U.S. patent application number 13/208992 was filed with the patent office on 2012-03-15 for fabrication of non-homogeneous articles via additive manufacturing using three-dimensional voxel-based models.
This patent application is currently assigned to SENSABLE TECHNOLOGIES, INC.. Invention is credited to David T. Chen, Robert Steingart.
Application Number | 20120065755 13/208992 |
Document ID | / |
Family ID | 46719152 |
Filed Date | 2012-03-15 |
United States Patent
Application |
20120065755 |
Kind Code |
A1 |
Steingart; Robert ; et
al. |
March 15, 2012 |
FABRICATION OF NON-HOMOGENEOUS ARTICLES VIA ADDITIVE MANUFACTURING
USING THREE-DIMENSIONAL VOXEL-BASED MODELS
Abstract
The invention provides systems and methods for manufacture of a
non-homogeneous article using a 3D voxel-based model of the article
and a rapid prototyping device. Use of a voxel-based model provides
processing advantages and offers improved realism of the
manufactured object with regard to non-homogeneous (i) color, (ii)
translucency, and/or (iii) hardness, for example.
Inventors: |
Steingart; Robert;
(Wellesley, MA) ; Chen; David T.; (Wrentham,
MA) |
Assignee: |
SENSABLE TECHNOLOGIES, INC.
Wilmington
MA
|
Family ID: |
46719152 |
Appl. No.: |
13/208992 |
Filed: |
August 12, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61373780 |
Aug 13, 2010 |
|
|
|
61426839 |
Dec 23, 2010 |
|
|
|
61373785 |
Aug 13, 2010 |
|
|
|
61445960 |
Feb 23, 2011 |
|
|
|
Current U.S.
Class: |
700/98 |
Current CPC
Class: |
B33Y 30/00 20141201;
B33Y 80/00 20141201; B33Y 50/00 20141201; A61C 13/0019
20130101 |
Class at
Publication: |
700/98 |
International
Class: |
G06F 17/50 20060101
G06F017/50 |
Claims
1. A method for manufacturing an aesthetically-acceptable
non-homogeneous object, the method comprising the steps of: (a)
defining a 3D voxel representation for the non-homogeneous object
to be manufactured, wherein each of a plurality of voxels is
assigned one or more values representing one or more of the
following prescribed physical properties M: color, translucency,
and hardness; (b) using the 3D voxel representation to: (i) define
a set of 3D dots to produce a shape of each of a plurality of
successive Z-layers of the object to be manufactured and (ii)
define the one or more prescribed physical properties at each dot
making up each of the successive Z-layers of the object to be
manufactured; (c) defining a transfer function T(M) that identifies
a pigment, a resin, or both a pigment and a resin to produce a
material having the one or more prescribed physical properties for
each 3D dot to be printed; and (d) using a 3D printer to deposit
the pigment and/or the resin identified by the transfer function at
each dot of each of the plurality of successive Z-layers of the
object, thereby producing the non-homogeneous object.
2. The method of claim 1, wherein step (b) comprises using
multivariate interpolation to define the one or more prescribed
physical properties at each 3D dot.
3. The method of claim 2, wherein the multivariate interpolation is
trilinear interpolation.
4. The method of claim 1, wherein the transfer function T(M)
identifies multiple pigments and/or multiple resins.
5. The method of claim 1, wherein the non-homogeneous object is one
or more teeth.
6. The method of claim 1, wherein a value of the one or more
prescribed physical properties varies within the object and/or
within each of the Z-layers of the object.
7. The method of claim 1, wherein the 3D printer is a rapid
prototyping device.
8. The method of claim 1, wherein the one or more prescribed
physical properties comprises translucency, and wherein step (d)
comprises depositing at least two different resins with embedded
crystalline particles at a given dot, the combination of which
resins produces the translucency prescribed for the given dot.
9. The method of claim 1, wherein the embedded crystalline
particles have a known size distribution.
10. The method of claim 1, wherein one or more of the voxels has at
least one associated real world dimension that is no greater than
about 10 microns.
