JP2001273856A - Color cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color cathode ray tube in which the displacement of a mask body to a panel and a mask frame can be reduced and display quality can be enhanced. SOLUTION: The shadow mask of this color cathode ray tube has a rectangular mask body 34 consisting of a nearly rectangular main plane 38 and a skirt 40 formed by bending around the main plane, and a rectangular mask frame 35 which is attached to the outside of the skirt. The skirt has an opening edge extending almost in parallel to the periphery of the main plane, plural snicks 44 extending from each opening edge towards the periphery of the main plane, and plural tabs 50 which are defined between adjacent two snicks and fixed to the inside of the mask frame, and near the upper edge of the snicks, recesses 52a, 52b extending in the direction crossing the snicks are formed the mask frame side as concave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube having a shadow mask.

[0002]

2. Description of the Related Art Generally, a color cathode ray tube has a vacuum envelope formed of glass, and the vacuum envelope has a substantially rectangular panel and a funnel joined to the panel. The panel integrally has a substantially rectangular effective portion and a frame-shaped skirt portion provided along the periphery of the effective portion and extending substantially perpendicular to the effective portion. On the inner surface of the effective portion, a phosphor screen composed of phosphor layers of three colors that emit blue, green and red light is formed.

[0003] In the vacuum envelope, a shadow mask having a large number of electron beam passage holes is arranged so as to face the phosphor screen, and in a funnel neck, three electron beams are directed toward the phosphor screen. An electron gun that emits a beam is mounted.

In the color cathode ray tube having the above structure, the three electron beams emitted from the electron gun are deflected by using a deflection yoke mounted outside the funnel, and the phosphor screen is passed through the electron beam passage hole of the shadow mask. By scanning the top horizontally and vertically, the corresponding phosphor layer is irradiated to display a color image.

In the above color cathode ray tube, a shadow mask is one of members having an important function of selecting colors of an electron beam. Such a shadow mask has a substantially rectangular mask body having a plate thickness of about 0.1 to 0.3 mm in which a large number of electron beam passage holes are formed in a main surface portion facing the effective surface of the inner surface of the panel. A substantially rectangular mask frame fixed to the periphery of the mask body.

[0006] It is desirable that the shadow mask be in a fixed position with respect to the panel and maintain its shape, and if this is not satisfied, it will have various adverse effects on the color cathode ray tube. However, in the manufacturing process of a color cathode ray tube, the shadow mask may undergo irreversible deformation before and after high heat treatment and subsequent cooling due to a difference in the coefficient of thermal expansion between the mask body and the mask frame and its fixed state, or Deformation due to impact or the like may occur.

Further, in the color cathode ray tube, the mask body and the frame are heated by the projection of the electron beam to cause thermal expansion. At this time, it should be referred to as a doming phenomenon in which the mask body locally expands due to a difference in thermal expansion between the mask body and the mask frame, or a so-called reverse doming phenomenon in which the mask body is pulled and deformed by the mask frame. A phenomenon occurs. When such a doming phenomenon occurs, the electron beam that has passed through the electron beam passage hole of the mask body does not reach the regular phosphor layer, and a color shift occurs. In order to prevent such a doming phenomenon, it is possible to form the mask body and the mask frame with a low thermal expansion material. However, in this case, there is a problem that the manufacturing cost increases.

[0008]

Generally, a mask body of a shadow mask is provided with a main surface portion having a large number of electron beam passage holes formed thereon, a peripheral portion of the main surface portion, and substantially perpendicular to the main surface portion. And a skirt portion that is bent. The mask body is attached to the mask frame by welding a plurality of portions of the skirt to the inner surface of the mask frame.

In such a shadow mask, a cut is made in the skirt portion of the mask body in the vicinity of a fixed portion fixed to the mask frame, and this fixed portion is formed as a tongue piece independent of the continuous skirt portion. Thus, the deformation of the mask body due to the thermal expansion of the mask frame described above can be partially prevented, and the effect thereof can be reduced.

However, when a mask body having a skirt as described above is formed by press molding or the like, the lower end of the skirt has a small radius of curvature. Wrinkles are generated in the vicinity of the cut portion of. Further, as described above, when the cut is provided in the skirt portion, excess material can escape to reduce the occurrence of wrinkles to some extent,
In many cases, wrinkles still remain.

