US2459732A - Electrical system - Google Patents

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US2459732A
US2459732A US657175A US65717546A US2459732A US 2459732 A US2459732 A US 2459732A US 657175 A US657175 A US 657175A US 65717546 A US65717546 A US 65717546A US 2459732 A US2459732 A US 2459732A
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magnetic
cathode ray
lines
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ray tube
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William E Bradley
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Space Systems Loral LLC
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/56Arrangements for controlling cross-section of ray or beam; Arrangements for correcting aberration of beam, e.g. due to lenses

Description

Jan. 18, 1949.
W. E. BRADLEY ELECTRICAL SYSTEM Filed March 25, 1946 INVENTOR. WILL/AM E. BRADLEY WWW w QTW ATTORNEYS Patented Jan. 18, 1949 ELECTRIC L SYSTEM William E; Bradley, Swarthmore, Pa., assignor, by .mesne assignments, to Philco Corporation,
corporation of Pennsyl- Philadelphia, Pa., a
Vania Application March 26, 1946, Serial No. 657,175
invention relates in general to cathode ray tube scanning methods, and more particularly concerns novel and simplified apparatus adaptable to cathode ray picture tubes for accomplishing keystone compensationl Generally, in cathode ray television systems, scanning of a screen is eiiected by an electron beam within a cathode ray tube; Beam deflection is-caused by horizontal and vertical sawtooth sweep voltages or magnetic fields which Claims. v (01.250-157) tion ,vvas accomplished in a, number of ways but in all cases it considerably complicated the sweep circuits and added the need for critical adjustment to the system. These modulating circuits resulted in additional stages, thus increasing cost 1 and constituting an added source of failure.
ordinarily produce a rectangular raster of substantially horizontal lines. In certain television pick-'up devices or cameras, as for example the icono'scope, the axis of*the cathode ray electron gun is at an angle to the screen surface being scanned. If then the scanning pattern is formed by horizontal and' vertical deflection voltages or fields having constant periods and amplitudes, the raster will not be rectangular. Thus, the horizontal scanning lines uppermost on the It has been discovered that the keystoning problem could be more convenientlyv and economically handled through the controlled distortion of the electron beam movement by establishing a comparatively weak, continuous magnetic field through the cathode ray tube. Thus,
in co-pending application of' Fisher and John, SerialNo. 580,564, filed March 2, 1945 now abandoned and entitled Television system, it was shown that the addition to the tube structure of ap'a'ir of small,-permanent magnets, suitably screen, which are furthest from the electron gun,
will be longer than thelowermost horizontal lines, nearest the gun, with the result that the scanning raster'is trapezoidal, or keystone, in shape. This trapezoidal efiect is highly undesirable in camera tubes.
In television projection type receivers, mechanical and optical considerations often" dictate th at'the image presented upon the face of a cathode ray'tube be projected upon'a viewing screen which is not normal "to the optical axis ofproj'ection. If thefimage presented upon the oathode ray tube were rectangular,-as would be the case where" uncompensated constantperiod and amplitude sweep voltages or fields are used, then the" picture appearing upon the viewing screen would be keystoned in shape. I
{In both camera and projectionreceiver systems, the keystone effect is a distortion which must be eliminated. In the camera tube; a compensation must'be made so thatthe actual-scanning raster is rectangularjwhereas in'the receiver tube mentioned, a keystone distortion-must be introduced to provide a trapezoidal cathode ray tube image which, in combination with the skew projection, produces a final image on the viewing screen whichis rectangular, asdesired'.
' Heretofore, the introduction or the removal of akeystone effect has been accomplished electrically' within' the sweep circuits; As an example, it has been the practice to modulate the horizontal deflectionf voltage with a predetermined component of the vertical sawtooth defiectionvoltage, in that phase'which would providethe'propertrapezoidal effects This modulaoriented with respect to the cathode ray tube electron beam, would produce or compensate for akeystone'raster. l i
There has, however, been a limitation on the extent of the use of the system disclosed in the aforementioned application, 'which results from a second distortion introduced, in addition to the keystone eifect. Thus, although the magnetic field formed a substantially trapezoidal raster, it also had the effect of bowing the horizontal scanning lines, such that a high degree of picture excellence was unattainable.
