DLP - AbsoluteAstronomy.com

Digital Light Processing (DLP) is a trademark

Trademark

A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...

owned by Texas Instruments

Texas Instruments

Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...

, representing a technology used in some TVs and video projector

Video projector

A video projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other...

s. It was originally developed in 1987 by Dr. Larry Hornbeck of Texas Instruments

Texas Instruments

Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...

.

DLP is used in DLP front projectors (small standalone projection units) and DLP rear projection television set

Television set

A television set is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after the Second World War, using vacuum tubes and cathode ray tube displays...

s. It is also one of the leading technologies used in digital cinema

Digital cinema

Digital cinema refers to the use of digital technology to distribute and project motion pictures. A movie can be distributed via hard drives, optical disks or satellite and projected using a digital projector instead of a conventional film projector...

projection.

DLP, along with LCD

LCD projector

An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector...

and LCoS

Liquid crystal on silicon

Liquid crystal on silicon is a "micro-projection" or "micro-display" technology typically applied in projection televisions. It is a reflective technology similar to DLP projectors; however, it uses liquid crystals instead of individual mirrors. By way of comparison, LCD projectors use...

, are the current display technologies behind rear-projection television

Rear-projection television

Rear-projection television or RPTV is a type of large-screen television display technology. Up until the mid-2000s, most of the relatively affordable consumer large screen TVs up to used rear-projection technology...

, having supplanted CRT rear projectors. These rear-projection technologies compete against LCD

Liquid crystal display television

Liquid-crystal display televisions are television sets that use LCD display technology to produce images. LCD televisions are thinner and lighter than cathode ray tube of similar display size, and are available in much larger sizes...

and plasma

Plasma display

A plasma display panel is a type of flat panel display common to large TV displays or larger. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent...

flat panel display

Flat panel display

Flat panel displays encompass a growing number of electronic visual display technologies. They are far lighter and thinner than traditional television sets and video displays that use cathode ray tubes , and are usually less than thick...

s in the HDTV market.

The single-chip version of DLP and 3LCD

3LCD

3LCD is the name and brand of a major LCD projection color image generation technology used in modern digital projectors. 3LCD technology was pioneered and refined by Japanese imaging company Epson in the 1980s and was first licensed for use in projectors in 1988...

are the two main technologies used in modern colour digital projectors, with the two technologies being used in over 95% of the projectors sold in 2008.

In March 2008, TI announced the initial production of the DPP1500 chipset, which are micro projectors to be used in mobile devices. Availability for final products would show up in the market early 2009.

Digital micromirror device

In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a Digital Micromirror Device

Digital micromirror device

A digital micromirror device, or DMD, is an optical semiconductor that is the core of DLP projection technology, and was invented by Dr. Larry Hornbeck and Dr. William E. "Ed" Nelson of Texas Instruments in 1987....

(DMD). Each mirror represents one or more pixel

Pixel

In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....

s in the projected image. The number of mirrors corresponds to the resolution of the projected image (often half as many mirrors as the advertised resolution due to wobulation

Wobulation

Wobulation is a term which refers to the known variation in a characteristic. Examples of where the term is used, include to describe advanced radar waveform modulations - where the repetition rate or centre frequency of a signal is changed in a repetitive fashion to reduce the probability of...

). 800x600

Super Video Graphics Array

Super Video Graphics Array or Ultra Video Graphics Array, almost always abbreviated to Super VGA, Ultra VGA or just SVGA or UVGA is a broad term that covers a wide range of computer display standards....

, 1024x768, 1280x720

720p

720p is the shorthand name for 1280x720, a category of High-definition television video modes having a resolution of 1080 or 720p and a progressive scan...

, and 1920x1080

1080p

1080p is the shorthand identification for a set of HDTV high-definition video modes that are characterized by 1080 horizontal lines of resolution and progressive scan, meaning the image is not interlaced as is the case with the 1080i display standard....

(HDTV) matrices are some common DMD sizes. These mirrors can be repositioned rapidly to reflect light either through the lens or on to a heat sink

Heat sink

A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...

