US3873877A - Mislanding corrector for color cathode ray tubes - Google Patents

Mislanding corrector for color cathode ray tubes Download PDF

Info

Publication number
US3873877A
US3873877A US417591A US41759173A US3873877A US 3873877 A US3873877 A US 3873877A US 417591 A US417591 A US 417591A US 41759173 A US41759173 A US 41759173A US 3873877 A US3873877 A US 3873877A
Authority
US
United States
Prior art keywords
magnetic
magnetic flux
temperature
strap means
strap
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US417591A
Other languages
English (en)
Inventor
Hiromasa Machida
Hiroshi Ichigaya
Kietsu Iwabuchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sony Corp
Original Assignee
Sony Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sony Corp filed Critical Sony Corp
Application granted granted Critical
Publication of US3873877A publication Critical patent/US3873877A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/006—Arrangements for eliminating unwanted temperature effects
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/701—Systems for correcting deviation or convergence of a plurality of beams by means of magnetic fields at least

Definitions

  • a temperature-responsive magnetic device comprising a pair of permanent magnet elements, each partly enclosed in a separate magnetic element that has temperature-responsive variable permeability, is provided for attachment to the wall of a color cathode ray tube to compensate for beam mislanding on the color phosphor screen caused by thermal expansion of'a beam selecting mask in the tube. The avoidance of mislanding is necessary to maintain fine color purity of color television images produced by the tube.
  • This invention relates generally to means for avoiding beam mislanding in a color cathode ray tube having a beam-separating structure and a color phosphor screen, and more particularly to means of compensating for such mislanding caused by temperature variations in the beam-separating structure of the color cathode ray tube.
  • a beamseparating structure in the form of a mask or grille that has a number of small apertures or slits therethrough to allow the electron beams to reach, or land on, only the phosphor elements that emit light of selected colors.
  • heat is generated by the impingement of the electron beams on the beamseparating structure. This heat causes thermal expansion or distortion of the beam-separating structure with the result that the positions of the slits or apertures are shifted relative to the phosphor elements of the screen.
  • This causes the landing positions of the electron beam on the color phosphor screen to shift, and this mislanding of the electron beams, in turn, causes deteriorations in color purity.
  • the mislanding of the electron beam is worse near the periphery of the screen than at the center and is particularly objectionable in the case of wide angle beam scanning tubes.
  • One conventional system is to hold the mask by a bimetallic support to change the position of the mask in the tube relative to the screen in response to temperature change.
  • Another compensating system uses an auxiliary beam deflection coil in addition to the main deflection coil. The current in the auxiliary beam deflection coil is changed in response to the mask temperature to change the electron beam path in order to avoid the mislanding of the electron beams.
  • an object of this invention is to provide a simplified color cathode ray tube arrangement wherein the magnetic flux to eliminate mislanding of electron beams on the screen of the color cathode ray tube caused by temperature variations in the mask and screen is spread out over a relatively large area by the correcting means located on the funnel portion of the tube.
  • Still another object of this invention is to provide a color cathode ray tube arrangement in which temperatureinduced mislanding of the electron beams in wide angle tubes is prevented by a temperature-responsive permanent magnetic device of simple construction in which the magnetic field is spread over a large area in a controlled manner.
  • a further object of this invention is to provide a simple color-purity'correcting means comprising a pair of temperature-responsive permanent magnetic devices for balanced correction of mislanding.
  • a temperatureresponsive magnetic device in the form of two permanent magnets, such as discs with diametrically opposed north and south poles, each magnet being held by a magnetic shunt the permeability of which changes in response to temperature variation.
  • the shunt-held magnets are joined by a relatively high-permeability member, such as a strap of silicon steel that helps control the flux distribution from the magnets.
  • the resulting two-magnet structure can be attached to the cathode ray tube at a predetermined position between the beam deflection center of the tube and the screen in order to modify the paths of the beams.
  • the extent to which the strap further shunts the fields of the magnets at its ends is a means for controlling the strength of the fields produced by the magnets.
  • FIG. 1 is a plan view of one example of a temperature-responsive magnetic device employed in a color cathode ray tube temperature compensating structure according to the invention.
  • FIG. 2 is a cross-sectional view of the device shown in FIG. 1.
  • FIG. 3 is a side elevational view of a complete temperature-responsive magnetic structure incorporat ing two of the devices shown in FIGS. 1 and 2 according to the invention.
  • FIG. 4 is a plan view of the structure shown in FIG. 3.
  • FIG. 5 is a side elevational view similar to FIG. 3 but illustrating magnetic flux distribution in the vicinity of the structure.
  • FIGS. 6 and 7 illustrate the variation in the magnetic flux field in the vicinity of the magnetic structure as the overlap between the strap and one of the magnetic devices is varied.
  • FIGS. 8 and 9 show side and rear views of a color cathode ray tube with two magnetic structures according to the invention attached to the funnel portion to correct for beam mislanding.
  • FIGS. 1 and 2 show one embodiment of a temperature-responsive magnetic device 11 used in the magnetic structure of this invention.
  • the device 11 includes a permanent magnet 12 held in a recess in a shunt 13 made of temperature-responsive magnetic material.
  • the permanent magnet 12 may be made of, for example, Ba-ferrite containing BaCO; and Fe O in the ratio of 15:85 by mol% and may be formed as a disc magnetized along its diameter at the pole locations marked N and S.
  • the disc is formed so that its physical shape can be used to indicate the locations of thepoles N and S.
  • the disc 12' has one flat section 14 along its edge, and the magnetizing of the disc is always carried out so that the poles N and S have a certain relationship to this edge.
  • the shunt 13 is also provided with flat edge 16 for the same reason.
  • the temperature-responsive magnetic material of the shunt 13 may be made of MnZn-ferrite and formed as a disc having a recess.
  • the shunt 13 has a magnetic permeability that decreases as the temperature increases.
  • An example of a suitable material for the shunt 13 is a Mn'Zn-ferrite composed on Fe O MnCO and ZnO combined in the ratio of 50:27:23 by mol%. In this case, when the permanent magnet 12 is fitted to the recess in the temperature-responsive shunt 13, one side of the permanent magnet 12 and its periphery are covered with the magnetic material of the shunt 13.
  • the permeability of the magnetic material of the shunt 13 is high when temperature is low, the magnetic flux that originates in the permanent magnet 12 is almost completely shunted by the magnetic material of the shunt 13, with the result that the magnetic flux density of the external magnetic field of the magnetic device 11 is low.
