. 24, 1946. |. wóLFF 2,413,276 CATHODE RAY APPARATUS Filed Nov. 19, 1942 2 Sheets-¿Sheet l f „iugm n INVENTOR Wmo? ATTORNEY Dec. 24, 1946. l. woLFF 2,413,276 CATHODE RAY APPARATUS Filed Nov. 19, 1942 2 sheets-sheet 2 / TTORNEY ¿naar Patented Dec. 24, 1946 UNITED STATES PA’E'ENT tries 2,413,276 oATHoDE-RAY APPARATUS Irving Wolü, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Dela Wall‘e Application November 19, 1942, Serial No. 466,129 12 Claims. (Cl. 2511-155) My invention relates to improvements in cath ode ray tubes and apparatus and particularly to tubes and apparatus and methods for developing a curvilinear or circular time base utilized for in dicating electrical phenomena. It has been proposed in the prior art to utilize a cathode ray tubehaving a target screen for measurements or for picture transmission where in the time base is evidenced by a closed curved 2 of the necessity of producing quadrature deflec tion potentials which for circular traces must be matched both as to quadrature relationship and potential variations. Thus a change in frequency in the applied quadrature deflection potentials requires a change in the circuits developing these potentials. In addition, the potentials for- such deflection must be relatively high especially in tubesY operating at relatively high voltage, to trace either on a luminescent screen as shown by obtain an intense trace on a luminescent screen. Heymann, 2,200,745, or on a target of the mosaic Such high potentials necessitate extensive equip type as shown by Hickok, 2,272,842. Tubes hav« ing luminescent screens wherein the cathode ray beam is deflected to form a closed curved trace, ment which is not only bulky but necessitates an increase in the weight factor wherefsuch appa ratus is utilized in aircraft applications. y In accordance with kmy invention I obtain `>a curved deflection trace in a cathode ray tube by such as a circle on the screen, have particular application in radio position and distance indi cating equipment wherein the distance or posi tion is indicated by a radial deflection of the beam from the normally produced circular trace. It has been customary'to form such curved closed traces utilizing quadrature deflection. For eX ample, two mutually perpendicular'pairs of de- _ ilection plates are supplied with sine-wave po tentials, one of which is in quadrature with the directing an electron beam into an axial mag netic or radial electrostatic vfield at an angle to the axis and with its projection tangent toa circle about the axis'of the field. I deflect the beam to vary> the angle of entrance into the-field to control and vary the pitch of the helical path of the beam. More particularly, I have found other. Such arrangements are not as iiexible as that the degree of angular deflection imparted to the beam is inversely proportional to the angle desired and inv addition require rather critical adjustment to maintain theV quadrature rela the beam makes with a plane perpendicular to the axis of the field. Still further, I direct the tionship. electron beam through the field thereby imparting ' - Among the objects of my invention are: to pro an eifective rotation to the beam and I'so limit vide apparatus for and a method of producing a 30 the field in length that the beam emerges from curved time base for cathode ray beam deilec the ñeld and continues in a‘direction determined tion, to provide means for obtaining curved time by the angle of entrance into the field and I then intercept the beam by a target, such as of the to phase delay or quadrature networks, to pro luminescent type, to provide the curved time vide apparatus wherein circular time base de 35 base. Following emergence from the field the flection may be obtained without recourse to electron beam may be given further radial de critically adjusted circuits, to provide a highly ilection, such as a signal deflection, to produce bases for cathode ray deiiection without recourse stable tube inherently capable of producing closed deñection traces having uniform curvature to indications of the phenomena to be observed. The foregoing description of the principles of provide a curved time axis in which substantially 40 my invention will be more readily appreciated by any relationship may exist between angular po references to Figure 1 wherein the apparatus or sition and time, and to provide a method and tube per se comprises an elongated envelopedy means whereby a spiral time axis may be ob having a neck portion 3 and a frusto-conical tained. These and other objects, features, and portion 5 which is provided at its closed end with advantages of my invention will become evident 45 a luminescent screen l. The electron beam is upon consideration of the following description developed by an electron gun preferably disposed and the accompanying drawings wherein: to direct the-beam at an angle to the longitudinal Figure 1 shows cathode ray apparatus, in sec axis of the envelope portions 3 and 5 and to one tional plan view, made and operated in accord side thereof and comprises the conventional ance with my invention; and 50 cathode 9, control electrode Il'connected'to the Figure 2 is a perspective View, partially in sec usual biasing source, a first anode I3 and a second tion, of a greatly simplified embodiment of my anode l5 so that the developed electron beam in an undeflected position is directed preferably per As indicated above, it is diificult to provide pendicularly to a radius of a circle surrounding closed curved traces in cathode ray tubes because 55 the axis andY at an angle to a plane normal to invention. Y - 2,413,276 4 quency, timing, and amplitude of the applied said longitudinal axis. The electron beam may be signal. grid modulated to vary the beam intensity such It should be particularly noted that the voltage as by applying potential variations across the applied to the deflecting plates 