(called a light dump in Barco

Barco

Barco N.V. is a display hardware manufacturer specialising in video projectors, LCD projectors, DLP projectors, LCoS projectors, LED displays, video walls, flat panel displays, automated luminaires, digital lighting and lighting controls....

terminology).

Rapidly toggling the mirror between these two orientations (essentially on and off) produces grayscale

Grayscale

In photography and computing, a grayscale or greyscale digital image is an image in which the value of each pixel is a single sample, that is, it carries only intensity information...

s, controlled by the ratio of on-time to off-time.

Color in DLP projection

There are two primary methods by which DLP projection systems create a color image: those utilized by single-chip DLP projectors, and those used by three-chip projectors. A third method, sequential illumination by three colored light emitting diodes, is being developed, and is currently used in televisions manufactured by Samsung

Samsung

The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea...

. Yet another method, color lasers, is currently in use by Mitsubishi in their LaserVue products.

Single-chip projectors



Interior view of a single-chip DLP projector, showing the light path. Light from the lamp enters a reverse-fisheye, passes through the spinning color wheel, crosses underneath the main lens, reflects off a front-surfaced mirror, and is spread onto the DMD (red arrows). From there, light either enters the lens (yellow) or is reflected off the top cover down into a light-sink (blue arrows) to absorb unneeded light. Top row shows overall components, closeups of 4-segment RGBW color wheel, and light-sink diffuser/reflection plate on top cover.

In a projector with a single DLP chip, colors are produced either by placing a color wheel

Color wheel (optics)

A color wheel or other switch for changing a projected hue is a device that uses different optics filters within a light beam...

between a white lamp

Lamp (electrical component)

A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made...

and the DLP chip or by using individual light sources to produce the primary colors, LED

LEd

LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

s or laser

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

s for example. The color wheel is divided into multiple sectors: the primary colors: red, green, and blue, and in many cases secondary colors including cyan, magenta, yellow and white. The use of the secondary colors is part of the new color performance system called BrilliantColor which processes the primary colors along with the secondary colors to create a broader spectrum of possible color combinations on the screen.

The DLP chip is synchronized with the rotating motion of the color wheel so that the green component is displayed on the DMD when the green section of the color wheel is in front of the lamp. The same is true for the red, blue and other sections. The colors are thus displayed sequentially at a sufficiently high rate that the observer sees a composite "full color" image. In early models, this was one rotation per frame. Now, most systems operate at up to 10x the frame rate.

The color wheel "rainbow effect"

DLP projectors utilizing a mechanical spinning color wheel may exhibit an anomaly known as the "rainbow effect." This is best described as brief flashes of perceived red, blue, and green "shadows" observed most often when the projected content features high contrast areas of moving bright or white objects on a mostly dark or black background. The scrolling end credits of many movies are a common example, and also in animations where moving objects are surrounded by a thick black outline. Brief visible separation of the colours can also be apparent when the viewer moves their eyes quickly across the projected image. Some people perceive these rainbow artifacts frequently, while others may never see them at all.

This effect is caused by the way the eye follows a moving object on the projection. When an object on the screen moves, the eye will follow the object with a constant motion, but the projector will display each alternating color of the frame at the same location, for the duration of the whole frame. So, while the eye is moving, it will see a frame of a specific color (red for example). Then, when the next color is displayed (green for example), although it gets displayed at the same location overlapping the previous color, the eye will have moved toward the object's next frame target. Thus, the eye will see that specific frame color slightly shifted. Then, the third color gets displayed (blue for example), and the eye will see that frame's color slightly shifted again. This effect is not perceived only for the moving object, but the whole picture.

The effect varies with the rotational speed of the color wheel and the frame refresh rate of the video signal. There is a maximum rotational speed limit for the wheel, typically 10,000 to 15,000 RPM

Revolutions per minute

Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

. Video framerate is usually measured in frames per second and must be multiplied by 60 to find the wheel speed, whereas 60 frames/sec equals 3,600 frames/minute. If the color wheel spins 4 times per frame, it is rotating at a speed of 14,400 RPM. (Projector specifications often list the wheel speed at specific framerates as 2x, 3x, 4x, etc.) Increasing the video refresh rate to 85 frames per second does not necessarily further reduce the rainbow effect since this rate would increase the wheel speed to 20,400 RPM, potentially exceeding the safe limits of wheel rotation and requiring the projector to drop back to 3x speed, at 15,300 RPM.

