DE102013107570B4 - Method and device for producing a three-dimensional object and exposure mask generating device - Google Patents

Abstract

Method for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28), wherein for forming each object layer (62) of the object (12) to be solidified in a Build level (22) at least one exposure mask (28) is produced, by means of which the radiation (14) is selectively projected into the build level, characterized in that each exposure area, which defines a cross-sectional area of the object, in each exposure mask (28) has a a closed outer contour line (74) is assigned to delimit the exposure area, that the pixels for forming the contour line (74) are assigned the bit value (32) “transparent”, that each exposure area in each exposure mask (28) has an inside on the contour line (74) adjoining dividing line (76) is assigned and that the pixels for forming the dividing line (76) are assigned the bit value (34) "n not permeable” is assigned.

Description

The present invention relates to a method for producing a three-dimensional object by layer-by-layer solidification of a material that can be solidified under the action of radiation using exposure masks, with at least one digital exposure mask being produced in a construction level to form each object layer of the object to be solidified, by means of which the radiation is selectively is projected into the construction level.

Furthermore, the present invention relates to an exposure mask generating device for a device for producing a three-dimensional object by layer-by-layer solidification of a material that can be solidified under the action of radiation using exposure masks, comprising a radiation source for generating the radiation and the exposure mask generating device, which exposure mask generating device for forming each object layer to be solidified of the Object in a building level at least one digital exposure mask generated, by means of which the radiation is selectively projected into the building level.

The present invention also relates to a device for producing a three-dimensional object by layer-by-layer solidification of a material that can be solidified under the action of radiation using exposure masks, comprising a radiation source for generating the radiation and an exposure mask generating device.

Methods and devices of the type described above are known in many ways, for example from DE 199 29 199 A1 . Three-dimensional objects are produced by layer-by-layer curing or fusing of preferably plastics using digital mask exposure, in which the energy input per area is controlled as a function of the locally available light output via the exposure time.

Various problems to be solved arise when producing three-dimensional objects using these methods and devices. In particular, it is important to homogenize a light intensity distribution. Due to an optical system that is used, which in particular comprises a radiation source and projection optics, an inhomogeneous intensity distribution usually results during imaging. However, such an inhomogeneity should be avoided as far as possible, so that the intensity distribution is as homogeneous as possible in a construction projection plane in which the three-dimensional object is created.

Furthermore, it is important to achieve a uniform hardening depth with differently designed cross-sectional areas of the object layers of the object. On the one hand, structures in the object layer with a filigree structure or cross-sectional area are hardened less deeply than structures with a large-area cross-sectional area. In addition, so-called blooming can occur in the contour area of the object layer. In particular, this can result in small cavities in more massive structures not being formed at all by overblasting contours of the same, since the material in the contour area hardens into the hollow space to be formed due to overblasting. And finally, the so-called green body hardness is often not sufficient when manufacturing the three-dimensional object. This means in particular that in the case of particularly filigree (support) structures, only a slight hardening can occur during the production of the object, so that these filigree structures often tear off. It can also happen that the critical energy for hardening is not reached in the case of very filigree structures, and the filigree structures are therefore not produced. In the case of solid components, it may be desirable to overexpose the interior during the construction process in order to achieve greater green body hardness in the component, since the radiation during the post-exposure process only has a low penetration depth, especially with opaque materials.

In particular, in order to achieve a more uniform depth of hardening with differently designed cross-sectional areas, it is known from the prior art to control the gray value of the individual pixels of the masks or through multiple exposure by using several masks for a single object layer, a controlled, pixel-precise hardening of the object or to achieve the object layers forming these. On the one mentioned at the beginning DE 199 29 199 A1 for gray value control and the EP 1 849 586 A1 reference is made to multiple exposures. A particular disadvantage of the gray value control is that due to the destruction/reduction of radiation intensity, a longer exposure time per exposure cycle of an object layer is always required in order to achieve the required energy input per object layer. The reason for this is in particular that an energy input is always based on the lowest intensity values in the image for optimization purposes. With multiple exposure, multiple masks must be provided and exposed one after the other. This procedure also results in a lengthening of the exposure time.

And finally, it is desirable that the three-dimensional object has the highest possible surface quality and that the dimensions of the object are maintained as precisely as possible.

It is therefore an object of the present invention to improve a method and a device as well as an exposure mask generating device of the type described at the outset in such a way that three-dimensional objects of high quality can be produced in a simple manner.

In a method of the type described above, this object is achieved according to the invention in that each exposure area, which defines a cross-sectional area of the object, is assigned a self-contained outer contour line for delimiting the exposure area in each exposure mask, that the pixels for forming the contour line of the bit -value "transparent" is assigned, that each exposure mask is assigned a dividing line bordering on the inside of the contour line, and that the pixels for forming the dividing line are assigned the bit value "non-transparent".

In particular, it can be advantageous if the object layer to be formed, defined by the exposure area, has at least one recess, if a self-contained inner contour line for delimiting the object layer is defined around the at least one recess, if the pixels for forming this contour line of the bit The value "permeable" is assigned if a dividing line is defined directly adjacent to this contour line and if the bit value "non-permeable" is assigned to the pixels to form the dividing line. In both cases, a quasi intensity swath is formed, specifically in each case directly adjacent to the contour line to the exposure area, ie to the area of the object layer to be exposed. In particular, this intensity corridor has the effect that as little scattered light as possible shines out over the outer and inner contours, as a result of which the surface quality on the one hand and the dimensional accuracy of the object to be produced can be impaired on the other. Furthermore, it can be advantageous if the respective dividing line is directly adjacent to the inner or outer contour line. In particular, it is advantageous if more than one dividing line is provided. In particular, two, three or more dividing lines can be provided which separate the corresponding number of contour lines from one another. In particular, one of the dividing lines can also border on an edge line, as defined above. In other words, two or three separating lines can also run parallel to one another, which can be separated from one another by a contour line. Optionally, it is also conceivable that one or more separating lines are interrupted, for example by transverse connecting lines that connect the contour line to another contour line or to an edge line of a surface area of the object layer to be exposed. These connecting lines, which preferably run transversely, in particular perpendicularly, to the dividing line, have the advantage that the overall stability of the three-dimensional object can be improved without significantly impairing the advantage of forming the dividing line.

It is advantageous if a single exposure mask is produced in one construction level in order to form each object layer of the object that is to be solidified. In this way, the object can be produced more quickly and easily.

A digital exposure mask is preferably produced in a construction level to form each object layer of the object that is to be solidified. In particular, it is possible to use only two different bit values, for example a first bit value to which the value “permeable” is assigned and a second bit value to which the value “not permeable” is assigned. In this context, “permeable” and non-permeable are not only to be understood literally, but also in such a way that the bit value “permeable” defines a higher radiation intensity in the construction level than the bit value “not permeable”.

It is favorable if the width of the contour line and/or the dividing line is at least 2 pixels. Preferably, the width is in a range of 2 to 8 pixels. A width of the contour line and/or the dividing line is preferably in a range of 2 to 4 pixels. The specified minimum width is particularly suitable for ensuring the advantages of forming a contour line or a dividing line on the one hand and ensuring stability of the three-dimensional object on the other.

Each exposure mask is advantageously assigned a separating line for those surface areas whose feature size has a width and/or length that is at least twice the width of the contour line. In this way it can be ensured in particular that particularly small, filigree structures are not impaired in their stability by the formation of a dividing line.

It is advantageous if a single 2-bit bitmap is calculated for each exposure mask depending on the object layer to be solidified, which assigns each pixel of the exposure mask either the bit value "transparent" or the bit value "not permeable" that at least one area of the 2-bit bitmap with a texture size the bit value "transparent" is assigned below a limit structure size and that an exposure texture is assigned to at least one surface area above the limit structure size, which exposure texture is designed in the form of a pattern of pixels with the bit values "translucent" and "non-transmissive". In particular, this procedure makes it possible to expose an object layer to be produced with just a single exposure mask. In addition, gray value control is basically superfluous, but is still possible as an option. For example, it is possible to provide only a black/white bitmap as the 2-bit bitmap. Of course, it is also conceivable to select the bit values “transparent” with different brightness for each exposure mask. Each bitmap should preferably only have two different intensity values for the transparency of the exposure mask, which are labeled “transparent” and “non-transparent” by way of example. In particular, both bit values can also permit a certain permeability for the radiation, with the permeability of the bit value "transmissive" always being greater than the permeability of the bit value "non-transmissive". Furthermore, the method can also be used in reflective systems, in which case the bit values "transmissive" and "non-transmissive" are to be understood in an analogous manner, i.e. the exposure mask reflects the radiation, for example, or deflects it onto the construction level in the desired manner if the bit value is "transparent" and does not reflect, absorb or deflect the radiation off the build plane when the bit value is "non-transparent". Preferably, exposure textures are used that have regular patterns of pixels with the two available bit values of the 2-bit bitmap. For example, patterns containing chessboard-like, zigzag-shaped lines or stripes can be provided. In particular, it is possible with the at least one exposure mask to selectively control the energy input through the radiation into the solidifiable material in the construction level at the pixel level. Furthermore, it is also possible to assign the bit value “transparent” to each surface area of the 2-bit bitmap with a structure size below a structure size limit and to assign an exposure texture to each surface area above the structure size limit, which exposure texture is in the form of a pattern of pixels with the bit Values "permeable" and "non-permeable" is formed. Overall, the production of a three-dimensional object can take place more easily and with higher quality.

It is favorable if the exposure texture has at most as many pixels with the bit value "non-transparent" as pixels with the bit value "transparent". In this way it can be ensured that essentially a planar structure can be produced. In particular, in the extreme case described, ie when there are as many pixels with the bit value “transmissive” as with the bit value “non-transmissive”, a chessboard-like structure can be formed in which the different pixels are arranged alternately.

Advantageously, each exposure texture has an exposure attenuation value that is greater than 0 and at most 0.5. In this way, an intensity of the radiation in desired areas of the object layer can be attenuated in a desired manner by means of the exposure mask with an exposure attenuation value in the specified range.

It is favorable if at least one surface area with a structure size above the limit structure size is assigned an exposure texture depending on its structure size and if the exposure attenuation value of the exposure texture increases with increasing structure size. In this way it can be achieved, for example, that larger structures in particular can be exposed to a lower average intensity of the radiation than more filigree structures. Due to the transfer function of the optical system, also known as the modulation transfer function ("MTF") - referred to here as "uncertainty" - and the blooming effect in the building plane, a mean value of light intensity is coupled into the material in the building plane over the structure surface. In particular, the dependence function of the exposure texture on the structure size can form a linear function or also a step function. In particular, a step function can define a dependency such that a finite number of discrete surface textures are provided, each associated with a discrete exposure attenuation value. For example, five, ten, 15 and 20 steps, ie n steps, can be provided in order to assign a corresponding exposure attenuation value in the range from 0 to 0.5 to a corresponding number of exposure textures. In particular, it is advantageous if each surface area with a structure size above the limit structure size is assigned an exposure texture depending on its structure size.

In order to increase the stability of the object, it is advantageous if identical exposure textures of exposure masks for exposure of successive object layers are arranged in a plane parallel to the building plane offset by an integer number of pixels relative to one another. Preferably, the identical exposure textures are offset by 1 pixel in an x or y direction of the plane parallel to the build plane. In particular, this variant of the method can be used to ensure that two pixels with the bit value "not permeable" are not lie on top of each other in successive object layers.

