EP3247552A1

EP3247552A1 - Method for exposing a three-dimensional region

Info

Publication number: EP3247552A1
Application number: EP16700227.8A
Authority: EP
Inventors: Andreas FITZINGER; Simon Gruber
Original assignee: Way To Production GmbH
Current assignee: Way To Production GmbH
Priority date: 2015-01-22
Filing date: 2016-01-12
Publication date: 2017-11-29
Also published as: US20180001562A1; AT516769A1; AT516769B1; CA2973174A1; WO2016116320A1

Abstract

The invention relates to a method for exposing a three-dimensional region (1), wherein the three-dimensional region is divided into at least two successive layers (2) which are exposed in chronological order, wherein each layer (2) is divided into at least two exposure fields (3) having at least a first part-region (4), a second part-region (4'), optionally a third part-region (4''), and optionally further part-regions, wherein adjacent exposure fields (3) overlap in individual part-regions (4', 4'' prevent) in order to avoid incorrectly exposed areas.

Description

Method for exposing a three-dimensional area

The invention relates to a method for exposing a three-dimensional area.

So-called 3D printing methods are known from the state of the art for forming a dimensionally stable object by exposure of a three-dimensional region of a non-dimensionally stable mass. In these methods, a powdery or liquid substance is selectively cured by the action of light or heat radiation in a three-dimensional region, thereby forming a solid body. For this purpose, the three-dimensional area is subdivided into at least two adjoining layers, which are exposed in time sequence with a predetermined exposure intensity. The exposure hardens the substance and becomes dimensionally stable, so that one layer after the other can be exposed.

A problem of such methods is that the available optical

Exposure field is limited by the optical exposure system used and the resolution used. In order to be able to expose areas which are larger than the optical exposure field at a given resolution, it is known to coat each individual layer in at least two exposure fields with adjacent ones

Subdivide sections. The entire layer information is generated by temporally successive exposure of several sub-areas.

A problem with these known methods for exposure of large areas is that in the edge areas, in which adjacent portions

may collide, or due to improper alignment, either an overlap or a gap in the exposure intensity may arise. This manifests itself in over-exposure in these areas, resulting in over-curing, or too little or no exposure, resulting in a lack of cure. In addition, since the incorrect alignment usually remains the same from layer to layer, this error manifests itself in a clearly visible interface in the object to be produced, which in particular also appears as undesired geometric inaccuracy, seam or breakage. The object of the present invention is to provide a method in which this false exposure (over-, under- or unexposure) is avoided, and which makes it possible to easily expose three-dimensional areas which are larger than the available exposure field are to avoid the formation of seam and break points at the boundaries of the sub-areas.

The object according to the invention is initially achieved by overlapping adjacent exposure fields in individual subregions. This avoids gaps being created between the exposure fields in which there is no or one

reduced curing takes place. For example, rectangular arrangement of

Subregions takes place an overlap of two sections at the edges, and an overlap of four sections at the corners.

The shape and design of the overlapping subregions can be arbitrary according to the invention. The overlapping partial regions can in particular assume rectangular, triangular or other geometric shapes. In particular, in the exposure of irregular structures can be provided according to the invention, the use of non-rectangular overlapping portions.

According to the invention, it may also be provided to allow an overlap of an arbitrary number of partial areas in order to achieve the fastest possible exposure of the entire area, wherein the exposure intensity in the overlapping partial areas is adjusted accordingly in order to achieve a target value of the exposure intensity in the overlapping partial areas.

According to the invention, the extent of the overlapping partial regions can be added

pixel-based exposure depending on the resolution used and may preferably be at least one to five pixels.

To avoid overexposure in the overlapping areas can

According to the invention, the mean exposure intensity in the overlapping partial areas is lower than in the non-overlapping partial areas. In the simplest case, in each case, for example, only half the exposure energy and / or half are used in the overlapping partial areas

Exposure time of the predetermined target value exposed. In total, this results in the overlapping partial areas of the target value of the exposure intensity.

This can according to the invention by the direct driving of the pixels in the

overlapping partial areas by means of pulse width modulation, or by using a partial gray level in the overlapping area. Depending on the number of exposure fields, a plurality of overlapping regions may be provided and thus several partial intensity values per individual image may be necessary.

