| 摘要 |
1,180,799. Colour television tubes. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 8 Sept., 1967 [13 Sept., 1966], No. 41186/67. Heading H1D In the manufacture of colour television screens of the type comprising strips of at least two different phosphors separated by opaque strips and including indexing strips overlying, for example, alternate opaque strips, the strips are formed with the aid of a set of matched masks produced from respective negatives formed from a common auxiliary mask by a radiation exposure process. Fig. 2, illustrates the production of a negative 95 on a curved glass screen 65 from the common auxiliary mask; this negative will correspond to the luminescent strips, so in the case of a three colour system two thirds of the transparent areas in the mask 2 are shielded by opaque areas in a supplementary mask 6, and two further negatives are made with the mask 6 displaced to expose other groups of strips for the other two colours. The planoparallel glass plate 4 is inclined at a small angle to displace the strips by a predetermined amount. When a negative is made corresponding to the opaque strips of the final screen (Fig. 1, not shown), the plate 4 is parallel to the auxiliary mask 2 and the mask 6 is omitted; when a negative is made for the index strips (Fig. 4, not shown) the plate 4 is parallel to mask 2 which is covered by a different supplementary mask which obscures alternate transparent areas. From the five negatives (three for coloured strips, one for intermediate opaque strips and one for index strips) corresponding masks are made by a further radiation exposure process (Fig. 5, not shown) which may include an optical system (151, Fig. 6, not shown). The radiation exposure processes may be either negative or positive. Fig. 9a illustrates the steps in an alternative method of producing the mask for the index strips. At a first exposure by a positive process the mask 208 is omitted and areas 210-214 on the negative 209 are exposed through the auxiliary mask 200. Mask 208 is then placed as shown and a planoparallel glass plate (not shown) is inserted to provide an optical shift such that areas 215-217 are exposed. From the negative 209 thus obtained the mask 218 is manufactured by a negative process. |