  • the permeability of the magnetic material of the shunt 13 is reduced, with the result that the magnetic flux density of the external magnetic field produced by the magnetic device 11 becomes high due to the fact that the magnetic flux from the magnet 12 is less shunted by the magnetic material of the shunt 13. Accordingly, it will be understood that the flux density of the external magnetic field from the magnetic device 11 increases as the temperature increases.
  • the permanent magnet 12 and the temperature-responsive shunt 13 used in the device 11 be limited to the configurations mentioned above. They can be formed, for example, with rectangular perimeters with one side of the permanent magnet and its rectangular perimeter covered by the magnetic material. Other polygonal forms may also be used.
  • the magnetic structure 17 uses two magnetic devices 11a and 11b attached to opposite ends of a strap, or bridge, of material having relatively high magnetic permeability, for example, or silicon steel a nickel-iron alloy known as Pe'rmalloy.
  • the magnetic devices 11a and 11b are attached so that they extend beyond the ends of the strap 18 and have their respective magnets facing away from the strap.
  • the flat sides 16a and 16b are, as shown in FIG. 4, aligned with each other so that the north and south poles N and S of both of the devices 11a and 11b are also aligned.
  • the right-hand end of the strap 18 as shown in FIG. 4 is polarized to have a north magnetic pole and the lefthand end of the strap 18 is polarized to have a south magnetic pole.
  • the magnetic flux within the strap 18 is thus additive rather than in bucking arrangement.
  • FIG. shows a magnetic flux field 19 representative of the structure 17.
  • the central part of the field lines 19 between the two magnetic devices 11a and 11b is pulled inwardly toward the strap 18, whereas the flux at the ends extends outwardly. It has been further controlled by varying the amount of overlap of the relatively high permeability strap 18 with respect to the magnetic devices 11a and 11b.
  • FIGS. 6 and 7 show two different overlapping amounts. In FIG. 6, the strap 18 overlaps relatively little of the magnetic device 11a, whereas in FIG. 7 the strap 18 overlaps a substantial part of the magnetic device 11a. The area, or portion, of the magnetic device 11a that is not overlapped by the strap 18, is indicated by the dimension W. In F IG. 6 where the overlap is relatively small, the length w is relatively large. The reverse is true in the structure shown in FIG. 7.
  • the permeability of the strap 18 is relatively high, the greater the overlap, that is the smaller dimension W, the more of the flux flows internally through the strap 18 and the less there is to form the field indicated in FIG. 6 by the lines 19a and in FIG. 7 by the lines 19b.
  • Controlling the dimension W provides a very useful way of controlling the intensity of the magnetic field used to prevent mislanding, since the intensity of the field can be varied while keeping the temperatureresponsive devices 11a and 11b in firm, heatconductive relationship with the wall of the cathode ray tube that is to be controlled.
  • FIGS. 8 and 9 show, respectively, side elevational and rear elevational views of a cathode ray tube in which temperature-responsive magnetic structures of the type shown in FIGS. 3-7 are used.
  • a beamseparating structure in the form of an aperture mask or a grille of a standard type (not shown).
  • a deflection yoke 24 is positioned on the neck 22 adjacent the funnel of the tube 21 to deflect electrons from electron gun means (not shown) within the neck to trace out a suitable raster on the face 23.
  • FIGS. 8 and 9 A typical position for the temperatureresponsive magnetic structures 17 and 170 on the funnel of the tube 21 is shown in FIGS. 8 and 9.
  • the structures 17 and 17a are affixed to the funnel to be responsive to heat generated by electrons striking the internal beamseparating structure. Increasing the heat increases the amount of flux external to the structures 17 and 17A. This external flux is the flux that affects the trajectories of the electron beams within the tube to direct them at the appropriate points to produce correct landing of the electrons on the face 23.
  • the tube 21 is constructed as a symmetrical device, it is advantageous that the structures 17 and 17a be arranged so that each of them has two magnetic devices. These are the devices lla and 11b in the case of the magnetic structure 17 and the devices 110 and 11d in the case of the magnetic structure 17a.
  • the temperature-responsive magnetic devices Ila-11d are located farthest from the axis of the neck 22 and are in the correct positions to provide the most intense magnetic field at the corners of the screen 23.
  • the magnetic structures 17 and 17a are designed so that they do not adversely affect the trajectories of the found that this field configuration is particularly useful electron beams when the tube 21 is cold. As the tube heats up, the shunting effect of the temperatureresponsive shunt 13 of each magnetic device 11 is reduced automatically, thereby allowing more flux to extend into the tube 21 and produce greater effect on the beam trajectories, thereby compensating for the mislanding due to differential thermal expansion of the beam-separating structure and the color phosphor elements on the screen 23.
  • an arrangement for correcting temperature induced mislanding of said electron beams in respect to said respective color phosphors comprising elongated strap means of relatively high magnetic permeability, and temperature-responsive magnetic flux generating means attached to the opposite ends of said strap means and being effective to produce magnetic fields which vary in intensity with varying temperature and which are spread by said strap means, said strap means and magnetic flux generating means being disposed against said envelope of the cathode ray tube so that said magnetic flux generating means are influenced by the temperature of said tube and said magnetic fields act within the latter on said electron beams for correcting said temperature induced mislanding thereof.
  • said strap means includes two straps of said relatively high magnetic permeability and each having said magnetic flux generating means attached to said opposite ends-thereof, said envelope has a funnel-shaped portion leading to said screen, and said two straps and the respective magnetic flux generating means are disposed on said funnel-shaped portion at opposite sides of the center of the tube with said straps extending substantially normal to the line scanning direction of said beams.
  • each of said magnetic flux generating means includes a permanent magnet having north and south poles disposed at opposed portions thereof, and a shunt member attached to the respective end of said strap means and in which said permanent magnet is mounted so that the permanent magnets of said magnetic flux generating means at the opposite ends of said strap means have their north and south poles, respectively, directed toward each other; and in which each said shunt member is of a material having its magnetic permeability varied with changes in temperature.
  • each said permanent magnet has a non-circular periphery to which the locations of said north and south poles have a predetermined relationship
  • each said shunt member has a recess shaped to receive the respective permanent magnet and to ensure the proper positional relationship of said poles of the magnets in said magnetic flux generating means at the opposite ends of said strap means.

