3D PRINTED ITEM WITH SURFACE WITH A WOVEN APPEARANCE

Abstract

The invention provides a method wherein 3D printed layers are stacked, but wherein at one or more positions one layer is shifted sideways relative to the other. It looks like a (small) excursion. Hence, the one layer deviates sideways from the layer below and returns back on the layer below. This may be over a relatively small length. The excursion is chosen such, that there is an opening between the lower layer and the layer that deviates sideways. In this way, a 3D printed item comprising a stack of layers may have (physical) openings, which allow transmission of light. In general, the layer height of the layers is not adapted. The deviations or excursions may be provided in a regular way. This provides a 3D printed with a regular arrangement of openings Note that not each layer of the 3D printed item necessarily includes such deviations or excursions.

Claims

1. A method for producing a 3D item by means of fused deposition modelling, the 3D item comprising an item wall having a plurality of layers of 3D printed material, the plurality of layers comprising a stack of a first layer and a second layer, which are configured on top to each other, wherein the method comprises a 3D printing stage comprising layer-wise depositing 3D printable material to provide the 3D item, and wherein the method comprises 3D printing the first layer and subsequently the second layer by moving a printer head along respective print paths in an xy-plane, wherein, for at least one of the first and second layers, the print path has a plurality of print path deviations in an arrangement in the xy-plane relative to the print path of the other of the first and second layers, thereby defining an arrangement of openings between the first and second layers and between both sides of the item wall.

2. The method according to claim 1, wherein the layers have a layer width, wherein the one or more print path deviations have an amplitude (D) relative to the print path, and wherein W<D≤10*W, wherein the one or more deviations have deviation widths (W1) at half amplitudes (D), wherein 0.1*W≤W1≤20*W.

3. The method according to claim 1, comprising 3D printing at least one of the first and second layers with a plurality of print path deviations in one or more of a block-shape way, in a zig-zag way, and in a meandering way.

4. The method according to claim 1, wherein the layers have a layer width (W), wherein the method comprises 3D printing at least one of the first and second layers with a plurality of print path deviations having a first pitch P1, and wherein 2*W≤P1≤20*W.

5. The method according to claim 1, comprising 3D printing two or more layers each with a plurality of print path deviations wherein the print path deviations of at least two of the two or more layers are shifted relative to each other.

6. The method according to claim 1, comprising 3D printing two or more layers each with a plurality of print path deviations, wherein the layers have a layer height, wherein for a set of two layers, which are nearest neighboring layers of each other, each with the plurality of print path deviations, applies one or more of: (i) the deviations of both of the layers have a same first pitch P1, but the print path deviations of the layers are shifted relative to each other, and (ii) nearest neighboring print path deviations in different layers of the set of two layers have a mutual distance (d1) of at least the layer height (H).

7. The method according to claim 1, wherein the method comprises providing a plurality of layers with a plurality of print path deviations in a regular arrangement to provide a regular arrangement of openings between both sides of the item wall.

8. The method according to claim 1, wherein the method comprises a continuous 3D printing of the at least one of the first and second layers with the one or more print path deviations.

9. A 3D item comprising 3D printed material, wherein the 3D item comprises an item wall having a plurality of layers of 3D printed material, wherein the plurality of layers comprises a stack of a first layer and a second layer, which are configured on top of each other, wherein the first layer and the second layer have been 3D printed by moving a printer head along respective print paths in an xy-plane, wherein relative to a projection on the xy-plane of the first and second layers at least one of the first and second layers defines a plurality of layer deviations in an arrangement protruding relative to the other of the first and second layers, thereby defining an arrangement of openings between the first and second layers and between both sides of the item wall.

10. The 3D item according to claim 9, wherein the layers have a layer width, wherein the at least one of the first and second layers defining one or more layer deviations comprises a stack axis (SA) in the projection on the xy-plane, wherein the one or more deviations have an amplitude (D) relative to the stack axis (SA) in the projection on the xy-plane (SA), wherein W≤D<10*W.