11. The method of claim 1, wherein the 3D voxel representation
defined in step (a) is partitioned into a hierarchy of blocks,
wherein each block: (i) has one or more spatial properties in
common; and/or (ii) has one or more of the prescribed physical
properties in common.
12. A system for fabricating a non-homogeneous article, the system
comprising: a user interface configured to receive input from a
user; a design application in communication with the user
interface, wherein the design application is configured to create a
3D voxel-based model of a non-homogeneous article, wherein each
voxel is assigned one or more physical properties; and a rapid
prototyping machine for fabrication of the non-homogeneous article,
wherein said rapid prototyping machine is configured to fabricate
the artificial tooth via additive manufacturing using the 3D
voxel-based model, wherein properties of the voxels of the model
correspond to properties of the voxels of the fabricated
article.
13. The system of claim 12, wherein the physical properties
comprise at least one of color, translucency, hardness, modulus,
and dynamic modulus.
14. The system of claim 12, wherein the system is configured to
perform additive manufacturing by providing successive layers or
parcels of material.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of, and
incorporates herein by reference in their entireties, U.S.
Provisional Patent Application No. 61/373,780, which was filed on
Aug. 13, 2010, U.S. Provisional Patent Application No. 61/426,839,
which was filed on Dec. 23, 2010, U.S. Provisional Patent
Application No. 61/373,785, which was filed on Aug. 13, 2010, and
U.S. Provisional Patent Application No. 61/445,960, which was filed
on Feb. 23, 2011.
FIELD OF THE INVENTION
[0002] This invention relates generally to rapid prototyping
(additive manufacturing) systems. More particularly, in certain
embodiments, the invention relates to systems for manufacture of
non-homogeneous articles using 3D voxel-based models and a rapid
prototyping device.
BACKGROUND OF THE INVENTION
[0003] Rapid prototyping is used to construct physical objects,
particularly prototype parts or small volume manufactured
components. Rapid prototyping systems make use of additive
manufacturing technology, wherein a machine uses digital data from
a virtual model of the object and deposits successive layers or
parcels of liquid, powder, or sheet material, corresponding to
layers or parcels of the virtual model. The layers or parcels bind
together (either upon contact or by application of heat and/or
binding materials), and the part is thereby produced.
[0004] To date, there have been no commercial 3D printers capable
of rapid manufacture of realistic-looking, aesthetic teeth,
veneers, or other dental implants. This largely has to do with the
variation in color, translucency, hardness, and other properties
within a tooth, and the difficult of manufacturing a close replica
of such a complex organic object.
[0005] The optical properties of a solid material are defined by
the way in which light waves interact with it through absorption,
scattering, reflection, transmittance and refraction. When white
light is incident on a solid material, its color is defined by
which frequencies are absorbed, and which are reflected back (or
transmitted, in the case of glass) to an observer. The reflection
can be either reflective, in which case the object will have a
specular or glossy appearance, or diffusive, in which the object
will appear to have a more matte finish.
[0006] Tooth enamel, dentin, cementum, and dental pulp are four
major tissues which make up the tooth in vertebrates. Enamel is the
hardest and most highly mineralized substance in the human body.
Enamel is the visible dental tissue of a tooth because it covers
the anatomical crown and is supported by the underlying dentin.
Ninety-six percent of enamel is mineral, with water and organic
material composing the rest. In humans, enamel varies in thickness
over the surface of the tooth, often thickest at the cusp, up to
2.5 mm, and thinnest at its border with the cementum at the
cementoenamel junction (CEJ). The normal color of enamel varies
from light yellow to grayish white. At the edges of teeth where
there is no dentin underlying the enamel, the color sometimes has a
slightly blue tone. Since enamel is semi-translucent, the color of
dentin and any material underneath the enamel strongly affects the
appearance of a tooth.
