U.S. patent application number 10/356689 was filed with the patent office on 2003-09-04 for three-dimensional model colorization during model construction from computer aided design data.
Invention is credited to Coe, Dorsey D..
Application Number | 20030164567 10/356689 |
Document ID | / |
Family ID | 26936287 |
Filed Date | 2003-09-04 |
United States Patent
Application |
20030164567 |
Kind Code |
A1 |
Coe, Dorsey D. |
September 4, 2003 |
Three-dimensional model colorization during model construction from
computer aided design data
Abstract
A method of generating colorized three-dimensional models with a
solid imaging printer is disclosed. The method comprises
discharging a model building material to a plurality of
compartments in a printerhead assembly, applying simultaneously to
a surface the model building material and the differently colored
model building materials generated by the solid imaging printer to
create the three-dimensional model, and directing an application of
the model building material and the differently colored model
building materials with a controller for generating the
three-dimensional model by a successive layering of the model
building material and the differently colored model building
materials.
Inventors: |
Coe, Dorsey D.; (Grand
Junction, CO) |
Correspondence
Address: |
SIERRA PATENT GROUP, LTD.
P O BOX 6149
STATELINE
NV
89449
US
|
Family ID: |
26936287 |
Appl. No.: |
10/356689 |
Filed: |
January 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10356689 |
Jan 30, 2003 |
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09963884 |
Sep 25, 2001 |
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60244048 |
Oct 27, 2000 |
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Current U.S.
Class: |
264/40.1 ;
264/109 |
Current CPC
Class: |
B29C 64/112 20170801;
B29K 2995/002 20130101; B29C 64/182 20170801; B29C 64/40 20170801;
B33Y 50/02 20141201; B33Y 30/00 20141201 |
Class at
Publication: |
264/40.1 ;
264/109 |
International
Class: |
B27N 003/00 |
Claims
What is claimed is:
1. A method of generating colorized three-dimensional models with a
solid imaging printer, comprising: discharging a liquid model
building material to a plurality of compartments in a printerhead
assembly, wherein at least one of said compartments receives a
model building material from an attached conduit, and each of at
least three of said compartments retains a differently colored
liquid model building material; applying simultaneously to a
surface said model building material and said differently colored
model building materials generated by said solid imaging printer to
create said three-dimensional model; and directing an application
of said model building material and said differently colored model
building materials with a controller for generating said
three-dimensional model by a successive layering of said model
building material and said differently colored model building
materials, wherein said controller accesses model defining
information from at least one data file and directs each of said
model building material and said differently colored model building
materials to be jetted from said compartments on to said model as
it is being generated, according to said model defining
information; wherein said differently colored model building
materials are substantially deposited near or at an external
surface of said generated model, and substantially an entire
interior bulk of said model is provided by said model building
material.
2. The method of claim 1, wherein at least three of said
differently colored model building materials are three primary
colors.
3. A method of using a solid imaging printer to generate a
colorized three-dimensional model, comprising: separating color
data of a full color three-dimensional object into data of three
primary colors; using said data of three primary colors to create
data for separate shell objects of said three primary colors;
transferring said color data and said data for separate shell
objects to said solid imaging printer; discharging a liquid model
building material to a plurality of compartments in a printerhead
assembly of said solid imaging printer, wherein at least one of
said compartments receives a model building material from an
attached conduit, and each of at least three of said compartments
retains a differently colored model building material; applying
simultaneously to a surface said model building material and said
differently colored model building materials generated by said
solid imaging printer to create said three-dimensional model; and
directing an application of said model building material and said
differently colored model building materials with a controller for
generating said three-dimensional model by a successive layering of
said model building material and said differently colored model
building materials, wherein said controller accesses model defining
information from at least one data file and directs each of said
model building material and said differently colored model building
materials to be jetted from said compartments on to said model as
it is being generated, according to said model defining
information; wherein said differently colored model building
materials are substantially deposited near or at an external
surface of said generated model, and substantially an entire
interior bulk of said model is provided by said model building
material.
4. The method of claim 3, wherein at least three of said
differently colored model building materials are three primary
colors.
5. The method of claim 3, wherein said full color object is a
texture map.
6. The method of claim 3, wherein said full color object is a
three-dimensional color scan.
7. A method of retrofitting a solid imaging printer to generate a
colorized three-dimensional model, comprising: adding a
pre-processing module for obtaining data of sub-models prior to
activating said solid imaging printer; separating color data of a
full color three-dimensional object in said pre-processing module
into data of three primary colors; using said data of three primary
colors to create data for separate shell objects of said three
primary colors; transferring said color data and said data for
separate shell objects to said solid imaging printer; discharging a
model building material to a plurality of compartments in a
printerhead assembly of said solid imaging printer, wherein at
least one of said compartments receives a model building material
from an attached conduit, and each of at least three of said
compartments retains a differently colored model building material;
applying simultaneously to a surface said model building material
and said differently colored model building materials generated by
said solid imaging printer to create said three-dimensional model;
and directing an application of said model building material and
said differently colored model building materials with a controller
for generating said three-dimensional model by a successive
layering of said model building material and said differently
colored model building materials, wherein said controller accesses
model defining information from at least one data file and directs
each of said model building material and said differently colored
model building materials to be jetted from said compartments on to
said model as it is being generated, according to said model
defining information; wherein said differently colored model
building materials are substantially deposited near or at an
external surface of said generated model, and substantially an
entire interior bulk of said model is provided by said model
building material.
