U.S. patent application number 17/240654 was filed with the patent office on 2021-08-12 for techniques for mixing in additive fabrication and related systems and methods.
This patent application is currently assigned to Formlabs, Inc.. The applicant listed for this patent is Formlabs, Inc.. Invention is credited to Sarah Bennedsen, Geoff Hill, Robert Joachim, Maxim Lobovsky, Jack Moldave, Konstantinos Oikonomopoulos, Christian Reed.
Application Number | 20210245443 17/240654 |
Document ID | / |
Family ID | 1000005542485 |
Filed Date | 2021-08-12 |
United States Patent
Application |
20210245443 |
Kind Code |
A1 |
Moldave; Jack ; et
al. |
August 12, 2021 |
TECHNIQUES FOR MIXING IN ADDITIVE FABRICATION AND RELATED SYSTEMS
AND METHODS
Abstract
According to some aspects, a mixer for detection and/or removal
of material in an undesired location of an additive fabrication
device is provided. For instance, in an inverse stereolithography
device, liquid photopolymer may adhere and cure or partially cure
to a surface of the additive fabrication device in a location that
may interfere with the additive fabrication process and/or cause
the additive fabrication process to be unsuccessful. The mixer may
be coupled to a movable structure within the additive fabrication
device so that the mixer, when coupled to the movable structure,
may be moved along at least one axis within the additive
fabrication device. The mixer may be configured to detect and/or
remove undesired material from a surface within the additive
fabrication device.
Inventors: |
Moldave; Jack; (Lincoln,
MA) ; Bennedsen; Sarah; (Somerville, MA) ;
Reed; Christian; (Chelsea, MA) ; Oikonomopoulos;
Konstantinos; (Boston, MA) ; Joachim; Robert;
(Brookline, MA) ; Hill; Geoff; (Boston, MA)
; Lobovsky; Maxim; (Cambridge, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Formlabs, Inc. |
Somerville |
MA |
US |
|
|
Assignee: |
Formlabs, Inc.
Somerville
MA
|
Family ID: |
1000005542485 |
Appl. No.: |
17/240654 |
Filed: |
April 26, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16817522 |
Mar 12, 2020 |
10987873 |
|
|
17240654 |
|
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|
62818963 |
Mar 15, 2019 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01F 2215/0049 20130101;
B29C 64/393 20170801; B01F 13/0818 20130101; B01F 15/00201
20130101; B33Y 50/02 20141201; B29C 64/135 20170801; B33Y 30/00
20141201; B29C 64/314 20170801 |
International
Class: |
B29C 64/393 20060101
B29C064/393; B33Y 30/00 20060101 B33Y030/00; B33Y 50/02 20060101
B33Y050/02; B29C 64/314 20060101 B29C064/314; B29C 64/135 20060101
B29C064/135; B01F 13/08 20060101 B01F013/08; B01F 15/00 20060101
B01F015/00 |
Claims
1. An additive fabrication device configured to form layers of
solid material on a build surface by directing light onto a liquid
photopolymer, the additive fabrication device comprising: a
container configured to hold liquid photopolymer; a mixer disposed
within the container and comprising a first magnetic component; and
a movable structure disposed below the container and configured to
move along a first axis, wherein the movable structure comprises a
second magnetic coupling component configured to couple to the
first magnetic component, and wherein motion of the moveable
structure along the first axis causes motion of the mixer along the
first axis as a result of said coupling.
2. The additive fabrication device of claim 1, wherein the second
magnetic component is configured to move toward and away from the
container and thereby couple and decouple, respectively, to the
first magnetic component.
3. The additive fabrication device of claim 1, wherein the movable
structure comprises an optical unit.
4. The additive fabrication device of claim 1, wherein the mixer
further comprises an elongated body with a first end and a second
end and at least one edge member extending along the elongated body
from the first end to the second end.
5. The additive fabrication device of claim 4, wherein the at least
one edge member is configured to remove debris from a surface
proximate to the at least one edge member.
6. The additive fabrication device of claim 4, wherein the at least
one edge member is configured to spread an even layer of liquid
photopolymer.
7. The additive fabrication device of claim 1, wherein the mixer
further comprises housings configured to house the at least one
magnetic component, and wherein the housings are disposed at the
first end and the second end of the elongated body.
8. The additive fabrication device of claim 1, wherein the mixer
further comprises at least one retaining arm configured to maintain
the position of the mixer in the container when the mixer is not in
use.
9. The additive fabrication device of claim 1, wherein the mixer
further comprises a filter element.
10. The additive fabrication device of claim 9, wherein the filter
element comprises an array of holes in an upper surface of the
elongated body.
11. An additive fabrication device configured to form layers of
solid material on a build platform, the additive fabrication device
comprising: a container; a mixer disposed within the container and
comprising a first magnetic component; a movable structure disposed
below the container and configured to move along a first axis,
wherein the movable structure comprises a second magnetic component
configured to couple to the first magnetic component; a sensor
configured to produce sensor data indicative of a state of the
mixer; at least one processor; and at least one computer readable
medium comprising instructions that, when executed by the at least
one processor: operate one or more actuators to move the movable
structure and the mixer along the first axis whilst the first and
second magnetic components are coupled; and detect a failure of an
additive fabrication process based at least in part on the sensor
data produced by the sensor during movement of the mixer along the
first axis.
12. The additive fabrication device of claim 11, wherein the second
magnetic component is configured to move toward and away from the
container and thereby couple and decouple, respectively, to the
first magnetic component.
13. The additive fabrication device of claim 11, wherein the
movable structure comprises an optical unit.
14. The additive fabrication device of claim 13, wherein the sensor
is a Hall sensor configured to monitor the coupling state of the
mixer and the movable structure.
15. The additive fabrication device of claim 11, wherein the sensor
is a force sensor configured to monitor forces experienced by the
mixer whilst the mixer is coupled to the movable structure and
moved along at least one axis.
16. The additive fabrication device of claim 11, wherein the
instructions, when executed by the at least one processor, further
comprise alerting the user upon detection of a failure.
17. The additive fabrication device of claim 16, wherein the
instructions, when executed by the at least one processor, further
comprise recoupling the mixer and the movable structure upon
detection of a failure prior to alerting the user.
18. An additive fabrication device configured to form layers of
solid material on a build platform, the additive fabrication device
comprising: a build platform; a mixer disposed below the build
platform and comprising at least one magnetic component; a movable
structure disposed below the mixer and configured to move along a
first axis, wherein the movable structure comprises a second
magnetic component configured to couple to the first magnetic
component; a sensor configured to produce sensor data indicative of
a state of the mixer; at least one processor; and at least one
computer readable medium comprising instructions that, when
executed by the at least one processor: lower the build platform
iteratively whilst moving the movable structure along the first
axis underneath the build platform whilst the first and second
magnetic components are coupled until the build platform contacts
the mixer; detect a failure of an additive fabrication process
based at least in part on sensor data produced by the sensor; and
move the movable structure along the first axis while the build
platform is in contact with the mixer to remove the detected
failure.