[0007] Enamel's primary mineral is hydroxylapatite, which is a
crystalline calcium phosphate. The large amount of minerals in
enamel accounts not only for its strength but also for its
brittleness. Tooth enamel ranks 5 on Mohs hardness scale and a
Young's modulus of 83 GPa. Dentin, less mineralized and less
brittle, 3-4 in hardness, compensates for enamel and is necessary
as a support. On X-rays, the differences in the mineralization of
different portions of the tooth and surrounding periodontium can be
noted; enamel appears more radiopaque (or lighter) than either
dentin or pulp since it is denser than both, both of which appear
more radiolucent (or darker).
[0008] Enamel does not contain collagen, as found in other hard
tissues such as dentin and bone, but it does contain two unique
classes of proteins--amelogenins and enamelins. While the role of
these proteins is not fully understood, it is believed that they
aid in the development of enamel by serving as a framework for
minerals to form on, among other functions. Once it is mature,
enamel is almost totally absent of the softer organic matter.
Enamel is avascular and has no nerve supply within it and is not
renewed, however, it is not a static tissue as it can undergo
mineralization changes.
[0009] Optical transparency in polycrystalline materials is limited
by the amount of light which is scattered by their microstructural
features. Light scattering depends on the wavelength of the light.
Limits to spatial scales of visibility (using white light)
therefore arise, depending on the frequency of the light wave and
the physical dimension of the scattering center. For example, since
visible light has a wavelength scale on the order of a micrometer,
scattering centers will have dimensions on a similar spatial scale.
Primary scattering centers in polycrystalline materials include
microstructural defects such as pores and grain boundaries.
[0010] The hardness of a solid material is determined by its
microstructure, or the structure and arrangement of the atoms at
the atomic level. At the atomic level, the atoms may be arranged in
an orderly three-dimensional array called a crystal lattice.
However, a given specimen of a material likely never contains a
consistent single crystal lattice. The material will likely contain
many grains, with each grain having a fairly consistent array
pattern. At a smaller scale, each grain contains irregularities. It
is these irregularities at the grain level of the microstructure
that are responsible for the hardness of the material.
[0011] When considering the rapid manufacture of non-homogeneous
articles, such as teeth, material parameters need to be precisely
controlled throughout the print volume in order to achieve an
aesthetically acceptable result, since those parameters vary
throughout the volume of the object. For example, color,
translucency, hardness, elasticity, and the like, vary throughout
the solid.
[0012] Current prototyping techniques employ Stereo Lithography
File (STL) data structures (e.g., triangles or other polygons
defining the surface of the object) that rapid prototyping machines
use as input. Even in the simplest case where only a single
parameter, such as color, varies throughout a solid, the required
STL-based geometry is difficult to construct. For example, consider
a red and white candy cane. Using STL geometry would first require
defining the surface of the basic cane, then defining the
complicated spiral shape of the red surface independently; and then
performing a constructive-solid-geometry operation to define the
white surface through a subtraction.
[0013] There is a need for improved methods for rapid prototyping
of non-homogenous objects.
SUMMARY OF THE INVENTION
[0014] Systems and methods are provided for the fabrication of
non-homogeneous articles via additive manufacturing using
three-dimensional voxel-based models. These systems and methods
make it possible to rapidly build a prototype, or perform small
volume manufacture, of an article that has varying colors, shades,
textures, and/or other properties throughout the article.
[0015] For example, a tooth has a variety of portions having
different properties, e.g., the enamel, dentin, pulp, cementum, and
root of a tooth have different color, translucency, hardness, etc.
A property that varies throughout the article (e.g., color) can be
represented by assigning each voxel in a virtual model of the
article a value corresponding to that property. The rapid
prototyping machine then deposits material on a voxel-by-voxel
basis (or parcel-by-parcel basis, if more than one voxel is grouped
at a time), such that the deposited material in each voxel has the
property value (e.g., color) assigned to that voxel.
[0016] An artificial tooth for use in a set of dentures is one
example of a heterogeneous (i.e., non-homogeneous) article that can
be quickly fabricated using the systems and methods described
herein. Other examples include jewelry, footwear, industrial parts,
automotive parts, medical devices, and prosthetics, to name a
few.
