US2490145A - Electron tube - Google Patents

Description

W. W. M GOFFIN ELECTRON TUBE Dec. 6, 1949 Filed July 12, 1946 Patented Dec. 6, 1949 UNITED STATES ELECTRON TUBE William Walter McGoflin, assignor of one-fifth to S. N. Y.

New York, N. Y., S. Baker, New York,

Application July 12, 1946, Serial No. 683,058

4-Glain'is. 1

This invention relates to electron tubes and more particularly to such a tube having a physically variable element for changing the operating. conditions of the tube.

One of the objects of this invention "is to provide means whereby the effective grid control area within the tube maybe varied automatically according to the conditions to be measured so that the plate current flow or the operating con.- ditions of the tube are similarly'varied.

Another object of this invention is to provide a simple device for automatically amplifying an indication of temperature or other condition when such condition can be caused to produce movement of an element.

Another object of this invention is to provide a simple device for giving remote indications of a condition existing at the site of an electronic tube constructed according to the instant invention.

Still another object of this invention is to provide a means of automatic temperature control wherein changes of temperature can be caused to produce physical move-mentor an electron tube element which tube can thereupon directly control heat or cold producing devices so as to neutralize the change of temperature,

A further object of this invention is to provide an electronic deviceadapted to effect rapid micrometer measurements such as where the thickness of articles is to be determined rapidly and with precision.

Other objects of my invention will be apparent from the following description, it being understood that the above general statements of the objects of my invention are intended to describe and not limit it in any manner.

Referring to the drawings:

Fig. 1 is a schematic circuit diagram illustrating an embodiment of the invention particularly adapted to temperature indications and control.

Fig. '2 illustrates a modification of the grid structure shown in'Fig. 1.

Fig. 3 is a schematic circuit diagram illustrating a modified embodiment of the invention.

Fig. 4 is a schematic circuit diagram illustrating another modified embodiment of the invention.

Fig. 5 is a front view of the grid structure of Fi 4.

Fig. 6 is a schematic circuit similar to Fig. 4, but illustrating an electronic tube havin a pair of anode structures so as to be adapted to pushpull operation.

The tube ill in Fig; 1 is illustrateda's being. of

to vary the bias potential.

the ordinary three element type although, as will hereinafter appear, the invention can be adapted to inulti-element tubes. The tube I0 is provided with a conventional anode or plate II and a cathode l2. The tube may be of the filamentary or indirect heated type although tubes having a cold cathode are well adapted to the invention.

The control grid I 4 is constructed according to the invention herein as thermometer tubing housing a supply of mercury in the column E5 of the bulb l8. As will be recognized, the mercury rises'in the grid tubing in response to temperature increases. Grid M is illustrated as taking the 'formpf a spiral glass tube surrounding the cathode I2. The physical shape, however, of the grid l4 may follow that of conventional grid Structures as, for example, mesh structures, the difference being that the grid in the present invention is of continuous glass tubing or other non-conducting material, is hollow, and is provided with a supply of temperature responsive liquid, such as mercury. If desired, salt water, a sodium solution, cesium or rubidium, may be substituted for the mercury when conditions so permit.

The column l5 may be as great as 4 inches in length so as to minimize the eifects of tube heat. However, since the tube heat is practically constant, its effect can be calibrated or otherwise provided for although in cold cathode tubes this is unnecessary. The spiral tubing comprising the grid I a may be substantially thinner than that of ordinary thermometers since it is not obliged to withstand the pressures acting upon conventional thermometers which are not disposed in a vacuum as is the grid I4 herein. The reduced thickness of the structure is furthermore advantageous in enhancing the effectiveness of the grid control.

Bias between the cathode I2 and grid I4 is provided in the form of battery ll, a tap l8 serving It is apparent, however, that ordinary cathode bias such as may be provided by a cathode resistor, may be used. Tap i8 is connected to lead l9 which in turn is electrically connected to the mercury. This may be effected by providing a metal plug 28 in the wall of bulb It so that the lead 59 may be soldered thereto so as to effect contact with the mercury. Alternatively, the lead l9 may be introduced into the bulb I6 and sealed with a conventional metal to glass seal.

The plate load takes the form of a resistor 2| which may have a conventional value such as in the"neigh-borhood of 199,060 ohms. In practice,

resistor 2| may be a heat producing device which, if desired, can be caused to react upon the mercury so as to produce cut-off in the tube and deactuation of the heat producing device. Plate voltage may approximate 150 volts although considerably higher voltages such as used in cathode and X-ray tubes may be used. Such higher voltages will decrease the effect of the glass tubing on the grid control system. Furthermore, alternating current may be used for tube operation whereupon said effect may be likewise decreased due to reduced impedance.

