An optical curing or selective laser sintering 3D printing apparatus comprising a hybrid illumination system of a certain wavelength, variable power and speed, and an optical coupling and magnification system

Abstract

, The present invention relates to an apparatus for 3D printing an object by means of photocuring or selective laser sintering with a hybrid illumination system of a constant wavelength, variable power and speed, said apparatus comprising: · A first light source for emitting and processing a first light beam for photocuring or sintering said object, and associated optical means for adjusting the light beam, said first light beam having linearly polarized light oriented according to a predetermined wavelength and a specific angle, a first light source, and associated optical means for adjusting the light beam; · A second light source for emitting and processing a second light beam for photocuring or sintering said object, and associated optical means for adjusting the light beam, said second light beam having the same wavelength as said first light beam and having linearly polarized light oriented according to an angle orthogonal to said first light beam, a second light source, and associated optical means for adjusting the light beam; · A polarizer arranged along the paths of said first light beam and said second light beam, said polarizer being adapted to polarization-couple said first light beam and said second light beam to obtain their spatial overlap (coaxiality) while maintaining the same wavelength, a polarizer; and comprising At least one of said light sources has variable power and is associated with deflection means for the associated light beam, said deflection means having variable speed, and said power and said speed of said deflection means are controlled by prediction software as a function of the time required for photocuring or sintering and the time required to give the same energy density to each part of said object, and between said polarizer and said object, there is arranged an adjustment, magnification and / or focusing optical group 8 adapted to the adjustment, combined magnification and / or focusing of said first light beam and said second light beam polarized and coupled to each other.

Description

Technical Field

[0001] The present invention relates to a hybrid lighting system with a certain wavelength, variable power and speed, and an optical coupling and magnification system, in particular an optical pre- or post-coupling and fixed or variable post-magnification system, for a 3D printing apparatus for photocuring or selective laser sintering.

[0002] The present invention relates to the field of three-dimensional printing, generally referred to as 3D printing, in particular 3D printing technology by photocuring or selective laser sintering (SLS), both of which refer to the formation of an object, in particular the former by curing a specific type of polymer by exposure to light radiation, and this term means not only radiation included in the visible spectrum, but also that in the UV region (radiation belonging to this range of the electromagnetic spectrum is denoted by the abbreviation UV-Vis), and in either case it is capable of curing the liquid polymer used, and the latter is by melting small particles of polymer powder by a high-power laser.

Background Art

[0003] For the sake of simplicity of explanation, hereinafter particular reference will be made to photocuring 3D printing technology, but it is clear that the solution proposed according to the present invention can be similarly applied to selective laser sintering without requiring adaptation beyond the common general knowledge of those skilled in the art.

[0004] The field of photocurable 3D printing technology is known to include two basic technologies. In stereolithography (also called SLA, an acronym for StereoLithography Apparatus), a laser emitting at approximately 400 nm is used to solidify a liquid photocurable polymer in a suitable tank by the emitted light rays. According to DLP printing (an acronym for Digital Light Processing in English), a photocurable polymer (or photocurable liquid resin) that is always in a liquid state in the tank is exposed to light radiation emitted from a device similar to a projector. A variant of DLP printing consists of printing obtained by irradiation from a liquid crystal light source, and the English acronym LCD (an acronym for Liquid Crystal Display) is commonly used.

[0005] According to these technologies, the printing process proceeds by successively creating layers or solidifying the first layer attached to the support plate, then attaching the second layer to the first layer and continuing this until a complete object is formed. Therefore, according to this technology, the data representing the three-dimensional object to be created is organized as a series of two-dimensional layers representing the cross-sections of the object.

[0006] Depending on whether the light radiation comes from above or below the tank, the support plate moves gradually from top to bottom, and the printing process is defined as a top-down type, or moves gradually from bottom to top, and the printing process is defined as a bottom-up type.

