Kin Piu Lam



Kin Piu Lam

Mario Vargas

EE3414 – Multimedia Communication Systems

May 12, 2003

Television for the Twenty-First Century

Project Plan:

For our term project we took an in-depth look at the development of the television. Our goal was to gain a better understanding of the origins of the television; where we today, how we got here and where it looks we’ll be in future years. For the first month we tried to research as much as possible, everything we could get our hands on about television including reading articles from magazines, newspapers, websites, and books. Once we thought we had enough information we pooled it together and decided on which direction we would focus in. Our plan was to write the paper first as if it were any ordinary term paper and then translate it into a presentation we could give in class.

Abstract:

The development of television and the numerous important developments that impacted the production of television have continued since the late nineteenth century. We will look at how the different types of televisions available to us today work and survey their present status in an attempt to predict what is to come in the following years. Before we can do this, we need to see how the first televisions came about to obtain a better understanding of how this product evolved.

History:

The first television patented was by a German engineering student, Paul Nipkow in 1884. It was unsuccessful because the television was too blurry. He did discover that “the light intensities of small portions of an image are successively analyzed and transmitted” and that selenium can be manipulated to provide the variation in electrical current needed to create different light intensities. No one knows for sure if he developed a prototype because he needed the amplification tube to be developed before his invention could become practical. A number of mechanical televisions were produced from the 1920s to the 1930s but none were really successfully.

In 1897, the first cathode-ray tube (CRT) was constructed by a German scientist, Karl Ferdinand Braun and was first demonstrated in 1905. The CRTs in television sets work by shooting electrons out of a glass tube onto the phosphor-coated screen, phosphor is any substance that emits light when exposed to radiation such as elections. These tubes moved the television industry into a new era, the electronic television period. In fact even today we are still using the tube television in most of our homes, proving how drastic this invention had on the development of the television. When first acknowledged the electronic television did not become very popular due to the Great Depression and shortly after World War II. The time after WWII was then considered the Golden Age for television due to the fact that people were now spending and everyone wanted a television in there apartment, unfortunately they had to experience it in black and white.

The next step was a television with color. Color television is possible by using simple three primary colors; red, green, and blue. According to the trichromatic color mixing theory, mixing the right proportion of each of these three colors will create any color in the visible spectrum. Three methods were proposed and implemented to their different extents. Columbia Broadcasting Systems (CBS), formed in 1927, tried the Field Sequential method which utilizes a black and white receiver sandwiched between two rotating color wheels to create a color image; however this approach did not succeed very much due to the fact that it was incompatible with many black and white sets at home. The Radio Corporation of America, formed in 1919, used the Dot Sequential approach. The three basic colors were sampled one after another using high speed time-division multiplexing instead of sampling all three colors simultaneously. The original image was sampled using this time division multiplexing and split into three images; luminance, chrominance A, and chrominance B. The black and white televisions already at home used only the luminance picture and the newer color televisions used a combination of the three images.

Later the Color Television Incorporated (CPI) proposed an alternative method called Line Sequential technique. It uses a similar approach as Dot Sequential, just that instead of scanning pixels, it scanned lines of an image for the three primary colors and combined two fields of this line by line scanning to create the picture in color. At first, the Field Sequential method was adopted by the Federal Communications Commission (FCC) but after it failed, the Dot Sequential technique was adopted with some improvements by the NTSC from the RCA’s original proposal. Using some new ideas and abandoning some old ones, NTSC improved the quality of the image produced enormously and obtained the FCC’s approval only a few years after the initiate proposal by RCA was deemed inadequate.

Now that color was established the size of the picture became much more important and the development shifted in terms of size. When we view a movie on our TV set at home we always read the following caption before the movie begins, “This film has been modified from its original version. It has been formatted to fit your screen.” What this means is that originally the film was intended to be viewed in a movie theater on a wide screen. The problem was that most of our television sets are square and so the picture had to be literally cut off at the ends to fit our TV. To gain back some of what was lost we had the development of High Definition Television or HDTV in 1998. The previous aspect ratio standard used by the NTSC was a 3:4 ratio. What this meant is that for every three pixels in height there were 4 pixels in length. HDTV took advantage of our natural field of vision, which is more rectangular than square and gave a much stronger visual impact. They increased there aspect ratio size to 9:16. Using HDTV the pixels were much smaller than those previously used. 1 NTSC pixel was equivalent to 4.5 HDTV pixels, which meant more pixels per inch creating a smoother picture with a higher resolution. (Not all televisions can support HDTV). With the demand for larger television sets we had the introduction of projection television which was no different from regular television just that they were usually 40’ or larger. This introduction was mainly used to boast sales and act as if something new had been invented when really it was merely a size increase.