The present invention contemplates and, has as a primary object the; provision of simplified, inexpensive and non-critical apparatus adaptable to cathode ray tubes for accomplishing keystone compensation without theintroductionof other and undesirable distortion. Generally, the apparatus of this invention involves means for producing a plurality of fixed and continuous magnetic fields which extend through a cathode ray tube and which are uitably disposed relativeto an electron beam passingtherethrough.
'It is another object of the present invention to provide magnetic means for producing a keystone eiiect in acathode ray tube which in itself causes substantially no displacement of the image center relative to the center of the screen.
A further object of this invention is to provide a simplified magnetic structure for producing the magnetic field required for keystone correction or trapezoidal correction of a scanning raster.
A still further object of the present invention is to provide a simplified magnetic structure for producing two magnetic fields within a cathode ray tube, one ofsaid 'fields being substantially uniform and the other being distorted; in a, predetermined manner,
These and other objects of thepresent invention Will now become apparent from the following detailed specification taken in connection with the accompanying drawings in which Figure 1 is a diagrammatic representation of a cathode ray tube and" illustratessthe' electron beam thereofrelative' to "the m aghetic fields established to provide a keystone effect;
Figure 2 is a front view of the screen of the:
cathode ray tube illustrated in Figure 1;,and.
Figures 3A, 3B, and 3C are a numbefo'fvi'ews' of a cathode ray tube and 'atmagnetic structure for producing the particuIar 'fielclsillustrate'd in Figure 1. i
Referring now to Figure 1, there is illustrated a conventional television receiverrcathode ray tube V II, having, as is well understood in the art, an evacuatedglass envelope J2 and a plugin' tubebase I3. Within the glass structure I2 is an electron gun.- l *f-or igenerating an electronibeam J 5i This electron gun: it. includes" at least a heatercathode conibination aacontro'l .gridfor determim ingaelectr'on beamintensity and a number of accelerating? electrodes. 'iThe electron i beam: 1 5 is directed tow'ard and impinges tupon ra fiuorescent soreen coating 1 l 6 :on thezinnerv surface: of the face ofz-glasssenv'elopef 12. I
- .Inaorder'to" provide aisharply defined spot-on theiscreen I16;thezelectronzbeamiis focused 'thereon by a magnetic zfocusing; coil 11-, slipped over the neck' of the glass envelope d2; its-illustrated, and
energized-byansadjustablecurrent from -a-source;
not shown; "The magneticifield ofithe'i focus-coirl l -is substantiallyraxial-within. the tube, that is, parallel --to the? electron beams-l 5. Focusing may also'b'e accomplished :electrostatlcally by suitableelectrodes withinthaelectrongun structure t i.-
In television -apparatus, it -is necessary to sc-an. the fluorescent screen with the electron-.beamd 5.-
This ;is\ generallyaocomplishedlby generatingtwc scanning-potentials; horizontal and vertical, and
appl-ying'these to mutuallyperpendicular deflecting means on the-cathode ray tube; -As illustrated in Figure 1, the deflec ing means comprise -,a,-mag netic defiection yol ze (2:1 .1 which-:is woundwith two coils having mutually perpendicular a Xes towhich;coilsrthedefiecting signals are-applied:v The horizontal scannin signal frequency is apredetermined multipleflof-thevertical scannin signal frequencyso thatprdinarily a substantially rectangular .raster. of .hor'izontal' lines obtained upon the fluorescent screen" 161. 'It is clear. that:- the conventional" type electrostatic deflection cathode ray,Itube couldjbe .usedto provide the scanning raster instead' 'of' t'he magnetie deflection tubeillustrated v v a 1 b Aspreviouslymentioned; there are numerous applicationsof receiver cathode ray'tubessuch as. H, Figure-1 ',.wherein the image generated upon the fluorescent screen-1'6 is projected upon a screenand wherein the screen axis is ot normal to the optical axis of projection. With .such an arrangement,:.theimageupon the screenwill have 4 the scanning beam progresses from the top of the raster 23 to the bottom thereof.