It is favorable if different texture patterns are provided for the formation of the exposure textures, which have a ratio of pixels with the bit value “not transparent” and pixels with the bit value “transparent” that is in a range between 0 and 1 . By providing the texture pattern, the surface areas of the object layer that are then defined can be filled directly with the respective texture pattern.

Each exposure texture is preferably in the form of hatching or a regular pattern. In this way, it can also be ensured in particular that two pixels with the bit value “not permeable” do not lie next to each other in the texture.

It is also advantageous if only exposure textures are used in which at most corners of pixels with the bit value “non-transparent” meet, but no longitudinal edges of pixels with the bit value “non-transparent” adjoin one another. In this way it can be avoided that two pixels with the bit value "non-transparent" are directly adjacent to each other, so that the exposure texture does not create larger areas with non-solidified material in the object.

Regular exposure textures can be produced in a particularly simple manner if they can be converted into themselves by a translation in a plane parallel to the building plane. In other words, they can consist in particular of a simple basic pattern comprising a few pixels, which can be arranged regularly by appropriate translation to form the exposure texture.

It is favorable if the translation is defined by a vector which has a length which corresponds to n pixels in an x-direction and m pixels in a y-direction which is not parallel to the x-direction, where n and m are integers. An exposure texture can thus be generated in a simple manner, for example using a mask exposure device. In particular, the x-direction and the y-direction can be oriented perpendicular to one another.

It is advantageous if the exposure texture is screened pixel by pixel. In particular, this is to be understood in such a way that the smallest unit of the exposure texture is a pixel.

In order in particular to achieve a solid, smooth, closed surface of the object, it is advantageous if each exposure area, which defines a cross-sectional area of the object, is assigned a closed edge line in each exposure mask for each outer and inner contour of the exposure area and if the edge line forming pixels are assigned the bit value “transparent”.

So that the stability of the edge line can be formed in an optimal relationship to a width, it is favorable if the width of the edge line is at least 2 pixels. In particular, it is advantageous if the width of the edge line is in a range from 2 to 8 pixels. Preferably, the width of the border line is in a range of 2 to 4 pixels.

Material can be solidified in a simple manner if electromagnetic radiation or particle radiation is used as the radiation. In particular, electromagnetic radiation in the ultraviolet spectral range is advantageously used.

In order to be able to build up the object as quickly as possible, it is advantageous if each exposure mask is assigned an individual exposure time. Depending on the shape and thickness of the object layer to be solidified and the lateral position of the area to be exposed within the construction level, the exposure time can be optimally specified so that exposure only has to be performed until the object layer has the required stability or through-hardening depth.

The method can be implemented particularly easily if the exposure time is identical for all exposure masks. In this way, an individual time control can be dispensed with.

In addition, the construction level can be illuminated in an oscillating manner during an exposure time. This means in particular that an oscillating relative movement is generated between the image in the construction plane and the object to be produced. The advantage of such an oscillating exposure is in particular that the surface of the object to be produced can be smoothed in a simple manner, since corners and steps in the edge area of the exposed object layer are virtually blurred, in contrast to the antialiasing function using gray levels in the contour area. Thus, as for example in the DE 10 2004 022 961 B4 described, no multiple exposure is necessary, but this anti-aliasing can be achieved with a single mask exposure.

It is advantageous if an oscillation range of the exposure in an x and/or a y direction parallel to the building plane is in a range which corresponds at most to a width of a pixel. In other words, it is advantageous if an oscillation in the sub-pixel area is implemented for edge smoothing. It is favorable if the oscillation deviation is a maximum of 0.5 pixels, in particular a maximum of 0.25 pixels.

It is particularly favorable if an oscillation of the exposure in the x and y directions is superimposed during the exposure time to form a circular or essentially circular oscillation. In this way, a complete circular movement can be performed overall, which leads to anti-aliasing in the corresponding sub-pixel area. All corners that are specified by the exposure mask can thus be smoothed with the corresponding radius of the circle defined by the oscillation. In particular, it is favorable if the oscillation is carried out in such a way that, at the end of the exposure time for solidifying a single object layer, integral multiples of a circular oscillation are completed. In this way, a particularly uniform energy input can be achieved in the edge area of the object layer to be formed.

According to a preferred variant of the method according to the invention, it can be provided that a radiation source for generating the radiation and/or the exposure mask and/or imaging optics for imaging the radiation onto the construction plane and/or the object to be produced are moved in an oscillating manner during the exposure time. Depending on the combination of the elements that are moved relative to one another, an oscillating exposure can be achieved in this way.

Oscillating exposure can be implemented in a particularly simple manner if imaging optics with a rotating plane-parallel disk are used, in which the disk is rotated about an axis of rotation that is perpendicular or essentially perpendicular to the construction plane and encloses an angle deviating from 90° with the axis of rotation .

The object set at the outset is also achieved according to the invention with an exposure mask generation device of the type described at the outset in that the exposure mask generation device is designed to assign a self-contained outer contour line for delimiting an exposure area which defines a cross-sectional area of the object and for assigning an inner contour line adjoining the contour line Separating line for each exposure mask, with the bit value “transparent” being assigned to the pixels for forming the contour line and the bit value “non-transparent” being assigned to the pixels for forming the separating line. As already described above, it can also be a closed inner contour line that delimits a recess, ie a region of the object layer to be solidified that is not to be exposed, with the adjoining separating line then surrounding the contour line on the outside. Several such contour lines can also be provided, which are separated from one another by dividing lines. The provision of separating lines has the advantage that it is easy to avoid over-blasting of external and internal contours, which can impair the surface quality of the object layer to be formed and thus of the object as a whole. Of course, each dividing line can also be interrupted by corresponding connecting lines or "connecting webs" which, for example, connect the contour line to the edge line and thus interrupt the dividing line. This can be desirable for reasons of stability, in order to be able to guarantee the cohesion of the object as a whole.

It is advantageous if the exposure mask generation device is designed to generate a single exposure mask. In this way, the object can be produced more quickly and easily.

It is favorable if the exposure mask generation device is designed to generate a digital exposure mask. In particular, it is possible to use only two different bit values, for example a first bit value to which the value “permeable” is assigned and a second bit value to which the value “not permeable” is assigned. In this context, “permeable” and non-permeable are not only to be understood literally, but also in such a way that the bit value “permeable” defines a higher radiation intensity in the construction level than the bit value “not permeable”.

So that the dividing line can bring about the desired effect, it is advantageous if the width of the contour line and/or the dividing line is at least 2 pixels. Conveniently, the width is in a range of 2 to 8 pixels. A width of said lines is preferably in a range of 2 to 4 pixels.

According to a further preferred embodiment of the invention, it can be provided that the exposure mask generating device is designed to assign a separating line to an exposure mask for those surface areas of the same whose structural size has a width and/or length which is at least twice the width of the contour line. In this way it can be ensured that dividing lines only cover areas can be assigned with sufficiently large structure sizes. Adequate curing, in particular of filigree structures, can thus be ensured.

It is favorable if the arithmetic unit is designed to calculate a single bitmap for each exposure mask as a function of the object layer to be solidified. In this way, the production of the object can in particular be implemented more easily and quickly.

The arithmetic unit is preferably designed to calculate a bitmap in the form of a 2-bit bitmap for each exposure mask as a function of the object layer to be solidified. In this way, an exposure mask can be calculated in particular with a minimum of computing effort.

It is also advantageous if the exposure mask generating device comprises a computing unit for calculating a single 2-bit bitmap for each exposure mask depending on the object layer to be solidified, which 2-bit bitmap gives each pixel of the exposure mask either the bit value "transparent" or the bit value "non-transparent", to assign the bit value "transparent" to at least one area of the 2-bit bitmap with a feature size below a threshold feature size and to assign an exposure texture to at least one area above the threshold feature size, which exposure texture in in the form of a pattern of pixels with the bit values “transparent” and “non-transparent”. Such a further developed exposure mask generating device for a device for producing a three-dimensional object by layer-by-layer solidification of a material that can be solidified under the action of radiation using exposure masks makes it possible to form an object layer of the object to be solidified with a single exposure mask in order to reduce the energy input into the material in the construction level depending on the surface structure within a layer or an exposure cycle per layer. In particular, the proposed invention makes it possible to expose the pixels with the bit value “transmissive” to the maximum available radiation intensity required to solidify the material to be solidified in the desired manner. This means in particular that the radiation intensity for pixels with the bit value "transparent" may vary depending on the object layer, but is preferably constant or as constant as the radiation source allows. As already explained above, the bit value "non-transmissive" does not necessarily mean that no radiation is transmitted at all. This is a possible special case. Rather, the "transmissive" and "non-transmissive" bit values represent two distinct transmittance values, with a pixel assigned the bit value "transmissive" transmitting more radiation than a pixel assigned the bit value "non-transmissive". " assigned. The proposed 2-bit bitmap makes it possible to reduce the average radiation input in a surface area with the associated exposure textures.

The arithmetic unit is preferably designed to assign an exposure texture which has at most as many pixels with the bit value “non-transparent” as pixels with the bit value “transparent” in a surface area to be exposed. In this way it can be achieved, in particular with a corresponding arrangement of the pixels, that two or more pixels with the bit value “not permeable” do not lie next to each other for forming the exposure texture, which could reduce the stability of the object to be formed.

It is advantageous if the computing unit is designed to assign an exposure texture that has an exposure attenuation value that is greater than 0 and is a maximum of 0.5. In this way it is possible to correspondingly weaken an average applied radiation intensity for a specific surface area to which the exposure texture is assigned. In particular, this can also serve to compensate for inhomogeneities in the intensity distribution of the radiation generated by the radiation source in a targeted manner for specific surface areas.

It is also advantageous if the computing unit is designed to assign an exposure texture to at least one surface area with a structure size above the limit structure size depending on its structure size, with the exposure attenuation value of the exposure texture increasing as the structure size increases. Designing the computing unit in this way has the advantage that the introduction of radiation into the respective area can be optimized in order to avoid overexposure in particular. The larger the associated, in particular contiguous, surface areas are, the less light intensity is required to achieve a solidification required for the formation of the respective object layer.

According to a further preferred embodiment of the invention, it can be provided that the arithmetic unit is designed to offset the arrangement of identical exposure textures of exposure masks for exposure of successive object layers in a plane parallel to the building plane by an integer number of pixels relative to one another. Preferably the exposure textures are offset relative to each other by 1 pixel in an x- and/or offset in the y-direction of the plane parallel to the building plane. In this way it can be avoided that pixels with the bit value “not permeable” in particular lie directly on top of one another in successive object layers, which could result in a reduction in the stability of the three-dimensional object.

It is advantageous if the exposure mask generating device provides different texture patterns for forming the exposure textures, which have a ratio of pixels with the bit value “non-transparent” and pixels with the bit value “transparent” that is in a range between 0 and 1 lie. If corresponding texture patterns are provided, for example in a memory unit of the computing unit or the exposure mask generation device, a texture does not have to be calculated each time according to the specified pixel ratio, but the correspondingly desired texture pattern can be selected directly and, for example, to fill a surface area of the object layer to be formed to generate the exposure mask be used.

