JPH07141997A - Slot type shadow mask structural body - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a shadow mask inexpensive and excellent in productivity. CONSTITUTION:A region C not welded to the middle part of a short side is provided on a frame 51 for holding a slot type shadow mask 5, and tension is applied to the slot type shadow mask to hold it. This eliminated inconvenience that tension in a lateral direction generated by a Poisson's ratio is transmitted by a bridge to make the grills of the shadow mask become not a straight line in a vertical direction as separating to right and left from a center but curve in a center direction, and inconvenience that a short side mask is displaced to cause color misconvergence with interlocking with the displacement of a mask long side caused by welding four sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask structure to be mounted on a color cathode ray tube, and more particularly to a slot type shadow mask structure capable of reproducing a high quality image by reducing landing deviation of an electron beam due to temperature change. Regarding

[0002]

2. Description of the Related Art Color cathode ray tubes are widely used as image display devices for television receivers and information terminals. The color cathode ray tube currently in practical use is a panel section with a phosphor screen formed on the inner surface and a neck section for accommodating an electron gun,
And a vacuum envelope composed of a funnel portion connecting the panel portion and the neck portion to each other, a shadow mask is arranged close to the fluorescent surface formed on the inner surface of the panel portion, and three pieces are emitted from the electron gun. Is a so-called shadow mask type color cathode ray tube which reproduces a color image by correctly landing the electron beam on the phosphors of the three colors forming the phosphor screen.

As described above, the function of the shadow mask used in this shadow mask type color cathode ray tube is that the three electron beams emitted from the electron gun are separately applied to the inner surface of the panel (image display surface). It is well known that the path of each electron beam is selectively controlled so that the phosphors of the three colors of red, blue, and green are allotted and hit (landing).

This shadow mask is generally made of iron or a thin plate of an iron-nickel alloy material having a small expansion coefficient, and has round holes, rectangular holes, or long rectangular openings continuous from the top to the bottom of the image display surface. It was opened. Less than,
A shadow mask with round holes is called a dot-type shadow mask, a shadow mask with rectangular holes is called a slot-type shadow mask, and a shadow mask with long rectangular holes continuous from the top to the bottom of the image display surface is called a grill-type shadow mask. I will decide.

Generally, the dot type shadow mask and the slot type shadow mask are often shaped spherically,
The grill type shadow mask is held in a cylindrical shape by applying a vertical tension. This type of shadow mask has a property that the electron beam collides with the shadow mask, so that the temperature rises and thermal expansion occurs.

In recent years, as the resolution of image display has increased, displacement due to thermal expansion of the shadow mask has become an obstacle.
The landing mistake of the electron beam on the phosphor occurs. To avoid this thermal expansion, the dot-shaped shadow mask and slot-shaped shadow mask that are shaped spherically use iron-nickel alloy with a small expansion coefficient as the material of the shadow mask, and the grill-type shadow mask applies tension to the shadow mask. Is being held.

However, the iron-nickel alloy is expensive, and when the grill type shadow mask is held in a cylindrical shape by applying tension in the vertical direction of the image display surface, the shadow mask is placed on the holding frame. The mechanical rigidity is required to withstand the tension, and there is a drawback that the weight becomes large. Further, in order to increase the definition of image display, it is necessary to reduce the pitch of the holes in the shadow mask and the diameter of the holes in each of the shadow mask types.

If the shadow mask material has a large thickness, it is very difficult to process it when making a small hole. Therefore, it is required to reduce the thickness. However, the dot-shaped shadow mask and the slot-shaped shadow mask, which are shaped spherically, cannot reduce the thickness of the shadow mask plate beyond a certain amount because it is necessary to maintain the shape of the shadow mask. The grill type shadow mask, which has a long rectangular hole continuous from the top to the bottom of the image display surface, cannot be reduced more than a certain thickness because the grill is entangled and deformed during production.
Therefore, it is very difficult to extend the precision of image display with the extension of the current technology.