11. The 3D item according to claim 9, wherein two or more layers each comprise a plurality of layer deviations, wherein the layers have a layer height (H), wherein for a set of two layers each with the plurality of layer deviations which are nearest neighboring layers of each other applies one or more of: (i) the layer deviations of both of the layers have a same first pitch P1, but the layer deviations of the layers are shifted relative to each other, and (ii) nearest neighboring layer deviations in different layers of the set of two layers have a mutual distance (d1) of at least the layer height (H).

12. A lighting device comprising the 3D item according to claim 9, wherein the 3D item is configured as one or more of (i) at least part of a lighting device housing, (ii) at least part of a wall of a lighting chamber, and (iii) an optical element.

13. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0076] FIGS. 1a-1c schematically depict some general aspects of the 3D printer and of an embodiment of 3D printed material;

[0077] FIGS. 2a-2b shows a reference example;

[0078] FIGS. 3a-3c schematically depicts embodiments;

[0079] FIGS. 4a-4c schematically depict further embodiments;

[0080] FIG. 5 depicts an example; and

[0081] FIG. 6 schematically depict applications. The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0082] FIG. 1a schematically depicts some aspects of the 3D printer. Reference 500 indicates a 3D printer. Reference 530 indicates the functional unit configured to 3D print, especially FDM 3D printing; this reference may also indicate the 3D printing stage unit. Here, only the printer head for providing 3D printed material, such as an FDM 3D printer head is schematically depicted. Reference 501 indicates the printer head. The 3D printer of the present invention may especially include a plurality of printer heads (see below). Reference 502 indicates a printer nozzle. The 3D printer of the present invention may especially include a plurality of printer nozzles, though other embodiments are also possible. Reference 320 indicates a filament of printable 3D printable material (such as indicated above). For the sake of clarity, not all features of the 3D printer have been depicted, only those that are of especial relevance for the present invention (see further also below). Reference 321 indicates extrudate (of 3D printable material 201).

[0083] The 3D printer 500 is configured to generate a 3D item 1 by layer-wise depositing on a receiver item 550, which may in embodiments at least temporarily be cooled, a plurality of layers 322 wherein each layers 322 comprises 3D printable material 201, such as having a melting point T.sub.m. The 3D printable material 201 may be deposited on a substrate 1550 (during the printing stage). By deposition, the 3D printable material 201 has become 3D printed material 202. 3D printable material 201 escaping from the nozzle 502 is also indicated as extrudate 321. Reference 401 indicates thermoplastic material.

[0084] The 3D printer 500 may be configured to heat the filament 320 material upstream of the printer nozzle 502. This may e.g. be done with a device comprising one or more of an extrusion and/or heating function. Such device is indicated with reference 573, and is arranged upstream from the printer nozzle 502 (i.e. in time before the filament material leaves the printer nozzle 502). The printer head 501 may (thus) include a liquefier or heater. Reference 201 indicates printable material. When deposited, this material is indicated as (3D) printed material, which is indicated with reference 202.

[0085] Reference 572 indicates a spool or roller with material, especially in the form of a wire, which may be indicated as filament 320. The 3D printer 500 transforms this in an extrudate 321 downstream of the printer nozzle which becomes a layer 322 on the receiver item or on already deposited printed material. In general, the diameter of the extrudate 321 downstream of the nozzle 502 is reduced relative to the diameter of the filament 322 upstream of the printer head 501. Hence, the printer nozzle is sometimes (also) indicated as extruder nozzle. Arranging layer 322 by layer 322 and/or layer 322t on layer 322, a 3D item 1 may be formed. Reference 575 indicates the filament providing device, which here amongst others include the spool or roller and the driver wheels, indicated with reference 576.

[0086] Reference A indicates a longitudinal axis or filament axis or axis of elongation of a layer of 3D printed material 202.

[0087] Reference C schematically depicts a control system, such as especially a temperature control system configured to control the temperature of the receiver item 550. The control system C may include a heater which is able to heat the receiver item 550 to at least a temperature of 50° C., but especially up to a range of about 350° C., such as at least 200° C.

