SU48553A1 - Transmitting device foresight - Google Patents

Description

The present invention relates to a forward looking transmitter according to the Farnsworth dissector. According to the invention, a photosensitive layer, made in the form of a mosaic, is deposited on a semiconductor covering a metal grid located between the thermal cathode and the anode.

Variants of the proposed device are shown in FIG. 1 and 2 of the proposed drawing.

The device is a glass balloon in which a planar cathode is placed, i.e. a plate emitting electrons from its surface with a corresponding heating thereof and creating a volume charge in front of the grid 2; a photosensitive grid 2 consisting of a metal grid (base) coated with a semiconductor on which a mosaic photocell is applied; the anode 3, which in particular can be made transparent to light and having an opening, and the electrode 4, which perceives electrons, which penetrate through the opening in the anode; In particular, a secondary-electronic amplifier can be supplied instead of the electrode 4.

The principle of operation of the device is as follows. The image is projected by lens 5 onto the photosensitive grid 2. The light will pull electrons out of the photoflora and will create

some voltage between the metal base of the grid and the photolayer, so that a current flows through the semiconductor separating the metal grid from the photocell. At steady state, the voltage on the mosaic photovoltaic cells will differ from the voltage on a metal base per volt, where R is the resistance of the semiconductor, and the / -current. Such a negative voltage is applied to the metal base of the photosensitive grid so that electrons emitted by the heated cathode 7 do not fall on the photosensitive grid. The combination of electrodes 7, 2 and 5 is a kind of three-electrode lamp, the grid of which in different places has a different voltage, depending on the brightness of the image at the corresponding points. Thanks to the latter, the intensity of the current passing through different places of the grid will be different according to the image. Using the focusing roller b surrounding the balloon, one can obtain an electronic image of grid 2 in the plane of the anode 3, i.e., electrons emitted from one point of the grid plane (no matter whether there are photoelectrons or electrons emitted by plane 7), can be assembled into one point in the anode plane. If a,

Now, using additional coils 7 to move the obtained electronic image relative to the hole in the anode, then from the electrode 4, to which some positive voltage is applied relative to the anode 3, you can remove the image signals and feed them to the amplifier input. As stated above, instead of electrode 4, a secondary electronic amplifier can be supplied.

A semiconductor or insulator with some leakage, on which a photosensitive mosaic is applied, serves both to obtain a useful voltage drop on it, and to neutralize the charge that has accumulated on the photocell after the light has been applied to it.

For undistorted transmission at a rate of, for example, 25 frames per second, it is necessary that the RC time constant (where R is the leakage resistance and C is the capacity of the photoflo with respect to the metal base of the grid) is no more than / 25 sec., I.e. . sec. From here you can find the required resistance value R. Consider, for example, the capacity of a 1 cm photosensitive layer relative to a metal base is 200. 10 F, we get that the resistance of 1 cm should be

1012

25

Image decomposition can also be carried out without rtoning coils if, instead of a planar cathode, a plate is emitted that emits electrons under the influence of electron bombardment of an electronic searchlight. Then, when the electron beam moves along this plate, which can be achieved by a conventional electrostatic or electromagnetic sweep, the current to the anode 3 will change depending on the voltage of the photosensitive grid at the point opposite to the point emitting at the moment. In order to avoid image blurring, the plate / must be located sufficiently close to grid 2. The same effect can be obtained if the cathode / is replaced by a grid through which electrons of the moving electron beam pass (Fig. 2). In the latter two cases, the displacement of the emitting point on the cathode or grid / can be compensated for by the deflecting coils so that the electrons corresponding to the transmitted image element always fall into the opening of the anode B.

The subject matter of the invention.

A forward-looking transmission device according to the Farnsworth dissector, characterized in that the photosensitive layer made in the form of a mosaic is deposited on a semiconductor covering a metal grid located between the solid thermal cathode and the anode in order to continuously change the density of the continuous electron flux from the thermal cathode to the anode.

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