KR200313363Y1 - Shadow Mask Frame of Color CRT - Google Patents

Abstract

The present invention discloses an improved frame for supporting a shadow mask of a color brown tube.

In the related art, there is a problem of deteriorating the image quality due to the distortion of the frame due to the difference in thermal expansion between the long and short sides of the frame. Compensates for the difference in the amount of thermal expansion between the edges to achieve high quality color images.

Description

Shadow Mask Frame of Color CRT

The present invention relates to a color-brown tube, and more particularly, to a frame for supporting a shadow mask.

As shown in FIG. 1, the basic structure of the color CRT forms a fluorescent surface S having R, G, and B fluorescent layers arranged in a dot or stripe shape on an inner surface of a panel (P). Then, the electron beam B emitted from the electron gun assembly is color-selected through the shadow mask M to selectively emit the corresponding fluorescent layer of the fluorescent surface S to implement a color image.

Here, the shadow mask (M) has a configuration in which a plurality of color selection holes are formed in a very thin metal sheet of about 0.1 to 0.2 mm, so that its own shape-keeping ability is almost absent, and thus the frame is installed in a tension state or as shown in the drawing. It is coupled to and supported by (F).

In general, the shadow mask (M) is used not only as a color screening means but also as an exposure mask for forming the fluorescent surface (S), so that the frame (F) is a stud pin (stud) around the panel (P) through the holder (H). elastically coupled to and detachable from pin: T).

However, a considerable amount of the electron beam (B) hits the shadow mask (M) itself instead of passing through the color selection hole of the shadow mask (M) to be converted into hot electrons, thereby heating the shadow mask (M) and at the same time, the glass electrons As a result, the short- and long-term drift of the electron beam B is generated by the difference in size and time of heat capacity and thermal expansion amount between the shadow mask M, which is a porous thin plate, and the frame F, which is a considerably thicker plate. do.

Here, the doming phenomenon caused by the suppression of the frame F to the thermal expansion rate of the shadow mask M at the initial operation is to attach the bimetal lamp to the holder H to bring the shadow mask M closer to the fluorescent surface S side. Is solved.

In addition, even in long-term drift, the problem in the tube axis direction of the CRT can be solved to some extent, but it is difficult to solve the problem of rotation and distortion, which is a major obstacle to improving the image quality of the CRT.

That is, as shown in FIG. 2, the frame F is coupled to the stud pins T of the panel P with three or four holders H, so that each holder H is thermally expanded in its longitudinal direction. Moment (Mt) for rotating the frame (F) in the direction away from the stud pin (T) is generated.

Accordingly, when the directions of the holders H are arranged in the same rotational direction as shown in the drawing, the frame F is rotated counterclockwise as a whole, so that the alignment state between the shadow mask M and the fluorescent surface S is maintained. Because of the disturbance, the color purity of the displayed image is inevitably deteriorated.

In order to prevent this, a method of preventing rotation of the frame F is generally used by using three holders H and arranging one of them in opposite directions. Twisting moment is generated by mutual suppression of rotational motion due to thermal expansion of H).

However, since the frame F does not have the same amount of thermal expansion in each direction but the amount of thermal expansion in the long side direction and the short side direction is further increased, the distortion moment by the holder H is further increased so that the frame F finally has considerable distortion. .

That is, since the shadow mask M supported on the frame F is warped in the operation state of the CRT, the distance between the shadow mask M and the fluorescent surface S is locally different, so that the color purity of the displayed image is entirely wide. It becomes uneven.

In view of such a conventional problem, an object of the present invention is to provide a frame that can suppress distortion.

1 is a schematic cross-sectional view of a color brown tube,

2 is a front view showing the problem of the conventional frame,

3 is a dimensional view of a frame for explaining a conventional problem,

Figure 4 is a front view showing the configuration of the subject innovation frame,

5 is a main portion of the present invention frame,

6 (A) and (B) are comparative cross-sectional views for explaining the operation of the frame of the present invention.

<Description of the symbols for the main parts of the drawings>

F: frame 1: long side

2: short side 1a, 2a: side wall

1b, 2b: flange

3: bend

4: incision

E: electron shield

5: shield

In order to achieve the above object, the present inventors first examined the difference in thermal expansion rate between the long and short sides of the frame F, which increases the distortion of the frame F.

That is, as shown in FIG. 3, the frame F has a long side E1 and a short side E2 having an aspect ratio almost the same as the aspect ratio of the panel P. In a standard CRT, the aspect ratio is 4: 3 and a wide screen. 16: 9 for the wide screen.

Since the thermal expansion amount is proportional to the length, when viewed linearly, the ratio of the thermal expansion amount of the frame F is equal to the aspect ratio.

That is, in the standard CRT of 4: 3, the thermal expansion of the long side E1 is 4/3 times that of the short side E2, and 16/9 times in the wide screen CRT.