[0017] In one aspect, the invention relates to a method for
manufacturing an aesthetically-acceptable non-homogeneous object
(e.g., one or more teeth). The method includes the steps of: (a)
defining a 3D voxel representation for the non-homogeneous object
to be manufactured, wherein each of a plurality of voxels is
assigned one or more values representing one or more of the
following prescribed physical properties M: color, translucency,
and hardness; (b) using the 3D voxel representation to (i) define a
set of 3D dots to produce a shape of each of a plurality of
successive Z-layers of the object to be manufactured, and (ii)
define the one or more prescribed physical properties at each dot
making up each of the successive Z-layers of the object to be
manufactured; (c) defining a transfer function T(M) that identifies
a pigment, a resin, or both a pigment and a resin to produce a
material having the one or more prescribed physical properties for
each 3D dot to be printed; and (d) using a 3D printer (e.g., a
rapid prototyping device) to deposit the pigment and/or the resin
identified by the transfer function at each dot of each of the
plurality of successive Z-layers of the object, thereby producing
the non-homogeneous object.
[0018] In certain embodiments, step (b) includes using multivariate
interpolation (e.g., trilinear interpolation) to define the one or
more prescribed physical properties at each 3D dot. In one
embodiment, the transfer function T(M) identifies multiple pigments
and/or multiple resins. In another embodiment, a value of the one
or more prescribed physical properties varies within the object
and/or within each of the Z-layers of the object.
[0019] In certain embodiments, the one or more prescribed physical
properties includes translucency, and step (d) includes depositing
at least two different resins with embedded crystalline particles
at a given dot, the combination of which resins produces the
translucency prescribed for the given dot. The embedded crystalline
particles may have a known size distribution. In one embodiment,
one or more of the voxels has at least one associated real world
dimension that is no greater than about 10 microns. In another
embodiment, the 3D voxel representation defined in step (a) is
partitioned into a hierarchy of blocks, wherein each block: (i) has
one or more spatial properties in common; and/or (ii) has one or
more of the prescribed physical properties in common.
[0020] In another aspect, the invention relates to a system for
fabricating a non-homogeneous article. The system includes a user
interface configured to receive input from a user; a design
application in communication with the user interface, wherein the
design application is configured to create a 3D voxel-based model
of a non-homogeneous article, wherein each voxel is assigned one or
more physical properties; and a rapid prototyping machine for
fabrication of the non-homogeneous article, wherein said rapid
prototyping machine is configured to fabricate the artificial tooth
via additive manufacturing using the 3D voxel-based model, wherein
properties of the voxels of the model correspond to properties of
the voxels of the fabricated article.
[0021] In certain embodiments, the physical properties include at
least one of color, translucency, hardness, modulus, and dynamic
modulus. The system may be configured to perform additive
manufacturing by providing successive layers or parcels of
material.
BRIEF DESCRIPTION OF THE DRAWING
[0022] The objects and features of the invention can be better
understood with reference to the drawing described below, and the
claims.
[0023] While the invention is particularly shown and described
herein with reference to specific examples and specific
embodiments, it should be understood by those skilled in the art
that various changes in form and detail may be made therein without
departing from the spirit and scope of the invention.
[0024] FIG. 1 is a flow chart for a method of manufacturing an
aesthetically-acceptable non-homogeneous object, according to an
illustrative embodiment of the invention.
DETAILED DESCRIPTION
[0025] It is contemplated that devices, systems, methods, and
processes of the claimed invention encompass variations and
adaptations developed using information from the embodiments
described herein. Adaptation and/or modification of the devices,
systems, methods, and processes described herein may be performed
by those of ordinary skill in the relevant art.
[0026] Throughout the description, where devices and systems are
described as having, including, or comprising specific components,
or where processes and methods are described as having, including,
or comprising specific steps, it is contemplated that,
additionally, there are devices and systems of the present
invention that consist essentially of, or consist of, the recited
components, and that there are processes and methods according to
the present invention that consist essentially of, or consist of,
the recited processing steps.
