Large-format plotter using segmented raster-scanning

摘要

A large-format plotting device is provided for transferring an image to a relatively large sized medium. A data processing device is used to divide the surface of the medium into a plurality of relatively narrow segments. A beam sweeping device, which can include a high energy beam such as a laser beam, is provided for sweeping the beam the width of the segment. The data processing device causes the beam to turn on and off to define a portion of the desired image. A movement mechanism is included to either move the beam generating device or the support for the medium at a desired velocity so that each sweep of the beam will produce a raster line whereby the entire segment will be swept forming a plurality of parallel raster lines covering the entire segment. The movement mechanism also includes placement mechanism for laterally moving the medium support or beam generating device to the next adjacent segment in sequence until the surface of the entire medium has been imaged. Alignment features can be provided so that the corresponding raster lines in each segment can be aligned so that they coincide and so that the beam will not overlap at the contiguous edges of the segments. Sensors can be provided on the beam generating device or on the medium to identify the edges of the desired segments. The medium can also be mounted on a rotating drum whereby the movement mechanism rotates the drum at a desired velocity synchronized with the sweep of the beam generating device. Raster-scan imaging is controlled by the data processing device which simultaneously controls the beam generating device for the sweep and intensity of the beam as well as the operation of the positioning mechanism.