[0009]

When a slot type shadow mask for high-definition display in which the plate thickness is made thin and small holes are formed is held by applying tension in the vertical direction of the image display surface,
The problems of the prior art described above are solved. However, another problem occurs. That is, when the slot type shadow mask is held by applying vertical tension in parallel to the grill, the horizontal tension generated by Poisson's ratio is transmitted by the bridge, and as the shadow mask grill moves away from the center to the left and right It causes a defect that it bends in the direction of.

One means for solving this has been proposed in US Pat. No. 4,973,283.
In this proposal, when the slot-type shadow mask is fixed only on the upper and lower sides and tension is applied vertically to the grill in parallel, the horizontal tension generated by the Poisson's ratio is transmitted by the bridge and the shadow mask grill moves from the center to the left and right. The problem is that the number of bridges is reduced to eliminate the inconvenience that it becomes a straight line in the vertical direction and bends toward the center as the distance increases.

An object of the present invention is to eliminate the above-mentioned problems of the prior art that occur when a slot type shadow mask is used, and to hold the slot type shadow mask in parallel with the grill by applying vertical tension. It is an object of the present invention to provide a slot-type shadow mask structure having a structure in which the grille is not straight in the vertical direction as it moves away from the center of the shadow mask in the left-right direction, and is not curved in the direction of the center.

[0012]

In order to achieve the above object, the present invention welds all of a pair of long sides of the four sides of a slotted shadow mask to a mask frame, and
It is characterized in that only a part of the pair of short sides is welded. That is, the present invention provides a collar having a slot type shadow mask structure close to a phosphor screen formed on the inner wall of the panel portion of a vacuum envelope including a panel portion, a funnel portion and a neck portion accommodating an electron gun. In the slot type shadow mask structure of the cathode ray tube, the slot type shadow mask is composed of a substantially rectangular mask frame and a slot type shadow mask fixed by applying tension between a pair of long sides of the mask frame. It is characterized in that a part of both ends of the pair of short sides of the mask which are connected to the long side are fixed to the mask frame.

[0013]

As described above, when the slot type shadow mask is fixed to the frame with only one pair of long sides thereof and is held vertically and vertically (in the vertical deflection direction) in parallel with the grill, the horizontal direction is generated by the Poisson's ratio. Is transmitted by the bridge connecting the grills, and as the grille of the shadow mask moves away from the center in the left-right direction (horizontal deflection direction), it becomes a straight line in the vertical direction and a positional displacement occurs in which it bends toward the center.

The positional displacement of the grille is caused by thermal expansion due to collision of electron beams, so that the tension is relaxed, and the landing position of the electron beam with respect to the phosphor is displaced in an attempt to return to the original position, and the adjacent phosphor is colored. I will end up. On the other hand, a slot-type shadow mask is applied with a vertical tension in parallel with the grill, and not only the upper and lower two sides (a pair of long sides) but also the left and right two sides (a pair of short sides) have a rectangular shape. When fixed to the frame, all the problems will be solved unless the frame is sufficiently rigid and is deformed by the tension of the shadow mask.

However, as described above, if the rigidity of the frame is made sufficiently large, the weight becomes large, which is not practical. The frame having a limited strength due to this weight limitation is deformed by the tension of the shadow mask. FIG. 4 is an explanatory diagram of thermal deformation of the shadow mask structure in which all the long sides and the short sides of the shadow mask are fixed to a rectangular frame.

In the figure, when a pair of long sides of the rectangular frame shown in (a) is compressed, the long sides are deformed into a pincushion shape and the short sides are deformed into a barrel shape as shown in (b). In this state, the long side and the short side of the shadow mask are welded to the long side and the short side of the frame, respectively, whereby tension is applied to the shadow mask in parallel with the grill.

Electrons collide with the shadow mask during operation of the cathode ray tube. The collision of the electrons raises the temperature of the shadow mask and causes the thermal expansion to change the tension, whereby the short side is displaced in the direction of arrow a and the long side is displaced in the direction of arrow b as shown in (c). It deforms so as to return to the original shape of (a). This deformation in the direction of the arrow a displaces the aperture position of the shadow mask and changes the landing position of the electron beam which passes through the aperture formed in the shadow mask and causes the appropriate phosphor to emit light. It causes a mistake.

