Abstract: A method for evaluating a color picture tube includes displaying on a display surface of a color picture tube a measurement pattern including a plurality of first patterns arranged at different positions relative to fluophor dots of said color picture tube and a plurality of second patterns near said first patterns and sufficiently large relative to said fluophor dots. A first image is obtained using an imaging element to image said displayed measurement pattern. A second image is obtained using said imaging element to image while controlling light intake to allow brightness components of no more than about 1% of maximum luminance from said first image to be separated from noise and imaged. A third image is created by combining said first image and said second image while adjusting scales according to a light intake ratio. From said third image, display center positions of said plurality of first patterns is calculated using said second pattern positions.

Abstract: The present invention provides an excellent color cathode ray tube of a black matrix type which can reduce the irregularities of a phosphor screen, can exhibits the uniformity of screen, can exhibit the favorable quality of screen, and can obtain the image display of high quality. The size T of a boundary portion between a large hole and a small hole of each electron beam aperture formed in a shadow mask is made small and the surface roughness of an inner surface is made small so that the Irregularity index which expresses the uniformity of the phosphor screen can be set to a value not greater than 7%.

Abstract: A method for evaluating a color picture tube includes displaying on a display surface of a color picture tube a measurement pattern including a plurality of first patterns arranged at different positions relative to fluophor dots of said color picture tube and a plurality of second patterns near said first patterns and sufficiently large relative to said fluophor dots. A first image is obtained using an imaging element to image said displayed measurement pattern. A second image is obtained using said imaging element to image while controlling light intake to allow brightness components of no more than about 1% of maximum luminance from said first image to be separated from noise and imaged. A third image is created by combining said first image and said second image while adjusting scales according to a light intake ratio. From said third image, display center positions of said plurality of first patterns is calculated using said second pattern positions.

Abstract: A cathode-ray tube apparatus capable of reducing a high frequency electric field radiated from the deflection yoke and the deflection and high voltage circuit to the outside of the cathode-ray tube apparatus. Mounted on the deflection yoke or on the cathode-ray tube are an induction coil for generating a pulse voltage opposite in polarity to a high pulse voltage applied to the h and an electric field cancellation electrode made of a conductive wire to which the opposite polarity pulse voltage is applied. When the opposite polarity pulse voltage is applied to the electric field cancellation electrode, the electric field cancellation electrode radiates an electric field opposite in polarity to the high frequency electric field radiated from the deflection yoke to the outside of the cathode-ray tube apparatus to reduce the intensity of the high frequency electric field.

Abstract: A cathode-ray tube apparatus capable of reducing a high frequency electric field radiated from the deflection yoke and the deflection and high voltage circuit to the outside of the cathode-ray tube apparatus. Mounted on the deflection yoke or on the cathode-ray tube are an induction coil for generating a pulse voltage opposite in polarity to a high pulse voltage applied to the h and an electric field cancellation electrode made of a conductive wire to which the opposite polarity pulse voltage is applied. When the opposite polarity pulse voltage is applied to the electric field cancellation electrode, the electric field cancellation electrode radiates an electric field opposite in polarity to the high frequency electric field radiated from the deflection yoke to the outside of the cathode-ray tube apparatus to reduce the intensity of the high frequency electric field.

Abstract: A deflection yoke having cancelling loop coils for reducing undesired portions of a horizontal deflection magnetic field generated by a deflection yoke body without mislanding. The cancelling loop coils generate a cancelling magnetic field which includes two peaks in a front region and a rear region of the deflection yoke body in which the undesired field portions exist, respectively. The peaks are opposite in direction to the horizontal magnetic field generated by the deflection yoke body, respectively, with same ratio to the deflection magnetic field, so that the undesired magnetic field portions are under-corrected in the front portion and over-corrected in the rear portion.