JPH0278134A - Shadow mask structure for color television picture tube - Google Patents

Abstract

PURPOSE:To suppress deformation of thick parts except welded parts so as to make deformation of a main body small by fusion welding of neighbouring two shadow mask plates through not penetrating holes in one of the plates. CONSTITUTION:Shadow mask plates 21, 22 are coated with a resist layer in a prescribed thickness and an image is baked on one side of the plates, and then unnecessary parts of the resist layer are removed. After that, metals only in the parts for through holes 23, 25, a not penetrating hole 27, circular grooves 30, 31, and position setting holes 42A, 42B, and 42C are removed so as to give a desired shadow mask plates 21, 22. A metal part 29 for welding is melted in a necessary amount to weld the plate 21 with the plate 22 from the bottom part of the hole 27 formed in the plate 22 through the plane (K) where the plates 21 and 22 have a contact each other by electron beam irradiation and then solidified the melted part by stopping the electron beam irradiation. The plates 21 and 22 are welded each other by the welded part 29 and a shadow mask main body 7 is thus formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a collar that is constructed by welding together a plurality of shadow mask plates and has an electron beam passage hole for passing the electron beam to the phosphor screen side within the picture tube. The present invention relates to a shadow mask structure for a picture tube.

[Prior Art] FIG. 9 is a partially cutaway perspective view schematically showing the structure of a shadow mask type color picture tube. In the figure, (1) is a funnel-shaped funnel, and a fluorescent screen (3) is formed on the inner surface of a panel (2) sealed at the open end of this funnel (1). A plurality of pins (4) are provided on the side wall of the panel (2), and a shadow mask structure (5) disposed facing the fluorescent screen (3) is supported by the bin (4). There is.

(12A), (12B), and (12C) are electron guns placed within the neck portion (14) of the funnel (1).

(7) is a shadow mask main body having a spherical shape almost equal to the inner surface shape of the panel (2), and this shadow mask main body (7) is connected to the electron gun (128), (12B).
.

(12C) Electron beam emitted from (6A), (
It consists of a perforated part having a large number of electron beam passing holes (13) through which electron beams 6B) and (6C) selectively pass, and a non-perforated part formed around the outer periphery of the perforated part.

(8) A skirt portion that is bent to be attached to the frame (9), and the skirt portion (8) is fixed to the frame (9) over its entire circumference by welding, for example, at 16 points. (10) is a thermal expansion correction mechanism welded to the frame (9), and this thermal expansion correction mechanism (10
) is provided to correct color shift due to thermal expansion of the shadow mask body (7) that occurs during operation of the color picture tube.

The thermal expansion correction mechanism (10) includes a bimetal (15),
A spring (11) welded to this bimetal (15)
), and this spring (11) has a pin (4
) to move the shadow mask body (7) to the panel (2
). The above shadow mask structure (5
) is composed of a shadow mask body (7), a frame (9), and a thermal expansion correction mechanism (1o).

In the shadow mask type color picture tube having the above structure, the electron guns (12A), (12B)
.

Electron beam (8A) emitted from (12C), (
611), (6G) passes through the electron beam passage hole (13) provided in the perforated part of the shadow mask body (7) and hits the fluorescent screen (3), emitting light in red, green, and blue colors. make the phosphor emit light.

By the way, normally, the total area of the electron beam passage hole (13) of the shadow mask body (7) is the same as the shadow mask body (7).
7), and most of the electron beams (6A), (6B), (6C) +7) collide with the non-opening parts of the perforated parts, and the electron beams (7)
) to heat up. For example, as a result of measuring the temperature of the shadow mask structure (5) in a 21-inch color picture tube, a temperature increase was observed as shown by curves (A) and (B) in FIG.

That is, when the temperature of the shadow mask body (7) was measured under the conditions of a high voltage of 28 kV and a beam current of 1 mA, as shown in the characteristic curve (A) in FIG.
The temperature rises significantly within 30 minutes, reaching saturation in 30 minutes and reaching approx.
A temperature increase of 0°C was observed.