19. The additive fabrication device of claim 18, wherein the second
magnetic component is configured to move toward and away from the
container and thereby couple and decouple, respectively, to the
first magnetic component.
20. The additive fabrication device of claim 18, wherein the
movable structure comprises an optical unit.
21. The additive fabrication device of claim 18, wherein the sensor
is a Hall sensor configured to monitor the coupling state of the
mixer and the movable structure.
22. The additive fabrication device of claim 18, wherein the sensor
is a force sensor configured to monitor forces experienced by the
mixer whilst the mixer is coupled to the movable structure and
moved along the first axis.
23. The additive fabrication device of claim 18, wherein the
instructions, when executed by the at least one processor, further
comprise alerting the user upon detection of a failure.
24. The additive fabrication device of claim 23, wherein the
instructions, when executed by the at least one processor, further
comprise recoupling the mixer and the movable structure upon
detection of a failure prior to alerting the user.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit as a continuation
under 35 U.S.C. .sctn. 120 of U.S. application Ser. No. 16/817,522,
filed Mar. 12, 2020, which claims the benefit under 35 U.S.C.
.sctn. 119(e) of U.S. Provisional Patent Application Ser. No.
62/818,963, filed Mar. 15, 2019, each of which is hereby
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Additive fabrication, e.g., 3-dimensional (3D) printing,
provides techniques for fabricating objects, typically by causing
portions of a building material to solidify at specific locations.
Additive fabrication techniques may include stereolithography,
selective or fused deposition modeling, direct composite
manufacturing, laminated object manufacturing, selective phase area
deposition, multi-phase jet solidification, ballistic particle
manufacturing, particle deposition, laser sintering or combinations
thereof.
[0003] Many additive fabrication techniques build parts by forming
successive layers, which are typically cross-sections of the
desired object. Typically each layer is formed such that it adheres
to either a previously formed layer or a substrate upon which the
object is built. In one approach to additive fabrication, known as
stereolithography, solid objects are created by successively
forming thin layers of a curable polymer resin, typically first
onto a substrate and then one on top of another. Exposure to
actinic radiation such as light cures a thin layer of liquid resin,
which causes it to harden and adhere to previously cured layers and
the bottom surface of the substrate.
SUMMARY
[0004] According to some aspects, an additive fabrication device
configured to form layers of solid material on a build platform is
provided. The additive fabrication device comprises: a container; a
mixer disposed within the container and configured to move along at
least a first axis; a sensor configured to produce sensor data
indicative of a state of the mixer; at least one processor; and at
least one computer readable medium comprising instructions. The
instructions, when executed by the at least one processor, operate
one or more actuators to move the mixer along the first axis; and
detect a failure of an additive fabrication process based at least
in part on the sensor data produced by the sensor during movement
of the mixer along the first axis.
[0005] According to some aspects, an additive fabrication device
configured to form layers of solid material on a build platform is
provided. The additive fabrication device comprises: a build
platform; a mixer disposed below the build platform and configured
to move along a first axis; at least one sensor configured to
produce sensor data indicative of a state of the mixer; at least
one processor; and at least one computer readable medium comprising
instructions. The instructions, when executed by the at least one
processor, lower the build platform iteratively whilst operating
one or more actuators to move the mixer along the first axis
underneath the build platform until the build platform contacts the
mixer; and detect a failure of an additive fabrication process
based at least in part on the sensor data produced by the sensor
during movement of the mixer along the first axis.
[0006] According to some aspects, an additive fabrication device
configured to form layers of solid material on a build surface by
directing light onto a liquid photopolymer is provided. The
additive fabrication device comprises: a container configured to
hold liquid photopolymer; a mixer disposed within the container and
comprising a first magnetic component; and a movable structure
disposed below the container and configured to move along at least
one axis, wherein the movable structure comprises a second magnetic
coupling component configured to couple to the first magnetic
component, and wherein motion of the moveable structure along the
at least one axis causes motion of the mixer along the at least one
axis as a result of said coupling.
[0007] According to some aspects, an additive fabrication device
configured to form layers of solid material on a build platform is
provided. The additive fabrication device comprises: a container; a
mixer disposed within the container and comprising a first magnetic
component; a movable structure disposed below the container and
configured to move along a first axis, wherein the movable
structure comprises a second magnetic component configured to
couple to the first magnetic component; a sensor configured to
produce sensor data indicative of a state of the mixer; at least
one processor; and at least one computer readable medium comprising
instructions. The instructions, when executed by the at least one
processor, operate one or more actuators to move the movable
structure and the mixer along the first axis whilst the first and
second magnetic components are coupled; and detect a failure of an
additive fabrication process based at least in part on the sensor
data produced by the sensor during movement of the mixer along the
first axis.
[0008] According to some aspects, an additive fabrication device
configured to form layers of solid material on a build platform is
provided. The additive fabrication device comprises: a build
platform; a mixer disposed below the build platform and comprising
at least one magnetic component; a movable structure disposed below
the mixer and configured to move along a first axis, wherein the
movable structure comprises a second magnetic component configured
to couple to the first magnetic component; a sensor configured to
produce sensor data indicative of a state of the mixer; at least
one processor; and at least one computer readable medium comprising
instructions. The instructions, when executed by the at least one
processor: lower the build platform iteratively whilst moving the
movable structure along the first axis underneath the build
platform whilst the first and second magnetic components are
coupled until the build platform contacts the mixer; detect a
failure of an additive fabrication process based at least in part
on sensor data produced by the sensor; and move the movable
structure along the first axis while the build platform is in
contact with the mixer to remove the detected failure.
[0009] The foregoing apparatus and method embodiments may be
implemented with any suitable combination of aspects, features, and
acts described above or in further detail below. These and other
aspects, embodiments, and features of the present teachings can be
more fully understood from the following description in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0010] Various aspects and embodiments will be described with
reference to the following figures. It should be appreciated that
the figures are not necessarily drawn to scale. In the drawings,
each identical or nearly identical component that is illustrated in
various figures is represented by a like numeral. For purposes of
clarity, not every component may be labeled in every drawing.
[0011] FIGS. 1A-1B illustrate a schematic view of a
stereolithographic additive fabrication device that forms a
plurality of layers of a part, according to some embodiments;
[0012] FIG. 2 illustrates a schematic view of an additive
fabrication device having a mixer and movable structure, according
to some embodiments;
[0013] FIG. 3 illustrates a schematic view of an additive
fabrication device having a mixer and movable structure comprising
an optical module, according to some embodiments;
[0014] FIG. 4A illustrates a plan view of a mixer for an additive
fabrication device, according to some embodiments;
[0015] FIG. 4B illustrates an elevation view of a mixer for an
additive fabrication device, according to some embodiments;
[0016] FIG. 4C illustrates a perspective view of a mixer for an
additive fabrication device, according to some embodiments;
[0017] FIG. 4D illustrates a perspective view of a mixer and
magnetic components for an additive fabrication device, according
to some embodiments;
[0018] FIG. 5 is a flowchart of a process suitable for detecting
and/or removing debris on a build platform of an additive
fabrication device, according to some embodiments;
[0019] FIG. 6 is a flowchart of a process suitable for detecting
and/or removing debris in a container of an additive fabrication
device, according to some embodiments;
[0020] FIG. 7 illustrates an example of a computing system
environment on which aspects of the invention may be implemented;
and
[0021] FIG. 8 is a block diagram of a system suitable for
practicing aspects of the invention, according to some
embodiments.
