JPH02160340A - Picture tube - Google Patents

Abstract

PURPOSE:To provide a bright and fine picture of high quality by giving a shadow mask tensile force for flat fixing. CONSTITUTION:In order that a size variation due to thermal expansion, predicted in normal operation temperature, is given as distortion at a minimum temperature, tensile force is given in a longitudinal direction or otherwise in a perpendicular direction under the necessity to a shadow mask 21. That is, the shadow mask 21 is given the tensile force for flat fixing. As a result, displacement such as positional shift of electron beam permeable cells following the thermal expansion of the shadow mask 21 can be restained. It is thus possible to obtain a less color-shift, fine and bright picture of high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a picture tube with high display image quality using a shadow mask.

[Technical background of the invention and its problems] A picture tube generally has the configuration shown in FIG.

That is, a neck portion 2 constituting one end of the glass envelope 1 is provided with, for example, an in-line electron gun 3, and a face portion 4 at the other end of the glass envelope 1 facing the electron gun 3 is provided. , a fluorescent screen 5 with red, blue, and green phosphors arranged in sections.
has been established. A shadow mask 6 having a large number of electron beam passage holes is disposed close to and facing the phosphor screen 5. This shadow mask 6 is attached to a frame 7 via a fastener 8, and an inner shield 9 is attached to the frame 7 to block the influence of V magnetism.

However, in a picture tube configured in this way, the mask 6
The light passes through the apertures and hits the fluorescent screen 5 to generate fluorescence and form an image.

Incidentally, the shadow mask 6, frame 7, and inner shield 9 are made of rimmed steel or AJ killed steel, which has better etching and formability than before, and which is easy to form an oxide film on its surface that contributes to reducing reflection of electron beams. It is made of steel or other materials. However, in order to respond to various new media these days, there is a demand for higher quality picture tubes, that is, so-called easy-to-see and ultra-fine display images, and shadow masks 6 made of the above-mentioned rimmed steel or AI2 killed steel are required. , the use of the frame 7 and the inner shield 9 has caused problems.

That is, during operation of the picture tube, the temperature of each of the above members is 3.
The temperature rises to 0 to 100°C, for example, due to distortion of the molded shape of the shadow mask due to thermal expansion.
So-called doming occurs. As a result, a deviation occurs in the relative positional relationship between the shadow mask and the phosphor screen, resulting in a color shift called purity drift (PD). In particular, in high-quality picture tubes, since the aperture diameter and the aperture pitch of the shadow mask are very small, the relative deviation ratio becomes large, and the inner parts of the tube are made of the above-mentioned rimmed steel or Al-killed steel. This would make it impractical for practical use.

In particular, the above-mentioned problems have occurred particularly with high-curvature picture tubes that reduce image distortion and reflection of external light.

Therefore, conventionally, the materials used to form this type of pipe internal parts were
Ni-Fe alloys with a small coefficient of thermal expansion, such as ant<
-(36N i-F e) has been proposed, for example, in Japanese Patent Publication Nos. 42-25446, 58977-1980, 68650-1980, and the like. However, even with this type of Fe--Ni alloy, its temperature rises due to the impact of electrons, causing color shift, and there is a limit to the ability to improve the quality of picture tubes.

[Purpose of the Invention] The present invention has been made in consideration of these circumstances, and its purpose is to provide a bright, high-quality image with little color shift, ultra-fine, high-contrast, flat, and easy-to-see images. An object of the present invention is to provide a picture tube that can obtain images with a simplified structure.

[Summary of the Invention] The present invention provides a method in which a shadow mask is held flat so that a constant stress is applied at room temperature (20° C.), and a phosphor screen provided on the face portion of the glass envelope and its inner surface is flat. It is characterized by being formed in

As long as there is a temperature range, there is a limit to suppressing the dimensional variation due to thermal expansion to zero. Therefore, in the present invention, the dimensional variation due to the thermal expansion and the total strain change due to the variation of stress acting on the material are suppressed by t[l. This suppresses dimensional fluctuations due to temperature to almost zero.

