JPS61188836A - Color picture tube - Google Patents

Abstract

PURPOSE:To prevent deterioration of color purity due to welding by limiting the welding point with the shadowmask frame within two for one short side and two diagonal sections. CONSTITUTION:The shadowmask bodies 7-9 is made of low thermal expansion metal while the frame is made of common iron material where the shadowmask is welded to the inside of frame at three points on the long side while two points on the short side. Upon function of color picture tube, the frame will thermally expand to apply tensile force in the arrow direction through the welded points thus to vary the landing position of electron beam onto the fluorescent material, but since the welding points on short side and diagonal section is limited, outward tensile force of the shadowmask near the horizontal axis is weakened. Consequently, the difference of the variation of landing position of electron beam in horizontal direction near the horizontal axis and the diagonal axis is reduced resulting in cancellation of the deterioration of the color purality.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a shadow mask type color picture tube, and
;Relates to its shadow mask structure (-).

[Technical background of the invention and its problems The co-shadow mask type color picture tube is as shown in Figure 3 (1) (panel (1), funnel (2), electron gun (3)).
.

Inner surface of the panel (3 colors coated with phosphors (4)
).

It plays the role of color selection for the three electron beams emitted from the electron gun, and is composed of shadow mask structures (5) mounted on the inner surface of the panel (one facing each other at a predetermined interval).

As shown in FIG. 4, the shadow mask structure (5) has a large number of slit-like pores (6) for passing the electron beam. ), outside the shadow mask effective part (7)
``The outer edge of the shadow mask (8) located at the outer edge of the shadow mask (8)!The outer edge of the shadow mask (8) has a relatively strong structure, and the shadow mask skirt (9) is bent at a substantially right angle C. In order to attach the frame Ql welded and supported and the shadow mask to the inner surface of the panel (1) at a predetermined interval,
The frame Qll is composed of two fixed holders αυ. Further, as the material C of the shadow mask and the frame, an inexpensive iron material is generally used.

In a color picture tube having such a shadow mask structure (5), the three electron beams emitted from the electron gun (3) are electromagnetically deflected and then transferred to the shadow mask effective part (7) which plays a role in color selection. A predetermined phosphor (4), eg red, green, passes through the pore (6) of the upper lapel pin.

The phosphor that emits light on the back is emitted by colliding with the phosphor, but since the pores (6) of the shadow mask occupy the effective part of the mask (force C1 is 15 to 25 inches), the electron beam Most of the remaining part hits the non-opening part of the shadow mask effective part (7).As a result, the shadow mask effective part (7) is heated as a living body.For example, in a 20-inch color picture tube, Under operating conditions with an anode voltage of 25 KV and an anode current of 1200 μA, the central portion of the shadow mask effective area (7) is heated to about 70°C. When (-the shadow mask structure (5) thermally expands, the relative positional relationship between the pores (6) of the shadow mask structure (5) and the phosphor (4) changes, and the fluorescence of the electron beam The landing position on the body shifts, and in extreme cases, the color purity on the screen is significantly degraded.Thermal expansion of the shadow mask can generally be divided into two cases.

The first case is due to the temperature increase of the entire shadow mask, and as shown in FIG.
(8) , (91 and frame Ql are in the tube axis direction (Z
) thermally expands in the direction ζ1 perpendicular to ). In the second case, when the color picture tube is in operation), if there are localized bright areas on the screen, as shown in Figure 6 (:
Y, the effective part of the mask corresponding to the local portion (Y) where only the force is in the direction parallel to the tube axis direction (Z) Expansion C: As shown in Japanese Patent Publication No. 44-3547 C, the shadow masks (7), (8),
When mounting (9) facing the inner surface of the panel (1), between the frame α and the holder (11),
By interposing the bimetal, the temperature of the shadow mask structure (5) increases due to the impact of the electron beam. An effective proposal has been made to compensate by bringing the value closer to 1.

Since the thermal expansion ml in the second case is local thermal expansion during operation of the color picture tube, no effective compensation method has been found as in the case of the bimetal.

In order to suppress the local thermal expansion, Special Publication No. 42-25446
No. 1, JP-A No. 50-58977, and JP-A-Sho 50
-68650 (U) As shown, a proposal has been made to use a low thermal expansion material such as an amber alloy on the second side of the V shadow mask. The use of a low thermal expansion metal for the frame, which is expensive and heavy together with the shadow mask, leads to a significant increase in cost. It is preferable to use an inexpensive steel material for the bulky frame (-).

