U.S. patent application number 17/567685 was filed with the patent office on 2022-04-21 for segments in virtual build volumes.
This patent application is currently assigned to Hewlett-Packard Development Company, L.P.. The applicant listed for this patent is Hewlett-Packard Development Company, L.P.. Invention is credited to Hector LEBRON, Stephen G. RUDISILL, Morgan T. SCHRAMM, Matthew A. SHEPHERD, Vanessa VERZWYVELT, Jake WRIGHT.
Application Number | 20220118712 17/567685 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-21 |
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United States Patent
Application |
20220118712 |
Kind Code |
A1 |
LEBRON; Hector ; et
al. |
April 21, 2022 |
SEGMENTS IN VIRTUAL BUILD VOLUMES
Abstract
In an example, a virtual build volume comprising a
representation of at least a part of an object to be generated in
additive manufacturing is segmented into a plurality of nested
segments comprising a core segment, an inner peripheral segment and
an outer peripheral segment. Additive manufacturing control
instructions may be generated for the nested segments. The control
instructions for the core segment may provide a first region of the
object corresponding to the core segment and having a first color.
The control instructions for the outer peripheral segment may
provide a second color for a second region of the object
corresponding to the outer peripheral segment. The control
instructions for the inner peripheral segment may provide a third
color for a third region of the object corresponding to the inner
peripheral segment, wherein a color of the third region is
determined so as to at least partially visually mask the first
region.
Inventors: |
LEBRON; Hector; (San Diego,
CA) ; WRIGHT; Jake; (San Diego, CA) ;
RUDISILL; Stephen G.; (San Diego, CA) ; SHEPHERD;
Matthew A.; (Vancouver, WA) ; VERZWYVELT;
Vanessa; (Vancouver, WA) ; SCHRAMM; Morgan T.;
(Vancouver, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hewlett-Packard Development Company, L.P. |
Spring |
TX |
US |
|
|
Assignee: |
Hewlett-Packard Development
Company, L.P.
Spring
TX
|
Appl. No.: |
17/567685 |
Filed: |
January 3, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16076240 |
Aug 7, 2018 |
11241837 |
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PCT/US2017/041372 |
Jul 10, 2017 |
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17567685 |
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International
Class: |
B29C 64/393 20060101
B29C064/393; B33Y 10/00 20060101 B33Y010/00; B33Y 30/00 20060101
B33Y030/00; B33Y 50/02 20060101 B33Y050/02; B33Y 70/00 20060101
B33Y070/00; B29C 64/165 20060101 B29C064/165; G05B 19/4099 20060101
G05B019/4099 |
Claims
1-15. (canceled)
16. An object generation apparatus comprising: a build material
applicator; print agent applicators; and a processor to: control
the build material applicator to provide a plurality of layers of
build material on a print bed; control the print agent applicators
to apply print agent onto some of the plurality of layers of build
material to generate a core segment having a first color; control
the print agent applicators to apply print agent onto some of the
plurality of layers of build material to generate an outer
peripheral segment having a second color; and control the print
agent applicators to apply print agent onto some of the plurality
of layers of build material to generate an inner peripheral segment
having a third color, wherein the third color is based on the first
color and the second color and is to at least partially visually
mask the core segment, and wherein the core segment is nested
within the inner peripheral segment and the inner peripheral
segment is nested within the outer peripheral segment to form an
object.
17. The object generation apparatus of claim 16, wherein the print
agent comprises a colored agent and a fusing agent, the apparatus
further comprising: a heat source, wherein the processor is to
control the heat source to apply radiation on the layers of build
material to cause the build material on which the print agent has
been applied to fuse together and respectfully form the core
segment, the inner peripheral segment, and the outer peripheral
segment.
18. The object generation apparatus of claim 16, wherein the
processor is to control the print agent applicators to apply a
fusing agent and at least. one colorant to generate the outer
peripheral segment having the second color, the fusing agent
comprising a Caesium Tungsten, Bronze, or a Caesium Tungsten Oxide
composition.
19. The object generation apparatus of claim 16, wherein the
processor is to control the print agent applicators to apply a
fusing agent and at least one colorant to generate the inner
peripheral segment having the second color, the fusing agent
comprising a Caesium Tungsten, Bronze, or a Caesium Tungsten Oxide
composition.
20. The object generation apparatus of claim 16, wherein the
processor is to control the print agent applicators to apply a
carbon-based fusing agent to generate the core segment.
21. The object generation apparatus of claim 16, wherein the
processor is further to: control the print agent applicators to
apply a fusion inhibiting agent to form a first external peripheral
segment that is external to the outer peripheral segment.
22. The object generation apparatus of claim 21, wherein the
processor is further to: control the print agent applicators to
apply at least one colorant, in forming the first external
peripheral segment.
23. The object generation apparatus of claim 16, wherein the core
segment is encompassed in three dimensions by the inner peripheral
segment and wherein the inner peripheral segment is encompassed in
three dimensions by the outer peripheral segment.
24. A method comprising: controlling, by a processor, a build
material applicator to provide a. plurality of layers of build
material on a print bed; controlling, by the processor, print agent
applicators to apply print agent onto some of the plurality of
layers of build material to generate a core segment having a first
color; controlling, by the processor, the print agent applicators
to apply print agent onto some of the plurality of layers of build
material to generate an outer peripheral segment having a second
color and controlling, by the processor, the print agent
applicators to apply print agent onto some of the plurality of
layers of build material to generate an inner peripheral segment
having a third color, wherein the third color is based on the first
color and the second color and is to at least partially visually
mask the core segment, and wherein the core segment is nested
within the inner peripheral segment and the inner peripheral
segment is nested within the outer peripheral segment to form an
object.