In the slot type shadow mask, since the displacement parallel to the grill does not affect the landing of the electron beam, the vertical displacement is allowed, but the horizontal displacement is caused by hitting a phosphor of another color in which the electron beam is not appropriate. It emits different colors. That is, if only the upper and lower sides are welded, a problem due to the Poisson's ratio will occur, and if the four sides are welded, a problem will occur due to the deformation of the frame. Therefore, the amount of welding on the short side may be determined so that the defect due to the Poisson's ratio does not occur and the defect due to the deformation on the long side of the frame does not occur.

With the above-described structure of the present invention, the horizontal displacement of the grill when the frame is thermally deformed is suppressed, and the landing error associated with the displacement on the long side of the frame due to the Poisson's ratio can be reduced. At the same time, it is not necessary to make the rigidity of the frame extremely high.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 (a) is a front view illustrating one embodiment of a slotted shadow mask structure according to the present invention, FIG.
(B) is a side view seen from the short side, and (c) is a side view seen from the long side.

In the figure, 5 is a slot type shadow mask, 50 is a welding line, 51 is a frame (mask frame), 5a is an effective area of the shadow mask, 5b is a skirt portion of the shadow mask, and 5c is a grill. The openings (slots) and 5d are bridges that connect the grills. The grill is a portion formed by a vertically continuous iron portion that separates the upper and lower slot rows.

This slot type shadow mask 5 has a vertical length of 3
A rectangular hole 5c having a width of 0.050 mm and a length of 0.95 mm is formed on an iron plate having a length of 00 mm, a width of 400 mm, and a thickness of 0.025 mm, with a vertical pitch of 1.0 mm and a horizontal pitch of 0.25 mm.
The length is about 280 mm and the width is about 380 mm, so that it fills the surface. The frame 51 has a plate thickness of 2.3 mm, is made of ferritic stainless steel, and has a rectangular shape.

The slot type shadow mask 5 is heated in a state where the frame 51 is pressed at room temperature and the pair of long sides are compressed, and is welded and fixed to the mask frame 51 at the welding line 50. After the welding, when the shadow mask 5 cools, tension in the long side direction is applied to the grille constituting the shadow mask. In the shadow mask structure when only the upper and lower sides (long sides) of the shadow mask 1 are welded at the time of mask welding, the grille is linear as it goes to the left and right ends of the shadow mask due to the transmission of tension due to the Poisson's ratio as described above. And the tension becomes weaker.

However, in this embodiment, the central region C on the short side of the frame 51 is not welded, but the end region connected to the long side and the entire region A of the long side are welded to the frame 51. The lateral displacement due to the Poisson's ratio due to the change in the tension of the grill can be suppressed. 2 (a) is a front view for explaining another embodiment of the slotted shadow mask structure according to the present invention, FIG. 2 (b) is a side view seen from the short side, and FIG. 2 (c) is a side view seen from the long side. .

The above-described embodiment is an application of the present invention to a flat shadow mask structure, but this embodiment is directed to a so-called cylindrical shadow mask structure which is curved cylindrically in the left-right direction (horizontal deflection direction). Is applied. In the figure, reference numeral 51 'corresponds to the frame, and the same reference numerals as those in FIG. 1 correspond to the same parts. The difference from the above-mentioned embodiment is that the frame 51' for fixing the shadow mask 5 is a so-called cylindrical shape which is curved in the left-right direction into a cylindrical shape. It is only a point that is a shape.

Also in this embodiment, as in the previous embodiment, the region C of the central portion on the short side of the frame 51 'is not welded, but the end region connecting to the long side and the entire region A of the long side are framed. By welding to 51 ', the lateral displacement due to the Poisson's ratio due to the change in the tension of the grill can be suppressed. The welding area B on the short side in each of the above embodiments is preferably about 1/2 of the length of the short side, but the present invention is not limited to this, and the Poisson's ratio according to the change in the tension of the grill is preferable. The length can be set to an appropriate value depending on the magnitude of displacement in the left-right direction.

