US3356886A

US3356886A - Variable spaced electrode for electron discharge device

Info

Publication number: US3356886A
Application number: US430797A
Authority: US
Inventors: William A Allgaier; Droppa Cyril
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1965-02-08
Filing date: 1965-02-08
Publication date: 1967-12-05
Anticipated expiration: 1984-12-05
Also published as: GB1077457A

Description

Dec. 5, 1967 w. A. ALLAlER ETAL 3 35 836 VARIABLE SPACED ELECTRODE FOR ELECTRON DISCHARGE DEVICE Filed Feb. 8, 1965 2 Sheets-Shet 1 i /7 Ms E I g I Y ELECTRODE SFAC/NG P/"for 24m Prior Ari 1 g. j i g. E

VOL T4 GE 5415c 7/?006' SFAC/NG I l I I Q7 INVENTORS J. g 4' W/AU/IM ,4. Hues/m I C YR/L .DRoPP BY 7 v ATTORNEY Dec. 5, 1967 w. A. ALLGEAIER. I ETAL 3,356,386

VARIABLE SPACED ELECTRODE FOR ELECTRON DISCHARGE DEVICE Filed Feb. 8, 1965 I 2 Sheets-Sheet 2 Q 55 59 v 59 7 g /55 6/ F1 g. 4 W1 q. 5

INVENTORS WILLIAM A. ALLGA/m I CYR/L .DROFPA ATTORNEY United States Patent 3,356,886 VARIABLE SPACED ELECTRODE FOR ELECTRON DISCHARGE DEVICE William A. Allgaier and Cyril Droppa, Emporium, Pa.,

assignors to Sylvania Electric Products Inc., a corporation of Delaware Filed Feb. 8, 1965, Ser. No. 430,797 11 Claims. (Cl. 313-294) ABSTRACT OF TI-IE DISCLOSURE An electrode disposed between the cathode and anode of an electron discharge device is formed to provide nonuniform spacing between the electrode and the cathode and between the electrode and the anode.

This invention relates to an improved electron discharge device and more particularly to an improved electrode for an electron discharge device of the type which includes an electron emitting cathode, an electron receiving anode, and an electrode intermediate thereto.

As is well known, electron discharge devices, excepting the so-called diode type, usually include an electron source or cathode, an electron receiver or anode, and one or more electrodes therebetween which serve to either control or confine the path of the electrons from the cathode to the anode. A more specific type of electron discharge device and one which will be utilized to illustrate one embodiment of the invention is the beam power type electron discharge device frequently used in the horizontal type deflection circuitry of a television receiver.

The beam power type of electron discharge device includes a cathode, aligned control and screen grid electrodes, a beam confining electrode including a pair of channel members with each member having a pair of substantially planar upstanding portions interconnected by a web portion, and an anode. Such devices are characterized by high power output, high power sensitivity, and high efl'iciency and for these reasons, as well as others, are extensively used in the horizontal deflection circuitry of television receivers.

It is well known, however, that certain receiver deficiencies do exist when presently available discharge devices of the beam power type are utilized therein. Perhaps the most prevalent or at least the most noticeable deficiency is the occurrence of spurious RF oscillations or snivets which usually appear on the viewing screen of the receiver as a series of either continuous or broken lines.

Although it is well known that numerous factors, other than the discharge devices, contribute to the RF oscillations or snivet problem, this does not preclude continued attempts to improve the discharge device. Further, an improved discharge device would reduce not only the criticality of the circuit componentry but also the criticality of the physical arrangement thereof.

One example of a known dis-charge device structural modification designed to alleviate the snivet problem is the distortion or dimpling of an anode in a manner such that the surface thereof, in the area of high electron beam concentration, is moved inwardly toward the screen grid electrode. Another structural modification has been the inclusion of oppositely disposed fin member within and aflixed to the anode in a manner such that the fin portion extends inwardly toward the screen grid electrode.

While the above modifications have improved the discharge devices and reduced the occurrence of snivets in a television receiver by improving the plate cur-rentplate voltage characteristic curves thereof, it has been 3,356,836 Patented Dec. 5, 1967 foundth'at furthermodification, which reduces the spacing} between the anode. and other electrodes, is limited because of the undesired increase in secondary emission from the anode and a tendency for arcing to occur between the anode and the other electrodes of the discharge device.