DETAILED DESCRIPTION
[0022] As discussed above, some additive fabrication techniques may
form solid objects by forming successive thin layers on a build
platform. In stereolithography, such layers are formed from a
liquid photopolymer, such as a photopolymer resin. Actinic
radiation (radiation that initiates and/or develops the curing
process) such as light may be directed to a selected portion of the
photopolymer resin, thereby curing it to a solid (or semi-solid)
layer in a desired shape.
[0023] Some stereolithographic devices may form solid material in
contact with a surface additional to previous layers of the part or
the build platform, such as a container in which liquid
photopolymer is held. Actinic radiation may be introduced through
the bottom of a liquid photopolymer container or to a top surface
of the liquid photopolymer. The first type of stereolithographic
device is sometimes referred to as an "inverted stereolithography"
or "constrained surface stereolithography" device, but the
techniques discussed herein may also be applied to the second type
of stereolithographic device.
[0024] In some instances of operating an inverted stereolithography
device, the cured photopolymer or portions of the cured
photopolymer may remain adhered to the container surface or build
platform during or after an additive fabrication process. This
adhered, cured photopolymer may interfere with the current or a
subsequent additive fabrication process by blocking or scattering
light or preventing the formation of a flat layer of solid
material, potentially distorting or destroying the part or damaging
the additive fabrication device. In a non-inverted
stereolithography device, such debris may remain floating on top of
the liquid photopolymer rather than remaining adhered to a surface.
Automatically detecting and addressing such debris in the
container, on the build platform, or in the liquid photopolymer may
improve both the quality of the fabricated parts and the user
experience.
[0025] The inventors have recognized and appreciated techniques for
magnetically coupling a mixer to an additive fabrication device
wherein the mixer is configured to remove cured photopolymer or
other debris from the surface of the container and/or the build
platform. In some cases, the mixer may be used to detect various
calibration or print failures in an additive fabrication device.
Taken individually or in any suitable combination, these
improvements mitigate at least one of the above-described
challenges, as will be described in further detail below.
[0026] Conventional additive fabrication devices may have a mixer
affixed to one or more actuators configured to move the mixer. For
instance, the mixer may be mechanically attached to an actuator
that moves the mixer within a container such that when the actuator
moves, the mixer also moves as a result of its coupling to the
actuator. The inventors have recognized and appreciated that it may
be desirable to couple a mixer to a movable structure such that the
mixer may be easily engaged and disengaged from the movable
structure. For example, in some modes of additive fabrication, it
may be desirable to move the movable structure without also moving
the mixer. Accordingly, the inventors have developed systems for
removably coupling a mixer to a movable structure within an
additive fabrication device. In some embodiments, such removable
coupling between the mixer and the movable structure may be
accomplished by any suitable mechanical coupling means (e.g., any
suitable locking mechanisms, latches, ball and socket joints, touch
and/or push latches, and/or actuated latches).
[0027] The inventors have further recognized and appreciated,
however, that using magnetic coupling to removably couple the mixer
and movable structure may reduce the mechanical complexity of the
additive fabrication device or may contain any components in
contact with the liquid photopolymer within the container, thereby
limiting user interaction with components contacting liquid
photopolymer. In some cases, the movable structure may be
configured to engage and disengage the magnetic coupling to the
mixer, such as by moving one or more magnets toward or away from
the mixer, by activating or deactivating an electromagnet, etc.
This configuration enables the mixer to be moved with the movable
stage only when desired. In some configurations the mixer may
always be engaged.
[0028] In some embodiments, the movable structure may comprise an
optical unit which houses optical components configured to cure
liquid photopolymer during an additive fabrication process. By
removably coupling the mixer to a movable structure such as an
optical unit, fewer actuators may be required within the additive
fabrication device, decreasing opportunities for mechanical failure
during use.
[0029] In some embodiments, coupling between the mixer and the
movable structure may be achieved through magnetic components
housed in the mixer and the movable structure. It may be further
appreciated that magnetic coupling may decrease the complexity of
installation and maintenance of the mixer within the additive
fabrication device, as the container may be easily removed and
installed, limiting user contact with the liquid photopolymer. This
may improve the overall user experience as well as reduce the
chance of a user damaging the additive fabrication device when
installing or removing the container.
[0030] Another problem that may arise in stereolithographic
additive fabrication devices is that cured photopolymer or other
debris may contaminate the liquid photopolymer or otherwise be
situated in a such a way that subsequent fabrication will be
impaired. Debris may interfere with an additive fabrication process
by, for example, blocking or scattering light within the
photopolymer resin, or by adhering to the build platform or part
being formed and preventing uniform layers from being formed,
distorting the part. In extreme cases, material attached to a build
platform, such as debris or previously formed parts, may cause
damage to a container if not detected and removed prior to forming
a new layer or part. In some embodiments, a mixer may include a
filter configured to catch and remove unwanted debris from the
liquid photopolymer. The liquid photopolymer may flow over the top
surface of the mixer and then down through the filter as the mixer
is moved through the liquid photopolymer, thereby removing debris
from the liquid photopolymer.
[0031] Following below are more detailed descriptions of various
concepts related to, and embodiments of, techniques for
magnetically coupling a mixer to an additive fabrication device. It
should be appreciated that various aspects described herein may be
implemented in any of numerous ways. Examples of specific
implementations are provided herein for illustrative purposes only.
In addition, the various aspects described in the embodiments below
may be used alone or in any combination, and are not limited to the
combinations explicitly described herein.
[0032] Although particular systems and methods have been described
and shown herein, it is envisioned that the functionality of the
various methods, systems, apparatus, objects, and computer readable
media disclosed herein may be applied to any now known or hereafter
devised additive fabrication technique wherein it is desired to
detect and remove failures of an additive fabrication process.
[0033] To illustrate one exemplary additive fabrication technique,
an inverse stereolithographic printer is depicted in FIGS. 1A-B.
Exemplary stereolithographic printer 100 forms a part in a downward
facing direction on a build platform such that layers of the part
are formed in contact with a surface of a container in addition to
a previously cured layer or the build platform. In the example of
FIGS. 1A-B, stereolithographic printer 100 comprises build platform
104, container 106, and liquid photopolymer 110. A downward facing
build surface 104 opposes the bottom surface of container 106,
which is filled with a liquid photopolymer 110. The bottom surface
of container 106 may be formed of any suitable material including a
hard, inflexible material or a flexible film. The structures and
methods described herein may be realized in any type of container.
FIG. 1A represents a configuration of stereolithographic printer
100 prior to formation of any layers of a part on build surface
104.
[0034] As shown in FIG. 1B, a part 112 may be formed layerwise,
with the initial layer attached to the build platform 104. The
container's floor may be transparent to actinic radiation such as
light, which can be targeted at portions of the thin layer of
liquid photocurable resin resting on the floor of the container.