FIG. 3 is a partial cross-sectional view for explaining an example of a color cathode ray tube having a slot type shadow mask structure according to the present invention, in which 1 is a panel portion, 2 is a funnel portion,
3 is a neck portion, 4 is an electron gun, 5 is a slot type shadow mask, 51 is a frame, 52 is a magnetic shield, 6 is a fluorescent screen, 7 is a reinforcing band, 71 is an insertion sheet, 72 is a bracket, and 8 is a deflection yoke. Is.

In FIG. 1, the panel portion 1, the funnel portion 2 and the neck portion 3 constitute a vacuum envelope. An interposer sheet 7 is provided near the joint between the panel 1 and the funnel 2.
The reinforcing band 7 is fastened via 1 to enhance the mechanical strength of the vacuum envelope and prevent implosion. The bracket 72 functions as a mounting tool when the color cathode ray tube is incorporated in a television receiver or an information terminal.

The three electron beams emitted from the electron gun 4 housed in the neck portion 3 are the funnel portion 2 and the neck portion 3.
Of the phosphor screen 5 formed on the inner surface of the panel 1 by being deflected in two directions, horizontal and vertical, by the deflection yoke 8 mounted in the transition region of the panel, color-selected by the slot type shadow mask 5.
And a desired color image is generated by landing on the phosphor constituting the.

The slot type shadow mask structure comprises a frame 51 and a slot type shadow mask 5.
A magnetic shield 52 that blocks an external magnetic field is fixed to the shadow mask structure. The slot type shadow mask structure has the structure described in the above embodiment, and even if the temperature rise due to the electron beam bombardment during the operation of the cathode ray tube, the displacement of the slot is suppressed to the minimum, and therefore the phosphor Landing mistakes of the electron beam to the electron beam are reduced.

As shown in the above embodiment, the displacement of the grill on the short side due to the Poisson's ratio linked to the displacement on the long side of the frame is suppressed, and the phosphor is caused by the thermal deformation of the shadow mask structure. It is possible to reduce landing mistakes of the electron beam and achieve high quality image reproduction.

[0032]

As described above, according to the present invention,
By not welding a part of the short side of the frame that holds the shadow mask, it is possible to suppress the displacement of the grill due to the influence of the Poisson's ratio, obtain a high-quality reproduced image, and increase the frame rigidity extremely. Since it is possible to avoid an increase in weight, it is possible to produce a slot-type shadow mask structure that is inexpensive and has good mass productivity.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a slotted shadow mask structure according to the present invention.

FIG. 2 is an explanatory view of another embodiment of the slot type shadow mask structure according to the present invention.

FIG. 3 is a partial cross-sectional view illustrating an example of a color cathode-ray tube equipped with a slot-type shadow mask structure according to the present invention.

FIG. 4 is an explanatory diagram of thermal deformation of a shadow mask structure in which all long sides and short sides of a shadow mask are fixed to a rectangular frame.

[Explanation of symbols]

 1 Panel Part 2 Funnel Part 3 Neck Part 4 Electron Gun 5 Slot Type Shadow Mask 5a Shadow Mask Effective Area 5b Shadow Mask Skirt Part 5c Opening (Slot) Formed in the Grill 5d Bridge Connecting the Grilles 50 Welding Line 51 frame 52 magnetic shield 6 fluorescent screen 7 reinforcing band 71 insertion sheet 72 bracket 8 deflection yoke.

Front page continuation (72) Hideo Tanabe, Hideo Tanabe, 3300 Hayano, Mobara, Chiba, Hitachi, Ltd., Electronic Devices Division (72) Inventor, Kawasaki, Hiroshi, 3681 Hayano, Mobara, Chiba

Claims (1)

[Claims] 1. A color cathode line having a slot type shadow mask structure adjacent to a fluorescent screen formed on an inner wall of the panel portion of a vacuum envelope comprising a panel portion, a funnel portion and a neck portion accommodating an electron gun. In the slot type shadow mask structure of the tube, the slot type shadow mask is composed of a substantially rectangular mask frame and a slot type shadow mask fixed by applying tension between a pair of long sides of the mask frame. 2. A slot type shadow mask structure, wherein a part of both ends of the pair of short sides on the side connected to the long side is fixed to the mask frame.