JP2645042B2 - Color picture tube - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a shadow mask type color picture tube, and more particularly to a panel.

(Prior Art) A shadow mask used in a shadow mask type color picture tube is one of important members having a color selecting function. That is, a rectangular panel having a large number of regularly arranged openings formed at regular intervals with respect to the inner surface of a curved panel having a rectangular frame in which phosphors that emit multicolor light are separately applied. A shadow mask including an effective curved surface portion having a frame is arranged. A plurality of electron beams from the electron gun arranged at the neck of the tube are focused, accelerated, and scanned by scanning the rectangular area under the deflecting action, and pass through the through holes of the shadow mask. The color of the image is displayed by causing the phosphor to emit light. Therefore, a specific relative positional relationship is required between the through-hole group of the shadow mask and the corresponding phosphor group in order to make a so-called beam landing accurate, and this relative relationship is always maintained during the operation of the picture tube. It must be kept constant. More specifically, the distance (q value) between the shadow mask and the phosphor screen must always be within a certain allowable range. However, the shadow mask type color picture tube has an operation amount of the electron beam which passes through the through hole of the shadow mask is 1/3 or less due to the principle of operation, and the remaining electron beams impinge on the non-hole portion of the shadow mask. The impinging electron beam is converted into thermal energy and heats and expands the shadow mask (doming phenomenon).
As a result, in general, a shadow mask made of a material containing iron as a main component changes its position due to thermal expansion, and when the q value changes to outside an allowable range, the color purity deteriorates due to a deviation of a beam landing position. Will be. The magnitude of the mislanding caused by the thermal expansion of the shadow mask greatly varies depending on the image pattern on the screen and the duration of the pattern.

Of these, the mislanding caused by heating from the shadow mask to the mask frame with a large heat capacity supporting the shadow mask takes a relatively long time,
As disclosed in JP-A-44-3547, it is effective to perform a correction by interposing a bimetal in a spring supporting structure attached to a mask frame. However, mislanding occurring in a relatively short time, for example, mislanding due to local doming due to local high-brightness display is a serious problem.

Using a signal that generates a rectangular window-like pattern for the mislanding that occurs in a short time, and changing the shape and position of the window-like pattern and measuring the magnitude of the mislanding, the screen as shown in Fig. 5 is obtained. When there is a large current beam pattern (5) over almost the entire screen (6), the mislanding is relatively small. However, as shown in FIG. 6, the largest mislanding occurs when the relatively elongated raster pattern (5) of the large current beam is slightly offset from the left and right ends of the contour of the screen (6). This experimental fact can be easily understood for the following reasons.

First, since the television receiver is designed so that the average anode current of the picture tube does not exceed a certain value, the current per unit area of the shadow mask in a large window-like pattern as shown in FIG. The temperature rise is smaller than in FIG.

Second, when the pattern is in the center of the screen, mislanding is unlikely to occur even if the shadow mask is thermally deformed.
The degree to which thermal deformation of the shadow mask appears as mislanding on the screen increases as it moves from the center to the left and right ends. However, since the shadow mask is fixed to the mask frame near the left and right edges of the screen, the deformation itself is small. Therefore, the largest mislanding occurs in the case of the pattern located at the position shown in FIG.

FIG. 7 is a view for explaining a state of mislanding when there is a pattern (5) as shown in FIG. That is, stud pins (12) are provided on the inner side wall of the panel (124).
5) The shadow mask (136) is opposed to the spring support structure (135) via the mask frame (134). Now, the low brightness, i.e. the shadow mask when operating in a small state of the electronic density (136) is in position (a _1), the electron beam position (c ₁₎ through the holes (137) (14
2) is correctly landing on the corresponding phosphor (130). When a locally high-luminance pattern as shown in FIG. 6 is projected from this state, use a shadow mask (136).
Is locally expanded by heating and is displaced to the position (a ₂ ), and the through hole (137) is displaced from the position (b ₁ ) to (b ₂ ). As a result, the electron beam (142) passing through the through hole (137) Is displaced from the position (c ₁ ) to (c ₂ ) and does not land properly on a predetermined phosphor.

