FR2570910A1 - MAGNETIC CORRECTION DEVICE WITH GEOMETRY CORRECTION FOR A TRICHROME TUBE WITH THREE RODS ONLINE - Google Patents

Abstract

GEOMETRY CORRECTION SUITABLE FOR COLOR TELEVISION TUBES. THE CORRECTION MEANS INCLUDES TWO MAGNETIC CORES 34, 35 SYMETRICALLY ARRANGED AND CARRYING COILS 37, 38 BROUGHT BY CURRENTS LINKED TO LINE OR FRAME DEVIATION CURRENTS DEPENDING ON WHETHER THE CORRECTION IS CARRIED OUT ON THE LINE OR WEFT.

Description

JUL.BOU

  MAGNETIC DEVIATOR WITH GEOMETRY CORRECTION

  INTENDED FOR A TRICHROME TUBE WITH THREE GUNS ONLINE

  The present invention relates to a geometrically corrected magnetic deflector for a trichromatic three-barreled tube

online.

  The present invention finds application mainly in the field of color television of large diffusion. In the field of consumer electronics, cost issues need to be considered together with accuracy issues. However, magnetic deflectors are electronic optics systems that need to be corrected

particular defects.

  In the prior art, for deflection angles of up to 900, it has been possible to produce deflectors causing the formation of images having a good convergence correction over the entire surface of the screen as well as a good correction. geometry in both North / South and East / West. For this, it is necessary to realize a deviator in several distinct zones: a first zone controls the section of each of the electron beams, the second zone corrects the

  red-blue deconvergences, the third zone corrects the geometry.

  The present invention relates to an improvement of

  devices of the prior art, allowing the realization of a deviation

  multi-zone converter, this invention makes possible the realization of deflectors correcting the geometry and convergence for an angle of

deflection of 1100.

  In the prior art, such devices may include magnetic field shapers that reduce a fraction of one of the fields to a region suitable for correction. Their

  geometry must be precisely established.

  The present invention proposes a solution that avoids the capture

  main field by directly forming the auxiliary field.

  Indeed, the present invention relates to a magnetic deflector

  geometric correction tick for a three-color trichromatic tube

cannons online.

  The invention resides in that a set of auxiliary coils is arranged in front of the deflector and fed through a means of

  connection so as to generate a cushioning field.

  geometry. Other advantages and features of the present invention

  will be better understood using the description and figures

  attached which are: - Figure I a deflector equipped according to the invention

  FIGS. 2 and 3 of the field line diagrams for correcting

  geometry; FIG. 4 is a diagram of the first overtones of fields corrected or not; FIGS. 5 and 6 show the distribution of the second harmonic of the generated field in the deflector and the shapes of the vertical deflection fields in three zones of the deflector;

  - Figures 7 to 9 of the diagrams of deviators provided with the correct

according to the invention.

  A deflector for a color television tube is a body of revolution of central axis aligned substantially on the axis of the cathode ray tube. The deflector is mounted on the neck of the tube in the enlarged part thereof. Regardless of the deviator position settings and the reel settings it contains, the diverter allows for three main types of corrections: a correction on the electron beam passing through it, an astigmatism correction in the middle and a geometry correction

on the front.

  In Figure I is shown the diagram of the section of a

  half-view of a deviator, in relation to its plane of symmetry

  The deflector comprises a separator 1 consisting of an insulating casing which supports on the one hand a line winding 4, for example of the "horse saddle" type referenced 2 in the drawing, and a toroidal winding mounted on ferrite 3. We have

  schematically represented the three areas of successive correction

  sives brought by the deflector along the path of an electron. In zone A corrections are made to the incident electron beam. These corrections improve the geometry of the spot on

  the screen itself arranged in front of the deviator.

  In zone B the correction of convergence of the

  outer bundles red and blue.

  In region C, the geometry correction is carried out, which limits the deformations of the North-South and East-West cushion image.

on the screen.

  The additional turns 5 are connected in series with the weft winding 4. This is done with a sizing

  suitable a good geometry correction in frame. The bala-

  Weage yage is therefore applied to the terminals 7 and 9 and the two weft coils are connected together by the wire 8. It goes without saying that a iS5 main winding comprises two symmetrical main coils connected in series. This association implies that the correction means according to the invention comprises a set of two auxiliary coils. It is known that in a plane perpendicular to the central axis of the

  deviator, each field H can decompose according to a development

of the form:

-2 4

H = H0 + H2Y + H4Y + ...

