JPH0622099B2 - Picture tube - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a picture tube using a shadow mask and having a high display image quality.

[Technical Background of the Invention and Problems Thereof] A picture tube generally has a structure shown in FIG. That is,
An electron gun 3 in an in-line arrangement, for example, is provided on the neck portion 2 that constitutes one end of the glass envelope 1.
Face portion 4 at the other end of the glass envelope 1 facing the
In addition, a phosphor screen 5 in which red, blue, and green phosphors are arranged and arranged is provided. A shadow mask 6 having a large number of electron beam passage holes is arranged to face the fluorescent screen 5 so as to face it. The shadow mask 6 is attached to a frame 7 via a locking tool 8, and an inner shield 9 is attached to the frame 7 in order to block the influence of geomagnetism.

In the picture tube thus constructed, however, the electron beam 11 emitted from the electron gun 3 is deflected by the deflection control by the deflecting device 10 provided at the base of the neck 2. An image is formed by passing through the aperture of the shadow mask 6 and striking the phosphor screen 5 to generate fluorescence.

By the way, the shadow mask 6, the frame 7, and the inner shield 9 have better etching properties and moldability than conventional ones, and are easy to form an oxide film on the surface thereof that contributes to reduction of reflection of electron beams. It is made of steel or the like. However, in order to deal with various new media in recent years, it is required to improve the quality of the picture tube, that is, the so-called readability and ultrafineness of the displayed image, and the shadow mask 6 composed of the above-mentioned rimmed steel or Al-killed steel. However, the use of the frame 7 and the inner shield 9 has a problem.

That is, when the picture tube is operating, the temperature of each member is 3
The temperature rises to 0 to 100 ° C., and so-called doming occurs due to distortion of the molding shape of the shadow mask due to its thermal expansion. As a result, the relative positional relationship between the shadow mask and the fluorescent screen is deviated, and a color misregistration called “purity drift (PD)” is generated. Particularly in a high-quality picture tube, since the aperture diameter and the aperture pitch of the shadow mask are very small, the relative deviation amount becomes large, and the above-mentioned rimmed steel or Al-killed steel pipe internal parts are used. Then it will not be practical. In particular, in a high-curvature type picture tube in which distortion of an image and reflection of external light are reduced, the above problem remarkably occurs.

Therefore, conventionally, as a material for forming this kind of in-pipe component,
Using a Ni-Fe alloy having a small coefficient of thermal expansion, for example, amber (36Ni-Fe), is disclosed in, for example, Japanese Patent Publication No.
No. 25446, JP-A-50-58977, and JP-A-5
It is proposed by No. 0-68650 and the like. However,
Even with this type of Fe-Ni alloy, the temperature rises due to electron bombardment and color misregistration occurs, and there is a limit to improving the quality of the picture tube.

[Object of the Invention] The present invention has been made in view of such circumstances, and an object of the present invention is to simplify a bright, high-quality image with little color shift, extremely fine and high contrast, and flat and easy to see. It is to provide a picture tube that can be obtained with a simplified structure.

SUMMARY OF THE INVENTION According to the present invention, a shadow mask is held flat so that a constant stress acts at room temperature (20 ° C.), and a face portion of a glass envelope and a fluorescent surface provided on the inner surface thereof are flat. It is characterized by being formed in.

That is, even if a material having a very small coefficient of linear expansion is selected as the shadow mask material, there is a limit to suppressing the dimensional variation due to thermal expansion to zero as long as the usage condition has a certain temperature range. Therefore, in the present invention, the dimensional variation due to the thermal expansion and the strain variation due to the stress acting on the material are offset. As a result, the dimensional variation due to temperature is suppressed to almost zero.

That is, now, it is considered that the stress σ is uniformly acting in the longitudinal direction of the shadow mask plate. When 20 ° C. is used as a reference, the lengthwise dimensional variation ε of the shadow mask at the temperature T is Can be expressed as Here, Δl is the amount of dimensional variation, l is the length of the shadow mask in the longitudinal direction, α is the coefficient of linear expansion of the shadow mask material at temperature T, To = 20 ° C., and E is the elastic coefficient at temperature T. That is, the first term on the right side of the equation (1) is the dimensional variation due to thermal expansion, and the second term is the strain due to the stress σ. Therefore, ε in equation (1) can be made almost constant by canceling out the dimensional increase due to temperature rise in the first term on the right side of equation (1) and the strain decrease due to stress reduction in the second term. It is possible to suppress the dimensional variation due to temperature.