When the wrinkles as described above occur at the fixed portion at the long or short axis end of the mask body, the fixed portion of the mask body, that is, the distance between the welding point and the mask frame becomes non-uniform. I will. In this case, it becomes difficult to weld the mask main body to an accurate position with respect to the mask frame, and an extra stress is applied to the welding point, so that there is a high possibility that the tongue portion is deformed. Therefore, the relative position between the mask main body and the mask frame and the position of the mask main body with respect to the panel deviate from the predetermined positions, and it becomes difficult to guide the electron beam onto the predetermined phosphor layer, which causes color shift.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a color cathode ray tube in which the displacement of a mask main body with respect to a panel and a mask frame is reduced and display quality is improved. .

[0013]

In order to achieve the above object, a color cathode ray tube according to the present invention comprises: an envelope having a face panel having a phosphor screen formed on an inner surface thereof; A shadow mask provided in the envelope, and an electron gun provided in the envelope and irradiating the phosphor screen with an electron beam through the shadow mask, wherein the shadow mask is A substantially rectangular main surface portion opposed to the phosphor screen and formed with a large number of electron beam passage holes, and a skirt portion bent around the main surface portion;
And a substantially rectangular mask frame attached to the skirt and located outside the skirt, the skirt comprising:
An open edge extending substantially parallel to the peripheral edge of the main surface portion, a plurality of cuts extending from the open edge toward the peripheral edge of the main surface portion, and between the two adjacent cuts, A plurality of tongue pieces fixed to the inner surface of the mask frame, the position of the end of the notch on the main surface side,
Alternatively, a recess formed at a position between the end of the cut and the peripheral edge of the main surface portion, extending in a direction intersecting the cut, and having the mask frame side recessed,
It is characterized by having. According to the present invention, the recess is formed by either a step or a groove.

[0014] According to the color cathode ray tube having the above-described structure, the same height as the upper end of the notch defining the tongue portion of the skirt portion of the mask body, which is the fixing point between the mask body and the mask frame, or more. By providing at least one recess at a high position, that is, on the main surface side of the mask body,
It is possible to prevent wrinkles from occurring in the vicinity of the cut portion, to fix the mask body to the mask frame without displacement, and to make the gap between the tongue piece, which is a fixing portion of the mask body, and the mask frame uniform. Can be. Thereby, no extra stress acts on the fixing portion of the mask body, and the relative position between the mask body and the mask frame,
In addition, the position of the mask body with respect to the face panel can be maintained at a predetermined position. Therefore, it is possible to provide a color cathode ray tube in which the landing deviation of the electron beam is reduced and the display quality is improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment in which the present invention is applied to a color cathode ray tube having an aspect ratio of 16: 9 and a diagonal dimension of 76 cm will be described in detail. As shown in FIG. 1, the color cathode ray tube includes a vacuum envelope 10, which has a face panel 12 and a funnel 14. Face panel 12
Is a substantially rectangular active portion 16 having a substantially flat outer surface.
And a skirt portion 18 erected on the periphery of the effective portion. The funnel 14 is joined to the skirt portion 18. On the inner surface of the effective portion 16 of the face panel 12,
A phosphor screen 20 is formed of phosphor layers of three colors that emit blue, green, and red light, and a black striped light absorbing layer formed in a gap between the phosphor layers.

In the vacuum envelope 10, a substantially rectangular shadow mask 22, which will be described later, is provided inside the face panel 12, and faces the phosphor screen 20. The shadow mask 22 includes a plurality of stud pins 30 protruding from the inner surface of the skirt 18 of the face panel 12.
It is supported inside the face panel 12 by engaging a plurality of elastic supports 32 attached to a mask frame, which will be described later. In addition, funnel 1
The four electron beams 17B, 17G,
An electron gun 24 for emitting 17R is provided.

In a color cathode ray tube, the electron gun 24
Electron beams 17B, 17G, 17R emitted from the
Is deflected by a magnetic field generated by a deflecting device 26 mounted outside the funnel 14, and the phosphor screen 20 is horizontally and vertically scanned via a shadow mask 22, thereby displaying a color image.

