US2793310A - Electric discharge tube comprising a plurality of electron beams - Google Patents

Description

May 21, 1957 G. H. P. ALMA 2,793,310

ELECTRIC DISCHARGE TUBE COMPRISING A PLURALITY OF ELECTRON BEAMS Filed Feb. 3, 1954 CHANNEL a j a Em 1357 GERRIVT HENDRIK PETRUS ALMA AGENT 3. INVENTOR I ELECTRIC DISCHARGE TUBE COMPRISING A PLURALITY F ELECTRON BEAMS Gerrit Hendrik Petrus, Alma, Eindhoven, Netherlands,

assignor, by mesne assignments, to North American Philips Company, Inc., New York, N. Y., a corporation of Delaware Application February 3, 1954, Serial No. 407,971 Claims priority, application Netherlands February 3, D53

4 Claims. (Cl. 313-69) The invention relates to an electric discharge tube in which a plurality of electron beams are produced, which can be deflected each into two diflerent positions independently of one another. The invention relates more particularly to a selector tube for selecting a definite channel from a plurality of channels.

Such tubes are known per se. A beam may be deflected in a manner such that it strikes a particular anode, in which position it is held. Similarly to the mechanical selectors, in which a contact arm is adapted to perform a rotary movement and an upward movement, the beam is adapted to move to and fro and up and down. However, such tubes are very complicated and use must be made of a beam having a small sectional area in order to avoid excessively large dimensions of the tube. With binary systems use is therefore frequently made of triodes, of which the triode corresponding to the selected channel draws current. Although the tubes employed may be of simple construction, the device is nevertheless involved owing to the great number of tubes required with the associated circuit elements. Use is frequently made of double triodes.

With calculating machines a choice is to be made frequently from a plurality of, for example, eight channels on the basis of an indication in the binary system. Then, if double triodes are used, 1+2+4=7 double triodes are required with their associated circuits and component parts.

This may now be achieved in a simpler manner by using a device comprising a selector tube according to the invention.

According to the invention in such a device comprising an electric discharge tube having a plurality of electron beams and suitable for selecting one from a plurality of channels on the basis of an indication in the binary system, the beams may be deflected each into two positions, independently of one another, each beam striking simultaneously a plurality of anodes equal to half the number of channels, these anodes being connected for the various beams to the various channels in a manner such that in each combination of beam positions for one channel all anodes connected thereto lie always outside the beams. The channel not conveying current is thus the selected channel.

If desired, the deflection may be effected by means of a grid, so that the electrons are allowed to pass to one group of anodes or reflected towards the other group. Then a number of systems corresponding to the number of binals may be provided in the longitudinal axis of the cathode. By suitable screening of the systems it is possible to ensure their independent operation.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, in which Fig. 1 shows diagrammatically an arrangement of a device in accordance with the principle of the invention and l atented May 21, 1957 ice simultaneously by a beam. The beam of each system occupies either the position 0 or the position 1. In the former, it strikes the upper group of four anodes. In the latter, it strikes the lower group of four anodes. The beam of each electrode system is separately controlled. Each channel is connected to all anodes of the same reference numeral. For example, all the anodes designated by the numeral 5, of which one is present in each electrode system, are electrically connected together to a common channel, which may also be designated 5. For simplicity, only one channel is shown in the drawing, there being, of course, separate channels for each of the anodes 1 to 8. The anodes are arranged among the two groups of each system such that in each combination of beam positions there is always one channel of which the anodes are not struck by a beam. By a suitable arrangement, such a channel, all anodes of which are idle, may be opened. For this purpose use may be made ofvarious arrangements, which are familiar to those skilled in the art. The anodes having the same reference numerals and connected to one anothenmay, for example, be connected to a grid of a triode, this grid being fed by positive voltage via a heavy resistor. If all anodes of the channel concerned become idle, the said grid becomes more positive, since the said resistor is no longer traversed by the electron flow, so that the triode becomes conductive.

