The following paper gives a detailed description of the Laser Television Technology. While the complete Television system is still to come out in the commercial market, the concept has been around for a couple of years.
The first section paper first gives a basic technology description, and its similarities with the older Projection-Systems and Cathode Ray Tube television. The superiority of Laser TV over these other Technologies is also highlighted. The description then moves on to the various features of the Laser TV.
The next section gives a detailed description of the Laser TV technology and mentions the various advantages and disadvantages against other contemporary Television technologies.
The third section concentrates the description of the other contemporary Television technologies introduced in the previous section i.e. the LCD and Plasma technology.
The next section then compares the Laser Television technology with these two technologies and goes on to give the future applications of all these technologies
The final section is the conclusion which summarizes the entire paper giving recommendations as to the better technology among all.
Laser TV Technology
Introduction & Working
The primary assumption, on which a Laser Television System is based, is that “a visual screen image can be produced by the proper manipulation of a monochromatic coherent visible laser” (Laser Vision Technologies n.d. pp. 4). Hence, a Laser Television is merely a process of manipulating a Laser beam so as to produce an actual visual image.
This manipulation of the Laser beam, mentioned above, is in accordance with the basic theories of the video signal architecture. In a single line the manipulation of the Laser bean for image production can be summarized as:
“The Laser beam is encoded using the Bragg Deflection by the Acousto-optic modulators, AOM, such that when the true visual image is scanned, it would produce a replica image of the electronic video signal. This scanning is done in the horizontal direction with polygon, and in the vertical direction with galvanometers” (Laser Vision Technologies n.d. pp. 4).
Thus, in a Laser Television, an image is printed by scanning a Laser beam directly on the projection screen. The final image that is visible on the screen is due to the visual persistence in the eye. The term Laser TV is thus misleading because, only the backlight user is laser not the way the video is displayed.
In fact, the main technology of the Laser TV is the same technology which is used in general projection-television systems (Strasser 2005). However, the light is not the UHP lamp as in the earlier cases. Lasers of Red, Green, Blue colors are used instead. As these are pure colors, the quality of image and the clarity of colors are very superior to the other projection systems, which usually use UHP lamp, a white light lamp.
Features of the Laser Television
Technology & Look – The Laser TV is also known as a rear-projection TV, which is the first of its kind. It is powered by a laser using digital light processing instead of the white-lights using which are typically used in other projector TVs. Instead the present system which is Mitsubishi’s uses separate red, green and blue semiconductor lasers in combination with an HD chip. In addition, the advances in Plastic technology mean no heavy-duty screen frames, thinner screen width,1/8th of an inch. The lighter overall weight means a lower center of gravity; which means the entire front area can be used as the screen surface. This translates to a newer and compact look for the Laser TV units and also a much sleeker design than other existing TVs. The screens will also be very lightweight which means that the need for frames will also be significantly lessened. This would in the end mean a cleaner, an almost all-screen television (Laser TV News 2006)
Resolution – The resolution of a Laser TV is the same as the Plasma TV mostly, though there is a lot more clarity and an almost 75% reduction in power. For e.g. – The native resolution of a Laser TV demonstrated by the Optoelectronics manufacturer Arasor, using the Laser technology from Novalux, in November 2006, was 1920 by 1080-pixel displays (Roche 2006).
Price – The Laser displays are cheaper than the existing plasma flat screens. The correct way to describe this is – Once in production, the laser TV will cost manufacturers about half as much to produce as a plasma television (Sbrogna 2006). However, it is the discretion of the manufacturer, if and how much of these savings would be passed on to the customer.
Laser TV Specifications
As mentioned above, the working of the Laser TV is very similar to a modern day television or projection systems. In current televisions and other projection systems the cathode ray tube or UHP lamp is the source of illuminated light. In case of the cathode ray tube, the electrons are scanned across and down a screen having pixels of red, green and blue phosphors. This scanning process then produces a fill color image on the face of the CRT, which is finally viewed by the viewer (Laser Vision Technologies n.d. pp. 5). This scheme is as shown in figure below
Shadow-mask color tube (Laser Vision Technologies n.d. pp. 5)
The laser TV also uses similar elements as described above. The horizontal scanning is carried out using a spinning mirror or polygon, and the vertical scanning is carried out in the form of a galvanometers or oscillating mirror, and pure red, green and blue pixels are combined to make a final colored visual image (Laser Vision Technologies n.d. pp. 6)
Lasers are preferred here; because the display of video comes from the huge color triangle which the Laser light can reproduce. In fact, no other light sources match the reproduction with similar amounts of hue and saturation. Also, laser light is inherently monochromatic i.e. a single wavelength for that color. When this single wavelength is projected and viewed, it produces extremely deep, rich colors only matched in nature (Laser Vision Technologies n.d. pp. 6).