[0088] Alternatively or additionally, in embodiments the receiver plate may also be moveable in one or two directions in the x-y plane (horizontal plane). Further, alternatively or additionally, in embodiments the receiver plate may also be rotatable about z axis (vertical). Hence, the control system may move the receiver plate in one or more of the x-direction, y-direction, and z-direction.

[0089] Alternatively, the printer can have a head can also rotate during printing. Such a printer has an advantage that the printed material cannot rotate during printing.

[0090] Layers are indicated with reference 322, and have a layer height H and a layer width W.

[0091] Note that the 3D printable material is not necessarily provided as filament 320 to the printer head. Further, the filament 320 may also be produced in the 3D printer 500 from pieces of 3D printable material.

[0092] Reference D indicates the diameter of the nozzle (through which the 3D printable material 201 is forced).

[0093] FIG. 1b schematically depicts in 3D in more detail the printing of the 3D item 1 under construction. Here, in this schematic drawing the ends of the filaments 321 in a single plane are not interconnected, though in reality this may in embodiments be the case. Reference H indicates the height of a layer. Layers are indicated with reference 203. Here, the layers have an essentially circular cross-section. Often, however, they may be flattened, such as having an outer shape resembling a flat oval tube or flat oval duct (i.e. a circular shaped bar having a diameter that is compressed to have a smaller height than width, wherein the sides (defining the width) are (still) rounded).

[0094] Hence, FIGS. 1a-1b schematically depict some aspects of a fused deposition modeling 3D printer 500, comprising (a) a first printer head 501 comprising a printer nozzle 502, (b) a filament providing device 575 configured to provide a filament 321 comprising 3D printable material 201 to the first printer head 501, and optionally (c) a receiver item 550. In FIGS. 1a-1b, the first or second printable material or the first or second printed material are indicated with the general indications printable material 201 and printed material 202, respectively. Directly downstream of the nozzle 502, the filament 321 with 3D printable material becomes, when deposited, layer 322 with 3D printed material 202.

[0095] FIG. 1c schematically depicts a stack of 3D printed layers 322, each having a layer height H and a layer width W. Note that in embodiments the layer width and/or layer height may differ for two or more layers 322. Reference 252 in FIG. 1c indicates the item surface of the 3D item (schematically depicted in FIG. 1c).

[0096] Referring to FIGS. 1a-1c, the filament of 3D printable material that is deposited leads to a layer having a height H (and width W). Depositing layer 322 after layer 322, the 3D item 1 is generated. FIG. 1c very schematically depicts a single-walled 3D item 1.

[0097] FIG. 2a schematically depicts the layer-wise deposition by 3D printing of layers 322 of 3D printed material 202. From left to right, it is shown that a stack of 4 layers is provide. The layer height is indicated with reference H and the layer width with reference W. Each layer has an axis of elongation A of the layer of 3D printed material 202. Note that these axes may also be curved. Further, reference 323 indicates a respective print path, which in these embodiments essentially coincide. Note that the stack may provide a face wherein all print paths 323 and/or axes of elongation A are comprised. Reference SA indicates a stack axis of a layer 322; each layer may comprise a stack axis. The stack axis may in embodiments be essentially parallel, though this is not necessarily the case. As can be seen on the right, the stack axes SA may define a cross-sectional plane. In embodiments, this plane may be planar, but in other embodiments this plane may be non-planer (i.e. a 1D or 2D curve plane). A cross-section is made of each upper layer, which cross-sections are schematically depicted in FIG. 2b. In fact, these cross-sections are projections on an xy plane (or are projected on an xy-plane). Note that each projection is essential identical. Further, note that in fact it is assumed that for these embodiments the layers are essentially on top of each other and are not curved.

[0098] FIG. 3a schematically depicts an embodiment of a stack of three layers being 3D printed, with on the left a single layer, in the middle a further layer on the first single layer, and on the right yet a further layer on the further layer on the first single layer. Cross-sections in an xz-plane are schematically depicted in FIG. 3b. To discriminate between layers, the indices ′, ″, and ′″ are applied. FIG. 3a is a top view, but can basically also be used as projection on the xy-plane of at the first layer (left embodiments) and at least the upper layer (middle and right embodiment).

