SU658775A1 - Method of selective erasing of signal in bistable storage crt - Google Patents

Description

I

The invention relates to radio engineering and can be used in information display devices.

The known method of sampling. erasing the Signal in a bistable storage tube with a VISIBLE image by irradiating the entire target surface with a defocused repetitive electron beam 1.

However, in the known method, the accuracy of selective signal erasure is low.

The purpose of the invention is to improve the accuracy of selective signal erasure.

To do this, in the method of selectively erasing a signal in a bistable memory, to her an electron beam tube with a visible image by irradiating the entire target surface with a defocused electron reproduction beam, a part of the defocusing electron reproduction beam is focused to a five to tenfold increase in beam current density compared to its average density and is fed to a target. a negative pulse with an amplitude equal to the slave voltage across the collector with a duration of 5 -50 msec, and the ratio

between the duration of the front and rear edges of the negative pulse is not less than 1:10.

FIG. 1 shows a schematic representation of a device implementing the prepositional method; in fig. Figure 2 shows the curve for the dependence of the secondary electron emission coefficient eS on the energy of the electron beam of a reproducing projector.

The essence of the method of selectively wiping a signal into a bistable memory of a cathode ray tube with a visible image is as follows.

The entire surface of the target is irradiated with a defocused repetitive electron beam, focused on the target site, which is selectively erased, and a part of the defocused repetitive electron beam is focused in the selected target site to a five to tenfold increase in the beam current density compared to its average density and a negative pulse is fed to the target or collector with an amplitude equal to the working voltage at the collector, with a duration of 5-50 ms, and the ratio between

the duration of the front and rear fronts of the detector) the south impulse is not less than 1:10.

A device that implements the proposed method contains a bistable memory cathode ray tube 1 with a deviation yuphei system 2 and an external focusing device 3.

The bistable storage electron beam tube 1 contains a glass shell 4 a target 5 with a dielectric surface b a recording spotlight 7, a reproducing spotlight 8, a screen 9, a collector 10 and a collimation lens 11.

In addition, in FIG. 1 shows a portion 12 of a target 5 in which a selective erasure of a signal occurs, a defocused reproducing electron beam 13 formed by a reproducing projector 8 and recording an electron beam 14.

The entire dielectric surface 6 of target 5 is irradiated with a defocused repetitive electron beam 13, and using a recording electron beam 14 creates a positive potential relief on target 5, which corresponds to the law of deflection of the recording electron beam 14 along the dielectric surface of the target 5. Selective deletion of information is produced by focusing part of the defocused reproducing electron beam 13 using an external focusing device 3 mounted in front of the screen 9 opposite section 12 of the mission5, where it is necessary to make a lot of information. Then a part of the defocused reproducing electron beam 13 is focused to a five to tenfold increase in the current density in the plane of the shadow 5 compared to the average density of the reproducing beam 13, which irradiates the entire surface of the target 5.

A significant increase in the density of the reproducing beam 13 in the area 12 of the target 5, on which information needs to be erased, is due to the fact that the time required to erase the recorded positive relief with a repetitive flow of electrons at an energy corresponding to a potential lower than Uupi (Fig. 2) , inversely proportional to the current density of the reproducing beam. Therefore, the focusing of the part of the reproducing beam 13, and consequently, a significant increase in the current density of the electrons of the reproducing illuminator 8 in the area 12 of the target 5, is necessary so that to erase the information in the section 12 of the target 5 it takes several times less time than for erasing information on the remaining surface of target 5. Then, target 5 {or collector 10) is given a short (5-50 ms) negative impulse with an amplitude equal to the operating voltage of collector 10 with steep anterior and gentler falling edges.

The use of such a pulse is due to the fact that the absolute amplitude of the pulse must be obviously greater than the first critical potential, taking into account its spread + AVtipi (Fig. 2) over the dielectric surface 6 of the target 5. Since the working voltage of the collector 10 the dielectric surface 6 of the target 5, the amplitude of the erase pulse, it is advisable to set equal to the working voltage of the collector. The rear front of the firing pulse should be gentle; Otherwise, due to the capacitive coupling of the target-collector, at the end of the erasing pulse with a steep falling edge, the dielectric surface 6 of target 5 will recharge to the potential of the collector 10.

If the leading edge of the pulse is more than 10% of the back, then it is difficult to establish such a minimum pulse length of km, at which information will be erased. This causes the use of a pulse with a steep leading edge.

The reproducing electron flow begins to erase information, provided that the positive potential relief is approximately equal to the potential of the collector 10 and c. corresponding to the recorded information, the target 5 - dielectric surface b will be displaced due to the communication capacitance by means of a negative impulse applied to the target 5 to the cathode potential of the reproducing floodlight 8. Erasing information is possible and subject to supplying the same negative impulse to the collector 10.

When performing the specified sequence of actions and applying a short (5-50-ms) pulse, the recorded potential relief in the selected section J2 of target 5 will be reduced, and on the rest of the dielectric surface 6 of the target 5 to 1 n 1 / np (Fig. 2). the pulse, the reproducing electron beam 13. will bring the potential UH in the selected section 12 of target 5 to zero, and the potential of the dielectric surface b of target 5, on which it is necessary to preserve previously, the recorded information will restore to the potential and the torus 10 (FIG. 2). The result will be a selective erasure of information.

Thus, the proposed method allows controlling the accuracy of the installation of a reproducing electron beam at a given target site and the quality of sequential erasing of information recorded on the target as separate numbers, signs, graphs and simultaneously watching information that is not subject to selective erasure.

Claims (1)

1. USSR author's certificate r 568982, cl. H 01 J 31/08, 1973. rir ftfj.Z