US2465041A - Electron discharge device - Google Patents

Description

March 22, 1949. c. A. SCHLElMANN-JENSEN ETAL 2,465,041

ELECTRON DISCHARGE DEVICE Filed Jan. 15, 1945 Patented Mar. 22 1949 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE Sweden,

assignors to Aktiebolaget Svenska Elektronriir, Stockholm, Sweden, a company of Sweden Application January 15, 1945, Serial No. 572,850 In Sweden December 12, 1942 2 Claims. (Cl. 25027 .5)

in which fluorescence produced by electron bombardment is employed for indicating varying voltages, by varying configurations of contrasted luminous and dark areas.

Such electronic voltage indicators as they may be termed have many uses, for example, to indicate the resonant or tuning positions of radio receivers, in test equipments and modulationmeters etc. Usually, in addition to a thermionic cathode and a fluorescent anode, they have a grid or other deflecting electrode, which operates at a positive potential varying with the automatic volume control voltage and thus with the strength of the input signals.

As a consequence of this fact a greater part of the fluorescent coating will be bombarded by electrons from the cathode at high signal voltages than at low signal voltages. Now, it is well known that most of the fluorescent materials generally used will fatigue with time of operation, that is the brightness of the bombarded sector or sectors of the fluorescent screen will diminish at a certain rate according to the time during which this part of the screen has been bombarded. In radio receivers which usually are tuned to a local transmitter station this means that after a relatively short time of use the greater part of the useful fluorescent screen will be fatigued and in this way make it difficult to indicate the exact tuning to a station with lower signal voltage because in this case the small bombarded section of the screen is positioned entirely within the sector or sectors of the screen which already are fatigued from the bombardment by the high signal voltage of the local station.

To eliminate this disadvantageous feature it has been proposed instead of applying the above mentioned positive potential on the deflecting electrode to operate the tube with a negative potential varying according to the automatic volume control voltage on the deflecting electrode. However, this method of operation almost always necessitates the use of an additional amplifying stage, which of course is very undesirable.

The main object of the present invention is to achieve an improvement in tuning indicators provided with a fluorescent anode and a cathode from which the electron stream is concentrated into one or more beams by using two control electrodes, disposed between the anode and the cathode on opposite sides of each electron beam and deflecting the electrons of the beam in one and the same direction.

Another object of this invention is to provide an electric discharge device comprising within an envelope an indicator section as described and an amplifier section comprising a grid and an anode, in which the cathode may be common to both sections.

A further object of this invention is to provide an indicator construction in which the two control electrodes together with an auxiliary electrode form an electron-optical lens system for the deflection of the beam.

A still further object of this invention is to provide an indicator, the sensitivity of which is variable along the fluorescent screen by arranging or shaping, or by both arranging and shaping, at least one of the control electrodes asymmetrically in relation to the other electrodes of the system.

In the following the terms control electrode and auxiliary electrode are used to denote one such electrode aswell as a combination of more such electrodes.

The novel features which we believe to be characteristic for our invention are set forth in the appended claims; the invention itself, however, both as to its construction and operation will be best understood by reference to the following description taken in connection with the accompanying drawings in which we have indicated some embodiments of the invention.

In the drawings:

Figure 1 shows an electron discharge device ac-,

cording to the invention with parts broken away to show details of construction.

Figures 2 and 3 diagrammatically show two forms of electronic voltage indicators according to the invention.

Figures 4 and 5 are cross-sections of two practical embodiments based on the diagram shown in Figure 2.

Figure 6 is a cross-section of a practical embodiment based on the diagram shown in Figure 3 Figures '1, 9, 11 and 13 are sections of four dif- 1, and base 8. Supported from the press are a cathode H, a grid 9 and anode ll] surrounding the cathode.

According to the invention the indicating section of the tube is mounted in the upper portion of the envelope I. The indicator comprises a cathode, an anode having a conical surface presented to said cathode and provided with a coating which fluoresces when subjected to electron bombardment, and, disposed between the cathode and the anode on opposite sides of the beam of electrons from the cathode, two control electrodes deflecting the electrons or" the beam in one and the same direction.

