SHADOW MASK INSPECTION DEVICE FOR COLOR CATHODE-RAY TUBE

PURPOSE:To enable easy and accurate inspection of the uneveness of opening among fine holes formed in a shadow mask within a short time. CONSTITUTION:The uneveness of opening among numerous fine holes 12 formed in a shadow mask 11 is inspected. A bar-shaped or linear light source 16 and a bar-shaped condenser lens 17 are disposed parallel to each other on the reverse and front sides of the mask 11, respectively. An inspection optical system 20 comprises an image pickup element 18 for obtaining data about the distribution of light quantity with respect to the open area of each of the fine holes by means of picking-up of images condensed by the condenser lens 17. While the inspection optical system 20 and the shadow mask 11 are shifted by a shifting mechanism 21 along the direction of a plane and relative to each other, images condensed by the condenser lens 17 through the fine holes 12 are picked up by the image pickup element 18. Data about the distribution of light quantity proportional to the open area of each fine hole 12 are obtained.