EP0341337A1 - Statische Konvergenzvorrichtung - Google Patents

Statische Konvergenzvorrichtung Download PDF

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Publication number
EP0341337A1
EP0341337A1 EP88107765A EP88107765A EP0341337A1 EP 0341337 A1 EP0341337 A1 EP 0341337A1 EP 88107765 A EP88107765 A EP 88107765A EP 88107765 A EP88107765 A EP 88107765A EP 0341337 A1 EP0341337 A1 EP 0341337A1
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EP
European Patent Office
Prior art keywords
neck
ray tube
cathode ray
mounting means
magnetic
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.)
Withdrawn
Application number
EP88107765A
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English (en)
French (fr)
Inventor
Roddy Belica
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Individual
Original Assignee
Individual
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Filing date
Publication date
Priority to US06/795,280 priority Critical patent/US4766343A/en
Application filed by Individual filed Critical Individual
Priority to EP88107765A priority patent/EP0341337A1/de
Publication of EP0341337A1 publication Critical patent/EP0341337A1/de
Withdrawn legal-status Critical Current

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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
    • H01J29/46—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
    • H01J29/702—Convergence correction arrangements therefor
    • H01J29/703—Static convergence systems

Definitions

  • This invention relates generally to static convergence assemblies for cathode ray tubes (CRTs) and particularly to a static convergence assembly wherein a pluralty of magnetic elements are maintained in fixed angular orientation relative to one another and are independently adjustable with regard to distance from, and orientation with respect to, the neck of a CRT.
  • CTRs cathode ray tubes
  • color images are produced on the screen of a CRT through the combined use of three independent electron beams and an array of red, green and blue phosphor dots on the screen surface.
  • Color images of various hues are produced through controlled independent illumination of the primary color phosphor dots.
  • color CRTs include a shadow mask which functions to assure that individual phosphor dots will be illuminated only by those electrons which arrive from a particular direction. Since the paths of the three electron beams generated within the tube are different from one another, the CRT, when properly constructed and adjusted, can be operated such that each beam illuminates only those phosphor dots of a particular color. When each of the beams is modulated with appropriate information, a wide spectrum of perceived colors can be displayed.
  • color CRTs are typically provided with three electron guns arranged in either a straight "in-line” or triangular "delta” pattern. Regardless of the pattern employed, proper operation of the CRT results when the three electron beams are made to converge toward a single point on the shadow mask. To provide such convergence, a variety of devices have been developed which seek to provide independant control of the static position of each electron beam.
  • a static convergency assembly for use with cathode ray tubes (CRTs) of the type having an elongate neck of generally circular cross-section includes a magnet for developing a magnetic field.
  • the magnet includes a pair of spaced magnetic poles between which a pole axis is defined.
  • a mount is provided for positioning the magnet adjacent the neck of the CRT such that the pole axis is oriented generally perpendicularly to a selected radius extending radially therefrom.
  • the mounting is such that the magnet is rotatable around the selected radius and is adjustably positionable therealong. When so mounted, the strength and orientation of the magnetic field developed within the CRT neck by the magnet, can be adjusted.
  • CRT 12 includes a hollow glass envelope 13 which tapers from a generally planar viewing screen 14 toward neck 11. Color images are formed on viewing screen 14 by means of three electron beams which are generated by an electron gun assembly 15 ( Figure 3) located within neck 11.
  • a deflection yoke 16 encircles a portion of the CRT neck and functions, in known manner, to magnetically deflect the electron beams horizontally and vertically across viewing screen 14 to produce a display raster.
  • Red, green and blue phosphor dots are distributed over the interior surface of the viewing screen, and a shadow mask (not shown), positioned adjacent the phosphor coating, functions to assure that individual phosphor dots are illuminated by only one of the three electron beams generated by electron gun 15. Proper color balance in the displayed image is achieved when phosphor dots of a particular hue are illuminated by only one of the three electron beams. This is achieved when the three beams converge such that each strikes the shadow mask at the same point at all times during the raster scan.
  • Static convergence assembly 10 functions to magnetically deflect each electron beam such that the desired convergence is obtained.
  • CRT neck 11 is of generally circular hollow cross-section.
  • Electron gun assembly 15 includes three individual electron guns 17, 18 and 19 which are arranged in a triangular or "delta" pattern and which generate the electron beams for illuminating the blue, green and red phosphor dots respectively.
  • a plurality of accelerating electrodes 20 and 21 are positioned immediately ahead of electron gun assembly 15 and function to shape and modulate each of the electron beams with appropriate video information.
  • Static convergence assembly 10 is positioned on CRT neck 11 between electron gun assembly 15 and viewing screen 14 as shown.
  • Static convergence assembly 10 is preferably molded of an electrically insulating, nonmagnetic, semi-flexible material, such as nylon, and includes a collar portion 22 adapted to encircle a portion of the generally circular exterior of neck 11. Collar 22 extends substantially fully around the neck and terminates in a pair of outwardly extending, substantially parallel, spaced flanges 23 and 24 through which a threaded fastener, such as sheet metal screw 25, extends.
  • the threaded shank 26 of screw 25 extends through a first aperture in flange 24 and engages a second aperture formed in flange 23.
  • the first aperture is somewhat larger than the second such that only flange 23 threadedly engages shank 26.
  • Static convergence assembly 10 further includes a plurality of extension arms which extend radially outwardly from collar 22.
  • three extension arms 27, 28 and 29 are provided at equal 120° spacing from one another as shown in Figures 1 and 2.
  • each of the extension arms is generally rectangular in shape and cross-section, and is integrally formed with collar 22.
  • Static convergence assembly 10 further includes a plurality of elongate stems 30, 31 and 32 extending along extension arms 27, 28 and 29 in generally parallel alignment therewith. As illustrated, each of the stems is of generally circular cross-section and is longer than the extension arm along which it is positioned. Preferably, the stems are formed of the same material as the collar.