[0099] FIGS. 3a-3b schematically depict a method for producing a 3D item 1 by means of fused deposition modelling. The method comprising a 3D printing stage comprising layer-wise depositing 3D printable material 201 to provide the 3D item 1 comprising 3D printed material 202. The 3D item 1 comprises a plurality of layers 322 of 3D printed material 202. Especially, the plurality of layers 322 comprises a stack 1300 of a first layer 1322 and a second layer 2322, which are configured adjacent to each other. Especially, the method comprises 3D printing the first layer 1322 and subsequently the second layer 2322 along respective print paths 323 while providing one or more print path deviations 340 in an xy-plane in at least one of the first and second layers 1322,2322 relative the (respective) the print path 323. Thereby, one or more openings 354 between the first and second layers 1322,2322 are defined.

[0100] As schematically depicted, the layers 322 have a layer width W. The one or more print path deviations 340 have an amplitude D (especially relative to the (respective) print path 323). In specific embodiments W≤D≤10*W, even more especially W<D≤10*W. Further, in specific embodiments, the one or more deviations have deviation widths W1 at half amplitudes D, wherein especially 0.1*W≤W1≤20*W.

[0101] In embodiments, the method comprises a continuous 3D printing of the at least one of the first and second layers 1322,2322 with the one or more print path deviations 340.

[0102] In this way, a 3D item 1 is provided, comprising 3D printed material 202. The 3D item 1 comprises a plurality of layers 322 of 3D printed material 202. The plurality of layers 322 comprises a stack 1300 of a first layer 1322 and a second layer 2322, which are configured adjacent to each other. Relative to a projection on an xy-plane of the first and second layers 1322,2322 at least one of the first and second layers 1322,2322 defines one or more layer deviations 1340 protruding relative to the other of the first and second layers 1322,2322. In this way, one or more openings 354 between the first and second layers 1322,2322 are defined. As indicated above, the layers 322 have a layer width W. Further, the at least one of the first and second layers 1322,2322 defining one or more layer deviations 1340 comprises a stack axis SA in the projection on the xy-plane. Especially, the one or more deviations 1340 have an amplitude D relative to the stack axis SA in the projection on the xy-plane SA. In specific embodiments W≤D≤10*W, even more especially W<D≤10*W.

[0103] FIG. 3c schematically depicts a stack 1300 in cross-sectional view comprising a plurality of layers 322 and a plurality of openings 354. Reference 355 indicates channel, which are provided between the two opposite sides of the 3D item 1 or of the stack 1300. FIG. 3c thus also schematically depicts an embodiment of the 3D item 1 comprising an item wall 350, wherein the item wall 350 comprises the plurality of layers 322 of 3D printed material 202, wherein the item wall 350 comprises a plurality of openings 354 between both sides of the item wall 350, wherein the plurality of openings 354 are at least partly defined by a plurality of layer deviations 1340.

[0104] Hence, amongst others in embodiments a method is suggested herein for giving to the surface of the printed item a fabric/knitwear appearance. For this purpose, it is suggested using printing strategies where the printer head moves continuously without stopping along a smooth line while oscillating in the print plane (xy) about the line. When the oscillations in successive layers are chosen to be out of phase then the successive layers contact each other only at crossing points this. This leads to a relatively open structure as shown in FIG. 4a with loops on both surfaces. However, oscillations may in embodiments not be symmetrical and oscillations may in embodiments only be from one side then loops are formed only on one of the surfaces while the other surface looks porous, such as a schematically depicted embodiment in FIG. 4b (see further below).

