JPS60107241A - Color cathode ray tube - Google Patents

Abstract

PURPOSE:To reduce loss of electron beam energy by collision with shadow mask 11 and improve luminous brightness by providing a ferro-magnetic member magnetized almost in the axial direction to the surface of shadow mask in the side of electron gun. CONSTITUTION:A ferro-magnetic material 13 is provided to the surface of shadow mask 11 in the side of electron gun in such a manner as not interfering the path of electron beam 14 which passes through electron beam passing hole 12 of shadow mask 11. Regarding the position of providing the ferro-magnetic member 13, the line of magnetic force 15 formed by the ferro-magnetic member 13 magnetized almost in the axial direction Z can be made thick in the vicinity of electron beam passing hole 12 by providing said member 13 with an interval L from the edge 111 in the side of electron gun of the electron beam passing hole and thereby convergence of electron beam 14 can be improved. In case the electron beam passing hole 22 is formed like the slit, the ferro-magnetic material 23 is provided in parallel with a longer side of the electron beam passing hole 22. In case the electron beam passing hole 32 is circular, the ferro-magnetic material 33 is provided at the circumference of electron beam passing hole 32.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a color cathode ray tube, and more particularly to a shadow mask having a large number of circular or slit-shaped electron beam passage holes.

[Technical background of the invention and its problems]

The color cathode ray tube most widely used today uses a shadow mask method. In general, this method consists of an electron gun that emits multiple electron beams, a phosphor surface that is regularly provided with phosphor layers that emit light of a plurality of different colors, and a phosphor layer that emits multiple electron beams. It is equipped with at least a shadow mask in which a large number of circular or slit-shaped electron beam passage holes are formed to strike the layer, and the plurality of electron beams are deflected by a deflection device and then deflected by one electron of the shadow mask. The beam passes through the beam passage hole, hits each phosphor layer, excites the phosphors constituting the phosphor layer, and reproduces a color image on the phosphor surface.

For this reason, the shape of the electron beam passage hole in the shadow mask is such that the hole diameter on the fluorescent surface side is larger than the hole diameter on the electron gun side so that the electron beam incident from an oblique direction is not blocked by the side wall of the electron beam passage hole. It has a large conical shape.

In a color cathode ray tube equipped with such a shadow mask, most of the electron beam emitted from the electron gun is blocked by the shadow mask, and the amount of electron beam that excites the phosphor is equal to the total amount emitted from the electron gun. 15 of the electron beam amount
% to 25%, otherwise the electron beam will collide with the shadow mask, so there will be a large loss of electron beam energy due to the shadow mask, and there will be deterioration of color purity due to brightness and thermal deformation of the shadow mask. There is also a problem in that it is very disadvantageous in terms of power consumption.

In order to solve this problem, a ferromagnetic material is provided on each side wall of the electron beam passage hole, and this ferromagnetic material is magnetized approximately in the tube axis direction of the color cathode ray tube. A technique in which the body is used as a magnetic lens to focus an electron beam onto a phosphor layer is disclosed in Japanese Patent Laid-Open Nos. 49-15361 and 49-29971. That is, in order to reduce the loss of electron beam energy due to the shadow mask and improve brightness, even if the electron beam passage hole is simply made larger, the diameter of the electron beam will also increase, and the electron beam will fall below the phosphor layer where it should strike. Since the phosphor layer of other colors may also be excited to emit light, leading to deterioration of color purity and deterioration of image quality, in order to utilize the focusing effect of the cylindrical magnet, the side wall of the electron beam passage hole is A magnetic lens is formed by a magnetized ferromagnetic material provided in the electron beam to focus the electron beam.

Next, to explain its configuration with reference to FIG. 1, a cylindrical ferromagnetic material (3) is provided on the side wall of the electron beam passage hole (2) of the shadow mask (1), By magnetizing the color cathode ray tube in a direction that substantially coincides with the tube axis (Z), the electron beam (4
) has a rotational speed component in the direction perpendicular to the plane of the paper due to the magnetic field component perpendicular to the electron movement direction of the magnetic field line (5), and the interaction between this rotational speed component and the magnetic field of the magnetic field line (5) in the tube axis (Z) direction Due to this action, the electron beam (4) has a velocity component in the radial direction, and this velocity component causes the electron beam (4) to converge as shown in (41).

However, in the shadow mask described above, since the magnetic resistance of the shadow mask is lower than that of the electron beam passage hole (2), the magnetic field is mainly formed on the Nyadu mask side, as shown by the lines of magnetic force (6) in Figure 1. , the magnetic field on the side of the electron beam passage hole (2) becomes weaker, and there is a problem that a sufficient electron beam convergence effect cannot be obtained.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and it more effectively performs the magnetic lens action, reduces the loss of electron beam energy due to the shadow mask, and improves the brightness. It is an object of the present invention to provide a color cathode ray tube in which deterioration in purity can also be reduced.

