JP3396497B2 - Color picture tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly to an improved structure for fixing a mask frame attached to the periphery of a shadow mask to an internal magnetic shield. To a color picture tube. 2. Description of the Related Art Generally, as shown in FIG. 7, a color picture tube has an envelope composed of a panel 1 and a funnel 2 having a funnel shape. A phosphor screen 3 made of a three-color phosphor layer that emits light is formed, and a shadow mask 4 is arranged inside the phosphor screen 3 so as to face the phosphor screen 3. This shadow mask
4 is a mask body having a large number of electron beam passage holes 5
And a mask frame 6 attached to the periphery of the mask body 5. As shown in FIG. 8, the mask frame 6 is formed in an L-shaped cross section having an inwardly projecting portion 8 at one end of a side wall 7. Furthermore this shadow mask 4
An internal magnetic shield 9 for shielding an electron beam emitted from an electron gun from an external magnetic field such as terrestrial magnetism is mounted on the mask frame 6 inside the large diameter portion of the funnel 2. Normally, the mask frame 6 and the internal magnetic shield 9 are made of a magnetic material such as mild steel, and have a black oxide film formed on the surface thereof. The mask frame 6 and the internal magnetic shield 9 are formed on respective opposing surfaces such as the inner projecting portion 8 of the mask frame 6 and the mounting surface 10 of the internal magnetic shield 9 facing the inner projecting portion 8. An elastic clip 13 or the like is inserted into the plurality of openings 12 (only the openings of the mask frame are shown in FIG. 8) and mechanically fixed, or the inner projection 8 of the mask frame 6 and the inner magnetic shield are fixed. 9 and is fixed by fixing means such as welding at a plurality of locations. [0004] However, when the internal magnetic shield 9 is attached to the mask frame 6 as described above, it is relatively firmly fixed in the vicinity of the fixing point by the elastic clip 13 or welding.
On the opposing surface other than the vicinity of the fixed point, only contact is made, so that impact or vibration is applied to the color picture tube, and when the vibration is transmitted to the shadow mask 4 or the internal magnetic shield 9, the opposing surfaces are rubbed by friction. The surface is scratched, the black oxide film peels off, and the peeled oxide film causes problems such as deterioration of withstand voltage characteristics and clogging of an electron beam passage hole of the shadow mask 4 to cause a screen defect. [0005] As described above, the internal magnetic shield disposed inside the large diameter portion of the funnel of the color picture tube is fixed to the mask frame of the shadow mask by mechanical or welding. It is fixed at a plurality of places by means. Therefore, when impact or vibration is applied to the color picture tube, and the vibration is transmitted to the shadow mask or the internal magnetic shield, each of the opposing surfaces is damaged by friction, and the black oxide film on the opposing surface is peeled off. Due to the oxide film, there is a problem that the withstand voltage characteristic deteriorates and a screen defect occurs due to clogging of an electron beam passage hole of the shadow mask. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Even when impact or vibration is applied to a color picture tube and the vibration is transmitted to a shadow mask or an internal magnetic shield, the mask frame or the internal magnetic shield is not affected. An object of the present invention is to reduce peeling of a black oxide film of an internal magnetic shield, thereby reducing screen defects due to deterioration of withstand voltage characteristics and clogging of an electron beam passage hole of a shadow mask. [0007] A color picture tube in which a mask frame attached to the periphery of a mask body of a shadow mask and an internal magnetic shield are fixed at a plurality of fixing points between opposing surfaces. In the above, a recess was formed in at least one of the opposing surfaces of the mask frame and the internal magnetic shield to form a gap between the opposing surfaces other than the fixed point. As described above, when at least one of the opposing surfaces of the mask frame and the internal magnetic shield is formed with a concave portion forming a gap between the opposing surfaces other than the fixed point, the mask frame and the internal magnetic shield are formed. The contact area of the opposing surface with the body can be reduced, and even when vibration is transmitted, peeling of the black oxide film due to friction can be reduced. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a color picture tube as one embodiment of the present invention. This color picture tube has a substantially rectangular panel 1 provided with a skirt portion 20 on the periphery and an envelope composed of a funnel-shaped funnel 2, and the inner surface of the panel 1 has
A phosphor screen 3 made of a three-color phosphor layer that emits blue, green, and red light is formed, and a substantially rectangular shadow mask 21 is disposed inside the phosphor screen 3 so as to face the phosphor screen 3. The shadow mask 21 has a substantially rectangular mask body 22 having a large number of electron beam passage holes formed therein, and a cross section L having a side wall and an inner protruding portion attached to a peripheral portion thereof.
A plurality of resilient supports 24 attached to the side walls of the mask frame 23 are engaged with a plurality of stud pins 25 fixed to the skirt portion 20 of the panel 1. By doing so, it is supported inside the panel 1. On the other hand, in the neck 26 of the funnel 2,
An electron gun 28 for emitting three electron beams 27 is provided.
Further, the electron gun 28 is placed inside the large diameter portion 29 of the funnel 2.
An internal magnetic shield 30 is arranged to shield the three electron beams 27 emitted from the magnetic field from an external magnetic field such as terrestrial magnetism. The mask frame 23 and the internal magnetic shield 30 are made of a magnetic material such as mild steel, and have a black oxide film formed on the surface. And these mask frames
23 and the internal magnetic shield 30 are shown in FIGS.