25. The method of claim 24, wherein the print agent comprises a
colored agent and a fusing agent, the method further comprising:
controlling a heat source to apply radiation on the layers of build
material to cause the build material on which the print agent has
been applied to fuse together and respectfully form the core
segment, the inner peripheral segment, and the outer peripheral
segment.
26. The method of claim 24, further comprising: controlling the
print agent applicators to apply the print agent onto the plurality
of layers of build material to generate the core segment to be
surrounded in three dimensions by the inner peripheral segment and
the inner peripheral segment to be surrounded in three dimensions
by the outer peripheral segment.
27. The method of claim 24, further comprising: controlling the
print agent applicators to apply a fusing agent and at least one
colorant to generate the outer peripheral segment having the second
color, the fusing agent comprising a Caesium Tungsten, Bronze, or a
Caesium Tungsten Oxide composition.
28. A three-din.sup.-tensional object comprising: a core segment
having a first color; an outer peripheral segment having a second
color; and an inner peripheral segment having a third color,
wherein the third color is based on the first color and the second
color and is to at least partially visually mask the first color of
the core segment, wherein the core segment, the outer peripheral
segment, and the inner peripheral segment are formed through
selective application of print agents in layers of build material,
and wherein the core segment is nested within the inner peripheral
segment and the inner peripheral segment is nested within the outer
peripheral segment to form an object.
29. The three-dimensional object of claim 28, wherein the core
segment is surrounded in three dimensions by the inner peripheral
segment and the inner peripheral segment is surrounded in three
dimensions by the outer peripheral segment.
30. The three-dimensional object of claim 28, wherein the third
color of the inner peripheral segment is to allow for a gradual
transition from the first color of the core segment to the second
color of the outer peripheral segment while enabling the second
color of the outer peripheral segment to closely match an intended
color.
Description
BACKGROUND
[0001] Three-dimensional (3D) printing is an additive manufacturing
process in which three-dimensional objects may be formed, for
example, by the selective solidification of successive layers of a
build material. The object to be formed may be described in a data
model. Selective solidification may be achieved, for example, by
fusing, binding, or solidification through processes including
sintering, extrusion, and irradiation. The quality, appearance,
strength, and functionality of objects produced by such systems can
vary depending on the type of additive manufacturing technology
used.
BRIEF DESCRIPTION OF DRAWINGS
[0002] Non-limiting examples will now be described with reference
to the accompanying drawings, in which:
[0003] FIG. 1 shows an example of a segmented model;
[0004] FIG. 2 is an example of a machine readable medium in
association with a processor;
[0005] FIG. 3 is an example of a method for generating a segmented
data model for an object to be generated in additive
manufacturing;
[0006] FIGS. 4A and 4B show examples of segmented models;
[0007] FIGS. 5 and 6 are examples of apparatus for processing data
relating to additive manufacturing; and
[0008] FIGS. 7 and 8 are examples of methods for generating an
object.
DETAILED DESCRIPTION
[0009] Additive manufacturing techniques may generate a
three-dimensional object through the solidification of a build
material. In some examples, the build material may be a powder-like
granular material, which may for example be a plastic, ceramic or
metal powder. The properties of generated objects may depend on the
type of build material and the type of solidification mechanism
used. Build material may be deposited, for example on a print bed
and processed layer by layer, for example within a fabrication
chamber.
[0010] In some examples, selective solidification is achieved
through directional application of energy, for example using a
laser or electron beam which results in solidification of build
material where the directional energy is applied. In other
examples, at least one print agent may be selectively applied to
the build material, and may be liquid when applied. For example, a
fusing agent (also termed a `coalescence agent` or `coalescing
agent`) may be selectively distributed onto portions of a layer of
build material in a pattern derived from data representing a slice
of a three-dimensional object to be generated (which may for
example be generated from structural design data). The fusing agent
may have a composition which absorbs energy such that, when energy
(for example, heat) is applied to the layer, the build material
coalesces and solidifies to form a slice of the three-dimensional
object in accordance with the pattern. In other examples,
coalescence may be achieved in some other manner.
[0011] Another example of a print agent is a coalescence modifying
agent (which may be referred to as a modifying or a detailing
agent), which acts to modify the effects of a fusing agent and/or
energy applied, for example by inhibiting, reducing or increasing
coalescence or to assist in producing a particular finish or
appearance to an object. A property modification agent, for example
comprising a dye, colorant, a conductive agent, an agent to provide
transparency or elasticity or the like, may in some examples be
used as a fusing agent or a modifying agent, and/or as a print
agent to provide a particular property for the object.
[0012] Additive manufacturing systems may generate objects based on
structural design data. This may involve a designer generating a
three-dimensional model of an object to be generated, for example
using a computer aided design (CAD) application, The model may
define the solid portions of the object. To generate a
three-dimensional object from the model using an additive
manufacturing system, the model data can be processed to generate
slices of parallel planes of the model. Each slice may define at
least a portion of a respective layer of build material that is to
be solidified or caused to coalesce by the additive manufacturing
system.
[0013] Examples herein comprise considering an object to be
manufactured as a plurality of different model segments, which in
turn relate to object regions, to which different processing may be
applied. An example of an object 100 which is segmented into object
regions/segments is shown in FIG. 1, which comprises a core 102, an
inner segment/region 104 and an outer segment/region 106 (wherein
segments of a model are processed to form regions of an object).
The inner and outer segments in this example represent nested
`shells` of an object to be generated using different processing
parameters (e.g., different selections of print agents) to form
nested object regions.
[0014] When printing 3D color objects, there may be trade-offs
between color and mechanical properties. Higher density 3D objects
that have significant mechanical strength and functionality can be
produced when a greater amount of thermal energy is applied to the
build material for fusing the layers together. The amount of
thermal energy available for fusing depends in part on the
intensity with which the fusing agent absorbs the radiation (its
`absorptance`), and the absorptance of the fusing agent depends in
part on the color of the fusing agent. For example, a carbon black
composition may be an effective fusing agent as it has a high
energy absorptance in the infrared and near infrared range.
