ELECTROPHOTOGRAPHY-BASED ADDITIVE PRINTING WITH IMPROVED LAYER REGISTRATION
An additive manufacturing system includes a transfer belt traveling along a belt path. An electrophotography engine positioned along belt path deposits a part material layer onto the transfer belt, and an image transfer assembly positioned along the belt path transfers the part material layer onto a build platform. An image sensing system positioned along the belt path between the electrophotography engine and the image transfer assembly captures an image which is analyzed to determine an in-track registration error. An in-track position of the build platform is adjusted to compensate for the in-track registration error.
1 . An electrophotography-based additive manufacturing system, comprising:
a transfer belt traveling along a belt path;
an electrophotography engine positioned along belt path that deposits a part material layer onto the transfer belt;
an image transfer assembly positioned along the belt path that transfers the part material layer onto a build platform;
an image sensing system positioned along the belt path between the electrophotography engine and the image transfer assembly adapted to capture an image of the part material layer on the transfer belt; and
a control system that:
analyzes a captured image from the image sensing system to determine an in-track registration error between an intended position of the part material layer and an actual position of the part material layer; and
adjusts an in-track position of the build platform to compensate for the in-track registration error before the part material layer is transferred onto the build platform in registration with previously transferred part material layers.
2 . The electrophotography-based additive manufacturing system of claim 1 , wherein the additive manufacturing system builds a three-dimensional part by building up a sequence of part material layers on the build platform.
3 . The electrophotography-based additive manufacturing system of claim 2 , wherein the image transfer assembly is an image transfusion assembly which transfuses the part material layer onto previously printed part material layers on the build platform.
4 . The electrophotography-based additive manufacturing system of claim 1 , wherein the control system further analyzes the captured image from the image sensing system to determine a cross-track registration error and adjusts a cross-track position of the build platform to compensate for the cross-track registration error before the part material layer reaches the image transfer assembly.
5 . The electrophotography-based additive manufacturing system of claim 1 , wherein the control system determines the actual position of the part material layer by detecting the positions of features of the part material layer in the captured image.
6 . The electrophotography-based additive manufacturing system of claim 1 , wherein the part material layer deposited on the transfer belt includes one or more registration marks, and wherein the control system determines the actual position of the part material layer by detecting the positions of the one or more registration marks in the captured image.
7 . The electrophotography-based additive manufacturing system of claim 1 , further including a second electrophotography engine positioned along the fixed-velocity portion of the belt path that deposits a support material layer onto the transfer belt in registration with the part material layer, and wherein the image transfer assembly transfers the support material layer together with the part material layer.