Additionally, it has been found that the reduction in the occurrence of snivets in a television receiver due to the previously mentioned structural modifications is chiefly confined to receivers which utilize only the VHF band of frequencies. It has been found that these spurious RF oscillations still occur, but the frequency thereof is such that the oscillations are outside of the VHF band. However, the increased emphasis and use of the UHF band of frequencies in presently manufactured television receivers has again projected the snivet problem into undesired prominence since the oscillations which were previously unobservable to the viewer now appear in the UHF band.

Therefore, it is an object of the invention to provide an improved electrode discharge device having a reduced susceptibility to the generation of relatively strong spurious RF signal radiation.

Another object of the invention is to provide an electron discharge device of the beam power type having enhanced characteristics when utilized in the deflection circuitry of a television receiver.

A further object of the invention is to provide a beam power type electron discharge device having enhanced utilization in a television receiver and including a beam confining electrode which is economical to fabricate and adapted to an automated fabricating process.

A still further object of the invention is to provide an improved beam confining electrode for a beam power type electron discharge device which reduces the susceptibility of the discharge device to the generation of strong spurious RF signal radiation when operated in the horizontal deflection circuitry of a television receiver. I

These and other objects of the invention are achieved in one aspect of the invention by an electrode disposed intermediate the cathode and the anode of an electron discharge device to provide a nonuniform spacing intermediate the electrode and the cathode and intermediate the electrode and the anode.

For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the accompanying drawings in which:

FIG. 1 is a cross-sectional schematic representation of a typical prior art electron discharge device of the beam power type;

FIG. 2 is a graphic representation of the potential gradients of the prior art device of FIG. 1;

FIG. 3 is a cut-away elevation representation of a beam power type electron discharge device illustrating the electrode spacings obtained with an improved beam confining electrode; I

FIG. 4 is an elevational view of one embodiment of an improved beam confining electrode;

FIG. 5 is a cross-sectional view of FIG. 4 taken along the line 55; and

FIG. 6 is a graphic illustration showing the potential gradients of the device of FIG. 4.

Referring to the drawings, FIG. 1 illustrates a beam power type electron discharge device 7 typical of the prior art. The discharge device 7 includes an electron source or cathode 9, aligned control and screen grid electrodes 1-1 and 13, respectively, a beam confining electrode 15, and an electron receiver or anode 1 7. The anode 17 preferably, not necessarily, includes a pair of oppositely disposed fin members 19.

As can be readily observed, the beam confining electrode 15 includes a pair of substantially planar

upstanding portions

21 and 23, and each of the

upstanding portions

21 and 23, respectively, is disposed intermediate the screen grid electrode 13 and the anode 17. Moreover, the planar form of the

upstanding portions

21 and 23 provides a substantially uniform spacing, as measured in a plane normal to the longitudinal plane thereof, between each of the

upstanding portions

21 and 23 and the anode 17. In a like manner, a uni-form spacing is provided between each of the

upstanding portions

21 and 23 and the screen grid electrode 13.

As to the reasons for the generation of RF signals in a beam power type discharge device and the phenomena known as snivets" in a television receiver utilizing such devices, no exacting explanation is, at present, known. However, numerous theories have been advanced and any one or all may be applicable and appropriate.

For instance, it is well known that beam power type electron discharge devices have a family of plate currentplate voltage curves at various values of control grid electrode voltages which are characterized by an initial portion of the curve having a rapidly increasing plate current with respect to plate voltage, a secondary portion having a slowly increasing plate current with respect to plate voltage, and a sharply bending or knee portion intermediate thereto. Further, a great number of beam power type discharge devices exhibit curves having discontinuities and hysteresis loops in either or both the initial portion and the knee portion thereof. As a result, when the operational load line of the device passes through either the initial or knee portion of the curve, which it usually does when such devices are utilized in the horizontal deflection circuitry of a television receiving, there exists a bistable condition wherein a single plate current value is obtained at two or more different plate voltage values.

With these facts in mind, the potential gradient existing within such a prior art type of discharge device is usually depicted substantially as illustrated by a curve A of FIG. 2. As can be seen, the curve A includes a point location 25 at or near zero potential which is usually referred to as the virtual cathode. Prior theoretical explanations indicate that the virtual cathode may perhaps best be described as a region of approximately zero potential having low electron velocity and high electron density.

Since the spacings intermediate the

upstanding portions

21 and 23 of the beam confining electrode 15 and the screen grid electrode 13 and intermediate the

upstanding portions

21 and 23 and the anode 17 are substantially uniform, it is believed that the virtual cathode at point location 25 is substantially in the form of a plane having height and width. Further, it is believed that this planar virtual cathode remains at the same point location 25 so long as the potential applied to the electrodes remains substantially unchanged.