However, it is dark in color and, even if mixed with colorants, the
range of colors, or color gamut, which is accessible using a black
fusing agent is relatively small.
[0015] Other print agents may be used as fusing agents. For
example, the absorptance of suitable cyan, magenta, or yellow (C,
M, or Y) colorants for use in additive manufacturing, while
generally lower than that of, for example, carbon black-based
fusing agent, may be sufficiently high that they may function as
fusing agents. This may, however, result in an object having a
lower level of fusing when compared to build material which is
treated with a higher absorptance print agent. This may in turn
result in a weaker and/or lower density object. In other words,
color objects may have lower densities and/or less mechanical
strength than comparable black objects. In another example, the
energy provided may be increased to improve fusion, although this
may result in unintended color shifts.
[0016] Low-tint fusing agents which have a relatively high
absorptance (for example for example comprising a Caesium Tungsten
Bronze, or a Caesium Tungsten Oxide composition) and which are
lighter in color than a carbon black based print agent may be used
as fusing agents. However, these tend to more expensive than carbon
black fusing agents.
[0017] In the examples herein, by differentiating between segments,
a colorful shell may for example be formed around a strong core to
which a carbon black based fusing agent is applied. This allows the
object to be colorful without unduly compromising its strength.
Moreover, while it may be the case that a colored peripheral
segment could be determined about a core segment which is fused
using a carbon black based fusing agent, the color gamut of
resulting object may be reduced by the surface visibility of the
underlying core segment (which may be particular the case for
partially transparent outer peripheral segments). Therefore, in the
examples set out herein, an intermediate segment/object region
which provides at least a degree of masking of the color of the
core is formed. Providing at least one intermediate peripheral
segment may allow for a more gradual transition of properties (e.g.
from black to colourful).
[0018] For example, a particular intended color may be provided by
the outer peripheral region 106 having one color, the inner
peripheral region 104 having a different color, and the core 102 of
a still further color. The color of the core 102, which is labelled
as the first color in FIG. 1 may be at least substantially
incidental, being a result of a fusing agent which is selected for
its fusing properties. The color of the peripheral regions 104, 106
may be provided by using a combination of colorants. in the example
of FIG. 1, the outer peripheral segment is associated with a second
color and the inner, or intermediate, peripheral segment is
associated with a third color.
[0019] In some examples, at least some segments may for example
represent object regions which are to be generated using particular
combinations of print agents so as to have different color
properties, and which may have different mechanical or functional
properties.
[0020] For the purpose of discussion, the object 100 may be
considered to be represented in a manner similar to a `geological
model`, having a core (core segment/region 102), a mantel (inner
shell 104) and a crust (outer shell 106).
[0021] Although in this example the core segment 102 is
substantially central within the object 100, this need not be the
case in all examples. In addition, while the peripheral segments
104, 106 in this example are concentric, and the boundaries thereof
follow the contours of the surface of the object 100, they may lack
either or both of these qualities in other examples. Indeed in some
examples, there may be a plurality of object core segments 102
around which peripheral segments 104,106 are formed.
[0022] FIG. 2 shows a machine readable medium 200, which may be a
non-transitory and/or tangible machine readable medium, and which
is associated with a processor 202. The machine readable medium 200
stores instructions 204 which, when executed by the processor 202,
cause the processor 202 to carry out processes. The instructions
204 comprise instructions 206 to segment a virtual build volume
comprising a representation of at least part of an object to be
generated in additive manufacturing, wherein the virtual build
volume is segmented into a plurality of nested segments comprising
a core segment, an inner peripheral segment and an outer peripheral
segment.
[0023] The inner peripheral segment may be between the core segment
and the outer peripheral segment.
[0024] The nesting of the segments may be complete or partial (i.e.
a peripheral segment may extend around the entire perimeter of the
core segment or an inner peripheral segment, or around just part of
the perimeter). In some examples, the peripheral segment(s) may
form shell(s) around a core segment, as shown in FIG. 1. The core
may be any inner segment which has a peripheral segment formed
around at least a part thereof.
[0025] The virtual build volume may for example comprise a boundary
box enclosing the object, may be the size and shape of the object
(i.e. follow the surfaces of the object), and/or represent at least
part of a build volume in which the object is to be fabricated. In
some examples, the virtual build volume may comprise one or more
`slices`, each of which may represent a layer of the object to be
fabricated in layer-by-layer additive manufacturing of the object,
and/or at least part of a fabrication chamber in which the object
is to be fabricated.
[0026] The representation of the object may for example comprise a
data model and may for example be received from a memory, over a
network, over a communications link or the like. In some examples,
such a data model may for example comprise object model data and
object property data. The object model data may define a
three-dimensional geometric model of at least part of the model
object, including the shape and extent of all or part of an object
in a three-dimensional co-ordinate system. In some examples, the
data model may represent the surfaces of the object, for example as
a mesh. The object model data may for example be generated by a
computer aided design (CAD) application. Object property data may
define at least one object property for the, or a part of,
three-dimensional object to be generated. If no object property
data is present the object may have some default properties based
on the build material and print agents used. In one example, the
object property data may comprise any or any combination of a
color, flexibility, elasticity, rigidity, surface roughness,
porosity, inter-layer strength, density, transparency, conductivity
and the like for at least a part of the object to be generated. The
object property data may define multiple object properties for part
or parts of an object, and the properties specified may vary over
the object.