Here again, the thermal expansion amount Δℓ is Δℓ = ε · ℓ · ΔT (ε is the thermal expansion rate, ℓ is the length, ΔT is the temperature difference), where the length (L) and the temperature difference (△ T) is Since it cannot be changed, only the thermal expansion coefficient epsilon is adjustable.

Therefore, if the coefficient of thermal expansion? Between the long and short sides E1 and E2 is set in inverse proportion to the aspect ratio, that is, the aspect ratio, the long side E1 and the short side E2 will have the same amount of thermal expansion DELTA L.

Based on this consideration, the present invention is characterized in that a bent portion is formed on at least a portion of the side wall of the short side to extend the girth thereof.

Preferably, the degree of formation of the bent portion of the short side portion is configured such that the amount of thermal expansion due to the extended gauze becomes equal to the amount of thermal expansion of the long side portion.

Accordingly, since the frame F receives only the twisting moment caused by the holder H, the distortion and the distortion of the shadow mask M are greatly reduced, and thus the image quality of the display image may be remarkably improved.

Example

Such specific features and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

In FIG. 4, the frame F has two long sides 1 and two short sides 2, and the long side 1 and the short side 2 have side walls 1 a, 2 a and a flange 1 b, respectively. 2b) and has a cross section of "L" shape.

In the side wall 2a of the short side portion 2 whose thermal expansion is smaller than the long side portion 1, a bent portion 3 for extending the gauze is formed on at least a part thereof according to the characteristics of the present invention, the center of the short side portion 2 Since the support mechanism of the frame F, such as holder H, should be provided, the bent part 3 is comprised by two divisions on both sides of the short side part 2 side wall 2a.

Such a bent portion 3 serves to increase the amount of thermal expansion of the short side portion 2, as will be described later with reference to Figure 6, the bent portion of the flange (2b) of the short side portion (2) to ensure the free expansion ( 3) It is preferable that the incision 4 is formed in the corresponding part as shown in FIG.

The cutout 4 may consist of a simple cutout that separates the sidewall 2b and the flange 2b, but in order to prevent the flange 2b from interfering with the expansion of the sidewall 2a, the cutout 4 is As shown, it is preferably formed with a relatively large opening.

In this case, the electron beam (B of FIG. 1) having escaped the effective area may be landed through the cutout 4 toward the fluorescent surface S side of the panel P, causing abnormal light emission. It can be blocked by electron shield: E).

That is, in most cases, the rim-shaped electron shield E is provided to prevent the glass electrons from entering the space between the frame F and the panel P. The cutout 4 is formed in the electron shield E. The above-mentioned problem can be solved by providing the shielding part 5 which shields ().

The operation of the present invention as described above will be described with reference to FIG. 6. First, as shown in (A), if the side wall 2a of the short side portion 2 is in a flat state, the amount of thermal expansion is simply proportional to its length. However, in the case where the bent portion 3 is provided as shown in (B), when the bent portion 3 is thermally expanded, the bent portion 3 not only extends the length itself, but also a gap between the bends is considerably larger than that in (A). It will indicate the expansion of direction.

Therefore, if the amount of formation of the gauze of the bent portion 3, that is, the bend, is set so that its thermal expansion amount is equal to the thermal expansion amount of the long side portion 1, there is no difference in the thermal expansion amount between the long and short side portions 1,2.

Here, the thermal expansion amount of the bent portion 3 is not linear like the long side portion 1 that is a straight line, so the above-described conditions of the same thermal expansion amount will be difficult to be easily satisfied, but the short and long edge portions may be provided by the provision of the bent portion 3. The difference in thermal expansion between (1, 2) can be reduced to be very small.

As such, the present invention increases the amount of thermal expansion of the short side portion by the bent portion, thereby reducing the difference in the amount of thermal expansion with the long side portion, thereby preventing frame distortion and shadow mask distortion, thereby realizing high quality color images. It works.

Claims (4)

In the frame supporting the shadow mask of the color tube, Forming at least a portion of the side wall 2a of the short side portion 2 of the frame F to form a bent portion 3 that increases the gauze. The shadow mask frame of the color brown tube characterized by the above. The method of claim 1, That the cutout portion 4 separating the side wall 2a and the flange 2b is formed on the flange 2b of the short side portion 2 corresponding to the portion where the bent portion 3 is formed. The shadow mask frame of the color brown tube characterized by the above. The method of claim 2, The space formed by the cutout 4 is shielded by the shield 5 of the electron shield E. The shadow mask frame of the color brown tube characterized by the above. The method of claim 1, The thermal expansion amount of the short side part 2 by the bending part 3 of the side wall 2a of the said short side part 2 is equal to the thermal expansion amount of the long side part 1 The shadow mask frame of the color brown tube characterized by the above.