JPH04359832A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent a shadow mask structure after completion from generation of such welding stresses and complicated residual strain as to cause irregular deformation when it is put, in practical service, even through the periphery of the shadow mask is welded fast to a mask frame in continuity to a certain degree, and preclude deterioration of the chromatic purity. CONSTITUTION:Outside of the scheduled position where a shadow mask is to be linearly welded to a mask frame 5. a work 6 for shadow mask provided with a plurality of parallel slits 6b stretching in the direction approx. perpendicular to this scheduled line for welding is welded fast to the mask frame 5 in this position of scheduled line 6a while the work is held being pulled with a uniform tension in the direction perpendicular to tone scheduled line 6a in a position outermore than the parallel slits 6b, and then slitted portions outside of the welding lines on the work are cut away. Thus a stretched-over type shadow mask structure is completed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention enables good welding to be easily performed without causing wrinkles at the welding point between the shadow mask and the mask frame, and allows the shadow mask of a completed color cathode ray tube to be welded without any complications caused by welding. This invention relates to a color cathode ray tube in which no residual stress remains.

0002

[Prior Art] In a shadow mask type color cathode ray tube,
The electron beam for a specific color that passes through a specific hole or slit in the shadow mask strikes a dot or stripe of phosphor of a specific color precisely at a specific position on the phosphor surface.
It must be excited to emit light. However, about 15 to 25% of the electrons emitted from the electron gun pass through the shadow mask opening and are useful for displaying an image on the fluorescent surface, and most of the remaining electrons pass through the shadow mask. It just hits and heats up the shadow mask. Shadow masks made of common materials, such as mild steel, naturally expand when heated and the temperature increases. If there is a very bright part in the displayed image, the area near the corresponding shadow mask opening is also hit by the high current density electron beam and heated to a high temperature, causing significant thermal expansion. In a normal shadow mask, if there is a part that undergoes particularly large thermal expansion, the part will be deformed protrudingly and the electron beam passing through the opening in the vicinity will not be able to hit the specific spot on the phosphor surface that is supposed to hit. The light will no longer strike only the phosphor, but will also strike the adjacent phosphor of another color to emit light, resulting in a deterioration in color purity.

Various countermeasures have been proposed for the above-mentioned deterioration of color purity, but one of them is to fix the shadow mask to the mask frame with tension applied in advance, and to reduce the tension due to thermal expansion of the shadow mask. There is a plan to absorb the deformation. In order to apply tension to the shadow mask and fix it to the mask frame, for example,
Japanese Patent No. 9-167936 discloses a technique for attaching an elongated shadow mask to a mask frame that has been compressed by applying pressure from the sides toward the center. This publication states that when spot welding the shadow mask and the mask frame at multiple locations, if welding is performed continuously on the same area of the shadow mask, the shadow mask will become distorted due to the heat generated by welding, so this should be prevented. Therefore, it states that it is best to weld the area around the shadow mask to the mask frame by welding. Skip welding means first welding the first point on each of the four sides of the frame, then returning to the second point on the four sides, and repeating this process to complete the entire welding process. That's what I'm saying.

However, although the inventor of the present invention tried the above method, it was difficult to effectively suppress the occurrence of distortion. That is, wrinkles remained in the shadow mask at the end of welding, making it difficult to completely remove the distortion. As a result, the tension of the shadow mask was no longer constant, and irregular deformation occurred due to heating and expansion of the shadow mask by the electron beam, resulting in a phenomenon of color purity deterioration.

[0005]

Problem to be Solved by the Invention The present invention solves the above-mentioned conventional problems, and even if the periphery of the shadow mask is welded and fixed to the mask frame at a number of points or continuous lines, the color cathode rays after completion cannot be easily removed. To provide a color cathode ray tube in which stress caused by welding and complicated welding distortion that cause irregular deformation in the shadow mask of the tube during actual use do not remain.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a color cathode ray tube in which a shadow mask is supported by welding the periphery to a mask frame while tension is applied to the shadow mask. A shadow mask original plate is used in which a plurality of slits extending outward in a direction approximately perpendicular to the welding line are arranged in parallel on the outside of the planned linear welding position of the shadow mask with the mask frame. After welding the shadow mask original plate to the mask frame at the position of the welding line while pulling and holding it with uniform tension in the direction perpendicular to the welding line further outside the welding line, I decided to separate it.