[0007] In particular, in the bottom-up process applied to SLA and DLP type machines, as well as LCD type machines, the object extraction plate moves from bottom to top, tilting layer by layer.

[0008] Essentially, the process of forming a three-dimensional object is · The software divides the 3D model provided as the input for printing into regular continuous layers, usually 50 to 200 microns thick, but in any case discrete and a finite number of layers in succession, depending on the technology employed, the opacity of the polymer, the amount of catalyst, the degree of accuracy to be achieved, and the characteristics of the machine provided. · The support plate, also called the extraction plate, is composed of a material that can facilitate the adhesion of the first layer of the polymer, moves up to a predetermined distance from the first layer, waits for the first layer to solidify by a light beam (SLA or DLP / LCD), then rises by a distance sufficient for the formed layer to peel off from the bottom of the tank (usually about 1 mm), then descends again by the same distance minus the distance set for the formation of the second layer, and repeats this until the entire object is formed. It is configured as follows.

[0009] The resulting back-and-forth movement is also called tilting movement and mainly has two purposes: to separate the newly formed layer from the bottom of the tank and at the same time insert a new amount of unpolymerized liquid resin between the newly formed layer and the bottom of the container to update the still liquid material under the already solidified layer so that the next layer can be cured and formed.

[0010] The top-down process proceeds in a similar manner. The support plate is initially near the surface of the liquid contained in the tank, where the light beam solidifies the first layer, and then descends by a sufficient distance so that the newly formed layer is placed at a predetermined distance for forming the second layer, and repeats this until the entire object is formed. In the top-down process, there is no need to remove the just-formed layer from the bottom of the tank, but there is a limitation that the overall height of the printed object is restricted by the depth of the tank.

[0011] Furthermore, as is well known, the mechanical behavior of printed objects varies depending on different light sources such as lasers, DLP, LCD, etc. In particular, different curing methods for a single layer result in a variety of physical / chemical / mechanical behaviors in the three spatial dimensions of XYZ of the printed object, accompanied by a spatial variety of chemical bonds formed.

[0012] Therefore, except for printing by a continuous DLP system as described in, for example, WO2017056124, it is not possible to obtain mechanically and physically isotropic objects with other printing methods.

[0013] First of all, on average, considering that when the proportion of chemical bonds converting liquid monomers to solid polymers is 75 - 85%, the formed object is considered to be "cured" and thus can maintain the desired shape. Therefore, the formed object needs to undergo further post-curing treatment after washing to achieve final chemical and mechanical stabilization (about 99% of the bonds).

[0014] Regarding the anisotropic properties of the objects obtained by photocurable 3D printing, the considerations vary depending on whether the light source used is a laser, DLP, or LCD.

[0015] In particular, to form a single layer, a process is advanced by using a laser to cure a single layer, drawing the cross-section of the object to be formed line by line, accurately aiming the laser like a pencil, and creating a vector path to fill the required areas at a predetermined density as needed.

[0016] Using this type of technology, it is obvious that the curing is not uniform because a limited number of lines are covered, further arranged to form a grid while overlapping at intersections, and the polymerization does not occur instantaneously, so the chemical chains are not uniformly connected in any direction.

[0017] Unlike lasers, in an LCD system, the entire layer being formed can be polymerized simultaneously. Therefore, if the LCD system is associated with a continuous printing process for a single layer, it should be possible to create an isotropic object. However, due to the inherent technical limitations of the liquid crystal matrix (liquid crystal display), even in this case, the resulting object is not isotropic. In fact, using LCD technology, a kind of non-bright area is generated between one pixel and the next, which corresponds to a grid of conductive filaments that can excite each single pixel and then turn it off or on. The same shadow generates non-uniform illumination and thus non-uniform polymerization, and in fact, an isotropic object cannot be created in any direction. Furthermore, the LCD system is affected by a phenomenon called aliasing, which generates defects on the outer surface of the printed object, and this will be explained in detail later.

