Measurement of paper stack topography

A paper curl measuring system comprising:

• a paper stack tray with an open top portion, said tray configured to house a stack of papers;
• said papers being substantially stationary, once stacked;
• a paper stack surface curl measuring probe that is a horizontally movable probe;
• a probe transport, a sensor and a system controller;
• said probe transport extending horizontally over and along a length of said stack to be measured and movably supporting said horizontally movable probe;
• said horizontally movable probe movable along said probe transport and comprising a front and a back section;
• said front section configured to contact a paper stack surface being measured;
• said probe back portion in an operative connection to said sensor;
• said sensor configured to measure vertical movement or displacement information of said horizontally movable probe as it travels along said probe transport and over said surface and configured to convey said displacement to said controller;
• said horizontally movable probe is a low contact force probe configured to measure the curl topography along at least one top edge of said paper stack located in said paper stacking tray.

A paper stack curl surface measurement system comprising:

• a paper stack tray with an open top portion, said tray configured to house a stack of said papers, said papers substantially stationary once positioned in said paper stack tray;
• a surface measuring probe in communication with a sensor;
• a horizontally disposed probe transport, and a system controller;
• said measuring probe configured during a curl measuring operation to be horizontally transported adjacent to and along a paper axis substantially parallel with an upper stack surface edge;
• said probe configured to be in a low contact force with said edge and configured thereby to measure a topography of said edge without causing any significant deformation of said surface;
• said probe configured to detect surface information, including any curls in said stack surface and said sensor enabled to transmit said surface information to said system controller;
• said probe transport comprising a motor operatively connected to a movable actuator transport, said actuator transport supporting a nut attached to said probe,
• said probe transport configured to traverse an entire length of said stack and parallel to said stack edge thereby enabling said attached probe to engage and lightly ride over said upper stack edge surface and configured thereby to measure said topography of said stack surface,
• said sensor configured to measure and transmit to said controller said surface information on said probe's angular displacement and direction of motion across said stack surface, said controller configured to transmit said information to a decurling system for any corrective action.

A method for measuring the curl of a sheet of paper on a top of a substantially stationary stack of paper sheets comprising:

• positioning a horizontally movable probe over said stack;
• positioning said probe on a movable actuator transport;
• moving said probe across the stack along an axis substantially parallel to one edge of the stack;
• exerting a controlled low contact force where said force is insufficient to deform said stack surface;
• providing a sensor to measure said probe's angular displacement and direction of motion across said stack;
• providing a controller in informational contact with said sensor;
• recording via said sensor the height of the probe relative to a reference height;
• and transmitting the recorded height measurements to said controller.