In accordance with the principles of the present invention the keystoned raster 23 is obtained upon fluorescent screen [6 by the use of conventional typelscanning signals app b dflection yoke 2H which signalsit'endito. producei'a rectangular raster, and by the use of two opposed magnetic fields 25 and 26 having field lines which extend through the cathode ray tube II and are substantially perpendicular to the axis of the tube and of theundeflecte'dzcathode ray beam and substantiallyl'paralleltoithe horizontal scanning lines of the raster 233 Magnetic field filindicated by the plurality of crosses; Figure .1; isdisposed adjacent the fluorescent screen l6 and is directed into the paper. The effect of a field so oriented is to uniformly deflect the electron beam I5 upward as illustrated by the curvingloflthe'beam l5 as-dt passes through-the field1region25. :If the beam-=l 5 ordinarilwwould, trace 'outa rectangular patternon the-fluorescentscreen lfi then the altered-iangle.'of approaehlintroduced by field 2 5 results-ins-a.keystonetraster sincethe path taken=by-thebeam 15 to :the-upper scanning lines-is longer than that (taken "tothe-- lowerhorizontal scanning (lines.-
The fie1d-25, generated ibysmeans to[be herein-- after :described is-preferably, a uniform fieldthat is; the lines either-field are essentiallyparal lel to each-otherand evenly distributedlas they.
traverse the-cathode raytube l In Furthermore' itl picture distortion; and is illustratedin- Figure 2. Thus,- the eflectof magnetic field: 25 acting alone is to produce a substantially trapezoidal raster 23 havingzsloping .sides, but wherein the horizontal: scanning; lines are bowed and fall tween \the limits of -curved, ..broken --lines 3! and. 32
Magnetic field 2e is.-disposed betweenttl' e :mas netic field 25 and the beam -defiecting- -means' 2il and extends through the acathode ray tube in: a direction'or sense opposite-to field-25L It also is; a constant field. As indicatedxby tile -plurality: of points-in Figure 1,. magnetic/field 26- is .substantially normal to and: directedout- -ofg-rthepaper. It---willbe: apparent that the-ueffect of magnetic field lines 2 6- is to-direct the-scanning; electron .beaml5zdownward asvindicated by thebeamcurvature in theregion-ofthe-lfield 25"; {soas to compensate-forthe upward -defiection .eifect. of field 25. In this-manner, fields-25wand=2 acting together-produceno resultant deflection :01'. the scanning pattern uponthe screen-- IS.
The magneticfieldgfi-is non-uniform; by which is meantthattthe field-lines-thereofl are-noLuniformly distributedand-.mutuallyi parallel. 'It -is' preferred thatthe magnetic fielddlibeestablishedl; by: two oppositearnagnetie poles. relativelyr com; centrated as disclosed in connection with the aforementioned application of Fisher and John. Also as disclosed in this application, the non- A uniform field 26 established by concentrated ophorizontal scanning lines, and the amount of key stoning is dependent upon the amount by which field 25 exceeds field 26. Generally, with conventional type receiver cathode ray tubes, field 25 of the order of twice the strength of field 26. The final trapezoidal pattern is, as illustrated in Figure 2, undistorted and centrally located upon the fluorescent screen l6. -'I 'he apparatus specifically described includes a; cathode ray target which is fiat or slightly curved. This invention applies best to tubes with such screens, but it may be practiced to some advantage with tubes having other types of screens. I
. The procedure for establishing the, required magnetic fields 25 and 26 may be greatly varied. One embodiment of a magnetic structure capable of producing the required fields is illustrated in Figures 3A, B and C. In these figures, there is' dia'grammatically shown a cathode ray tube ll. as in Figures 1 and, 2. Figure 3A is a top view of the tube and magnetic structure. Figures 3B and'BC are side and front views of the tube and correspond with the views of Figures 1 and 2. The magnetic structure comprises inexpensive means of obtaining the uniform strong field 25, and the non uniform comparatively weak field '26, and includes a pair of comparatively large, curved, soft steel pole faces 35 and 36 placed about the screen end of the cathode ray tube H. A pair of magnets 31 and 38 are placed adjacent the pole pieces 35 and 36 respectively and at an angle thereto.