[0018] Finally, DLP technology uses a completely different method to generate an image. The light beam is incident on a chip of micromirrors that tilt at 0 degrees and approximately 20 degrees respectively towards or away from the light beam source, and reflect the image into the optical tube one pixel at a time. When a scattering phenomenon (diffusion) occurs at the boundaries between the mirrors, the projection becomes effectively uniform, and this is the reason why DLP technology is currently used to generate mechanically isotropic three-dimensional objects.

[0019] In particular, when this light source is associated with a continuous printing process, consistent operation in three spatial dimensions can be achieved. However, even this type of printing system is affected by the aliasing phenomenon described below.

[0020] The aliasing phenomenon lies in the fact that an object generated by a digital system is represented by multiple minimum units. The smaller the unit, the higher the resolution. It is recognized on the surface of the object, and the smoothness of the surface itself is impaired. This phenomenon is also known in the field of 2D digital printing (and more generally, the 2D digital replication of text or images). The corresponding minimum unit is called a pixel, and the printing resolution depends on the pixel size. A contour of the same size as the pixel size (i.e., an approximation of the outline of the image) is generated.

[0021] When using a laser system, as described above, these objects are by definition anisotropic (from the perspective of mechanical operation). During manufacturing, they are very slow and vary temporally not only depending on the height of the object but also on the amount of objects printed simultaneously with the same machine. However, in terms of the quality of the generated surface, the creation of the object is particularly accurate.

[0022] In DLP and LCD type projection systems, the entire layer of the object to be printed can be instantaneously cured, thus improving mechanical performance, speed, and temporal invariance. However, they are characterized by an XY resolution of the printed object that is equal to the dimensions of the pixels actually projected. In particular, in a DLP system, the longer the projection distance (i.e., the printing area), the larger the size of the projected pixels, and as a result, the lower the resolution of the printed object.

[0023] Although it has only recently been recognized as being related to the aliasing phenomenon, previously it was not felt because the essential inaccuracy of 3D printing systems did not allow achieving a polymerization resolution high enough to display this phenomenon on the surface. On the contrary, the aliasing phenomenon has emerged thanks to the high technological and chemical accuracy achieved in the latest photocuring 3D printing systems and the extremely high accuracy of the process characteristics.

[0024] To solve the aliasing problem, according to US2017 / 326786, a method and a stereolithography 3D printing apparatus have been proposed. This apparatus includes a control platform that can represent the object to be printed as a series of layers and subdivide each layer into a main area and an outline filling area, a processing unit of a digital light source that can emit a first light beam used for the corresponding main area of the layer during the printing stage of the object to be 3D printed under the control of the control platform, and a laser marking unit that can emit a second light beam used for the corresponding filling area of the layer outline during the printing stage of the object to be 3D printed under the control of the control platform. Therefore, the solution proposed in US2017 / 326786 can not only perform stereolithography 3D printing of an object at high speed, but also avoid edge distortion caused by the aliasing phenomenon, and thus can improve the accuracy of 3D printing on the surface of the object. However, in the solution proposed in US2017 / 326786, the main area and the filling area of the outline of each layer are exposed to two different light emissions, and no preventive measures have been taken in this regard. As a result, the two areas have different mechanical properties, and tension may occur inside the final object.

[0025] A solution to address all these aspects has been proposed in document WO2021 / 166005. It uses a hybrid type photo-curing radiation light source, combining a DLP type light source with a defined wavelength and a laser light source with the same wavelength, equipped with a galvanometric head that can change the power of the radiation beam and operate at a variable speed. In this way, on the one hand, there is no limitation due to the aliasing phenomenon, and on the other hand, there is no reduction in resolution. The two light sources are managed by a predictive type hybrid software CAD-CAM / slicer that can calculate the perimeter of the layer to be cured and then set the power and speed of the laser light source. Therefore, it proposes an isotropic type printing process that integrates the advantages of DLP technology and laser technology and enables continuous printing.

