A cathode ray tube (CRT) is a type of analog display device. It is a special, electronic vacuum tube that uses a focused electron beam to display images. Though tubes of this type are used for many purposes, CRTs are most famous for their use in such things as televisions, oscilloscopes, computer and radar displays, and automated teller machines. They are also used in video game equipment.
A cathode or negatively charged terminal in a cathode ray tube is a heated filament, much like the filament seen in a light bulb. The filament is contained inside a vacuum within a glass tube. Inside the tube, a beam of electrons is allowed to flow from the filament into the vacuum. The flow of the electrons is natural, not forced.
When used inside a television set, a CRT’s electrons are concentrated into a tight beam by a positively charged terminal, called an anode. An accelerating anode is then used to speed up the movement of the electrons. These fast-moving electrons fly through the tube’s vacuum, hitting the phosphor-coated screen and making it glow.
A German physicist named Karl Ferdinand Braun is credited with inventing the cathode ray tube in 1897. His invention consisted of a tube with a fluorescent screen. This new technology was called a cathode ray oscilloscope. The screen of this tube would display a light when a beam of electrons touched it. Braun’s cathode ray oscilloscope is considered the predecessor of modern tubes used in television sets.
In 1929, Vladimir Kosma Zworykin created another type of CRT. Called the kinescope, it was designed for used with some of the earliest televisions. Two years later, Allen B. Du Mont introduced the first tube that was considered practical for use in a television set. It was also more durable than some of the previously introduced CRTs.
The cathode ray tube still plays a major part in television sets and many other electronic devices. However, there have been many new developments in display technology, such as plasma screens, liquid crystal display televisions (LCD TVs), and digital light processing (DLP) devices. Organic light-emitting diode (OLED) displays are also used to produce images. Still, the CRT maintains its popularity in television systems, as evidenced by the fact that the television is frequently referred to as “the tube.”