| 摘要 |
A hollor tubular shaft containing optical elements for a laser-type facsimile transceiver employing helical scanning is horizontally supported by air bearings, and translated along its major axis by means of a piston and pneumatic cylinder coaxial with the shaft. An integral reaction-powered air motor provides shaft rotation, and a fail-safe automatic control and braking system prevents damage to the scanning mechanism in the event of interruption of the pneumatic or electrical supplies by permitting physical shaft-to-bearing contact only in the absence of shaft rotation and translational motion. The apparatus finds particular utility in the production of printing plates for use in the Graphic Arts.
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