Color cathode ray tube
View Patent ↗A color cathode ray tube in which beam landing errors caused by non-uniform thermal expansion of a shadow mask are corrected is provided such that color purity is improved. The color cathode ray tube in accordance with the present invention comprises a panel having a phosphor screen formed on an inner surface thereof, a shadow mask having a faceplate portion and a peripheral skirt portion bent back from the faceplate portion and a frame joined to the skirt portion, wherein a height of the skirt portion is less than or equal to 12 mm for substantially the entire skirt portion, and a plurality of holes are perforated at the skirt portion.
1. A color cathode ray tube comprising:
a panel having a phosphor screen formed on an inner surface thereof;
a shadow mask having a faceplate portion and a skirt portion bent back from the faceplate portion; and
a frame joined to the skirt portion of the shadow mask, wherein a height of the skirt portion is less than or equal to 12 mm for substantially the entire skirt portion and a plurality of holes are perforated at said skirt portion.
2. The color cathode ray tube of claim 1 , wherein said holes are perforated at a part of the skirt portion which is opposite to the frame.
3. The color cathode ray tube of claim 1 , wherein an edge line of said skirt portion curves toward a front face side of said shadow mask.
4. The color cathode ray tube of claim 3 , wherein a length of the edge line of said skirt portion, which is farther from the front face side than the edge line of said frame is less than or equal to ½ of the overall length of the edge line of said skirt portion.
5. The color cathode ray tube of claim 1 , wherein said skirt portion includes a protrusion having a welding point at which to weld said frame.
6. The color cathode ray tube of claim 5 , wherein a notch is cut at an edge of said protrusion.
7. The color cathode ray tube of claim 5 , wherein a hole is perforated at said protrusion.
8. The color cathode ray tube of claim 1 , wherein said plurality of holes are opened from a front face side to a rear face side of said skirt portion.
9. The color cathode ray tube of claim 1 , wherein said shadow mask is made of aluminum killed material.
10. The color cathode ray tube of claim 1 , wherein an electron beam reflective material is coated on a back plate surface of said shadow mask.
11. The color cathode ray tube of claim 1 , wherein an outer surface of said panel is substantially flat.
12. The color cathode ray tube of claim 1 , wherein at least 65% of the overall skirt portion at a long side of the faceplate portion of said shadow mask is less than or equal to 12 mm.
13. The color cathode ray tube of claim 1 , wherein at least 60% of the overall skirt portion at a short side of the faceplate portion of the shadow mask is less than or equal to 12 mm.
14. The color cathode ray tube of claim 1 , wherein a ratio of areas of the faceplate portion to the skirt portion of the shadow mask is not less than d 2 /(d+24) 2 and no greater than 1, wherein d is the diagonal length of the faceplate portion of the shadow mask.
15. The color cathode ray tube of claim 1 , wherein a maximum length of a part of said skirt portion which is opposite to said frame is less than or equal to 10 mm.
16. The color cathode ray tube of claim 1 , wherein a length of said skirt portion is in a range of 3 mm to 10 mm.
17. The color cathode ray tube of claim 1 , wherein said plurality of holes are located at a part of said skirt portion which is not opposite to said frame.
18. The color cathode ray tube of claim 1 , wherein a ratio of a height Ho of a part of said skirt portion which is opposite to said frame and a height H of said skirt portion, i.e., Ho/H, is less than or equal to 0.8.
19. The color cathode ray tube of claim 18 , wherein the ratio Ho/H is less than or equal to 0.5.
20. A color cathode ray tube comprising:
a panel having a phosphor screen formed on an inner surface thereof;
a shadow mask having a faceplate portion and a skirt portion bent back from the faceplate portion; and
a frame joined to the skirt portion, wherein
said skirt portion includes a protrusion having a welding point at which to weld said frame, and
a ratio of a height Ho of a part of said skirt portion which is opposite to said frame and a height H of said skirt portion, i.e., Ho/H, is less than or equal to 0.8.
21. The color cathode ray tube of claim 20 , wherein the ratio Ho/H is less than or equal to 0.5.
22. The color cathode ray tube of claim 20 , wherein said shadow mask is made of aluminum killed material.
23. The color cathode ray tube of claim 20 , wherein an electron beam reflective material is coated on a back plate surface of said shadow mask.
24. The color cathode ray tube of claim 20 , wherein an outer surface of said panel is substantially flat.
25. The color cathode ray tube of claim 20 , wherein a plurality of holes are perforated at said skirt portion.
26. The color cathode ray tube of claim 20 , wherein a plurality of holes are provided at part of said skirt portion which is opposite to said frame.