(Problems to be Solved by the Invention) In recent color picture tubes, those having a flatter face plate have become mainstream, and such a color picture tube naturally has a flat shadow mask. Mislanding due to thermal deformation of the shadow mask increases. On the other hand, Japanese Patent Laid-Open No. 61-1635 discloses a method of correcting mislanding by changing the shape of a shadow mask.
No. 39, JP-A-61-884237 and the like. However, if the face plate becomes flat, it is not enough to consider only the shape of the shadow mask.
This correction had limitations.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides an X-axis (see FIG. 1) section of a panel effective portion in a direction parallel to the Y-axis (short axis) -Z-axis (tube axis) in the panel effective curved surface. The difference between the panel thickness on the long axis) and the panel thickness near both ends in the Y-axis direction having a thickness larger than this panel thickness is maximized in the middle of the panel effective curved surface in the X-axis direction. Color picture tube.

(Operation) In such a color picture tube, since the face plate panel has a shadow mask along the inner surface of the panel, it is possible to effectively suppress thermal deformation of the shadow mask despite being flat. Becomes

(Embodiment) FIGS. 1 to 4 illustrate an embodiment of the present invention. In FIG. 3, the color picture tube (20) has a glass envelope (22), which has a substantially rectangular panel (24), a funnel (26) and a neck (28). ). The inner surface of the panel (24) is a concave surface that is curved into a spherical surface, and a fluorescent screen (30) in which phosphor stripes of three colors are regularly arranged is provided on the inner surface. These phosphor stripes are red, green,
Each of the blue light emitters is arranged alternately and sequentially. Usually, the direction of the stripe is the vertical direction shown in FIG.
In the axial direction. A shadow mask structure (32) is mounted close to the screen (30). The shadow mask structure (32) comprises a rectangular mask frame (34) and a curved shadow mask (36) having a large number of through-holes.
A stud pin (25) embedded in a skirt portion of the panel (24) is elastically held by an elastic support member (35). The dashed rectangular area (33) shown in FIG. 4 is an effective area for projecting an image on the panel.

An in-line type electron gun (40) is attached to the neck (28), and three electron beams (42) are emitted, and the fluorescent screen (3) passes through the through holes of the shadow mask (36).
Fire at 0). These electron beams (42) are deflected by a deflection yoke (44) attached to the outer wall of the funnel (26), and scan the shadow mask (36) and the fluorescent screen (30). If the center axis of the tube axis, that is, the center of the screen (30) in the direction perpendicular to the screen is the Z axis, the X axis is supported at a position passing vertically through the panel center O. As shown in FIG. 4, the panel is set with the major axis X axis in the horizontal direction and the minor axis Y axis in the vertical direction with the panel center O as the base point.

1 and 2 illustrate an embodiment of the present invention in more detail. In FIG. 1, in the panel effective area (33), of the section (52) passing through the panel center (O), of the thickness (h ₁ ) on the X-axis in the Y-axis direction end of the section parallel to the Y-axis and the Z-axis. The difference in wall thickness (H ₁ ) is determined by the difference
The difference between the thickness (h ₂ ) on the X-axis of the Z-axis parallel cross section (53) and the thickness (H ₂ ) at the end in the Y-axis direction is smaller. The difference between the thickness (h ₃ ) on the X-axis of the Y-axis-Z-axis parallel cross section (54) and the thickness (H ₃ ) of the end in the Y-axis direction at the effective diameter end (P) in the X-axis direction is Similarly, the difference between the thickness (h ₂ ) on the X-axis of the cross section (53) of the intermediate portion and the thickness (H ₂ ) at the end in the Y-axis direction is smaller.

That is, H ₂ −h ₂ > H ₁ −h ₁ and H ₂ −h ₂ > H ₃ −h ₃ . This relationship along the X axis is the second
FIG.