However when there exists a bistable condition of potential on the electrodes, such as previously described, the planar virtual cathode shifts from the normal point location 25 to a second point location 27 as indicated by the curve B. Moreover, the virtual cathode in the form of a high electron density planar surface oscillates between the point locations 25 and 27, respectively, resulting in the generation of a relatively strong RF signal which is radiated from the device 7, picked up and transmitted through a receiver, and appears as snivets on the viewing screen of a television receiver.

Another possible explanation suggests that electrons are entrapped between the control grid electrode 11 and the beam confining electrode 15. Under the influence of the voltages on the electrodes 11 and 15, respectively, the entrapped electrons travel in an orbital path intermediate thereto. Since the spacing between the control grid electrode 11 and the beam confining electrode 15 is uniform throughout the longitudinal length thereof, it is believed that a relatively strong planar field of orbiting electrons is provided and this planar field of orbiting electrons oscillates at a frequency dependent upon the variations in potential applied to the discharge device 7. Thus, a bistable condition, such as previously described with regard to the plate current-plate voltage curves, causes the relatively strong planar field of orbiting electrons to oscillate at a frequency dependent upon the frequency of variation in voltages applied to the discharge device 7, and these relatively strong spurious oscillations appear as snivets on the viewing screen of the television receiver.

Other possible explanations include the suggestion that the discharge device 7 functions in a manner similar to a klystron wherein the electrons are bunched by applied potential variations due to the discontinuities in the plate current-plate voltage characteristic curves. Thus, spurious RF signals are generated by the substantially planar form of the bunched electrons.

Also, the beam confining electrode 15 may be considered as an electrostatic lens having a given focusing characteristic and surrounding field strength so long as the potentials applied to the discharge device 7 remain substantially constant. Moreover, either or both the focusing characteristic and the surrounding field strength of the electrostatic lens formed by the beam confining electrode 15 shift as variations in the potentials applied to the discharge device 7 occur. As a result, spurious RF oscillations are generated which are transmitted and appear as snivets.

In any event and regardless of whether or not any one or all of the possible theoretical explanations are applicable, it has been found that the generation of spurious RF oscillations in an electron discharge device can be virtually eliminated or at least greatly reduced by the provision of a nonuniform spacing between an electron emitting electrode or cathode and a grid electrode and a nonuniform spacing between the grid electrode and the anode or electron receiving electrode. Moreover, the above-mentioned improved results are obtained regardless of the fact that the plate current-plate voltage charactristics of the discharge may or may not include discontinuities or hysteresis loops therein.

Accordingly, FIG. 3 illustrates an improved beam power type electron discharge device 29 which includes an envelope 31 and a mount structure 33. The mount structure 33 has a cathode 35, aligned control and screen grid electrodes 37 and 39, respectively, an anode 41, and at beam confining electrode 43 disposed intermediate the screen grid electrode 39 and the anode 41.

The beam confining electrode 43, more clearly illustrated in FIGS. 4 and 5, includes a pair of substantially

identical channel members

45 and 47, respectively, which are spaced and interconnected by cross members 48. Each of the

channel members

45 and 47 includes a pair of

upstanding portions

49 and 51 interconnected by a web portion 53. The upstanding portion 49 has a corrugated or ridged and grooved section 55 with the depth 57 of the ridges and grooves extending in a plane normal to the longitudinal axis of the electrode 43. Similarly, the upstanding portion 51 has a corrugated or ridged and grooved section 59 with the depth 61 of the ridges and grooves extending in a plane normal to the longitudinal axis of the electrode 43. Also, the ridges of the ridged and grooved section 55 of the upstanding portion 49 and the grooves of the ridged and grooved section 59 of the upstanding portion 51 are preferably, not necessarily, in one plane normal to the longitudinal axis of the electrode 43. Further, the ridges of the channel member 45 and the grooves of the channel member 47 are preferably, not necessarily, in one plane which is also normal to the longitudinal axis of the electrode 43.

Thus, the corrugated or ridged and grooved section 55 of the upstanding portion 49 of each of the

channel members

45 and 47, respectively, provides a nonuniform and nonsymmetrical surface. Further, this nonsymmetrical surface, readily observable in FIG. 3, is located intermediate the screen grid electrode 39 and the anode 41 of the discharge device 29 and thereby provides a nonuniform and nonsymmetrical spacing not only intermediate the beam confining electrode 43 and the screen gn'd electrode 39, but also intermediate the beam confining electrode 43 and the anode 41. In a similar manner, the corrugated or ridged and grooved section 59 of the upstanding portion 51 of each of the

channel members

45 and 47, respectively, also provides a nonuniform and nonsymmetrical surface and spacing, not only intermediate the beam confining electrode 43 and the screen grid electrode 39, but also intermediate the beam confining electrode 43 and the anode 41. Moreover, the

depths

57 and 61, respectively, of the ridged and

grooved sections

55 and 59 are controllable and may be uniform although nonuniformity is preferred in order to further advance the desired nonuniformity and nonsymmetry of the spacing.

