JP2793197B2 - Color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a color picture tube, and particularly to a material having a low coefficient of thermal expansion (for example, amber material) for a shadow mask and iron for a mask frame. The present invention relates to an improvement in a color picture tube, and to a means for preventing color purity from deteriorating due to outside air temperature.

(Prior Art) It is known that about 80% of the energy of a shadow mask type color picture tube is consumed by the shadow mask when an electron beam strikes the shadow mask. As a result, the shadow mask undergoes thermal deformation, sometimes referred to as doming, during operation of the picture tube, sometimes entirely, and sometimes partially. This doming causes a so-called mislanding in which the positions where the electron beams impinge on the phosphor layer are different, causing color unevenness and making it impossible to reproduce colors properly.

To improve this doming, shadow mask
Those using a thermal expansion material such as an Fe-Ni alloy (amber material) and a Co-Fe alloy have been put to practical use. If these low thermal expansion materials are used, so-called landing changes are negligibly small even when the temperature of the shadow mask rises due to the impact of the electron beam, and mislanding does not occur, so that color unevenness does not occur.

Such a low expansion coefficient shadow mask is usually welded to an iron frame for cost reasons. In this case, the welding point is a horizontal axis, as shown in JP-A-59-203349. Usually, there are eight points on each of the vertical axis and the diagonal axis. In fact, only those having such a structure have been put to practical use.

(Problems to be Solved by the Invention) However, with the recent emergence of a large color picture tube, a new problem has been found in a picture tube using such a low expansion coefficient shadow mask. It is a problem that the color picture tube causes mislanding due to the environmental temperature. That is, if the temperature at the time of operating the color picture tube is high or low, mislanding may occur. This cause can be explained as follows with reference to FIG. In this figure, the positions of the support spring (5) and the stud pin (6) at normal temperature are omitted because the figure becomes complicated. Opening of shadow mask (3) at room temperature (3a)
The electron beam (4) passing through the
, And a correct beam landing can be obtained. However, when the environmental temperature rises, the temperature of the panel (1) also rises and thermally expands, so that the position of the phosphor (2a) changes to (2b). On the other hand, shadow masks
Since it hardly expands, the aperture (3a) does not change its position, and the electron beam (4) passing through it does not change its position. As a result, mislanding occurs by Δl. If a specific example is shown with a 32-inch picture tube, it is as follows. If the temperature at which the deflection yoke is mounted on the color picture tube and adjusted is 15 ° C., and the temperature at the time of operation is 35 ° C., the temperature difference ΔT is 20 ° C. The horizontal dimension of the screen of a 32-inch picture tube is about 305 mm measured from the center of the screen, and the thermal expansion coefficient α of the panel is about 1.0 × 10 ⁻⁵ / ° C., Δl = 305 (1.0 × 10 ⁻⁵ × 20) = 0.061. On the other hand, the elongation of the shadow mask is 1.0 × 10 ⁻⁶ or less, as shown in the science chronological table, for the amber material, and therefore is 1/10 or less of the panel. Therefore, a landing change of 0.05 mm or more occurs. The landing change of 0.05 mm is a considerably large amount for a color picture tube and easily leads to mislanding. Conversely, the operating temperature is 0 ° C or -10 ° C
In this case, a landing error in the opposite direction to that in FIG. 6 occurs. The mislanding caused by the panel temperature change due to the environmental temperature is so small that it does not become a problem in a conventional color picture tube using iron as a shadow mask material. This is because the coefficient of thermal expansion of iron is about 1.2 × 10 ⁻⁵ , which is not so different from that of the panel. In a picture tube using a low-expansion material for a shadow mask, and a large picture tube, a problem of a landing change particularly due to a change in panel temperature has appeared. A color picture tube using a low thermal expansion material such as amber material for a shadow mask shows much better characteristics than an iron mask in so-called local doming. Until now, there was no suitable one.

[Configuration of the invention]

(Means for Solving the Problems) The present invention solves the above-mentioned problem caused by the environmental temperature, and comprises a short shadow mask body made of a low thermal expansion material and a material having a higher thermal expansion coefficient than the shadow mask body. When the temperature of the picture tube envelope changes due to the difference between the thermal expansion amount of the shadow mask body and the thermal expansion amount of the mask frame, the shadow mask body is deformed mainly in the tube axis direction. At least a diagonal axis, a horizontal axis, and a welded portion for fixing the shadow mask body and the mask frame between the diagonal axis and the horizontal axis so as to move, and a diagonal axis and a horizontal axis of the skirt portion of the shadow mask body are provided. A color picture tube having a cut near the welded portion between the picture tubes to reduce the rigidity in the direction along the vertical axis of the picture tube.