  • each stem Adjacent the outermost end of each extension arm, a generally cube-shaped block 33, 34 and 35 is formed.
  • a circular passage 36 is formed through each block and extends in a direction parallel to, and spaced from, the longitudinal axis of the associated extension arm.
  • a channel 37 is formed through the side face of each block such that the block is of somewhat U-shaped cross-section as illustrated in Figure 4. The dimensions of bore 36 and channel 37 are such that stems 30-32 are snugly received in their respective blocks with the result that each can be moved to, and retained in, a selected rotational and longitudinal position relative to its adjacent extension arm. As shown, for example, by the arrow and phantom view of stem 32 in Figure 2, each stem is longitudinally displaceable over a range along its associated extension arm.
  • each stem 30-32 is provided with a magnetic field producing element such as permanent magnets 38, 39 and 40.
  • Each magnet is of generally cylindrical form and has length substantially equal to the diameter of the stem on which it is mounted.
  • a pair of magnetic poles are formed at opposite ends of each magnet and a pole axis 38a, 39a and 40a is defined between each pole pair.
  • Each magnet is mounted such that its pole axis is oriented perpendicularly to the longitudinal axis of its associated stem, and is received in a circular recess 41, 42 or 43 formed therethrough.
  • a bevelled channel 44, 45 and 46 is formed in the end of each stem and extends into the adjacent recess as illustrated to allow each permanent magnet to be pressed through the end of the stem and into its recess.
  • the bevelled shape of the channels 44-46 permits the magnets to be installed at the time of manufacture through the simple expedient of pressing the stems downwardly onto the magnets such that each magnet is forced into its respective recess.
  • the ends of each stem preferably extend slightly beyond the magnets and are shaped to conform to the external shape of CRT neck 11.
  • static convergence assembly 10 is positioned on CRT neck 11 such that each of the extension arms extends along a radius defined by the central axis 47 of the neck and one of the electron guns 17-19. Screw 25 is then tightened to lock the assembly in the desired position.
  • the rotational and longitudinal position of each stem 30-32 is adjusted by displacing the stems along the directions shown by the arrows in Figures 2 and 5. This has the effect of altering the strength and orientation of the magnetic fields developed within CRT neck 11 by each of the permanent magnets with the further effect that the paths of the electron beams developed by electron guns 17-19 are varied. Because each permanent magnet is substantially closer to one of the three electron beams than to the others, adjustment of a single stem will primarily influence the position of the nearest beam.
  • static convergence assembly 10 provides substantially independent adjustment of each of the three electron beams and thereby simplifies the convergence adjustment.
  • the length of each stem is such that a convenient handle portion 48-50 projects beyond the ends of the extension arms even when each stem is pressed fully toward CRT neck 11.
  • FIG. 6 illustrates the static convergence assembly adapted for use with CRTs having an "in-line" electron gun configuration.
  • the electron guns 17, 18 and 19 of such a CRT are arranged in linear fashion along a diameter of CRT neck 11.
  • the static convergence assembly includes a collar 51 having a pair of extension arms 52 and 53 extending radially outwardly therefrom at 180° spacing from one another. Collar 51 and extension arms 52 and 53 are similar in construction to their counterparts in the "delta" configuration embodiment shown in Figure 2.
  • a pair of stems 54 and 55 are mounted along arms 52 and 53 in the manner previously described and carry permanent magnets 56 and 57 at their ends adjacent CRT neck 11.
  • collar 51 is positioned such that arms 52 and 53 are aligned with the electron guns 17-19 as shown.
  • permanent magnets 56 and 57 function to magnetically deflect the electron beams, formed by electron guns 17 and 19 respectively, toward the beam developed by the center electron gun 18. In most cases, the adjustment available with the assembly shown in Figure 6 will be sufficient to achieve satisfactory beam convergence.
  • a third extension arm 58 is provided opposite screw 25 and at an equal 90° circumferential spacing from arms 52 and 53.
  • a stem 59 which can be identical with the other stems shown and described, extends along extension arm 58 and carries a permanent magnet 60 at its end nearest CRT neck 11.
  • the field produced by magnet 60 primarily influences the vertical position of the beam developed by electron gun 18 and permits exact convergence to be achieved in the event of slight miss alignment of the electron guns.
  • the construction of the assembly illustrated in Figure 7 is all other respects similar to that shown in Figure 2.
  • Figures 8, 9 and 10 show the magnet field orientations which result when one of the stems (e.g. stem 30) is rotated.
  • the pole axis 38a of permanent magnet 38 is parallel to the axis 47 of CRT neck 11. Accordingly, the lines of force 61 of the field produced by the magnet are substantially parallel to the path traveled by the electrons in each of the electron beams. It is a well known physical property that movement of a charged particle in a direction parallel to the field lines of a static magnetic field will have no effect on the movement of the particle. Accordingly, when the magnet is positioned as shown in Figure 8, the field it develops will have little or no effect on the position of the beam on the CRT viewing screen.
  • the magnet is positioned such that its pole axis 38a is oriented perpendicularly to the axis 47 of the CRT neck.
  • the magnetic field lines will be substantially perpendicular to the path of the beam electrons and, accordingly, each electron will experience a substantially vertically oriented force as it passes through the magnetic field. This has the effect of deflecting the electron beam either up or down on the viewing screen depending on the particular orientation of the magnet. Rotation of the magnet through 180° will reverse the direction of beam deflection.
  • the pole axis 38a of the permanent magnet is oriented at an angle with respect to the axis of the CRT neck, and, thus, the magnetic field produced within the neck will include parallel and perpendicular components. Beam deflection will depend primarily on the strength of the perpendicular field component and will be substantially unaffected by the parallel components. The angular position of the permanent magnet with respect to the neck axis determines the relative strength of the perpendicular field component and thus affects the degree to which the beam is deflected. Accordingly, the degree of beam deflection can be varied through rotation of the appropriate stem.