{The magnets 31 and 38 are preferably permanent magnetsjalthough electromagnets may be used with equal efiect. As illustrated in Figure3A the extended pole pieces 35 and 36, magnetized by the bar magnets 31 and 38 establish the substantially'uniform magnetic field 25 adjacent the screen of the tube. The free ends of'the magnets 31 and 38, that is, those ends not in contact with pole faces 35 and 36, establish the comparatively weak and non-uniform field 26, located between the neck of the cathode ray tube and magnetic field 25.
Summarizing the above, a keystone compensation isobtained through the use of a uniform magnetic field and a non-uniform magnetic field of predetermined strength, each generally substantially transverse to the cathode ray beam. The resultant scanning pattern is undisplaced upon the tube target screen. The strength of the uniform field is adjusted so that there is no pattern displacement and the strength of the non-uniform field is adjusted so that there is no horizontal line curvature in the raster. If it is desiredto reverse the keystone effect illustrated in Figure 2, then the bar magnets illustrated in Figure-3 may bereversed in polarity tojreverse the direction of the fields.
'l'teduced'to its elements, the principleunder- 6 lying the present invention is as follows. electron beam which may occupy any region of a square pyramid, provided by the electron gun and the deflecting system, traverses a region occupied by a magnetic field '26, this field 26 acts.
on the beam to an extent depending on the in. tensity of the portion of the field traversed to introduce a keystoning of strength S1, a distortion D1 in the linearity of the scanning lines, and a displacement Y, in the vertical position of the scanned area on the screen. After having left the region where the field 26 has a substantial effect, the beam encounters a second .field 25, which also introduces similar efiects,which may be designated keystoning S2 distortion D2 and displacement .Y2. The fields have opposite senses, so that the net effect on the screen is akeystoning of strength S2S1=So, a distortion of extent D2D1=D0 and a displacement of extent Y2'Y1- Yo.
Inasmuch as the keystoning S varies with the.
tangent of the angle which the axis of the beampyramid makes with the undisplaced beam, the
distortion D varies with the barrelling or spread of the field, and the displacement Y varies with the tangent of the angle between the axis of the beam-pyramid and the undisplaced beam, as well as with the distance between the field, producing the displacement on the screen. The two fields 26 and 25, which are at different distances from the screen and of opposite senses may be combined to balance out the distortion D0 and the displacement Yo, while leaving the desired amount of keystoning So. So will, of course, be less than S2. I
The above description and the figures are related specifically to keystoning the image on a receiver type cathode ray tube. The application of this magnetic keystone method to cameratype the receiver illustration above a trapezoidal image was required. It is further evident that there are various other magnetic and electromagneticstructures which may be utilized to establish the proper fields.
Since various modifications and extensions .of-
the principles hereinabove set forth may become evident to those skilled in the art, it is preferred that the spirit and scope of the invention be defined by the appended claims.
I claim:
1. In combination with a cathode ray tube having a fluorescent screen, a magnetic structure providing within said tube a plurality of continuous and fixed magnetic fields, one of said fields being of predetermined uniform configuration and being disposed adjacent said fluorescent screen and the other field being of non-uniform configuration, said first field producing a keystone effect at said screen with the horizontal lines bowed and the second field producing a compensation for the bowing of the horizontal lines.