[0027] It should be understood that the order of steps or order for
performing certain actions is immaterial so long as the invention
remains operable. Moreover, two or more steps or actions may be
conducted simultaneously.
[0028] The mention herein of any publication, for example, in the
Background section, is not an admission that the publication serves
as prior art with respect to any of the claims presented herein.
The Background section is presented for purposes of clarity and is
not meant as a description of prior art with respect to any
claim.
[0029] Previous prototyping techniques use STL-based geometry and
therefore suffer significant limitations, even in producing simple,
non-homogeneous objects, such as the candy cane example described
above. However, a solution presented herein is to switch to a
voxel-based modeling approach. By assigning one or more values to
each voxel in the model that is reflective of physical properties
that vary throughout the volume to be produced, it is much easier
to produce high quality, aesthetically acceptable, non-homogenous
objects. In the candy cane example discussed above, the cane shape
may be first defined in voxels, then a 3D texture map applied to
define the red portion of the candy cane by tagging the appropriate
voxels, with the remaining untagged voxels defined as the white
portion of the candy cane.
[0030] Further, a voxel representation lends itself to a more
accurate, simpler, direct interface of model data with 3D printer
output. Typically, for current STL-based output systems, the STL
file is scan-converted to produce pixels at the printer's native
resolution (dpi or dots per inch) one level at a time, thereby
defining each successive Z-layer. However, voxels lend themselves
to a more efficient, more direct interface with a 3D printer. For
example, the shape and desired material properties of each
successive Z-layer (depth layer) of the object to be manufactured
can be defined by simple tagging of voxels. Values of one or more
physical properties (e.g. color, translucency, hardness,
elasticity, etc.) are then assigned for each voxel.
[0031] Also, voxel representations lend themselves to efficient
processing, e.g., performance of multivariate (e.g., trilinear)
interpolation to drive the printer output on demand and at the
proper resolution. Moreover, in certain embodiments, a block coding
scheme is utilized to represent spatial features of the 3D voxel
models efficiently at a high resolution. For the case of production
of aesthetic teeth, the resolution needed requires voxels no
greater than about 10 microns in one, two, or three dimensions.
Memory space need not be allocated for each voxel--such high
resolution would require many megabytes of RAM. However, this
obstacle is overcome in various embodiments, for example, by
employing a block coding algorithm that partitions space into a
hierarchy of blocks that share the same spatial value and/or
material properties,
[0032] In addition to the processing advantages, voxel
representation offers improved realism of the produced object with
regard to non-homogeneous (i) color, (ii) translucency, and/or
(iii) hardness, for example.
[0033] Regarding color, pigments work by selectively absorbing
certain wavelengths of light in the visible portion of the
spectrum. The use of different pigments and/or different amounts of
pigment among the various dots of each Z-layer of the object being
3D-printed allows representation of non-homogenous color. It is not
necessary to design a rapid prototyping machine with every possible
pigment necessary, but instead, primary colors can be combined to
produce a full range of colors. For example, a combination of three
pigments such as red, yellow, and blue, or a combination of primary
ink colors such as cyan, magenta, yellow, and black (CMYK), or
other combination of colors, may be prescribed for each 3D dot of
each successive Z-layer laid down by the printer. A 3D dot can be
any 3D structure that corresponds to one or more voxels.
[0034] The color mixing can happen in several ways. For example, in
the Objet Geometries, Ltd., prototyping machine, the Connex500.TM.,
it is possible to jet and mix multiple resins simultaneously
(Object Geometries, Let. Is headquartered in Rehovot, Israel, with
U.S. office in Billerica, Mass.). In order to take advantage of the
trichromatic effect, multiple resins are provided in the primary
colors, and these are jetted and mixed in the proper proportion to
produce a desired color for each 3D dot of each layer of the
object. The Connex500.TM. uses a computer controlled print-head,
similar to those used in standard, 2D, ink jet printers to create
3D objects one layer at a time.