The operation of the tube Ill will be understood by those skilled in the art. Briefly, when temperature conditions are such that the mercury is low in the grid structure, the efiective grid area will be small so that the electron stream between the cathode l2 and anode II is impeded very little by the presence of the grid. Should the mercury rise however, the mercury will control a larger area between the cathode and anode so as to serve as a more eifective barrier to the electron flow inasmuch as the mercury is charged with the biasing potential. Should the mercury reach sufficiently high, it will introduce the bias voltage between the entire cathode and anode so as to approach or produce cut-off in the tube operation. The voltage required therefor will be determined by the specific tube employed since the characteristics of different tubes vary in a manner which is well known to those skilled in the art.

If the above circuit is utilized in a temperature oven, the effect on the electron stream by the rising or falling mercury may be utilized in operating a relay in the anode circuit for controlling temperature balancing devices such as refrigerators or heat producing devices. It is also feasible to substitute a temperature calibrated plate-current meter in the circuit in place of resistor 2| whereupon remote reading of the temperature existing at the location of the tube will be given.

In Fig. 2 is illustrated a form of grid structure wherein the bias voltage appears externally of the tubing so as to present a more effective grid control. Grid 25 is of the hollow glass construction described above and is provided with a supply of mercury in its bulb 2%. Each half turn of the spiral tubing is provided with spaced metallic plates located exteriorly of the tubing but communicating with the inside thereof. Thus, metal plate 21, shown broken away may be formed by spraying metal around spiral portion 28 so as to deposit a metallic coat thereon. Portion 28 may have one or more minute openings communicating with the interior of the spiral tubing for receiving the sprayed metal therethrough so as to form an integral projection 21a with sprayed metallic plate 2? so as to efiect electrical contact with the mercury. Thus, the potential of the mercury which is applied through the plug 29 is transferred to plate 21. Instead of the sprayed formation of plate 21, it is apparent that the plate in tubular form having an integral projection on the inner wall thereof, may be suitably heated so as to penetrate portion 28 with its integral projection and thereafter suitably fastened as by a metal to glass seal. The mercury will thereupon transfer the bias potential to the plate. Plates 39, 3|, 32, 33 and additional plates follow successively up the spiral grade tubing and are mutually spaced by small sections of the glass tubing so as to be insulated from each other. Each of said plates is formed in a manner similar to that of plate 21 so as to communicate electrically with the mercury disposed within the tube.

It will be recognized that as the mercury rises in the grid structure illustrated in Fig. 2, each half turn of the spiral grid will become successively charged with the bias potential so as to present a progressively higher grid control or barrier to the electron flow. The spacing between plates may be as small as desired in order to provide the required sensitivity in the device.

In Fig. 3 is illustrated a modified method of varying the efiective grid area in accordance with the conditions to be measured. Tube is again illustrated as being of the triode type, the anode 36 and cathode 37 serving the same functions as those in the previous embodiment. Grid 39 may be of the conventional metallic mesh and means are provided for swinging the grid in and out of the electron stream in varying degrees. Accordingly, a bell crank lever having the metallic arms 40 and 4| pivoted on pin 42 is connected to grid 39 so as to provide the grid with a swinging movement. Pivot pin 42 may be fixed in the base of the tube, the upper end of pin 42 rotatably supporting the bell crank lever. A spring 43 which is connected to a pin 44 likewise mounted in the base of the tube, is connected to lever arm 4|. Thus, the normal position of the grid 39 is outside of the electron stream so that, in effect, the tube is a diode since the grid 39 is ineffective in varying the electron flow. As in conventional electron tubes, cathode 31 and anode 36 are substantially in longitudinal alignment. The alignment of the grid in the instant structure therewith is variable as disclosed. As the grid approaches alignment with the anode and cathode it tends to approach or produce cut-off in the tube. Lever arm 40 is of magnetic material such as steel and it may be of the permanent magnet type, if desired.

tron stream.

Arm 45 which is mounted outside of and distinct from tube 25 may take the form of a bimetal strip which bends in response to temperature Variations. A magnet 46 is arranged to bear against arm 45 through the integral pin 41 which is drawn toward arm 45 by spring 48 and pin 49.