2. In combination with a cathode ray tube, said tube having means-for generating an electron beam, means for deflecting said beam in accordance with scanning signals and a fluorescent screen; a magnetic structure providing within said tube a plurality of continuous and fixed magnetic fields, said fields being of predetermined uniform and non-uniform configuration, said fields being disposed between said cathode ray defiectingimea'ns andwsaid-fluorescent screemoner of saidifields producing; keystoning of-the -raster atisaidscreen withzthe horizontal lines bowed and the: other of said fields of less-strengththan 'said first: field producing a compensation to. correct for said bowing. M
:3. llnicombinationiwithvacathode ray tube havingazmeansfor generating an electron. beam,
means for deflecting saidf beam .in accordance.
withiscanning signals and: a fluorescent! screen; a magnetic structure providin -within "said tube. a plurality; of continuousiiand fixedimagnetic field's,
saidiifields being of predetermineduniform. and.
non-uniform configuratiomsaid fields beingydisposedzbetween said: cathode .ray 'defiectingime'ans and saidfiuorescent screen, one of said :fieldsiproducing'keystoning of the raster at said screen with'the horizontal lines bowed and the other 'of said fields of less strength than said first field means for deflecting said beam in accordance.
with scanning signals and a screen, means forcontrolling the keystone effect uponsaid screen comprising means for establishing two magnetic fields of predetermined configuration within said cathode ray-tube and between a deflecting meansan'd said screen; oneof said fields beingin a plane transverse tothe axis of saidbeam and producing keystoning at said screen, the other of said fields being in a plane transverse to the axis of said beam and'in opposed direction to said first field.
5. In television apparatus, a cathode ray tube having means for generating an electron beam, means for deflecting said beam in accordance with scanning signals and a screen, means for controlling the keystone efiect uponsaid screen comprising means for establishin two magnetic fields-oi predetermined configuration within said cathode ray tube and between said deflecting means and said screen, one of said fields being substantially uniform and the other'of said fields being non-uniform, said fields being substantially continuous andtfixed, one of said fields being in a plane transverse to the axis of-said beam andiproducing keystoning'at said screen, the other of said fields being in a plane transverse to the axis of said beam and in opposed-direction to said first field, and said other field compensating for bowing distortion produced by said one of said fields.
6; In television apparatus, a cathode ray tube having means for generating an electron beam, means for deflecting said electron beam in accordance with scanning signals and a target s'creen,.means for producing a first magnetic field within said cathode ray tube and adjacent said target screen, said first magnetic field deflecting said electron beam at an angle to said screen, means for generating a second magnetic fieldadjacent said first mentioned deflecting means for deflecting said electron beam at an angle to said screen andopposite to said first mentioned angle, whereby said first and second magnetic fields providea keystone compensation upon said target screen.
7; In a television receiver, a cathode ray pictureftube having means for generating an electron beam, a fluorescent screen and means fordeflecting said electron beam in accordance-with scanning signals to; provide. a scanning raster generating-av first rmagnetic :field withinisaidi cathode ray tube: substantially parallel tOF SBid' a fluorescent SOIJGBIIfiaTId adjaoentrthereto, means;
for generating-. a second magnetic: field: within: said cathode ray :tubeof opposite: direction relaw tive to said-first magnetic 'fieldi and disposed Lad jacent' to saidtdeflecting, means.
'8; In:atelevision receivenia cathode ray pic-' ture tubetiihavingi means rforigenerating an :electron' beam, a: fluorescent screen? and means for deflecting said-electron beamsinzaccordance with scanning signals: to: provide. 5 a scanning masters upon said: screen; Ime'ans; tori introducing-l azi-keystone: effect-r into: said raster I comprising 'meansi for generating a first: magnetic flel'd w-ithin said-*- cathode ray tube substantially parallel ito s'aidt fluorescentscreen and adjacent 'thereto; means? for generating asecond magnetic field' within said cathoderay tube of opposite "direction-"relie tive to said first magnetic-field anddisposed ad jacent to said deflecting means;- sa-i'd 'fl'rst magnetic field being substantially uniform, I said sec-- ond magnetic field being non-uniform.