(Operation) In a conventional amber mask tube (hereinafter referred to as a color picture tube using a low expansion coefficient material for a shadow mask), the welding point between the shadow mask and the mask frame is on the vertical axis and the horizontal axis. , And eight points on the diagonal axis, but in the present invention, they are provided at the horizontal axis and the diagonal axis and at the intermediate portion between them. Even if it is the middle part, it does not mean that it may be anywhere between the horizontal axis and the diagonal axis. When the shadow mask body and the mask frame are heated by the electron beam bombardment caused by operating the color picture tube, the short shadow mask caused by the difference between the thermal expansion amount of the shadow mask body and the thermal expansion amount of the mask frame is heated. The two are welded so that thermal deformation occurs at both short sides, particularly near the horizontal axis.

That is, as shown in FIG. 2, since the mask main body (3) and the frame (7) having different coefficients of thermal expansion are fixed by welding, the panel temperature changes due to the environmental temperature change, and the entire shadow mask becomes an electron beam. When the mask is heated by the projection, a difference in the amount of elongation (difference in the amount of thermal expansion) occurs between the mask body (3) and the frame (7) due to thermal expansion. Since the frame (7) is made of iron, the elongation amount x _{1 in} the horizontal axis direction (hereinafter simply referred to as X direction) and the vertical axis direction (hereinafter simply Y direction)
Elongation amount y ₁ both large that direction), the elongation of the mask body (3) extends quantity x ₂ in the X direction, Y direction elongation of y ₂
Both are small. Accordingly, when viewed in the X direction, as the mask body is slightly stretched by x _2, the elongation amount of the frame
x ₁ but is a form of pull much greater in the mask body skirt a second view in FIG When the right direction (the mask skirt portion thickness direction), since the mask skirt portion bends easily in this direction, the mask body And the difference in the amount of elongation of the frame is absorbed so as not to affect the effective curved surface.

However, when viewed in the vertical (Y-axis) direction, while the elongation amount y ₂ of the mask body is small, the elongation amount y ₁ frame is much larger, the difference Δy only elongation amount occurs. Therefore, as is apparent from FIG. 2, when the mask body and the frame having different thermal expansion amounts are welded at the positions indicated by the crosses, the frame is stretched more, so that the thin mask body is pulled by the frame. Cause deformation. The present applicants performed a computer simulation using the finite element method for this modified state, and found that when the environmental temperature rose and the panel temperature rose,
We found that the effective curved surface of the shadow mask deformed away from the phosphor screen. In particular, the deformation is such that the outermost peripheral portion near the horizontal axis is largely deformed and becomes smaller toward the center or the diagonal axis of the mask. With this deformation, the position of the opening of the shadow mask is moved in the outer peripheral direction to achieve a correct landing. Thus, the present application
The present invention shows a completely new idea of solving a new problem of mislanding caused by a change in panel temperature by skillfully utilizing deformation of a mask, which is usually a problem, due to thermal expansion. The movement away from the phosphor screen shifts the landing position of the electron beam in the peripheral direction, so that the change in the position of the phosphor can be corrected. Since the deformation in the effective plane is too large, an appropriate correction amount can be obtained by providing a notch or the like near the welding point to appropriately reduce the rigidity in the Y direction.

Further, the relationship between the position of the welded portion and the amount of deformation of the shadow mask was further examined by simulation. The size can be further reduced, and an appropriate shadow mask can be obtained.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. First
FIG. 1 is a diagram showing one embodiment of the present invention. The welding points of the shadow mask (3) and the mask frame (not shown) are on the vertical axis (50), on the horizontal axis (51), on the diagonal axis (52), and on the horizontal axis (51). ) And the diagonal axis (52) also have an intermediate welding point (60). FIG. 3 is an enlarged view of the vicinity of the intermediate welding point (60) viewed from the short side. Middle welding point (60)
There is a notch (9) in the vicinity of the notch (9), and the rigidity of the shadow mask skirt (8) in the vertical axis (Y) direction (left-right direction in FIG. 3) near the middle welding point is notched (9).
It is weakened compared to the case without.

FIG. 4 is a view showing the operation of the present invention, and is a cross-sectional view including the horizontal axis (51) of FIG. In this figure, as in FIG. 6, the positions of the stud pin (6) and the support spring (5) at room temperature are not shown in order to avoid complicating the drawing. In FIG. 4, the broken line indicates the position at normal temperature, and the solid line indicates the position at high temperature.

When the environmental temperature rises, the position of the phosphor changes from (2a) to (2b) because the temperature of the panel (1) rises and expands.
Since the shadow mask (3) moves away from the phosphor screen (2) as the panel temperature rises, the electron beam (4a) that has passed through the aperture (3a) and correctly hit the predetermined phosphor (2a) is , As the aperture moves to (3b),
Move as shown in (4b) and move to the position of (2b). That is, beam landing is maintained.