Video Modulation of Lasers
The most common technology used for Laser beam modulation is acousto-optic modulation AOM. This principle when is used to display video with lasers manipulates the laser beam at the pixel level of information. As the AOM’S can regulate the percentage of light needed at each pixel, they can produce an exact duplication of the video signal and also the original picture. Using this modulation technique, a very high-resolution picture could be produced the bandwidth of AOMS exceeds the present video standards. (Laser Vision Technologies n.d. pp. 8).Figure below shows the method
(Laser Vision Technologies n.d. pp. 8)
Use of electronics
Acousto-optic modulation always was superior in working. But cost and availability of TeO2, and the high frequency and power of RF driver, made the initial AOM expensive for mass production. To counter this optoelectronics were used for the prototype was started. These made the driver and in turn the cost of components much cheaper. Also it reduced the noise factor in the circuit (Laser Vision Technologies n.d. pp. 11). The following diagram shows a rough schematic of a Laser video projector using electronics
(Laser Vision Technologies n.d. pp. 12)
Advantages of Laser TV
The Laser TV, as already mentioned, has not yet been released in the commercial market. It is due in sometime in late December in 2007. The first Laser TV would be by Mitsubishi, which would be using the optoelectronic components from Arasor and Laser from Novolux. They claim that the prototype and in consequence the final product has the following advantages:
1. As against the UHP, ultra high pressure, lamps the Lasers are better for front / rear projection systems
2. Lasers based back light projection systems would be very bright
3. The Laser TVs would consume about 25% of power by Plasma or LCD TVs
4. Laser TVs would be half the weight of Plasma and LCD TVs
5. Laser TVs would be cheaper, about half that of Plasma and LCD displays
6. Laser TVs can produce twice the color content than what is generated by LCD and plasma
7. Laser TVs would produce perfect and undiluted colors allowing precise hue mixing. With this color enhancement up to 90% of the spectrum that is currently not viewable, can be brought in the viewable range.
8. They would have a long life about 50,000 hour life
Skeptics however, point out a couple of drawbacks in the Laser TVs
1. The room needs to be dark for viewing a quality picture (Sbrogna 2006)
2. While solid state Lasers have reduced the prices, the mass production scene is not as good as it being projected
3. At the time of demonstrations, some color-bleeding between the red and magenta -bars was seen which gave a Rainbow-Effect, similar to some DLP rear-projection units. This was explained as a prototype defect which is already cleared in the commercial models, but this still remains to be confirmed (Roche 2006).
Other Television Technologies
The basic principle of LCD TVs is the blocking of light.. The liquid crystals untwist depending on the voltage of the electric charge passing through them. When this happens the intensity of light passing through the second polarized plane is affected. The main principle is thus switching between the different light states and dark states, depending on whether the liquid crystals are twisted or untwisted, and a gray scale for all the middle states of the liquid crystals. In an LCD the light source is a fluorescent bulb. This emits white light via a polarized glass pane behind the liquid crystal solution. To achieve a full color pallet on the LCD TV display, each pixel is divided into three sub pixels – red, green and blue, which then work in conjunction to determine the LCD panel’s overall hue. These sub pixels are in the first place created by subtracting certain wavelengths using various filters. By using a combination of sub pixels, a single pixel triad can reproduce approximately 16.8 million colors. Figure below shows basic working of TFT LCD (Burden 2007)
(TFT LCDs 2007)
The basic principle of plasma display is to illuminate tiny colored fluorescent lights to form an image. As in can of LCD TV sub pixels, here also each pixel is made up of three fluorescent lights – red, green and blue, which change in intensities to produce a range of colors. The main element of this TV is plasma, which is a gas made up of free-flowing ions and electrons. In the plasma, when an electric current is running through it, it creates a rapid flow of charged particles, which stimulates the gas atoms to release ultraviolet photons. These released ultraviolet photons interact with phosphor material coated on the inside wall of the cell. Phosphors are essentially substances that give off light when they are exposed to other light. The ultraviolet photon hits a phosphor atom in the cell, and one of the phosphor’s electrons jumps to a higher energy level, thus heating up the atom. When this electron falls back to its normal level, it releases energy in the form of a visible light photon. Figure below shows a basic structure of the Plasma TV internals