Only the shadow mask 1 - If the shadow mask structure is constructed using a low thermal expansion metal, the entire shadow mask structure is heated to a high temperature (for example, about 4
00°C) state (when the shadow mask made of the low thermal expansion metal and the frame made of iron material have different thermal expansions, the shadow mask is in the frame (tube axis C: perpendicular direction C; As a result, the shadow mask plastically deforms as shown in FIG.
Become more personable in the direction of the arrow. On the other hand, the shadow masks (7) to (9) C, which are made of a low thermal expansion material and are welded together at multiple locations C on the outer surface of the frame indicated by the marks C, do not change much, so the shadow masks are the same as those indicated by the arrows. direction (
- As a result of receiving tensile force from the entire outer surface of the frame, the shadow mask undergoes plastic deformation (as shown by the dotted line in FIG. 7(b)), resulting in a deterioration of color purity. As an effective method to prevent the deterioration of
It has been proposed in Japanese Patent Application No. 59-91793 C to weld the shadow mask made of the low thermal expansion material to the inside of the seven frames made of iron at a plurality of locations. That is, in Fig. 8 (the shadow mask body (7)
, (8) and (9) are made of a low thermal expansion metal such as an amber alloy containing Ni36, while the frame is made of a general inexpensive iron material, and the shadow mask is generally indicated by an x mark inside the frame. 8 locations (1 location on each short side, 1 location on each long side).

They are held together by welding at one location on each diagonal. When the shadow mask structure is placed in a high temperature state during the manufacture of a color picture tube in FIG. 8(a), the frame made of general iron material expands thermally. The frame applies a tensile force to the shadow mask in the direction shown by the arrow in the figure through the welded joint between the shadow mask and the frame, and the shadow mask deforms as shown by the dotted line in Fig. 8(b). However, since the tensile force applied to the shadow mask main body C is limited to a narrow area near the welded joint, the deformation of the shadow mask is limited to the shadow mask skirt portion (9) (
However, when the tensile force is fjIc7, it is extremely weak, so when the temperature is returned from a high temperature state to room temperature, it can almost recover to its original shape.

On the other hand, when the color picture tube is in operation, the seven beams thermally expand and apply a tensile force to the shadow mask in the direction C shown by the arrow in FIG. This thermal expansion occurs during the manufacturing of the color picture tube (the thermal expansion during the manufacture of the color picture tube) is small, so it does not deform the effective part of the shadow mask, but as the shadow mask is pulled outward, the landing position of the electron beam on the phosphor changes. is displaced, leading to deterioration of color purity.Specifically, in the case of a shadow mask C having slit-like pores, the color purity l has almost no effect on the displacement of the shadow mask in the vertical axis direction. No, but displacement C in the horizontal axis direction - significant C
: Degrades color purity. Furthermore, the amount of landing that is displaced in the horizontal axis direction is different near the diagonal axis and near the horizontal axis due to thermal expansion of the frame. For example, as shown in Figure 8 (
:Short side 1ill 3t! In a 15-inch color receiver tube with slit-like pores at location A, 3 locations on the long side, and welded joint locations, the anode voltage is 23, and the anode current is 8.
After operating for 90 minutes at 50/jA, the change in the landing position of the electron beam in the horizontal axis direction is approximately 20 μm more near the horizontal axis than near the diagonal axis. This is because the pulling force on the frame is stronger near the horizontal axis than near the diagonal axis.This deterioration can be compensated for by interposing a bimetal between the frame and the holder. I can't.

[Object of the Invention] The present invention has been made in view of the above points, and the present invention has been made in view of the above points. The purpose is to suppress deterioration of purity.

