KINESCOPE

The kinescope is a device consisting in a cathode ray tube that allows the reproduction of still or moving images. The images are formed by conveying an electron beam on a photosensitive surface.

INSIGHTS

The cathode ray tube was invented in the early 1870s by William Crooke and was initially intended for laboratory use. It was then widely used in televisions and monitors, until the advent of LCD display panels.
A cathode ray tube consists in a cathode, an anode, a series of grids and a deflection system, all enclosed inside a thermionic tube. The cathode is a metallic element which - if heated to incandescence - emits electrons due to the thermionic effect. The electrons are then accelerated by the difference in electrical potential existing between the cathode and the anode, and they are focused in a beam thanks to a series of grids. The beam is then deflected by the action of magnetic fields or electric fields, in order to hit the desired area of the internal surface of the screen. This surface is coated with fluorescent material that emits light when hit by electrons.
Initially, the fluorescent material was zinc fluoride, and the images being produced were in black and white. Afterwards, the availability of fluorescent material in the three primary colors (red, green and blue) allowed the creation of color cathode-ray tubes.