| 摘要 |
An apparatus for use in producing an illumination pattern on an electrically conductive mask blank having a photoresist coating thereon for a color cathode ray tube. The apparatus comprises a rigid, transparent substrate which has a first preselected pattern on the substrate, having a preselected optical density. The first pattern has first areas corresponding in distribution to the pattern of apertures to be formed in a mask blank, at least a predetermined group of the first areas being smaller in size than the desired ultimate mask aperture size. The substrate has a second preselected pattern having second areas surrounding the first areas, at least a predetermined group of the second areas corresponding to the first group of areas and having the size and outer configuration of the desired ultimate mask apertures. A third area between the second areas of the second preselected pattern has an optical density substantially different from the optical density of the first areas of the first preselected pattern. The second areas have an optical density intermediate to the optical density of the first areas and the third areas. The first and second patterns are such as to effectively establish, upon exposure of the photoresist coating through the apparatus, a first image corresponding to the first pattern and a second image corresponding to the second pattern, the first and second images being capable of being separately developed in separate photoresist development operations.
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