If the position of the electron beam shown is indicated by 0 and the other position by 1, the combinations indicated in the table at the side of Fig. 1 are possible for the three beams; it will be observed that in each position of the beams the anodes of only one channel are idle. For example, if the beam in the upper system is in position 1, that of the center system in position 0 and that of the lower system likewise in position 0, it will be noted that of all the anodes 1 to 8, only the three anodes 5 in the three systems are all simultaneously free from being struck by an electron beam; hence, this channel becomes the selected channel. In the table, the three columns to the left indicate the positions occupied by the beams in the upper, central and lower electrode systems, respectively; whereas, the column to the right indicates the selected channel for those positions of the beam.

A binary system as described above has the advantage that each beam can always be moved into the one or the other extreme position without the need for intermediate positions. This provides a very reliable operation, since the beam position varies only with the polarity of the voltage at the deflection plate concerned and is independent of the value of this voltage within wide limits.

The system shown in Fig. 1 may be arranged in the longitudinal axis of a common cathode one above the other.

Figs. 2 and 3 show a further embodiment, in which three systems are stacked up around a cathode k, each system comprising four rod-shaped anodes, located inside the second grid and four similar anodes located outside the second grid. This second grid serves as a controlgrid and is capable of passing the complete electron flow to the anodes outside this grid or it is capable of completely reflecting the flow to the anodes inside this grid. The first grid serves as an accelerating grid. By means 3 of screens the systems may be isolated from one another. Such a tube has 13 contact pins.

If desired, the various systems may be displaced relatively to one another with a view to the positioning of the interconnecting wires of the anodes. With a suitable arrangement of the anodes various anode rods may extend through two or more systems and thus be constituted by a single rod, for example, the anodes 1 and 8,.which occur in each system in a corresponding group, as is evident from .Fig. 1.

Although by way of example a tube comprising three beams is described, the tube being thus capable of selecting from 2 :8 channels, use may, as an alternative, be made of more than three or less than three beams.

A tube having two beams can select from four channels,

atube having four beams from 16 channels, and so on. In general, for n electrode systems, .2 channels are available, andeach group of anodes in a system struck by a beam in one position is equal to As an alternative, the construction may be varied. The rod-shaped anodes, for example, may be replaced by plates and the like.

What is claimed is:

1. An electric discharge tube comprising a plurality of electrode systems; each of said electrode systems including electron beam-producing means, two groups of anodes, and means for controlling said 'beam to strike one or the other of said anode groups; each of said anode groups including a plurality of anode electrodes, each anode electrode of each anode group being interconnected with one anode of each of the other systems, said anodes being arranged in the groups of each system such that for every combination of beam positions striking whole anode groups, only one series of interconnected anodes of the systems are not struck by any of the beams.

2. An arrangement comprising an electric discharge tube having n separately controllable electrode systems where n is an integer greater than one; each of said electrode systems including electron beam-producing means, two groups of anodes, and means for controlling said beam to strike the whole of one or the other only of said anode groups, each of said anode groups including independent anode electrodes; and 2 channels, each of said channels being coupled to one anode of each of the electrode systems whereby n anodes are connected to each channel, said anode electrodes being arranged in the groups of each system such that for every combination of positions of the beams in each of the systems, only one series of anode electrodes all connected to the same channel are not simultaneously struck by any of the beams.

3. An electric discharge tube asset forth in claim 1 wherein there is provided a common elongated cathode for all the electrode systems, said systems being arranged adjacent one another in the direction of length of the cathode, some of the anodes of the systems being constituted by rod-like members common to at least two of the systems.

4. An electric discharge tube as set forth in claim 1 wherein there are provided a pair of grids for each of the electrode systems, one of said anode groups being arranged within the grids, the other of said anode groups being arranged outside the grids.

References Cited in the file of this patent UNITED STATES PATENTS 2,111,625 Heising Mar. 22, 1938 2,424,289 Snyder et al July 22, 1947 2,470,732 Visschcr May 17, 1949 2,472,779 Selgin June 7, 1949 2,615,142 Adler Oct. 21, 1952

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