[0026] The solution according to WO2021 / 166005 is based on the concept that a hybrid software, on the one hand a slicer type for generating monochromatic images for DLP and on the other hand a vector type for generating laser paths related to the lateral edges of a single layer and evaluating the perimeter length for curing each single layer, can define the speed and output of the laser for each single layer, thereby ensuring the same time and the same energy density supplied by the DLP light source for curing the internal part of the layer, thus · polymerizing the entire layer simultaneously, · ensuring isotropic polymerization, · ensuring continuous printing using a laser, · solving the problem of the aliasing effect, · making the XY resolution independent of the size of the printing area, becomes possible.

[0027] In particular, according to the content described in WO2021 / 166005, the DLP light source has linearly polarized light oriented according to a specific angle, i.e., is associated with a polarizer configured to transmit only a portion of the radiation having linearly polarized light oriented according to a specific angle, the laser light source has linearly polarized light oriented according to an angle orthogonal to the angle of the DLP light source, i.e., is associated with a polarizer configured to transmit only a portion of the radiation having linearly polarized light oriented according to an angle orthogonal to the angle of the DLP light source, the laser light source has a variable radiant flux power and is equipped with laser deflection means with variable speed, and the radiant flux power and the speed of the deflection means are controlled by prediction software as a function of the time required to photocure each layer by the DLP light source.

[0028] Referring to FIGS. 1 and 2 (relating to bottom-up and top-down photopolymerization 3D printing apparatuses respectively fabricated in accordance with the content described in WO2021 / 166005), they show elements of an isotropic type stereolithography 3D printing apparatus with a variable speed and variable power hybrid light source according to the known art. The apparatus basically comprises a tank 1 (which can be regarded as a consumable) suitable for containing a photocurable liquid material, and a monochromatic DLP light source suitable for curing the inside of each layer of the object under construction, having an energy density and residence time specific to various resins and layer thicknesses. This DLP light source comprises a DLP chipset 2 for projecting an image by processing light from an LED or lamp-type light source 3, and a coupling optical system 4 inserted between the DLP chipset 2 and the light source 3. And the apparatus basically comprises a monochromatic laser light source 5 equipped with a variable output diode, a laser beam expander 6 (also hereinafter referred to as a beam expander 6), and a device adapted to deflect two-dimensionally the laser beam generated by the monochromatic laser light source 5 and expanded by the beam expander 6, in particular, a variable speed galvanometric head 7 appropriately calibrated to cure only the contour of each single layer at the same output density and timing as the DLP light source. Also, in order to obtain an isotropic object, the DLP monochromatic light source and the monochromatic laser light source need to have the same wavelength, i.e., the same energy. The DLP monochromatic light source is also equipped with an enlargement and focusing optical group 8 adapted to enlarge the width of the projection and realize the maximum effective area at the minimum possible projection distance. The apparatus also comprises a support plate 9 adapted to accommodate the overlapping layers forming the printed object, which is obtained by photocuring the photocurable liquid material by the radiation from the two light sources, on the surface facing the light source. Further, referring to FIG. 1 relating to the bottom-up photopolymerization 3D printing apparatus, the bottom of the tank 1 is transparent to the radiation of both light sources.

[0029] The feature of the photopolymerization 3D printing apparatus according to WO2021 / 166005 is that, regardless of whether it is a bottom-up type or a top-down type, there is a polarization coupling optical system 10, also called a polarizer 10, and its function is to polarization-couple light rays from two light sources to obtain the spatial overlap (coaxiality) of the two light rays while maintaining the same wavelength. Assuming that the polarization states of the two light rays can be identified (or decomposed) along two directions that are orthogonal to each other and orthogonal to their respective propagation directions, according to WO2021 / 166005, By using the polarization coupling optical system 10 (polarization beam combiner 10), one of the aforementioned polarization states (typically the so-called "p" polarization) can be transmitted, and the state orthogonal to it (typically the so-called "s" polarization) can be reflected. One of the light sources has linearly polarized light oriented at a specific angle, and the other has orthogonally linearly polarized light. Therefore, the polarization of the light ray of one of the light sources is perpendicular (s polarization) to the incident surface of the coupling optical system, and the light ray is reflected, while the polarization of the light ray of the other light source is parallel (p polarization) to the same surface, and the light ray is transmitted. In the printing apparatus shown in FIGS. 1 and 2, the polarization of the light ray 11 from the DLP light source is parallel to the incident surface of the coupling optical system 10 and is transmitted, and the polarization of the light ray 12 from the laser light source is perpendicular to the incident surface of the coupling optical system 10 and is reflected. Through polarization coupling, the two light rays maintain the same wavelength while overlapping spatially.