Exposure to actinic radiation such as light cures a thin layer of
the liquid resin, which causes it to harden. The layer 114 is at
least partially in contact with both a previously formed layer and
the surface of the container 106 when it is formed. The top side of
the cured resin layer typically bonds to either the bottom surface
of the build surface 104 or with the previously cured resin layer
in addition to the transparent floor of the container. In order to
form additional layers of the part subsequent to the formation of
layer 114, any bonding that occurs between the transparent floor of
the container and the layer must be broken. For example, one or
more portions of the surface (or the entire surface) of layer 114
may adhere to the container such that the adhesion must be removed
prior to formation of a subsequent layer.
[0035] An exemplary additive fabrication device comprising a mixer
and a movable structure is shown in FIG. 2. According to some
embodiments, additive fabrication device 200 may comprise a
container 106 which is configured to hold liquid photopolymer 110.
Mixer 202 is disposed within container 106, and comprises a
magnetic component 204 for coupling to a magnetic component 208 of
a movable structure 206 which may be disposed below container 106.
In some embodiments, movable structure 206 may be disposed next to
container 106 or above container 106.
[0036] In the example of FIG. 2, one or more magnetic components
208 may be raised and lowered along axis 210 in order to couple and
decouple, respectively, with one or more magnetic components
magnetic component 204 of the mixer 202. In some embodiments, the
magnetic component(s) 208 may be mechanically coupled to one or
more arms arranged within the movable structure 206 that are
configured to raise and lower the magnetic component(s) along axis
210. The movable structure 206 may be configured to move along axis
212, and when magnetically coupled to the mixer 202, may also move
the mixer 202 along axis 212. When the mixer 202 is not
magnetically coupled to the movable stage 206, motion of the
movable stage 206 along axis 212 may not cause motion of the mixer.
In some embodiments, movable structure 206 is configured to move
along axis 212 through mechanical coupling to one or more
actuators.
[0037] Additive fabrication device 200 may further comprise an
optional sensor 216 configured to monitor mixer 202 through link
214. Link 214 may comprise any suitable wired and/or wireless
communications connection. According to some embodiments, sensor
216 may be at least one Hall Effect sensor configured to detect
when the magnetic component 208 is raised or lowered and whether
the mixer 202 is coupled to the movable structure 206. Sensor 216
may further be able to detect minor displacement of mixer 202 away
from movable structure 206 in addition to detecting an unexpected
decoupling of mixer 202 and movable structure 206. Such detection
may allow the user to determine when the container or build
platform may need additional passes of the mixer or additional user
intervention steps to remove debris such as cured liquid
photopolymer 110. In some embodiments, such as where additive
fabrication device 200 does not comprise a sensor 216, the user may
be prompted to confirm that mixer 202 is in position prior to an
additive fabrication process.
[0038] "Decoupling," as used herein, refers to unexpected
disengagement between mixer 202 and movable structure 206 due to an
outside force. The outside force may be caused by the mixer
encountering cured photopolymer or other debris adhered to the
build platform 104 or the bottom of the container 106. If the cured
photopolymer or other debris is adhered strongly to the build
platform 104 or the bottom of the container 106, the mixer 202 may
not be able to overcome the adhesion to remove the cured
photopolymer or other debris. Additionally, the outside force
causing decoupling may be due to the liquid photopolymer 110.
Liquid photopolymer 110 may be a viscous liquid which may resist
the movement of the mixer 202. Decoupling may occur due to the
liquid photopolymer 110 if the magnetic coupling between magnetic
components 204 and 208 is not strong enough to overcome the force
of the liquid photopolymer 110 or if the mixer 202 is moved too
quickly through the liquid photopolymer 110.
[0039] The magnetic coupling force may be any suitable strength
which prevents decoupling while the mixer 202 is moved through the
liquid photopolymer 110 and allows the mixer 202 to move at a
reasonable speed. In some embodiments, the magnetic coupling force
may enable the removal of debris. The magnetic coupling force may
enable the removal of small debris in a single pass of the mixer
202 or the removal of medium debris in multiple passes of the mixer
202. In other embodiments, the magnetic coupling force may not
enable the removal of debris, but rather allows the mixer 202 to
decouple from the movable structure 206 upon encountering debris of
any size so that the additive fabrication device may alert the user
of a failure.
[0040] The desirable coupling force may depend on a variety of
factors including, but not limited to, the viscosity of liquid
photopolymer 110, the speed at which the mixer 202 is intended to
move, and/or the expected strength of adherence for some typical or
"model" debris. These factors may differ between different
materials and/or additive fabrication devices. In some embodiments,
the magnetic coupling force between magnetic components 204 and 208
may be higher than 5 N. In some embodiments where the viscosity of
the liquid photopolymer 110 or the speed at which the mixer 202 is
intended to move are lower, the magnetic coupling force may ideally
be between 5 and 15 N and the speed of the mixer 202 may be between
30 and 100 mm/s. Where the viscosity of the liquid photopolymer 110
and/or the speed at which the mixer 202 is intended to move is
higher, the magnetic coupling force may ideally be between 10 and
25 N and the speed of the mixer 202 may be between 80 and 180 mm/s.
A magnetic coupling force higher than 25 N may also be implemented
depending on factors such as, but not limited to, the viscosity of
liquid photopolymer 110, the speed at which the mixer 202 is
intended to move, and/or the expected strength of adherence for
some typical or "model" debris.
[0041] According to some embodiments, sensor 216 may be, or may
comprise, a force sensor configured to monitor forces applied to
mixer 202 whilst being moved by movable structure 206. Sensor 216
may be configured to detect decoupling of mixer 202 from movable
structure 206 as well as smaller fluctuations in coupling that
mixer 202 encounters as it is moved by movable structure 206.
Sensor 216 may additionally or alternatively be configured to
trigger a stop of the mixing process if a force is sensed above a
threshold force to prevent damage to the additive fabrication
device 200.
[0042] According to some embodiments, movement of the mixer 202
along axis 212 may serve to remove debris, described herein as
fabrication failures, from the lower surface of the container 106
or the surface of the build platform 104. Fabrication failures can
occur in numerous ways during the fabrication process, or even
prior to the fabrication process, if unexpected behavior occurs.
Such behavior often includes the presence of material in an
undesired location, which can cause the fabrication process to
proceed in a manner other than the intended manner. For instance,
the presence of solid material, such as a previously formed part,
on the build platform 104 prior to fabrication may cause a failure
because the additive fabrication device is configured to form
material on the build platform under the assumption that the build
platform is a flat surface at a specific location in the additive
fabrication device. In some embodiments wherein the bottom surface
of the container 106 is formed of a flexible film, adhered debris
or a previously formed part on the build platform 104 may cause the
build platform 104 to puncture the film as the build platform 104
is lowered to be proximate to the film.
[0043] As another example, cured or partially-cured photopolymer
may adhere to a part being fabricated or some other surface during
fabrication and thereby cause additional material to be cured in an
undesired location. Collectively, such issues may be termed
"failures" herein, although it will be appreciated that the
production of unexpected behavior may not immediately cause the
additive fabrication device itself to fail and in some cases, may
not even cause the device to fail at all. In some cases, for
example, a "failure" may reduce the quality of the fabricated part
but may otherwise not impede the fabrication process.