8. The method of claim 7, wherein at least three of said
differently colored model building materials are said three primary
colors.
9. The method of claim 7, wherein said full color object is a
texture map.
10. The method of claim 7, wherein said full color object is a
three-dimensional color scan.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Divisional of co-pending U.S. patent
application Ser. No. 09/963,884, filed Sep. 25, 2001, which claims
the benefit of the date of U.S. Provisional Patent Application
Serial No. 60/244,048, entitled "Three-dimensional Model
Colorization During Model Construction From Computer Aided Design
Data", filed on Oct. 27, 2000, which is incorporated herein in its
entirety.
BACKGROUND
[0002] The present application relates to a method and system to
colorize three-dimensional models produced by a printing or
layering process. This process is performed when a solid imaging or
model building printer, such as a thermojet printer, is supplied
with computed aided design data for generating a rapid prototype of
a part.
[0003] Current solid imaging printers, such as the Thermojet from
3D Systems, Inc., create solid models from computer aided design
(CAD) data generally according to the following steps:
[0004] Step 1. The CAD data is converted to an industry standard
stereolithography (STL) data format.
[0005] Step 2. The data for the model represented by the STL file
is used to determine data representations of thin (e.g., 0.001
inch) cross sectional layers of the model.
[0006] Step 3. Each of the cross sections is converted into a
bitmap.
[0007] Step 4. Each bitmap is printed onto a platform successively
one on top of another for progressively building the model.
[0008] Step 5. The resulting model is removed from the
platform.
[0009] Full color (two dimensional) printing on a planar substrate
is traditionally achieved by a four color process method whereby
ink for each of the primary colors such as cyan, magenta, yellow,
and black, are applied to the substrate in specified or
predetermined percentages to produce each desired color of a
spectrum of colors. More particularly, such color printing uses 2
to 6 grayscale renderings of the same image in combination, wherein
each grayscale image is printed with a different primary color, and
it is the combination of these primary colors that gives the
appearance of all other colors. In particular, the primary colors
may be applied in layers to the planar substrate as needed to
achieve the desired coloring. However, there has been no comparable
process of printing for colorizing a three-dimensional model
generated by, for example, an extrusion process, such as the five
step process above that is used with solid imaging printers. In
particular, providing full color to such three-dimensional models
has previously been performed by applying decals or painting such
resulting models after they have been constructed.
[0010] The reasons for coloring a three-dimensional model after
construction has been at least due to difficulties of manufacture
(i.e., the computational complexity of rendering a full spectrum of
colors in three dimensions, and the complexity of providing
variously colorized model building materials to such a solid
imaging printer). For example, an impediment to colorizing
three-dimensional model during model generation has been the belief
that duplicate substrate delivery systems (one for each primary
colored substrate) would be required when building colored models.
Accordingly, such duplication would likely require additional
heating or melting components, and additional substrate reservoirs.
Moreover, such difficulties have previously inhibited development
of a process similar to the two dimensional printing process for
use in the generation of three-dimensional models. Previously, the
contemplated modifications to, for example, the thermojet machine
to produce colored three-dimensional models during model
construction have been cost prohibitive both by reason of cost to
manufacture the models as well as cost of machine operation when
compared to the one color rapid prototyping (RP) methods and
machines currently being used (in conjunction with, for example, a
subsequent step of model painting).
[0011] With traditional two dimensional color printing four colored
inks (e.g., cyan, magenta, yellow, and black) have been combined to
produce a full spectrum of colors. With three-dimensional printing,
a fifth model building material (herein also referred to as the
"substrate", or "center portion" of a three-dimensional model) is
also required to be output (i.e., jetted or sprayed) from the solid
imaging printer together with the four primary colors in order for
the printer to build the internal structure of the model at the
same time that it is applying color to, for example, a relatively
thin model thickness (or shell) at the surface of the model.
[0012] Accordingly, in one naive application of the two dimensional
color printing approach to three-dimensional printed models, the
printhead assembly for such a solid imaging printer must include at
least five printheads: one printhead for each of the four print
colors and at least one printhead to output the model building
material that provides the bulk of the resulting model. While this
is entirely possible, most printhead assemblies of such imaging
printers are designed to jet, at most, four different materials.
Thus, to jet five different materials increases the complexity of
such a three-dimensional imaging printer in terms of size,
electronics, material delivery as well as computational complexity
and other factors all of which increase the cost of such a machine.