[0035] In another embodiment, the structural component of each
printed 3D dot is considered separately from its color. For
example, a uniform resin "structural" material is mixed with the
prescribed combination of primary pigment colors as each droplet is
sprayed to produce a final colored three-dimensional shape.
[0036] Regarding translucency, in order to realistically replicate
a translucent object, the volume fraction of microscopic pores in
the manufactured object should be less than about 1% for
high-quality optical transmission; that is, the material density
should be at least about 99.99% of the theoretical crystalline
density of the object (e.g., tooth, veneer, or dental implant) in
order to provide a realistic, aesthetic manufactured object.
Furthermore, most of the interfaces in a typical metal or ceramic
object are in the form of grain boundaries which separate tiny
regions of crystalline order. When the size of the scattering
center (or grain boundary) is reduced below the size of the
wavelength of the light being scattered, the scattering no longer
occurs to any significant extent.
[0037] In the formation of polycrystalline materials (metals and
ceramics) the size of the crystalline grains is determined largely
by the size of the crystalline particles present in the raw
material during formation (or pressing) of the object. Moreover,
the size of the grain boundaries scales directly with particle
size. Thus, a reduction of the original particle size well below
the wavelength of visible light (about 1/15 of the light wavelength
or roughly 600/15=40 nm) eliminates much of light scattering,
resulting in a translucent or even transparent material.
[0038] Thus, in order to simulate the semi-translucent scattering
appearance of tooth enamel, the rapid manufacturing machine used
should be able to control the size of the microstructural
scattering centers. It is possible to embed crystalline particles
in a photosensitive (UV) epoxy base resin for the purpose of
stereolithography (SLA), for example, as has been done by DSM Somos
of Elgin, Ill., for their NanoTool.TM. product.
[0039] A number of methods for controlling the scattering
appearance of a non-homogenous article are presented herein. For
example, an Objet Connex machine (e.g., Connex500.TM.) features
multiple resins that are mixed and jetted to produce a finished
three-dimensional object. In certain embodiments of the present
invention, two separate photosensitive resins can be provided with
embedded crystalline particles of differing, but known sizes and/or
size distributions. To produce a desired scattering effect would
then involve mixing of these resins in the correct proportions.
[0040] Another approach for controlling the scattering appearance
of a non-homogenous article uses stereolithography (SLA) in the
rapid manufacturing/printing of the 3D object. For example, a
single laser is used to trace and cure one layer of material at a
time. This approach can be extended to include a vat with two or
more different resins, with differing scattering center sizes,
sensitive to different frequencies of light. Here, it is possible
to control the scattering appearance of the non-homogeneous article
by using multiple lasers of different wavelengths to selectively
cure each of the resins individually. This particular method is
also applicable to rapid manufacturing based on DLP (Digital Light
Processor) projection by using multiple light sources with
different wavelengths, such as employed by EnvisionTEC of Gladback,
Germany, in its Perfactory.RTM. system.
[0041] Regarding hardness, as discussed previously for producing
different colors with a rapid manufacturing machine, it would be
cumbersome to make a 3D printing machine including a different
resin for every possible desired material hardness. Thus, certain
embodiments employ composites that are made up of one or more
individual constituent materials that can be selected or mixed
together in the proper proportion before being deposited in each 3D
dot of the object.
[0042] For the problem of printing (rapid prototyping) aesthetic
teeth, a simpler case can be considered, since, in certain
embodiments, the requirements are: a dentin support layer that is
relatively elastic and opaque; a hard enamel layer with variable
scattering properties; and color control through the enamel layers.
In one example, this is accomplished using three different resins,
along with the correct combinations of primary pigment colors.
[0043] A 3D printer capable of printing realistic, non-homogeneous
objects according to an embodiment of the invention uses a
combination of resins and pigments that will approximate any given
set of desired material property parameters M. A transfer function
T of the ideal, desired material properties is defined to yield the
closest matching combination of resins and pigments that the
printer has available. In general, T is likely (though not
necessarily) best chosen as a non-linear function that will depend
on the particular resins and pigments employed.