Exposure textures can be stored in a particularly simple manner if the exposure mask generating device provides each exposure texture in the form of hatching or a regular pattern. Such hatching or regular patterns can be traced back to individual basic patterns that are repeated within the pattern, so that the storage space required for this can be minimized and the filling of surface areas can be optimized in terms of time.

It can also be favorable if the processing unit is designed to exclusively use exposure textures in which at most corners of pixels with the bit value “non-transparent” meet, but no longitudinal edges of pixels with the bit value “non-transparent” adjoin one another . In this way it can be avoided that an exposure texture has two directly adjoining pixels with the bit value "not permeable", which could reduce the stability of the three-dimensional object.

The exposure mask generation device can be designed in a particularly simple manner if the exposure mask generation device is designed to provide exposure textures which can be converted into themselves by a translation in a plane parallel to the construction plane. As already explained, individual texture elements, which include a minimum number of pixels, can be stored as a texture pattern and can be used to fill in previously determined surface areas by appropriate translation, as a result of which an exposure mask can be generated in a simple manner.

Preferably, the translation is defined by a vector having a length corresponding to n pixels in an x-direction and m pixels in a y-direction non-parallel to the x-direction, where n and m are integers. For example, an associated vector can be defined and stored for each basic pattern of a texture, with which vector a previously determined area of the exposure mask can be filled with the texture pattern in connection with the basic pattern of the texture.

The exposure mask generating device is expediently designed to provide exposure textures which are screened pixel by pixel. In this way, specific surface areas of the exposure mask can be easily filled with specific exposure textures.

According to a further preferred embodiment of the invention, it can be provided that the exposure mask generating device is designed to assign a closed edge line to each exposure area, which defines a cross-sectional area of the object, each exposure mask having a closed edge line (56) for each outer and inner contour of the exposure area. is assigned and that the pixels forming the border line are assigned the bit value "transparent". Providing such an edge line has the advantage that the surface quality of the component is increased.

In order to generate an edge line with sufficient stability, it is advantageous if the width of the edge line is at least two pixels. The width of the edge line is preferably in a range from 2 to 8 pixels, in particular in a range from 2 to 4 pixels. In particular, even small structures, ie structures with a minimum dimension in a range of only a few pixels, can be provided with a corresponding edge line.

It is advantageous if the exposure mask generation device is designed to assign an individual exposure time to each exposure mask. This makes it possible, for example, to select the exposure time individually for each object layer to be created, depending on the exposure mask and in particular the type and shape of the area to be exposed. This makes it possible to expose each object layer with only the minimum exposure time required to cure the material, which in total makes the Her creation time for the three-dimensional object is minimized.

The device can be designed in a particularly simple manner if the exposure mask generation device is designed to allocate an identical exposure time for all exposure masks. In this way, an exposure time control or an individual exposure time calculation for each exposure mask can be dispensed with, which simplifies the provision of the respective exposure masks.

The object stated at the outset is also achieved according to the invention in a device for producing a three-dimensional object of the type described at the outset in that the exposure mask generation device is designed in the form of one of the above-described preferred embodiments of exposure mask generation devices. The device for producing a three-dimensional object thus also has the advantages described above in connection with preferred embodiments of exposure mask production devices. In particular, devices already available on the market for producing a three-dimensional object can be retrofitted with an exposure mask production device according to the invention.

It is advantageous if the device comprises an oscillation device for the oscillating exposure of the building plane during an exposure time. - Exposing in an oscillating manner means in particular that an oscillating movement of the image projected onto the building plane relative to the object is realized by the oscillating device. It is thus possible to use such an oscillation device to smooth out angular structures along a contour of the object layer, specifically in that an outer contour is virtually smeared by the oscillation during the exposure of the object layer. The oscillation device preferably makes it possible to realize a natural number of oscillations during the exposure time provided for the respective object layer in order to achieve the most uniform possible edge smoothing along the contour of the object layer.

It is favorable if the oscillation device has an oscillation swing of the exposure which lies in an x and/or a y direction parallel to the building plane in a range which corresponds at most to a width of one pixel. The oscillation swing is preferably a maximum of 0.5 pixels. It is favorable if it is a maximum of 0.25 pixels. In any case, with such an oscillation swing in the sub-pixel range, it is possible to smooth an outer or inner contour of the object layer to be solidified.

In order to round off edges of the contour of the object layer to be solidified, it is favorable if the oscillation device is designed to superimpose an oscillation of the exposure in the x and y directions during the exposure time to form a circular or essentially circular oscillation. In particular, exactly one circular or essentially circular oscillation can be realized with the oscillation device during the exposure time, in order to achieve the most uniform possible edge smoothing.

In order to achieve the relative movement for the oscillating exposure described above, it is advantageous if the oscillation device is coupled to the radiation source and/or the exposure mask generating device and/or imaging optics for imaging the radiation onto the construction plane and/or a carrier for the object to be produced for oscillating movement of the same during the exposure time. For example, the exposure mask generating device can thus be moved relative to a carrier for the object to be produced in order to achieve the described smoothing of edges and corners.

An oscillating device can be implemented in a particularly simple manner if the imaging optics comprise a rotating, plane-parallel disk which is mounted so as to be rotatable about an axis of rotation that is perpendicular or substantially perpendicular to the construction plane and defines a plane of the disk that encloses an angle deviating from 90° with the axis of rotation. In this way, it is possible to send the radiation through the plane-parallel disk, which is tilted relative to the building plane, for example, before it hits the construction plane, which due to its rotation, in particular about the optical axis of the imaging optics, causes the projected radiation and thus the projected image to rotate leads to solidified object layer on the building level.

The radiation source is advantageously designed to generate radiation in the form of electromagnetic radiation or particle radiation. Depending on the material to be solidified, for example a synthetic resin or a prepolymer, this makes it possible to use the ideal radiation source for this purpose. In particular, a corresponding radiation source with sufficient radiation intensity can be selected as a function of the energy input required to solidify the material.

The object set at the outset is also achieved by using a device for producing a three-dimensional object by layer-by-layer solidification of a material that can be solidified under the action of radiation using exposure masks, as described above, for carrying out a method for producing a three-dimensional object by layer-by-layer solidification a radiation solidifiable material using exposure masks also as described above.