[0007]

[Operation] Generally, when a shadow mask original plate is welded and fixed to a mask frame at a number of adjacent welding points or a continuous welding line, the welding area is Stress and strain occur in the shadow mask and its vicinity, and the completed shadow mask structure does not have a constant residual tension as desired, and as a result, the shadow mask deforms as the temperature rises during use. Deterioration of color purity begins to occur. Welding increases the temperature of both the shadow mask and the mask frame, but in general, a tension type shadow mask structure uses a shadow mask made of thin material and a relatively strong mask frame that can withstand tension. , the shadow mask is better when considering the heat conduction and cooling of the plate material.
The heat capacity near the weld is small and expands easily. The parts that are heated by the heat of welding tend to expand, but the colder parts that are a little further away are not expanding, so they try to stop that expansion. As with conventional shadow mask structures, the inside of the weld line has many holes and slits arranged to allow the electron beam to pass through, whereas the outside has no such holes and generally has a large heat capacity. When the tool is firmly clamped and an outward tension is applied to the tool, the above-mentioned stress for preventing thermal expansion acts mainly from the outside. By sequentially welding the shadow mask and mask frame along the planned welding line,
Strain due to the heat of welding gradually accumulates along this line, and at the same time the stress for preventing thermal expansion increases, and when this stress exceeds a certain level, deformations such as wrinkles and circular warts occur in the weld. After the stress is relieved, the same process as above is likely to be repeated. On the other hand, if a shadow mask original plate in which multiple slits are arranged in parallel outside the welding line according to the present invention is used, the thermal expansion prevention stress acting from the inside and outside of the welding line is almost balanced, and this stress Even if stress remains because it is absorbed by the deformation of openings, slits, etc. near the weld line, it is limited to the very vicinity of the weld line, and deformations such as wrinkles and warts do not occur in the weld area. It also appears that stress absorption occurs near the welded area due to plastic deformation in a high-temperature softened state. According to the present invention, although the reason is not clear, experimentally,
Deformations such as wrinkles and warts that impede good welding do not appear, and when the shadow mask is heated and the temperature rises in practical conditions, no deterioration in color purity due to the deformation is observed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic side sectional view of a color cathode ray tube for television image reception equipped with a shadow mask structure according to the present invention. In the figure, 1 is a panel, 2 is a panel skirt part, 3 is a stud embedded in the panel skirt for supporting the shadow mask structure, and 4 is a hole at one end that engages with the stud 3 to support the shadow mask structure. 5 is a mask frame, 61 is a shadow mask, 7 is an electron gun, 8 is an electron beam, 9 is a deflection coil, 10 is a color fluorescent surface, and 11 is a panel. This is the face plate. The shadow mask 61 is made of a relatively thin mild steel plate and is welded and fixed to the mask frame under tension, and has a width of 0.0 mm extending in the vertical direction of the display screen.
Slit holes of 75 mm are arranged on the entire surface at a pitch of 0.3 mm. Three electrons are emitted from dedicated red, green, and blue electron guns 7 arranged on one plane with a mutual spacing of 5.5 mm so that they are concentrated at the center of the inner surface of the face plate 11 in the non-deflected state. The beam 8 is transmitted over the entire surface of the color phosphor surface 10 by a deflection coil 9, passing each horizontal scanning line one by one along the three primary color phosphors constituting each pixel from left to right. A television screen is displayed by being deflected so as to repeat a horizontal scan in which light is emitted and a vertical scan in which the light is sequentially moved vertically from top to bottom.

Next, a method of manufacturing a shadow mask structure for a color cathode ray tube according to the present invention will be explained with reference to FIG. First, the mask frame 5 is fixed in position and a pressure 12 is applied uniformly distributed from the outside to the inside along its long sides. Then, the shadow mask original plate was expanded so that the planned welding line 6a of the shadow mask original plate 6 coincided with the planned welding line position of the mask frame 5 (that is, the plurality of slits 6b of the shadow mask original plate 6 were aligned with the planned welding line). The outside of the portions arranged in parallel in the perpendicular direction is placed in a state (not shown), which is clamped and pulled by a tool. Here, in the shadow mask original plate 6, a shadow mask 61 in which slits for passing the electron beam are arranged is formed inside the planned welding line 6a, and a shadow mask 61 having slits for passing the electron beam is formed outside the planned welding line 6a, and a shadow mask 61 is formed on the outside of the planned welding line 6a. A plurality of slits 6b extending outward in the direction are arranged in parallel. Note that at this time, the shadow mask original plate 6 may be heated or may be left at room temperature. In this state, the shadow mask original plate 6 and the mask frame 5 are welded and fixed together by laser welding or resistance welding along the planned welding line 6b shown in broken lines. Next, the shadow mask original plate 6 is irradiated with a laser beam substantially along the outer shape of the mask frame 5 to cut, separate, and remove unnecessary portions where the slits 6b are arranged in parallel. Finally, by removing the pressure 12 that was pressurizing the frame 5 from the outside to the inside, a stretched shadow mask structure is completed.