9; In a television receiver, a cathoderay picture tube-having means-for generating an electrom beam, a fluorescent screen and means for" de-' fleeting said electronbeamdn accordance with scanning signals to provide a scanning'raster upon-said screen, means for introducing a ke stone effect into said raster coniprisingmeans for generating a first magnetic field within said cathode ray tube substantially parallel to'said fluorescent screen; and adjacent thereto; "means for generating a'secondm'agneticfield within said cathode ray tube of opposite directionrel'ative' to said first magnetic field.and disposed adjacent? to said defi'ectingm'eans, saidfirst magnetic 'field' being substantially uniform, said second. magnetic field being non-uniform, said means for' generating, said first] and second magnetic field comprising a pair of oppositely, disposed. ,pfole pieces .of magneticlmat'erial. and a pair of. mag,- nets in contact with said polepieces.
10."Th'e method of deforming 'thelscanning; raster of a television cathode ray. tube I control keystoning which comprises theusteps of estab-v lishing a first? uniform and continuous; magnetic. field extending through said" tube in one direc-. tion, and establishing a second continuousuand: non-uniform magnetic field adjacent said. first; magneticifield and extending through said tube in .a direction opposite .tQ-said .fi'rst magnetic; field;
11'. In a television cathode ray. .tube ,having means for producing annelectroncbeam, means for directing said electronbeam ataefluorescent screen, means for deflecting. said ,electronbeam in accordance with. horizontal andrvertical die.- flection scanning signals to produceaa rasten .o horizontal scanning linesauponsaidl fluorescent screen, said horizontal scanning signals being of higherirequency than saidwertical scanning sig nals, means for substantially uniformly varying: the length, ofi said horizontal. scanning lines toprovide akeystone. effect comprisingimeansifor establishing a first magnetic field havingwcon tinuous and substantially uniform field lines through. said cathode ray tube substantially, parallel to saidhorizo'ntallines, saidfirstmagnetic field being disposed adjacent to i said fluorescent screen, means fo iestablishing.;a-second magnetic field having continuousand non-uniform r-fisld lines through said cathode ray tube and of opposite direction relative to said first magnetic field lines, said second magnetic field being adjacent to said first magnetic field lines.
12. In a television cathode ray tube having means for producing an electron beam, means for directing said electron beam at a fluorescent screen, means for deflecting said electron beam in accordance with horizontal and vertical deflection scanning signals to produce a raster of horizontal scanning. lines upon said fluorescent screen, said horizontal scanning signals being of higher frequency than said vertical scanning signals, means for substantially uniformly varying the length of said horizontal scanning lines to provide a keystone effect comprising means for establishing a first magnetic field having continuous and substantially uniform field lines through said cathode ray tube substantially parallel to said horizontal lines, said first magnetic field being disposed adjacent to said fluorescent screen, means for establishing a second magnetic field having continuous and non-uniform field lines through said cathode ray tube and of opposite direction relative to said first magnetic field lines, said second magnetic field being adjacent to said first magnetic field lines, said first and second magnetic fields acting to displace said raster in opposite directions, whereby substantially no resultant displacement of said raster is obtained.
13. In a television cathode ray tube having means for producing an electron beam, means for directing said electron beam at a fluorescent screen, means for deflecting said electron beam in accordance with horizontal and vertical deflection scanning signals to produce a raster of horizontal scanning lines upon said fluorescent screen, said horizontal scanning signals being of higher frequency than said vertical scanning signals, means for substantially uniformly varying the length of said horizontal scanning lines to provide a keystone efiect comprising means for establishing a first magnetic field having continuous and substantially uniform field lines through said cathode ray tube substantially parallel to said horizontal lines, said first magnetic field being disposed adjacent to said fluorescent screen, means for establishing a second magnetic field having continuous and non-uniform field lines through said cathode ray tube and of opposite direction relative to said first magnetic field lines, said second magnetic field being adjacent to said first magnetic field lines, said means for producing said first magnetic field including comparatively broad field poles, said means for producing said second magnetic field including comparatively small field poles.