Thus, it is believed that the above-described nonuniformity in spacing provides a discharge device having a voltage gradient substantially as depicted in the illustration of FIG. 6 wherein there is provided a virtual cathode representing a field of electrons having not only height and width but also depth 63. Under such conditions, there is provided not a single relatively strong field of electrons but rather a plurality of relatively weak electron fields. When an unstable condition exists, such as the previously described plate current-plate voltage bistable condition, it is believed the oscillations of the electron field which do occur will be at a multiple of frequencies rather than a single frequency and no one frequency of oscillation will have sufiicient signal strength to cause the appearance of so-called snivets in a television receiver.

Alternately, it may be that the nonuniformity of spacing between the screen grid electrode 39Vand beam confining electrode 43 prevents the formation of a single relatively strong and substantially planar field of orbiting electrons. Rather, the orbiting electrons are divided into a plurality of relatively weak fields having different frequencies of oscillation due to the nonuniformity of spacing. Thus, no single spurious oscillating electron field has sufficient strength to be transmitted, picked-up, amplified, and appear on the viewing screen as a snivet.

Further, the above-mentioned provision of nonuniform spacing may have altered the lens-like action of the beam confining electrode 15, varied the surrounding field strength pattern thereabout, changed the bunching effect obtained with a substantially uniform spacing, or provided a combination of any one or all of the abovementioned conditions. In any event, the above-mentioned improved and desirable conditions have been provided without any measurable deleterious effects upon the known characteristics of the discharge device.

As a specific example, a control group and a test group of beam power type electron discharge devices having essentially similar parts except for the beam confining electrode were fabricated in substantially the same manner. The control group utilized a beam confining electrode which provided a uniform spacing between the screen grid electrode and the beam confining electrode as well as a uniform spacing between the beam confining elec trode and the anode. The test group utilized a beam confining electrode 43 which provided a nonuniform spacing such as previously described.

The control and test groups had substantially identical characteristic curves as well as substantially identical parameters such as average knee voltage, plate current to screen current ratio, high voltage cutoff, average plate current, and discontinuities and hysteresis loops at and below the knee area of the plate current-plate voltage characteristic curves. However, when tested in the same commercially available receiver, it was found that the presence of 'sni'vet's in the control group exceeded those of the test group by an amount in excess of a 10:1 ratio. Thus, there has been provided a unique and greatly improved electron discharge device having a greatly reduced tendency to generate undesired and relatively strong spurious RF signals. The discharge device includes an electrode which provides a nonuniform and nonsyrnmetrical spacing between the electrode and the cathode or electron source as well as a nonuniform and nonsymmetrical spacing between the electrode and the anode or electron receiver. Further, the provision of such nonuniformity of spacing in an electron discharge device of the beam power type utilized in the horizontal circuitry of a television receiver has greatly reduced the susceptibility thereof to snivets. Moreover, this reduction in snivet susceptibility is obtained without deleterious effec-ts upon the critical parameters of the discharge device. While there has been shown and described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.

What is claimed is: 1. An electron discharge device comprising: an envelope containing at least one electron emitting cathode, an electron receiving anode, and an electrode therebetween, said electrode being formed to provide a nonuniform spacing, said nonuniform spacing extending between the electrode and said cathode and between the electrode and said anode. 2. An electron discharge device comprising: an envelope containing at least one electron emitting cathode, an electron receiving anode, and an electrode therebetween, said electrode being formed to provide a nonuniform spacing, said nonuniform spacing extending longitudinally along and between said electrode and said cathode and longitudinally along and between said electrode and said anode. 3. An electron discharge device comprising: an envelope containing at least one electron emitting cathode, an electron receiving anode, and an electrode therebetween, said electrode being formed to confine the flow path of electrons from said anode to said cathode and provide a nonuniform spacing, said nonuniform spacing extending longitudinally along and between said electrode and said cathode and longitudinally along and between said electrode and said anode. 4. An electron discharge device comprising: an envelope containing an electron emitting cathode,

