Shadow mask having slotted skirt portion
View Patent ↗A cathode ray tube comprises a panel; a funnel engaged to the panel for forming a vacuous space; and a shadow mask supported in the cathode ray tube by being fixed to a mask frame and including an effective surface having a plurality of electron beam passing holes at a center thereof, an ineffective surface formed at a periphery of the effective surface and not having the electron beam passing holes and a skirt portion extended from the ineffective surface towards a vertical direction thereof and welded to the mask frame. In the cathode ray tube, a slot of a predetermined size is formed between welding points by which the skirt portion is welded to the mask frame, and a height of the slot from an end of the skirt portion is higher than a height of the welding points, thereby reducing a doming effect of the shadow mask, reducing a mis-landing which the electron beam does not land to a precise landing point, and thus preventing a color purity of a screen from being deteriorated.
1. A cathode ray tube comprising:
a panel;
a funnel engaged to the panel for forming a vacuous space; and
a shadow mask supported in the cathode ray tube by being fixed to a mask frame and including an effective surface having a plurality of electron beam passing holes at a center thereof, an ineffective surface formed at a periphery of the effective surface and not having the electron beam passing holes and a skirt portion extended from the ineffective surface and welded to the mask frame,
wherein the skirt portion of the shadow mask includes a slot formed between at least two welding points by which the skirt portion is welded to the mask frame, and a plurality of notches formed at peripheries of the welding points;
a height of the slot from an end side of the skirt portion is higher than that of the welding point; and
a ratio of a width Ws of the slot to a distance Wn between the notches satisfies a formula of 0.22≦Ws/Wn≦0.57.
2. The cathode ray tube of claim 1 , wherein the following formula is satisfied:
Hs≦Hn,
wherein Hs denotes a height of the slot from an end of the skirt portion and Hn denotes a height of the notch.
3. The cathode ray tube of claim 2 , wherein the plurality of notches are formed at an outer side of the welding points.
4. The cathode ray tube of claim 1 , wherein a following formula is satisfied: 0.34≦Ws/Ww≦0.87, wherein Ws denotes a width of the slot and Ww denotes a distance between the welding points.
5. The cathode ray tube of claim 1 , wherein a number of said slots is more than two.
6. The cathode ray tube of claim 5 , wherein the following formula is satisfied: 0≦D(Ww−(Ws×X)), wherein Ww denotes a distance between the welding points, Ws denotes a width of the slot, X denotes the number of the slots, and D denotes a distance between the slots.
7. The cathode ray tube of claim 1 , wherein the panel has a substantially flat outer surface and an inner surface of a predetermined curvature.
8. The cathode ray tube of claim 1 , wherein the electron beam passing holes of the shadow masks are formed as circular apertures.
9. The cathode ray tube of claim 1 , wherein the plurality of notches are formed in a central portion of a short side of said skirt portion.
10. The cathode ray tube of claim 9 , wherein the height of the slot is substantially equal to a height of said notches.