Development of the RCA 25-inch 90-degree rectangular color picture tube

The new RCA-25AP22 25-inch rectangular 90-degree shadow-mask color picture tube represents a basic advancement in the art of picture-tube development. The result of an extensive developmental program, the 25AP22 features the new look in screen shape and shorter over-all length, with no sacrifice in the performance potential and reliability features established by the earlier RCA 21-inch 70-degree color tubes. The development of a tube having a new shape or increased picture size is, in itself, a relatively simple accomplishment. Of far greater complexity is the design and development of a new tube type having these features, as well as high performance and reliability, together with economics of manufacture. Part I of this paper discusses the innovations made in the design and geometry of the 25AP22. These improvements include a new bulb design, a four-point mask-support system, and an electron-gun structure having a reduced size. These advances, coupled with the improved efficiency of the RCA all-sulphide screen described in Part II, made the 25AP22 an outstanding contribution to the color television industry.