As shown in Figure 1 the cathode II is extended into the upper portion of the envelope I with an emitting section for applying electrons in the indicating device. Two control electrodes in the form of cylinders 3 and 4 are positioned above each other and around the cathode having an annular opening between themselves through which electrons pass from the cathode If to the coated anode 2 and form a luminous ring thereon. One control electrode 4 of the indicator is supported from a bar 5 electrically connected to the grid 9 of the amplifier portion of the tube, the other control electrode 3 being supported from a bar 6 supporting the anode IU of the amplifier portion. In operation the control electrode 4 has a negative potential and the control electrode 3 a positive potential in relation to the cathode ii. If the signals increase, the potential of the electrode 4 will grow more negative and that of the electrode 3 will grow more positive, i. e. the said electrodes will deflect the electronic stream upwards, as indicated by the dash-and-dot lines in Figure 2 which diagrammatically shows the indicator portion of the device in Figure 1. When the signal voltage has a lower value the electrons will follow the dash lines. Consequently, at high input voltages different parts of the fluorescent screen 2 will be bombarded by electrons than at low input voltages.

Figures 4 and 5 show indicators based on the same principle as illustrated in Figure 2. One control electrode consists of two interconnected rings l2 and I4 placed above each other and around the cathode I I. Placed in front of the opening formed between the two rings I2, I4 is an annular deflecting electrode l3 lying on the anode side of the electrode l2, H3 in Figure 4 and on the cathode side in Figure 5. In these embodiments of our invention two luminous rings will appear on the fluorescent target, said rings receding from each other upwards and downwards at strong signals and approaching each other at weak signals. This way of indicating has been found to be especially favourable to facilitate observation.

In the diagram shown in Figure 3 in addition to the two control electrodes 3 and 4, disposed on opposite sides of the electron beam, a further auxiliary deflecting electrode I5 is arranged on one side of the beam forming together with the control electrodes 3 and 4 an electron-optical lens system for the beam passing through the opening between the electrodes. The auxiliary electrode l5 may be connected electrically to the control electrode 3 lying on the same side of the beam, or it may be connected to the control electrode 4 lying on the opposite side of the beam. The diagram shows the electrodes 3 and i5 working at a positive potential and the electrode 4 at a negative potential in relation to the cathode.

At high signal volage the electrons follow the dash-and-dot lines and at lower input voltage they follow the dash lines.

The indicator shown in Figure 6 is made according to the principle in Figure 3, but with the deflecting electrode inversely positioned. In this case the deflecting electrodes 3 and 4 and the auxiliary electrode 15 consist of cylindrical rings, surrounding the cathode II, the electrode 4 being placed above the electrodes 3 and I5, and the electrode 3 being so arranged within the electrode 15 that its upper edge is situated in the opening between the electrodes 4 and I5 or is on the same, or approximately the same level as the upper edge of the electrode I5. In this case the visible indication on the fluorescent screen will consist of a luminous ring.

In the indicators shown in Figures 7 to 14 the sensitivity of the indicator is made variable along the screen. According to our invention this object is achieved by arranging or shaping, or by both arranging and shaping, at least one of the deflecting electrodes asymmetrically in relation to the other electrodes of the system. In other respects these indicators are based on the principle shown in Figure 2.

In the embodiment of our invention shown in Figures 7 and 8 the control electrodes consist of two rings l6 and I! placed above each other and around the cathode ll. One of the deflecting electrodes, H, is cut off obliquely in relation to the other deflecting electrode l6 to enable a variable sensitivity of the device at variable signal strength. Only one luminous part will appear on the fluorescent screen 2. The boundaries between the luminous and the dark parts of the screen are indicated by a dash-and-dot line 20 (Figure 8) in the case of a station with great signal strength and by a dash line l8 in the case of a station with low signal voltage, the luminous part 2i of the screen lying outside the boundary-lines. In the first case the dark part 22 located to the left in Figure 8 and having the lower sensitivity is utilized according to the invention for indication while in the second case the dark part is to the right is made use of, said latter part having the greatest sensitivity.

