JPH0451930B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an electrostatic lens or a magnetic lens formed in the mask portion or mainly in the mask portion, by arranging one or more masks closely facing a screen surface. The present invention relates to a mask-focusing type color picture tube in which at least a portion of an electron beam is focused and bombarded on a screen surface, and particularly relates to the structure of the screen portion thereof.

[Technical background and problems of the invention]

Generally, color picture tubes equipped with a shadow mask have a poor electron beam utilization rate of about 20% due to the presence of the shadow mask, which limits the brightness of the screen surface. Therefore, the most effective way to improve brightness is to increase the electron beam utilization rate by increasing the hole diameter of the shadow mask, but simply increasing the hole diameter of the shadow mask will result in a decrease in color purity and resolution. . Therefore, it is necessary to strongly focus the electron beam after passing through the shadow mask so that the electron beam diameter can be suppressed to a small value while accurately striking the phosphor on the screen surface.
As a means for this purpose, a post-acceleration tube or a mask focusing tube in which an electron lens is formed in a mask portion or mainly in a mask portion has been proposed for a long time. Such a color picture tube is disclosed in US Pat. No. 2,971,117, for example.
No. 3892995, No. 4112563, Special Publication No. 1977-
Publication No. 31265, Publication No. 45-4819, Japanese Unexamined Patent Publication No. 1972
-This is shown in Publication No. 80773, etc.

In these latter-stage accelerator tubes or mask focusing tubes (hereinafter referred to as mask focusing tubes), the electron beam utilization rate can be increased as the mask portion or the electron lens mainly formed in the mask portion has a stronger focusing power. Can be done. However, in reality, the focusing power of the electron lens is not so strong, so the utilization rate of the electron beam cannot be significantly improved.
Attempts to increase the focusing power will cause various inconveniences, which will significantly impair practicality. These inconveniences include, for example, 1
In the electrostatic lens method using a mask configuration, the voltage of the mask must be set considerably lower than the voltage of the screen surface in order to strengthen the focusing power.
Therefore, secondary electrons from the mask portion are accelerated and impacted on the screen surface, causing blurring of the image and reduction in contrast. Also, Special Publication No. 55-24652,
Two mask configurations such as U.S. Patent No. 3,892,995 and three
In the electrostatic lens method using a mask configuration, in order to obtain a strong focusing force to form an electron lens by creating a potential difference between each mask, the potential difference between the masks must be increased or the mask spacing must be shortened. The electric field between the masks must be strong, which makes it extremely difficult to maintain insulation between the masks, causing dielectric breakdown between the masks.
Furthermore, using a magnetic lens method such as that disclosed in Japanese Patent Application Laid-open No. 52-80773, it is necessary to form strong magnetic poles in order to strengthen the focusing power, but it is extremely difficult to form these strong magnetic poles, and due to these magnetic poles, This causes undesirable magnetization of metal inside and outside the color picture tube.
This causes an undesirable deflection of the electron beam trajectory.

Here, a conventional mask-focusing type color picture tube of an electrostatic lens type having a two-mask configuration will be described in more detail with reference to the drawings. FIG. 1 is an example of a conventional electrostatic lens type mask focusing tube having a two-mask configuration, and shows the schematic configuration thereof. Mask focusing type color picture tube 1 shown in FIG.
consists of a face plate 3 mainly having a screen surface 2, a net 5 connected to a side wall of the face plate 3 via a funnel 4, an electron gun 6 housed in the neck 5, and a net connected to the funnel 4. 5, a deflection device 7 attached to the outer wall, and a second beam passage hole 8 having a plurality of beam passing holes 8 facing each other at predetermined intervals in the screen 2.
a first mask 11 having a large number of beam passing holes 10 oppositely provided at a predetermined distance from the second mask 9 toward the electron gun 6; The conductive film 12 is uniformly applied to a part of the neck portion 5. The electron gun 6 has three electron guns 6R, 6G, and 6B arranged in a row in the horizontal direction, and the screen surface 2 has three colored fluorescent lights covered with a metal back, corresponding to the three electron guns 6R, 6G, and 6B. Body 13R, 13
G, 13B are regularly arranged in a stripe pattern. These striped phosphors 13 extend in the same direction as the direction perpendicular to the arrangement direction of the three electron guns 6. A pin 15 for holding the frame 14 is provided on the inner side of the face plate 3, and the frame 14 is held by an elastic body 16 welded to the frame 14 fitting into the pin 15. A first mask 11 is welded and fixed to the frame 14, and a second mask 9 is attached to the first mask 11 by an insulating fixing element (not shown).
is fixed. Further, a geomagnetic shield 17 is fixed to the frame 14 with an elastic material (not shown).

