| 摘要 |
PCT No. PCT/JP97/03994 Sec. 371 Date Jul. 2, 1998 Sec. 102(e) Date Jul. 2, 1998 PCT Filed Oct. 31, 1997 PCT Pub. No. WO98/20514 PCT Pub. Date May 14, 1998A shadow mask disposed to face a phosphor screen of a cathode ray tube includes a substantially rectangular effective surface on which a number of substantially rectangular apertures are formed. The effective surface has horizontal and vertical axes which perpendicularly cross in the center thereof and diagonal axes passing through the center. The apertures are arranged to form a plurality of vertical rows of apertures extending in the direction of the vertical axis. Each of the vertical rows of apertures includes a plurality of apertures arranged in the direction of the vertical axis with a bridge portion being interposed between two adjacent apertures, and those vertical rows of apertures are arranged in the direction of the horizontal axis at a predetermined pitch. The width W of the apertures in the direction of the horizontal axis is formed so as to gradually increase from that of the aperture located at the center of the effective surface to that of the apertures located at the peripheries of the effective surface in the direction of the horizontal axis. The width of each of corner apertures located in the vicinity of the ends of the diagonal axes is larger than the width of the aperture located on the horizontal axis in the same vertical row of apertures to which the corner aperture belongs.
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