When the temperature of the frame (9) was measured under similar conditions for ,=shi, it was found that since the heat capacity of the frame (9) was larger than that of the shadow mask body (7),
As shown by the characteristic curve (B) in FIG. 10, the temperature gradually increased and reached a saturated state in about 1 hour.

When such a temperature rise occurs, the shadow mask body (7) first thermally expands in a dome shape (hereinafter referred to as doming) and protrudes toward the phosphor screen (3), causing color shift (hereinafter referred to as misalignment). (referred to as landing).

That is, as shown in FIG. 11, the shadow mask main body (7), which was in the state shown by the solid line S in the figure before the start of the operation,
As the temperature rises, the entire structure thermally expands toward the phosphor screen (3) in a dome shape as shown by the dotted line S1, using the joint W with the frame (9) as a fixed point. Due to this doming, the electron beam passing hole (13), which was in the normal position indicated by point H in the figure, moves to point H1, and originally should reach point P on the phosphor screen (3), for example. Electron gun (1
The electron beam (6A) from 2A) reaches point P1,
This results in a false landing.

This type of mislanding occurs when the center Z of the fluorescent screen (3)
It is characterized by the deviation in the direction of arrow a (direction of arrow a), which causes adjacent phosphors of other colors to emit light, making it impossible to display a normal color image. Such a phenomenon appears over the entire screen.

The inner radius of the diagonal axis of panel (2) is 1°350mm.
When measured with a 21-inch color picture tube, it appeared most prominently on a long sleeve 150 mm from the center axis Z of the face surface of the panel (2), with a high voltage of 28 kV and a beam current of 1 m.
Under the conditions of A, the electron beam is 0.05-0.08 mmf
I was working a J shift, which caused color shift phenomenon.

In addition, when the temperature of the frame (9) gradually increases and approaches the saturated state, the frame (9), which was in the state shown by the solid line F in the same figure before the start of operation, will be caused by thermal expansion of the frame (9) itself.
) thermally expands in the radial direction as a whole as shown by the dotted line Fl. As a result, the shadow mask main body (7), which was in the state shown by the solid line S in the figure before the start of the operation, moves as a whole in the radial direction as shown by the dotted line S2, since the joint W with the frame (9) moves to the point Wl. Displaced as shown in . Due to this displacement, the electron beam passage hole (1
3) moves to point H2 and should originally reach point P on the phosphor screen (3). For example, the electron beam (6A) from the electron gun (+2A) reaches point P2 and causes a mislanding. becomes.

This type of mislanding is characterized by a shift toward the periphery of the phosphor screen (3) (in the direction of the arrow), and other colors in the opposite direction to the phenomenon that appears at the beginning of the operation of the color picture tube described above. This makes it impossible to make the phosphors emit light and produce a normal color image as in the early stages of operation of the color picture tube.

The above-mentioned phenomenon continues to occur while the color picture tube is in continuous operation, and therefore it is necessary to correct it.

Conventionally, various types of thermal expansion correction mechanisms (10) interposed between the shadow mask main body (7) and the frame (9) have been known in order to correct this.

That is, as explained with reference to FIG. 11, doming occurs when the joint W between the shadow mask main body (7) and the frame (9) serves as a fixed point, so it is caused by the thermal expansion correction mechanism (10). The above joint W before the start of operation
If it is moved to the point W3 shown by the imaginary line, the shadow mask body (7) which was in the state shown by the solid line S in the same figure before the start of the operation
, as shown by the virtual line s3, moves closer to the electron gun (12^) than in the case shown by the dotted line S2. As a result of this movement, the electron beam passing hole (13), which was in the normal position indicated by point H in the same figure, moves to point H3, and the electron beam passing hole (13), which has moved to this point H3, moves to the electron gun (12^). ) to which the electron beam (6A) must originally reach the phosphor screen (
3) The position points toward the point P above, reducing mislanding.

On the other hand, due to an increase in the temperature of the frame (9), the frame (9) was in the state shown by the solid line F in FIG. 12 before the start of operation.
thermally expands as shown by dotted line F1, and the electron beam passage hole (13), which was in the normal position shown by point H, moves to point H2.

