Three-dimensional printing appratus and method for calibrating printing inaccuracy thereof

A three-dimensional printing apparatus, comprising:

• a platform comprising a supporting surface and a plurality of calibration position points wherein the calibration position points are located on the supporting surface, and the calibration position points divide the supporting surface into a plurality of first zones;
• a printing head disposed above the platform, wherein the printing head is disposed to move along a datum plane and along a direction of a normal line of the datum plane;
• a touch sensor, disposed on a nozzle of the printing head;
• and
• a controller coupled to the printing head to control the printing head along the direction of the normal line respectively move toward the calibration position points on the supporting surface from a predetermined height until the touch sensor is in contact with the calibration position points to respectively obtain the compensation reference values of the calibration position points relative to the datum plane, wherein the compensation reference values decides linear compensation relationships respectively corresponding to the first zones,
• wherein the first zones are divided to generate a plurality of second zones, the controller based on the linear compensation relationships calculates a plurality of reference compensation values respectively corresponding to the second zones, and the controller records the reference compensation values,
• wherein the controller by using the linear compensation relationships and the reference compensation values calibrates a printing height of a starting point and a printing height of an ending point to obtain a first printing coordinate of the starting point and a second printing coordinate of the ending point, the controller based on the first printing coordinate and the second printing coordinate controls the printing head to move and simultaneously feed out forming material.