25-21 may be of terminals il, the shunt i9 shown in dashed lines being provided when no modulation is applied. Ul any desired time function and that the rate of angular deflection will approximately follow the The electron beam is developed by applying po same time function. To obtain uniform circular tentials between the cathode and the first and sweep a linear sawtooth deñection of amplitude second anodes, such as by a battery or potential sufñcient for one rotation may be used. However, source 2! provided with a bleeder 23. Situated on if it is desirable to spread any part of the scale, either side of the electron gun axis I provide means to deflect the electron beam such that the rate of travel along said longitudinal axis de» pends upon the degree of deflection. Such de~ flection means may comprise a pair of deflection plates ESL-2l although magnetic deiiection means may be provided in lieu thereof. g In accordance with my invention I direct the ‘deflected beam into a longitudinal axial field such as a magnetic iield of relatively long extent or length developed by a coil 29 enclosing the prin cipal portion of the neck section 3 between the intersection of the electron gun envelope portion and extending in the direction of the target or screen 1. The beam upon entering this magnetic an exponential or other type of sweep having non uniform voltage change may be employed. Blank ing circuits whose construction is well known in the art may be used to eliminate the effect of the return line by 4developing blanking signals which are applied across the terminals il. A spiral type of indication> either with uniform or non uniform angular velocity may also readily be ob tained with my tube. This result may be accom» plished by imposing some of the sweep deflecting voltage between the central radial deflecting elec trode 39 and the electrode ¿l l. A fixed radial elec~ trostatic field may be used in place of the longi tudinal magnetic iield in order to supply the ñeld will follow helical paths over an extent de radial force to cause the electrons to assume spiral termined by the angle of incidence between the entering beam and the longitudinal magnetic field netic field is to be preferred because of better fo paths. However, in general the longitudinal mag cusing action. A better understanding of the motion and tra throughout the length of the field. Upon termi jectory of the electron beam may be obtained by nation of the helical path, the electron beam conn reference to Figure 2 wherein an envelope en tinues to the screen 'l along unconstrained paths closes an electron gun 4 and target structure 8. and impinges the screen at a position determined In contradistinction to the previously described by the original deflection such as by the plates tube the electron gun 4 is located within the longi 25-21. Since the electron beam enters the field at these different angles and follows a path whose 35 tudinal field developed by the coil ß, no deflection being imparted to the beam since this showing is extent is determined by this incident angle, the merely for purposes of explanation. I position the beam emerges at various points lying on a circle, electron gun 4 to emit the electrons in a 'direc the beam then continuing along diverging paths so that the beam will follow a helical path to the screen l. The dashed lines show repre~ sentative beam paths for the 180 degrees of de fiection by the plates 25--2l~ The electron beam may be developed and deñected at relatively low potentials and further accelerated along the length of the envelope portions 3 and 5 by a series of electrodes surrounding the beam. For example, the electrodes 3 l-3'l may bein the form of electrically conductive coatings positioned in the order named in a direction from the electron tion at an angle to the axial magnetic field and tangential to a circle about the axial magnetic ñeld. Only one beam path is shown since no deflection of the beam is provided. Thus the dashed line in Figure 2 represents the beam mo tion along a helical trajectory intercepting the , target 6 at the point IB, this helical path >being of uniform diameter and pitch. It will be noted that the projection of the beam paths on a plane normal to the ñeld axis is always, tangentto the beam path as it leaves the electron gun. How gun to the screen and may be supplied with oper ating potentials from the potential bleeder 23. 50 ever, assuming that the location of the electron gun 4 is moved so that the beam is initiated at Further electrodes of similar formation, such as a dilferent angle to a plane normal to the longi the electrodes 39 and lll, may be provided along tudinal axial field, the radial 4deflection will be the frusto-conical portion E and may likewise different from that shown kand the point at which be operated from the potential source 2l or bleeder the beam intercepts the target will be displaced 23. While I have shown these electrodes as pro from the point lll such as to the point l2. The gressively more positive in the direction of the movement of the electron gun to initiate the beam screen, it will be appreciated that depending upon at different angles to this plane is thus equiva the length and diameter of these electrodes the lent to deflecting the beam by the plates 25-21 potentials applied thereto will vary with differ» in Figure 1 thereby causing the beam to describe ent constructions although the final electrode or CH a path on the screen 'l as modified by radial den electrodes such as 3B and ¿il are preferably operm ated at high positive potentialsl with respect to ` the cathode 9 to obtain an intense luminous trace on the screen l. Following emergence of the electron beam from the longitudinal magnetic field, radial deflection components may be imparted to the beam by a centrally disposed deñecticn electrode 43 to which deilection potentials, such as representative of ~ signal deñection, may be applied with respect to the surrounding electrode ¿i l. Thus the electrodes 4! and 43 provide a concentric system which de~ fleets the electron beam radially from the curved path or trace to provide an indication of the fre~ ilection components applied between the elec trodes 4I-43. The amplitude, that is the diameter, oi’ the trace may be controlled by varying the ratio be tween the field strength, such as the magnetic field delevoped by the coil 2@ and the potential applied to the various electrodes determinative of the electron beam velocity while the beam is under the influence of the magneticñeld. For example, the stronger the magnetic field devel cned by the coil 253, the smaller will be the diam eter of the trace developedppon the screen 'l for a given beam velocity. Similarly, the lower the velocity ,of the beam while under the influence 2,413,276 5 of the magnetic field, the smaller will be the di ameter of the beam trace on the screen 1 for a given magnetic field strength. Consequently, the 6 stantially parallel to and surrounding a longitu dinal axis, developing an electron beam, direct ing said beam into said field in a direction at an diameter of the trace may be adjusted within the angle to the said axis and tangentially to a right spatial limits of the screen by controlling the Cl circular1 cylindrical surface surrounding said ratio of the field strength to beam velocity. Pref axis, varying said angle at which said beam in erably, the magnetic ñeld strength is of the or tercepts said ñeld to cause said beam to follow der of 50 to 100 gausses, being relatively strong to helical paths, and intercepting said beam with a minimize eiîects produced by extraneous mag target surface. ' 3. Cathode ray apparatus comprising an evac netic fields. Furthermore, for particular con structions it may be found that the fringe por uated envelope, a target within said envelope tion of the field developed by the coil 29 interacts adapted to be impinged by an electron beam ap proaching said target substantially about an in the electron gun or deflection space so that magnetic shielding means such as a slotted shield axis normal thereto, electron beam forming 45 may be provided between the deñection plates means within said envelope positioned to direct 25----21 and the magnetic coil 29. The effect of an electron beam along an undeflected path at the shield 45 may be extended by an external an angle to the said axis, field means for estab lishing a ñeld of force extending along said axis shield as shown at 6l, the need for such shield ing arrangements being determined by the dis for rotating said electron beam around said'lon gitudinal and means adjacent said electron tance between the deflection plates 25--21 and gun for directing the electron beam at a varying the coil 29. ‘ angle to said longitudinal axis in a plane paral It will be appreciated that my method of elec tron beam deflection is not dependent upon the lel thereto and including said undeilected elec tron beam path. specific apparatus disclosed above, but that the 4. Cathode ray apparatus comprising an method may be practiced entirely by hand. For elongated evacuated envelope, a target near one example, an electron beam developed in any end of said envelope adapted to be impinged by manner may be deflected by hand such as by manually moving the electron gun through an an electron beam, electron beam forming means near the opposite end of said envelope positioned angle in a predetermined plane, developing a with its axis at an angle to the longitudinal axis magnetic field such as forming a ñeld between ‘ of said envelope, ñeld means for establishing a apertured pole faces to develop the helical mo field of> force` for rotating said electron beam tion of the beam, radially deflecting the beam by around said longitudinal axis, and means adja manually manipulating an electrostatic element following emergence of the beam from the longi cent said electron gun for directing the electron beam at a varying angle to said longitudinal axis tudinal magnetic field and intercepting the beam in a single plane parallel thereto and including to render it manifest. said electron beam. v While I have described my invention with par 5. Cathode ray apparatus comprising an ticular references to its use in tubes of the lu minescent screen type, it will be appreciated that evacuated envelope, a target near one end of and its application is not so limited, the principles 40 transverse to an axis extending within said en and advantages of my invention accruing equally velope adapted to be impinged by an electron to tubes of the television transmitting type beam, electron beam forming means near the opposite end of said envelope positioned to direct shown by the above-mentioned Hickok patent. an electron beam along a path at an angle to In addition, while I have described my invention particularly with respect to an axial magnetic and offset from the said axis, means for estab lishing a magnetic field having lines parallel to ñeld, it will be appreciated that an axial elec trostatic ñeld may be used substantially with and surrounding said axis for rotating said elec equal advantage. Such a ñeld may be developed tron beam in a helical path around said axis, between two concentric cylindrical electrodes and means adjacent said electron gun for di maintained at different potentials and extend- , recting the electron beam at a varying angle to ing over the space occupied by the magnetic coil said longitudinal axis in a plane parallel there 29 so that the electron beam is directed into the to and including said electron beam path. ñeld in a direction at an angle to the axis of the 6. Cathode ray apparatus comprising an equipotential lines of the field and with its pro-` elongated envelope, a target adjacent one end jection tangent to a circle about the axis of the of said