1. 1. Verfahren zum Herstellen eines dreidimensionalen Objekts (12) durch schichtweises Verfestigen eines unter Einwirkung von Strahlung (14) verfestigbaren Materials (16) unter Verwendung von Belichtungsmasken (28), wobei zum Ausbilden jeder zu verfestigenden Objektschicht (62) des Objekts (12) in einer Bauebene (22) mindestens eine Belichtungsmaske (28) erzeugt wird, mittels derer die Strahlung (14) selektiv in die Bauebene projiziert wird, dadurch gekennzeichnet, dass jeder Belichtungsfläche, welche eine Querschnittsfläche des Objektes definiert, in jeder Belichtungsmaske (28) eine in sich geschlossene äußere Konturlinie (74) zur Begrenzung der Belichtungsfläche zugewiesen wird, dass den Pixeln zur Ausbildung der Konturlinie (74) der Bit-Wert (32) „durchlässig“ zugewiesen wird, dass jeder Belichtungsfläche in jeder Belichtungsmaske (28) eine innen an die Konturlinie (74) angrenzende Trennlinie (76) zugewiesen wird und dass den Pixeln zur Ausbildung der Trennlinie (76) der Bit-Wert (34) „nicht durchlässig“ zugewiesen wird.
2. 2. Verfahren nach Satz 1, dadurch gekennzeichnet, dass zum Ausbilden jeder zu verfestigenden Objektschicht (62) des Objekts (12) in einer Bauebene (22) eine einzige Belichtungsmaske (28) erzeugt wird.
3. 3. Verfahren nach Satz 1 oder 2, dadurch gekennzeichnet, dass zum Ausbilden jeder zu verfestigenden Objektschicht (62) des Objekts (12) in einer Bauebene (22) eine digitale Belichtungsmaske (28) erzeugt wird.
4. 4. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass eine Breite der Konturlinie (74) und/oder der Trennlinie (76) mindestens 2 Pixel beträgt, insbesondere in einem Bereich von 2 bis 8 Pixeln liegt, vorzugsweise in einem Bereich von 2 bis 4 Pixeln.
5. 5. Verfahren nach einem der voranstehenden Anpsprüche, dadurch gekennzeichnet, dass jeder Belichtungsmaske (28) eine Trennlinie (76) für diejenigen Flächenbereiche (66b, 66c) zugewiesen wird, deren Strukturgröße eine Breite und/oder Länge aufweist, welche mindestens doppelt so groß ist wie eine Breite der Konturlinie (74).
6. 6. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass für jede Belichtungsmaske (28) in Abhängigkeit der zu verfestigenden Objektschicht (62) eine einzige 2-Bit-Bitmap (30) berechnet wird, welche jedem Pixel der Belichtungsmaske (28) entweder den Bit-Wert (32) „durchlässig“ oder den Bit-Wert (34) „nicht durchlässig“ zuordnet, dass mindestens einem Flächenbereich (66a) der 2-Bit-Bitmap (30) mit einer Strukturgröße unterhalb einer Grenzstrukturgröße der Bit-Wert (32) „durchlässig“ zugewiesen wird und dass jedem Flächenbereich (66b, 66c) oberhalb der Grenzstrukturgröße eine Belichtungstextur (52) zugewiesen wird, welche Belichtungstextur in Form eines Musters von Pixeln mit den Bit-Werten (32) „durchlässig“ und (34) „nicht durchlässig“ ausgebildet ist.
7. 7. Verfahren nach Satz 6, dadurch gekennzeichnet, dass die Belichtungstextur (52) höchstens so viele Pixel mit dem Bit-Wert (34) „nicht durchlässig“ wie Pixel mit dem Bit-Wert (32) „durchlässig“ aufweist.
8. 8. Verfahren nach Satz 6 oder 7, dadurch gekennzeichnet, dass jede Belichtungstextur (52) einen Belichtungsabschwächungswert aufweist, welcher größer als 0 ist und maximal 0,5 beträgt.
9. 9. Verfahren nach einem der Sätze 6 bis 8, dadurch gekennzeichnet, dass mindestens einem Flächenbereich (66b, 66c) mit einer Strukturgröße oberhalb der Grenzstrukturgröße eine Belichtungstextur (52) in Abhängigkeit seiner Strukturgröße zugewiesen wird und dass mit zunehmender Strukturgröße der Belichtungsabschwächungswert der Belichtungstextur (52) zunimmt.
10. 10. Verfahren nach einem der Sätze 6 bis 9, dadurch gekennzeichnet, dass identische Belichtungstexturen (52) von Belichtungsmasken (28) zur Belichtung aufeinanderfolgender Objektschichten (62) in einer Ebene parallel zur Bauebene (22) um eine ganzzahlige Pixelzahl relativ zueinander versetzt angeordnet sind, vorzugsweise um 1 Pixel in einer x- und/oder y-Richtung der Ebene parallel zur Bauebene (22).
11. 11. Verfahren nach einem der Sätze 6 bis 10, dadurch gekennzeichnet, dass unterschiedliche Texturmuster zur Ausbildung der Belichtungstexturen (52) bereitgestellt werden, die ein Verhältnis von Pixeln mit dem Bit-Wert (34) „nicht durchlässig“ und von Pixeln mit dem Bit-Wert (32) „durchlässig“ aufweisen, die in einem Bereich zwischen 0 und 1 liegen.
12. 12. Verfahren nach einem der Sätze 6 bis 11, dadurch gekennzeichnet, dass jede Belichtungstextur (52) in Form einer Schraffur oder eines regelmäßigen Musters ausgebildet ist.
13. 13. Verfahren nach einem der Sätze 6 bis 12, dadurch gekennzeichnet, dass nur Belichtungstexturen (52) verwendet werden, bei denen allenfalls Ecken von Pixeln mit dem Bit-Wert (34) „nicht durchlässig“ aufeinandertreffen, jedoch keine Längskanten von Pixeln mit dem Bit-Wert (34) „nicht durchlässig“ aneinander angrenzen.
14. 14. Verfahren nach einem der Sätze 6 bis 13, dadurch gekennzeichnet, dass jede Belichtungstextur (52) durch eine Translation in einer Ebene parallel zur Bauebene (22) in sich selbst überführbar ist.
15. 15. Verfahren nach Satz 14, dadurch gekennzeichnet, dass die Translation durch einen Vektor definiert wird, welcher eine Länge aufweist, die n Pixeln in einer x-Richtung und m Pixeln in einer zur x-Richtung nicht parallelen y-Richtung entspricht, wobei n und m ganze Zahlen sind.
16. 16. Verfahren nach einem der Sätze 6 bis 15, dadurch gekennzeichnet, dass jede Belichtungstextur (52) pixelweise gerastert ist.
17. 17. Verfahren nach einem der Sätze, dadurch gekennzeichnet, dass jeder Belichtungsfläche, welche eine Querschnittsfläche des Objektes definiert, in jeder Belichtungsmaske (28) für jede Aussen- und Innenkontur der Belichtungsfläche jeweils eine geschlossene Randlinie (56) zugewiesen wird und dass den die Randlinie (56) ausbildenden Pixeln der Bit-Wert (32) „durchlässig“ zugewiesen wird.
18. 18. Verfahren nach Satz 17, dadurch gekennzeichnet, dass eine Breite der Randlinie (56) mindestens zwei Pixel beträgt, vorzugsweise dass die Breite der Randlinie (56) in einem Bereich von 2 bis 8 Pixeln liegt, weiter vorzugsweise in einem Bereich von 2 bis 4 Pixeln.
19. 19. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass als Strahlung (14) elektromagnetische Strahlung oder Teilchenstrahlung verwendet wird.
20. 20. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass jeder Belichtungsmaske (28) eine individuelle Belichtungszeit zugeordnet wird.
21. 21. Verfahren nach Satz 20, dadurch gekennzeichnet, dass die Belichtungszeit für alle Belichtungsmasken (28) identisch ist.
22. 22. Verfahren nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass die Bauebene (22) während einer Belichtungszeit oszillierend belichtet wird.
23. 23. Verfahren nach Satz 22, dadurch gekennzeichnet, dass ein Oszillationshub der Belichtung in einer x- und/oder einer y-Richtung parallel zur Bauebene (22) in einem Bereich liegt, welcher maximal einer Breite eines Pixels entspricht, vorzugsweise maximal 0,5 Pixel, insbesondere maximal 0,25 Pixel.
24. 24. Verfahren nach Satz 22 oder 23, dadurch gekennzeichnet, dass eine Oszillation der Belichtung in der x- und der y-Richtung während der Belichtungszeit zu einer kreisförmigen oder im Wesentlichen kreisförmigen Oszillation überlagert ist.
25. 25. Verfahren nach einem der Sätze 22 bis 24, dadurch gekennzeichnet, dass eine Strahlungsquelle (18) zur Erzeugung der Strahlung (14) und/ oder die Belichtungsmaske (28) und/oder eine Abbildungsoptik (20) zum Abbilden der Strahlung (14) auf die Bauebene (22) und/oder das herzustellende Objekt (12) während der Belichtungszeit oszillierend bewegt werden.
26. 26. Verfahren nach Satz 25, dadurch gekennzeichnet, dass eine Abbildungsoptik (20) mit einer rotierenden planparallele Scheibe (86) verwendet wird, wobei die Scheibe (86) um eine zur Bauebene (22) senkrechte oder im Wesentlichen senkrechte Rotationsachse rotiert wird und eine Scheibenebene (88) definiert, die mit der Rotationsachse (84) einen von 90° abweichenden Winkel (90) einschließt.
27. 27. Belichtungsmaskenerzeugungseinrichtung (26) für eine Vorrichtung (10) zum Herstellen eines dreidimensionalen Objekts (12) durch schichtweises Verfestigen eines unter Einwirkung von Strahlung (14) verfestigbaren Materials (16) unter Verwendung von Belichtungsmasken (28), welche Vorrichtung (10) eine Strahlungsquelle (18) zum Erzeugen der Strahlung (14) und die Belichtungsmaskenerzeugungseinrichtung (26) umfasst, welche Belichtungsmaskenerzeugungseinrichtung (26) zum Ausbilden jeder zu verfestigenden Objektschicht (62) des Objekts (12) in einer Bauebene (22) mindestens eine digitale Belichtungsmaske (28) erzeugt, mittels derer die Strahlung (14) selektiv in die Bauebene projiziert wird, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist zum Zuweisen einer in sich geschlossenen äußeren Konturlinie (74) zur Begrenzung der Objektschicht (62) und einer innen an die Konturlinie (74) direkt angrenzenden Trennlinie (76) zu jeder Belichtungsmaske (28), wobei den Pixeln zur Ausbildung der Konturlinie (74) der Bit-Wert (32) „durchlässig“ und den Pixeln zur Ausbildung der Trennlinie (76) der Bit-Wert (34) „nicht durchlässig“ zugewiesen ist.
28. 28. Belichtungsmaskenerzeugungseinrichtung nach Satz 27, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung ausgebildet ist zum Erzeugen einer einzigen Belichtungsmaske (28).
29. 29. Belichtungsmaskenerzeugungseinrichtung nach Satz 27 oder 28, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung ausgebildet ist zum Erzeugen einer digitalen Belichtungsmaske (28).
