Electron gun for cathode ray tube

1. An electron gun for a cathode ray tube comprising:

a triode including a cathode, a control electrode and an accelerating electrode;

a pre-focusing electrode unit adjacent to the triode;

a main lens unit including a focusing electrode and an anode for forming a main lens for focusing the electron beam toward a screen;

a first focusing electrode unit having vertically-elongated electron beam passing holes and horizontally-elongated electron beam passing holes for forming a quadrupole lens;

a second focusing electrode unit having vertically-elongated electron beam passing holes and horizontally-elongated electron beam passing holes for forming a quadrupole lens; and

an auxiliary electrode disposed between the first focusing electrode unit and the second focusing electrode unit, to which a dynamic voltage is applied, and including vertically-elongated electron beam passing holes on electron beam incoming side thereof and horizontally-elongated electron beam passing holes on electron beam outgoing side thereof.

2. The electron gun of claim 1 , wherein an electrode of the first focusing electrode unit which is adjacent to the auxiliary electrode is formed as a plate shape, and an electrode of the second focusing electrode unit which is adjacent to the auxiliary electrode is formed as a plate shape.

3. The electron gun of claim 2 , wherein a static voltage is applied to the electrodes adjacent to the auxiliary electrode.

4. The electron gun of claim 1 , wherein horizontally-elongated electron beam passing holes are formed in an electrode of the first focusing electrode unit to which a static voltage is applied.

5. The electron gun of claim 1 , wherein vertically-elongated electron beam passing holes are formed in an electrode of the second focusing electrode unit to which a static voltage is applied.

6. The electron gun of claim 5 , wherein horizontally-elongated electron beam passing holes are formed in an electrode of the first focusing electrode unit to which a static voltage is applied.

7. The electron gun of claim 6 , wherein the first focusing electrode unit is adjacent to the pre-focusing electrode unit, and the second focusing electrode unit is adjacent to the main lens unit.

8. The electron gun of claim 1 , wherein the auxiliary electrode is formed as a cup shape or a cap shape.

9. The electron gun of claim 1 , wherein a sum of horizontal widths of electron beam passing holes of the first and second focusing electrode units to which a dynamic voltage is applied is smaller than a sum of vertical widths of electron beam passing holes of the first and second focusing electrode units to which a static voltage is applied.

10. The electron gun of claim 1 , wherein a magnification of a quadruple lens formed by the first focusing electrode unit is larger than a magnification of a quadruple lens formed by the second electrode unit.

11. The electron gun of claim 1 , wherein

each electrode of the first focusing electrode unit, the second focusing electrode unit, and the auxiliary electrode receives either a static or a dynamic focus voltage, and

a sum of horizontal widths of electron beam passing holes of electrodes on which the dynamic focus voltage is received is less than a sum of vertical widths of electron beam passing holes of electrodes on which the static focus voltage is received.

12. An electron gun for a cathode ray tube comprising:

a triode including a cathode, a control electrode and an accelerating electrode;

a pre-focusing electrode unit adjacent to the triode;

a main lens unit including a focusing electrode and an anode for forming a main lens for focusing the electron beam toward a screen;

a first focusing electrode unit having vertically-elongated electron beam passing holes and horizontally-elongated electron beam passing holes for forming a quadrupole lens, wherein at least one electrode of the first focusing electrode unit is formed as a plate shape;

a second focusing electrode unit having vertically-elongated electron beam passing holes and horizontally-elongated electron beam passing holes for forming a quadrupole lens, wherein at least one electrode of the second focusing electrode unit is formed as a plate shape; and

an auxiliary electrode disposed between the first and second focusing electrode units, to which a dynamic voltage is applied,

wherein horizontally-elongated electron beam passing holes are formed in an electrode of the first focusing electrode unit, to which a static voltage is applied.

13. The electron gun of claim 12 , wherein vertically-elongated electron beam passing holes are formed in an electrode of the second focusing electrode unit, to which a static voltage is applied.

14. The electron gun of claim 13 , wherein horizontally-elongated electron beam passing holes are formed in an electrode of the first focusing electrode unit, to which a static voltage is applied.

15. The electron gun of claim 14 , wherein the first focusing electrode unit is adjacent to the pre-focusing electrode unit, and the second focusing electrode unit is adjacent to the main lens unit.

16. The electron gun of claim 12 , wherein a static voltage is applied to electrodes adjacent to the auxiliary electrode.

17. The electron gun of claim 12 , wherein a magnification of a quadruple lens formed by the first focusing electrode unit is larger than a magnification of a quadruple lens formed by the second electrode unit.

18. The electron gun of claim 12 , wherein

each electrode of the first focusing electrode unit, the second focusing electrode unit, and the auxiliary electrode receives either a static or a dynamic focus voltage, and

a sum of horizontal widths of electron beam passing holes of electrodes on which the dynamic focus voltage is received is less than a sum of vertical widths of electron beam passing holes of electrodes on which the static focus voltage is received.

19. An electron gun for a cathode ray tube comprising:

a triode including a cathode, a control electrode and an accelerating electrode;

a pre-focusing electrode unit adjacent to the triode;

a main lens unit including a focusing electrode and an anode for forming a main lens for focusing the electron beam toward a screen;

at least two focusing electrodes disposed between the pre-focusing electrode unit and the main lens unit for forming at least two quadrupole lenses; and

an auxiliary electrode disposed between the at least two focusing electrodes and including horizontally-elongated electron beam passing holes on an electron beam incoming side thereof and vertically-elongated electron beam passing holes on an electron beam outgoing side thereof, wherein a static voltage is applied to the auxiliary electrode.

20. The electron gun of claim 19 , wherein a dynamic voltage is applied to each of the at least two focusing electrodes adjacent to the auxiliary electrode.

21. The electron gun of claim 19 , wherein a first focusing electrode of the at least two focusing electrodes is adjacent to the pre-focusing electrode unit, and has vertically-elongated electron beam passing holes.

22. The electron gun of claim 19 , wherein a second focusing electrode of the at least two focusing electrodes is adjacent to the main lens unit, and has horizontally-elongated electron beam passing holes.

23. The electron gun of claim 19 , wherein

a first focusing electrode of the at least two focusing electrodes is disposed between the pre-focusing electrode and the auxiliary electrode forming a first quadrupole lens,

a second focusing electrode of the at least two focusing electrodes is disposed between the auxiliary electrode and the main lens unit forming a second quadrupole lens, and

a magnification of the first quadruple lens is larger than a magnification of the second quadruple lens.

24. The electron gun of claim 19 , wherein

each electrode of the at least two focusing electrodes and the auxiliary electrode receives either a static or a dynamic focus voltage, and

a sum of horizontal widths of electron beam passing holes of electrodes on which the dynamic focus voltage is received is less than a sum of vertical widths of electron beam passing holes of electrodes on which the static focus voltage is received.