When magnet 46 is brought toward arm 40, said arm 40 will be attracted thereto so as to produce pivotal movement of the 'bell crank lever about pin 42 and swing the grid 39 into the elec- This position of the grid 39 is shown in broken lines in Fig. 3. Conventional grid bias, not shown, between the cathode 31 and grid 39 is provided so as to produce grid control of the electron stream. The ensuing reduced current flow in the plate circuit may be caused to actuate or de-actuate a heat or cold producing apparatus which may then react upon thermal responsive arm 45 so as to permit the withdrawal of the magnet 46. The grid 39 is then swung back out of the electron stream when a balance has been reached between the movement of the arm and the effect of the apparatus controlled by the tube. However, whether or not the reduced plate current is caused to move the arm 45, it will be apparent that any temperature produced changes in the arm 45 will be reflected by variations of plate current flow as proximity of the magnet 46 to the arm 49, and the magnetic action thereon is accordingly intensified.

Arm 45 may alternatively take the form of an ordinary fixed bracket member. Accordingly, articles the thickness of which it is desired to determine, may be inserted between pin 41 and arm 45 so as to move magnet 46 forward against serted article.

the action of the spring 48. This will produce movement of the bell crank lever and interposition of the grid 39 into the electron strea'mto a degree depending upon the thickness of the in- Such thickness can then be read from a calibrated plate-currentimeter in the circult of anode 36.

In the embodiment of Fig. 3, the tube 35 may be a gas-filled tube,if desired, or it may normally be a rectifier using only the cathode and anode elements functioning as an ordinary diode arrangement and capable of handling heavy currents. The introduction of the grid 39 into the electron stream, however, is effective in converting the tube from an effective diode to a triode. The bell crank lever serves .to amplify the movement of arm 40 as the grid is caused thereby to travel in a path between the anode and cathode electrodes. Thus the transverse position of the grid in the electron stream between these electrodes determines the controlling effect thereof as in the previous embodiment.

Referring to Fig. 4, a tube construction is shown which varies the grid control between the cathode and anode by a rotating action of the grid structure. Thus, tube 50 is illustrated as having a plurality of anodes which may be intercon nected either internally or externally of the tube. Cathode 52 constitutes, as hereinbefore mentioned, the source of electrons which flow towards the anodes. The control grid 53 is rotatably mounted within the tube in a manner illustrated in Fig. 5. The grid 53 comprises a shell or circular wall of thin metal having a series of openings or discontinuities 54 formed therethrough,

thenumber of which corresponds to the number of anodes 5| in the tube.

Grid 53 has a reduced portion or neck 55 which is formed with a ball '55 supported and rotatably mounted in the knuckle 51. Knuckle 51 may :be connected or be integral with a grid cap 58 so that bias potential to the grid 53-may be applied through the cap 58, knuckle 51 and ball 56 thereto. Such construction effectively suspends the grid 53 within the tube and permits rotation thereof for variation of its control functions. The knuckle 51 may have flattened socket portions as shown so that the grid 53 will not tilt but will rotate only, or any conventional manner of preventing such tilting may be employed.

In order to produce rotation of grid 53, a wire 59 may be curled around neck 55 and connected thereto at point 60. Wire 59 is connected at its other terminal 6! to arm 62. Arm 62 is pivoted at 83 within the tube so that pivotal movement of arm 62 actuates wire 59 so as to rotate grid 53. Arm 62 is provided with an armature member 65 adapted to be attracted to an externally located magnet such as the magnet 46 in the previous embodiment. Wire 59 may take the form of a coiled spring whose normal function is to maintain arm 62 in a rearward position where the wire 59 is wound around neck 55. Attraction of armature member 64 by the magnet is therefore effected against the action of spring wire 59.

When the grid 53 is rotated as hereinabove set forth, it will block the path of the electrons by presenting the bias potential thereto. Only slight movement of the grid is necessary to effect such action because such slight action is multiplied by a factor of 5, there being 5 anodes and associated grid portions in the illustrated embodiment. Thus, the grid need rotate only approximately 35 degrees in order to proceed from structure.

absence of control to complete control. It isapparent, however, that'the number of anodes and grid openings may be varied as desired. As the grid rotates from the position shown in Fig. 4, the position of the discontinuities 54 thereof is varied and they are brought out of alignment with the anodes whereby grid control is correspondingly rendered effective.

In Fig. 6 is illustrated a tube structure wherein two sets of anodes are provided so as to permit a differential flow of electrons thereto. Thus, tube 10 is provided with the anode sets 1-! and 12 each being connected into a separate circuit. Anodes 1.5 are interconnected so as to form a first anode structure. Anodes 12 arestaggered in relation to anodes 1| and form a second anode The grid 13 is constructed in a man'- ner similar to that of grid 53 in the previous em bodiment so as to intercept or permit the how of electrons from cathode 14 to anodes 1.] or 12 differentially. Anodes 1i and anodes it will have different load resistors so that the position of grid 13 will be reflected by the amount of current flowing in these load resistors or the voltage drop across them. This effect will be differential so that the tube may be used either in a Wheatstone bridge or push-pull arrangement.