30. 30. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 27 bis 29, dadurch gekennzeichnet, dass eine Breite der Konturlinie (74) und/oder der Trennlinie (76) mindestens 2 Pixel beträgt, insbesondere in einem Bereich von 2 bis 8 Pixeln liegt, vorzugsweise in einem Bereich von 2 bis 4 Pixeln.
31. 31. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 27 bis 30, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist zum Zuweisen einer Trennlinie (76) zu einer Belichtungsmaske (28) für diejenigen Flächenbereiche (66b, 66c) derselben, deren Strukturgröße eine Breite und/oder Länge aufweist, welche mindestens doppelt so groß ist wie eine Breite der Konturlinie.
32. 32. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 27 bis 31, dadurch gekennzeichnet, dass die Recheneinheit ausgebildet ist zum Berechnen einer einzigen Bitmap (30) für jede Belichtungsmaske (28) in Abhängigkeit der zu verfestigenden Objektschicht (62).
33. 33. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 27 bis 32, dadurch gekennzeichnet, dass die Recheneinheit ausgebildet ist zum Berechnen einer Bitmap (30) in Form einer 2-Bit-Bitmap (30) für jede Belichtungsmaske (28) in Abhängigkeit der zu verfestigenden Objektschicht (62).
34. 34. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 27 bis 33, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) eine Recheneinheit (38) umfasst zum Berechnen einer einzigen 2-Bit-Bitmap (30) für jede Belichtungsmaske (28) in Abhängigkeit der zu verfestigenden Objektschicht (62), welche 2-Bit-Bitmap (30) jedem Pixel der Belichtungsmaske (28) entweder den Bit-Wert (32) „durchlässig“ oder den Bit-Wert (34) „nicht durchlässig“ zuordnet, zum Zuweisen des Bit-Werts (32) „durchlässig“ zu jedem Flächenbereich (66a) der 2-Bit-Bitmap (30) mit einer Strukturgröße unterhalb einer Grenzstrukturgröße und zum Zuweisen einer Belichtungstextur (52) zu jedem Flächenbereich (66b, 66c) oberhalb der Grenzstrukturgröße, welche Belichtungstextur (52) in Form eines Musters von Pixeln mit den Bit-Werten (32) „durchlässig“ und (34) „nicht durchlässig“ ausgebildet ist.
35. 35. Belichtungsmaskenerzeugungseinrichtung nach Satz 34, dadurch gekennzeichnet, dass die Recheneinheit (38) ausgebildet ist zum Zuweisen einer Belichtungstextur (52), welche höchstens so viele Pixel mit dem Bit-Wert (34) „nicht durchlässig“ wie Pixel mit dem Bit-Wert (32) „durchlässig“ aufweist.
36. 36. Belichtungsmaskenerzeugungseinrichtung nach Satz 34 oder 35, dadurch gekennzeichnet, dass die Recheneinheit (38) ausgebildet ist zum Zuweisen einer Belichtungstextur (52), welche einen Belichtungsabschwächungswert aufweist, welcher größer als 0 ist und maximal 0,5 beträgt.
37. 37. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 34 bis 36, dadurch gekennzeichnet, dass die Recheneinheit (38) ausgebildet ist zum Zuweisen einer Belichtungstextur (52) zu jedem Flächenbereich (66b, 66c) mit einer Strukturgröße oberhalb der Grenzstrukturgröße in Abhängigkeit seiner Strukturgröße, wobei mit zunehmender Strukturgröße der Belichtungsabschwächungswert der Belichtungstextur (52) zunimmt.
38. 38. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 34 bis 37, dadurch gekennzeichnet, dass die Recheneinheit (38) ausgebildet ist zum versetzten Anordnen identischer Belichtungstexturen (52) von Belichtungsmasken (28) zur Belichtung aufeinanderfolgender Objektschichten (62) in einer Ebene parallel zur Bauebene (22) um eine ganzzahlige Pixelzahl relativ zueinander, vorzugsweise um 1 Pixel in einer x- und/oder y-Richtung der Ebene parallel zur Bauebene (22).
39. 39. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 34 bis 38, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) unterschiedliche Texturmuster zur Ausbildung der Belichtungstexturen (52) bereitstellt, die ein Verhältnis von Pixeln mit dem Bit-Wert (34) „nicht durchlässig“ und von Pixeln mit dem Bit-Wert (32) „durchlässig“ aufweisen, die in einem Bereich zwischen 0 und 1 liegen.
40. 40. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 34 bis 39, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (28) jede Belichtungstextur (52) in Form einer Schraffur oder eines regelmäßigen Musters bereitstellt.
41. 41. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 34 bis 40, dadurch gekennzeichnet, dass die Recheneinheit (38) ausgebildet ist zum ausschließlichen Verwenden von Belichtungstexturen (52), bei denen allenfalls Ecken von Pixeln mit dem Bit-Wert (34) „nicht durchlässig“ aufeinandertreffen, jedoch keine Längskanten von Pixeln mit dem Bit-Wert (34) „nicht durchlässig“ aneinander angrenzen.
42. 42. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 34 bis 41, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist zum Bereitstellen von Belichtungstexturen (52), welche durch eine Translation in einer Ebene parallel zur Bauebene (22) in sich selbst überführbar sind.
43. 43. Belichtungsmaskenerzeugungseinrichtung nach Satz 42, dadurch gekennzeichnet, dass die Translation durch einen Vektor definiert wird, welcher eine Länge aufweist, die n Pixeln in einer x-Richtung und m Pixeln in einer zur x-Richtung nicht parallelen y-Richtung entspricht, wobei n und m ganze Zahlen sind.
44. 44. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 34 bis 43, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist zum Bereitstellen von Belichtungstexturen (52), welche pixelweise gerastert sind.
45. 45. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 27 bis 44, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist zum Zuweisen einer geschlossenen Randlinie (56) zu jeder Belichtungsmaske (28) für jeden Flächenbereich (66b, 66c) oberhalb der Grenzstrukturgröße, wobei den die Randlinie (56) ausbildenden Pixeln der Bit-Wert „durchlässig“ zugewiesen ist.
46. 46. Belichtungsmaskenerzeugungseinrichtung nach Satz 45, dadurch gekennzeichnet, dass eine Breite der Randlinie (56) mindestens 2 Pixel beträgt, insbesondere in einem Bereich von 2 bis 8 Pixeln liegt, vorzugsweise in einem Bereich von 2 bis 4 Pixeln.
47. 47. Belichtungsmaskenerzeugungseinrichtung nach einem der Sätze 27 bis 46, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist zum Zuordnen einer individuellen Belichtungszeit zu jeder Belichtungsmaske (28).
48. 48. Belichtungsmaskenerzeugungseinrichtung nach Satz 47, dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist zum Zuordnen einer identischen Belichtungszeit für alle Belichtungsmasken (28).
49. 49. Vorrichtung (10) zum Herstellen eines dreidimensionalen Objekts (12) durch schichtweises Verfestigen eines unter Einwirkung von Strahlung (14) verfestigbaren Materials (16) unter Verwendung von Belichtungsmasken (28), umfassend eine Strahlungsquelle (18) zum Erzeugen der Strahlung (14) und eine Belichtungsmaskenerzeugungseinrichtung (26), dadurch gekennzeichnet, dass die Belichtungsmaskenerzeugungseinrichtung (26) ausgebildet ist in Form einer Belichtungsmaskenerzeugungseinrichtung (26) nach einem der Sätze 27 bis 48.
50. 50. Vorrichtung nach Satz 49, dadurch gekennzeichnet, dass eine Oszillationseinrichtung (80) vorgesehen ist zum oszillierenden Belichten der Bauebene (22) während einer Belichtungszeit.
51. 51. Vorrichtung nach Satz 50, dadurch gekennzeichnet, dass die Oszillationseinrichtung (80) einen Oszillationshub der Belichtung aufweist, welcher in einer x- und/oder einer y-Richtung parallel zur Bauebene (22) in einem Bereich liegt, welcher maximal einer Breite eines Pixels entspricht, vorzugsweise maximal 0,5 Pixel, insbesondere maximal 0,25 Pixel.
52. 52. Vorrichtung nach Satz 50 oder 51, dadurch gekennzeichnet, dass die Oszillationseinrichtung (80) ausgebildet ist zum Überlagern einer Oszillation der Belichtung in der x- und der y-Richtung während der Belichtungszeit zu einer kreisförmigen oder im Wesentlichen kreisförmigen Oszillation.
53. 53. Vorrichtung nach einem der Sätze 50 bis 52, dadurch gekennzeichnet, dass die Oszillationseinrichtung (80) gekoppelt ist mit der Strahlungsquelle (18) und/oder der Belichtungsmaskenerzeugungseinrichtung (26) und/oder einer Abbildungsoptik (20) zum Abbilden der Strahlung (14) auf die Bauebene (22) und/oder einem Träger (42) für das herzustellende Objekt (12) zum oszillierenden Bewegen derselben während der Belichtungszeit.
54. 54. Vorrichtung nach Satz 53, dadurch gekennzeichnet, dass die Abbildungsoptik (20) eine rotierende planparallele Scheibe (86) umfasst, welche um eine um eine zur Bauebene (22) senkrechte oder im Wesentlichen senkrechte Rotationsachse (84) rotierbar gelagert ist und eine Scheibenebene (88) definiert, die mit der Rotationsachse (84) einen von 90° abweichenden Winkel (90) einschließt.
55. 55. Vorrichtung nach einem der Sätze 49 bis 54, dadurch gekennzeichnet, dass die Strahlungsquelle (18) ausgebildet ist zum Erzeugen von Strahlung (14) in Form von elektromagnetischer Strahlung oder Teilchenstrahlung.
56. 56. Verwendung einer Vorrichtung (10) zum Herstellen eines dreidimensionalen Objekts (12) durch schichtweises Verfestigen eines unter Einwirkung von Strahlung (14) verfestigbaren Materials (16) unter Verwendung von Belichtungsmasken (28) nach einem der Sätze 46 bis 55 zur Durchführung eines Verfahrens zum Herstellen eines dreidimensionalen Objekts (12) durch schichtweises Verfestigen eines unter Einwirkung von Strahlung (14) verfestigbaren Materials (16) unter Verwendung von Belichtungsmasken (28) nach einem der Sätze 1 bis 26.