[Summary of the Invention] The present invention provides that when the shadow mask made of the low thermal expansion material is inserted into the inner side of the frame made of iron material and welded together, the short side of the shadow mask with the frame is The number of welded joints should be one short side and two diagonal parts sandwiching this short side. Embodiment of the Invention The embodiment of the invention will be explained in detail below using the drawings. Fig. 1 shows an embodiment of the invention. As shown in Figure 1C, there is a shadow mask main body having slit-like pores (
7), (8), and (9) are, for example, Ni 36%
The frame is made of a low thermal expansion metal such as an amber alloy containing aluminum alloy, while the frame is made of a general inexpensive iron material. When the color picture tube is in operation, the frame made of general iron material expands thermally and passes through the welded connection point between the shadow mask and the frame as indicated by the arrow in the figure. A tensile force is applied in the direction C shown in .This changes the landing position of the electron beam on the phosphor, but compared to Fig. 8, there are fewer welded joints on the short side and diagonal.
The force that pulls the shadow mask outward becomes weaker near the horizontal axis. On the other hand, near the diagonal axis, originally the short side (-vertical direction C
Since the pulling force is weak, it does not change much.

Therefore, the difference in the change in the landing position of the Hiroko beam in the horizontal axis direction near the horizontal axis and near the diagonal axis becomes extremely small, eliminating deterioration in color purity.

For example, in the above-mentioned 15-inch color picture tube, if the C unit is welded at one location on each short side and one location on each diagonal as shown in Figure 8, the areas near the diagonal axis and the area near the horizontal axis during operation. Although the difference in the change in the landing position of the electron beam was 30-m, as shown in FIG.

Fig. 2 shows another embodiment of the present invention. The welding point is shifted to the long side 1i11+center Cyu.Thermal expansion of the frame when the color picture tube is operated C: The tensile force against the shadow mask due to the thermal expansion C: is as shown by the arrow in Fig. 2. Even in the case (-), the outward pulling force near the horizontal axis is weaker than in the case shown in Figure 8; The difference in the change in the landing position of the electron beam in the horizontal axis direction becomes extremely small.

As described above, the welding points of the short side of the shadow mask made of a low thermal expansion material and the frame made of general iron material, and the diagonal parts that sandwich this short side are 21i! Below (if you do)
The thermal expansion of the frame during operation of the collar tube (Y) can weaken the outward pulling force on the shadow mask near the horizontal axis. Therefore, the horizontal axis direction of the electron beam near the horizontal axis and near the diagonal axis can be reduced. This reduces the difference in changes in landing position and eliminates the deterioration of color purity.In addition, in shadow masks with slit-like pores, displacement in the vertical axis direction has almost no effect on color purity, so The effect of the welded joint on the short side is small.

[Effects of the Invention] As explained above, according to the present invention, when a shadow mask structure is constructed by using a low thermal expansion metal only for the shadow mask, C: without significantly changing the structure, Deterioration of color purity due to thermal deformation during color tube operation can be effectively suppressed.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing a combination of a shadow mask and a frame according to an embodiment of the present invention, FIG. 2 is a schematic plan view showing a combination of a shadow mask and a frame according to another embodiment of the present invention, and FIG. A partially cutaway perspective view showing a schematic configuration of a color picture tube having a shadow mask, FIG. 4 is a configuration diagram of the shadow mask structure, and FIGS. 5 and I@6 are diagrams for explaining thermal expansion of the shadow mask structure. Schematic diagram, Figure 7 (,) and Figure 7
Figure (b) is a schematic plan view and cross-sectional view for explaining the thermal expansion effect when the shadow mask and frame are combined, and Figure 8 (-
) and FIG. 8(b) are a schematic plan view and a sectional view for explaining the thermal expansion effect when the U shadow mask and the frame are combined. (l)... Panel (21... Funnel (3)... City, subgun (4)... Fluorescent body (
5)...Color selection electrode (6)...Pore (force...
・Shadow mask effective part (8)...Shadow mask outer edge part (9)...Shadow mask skirt part 00)...Frame Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 (α) Figure 7 <b> U Figure S Figure (a) Figure 8 (b)

Claims (1)

[Claims] The shadow mask is composed of a substantially rectangular main surface having a large number of slit-shaped through holes and a skirt portion bent around the periphery of the main surface, and a frame supporting the shadow mask by the skirt portion. and a color picture tube using a shadow mask structure in which the frame is made of metals having different coefficients of thermal expansion, and the shadow mask is welded to the inside of the frame at a plurality of locations, the short side of the shadow mask to the frame; and a color picture tube characterized in that the number of welding points on the diagonal portions is two or less on one short side and two diagonal portions sandwiching the short side.