[0027] The instructions 204 further comprise instructions 208 to
generate additive manufacturing control instructions for the nested
segments. The additive manufacturing control instructions for each
segment are generated individually such that:
[0028] (i) the control instructions for the core segment are
generated so as to provide a first region of the object
corresponding to the core segment and having a first color;
[0029] (ii) the control instructions for the outer peripheral
segment are generated so as to provide a second color for a second
region of the object corresponding to the outer peripheral segment;
and
[0030] (iii) the control instructions for the inner peripheral
segment are generated so as to provide a third color for a third
region of the object corresponding to the inner peripheral segment,
wherein the color of the third region is determined so as to at
least partially visually mask the first region.
[0031] Masking the first region within the object may increase an
accessible apparent color gamut of the object, for example
increasing an accessible color brightness. In some examples, the
color of the third region may comprise a relatively light color, so
as to provide a light background for the second region (the outer
peripheral segment). In some examples, the third region may be
relatively opaque, and/or have a thickness so as to provide a
reasonable degree of masking of the core. In some examples, the
color of the third region may comprise a color which is
intermediate to the color of the core and the second region, so as
to mitigate the visual impact of the core on the appearance of the
object. The color, opacity, number of nested regions and their
thickness may all have an impact, individually or in combination,
on the degree to which the appearance of the core is masked.
Moreover, in some examples, the degree of masking may be selected
based on the intended color of the object: lighter objects may be
associated with a greater degree of masking (e.g. thicker, more
opaque and/or more numerous regions) than darker objects.
[0032] In some examples, the control instructions for the second
region specify the use of a low-tint fusing agent and at least one
colorant. This may allow a large color gamut to be accessed for the
second region without undue risk of color change due to
over-heating. In some examples, the control instructions for the
third region may also specify the use of a low-tint fusing agent
and at least one colorant. This also provides a large color gamut
for this region. In some examples, at least some darker fusing
agent, for example, carbon-black based fusing agent may be used in
the third region. In some examples, the control instructions
specify the use of a default print agent, which may be a carbon
black fusing agent, for the core. The color of the core may be at
least somewhat arbitrary, for example being a result of a selected
fusing agent, whereas the color of the second and third region may
be predetermined or specified, and print instructions may be
determined so as to provide such a color (for example comprising
colorants or the like).
[0033] In some examples, the print instructions for the third
(intermediate) region may be determined to access a smaller color
gamut than the color gamut which is accessible in the second
region.
[0034] Generating control instructions may for example comprise
using mapping resources such as a look-up table or mapping
algorithm to identity print agent amounts and/or combinations to
apply to an object region corresponding to a particular segment,
given target properties for that region. In some examples,
different mapping resources may associated with different
segments.
[0035] For example, a mapping resource for the first region (the
core segment) may map properties to a coverage of a fusing agent,
and in one example the possible printing instructions specify
different amounts of fusing agent, which in some examples is a
carbon-based fusing agent, and no other print agents. In other
words, in some examples, the core may be generated with carbon
black fusing agent, with no other agents being available for
selection, although the amount of carbon black fusing agent is
variable. For example the amount may be varied based on thermal
considerations (less fusing agent may be placed in regions of an
object which may otherwise overheat in object generation, more
fusing agent may be placed in regions of an object which may
otherwise fail to reach its fusing temperature in object
generation), or other object property specifications, such as
strength.
[0036] A mapping resource for the second and third region may allow
selection of a wider range of print agents than are available for
the first region, for example including at least one colorant, In
one examples, the selection may be made from a set of print agents
comprising a Cyan, Magenta, Yellow and black (Key) (CMYK) color set
(where the K may be provided by a cosmetic black colorant, selected
for its color providing qualities, and/or a carbon black fusing
agent). The print agent set may comprise low-tint fusing agent, In
other examples, other sets of print agents may be provided.
[0037] In some examples, the mappings for the third region may be
designed so as to restrict amounts of at least one colorant and/or
low-tint fusing agent when compared to the combinations accessible
in the second region. This may mean that the accessible gamut is
lower, but as the third region may not be directly viewed by a user
(instead being viewed via the second region), this may be
acceptable and may reduce costs associated with print agents.
[0038] In some example, therefore, the accessible gamut varies
between the regions. This may for example result in coarser color
match between a specified color and a generated color in some
regions when compared to others. For example, while the target
color for an object may be a particular green, the color mapping
for an outer region may closely match the intended green, whereas
the color mapping for an inner, or intermediate, region may result
in a green which is less closely matched, but which provides a
`background` which is sufficiently similar to the intended green
that the perceived color matches the intended green closely.
Providing fewer mappings reduces storage resources consumed any may
simplify the specification of print instructions (as more of a
volume of the object may be manufactured with a common print
instruction). Thus, by providing smaller gamuts for at least some
segments/regions, processing resources may be kept
[0039] FIG. 3 shows an example of a method which may be carried out
by the processor 202 carrying out instructions stored on the
machine readable medium 200.
[0040] Block 302 comprising segmenting a virtual build volume,
which in this example is a `slice` of a virtual representation of a
fabrication chamber. The slice corresponds to a single layer of the
object which is to be generated in an additive manufacturing
process. In addition to the core segment, the inner peripheral
segment and the outer peripheral segment described in relation to
FIGS. 1 and 2, the segmentation comprises a first and a second
external peripheral segment. These segments are external to the
representation of the object within the virtual build volume. Block
304 comprises determining control instructions for each
segment.
[0041] The control instructions for the core, the inner peripheral
segment and the outer peripheral segment may be generated as
described above. The control instructions for the first external
peripheral segment are generated so as to provide the second color
for a region of build material which is external to the object. For
example, this may comprise using a mapping resource which specifies
the use of a fusion inhibiting agent and at least one colorant.