Depending on how many sub-areas of the overlap is performed, the exposure intensity in these areas is reduced accordingly to the

to achieve the intended exposure intensity. In particular, it may be provided that only half the intensity is exposed at the edges of a subarea, and only one quarter of the intensity of the non-overlapping region at the corners. When overlapping any number of

Partial areas, the exposure intensity in these areas on a

corresponding fraction of the exposure intensity in the non-overlapping partial area can be reduced in order to achieve the target value of the exposure intensity in total in the overlapping partial areas.

According to the invention, it may further be provided that the exposure intensity in the overlapping subregions of adjacent layers is different. In particular, it can be provided that the exposure intensity in the overlapping

Subareas varies from layer to layer. This has the advantage that, even if the resulting intensity and the exact shape of the overlapping area can not be adjusted accurately, no seam that passes through the entire formed object is produced, which would subsequently appear as a breakage point or a geometrical inaccuracy.

According to the invention, it can further be provided that the exposure intensity in the overlapping partial regions varies in one or two spatial coordinates of the layer, so that the exposure intensity in these regions is location-dependent. As a result, an arbitrary energy curve can be realized in the overlapping partial regions of the exposure field. This can be achieved in particular that, for example, in the interior of the object to be exposed another

Exposure intensity or a different course of the exposure intensity is achieved than at the edge of the object to be exposed.

According to the invention, it may further be provided that a locally constant exposure intensity is provided in individual overlapping partial regions, and a spatially variable illumination intensity is provided in other overlapping partial regions. For example, in the corners of a subarea a constant exposure intensity, and in the edges of a variable in the x or y direction

Exposure intensity may be provided, where x and y are the two-dimensional

Designate location coordinates of a layer. The exposure intensity can also vary in this two-dimensional area around the respective target value of the intensity.

According to the invention, it can further be provided that the exposure intensity in the overlapping subareas at a point of the exposure field, ie a fixed x and y coordinate, varies along successive layers by a slice-dependent target value. This has the advantage according to the invention that along

averaging the target value of the exposure on average, even if the exposure fields and overlapping areas are not set completely precisely, so that the formation of a seam along the layers is completely avoided.

According to the invention, it can be provided that the variation around the slice-dependent target value amounts to at least 5%, preferably at least 10%, of the target value.

According to the invention, it can further be provided that the exposure fields are exposed simultaneously. According to the invention can also be provided that the

Exposure fields are exposed in chronological order.

According to the invention, it may further be provided that a plurality of exposures of the same or different intensity are performed in chronological order.

For example, first the entire exposure field with a basic intensity, and then selected subregions at least once with an additional

Intensity are exposed. According to the invention, it may further be provided that the exposure takes place continuously, by passing an exposure field in constant or variable speed over the area to be exposed, wherein the projected exposure pattern is changed continuously. For example, the exposure pattern may be played in the form of a continuous projection or a video, and that

Exposure field to be moved in a coordinated speed.

Other features of the invention will become apparent from the claims, the drawings and the description of the figures.

The invention will be explained in more detail below with reference to non-exclusive embodiments.

Fig. 1 shows a schematic representation of the area to be exposed and a section of a layer to be exposed;

Fig. 2 shows a schematic representation of four overlapping exposure fields and a single exposure field with a plurality of partial regions;

3 shows a two-dimensional representation of an exposure field and courses of the exposure intensity along given interfaces;

4 shows a schematic representation of the course of the exposure intensity in two points of the exposure field along successive layers;

FIGS. 5a-5c show further schematic representations of a device according to the invention

Embodiment.

1 shows a schematic representation of the three-dimensional region 1 to be exposed. This is subdivided along the z-axis into successive layers 2, which are designated by way of example as a, b, c. During exposure, the layers are processed in sequence and the object to be exposed 5 is generated layer by layer.

In the right-hand area of FIG. 1, a layer 2 to be exposed is shown schematically. The layer 2 comprises four rectangular exposure fields 3 arranged in a rectangle lying adjacent to one another, which are indicated by broken lines. The object 5 to be developed is located inside the layer 2. At the separation points between the individual exposure fields 3, geometrically exactly matched exposure fields form the schematically represented seams 6, the avoidance of which represents one of the objects of the present invention.

Fig. 2 shows a representation of the four exposure fields 3, which overlap in their edge regions. One of the exposure fields is highlighted by way of example and shown in the right part of FIG. 2. The exposure field 3 comprises first, second and third subregions 4, 4 ', 4 ", wherein the first subregion 4 does not overlap with other exposure fields, the second subregion 4' overlaps with another exposure field, and the third subregion 4" with three other exposure fields overlaps. Accordingly, the exposure intensity in the first, second and third subregions 4, 4 ', 4 "is different in each case.