As shown in FIG.
A plurality of openings 34 and 35 are formed on each of the opposing surfaces such as the mounting surface 33 of the internal magnetic shield 30 facing the inner protrusion 32, and the elastic clips inserted into the respective openings 34 and 35 It is mechanically fixed by 36. Further, in the mask frame 23 of this example, a concave portion 37 composed of a groove having an arc-shaped cross section is formed between the openings 34 of the inner projecting portion 32, and as shown in FIG. The mounting surface 33 of the 30 has its recess 37
Is covered. By the way, as described above, the mask frame 23
When the internal magnetic shield 30 is fixed with the configuration, the opposing surfaces of the mask frame 23 and the internal magnetic shield 30
In the vicinity of the openings 34, 35 fixed by the 36, that is, in the vicinity of a plurality of fixing points by the elastic clip 36, it is fixed by being relatively in contact with honey, but between the fixing points, it does not contact very closely,
When vibration is transmitted to the mask frame 23 and the internal magnetic shield 30, friction occurs. However, in the color picture tube of this example, since the concave portion 37 is formed between the plurality of openings 34 of the mask frame 23, a non-contact portion is formed between the openings 34 and 35, and the contact surface of each opposing surface is formed. The area is reduced. As a result, even if vibrations are transmitted to the mask frame 23 and the internal magnetic shield 30, damage due to friction and peeling of the black oxide film are reduced, the withstand voltage is reduced due to the peeling of the black oxide film, and the shadow mask 21 is damaged. Image defects due to clogging of the electron beam passage holes can be reduced. Next, some modifications will be described. In the above embodiment, the case where the mounting surface of the internal magnetic shield is fixed so as to cover the recess formed in the overhang portion of the mask frame has been described. However, as shown in FIG. Alternatively, the mounting surface 33 of the internal magnetic shield 30 may be fixed so as to cover, for example, only one side of the concave portion 37 of the inner projecting portion 32 of the mask frame 23, or as shown in FIG. The overhang 32 may be fixed so as to cover only the center of the recess 37. Even with such fixing, the same effects as in the above embodiment can be obtained. In the above embodiment, a concave portion having an arc-shaped cross section is formed in the projecting portion on the inner side of the mask frame. This concave shape forms a non-contact part between the mounting surface of the internal magnetic shield. What is necessary is just a thing, for example, FIG.
As shown in (c), the concave portion 37 may have another shape such as a triangular, rectangular, or W-shaped cross section. In the above embodiment, the concave portion is formed in the projecting portion on the inner side of the mask frame. However, the concave portion 37 may be formed on the mounting surface 33 of the internal magnetic shield 30 as shown in FIG. . Although the drawings show the case where the concave portion 37 having an arcuate cross section is formed, the shape of the concave portion 37 is not limited to the arcuate cross section also in this case, and may be formed into various shapes. Further, in the above-described embodiment, a continuous concave portion is formed between the openings of the inner projecting portion of the mask frame.
Alternatively, as shown by 37a and 37b in FIG. According to the present invention, when at least one of the opposing surfaces of the mask frame of the shadow mask and the internal magnetic shield is provided with a concave groove for forming a gap between the opposing surfaces other than the fixed point, the contact between these opposing surfaces can be achieved. Even if vibration is transmitted to the mask frame or internal magnetic shield, the area can be reduced, and damage due to friction and peeling of the black oxide film can be reduced. Image defects due to clogging of the electron beam passage holes can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a view showing a configuration of a color picture tube which is an embodiment of the present invention, and FIG. 1 (b) is a view showing a structure of a mask frame of the shadow mask. FIG. FIG. 2A is a view showing a mounting structure at a fixed point between the mask frame and the internal magnetic shield, and FIG. 2B is a view showing a mounting structure at a position other than the fixed point. FIGS. 3 (a) and 3 (b) are views showing different mounting structures except for a fixing point between a mask frame and an internal magnetic shield. FIGS. 4 (a) to 4 (c) are diagrams showing further different mounting structures except for the fixing points of the mask frame and the internal magnetic shield. FIG. 5 is a view showing another different mounting structure other than the fixing point between the mask frame and the internal magnetic shield. FIG. 6 is a diagram showing a different structure of a mask frame. FIG. 7 is a diagram showing a configuration of a main part of a conventional color picture tube. FIG. 8 is a diagram showing the structure of the mask frame. [Description of Signs] 1 ... Panel 2 ... Funnel 3 ... Phosphor Screen 21 ... Shadow Mask 22 ... Mask Body 23 ... Mask Frame 30 ... Internal Magnetic Shield 32 ... Inner Overhang 33 ... Mounting Surface 34 ... Aperture 35 ... Opening 36 ... Elastic clip 37 ... Recess

Claims (1)

(1) Claims 1. A mask frame attached to a peripheral portion of a mask body of a shadow mask and an internal magnetic shield are fixed by a plurality of fixing points between respective opposing surfaces. In the color picture tube, the mask frame and the internal magnetic shield are provided on the respective opposing surfaces .
To any color that the facing surface of the concave portion is provided in the circumferential direction to the projecting direction away from the pair facing surfaces groove-shaped, and forming a gap by the recess between the opposed face other than the fixed point Picture tube.