View of a picture tube neck with a system installed at an angle However, this construction could not prevail because of the difficult to control, permanent sealing of the vacuum between the metal cone and the glass screen, as well as for reasons of insulation. There are also tube models in which the cone itself is made of metal and in turn is at anode potential. This outer layer, together with the inner anode coating, forms a capacitor for smoothing the anode voltage. ĭepending on the type of tube, the outside of the glass bulb is often covered with a thin, grounded graphite layer on the conical part in order to protect the rest of the device from charge equalization processes (see Faraday cage ). It also prevents the ion spot from forming. On the one hand, the aluminum layer increases the achievable brightness (light falling inwards from the luminous layer is reflected) and, on the other hand, the achievable contrast (dark areas are no longer brightened by scattered light in the bulb).
The luminescent screen with aluminum backing on picture tubes and (on color picture tubes ) the perforated or slotted mask are also at anode potential. This consists of minerals which, when bombarded by electrons, either emit visible light or, in special cases, absorb light incident from outside to a greater extent.
It surrounds the cathode like a pot and has a small hole in its bottom facing the screen through which the beam can exit. The Wehnelt cylinder is used to control the brightness, but is also intended to prevent the electron beam from diverging (diverging) immediately after its generation. The larger the bulb of the tube, the more stable it has to be, which is achieved by a correspondingly thicker glass bulb wall. 1 bar, which clearly corresponds to a load of one kilogram per square centimeter of the bulb. The empty glass bulb is under the not inconsiderable air pressure of approx. The cathode ray tube consists of a closed, evacuated glass bulb with a hot cathode, the Wehnelt cylinder located in front of the cathode, several focusing electrodes and an anode. Manfred von Ardenne has made great contributions to the further development of the Braun tube into a television set, the scanning electron microscope and powerful electron beam sources for industrial applications.Įxternal magnetic fields affect the deflection and color display of a three-color cathode ray tube Therefore, he is considered the father of Japanese television. He later succeeded in the first electronic transmission of a human face. ) He first transmitted a Japanese character with the help of a Braun tube. (Before that there were televisions with mechanical image decomposition, see also mechanical television. Kenjiro Takayanagi built the first black and white television with a picture tube in 1926. This did not prevent Dieckmann from using a Nipkow disk to display mechanically scanned metal templates as shadow images on the picture tube in an experimental setup. Max Dieckmann suggested the use of cathode ray tubes for television as early as 1906, Braun dismissed this idea as "nonsense like the perpetual motion machine ". At first it was not known that the radiation emanating from the cathode consists of electrons, which is why the term cathode rays was used for it. The cathode ray tube with deflection of the beam in horizontal and vertical directions was developed by Ferdinand Braun in 1897, which is why it is also called the Braun tube.
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