[0044] Movement of the mixer 202 along axis 212 may also serve to
mix the liquid photopolymer 110. "Mixing" of the liquid
photopolymer 110, as used herein, refers to the redistribution of
liquid photopolymer 110 within the container 106. Rather, mixing,
as used herein, indicates the homogenization of the liquid
photopolymer. For example, some liquid photopolymers may contain
components that may settle or compact over time. Such components
may include composite or particulate filler components such as
ceramic, glass, or wax. Some liquid photopolymers may have dyes or
pigments that may settle leading to inconsistent coloring or poor
resin quality. Mixing may redistribute the liquid photopolymer in
such a way as to homogenize the viscosity and/or composition of the
liquid photopolymer. Mixing prior to an additive fabrication
process may improve the consistency of the additive fabrication
process, as the liquid photopolymer will respond to light in a
similar manner throughout its volume if its properties are
homogenous.
[0045] In some embodiments the mixer 202 may be configured to
include a process of recoating in which the liquid photopolymer is
moved to hasten the natural motion that occurs as the liquid flows
and ensure an even layer of liquid photopolymer is prepared for the
printing process. Since the liquid may be viscous, recoating may
provide improvements in the form of a quicker print process and/or
a more uniform printing layer.
[0046] FIG. 3 depicts an exemplary embodiment of an additive
fabrication device 300 wherein the movable structure comprises an
optical unit 302. Optical unit 302 may be used to direct actinic
radiation such as light onto the liquid photopolymer 110 in order
to perform a stereolithographic additive fabrication process as
described previously. Optical unit 302 may be further configured to
move along two or more axes, as described in U.S. application Ser.
No. 16/163,403, which is incorporated herein by reference in
full.
[0047] Optical unit 302 may serve two purposes within additive
fabrication device 300, being configured to both move the mixer 202
prior to or during a fabrication process to address failures in the
container 106 or on the build platform 104 as well as to decouple
from the mixer and direct light onto the liquid photopolymer 110 to
form a part 112 during an additive fabrication process. According
to some embodiments, the multifunctionality of optical unit 302 may
reduce the number of actuators needed within additive fabrication
device 300, simplifying the device and reducing opportunities for
mechanical failure.
[0048] Optical unit 302 may comprise such optical components as an
optical window 304, which allows light or other radiation to exit
the optical unit 302, a light source 306, and an optical component
308 configured to steer light from light source 306. Optical
component 308 may be a mirror galvanometer. Optical unit 302 may
further comprise additional optical components to assist in
steering or focusing light from light source 306. These additional
optical components may include, but are not limited to, mirrors,
lenses, filters, galvanometers, or any combination thereof. In some
embodiments, optical unit 302 may further comprise magnetic
component 208 which may be raised and lowered along axis 210 in
order to couple to and decouple from magnetic component 204 of
mixer 202. Optical unit 302 may also move along axis 212. When
optical unit 302 is coupled to mixer 202, optical unit 302 may move
along axis 212, thereby moving mixer 202 along axis 212.
[0049] FIGS. 4A-4D illustrate various views of an illustrative
mixer, according to some embodiments. Mixer 400 may be an
illustrative implementation of, for example, mixer 202 shown in
FIGS. 2 and 3. Mixer 400 may be formed of any suitable material
configured to be chemically inert when in contact with the liquid
photopolymer 110, including, but not limited to, metals, glass, or
plastics such as PVDF, PEEK, or PVC. In the example of FIGS. 4A-4D,
mixer 400 may comprise an edge 402 configured to extend along the
width of mixer 400. Edge 402 may be further configured in any
suitable way to scrape failures such as adhered, cured liquid
photopolymer off of the bottom surface of a container, such as
container 106. For example, edge 402 may be wedge-shaped (e.g.,
changing in thickness over its profile from a thin leading edge to
a thick body portion) such that edge 402 may fit between the bottom
surface of the container 106 and an adhered failure and separate
the adhered failure from the bottom surface. In some embodiments,
edge 402 may be formed of a flexible material including, but not
limited to, flexible plastics, urethane, or rubbers.
[0050] Mixer 400 may further comprise an edge 404 extending along
the width of mixer 400 which may be configured to recoat the bottom
surface of container 106 with an even layer of liquid photopolymer
110. Edge 404 may be configured to extend proximate to, but not in
contact with, the bottom surface of a container. Edge 404 may be
disposed above the bottom surface of container 106 by a distance
equal to or greater than the layer thickness to be formed during an
additive fabrication process. Edge 404 may be disposed above the
bottom surface of container 106 by a distance between or greater
than 10 to 300 microns. Edge 404 may additionally be angled to
improve wicking of liquid photopolymer 110 from outside edges of
container 106 to the center of container 106. In the example of
FIGS. 4A-4D, a filter 410 is disposed on the upper surface of the
mixer 400. Filter 410 may be configured to catch cured photopolymer
or other debris which are loose in the liquid photopolymer 110.
[0051] Magnet compartments 406 may be arranged in any suitable
manner to enable coupling to the movable structure 206 or optical
unit 302. In the exemplary embodiment of FIG. 4A, a magnet
compartment 406 is disposed at both ends of the mixer 400.
Extending off of the magnet compartments 406 are parking features
408. These parking features 408 may enable mixer 400 to be "parked"
when not in use. That is, during an additive fabrication process,
the movable structure 206 may couple to mixer 400 and move it to a
pre-determined location wherein parking features 408 may engage
with the additive fabrication device in such a way to keep mixer
400 stationary. The movable structure 206 may then decouple from
mixer 400 and begin or continue an additive fabrication process
while mixer 400 remains stationary and does not interfere with the
additive fabrication process.
[0052] FIG. 4B illustrates an elevation view of mixer 400,
according to some embodiments. Mixer 400 may further comprise edge
412, which is disposed along the upper surface of mixer 400 and
extends along the width of mixer 400. Edge 412 may be configured in
any suitable way to scrape failures such as adhered, cured liquid
photopolymer off of the surface of build platform 104. For example,
edge 412 may be wedge-shaped (e.g., changing in thickness over its
profile from a thin leading edge to a thick body portion) such that
edge 412 may fit between the build platform 104 and an adhered
failure and separate the adhered failure from the build platform
104.
[0053] FIGS. 4C and 4D illustrate perspective views of mixer 400
from above and below mixer 400, according to some embodiments.
Differences in the configurations of edges 402 and 404 may be seen
in FIG. 4C, with edge 402 configured to scrape and remove failures
from the bottom of container 106 while edge 404 is configured to
distribute an even layer of liquid photopolymer as the mixer 400 is
moved through the container 106. In some embodiments, mixer 400 may
comprise only one of any of a selection of edges 402, 404, and/or
412. Mixer 400 may comprise any combination of edges 402, 404,
and/or 412.