However, the thermal expansion correction mechanism (10) moves the shadow mask body (7) and frame (9) to the virtual line S3.
, as shown by F3, if you approach the fluorescent screen (3) side,
The electron beam passing hole (13), which was in the normal position indicated by point H in the figure, moves to point H3, and the electron beam passing hole (13), which has moved to this point H3, receives electrons from the electron gun (12A). The fluorescent screen (
3) The position points toward the point P above, reducing mislanding.

Conventionally, as such a thermal expansion correction mechanism (lO), for example, a bimetal (15) was used.
-26152, Special Publication No. 1977-3547, Special Publication No. 1977
-3508, Japanese Patent Publication No. 47-40505, etc. are known.

However, as shown in FIG. 13(a), for example, a screen (
16), the local part (7a) of the shadow mask main body (7) shown in FIG.
is thermally deformed, causing color shift due to local doming. It has been impossible to correct color shift due to such local doming using the conventional thermal expansion correction mechanism (10).

In order to solve this problem of color shift due to local doming, as shown in the paper "Theoretical Study on Local Doming Phenomenon of Shadow Mask Tube" published in the Journal of the Television Society, it is necessary to improve the shadow mask body (7). It has been theoretically proven that increasing the thickness of the material is effective.

However, the shadow mask body (7) is generally manufactured by a chemical method such as the etching method disclosed in Japanese Patent Publication No. 51-9264.

In this chemical manufacturing method, the shadow mask body (
7) and the size (Sw) of the electron beam passage hole (13) through which the electron beam passes, Sw>o
, axt...
There is a condition called ・・・■, and if this condition is satisfied,
It is impossible to closely space small holes in a thick plate.

In other words, to improve the resolution of color picture tubes,
By reducing the setting pitch of the phosphors constituting the phosphor screen (3), the shadow mask body (7) can improve its color selection function by reducing the electron beam passage holes (
It goes without saying that the size of 13) must also be made small.

On the other hand, in order to suppress color shift due to thermal deformation of the shadow mask body (7) and maintain good color purity, a thick shadow mask body (7) is required, as stated in the aforementioned Journal of the Television Society. As the paper says.

However, these two have a clearly contradictory relationship from the above equation 0. Therefore, in order to satisfy both of these requirements, it is extremely difficult to form a small electron beam passage hole (13) in the shadow mask body (7), which is made of a single thick plate, in terms of manufacturing, as described above. It is.

Therefore, for example, as shown in Japanese Unexamined Patent Publication No. 57-138746, by stacking a plurality of thin shadow mask plates and welding them, a substantially thick shadow mask body (7 ) is proposed.

That is, in Fig. 14, (21) and (22) are two thin shadow mask plates, and these shadow mask plates (21) and (22) are usually made of extremely thin aluminum killed steel with a thickness of 0.3 mm or less. It is manufactured from
A large number of through holes (13a) and (13b) which become electron beam passage holes (13) are formed by etching.

After the shadow mask plates (21) and (22) are laminated, welding is started from the surface (22a) of the shadow mask plate (22) using, for example, a laser beam.

The metal welded part (38) by laser light irradiation passes from the surface (22a) of the shadow mask plate (22) through the mutually contacting surface (K) of the two shadow mask plates (21) and (22), After the other shadow mask plate (21) is melted by an amount necessary for welding, the molten portion is solidified by cutting off the laser beam irradiation. The shadow mask plates (21) and (22) are joined to each other by this solidified metal weld (38) to form a shadow mask main body (7).

[Problems to be Solved by the Invention] However, according to the joining based on such welding, since the volume of the welded part (38) is relatively large, the welded part (3B) shrinks in the process of melting and solidifying. At this time, the thick part in the vicinity is pulled, causing so-called welding distortion.

As a result, the shadow mask main body (7) is deformed, and the deformation is further aggravated by the pressing operation to form it into a spherical shape, resulting in the disadvantage that it cannot function as a shadow mask for a color picture tube.

