| 摘要 |
A drum control system for providing a predetermined incremental lateral spacing on a drum surface to be accessed in response to a request signal therefor in which the degree of rotation of the drum is controlled in response to the request signal to provide the predetermined incremental lateral spacing by selectively optically reading one of a plurality of optically readable encoded discs each of which has a plurality of circumferentially extending bands, with each of the bands being encoded to correspond to a different uniform proportionate degree of incremental rotation of the drum. The discs are optically read by associated selectively energized optical readers, such as photocells, when the band to be read is illuminated by a substantially simultaneously selectively energized light source. The plurality of discs are preferably arranged in pairs in which a common light source illuminates both discs of the pair with the appropriate associated photocell being selectively energized so that only one disc of the pair is optically read. The light sources and photocells are commonly mounted on a incrementally movable platform which may be indexed to commonly optically align the light source-photocell associated with the band to be read, each of the bands on a given disc preferably being radially spaced apart. The disc may preferably be mounted on a common shaft with the drum and held in place by a threaded resilient clamp which secures the disc in a given predetermined axial position on the shaft as well as enables the provision of the desired spacing between adjacent discs. The drum as well as the indexible light source-photocell platform, are preferably commonly mounted on another incrementally movable platform for simultaneous movement therewith with this platform being axially movable in the direction of the longitudinal axis of the drum, preferably bidirectionally, in response to a request signal for a different predetermined axial position or line feed on the drum surface relative to a fixed access location with the request signal being dynamically variable or programmable, such as from a computer. The system may be employed in a phototypesetting system, such as with a conventional Alphatype or Alphasette incremental model in which predetermined codes normally associated therewith may be swung, such as by means of an attachment to the conventional Alphatype recorder, to provide the code signals which control the operation of the programmable line feed circuitry as well as the indexing and lamp-photocell selection circuitry.
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