Moreover, there is likely increased maintenance and lowered
reliability with the additional complexity of an extra printhead.
Additionally, the prospect of cost effectively retrofitting
currently available four printhead solid imaging printers with a
five printheads is unlikely.
[0013] Accordingly, it would be desirable to have a method and
system for cost effectively colorizing a three-dimensional model as
it is being constructed by, for example, a solid imaging printer.
Moreover, it would be particularly desirable to have such a method
and system, wherein currently available solid imaging printers that
generate three-dimensional models in a single color (or colorless)
can be easily retrofitted to additionally produce colored
three-dimensional models.
SUMMARY
[0014] The drawbacks and disadvantages of the prior art are
overcome by the three-dimensional model colorization during model
construction from computer aided design (CAD) data.
[0015] The present application discloses a method and system for
coloring a three-dimensional model as it is being constructed by a
extrusion process such as is performed by a thermojet printer or
other solid imaging printer. In particular, the present application
discloses a method and system for coloring the surface of such an
extruded model during its construction.
[0016] The method and system of the present application may be
implemented with a new solid imaging printing machine. However, in
an alternative embodiment (and at least in some contexts a
preferred embodiment), the present invention may be performed by
retrofitting currently available solid imaging printing machines so
that with minimal changes or additions, full color
three-dimensional models may be printed (e.g., extruded). For
example, in one embodiment that is compatible with the retrofitting
of currently available imaging printers, a traditional printhead
assembly having a four printhead array of jets is utilized.
Currently available imaging printers, such as the Thermojet machine
from 3D Systems Inc., utilize such a printhead assembly. However,
the four jet arrays are used as a single large array to jet a
single colored (or colorless) model building material through the
combined jet arrays. The present application utilizes a greater
degree of the functionality of such printhead assemblies (with,
perhaps, minor enhancements thereto) to generate colorized
three-dimensional models.
[0017] Moreover, in retrofitting of available solid imaging
printing machines consideration is given to keeping color printing
production costs of such three-dimensional models low, as well as
keeping low the amount of time required to retrofit the currently
available solid imaging printing machines.
[0018] Additionally, to keep the overhead low for implementing new
training and maintenance procedures of field engineers already
familiar with existing solid imaging printing machines.
Accordingly, in a first embodiment, a combination of software and
hardware modifications or add-ons (rather than a total redesign) as
a retrofit is provided herein. Moreover, the modifications to
existing solid imaging printing machine hardware are minor. In
particular, such a printer will continue to function as a "dumb"
printer, in that it is unnecessary that the imaging printer
distinguish between colors.
[0019] Furthermore, the modifications to the software to provide
the present invention in an existing solid imaging printer is also
minor. For example, the software of a data model preparation module
(e.g., a module, possibly remotely linked to the solid imaging
printer via a network such as the Internet, wherein the module
prepares STL data files for input to the printer) does not need to
make distinctions between colors. That is, since currently
available imaging printers are able to print many STL models
simultaneously without knowledge of colors, such simultaneous model
printing can be used to build color models by simultaneously
building the following four "sub-models":
[0020] (a) a model corresponding to most of the interior of the
color model;
[0021] (b) a model corresponding to grayscale rendering of the
amount (i.e., number of layers) of cyan to be layered at the
surface of the color model (the darker the grayscale, the more
surface layers of cyan);
[0022] (c) a model corresponding to grayscale rendering of the
amount (i.e., number of layers) of magenta to be layered at the
surface of the color model (the darker the grayscale, the more
surface layers of magenta); and
[0023] (d) a model corresponding to grayscale rendering of the
amount (i.e., number of layers) of yellow to be layered at the
surface of the color model (the darker the grayscale, the more
surface layers of yellow).
[0024] Thus, if such an imaging printer is sent an STL data file
describing each of these four sub-models for simultaneously
printing, the imaging printer will print (i.e., build) each
sub-model simultaneously on the printer platform thereby resulting
in the color model being built. Accordingly, a modified embodiment
of a currently available imaging printer will continue to print a
model, or several models simultaneously. However, for building a
color model, each sub-model will be printed through a predetermined
different jet array of the imaging printer. Therefore, a new and/or
retrofitted solid imaging will simultaneously print all four
sub-models (e.g., three grayscale sub-models of the color model and
a non-colored interior sub-model of the colored model), but the
sub-models will be printed in the same space on the printing
platform of the printer.
[0025] Thus, the primary software modification necessary for
implementing the present invention with a currently available solid
imaging printer is a modification to the CAD software so that each
of the above described sub-models are represented in, for example,
a different STL data file prior to exporting these files to the
imaging printer. Therefore, the main modification to the software
for retrofitting the present invention to use current printers is
an addition and/or enhancement of a pre-processing module to obtain
the STL files of the submodels prior to activating such a printer.
In particular, this pre-processing module identifies and separates
portions of an image by color at the CAD software workstation as an
export filter prior to the creation of an STL file. The four STL
files output by the color export filter will have no color
information included in them, just as two dimensional color
separations have no color information included in them.