In the dotted line (57) showing the conventional example, X = O (YZ section)
Has the largest thickness difference, and the thickness difference gradually decreases toward the periphery of the X-axis. On the other hand, the curve (56) of the present invention has the largest thickness difference at the middle part.

Usually, the outer surface of the panel has a number of curved surfaces such as a spherical shape, a cylindrical shape, or a substantially curved surface in the peripheral portion in consideration of visibility, but is generally flat due to the problem of visibility. After determining these outer surface shapes, the present invention reduces the radius of curvature of the YZ parallel cross section of the inner surface of the panel at the X-axis intermediate portion where the mislanding due to thermal deformation of the shadow mask is greatest due to the thickness distribution of the panel. Things. When the outer surface is constant, the X of the inner surface is efficiently
In order to reduce the radius of curvature of the YZ parallel plane at the intermediate portion of the axis, the thickness of this section on the X-axis may be reduced and the thickness of the peripheral portion may be increased. According to the present invention, this is efficiently performed without reducing the strength or increasing the weight of the panel as viewed from the entire panel.

In the case of the above structure, even if the outer surface of the panel is flat, the radius of curvature of the YZ parallel section of the inner surface of the panel at the middle portion of the X axis can be reduced from the thickness distribution.
On the other hand, the distance between the shadow mask and the inner surface of the panel (q value)
Must be constant. For this purpose, it is necessary to make the shape of the shadow mask substantially similar to the inner surface of the panel. Therefore, the largest thermal deformation of the shadow mask, X
The radius of curvature of the YZ parallel section at the shaft intermediate portion can be reduced. For this reason, even when the outer surface of the panel is flat, mislanding due to thermal deformation of the shadow mask can be corrected most efficiently.

As an example, in the case of FIG. 2, the mislanding due to the thermal deformation of the shadow mask could be improved by about 15% when the curve (56) was used in the example of a 30-type 110 ° deflection tube.

Also, the valve strength does not cause any problematic deterioration at the level of the example shown in FIG.

〔The invention's effect〕

As described above, according to the present invention, even in a color picture tube having a flat face plate, the shadow mask can be formed only by partially changing the curved surface shape without largely changing the structure of the shadow mask or panel. Deterioration of color purity due to local thermal deformation can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an effective curved surface portion of a panel in an embodiment of the present invention, and FIG. 2 is a curve diagram showing a difference between a panel thickness on an X-axis and a panel thickness on an end portion in a Y-axis direction. FIG. 3 is a longitudinal sectional view of one embodiment of the present invention, FIG. 4 is a plan view seen from the panel side of FIG. 3, and FIG. 5 is a schematic view showing an example of a projected pattern on a screen of a color picture tube. FIG. 6 is a schematic plan view showing another example of the projected pattern on the screen of the color picture tube;
FIG. 7 is a schematic diagram for explaining local thermal deformation of the shadow mask caused when the pattern of FIG. 6 is projected. (5) Projection pattern, (6) Screen, (22) Envelope, (24), (124) Panel, (26) Funnel, (28) Neck , (30)… fluorescent screen, (32)… shadow mask structure, (33)… effective area of panel, (34), (134)… mask frame, (35), (135)… elasticity Member, (36), (136) ... shadow mask, (40) ... electron gun, (42) ... electron beam, (52), (53), (54) ... cross section, (56) ... Curve, (57) ... dotted line.

Claims (1)

(57) [Claims] 1. A panel having a substantially rectangular effective curved surface, a fluorescent screen formed on an inner surface of the panel,
In a color picture tube provided with a curved shadow mask having an effective curved surface formed with a large number of through-holes through which electron beams pass, a Y axis (short axis) -Z axis (tube axis) in the panel effective curved surface Panel thickness on the X axis (long axis) in a cross section parallel to
A color picture tube characterized in that the difference from the panel thickness near both ends in the Y-axis direction, which is larger than the panel thickness, is greatest at the middle portion in the X-axis direction of the effective curved surface of the panel.