14. In a television cathode ray tube having means for producing an electron beam, means for directing said electron beam at a fluorescent screen, means for deflecting said electron beam in accordance with horizontal and vertical deflection scanning signals to produce a raster of horizontal scanning lines upon said fluorescent screen,
said horizontal scanning signals being of higher frequency than said vertical scanning signals, means for substantialy uniformly varying the length of said horizontal scanning lines to provide a keystone effect comprising means for establishing a first magnetic field having continuous and substantially uniform field lines through said cathode ray tube substantially parallel to said horizontal lines, said first magnetic field being disposed adjacent to said fluorescent screen, means for establishing a second magnetic field having continuous and non-uniform field lines through said cathode ray tube and of opposite direction relative to said first magnetic field lines, said second magnetic field being adjacent to said first magnetic field lines, said means for producing said first and second magnetic fields comprising a pair of comparatively broad magnetic pole pieces and a pair of permanent bar magnets in contact with said pole pieces.
15. In a television cathode ray tube having means for producing an electron beam, means for directing said electron beam at a fluorescent screen, means for deflecting said electron beam in accordance with horizontal and vertical deflection scanning signals to produce a raster of horizontal scanning lines upon said fluorescent screen, said horizontal scanning signals being of higher frequency than said vertical scanning signals, means for substantially uniformly varying the length of said horizontal scanning lines to provide a keystone effect comprising means for establishing a first magnetic field having continuous and substantially uniform field lines through said cathode ray tube substantially parallel to said horizontal lines, said first magnetic field being disposed adjacent to said fluorescent screen, means for estabishing a second magnetic field having continuous and non-uniform field lines through said cathode ray tube and of opposite direction relative to said first magnetic field lines, said second magnetic field being adjacent to said first magnetic field lines, said means for producing said first magnetic field including comparatively broad field poles, said means for producing said second magnetic field including comparatively small field poles, said uniform field being substantially stronger than said non-uniform field.
WILLIAM E. BRADLEY.
REFERENCES CITED The following references are of record in'the file of this patent:
UNITED STATES PATENTS Number Name Date 2,177,688 Cawein Oct. 31, 1939 2,227,711 Gunther Jan. 7, 1941 2,255,039 Gunther Sept. 9, 1941 2,258,643 Degier et a1 Oct. 14, 1941 2,259,233 Tingley Oct. 14, 1941 2,264,567 Gunther Dec. 2, 1941 2,297,407 Gunther Sept. 29, 1942
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US2541446A (en) * 1949-01-04 1951-02-13 Barnet S Trott Image distortion corrector for cathode-ray tubes
US2574039A (en) * 1951-02-17 1951-11-06 All Star Products Inc Magnetic centering device for cathode ray tubes
US2591159A (en) * 1950-05-29 1952-04-01 Gilfillan Bros Inc Magnetic means for producing compensations and other effects in a cathode-ray tube
US2675501A (en) * 1950-10-31 1954-04-13 Rca Corp Electron beam focusing system
US2807740A (en) * 1955-10-14 1957-09-24 Hazeltine Research Inc Cathode-ray tube apparatus
US2859365A (en) * 1954-09-14 1958-11-04 Rca Corp Electron beam controlling apparatus
