JPH0747783Y2 - Color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is directed to a color picture tube in which an electron beam emitted from an electron gun passes through pores of a shadow mask supported by a frame and strikes a fluorescent screen. It is about.

[Prior Art] Third outline of a conventional shadow mask type color picture tube
In the figure, a picture tube (1) includes a panel portion (2) and a fluorescent screen (3) formed on the inner surface of the panel portion (2).
A shadow mask (4) arranged to face the fluorescent screen (3), a funnel-shaped funnel portion (5) connected to the panel (2), and a neck portion including an electron gun (not shown). (6) and. The shadow mask (4) is supported by the frame (7) and the like so as to face the fluorescent screen (3).

In such a color picture tube, the shadow mask (4) receives an electron beam from the electron gun and undergoes thermal expansion, and expands from a cold state (shown by A) to a dome shape as shown in FIG. Moving to the state (indicated by B), the relative positional relationship between the fluorescent screen (3) and the electron beam is broken, and an undesirable color shift phenomenon occurs. This phenomenon is called "doming" and has the characteristics shown in FIG.

In the figure, the horizontal axis shows the distance r from the center of the fluorescent screen (3), and the vertical axis shows the mismatch (shift) due to the doming of the phosphor dots and the electron beam, that is, the amount of misregister. This misregister amount has a peak in the vicinity of a deflection angle of 50 ° in a color picture tube with a 90 ° deflection, for example.
It may reach m. This is a very large amount that cannot be ignored compared to the dot size of the high resolution color picture tube of about 120 μm.

By the way, this doming development is mainly caused by the following two steps. That is, when the electron beam strikes the shadow mask (4), the shadow mask (4)
5 due to the difference in heat capacity due to the thickness of the plate (about 0.10 to 0.20 mm) and the thickness of the frame (7) (about 1.6 to 2.3 mm)
Up to about a minute, mainly the shadow mask (4) thermally expands and projects into a dome shape as shown in FIG. 4 to cause a misregister. FIG. 6 shows the direction and size of the misregister with respect to the distance from the center of the fluorescent screen (3) on the horizontal axis. On the other hand, when the frame (7) thermally expands after 5 minutes, a particularly large misregister appears in the peripheral portion as shown in. However, this misregister can be corrected by interposing a bimetal or the like to bring the entire shadow mask (4) closer to or further from the fluorescent screen (3). Furthermore, the component when used as a picture tube (1) is, for example,
It can be considered that it does not change much after 30 minutes, but the misregister of changes at any time depending on the image (light and dark) displayed on the fluorescent screen (3). Therefore, in most cases, it is a problem with the component.

Here, FIG. 7 shows the general structure of the shadow mask (4). (4A) is a perforated portion of the phosphor screen facing portion which is disposed so as to face the phosphor screen (3), and (4B). Is a non-perforated portion of the fluorescent screen facing portion, and (4C) is a skirt portion extended from the non-perforated portion (4B). Nearly the end of the skirt (4C) is welded and fixed to the frame (7). Although the frame (7) is provided inside the skirt portion (4C) of the shadow mask (4) in the figure, it may be provided outside.

The doming phenomenon is affected by the thickness of the shadow mask (4). FIG. 8 is a diagram in which the horizontal axis represents time and the vertical axis represents the amount of change in the misregister, and shows the case where the code B is made of a metal plate thinner than the code A. This is because when the electron beam has a constant energy and hits the shadow mask (4), there is a difference in the heat capacity of the shadow mask (4), so that the final thermal deformation amount is different. Therefore, as a measure against the doming of the shadow mask (4), generally, a thicker plate is advantageous. However, as the plate thickness of the shadow mask (4) becomes thicker, it becomes difficult to make small holes and small hole pitches.

FIG. 9 is a shadow mask (4) showing a structure in which the above problems are solved, and the perforated part (4A), the non-perforated part (4B) and the skirt part (4C) are the first metal plate (10). ) And the second metal plate (11). The first metal plate (10) and the second metal plate (11) are each perforated by etching before joining, and the first metal plate (10) is compared with the second metal plate (11). The plate thickness is thin and the hole size is small.