When grid 1'3 is so oriented as to cut off the flow of electrons to anodes 1|, it permits the flow of electrons to anodes 12 and vice Versa. Intermediate positions are also provided wherein each of the anode sets receives a portion of the electrons.

It will be seen from the foregoing that I have provided an electron tube wherein a grid element is mechanically or physically varied to alter its effective area, through conditions originating externally of the tube and transmitted to the grid element through a rigid tube envelope structure which is not provided with special tube envelope formations or flexible diaphragms therein. However, the invention is not to be limited to actuation of control grids since a screen grid may well be treated by the present invention as may be anode structures which may be moved relative to a controlled electron path. Such an arrangement as well as the embodiments above mentioned may Well operate as a volume control in radio apparatus since the current flowing in the anode circuit is controlled thereby. Thus, the usual volume control potentiometers or variable resistors may be dispensed with. In addition, while I have shown a permanent magnet for actuating the grid lever in Fig. 3, it is apparent that an electromagnet may be substituted therefor and the intensity of the magnetic field thereof may be varied through variations in proximity thereof to the grid lever or through variations of current flow in the electromagnet. Therefore, it is intended in the following claims to cover all such changes and modifications as fall within the true spirit and scope of the invention, such as, for example, described above or hereinafter.

In the event that an electromagnet is utilized instead of a permanent magnet, such electromagnet may well be disposed within the tube envelope with the leads therefrom being connected to the usual base pins. Thus, a signal which is applied to the internal electromagnet will act upon the grid structures such as shOWn in Figs. 3 to 6 so as to produce a considerable change of plate current flow in response to the small variations of current. The proximity of an internal electromagnet to the grid structure will thus provide very high degrees of amplification particularly with the light weight grid which is easily actuated. With such a construction it is also feasible to apply the signal to the grid as a potential thereon while simultaneously applying it as a current to the electromagnet so that a double action is achieved and extremely high amplification eiiected, particularly when heavy currents are being handled by the tube.

1. An electron tube having cathode and anode electrodes, physically variable control grid means for controlling the electron stream between said electrodes, said control grid means comprising a hollow tube of electrically non-conductive ma-- terial disposed within said tube and substantially between said electrodes, a conductive liquid within said tube which rises or falls in response to conditions external of said tube, means to apply grid bias potential to said liquid whereby the effective area of said bias potential rises or falls in accordance with said external conditions, said rise or fall being adapted to longitudinally vary the effective control grid area in said electron stream whereby the controlling efiect of said control grid means is varied accordingly.

2. Apparatus according to claim 1 wherein said control grid means comprises a mercury thermometer having a portion thereof extending outside of said tube.

3. Apparatus according to control grid means comprises a spirally arranged mercury thermometer disposed around said cathode electrode and having a mercury supply reservoir extending outside of said tube, said grid bias potential being applied to the mercury in said supply reservoir.

4. An electron tube having elements for proclaim 1 wherein said ducing an electron flow therein, an electrode in i said tube adapted to influence said electron flow by having a potential thereon, and means to vary the efiective physical position of said electrode, said electrode comprising a hollow tubing of electrically insulating material, an electrically conductive liquid adapted to rise and fall in said tube in response to conditions existing externally of said tube and adapted to have said potential applied thereto, mutually spaced metallic areas disposed externally of and continuously up said tubing so as to be separated by lengths of the electrically insulating material of said tubing and communicating with said conductive liquid whereby said potential is transmitted to a number of said areas in accordance with the degree of rise of said liquid, the number of said areas having said potential transmitted thereto representing the degree of influence of said electrode.

WILLIAM WALTER McGOFFIN.

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

UNITED STATES PATENTS Number Name Date 841,386 De Forest Jan. 15, 1907 1,610,316 Quilter Dec. 14, 1926 1,884,591 Davis Oct. 25, 1932 1,983,838 Bowles Dec. 11, 1934 1,997,986 Thomas Apr. 16, 1935 2,018,220 Morrisson Oct. 22, 1935 2,027,405 Smede Jan. 14, 1936 2,225,032 Carbonara Dec. 17, 1940 2,300,882 Ferguson Nov. 3, 1942 2,348,177 Keeler May 2, 1944

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