envelope, an electron gun adjacent the opposite end of said envelope positioned to de field. Furthermore, while I have described only two particular embodiments of my invention, it velop and direct an electron beam at an angle to will be appreciated that many variations thereof and offset from said longitudinal axis, means adjacent said gun and said longitudinal axis to will occur to those skilled in the art and that my invention is not limited to the speciñc apparatus 60 deilect the beam in a plane parallel to said axis and magnetic means to develop a longitudinal shown or its mode of operation except as set magnetic iield extending from the point of inter forth in the appended claims. section most remote from said target and in a I claim: direction toward said screen, parallel to said l. The method of defiecting an electron beam over a target surface comprising sweeping the 65 plane, and surrounding said axis to direct said beam toward said target along helical paths. beam in a plane through a predetermined angle, 7. Cathode ray apparatus comprising an developing an axial magnetic field having lines evacuated envelope, a luminescent target adja of force in said plane but at an angle to said cen't one end -and intercepting a Alongitudinal beam and to one side of the centrally .disposed axis of said ñeld to cause said beam to follow 70 axis Within said envelope, an electron gun in cluding a plurality of apertured anodes with the helical paths, and intercepting said beam with a apertures aligned along a line disposed at an target surface. acute angle to the longitudinal axis of said en 2. The method of deflecting an electron beam velope to develop and direct an electron beam over a target surface comprising developing an axial field having lines of force extending sub 75 in a plane parallel to said longitudinal axis, de 2,413,276 8 flection means to shift the direction of said beam in said plane, magnetic means to develop a longitudinal magnetic field substantially paral lel with said axis and intercepting the plane of deñection of said beam to sweep said beam in 5 screen, a pair of deflection plates adjacent said electron gun to deflect the electron beam in a plane intercepting said magnetic ñeld parallel to the lines of force of said ñeld to cause said beam to follow a multiple of helical paths intercepted combination with said deñection means over a by said screen in a curved trace thereon, and a curved path on said target and a pair of tele scoped concentric electrodes between said mag netic means and said target to deflect said beam in a direction radially of said longitudinal axis. 10 pair of telescoping concentric electrodes adapted to have Aa signal deñection potential applied therebetween positioned Without the magnetic ‘ ñeld developed by said coil and closely adjacent 8. Cathode ray apparatus comprising an said luminescent screen to radially deflect said evacuated envelope, a luminescent screen posi electron beam from said curved trace. tioned transversely of and at one end of said 10. The steps in the method which comprises, envelope, an electron gun at the opposite end of producing a ñeld, projecting an electron beam said envelope positioned to develop and direct an 15 into said ñeld at an angle to the lines of force electron beam alongV an initial path at an angle Y thereof, and causing the electrons of the beam to said screen, an elongated magnetic field de to travel in a helical path through said field and veloping coil positioned with its longitudinal axis cyclically varying said angle'to vary the path substantially normal to said screen and at an and cause the electron beam to pass through angle to the initial path of Said beam to develop 20 a plane at a multiplicity of points of a continu a magnetic iield in the path of said beam, a pair ous curve around the axis of said field. of oppositely disposed deflection plates, one on 11. The steps in the method which comprises, either side of the undeñected path of said beam producing a constant ñeld, projecting an electron and adjacent said electron gun to deflect the beam into said ñeld at an angle to the lines of electron beam in a plane parallel to and offset force thereof, and causing the electrons of the from the axis of said magnetic coil, and a pair beam to travel in a helical path through said of concentric telescoping electrodes along said field and cyclically varying said angle to vary axis and closely adjacent said screen to radially the path, and cause the electron beam to emerge deñect said electron beam from the path on said from the iield at a multiplicity of substantially screen determined by the angle of deñection in 30 contiguous points of a circle having its centerV said plane. in the axis of said ñeld. 9. Cathode ray apparatus comprising an 12. 'I'he method of producing a circular trace evacuated envelope, a luminescent screen at one on a target which comprises, producing a constant end of said envelope, an electron gun at the oppo- field, projecting an electron beam into said ñeld at an angle to the lines of force thereof, and causing the electrons of the beam to travel in a site end of said envelope positioned to develop and direct an electron beam along an undeiiected path not intercepted by said screen, a magnetic ñeld generating coil surrounding a portion of said envelope and positioned to develop a ñeld having lines of force at an angle to and inter cepting the undeñected path of said beam, elec trode means in the region of said magnetic iield to direct electrons in combination with said ñeld along a helical path toward and upon said helical path through said iield, cyclically varying said angle to vary the path and cause the elec tron beam to emerge from the ñeld at a mul tiplicity of substantially contiguous points of a circle having its center in the axis of said ñeld, and causing the emerged ray to Strike said target. IRVING WOLFF.