In the indicator shown in Figures 9 and 10 one of the deflecting electrodes consists of two interconnected rings 23 and 25 placed above each other and around the cathode ll. Between the rings 23, 25 there is formed a circular opening, in front of which an annular deflecting electrode 24 is arranged. This annular electrode 24 is shaped asymmetrically in relation to the remaining electrodes of the system and produces together with the other deflecting electrodes 23, 25 an. inner and an outer luminous ring on the screen 2. The dark intermediary portion of the screen is indicated by the dash-and- dot lines 20 and 20 in the case of a station with great signal strength and by the dash lines l8 and I8 in the case of a station with low signal voltage. At great signal strength the left parts of the dash-and- dot boundaries 20, 20 is utilized; at low signal strength the right parts of the dash lines l8, 18 are made use of.

In the indicator shown in Figures 11 and .12 the electrode 26 located in the opening between the deflecting electrodes 23, 25 has annular shape and is placed inclined in'said opening. The. dark part on the screen will appear between the. dashand- dot lines 20 and 28 at "full signal strength and between the dash lines 18 and 18' on tuning to a station with low signal voltage. In the first case the left parts of the dash-and-dot lines 20 and 20' serve to indicate the tuning position, in the second case the right parts of the dash boundaries I8 and I8 are utilized for the same purpose.

In the indicator according to Figures 13 and 14 the electrode placed in the opening between the electrodes 23, 25 consists of two half rings 21 and 28 arranged opposite each other and at mutually difierent levels. In this way the sensitivity of the device becomes different in two 180- sectors, the dark part at high signals lying between the dash-and-dot lines 20 and 20' and at low signals lying between the dash lines I8 and I8. In the first case the lower parts of the dashand-dot lines 20 and 20' are utilized to indicate, in the second case the upper parts of the dash lines I8 and I8.

The asymmetrical electrodes 24, 26 and 21, 28 respectively (Figures 9 to 14) may be more or less displaced in relation to the opening and even displaced on one side of the opening in which case one luminous ring only will be formed on the fluorescent screen.

Figure 15 schematically shows a further form of the electric discharge device according to the invention, comprising within the envelope I an indicator section, containing the fluorescent anode 2, the control electrodes 3 and 4, the cathode II, and an amplifier section, containing the common cathode I I, an anode 29, a control grid 33, a screen grid 32, and if desired a suppressor grid 3|, the control grid 33 and the screen grid 32 being connected each to one of the control electrodes 3 and 4 of the indicator section. The object of this particular arrangement is to provide a tube containing a separate amplifier section intended to be used as an amplifier in the receiving set or other apparatus in which the indicator section is utilized to show the tuning position.

Although we have shown and fully described, by way of example, some embodiments of our invention, it will be apparent that many changes may be made therein without departinng from the intended scope and spirit of the invention. For instance, there may be provided more openings for the stream of electrons between the cathode and the fluorescent target in order to produce other patterns of the luminating spots on the fluorescent screen as may be suitable for the indi- 80 Number cation desired.

What we claim is:

1. An electron discharge device having in an envelope an indicator section, comprising an anode with a fluorescent coating, an elongated cathode for producing electrons, two closed ringshaped control electrodes surrounding and spaced from the cathode for concentrating the electrons into at least one beam and for deflecting the electrons in each beam in one and the same direction, and mounted in the said envelope, an amplifying section comprising an anode, a cathode, and a control electrode, the anode and the control electrode of the amplifying section each being electrically connected to one of the control electrodes of the indicator section inside said envelope.

2. An electron discharge device having in an envelope an indicator section, comprising an anode with a fluorescent coating, an elongated cathode for producing electrons, two closed ringshaped control electrodes surrounding and spaced from the cathode for concentrating the electrons into at least one beam and for deflecting the electrons in each beam in one and the same direction, and mounted in the said envelope an amplifying section containing an anode, a cathode, a control grid, and a screen grid, the control grid and the screen grid of the amplifying section each being electrically connected to one of the control electrodes of the indicator section inside said envelope.

CARL ARNE SCHLEIMANN-JENSEN. NILS ERIK GUSTAV BACKMARK,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,051,188 Thompson Aug. 18, 1936 2,098,231 DuMont Nov. 9, 1937 2,108,880 Braden Feb. 22, 1938 2,243,408 Anderson et a1 May 27, 1941 2,273,800 Jensen Feb. 17, 1942 2,283,103 Stuart, Jr May 12, 1942 2,318,140 Clark May 4, 1943 2,366,320 Elston Jan. 2, 1945 FOREIGN PATENTS Country Date 495,732 Great Britain Nov. 18, 1938

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