[Problems to be solved by the device]

In the color picture tube configured as described above, since the first metal plate (10) and the second metal plate (11) having the same size are joined to each other to perform draw forming, the non-perforated part ( 4B), wrinkles are generated in the first metal plate (10) corresponding to the inner side of the diaphragm in the skirt portion (4C), and the pore size and pitch of the shadow mask (4) vary, resulting in color shift. There was a problem that occurred.

The present invention has been made to solve such a problem, and a wrinkle does not occur when drawing a metal plate, and a color picture tube provided with a shadow mask having a predetermined hole size and pitch is obtained. The purpose is to

[Means for Solving the Problems]

A shadow mask for a color picture tube according to the present invention has a fluorescent screen facing portion formed by drawing at least two metal plates, and extends from the non-effective portion end of the fluorescent screen facing portion to the skirt portion. Is one of the drawn metal plates
One has been extended.

[Action]

In this invention, one of the drawn metal plates
Since it is extended from the end of the non-effective portion of the fluorescent screen facing portion to the skirt portion, wrinkles that occur in the skirt portion during the drawing process of the shadow mask are reduced, and a shadow mask having a predetermined hole size and pitch is formed. can get.

〔Example〕

An embodiment of this invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a lower back portion showing a first embodiment of the present invention.
The same or corresponding parts as those in the conventional drawing are designated by the same reference numerals, and the description thereof will be omitted.

In the case of this shadow mask (20), the second metal plate (1
The first metal plate (21) joined to the inside of 1) does not extend to the skirt (20C), and the second metal plate (11)
Is the skirt (20C) from the end of the ineffective part of the part facing the fluorescent screen
It is extended to and is connected to the frame (7).

In such a shadow mask (20), since the skirt portion (20C) is a single plate, the shadow mask (20)
Wrinkles are reduced in the skirt (20C) during drawing of
A shadow mask (20) having a predetermined pore size and pitch is obtained. Also, since the shadow mask (20) can be easily drawn and the plate thickness of the skirt (20C) is reduced and the shadow mask (20) is fixed to the frame (7).
As described in Japanese Patent No. 860, it is possible to reduce the beam movement amount during doming.

FIG. 2 is a waist sectional view showing a second embodiment of the present invention. In this embodiment, the second metal plate (22) is extended to the skirt portion (23C) of the shadow mask (23). Not not.

[Effect of device]

As described above, in the color picture tube of the present invention, one of the drawn metal plates is extended from the end of the ineffective portion of the fluorescent screen facing portion to the skirt portion, so that the shadow mask is drawn. In this case, wrinkles occurring in the skirt portion are reduced, and a shadow mask having a predetermined size and pitch of pores is obtained. As a result, the phenomenon of color misregistration is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a first embodiment of the present invention, and FIG. 2 is a sectional view showing a second embodiment of the present invention.
FIG. 4 is a partially cutaway sectional view showing an example of a conventional color picture tube, FIG. 4 is a characteristic diagram for explaining doming of a shadow mask, and FIGS. 5 and 6 are diagrams of misregister distribution due to doming. FIG. 7 is a sectional view of a main part of a shadow mask made of a single plate, FIG. 8 is a relationship diagram showing the relationship between the thickness of the shadow mask and a misregister, and FIG. 9 is a conventional double plate. It is a principal part sectional view of a shadow mask. In the figure, (1) is a picture tube, (2) is a panel, and (3)
Is a fluorescent screen, (7) is a frame, (10), (21)
Is the first metal plate, (11), (22) is the second metal plate, (2
0) and (23) are shadow masks. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] 1. In a color picture tube in which an electron beam passes through pores of a shadow mask disposed inside a panel and supported by a frame and strikes a fluorescent screen on the inner surface of the panel, the shadow mask is A drawn metal plate having a phosphor screen facing portion formed by drawing at least two joined metal plates, and the drawn metal plate from the non-effective end portion of the phosphor screen facing portion to the skirt portion. A color picture tube, characterized in that one of them is extended.