Two buttons 19 and 20 are embedded in the funnel part 4, and one button 19 is embedded in the conductive film 1.
2 and the other button 20 is in contact with the conductive film 12
It is insulated from the outside so that different potentials can be applied from the outside. The first mask 11 on the electron gun 6 side is in contact with the conductive film 12 coated on the funnel part through the frame 14 and the connector 21, and at the same time is in contact with the screen surface 2 through the frame 14 and pins 15. A high voltage is applied to the anode from the outside. On the other hand, the second mask 9 on the screen 2 side has lead wires 22 and connectors 23.
A voltage slightly lower than the anode high voltage is applied from the outside via the button 20.

The first mask 11 and the second mask 9 are
As shown in Figure a, each has elongated striped beam passage holes 41 and 40. The longitudinal direction (Y-axis direction) of the striped beam passage holes 41, 40 is perpendicular to the arrangement direction (X-axis direction) of the electron guns 6, as shown in FIG. In the mask focusing tube configured in this way, the three electron beams 30R, 30G, and 30B emitted from the electron gun 6 are deflected by the deflection device 7 while being directed toward the first mask 1.
1, a part of which passes through the beam passing hole 41 and is focused by the electrostatic lens formed between the first mask 11 and the second mask 9, and then passes through the beam passing hole 40 of the second mask 9. and the corresponding phosphors 13R, 13G, 13 on the screen 2.
Impact B and cause it to emit light. However, FIG. 2 only shows the case of one beam. Therefore, in order to prevent mislanding, the beam width W on the screen must be smaller than the width H of one striped phosphor. That is, W<H...(1) On the other hand, the beam width W on the screen is determined by the diameter D of the beam passing hole in the mask part 31, the distance Q from the mask part to the screen, and the focusing power of the electron lens formed in the mask part. It's decided by then. Figure 3 shows the focused state of the beam in the X-Z plane. From the figure, if the focal length of the electron lens is f, the beam width W on the screen is W = D (f - Q) / f ...(2) It is expressed as. Therefore, if the focusing power of the electron lens is weak, that is, if the focal length f is long, the above equation (1) cannot be satisfied. Therefore, in order to strengthen the focusing power of the electron lens, it is necessary to strengthen the electric field between the two masks, but this is not preferable because it causes dielectric breakdown. On the other hand, as a method to satisfy the above equation (1) while keeping the focusing power of the electron lens weak, there is a method of decreasing the beam passage aperture diameter D or increasing the distance Q between the mask and the screen. It is undesirable to reduce the beam passage aperture diameter D because it reduces the beam utilization rate, and it is not possible to increase the mask-screen distance Q unconditionally due to the limitations of the picture tube. As shown in Fig. 4, the distance S _g between each electron gun, the distance L from the electron gun to the screen, and the distance Q between the mask and the screen from the pitch P of the beam passage hole in the mask section are geometrically expressed as Q= This is because it is determined as P・L/3・S _g ……(3).

As described above, it is difficult to significantly improve the utilization rate of electron beams with the conventional mask focusing tube in which the focusing power of the electron lens formed in the mask part or mainly in the mask part is weak, and it is extremely impractical. .

[Purpose of the invention]

An object of the present invention is to solve practical inconveniences in a mask-focusing color picture tube that is composed of one or more masks and has an electron lens formed in the mask part or mainly in the mask part. The object of the present invention is to provide a highly practical mask-focusing type color picture tube that can improve the utilization rate of electron beams and is highly practical.