Multi-color LED-based and laser-based single-chip projectors are able to eliminate the spinning wheel and minimize the rainbow effect since the pulse rate of LEDs and laser are not limited by physical motion.

Three-chip projectors

A three-chip DLP projector uses a prism to split light from the lamp

Lamp (electrical component)

, and each primary color of light is then routed to its own DLP chip, then recombined and routed out through the lens

Lens (optics)

A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...

. Three chip systems are found in higher-end home theater projectors, large venue projectors and DLP Cinema projection systems found in digital movie theaters.

According to DLP.com, the three-chip projectors used in movie theaters can produce 35 trillion colors. The human eye is suggested to be able to detect around 16 million colors, which is theoretically possible with the single chip solution. However, this high color precision does not mean that three-chip DLP projectors are capable of displaying the entire gamut

Gamut

In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a...

of colors we can distinguish (this is fundamentally impossible with any system composing colors by adding three constant base colors). In contrast, it is the one-chip DLP projectors that have the advantage of allowing any number of primary colors in a sufficiently fast color filter wheel, and so the possibility of improved color gamuts is available.

Light source

The main light source used on DLP-based rear screen projection TVs is based on a replaceable high-pressure mercury-vapor metal halide

Metal halide lamp

Metal-halide lamps, a member of the high-intensity discharge family of lamps, produce high light output for their size, making them a compact, powerful, and efficient light source. By adding rare earth metal salts to the mercury vapor lamp, improved luminous efficacy and light color is obtained...

arc lamp unit (containing a quartz arc tube, reflector, electrical connections, and sometimes a quartz/glass shield), while in some newer DLP projectors high-power LEDs or laser

Laser

s are used as a source of illumination.

Metal-halide lamps

For metal-halide lamps, during start-up, the lamp is ignited by a 5000 volt pulse from a current-regulating ballast to initiate an arc between two electrodes in the quartz tube. After warmup, the ballast's output voltage drops to approximately 60 volts while keeping the relative current high. As the lamp ages, the arc tube's electrodes wear out and light output declines somewhat while waste heating of the lamp increases. The mercury lamp's end of life is typically indicated via an LED on the unit or an onscreen text warning, necessitating replacement of the lamp unit.

Older projectors would simply give a warning that the lamp life had expired but would continue to operate. Newer projectors will not power up until the lamp is replaced and the lamp hours are reset. Most devices include a lamp hours reset function for when a new lamp is installed, but it is possible to reset a projector to continue to use an old lamp past its rated lifespan.

When a metal-halide lamp is operated past its rated lifespan, the efficiency declines significantly, the lightcast

Lightcast

A lightcast is a functional analysis and mapping of the illumination produced by a light source. It is used to map the physical characteristics of light emission for use in functional systems...

may become uneven, and the lamp starts to operate extremely hot, to the point that the power wires can melt off the lamp terminals. Eventually, the required startup voltage will also rise to the point where ignition can no longer occur. Secondary protections such as a temperature monitor may shut down the projector, but a thermally overstressed quartz arc tube can also crack and/or explode, releasing a cloud of hot mercury vapor inside and around the projector. However, practically all lamp housings contain heat-resistant barriers (in addition to those on the lamp unit itself) to prevent the red-hot quartz fragments from leaving the area.

LED-based DLPs

The first commercially-available LED-based DLP HDTV was the Samsung

Samsung

The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea...

HL-S5679W in 2006, which also eliminated the use of color wheel. Besides long lifetime eliminating the need for lamp replacement and elimination of the color wheel, other advantages of LED illumination include instant-on operation and improved color, with increased color saturation and improved color gamut to over 140% of the NTSC color gamut

RGB color space

An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticities of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors...

. Samsung expanded the LED model line-up in 2007 with products available in 50", 56" and 61" screen sizes. For spring 2008, the third generation of Samsung LED DLP products are available in 61" (HL61A750) and 67" (HL67A750) screen sizes.

