Plotter with drive rollers having variable radial contact surfaces

Abstract

A plotter wherein, while a sheet is being moved on a recording surface, figures, characters etc. are automatically depicted on the surface of the sheet, or the contours of figures, characters etc. are automatically cut in the surface of the sheet. In the plotter, both the side edges of the sheet are respectively held between drive rollers and corresponding pinch rollers mounted at both the sideward parts of the recording surface in opposition to each other, and the drive rollers at both the sideward parts of the recording surface are rotated synchronously to each other, whereby the sheet is moved in the rotating direction of the drive rollers on the recording surface. Each of the drive rollers is formed at its peripheral surface with milling or ruggedness for preventing the sheet from slipping. The plotter comprises piston-cylinder assemblies and associated springs for regulating respective pressures acting to press the pinch rollers at both the sideward parts of the recording surface against the surface of the sheet. It also comprises sensors for sensing the directions and degrees of the wobbles of the sheet moving on the recording surface, and a controller for controlling the lengths of the springs in accordance with the direction and degree of the wobble of the sheet sensed by the sensors, thereby to regulate the respective pressures acting to press the pinch rollers at both the sideward parts of the recording surface against the sheet surface. When the sheet has begun to wobble, the direction and degree of the wobble are sensed by the sensors, and the pressure acting to press the pinch roller against the sheet surface is increased or decreased, thereby to correct the moving orbit of the sheet.