The above description thus includes, in particular, the embodiments of exposure mask generating devices, as well as methods and devices for producing a three-dimensional object, which are explicitly listed below in the form of numbered sentences:

1. 1. Method for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28), wherein for forming each object layer (62) of the object (12) to be solidified at least one exposure mask (28) is produced in a building level (22), by means of which the radiation (14) is projected selectively into the building level, characterized in that each exposure area, which defines a cross-sectional area of the object, in each exposure mask (28) has a self-contained outer contour line (74) is assigned to delimit the exposure area, that the pixels for forming the contour line (74) are assigned the bit value (32) "transparent", that each exposure area in each exposure mask (28) has an inside the dividing line (76) adjoining the contour line (74) is assigned and that the pixels for forming the dividing line (76) are assigned the bit value (34) is assigned "not permeable".
2. 2. The method according to sentence 1, characterized in that a single exposure mask (28) is produced in a construction level (22) to form each object layer (62) of the object (12) to be solidified.
3. 3. Method according to sentence 1 or 2, characterized in that a digital exposure mask (28) is produced in a construction plane (22) to form each object layer (62) of the object (12) to be solidified.
4. 4. The method according to any one of the preceding sentences, characterized in that the width of the contour line (74) and/or the dividing line (76) is at least 2 pixels, in particular in a range of 2 to 8 pixels, preferably in a range of 2 up to 4 pixels.
5. 5. The method according to any one of the preceding claims, characterized in that each exposure mask (28) is assigned a separating line (76) for those surface areas (66b, 66c) whose structural size has a width and/or length that is at least twice as large as a width of the contour line (74).
6. 6. The method according to any one of the preceding sentences, characterized in that for each exposure mask (28) as a function of the object layer (62) to be solidified, a single 2-bit bitmap (30) is calculated, which each pixel of the exposure mask (28) either assigns the bit value (32) "permeable" or the bit value (34) "not permeable" that at least one area (66a) of the 2-bit bitmap (30) with a structure size below a limit structure size the bit value (32) is assigned "transparent" and that each area (66b, 66c) above the limit structure size is assigned an exposure texture (52), which exposure texture is in the form of a pattern of pixels with the bit values (32) "transparent" and (34 ) is "non-permeable".
7. 7. The method according to sentence 6, characterized in that the exposure texture (52) has at most as many pixels with the bit value (34) “non-transparent” as pixels with the bit value (32) “transparent”.
8. 8. The method according to sentence 6 or 7, characterized in that each exposure texture (52) has an exposure attenuation value which is greater than 0 and is at most 0.5.
9. 9. Method according to one of sentences 6 to 8, characterized in that at least one surface area (66b, 66c) with a structure size above the limit structure size is assigned an exposure texture (52) depending on its structure size and that the exposure attenuation value of the exposure texture ( 52) increases.
10. 10. The method according to one of sentences 6 to 9, characterized in that identical exposure textures (52) of exposure masks (28) for exposure of successive object layers (62) are arranged in a plane parallel to the building plane (22) offset by an integer number of pixels relative to one another , preferably by 1 pixel in an x and/or y direction of the plane parallel to the building plane (22).
11. 11. The method according to any one of sentences 6 to 10, characterized in that different texture patterns for forming the exposure textures (52) are provided which have a ratio of pixels with the bit value (34) “not transparent” and pixels with the bit -value (32) "permeable" ranging from 0 to 1.
12. 12. The method according to any one of sentences 6 to 11, characterized in that each exposure texture (52) is designed in the form of hatching or a regular pattern.
13. 13. The method according to any one of sentences 6 to 12, characterized in that only exposure textures (52) are used in which at most corners of pixels with the bit value (34) "not permeable" meet, but no longitudinal edges of pixels with the Bit value (34) "non-permeable" adjoin each other.
14. 14. Method according to one of sentences 6 to 13, characterized in that each exposure texture (52) can be converted into itself by a translation in a plane parallel to the building plane (22).
15. 15. Method according to clause 14, characterized in that the translation is defined by a vector which has a length which corresponds to n pixels in an x-direction and m pixels in a y-direction which is not parallel to the x-direction, where n and m are integers.
16. 16. Method according to one of sentences 6 to 15, characterized in that each exposure texture (52) is screened pixel by pixel.
17. 17. The method according to any one of the sentences, characterized in that each exposure area, which defines a cross-sectional area of the object, is assigned a closed edge line (56) in each exposure mask (28) for each outer and inner contour of the exposure area and that the edge line (56) forming pixels is assigned the bit value (32) “transparent”.
18. 18. The method according to sentence 17, characterized in that a width of the edge line (56) is at least two pixels, preferably that the width of the edge line (56) is in a range from 2 to 8 pixels, more preferably in a range from 2 to 4 pixels.
19. 19. The method according to any one of the preceding sentences, characterized in that electromagnetic radiation or particle radiation is used as the radiation (14).
20. 20. Method according to one of the preceding sentences, characterized in that each exposure mask (28) is assigned an individual exposure time.
21. 21. Method according to sentence 20, characterized in that the exposure time is identical for all exposure masks (28).
22. 22. The method according to any one of the preceding sentences, characterized in that the building plane (22) is oscillatingly exposed during an exposure time.
23. 23. The method according to sentence 22, characterized in that an oscillation range of the exposure in an x and/or a y direction parallel to the building plane (22) lies in a range which corresponds at most to a width of a pixel, preferably at most 0.5 pixels, in particular a maximum of 0.25 pixels.
24. 24. The method according to sentence 22 or 23, characterized in that an oscillation of the exposure in the x and y directions is superimposed during the exposure time to form a circular or substantially circular oscillation.
25. 25. The method according to any one of sentences 22 to 24, characterized in that a radiation source (18) for generating the radiation (14) and/or the exposure mask (28) and/or imaging optics (20) for imaging the radiation (14) are moved in an oscillating manner on the construction level (22) and/or the object (12) to be produced during the exposure time.
26. 26. The method according to sentence 25, characterized in that imaging optics (20) with a rotating plane-parallel disk (86) are used, the disk (86) being rotated about an axis of rotation perpendicular or substantially perpendicular to the construction plane (22) and a Disk plane (88) defined, which includes an angle deviating from 90 ° (90) with the axis of rotation (84).
27. 27. Exposure mask generating device (26) for a device (10) for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28), which device (10) has a Radiation source (18) for generating the radiation (14) and the exposure mask generating device (26), which exposure mask generating device (26) comprises at least one digital exposure mask (28 ) generated, by means of which the radiation (14) is selectively projected into the building plane, characterized in that the exposure mask generating device (26) is formed for assigning to each exposure mask (28) a self-contained outer contour line (74) for delimiting the object layer (62) and a separating line (76) directly adjoining the inside of the contour line (74), the pixels for forming the contour line (74) the bit value (32) is assigned “transparent” and the pixels for forming the dividing line (76) are assigned the bit value (34) “non-transparent”.
28. 28. Exposure mask generation device according to sentence 27, characterized in that the exposure mask generation device is designed to generate a single exposure mask (28).
29. 29. Exposure mask generation device according to sentence 27 or 28, characterized in that the exposure mask generation device is designed to generate a digital exposure mask (28).
30. 30. Exposure mask generation device according to one of sentences 27 to 29, characterized in that a width of the contour line (74) and/or the dividing line (76) is at least 2 pixels, in particular in a range of 2 to 8 pixels, preferably in a range from 2 to 4 pixels.
31. 31. Exposure mask generation device according to one of sentences 27 to 30, characterized in that the exposure mask generation device (26) is designed to assign a separating line (76) to an exposure mask (28) for those surface areas (66b, 66c) of the same whose structure size is a width and /or has a length which is at least twice as large as a width of the contour line.
32. 32. Exposure mask generation device according to one of sentences 27 to 31, characterized in that the computing unit is designed to calculate a single bitmap (30) for each exposure mask (28) as a function of the object layer (62) to be solidified.
33. 33. Exposure mask generation device according to one of sentences 27 to 32, characterized in that the computing unit is designed to calculate a bitmap (30) in the form of a 2-bit bitmap (30) for each exposure mask (28) as a function of the object layer to be solidified ( 62).
34. 34. Exposure mask generation device according to one of sentences 27 to 33, characterized in that the exposure mask generation device (26) comprises a computing unit (38) for calculating a single 2-bit bitmap (30) for each exposure mask (28) as a function of the object layer to be solidified (62), which 2-bit bitmap (30) assigns each pixel of the exposure mask (28) either the bit value (32) "transparent" or the bit value (34) "non-transparent", for assigning the bit Value (32) "permeable" to each area (66a) of the 2-bit bitmap (30) with a structure size below a limit structure size and for assigning an exposure texture (52) to each area (66b, 66c) above the limit structure size, which exposure texture (52) is in the form of a pattern of pixels with bit values (32) "transparent" and (34) "non-transparent".
35. 35. Exposure mask generation device according to sentence 34, characterized in that the arithmetic unit (38) is designed to assign an exposure texture (52) which has at most as many pixels with the bit value (34) as “non-transparent” pixels with the bit value (32) "permeable".
36. 36. Exposure mask generation device according to sentence 34 or 35, characterized in that the computing unit (38) is designed to assign an exposure texture (52) which has an exposure attenuation value which is greater than 0 and is a maximum of 0.5.
37. 37. Exposure mask generation device according to one of sentences 34 to 36, characterized in that the computing unit (38) is designed to assign an exposure texture (52) to each surface area (66b, 66c) with a structure size above the limit structure size depending on its structure size, with as feature size increases, the exposure attenuation value of the exposure texture (52) increases.
38. 38. Exposure mask generation device according to one of sentences 34 to 37, characterized in that the computing unit (38) is designed for the offset arrangement of identical exposure textures (52) of exposure masks (28) for the exposure of successive object layers (62) in a plane parallel to the building plane (22 ) by an integer number of pixels relative to one another, preferably by 1 pixel in an x and/or y direction of the plane parallel to the building plane (22).
39. 39. Exposure mask generation device according to one of sentences 34 to 38, characterized in that the exposure mask generation device (26) provides different texture patterns for forming the exposure textures (52) which have a ratio of pixels with the bit value (34) "non-transparent" and of Pixels with bit value (32) "perv sig" that ranges from 0 to 1.
40. 40. Exposure mask generating device according to one of sentences 34 to 39, characterized in that the exposure mask generating device (28) provides each exposure texture (52) in the form of hatching or a regular pattern.
41. 41. Exposure mask generation device according to one of sentences 34 to 40, characterized in that the computing unit (38) is designed to exclusively use exposure textures (52) in which at most corners of pixels with the bit value (34) "non-transparent" meet , but no long edges of pixels with bit value (34) “non-transparent” are contiguous.
42. 42. Exposure mask generation device according to one of sentences 34 to 41, characterized in that the exposure mask generation device (26) is designed to provide exposure textures (52) which can be converted into themselves by translation in a plane parallel to the building plane (22).
43. 43. Exposure mask generation device according to clause 42, characterized in that the translation is defined by a vector which has a length which corresponds to n pixels in an x-direction and m pixels in a y-direction which is not parallel to the x-direction, where n and m are integers.
44. 44. Exposure mask generation device according to one of sentences 34 to 43, characterized in that the exposure mask generation device (26) is designed to provide exposure textures (52) which are screened pixel by pixel.
45. 45. Exposure mask generation device according to one of sentences 27 to 44, characterized in that the exposure mask generation device (26) is designed to assign a closed edge line (56) to each exposure mask (28) for each surface area (66b, 66c) above the limit feature size, wherein the the pixels forming the border line (56) are assigned the bit value “transparent”.
46. 46. Exposure mask generation device according to sentence 45, characterized in that a width of the edge line (56) is at least 2 pixels, in particular in a range from 2 to 8 pixels, preferably in a range from 2 to 4 pixels.
47. 47. Exposure mask generation device according to one of sentences 27 to 46, characterized in that the exposure mask generation device (26) is designed to assign an individual exposure time to each exposure mask (28).
48. 48. exposure mask generation device according to sentence 47, characterized in that the exposure mask generation device (26) is designed to assign an identical exposure time for all exposure masks (28).
49. 49. Device (10) for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28), comprising a radiation source (18) for generating the radiation (14 ) and an exposure mask generating device (26), characterized in that the exposure mask generating device (26) is designed in the form of an exposure mask generating device (26) according to one of sentences 27 to 48.
50. 50. Device according to sentence 49, characterized in that an oscillation device (80) is provided for the oscillating exposure of the building plane (22) during an exposure time.
51. 51. The device according to sentence 50, characterized in that the oscillation device (80) has an oscillation stroke of the exposure which is in an x and/or a y direction parallel to the building plane (22) in an area which has a maximum width of one Pixels corresponds, preferably a maximum of 0.5 pixels, in particular a maximum of 0.25 pixels.
52. 52. Device according to sentence 50 or 51, characterized in that the oscillation device (80) is designed to superimpose an oscillation of the exposure in the x and y directions during the exposure time to form a circular or substantially circular oscillation.
53. 53. Device according to one of sentences 50 to 52, characterized in that the oscillation device (80) is coupled to the radiation source (18) and/or the exposure mask generating device (26) and/or imaging optics (20) for imaging the radiation (14 ) on the construction level (22) and/or a carrier (42) for the object (12) to be produced for the oscillating movement thereof during the exposure time.
54. 54. Device according to sentence 53, characterized in that the imaging optics (20) comprises a rotating plane-parallel disc (86), which is rotatably mounted about an axis of rotation (84) perpendicular or substantially perpendicular to the construction plane (22) and defines a disk plane (88) which encloses an angle (90) deviating from 90° with the axis of rotation (84).
55. 55. Device according to one of sentences 49 to 54, characterized in that the radiation source (18) is designed to generate radiation (14) in the form of electromagnetic radiation or particle radiation.
56. 56. Use of a device (10) for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28) according to one of sets 46 to 55 for carrying out a method for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28) according to one of sets 1 to 26.

• 1: eine schematische Darstellung eines Teils einer Vorrichtung zum Herstellen eines dreidimensionalen Objekts;
• 2: eine schematische Ansicht eines weiteren Teils einer Vorrichtung zum Herstellen eines dreidimensionalen Objekts;
• 3: eine schematische Ansicht eines weiteren Teils eines zweiten Ausführungsbeispiels einer Vorrichtung zum Herstellen eines dreidimensionalen Objekts;
• 4: eine schematische Darstellung eine Belichtungsmaske mit einer Belichtungstextur;
• 5: eine schematische Darstellung der Durchhärtetiefe mit und ohne Belichtungstextur;
• 6: eine schematische Darstellung der Intensitätsverteilung der Strahlung nach der Erzeugung und beim Auftreffen auf die Bauebene im Flächenbereich einer Belichtungstextur, hier Schachbrettmuster auf Pixelniveau;
• 7: eine schematische Darstellung verschiedener Texturmuster mit zugeordnetem Belichtungsabschwächungswert in Prozent;
• 8: eine schematische Schnittdarstellung identischer Texturmuster von Belichtungsmasken zur Belichtung aufeinanderfolgender Objektschichten;
• 9: eine schematische Darstellung der Auswahl einer Belichtungsmaske mit unterschiedlichen Texturmustern in Abhängigkeit unterschiedlicher identifizierter (Grenz-)Strukturgrößen innerhalb einer zu belichtenden Fläche in der auszubildenden Objektschicht;
• 10: eine schematische Darstellung der Intensitätsverteilung einer Strahlungsquelle;
• 11: eine schematische Darstellung einer Belichtungsmaske unter Berücksichtigung der Intensitätsverteilung der Strahlungsquelle;
• 12: eine schematische Darstellung einer Belichtungsmaske ohne Berücksichtigung der Intensitätsverteilung der Strahlungsquelle;
• 13: eine schematische Darstellung einer Belichtung einer Kreisscheibe mit schematischer dargestelltem Streulicht im Randbereich;
• 14: eine schematische Ansicht analog 13, jedoch unter Einsatz einer äußeren Konturlinie mit daran angrenzender Trennlinie und schematischer Darstellung einer Verringerung des Streulichts;
• 15: eine schematische Darstellung einer kreisförmigen Oszillation einer Belichtungsmaske im Subpixelbereich;
• 16: eine vergrößerte Ansicht des Bereichs A in 15; und
• 17: eine schematische Darstellung eines weiteren Ausführungsbeispiels einer Oszillationseinrichtung.

The following description is used in connection with the drawings for more detailed explanation. Show it:

• 1 1: a schematic representation of part of a device for producing a three-dimensional object;
• 2 1: a schematic view of a further part of a device for producing a three-dimensional object;
• 3 1: a schematic view of a further part of a second exemplary embodiment of a device for producing a three-dimensional object;
• 4 : a schematic representation of an exposure mask with an exposure texture;
• 5 : a schematic representation of the depth of cure with and without exposure texture;
• 6 : a schematic representation of the intensity distribution of the radiation after generation and when it hits the construction level in the surface area of an exposure texture, here a chessboard pattern at pixel level;
• 7 : a schematic representation of different texture patterns with associated exposure attenuation value in percent;
• 8th : a schematic sectional view of identical texture patterns of exposure masks for exposure of successive object layers;
• 9 1: a schematic representation of the selection of an exposure mask with different texture patterns as a function of different identified (limit) structure sizes within an area to be exposed in the object layer to be formed;
• 10 : a schematic representation of the intensity distribution of a radiation source;
• 11 : a schematic representation of an exposure mask taking into account the intensity distribution of the radiation source;
• 12 : a schematic representation of an exposure mask without taking into account the intensity distribution of the radiation source;
• 13 1: a schematic representation of an exposure of a circular disk with scattered light represented schematically in the edge region;
• 14 : a schematic view by analogy 13 , but using an outer contour line with adjacent dividing line and schematic representation of a reduction in stray light;
• 15 : a schematic representation of a circular oscillation of an exposure mask in the sub-pixel area;
• 16 : an enlarged view of area A in 15 ; and
• 17 1: a schematic representation of a further exemplary embodiment of an oscillation device.