[0026] It is also an aspect of the present invention that together
with at least one of four sub-model STL files, a descriptor or
other identification may be exported indicating which sub-model
file corresponds to which primary color. Alternatively,
predetermined file naming conventions may be used for identifying
the color to be used in rendering each sub-model STL file.
[0027] Thus, at a high level (and as will be explained more fully
in the Detailed Description herein), the following steps are
performed by the present invention:
[0028] (a) Separate the color data of a full color object, texture
map, three-dimensional color scan, etc. into three primary colors
and create separate "shell objects" of the primary colors. Shells
would be preferred rather than solid objects, as the interior of
the color is not needed and the amount of material needed to print
a shell is greatly reduced.
[0029] (b) Send (or transfer) the shell object data and the primary
substrate object data to the printing machine in the same manner as
is currently performed, with the main difference being to send each
object to a separate printhead, and build the object in the same
fashion as is currently performed, with the exception being to
build each object in the same three-dimensional space rather than
four separate spaces.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Referring now to the figures, wherein like elements are
numbered alike:
[0031] FIG. 1 illustrates a prior art solid imaging printer;
and
[0032] FIG. 2 is a diagram illustrating high level software and
electronic components of both the solid imaging printer of prior
art FIG. 1 and an enhanced solid imaging printer.
DETAILED DESCRIPTION
[0033] Those of ordinary skill in the art will realize that the
following description of the present invention is illustrative only
and not in any way limiting. Other embodiments of the invention
will readily suggest themselves to such skilled persons.
[0034] The present application is based on the idea that an entire
color three-dimensional model does not need to be printed or built
in color, i.e., in substantially every application requiring a
color three-dimensional model, only the surface or skin thereof
requires specified coloring. Accordingly, the amount of colorizing
material needed to produce the desired coloring of a
three-dimensional model surface is considerably less than the
amount required to color the interior of the model as well.
[0035] FIG. 1 illustrates a prior art solid imaging printer 10. The
printer has a platform 20, which is movable in two dimensions
(i.e., the "Y" and "Z" directions as shown by the arrows 22 and 24
respectively) by a controller (not shown in FIG. 1, but represented
as a "planar mechanism" 48 in FIG. 2). The platform 20 provides the
support upon which a three-dimensional model 26 can be printed.
Above both the platform 20 and the model 26 is a printhead assembly
28 for iteratively printing layers of a model building material
supplied to the printhead assembly 28 via conduit 30. The printhead
assembly 28 includes four printheads therein (not individually
shown in FIG. 1, but shown individually as 40a-40d in FIG. 2),
wherein each of the printheads outputs one or more sprays (or
droplets) 32 of the model building material through an end 34 of
the printhead assembly 28. Thus, each printhead receives model
building material that has typically been heated to a liquid state
so that it can flow through the conduit 30. Moreover, the model
building material must remain in a liquid state in order to be
sprayed from each of the printheads and subsequently solidify and
adhere to the exposed upper surfaces of the model 26. Accordingly,
the printhead assembly 28 includes one or more heated model
building material reservoirs (not individually shown in FIG. 1) for
retaining this material in a heated and pressurized (or vacuous)
state conducive to being sprayed. In a typical printhead assembly
28, there is such a separate substrate reservoir for each
printhead. Each printhead further includes a series of one or more
jets 36 for outputting the series of one or more sprays 32 from the
end 34. For each printhead, the series of jets 36 therefore are
adjacent to one another across the length of the end 34 (the length
being in the Y direction of arrow 22). Thus, there are four
substantially equally spaced series of jets 36 distributed across
the end 34, one series of jets 36 per printhead (one such series of
jets 36 is illustrated in the magnified portion of FIG. 1).
[0036] Accordingly, as the printhead assembly 28 moves in the "X"
direction (as shown by the arrow 38) and the platform 20 moves in
the "Y" (as shown by the arrow 22) and "Z" (as shown by the arrow
24) directions, the series of jets 36 of the printheads are able to
iteratively spray successive layers onto the adjacent most surfaces
of the model 26 underneath the printhead assembly 28. Moreover, any
combination of printheads can be activated to spray the model
building material so that at any given time zero or up to all four
of the printheads may be depositing the model building material on
the model 26.
[0037] FIG. 2 illustrates a schematic diagram of a prior art solid
imaging printer 10, having four individual printheads 40a, 40b,
40c, and 40d of the printhead assembly 28. For simplicity, only a
single jet 36 is illustrated depositing the model building material
as droplets 32 from each one of the printheads 40a, 40b, 40c, and
40d.
[0038] The components that control the solid imaging printer 10,
such as the control electronics 42 for controlling the movement of
both the platform 20 (via the planar mechanism 48) and the movement
of the printhead assembly 28.