Landscapes

  • Video Image Reproduction Devices For Color Tv Systems (AREA)
EP88107765A 1985-11-05 1988-05-13 Statische Konvergenzvorrichtung Withdrawn EP0341337A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US06/795,280 US4766343A (en) 1985-11-05 1985-11-05 Static convergence assembly
EP88107765A EP0341337A1 (de) 1988-05-13 1988-05-13 Statische Konvergenzvorrichtung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP88107765A EP0341337A1 (de) 1988-05-13 1988-05-13 Statische Konvergenzvorrichtung

Publications (1)

Publication Number Publication Date
EP0341337A1 true EP0341337A1 (de) 1989-11-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP88107765A Withdrawn EP0341337A1 (de) 1985-11-05 1988-05-13 Statische Konvergenzvorrichtung

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EP (1) EP0341337A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4205146A1 (de) * 1992-02-20 1993-08-26 Thomson Brandt Gmbh Ablenkeinheit fuer die bildroehre in einem fernsehempfaenger
US5600212A (en) * 1992-02-20 1997-02-04 Deutsche Thomson-Brandt Gmbh Deflection circuit for a television receiver using symmetrical deflection

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2717323A (en) * 1954-03-23 1955-09-06 Rca Corp Electron beam centering apparatus
US3138730A (en) * 1960-05-19 1964-06-23 Zenith Radio Corp Convergence device for color television
USRE27417E (en) * 1967-12-11 1972-07-04 Susumu egawa
US4232283A (en) * 1979-03-27 1980-11-04 Rca Corporation Electron beam moving apparatus for a color cathode ray tube

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2717323A (en) * 1954-03-23 1955-09-06 Rca Corp Electron beam centering apparatus
US3138730A (en) * 1960-05-19 1964-06-23 Zenith Radio Corp Convergence device for color television
USRE27417E (en) * 1967-12-11 1972-07-04 Susumu egawa
US4232283A (en) * 1979-03-27 1980-11-04 Rca Corporation Electron beam moving apparatus for a color cathode ray tube

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4205146A1 (de) * 1992-02-20 1993-08-26 Thomson Brandt Gmbh Ablenkeinheit fuer die bildroehre in einem fernsehempfaenger
US5600212A (en) * 1992-02-20 1997-02-04 Deutsche Thomson-Brandt Gmbh Deflection circuit for a television receiver using symmetrical deflection

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