JPS63190230A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To unify the effect of the eddy current in the side wall on three electron beams by making the thickness of the side wall of a screening electrode made of nonmagnetic metal thin in the vertical direction and thick in the horizontal direction. CONSTITUTION:The thickness of the side wall of a screening electrode 1 is made thin in the vertical direction 2 and thick in the horizontal direction 3. The eddy current generated on the side wall of the screening electrode 1 by the horizontal deflection magnetic flux is made larger as the wall thickness becomes thick, and it serves as the magnetic field source affecting the beams on both sides. The wall thickness in the horizontal direction is made thick, thereby the effect of the eddy current on the in-line electron beams can be unified. As a result, the mis-convergence caused by the eddy current can be suppressed to the nonproblematic degree even if the horizontal deflection frequency is made high.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an in-line color cathode ray tube having convergence characteristics suitable for use at high horizontal deflection frequencies, or at multiple horizontal deflection frequencies.

[Conventional technology]

Currently, there are not many problems when using in-line color cathode ray tubes in standard broadcast color television receivers, but in high-definition video data terminals (VD
T) As a river, when used with a large number of horizontal scan lines and therefore a high horizontal deflection frequency - of the three electron beams aligned on the horizontal plane.

There has been a problem in that the difference between the area scanned by the central beam, that is, the image reproduction area, and the area scanned by the electron beams at both ends becomes noticeable.

The cause of this problem is estimated to be as follows.

A cylindrical shield side wall surrounding the three electron beams is installed at the end of the fluorescent screen side of the electron gun that forms three electron beams in-line, in order to shield the electron beams from the electrostatic charge that is charged on the inner wall surface of the glass bulb. A bottomed cylindrical shield electrode made of non-magnetic metal and having a bottom surface near the cathode with electron beam passage holes for each of the three electron beams is disposed.

On the other hand, the deflection yoke for generating the deflection magnetic field for deflecting the electron beam is placed outside near the connection with the funnel tube of the bulb, but the end near the cathode side of the deflection magnetic field is exactly Due to the relative position of the shield electrode passing through the shield side wall, eddy currents are induced in the conductive shield side wall by the deflection magnetic field that changes between The magnetic field is weakened. At a horizontal deflection frequency similar to that of a standard broadcasting system, the influence of eddy currents is small, and even if the scanning area of the center electron beam differs from the scanning area of the electron beams at both ends, the amount of difference is small and does not pose a problem. However, in high-definition display tubes for VDT, the number of horizontal scanning lines is large, and the time rate of change of the magnetic field for horizontal deflection is much faster than in the case of television broadcasting, so eddy currents occur on the shield side walls of the shield electrode. This is thought to be due to the fact that it has become much larger, and its influence has become more noticeable.

Furthermore, in JP-A-56-76145, a magnetic field control element is provided on the bottom surface of the shield magnetic pole to increase the horizontal deflection magnetic flux density acting on the central electron beam and to lower the horizontal deflection magnetic flux density acting on both side electron beams. Inline color l1
In a triode tube, a vortex is formed in the path of each electron beam generated from an electron gun, the one whose deflection lags in time compared to other electron beams, due to temporal changes in the horizontal deflection magnetic flux. It is disclosed to provide an eddy current inducing element that generates an electric current. In order to prevent the horizontal deflection angle of the central electron beam from becoming small, the magnetic field control elements (actually, small cylindrical members made of a high permeability magnetic material) are placed above and below the central electron beam passage hole. This arrangement increases the magnetic flux density of the deflecting magnetic field acting on this beam. In addition, an annular body made of a high-permeability magnetic material is placed around the electron beam passage holes on both sides to form a bypass for the magnetic flux that detours around the beam passage holes, thereby weakening the horizontal deflection magnetic field that acts on the electron beams on both sides. I have to. Furthermore, eddy current inducing elements are provided above and below the beam passage holes on both sides, respectively, to protrude in the shape of an eave and extend horizontally and orthogonally to the deflection magnetic flux.

Therefore, four magnetic control elements and four eddy current induction elements are arranged on the bottom surface of the shield electrode.

Next, JP-A-60-86736, JP-A-60-867
In order to prevent the horizontal deflection magnetic field from being weakened by the above-mentioned eddy currents, Publication No. 37 discloses that, in order to prevent the horizontal deflection magnetic field from being weakened by the above-mentioned eddy current, the portions of the shield side wall where the eddy current intersects with the horizontal deflection magnetic field are cut out, and the shield side wall is deflected. It is disclosed that the height of the shield side wall is limited to 6.0 m or less in order to reduce the area that intersects with the magnetic field.