As shown in FIGS. 1 and 2, the shadow mask 22 includes a substantially rectangular mask body 34 and a substantially rectangular mask frame 35 supporting the peripheral edge of the mask body.
And The mask body 34 has a thickness of 0.1 to
It is formed in a substantially rectangular shape made of a 0.3 mm cold-rolled steel sheet, and has a long axis (X axis) and a short axis (Y axis) orthogonal to each other through the tube axis Z. Also, the mask body 34
Is a rectangular main surface 3 facing the phosphor screen 20.
8 and a skirt portion 40 bent around the main surface portion
And Further, the main surface portion 38 has a substantially rectangular effective area 38a, in which a large number of slit-like electron beam passage holes 42 are formed.

As shown in FIGS. 2 to 4B, of the skirt portion 40, the central portion of a pair of long side walls 40a extending along the long side of the main surface portion 38, along the short side of the main surface portion 38. A tongue piece 50 is formed at the center of each of the pair of extended short side walls 40b and at each corner. That is, the tongue pieces 50 formed on the long side wall 40a are located at both ends of the short axis Y, and the tongue pieces 50 formed on the short side wall 40b are respectively located at both ends of the long axis X. The tongue pieces 50 formed at the respective corners are located at diagonal shaft ends.

Each tongue 50 is defined between a pair of slit-shaped cuts 44 extending from the open edge 41 of the skirt 40 toward the main surface 38. For example, the height of the skirt portion 40 is set to about 25 mm, and the height of each cut 44 is set to about 17 to 18 mm.

The skirt portion 40 is formed with two steps extending over the entire circumference, ie, recesses 52a and 52b. Each recess 52a extends in parallel with the periphery of the main surface portion 38 and extends in a direction substantially orthogonal to each tongue 50 and the cut 44. The recess 52a is formed at a height overlapping the end of the cut 44 on the side of the main surface 38, and the recess 52b is formed by the recess 52a and the open edge 41 of the skirt portion 40.
Is formed between. And the recesses 52a, 52b
Is press-formed so that the outer surface side of the skirt portion 40, that is, the mask frame 35 side is concave, and the inner surface side of the skirt portion is convex.

On the other hand, the mask frame 35 has a thickness of 1 mm.
It is formed in a substantially rectangular shape having an L-shaped cross-section made of a cold-rolled steel sheet having a degree. Then, the mask body 34 is disposed inside the mask frame 35, and the skirt portion 40 includes:
The welding point 56 at the tip of each tongue 50 is connected to the mask frame 35.
It is attached to the mask frame by welding to the inner surface of the mask frame.

According to the color cathode ray tube configured as described above, in the shadow mask 22, the mask body 34
The skirt portion 40 has a recess 52a extending over the entire circumference,
52b is formed, and the recess 52a is formed at the same height position as the upper end of the cutout 44 defining the tongue piece 50. Thus, wrinkles generated near the upper end of each cut 44 during press forming of the mask body 34 can be absorbed by the recess 52a, and the occurrence of a protrusion protruding toward the outer surface of the skirt 40 can be prevented. Therefore, the mask body 34
When welding is fixed to the mask frame 35 by welding, only the welded portion of the tongue piece 50 comes into contact with the inner surface of the mask frame, and the adverse effect due to wrinkles can be eliminated.

As a result, the variation in the welding position is reduced,
The mask frame 35 and the mask main body 34 after welding can be fixed in a desired positional relationship. Further, no extra stress is applied to the welding point, and the deformation of the tongue piece 50 can be prevented. Therefore, the relative position between the mask body 34 and the mask frame 35 and the position of the mask body 34 with respect to the face panel 12 can be set as designed values, and the landing deviation of the electron beam can be reduced. As a result, it is possible to obtain a color cathode ray tube in which the occurrence of color misregistration is prevented and the display quality is improved.

It is to be noted that at least one recess of the skirt portion 40 is formed between the upper end of the cut 44 formed in the skirt portion, that is, from the end on the main surface portion 38 side and the periphery of the main surface portion. In the same manner as in the above embodiment, the cut 44
Wrinkles generated near the upper end of the mask frame 35 can be absorbed, and misalignment between the mask frame 35 and the mask body 34 can be prevented.