Therefore, at the time of operation of the picture tube, the temperature of the shadow mask changes between 20 ° C and 90 ° C. At that time, (1)
The dimensional variation ε _T of the first term on the right side of the equation is ε _T (T = 20 °) = 0 (2) ε _T (T = 90 °) = 70α (3). Therefore, if the strain amount ε _{P of} the second term on the right side of the equation (1) is also ε _P (T = 20 °) = 70α (4) ε _P (T = 90 °) = 0 (5), No dimensional change occurs when the temperature changes by 90 ° C. At this time, the stress σ _{0 at} T = 20 ° C. is σ ₀ = 70α · E (6).

That is, so that the dimensional variation due to thermal expansion, which is considered at the operating temperature, is given as strain at the lowest temperature,
Tension may be applied in the longitudinal direction of the shadow mask and, if necessary, in the perpendicular direction so that a stress of σ ₀ ≧ 70α · E is applied. In the present invention, by applying tension to the shadow mask and fixing the shadow mask in this manner, it is possible to suppress the displacement such as the position deviation of the electron beam passage hole that accompanies the thermal expansion of the shadow mask. , You can get very fine and bright high quality images.

In the present invention, the material of such a shadow mask is not particularly limited, but an alloy such as amber having a small coefficient of thermal expansion is preferably used, and a homoelastic alloy is more preferably used. As such a constant elasticity alloy, for example,
As a main component of Fe, 30% or more and 45% or less by weight of N
Examples of the Fe-Ni-Cr-based constant elasticity alloy are i and a composition containing 3% or more and 15% or less of Cr and have a thermoelastic coefficient within a range of ± 20 × 10 ^-6 / ° C. In each case, the weight ratio of Ti is 0.5% or more and 4% or less,
0.1% or more and 3% or less Al, 1% or less C, 5% or less Co, 12% or less Mo, 5% or less W, 4% or less Mn, 3% or less Si, 2% or less Of Be, 0.5% or less of Cu, 2% or less of Zr, and 0.1% or less of S in a constant elastic alloy having a composition containing at least one of them. The thermoelastic coefficient, which is usually represented by TEC, is the sum of the temperature change rate e of the elastic coefficient E and the thermal expansion coefficient α, and is represented by the following equation.

TEC = 2 (e + α) In a constant elastic alloy, α (coefficient of thermal expansion) and e (rate of temperature change of elastic coefficient) are positive and negative, which cancel each other
Since the EC becomes a value of approximately zero (± 20 × 10 ⁻⁶ / ° C. or less), the elastic modulus does not change even when the temperature rises, and the elongation length does not change when a tensile force is applied. This constant elastic alloy has two major characteristics that the temperature change rate of the elastic coefficient having a small thermal expansion coefficient is substantially zero. Therefore, if the above equation (1) is considered to be a constant elastic alloy, both the dimensional increase due to the temperature increase in the first term on the right side of the equation (1) and the strain reduction due to the stress reduction in the second term are linear changes. In other words, if the degree of increase and decrease are the same, ε in equation (1) can be kept constant and dimensional variation due to temperature can be suppressed.

In the present invention, since the shadow mask is fixed flat by applying tension as described above, the thermal expansion of the shadow mask is not limited to the above-mentioned constant elastic alloy, and any metal or alloy may be used as the material of the shadow mask. The dimensional variation due to the stress can be offset by the strain due to the stress reduction, and the effect of the present invention can be achieved. In particular, if an alloy such as Amber with a small coefficient of thermal expansion is used, the dimensional variation due to temperature can be suppressed even during high-quality image reception to such an extent that it does not pose a problem in practice, and there is little color misregistration and it is extremely fine and bright. It is possible to obtain a clear image.

Furthermore, in the present invention, in order to obtain a higher quality image,
The face portion of the glass envelope and the fluorescent surface provided on the inner surface thereof are both formed flat. With such a configuration in the picture tube of the present invention, a flat screen is formed on the phosphor screen during operation. Therefore, it is possible to prevent the straight image from being curved, which is a problem in the conventional picture tube in which the face portion and the fluorescent surface of the glass envelope are of a curvature type, and the contrast is high, and the flat and easy-to-see image is extremely high quality. It is possible to obtain a clear image.

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

50% of thickness after hot rolling of material made of desired alloy
As described above, cold rolling is performed at a rolling ratio of preferably about 70 to 95%, and then a high temperature of recrystallization temperature or higher, preferably 800
Annealing is performed at a temperature of ℃ or more to obtain a shadow mask material. Next, after smoothing with a leveler or adjusting rolling with a rolling rate of 40% or less, preferably 5% or less, electron beam passage holes are opened by a normal photoetching method.