Future:

We now move on to some of the more newer technologies like, plasma, digital light processing (DLP), liquid-crystal display (LCD), and liquid crystal on silicon (LCoS), which are leaving tube televisions behind. These four types of television show the most promise in replacing the old CRT (tube) televisions. Below we describe how each of the four televisions function in order from least likely to most likely to take over the television market.

What makes these televisions better than the old fashion tube television? It’s very simple indeed, tube televisions are bulky and unpleasant to look at. Consumers want lighter and more elegant televisions so the companies are all trying to satisfy this enormous demand. Also, tube televisions need to be realigned periodically to keep the image sharp while fixed-pixel display televisions do not. Before we go any further, keep in mind that all four of the following televisions are fixed-pixel televisions and therefore, also thinner than CRT televisions.

LCD television works by exerting voltage to liquid crystal-filled sub-pixels coated with red, green, and blue phosphors which untwists to a precise degree to allow the right amount of light to pass through. They are the least likely candidate to take control of the television market because they have trouble displaying the color black. This problem is caused by some light always being able to pass through the liquid crystal. They do work well on computers because the quality of the image is not as demanding as in television. In fact, they have are already been in wide use for some time now, the most obvious one is the fact that every student in Poly has a laptop which uses an LCD screen.

Plasma television works by filling sub-pixels with gas covered with red, green, and blue phosphors and jolting them with different amounts of voltages supplied by the address electrode. The voltage stirs up the gas and thereby, stimulates the phosphors to produce colored light. Although it also has the same problem as LCD by not producing a true black and an image can be permanently be engraved onto the screen if an image is left unchanged for hours; its wide viewing angle and large screen size do help its cause. New research shows the development of a new technology called a “pixel orbiter”, which does what it says to avoid burn-in, making it a better television than LCD.

The second to best is the DLP, which uses a Digital Micromirror Device (DMD) made up of approximately a million mirrors to reflect light from a lamp onto a screen. Depending on the consumer, they can purchase the cheaper model which only possesses one chip that reflects white light through a color wheel or the more expensive model which possesses three chips for each primary color. An obvious question one can ask is: do we need to realign the television periodically, like the CRT? No, because the chip is not prone to aging. This set is better than the other two because it produces better dark color and quality pictures and also does not suffer from burn-in. Still, the single-chip DLP television set’s color wheel may not spin fast enough, so you can see streaks of color if you look close enough. Obviously, making a faster wheel can reduce to rainbow effect and that is what is being done.

Finally, our choice for the most likely television to replace tube televisions is LCoS. It works by combining both the LCD and DLP methods into one. Instead of glass around the liquid crystal-filled sub-pixels, silicon is used and light is reflected of one chip or three chips onto a screen. Also, if one chip is used, a color wheel or a prism is used to separate the light beam. We believe it is the most likely type of television to work out because it has higher resolution and lower pixel spacing than most LCD and DLP television. This is most important because it can display enough detail for high definition television (HDTV), which I foresee as a must within the next five years. The prism also eliminates the rainbow effect plaguing color wheel televisions. Upon further study, we also noticed a number of companies interested in this new technology. Therefore, we believe LCoS televisions are going to become a big item in the future.

Many people also believe that the best use of our technology is threw the use of enhanced television with interactivity. Viewers will be able to passively watch TV, but customize it to make it there own. Enhanced television is not a new technology, experiments by TCI and Time Warner in the 1980’s demonstrated how people could shop online, play games versus others across town and many other things. Testers found the service very useful however it failed to the inability of the companies to cover the cost of operating the service while keeping the prices reasonable for consumers. History has shown that their downfall was the use of an external network line to transmit the data; however with current digital television and higher bit rates we will soon see a convergence of TV and computers. Not only will TV’s receive an audio and a video signal but also a data signal embedding the interactivity inside the broadcast signal in turn producing a cheaper active television. These are some of the more promising developments we should be seeing in the near future.

List of References

Genova, Tom. “Television History: The First 75 Years”, April 9, 2001, April 23, 2003

Reitan, Ed. “Ed Reitan’s Color Television History”, January 12,1997, May 3, 2003,

“Adventures in Cybersound: The Nipkow Disk”, May 1, 2003,

Brain, Marshall “How Television Works” May 1, 2003,

Reiman, R. J. “Who Invented Television?” April 22, 2003

Donnelly, David “Color Television” May 5, 2003

“Digital Television: A Cringley Crash Course” May1, 2003

- Katzmaier, David “Totally Tubeless”, Sound Vision, May 2003

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