[0039] Additionally represented is the control software 44
directing the control electronics 42 to perform various tasks such
as moving the platform 20 a specified amount in a specified
direction, moving the printhead assembly 28 a specified amount in a
specified direction, activating a specified one or more of the
printheads 40a-d for spraying the model building material, and the
like. Additionally illustrated is CAD system 46 for generating the
data files for building and coloring the model 26. The data path
between the CAD system 46 and the control software 44 may include a
portion of a network, such as the Internet. An overhang support 50
can also be located on the platform.
[0040] In retrofitting a currently available solid imaging printer
10 such as is shown in FIGS. 1 and 2, for the operationalizing
present invention, one or more modifications to the printhead
assembly 28 of the solid imaging printer 10 may be required.
Although the prior art printer 10 uses four printheads 40a-40d, it
outputs only the single colored (or colorless) model building
material from all four of the printheads.
[0041] Another embodiment includes the following modifications to
the printhead assembly 28:
[0042] (a) Provide (if not already provided) a separate model
building material reservoir for each of the printheads 40a-40d;
[0043] (b) Attach and direct the conduit 30 to feed only one of the
printhead reservoirs, wherein the printhead for this reservoir is
for printing the bulk of the interior of the model 26 with model
building material that needs no particular color;
[0044] (c) Attach to the top of the three other reservoirs lids and
seals so that there is one reservoir for each of a small quantity
of colored model building material, and more particularly, one of
these reservoirs for each of, for example, a cyan colored model
building material, a magenta colored model building material, and a
yellow, model building material (or another set of three primary
colors); and
[0045] (d) Additionally, such retrofits may require some ancillary
electrical/data modifications to support the above described
printhead assembly 28 modifications.
[0046] The present invention requires minimal modifications to the
model building material feed systems of presently available solid
imaging printers 10. A model building material feed system (not
shown) is modified such that the existing bulk material feed system
using, for example, a white liquid model building material is
attached to only one (e.g., 40a) of the four printheads reservoirs
and the other three printheads are only attached to other three
small reservoirs residing directly, for example, on the top of
these other three printheads (e.g., 40b, 40c, and 40d). The bulk
substrate feed (not shown), bulk melter (not shown), axis movement
systems (i.e., planar mechanism 48) and the majority of the
remainder of the printer 10 function as originally designed, as one
skilled in the art will understand. Accordingly, just as in the
non-modified printhead assembly 28, air is used to either
pressurize or vacuum the model building material in the reservoirs
and force this material (colorized and non-colorized) onto the
model 26 and/or the platform through the corresponding printhead
60. Additionally, note that each colorized version of the model
building material maybe in solid form prior to being, for example,
manually placed in its corresponding reservoir. Alternatively, an
amount of the non-colorized model building material may be combined
in such reservoir with a die for colorizing the model building
material within its heated reservoir.
[0047] In generating a three-dimensional model with an imaging
printer, it is often the case that more than 1,000 times the amount
of ink needed for a two dimensional print is required. Thus, an
imaging printer according to the present invention may, in some
embodiments, also utilize an oversized substrate reservoir and
additional substrate heating and/or melting components.
[0048] Thus, such a retrofit of a printer 10 is able to
substantially utilize the existing heating, material storage, and
electrical components incorporated of currently available printhead
assemblies provided by manufacturers as one skilled in the art will
appreciate.
[0049] As indicated in FIG. 2, the software typically includes a
CAD system 46 and control software 44, wherein these two software
components may communicate via a communications network.
Accordingly, in such a configuration, the CAD system 46 (and any
other co-located auxiliary components such as the pre-processing
module identified herein above) may be referred to as the "client
side" system(s) for model building via a (modified or otherwise)
printer 10. Conversely, the control software 44 (and any other
co-located auxiliary software components) may be referred to as the
"server side" system(s) for model building with a co-located
(modified or otherwise) printer 10.
[0050] On the "server side", the current way in which
three-dimensional models are built with a solid imaging printer 10
remains functionally the same as in the retrofitted version
embodying the present invention. However, the only addition or
change to such "server side" software is the introduction of
software for identifying and utilizing an STL file name convention
(or other distinguishing technique such as data descriptors within
the files) that allows the "server side" software to recognize and
distinguish between the STL data files for the different sub-models
(as described in the SUMMARY Section above). Thus, for example, a
data file for each sub-model may be identified by its file
name.
[0051] Present practice in the art is to name data files defining
support structures for models with a suffix of "_s". Thus, if the
data file for a model (or portion thereof) is named with the "_s"
as a suffix to its file name, the printer 10 will interpret it as
being a data file for defining a support structure for a
corresponding model. Moreover, it is typical that the control
software 44 for such imaging printers 10 build such support
structures hollow since only enough substrate is used in building
such a support structure as is needed to effectively support the
model while it is being concurrently built. Accordingly, this
technique of using a file name suffix to inform the control
software 44 whether to build an object as solid or hollow together
with the capability of building a plurality of such objects
concurrently can be utilized to enable the present invention. That
is, in one embodiment, the control software 44 may be modified to
recognize additional file name suffixes of the form "_x.stl" on
data file names received from, for example, the CAD system 46. For
example, a model data file (having the data defining a desired
model or part) may be created with and subsequently identified by a
suffix of ".sub.--1.stl" appended to the file name.