When manufactured as described above, in the manufacturing process, the crystal plane of the surface part has an F value of (100) of 0.35 or more, preferably
It is 0.42 or more, and as a result, the etching property and the like are extremely excellent.

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 reduce 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 made bright and can be of extremely fine quality. Moreover, 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 for a white image for a long time. Further, in the picture tube of the present invention, the face portion of the glass envelope and the fluorescent surface provided on the inner surface thereof are formed flat, so that the obtained screen is flat and the bending of the linear image can be suppressed, resulting in a bright contrast. Effective for displaying high-quality images. on the other hand,
Since its strength is also high, it does not cause vibrations due to low frequency sound waves from closely arranged speakers, and has the effect that it can withstand mechanical shocks, etc., and obtain so-called fluctuation-free images. Sent.

Further, the effect can be realized by an extremely simple method of applying tension to the shadow mask to fix it. With this structure, since there is no fluctuation due to thermal expansion, the conventionally used bimetal is unnecessary.
Therefore, the structure of the picture tube is simplified. Further, along with this, a high mounting accuracy of the shadow mask can be secured. On the other hand, since there is almost no dimensional change due to temperature change of the shadow mask, a picture tube with stable image quality can be provided.

Embodiments of the Invention Next, embodiments of the present invention will be described.

[Example-1] First, an ingot of a constant elasticity alloy containing 43 wt% Ni and Fe as main components, containing 5 wt% of Cr and containing 3 wt% of Ti was prepared, and this ingot was hot cast at 1250 ° C, 1100 ° C. Hot-rolled at 0, then rolled twice to make a ribbon of 0.8mm thickness, 10
Bright annealing in hydrogen at 50 ℃, cold rolling with a reduction rate of 80% to obtain a strip with a thickness of 0.16 mm, further bright anneal in hydrogen at 1000 ℃ and final adjustment rolling and final annealing at 620 ℃ to 0.13 mm. A shadow mask material having a thickness of mm and a thermoelastic coefficient of −6.3 × 10 ⁻⁶ was obtained.

Thereafter, a photoresist was applied to the plate material, dried, and then a film having a slot or dot-shaped reference pattern formed on both surfaces thereof was brought into close contact with the plate material to expose and develop the photoresist. By this development, the photoresist in the unexposed portion is dissolved and removed. However, after burning and curing the remaining photoresist,
An etching treatment was carried out with a ferric chloride solution, and then the remaining resist was removed with hot alkali to prepare a shadow mask.

Then, the flat mask was washed, sheared, annealed at 10 ⁻⁴ torr and 1000 ° C., and pressed to obtain a shadow mask.

The coefficient of thermal expansion of the above alloy is α = 7.5 × 10 ⁻⁶ .
Now, assuming that the length of the shadow mask in the longitudinal direction is l = 300 mm, the dimensional variation Δl due to thermal expansion between T = 20 to 90 ° C. is based on the equation (3), and Δl = 70 · α · l = 0. It becomes 158 [mm]. Then, after attaching the shadow mask to the glass envelope of the picture tube, tension is applied to the shadow mask so that a distortion of about 0.158 mm occurs at 20 ° C. As a structure of a color television picture tube that enables such a mounting method, for example, the structure shown in FIGS. 2 to 4 can be considered. 2 to 4, the color television picture tube 20 has a structure in which both short sides of a shadow mask 21 are supported by supporting means 22. Support means 22
Is a mounting base 24 fixedly attached to the inner side wall of the glass envelope 23 at three places, upper, middle and lower, a support frame 25 for sandwiching both short sides of the shadow mask 21 over the whole, and the mounting base 24. ,
It is composed of a bolt 26 that connects both of the support frames 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 slit having a rectangular cross section is provided in the longitudinal direction. Then, the shadow mask 21
The two short sides press-formed into a hook shape are accommodated in the tubular body through the slits of the support frame 25 and supported by the support frame 25.

In the color television picture tube configured as described above, the amount of distortion described above is applied to the shadow mask 21 by appropriately adjusting the degree of tightening of the bolt 26.

By the way, the stress σ ₀ acting on the shadow mask due to the strain of 0.158 mm is σ ₀ = 70α · E = 70 × 7.5 × 10 ⁻⁶ × 18000 = 9.45 [kg / mm ² ] Becomes This is a number sufficiently lower than the maximum allowable stress of 127 kg / mm ² of the homoelastic alloy having the above-mentioned composition, so that it is not plastically deformed.

