Cathode-ray tube apparatus

Abstract

A pair of coma coils for correcting a VCR that is a positional displacement in a vertical axis direction of a center electron beam with respect to the center of a pair of side electron beams on a vertical axis in upper and lower portions on a screen are provided at a position in the vicinity of an end of a deflection yoke on an electron gun side. Assuming that a maximum value of the intensity of a vertical deflection magnetic field on a tube axis is HMAX, and the intensity of a vertical deflection magnetic field on the tube axis at the position where the pair of coma coils are arranged in the tube axis direction is HC, HC/HMAX≧0.8 is satisfied. Owing to this, high-order distortion of horizontal lines on a screen can be corrected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a half cross-sectional view showing a schematic configuration of a cathode-ray tube apparatus according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a deflection yoke mounted on the cathode-ray tube apparatus according to one embodiment of the present invention.

FIG. 3A is a view showing lines of magnetic force generated by a pair of coma coils in the cathode-ray tube apparatus according to one embodiment of the present invention, and FIG. 3B is a circuit diagram of the pair of coma coils.

FIG. 4 is a diagram showing a magnified change in high-order distortion of horizontal lines obtained by a correction in a first stage of increasing the turn number of a winding of a center leg of each E-shaped core constituting the pair of coma coils in the cathode-ray tube apparatus according to one embodiment of the present invention.

FIG. 5 is a diagram showing misconvergence of a VCR on a screen.

FIG. 6 is a diagram showing that a pincushion type magnetic field generated by the pair of coma coils can be decomposed to a dipole magnetic field component and a hexapole magnetic field component in the cathode-ray tube apparatus according to one embodiment of the present invention.

FIG. 7 is a graph showing a tube-axis direction distribution of the intensity of a vertical deflection magnetic field on a tube axis in the cathode-ray tube apparatus according to one embodiment of the present invention.

FIG. 8A is a plan view showing the arrangement and magnetic poles of a first magnet and FIG. 8B is a diagram showing the mechanism in which the distortion in an end portion of a horizontal line is corrected by the first magnet in a first quadrant, in a deflection yoke mounted on the cathode-ray tube apparatus according to one embodiment of the present invention.

FIG. 9 is a perspective view showing a schematic configuration of a deflection yoke mounted on a cathode-ray tube apparatus according to another embodiment of the present invention.

FIG. 10A is a plan view showing the arrangement and magnetic poles of a second magnet, and FIG. 10B is a diagram showing the mechanism in which the distortion in an end portion of a horizontal line is corrected by the second magnet in a first quadrant, in a deflection yoke mounted on a cathode-ray tube apparatus according to another embodiment of the present invention.

FIG. 11A is a plan view showing the arrangement and magnetic poles of a third magnet, and FIG. 11B is a diagram showing the mechanism in which the distortion in an end portion of a horizontal line is corrected by the third magnet in a first quadrant, in a deflection yoke mounted on the cathode-ray tube apparatus according to another embodiment of the present invention.

FIG. 12 is a diagram showing sagging amounts S_A, S_B of high-order distortion of horizontal lines displayed on a screen.

FIG. 13 is a perspective view showing an example of a curved surface shape of a panel inner surface on which a phosphor screen is formed in a conventional cathode-ray tube apparatus.

FIG. 14 is a perspective view showing another example of a curved surface shape of a panel inner surface on which a phosphor screen is formed in the conventional cathode-ray tube apparatus.

FIG. 15 is a diagram showing magnified high-order distortion of horizontal lines displayed on a screen in the conventional cathode-ray tube apparatus.

Claims

1. A cathode-ray tube apparatus, comprising: a panel with a substantially rectangular phosphor screen formed on an inner surface; a funnel connected to the panel; an electron gun housed in a neck of the funnel and emitting a center electron beam and a pair of side electron beams on both sides of the center electron beam; a deflection yoke mounted on an outer circumference of the funnel; and a pair of coma coils placed at a position in a vicinity of an end of the deflection yoke on the electron gun side and correcting a VCR that is a positional displacement in a vertical axis direction of the center electron beam with respect to a center of the pair of side electron beams on a vertical axis in upper and lower portions of a screen, wherein assuming that a maximum value of intensity of a vertical deflection magnetic field on a tube axis is HMAX, and intensity of the vertical deflection magnetic field on the tube axis at the position where the pair of coma coils are placed in a tube axis direction is HC, HC/HMAX≧0.8 is satisfied.

2. The cathode-ray tube apparatus according to claim 1, wherein at least one magnet having an N-pole and an S-pole is placed in a direction so as to bring both ends of a horizontal line on the screen close to an outside in a vertical direction, respectively in four portions corresponding to four corners of the phosphor screen in a vicinity of an end of the deflection yoke on the phosphor screen side.

3. The cathode-ray tube apparatus according to claim 1, wherein two magnets are placed respectively in four portions corresponding to four corners of the phosphor screen in a vicinity of an end of the deflection yoke on the phosphor screen side, and the two magnets are selected from the group consisting of a magnet with an N-pole and an S-pole thereof placed in a straight line parallel to a horizontal axis, a magnet with an N-pole and an S-pole placed in a straight line parallel to the tube axis, and a magnet with an N-pole and an S-pole placed in a straight line parallel to a tangent to an outer circumference of the deflection yoke.

4. The cathode-ray tube apparatus according to claim 1, wherein three magnets are placed respectively in four portions corresponding to four corners of the phosphor screen in a vicinity of an end of the deflection yoke on the phosphor screen side, and an N-pole and an S-pole of one of the three magnets are placed in a straight line parallel to a horizontal axis, an N-pole and an S-pole of another magnet are placed in a straight line parallel to the tube axis, and an N-pole and an S-pole of the remaining one magnet are placed in a straight line parallel to a tangent to an outer circumference of the deflection yoke.