[0030] The polarization directions of the two light rays shown in FIGS. 1 and 2 are merely illustrative. Similarly, for the purpose of spatially overlapping the light rays from the two light sources, by reversing the positions of the DLP light source and the laser light source with respect to the coupling optical system, the basic condition of having orthogonally linearly polarized light is also guaranteed.

[0031] Typically, the DLP-type light source used in this application emits linearly polarized light rays or randomly polarized light rays according to the first determined direction, while the laser-type light source is a laser diode that emits linearly polarized light rays according to the second determined direction. To obtain the spatial overlap of the two light rays of the laser and DLP, one must be directed perpendicular (s-polarized) to the incident surface and the other parallel (p-polarized) to it, and enter the polarization optical system with linear polarization. If the polarization axis of one or both light rays is not straight or is not oriented according to this definition, an optical system called a "polarizer" can always be used to correct their orientation.

[0032] The solution described in WO2021 / 166005 has application limitations related to the scalability of the printing area (XY). This limitation is due to the allowable angle of the polarizer, i.e., the maximum allowable deviation from the designed incident angle at which the polarizer continues to operate within the specifications.

[0033] In this regard, it is known that commercially available polarizers can be classified into planar polarizers and cube polarizers. Both of these configurations have inherent structural limitations on the incident angles of transmitted light rays (in the stereolithography 3D printing system described in WO2021 / 166005, those from the DLP light source) and reflected light rays, which are included in the range of + / - 7° unless further restricted. When the angle of the transmitted light ray and / or the reflected light ray exceeds this limit, the polarizer loses its effectiveness and cannot transmit / reflect the incident light, losing the function of this device described in WO2021 / 166005, i.e., beyond this angle, coaxial light rays useful for hybrid polymerization cannot be reproduced. It is also known that there are other forms of polarization optical elements in the market, which operate based on a special surface nanostructure called a wire grid and can significantly expand the acceptance angle of light rays. However, when these elements are used for the output to standard DLP and laser optical systems, their dimensions are very large and the cost is very high, making them unusable.

[0034] Referring to FIGS. 1 and 2, the image generated by the DLP magnification and focusing optical block 8 has portions at angles exceeding 14° (+ / -7°) indicated by reference numeral 13, and thus it is filtered by the polarizer, resulting in the loss of the effective area. Usually, for DLP systems for additional applications, the projection angle actually greatly exceeds 30° (+ / -15°) in order to shorten the projection distance and increase the effective printing area.

[0035] This is an essential limitation of stereolithography 3D printing technology with hybrid illumination and a severe limitation for market development. In fact, the scalability of a stereolithography 3D printing system with a hybrid illumination system that can maintain extreme resolution in a large printing area is severely limited by the maximum allowable angle of the polarizer. Currently, the only way to overcome this problem is to increase the distance between the light source and the polymerization region. On the other hand, this solution · results in a significant loss of power by the DLP light source due to the increase in distance and the loss of the entire active area, and · an unacceptable increase in the size of the 3D printer to be constructed, and is not feasible for these two reasons.