According to the present embodiment described above, there is no dimensional change in the longitudinal direction due to the temperature rise of the shadow mask. Therefore, it is possible to sufficiently exert the effects described above. It goes without saying that this can be similarly applied to other picture tubes.

As usual, the phosphor screen is formed by coating red, blue, and green phosphors on the inner surface of the face part of the glass envelope in accordance with the electron beam passage hole of the shadow mask, and then depositing the Al and doggling the inner shield. A funnel at the rear of the glass envelope with an attached electron gun was connected to this panel, and the interior was evacuated to produce a picture tube.

In the present embodiment, the description of the dimensional variation of the shadow mask in the vertical direction is omitted, but if the concept of the present invention is developed, the dimensional variation in the four vertical and horizontal directions can be similarly suppressed.

Further, the above-mentioned shadow mask supporting means 22 is not particularly limited to this type. That is, various modifications are conceivable as long as the structure is such that the shadow mask is fixed and attached to a fixed length.

[Example-2] 36 wt% Ni and Fe as main components and 9 wt% of Cr,
A flat mask was produced in the same manner as in [Example-1] using an ingot of a constant elasticity alloy. Then, this flat mask was annealed with hydrogen at 1100 ° C. to obtain a shadow mask, and this was used to complete a color picture tube.

Example 3 42 wt% Ni and Fe as main components, 5 wt% of Cr, T
i is 1.0 wt%, Al 0.5 wt%, Zr 1.5 wt%, C
A flat mask was produced in the same manner as in [Example 1] using an ingot of a homoelastic alloy containing 1 wt% of o. Then, this flat mask was annealed with hydrogen at 1000 ° C. to obtain a shadow mask, and using this, a color picture tube was completed.

[Example-4] A flat mask was manufactured in the same manner as in [Example-1] using an amber ingot composed of 36 wtNi and the balance Fe. Then, this flat mask was annealed with hydrogen at 1150 ° C. to obtain a shadow mask, and this was used to complete a color picture tube.

[Example-5] A flat mask was manufactured in the same manner as in [Example-1] using an ingot of Al killed steel. Then, this flat mask was annealed with hydrogen at 950 ° C. to obtain a shadow mask, and this was used to complete a color picture tube.

With respect to each of the color picture tubes of Examples 1 to 5 thus obtained, as a result of examining the PD values at the four corners, the conventional one was about 120 to 130 μm.
In each of Examples 1 to 3, about 20 μm, Example 4,
No. 5 also showed a small value of about 25 μm. Further, the time from the occurrence of PD to the return to the original normal state was about half (about 2 minutes and 30 seconds) as compared with the conventional case. In addition, it was possible to obtain a bright, high-quality image that was flat, easy to see, and had a fine contrast with no color shift and high contrast throughout the entire screen.

[Brief description of drawings]

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. The same schematic sectional view seen from
FIG. 4 is a cross-sectional view showing the C portion of FIG. 3 in detail. 2 …… Electron gun, 7 …… Frame 8 …… Inner shield 3,21 …… Shadow mask 1,23 …… Glass envelope 20 …… Color TV picture tube 22 …… Supporting means, 24 …… Mounting stand 25 …… Support frame, 26 …… Bolt

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) The inventor, Shoji Kanto, 50, Kamimayube, Yobu Ward, Himeji City, Hyogo Prefecture Inside the Himeji Plant, Toshiba Corporation (56) References JP-A-53-47266 (JP, A)

Claims (1)

[Claims] 1. A glass envelope in which a fluorescent surface for maintaining a vacuum inside and a screen is formed during operation is provided inside the face, and a glass envelope disposed inside the glass envelope toward the fluorescent screen. An electron gun for irradiating an electron beam, a shadow mask arranged in the glass envelope so as to face the phosphor screen, and the shadow mask is provided inside the glass envelope from an end of the shadow mask. In the picture tube having a supporting means for flatly fixing and supporting the film while applying a tension toward, the stress σ applied to the shadow mask in the tensioned direction at 20 ° C. is σ ≦ 70α · E (1) (Where α is the coefficient of linear thermal expansion of the shadow mask material at 90 ° C. and E is the elastic coefficient of the shadow mask material at 90 ° C.), and the face portion of the glass envelope is flat. Picture tube, characterized by comprising a.