It was not initially clear why the shadow mask (3) moved away from the phosphor screen (2). From FIG. 4, since the skirt portion (8) is pulled in the “thickness direction” of the skirt portion (8) by the thermal expansion of the frame (7), it is easy to think that the effective surface of the shadow mask is also deformed. But in reality it is not. If so, a similar deformation should occur in a conventional amber mask tube having a welding point on the horizontal axis, resulting in the correction as shown in FIG.
It does not happen in reality. By providing the intermediate welding point (60), the characteristics with respect to the panel temperature change are greatly different. The present applicant has found the reason why the shadow mask (3) is deformed as shown in FIG. 4 by the analysis using the finite element method. As shown in FIG. 2, the difference Δ 熱 in the thermal expansion amount between the shadow mask (3) and the mask frame (7).
y (vertical component) because the frame (7) exerts a force on the skirt (8) of the shadow mask (3) in a direction parallel to the vertical axis (50). That is, the shadow mask (3) is pulled by the mask frame (7).

However, if the intermediate welding point (60) is provided directly on the skirt (8), the deformation in the effective plane of the shadow mask (3) becomes too large, so the cut (9) is made near the intermediate welding point. ) To reduce the rigidity of the portion in the direction along the vertical axis (50), so that an appropriate correction amount can be obtained. That is, the amount of correction can be adjusted by this notch, and the amount of correction can also be changed by the size of this notch. For example, if the deformation is too large, the amount of notch can be increased to further reduce the rigidity. Good. However, in this case, the size must be selected so as not to impair the formability of the press.

FIG. 5 shows another embodiment of the present invention, in which an intermediate welding point (61) is closer to the horizontal axis (51) than in the embodiment of FIG. With such a configuration, the difference Δy in the amount of thermal expansion between the shadow mask (3) and the mask frame (not shown) in the direction of the vertical axis (50) can be reduced, and more appropriate deformation of the shadow mask can be achieved. can get.

In the above description, the case where the panel temperature rises is described. However, when the panel temperature falls, the phosphor moves in the vertical axis direction and the shadow mask moves in the direction approaching the phosphor screen, so that similarly good beam riding can be achieved. Will be kept. In the above description, the welding points are 12 in total, but the welding points on the horizontal axis (51) may not be provided. It is desirable that there is no welding point between the diagonal axis (52) and the vertical axis (50).

Regarding the position of the welding point, conventionally, for example,
No. 481, but these are all for improving the doming phenomenon that occurs about 15 minutes after the start of operation in a color picture tube using an iron shadow mask, and the present invention The purpose and action are completely different. The present invention is an effect that appears for the first time in a combination of an amber mask and an iron frame.By providing a welding point between the horizontal axis and the diagonal axis and between them, the mask frame allows the skirt portion of the shadow mask to be parallel to the vertical axis. No one has ever thought of a way to pull the shadow mask in the effective plane away from the screen in any direction. As for the cut, there is Japanese Utility Model Publication No. 49-24218 and the like,
This also relates to a color picture tube using a shadow mask made of iron. The tongue-shaped portion of the skirt portion formed by the cut is formed with a cut in order to weaken the rigidity in the thickness direction. However, the present invention is different in that a notch is formed so that the portion to be welded can easily move in the vertical axis direction.

〔The invention's effect〕

According to the present invention, when a material having a thermal expansion coefficient of about 1/2 or less of iron, such as invar, is used for a shadow mask, and a color picture tube using iron is used as a mask frame, when a panel temperature changes due to an environmental temperature. Of the beam landing was prevented.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a shadow mask used in the color picture tube of the present invention, FIG. 2 is a partially enlarged view for explaining the operation of the shadow mask of FIG. 1, and FIG. FIG. 4 is a partial cross-sectional view for explaining the operation of the color picture tube of the present invention, FIG. 5 is a schematic front view of a shadow mask showing another embodiment of the present invention, and FIG. FIG. 4 is a partial cross-sectional view for explaining the operation of the color picture tube. (1) ... panel, (2) ... phosphor screen, (3) ... shadow mask, (4) ... electron beam orbit, (5) ... support spring, (6) ... stud pin, (7) ) ... Mask frame, (8) ... Skirt, (9) ... Incision, (50) ... Vertical axis, (51) ... Horizontal axis, (52) ... Diagonal axis, (60), (61) ... Middle welding point.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-203349 (JP, A) JP-A-62-2433 (JP, A) Jikai Sho 60-33743 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) H01J 29/07

Claims (1)

(57) [Claims] 1. A shadow mask body having a short shape made of a low thermal expansion material, a skirt portion of a peripheral portion of the shadow mask body, and a plurality of welds, which are fixed to each other and made of a material having a higher coefficient of thermal expansion than the shadow mask body. A color picture tube comprising a mask frame, wherein the difference between the amount of thermal expansion of the shadow mask body and the amount of thermal expansion of the mask frame causes the shadow mask body to be mainly used when the temperature of the picture tube envelope changes. At least a diagonal axis, a horizontal axis, and a welding portion for fixing the shadow mask body and the mask frame between the diagonal axis and the horizontal axis so as to deform and move in the axial direction, and a diagonal axis of a skirt portion of the shadow mask body. The collar is characterized by having a notch near the weld between the horizontal axis and the vertical axis of the picture tube to reduce the rigidity in the direction along the vertical axis. Image tube.