[Summary of the invention]

That is, the present invention provides an electron gun that emits a plurality of electron beams, a fluorescent surface in which four fluorescent layers having a plurality of different emission colors are regularly provided, and an electron gun that emits a plurality of electron beams with a predetermined fluorescent light. In a color cathode ray tube, which is equipped with at least a mask having a large number of circular or slit-shaped electron beam passage holes for impinging on the body layer, the path of the electron beam passing through the electron beam passage holes is obstructed. This is a color cathode ray tube characterized in that a ferromagnetic member magnetized approximately in the tube axis direction is provided on the electron gun side surface of the shadow mask to prevent In an embodiment, the member is provided around a circular electron beam passage hole, and in a stripe shape in the longitudinal direction of the slit-shaped electron beam passage hole.

With such a structure, it is possible to provide an effective magnetic lens effect and improve the convergence effect of the electron beam.

[Embodiments of the invention]

First, the present invention will be conceptually explained with reference to FIG.

That is, the electron beam passing hole portion (
A ferromagnetic member f1.31 with a large coercive force is provided on the electron gun side surface of the shadow mask (I) so as not to obstruct the path of the electron beam (14J) passing through the ferromagnetic member (1). Magnetize in the direction of the tube axis (Z). In this case, the ferromagnetic part (, 1 (13) should be placed at a distance (L) from the γB electron gun side edge part (111) of the electron beam passage hole). This magnetized ferromagnetic member (
13) The lines of magnetic force 05) formed by the electron beam passage hole (
It becomes possible to make it dense in the vicinity of lz, and the convergence of the electron beam 04) can be improved.

This improvement in convergence makes it possible to substantially increase the hole diameter of the electron beam passage hole 02, thereby reducing the loss of electron beam energy due to impact on the Nyadou mask (1υ) and improving the luminance. Further, deterioration of color purity caused by heating deformation caused by the impact of the electron beam 04) on the shadow mask 0υ can also be suppressed. Furthermore, if the luminance of light emission remains at the same level as the conventional one, it is possible to save power by reducing the loss of electron beam energy.

This ferromagnetic part April 13) has a high coercive force) N1-Co alloy with a single Curie point, N1-Co-P alloy,
Co-Cr alloy etc. are suitable.

In addition, methods for providing this ferromagnetic member (2) in a shadow mask include a vapor deposition method in which the ferromagnetic member (2) is deposited through a mask having openings corresponding to the forming portions, and a method in which an insulating layer is formed in areas other than the forming portions by an exposure method. There are electrodeposition methods such as electrodeposition.

In addition, after providing the ferromagnetic member (13) at a desired portion of the shadow mask I, it is preferable to magnetize the shadow mask (11) in the substantially tube axis direction by magnetizing both sides of the shadow mask (11) with an electromagnet or a permanent magnet. Mask and ferromagnetic member (131
It is easy to magnetize it by heating it to about 200"C to 300C.

Furthermore, the magnetization strength of the ferromagnetic member (1 m) should be selected appropriately depending on the type of pipe to be used, but experiments have shown that a few tens of Gauss can almost achieve the purpose.

Next, one embodiment of the color cathode ray tube of the present invention will be explained with reference to FIG. Since the shadow mask type color cathode ray tube having a fluorescent surface is almost the same as that commonly used, illustrations and explanations thereof will be omitted, and only the essential parts of the shadow mask will be explained.

That is, FIG. 3 shows the shadow mask (?I) when the electron beam passing hole (the plastic material is slit-shaped, and the ferromagnetic material 03 is magnetized approximately in the direction of the tube axis) is the shadow mask Q.
An electron beam passing hole (2) is placed on the electron gun side of υ so as not to obstruct the path of the electron beam passing through the
22) are provided in parallel to the long side direction.

The reason for this horizontal spread is that the electron beam passage hole (22i
This is because it is difficult to provide it in the short side direction of the shadow mask because the area of the shadow mask in this direction is small, and also because color cathode ray tubes using this type of shadow mask do not require convergence of the electron beam in the short side direction. be.

Next, another embodiment of the present invention will be described with reference to FIG. In this case as well, only the main parts of the shadow mask will be explained as in the previous embodiment.

That is, FIG. 4 shows a shadow mask (3υ) in which the electron beam passage hole C33 is circular, and the ferromagnetic material G moat, which is magnetized approximately in the direction of the tube axis, is located on the electron gun side of the shadow mask (3I). Electron beam passage hole (3) Provided around the electron beam passage hole C32 so as not to obstruct the path of the electron beam passing through the pier.