Landscapes

  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US417591A 1972-11-20 1973-11-20 Mislanding corrector for color cathode ray tubes Expired - Lifetime US3873877A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13353372 1972-11-20

Publications (1)

Publication Number Publication Date
US3873877A true US3873877A (en) 1975-03-25

Family

ID=15107015

Family Applications (1)

Application Number Title Priority Date Filing Date
US417591A Expired - Lifetime US3873877A (en) 1972-11-20 1973-11-20 Mislanding corrector for color cathode ray tubes

Country Status (7)

Country Link
US (1) US3873877A (de)
CA (1) CA982207A (de)
DE (1) DE2357895C2 (de)
FR (1) FR2207355B1 (de)
GB (1) GB1414240A (de)
IT (1) IT996490B (de)
NL (1) NL177056C (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4376272A (en) * 1980-11-12 1983-03-08 Hitachi, Ltd. Magnetic field generators for use in electromagnetic focusing type cathode ray tubes
US4673906A (en) * 1986-06-03 1987-06-16 Zenith Electronics Corporation CRT deflection yoke with rigidifying means
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
US5038074A (en) * 1988-07-28 1991-08-06 Mitsubishi Denki Kabushiki Kaisha Shadow-mask color picture tube
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
WO2004042767A2 (en) * 2002-11-04 2004-05-21 Lg. Philips Displays Display device comprising a deflection unit and a deflection unit for a display device
EP1501113A1 (de) * 2002-11-22 2005-01-26 Matsushita Electric Industrial Co., Ltd. Ablenkjoch und kathodenstrahlröhreneinheit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2972073A (en) * 1955-08-31 1961-02-14 Rca Corp Electron beam controlling apparatus
US3296570A (en) * 1963-09-23 1967-01-03 Mitsubishi Electric Corp Device for correcting distortion of deflection in television receiver
US3573525A (en) * 1967-11-21 1971-04-06 Sony Corp Color purity temperature compensation system for a color picture tube

