An XY recorder in which a recording paper is moved on a platen along the X axis in accordance with one variable and a stylus is moved along the Y axis in accordance with another variable, employs a controller to control the paper movement in several different modes. In a paper draw out mode, the paper is drawn out from a paper-feed roll pinched on the platen between pinch rollers and drive rollers, and during a time interval when the paper-feed roll exerts a backward tension to the paper, the paper is intermittently allowed to slip on the platen by disengaging the pinch rollers from the drive rollers. The tension to the paper backward from the paper-feed roll automatically aligns the paper.

In a flat table drawing plotter, an image is drawn on the portion of a continuous work piece, e.g., a sheet of paper, located on a drawing table. Upon completion of the drawing of the image, a trace line is drawn at the rear end location of the image. The drawing carriage, having an optical detector means mounted thereon, is moved to the forward end of the table. The work piece is advanced with the optical detector means in continuous contact therewith. The advance of the work piece is stopped when the optical detector means detects the trace line. Then, the drawing carriage is slowly moved until the optical detector means again detects the trace line thereby identifying where the prior drawing of the image was completed. Drawing of the image is then recommenced.

Apparatus for assisting in the loading of strip roll paper in a graphics drum plotter having a vacuum column disposed between a strip paper supply roller and a drum wherein insufficient space is available between the drum and the beam/writing head above it for reaching through to grasp the paper on the supply roller for pulling it through. A hook-shaped wire guide is hingedly attached through a slot in the center of the back wall of the vacuum column. The guide wire is biased by a counter weight to a position within the vacuum column and is moved out of the vacuum column through the slot from the force of paper descending into the vacuum column. The hook is shaped to guide paper being rolled off the supply roller across the space between the front and back walls of the vacuum column and to direct it into a position between the drum and the beam/writing head where it can be grasped.

A graphic machine or plotter comprising a feed roll (30) for continuously supplying a print medium such as paper (20), driving means (24) for driving the paper supplied by the feed roll to produce a drawing on the paper, and a take-up roll (40) for receiving the paper after the drawing is produced. The feed roll (30) and the take-up roll (40) are linked together in such a way that the rotation of the feed roll (30) in a forward direction for which the paper is payed out from the feed roll drives the take-up roll (40) to wind up the paper but the rotation of the take-up roll (40) in the reverse direction does not drive the feed roll (30).

In a conventional vacuum box a loop of a web material is received in an elongate chamber of the box, and a vacuum at the lower portion of the chamber draws air through the chamber to hold the loop of web material under tension as it moves through the chamber. When the web has one or more notches along a side edge thereof, the web may vibrate excessively and experience a drop in web tension as the notch passes through the bottom of the loop in the box. In order to avoid this problem an endless ring of flexible material is positioned in the vacuum box and within the loop of web material. The ring has a plurality of spaced openings around the circumference of the ring, and they are offset from the side edges of the ring so that the portion of the ring adjacent the openings will cover the notches in the web as the web passes through the bottom of the loop in the vacuum box, thus avoiding the excessive vibration in the web and loss in web tension mentioned above.