[Summary of the invention]

In the present invention, the phosphor on the screen is formed in a stripe shape that is inclined with respect to the arrangement direction of a plurality of electron beams arranged in the electron gun part, or in an intermittent stripe shape. This substantially increases the distance between the screens.
This makes it possible to improve the efficiency of electron beam utilization even in a mask focusing type color picture tube having an electron lens with a weak focusing power.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 5 shows an embodiment of the present invention and corresponds to FIG. 2. Most of the structure of the mask focusing tube of the present invention is the same as the conventional mask focusing tube shown in FIG.
In the figures, the same reference numerals as in FIG. 1 indicate the same parts as in FIG. 1. In FIG. 5, the striped beam passing holes 41 and 40 of the first mask 11 and the second mask 9 and the striped phosphor 13 on the screen 2 have their longitudinal direction (Y' axis direction) aligned with the electron gun. It is formed to be inclined with respect to the direction (Y-axis direction) perpendicular to the arrangement direction (X-axis direction) of 6. With this configuration, the pitch between the striped beam passage hole and the striped phosphor increases in the X-axis direction, which is the direction in which the electron guns are arranged. That is, if the angle formed by the Y-axis and the Y'-axis is θ in FIG. With respect to the conventional pitch P in the direction, P'=P/cosθ, 0°≦θ≦90° (4), and P'>P always holds. Therefore, from equation (3), the distance Q between the mask and the screen is also Q'=P'L/3·S _g =Q/cosθ (5), and Q'>Q is always satisfied. Therefore, as described above, the beam width on the screen can be reduced from equation (2), and equation (1) can be satisfied. At this time, the larger the inclination angle θ is, the larger the distance between the mask and the screen can be. Therefore, since the beam width on the screen can be reduced, the diameter of the beam passing hole in the mask portion can be further increased to further improve the beam utilization efficiency. However, if the inclination angle θ is too large, the image received from the inclined striped phosphor screen will be very strange, unlike the image received from the conventional vertical striped phosphor screen. This strange feeling is least noticeable in the case of a striped phosphor screen tilted at θ=45°. This is because the human eye has anisotropy in its spatial frequency characteristics, and as shown in Figure 7, the spatial sine wave response is large for vertical and horizontal patterns, and for patterns in the 45° direction. This can also be understood from the fact that it decreases. Generally, it is appropriate for θ to be between ±30° and ±60°.

As described above, according to the present invention, the distance Q between the mask and the screen can be changed without changing the other basic dimensions of the picture tube such as the electron gun interval S _g , the distance L between the electron gun and the screen, and the beam passage hole diameter D of the yask part. only can be made larger. Therefore, even if the focusing power of the electron lens formed in the mask portion is weak, the beam diameter W can be made smaller than the striped phosphor width H on the screen, and mislanding can be prevented. That is, in such a mask focusing type color picture tube, there is no need to make the potential difference between the masks excessively large in order to strengthen the focusing power of the electron lens formed in the mask portion. Therefore, to provide a highly practical mask-focusing type color picture tube that does not cause dielectric breakdown between masks and does not require reducing the beam utilization rate by reducing the diameter of the beam passing hole in the mask portion. Can be done.

In the above embodiment, the beam passing holes in the mask part were striped, but the present invention is not limited to this, but rectangular shapes as shown in Japanese Patent Publication No. 55-24652 and Japanese Patent Application Laid-Open No. 57-163955. Needless to say, the beam passing hole may also be a beam passage hole having a circular shape or the like.

For example, in a mask focusing tube as shown in Japanese Patent Publication No. 55-24652, the striped phosphor 13 on the screen 2 is moved in the direction perpendicular to the arrangement direction of the electron guns 6 (Y), as shown in FIG. By arranging the mask focusing tubes at an angle (in the Y'-axis direction) with respect to the axial direction, a more practical mask focusing tube can be provided for the same reason as in the above embodiment. At this time, in FIG. 8, since a quadrupole lens is formed in the mask portion 31, the beam is focused into a long and narrow beam along the Y'-axis direction.