[0042] In some examples, build material from outside the object may
adhere or partial fuse to the surfaces of the object, which can
decrease the quality of the appearance of the object. For example,
this may occur when unfused or partially fused build material
having a white appearance adheres to the surface of the object.
Therefore, in some examples, color may be added to a region of
build material corresponding to an external segment to match the
color of the object being generated. In other words, the colour may
be applied to what is intended to be outside of the object being
generated, as some of the build material to which the color is
applied may become attached to the object.
[0043] The fusion inhibiting agent may comprise a coolant, for
example water or some other substance which tends to inhibit fusion
(e.g., an alcohol, a glycol or the like, for example ethanol,
ethylene glycol, glycerin/glycerol, and/or propylene glycol). The
use of fusion inhibiting agent may assist in providing well defined
object boundaries, and limiting accidental fusion in portions of a
layer of build material where fusion is not intended.
[0044] The fusion inhibiting agent may have a color, which may be
taken into account when determining what colorants are applied to
provide the target color. The first external peripheral segment may
correspond to a region of a layer of build material which is not
intended to form part of the object under generation. The first
external peripheral segment may be adjacent to the outer peripheral
segment. For example, the first external peripheral segment may
comprise a border region which surrounds at least part of the outer
peripheral segment of the slice which is to be solidified to
provide a layer of the object. In examples in which the object as a
whole is segmented, the first external peripheral segment may
border an outer peripheral segment to be formed in a different
layer (and which therefore may be represented in a different
slice
[0045] The second external peripheral segment is also external to
the representation of the object within the virtual build volume,
and in some examples, is external or peripheral to the first
external peripheral segment. The control instructions for the
second external segment may be generated to specify the application
of a fusion inhibiting agent so as to minimise a color change in a
further region of build material which is external to the object.
This may for example comprise specifying the application of just
fusion inhibiting agent, and no colorant.
[0046] As applying color to a region which is intended to be
external to the object utilises resources and/or may impact the
recyclability of the build material, such a segment may designed to
be relatively thin, for example, extending across a region which
may be heated by proximity to the fused object region. However,
this may not provide fusion inhibition in all areas which are at
risk of fusion and therefore an additional region of build material
may be treated with fusion inhibiting agent. In some examples, the
remaining region of the slice after the core segment, inner
peripheral segment, the outer peripheral segment and the first
external peripheral segment have been defined may comprise the
second external peripheral segment.
[0047] FIG. 4A shows a plan view of an example of a slice 400 of a
virtual build volume 402 comprising an object 404 to be generated.
In this example, the object 404 comprises an elongate structure
with a narrow central section 406 and two wider end sections 408a,
408b. In this example, the core segment 410 extends towards either
end of the object via the central section 406. An inner 412 and an
outer 414 peripheral segment are defined. A first 416 and a second
418 external peripheral segment are defined outside the object. To
continue the example of a geological model above, the external
peripheral segments 416, 418 may be thought of as comprising the
`atmosphere` of the object. In this example, the second external
peripheral segment extends to fill the build volume 402, but this
may not be the case in all examples.
[0048] FIG. 4B shows a plan view of an example of a slice of a
virtual build volume for generating a different object to that
shown in FIG. 4A, in which an inner peripheral segment 420 is wider
in a first section 422 than in a second section 424 of the build
volume (and a core segment 426 is correspondingly narrower in the
first section 422 than in the second section 424). Two outer
peripheral segments 428, 430 are of constant (and in this example,
equal) thickness. A first outer peripheral segment 428 lies in the
first section 422 of the build volume and the second outer
peripheral segment 430 lies in the second section 424 of the build
volume. In this example, the color of the first outer peripheral
segment 428 may be lighter than the color of the second outer
peripheral segment 430.
[0049] The increased thickness of the inner peripheral segment 420
in the first section 422 may provide a higher degree of color
masking, which may be appropriate given the lighter overlying
color. In another example, the thickness may vary based on
transparency, or an appearance quality specification, or for some
other reason which means that increased masking is appropriate. In
other examples, a similar affect may be achieved by increasing the
thickness of an outer peripheral portion where increased masking is
sought. However, there may be a greater level of versatility
associated with the inner peripheral segments than the outer
peripheral segments (for example, a color match may be less
accurate (for example, a choice of agents to provide a target color
may be less constrained as the color may be matched less
precisely), and/or the choice of print agent may include carbon
black whereas this may be inaccessible for the outer peripheral
segment), in some examples it may be the inner peripheral segments
tend to vary in thickness in preference to the outer peripheral
segments.
[0050] Varying the thickness of peripheral segments may also allow
other trade-offs between properties, For example if the peripheral
segments 420, 428, 430 are to be processed to provide a colourful
shell and the core 426 is to be processed to provide strength (for
example, comprising a high proportion of `carbon black` fusing
agent), there may be different trade-offs between the thickness of
the first and second portion of a build volume: the first section
422 may be more colorful than the second section 424 as it has a
thicker peripheral segment 420. However, the second section 424 may
be relatively strong as, as described above, colored object
portions may have a lower strength due to their generally lower
capacity to absorb radiation.
[0051] Additional peripheral segments may be formed in other
examples.
[0052] Where slices of the object are formed into segments, this
may be carried out independently for different slices. For example,
a core segment in one slice may be aligned with, partially aligned
with, or non-overlapping to a core segment in a previous or
subsequent slice. Different slices may have differing numbers of
segments.
[0053] In some examples, at least one of a number of segments and a
thickness of the segments for an object region is determined based
on a local object geometry.
[0054] For example, the local geometry of the object at each point
where the segment may exist may be considered. When considering a
slice of the object, this may comprise a cross-section of the slice
at that point. Where the object as a whole is to be segmented, the
size of an object feature may be determined. In one example this
may comprise integrating for `voxel density`. A voxel may describe
a region of the model and is analogous to a three dimensional
pixel. The voxels may be of a consistent shape and size, in some
examples being cuboids which are determined such that each voxel
can be individually addressed by an object generation apparatus
(although such apparatus may also be able to apply print agents
with sub-voxel resolution). In some examples, the object properties
are specified at voxel resolution.