an electron receiving anode and a plurality of electrodes therebetween, at least one of said electrodes being formed to provide a nonuniform spacing, said nonuniform spacing extending longitudinally along and between said electrode and said cathode and longitudinally along and between said electrode and said anode. 5. An electron discharge device comprising: an envelope containing an electron emissive cathode, an electron receiving anode, aligned control and screen grid electrodes intermediate thereto, and a beam confining electrode between said screen grid electrode and said anode, said beam confining eletrode including a pair of spaced channel members with each channel member having a pair of upstanding portions interconnected by a web portion and each of said upstanding portions being formed to provide a nonuniform spacing, said nonuniform spacing extending longitudinally along and between said upstanding portion and said screen grid electrode and longitudinally along and between said upstanding portion and said anode. 6. An electron discharge device comprising: an envelope containing an electron emissive cathode,

an electron receiving anode, aligned control and screen grid electrodes intermediate thereto, and a beam confining electrode between said screen gridelectrode and said anode, said beam confining elec trode including a pair of spaced channel members with each channel member having a pair of interconother upstanding member of each channel and the ridges of the ridged and grooved sections of one channel and the grooves of the ridged and grooved sections of the other channel in one plane normal to a plane extending longitudinally along said electrodes.

9. A beam confining electrode for an electrode discharge device comprising:

a pair of spaced channel members with each channel member having a pair of upstanding portions interconnected by a web portion, each of said upstanding portions having a section of alternate ridges and grooves, said ridged and grooved sections having a depth dimension extending in the direction of a plane normal to the plane of said upstanding portions.

10. A beam confining electrode for an electron discharge device comprising:

a pair of interconnected and spaced channel members screen gride electrodes intermediate said cathode and with each channel member having a pair of upanode, and a beam confining electrode between said standing portions interconnected by a web portion screen grid electrode and said anode, said beam conand each upstanding portion having a section of fining electrode including a pair of spaced channel alternate ridges and grooves of uniform depth measmembers with each channel member having a pair ured in the direction of a plane normal to the plane of interconnected and spaced upstanding portions of said upstanding portions, said ridges of one of and each upstanding portion having a longitudinally said upstanding members and said grooves of the extending alternately ridged and grooved section, other of said upstanding members of one of said each of said ridges and grooves of said sections channels and said ridges of said upstanding members having a nonuniform depth as measured along a of one of said channels and said grooves of said plane normal to the plane of said upstanding porupstanding members of the other of said channels tions, and each of said sections being disposed interbeing in a plane normal to the plane of said upmediate said screen grid electrode and said anode to standing members.

11. A beam confining electrode for an electron discharge device comprising:

a pair of spaced channel members with each channel member having a pair of upstanding portions interconnected by a web portion and each upstanding portion having a section of alternate ridges and provide a nonuniform spacing intermediate each of said ridges and grooves and said screen grid electrode and intermediate each of said ridges and grooves and said anode. 3 8. An electron discharge device comprising: an envelope containing an electron emissive cathode,

an electron receiving anode, aligned control and screen grid electrodes between said cathode and anode, and a beam confining electrode between said screen grid electrode and said anode, said beam confining electrode including a pair of spaced channel members with each channel member having a pair of grooves of nonuniform depth in the direction of a plane normal to the plane of said upstanding portions to provide a nonuniform spacing between said ridges and grooves and a plane substantially parallel to the plane of said upstanding portions.

References Cited spaced upstanding portions interconnected by a web portion and each upstanding portion having a ridged and grooved section extending longitudinally there- UNITED STATES PATENTS along and located intermediate said screen grid elec- 1479256 1/1924 Sande 313299 trode and said anode each of said rid es and rooves 2898504 8/1959 Norton 313-299 g g 3,217,203 11/1965 Cullen 313299 having a nonuniform depth as measured in a plane normal to the longitudinal plane of said channel members with the ridges of the ridged and grooved section of upstanding member and the grooves of the JOHN w. HUCKERT, Primary Examiner.

A. 1. JAMES, Assistant Examiner.

Claims

1. AN ELECTRON DISCHARGE DEVICE COMPRISING: AN ENVELOPE CONTAINING AT LEAST ONE ELECTRON EMITTING CATHODE, AN ELECTRON RECEIVING ANODE, AND AN ELECTRODE THEREBETWEEN, SAID ELECTRODE BEING FORMED TO PROVIDE A NONUNIFORM SPACING, SAID NONUNIFORM SPACING EXTENDING BETWEEN THE ELECTRODE AND SAID CATHODE AND BETWEEN THE ELECTRODE AND SAID ANODE.