That is, it is considered that stress σ is now acting in the longitudinal direction of the shadow mask plate in a −-like manner. When 2°C is the standard, the longitudinal dimension variation ε of the shadow mask at the temperature T is: ε-''L-α(TTo)+Lni...(
1) It can be expressed as ρ. Here, Δi is the amount of dimensional variation, i is the longitudinal length of the shadow mask, α is the linear expansion coefficient of the shadow mask M at the temperature T, To-20° C., and E is the elastic modulus at 1 m degree T. That is, the first term on the right side of equation (1) is the dimensional variation due to thermal expansion, and the second term is the strain due to stress σ. Therefore, by canceling out the dimensional increase due to temperature rise in the first term on the right side of equation (1) and the strain reduction due to stress reduction in the second term, ε in equation (1) can be kept almost constant. This makes it possible to suppress dimensional fluctuations caused by temperature.

Therefore, we are now setting the normal operating temperature of the shadow mask to 20 to 90.
℃, the first term on the right side of equation (1) is the dimensional variation ET
is εT (T-20”)−0...(2)εT (T-
900)-70α...(3). Therefore, the amount of distortion Ep in the second term on the right side of equation (1) is also εP (T-20')-70α...(
4) εP (T-90')-0 (5).

Thus, the stress σ0 at T-20°C is σo-70α-・E (6
).

In other words, tension may be applied in the longitudinal direction of the shadow mask and, if necessary, in the perpendicular direction so that the dimensional variation due to thermal expansion considered at the normal operating temperature is given as distortion at the lowest temperature. In the present invention, by applying tension to the shadow mask and fixing it flat, it is possible to suppress displacement such as displacement of the electron beam passage hole due to thermal expansion of the shadow mask, thereby reducing color shift. , you can obtain ultra-detailed, bright, high-quality images.

In the present invention, the material of the shadow mask is not particularly limited, but it is preferable to use an alloy such as amber, which has a small coefficient of thermal expansion, and it is more preferable to use a constant modulus alloy. Examples of such constant modulus alloys include:
Fe is the main component, and N is 30% or more and 45% or less by weight.
Examples include Fe-Ni-Cr constant modulus alloys having a composition containing i and 3% or more and 15% or less of Cr, and having a thermoelastic coefficient of λ within the range of ±70 x 10-6/"C. , furthermore, Ti of 0.5% or more and 4% or less in weight ratio,
AJ of 0.1% or more and 3% or less, C of 1% or less C0 of less than 15%, Mo of 12% or less, W of 5% or less, Mn of 4% or less, St of 3% or less, Be of 2% or less, 0 .5% or less Cu, 2% or less Zr.

Examples include constant modulus alloys having a composition in which at least one type of S is added in an amount of 0.1% or less. Note that the thermoelastic coefficient, usually expressed as TEC, is the sum of the temperature change rate e of the elastic coefficient E and the thermal expansion coefficient α, and is expressed by the following equation.

TEC San 2 (e+α) However. −Δl ρ ΔT Δ E E Δ T A constant elastic alloy has T
The two major characteristics are that the EC is approximately zero (less than ±20 x 10-6/''C), the elastic modulus remains unchanged even when the temperature rises, and it elongates when a tensile force is applied. Therefore, if we consider the above equation (1) only for constant modulus alloys, the first term on the right side of equation (1), which is the increase in size due to the temperature increase, and the second term, which is the decrease in strain due to the decrease in stress, are both: This is a linear change.In other words, if the above-mentioned increases and decreases are made the same, ε in equation (1) can be kept constant and dimensional fluctuations caused by temperature can be suppressed.

In addition, in the present invention, as mentioned above, since the shadow mask is fixed flat by applying tension, it is possible to use any metal or alloy as the material of the shadow mask, not only the constant elastic alloy mentioned above, but the thermal expansion of the shadow mask will be prevented. The effect of the present invention can be achieved by canceling out the dimensional variation due to the reduction in strain due to the stress reduction. In particular, by using alloys such as amber, which have a small coefficient of thermal expansion, it is possible to suppress dimensional fluctuations caused by temperature to a level that does not pose a practical problem even in high-quality picture tubes. You can get high quality images.

Furthermore, in the present invention, - in order to obtain an image with high layer quality,
Both the face portion of the glass envelope and the fluorescent screen provided on its inner surface are formed flat. By having the picture tube of the present invention configured in this manner, a flat screen is formed on the fluorescent screen during operation. Therefore, it is possible to suppress the curvature of straight-line images, which was a problem with conventional picture tubes in which the face of the glass envelope and the phosphor screen were curved, resulting in extremely high quality images that have high contrast and are flat and easy to see. You can get a good image.