The schematic structure of a device 10 for producing a three-dimensional object by layer-by-layer solidification of a material 16 that can be solidified under the action of radiation 14 is shown schematically in FIGS 1 until 3 shown for two different configurations.

The device 10 includes a radiation source 18 which includes imaging optics 20 for imaging an object layer image in an image/construction plane 22 . The imaging optics 20 include a mask unit 24 which can be controlled by an exposure mask generating device 26 . With the exposure mask generating device 26, an exposure mask 28 can be generated for each object layer of the object 12, specifically in the form of a 2-bit bitmap 30. Each 2-bit bitmap 30 therefore has only two bit values 32 and 34, with the Bit value 32 allows for greater transmission of radiation 14 than bit value 34. In the extreme case, bit value 32 can be completely "transparent" for radiation 14, bit value 34 can be completely "non-transparent" for radiation 14 “. In any case, the permeability of Pixels of the 2-bit bitmap 30 with bit value 32 greater than the opacity of the pixel with bit value 34.

The exposure mask generation device 26 also includes a storage device 36, which can contain, for example, stored native information for the object layers of the object 12 to be formed. In particular, these can be transferred to a computer 38 or another computing device suitable for this purpose. Depending on the layer information, the computer 36 calculates a 2-bit bitmap 30, which is then transferred to the mask unit 24 in order, for example, to control an LCD display when exposed in transmission or a digital micromirror device, in order in this way to control the light emitted by the radiation source 18 to map the generated radiation 14 onto the image/construction plane 22 in accordance with the object layer to be formed. In the image/construction plane 22, the radiation 14 impinges on still unsolidified, viscous material 16, which is solidified after a certain time by the energy input through exposure. An individual exposure time can be specified for each object layer, so that, for example, the mask unit 24 completely holds back the radiation 14 if no object layer is to be formed and selectively lets the radiation 14 through if an object layer is to be formed.

In particular, two types of carrier systems 40 are used to form objects 12 . At the in 2 In the variant shown schematically, a carrier plate 42 is located in a container 44 filled with the material 16. The carrier plate 42 can be moved into the container 44 with a drive device 46, preferably in predetermined, discrete steps, which are always carried out when a further object layer is solidified by hardening of the material on the surface of the already partially formed object 12 and thus forms a further object layer.

Alternatively, as in 3 1, the radiation 14 can also be imaged into the image/build plane 22 through a radiation-transmissive plate 48 which forms a base 50 of the alternative container 44'. The object layer to be formed is also created by the input of energy in the image/construction plane 22, specifically under the last object layer formed. If an object layer has hardened, the already formed object 12 is moved in a predetermined manner by means of the drive unit 46 a piece, in particular a distance that corresponds to a thickness of the newly formed object layer, away from the container 44, i.e. somewhat pulled out of it. In a next step, the next object layer can now be produced by exposing the material 16 in the image/construction plane 22 .

The exposure mask generating device 26 also makes it possible to generate not just simple 2-bit bitmaps for controlling the mask unit 24, in which pixels to be solidified in the object layer to be formed are assigned the bit value 32 and all other pixels are assigned the bit value 34. Rather, it is optionally also possible to use the exposure mask generating device 26 to avoid the problem of overexposure of large areas mentioned at the outset. In order to be able to produce filigree and large-volume structures side by side when forming an object layer with the same good quality, it is proposed according to the invention to fill surface areas of the object 12 with a size above a limit structure size with an exposure texture 52 . In 4 This procedure is shown schematically. A filigree structure 54 is in 4 schematically shown 2-bit bitmap 30 in the form of an elongated narrow rectangle shown on the right.

In the 2-bit bitmap 30, a circular area that is relatively large in comparison to the elongated, narrow rectangle is shown on the left, which is delimited on the outside by a closed contour line 56. However, the circular area is not completely filled with pixels with the bit value 32 "transparent", but with an exposure texture 52. This is composed of individual pixels with the only two available bit values 32 "transparent" and 34 "non-transparent". The exposure texture 52 is preferably implemented in the form of a regular pattern which is screened at the pixel level. In particular, the screening is designed in such a way that only exposure textures are used in which the corners of pixels with the bit value 34 "non-permeable" meet at most, but no longitudinal edges of pixels with the bit value 34 "non-permeable" adjoin one another. In the 4 The exposure texture 52 shown as an example corresponds exactly to this specification. It shows a chessboard-like pattern in which pixels with the bit values 32 “permeable” and 34 “non-permeable” are arranged alternately. In order to ensure the stability of the object 12, the contour line 56 is provided with a width which is preferably in a range of 2 to 8 pixels. In particular, it can also only be 2 to 4 pixels wide.

An effect that using the in 4 has exposure mask 30 shown, is shown schematically in 5 shown. With a predetermined fixed exposure time, for the filigree structure 54 the in 5 the hardening depth shown schematically with arrows on the right is reached. Would the circular area surface is completely exposed, there is a significantly greater depth of hardening over the large surface area. This is in the diagram in 5 symbolized by the solid arrows. The exposure texture 52 serves to compensate for this, which on average reduces the depth of hardening for the larger structure due to the lower energy input. It is thus possible, by appropriate choice of exposure textures 52, to simultaneously expose filigree structures 54 and larger-area structures with a single exposure mask in a single exposure process for a particularly minimal exposure time t.

An overall imaging system comprising in particular the imaging optics 20, the material 16 and optionally the radiation-transmissive plate 48 defines a transfer function for the intensity as a function of the location x. In 6 the intensity distribution is shown schematically with hatching 58, for example directly after a micromirror unit or an LCD transmitted light mask. Due to the transfer function of the overall system, there is a reduction in intensity and a smeared intensity distribution in the construction level, which is identified by hatching 60. In other words, this means that a pixel line pair can only be imaged by the overall system with a modulation transfer function of less than 50% due to optical errors.

The contour line 56 surrounding the large surface area as described has the particular advantage that the object 12 can have a smooth, sharp surface overall.

The exposure textures 52 used can in particular be designed in such a way that different, so-called “degrees of filling” arise overall. In particular, this means that the respective “degree of filling” corresponds to an exposure reduction value, which is a measure of how much the total energy input into an area is reduced. In the 7 The surface patterns 52a to 52g shown schematically represent corresponding exposure attenuation values which are given as percentages for each exposure texture 52a to 52b by way of example. The respective percentage number thus indicates the portion of the pixels with the bit value 34 “not permeable” in the respective exposure texture 52a to 52g.

It is advantageous if the pixels with the bit value 34 “non-transmissive” are evenly distributed in the respective exposure texture 52a to 52g. The pixels with the bit value 34 “non-permeable” are preferably each arranged individually, ie along their longitudinal edges they always border on pixels to which the bit value 32 “permeable” is assigned. Such a configuration of exposure textures 52a to 52g has the particular advantage that an intensity distribution of the radiation 14 in the image/construction plane 22 is homogenized and averaged by the described optical transfer function of the overall system. In other words, even large surface areas are exposed in the desired manner, although they are filled with an exposure texture 52, and achieve the necessary through-hardening depth, which is also achieved for filigree structures 54.

In order to increase the stability of object 12 overall, exposure textures 52 of exposure masks 30 for exposure of successive object layers are preferably arranged offset relative to one another by an integer number of pixels, preferably by 1 pixel, in a plane parallel to image/construction plane 22 . This is schematic in 8th for object layers 62a through 62d, each of object layers 62a through 62d corresponding to an exposure area defined by exposure mask 30.

Complex cross-sectional areas of objects 12, as in 9 shown schematically on the left, can be subdivided into surface areas 66a, 66b and 66c of different sizes. The surface areas 66b and 66c are in the in 9 illustrated schematic example greater than, for example, a predetermined limit structure size. The surface area 66a is correspondingly smaller than the predefined limit structure size. Therefore, the surface area 66a, which forms a filigree structure, is not filled with an exposure texture, but a bitmap 30 is used, as shown by way of example in 9 shown on the right, is chosen in which the area 66a is completely filled with pixels with the bit value 32 “transparent”. The areas 66b and 66c are preferably completely surrounded by an outer border line 56, which ideally has a width of at least 2 pixels. In order to achieve an intensity distribution that is as homogeneous as possible and a hardening depth that is as homogeneous as possible for all surface areas of the object layer to be formed, surface area 66b is filled with exposure texture 52e, for example, and surface area 66c with exposure texture 52c. The energy input from surface area 66b is thus reduced by an average of 20%, and the energy input in surface area 66c by an average of 50%.

Of course, the division into surface areas can be further refined in an analogous manner, even with more complex cross-sectional areas of the object 12, and the appropriate exposure texture 52 can be selected according to their size in order to achieve the most homogeneous possible distribution for the through-hardening depth.

Furthermore, as already mentioned at the beginning, a problem to be solved is an inhomogeneous intensity distribution of the radiation 14 generated by the radiation source 18. If, for example, only a central area of a construction field in the image/construction plane 22 is used, then in a plane parallel to the Image/construction level 22, for example, an intensity distribution as in 10 shown schematically. The intensity of the radiation 14 is thus at its highest in the center of the construction area. However, the intensity of the radiation decreases continuously towards the edge of the construction area. In 10 the intensity is plotted schematically on the vertical axis, the expansion in a plane parallel to the image/construction plane 22 of the radiation field forms an xy plane.

If, for example, only the middle area of the construction field is used to form an object layer, which corresponds to the area of the maximum and most uniform intensity distribution of the radiation 14, this area does not have to be at the lowest intensity value, which is usually in the corners of the radiation field , to be pressed. Valuable exposure time can be gained in this way and the construction time for forming the object 12 can thus be reduced. With appropriate image processing software running on the computer 38, an exposure mask can then be controlled individually for each object layer by the calculated 2-bit bitmap 30, which manages with the smallest exposure attenuation values in order to cover the respective cross-sectional area of the object in the shortest possible time expose. This effect is in the 11 and 12 shown schematically.

In 11 it is taken into account that the structure 68 to be exposed is exposed exclusively in the area of the two highest intensity levels, which are symbolized by the dotted circles. Therefore, the exposure level is adjusted to the lowest of these two intensity levels. This means that the surface areas 66a can be assigned pixels with the bit value 32 "transmissive", and only the surface area 66b, which is in the area of the radiation field with the highest intensity in the range between 55 and 60, by filling in, for example, with the Exposure Texture 52f is softened by 10%.

In contrast, the exposure mask is 30 in 12 , when the exposure is matched to corners of the image field, for example exposure texture 52f for areas 66a and exposure texture 52d for area 66b. In other words, without taking into account that exposure only takes place in the center of the radiation field generated by the radiation source 18, a darkening is significantly greater, as a result of which the exposure time of this object layer increases significantly, in the case of the in FIGS 11 and 12 brands 30 shown schematically, for example, by 20%.