[0055] Integrating for voxel density may comprise determining the
number of voxels in, for example, a fixed spherical radius which
contains part of an object model to determine local feature size
(or circular radius in a slice). In such an example, if there is a
high proportion of voxels within this local neighbourhood which are
filled with the object, it may be determined that the feature is
relatively large. If there are few voxels filled in the local
neighbourhood, a small feature may be identified. In other
examples, feature size may be determined in some other manner, for
example having been tagged by a user or the like.
[0056] The visual requirements for color may vary over an object:
regions of the object which are relatively small or geometrically
complex (the human eye being relatively less sensitive to color
variations over such areas) may be printed with a lower quality
standard applied to color without sacrificing the perceived color
quality of the object. Thus a peripheral segment may be thinner in
such sections and a use of colored print agents may be reduced than
in examples where such a segment was thicker, and/or at least one
peripheral segment specified for at least one object region may not
be provided in such a region. In another example, the bottom
section of an object may have different dimensional tolerances or
strength properties than the top of a part. A volume of a core
segment may be increased in such an object portion and/the number
of peripheral segments may be reduced in such an area. As a fine
feature may be weaker than parts with a larger cross-section, any
core may for example constitute a relatively large proportion of
the cross-sectional area of the object at such a point (which may
for example sacrifice colorfulness, although as noted above, this
may be less critical for smaller areas). In addition, this may
allow for different thermal properties during a fusing process
depending on a location of an object. For example, initial layers
(i.e. those formed earlier in additive manufacturing) may, by
specifying larger cores or inner segments for such layers, be
provided with higher amounts of fusing agent (or of a more
effective fusing agent) than upper layers, which may absorb heat
from a previous layer.
[0057] Thus in some examples, not all object regions may be
associated with the specification of inner and outer peripheral
segments, and/or in some examples, in which a plurality of segments
may be specified, this may vary over the object based on local
geometry.
[0058] As mentioned above, in some examples, at least one
peripheral segment may be external to the model of the object,
comprising an `atmosphere` segment. This may for example be used to
control an extent to which fusing inhibiting or detailing agent is
applied about the object. As such agents can be thought of heat
reducing, this may be tailored to the amount of heat likely to be
generated in a portion of the object: generally, object portions of
smaller cross section may generate less heat than object portions
of larger cross section, Thus, a region of a smaller object
features may not have any external segments specified, or such
segments may be thin.
[0059] In some examples, as has been mentioned above, the thickness
of the segments may be moderated based on local object geometry
(which may be a thickness in two or three dimensions) of at least
one peripheral segment around the object core segment.
[0060] In some examples, a segment thickness may be sacrificed, for
example, to allow another segment to occupy a greater volumetric
proportion. For example, an outer peripheral segment may be reduced
in width to allow an inner segment (which may be the core segment
or an inner peripheral segment) to have a particular strength,
fusing heat, to have a threshold size, or the like. This may be
based on a local feature size, for example the cross sectional area
of the object at a location. In another example, determining the
thickness based on object geometry may comprise determining a
location of a segment (or part of the segment) within an object:
for example, higher parts of the object may be associated with a
different segment thickness than lower parts, and/or upwards facing
faces may be associated with a different segment thickness than
downwards facing faces, which may take into account thermal
consideration during manufacture, or the like,
[0061] In some examples, the thickness may be based on an intended
appearance. For example, relatively opaque and/or dark colored
segments may be thinner than relatively transparent and/or light
colored segments. The color, opacity, number of nested regions and
their thickness may all have an impact, individually or in
combination, on the degree to which the impact of the appearance of
the core on the appearance of the object is masked.
[0062] FIG. 5 is an example of an apparatus 500 comprising
processing circuitry 502. In this example the processing circuitry
502 comprises an object segmentation module 504 and a control
instruction module 506. In use of the apparatus 500, the object
segmentation module 504 represents a virtual build volume
comprising at least part of an object to be generated in additive
manufacturing as a plurality of nested segments comprising an
object core segment, an inner peripheral segment and an outer
peripheral segment. The control instruction module 506 generates
control instructions for generating an object, wherein the
generation of control instructions by the control instruction
module is such that:
[0063] (i) the control instructions for the core segment are
generated so as to provide a first region of the object
corresponding to the core segment having a first color;
[0064] (ii) the control instructions for the outer peripheral
segment are generated so as to provide a second color for a second
region of the object corresponding to the outer peripheral segment;
and
[0065] (iii) the control instructions for the inner peripheral
segment are generated so as to provide a third color for a third
region of the object corresponding to the inner peripheral segment,
wherein the color of the third region is determined so as to
increase an accessible color gamut of the object.
[0066] For example, this may be the color gamut of the object's
surfaces as viewed externally. In other words, the apparent color
gamut of the second portion (i.e. as observed by a viewer from an
external view point) may be increased by selecting a color for the
third region. The gamut may be increased compared to the accessible
gamut absent such third region. For example, the object may be
perceived to have a color which could not be achieved in practice
absent the intervening third portion, given the existence of the
core. The third color may for example be relatively light and/or be
closer to the second color than the first color (i.e. the color
difference between the first color and the second color may be
greater than the color difference between the third color and the
second color).
[0067] The shape of the peripheral segment(s) may follow the
contours of the surfaces of an object or may differ therefrom. In
some examples, the object segmentation module 504 may generate the
virtual build volume from a received object model and generating
the virtual build volume may comprise modifying the received object
model, for example by segmenting the received object model.
