Assignment

Whether it's used for a conventional TV set, a computer-monitor or a workshop testing device, the construction is virtually, always the same. Since the breakthrough of television, and particularly after it became a part of our everyday lives through computer-monitors, one cannot imagine it no longer being there. Indeed, even the most successful have competition, in this case, the TFT-flat-screen and the plasma monitors.

Function

It is called the 'Braunsche Röhre' (Braun's tube or CRT - Cathode Ray Tube) and is named after it's inventor, Karl Ferdinand Braun, it is primarily made up of a hollow glass body, from which almost all the air has been pumped (high-vacuum). The spiral element (1) is connected to a power source, heated to glowing-point, and thus transmits electrons. The (negative charged) electrons are accelerated through the ring which is linked to the positive pole (2). In the above figure it is momentarily assumed that the vertical deflection (3) is also connected at the bottom with plus and at the top with minus and that the flow of electrons is now deflected downwards. The following horizontal deflection (4) is positive on the side turned towards us, and deflects the ray exactly in this direction. When the ray reaches the screen surface, a light-point is depicted.

To make a complete picture which is visible to the human eye, one only needs to supply the horizontal deflection with alternating current. The point of light then passes through an area very quickly, which is then perceived as a line or as a row. If the DC voltage is now changed for the vertical deflection after each row by a certain small amount, a picture is created. The formation of the picture depends on the circuit of the accelerator (2). Only the areas which were covered when the accelerator was switched on, are made visible. Thus, one can indeed, only by using an elaborate switching logic, make fast tension changes in engine technology visible.