Advantages and Disadvantages
Advantages – A very wide screen can be produced using extremely thin materials. Also because each pixel is lit individually, the image is very bright and looks good from almost every angle. Also they have Better contrast ratio, better ability to render deep blacks, more color depth, better motion tracking (response time), and more availability in very large screen sizes (Silva 2007)
Disadvantages – The image quality is below than that of best cathode ray tube sets. They are more susceptible to burn-in. Also the technology is very costly, about $4,000 – to past $20,000. It does not perform as well at higher altitudes, and shorter display life span (although this too is changing due to technology improvements), heavier weight, and more delicate to ship (Silva 2007)
Advantages – Look better in brightly lit rooms, lighter and easier wall installation, prices are lower compared to the Plasma TVs, lesser screen glare (Silva 2007)
Disadvantages – Lower contrast ratio, not as good rendering deep blacks, not as good at tracking motion, and not as common in large screen sizes above 42-inches (Silva 2007)
Comparison with other TV Technologies
The laser-based HDTV technology, introduced by Mitsubishi offers an expanded color depth and the widest color gamut possible from any display source, including LED-lighted displays. In fact, this laser-based HDTV technology produces a color gamut 1.8 times greater than that of normal LCD televisions. For stand-mounted applications, laser-based televisions will provide a more compact footprint than flat panel plasma and LCD televisions, which require stand depths of up to 15 inches at 50-inch screen sizes to stabilize relatively top-heavy glass-based displays. In contrast, laser technology will enable a lighter display product with a significantly lower center of gravity, providing improved stability in a thinner base dimension. Laser technology, in comparison to plasma and LCD flat panel, is also economically scaleable to larger screen sizes. The following working Laser TV prototype is a modified 52-inch Mitsubishi WD-52627 using optical chips and lasers to drive the display. This was compared with a 52-inch Samsung plasma, with a 1080p high-definition video was simultaneously played through both of them (Roche 2006). The figure below shows the comparison
In the discussion above the Laser TV technology was decribed. This is a supposed threat to Plasma and LCD TVs. However, it isfound that while the quality of the picture is decidedly better than the other television, the actual usage for example in different lighting sitations could be a problem. In addition the price factor is also something which has to be observed when the product is finally made in mass production and marketed.
In conclusion one can say that, the Laser TV hype, can be said to be true enough merit an avid curiosity for the product, yet it is not the perfect technology as it is made out to be, and would not be a immediate threat to the present day television technologies.
Burden J, “ How do LCD TVs work“, 2007, Article retrieved on 18th May 2007, http://www.lcdtvbuyingguide.com/lcdtelevision/2howwork.shtml
Laser TV, “ Laser TV“ , Article retrieved on 18th May 2007, http://displayblog.wordpress.com/2006/12/04/laser-tv/
“Laser TV News”, 2007, Article retrieved on 18th May 2007, http://www.lasertvnews.com/features.htm
Laser Vision Technologies, “Full Color Laser Television”, Article retrieved on 18th May 2007, http://www.osti.gov/bridge/servlets/purl/761030-VWlu6r/webviewable/761030.PDF
Plasma TV, “ The Plasma behind the Plasma TV screen “, 2007, Article retrieved on 18th May 2007, http://www.plasmatvscience.org/theinnerworkings.html
Au Optronics Corporation, “ TFT-LCD Introduction“ 2007, Article retrieved on 18th May 2007, http://www.auo.com.tw/auoDEV/technology.php?sec=tftIntro;ls=en
Roche J, “Laser TV unveiled in Australia”, 11th October 2006, Article retrieved on 18th May, http://www.cnet.com.au/tvs/0,239035250,339271573,00.htm
Sbrogna M, “Tech Journal: Laser TVs could trump current technologies”, 20th November 2006, Article retrieved on 18th May 2007, http://media.www.bcheights.com/media/storage/paper144/news/2006/11/20/Marketplace/Tech-Journal.Laser.Tvs.Could.Trump.Current.Technologies-2470222.shtml?norewrite200611211817;sourcedomain=www.bcheights.com
Silva R, “Should I buy an LCD TV Or Plasma TV”, 2007, Article retrieved on 18th May 2007, http://hometheater.about.com/od/lcdtvfaqs/f/lcdtvfaq8.htm
Strasser E, “Introduction to Laser TV”, 2005, Article retrieved on 18th May 2007, http://www.articledashboard.com/Article/Introduction-to-Laser-TV/213465
”What means Laser TV”, 2007, Article retrieved on 18th May 2007, http://www.sed-fernseher.eu/what-means-laser-tv