Note that the shadow mask according to the present invention is manufactured, for example, as follows.

The thickness of the hot-rolled material made of the desired alloy is 50%.
The above is preferably cold rolled at a rolling ratio of about 70 to 95%, and then rolled at a high temperature above the recrystallization temperature, preferably 800%.
Annealing is performed at a temperature of 0.degree. C. or higher to obtain a mesh shadow mask material. Next, smooth it with a leveler or roll at a rolling rate of 40%.
Preferably, when manufactured as described above, in the manufacturing process, the crystal plane of the surface portion is 0.3 as an F value of (100).
5 or more, preferably 0.42 or more, resulting in extremely excellent etching properties.

In the shadow mask of the present invention, a black oxide film may be formed on the surface by steam oxidation or the like in order to radiate radiant heat and lower the PD value.

[Effects of the Invention] Thus, in the picture tube of the present invention, by applying tension to the shadow mask and fixing it flat, the image can be bright, extremely fine, and of high quality. Furthermore, it is possible to effectively obtain an image with little color shift even at the four corners of the screen, and it is possible to suppress color change even in a white image that lasts for a long time. Furthermore, in the picture tube of the present invention, by forming the face portion of the glass envelope and the phosphor screen provided on its inner surface flat, the resulting screen is flat, the curvature of the straight image can be suppressed, and the image is bright and contrasty. This is effective in displaying images with high quality. On the other hand, because its strength is high, it does not cause vibrations caused by low-frequency sound waves from speakers placed close to each other, and has the advantage of being able to withstand mechanical shocks and other effects, resulting in images without fluctuations. is played.

Furthermore, this effect can be achieved by an extremely simple method of applying tension to the shadow mask and fixing it. With this configuration, there is no variation due to thermal expansion, so the bimetal used conventionally is unnecessary.

Therefore, the structure of the picture tube becomes simple. Furthermore, in connection with this, high mounting accuracy of the shadow mask can be ensured. On the other hand, since there is almost no dimensional variation due to temperature changes in the shadow mask, it is possible to provide a picture tube with stable image quality.

[Embodiments of the invention] Next, examples of the present invention will be described.

[Example-1] First, 43vt% Ni and Fe are the main components, and Cr is 5vt%.
An ingot of a constant modulus alloy containing 3vt% of Ti was prepared, and this ingot was hot forged at 1250"c.
Hot rolled at 100℃, then rolled twice to 0,8
A ribbon with a thickness of ta11 was formed, brightly annealed in hydrogen at 1050°C, further cold rolled at a rolling reduction of 80% to obtain a ribbon with a thickness of 0.16+n, and further brightly annealed in hydrogen at 1000°C for final adjustment rolling. A shadow mask material having a thickness of 0.13 mm and a thermoelastic coefficient of -6JX 10-6 was obtained by final annealing at 620°C.

Thereafter, a photoresist was applied to this plate, and after drying, a film having a slot or dont-shaped reference pattern formed on both sides was brought into close contact with the photoresist, and the photoresist was exposed and developed.

By this development, the unexposed portions of the photoresist are removed. Thereafter, the remaining photoresist was hardened by burning, and then etched with a ferric chloride solution, and then the remaining resist was removed with a hot alkali to produce a shadow mask.

After that, the flat mask was washed, sheared, and annealed at 1000°C at 10'''torr.
I pressed it and got a shadow mask.

” - Princess, the coefficient of thermal expansion of the alloy is α-7,5X 10-6'
There is a tr. Now, the length of the shadow mask in the longitudinal direction is 44-3
00III, the dimensional variation due to thermal expansion between T-20 and 90°C is Δ! is based on equation (3), Δ J−
70 conflicts α・R−0,1511 [ms]. Therefore, after attaching the shadow mask to the glass envelope of the picture tube, tension is applied to the shadow mask so that at 20'C, a distortion of about 0.158 mm occurs. As a color television picture tube structure that allows such an attachment method, for example, the structure shown in FIGS. 2 to 4 can be considered.

In FIGS. 2 to 4, the color television picture tube 20 is
It has a structure in which both short sides of the shadow mask 21 are supported by supporting means 22. The supporting means 22 layer includes a mounting base 24 fixed to the inner surface VC of the glass envelope 23 at three locations at the top, middle and bottom, and the shadow mask 2.
1, and bolts 28 that connect both the mounting base 24 and the support frame 25. The face portion of the glass envelope 23 is formed flat as shown in FIG. Further, the support frame 25 has a shape in which a tube body having a rectangular cross section is provided with one slit in the longitudinal direction. The shadow mask 21 is supported by the support frame 25 with both short sides pressed into a hook shape accommodated inside the tube through the slits of the support frame 25.