[0036] Therefore, in this particular field, there is a need for a photo-curing or selective laser sintering 3D printing apparatus with a hybrid illumination system of a certain wavelength, variable power and speed, and an optical coupling and magnification system, whose scalability is not limited by the maximum allowable angle of the polarizer and whose overall size is maintained compact.

[0037] This need is met by the photo-curing or selective laser sintering 3D printing apparatus according to the present invention, which also provides further advantages to be described below, with a hybrid illumination system of a certain wavelength, variable power and speed, and an optical coupling and magnification system, particularly an optical pre- or post-coupling and fixed or variable post-magnification system.

Summary of the Invention

[0038] Accordingly, an object of the present invention is to provide a photo-curing or selective laser sintering 3D printing apparatus which includes a hybrid lighting system with a fixed wavelength, variable power, and variable speed, and an optical coupling and magnification system, particularly an optical pre- or post-coupling and fixed or variable post-magnification system, and which overcomes the limitations of stereolithography 3D printing systems equipped with hybrid lighting systems according to known techniques and can achieve the aforementioned technical results.

[0039] A further object of the present invention is that the 3D printing apparatus can be manufactured at a substantially low cost with respect to both manufacturing costs and management costs.

[0040] Finally, but not least, an object of the present invention is to propose a simple, safe, and reliable photo-curing or selective laser sintering 3D printing apparatus which includes a hybrid lighting system with a fixed wavelength, variable power, and variable speed, and an optical coupling and magnification system, particularly an optical pre- or post-coupling and fixed or variable post-magnification system.

[0041] Accordingly, a first specific object of the present invention is a photo-curing or selective laser sintering 3D printing apparatus including a hybrid lighting system with a fixed wavelength, variable power, and variable speed, the apparatus comprising: · a first light source and associated optical devices for emitting and processing a first light beam for photo-curing or sintering an object, the first light beam having linearly polarized light oriented according to a predetermined wavelength and a specific angle, the first light source and associated optical devices for adjusting the light beam; · a second light source and associated optical devices for emitting and processing a second light beam for photo-curing or sintering an object, the second light beam having the same wavelength as the first light beam and having linearly polarized light oriented according to an angle orthogonal to the first light beam, the second light source and associated optical devices for adjusting the light beam; · A polarizer arranged along the paths of the first light beam and the second light beam, the polarizer being adapted to polarization-couple the first light beam and the second light beam to obtain their spatial overlap (coaxiality) while maintaining the same wavelength, the polarizer; comprising At least one of the light sources has variable power and is associated with deflecting means for the associated light beam, the deflecting means having variable speed, and the power and the speed of the deflecting means are controlled by prediction software as a function of the time required for photocuring or sintering and the time required to provide the same energy density to each part of the object, and between the polarizer and the object, there is arranged an adjustment, magnification and / or focusing optical group adapted to the adjustment, combined magnification and / or focusing of the first light beam and the second light beam polarized-coupled to each other.

[0042] Preferably, according to the present invention, the first light source is a DLP type light source, comprising an LED or a lamp type light source, a DLP chipset, and a coupling optical system inserted between the DLP chipset and the light source, and the second light source is a single-color laser light source, comprising a variable output diode, a laser beam expander, and a two-dimensional deflecting device for the laser light beam generated by the single-color laser light source and expanded by the laser beam expander.

[0043] More preferably, according to the present invention, the deflecting device is a variable speed galvanometric head, and an optical system for adapting and optimizing the light beam may be inserted between the first DLP type light source and the polarizer.

[0044] In particular, according to the present invention, the polarizer is adapted to transmit the light beam of the first light source and reflect the light beam of the second light source, or vice versa.

[0045] Alternatively, according to the present invention, the polarizer may be a plane polarizer or a cube polarizer.

[0046] It is also the second specific object of the present invention to use the previously defined 3D printing apparatus in a bottom-up type photopolymerization three-dimensional printing system.

[0047] It is the third specific object of the present invention to use the previously defined 3D printing apparatus in a top-down type photopolymerization three-dimensional printing system.

