JPH03297035A - Shadow mask structure for cathode-ray tube - Google Patents

Abstract

PURPOSE:To liberate from problem with chromatic misconvergence etc., even though a wholy or partially bright screen is displayed, or even though the installing position and/or direction is varied, by using a mild steel plate for a shadow mask, and using a specific material for the mask frame. CONSTITUTION:A shadow mask 3 is made of mild steel, while a mask 1 is made of a material containing 12-19wt.% Cr and remainder of Fe with additives of 1-3wt.% Si or 0.1-0.5wt.% Al, wherein the C content is suppressed below 0.01wt.%. The uniform tension given to the shadow mask 3 when the shadow mask 3 is secured to the mask frame 1 will never drop during the CRT manufacturing process. Thereby no chromatic misconvergence will occur even in the event of temp. rise of the shadow mask 3 caused by bombardment with electron beam during practical service, and also influence of the terrestrial magnetic field sink to a great extent. Thus the chromatic misconvergence is suppressed to a degree not presenting any substantial problem even through the installing position and direction are changed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can be used even when displaying a bright screen or a screen including a very bright part, and even when changing the installation position or direction.
The present invention relates to a shadow mask structure for a color cathode ray tube that does not cause problems such as color shift.

[Prior Art] In a shadow mask type color cathode ray tube, three electron beams emitted from electron guns dedicated to each primary color, emitting red, green, and blue light, strike one electron at a scanning position on a shadow mask. After passing through the beam passage hole, the electron beams for each primary color impinge on dots or stripes of red, green, and blue phosphors arranged at landing positions on the inner surface of the panel, respectively, and are excited to emit light.

Therefore, in order to achieve good color display, it is necessary to have a large number of electron beam passing holes in the shadow mask and red, green, and blue phosphor dots or dots arranged on the inner surface of the panel corresponding to each of these electron beam passing holes. The stripes must maintain a given correct relative position.

However, the electron beam passage hole occupies only about 15 to 20% of the area within the effective surface of the shadow mask, and the electron beam collides with the shadow mask at locations other than the holes, heating the shadow mask and increasing the temperature there. raise. Unless you have taken special measures.

The shadow mask expands as the temperature rises, and when the degree of expansion becomes severe, the correspondence between the electron beam passage holes and the dots and stripes of each primary color phosphor on the inner surface of the panel deviates from the predetermined correct relative position. This results in deterioration of color purity.

Conventionally, as one of the solutions to the above problem, a shadow mask is fixed to a mask frame while being given a uniform tension in each direction.

When a shadow mask attempts to thermally expand, a method has been proposed in which the tension there is only relaxed and the shadow mask does not actually deform. In other words, a method has been proposed in which the deformation due to thermal expansion is absorbed by the pre-applied tension.

However, in the above-mentioned conventional technology, if the shadow mask to which tension is applied is heated to around 450°C during the manufacturing process of the cathode ray tube, such as the process of melting and exhausting the panel and funnel, plastic deformation etc. may occur. There was a problem that the tension could be significantly reduced due to the tension generated.9 In order to solve this problem, the present inventors have
As disclosed in Japanese Patent No. 9736, mild steel is used as the shadow mask material and 10 to 32% (
We have developed a technology to suppress the drop in shadow mask tension in the cathode ray tube manufacturing process by using stainless steel containing Cr (hereinafter referred to as weight percent) and residual Fe due to the difference in coefficient of thermal expansion. Proposed.

[Problem to be solved by the invention] However, the above countermeasure technology lacks consideration for the magnetic properties of the mask frame material, and when the color cathode ray tube is actually used, if the installation position or direction is changed, the earth It was not possible to completely suppress color shift caused by the influence of the magnetic field.

The present invention can be used even when displaying a bright screen or a screen containing extremely bright parts, and even when changing the installation position or direction.
An object of the present invention is to provide a shadow mask structure for a color cathode ray tube that does not cause problems such as color shift.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a shadow mask provided with a large number of holes, and a mask frame to which this shadow mask is fixed with uniform tension. In the shadow mask structure for a cathode ray tube, the shadow mask is made of a mild steel plate, and the mask frame is made of a mild steel plate.

The main components are 12 to 19% Cr and the remainder Fe, and 1
It was decided to use a material to which ~3% Si or 0.1~0.5% Al was added, and the C content was further suppressed to 0.01% or less.

[In the process of manufacturing working cocolor cathode ray tubes, the shadow mask is heated to 400° C. or higher. At this time, if a shadow mask that has been tensioned in advance is stretched on a mask frame, for example, if both the shadow mask and the mask frame are made of mild steel, which is the easiest to obtain, the yield strength will decrease at high temperatures, and the - This leads to plastic deformation. Additionally, when cooling from a high temperature, the shadow mask and mask frame tend to cool down and contract more quickly than the mask frame due to differences in heat capacity and surface area, which may also result in plastic deformation. .

