Pen tip structure

A pen tip structure which comprises

• an elongated core which has a generally cylindrical outer surface, a first end for contact with an ink-containing material and a second end for supporting a rotatable sphereical ball, said second end having a recess therein shaped to provide a flat, circular center surface and an annular projection surface which flares outwardly from the periphery of said flat, circular center surface,
• a pipe which includes a shank portion positioned around said elongated core and an end portion located beyond said second end of said elongated core, said shank portion of said pipe defining an inner surface and including a plurality of indentations therein which contact the cylindrical outer surface of said elongated core and thereby provide a longitudinal ink flow channel between said cylindrical outer surface of said elongated core and said inner surface of said shank portion of said pipe along which ink can flow by capillary action, said end portion of said pipe including an inwardly-extending tip which provides a mouth for retaining a rotatable ball between said tip and said second end of said elongated core, and
• a rotatable ball positioned between said mouth of said pipe and said second end of said elongated core, said rotatable ball having a surface, a first portion of said surface extending beyond said mouth of said pipe and an opposite, second portion of said surface being in rubbing contact with said flat, circular center surface of said second end of said elongated core, said rotatable ball having a diameter such that a gap is formed between said surface of said rotatable ball and said annular projection surface which will enable ink to pass therethrough from said ink flow channel to said surface of said rotatable ball by capillary action.