US2861209A (en) * 1953-12-14 1958-11-18 Hazeltine Research Inc Cathode-ray-tube beam-deflection system
US2879435A (en) * 1956-08-24 1959-03-24 Du Mont Allen B Lab Inc Cathode-ray tube
US2921226A (en) * 1956-05-24 1960-01-12 Philco Corp Apparatus for color purity correction in color television receivers
US2972073A (en) * 1955-08-31 1961-02-14 Rca Corp Electron beam controlling apparatus
US2999185A (en) * 1950-01-09 1961-09-05 Harry R Lubcke Television device
US3115544A (en) * 1956-04-25 1963-12-24 Hazeltine Research Inc Color-television receivers and deflection yokes
US3354337A (en) * 1966-02-28 1967-11-21 Zenith Radio Corp Convergence magnet pole shoes
US5023509A (en) * 1989-10-27 1991-06-11 Rca Licensing Corp. Color CRT-yoke combination having conforming corrective magnetic field means attached to the CRT
US6586870B1 (en) * 1999-04-30 2003-07-01 Sarnoff Corporation Space-saving cathode ray tube employing magnetically amplified deflection
US6674230B1 (en) * 1999-04-30 2004-01-06 Sarnoff Corporation Asymmetric space-saving cathode ray tube with magnetically deflected electron beam

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US2177688A (en) * 1936-12-24 1939-10-31 Hazeltine Corp Cathode-ray tube scanning system
US2227711A (en) * 1937-02-20 1941-01-07 Firm Of Fernseh Ag Deflecting device for cathode ray tubes
US2258643A (en) * 1938-04-25 1941-10-14 Philips Nv Distortion correction for cathode ray tubes
US2259233A (en) * 1938-08-08 1941-10-14 Cinema Television Ltd Cathode ray deflecting apparatus
US2255039A (en) * 1938-11-24 1941-09-09 Fernseh Ag Cathode ray deflecting device
US2264567A (en) * 1938-11-24 1941-12-02 Fernseh Ag Deflecting device
US2297407A (en) * 1938-11-24 1942-09-29 Gunther Johannes Magnetic deflecting systems for cathode-ray tubes

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2541446A (en) * 1949-01-04 1951-02-13 Barnet S Trott Image distortion corrector for cathode-ray tubes
US2999185A (en) * 1950-01-09 1961-09-05 Harry R Lubcke Television device
US2591159A (en) * 1950-05-29 1952-04-01 Gilfillan Bros Inc Magnetic means for producing compensations and other effects in a cathode-ray tube
US2675501A (en) * 1950-10-31 1954-04-13 Rca Corp Electron beam focusing system
US2574039A (en) * 1951-02-17 1951-11-06 All Star Products Inc Magnetic centering device for cathode ray tubes
US2861209A (en) * 1953-12-14 1958-11-18 Hazeltine Research Inc Cathode-ray-tube beam-deflection system
US2859365A (en) * 1954-09-14 1958-11-04 Rca Corp Electron beam controlling apparatus
US2972073A (en) * 1955-08-31 1961-02-14 Rca Corp Electron beam controlling apparatus
US2807740A (en) * 1955-10-14 1957-09-24 Hazeltine Research Inc Cathode-ray tube apparatus
US3115544A (en) * 1956-04-25 1963-12-24 Hazeltine Research Inc Color-television receivers and deflection yokes
US2921226A (en) * 1956-05-24 1960-01-12 Philco Corp Apparatus for color purity correction in color television receivers
US2879435A (en) * 1956-08-24 1959-03-24 Du Mont Allen B Lab Inc Cathode-ray tube
US3354337A (en) * 1966-02-28 1967-11-21 Zenith Radio Corp Convergence magnet pole shoes
US5023509A (en) * 1989-10-27 1991-06-11 Rca Licensing Corp. Color CRT-yoke combination having conforming corrective magnetic field means attached to the CRT
US6586870B1 (en) * 1999-04-30 2003-07-01 Sarnoff Corporation Space-saving cathode ray tube employing magnetically amplified deflection
US6674230B1 (en) * 1999-04-30 2004-01-06 Sarnoff Corporation Asymmetric space-saving cathode ray tube with magnetically deflected electron beam

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