Furthermore, in the above embodiments, the beam passing holes in the mask portion are inclined in the same direction as the striped phosphors on the screen, but the present invention is not limited to this.
In a mask focusing tube in which a magnetic lens is formed in a mask part as shown in Japanese Patent No. 80773, the beam passing hole in the mask part does not need to be inclined. Figure 9 shows the situation at this time. In FIG. 9, a first mask 111 and a second mask 1
09 are striped holes 141 and 140, respectively.
are made of a soft magnetic material and are arranged perpendicular to each other. A beam passage hole 142 serving as the mask portion 31 has a rectangular shape, and a disk 143 made of a permanent magnetic material is placed at the intersection of these holes, and the two masks 111 and 109 are fixed thereto. The magnetization directions of all the disks are perpendicular to the mask surface, and for example, the north pole of the disk is on the electron gun side and the south pole is on the screen side. In the mask focusing tube having such a structure, an N-S-N-S magnetic quadrupole lens is formed as shown in the figure, and the beam is focused obliquely into a long and narrow beam.
Therefore, by forming the phosphors on the screen 2 in a stripe shape that is inclined with respect to the direction perpendicular to the direction in which the electron guns are arranged, as shown in FIG. 2, the focused beams can correctly impact the phosphors. It will be like that. At this time, the pitch of the beam passage hole of the mask part and the striped phosphor on the screen in the same direction as the arrangement direction of the electron guns becomes large as in the previous embodiment.
That is, as shown in FIG. 10, the pitch P when the striped phosphor is formed in the vertical direction (Y-axis direction) and the pitch P' when it is formed inclined in the Y'-axis direction are (4 ), P'=P/cosθ...(6). Therefore, as in the case described above, the distance between the mask and the screen can be increased from equation (3), and the beam width on the screen can be made smaller than from equation (2). Therefore, it is possible to provide a highly practical mask focusing tube without causing various problems by extremely increasing the strength of the magnetic pole of the disk.

In the above embodiment, the phosphors on the screen are three striped phosphors arranged in succession, but the present invention is not limited to this. They may be arranged continuously, or one striped phosphor may be intermittently connected in the vertical direction with non-light-emitting parts in between.

〔Effect of the invention〕

As described above, according to the present invention, by forming the phosphor on the screen to be inclined with respect to the direction perpendicular to the direction in which the electron guns are arranged, the beam passage holes of the mask part are formed in the direction in which the electron guns are arranged. This increases the pitch, thereby making it possible to substantially increase the distance between the mask and the screen. Therefore, even if the focusing power of the electron lens formed in the mask part is weak, there is no need to strengthen the electric field or magnetic field to strengthen the focusing power while causing other inconveniences, and the beam utilization efficiency can be improved by reducing the diameter of the beam passage hole. It is possible to reduce the beam width on the screen to the desired size without needing to reduce the beam width, and it is expected to have the same effect as increasing the focusing power of an electron lens, making it very practical. It is possible to provide a mask focusing type color picture tube with rich characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a conventional mask focusing type color picture tube, and FIGS. 2a and 2b are schematic enlarged views showing parts of the mask section, screen section, and electron gun section of FIG. 1. 3 is a schematic sectional view taken along the X-Z plane of FIG. 2, FIG. 4 is a schematic diagram for explaining the basic positional relationship of color picture tubes, and FIG. FIGS. 6a and 6b are schematic diagrams showing a part of the mask section for explaining the pitch of the mask, and FIG. 7 is a schematic diagram corresponding to FIG. 2 in one embodiment of the present invention. Characteristic diagrams for explaining the anisotropy of resolution, Figures 8 and 9 are schematic diagrams corresponding to Figure 2 in other embodiments of the present invention, and Figure 10 shows the pitch relationship in Figure 9. It is a schematic diagram showing a part of screen part for explanation. 2... Screen portion, 6... Electron gun, 9... Second mask, 11... First mask, 31... Mask portion, 13... Phosphor.

Claims (1)

[Scope of Claims] 1. Consists of at least an electron gun section, a mask section, a screen section, an envelope surrounding these, and a deflection system, and the electron gun has at least a plurality of electron guns arranged in a line, The mask section is composed of one or more masks, and the mask section allows a part of the electron beam emitted from the electron gun section to pass through to the screen section, and at least a part of the electron beam passing through the screen section. The screen part has at least a plurality of types of phosphors arranged in stripes or intermittent stripes, and the electrons emitted from the electron gun In a mask-focusing color picture tube in which the beam is deflected and scanned by the deflection system to impact the screen section and emit phosphor, the striped or intermittent striped phosphor is used to deflect a plurality of electrons in the electron gun section. 1. A mask focusing type color picture tube, characterized in that it is formed to be inclined with respect to a direction perpendicular to the direction in which guns are arranged.