[0052] Accordingly, the software controller 44 can then interpret
such a file as having model data wherein the entire interior to the
model is printed (i.e., filled with model building material).
Moreover, the control software 44 may associate such model data
with only the predetermined printhead that receives model building
material via the conduit 30. Additionally, it can be assumed that
there are grayscale sub-model data files (e.g., for each of cyan,
magenta, and yellow) for the model and that there are different
file name suffixes for each of these grayscale sub-model data files
as well (e.g., such as ".sub.--2.stl" for the cyan grayscale
sub-model, ".sub.--3.stl" for the magenta grayscale submode, and
".sub.--4.stl" for the yellow grayscale sub-model). In this case,
the control software 44 can be modified so that each such file name
suffix is associated with exactly one of the printheads 40a-40d of
the printhead assembly 28. For example, assuming printhead 40a
receives the substrate from the conduit 30, then the control
software 44 will assign data files having a ".sub.--1.stl" suffix
to be printed by printhead 40a. Additionally, the control software
44 can assign data files having a ".sub.--2.stl" suffix to be
printed by printhead 40b, assign data files having a ".sub.--3.stl"
suffix to be printed by printhead 40c, and assign data files having
a ".sub.--3.stl" suffix to be printed by printhead 40d.
[0053] Thus, in using this file naming convention (or any other
similar conventions) then color three-dimensional models may be
generated in a conventional manner with minor modifications to the
control software 44. That is, the control software 44 may be
modified so as to execute the programs that build hollow
structures, such as the model supports described above, when a data
file has suffix identifying a data file for a primary color
grayscale sub-model (e.g., cyan, magenta, or yellow), and execute
the programs for building a non-hollow or solid object
otherwise.
[0054] On the "client side", the data model preparation module
(which includes the pre-processing module mentioned above) remains
functionally the same in that it prepares STL data files for model
building by a solid imaging printer. However, the present invention
also includes modifications to such modules. In particular, one
such modification includes specifying different data model (i.e.,
STL) files for each of the four different printheads 40a-40d of the
printhead assembly 28. In particular, this may be accomplished by
the naming convention discussed above, or a switch or flag in the
data file header, or other ways known in the art, if needed.
However, it is within the scope of the present invention that the
assignment as to which printhead builds which sub-model can be
determined on either the "client side" or the "server side", or, on
both sides (e.g., a default assignment on the "client side" and a
default over ride on the "server side"). In one preferred
embodiment, the "server side" may determine such assignments.
[0055] Moreover, in one embodiment, such data model preparation
modules on the "client side" use the existing conventions for
naming data model files, wherein a data model file named "part.stl"
is interpreted differently than a data model file named "part
s.stl". Accordingly, for a data model preparation module for the
present invention, three additional "color" data model files may be
output. The additional data model files may be a data file for
printing cyan (e.g., having a file name suffix of "_c.stl"), a data
file for printing magenta (e.g., having a file name suffix of
"_m.stl"), and data file for printing yellow (having a file name
suffix of "_y.stl"). Thus, when the control software 44 receives
files with such suffixes, it will associate these file names with a
corresponding printhead. The original data model CAD file, from
which the corresponding grayscale sub-model data files are derived,
is still provided to the printer (regardless of the technique for
assigning the sub-model data files to their particular printheads)
since this file provides the model data for depositing the base
model building material (which is not colored, i.e., white or
opaque).
[0056] An important modification of the "client side" software is
provided by a novel software subsystem referred to as an "STL color
export filter" (or simply "filter"). The STL color export filter is
designed to be used with a particular (or several)
three-dimensional rendering or CAD packages. The function of the
STL color export filter is to create from a CAD three-dimensional
model both an STL data file corresponding to the three-dimensional
CAD model (as is currently performed in the art), and STL data
files for one or more textures or image maps corresponding to, for
example, the color of the surfaces of the CAD three-dimensional
model within the CAD or three-dimensional package.
[0057] These STL data files for textures or image maps may be
considered as generalizations of the sub-model data files described
above, in that in addition to model surface color characteristics,
the data defining various surface patterns may by also provided
therein. Such STL data files for textures or image maps are
referred to as "shells" (a model skin having a relatively shallow
depth into the interior of the model, and accordingly being
substantially hollow). The data files for these "shells" may be
processed similarly to support files currently used to generate
model supporting structures during the solid model building
process.
[0058] Currently three-dimensional CAD and three-dimensional image
mapping software, such as 3D Studio by Autodesk Inc., apply color
images to the surfaces of three-dimensional models (inside computer
software only, no physical parts) in a fashion known as "mapping".
