Epson 3LCD Technology A Technical Analysis and Comparison against 1-Chip DLP Technology

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1 An Epson White Paper Epson 3LCD Technology A Technical Analysis and Comparison against 1-Chip DLP Technology Epson South Asia & Southeast Asia June 2010

2 About 3LCD Technology 3LCD Technology is the world s leading projection technology that delivers unbelievably bright and natural colour, amazing detail and proven reliability. 3LCD Technology was pioneered by Epson in the 1980s and is today marketed by an affiliated organisation named after the technology 3LCD ( that has licensed the technology for use by other manufacturers worldwide for the ultimate viewing experience in projectors. In 2008, 3LCD Technology celebrated its 20 th Anniversary. Over the past two decades, Epson has constantly refined and scaled the technology to cater to ever-increasing performance and resolution requirements. To date, over 60 million liquid crystal display (LCD) chips have been shipped (1), and 3LCD Technology is found in over 51% (2) of the projectors that were sold worldwide in 2009, which bears testament to its success. The Birth of 3LCD Technology Since the 70s, Epson has developed a leading expertise in LCD technologies as demonstrated by many cutting-edge products including the world s first digital quartz watch in 1973, the world s first TV watch in 1982, and the world s first LCD pocket colour TV in The LCD engineering expertise built up through the development of these products eventually led to Epson introducing the world s first commercially produced ultra-compact, full-colour TFT liquid crystal panel module for video camera viewfinders in August The launch of this product triggered a critically acclaimed response around the world. Epson s first liquid crystal panel module for video cameras Whereas earlier video camera viewfinders were monochrome and used a cathode-ray tube, this viewfinder was the first on the market with the ability to display colour and use a liquid crystal panel. Users of the viewfinder could now check and verify their video recordings in colour using this device. In addition, the poly silicon thin film transistors (TFT) used in the module enabled even greater reductions in viewfinder size and weight, because for the very first time, the circuits used to drive the liquid crystal could be fabricated concurrently with the pixels on the glass substrate. As time passed, colour viewfinder panels migrated to smaller sizes and higher pixel densities in line with market trends. They became a core product of Epson's TFT display business, growing the company s market share and driving a higher rate of colour panel adoption in the market. Epson s TFT LCD engineering expertise honed during the development of these panels would come in very handy when the company set out to develop liquid crystal panels for projectors. The world s first 3LCD digital projector, the Epson VPJ-700 that was launched in 1989 In January 1989, Epson launched its first 3LCD projector: the Epson VPJ-700, renowned for being the market s smallest, lightest and brightest projector when it was launched.

3 Analysis of a Projected Image To appreciate 3LCD technology and its advantages at a technical level, one has to first understand the basics of how a projected image is formed on a screen. To create a projected image, each pixel that composes it must have the following: A specific colour that is generated by a combination of the primary colours of red, green and blue, and A certain degree of brightness The way that 3LCD technology creates colour and brightness levels for each pixel is fundamentally different from the closest competing technology: 1-Chip DLP (Digital Light Processing): How a 3LCD Projector Works 1: Creating Colours from White Light Above Basic workings and components of 3LCD Projector A 3-chip Liquid Crystal Display (3LCD) projector works by first splitting the white light from the lamp into its three primary colours of red, green and blue by passing it through special dichroic filter / mirror assemblies called dichroic mirrors. Each dichroic mirror only allows specific coloured wavelengths of light to pass through while reflecting the rest away. In this way, the white light is split into its three primary colour beams and each is directed toward its own LCD panel. 2: Image Generation at the LCDs The three LCDs are the elements that receive the electronic signals to create the image which is to be projected (hence the technology s name, 3LCD ). Each pixel on an LCD is covered by liquid crystals. By changing the electrical charge given to the liquid crystals, each pixel on an LCD can be: Darkened until they are totally opaque (for full black), Lightened until they are totally transparent (allowing all the lamp light to pass through for full white), or Shaded in varying degrees of translucence (for different shades of gray) This is similar to how a digital watch s characters appear bold and black on its LCD when its battery is new, but start to fade gradually as its battery weakens. In this way, the brightness level on every pixel for each primary color can be very precisely controlled to produce the final pixel's specific color and brightness level required on the screen. Thanks to this ability to display a smooth range of brightness levels, the LCD panels of a 3LCD projector can generate very smooth image gradations.