This invention was made to solve the above-mentioned problems.It prevents the deformation that occurs when multiple stacked shadow masks are melted and bonded, and produces high-resolution, brownish-purity colors. An object of the present invention is to provide a shadow mask structure for a color picture tube that can constitute a picture tube.

[Means for Solving the Problems] A shadow mask structure for a color picture tube according to the present invention has the following features:
Adjacent two of the multiple stacked shadow mask plates
A non-through hole is formed in one of the shadow mask plates, and a plurality of shadow mask plates are fused and bonded through the non-through hole, and two
The present invention is characterized in that annular grooves are formed to face each other on the bonding surfaces of the shadow mask plates, and at least a portion of each annular groove is opened to an electron beam passage hole.

[Operation] According to the present invention, two shadow mask plates adjacent to each other are melted and bonded through the non-through hole formed in one of the shadow mask plates, so that the molten volume of the shadow mask plates becomes small. Therefore, the amount of welding distortion caused by solidification and shrinkage of the molten part becomes small. Further, since the strain force due to welding strain is blocked and absorbed by the annular groove formed so as to surround the welded portion, deformation of the thick portion other than the welded portion can be suppressed. Therefore, deformation of the shadow mask main body having a laminated structure can be minimized.

Furthermore, since the annular groove is opened at the electron beam passage hole, during welding, impurity gas remaining in the annular groove passes through the electron beam passage hole before the shadow mask main body is incorporated into the color picture tube. It is easily discharged outside.

Therefore, the inside of the color picture tube can be maintained at a high vacuum and its life can be extended.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is an enlarged plan view of essential parts of a shadow mask structure for a color picture tube according to an embodiment of the present invention, viewed from the phosphor screen side.

The overall configuration of the shadow mask type color picture tube is as follows.
Since it is similar to that shown in the figure, the following description will be made with reference to the same figure.

In Fig. 1, (21) is an electron gun (12A), (
12B).

One relatively thin shadow mask plate (12C) is disposed on the side (12C), and as clearly shown in FIGS. ) are laminated. This shadow mask plate (22) is disposed on the phosphor screen (3) side which is the main conductor of heat, and is formed relatively thick in order to reinforce the shadow mask plate (21). (23) ) is a slot-shaped through hole forming an electron beam passage hole (13) provided in the shadow mask plate (21);
(24) is the side wall of the through hole (23), and (25) is the electron beam passing hole (13) provided in the shadow mask plate (22).
) is a slot-shaped through hole that forms a through hole (25
) is the through hole (23) on the shadow mask plate (21) side.
It is formed somewhat larger than the . (26) is a through hole (
25).

(27) is the surface (22a) of the shadow mask plate (22)
The non-through hole (28) formed on the side is this non-through hole (2
7), (29) is a welded part where both shadow mask plates (21) and (22) are fused and joined through the bottom of the non-through hole (27), and (30) is a welded part to the shadow mask plate (22). The annular groove ('10) is formed in the shadow mask plate ('10) so as to surround the welded part (29).
21) is formed on the joint surface (K) with

(31) is an annular groove formed in the shadow mask plate (21), and this annular groove (31) is connected to the joint surface (K) with the shadow mask plate (22) so as to surround the welded portion (29) is formed. Both annular grooves (30), (
31), one part of which faces each other, and one of the annular grooves (31)
) is formed with an opening (32) that communicates with the through hole (23).

FIG. 7 is a schematic plan view of the shadow mask main body (7), which consists of a perforated part (35) and a non-perforated part (36).
6) has the above two shadow mask plates <21), (2
2) Positioning hole (42A) for accurate positioning
).

(42B) and (42C) are formed.

FIG. 8 is a perspective view of the shadow mask main body (7) shown in FIG. 7 which has been press-molded into a spherical shape, and a skirt portion (8) is integrally formed around it by folding.

Next, a method for manufacturing the shadow mask main body (7) having the above structure will be schematically explained.

First, a resist layer of a predetermined thickness is coated on both sides of each of the two shadow mask plates (21) and (22), and the resist layer corresponding to one side of each shadow mask plate (21) and (22) is coated with a resist layer of a predetermined thickness. After each image drawn by an automatic drawing device is printed on the resist layer, unnecessary portions of the resist layer are removed.

