Importance

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Abstract

An engraving apparatus for engraving the outer surface of a cylinder used in a gravure printing process includes an engraving stylus mounted onto a shaft for engraving the surface of the cylinder. A drive mechanism is employed for producing angular movement of the shaft and the stylus aboout the central axis of the shaft. A position sensor comprising a light beam illuminator and a light beam detector is associated with the shaft to sense the angular movement of the shaft and produce a shaft position signal representative thereof. A reference signal generator is employed for producing a reference drive signal and a video signal generator is used to produce a video drive signal representative of the information to be engraved into the surface of the cylinder. A feedback control is employed which is responsive to high frequency portions of the video signal, the reference drive signal and the shaft position signal, and generates a corrected drive signal including a correction for any variations in the amplitude of the angular oscillatory movement of the shaft. The corrected drive signal and the video signal are then combined and supplied to an engraver driver which produces an engraver drive signal for actuating the drive mechanism. The engraving apparatus may further include an electronic damping mechanism connected to the position sensor and responsive to the shaft position signal for generating a negative feedback signal to the engraver driver to provide damping for the shaft and the engraving tool.

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First Claim