[0054] FIG. 4D illustrates a perspective view of mixer 400 from
above and an exemplary configuration of magnets 416 which may be
contained in magnet compartments 406, according to some
embodiments. In the example of FIG. 4D, three magnets 416 are
housed in each magnet compartment 406, but any suitable number of
magnets may be used. In some embodiments, the force required for
decoupling the magnetic components 204 and 208 may determine how
much force the mixer may be able to apply to failures within the
container 106 or on the build platform 104.
[0055] In some instances, it may be desirable to use multiple
magnets arranged with alternating poles as shown in FIG. 4D in
order to reduce the chance of decoupling between mixer 400 and
movable structure 206 or to increase the force required to decouple
magnetic components 204 and 208. Such an arrangement harnesses
magnetic repulsion between same magnetic poles. As magnetic
components 204 and 208 begin to slide past each other in a
decoupling event, same magnetic poles (i.e. N-N and S-S pairs) in
the magnetic components 204 and 208 become closer together,
increasing the repulsion between them. This repulsion may help
shift magnetic components 204 and 208 back to a fully coupled
state.
[0056] FIG. 5 is a flowchart of an exemplary process 500 for
detecting and addressing failures on the build platform 104 of an
additive fabrication device, according to some embodiments. Process
500 may also act to mix and/or filter the liquid photopolymer, that
is, to homogenize the liquid photopolymer prior to an additive
fabrication process. In act 502, the build platform 104 is lowered
a step toward the mixer 202. In act 504, the movable structure 206,
whilst being coupled to mixer 202, is actuated along at least one
axis 212 in order to move the mixer 202 along the at least one axis
212 through container 106. If sensor 216 detects a decoupling of
the mixer 202 from movable structure 206 in act 505, the additive
fabrication device may alert the user to a failure on the build
platform in act 506.
[0057] In some embodiments, rather than detecting a decoupling of
mixer 202 from movable structure 206, sensor 216 may be configured
to detect a force on the mixer. Sensor 216 may be further
configured to monitor the path of the mixer 202 to then alert the
user to fluctuations in forces experienced by the mixer 202 or in
the movement of mixer 202. Such fluctuations could indicate
anomalies in the liquid photopolymer 110 or failures which the
mixer 202 cannot remove but do interfere with the motion of mixer
202.
[0058] If sensor 216 does not detect a decoupling of the mixer 202
from movable structure 206 in act 505, and the build platform has
not reached a vertical position equal to the height of the mixer
202 as may be detected in act 507, the system returns to act 502
and moves the build platform 104 further. If, instead, the build
platform had reached a vertical position equal to the height of the
mixer 202, then the additive fabrication process may be continued
in act 508, as no failures have been detected on the build platform
104.
[0059] FIG. 6 is a flowchart of an exemplary process 600 for
detecting and addressing failures in the container 106 of an
additive fabrication device, according to some embodiments. Process
600 may be run prior to an additive fabrication process,
intermittently during an additive fabrication process, or after the
formation of each layer of an object. In act 602, whilst the mixer
202 is coupled to the movable structure 206, the movable structure
may be actuated along at least one axis to move the mixer along the
at least one axis. If sensor 216 does not detect a decoupling of
the mixer 202 from the movable structure 206 in act 603, then the
additive fabrication device may proceed with next steps of the
additive fabrication process in act 608, as no failures in the
container have been detected.
[0060] If sensor 216 detects a decoupling of the mixer 202 from
movable structure 206 in act 603, the additive fabrication device
may attempt to recouple the mixer 202 and the movable structure 206
in act 604. In some embodiments, rather than detecting a decoupling
of mixer 202 from movable structure 206, sensor 216 may be
configured to detect a force on the mixer above a threshold force.
If the mixer 202 and the movable structure 206 are successfully
recoupled in act 605, the additive fabrication device may return to
act 602. If the mixer 202 and the movable structure 206 do not
successfully recouple, the additive fabrication device may alert
the user to a failure in the container in act 606.
[0061] FIG. 7 is a block diagram of a system suitable for
practicing aspects of the invention, according to some embodiments.
System 700 illustrates a system suitable for generating
instructions to perform additive fabrication by an additive
fabrication device and subsequent operation of the additive
fabrication device to fabricate an object. For instance,
instructions to identify contamination on an optical window of an
additive fabrication device or detect a failure mode of an additive
fabrication process as described by the various techniques above
may be generated by the system and provided to the additive
fabrication device. Various parameters associated with identifying
contamination on an optical window of an additive fabrication
device or detecting a failure mode of an additive fabrication
process may be stored by system computer system 710 and accessed
when generating instructions for the additive fabrication device
720 to identify contamination or detect a failure mode.
[0062] According to some embodiments, computer system 710 may
execute software that generates instructions for identifying
contamination within an additive fabrication device. Said
instructions may then be provided to an additive fabrication
device, such as additive fabrication device 720, that, when
executed by the device, performs a two-dimensional, optical scan of
a calibration plate. Such instructions may be communicated via link
715, which may comprise any suitable wired and/or wireless
communications connection. In some embodiments, a single housing
holds the computing device 710 and additive fabrication device 720
such that the link 715 is an internal link connecting two modules
within the housing of system 700.
[0063] FIG. 8 illustrates an example of a suitable computing system
environment 800 on which the technology described herein may be
implemented. For example, computing environment 800 may form some
or all of the computer system 710 shown in FIG. 7. The computing
system environment 800 is only one example of a suitable computing
environment and is not intended to suggest any limitation as to the
scope of use or functionality of the technology described herein.
Neither should the computing environment 800 be interpreted as
having any dependency or requirement relating to any one or
combination of components illustrated in the exemplary operating
environment 800.
[0064] The technology described herein is operational with numerous
other general purpose or special purpose computing system
environments or configurations. Examples of well-known computing
systems, environments, and/or configurations that may be suitable
for use with the technology described herein include, but are not
limited to, personal computers, server computers, hand-held or
laptop devices, multiprocessor systems, microprocessor-based
systems, set top boxes, programmable consumer electronics, network
PCs, minicomputers, mainframe computers, distributed computing
environments that include any of the above systems or devices, and
the like.
[0065] The computing environment may execute computer-executable
instructions, such as program modules. Generally, program modules
include routines, programs, objects, components, data structures,
etc. that perform particular tasks or implement particular abstract
data types. The technology described herein may also be practiced
in distributed computing environments where tasks are performed by
remote processing devices that are linked through a communications
network. In a distributed computing environment, program modules
may be located in both local and remote computer storage media
including memory storage devices.
[0066] With reference to FIG. 8, an exemplary system for
implementing the technology described herein includes a general
purpose computing device in the form of a computer 810. Components
of computer 810 may include, but are not limited to, a processing
unit 820, a system memory 830, and a system bus 821 that couples
various system components including the system memory to the
processing unit 820. The system bus 821 may be any of several types
of bus structures including a memory bus or memory controller, a
peripheral bus, and a local bus using any of a variety of bus
architectures. By way of example, and not limitation, such
architectures include Industry Standard Architecture (ISA) bus,
Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus,
Video Electronics Standards Association (VESA) local bus, and
Peripheral Component Interconnect (PCI) bus also known as Mezzanine
bus.
