Plotter and aligning method

In plotter apparatus adapted to receive a signal comprising a frame, means for transporting a sheet through said frame along a first axis, and means for marking the sheet moving through said frame in accordance with the signal received, the improvement comprising a system for aligning a sheet with a first linear side parallel to the first axis comprising:

• (a) as said transporting means, a horizontally spaced pair of sheet transport means adapted to be disposed adjacent opposite sides of the sheet for independently transporting the sheet sides both forwardly and rearwardly, both with both of said transport means transporting the sheet in the same direction at the same rate to transport the sheet forwardly or rearwardly and with a first one of said transport means transporting the first side of the sheet at a lesser rate than a second one of said transport means transports the second side of the sheet to swivel the sheet;
• (b) means spaced a given distance from said first transport means for sensing the first side of the sheet;
• and
• (c) means for aligning the first side of the sheet with said sensing means comprising
• (i) means for swiveling a first point on the first side of the sheet across said sensing means to locate the first side and align it substantially at the first point with said sensing means;
• (ii) means for advancing the sheet the given distance;
• and
• (iii) means for swiveling a second point on the first side of the sheet across said sensing means to locate the first side and align it substantially at the second point with said sensing means, said first and second points being spaced apart the given distance.

In plotter apparatus adapted to receive a signal comprising a frame, means for transporting a sheet through said frame along a first axis, and means for marking the sheet moving through said frame in accordance with the signal received, the improvement comprising system for accurately aligning a sheet with a first linear side parallel to the first axis comprising:

• (a) as said transporting means, a horizontally spaced pair of sheet transport means adapted to be disposed adjacent opposite sides of the sheet for independently transporting the sheet sides both forwardly and rearwardly, both with both of said transport means transporting the sheet sides in the same direction at the same rate to transport the sheet forwardly or rearwardly and with a first one of said transport means transporting the first side of the sheet at a lesser rate than a second one of said transport means transports the second side of the sheet to swivel the sheet;
• (b) means spaced a given distance X.sub.1 from said first transport means for sensing the first side of the sheet disposed adjacent said first transport means;
• and
• (c) means for aligning the first side of the sheet with said sensing means comprising
• (i) means for aligning by use of said sensing means two points A and B narrowly spaced from each other by the distance X.sub.1 along the first side of the sheet;
• (ii) means for then aligning by use of said sensing means a fourth point D widely spaced from point B by the distance X.sub.2 along the first side of the sheet;
• and
• (iii) means for finally aligning by computation and without use of said sensing means a third point C intermedaite points B and D and narrowly spaced from point D by the distance X.sub.1 along the first side of the sheet.

In plotter apparatus adapted to receive a signal comprising a frame, means for transporting a sheet through said frame along a first axis, and means for marking the sheet moving through said frame in accordance with the signal received, said marking means comprising

• (a) a marker holder for holding a marker;
• (b) storage means for holding a plurality of markers;
• (c) means for causing said holder to receive a selected marker from and return it to said storage means;
• and
• (d) means for moving said holder and any market held thereby along a second axis of the sheet substantially perpendicular to the first axis and along a third axis substantially perpendicular to the sheet;
• the improvement comprising knife means for cutting the sheet along the second axis, said knife means being configured and dimensioned to be received, held and returned by said holder and held by said storage means as a marker.

Plotter apparatus having the capability of unattended operation comprising:

• (a) independently driven dual X-axis friction drives for transporting a sheet through the plotter;
• (b) means for automatically aligning a sheet with the X-axis of the plotter;
• (c) means for automatically cutting a sheet into segments along the Y-axis of the plotter;
• and
• (d) means for automatically collecting and storing the segments.

A method for aligning a sheet with a first linear side parallel to its axis of transport through plotter apparatus comprising:

• (a) swiveling a first point on the first side of the sheet across a single fixed sensing means to locate the first side and align it substantially at the first point with the sensing means;
• (b) advancing the sheet a given distance;
• and
• (c) swiveling a second point on the first side of the sheet across the sensing means to locate the first side and align it substantially at the second point with the sensing means, the first and second points being spaced apart the given distance.

A method for accurately aligning a sheet with a first linear side parallel to its axis of transport through plotter apparatus comprising the steps of:

• (a) aligning by use of a sensing means first and second points A and B narrowly spaced from each other by the distance X.sub.1 along a first side of the sheet;
• (b) then aligning by use of the sensing means a fourth point D widely spaced from point B by the distance X.sub.2 along the first side of the sheet;
• and
• (c) finally aligning by computation and without use of said sensing means a third point C intermediate points B and D and narrowly spaced from point D by the distance X.sub.1 along the first side of the sheet.