[0105] FIGS. 4a-4b also schematically depicts embodiments of methods comprising 3D printing at least one of the first and second layers 1322,2322 with a plurality of deviations 340, wherein (i) two or more of the print path deviations 340 are configured symmetrical relative to the (respective) print path 323, and/or (ii) two or more of the print path deviations 340 are configured asymmetrical relative to the (respective) print path 323. Further, FIGS. 4a-4b also schematically depicts embodiments of methods comprising 3D printing at least one of the first and second layers 1322,2322 with a plurality of print path deviations 340 in one or more of a block-shape way, in a zig-zag way, and in a meandering way. Yet further, FIGS. 4a-4b also schematically depicts embodiments of methods wherein the layers 322 have a layer width W, wherein the method comprises 3D printing at least one of the first and second layers 1322,2322 with a plurality of print path deviations 340 having a first pitch P1, and wherein 2*W≤P1≤20*W. In the figures, the indications ′ and ″ are used to distinguish between two pitches (which do not necessarily have different values).

[0106] FIGS. 4a-4b also schematically depicts embodiments of methods comprising 3D printing two or more layers 322 each with a plurality of print path deviations 340, wherein the print path deviations 340 of at least two of the two or more layers 322 are shifted relative to each other.

[0107] FIG. 4c shows a front view (I) and back side view (II) of an embodiment wherein alternating layers comprise the deviations 340.

[0108] Hence, FIGS. 4a-4c (also) schematically depicts embodiments of methods comprising 3D printing two or more layers 322 each with a plurality of print path deviations 340, wherein the layers have a layer height H, wherein for a set of two layers 322, which are nearest neighboring layers 322 of each other, each with the plurality of print path deviations 340, applies one or more of: (i) the deviations of both of the layers 322 have a same first pitch P1, but the print path deviations 340 of the layers 322 are shifted relative to each other, and (ii) nearest neighboring print path deviations 340 in different layers 322 of the set of two layers 322 have a mutual distance d1 of at least the layer height H.

[0109] FIG. 4c may e.g. be the result when the layer height is almost the same as the diameter of nozzle a porous structure is obtained.

[0110] In specific embodiments, the amplitude of the oscillation A is large enough to produce loops but not too large to give the surface an untidy appearance. In yet more specific embodiments, the width (W) of the printed layer may especially satisfy the following condition W<A<3 W. Such a way of printing can lead to a perforated structure as the loops can lead to the formation of holes. Size of the holes can also be altered by adjusting the printing strategy.

[0111] Note that in the embodiments schematically depicted in FIGS. 4a-4c the stack axes may essentially provide a planar plane. Hence, an essentially flat wall element may be provided with opening due to the presence of deviations which extend from the planar plane.

[0112] FIG. 4c and FIG. 5 schematically depict embodiments of methods wherein the 3D item 1 comprises an item wall 350, wherein the item wall 350 comprises the plurality of layers 322 of 3D printed material 202, wherein the method comprises providing a plurality of layers 322 with a plurality of print path deviations 340 in a regular arrangement to provide a regular arrangement of openings 354 between both sides of the item wall 350. Hence, amongst others embodiments are depicted wherein the layers have a layer height H, wherein for a set of two layers 322 each with the plurality of layer deviations 1340 which are nearest neighboring layers 322 of each other applies one or more of: i the layer deviations 1340 of both of the layers have a same first pitch P1, but the layer deviations 1340 of the layers 322 are shifted relative to each other, and ii nearest neighboring layer deviations 1340 in different layers of the set of two layers 322 have a mutual distance d1 of at least the layer height H.

[0113] FIG. 5 schematically depicts an embodiment showing the frontside of such a print with loops sagging downwards. It can be seen that both surfaces are quite porous. In order to reduce the porosity, the layer height is set to be less than half the diameter of the printer nozzle. Furthermore, several layers including a straight layer are printed on top of each other before the structure is shifted. This leads to the squeezing of the layers on top of each other while the loops free to have the diameter of the nozzle. This is schematically shown in FIG. 4c where the layer thickness was assumed to be about the same as the radius of the nozzle.