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2941102A (en) * 1956-07-26 1960-06-14 Sol L Reiches Post deflection color purity correcting device for a color tv cathode ray tube and system using the same
DE1810005A1 (de) * 1968-11-20 1970-06-04 Max Baermann Temperaturkompensation an Dauermagneten mit Temperaturkompensationsmaterial

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2972073A (en) * 1955-08-31 1961-02-14 Rca Corp Electron beam controlling apparatus
US3296570A (en) * 1963-09-23 1967-01-03 Mitsubishi Electric Corp Device for correcting distortion of deflection in television receiver
US3573525A (en) * 1967-11-21 1971-04-06 Sony Corp Color purity temperature compensation system for a color picture tube

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4376272A (en) * 1980-11-12 1983-03-08 Hitachi, Ltd. Magnetic field generators for use in electromagnetic focusing type cathode ray tubes
US4673906A (en) * 1986-06-03 1987-06-16 Zenith Electronics Corporation CRT deflection yoke with rigidifying means
US5038074A (en) * 1988-07-28 1991-08-06 Mitsubishi Denki Kabushiki Kaisha Shadow-mask color picture tube
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
WO2004042767A2 (en) * 2002-11-04 2004-05-21 Lg. Philips Displays Display device comprising a deflection unit and a deflection unit for a display device
WO2004042767A3 (en) * 2002-11-04 2004-07-15 Lg Philips Displays Display device comprising a deflection unit and a deflection unit for a display device
US20060273708A1 (en) * 2002-11-04 2006-12-07 L.G. Philips Displays Display device comprising a deflection unit and a deflection unit for a display device
EP1501113A1 (de) * 2002-11-22 2005-01-26 Matsushita Electric Industrial Co., Ltd. Ablenkjoch und kathodenstrahlröhreneinheit
EP1501113A4 (de) * 2002-11-22 2008-07-16 Matsushita Electric Ind Co Ltd Ablenkjoch und kathodenstrahlröhreneinheit

Also Published As

Publication number Publication date
FR2207355B1 (de) 1978-11-17
IT996490B (it) 1975-12-10
DE2357895A1 (de) 1974-05-30
NL177056B (nl) 1985-02-18
GB1414240A (en) 1975-11-19
NL7315890A (de) 1974-05-22
DE2357895C2 (de) 1982-11-04
CA982207A (en) 1976-01-20
NL177056C (nl) 1985-07-16
FR2207355A1 (de) 1974-06-14

Similar Documents

Publication Publication Date Title
CA1124308A (en) Deflection yoke with permanent magnet raster correction
EP0456942B1 (de) Ablenkjoch mit überlappenden Ablenkspulen
US2752520A (en) Tri-color kinescope
US4386331A (en) Deflection yoke
PL123926B1 (en) Deflecting yoke
US3873877A (en) Mislanding corrector for color cathode ray tubes
US2769110A (en) Electron beam control means
US3573525A (en) Color purity temperature compensation system for a color picture tube
US3290532A (en) Conjointly-movable, plural magnet means for blue lateral correction in color kinescopes
US2816244A (en) Electron beam controlling apparatus
US2923844A (en) Cathode ray tube structure including convergence system
US3701065A (en) Color picture tube beam convergence apparatus
US3899710A (en) Color cathode ray tube with temperature-responsive color purity magnets
US4940920A (en) Device to shield mask cathode tubes from the earth's magnetic field
US4782264A (en) Color picture device including convergence correcting magnetic plates
PL118815B1 (en) Method for correction of colour purity
US3098942A (en) Magnetic centering device for cathode ray tubes
US2790920A (en) Apparatus for control of electron beam cross section
US4316119A (en) Tilted unitary degaussing coil arrangement
US4274031A (en) Color tube having shield correcting for terrestrial magnetism
KR910010100B1 (ko) 컬러음극선관
US2859365A (en) Electron beam controlling apparatus
US2880339A (en) Device for cathode ray tube
US5196761A (en) Color cathode-ray tube
US3409791A (en) Color tube convergence system deflecting beam in two directions with single magnet