[0068] FIG. 6 shows an example of an apparatus 600 comprising
processing circuitry 602 which comprises the object segmentation
module 504 and the control instruction module 506, as well as a
model assessment module 604, a model slicing module 606 and an
object generation apparatus 608.
[0069] In use of the apparatus 600, the model assessment module 604
determines, from data relating to the object, at least one of a
relative volumetric composition and a shape for the segments. The
shape may be determined such that at least one peripheral segment
has a variable thickness. In some examples, the model assessment
module 604 may determine localised relative volumetric compositions
for the segments within the object based on a local geometry of the
object and at least one intended object property. For example, in
the region of a smaller object feature, a core segment may be
occupy a relatively larger relative volume than in the region of a
larger object feature. In another example, in a lower region of the
object, a core segment may be occupy a relatively larger relative
volume than in a higher region of the object. In another example,
in an intended front face of an object, a peripheral segment (for
example, an outer peripheral segment) may occupy a higher relative
volume than in an intended rear or bottom face, in which a lower
appearance quality level may be tolerated.
[0070] In use of the apparatus 600, the model slicing module 606
may represent the object model as a plurality of slices
corresponding to an integer number of object layers to be generated
in layer by layer additive manufacturing. In some examples, one
layer is represented by each slice, The slicing may occur before or
after the object is segmented. In some examples, the slicing occurs
after control instructions have been generated. When the slicing is
carried out relatively early in the process, this allows the slices
to be treated separately, which may allow for efficient use of data
processing resources (for example, slices corresponding to layers
to be formed later may be processed after slices corresponding to
layers to formed earlier, and in some examples while fabrication of
earlier layers has begun).
[0071] The object generation apparatus 608 is to generate the
object according to the control instructions, and may to that end
comprise additional components such as a print bed, build material
applicator(s), print agent applicator(s), print agent source(s),
heat source(s) and the like, not described in detail herein,
[0072] In some examples, the object generation apparatus 608 may
carry out a method as described in relation to FIG. 7 (although the
method may be carried out by other object generation
apparatus).
[0073] The apparatus 600 may carry out the method of FIG. 3.
[0074] The method of FIG. 7 comprises a method of generating an
object using additive manufacturing which comprises, in block 702,
providing build material. For example, one or more layers of build
material may be formed of a granular material, such as a granular
plastic material. The build material may be a powder, a liquid, a
paste, or a gel. Examples of build material include
serni-crystalline thermoplastic materials. A layer may for example
be formed on a print bed, or on a previously formed and processed
layer of build material.
[0075] Block 704 comprises applying, to a first region of the build
material which is to be fused in additive manufacturing, a first
selection of print agent. Block 706 comprises applying, to a second
region of the build material which is to be fused in additive
manufacturing, a second selection of print agent, wherein the
second selection comprises at least one colorant. Block 708
comprises applying, to a third region of the build material which
is to be fused in additive manufacturing and which is between the
first region and the second region, a third selection of print
agent, wherein the third selection is to at least partially
visually mask the first region. In some example the first region
may be visually masked when viewed from a surface of an object
being generated.
[0076] Blocks 704, 706 and 708 may be carried out in an overlapping
timeframe, for example as a print agent applicator is scanned over
a layer of build material. As such, application of the print agent
to the first, second and third regions may be interleaved depending
on the position of the print agent applicator over the layer of
build material.
[0077] In some examples, application of print agent is carried out
using a print agent distributor, for example a print head which may
dispense print agent using `inkjet` techniques or the like, and
which may for example move relative to the layer of print agent,
and may perform at least one printing pass of the layer of build
material. The print agent may be applied from a plurality of print
agent sources to provide the target selection (for example using
appropriate halftoning techniques), or may be pre-mixed to provide
the target selection.
[0078] Where colorant is applied, the colorant may in some examples
comprise a colored print agent, a selection of a plurality of
colored agents, or at least one colored agent and a fusing agent.
The colorant may comprise organic pigment, inorganic pigment,
organic dye, thermochromic dye such as leuco dye, or the like. The
colorant may be selected to (in some examples in combination with a
fusing agent) provide a target color within a color space which may
be applied to the layer of build material. For example, the
colorant may comprise a choice of different colored agents, for
example, from a CYMK (cyan, magenta, yellow, and black) color set,
in some examples with the addition of orange green and violet
colored agents, and/or light versions of the CYM agents, and the
like. In other examples, alternative colorant sets may be
provided.
[0079] Applying print agent may comprise applying a fusing agent to
the first region. The fusing agent may be an absorber of IR
radiation, visual radiation, near IR radiation or the like.
[0080] For example, the fusing agent may comprise an agent having a
high energy absorptance (noting that a material's "absorptance"
relates to its effectiveness in absorbing radiant energy) in the
infra-red and/or near infrared range, for example a carbon
black-based print agent, or an alternative (for example a low-tint)
fusing agent, for example comprising a Caesium Tungsten Bronze, or
a Caesium Tungsten Oxide composition which may be lighter in color
than a carbon black based print agent.
[0081] In other examples, the colorant(s) themselves may be
sufficiently efficient thermal absorbers to act as fusing agent.
For example, the energy may be infrared energy: any agent which is
not transparent in the infrared region will absorb at least some
energy which may cause heating. In some examples, radiation to be
applied may be increased so as to cause fusion with applied agents
of relatively low absorptance. In some examples, print agent may be
applied to comprise fusing agent for some target colors and not for
others to achieve a print agent with an acceptable thermal
absorptance.
