Thomas Goldsmith Jr. files a patent for a "Cathode Ray Tube Amusement Device", the first ever electronic game.

Thomas Toliver Goldsmith Jr.: A Pioneer of Television and Interactive Entertainment

Thomas Toliver Goldsmith Jr. (January 9, 1910 – March 5, 2009) was a truly influential American figure, widely recognized as a pivotal television pioneer and a distinguished professor of physics at Furman University. His most notable contribution to technological history, however, lies in his co-invention of the groundbreaking cathode-ray tube (CRT) amusement device. Developed in 1947 with Estle Ray Mann, this innovative creation is widely acknowledged by historians and enthusiasts alike as one of the earliest electronic games, laying foundational groundwork for the vast interactive entertainment industry we know today.

Understanding the Cathode-Ray Tube (CRT)

At its core, a cathode-ray tube (CRT) is a specialized vacuum tube designed to display images. It houses one or more electron guns which are responsible for emitting precise electron beams. These beams are then meticulously manipulated to project images onto a phosphorescent screen, which glows when struck by the electrons. The versatility of CRTs allowed them to display a wide range of visual information, including:

On a television set, the CRT component was so central to its function that it was commonly referred to as the "picture tube." Beyond visual displays, CRTs also found application as memory devices in early computing systems, where the screen was not intended for direct human observation but rather for data storage via persistent phosphorescence or other electron beam effects. Historically, the term "cathode ray" was coined to describe these mysterious beams when they were first discovered, long before scientists fully understood that they were, in fact, streams of electrons.

How CRTs Generate Images: Raster Scanning and Deflection

In CRT-based television sets and computer monitors, the entire front surface of the tube is systematically scanned by the electron beam in a precise, fixed pattern known as a raster. This repetitive scanning, typically occurring at high frequencies (e.g., 60 times per second for NTSC television), creates the illusion of a continuous moving image.

For color displays, the process becomes more intricate: an image is formed by precisely controlling the intensity of three separate electron beams. Each beam corresponds to one of the additive primary colors – red, green, and blue (RGB). A video signal acts as a reference, dictating the individual intensity of each beam at every point on the screen. This allows for the faithful reproduction of a full spectrum of colors when these primary colors are mixed. In most modern (pre-flat-panel era) CRT monitors and televisions, these electron beams are precisely steered and bent across the screen using magnetic deflection, facilitated by a component called a deflection yoke. In contrast, electrostatic deflection, which uses charged plates to manipulate the beams, was more commonly employed in oscilloscopes due to its higher precision and faster response for waveform visualization.

Physical Characteristics and Safety Considerations of CRTs

CRTs are inherently distinctive in their physical design. They consist of a robust glass envelope that is deep (meaning it extends significantly from the front screen face to its rear end), heavy, and relatively fragile. The interior of this glass enclosure is maintained at an extremely high vacuum, typically ranging from approximately 0.01 pascals (equivalent to about 9.9 x 10-8 atmospheres) down to 133 nanopascals (a mere 1.3 x 10-12 atmospheres). This near-perfect vacuum is crucial as it facilitates the unimpeded flight of electrons from the electron gun(s) to the tube's phosphorescent face, preventing them from scattering or being obstructed by collisions with air molecules.

Given this high vacuum, handling a CRT requires caution. Any significant damage to the glass envelope carries the risk of a violent implosion, a rapid inward collapse caused by the immense external atmospheric pressure. Such an event can hurl glass fragments at considerable velocity, posing a serious safety hazard. To mitigate this risk and other potential dangers, the front face of a CRT is typically constructed from thick lead glass or specialized barium-strontium glass. These materials are engineered to be shatter-resistant and, critically, to effectively block the majority of X-ray emissions that are a byproduct of the electron beams impacting the screen at high velocities. It is worth noting that the CRT itself typically constituted the bulk of the weight in a traditional CRT television or computer monitor.

The Decline of CRT Technology and the Rise of Flat-Panel Displays

Beginning in the early 2010s, cathode-ray tube technology began to be largely superseded by a new generation of flat-panel display technologies. These include Liquid Crystal Displays (LCDs), plasma display panels, and Organic Light-Emitting Diode (OLED) displays. This transition marked a significant shift in the consumer electronics landscape for several compelling reasons:

Detailed Working Principle of a Cathode-Ray Tube

The intricate process by which a CRT generates light and images involves several key stages:

  1. Electron Emission: The process begins in the rear of the CRT with an electrically heated tungsten coil. This coil, acting as a filament, heats a small metal cylinder called the cathode. The heat causes the cathode to emit a steady stream of electrons through a process known as thermionic emission.
  2. Modulation and Focusing: As electrons are emitted, they pass through a series of control electrodes. These electrodes modulate the electron beam's intensity (controlling brightness) and focus it into a tight, precise beam.
  3. Acceleration: Further along the tube, a high-voltage anode, charged positively, strongly attracts the negatively charged electron beam, accelerating it to very high velocities towards the screen.
  4. Steering (Deflection): Before reaching the screen, the accelerated electron beam passes through deflection coils (for magnetic deflection) or deflection plates (for electrostatic deflection). These components create magnetic fields or electric fields, respectively, which precisely steer the electron beam both horizontally and vertically across the screen's surface.
  5. Light Generation: Finally, the high-velocity electron beam strikes the inner surface of the CRT's front screen. This surface is coated with a phosphorescent material (phosphor). When the electrons impact the phosphor, their kinetic energy is converted into light, causing the phosphor to glow and create a visible point of light, which collectively forms the displayed image.

Frequently Asked Questions About Cathode-Ray Tubes (CRTs)

Who was Thomas Toliver Goldsmith Jr.?
Thomas Toliver Goldsmith Jr. was an American physicist and television pioneer. He is best known as the co-inventor of the cathode-ray tube amusement device, considered one of the earliest electronic games, and served as a professor of physics at Furman University.
What is a Cathode-Ray Tube (CRT)?
A Cathode-Ray Tube (CRT) is a vacuum tube containing electron guns that emit beams directed onto a phosphorescent screen to display images. It was the primary display technology for televisions and computer monitors for decades.
How does a CRT produce an image?
A CRT produces an image by electrically heating a cathode to emit electrons. These electrons are then modulated, focused, accelerated by an anode, and steered by deflection coils or plates. When the high-velocity electron beams strike the phosphor-coated screen, the phosphor glows, creating visible light points that form the image.
Why did CRTs become obsolete?
CRTs became largely obsolete starting in the early 2010s because newer flat-panel display technologies (LCD, plasma, OLED) offered numerous advantages. These included lower manufacturing costs, reduced power consumption, significantly lighter weight, much thinner profiles, and the ability to produce much larger screen sizes.
Is handling a CRT dangerous?
Yes, handling CRTs requires caution due to the extreme vacuum inside. If the glass envelope is compromised, it can lead to a violent implosion, causing glass fragments to be propelled at high speed. Additionally, older CRTs can emit some X-rays, though their thick leaded glass faces are designed to block most of them.