[0048] Finally, it is the fourth specific object of the present invention to use the previously defined 3D printing apparatus in an SLS laser sintering three-dimensional printing system for polymerization / sintering / melting of plastic powder.

Brief Description of the Drawings

[0049] The present invention will be described, for purposes of illustration and not limitation, in accordance with preferred embodiments, with particular reference to the following accompanying drawings.

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Embodiments for Carrying Out the Invention

[0050] Referring preliminarily to FIGS. 3 - 6, components related to the known technology already described with reference to FIGS. 1 and 2 are denoted by the same reference numerals and will not be described again. However, the first embodiment of the present invention is shown as being applied to bottom - up type (FIGS. 3, 4) and top - down type (FIGS. 5, 6) photopolymerization 3D printing apparatuses each provided with a plane polarizer 10 (FIGS. 3, 5) or a cube polarizer 14 (FIGS. 4, 6).

[0051] In particular, in this first embodiment of the present invention, it is proposed to first arrange a pre - coupling system for two light rays in the paths of two light rays, namely, the path of the light ray 11 of the DLP light source and the path of the light ray 12 of the laser light source, and then arrange an enlarging and focusing optical group 8 for their combination for enlargement. By this solution, the above - mentioned problems caused by the maximum acceptance angle of the polarizer (both the planar type 10 and the cubic type 14) can be completely avoided. In particular, according to the present invention, a polarizer (either the planar type 10 or the cubic type 14 depending on the type of blocked bandwidth) is arranged immediately next to the output of the light ray 11 from the DLP processor, and then, after both light rays are combined, an enlarging and focusing optical group 8 of a size suitable for the printing target area is inserted to enable the enlargement of both optical flows and to enable the optimization of the operating angle, focus, and the size of the printing plate for each type of printer desired to be constructed. The enlarging and focusing optical group 8 is also sized to limit the distortion caused by the optical system in order to reduce the barrel distortion effect which is a characteristic of the DLP system.

[0052] This initially proposed solution relates not only to both bottom-up and top-down photopolymerization 3D printing systems, but also to SLS laser sintering systems for the polymerization / sintering / melting of plastic powders (in this particular case, the infrared band).

[0053] Furthermore, what has been described above can be equally applied to both the case where the light beam 11 of the DLP light source is transmitted by the polarizer and the light beam 12 of the laser light source is reflected, and the reverse case where the light beam 12 of the laser light source is transmitted by the polarizer and the light beam 11 of the DLP light source is reflected. In either case, the stereolithography 3D printing method and apparatus according to the present invention have the same technological development.

[0054] As an example, FIG. 7 shows a bottom-up photopolymerization 3D printing apparatus in which the light beam 11 of the DLP light source is reflected by the polarizer 10 and the light beam 12 of the laser light source is transmitted.

[0055] Referring to FIGS. 8 to 11, the second embodiment of the present invention is shown applied to bottom-up (FIGS. 8 and 9) and top-down (FIGS. 10 and 11) photopolymerization 3D printing apparatuses each provided with a planar polarizer 10 (FIGS. 8 and 10) or a cubic polarizer 14 (FIGS. 9 and 11).

[0056] In particular, according to this second embodiment of the present invention, · the quality of the image projected onto the effective area, · the optimization of aberration, · the optimization of the barrel distortion effect, · the uniform energy density at the interface, and · the optimization of the operating dimensions and acceptance angle of the polarizer, it is an object to further optimize the performance of the printing apparatus in order to achieve maximally optimized characteristics in terms of these aspects.

[0057] For this purpose, according to the present invention, it is proposed to insert an optical system 15 for adapting and optimizing the light beam 11 of the DLP light source immediately after the output of the light beam 11 of the DLP light source and immediately before the coupling system with the polarizer. This configuration, on the one hand, leads to an increase in manufacturing costs, but by correcting the light beam 11 of the DLP light source before coupling with the light beam 12 of the laser light source, especially before the focusing and enlarging system, the quality of the image obtained at the polymerization interface can also be further improved.