These appear in the form that when the shadow mask is cooled to room temperature, the tension of the shadow mask is lower than before passing through the high temperature.

As a result of experiments, it was found that when mild steel is used for the shadow mask, it is desirable that the mask frame has an average thermal expansion coefficient of (8 to 13) x 10-'/°C from room temperature to around 450°C.

In addition to the coefficient of thermal expansion, as a mask frame material,
It is necessary to have magnetic characteristics, that is, a high magnetic permeability that can be demagnetized by a degaussing means provided in the television set to such an extent that color shift does not occur even if the installation position and direction are changed under the influence of the earth's magnetic field. The main components are 12-19% Cr and residual Fe, with 1-3% Si or 0.1-0.5% AI.
Materials with C content added to and further suppressed to 0.01% or less have a maximum magnetic permeability of 3000 or more and a coercive force of 0.50.
The shadow mask structure of the present invention uses this material as a mass frame material, which improves the magnetic shielding effect of the color cathode ray tube and reduces color shift due to the earth's magnetic field. reduce

[Example 1] Fig. 1 is a perspective view of an embodiment of the present invention, in which 1 is a mask frame, 1a is a peripheral upper end surface of the mask frame, 1b is a weld line on the peripheral upper end surface of the mask frame, and 2 is a plate. spring, 2
a is a hole that engages with a stud, 3 is a shadow mask, 3a
is the electron beam passage hole. Mask frame 1 is 13
The main components are %Cr and Fe, to which 2%Si is added,
Stainless steel with a C content of 0.01% or less, L
It has a cross section with a diameter of 8 cm at the top, a width of 3.5 wm at the bottom, and a height of 1.5 m, and the overall size is 404 m + width and 306 ai in height. Since it is made of stainless steel, the surface is difficult to oxidize, but the outer surface of the frame
Fine irregularities of about 0 to 50 μm are formed by sandblasting or the like to facilitate oxidation, and this is heated at 600° C. for 20 minutes in an oxidizing atmosphere, such as CO or —CO, to form an oxide film on the surface.

When an oxide film is formed in this manner, the reflection of the surface is significantly reduced, and in general, the reflectance easily becomes 1% or less at the wavelength of light used during exposure.

Note that a leaf spring 2 having a hole 2a is fixed to the mask frame 1 for attaching it inside the panel.

The shadow mask 3 is made of a mild steel plate and has a thickness of 0.025
m+, hole diameter 0.11++a on the entire effective area excluding the peripheral area
The electron beam passing holes 3a are arranged at intervals of about 0.25 mm and the mutual angle of the rows is 60 degrees. This is Shadow Mask 3.

Under tension, its peripheral edge is welded to the mask frame along a welding line 1b indicated by a two-dot chain line connecting approximately the center of the peripheral upper end surface 1a of the mask frame 1.

Next, a method of manufacturing such a shadow mask structure will be explained with reference to FIG. First, a shadow mask material plate 3b, which has a large number of electron beam passing holes 3a formed in the effective part corresponding to the screen display part and whose outer periphery is circular and widely spread, is arranged at many locations over the entire circumference. The mask is flatly fixed to the surrounding frame 5 by welding points 4.

At this time, the shadow mask 3 can be easily fixed flat by pulling it slightly outward from the center using a spring or the like (not shown). As the material for the mask tension frame 5, austenitic stainless steel 5US304 or the like is used.

The shadow mask material plate 3b flatly fixed to the mask tension frame 5 as described above is placed in a furnace and heated to 90°C. Thereafter, this is taken out from the furnace, and air 6 whose temperature is adjusted to 30°C is blown over the entire shadow mask material plate 3b, and only the shadow mask material plate 3b is cooled to 30°C. At this time, the thickness of the shadow mask material plate 3b is 0.
．． 025, which is extremely thin, so it cools down to 30 degrees Celsius in about 10 seconds. On the other hand, since the mask tension frame 5 has a large heat capacity, the temperature hardly decreases. Mask pulling frame 5
The thermal expansion coefficient of 5US304 used as the material is 17.
Since it is about 3 x 10-', the temperature at 90°C
The shadow mask material plate 3b shrinks due to a temperature drop of 60°C from 30°C to 30°C.

A tension of 20 kg/a112 or more is applied uniformly.

At a predetermined position under the shadow mask material plate 3b in a state where uniform tension is applied in this way.

