The word "picturetube" refers to a vacuum tube used in early television sets to display images. Its spelling can be explained using IPA phonetic transcription. The first syllable "pic" is pronounced as [pɪk], with a short "i" sound and a hard "k" at the end. The second syllable "ture" is pronounced as [tʃʊr], with a "ch" sound and a "u" sound that is shorter than "oo". The final syllable "tube" is pronounced as [tjuːb], with a "t" sound and a "yoo" sound that is longer than "u".
A picture tube is a device found in older television sets and computer monitors that converts electronic signals into visual images. Also known as a cathode ray tube (CRT), it is composed of several key components responsible for producing the pictures that are displayed on the screen.
At the heart of the picture tube is a vacuum-sealed glass cylinder, which houses an electron gun and a fluorescent screen. The electron gun consists of a heated cathode that emits a stream of high-energy electrons when heated. These electrons are then accelerated and focused into a narrow beam by various electrodes.
When the electron beam is directed towards the fluorescent screen, it interacts with phosphor compounds that coat the inner surface of the screen. These phosphors emit light when excited by the bombardment of electrons, producing the visual image that we perceive.
The picture tube also contains magnetic coils, known as deflection coils, which control the movement of the electron beam across the screen. These coils generate magnetic fields that can be adjusted to steer the beam horizontally and vertically, allowing for the creation of different shapes and positions of the displayed image.
Picture tubes have been largely replaced by more modern technologies, such as liquid crystal displays (LCDs) and light-emitting diodes (LEDs). However, they played a significant role in home entertainment for many decades and continue to be used in specific applications, such as in some professional-grade monitors and specialty devices.
The word "picture tube" is a compound word made up of "picture" and "tube". Here is the etymology of each:
- "Picture" comes from the Latin word "pictura", which means a painting or a depiction. It was first used in English in the 15th century to refer to a painting or a representation. Over time, it expanded its meaning to include a visual representation captured through photography or other means.
- "Tube" comes from the Latin word "tubus", which means a pipe or a cylindrical vessel. It entered English in the mid-17th century and originally referred to a long, hollow cylinder made of metal or other materials.
The term "picture tube" specifically refers to a cathode ray tube (CRT) that was used in older television sets and computer monitors to display images.