[0114] FIG. 6 schematically depicts an embodiment of a lamp or luminaire, indicated with reference 2, which comprises a light source 10 for generating light 11. The lamp may comprise a housing or shade or another element, which may comprise or be the 3D printed item 1 (of which several embodiments are described above). Here, the half sphere (in cross-sectional view) schematically indicates a housing or shade. The lamp or luminaire may be or may comprise a lighting device (which comprises the light source 10). Therefore, the term lighting device may refer to a lamp or a luminaire, and may thus be indicated with reference 2. Hence, in specific embodiments the lighting device comprises the 3D item 1. The 3D item 1 may be configured as one or more of (i) at least part of a lighting device housing, (ii) at least part of a wall of a lighting chamber, and (iii) an optical element. Hence, the 3D item may in embodiments be reflective for light source light 11 and/or transmissive for light source light 11. Here, the 3D item may e.g. be a housing or shade. The housing or shade comprises the item part 400. For possible embodiments of the item part 400, see also above. FIG. 6 schematically depict several embodiments, wherein in the first embodiment I, the transmissivity of the 3D item 1 is relatively small, and in the other embodiments II and III, the transmissivity is larger.

[0115] In embodiments, the 3D item may comprise alternating printed levels, wherein the first 3D printed level comprises surface loops, and the second 3D printed level comprises no 3D printed loops (i.e. a spacing). In embodiments, the 3D item may comprise alternating printed levels, wherein the first 3D printed level comprises surface loops, and the second 3D printed level comprises 3D printed loops (i.e. a spacing). In embodiments, the 3D item may comprise at least 10 surface loops per 3D printed level, more especially at least 13, most preferably at least 15.

[0116] In embodiments, the 3D item may comprise a regular pitch per 3D printed level. In embodiments, the 3D item may comprise a regular pitch for at least 10 3D printed levels, more preferably at least 13, most preferably at least 15.

[0117] In embodiments, the 3D item may comprise a first 3D printed level comprising surface loops having a first pitch, and a second 3D printed level comprising surface loops having a second pitch different from the first pitch.

[0118] In embodiments, the 3D item may comprise, the surface loops may be configured in phase. In other embodiments, the surface loops may be out of phase, but preferably shifted by ½ pitch

[0119] In embodiments, the 3D item may comprise a first 3D printed level comprising a first material, and a second 3D printed level comprising a second material different from the first material.

[0120] In embodiments, the 3D item may comprise a first 3D printed level comprising a first color, and a second 3D printed level comprising a second color different from the first color.

[0121] In embodiments, the pitch P may be preferably W<P<3 W, more especially 1.2 W<P<2.7 W, most especially 1.5 W<P<2.5 W such as for example P=2.

[0122] In embodiments, the 3D item may comprise at least 1 layer of 4 neighboring layers comprising surface loops, more especially at least 2 layer of 4 neighboring layers comprises surface loops, such as in specific embodiments at least 3 layer of 4 neighboring layers comprises surface loops, such as for example 4 neighboring layers comprises surface loops.

[0123] In embodiments, at least two layers may comprise surface loops having different shape, and/or a different width, and/or a different amplitude.

[0124] The term “plurality” refers to two or more.

[0125] The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

[0126] The term “comprise” includes also embodiments wherein the term “comprises” means “consists of”.

[0127] The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term “comprising” may in an embodiment refer to “consisting of” but may in another embodiment also refer to “containing at least the defined species and optionally one or more other species”.

[0128] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0129] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0130] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0131] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0132] Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0133] The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0134] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0135] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0136] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

[0137] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

[0138] It goes without saying that one or more of the first (printable or printed) material and second (printable or printed) material may contain fillers such as glass and fibers which do not have (to have) influence on the on T.sub.g or T.sub.m of the material(s).

[0139] Amongst others, the invention provides in embodiments a method wherein 3D printed layers are stacked, but wherein at one or more positions one layer is shifted sideways relative to the other. It may look like a (small) excursion. Hence, the one layer deviates sideways from the layer below and returns back on the layer below. This may be over a relatively small length. The excursion is chosen such, that there is an opening between the lower layer and the layer that deviates sideways. In this way, a 3D printed item comprising a stack of layers may have (physical) openings, which allow transmission of light. In general, the layer height of the layers is not adapted. The deviations or excursions may be provided in a regular way. This may provide a 3D printed with a regular arrangement of openings. Note that not each layer of the 3D printed item necessarily includes such deviations or excursions.