According to the embodiment shown in FIGS. 5a and 5b,
One recess 52 a is formed over the entire circumference of the skirt portion 40 of the mask body 34, and this recess 52 a
It is provided at a position slightly higher than 4. With such a configuration, the same operation and effect as those of the above-described embodiment can be obtained.

The recess 52a of the skirt portion is not limited to the groove having the above-mentioned shape, but a step formed by bending the skirt portion as shown in FIG. 6a, and a triangular section as shown in FIG. 6b. Or a groove having a rectangular cross section as shown in FIG. 6c. In either case,
By providing a recess 52a defined by a step or a groove at a position equal to or higher than the height of the cut 44, that is, on the peripheral side of the main surface portion 38, wrinkles generated at the upper portion of the cut are absorbed or the mask frame is contacted. It is possible to prevent the influence when welding the mask frame and the mask body. As a result, variations in the welding position can be reduced, and the displacement between the mask frame and the mask body after welding can be prevented.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, the formation position, number, and the like of the tongue pieces of the mask frame can be variously selected as necessary. Similarly, the shape of the cut is not limited to the slit shape, but may be another shape.

[0029]

As described above in detail, according to the present invention, in the mask body of the shadow mask, the height is equal to or higher than the upper end of the cut defining the tongue provided on the skirt. By providing a recess at the position, that is, the peripheral side of the main surface of the mask body, and absorbing the wrinkles generated near the cut, the displacement of the mask body with respect to the mask frame and the panel is reduced, and a color cathode ray tube with improved display quality is provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a shadow mask of the color cathode ray tube.

FIG. 3 is a partially cutaway perspective view showing a welded portion between the mask body and the mask frame in the shadow mask.

FIG. 4 is a sectional view of a welded portion between the mask body and the mask frame, and a side view showing a skirt portion of the mask body.

FIG. 5 is a sectional view of a welded portion between a mask body and a mask frame in a color cathode ray tube according to another embodiment of the present invention, and a side view showing a skirt portion of the mask body.

FIG. 6 is a cross-sectional view showing a modified example of the recess provided in the skirt portion of the mask body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Vacuum envelope 12 ... Face panel 14 ... Funnel 20 ... Phosphor screen 22 ... Shadow mask 24 ... Electron gun 34 ... Mask main body 35 ... Mask frame 38 ... Main surface part 40 ... Skirt part 41 ... Open edge 44 ... Cut 50: tongue piece 52a, 52b: recess

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Murai 1-9-2, Harara-cho, Fukaya-shi, Saitama Prefecture Inside the Toshiba Fukaya Plant (72) Inventor Masayo Inoue 1-9-1, Harara-cho, Fukaya-shi, Saitama No. 2 F-term in Toshiba Fukaya Plant (reference) 5C031 EE04 EE11 EH04

Claims (3)

[Claims] 1. An envelope having a face panel having a phosphor screen formed on an inner surface thereof; a shadow mask provided in the envelope opposite to the phosphor screen; An electron gun for irradiating the phosphor screen with an electron beam through the shadow mask, wherein the shadow mask faces the phosphor screen and has a large number of electron beam passage holes formed therein. A substantially rectangular mask main body having a substantially rectangular main surface portion and a skirt portion bent around the main surface portion; and a mask body attached to the skirt portion and located outside the skirt portion. A mask frame having a substantially rectangular shape, wherein the skirt portion has an open edge extending substantially in parallel with a peripheral edge of the main surface portion, and an open edge extending from the open edge to a peripheral edge of the main surface portion. And a plurality of tongues defined between two adjacent cuts and fixed to the inner surface of the mask frame, and the position of an end of the cut on the main surface side, or A recess formed at a position between the end of the cut and the peripheral edge of the main surface portion, extending in a direction intersecting with the cut, and having a concave portion on the mask frame side. A color cathode ray tube characterized by the above. 2. The color cathode ray tube according to claim 1, wherein said recess extends over the entire circumference of said skirt portion. 3. The color cathode ray tube according to claim 1, wherein the recess is formed by a step or a groove.