating a six-segment color wheel, which spins at the speed of 120 Hertz or 7200 rotations per minute. Although, the appearances of these artifacts have reduced amongst viewers, the problem still persists.

More and more information in today?s world is created, edited and transmitted in the digital domain. Majority of the already existing technologies limit the full potential of digital display. At present, Digital Light Projection technology is the only digital projection solution available which produces an entirely digital video infrastructure.