Cathode-Ray Storage Tube

a cathode-ray tube that is capable of storing electrical signals for a certain period of time. It is used for such purposes as recording and repeatedly reproducing transients, comparing signals (when they cannot be obtained simultaneously), detecting (selecting) moving targets in radar displays, converting radar signals into television signals, and serving as internal storage for electronic computers.

Cathode-ray storage tubes are classified into two types: those in which the recorded information is presented in the form of electrical signals (such as the graphecon) and those in which the recorded signals are converted into an image on a screen (such as the electrostatic-image storage tube). All types operate according to the following sequence: (1) preparation for recording, which includes the erasure of the previously recorded signal; (2) presentation of the signal in the form of a charge distribution (a potential relief) on the surface of a dielectric plate; (3) storage of the signal for the required period of time—the signal “memory”; and (4) the reproduction of the signal at any time—”reading” the signal.

Before recording signals on the tube’s target a uniform potential is established at all points of the target’s surface. The input signals are recorded by scanning the target’s sur-face with a recording electron beam which is modulated in intensity by the signals. As a result a potential relief is formed on the surface of the dielectric that describes a particular recording sequence of signals. The stored signal is “read” by a reading electron beam that acts as a current commutator. The points of the target are successively charged to the same potential, and currents are produced in the circuit of the signal plate that correspond to the depth of the recorded potential relief. In the image storage tube the target is made in the form of a metal grid coated with a dielectric layer. A luminescent screen located behind the target is supplied with a constant electric potential. Electrons that fly through the target grid create a luminous image on the screen of the potential relief recorded on the target. In many designs this image can be “erased” by a second (unmodulated) beam that equalizes the potential at all points on the target. In some cathode-ray storage tubes the potential relief is removed when read repeatedly and special erasing is not required. The potential relief can be stored for several days. A single recording of the information can be reproduced hundreds of times.