[0067] Computer 810 typically includes a variety of computer
readable media. Computer readable media can be any available media
that can be accessed by computer 810 and includes both volatile and
nonvolatile media, removable and non-removable media. By way of
example, and not limitation, computer readable media may comprise
computer storage media and communication media. Computer storage
media includes volatile and nonvolatile, removable and
non-removable media implemented in any method or technology for
storage of information such as computer readable instructions, data
structures, program modules or other data. Computer storage media
includes, but is not limited to, RAM, ROM, EEPROM, flash memory or
other memory technology, CD-ROM, digital versatile disks (DVD) or
other optical disk storage, magnetic cassettes, magnetic tape,
magnetic disk storage or other magnetic storage devices, or any
other medium which can be used to store the desired information and
which can accessed by computer 810. Communication media typically
embodies computer readable instructions, data structures, program
modules or other data in a modulated data signal such as a carrier
wave or other transport mechanism and includes any information
delivery media. The term "modulated data signal" means a signal
that has one or more of its characteristics set or changed in such
a manner as to encode information in the signal. By way of example,
and not limitation, communication media includes wired media such
as a wired network or direct-wired connection, and wireless media
such as acoustic, RF, infrared and other wireless media.
Combinations of the any of the above should also be included within
the scope of computer readable media.
[0068] The system memory 830 includes computer storage media in the
form of volatile and/or nonvolatile memory such as read only memory
(ROM) 831 and random access memory (RAM) 832. A basic input/output
system 833 (BIOS), containing the basic routines that help to
transfer information between elements within computer 810, such as
during start-up, is typically stored in ROM 831. RAM 832 typically
contains data and/or program modules that are immediately
accessible to and/or presently being operated on by processing unit
820. By way of example, and not limitation, FIG. 8 illustrates
operating system 834, application programs 835, other program
modules 836, and program data 837.
[0069] The computer 810 may also include other
removable/non-removable, volatile/nonvolatile computer storage
media. By way of example only, FIG. 8 illustrates a hard disk drive
841 that reads from or writes to non-removable, nonvolatile
magnetic media, a flash drive 851 that reads from or writes to a
removable, nonvolatile memory 852 such as flash memory, and an
optical disk drive 855 that reads from or writes to a removable,
nonvolatile optical disk 856 such as a CD ROM or other optical
media. Other removable/non-removable, volatile/nonvolatile computer
storage media that can be used in the exemplary operating
environment include, but are not limited to, magnetic tape
cassettes, flash memory cards, digital versatile disks, digital
video tape, solid state RAM, solid state ROM, and the like. The
hard disk drive 841 is typically connected to the system bus 821
through a non-removable memory interface such as interface 840, and
magnetic disk drive 851 and optical disk drive 855 are typically
connected to the system bus 821 by a removable memory interface,
such as interface 850.
[0070] The drives and their associated computer storage media
discussed above and illustrated in FIG. 8, provide storage of
computer readable instructions, data structures, program modules
and other data for the computer 810. In FIG. 8, for example, hard
disk drive 841 is illustrated as storing operating system 844,
application programs 845, other program modules 846, and program
data 847. Note that these components can either be the same as or
different from operating system 834, application programs 835,
other program modules 836, and program data 837. Operating system
844, application programs 845, other program modules 846, and
program data 847 are given different numbers here to illustrate
that, at a minimum, they are different copies. A user may enter
commands and information into the computer 810 through input
devices such as a keyboard 862 and pointing device 861, commonly
referred to as a mouse, trackball or touch pad. Other input devices
(not shown) may include a microphone, joystick, game pad, satellite
dish, scanner, or the like. These and other input devices are often
connected to the processing unit 820 through a user input interface
860 that is coupled to the system bus, but may be connected by
other interface and bus structures, such as a parallel port, game
port or a universal serial bus (USB). A monitor 891 or other type
of display device is also connected to the system bus 921 via an
interface, such as a video interface 890. In addition to the
monitor, computers may also include other peripheral output devices
such as speakers 897 and printer 896, which may be connected
through an output peripheral interface 895.
[0071] The computer 810 may operate in a networked environment
using logical connections to one or more remote computers, such as
a remote computer 880. The remote computer 880 may be a personal
computer, a server, a router, a network PC, a peer device or other
common network node, and typically includes many or all of the
elements described above relative to the computer 810, although
only a memory storage device 881 has been illustrated in FIG. 8.
The logical connections depicted in FIG. 8 include a local area
network (LAN) 871 and a wide area network (WAN) 873, but may also
include other networks. Such networking environments are
commonplace in offices, enterprise-wide computer networks,
intranets and the Internet.
[0072] When used in a LAN networking environment, the computer 810
is connected to the LAN 871 through a network interface or adapter
870. When used in a WAN networking environment, the computer 810
typically includes a modem 872 or other means for establishing
communications over the WAN 873, such as the Internet. The modem
872, which may be internal or external, may be connected to the
system bus 821 via the user input interface 860, or other
appropriate mechanism. In a networked environment, program modules
depicted relative to the computer 810, or portions thereof, may be
stored in the remote memory storage device. By way of example, and
not limitation, FIG. 8 illustrates remote application programs 885
as residing on memory device 881. It will be appreciated that the
network connections shown are exemplary and other means of
establishing a communications link between the computers may be
used.
[0073] The above-described embodiments of the technology described
herein can be implemented in any of numerous ways. For example, the
embodiments may be implemented using hardware, software or a
combination thereof. When implemented in software, the software
code can be executed on any suitable processor or collection of
processors, whether provided in a single computer or distributed
among multiple computers. Such processors may be implemented as
integrated circuits, with one or more processors in an integrated
circuit component, including commercially available integrated
circuit components known in the art by names such as CPU chips, GPU
chips, microprocessor, microcontroller, or co-processor.
Alternatively, a processor may be implemented in custom circuitry,
such as an ASIC, or semicustom circuitry resulting from configuring
a programmable logic device. As yet a further alternative, a
processor may be a portion of a larger circuit or semiconductor
device, whether commercially available, semi-custom or custom. As a
specific example, some commercially available microprocessors have
multiple cores such that one or a subset of those cores may
constitute a processor. However, a processor may be implemented
using circuitry in any suitable format.
[0074] Further, it should be appreciated that a computer may be
embodied in any of a number of forms, such as a rack-mounted
computer, a desktop computer, a laptop computer, or a tablet
computer. Additionally, a computer may be embedded in a device not
generally regarded as a computer but with suitable processing
capabilities, including a Personal Digital Assistant (PDA), a smart
phone or any other suitable portable or fixed electronic
device.
[0075] Also, a computer may have one or more input and output
devices. These devices can be used, among other things, to present
a user interface. Examples of output devices that can be used to
provide a user interface include printers or display screens for
visual presentation of output and speakers or other sound
generating devices for audible presentation of output. Examples of
input devices that can be used for a user interface include
keyboards, and pointing devices, such as mice, touch pads, and
digitizing tablets. As another example, a computer may receive
input information through speech recognition or in other audible
format.
