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4-2 The working principle of the Vidicon type camera tube: This camera is used for closed-circuit television (CCTV) and for filming movies and so on. Some types of (Vidicon) can also be used in dark places or under direct sunlight - Figure (2) - 11) The RCA valve shows a diameter ranging between 3.8-127 cm and a total length of 203-89 cm.
As for the parts of this valve, they are: It consists of a flat glass lens, behind it is the target plate, and a cathode electronic ejector that emits the electronic beam, and it has several networks for control and focus. As for the outer section, it contains the horizontal and vertical deflection files, the beam guide files and the focusing files, as in Figure (12-2). The target plate contains a very thin layer of phototransmitting material

It is tube type, and the photosensitive layer includes allantoin and selenium. The important feature of this article. Its resistance decreases as the intensity of the light shining on it increases. In the dark, its resistance reaches 20 megohms, and in light it decreases to about 2 megohms. Each point on the target plate has a resistance that is commensurate with the intensity of the light shining on it from the opposite point in the image. It is as if the image on it is drawn on the target plate in the form of a change in the resistance of each point, as in Figure (13-2) and (2-14). The black point in the image has a resistance of (20) megohms, and the white point has a resistance of (2) megohms). In the receiver with the same number (625 errors) in the European system used by us, and it is transformed into a radio signal that has a large amplitude in .

From it, the output signal is taken and a voltage ranging from (10 to 60 volts) is applied to it, depending on

The white dots and a small broadening in the black dots of the winding deflection correction
The working principle of the plumbecon camera tube: This type was developed by the Dutch company Philips. It is characterized by its light weight, small size, and high sensitivity. It produces good-clear images even in low light, and it consumes little electrical energy, which made it commonly used in various television cameras for different purposes. Figure (2) - (15) shows several measurements of them.

Figure (2) - (15) different types of bluebecon tubes, compare with the total length of the ruler 6 inches. The Plumbecon type is very similar to the Videcon type in most of its parts, where the beam is centered and deflected by magnetic coils in both types. The point of difference between them is the Target plate, which is located behind the front glass lens Figure (2)-16 and covers the face The back of the glass is covered with a thin transparent layer of tin dioxide (No) to form the sign board, then a layer of lead oxide (Pb0) with optical conductivity is placed on the side of the scanning surface of the sign board. Then another layer of lead dioxide is placed, and thus the three layers of different conductivity are formed - the first is type N and the second is type P, forming what is called a diode with
Link (P-I-N). When the image of the scene is drawn on the lens of the Plumbecon tube, the light passes through the transparent layer (tin dioxide), and each element in the image has a corresponding spot in the sensitive layers, each of which represents a small capacitor charged with a charge proportional to the illumination of the image element. The negative is the layer, so the passing of the scanning ray at each point leads to a change in the output current of the target plate