[Problem that the invention seeks to solve]

The present invention focuses on the convergence of the central electron beam and both side electron beams, which becomes noticeable when an in-line color cathode ray tube is used by increasing the number of horizontal scanning lines and increasing the horizontal deflection frequency in order to obtain high definition. It is an object of the present invention to provide a color cathode ray tube that sufficiently suppresses defects, solves other problems, is simple and easy to manufacture, and fully exhibits not only the original effect of the shield electrode but also the secondary effects. purpose.

[Means for solving problems]

In the present invention, it is made of non-magnetic metal and has a bottom with an opening toward the phosphor screen. The total flexural thickness of the shield side wall of the cylindrical shield electrode is made thin in the vertical direction and thick in the horizontal direction, so that the effects of eddy currents generated in the shield side wall due to temporal changes in the magnetic flux for the horizontal deflection magnetic field are lined up in-line. So as to act on the three electron beams, that is,
Instead of working strongly only on the central electron beam as in the past,
It has been made to work even more strongly than before for double-sided electron beams.

[Effect]

The eddy current flowing through the shield side wall of the shield electrode due to the water IL deflection magnetic flux increases as the resistance of the circuit through which the eddy current flows decreases, that is, the thickness of the shield side wall increases. Therefore, by making the thickness of the left-right portion of the shield side wall, which becomes the source of the magnetic field acting on both beams, n smaller than the thickness of the vertical portion where the eddy current acting on the central electron beam flows, the eddy current can be reduced. The effect of the weakening magnetic field formed can now be made equal for each electron beam in the inline array, suppressing misconvergence caused by eddy currents to within a non-problematic range even when the horizontal deflection frequency is high. I can do it.

〔Example〕

FIG. 1(a) shows a shield electrode 1 of a first embodiment of a color cathode ray tube according to the present invention, in which 2 is a lower side wall of the shield side wall, 3 is a left and right side wall, and 4 and 6 are beam passing holes on both sides. ,
Reference numeral 5 indicates a central beam passage hole, and reference numeral 7 indicates an inner wall material forming a part of the left-right side wall 3.

Further, FIG. 1(b) shows a shielded structure 7441a according to another embodiment of the present invention, in which 2a is a vertical side wall of the shield side wall, 3a is a left and right side wall, 4 and 6 are beam passing holes on both sides,
Reference numeral 5 designates a central beam passage hole. In both embodiments, the vertical side walls 2, 28 perpendicular to the in-line arrangement direction are made thinner than the left-right side walls 3, 3a. For this reason, the influence of eddy currents flowing through the shield side walls is relatively weaker in the central beam portion and stronger in both side beam portions than in the case where the side walls have a uniform thickness. In other words, the horizontal deflection magnetic field acting on the central electron beam becomes relatively strong, and the water T1 acting on both side electron beams becomes relatively strong.
2. The deflection magnetic field becomes relatively weak, and the three electron beams are concentrated with high accuracy both in the center and on both sides of the screen, resulting in a good high-definition image.

If it is not necessary to produce in large quantities, the left and right side walls can be made thicker by using two layers with abutment according to the first embodiment, and if produced in large quantities, relatively flexible plastic deformation can be used. By press-forming materials that are easy to mold, or by using the precision U-adic system,
It may be produced according to the embodiment.

In addition, when adopting the first embodiment, the portions where the thickness of the fillet is thickened only need to be the portions where the deflection magnetic flux intersects with the side wall.
It goes without saying that it is not necessary to span the entire height of the side wall.

Moreover, FIGS. 1(c) and 1(d) show a shield electrode 1b and an IC of still another embodiment of the color cathode ray tube of the present invention, and the same parts as FIGS. 1(a) and (b) are shown. The same symbols will be used and detailed explanation will be omitted. FIG. 1(c) shows an embodiment corresponding to FIG. 1(a), in which a portion 8 of the left-right side wall 3 that does not affect the trajectory of both side beams is cut away. Also, FIG. 1(d) corresponds to FIG. 1(b),
Similar to Fig. 1 CQ), part 9 is cut away.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily manufacture a high-definition tube in which electron beam misconvergence is suppressed to a practically non-problematic level using an in-line electron gun.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(d) are plan views of shield electrodes of an embodiment of the color cathode ray tube of the present invention. 1.1a... Shield electrode, 2.2a... Upper and lower side walls, 3, 3a... Left and right side walls, 4, 6... Beam passing holes on both sides, 5... Center beam passing hole. 1st item 4.5, 4: Himi-m-i-Buddha-ru

Claims (1)

[Claims] 1. In an in-line color cathode ray tube, an electron gun that forms three nearly parallel electron beams in one horizontal plane.
It is located at the end of the phosphor screen, and is made of non-magnetic metal and consists of a bottom surface with three electron beam passage holes and a cylindrical shield side wall that shields the electron beam from charging on the glass bulb wall. A color cathode ray tube characterized in that the metal thickness of the side wall of the shield of an open bottomed cylindrical shield electrode is thinner in the vertical direction and thicker in the horizontal direction.