Shadow mask original plate 6 used in this example
was a mild steel plate with a thickness of 0.025 mm, the width of the slit 6b was 0.3 mm, the length was 100 mm, the interval between the slits was 10 mm, and the distance from the planned welding line 6a was 4 mm. These should be selected appropriately depending on the size of the shadow mask to be manufactured and the thickness of the shadow mask original plate, but the size is 20 inches and the plate thickness is 0.025 m.
m, the width of the slit is 0.025mm or more, 5mm
The following are appropriate. If it is narrower than 0.025 mm, distortion absorption will be insufficient, and if it is wider than 5 mm, the strength of the shadow mask original plate itself will decrease, making it difficult to handle. In addition, if the length of the slit is 30 mm or more, almost sufficient effect can be obtained, but if the slit is too long, the length of the shadow mask original plate 6 will become too long, which will cause problems in productivity.
It is better to make it 200mm or less. The spacing between the slits is 10
Effects can be obtained even with a thickness of about 0mm, but generally 30mm
It is better to do the following. The shorter the distance between the end of the slit and the planned mask welding line 6a, the greater the effect, but as long as it is 20 mm or less, there is almost no problem.

By providing the slit 6b as described above in the shadow mask original plate 6, it is possible to suppress the accumulation of stress near the welding line of the shadow mask that occurs when welding the shadow mask original plate 6 and the frame 5, and the shadow mask 61 A shadow mask structure is obtained in which a uniform tension is applied to the main body portion.

In the above embodiment, the shadow mask was flat, but the same effect can be obtained even if the shadow mask is cylindrical. Further, in the above embodiment, the case where two long sides are welded is described, but the present invention brings about the same effect even when welding all four sides around the entire periphery and applying tension to the entire surface of the shadow mask.

When using a shadow mask structure of a conventional color cathode ray tube not according to the present invention, deterioration in color purity was observed at an electron beam input energy of 20 mW/cm2, whereas in the color cathode ray tube according to the present invention, deterioration in color purity was observed at an electron beam input energy of 20 mW/cm2. When a tube shadow mask structure was used, no deterioration in color purity was observed up to 55 mW/cm2.

[0014]

[Effects of the Invention] As explained above, according to the present invention, the periphery of the shadow mask is fixed to the mask frame by continuous welding (not skip welding) over a somewhat long distance at a large number of points or continuous lines. Also, it is possible to obtain a color cathode ray tube in which stress and complicated welding distortion caused by welding that cause irregular deformation in the shadow mask of the completed structure during actual use do not remain, and color purity does not deteriorate.

In a color cathode ray tube using a conventional conventional shadow mask structure, deterioration in color purity was observed at an electron beam input energy of 20 mW/cm2, whereas in a color cathode ray tube using a conventional shadow mask structure, deterioration in color purity was observed when the electron beam input energy was 20 mW/cm2. In some cases, no deterioration in color purity was observed up to 55 mW/cm2.

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view of a color cathode ray tube for television image reception equipped with a shadow mask structure according to the present invention.

FIG. 2 is a perspective view of a shadow mask original plate and a mask frame for explaining a method of manufacturing a shadow mask structure for a color cathode ray tube according to the present invention.

[Explanation of sign]

DESCRIPTION OF SYMBOLS 1... Panel, 2... Panel skirt part, 3... Stud, 4... Leaf spring, 5... Mask frame, 6...
Shadow mask original plate, 6a... Welding planned line, 6b
...Slit, 61...Shadow mask, 7...Electron gun, 8...Electron beam, 9...Deflection coil, 10...
Color fluorescent surface, 11...Panel face plate,
12...Pressure.

Claims (1)

[Claims] Claim 1: With tension applied to the shadow mask,
In a color cathode ray tube whose periphery is welded and supported by a mask frame, a slit extending outward in a direction approximately perpendicular to the planned welding line is provided outside the planned linear welding position of the shadow mask with the mask frame. A color cathode ray tube characterized by using a shadow mask original plate in which a plurality of shadow masks are arranged in parallel.