| 摘要 |
The invention relates to apparatus and methods for producing three- dimensional objects through building of successive layers printed by eg inkjet printheads. For aligning the printheads a test pattern (129) is used, made up of alternating reference lines (135) and test lines (136), both parallel and perpendicular to a fast-axis travel, the testlines comprising test bars (191) incrementally displaces around a central test bar. Cleaning of the printheads is also provided. The test pattern (129) is read by alignment sensor system (132) and analysed with a Fast Fourier Transform (FFT). |