4 3: Colour Image Recombination and Projection After each coloured light is filtered through its individual LCD panel, the beams are recombined in a dichroic prism that forms the final image which is then reflected out toward the lens. This results in images with rich and full colour, since all three basic colours are included in each pixel of the projected image at all times. How a 1-Chip DLP Projector Works DMD Colour Wheel Above Basic workings and components of 1-Chip DLP Projector 1: Creating the Image with the DMD A 1-Chip DLP projector uses a microchip known as a DMD (Digital Micromirror Device) that creates the image and uses the light from the projector s lamp to reflect it toward the lens. As its name implies, the surface of the DMD is made up of a matrix of microscopic mirrors that represents the image which is to be projected. The brightness of each pixel that is on the image is controlled by a corresponding mirror on the DMD. Each tiny mirror is mounted on a pivot that allows it to tilt toward or away from the lamp to reflect or block its light from on to the lens. To control the brightness of each pixel, the mirror either tilts fully toward the light source in an on position (for full white), away in an off position (for full black) or vibrates on and off at varying frequencies to make the human eye perceive different shades of gray. 2: Creating Colour An interesting fact is that a 1-Chip DLP projector actually projects only one colour at a time, but relies on the human mind s colour perception abilities to combine single colours that are rapidly projected in a sequential manner, into a range of colours that form the image. This is how the system works: The colour system of a 1-Chip DLP projector is composed of a dichroic spinning colour wheel that is divided into different colour sections. Basic 1-Chip DLP projectors use a colour wheel that has red green and blue sections. Advanced models may use a greater number of colours on the wheel to increase the projector s colour range, but all 1-Chip DLP projectors use a single color wheel. Each section of the colour wheel only allows certain wavelengths of light (and hence a single colour) to pass through while reflecting all other colour wavelengths away. Each colour of a pixel is created by its corresponding mirror on the DMD synchronizing its on/off state to coincide with the beam of light being passed through the required colour sections on the wheel.

5 For example, to create a yellow pixel, the mirror representing the pixel on the DMD will tilt on (i.e. tilt toward the lamp to reflect its light) only when the green and red sections of the wheel are in front of the light path, but is tilted off when the blue section of the wheel is in the light path. This rapid sequential projection of only red and green light for that pixel is then perceived by the human mind as yellow. This method of operation can be observed by shooting the projected image from a 1-Chip DLP projector with a high speed camera. 3: The Colour / Brightness Compromise To increase the brightness of images created by 1-Chip DLP projectors, some manufacturers choose to use more powerful lamps, thereby increasing power consumption. Alternatively, others add white sections of varying sizes to the colour wheel. The inclusion of a sequential flash of white light in the projected image enhances its brightness. However, the inclusion of a white section also means that there is less space on the wheel for other colours. Thus, the increase in brightness by the addition of a white section to the colour wheel is at the expense of colour reproduction. The colour wheels of five different 1-Chip DLP projectors from different manufacturers. Some use a larger white section in the wheel to increase brightness ratings at the expense of colour reproduction. 3LCD Technology Advantages Projectors based on 3LCD Technology offer users three main benefits compared to 1-Chip DLP systems: 1: Outstanding Colour and Image Gradations Due to the fact that each pixel on an image created by a 3LCD projector has all three primary colours at the same time, and that each pixel on an LCD panel can precisely control the amount of light being passed through, 3LCD projectors are able to reproduce more natural-looking and brilliant image colours and tonal gradations. 1-Chip DLP projectors are technically limited by the mirrors on the DMD that can only have an on or off state, so images produces have poorer gradations. Due to the use of a color wheel in 1-Chip DLP projectors, lamp energy is wasted in colour production as only one colour wavelength is allowed through at one time. 2: Efficient Power Use All the lamp light in a 3LCD projector is used to create the image while the colour wheel in a 1-Chip DLP system reflects all but the light wavelengths of one colour away, wasting the lamp energy. On average, 3LCD projectors use 25% less power than 1-Chip DLP projectors. (3) This also translates to lower operating heat that in turn, allows the lamp in a 3LCD projector to last longer. 3: Greater Reliability All 3LCD projectors have no moving parts involved in the image generation engine. This compares to 1-Chip DLP projectors that all need a rapidly spinning colour wheel to create colour. All 3LCD projectors are also protected by serviceable filters that effectively clean the air that is being sucked in by the fan to cool the lamp.

6 3LCD Scalability 3LCD Technology has successfully proven itself to be extremely scalable over the last two decades since its introduction to become the world s most popular projection technology. On 9 November 2009, the Seiko Epson Corporation announced the availability of the world s first 4K Compatible (4096 x 2160 resolution) HTPS TFT Liquid Crystal Panel. The world's first 4096 x 2160 resolution HTPS TFT Liquid Crystal Panel for 3LCD Projectors developed by Seiko Epson Corporation. The diagram below shows the resolution of this liquid crystal panel compared to full HD (1920 x 1080) With a resolution of nearly 8.85 megapixels, future 3LCD projectors that use these 4K panels will offer four times the resolution of full HD ( ), making them ideal for the high resolutions required by special applications such as industrial design, architectural design and simulations, as well as for presentations and projecting four full HD images at the same time. This liquid crystal panel demonstrates the high degree of scalability and constant evolution of 3LCD technology. Citations: (1) (2) (3) 3LCD Business Centre Press Release: 3LCD Achieves Projection Industry Milestone: 60 Million Chips Shipped, 12 October 2009 ( FutureSource Consulting 2010 Data source: ProjectorCentral.com Jan Comparison of 796 shipping models, all resolutions and brightness levels