Ordinary LED technology does not produce the intensity and high lumen output characteristics required to replace arc lamps. The special patented LEDs used in all of the Samsung DLP TVs are PhlatLight LEDs, designed and manufactured by US based Luminus Devices. A single RGB PhlatLight LED chipset illuminates these projection TVs. The PhlatLight LEDs are also used in a new class of ultra-compact DLP front projector commonly referred to as a "pocket projector" and have been introduced in new models from LG Electronics (HS101), Samsung electronics (SP-P400) and Casio

Casio

is a multinational electronic devices manufacturing company founded in 1946, with its headquarters in Shibuya, Tokyo, Japan. Casio is best known for its electronic products, such as calculators, audio equipment, PDAs, cameras, musical instruments, and watches...

(XJ-A series). Home Theater projectors will be the next category of DLP projectors that will use PhlatLight LED technology. At InfoComm, June 2008 Luminus and TI announced their collaboration on using their technology on home theater and business projectors and demonstrated a prototype PhlatLight LED based DLP home theater front projector. They also announced products will be available in the marketplace later in 2008 from Optoma and other companies to be named later in the year.

Luminus Devices PhlatLight LEDs have also been used by Christie Digital

Christie (company)

The Christie group of companies are part of the Ushio group of companies, the ultimate parent of which is Ushio Inc., a publicly traded Japanese company, Japan...

in their DLP-based MicroTiles

MicroTiles

The MicroTiles video display system from Christie Digital is composed of modular 16" × 12" rear projection cube units which can be built together into a large video wall-style display. Each MicroTile unit contains a short-throw projector based on an LED light source and DLP optical imaging...

display system. It is a modular system built from small (20 inch diagonal) rear projection cubes, which can be stacked and tiled together to form large display canvasses with very small seams. The scale and shape of the display can be any size, only constrained by practical limits.

Laser-based DLPs

The first commercially-available laser-based DLP HDTV was the Mitsubishi

Mitsubishi

The Mitsubishi Group , Mitsubishi Group of Companies, or Mitsubishi Companies is a Japanese multinational conglomerate company that consists of a range of autonomous businesses which share the Mitsubishi brand, trademark and legacy...

L65-A90 LaserVue in 2008, which also eliminated the use of a color wheel. Three separate color lasers illuminate the digital micromirror device

Digital micromirror device

(DMD) in these projection TVs, producing a richer, more vibrant color palette than other methods. See the laser video display article for more information.

Digital cinema

On February 2, 2000, Philippe Binant, technical manager of Digital Cinema Project at Gaumont

Gaumont Film Company

Gaumont Film Company is a French film production company founded in 1895 by the engineer-turned-inventor, Léon Gaumont . Gaumont is the oldest continously operating film company in the world....

in France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, realized the first digital cinema projection in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

with the DLP CINEMA technology developed by Texas Instruments.

DLP is the current market-share leader in professional digital movie projection, largely because of its high contrast ratio and available resolution as compared to other digital front-projection technologies. As of December 2008, there are over 6,000 DLP-based Digital Cinema Systems installed worldwide.

DLP projectors are also used in RealD Cinema and newer IMAX

IMAX

IMAX is a motion picture film format and a set of proprietary cinema projection standards created by the Canadian company IMAX Corporation. IMAX has the capacity to record and display images of far greater size and resolution than conventional film systems...

theatres for 3-D film

3-D film

A 3-D film or S3D film is a motion picture that enhances the illusion of depth perception...

Manufacturers and marketplace

Texas Instruments remains the primary manufacturer of DLP technology, which is used by many licensees who market products based on TI's chipset

Chipset

A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :...

s. The Fraunhofer Institute of Dresden, Germany, also manufactures Digital Light Processors, termed Spatial Light Modulators, for use in specialized applications. For example, Micronic Laser Systems of Sweden utilizes Fraunhofer's SLMs to generate deep-ultraviolet imaging in its Sigma line of silicon mask lithography writers.

