Membrane assembly for a three-dimensional printing system

Abstract

A vat polymerization apparatus configured with a resin circulatory system that includes pumps arranged to extract used photo-curing resin from a tank and refresh or replace it with new resin, another fluid, or a combination of new resin and the fluid. Resin flow is regulated using a plurality of valves which are opened and closed to achieve a desired circulation process. Additional aspects of the apparatus include a membrane assembly in which a radiation-transparent flexible membrane is supported in a frame that stretches the membrane. A lip of the frame is secured to a bottom rim of the tank; thus, when the membrane assembly is in place it forms a bottom of the tank. A tension adjustment mechanism may be employed to adjust the tension of the membrane within the frame. The frame may be aligned with the tank with the aid of magnetized alignment aids distributed about the frame.

What is claimed is: 
     
         1 . A membrane assembly for a three-dimensional printing system, comprising:
 a radiation-transparent flexible membrane; and   a frame configured to stretch the radiation-transparent flexible membrane along a first plane,   wherein the frame comprises a top planar surface that extends parallel to the first plane, a bottom planar surface that extends parallel to the first plane, an inner side surface disposed between the top and bottom planar surfaces, and a lip extending from the top planar surface in a direction perpendicular to the first plane, and spaced apart from the inner side surface, and   wherein a perimeter of the radiation-transparent flexible membrane contacts the inner side surface of the frame.   
     
     
         2 . The membrane assembly of  claim 1 , wherein the frame further comprises an outer side surface disposed between the top and bottom planar surfaces, and wherein the lip is further spaced apart from the outer side surface of the frame. 
     
     
         3 . The membrane assembly of  claim 1 , wherein a distance that the lip is setback from the inner side surface of the frame is equal to a distance that the lip is setback from the outter side surface of the frame. 
     
     
         4 . The membrane assembly of  claim 1 , further comprising a tension adjustment mechanism coupled to the radiation-transparent flexible membrane and configured to adjust a tension of the radiation-transparent flexible membrane. 
     
     
         5 . The membrane assembly of  claim 1 , further comprising a tension sensor affixed to a surface of the radiation-transparent flexible membrane and configured to measure a tension of the radiation-transparent flexible membrane. 
     
     
         6 . The membrane assembly of  claim 5 , wherein the tension sensor comprises a strain gauge affixed to the surface of the radiation-transparent flexible membrane. 
     
     
         7 . The membrane assembly of  claim 1 , further comprising a tension sensor embedded within the radiation-transparent flexible membrane and configured to measure a tension of the radiation-transparent flexible membrane. 
     
     
         8 . The membrane assembly of  claim 7 , wherein the tension sensor comprises a conductive strip embedded within the radiation-transparent flexible membrane.