[0044] FIG. 1 is a flow chart 100 for a method of manufacturing an
aesthetically-acceptable non-homogeneous object, according to an
illustrative embodiment of the invention. In step 102, a 3D voxel
representation is defined for the non-homogeneous object to be
manufactured, wherein each of a plurality of voxels making up the
virtual representation of the object (the virtual object) is
assigned one or more values representing one or more physical
properties M such as color, translucency, and hardness, for
example. In step 104, the 3D voxel representation is scan converted
to define a set of 3D dots, or parcels, which, when agglomerated
together, will produce the shape of each of a plurality of
successive Z-layers of the object to be manufactured--putting
together all of the Z-layers will produce the shape of the complete
object. Multivariate interpolation (e.g., trilinear interpolation)
may be used in the scan conversion step 104. In addition to the
shape, the 3D voxel representation also defines the one or more
prescribed physical properties M at each dot making up each Z-layer
of the object. These physical properties can vary throughout the
object (the object is non-homogeneous), and the values of a given
physical property can differ at different 3D dots. In step 106, the
shape and the material properties M at each layer Z, is defined at
the resolution of the 3D printer (dpi). In step 108, a transfer
function T(M) is defined that identifies a resin and/or a pigment
(and or combinations of the two) to produce a material having the
one or more prescribed physical properties for each 3D dot to be
printed. In step 110, a 3D printer deposits the pigment(s) and/or
resin(s) (and/or concentrations thereof) identified by the transfer
function T(M) at each dot of each of the plurality of successive
Z-layers of the object, thereby producing the non-homogeneous
object.
[0045] The methods described above may include depositing at least
two different resins with embedded crystalline particles (e.g., of
known, differing sizes or size distributions) at a given dot, the
combination of which resins produces the translucency prescribed
for the given dot. The deposition of dots may be repeated for a
plurality of dots, e.g., all the dots making up a given Z-layer,
for all the Z-layers making up the object.
[0046] Examples of voxel-based modeling systems and user interfaces
(e.g., graphical and/or haptic interfaces) that can be used with
the system described herein include those described in the
following U.S. patents and patent applications, the texts of which
are all incorporated herein by reference in their entirety: pending
U.S. patent application Ser. No. 12/692,459, titled, "Haptically
Enabled Coterminous Production of Prosthetics and Patient
Preparations in Medical and Dental Applications," by Rawley et al.,
filed Jan. 22, 2010; pending U.S. patent application Ser. No.
12/321,766, titled, "Haptically Enabled Dental Modeling System," by
Steingart et al., published as U.S. Patent Application Publication
No. 2009/0248184; pending U.S. patent application Ser. No.
11/998,457, titled, "Systems for Haptic Design of Dental
Restorations," by Steingart et al., published as U.S. Patent
Application Publication No. 2008/0261165; pending U.S. patent
application Ser. No. 11/998,877, titled, "Systems for Hybrid
Geometric/Volumetric Representation of 3D Objects," by Faken et
al., published as U.S. Patent Application Publication No.
2008/0246761; U.S. Pat. No. 7,149,596, titled, "Apparatus and
Methods for Modifying a Model of an Object to Enforce Compliance
with a Manufacturing Constraint," by Berger et al.; U.S. Pat. No.
6,958,752, titled, "Systems and Methods for Three-Dimensional
Modeling," by Jennings, Jr. et al.; U.S. Pat. No. 6,867,770,
titled, "Systems and Methods for Voxel Warping," by Payne; U.S.
Pat. No. 6,421,048, titled, "Systems and Methods for Interacting
With Virtual Objects in A Haptic Virtual Reality Environment," by
Shih et al.; and U.S. Pat. No. 6,111,577, titled, "Method and
Apparatus for Determining Forces to be Applied to a User Through a
Haptic Interface," by Zilles et al.
Equivalents
[0047] While the invention has been particularly shown and
described with reference to specific preferred embodiments, it
should be understood by those skilled in the art that various
changes in form and detail may be made therein without departing
from the spirit and scope of the invention as defined by the
appended claims.
* * * * *