In the color television picture tube configured in this way, the amount of distortion described above can be applied to the shadow mask 21 by appropriately adjusting the degree of tightening of the bolts 26.

By the way, the stress σ0 that acts on the shadow mask due to the amount of distortion of the 0.158 fin mentioned above is σo = 70 from equation (4).
α・E ”” 70 X 7.5X 10 =X 1800
0-9.45 [kg/aA]. Since this value is sufficiently lower than the maximum allowable stress of 127 kg/rMA for the constant elastic alloy having the above-mentioned composition, no plastic deformation occurs.

According to this embodiment described above, there is no change in dimension in the longitudinal direction due to temperature rise of the shadow mask.

Therefore, it is possible to fully exhibit the effects described above. Needless to say, this can be similarly applied to other picture tubes.

After applying red, blue, and green phosphors, AJ vapor deposition, and DAG coating, attach the inner shield. Connect this panel to the funnel at the rear of the glass envelope with the electron gun, evacuate the inside, and receive the image. I made a tube.

Note that in this embodiment, a description of the dimensional variation in the vertical direction of the shadow mask is omitted, but if the idea of the present invention is developed, it is possible to similarly suppress the dimensional variation in the four directions of the top, bottom, left, and right.

Furthermore, the shadow mask support means 22 described above is not particularly limited to this type. That is, various modifications can be considered as long as the structure allows the shadow mask to be fixed and attached at a constant length.

[Example 2] An ingot of a constant modulus alloy containing 36 wt% Ni and Fe as main components and 9 wt% Cr was used to obtain a shadow mask, and a color picture tube was completed using this shadow mask.

[Example-3] Main components are 42vt% Ni and Fe, 5vt% of C, 1.0wt% of Ti, 5wt% of A II O,
A flat mask was manufactured in the same manner as in [Example 1] using an ingot of a constant modulus alloy containing 1.5 vt% Zr and 1 wt% Co. Then heat this flat mask to 1000℃.
Hydrogen annealing was performed to obtain a shadow mask, which was used to complete a color picture tube.

[Example 4] A flat mask was manufactured in the same manner as [Example 1] using an amber ingot consisting of 36 vt% Ni and the balance Fe. Then, this flat mask was hydrogen-annealed at 1150''c to obtain a shadow mask, which was used to complete a color picture tube.

[Example 5] Using an ingot of Al guild steel, this flat mask was hydrogen-annealed at 950° C. to obtain a shadow mask, which was used to complete a color picture tube.

As a result of examining the PD values at the four corners of each of the color picture tubes of Examples 1 to 5 obtained in this way, it was found that the conventional ones were about 120 to 13 Vμm.
In Examples 1 to 3, the diameter was approximately 20 μm, and in Example 4.
5 also showed a small value of about 25 μm. Furthermore, the time from the occurrence of PD to the return to the original normal state was about half (about 2 minutes and 30 seconds) compared to the conventional case. In addition, a bright, high-quality image with no color shift, extremely fine detail, high contrast, and a flat, easy-to-see image was obtained across the entire screen.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the structure of a conventional picture tube, FIG. 2 is a partially cutaway perspective view of a picture tube according to an embodiment of the present invention, and FIG. 3 is a direction B in FIG. A schematic cross-sectional view of the same as seen from
FIG. 4 is a sectional view showing the 0 part of FIG. 3 in detail. 2...Electron gun 7...Frame 8...
Inner shield 3.21...Shadow mask 1.23...Glass envelope 20...Color television picture tube

Claims (1)

[Claims] A glass envelope that maintains a vacuum inside and has a phosphor screen on the inner surface of its face that forms a screen during operation, and an electron beam that is placed inside the glass envelope and irradiates the phosphor screen. a shadow mask disposed within the glass envelope to face the phosphor screen;
In the picture tube, the picture tube includes support means for fixedly supporting the shadow mask inside the glass envelope, wherein the support means flattens the shadow mask while applying tension from the inside of the shadow mask toward the ends. 1. A picture tube, characterized in that the face of the glass envelope is formed flat.