Three-dimensional printer with integrated coloring system

Abstract

A three-dimensional printer effects color changes in an extrudate using a color-application unit applying a colorant to the interior of a filament before it is melted within an extruder. Specifically, the color-application unit may receive a filament (or portions thereof) having an exposed interior surface, where color applicators are actuated to apply one or more colors to the interior surface of the filament in order to modify the extruded color. The filament may then be coupled, collapsed, or otherwise closed about the interior surface, e.g., by a mechanical coupler, to substantially enclose the interior surface of the filament, which is then fed to the extruder for fabricating a colored object in a three-dimensional fabrication process. By enclosing the colored surface within the filament before melting for extrusion, transition effects of a color change can be mitigated and transition time for a substantially complete change in color can be significantly reduced.

What is claimed is: 
     
         1 . A three-dimensional printer comprising:
 an extruder configured to deposit a build material in a three-dimensional printing process;   a coloring system including a color-application unit disposed upstream from the extruder, the color-application unit configured to receive a filament of the build material, the color-application unit including a color applicator operable to selectively apply a color to an interior surface of the filament without applying color to an exterior surface of the filament; and   a drive assembly for moving the filament from the coloring system to the extruder for depositing colored build material in the three-dimensional printing process.   
     
     
         2 . The three-dimensional printer of  claim 1  further comprising a coupler configured to receive the filament from the color applicator and to substantially enclose the interior surface of the filament that received the color before passing the filament to the extruder. 
     
     
         3 . The three-dimensional printer of  claim 2  wherein the coupler is connected to the extruder by a conduit, the conduit including a pathway for the filament to travel between the coupler and the extruder. 
     
     
         4 . The three-dimensional printer of  claim 2  wherein the color-application unit and the coupler are integrated together as a single unit. 
     
     
         5 . The three-dimensional printer of  claim 2  wherein the extruder and the coupler are integrated together as a single unit. 
     
     
         6 . The three-dimensional printer of  claim 2  wherein the filament includes a first filament portion and a second filament portion, at least one of the first filament portion and the second filament portion including the interior surface, and wherein the coupler is configured to join the first filament portion to the second filament portion to form the filament for extrusion in the three-dimensional printing process. 
     
     
         7 . The three-dimensional printer of  claim 6  wherein the coupler includes a body that has a first channel and a second channel, wherein the first channel receives the first filament portion and the second channel receives the second filament portion, and wherein the first channel and the second channel converge within the body to form a discharge channel that guides the filament through the body. 
     
     
         8 . The three-dimensional printer of  claim 7  wherein the coupler includes a motor and a roller assembly that is actuated by the motor, and wherein the roller assembly engages the first filament portion and the second filament portion to advance the filament through the body. 
     
     
         9 . The three-dimensional printer of  claim 1  wherein the extruder and the color-application unit are disposed within a build volume of the three-dimensional printer. 
     
     
         10 . The three-dimensional printer of  claim 1  wherein the color-application unit includes a plurality of color applicators, each operable to selectively apply a different color to the interior surface of the filament. 
     
     
         11 . The three-dimensional printer of  claim 1  wherein the color-application unit includes a body, a conduit extending through the body, and a motor that engages the filament to move the filament through the conduit. 
     
     
         12 . The three-dimensional printer of  claim 11  wherein the color-application unit includes a through-hole that extends through the body and is communication with the conduit, and wherein the color applicator includes an elongate member containing the color and having a color applicator tip that is configured to apply the color to the interior surface of the filament through the through-hole, and wherein at least a portion of the elongate member is slidably received within the through-hole to selectively engage and apply the color to the interior surface of the filament. 
     
     
         13 . The three-dimensional printer of  claim 1  wherein the color applicator includes an inkjet cartridge. 
     
     
         14 . The three-dimensional printer of  claim 1  wherein the extruder is disposed in a printer head of the three-dimensional printer. 
     
     
         15 . A method for three-dimensional fabrication of an object using a three-dimensional printer comprising:
 receiving a filament at a color-application unit of the three-dimensional printer, the color-application unit positioned upstream of an extruder within the three-dimensional printer;   applying color to an interior surface, but not an exterior surface, of the filament using a color applicator coupled to the color-application unit;   directing the filament from the color-application unit to the extruder; and   extruding the filament to fabricate the object in a three-dimensional printing process.   
     
     
         16 . The method of  claim 15  wherein the filament includes a first filament portion and a second filament portion, at least one of the first filament portion and the second filament portion including the interior surface. 
     
     
         17 . The method of  claim 16  further comprising coupling the first filament portion to the second filament portion to form the filament for extrusion. 
     
     
         18 . The method of  claim 17  wherein a coupler that is positioned downstream of the color applicator and upstream of the extruder couples the first filament portion and the second filament portion. 
     
     
         19 . The method of  claim 18  further comprising:
 receiving the first filament portion in a first channel disposed in a body of the coupler; 
 receiving the second filament portion in a second channel disposed in the body of the coupler; and 
 joining the first filament portion and the second filament portion within a discharge channel formed by a convergence of the first channel and the second channel within the body of the coupler. 
 
     
     
         20 . A device comprising:
 a color-application unit configured for placement upstream from an extruder configured to deposit a build material in a three-dimensional printing process, wherein the color-application unit is configured to receive a filament of the build material; and   a color applicator coupled to the color-application unit and operable to selectively apply a color to an interior surface, but not an exterior surface, of the filament before the filament is passed to the extruder.