After that, through-holes (23) are formed by chemical etching.
, (25), non-through hole (27), annular groove (30),
(31) and positioning holes (42, A), (42B)
, (42C) is removed by corrosion to obtain the desired shadow mask plates (21) and (22).

Next, the shadow mask plates (21), (22) are joined on the side where the annular grooves IO), (31) are formed, and the positioning holes (42A), (42B), (4) are formed.
2G), it can be accurately aligned and attached to a predetermined jig (not shown). Thereafter, an electron beam welding machine is used to irradiate the bottom of the non-through hole (27) with an electron beam, and welding is started from the bottom of the non-through hole (27).

The metal welded part (29) by electron beam irradiation is formed in the non-through hole (27) formed in the shadow mask plate (22).
) from the bottom of the two shadow mask plates (2t), (
2z), which are in contact with each other, are melted in an amount necessary to weld the other shadow mask plate (21), and the melted portion is solidified by blocking the irradiation of the electron beam. Ru. This solidified metal weld (
29), the shadow mask plate (21), (
22) are welded together to form a shadow mask body (7).
is configured.

In addition, when welding by the electron beam welding machine, the amount of incident energy of the electron beam is set in order to determine the accurate amount of melting of the metal corresponding to the welding part (29).

By the way, when the welded portion (29) is melted and solidified, welding distortion occurs due to the solidification shrinkage. However, the amount of melting of this welding part (29) is large enough to weld the bottom wall thickness t1 of the non-through hole (27) formed in the shadow mask plate (22) and the other shadow mask plate (21). This amount corresponds to the wall thickness t2 that is melted by the required amount.

In other words, as shown in FIG. 14, in the conventional welding part (38), the other shadow mask plate (21) is first welded by melting an amount corresponding to the wall thickness t3 of the shadow mask plate (22). can be done.

However, by forming the welded portion (29) at the bottom of the non-through hole (27) as described above, this welded portion (29)
The amount of melting is significantly reduced. Therefore, the welded part (29
) when it solidifies from melting, the amount of welding strain that occurs due to its contraction becomes smaller.

In addition, since the strain force due to welding strain is blocked and absorbed by the annular grooves (30) and (31) formed so as to surround the welded part (29), the welded part (29) is Deformation can be suppressed. Therefore, deformation of the shadow mask main body (7) having a laminated structure can be minimized.

Further, the annular grooves (30) and (31) are one of the annular grooves (3
1) and the through hole (23) to open into the electron beam passage hole (13). Therefore, during welding, the annular grooves (30), (31) The impurity gas remaining in the shadow mask body (7) is removed from the electron beam passage hole (13) before it is incorporated into the color picture tube.
) is easily discharged to the outside. Therefore, there is no fear that impurity gas will be released into the color picture tube, and the interior of the tube can be maintained at a high vacuum, thereby achieving a longer service life.

In the above embodiment, the shadow mask body (7) has two parts.
Although we have explained the case where the shadow mask body (7) is composed of two shadow mask plates (21) and (22), the same applies to the case where the shadow mask body (7) is composed of three or more shadow mask plates by welding. Of course, it is effective.

In addition, in the above embodiment, the two shadow mask plates (21) and (22) are welded using an electron beam welding machine, but the welding is performed using a laser beam as in the conventional case. Needless to say, the same effect can be achieved.

Furthermore, in the above embodiment, the shadow mask structure (
Although a case has been described in which a bimetal is used as the thermal expansion correction mechanism (10) in 5), the same effect can be achieved by using other known means.

Furthermore, in the above embodiment, the opening (32) communicating with the electron beam passage hole (13) was formed in the annular groove (31) of one of the shadow mask plates (21). 32) is the other shadow mask plate (
22) annular groove (30) or both annular grooves (30).

(31), similar effects can be obtained.