  The same development according to X is possible, where X and Y are two orthogonal axes, X in the direction of the line scan and Y in the direction of the frame scan. Such a development includes only even-order terms. When the coefficient H2 is positive, we say that the field is in a cushion. If H2 is negative, the field is in barrel. In the prior art the construction of such a deviator leads to a trilemma problem. The invention makes it possible

besides reducing this problem.

  The trilemma is a function of three parameters: - convergence "three hours - nine hours" C 3/9, - convergence "six hours - twelve hours" C 6/12,

  - horizontal trapezoid red-blue Trh.

  The trilemma measures a residual fault related to the profile of the line and frame coils. The trilemma T is defined by the relation:

T = C 3/9 + Trh - C 6/12.

  In FIG. 4, it can be seen that an additional coil placed in front of the frame contributes to an expansion of the weft field forward and thus to a displacement of the center of frame deviation T1 in a new center center-leading center T2. L line deviation. This

  helps reduce the positive trilemma.

  Figures 5 and 6 show the form of the function, H2 = H2 (z) distribution of the second harmonic of a vertical deflection field along the deflector. There are three zones: weakly positive in zone A, the H2 component is negative in zone B and then positive in zone C. In zone A, the

  deflector makes a correction on the section of the

  from canons. In zone B, the deviator performs a red-blue convergence correction of the image and in zone C

a geometry correction.

  However, the positive H2 field gave a good correction of

  geometry. As the negative H2 field ensures a good correction

  A solution would be to conform the coils so that the ampere-turns harmonics provide a second field harmonic that varies along z in the manner recalled above. But if the value H2p and the value H2n are too far apart, it is impossible to construct a sufficiently variable winding along this axis, especially for a toroidal winding. It is necessary to add a magnetic element capable of raising the value H2p in the zone C. It is known to use field shapers equipped with arms which conform the field lines captured in the active zone in a suitable manner. But this gehre of solution has the disadvantage of forming excrescences that interfere with the mechanical assembly of the deflator on the tube. In addition, it is necessary to size the shapers in a fixed manner, which can not be adjusted. Such a setting does not fit along the z axis. The field ramemé is limited in intensity which limits all the dynamics of correction. Finally, these conformers can not be used to capture

of the line field.

  The invention makes it possible to overcome these disadvantages. In Figure 7, there is shown from its front, a deflector. The deflector comprises a substantially conical portion represented by its small circle 31 and its large circle 30. The small circle 31 is adapted to the diameter of the neck of the television tube and the large circle 30 to the flared portion of the tube which connects itself to the glass slab closing the tube and constituting its luminescent screen. The x and y axes are shown respectively horizontal and vertical. The deflector carries the line and weft windings. The not shown line winding is composed of two saddle-shaped electric masses. The deflector, in the embodiment shown here, also comprises an annular portion 45 in the plane (x, y) perpendicular to the deflection axis. This annular portion 45 carries the correction means according to the invention. This one is constituted in

  two parts 34 and 35 arranged symmetrically to the horizontal axis x.

  In addition, each portion 34 and 35 is symmetrical with respect to the vertical axis y. This portion 34 is identical to the portion 35. It consists of a magnetic core. Each core is here composed of four sectors 36 to 39. The extreme sector 36 has an angular opening of amplitude b and the middle sector 37 an angular opening of amplitude a. In a preferred embodiment, take a = b = 30. The sectors 38 and 39 are respectively symmetrical to them by each median sector 37 and 38. The core is reeled

  magnetic so as to constitute a 40 or 41 worn spool.

  These bobbins 40 and 41 are symmetrical with respect to the vertical axis y. They therefore have the same number of turns of wire of the same diameter and have the same shape. They allow to create a

  symmetric field in the four quadrans of the plane (x, y).

  In the exemplary embodiment, each portion 34 or 35 is made in two groups of sectors. Each group has a median sector carrying a spool and an end sector. They can be glued on the annular part 45 or inserted on this

part 45.

