Television Production

ABSTRACT

Television has been an excellent medium for entertainment and information ever since the invention of the electron scanning tube in 1923 by Vladimir Kosma Zworykin, who is considered the father of the modern television. With the conversion to digital format 1080i in 1998, there has been a boom in the production of different types and technologies for Televisions. A new generation of televisions has been developed, including liquid crystal display (LCD), rear projection, and high definition that provide amazing visual characteristics and can be integrated in to a home theater system. As the technology behind these televisions decreases in costs, more companies are entering the market. DLH Visions is a company that has a vision for producing three types of high quality visual displays. This paper will explain the plan for the production of CRT, LCD, and DLP rear-projection Television sets.

INTRODUCTION

Television is not a post World War II achievement only a conquest of the mass media. Well over a century has passed since research on television technology first began. The first successful television demonstrations occurred in both the United States and Britain over fifty years ago. Moreover, forty years have gone by since the Federal Communications Commission authorized commercial television and stations began broadcasting on current American monochromatic standards. On the eve of the Japanese attack on Pearl Harbor, in December 1941, an integrated television system, technology, programming requirements, financing, and industry standards had been fully developed and was ready for public consumption. Only the war delayed its triumph in the mass market.

The origins of what would become the present television system can be traced back at least as far as the scanning disk of Paul Nipkow of 1885. All practical television systems use the fundamental idea of scanning an image to produce a time series signal representation which is then transmitted to a device which reverses the scanning process and which relies on the human eye to integrate the result into a coherent image again. While electromechanical techniques were developed extensively prior to World War II, most notably by John Logie Baird, all-electronic television systems relied on the inventions of Philo Taylor Farnsworth, Vladimir Zworykin and others to produce a system suitable for mass distribution of television programming. Commercial broadcast programming, following years of experimental broadcasts seen only in a few specially-equipped homes, occurred in both the United States, and the United Kingdom before World War II. The first regular high-definition television broadcasts (240+ lines) were made in England in 1936. Television did not become commonplace in homes until the middle 1950s. While North American over-the-air broadcasting was originally free of direct cost to the consumer and supported primarily by advertising revenue, increasingly television consumers obtain their programming by subscription to cable television systems or direct-to-home satellite transmissions.

CATHODE RAY TUBE (CRT)

History/Background

Electronic television is based on the development of the cathode ray tube CRT, which is the picture tube, found in modern television sets. A cathode ray tube or CRT is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface. Television sets, computers, automated teller machines, video game machines, video cameras, monitors, oscilloscopes and radar displays all contain cathode ray tubes. Phosphor screens using multiple beams of electrons have allowed CRTs to display millions of colors. [7]

The first cathode ray tube scanning device was invented by the German scientist Karl Ferdinand Braun in 1897. Braun introduced a CRT with a fluorescent screen, known as the cathode ray oscilloscope. The screen would emit a visible light when struck by a beam of electrons. In 1907, the Russian scientist Boris Rosing used a CRT in the receiver of a television system that, at the camera end, made use of mirror-drum scanning. Rosing transmitted crude geometrical patterns onto the television screen and was the first inventor to do so using a CRT. The first practical signal generating tubes were invented by Vladimir K. Zworykin and Philo T. Farnsworth. Zworykin invented the iconoscope, which became the imaging iconoscope. Farnsworth invented the image dissector.

Present Day

Almost all TVs in use today rely on cathode ray tube to display images. LCDs and plasma displays are sometimes seen, but they are still rare when compared to CRTs. It is even possible to make a television screen out of thousands of ordinary 60-watt light bulbs. It is possible to see at a football event, scoreboard. CRTs are the most common way of displaying images today.

The terms anode and cathode are used in electronics as synonyms for positive and negative terminals. For example, one could refer to the positive terminal of a battery as the anode and the negative terminal as the cathode.

In a cathode ray tube, the "cathode" is a heated filament (not unlike the filament in a normal light bulb). The heated filament is in a vacuum created inside a glass "tube." The "ray" is a stream of electrons that naturally pour off a heated cathode into the vacuum.

Figure 1 Inside a Cathode Ray Tube

Electrons are negative. The anode is positive, so it attracts the electrons pouring off the cathode. In a television cathode ray tube, the stream of electrons is focused by a focusing anode into a tight beam and then accelerated by an accelerating anode. This tight, high-speed beam of electrons flies through the vacuum in the tube and hits the flat screen at the other end of the tube. This screen is coated with phosphor, which glows when struck by the beam. [8]

There is a cathode and a pair (or more) of anodes. There is the phosphor-coated screen. There is a conductive coating inside the tube to soak up the electrons at the screen-end of the tube. However, in Figure 1, one can see no way to "steer" the beam. The beam will always land in a tiny dot right in the center of the screen.

That is why; if one look inside any TV set, they will find that the tube is wrapped in coils of wires.

The steering coils are simply copper windings. These coils are able to create magnetic fields inside the tube, and the electron