[0058] Similar to the first embodiment, the solution of this embodiment can also be adopted at all wavelengths of interest in all photopolymerization 3D printing technologies, such as bottom-up type, top-down type, or those by plastic laser sintering SLS.

[0059] Furthermore, in this case as well, the proposed solution can be equally applied to both the case where the light beam 11 of the DLP light source is transmitted by the polarizer and the light beam 12 of the laser light source is reflected, and the reverse case where the light beam 12 of the laser light source is transmitted by the polarizer and the light beam 11 of the DLP light source is reflected. In either case, the stereolithography 3D printing method and apparatus according to the present invention have the same technological development.

[0060] The present invention has been described for illustrative purposes and not for limiting purposes according to its preferred embodiments, but it should be understood that it may be changed and / or modified by those skilled in the art without departing from the relative scope of protection defined by the appended patent claims.

Claims

1. A 3D printing apparatus for photocuring or selective laser sintering, comprising a hybrid lighting system with a fixed wavelength, variable power, and variable speed, said apparatus comprising: - A first light source and associated optical devices for emitting and processing a first light beam for photocuring or sintering an object, said first light beam having linearly polarized light oriented according to a predetermined wavelength and a specific angle, a first light source, and associated optical devices for adjusting the light beam; - A second light source and associated optical devices for emitting and processing a second light beam for photocuring or sintering an object, said second light beam having the same wavelength as said first light beam and having linearly polarized light oriented at an angle orthogonal to said first light beam, a second light source, and associated optical devices for adjusting the light beam; - A polarizer arranged along the paths of said first light beam and said second light beam, said polarizer being adapted to polarization-couple said first light beam and said second light beam to obtain their spatial overlap (coaxiality) while maintaining the same wavelength; comprising; At least one of said light sources has variable power and is associated with deflecting means for the associated light beam, said deflecting means having variable speed, and said power and said speed of said deflecting means are controlled by prediction software as a function of the time required for photocuring or sintering and the time required to provide the same energy density to each part of said object, and between said polarizer and said object, there is arranged an adjustment, magnification, and / or focusing optical group adapted to the adjustment, combined magnification, and / or focusing of said first light beam and said second light beam polarized-coupled to each other. A 3D printing apparatus characterized by this.

2. Said first light source is a DLP type light source, comprising an LED or lamp type light source (3), a DLP chipset (2), and a coupling optical system (4) inserted between said DLP chipset (2) and said light source (3), and said second light source is a single-color laser light source (5), comprising a variable output diode, a laser beam expander (6), and a two-dimensional deflection device for the laser light beam generated by said single-color laser light source (5) and expanded by said laser beam expander (6). The 3D printing apparatus according to Claim 1, characterized by this.

3. The 3D printing device according to claim 2, characterized in that the deflection device is a variable speed galvanometric head (7).

4. The 3D printing device according to claim 2 or 3, characterized in that an optical system (15) for adapting and optimizing the light beam (11) is inserted between the first DLP type light source and the polarizer (10).

5. The 3D printing device according to any one of claims 1 to 4, characterized in that the polarizer is adapted to transmit the light beam of the first light source and reflect the light beam of the second light source, or vice versa.

6. The 3D printing device according to any one of claims 1 to 5, characterized in that the polarizer is a plane polarizer (10).

7. The 3D printing device according to any one of claims 1 to 5, characterized in that the polarizer is a cube polarizer (14).

8. Use of the 3D printing device according to any one of claims 1 to 7 in a bottom-up type photopolymerization three-dimensional printing system.

9. Use of the 3D printing device according to any one of claims 1 to 7 in a top-down type photopolymerization three-dimensional printing system.

10. Use of the 3D printing device as defined in any one of claims 1 to 7 in a laser sintering SLS three-dimensional printing system for polymerization / sintering / melting of plastic powder.

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