For example, the mapping procedure assigns a coordinate in the
image to each vertex of the three-dimensional object. In this
example, a selected two dimensional image is applied to the surface
of a three-dimensional model (e.g., wrapping a two dimensional logo
on to a coffee mug). For instance, colored images or photographs
may be mapped to the exterior of a three-dimensional object using
the CAD space coordinates of the object as reference points or
coordinate system.
[0059] The coordinate systems are the geometric relation used to
denote the location of points in three-dimensional space. The most
common is the rectangular coordinate system, whereby points are
located by traversing the x, y and z axes of three-dimensional
space. Normally, the origin of a coordinate system is defined as
0,0,0 though this is not required, as one skilled in the art will
understand. Accordingly, each pixel of the mapped image is
"wrapped" onto a surface of the three-dimensional object, and the
CAD space values (i.e., modeling space coordinates) are stored for
both the position of the object and the image mapped to it.
Concurrently, the color value of each pixel of an image mapped to
an object is also stored.
[0060] Each such CAD space value or point is referred to as a
vertex. A vertex is generally defined as three coordinates
separated by commas, one each for the x, y, and z coordinate axes
denoting the location of the vertices in three-dimensional space. A
two dimensional computer bitmap image is a photographic image
composed of pixels or picture elements defined in two dimensional
space (x, y coordinates only). Each pixel of a bitmap image is
defined as a color value composed of, for example, a number between
0 and 255 for each of the colors red, green, and blue. In this
case, 0 represents the darkest or least illuminated portion of a
color (black), and 255 represents the lightest or most illuminated
portion of a color (white). Red green and blue values are used to
display images on a computer screen, however these values must be
converted or interpreted into values used for printing inks.
[0061] These values are commonly referred to as cyan magenta and
yellow (CMY). CMY values are represented in percentages of
luminosity from light to dark with 0% being white (255 in RGB), 50%
equal to medium gray (128 in RGB), and 100% equal to black (0 in
RGB). In one embodiment, the following steps (A-C) may be performed
to separate the color values (i.e., for cyan, magenta and yellow)
of a bitmap images into individual STL files:
[0062] (A) Convert the RGB color values mapped to an object by
three-dimensional CAD software into cyan, magenta, and yellow (CMY)
color percentage values in the same fashion as is performed by
popular image editing and color separation software, such as Adobe
Systems Photoshop.
[0063] (B) Perform a Boolean subtraction in the CAD system 46,
wherein for a given surface area resolution surface pixels, and for
each color (C) (cyan, magenta and yellow), the CAD object has
subtracted therefrom a second CAD object that is interior to the
initial CAD object and wherein at each surface pixel (P) of the
initial CAD object, the second CAD object has a corresponding
surface pixel P0 that is offset from P toward the interior of the
initial CAD object in a surface normal direction at P. In
particular, each such offset is to a depth varying directly with a
color value percentage (i.e., color saturation) of the bitmap pixel
for the color C. For instance, a 1% color value percentage may
correspond to an offset of 0.001 inches, a 50% color value
percentage may correspond to an offset of 0.05 inches, and a 100%
color value percentage may correspond to an offset of 0.1
inches.
[0064] (C) Export the results of each Boolean subtraction as a
separate STL file in the same manner as is currently utilized by
CAD software for three-dimensional objects applying the
corresponding suffix (e.g., "c.stl", "m.stl", or "y.stl") to each
data file name to correspond with the color value used to subtract
the object from the original of either cyan magenta or yellow.
[0065] This process can be illustrated as follows. A computer
picture is composed of pixels or picture elements. The
corresponding three-dimensional model is built from drops of the
liquid model building material (having a composition similar to
"wax") that hardens. If the resolution of the three-dimensional
model was determined to be 300 dots or drops per inch (dpi), then
the maximum resolution for the image to be applied to the skin of
the model should be fixed at (or no larger than) 300 dpi along the
x or y axis (x and y axes here corresponding to the x and y axes
of, for example, FIG. 1). If the model is determined to be sliced
at a resolution of 1000th of an inch thickness (along the z axis),
then the resolution of the color bitmap in the z direction should
not exceed 1000 dpi.
[0066] Perhaps for simplification, the initial embodiment of the
export filter could call out 600.times.600.times.600 dpi parts (x,
y, z dimensions) and 600.times.600 dpi images (x, y dimension) to
correspond. Lower or higher resolution images applied to a model
may be extrapolated or interpolated to the correct resolution
before creation of the STL files. This type of software definition
could then be released to different CAD vendors in order to let the
CAD vendor write the actual export filters for their software as
they do currently with the standard STL file export definition.
[0067] The materials utilized in the present invention need to be
modified. In one embodiment, the model building materials from
which three-dimensional models may be constructed are substantially
the same as the model building materials used in current solid
imaging printers, except that in the present invention three
differently colored versions of such a model building material is
used. For example, the model building material may be provided in
the three primary colors of cyan, magenta and yellow.