[0076] Such computers may be interconnected by one or more networks
in any suitable form, including as a local area network or a wide
area network, such as an enterprise network or the Internet. Such
networks may be based on any suitable technology and may operate
according to any suitable protocol and may include wireless
networks, wired networks or fiber optic networks.
[0077] Also, the various methods or processes outlined herein may
be coded as software that is executable on one or more processors
that employ any one of a variety of operating systems or platforms.
Additionally, such software may be written using any of a number of
suitable programming languages and/or programming or scripting
tools, and also may be compiled as executable machine language code
or intermediate code that is executed on a framework or virtual
machine.
[0078] In this respect, the invention may be embodied as a computer
readable storage medium (or multiple computer readable media)
(e.g., a computer memory, one or more floppy discs, compact discs
(CD), optical discs, digital video disks (DVD), magnetic tapes,
flash memories, circuit configurations in Field Programmable Gate
Arrays or other semiconductor devices, or other tangible computer
storage medium) encoded with one or more programs that, when
executed on one or more computers or other processors, perform
methods that implement the various embodiments of the invention
discussed above. As is apparent from the foregoing examples, a
computer readable storage medium may retain information for a
sufficient time to provide computer-executable instructions in a
non-transitory form. Such a computer readable storage medium or
media can be transportable, such that the program or programs
stored thereon can be loaded onto one or more different computers
or other processors to implement various aspects of the present
invention as discussed above. As used herein, the term
"computer-readable storage medium" encompasses only a
non-transitory computer-readable medium that can be considered to
be a manufacture (i.e., article of manufacture) or a machine.
Alternatively or additionally, the invention may be embodied as a
computer readable medium other than a computer-readable storage
medium, such as a propagating signal.
[0079] The terms "program" or "software," when used herein, are
used in a generic sense to refer to any type of computer code or
set of computer-executable instructions that can be employed to
program a computer or other processor to implement various aspects
of the present invention as discussed above. Additionally, it
should be appreciated that according to one aspect of this
embodiment, one or more computer programs that when executed
perform methods of the present invention need not reside on a
single computer or processor, but may be distributed in a modular
fashion amongst a number of different computers or processors to
implement various aspects of the present invention.
[0080] Computer-executable instructions may be in many forms, such
as program modules, executed by one or more computers or other
devices. Generally, program modules include routines, programs,
objects, components, data structures, etc. that perform particular
tasks or implement particular abstract data types. Typically the
functionality of the program modules may be combined or distributed
as desired in various embodiments.
[0081] Also, data structures may be stored in computer-readable
media in any suitable form. For simplicity of illustration, data
structures may be shown to have fields that are related through
location in the data structure. Such relationships may likewise be
achieved by assigning storage for the fields with locations in a
computer-readable medium that conveys relationship between the
fields. However, any suitable mechanism may be used to establish a
relationship between information in fields of a data structure,
including through the use of pointers, tags or other mechanisms
that establish relationship between data elements.
[0082] Having thus described several aspects of at least one
embodiment of this invention, it is to be appreciated that various
alterations, modifications, and improvements will readily occur to
those skilled in the art.
[0083] Such alterations, modifications, and improvements are
intended to be part of this disclosure, and are intended to be
within the spirit and scope of the invention. Further, though
advantages of the present invention are indicated, it should be
appreciated that not every embodiment of the technology described
herein will include every described advantage. Some embodiments may
not implement any features described as advantageous herein and in
some instances one or more of the described features may be
implemented to achieve further embodiments. Accordingly, the
foregoing description and drawings are by way of example only.
[0084] The above-described embodiments of the technology described
herein can be implemented in any of numerous ways. For example, the
embodiments may be implemented using hardware, software or a
combination thereof. When implemented in software, the software
code can be executed on any suitable processor or collection of
processors, whether provided in a single computer or distributed
among multiple computers. Such processors may be implemented as
integrated circuits, with one or more processors in an integrated
circuit component, including commercially available integrated
circuit components known in the art by names such as CPU chips, GPU
chips, microprocessor, microcontroller, or co-processor.
Alternatively, a processor may be implemented in custom circuitry,
such as an ASIC, or semi-custom circuitry resulting from
configuring a programmable logic device. As yet a further
alternative, a processor may be a portion of a larger circuit or
semiconductor device, whether commercially available, semi-custom
or custom. As a specific example, some commercially available
microprocessors have multiple cores such that one or a subset of
those cores may constitute a processor. Though, a processor may be
implemented using circuitry in any suitable format.
[0085] Various aspects of the present invention may be used alone,
in combination, or in a variety of arrangements not specifically
discussed in the embodiments described in the foregoing and is
therefore not limited in its application to the details and
arrangement of components set forth in the foregoing description or
illustrated in the drawings. For example, aspects described in one
embodiment may be combined in any manner with aspects described in
other embodiments.
[0086] Also, the invention may be embodied as a method, of which an
example has been provided. The acts performed as part of the method
may be ordered in any suitable way. Accordingly, embodiments may be
constructed in which acts are performed in an order different than
illustrated, which may include performing some acts simultaneously,
even though shown as sequential acts in illustrative
embodiments.
[0087] Further, some actions are described as taken by a "user." It
should be appreciated that a "user" need not be a single
individual, and that in some embodiments, actions attributable to a
"user" may be performed by a team of individuals and/or an
individual in combination with computer-assisted tools or other
mechanisms.
[0088] Use of ordinal terms such as "first," "second," "third,"
etc., in the claims to modify a claim element does not by itself
connote any priority, precedence, or order of one claim element
over another or the temporal order in which acts of a method are
performed, but are used merely as labels to distinguish one claim
element having a certain name from another element having a same
name (but for use of the ordinal term) to distinguish the claim
elements.
[0089] The terms "approximately" and "about" may be used to mean
within .+-.20% of a target value in some embodiments, within
.+-.10% of a target value in some embodiments, within .+-.5% of a
target value in some embodiments, and yet within .+-.2% of a target
value in some embodiments. The terms "approximately" and "about"
may include the target value. The term "substantially equal" may be
used to refer to values that are within .+-.20% of one another in
some embodiments, within .+-.10% of one another in some
embodiments, within .+-.5% of one another in some embodiments, and
yet within .+-.2% of one another in some embodiments.
[0090] The term "substantially" may be used to refer to values that
are within .+-.20% of a comparative measure in some embodiments,
within .+-.10% in some embodiments, within .+-.5% in some
embodiments, and yet within .+-.2% in some embodiments. For
example, a first direction that is "substantially" perpendicular to
a second direction may refer to a first direction that is within
.+-.20% of making a 90.degree. angle with the second direction in
some embodiments, within .+-.10% of making a 90.degree. angle with
the second direction in some embodiments, within .+-.5% of making a
90.degree. angle with the second direction in some embodiments, and
yet within .+-.2% of making a 90.degree. angle with the second
direction in some embodiments.
[0091] Also, the phraseology and terminology used herein is for the
purpose of description and should not be regarded as limiting. The
use of "including," "comprising," or "having," "containing,"
"involving," and variations thereof herein, is meant to encompass
the items listed thereafter and equivalents thereof as well as
additional items.
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