[0082] In some examples, while a fusing agent may be black in
color, a black colorant of a colorant set such as the CMYK colorant
set may comprise a cosmetic black colorant, selected for its color
properties, whereas a black colored fusing agent may comprise a
material (such as carbon black) selected for its absorptance in the
near-infrared range. In other words, a cosmetic black colorant may
be provided in addition to at least one fusing agent, even where
that fusing agent is black in color. The cosmetic black agent may
have lower absorptance that the fusing agent in a waveband of
radiation intended to result in heating of the build material.
[0083] Block 710 comprises heating the build material by exposing
the build material to radiation, for example so as to cause fusing
of the first, second and third region.
[0084] For example, this may comprise exposing a layer containing
the regions to a heat source such as a heat lamp. In some examples,
heating is carried out at least partially concurrently with print
agent application (for example, a print agent applicator may
comprise a heat source). Heating may be carried out before, during
and/or after print agent application.
[0085] In some examples, the method may be carried out over each of
a plurality of layers of build material until an object is
formed.
[0086] FIG. 8 is an example of a method which may be integrated
with the method of FIG. 7. Block 802 comprises applying, to a
fourth region of the build material which is adjacent to the second
region, print agent comprising a combination of a fusion inhibiting
agent and colorant, wherein the combination is applied according to
a target color of the second region. The fourth region may be
intended to remain unfused in additive manufacturing (i.e.
corresponding to first external peripheral segment described
above).
[0087] In some examples, the colored print agents applied to the
fourth portion may be taken from the same set of colored print
agents as is applied to the second and/or third region. For
example, a selection from the same set of CMYK color agents may be
applied to different regions, but the relative amounts of each
color agent may differ between regions.
[0088] In some examples, an amount of fusion inhibiting agent to be
applied in block 802 may be determined based on an energy
absorptance of the colorant applied to the fourth region. For
example, if a colorant (or combination of colored agents) with a
relatively high energy absorptance is applied to the fourth region,
this will mean that the colorant at the fourth region comparatively
absorbs more thermal energy during a fusion process of the first,
second and third regions than if the colorant has a relatively low
energy absorptance. In order to reduce the likelihood of fusion
occurring in the fourth region, the effect of using a colorant with
a relatively high energy absorption can be offset by an increased
amount of fusion inhibiting agent. In some examples, any colorants
applied to different regions are selected from a common colorant
set.
[0089] Similar to blocks 704-708, in sonic examples, applying print
agent to the fourth region is carried out using a print agent
distributor, for example a print head which may dispense print
agent using `inkjet` techniques or the like, and which may for
example move relative to the layer of build material, and may
perform at least one printing pass of a layer of build material.
This may be interleaved with the processes of blocks 704-708.
[0090] The amount of fusion inhibiting agent to be applied to the
fourth region of the build material may also be determined based on
other factors, such as an efficiency with which the fusing agent
applied to the region to be fused (or for example, the second
region to which the fourth region is adjacent) absorbs radiation
(as this can result in heating of the fourth region), and/or the
energy to be applied to the build material.
[0091] Examples in the present disclosure can be provided as
methods, systems or machine readable instructions, such as any
combination of software, hardware, firmware or the like. Such
machine readable instructions may be included on a computer
readable storage medium (including but is not limited to disc
storage, CD-ROM, optical storage, etc.) having computer readable
program codes therein or thereon.
[0092] The present disclosure is described with reference to flow
charts and block diagrams of the method, devices and systems
according to examples of the present disclosure. Although the flow
diagrams described above show a specific order of execution, the
order of execution may differ from that which is depicted. Blocks
described in relation to one flow chart may be combined with those
of another flow chart. It shall be understood that various blocks
in the flow charts and block diagrams, as well as combinations
thereof, can be realized by machine readable instructions.
[0093] The machine readable instructions may, for example, be
executed by a general purpose computer, a special purpose computer,
an embedded processor or processors of other programmable data
processing devices to realize the functions described in the
description and diagrams. In particular, a processor or processing
apparatus may execute the machine readable instructions. Thus
functional modules of the apparatus and devices (such as the object
segmentation module 504, the control instruction module 506, the
model assessment module 604 and the model slicing module 606) may
be implemented by a processor executing machine readable
instructions stored in a memory, or a processor operating in
accordance with instructions embedded in logic circuitry. The term
`processor` is to be interpreted broadly to include a CPU,
processing unit, ASIC, logic unit, or programmable gate array etc.
The methods and functional modules may all be performed by a single
processor or divided amongst several processors.
[0094] Such machine readable instructions may also be stored in a
computer readable storage that can guide the computer or other
programmable data processing devices to operate in a specific
mode.
[0095] Such machine readable instructions may also be loaded onto a
computer or other programmable data processing devices, so that the
computer or other programmable data processing devices perform a
series of operations to produce computer-implemented processing,
thus the instructions executed on the computer or other
programmable devices realize functions specified by flow(s) in the
flow charts and/or block(s) in the block diagrams.
[0096] Further, the teachings herein may be implemented in the form
of a computer software product, the computer software product being
stored in a storage medium and comprising a plurality of
instructions for making a computer device implement the methods
recited in the examples of the present disclosure.
[0097] While the method, apparatus and related aspects have been
described with reference to certain examples, various
modifications, changes, omissions, and substitutions can be made
without departing from the spirit of the present disclosure, It is
intended, therefore, that the method, apparatus and related aspects
be limited only by the scope of the following claims and their
equivalents, It should be noted that the above-mentioned examples
illustrate rather than limit what is described herein, and that
those skilled in the art will be able to design many alternative
implementations without departing from the scope of the appended
claims. Features described in relation to one example may be
combined with features of another example.
[0098] The word "comprising" does not exclude the presence of
elements other than those listed in a claim, "a" or "an" does not
exclude a plurality, and a single processor or other unit may
fulfil the functions of several units recited in the claims.
[0099] The features of any dependent claim may be combined with the
features of any of the independent claims or other dependent
claims.
* * * * *