  Each spool 37 is electrically connected in series with the winding 38 associated on the same element 34 corrector. Both coils are wound in the same electrical direction. On the two elements of the corrector the groups of coils are wound in opposite directions from each other. They are connected by one of their ends by a wire 44. The other two ends 43a and 43b are connected to a connection means 42. In a first example of embodiment illustrated in Figure 1, the connector is a single wire 8 which allows the series assembly of the weft and auxiliary weft coils. In a second exemplary embodiment, the frame and auxiliary frame coils are connected in parallel. Other means of connection are envisaged which lead to an improvement of the quality

deviator.

  The end sectors such as sectors 36 and 39 are shaped so as to provide a cushioned field (with positive H2 harmonic) which locally adds to the field field in the

zone C at the front of the deflector.

  In another embodiment, one works in the saturation zone of the magnetic cores of the corrector so as to

  take advantage of the nonlinear responses of the induced field.

  In another embodiment, an additive correction is performed by extending each magnetic core 34 or 35 to

  forward or backward by tabs made of magnetic materials.

  In another embodiment, the correction means is disposed on the conical part of the deflector in the space between the

line and frame windings.

  In Figure 8, there is shown a color television tube which has a screen 50, a flared portion 51 and a neck 58. The neck 58 supports a connecting cap 57 and a deflector 52, consisting of a separator 54 and of winding line and frame as the winding 55. At a predetermined distance depending on the shape of the correction on the second harmonic H2 of the field there is a

-7O910

  ring 56 integral or not of the deflector itself. This ring 56 carries the corrector according to the invention in one of the forms described above. The correction according to the invention has been described on the field field. It is also useful as a line field corrector by taking a suitable current source and arranging auxiliary coils turned of 90 relatively to the layout.

described here.

  In Figure 9, there is shown a half-ferrite 70 during 0 winding. It consists of a hollow conical body classically obtained. On the enlarged part, there is an insulation spacer 71 and a magnetic core 72. It is thus possible to perform in a single operation the weft and correction coils.

  frame, the coil package 74 sufficient to magnetize the core 72.

  1 Another half ferrite is wound symmetrically and all

  reconstituted according to the state of the art.

  In another embodiment, the half ferrite is wound in a first pass. Then the magnetic core 72 is added thereto. A second pass is then made so as to produce turns which leave the ends of the core free.

  as described for the assembly of FIG. 7.

Claims (11)

  A geometrically corrected magnetic deflector for a trichromatic three-barrel in-line tube, characterized in that a set of auxiliary coils (34, 35) is disposed in front of the deflector and fed through a connecting means (42). ) so as to generate a geometry correction pad field. 2. Deflector according to claim 1, characterized in that each coil (34, 35) comprises a magnetic core (36-39) on   which is mounted a winding (40, 41).   3. Diverter according to claim 2, characterized in that each magnetic core is made in two symmetrical parts (36, 37 and 38, 39).   4. Deflector according to claim 3, characterized in that the two symmetrical parts are initially separated and each carry a winder (40 or 41), the two windings being of same characteristics.   5. Deflector according to claim 1, characterized in that the connecting means is a wire (8) which connects in series a first main coil (4) generating the field to be corrected to a second   auxiliary coil (5) generating the correction field.   6. Diverter according to claim 1, characterized in that the connecting means (42) is in parallel with a first main coil (4) generating the field to be corrected to a second coil   auxiliary device (5) generating the correction field.   7. Deflector according to claim 1, characterized in that the auxiliary coils are carried by a ring (56) in front of the deflector (52).   8. Diverter according to claim 7, characterized in that the   ring (56) is mechanically free from the deflector (52).   9. Diverter according to claim 1 for the raster correction, characterized in that the set of auxiliary coils is formed at the same time as the pair of main winding coils by toroid winding turns (74) of wire which simultaneously surround a section radial of a half-ferrite (70) and a section of a magnetic core (72) suitably spaced (71) from   the enlarged front of the half ferrite.   10. Deflector according to claim 2, characterized in that each magnetic core (36-39) comprises polar extensions to perform a supplementary correction combined with   correction field induced by the coils.   He. Deflector according to Claim 1, characterized in that the set of auxiliary coils is fixed on an annular part (45) of the   deviator in the plane perpendicular to the axis (z) of the deflector.   Diverter according to Claim 1, characterized in that the set of auxiliary coils is fixed on a conical part (30, 31).   the deflector between the line and frame windings in front of them.   13. Diverter according to claim 2, characterized in that the induction currents through the coils are calculated so as to work the cores in their magnetic saturation zone.