Note that FIGS. 4 to 6 show other embodiments of the present invention, in which two shadow masks (21) and (2
An annular groove (30) surrounding the welding part (29) of 2)
is formed only on the contact surface of one shadow mask plate (22) to be overlapped, and an opening ( 32), and its operation and effect are exactly the same as in the above embodiment.

[Effects of the Invention] As described above, according to the present invention, a thick shadow mask body can be constructed by melting and joining a plurality of stacked shadow mask plates, and the resulting thick The shadow mask body can prevent wrinkles due to welding distortion, and deformation such as separation and misalignment between the laminated shadow mask plates.

Therefore, in order to improve the resolution of color picture tubes, the setting pitch of the phosphors that emit red, green, and blue colors that make up the phosphor screen is reduced, and the electron beams formed on the shadow mask body are reduced. It is possible to reduce the size of the passage hole.

Further, in order to suppress color shift due to thermal deformation of the shadow mask body and maintain good color purity, a thick shadow mask body can be easily obtained.

That is, according to the shadow mask structure for a color picture tube according to the present invention, it is possible to achieve both an improvement in resolution and an increase in color purity.

In particular, according to the shadow mask structure according to the present invention, since the shadow mask main body is thick, it is theoretically proven in an article in the Journal of the Television Society that the electron beam does not reach the local shadow mask plate. It is possible to prevent thermal deformation of the shadow mask plate itself, that is, local doming, caused by the impact of the shadow mask plate, and thereby provide a color picture tube with good color purity.

Furthermore, impurity gas generated during melt bonding of the shadow mask body can be easily exhausted to the outside, making it possible to maintain a high vacuum inside the picture tube, thereby extending the life of the color picture tube. .

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view of the main parts of a shadow mask for a color picture tube according to an embodiment of the present invention, and FIG. 2 is an enlarged plan view showing II of FIG.
-A cross-sectional view along the line II, FIG. 3 is the III- in FIG.
4 is an enlarged plan view of essential parts of a shadow mask for a color picture tube according to another embodiment of the present invention; FIG. 5 is a sectional view taken along line V-V in FIG. 4; Figure 6 is a cross-sectional view taken along the VT-VT line in Figure 4, Figure 7 is a schematic plan view of the joined shadow mask body, Figure 8 is a perspective view of the press-molded shadow mask body, and Figure 9 is a cross-sectional view taken along the VT-VT line in Figure 4. A partially cutaway perspective view of a shadow mask type color picture tube. Fig. 1O is a characteristic diagram showing the temperature rise course with respect to the operation time of the frame and shadow mask plate in the shadow mask type color picture tube. FIG. 12, a diagram for explaining an example of doming of the shadow mask structure and its correction operation, shows the heat I! of the frame in the shadow mask structure. FIG. 13 is a line diagram for explaining an example of local doming of the shadow mask structure in a color picture tube; 14(a) is a front view of a screen in a color picture tube, FIG. 14(b) is a plan view of the color picture tube, and FIG. 14 is an enlarged plan view of essential parts of a conventional shadow mask structure for a color picture tube. (2)... Panel, (3)... Fluorescent screen, (7)...
・Shadow mask body, (9)...Frame, (10
)...Thermal expansion correction mechanism, (13)...Electron beam passage hole, (21), (22)...Shadow mask plate, (
27)...Non-through hole, (29)...Welded part, (30
), (31)... annular groove, (32)... opening,
(K)...Contact surface of shadow mask plate. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A shadow mask main body, which is disposed facing a phosphor screen formed on the inner surface of the panel and in which a large number of electron beam passing holes are formed, and a frame fixed to the outer periphery of this shadow mask main body, and during image receiving operation. A color picture tube shadow mask structure comprising a thermal expansion correction mechanism for correcting color shift due to thermal expansion of the shadow mask main body, and comprising a plurality of laminated shadow mask plates joined together by welding. A non-through hole formed in one of the two adjacent shadow mask plates of the shadow mask plate, and a welded portion of the two shadow mask plates welded together through the non-through hole are surrounded by the at least A shadow mask structure for a color picture tube, comprising an annular groove formed on a contact surface of one of the shadow mask plates, and an opening through which the annular groove communicates with an electron beam passage hole.