[0068] Moreover, providing the three colored versions of the model
building material is a simple process of adding the correct dye
formulation to the typically white model building material
currently in use. Black colored material is not needed for the
present invention since the three primary colors mixed produce a
near perfect black. In traditional two dimensional printing where
the ink thickness on a page is so thin (e.g., about 100 microns)
that the page color shows through the ink, black is used to hide
the paper color. In the present invention, the colored material
would predominately hide the white since the colored material is
applied in drop size or thickness (e.g., about 0.004 inches to
about 0.008 inches).
[0069] Additionally, the amount of colored material needed depends
upon geometry of a three-dimensional model's surface area. However,
in general it is believed that the amount of colored material
required for coloring the surface of the model is about {fraction
(1/100)} of the amount of the model building material required to
construct the entire model.
[0070] Moreover, since the amount of colored material may be
considered to be approximately the same (e.g., one primary colored
material used at the rate of no more than twice any other colored
material), the amount of any one of the primary colored materials
for coloring a model having a surface area of, for example, about
four inches square, will typically fit in a very small cartridge.
This is compared to the amount of material in the substrate
reservoir used to build the internal solid structure of the model.
Thus, the small amount of the colored model building material
typically required allows for placement of the model building
material reservoirs directly over the printheads, as described
above.
[0071] Utilizing the method of skin (or shell) printing according
to the present invention, specialized external model building
materials could be used (instead of color or in conjunction with
color) for applying to the exterior surface of a three-dimensional
model being printed. For example, model building materials may be
utilized that are designed to resist breaking, induce electrical
conductivity, resist degrading with increased heat and/or cold,
resist corrosion by certain chemicals, and the like. This method
also allows internal part structures to obtain the exterior
materials, if desired, and the possibilities are almost endless and
unknown (this process can be extended to build internal skins or
"parts inside of parts" for the purpose of electrical connections,
to increase part strength, and the like).
[0072] It is common practice in the art to plan off a small amount
of each layer deposited when generating a three-dimensional model
with a "planarizer". Planarizing 30% of the model building material
of each layer off the model surface may induce color streaks or
distort the colors. The present invention prints the colors in a
specific order according to the density of the color. That is,
since magenta is the darkest of the three primary colors it is
printed first, then cyan, and then yellow. Also, if no color is
specified, then the white of the model building material is
provided. Thus, the plananizer will wipe the least contributive
color (e.g., yellow and white) off of the top of each layer either
intermittently or after the application of every layer to the model
since these colors are minor contributors to the more rich or
darker colors. Also, it may be desirable to increase the layer
thickness slightly and reduce the percentage of material scraped
off of each layer, since models built with color may have a more
aesthetic function, whereas models built in one color are generally
built to be cast and need tighter dimension tolerances. Models
built in color may be created as a final product. Models built in
one color are designed to be either disposable (e.g., as a product
of a rapid prototyping step in the process for manufacturing a
part) or to be for casting many parts from a mold created by the
one color model.
[0073] In one embodiment, the following software was used to
implement the invention:
[0074] (a) Photoshop by Adobe Systems Inc. This software package
was used for color separation and image size modification.
[0075] (b) Streamline, by Adobe Systems Inc. This software package
was used for intermediate conversion of color data in bitmap form
converted to vector based data for CAD program recognition.
[0076] (c) Rhinoceros Nurbs modeling Software, from Robert McNeil
and Associates for creating three-dimensional objects, and
extrusion of the two dimensional vectors created in Streamline into
the third dimension along the z axis, and Boolean addition and/or
subtraction of three-dimensional geometries.
[0077] (d) 3D LightYear, by 3D Systems, Inc. for adding the "_s" to
the file name causing the software to interpret a sub-model as a
support and therefore not a solid structure, but instead only a
shell.
[0078] (e) 3D Studio Max, by Autodesk Inc for creating
three-dimensional objects, and mapping two dimensional full color
photographs to the skin of three-dimensional objects.
[0079] Additionally, the present invention may be particularly
useful in:
[0080] (a) manufacturing of prototypes for toys, medical equipment,
topographical maps;
[0081] (b) the replication of any object to duplicate its form or
likeness, such as a celebrity or an ancient artifact, or geological
find;
[0082] (c) to duplicate any existing physical object out of a less
expensive material than the original is composed of, or to
duplicate any object wherein multiples of that object cannot be
obtained, (one of a kind items);
[0083] (d) to replicate the internal structures in full color
detail of living entities such as animals or humans, for display or
scientific instruction, purpose;
[0084] (e) to replicate in a "frozen" or static form data that is
captured from singular or plural "short events" such as
explosions/implosions, tornadoes, clouds and other atmospheric
phenomena; and
[0085] (f) to replicate objects either too large or small to be
seen with the naked eye at a size one could easily perceive, such
as stellar or microscopic bodies from galaxies to DNA pattern
structure.
[0086] While the invention has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings without
departing from the essential scope thereof. Therefore, it is
intended that the invention not be limited to the particular
embodiment disclosed as the best mode contemplated for carrying out
this invention, but that the invention will include all embodiments
falling within the scope of the appended claims.
* * * * *