System and method for controlling material drop volume in three dimensional object printing

摘要

A printer uses closed loop control to keep material drops ejected by a printhead within a predetermined range. The printer forms at least two objects on a support member and then operates a specular sensor array to obtain image data of the two objects on the support member. The two objects have different predetermined heights to enable a controller in the printer to identify the mass or volume of the material drops forming the objects to adjust operational parameters of the printer to maintain the mass or volume of the material drops in the predetermined range.

主权项

1. A printer comprising:
a planar support member; a printhead positioned to eject drops of material towards the support member, at least one of the planar support member and the printhead being configured to move relative to the other of the planar support member and the printhead; a specular sensor array having an illumination source and a plurality of light receivers, the illumination source being configured to emit light at a predetermined angle to the planar support member and each light receiver being configured to generate an electrical signal corresponding to light reflected from ejected material on the planar support member; and a controller operatively connected to the planar support member, the printhead, and the specular sensor array, the controller being configured to:
operate the printhead to form at least two objects on the planar support member;operate one of the planar support member and the printhead to move relative to the other of the planar support member and the printhead to enable the at least two objects to have a length in a cross-process direction that substantially covers a width of the printhead across the planar support member and have a length in a process direction that extends along a portion of the planar support member in a process direction;operate the specular sensor array to direct light towards the planar support member and receive the electrical signals generated by the light receivers as one of the specular sensor array and the planar support member move relative to the other of the specular sensor array and the planar support member;analyze image data corresponding to the electrical signals received from the light receivers to identify a ratio between a difference in shadow distances identified by a response of the light receivers to reflected light at an edge of the two objects and a difference in height between the two objects; andadjust an operational parameter of the printhead in response to the analyzed image data indicating a mass of material drops ejected by an inkjet in the printhead has change with reference to a predetermined material drop mass.