Although the relationship between the electron beam passage hole and the ferromagnetic material was not clearly explained in the two embodiments described above, the angle of incidence of the electron beam to the electron beam passage hole is minimized when the deflection angle is maximum. The ferromagnetic member is most likely to block the electron beam in this part.

Therefore, if a ferromagnetic member is provided so as not to obstruct the electron beam at this position, the electron beam will not be obstructed at other parts of the shadow mask. Further, the larger the cross-sectional area of the ferromagnetic member is, the more the magnetic lens effect can be enhanced.

Next, the relationship between the electron beam passage hole and the ferromagnetic member will be explained with reference to FIG. However, although FIG. 5 shows the case of a slit-shaped electron beam passage hole, the same applies to a circular shape.

That is, a ferromagnetic member (43) having a rectangular cross section is provided on the electron gun side of a shadow mask (41) in which an electron beam passage hole (421) is formed, and a shadow mask (41) is provided in the electron beam passage hole (6). ) at an angle of incidence (θ) with respect to the electron beam (
44) is incident, the electron beam passing hole (4 diameters (to), pitch (P), electron beam passing hole (42
The edge (421) on the electron gun side of is L-(P-
W)/4. H=(I)-W)tan e/8.

As an example, the dimensions of each part of a 20-inch color cathode ray tube are shown as follows: maximum beam deflection angle of 9238 degrees, shadow mask curvature Mn = 780 mm, distance between the center of deflection and the center of the shadow mask LO = 265. The incident angle of the electron beam on the shadow mask surface is 0 = 66 degrees,
W=0.2 mvt, P=0.75 mm.

In this case, the structural dimensions of the ferromagnetic member (49) are set to height H=0.3
As a result of setting the 1/1 space L = 0.14 mm and using Ni-Co alloy as the ferromagnetic member, the luminance is approximately 20% higher than that of conventional color cathode ray tubes, and the color purity is improved by heating deformation of the shadow mask. An improvement of approximately 25% was also observed in the deterioration of

〔Effect of the invention〕

As described above, according to the present invention, the action of the magnetic lens formed in the electron beam passage hole can be made more effective on two planes, so that the convergence of the electron beam can be improved. As a result, it is possible to provide a color cathode ray tube that can be expected to reduce electron beam energy loss, improve luminance, and improve color purity characteristics due to thermal deformation of the shadow mask.

[Brief explanation of the drawing]

Figure 1 is an explanatory cross-sectional view showing an example of a shadow mask with a magnetic lens used in a conventional color cathode ray tube;
The figure is an explanatory sectional view showing the basics of a shadow mask with a magnetic lens used in the color cathode ray tube of the invention, and FIG. 3 is a diagram showing a shadow mask adapted to an embodiment of the color cathode ray tube of the invention. , FIG. 3(a) is a plan view of the main part seen from the electron gun side, FIG. 3(tb) is a cross-sectional view of FIG. 3(a) taken along line A-A, FIG. 4 is a diagram showing a shadow mask adapted to another embodiment of the color cathode ray tube of the present invention, FIG. 4(a) is a plan view of the main part as seen from the electron gun side, and FIG. 4(b) Figure 4 is a cross-sectional view taken along the line B-Il and viewed in the direction of the arrow; Figure 5 is an explanatory factor showing the dimensional relationship between the electron beam passage hole, the electron beam, and the ferromagnetic assembly. 1.11, 21, 31.41...Shadow mask 2.
12, 22, 32.42...Electron beam passage hole 3.
13,23,33.43...Ferromagnetic material 4.14.44
... Electron beam 5.6, 15.16 ... Magnetic field agent Patent attorney Inoue - Male 1st r: IA Figure 2 1711

Claims (3)

[Claims] (1) An electron gun that emits a plurality of electron beams; a phosphor surface in which phosphor layers having a plurality of different emission colors are regularly provided; In a color cathode ray tube comprising at least a shadow mask in which a large number of circular or slit-shaped electron beam passing holes are formed for the electron beam to strike a layer, a path of the electron beam passing through the electron beam passing holes; A color cathode ray tube, characterized in that a ferromagnetic member magnetized substantially in the tube axis direction is provided on a surface of the shadow mask on the electron gun side so as not to interfere with the electron gun. (2) A color cathode ray tube according to claim 1, wherein a ferromagnetic member magnetized substantially in the direction of the tube axis is provided around the circular electron beam passage hole. (3) Ferromagnetic strips magnetized substantially in the tube axis direction are provided in a stripe shape in the long side direction of the slit-shaped electron beam passage hole. Color cathode ray tube as described.