System for detecting inoperative inkjets in three-dimensional object printing using an optical sensor and movable test substrates

摘要

An apparatus detects inoperative inkjets during printing of three-dimensional objects. The apparatus includes an optical sensor that generates measurements of a height, a diameter, and a position for test dots formed on a substrate with material ejected from a printhead. These measurements are analyzed to detect inoperative inkjets to enable printhead maintenance at appropriate times to maintain the operational status of the inkjets in the printhead.

主权项

1. A printer comprising:
a printhead configured with inkjets to eject material; a supply of substrate configured to move a substrate to a position opposite the printhead to receive drops of material ejected from inkjets in the printhead; an optical sensor configured to generate measurements of heights and diameters of drops of material on the substrate and positional data of positions of the drops of material on the substrate; a transport configured to move the substrate and material on the substrate to a position opposite the optical sensor; and a controller operatively connected to the transport, the optical sensor, and the printhead, the controller being configured to operate the printhead to eject a predetermined number of drops of material from each inkjet in the printhead onto the substrate while the substrate remains stationary at the position opposite the printhead to enable the predetermined number of drops of material to form a test dot for each inkjet in the printhead on the substrate, to operate the transport to move the substrate from being opposite the printhead to being opposite the optical sensor, and to identify inoperable inkjets in the printhead with reference to the height and diameter measurements for each test dot on the substrate and the positional data for each test dot on the substrate received from the optical sensor.