The mask frame 1 on which the oxide film has been formed as described above is placed on the stand 7.
The welding point 8 (
These welding points 8 are connected to form the above-mentioned welding line 1b)
Then, the shadow mask 3 and the mask frame 1 are welded and fixed over the entire circumference by spot welding, seam welding, or the like. After welding, the shadow mask 3 is cut and separated from the shadow mask material plate 3b along the outer periphery of the mask frame 1.

This separation work may be performed after the mask tension frame 5 has cooled to room temperature. In this way, a shadow mask structure as shown in FIG. 1 in which uniform tension is applied to the shadow mask 3 is completed.

FIG. 3 is a side view showing, in sectional view, the essential parts of the color cathode ray tube according to the present invention equipped with the shadow mask structure according to the embodiment of the present invention completed as described above. Here, in the shadow mask structure, the hole 2a of the leaf spring 2 attached to the mask frame 1 is engaged with the stud 10 planted on the inner surface of the skirt portion of the panel 9, as shown in FIG. supported on the inside. Exhaust treatment and the like are performed in this state.

The shadow mask structure manufactured in this way does not lose its tension even when it passes through a heating process of 400°C or higher during the subsequent manufacturing process of the cathode ray tube, such as the exhaust process, and the shadow mask structure does not lose its tension even when it passes through the heating process of 400°C or higher during the subsequent manufacturing process of the cathode ray tube, and it also has the ability to withstand the coating drying of graphite for the conductive film and the fluorescent coating. No problems occur during exposure to form a surface, and the magnetic properties of the completed tube are excellent.

In the above example, a case was explained in which 2% Si was added to the main components of 13% Cr and the remaining Fe, but a material in which 0.1 to 0.5% Al was added instead of Si was used. Similarly, a shadow mask structure having good magnetic properties can be obtained.

In the shadow mask structure of the present invention, a mild steel plate is used for the shadow mask itself, and the mask frame is made of so-called 13Cr stainless steel, which has been widely used as an inexpensive stainless steel, with 1 to 3% Si or 0.5% Si. 1-0.5% A
1 and suppressing the C content to 0.01% or less, it is an inexpensive material that is very easy to manufacture at the current state of the art. In addition, the coefficient of thermal expansion of this material is 1' I L X I from room temperature to 430°C.
O-'/"C1", which is smaller than 14x10-'/"C of the mild steel used as the shadow mask material, causes plastic deformation of the shadow mask when heated in the color cathode ray tube manufacturing process. There is no danger that the tension will decrease.

Conventionally, when the mask frame was manufactured from ordinary so-called 13Cr stainless steel, the amount of movement of the electron beam on the fluorescent surface of the cathode ray tube due to the earth's magnetic field was 40 μm. Therefore, it is 15
decreased to μm.

Note that the shape of the mask frame does not need to be limited to an L-shaped cross section, and may be formed into a more complicated cross-sectional shape by, for example, press working. Further, in the above embodiment, tension was applied to the shadow mask using the mask tensioning frame, but the present invention is not limited to this, and tension may of course be applied by other methods.

[Effects of the Invention] As explained above, according to the present invention, the uniform tension applied to the shadow mask when fixing the shadow mask to the mask frame does not decrease during the cathode ray tube manufacturing process, and can be applied to the actual tension. Even if the temperature of the shadow mask rises due to electron beam impact during use, one color shift will not occur, and the influence of the earth's magnetic field is also significantly reduced, even if the installation position and direction are changed.

Color shift is suppressed to such an extent that it hardly becomes a problem.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a diagram illustrating a method of fixing a shadow mask to a mask frame with uniform tension applied to the shadow mask in advance, and FIG. The figure is a sectional side view showing the main parts of a color cathode ray tube equipped with a shadow mask structure according to the present invention. DESCRIPTION OF SYMBOLS 1... Mask frame, 1a... Surrounding upper end surface of mask frame, 1b... Welding line on upper end surface of mask frame, 2... Leaf spring, 2a... Hole that engages with stud, 3 ...Shadow mask, 3a...
・Electron beam passing hole, 3b... Shadow mask material plate, 4... Welding point, 5... Mask tension frame, 6... Air, 7... Stand, 8... Welding point,
9...Panel, 3rd Figure 1-Masfu shi 1m 2-nonρ) Pregnancy 3-yoi ¥-゛tsu1fufu 9-no

Claims (1)

[Claims] 1. A cathode ray tube shadow mask structure comprising a shadow mask provided with a large number of holes and a mask frame to which the shadow mask is fixed under uniform tension, wherein the shadow mask is made of mild steel; In addition, the mask frame contains 12 to 19% by weight of Cr and the remainder F.
e as the main component, and 1 to 3% by weight of Si or 0.5% by weight.
A shadow mask structure for a cathode ray tube, characterized in that it is made of a material to which 1 to 0.5% by weight of Al is added and the content of C is suppressed to 0.01% by weight or less.