DLP technology has quickly gained market share in the front projection market and now holds roughly 50% of the worldwide share in front projection. Over 30 manufacturers use the DLP chipset to power their projectors.

Pros

Smooth (at 1080p resolution), jitter-free images
Perfect geometry and excellent grayscale linearity achievable
Usually great ANSI contrast
No possibility of screen burn-in
Less "screen-door effect
Screen-door effect
The screen-door effect or fixed-pattern noise is a visual artifact of the projection technology used in digital projectors, where the fine lines separating the projector's pixels become visible in the projected image...

" than with LCD projectors
DLP rear projection TVs generally have a smaller form factor than comparable CRT projectors.
DLP rear projection TVs are considerably cheaper than LCD or plasma flat-panel displays and can still offer 1080p resolution.
The use of a replaceable light source means a potentially longer life than CRTs and plasma displays (this may also be a con as listed below)
The light source is more-easily replaceable than the backlight
Backlight
A backlight is a form of illumination used in liquid crystal displays . As LCDs do not produce light themselves , they need illumination to produce a visible image...

s used with LCDs, and on DLPs is often user-replaceable.
New LED and laser DLP TVs and projectors eliminate the need for lamp replacement.
Using two projectors, one can project full color stereoscopic images using polarized process (because beams can be polarized).
Lighter weight than LCD and plasma televisions
Unlike their LCD and plasma counterparts, DLP screens do not rely on fluids as their projection medium and are therefore not limited in size by their inherent mirror mechanisms, making them ideal for increasingly larger high-definition theater and venue screens.
DLP projectors can process up to 7 separate colors, giving them strong color performance.
DLP projectors do not suffer from "color decay", often seen with LCD projectors in which the image on the screen yellows after extended periods of usage.

Cons

Some viewers are bothered by the "rainbow effect" (explained above).
Rear projection DLP TVs are not as thin as LCD or plasma flat-panel displays (although approximately comparable in weight), although some models as of 2008 are becoming wall-mountable (while still being 10" to 14" thick)
Replacement of the lamp / light bulb. The average life span of a TV light source averages 2000–5000 hours and the replacement cost for these range from $99 – 350, depending on the brand and model. After replacing the bulb a few times, the cost can easily exceed the original purchase price of the television or projector itself. Newer generations' units use LEDs or lasers which effectively eliminate this issue, although replacement LED chips could potentially be required over the extended lifespan of the television set.
Some viewers find the high pitch whine of the color wheel to be an annoyance. though the drive system can be engineered to be silent and some projectors don't produce any audible color wheel noise.
Dithering noise may be noticeable, especially in dark image areas. Newer (post ~2004) chip generations have less noise than older ones.
Error-diffusion artifacts caused by averaging a shade over different pixels, since one pixel cannot render the shade exactly
Response time in video games may be affected by upscaling lag. While all HDTVs have some lag when upscaling lower resolution input to their native resolution, DLPs are commonly reported to have longer delays. Newer consoles such as the Xbox 360
Xbox 360
The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...

do not have this problem as long as they are connected with HD-capable cables.
Reduced viewing angle as compared to direct-view technologies such as CRT, plasma, and LCD

DLP, LCD, and LCoS rear projection TV

The most similar competing system to DLP is known as LCoS (liquid crystal on silicon

Liquid crystal on silicon

), which creates images using a stationary mirror mounted on the surface of a chip, and uses a liquid crystal matrix (similar to a liquid crystal display

Liquid crystal display

A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

) to control how much light is reflected. DLP-based television systems are also arguably considered to be smaller in depth than traditional projection television.

External links

DLP demonstration
Boxlight Corp. DLP White Paper, Netsuite.com
DLP projectors vs LCD projectors; guide on DLP and LCD technology in projectors and how they compare
DLP Projector Technology

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Digital micromirror device

Color in DLP projection

Single-chip projectors

The color wheel "rainbow effect"

Three-chip projectors

Light source

Metal-halide lamps

LED-based DLPs

Laser-based DLPs

Digital cinema

Manufacturers and marketplace

Pros

Cons

DLP, LCD, and LCoS rear projection TV

See also

Further reading

External links