In order to improve the surface quality of the object 12, it is advantageous if, in particular, scattered light effects in the edge area of structures are also taken into account. If, for example, a circular structure 72 is completely exposed, i.e. the bit value 32 “transmissive” is assigned to all pixels of the associated 2-bit bitmap 30, strong scattered light effects result in the edge area, as is shown schematically in 13 shown. The scattered light 70 surrounds the circular structure 72 in the manner of a corona and leads to undefined edge areas of the exposure.

In order to compensate for these disadvantages, a contour line 74, which delimits the respective cross section of the structure 72 on the outside, is separated from the rest of the planar structure by a separating line 76. In this way, scattered light effects, as in 14 shown schematically, significantly reduce. A clearer delimitation of a surface area can be achieved by the contour line 74 . The contour line is preferably 2 to 8 pixels wide, 2 to 4 pixels are advantageous.

Optionally, connecting lines 78 can be provided, which interrupt the dividing line 76 and connect the contour line 74 to the planar structure 72 in order to ensure the required stability of the object 12 overall. Particularly in the case of dividing lines 76 with a width of no more than 8 pixels, these connecting lines 78 have hardly any effect on the reduction in scattered light achieved by the dividing line 76 .

As already explained in the introductory part, two or more separating lines 76 can also be provided, which then run parallel to one another and are each separated from one another by a continuous contour line. Likewise, the arrangement of a dividing line described in the area of an outer contour of a structure 72 can be provided in the case of recesses in an object layer, ie in the case of non-exposed structures. These can then be surrounded on the outside by a contour line 74, which in turn is surrounded by a dividing line 76 in order to delimit the recess from a larger structure to be exposed and to minimize the occurrence of scattered light. In particular, in the case of small recesses in an object layer, it is only possible in this way to form them with the desired dimensions at all.

To improve the outer and inner surfaces of the object 12, the device 10 can optionally include an oscillating device 80. This can, as shown schematically in 2 shown to be coupled to the imaging optics 20 . Alternatively, it is also possible to couple this to the plate 48 or the carrier plate 42 . It is also conceivable to couple the mask unit 24 to the oscillation device 80 . The oscillation device 80 is preferably designed in the form of a mechanical oscillation device 80 in order to achieve an oscillating exposure in the image/construction plane 22 .

The oscillation device 80 is preferably designed to superimpose an oscillation of the exposure in an x and/or a y direction in a plane parallel to the image/construction plane 22. The oscillation range is preferably in a range of less than 1 pixel, ideally it is 0.25 pixels. This can, as shown schematically by the arrow 82 in the 15 and 16 shown, a circular movement of the radiation field predetermined by the mask unit 24 can be realized in the image/construction plane 22 relative to the object layer formed last. In this way, there is a partial superimposition during exposure in the contour area. If, for example, one or more oscillation cycles are carried out during the exposure time of an object layer, then all outer and inner corners and edges are rounded off with the corresponding radius of the circle defined by the oscillation.

In particular, the oscillation device 80, as shown schematically in 17 shown comprise a plane-parallel disk 86 which rotates about an axis of rotation 84 which is inclined at an angle of 90° or substantially 90° relative to the image/construction plane 22 . However, the pane 86, which defines a pane plane 88, is inclined in relation to the image/construction plane 22 in such a way that the pane plane 88 encloses an angle 90 deviating from 90° with the axis of rotation 84. Due to the rotation of the disk 86, as in 17 shown schematically, a circular movement, symbolized by the arrow 82, of the radiation field specified by the mask unit 24 in the image/construction plane 22 relative to the object layer formed last is realized, specifically due to the refraction of the radiation 14 at the pane 86.

The oscillation device 80 thus makes it possible, in particular, to achieve edge smoothing in the sub-pixel region with a single exposure mask 28 by oscillating, for example, the same or the carrier plate 42 during a single exposure cycle. In particular, the plane-parallel glass pane can be arranged in the beam path between a digital micromirror unit and the imaging optics 20 or between the imaging optics and the image/construction plane 22 . In contrast to what is described in the prior art, multiple exposure is therefore not necessary. Rather, a deliberately unsharp imaging is performed with a single exposure mask without brightness control of the individual pixels by the oscillation in order to achieve edge smoothing. This procedure requires no additional computing effort, since no further bitmaps with pixel offsets have to be calculated, as is known, for example, from the prior art.

Claims (18)

Method for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28), wherein for forming each object layer (62) of the object (12) to be solidified in a Build level (22) at least one exposure mask (28) is produced, by means of which the radiation (14) is projected selectively into the build level, characterized in that each exposure area, which defines a cross-sectional area of the object, in each exposure mask (28) has a a closed outer contour line (74) is assigned to delimit the exposure area, that the pixels for forming the contour line (74) are assigned the bit value (32) "transparent", that each exposure area in each exposure mask (28) has an inside on the contour line (74) adjacent dividing line (76) is assigned and that the pixels for forming the dividing line (76) are assigned the bit value (34) " not permeable” is assigned. procedure after claim 1 , characterized in that a width of the contour line (74) and/or the dividing line (76) is at least 2 pixels, in particular in a range from 2 to 8 pixels, preferably in a range from 2 to 4 pixels. procedure after claim 1 or 2 , characterized in that each exposure mask (28) is assigned a separating line (76) for those surface areas (66b, 66c) whose structural size has a width and/or length which is at least twice the width of the contour line (74) . Method according to one of the preceding claims, characterized in that a single exposure mask (28) is produced in a construction level (22) in order to form each object layer (62) of the object (12) to be solidified. Method according to one of the preceding claims, characterized in that for forming each object layer to be consolidated (62) of the object (12) in a construction level (22) a digital exposure mask (28) is produced. Method according to one of the preceding claims, characterized in that a single 2-bit bitmap (30) is calculated for each exposure mask (28) as a function of the object layer (62) to be solidified, which bitmap each pixel of the exposure mask (28) either -value (32) "permeable" or the bit value (34) "not permeable" assigns that at least one surface area (66a) of the 2-bit bitmap (30) with a structure size below a limit structure size has the bit value (32 ) is assigned “transparent” and that each area (66b, 66c) above the limit structure size is assigned an exposure texture (52), which exposure texture is in the form of a pattern of pixels with the bit values (32) “transparent” and (34) “ not permeable”. Method according to one of the preceding claims, characterized in that the building plane (22) is illuminated in an oscillating manner during an exposure time. Exposure mask generating device (26) for a device (10) for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28), which device (10) has a radiation source ( 18) for generating the radiation (14) and the exposure mask generating device (26), which exposure mask generating device (26) generates at least one exposure mask (28) for forming each object layer (62) of the object (12) to be solidified in a construction level (22), by means of which the radiation (14) is projected selectively into the building plane, characterized in that the exposure mask generating device (26) is designed to assign a self-contained outer contour line (74) to delimit the object layer (62) and an inner contour line ( 74) directly adjacent dividing line (76) to each exposure mask (28), wherein the Pixels for forming the contour line (74) are assigned the bit value (32) “transparent” and the pixels for forming the dividing line (76) are assigned the bit value (34) “non-transparent”. Exposure mask generation device according to claim 8 , characterized in that a width of the contour line (74) and/or the dividing line (76) is at least 2 pixels, in particular in a range from 2 to 8 pixels, preferably in a range from 2 to 4 pixels. Exposure mask generation device according to claim 8 or 9 , characterized in that the exposure mask generating device (26) is designed to assign a separating line (76) to an exposure mask (28) for those surface areas (66b, 66c) of the same whose structure size has a width and/or length which is at least twice as large is like a width of the contour line. Exposure mask generation device according to one of Claims 8 until 10 , characterized in that the exposure mask generating device is designed to generate a single exposure mask (28). Exposure mask generation device according to one of Claims 8 until 11 , characterized in that the exposure mask generating device is designed to generate a digital exposure mask (28). Exposure mask generation device according to one of Claims 8 until 12 , characterized in that the exposure mask generation device (26) comprises a computing unit (38) and that the computing unit (38) is designed a) to calculate a single bitmap (30) for each exposure mask (28) as a function of the object layer (62) to be solidified and/or b) for calculating a bitmap (30) in the form of a 2-bit bitmap (30) for each exposure mask (28) depending on the object layer (62) to be solidified and/or c) for calculating a single 2-bit -Bitmap (30) for each exposure mask (28) depending on the object layer (62) to be solidified, which 2-bit bitmap (30) each pixel of the exposure mask (28) either the bit value (32) "transparent" or the assigns bit value (34) "non-transmissive", assigning bit value (32) "transmissive" to each area (66a) of the 2-bit bitmap (30) with a feature size below a threshold feature size, and assigning an exposure texture (52) to each area (66b, 66c) or similar Above the feature size limit, exposure texture (52) is in the form of a pattern of pixels with bit values (32) “transparent” and (34) “non-transparent”. exposure mask generator Claim 13 , characterized in that the arithmetic unit (38) is designed a) to assign an exposure texture (52) which has at most as many pixels with the bit value (34) “not transparent” as pixels with the bit value (32) “ permeable" and/or b) for assigning an exposure texture (52) which has an exposure attenuation value, which is greater than 0 and has a maximum of 0.5, and/or c) for assigning an exposure texture (52) to each surface area (66b, 66c) with a structure size above the limit structure size depending on its structure size, with the exposure attenuation value of the Exposure texture (52) increases, and/or d) for arranging identical exposure textures (52) of exposure masks (28) for exposure of successive object layers (62) in a plane parallel to the construction plane (22) offset by an integer number of pixels relative to one another, preferably by 1 Pixels in an x and/or y direction of the plane parallel to the construction plane (22), and/or e) for the exclusive use of exposure textures (52), in which at most corners of pixels with the bit value (34) "not permeable" meet, but no longitudinal edges of pixels with the bit value (34) "non-permeable" are adjacent to each other. Exposure mask generation device according to Claim 13 or 14 , characterized in that the exposure mask generating device (26) a) provides different texture patterns for the formation of the exposure textures (52), which have a ratio of pixels with the bit value (34) "non-transparent" and pixels with the bit value (32 ) have “transparent”, which are in a range between 0 and 1, and/or b) provides each exposure texture (52) in the form of hatching or a regular pattern and/or c) is designed to provide exposure textures (52), which can be converted into itself by a translation in a plane parallel to the construction plane (22), the translation being defined in particular by a vector which has a length of n pixels in an x-direction and m pixels in an x-direction Direction does not correspond to a parallel y-direction, where n and m are integers, and/or d) is designed to provide exposure textures (52) which are screened pixel by pixel. Device (10) for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28), comprising a radiation source (18) for generating the radiation (14) and an exposure mask generating device (26), characterized in that the exposure mask generating device (26) is designed in the form of an exposure mask generating device (26) according to one of Claims 8 until 15 . device after Claim 16 , characterized in that an oscillation device (80) is provided for the oscillating exposure of the building plane (22) during an exposure time. Use of a device (10) according to Claim 16 or 17 for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28) for carrying out a method according to one of Claims 1 until 7 for producing a three-dimensional object (12) by layer-by-layer solidification of a material (16) that can be solidified under the action of radiation (14) using exposure masks (28).

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