3 shows a schematic representation of an exposure field 3 and the course of the exposure intensity I along the x-coordinate in the layers a, b and c at the y-coordinates y1 and y2. Also indicated is the profile of the object 5 to be exposed, the exposure intensity outside of this object 5 generally falling to zero.

As an example, the course of the exposure intensity I in layer a is shown. The exposure intensity is initially 0.25 along the y-coordinate y1, since four exposure fields overlap in the sub-area 4 ", the intensity increases to 0.5 since the x-coordinate xa, since two exposure fields overlap in the sub-area 4 '. Coordinate y2, the exposure intensity is initially 0.5, since two exposure fields overlap in the subarea 4 'From the x coordinate xa, the intensity increases to 1, since no exposure fields overlap in the subarea 4.

For the layers b and c, further courses of the intensity I are shown by way of example. Thus, the intensity in the x direction can increase linearly, nonlinearly or in a composite manner up to the coordinate xa with a different gradient, as shown for layer b. The intensity may also initially be high, and then linearly, nonlinearly or exponentially decay in the x direction, as exemplified for layer c. A linear or non-linear course of the intensity in the y-direction can also be provided according to the invention. The respectively selected courses of the intensity depend on the respective task.

4 shows by way of example a profile of the exposure intensity in the direction of the z-coordinate along the layers 2 at the fixed positions x1, y1 (in the partial area 4 ") and x1, y2 (in the partial area 4 ') within the overlapping areas of one

Exposure field 3. The exposure intensity 11, 12 is selected such that it varies by the respectively required target value at this point, so that even with incorrectly set overlap of the partial areas 4 ', 4 "the formation of seam lines is avoided, and on average along the layers the exposure intensity is correct at this point.

Fig. 5a shows a schematic representation of an inventive

Intensity curve in four successive layers a, b, c and d, each having two first non-overlapping portions 4, and a second, overlapping

Part 4 'have. The local course of the exposure intensity in the layers a, b, c and d is denoted by la, Ib, Ic and Id and follows in each case essentially a bell-shaped or Gaussian profile, wherein according to the invention also any other courses can be provided. In order to prevent the maxima of the intensity in each layer from being at the same x position, the Gaussian shape in each layer is shifted with respect to the adjacent layers.

Fig. 5b shows the same layer arrangement, wherein in each layer with a point the maximum of the intensity is indicated. Since the maxima in adjacent layers always come to rest at different x-positions, the formation of a straight seam is avoided, so that the joining together of the adjoining partial regions 4 and the superimposed layers a, b, c, d

is favored. Fig. 5c shows a further schematic representation of an inventive

Intensity curve in three juxtaposed sub-areas n, n + 1 and n + 2 with overlapping portions 4 '. In the overlapping partial regions 4 ', the exposure intensity of each partial region 4 is linearly reduced to zero, so that by adding the intensity in the overlapping partial regions, the target value of the

Exposure intensity results. According to the invention, any other courses of the exposure intensity can also be provided.

The invention is not limited to the present embodiments but includes all methods within the scope of the following claims. In addition, the invention also extends to the three-dimensional objects generated by using the method.

Claims

claims

1 . Method for exposing a three-dimensional area (1), wherein the

divided into at least two successive layers (2), which are exposed in time sequence, each layer (2) in at least two exposure fields (3) with at least a first portion (4), a second portion (4 '), optionally a third sub-area (4 ") and possibly further sub-areas is divided, thereby

characterized in that adjacent exposure fields (3) in individual

Overlap partial areas (4 ', 4 ") to avoid missing areas.

2. The method according to claim 1, characterized in that to avoid

overexposure the average exposure intensity in the overlapping subregions (4 ', 4 ") is lower than in the non-overlapping subregions (4).

3. The method according to claim 2, characterized in that the

Exposure intensity in the overlapping portions (4 ', 4 ") of adjacent layers (2) is different.

4. The method according to claim 3, characterized in that the

Exposure intensity in the overlapping partial areas (4 ', 4 ") varies in one or two location coordinates, so that the exposure intensity in these

Areas is location dependent.

5. The method according to claim 3 or 4, characterized in that in individual overlapping subregions (4 ') a locally constant exposure intensity is provided, and in other overlapping subregions (4 ") a locally variable exposure intensity is provided.

6. The method according to any one of claims 3 to 5, characterized in that the exposure intensity in the overlapping subregions (4 ', 4 ") at a point of the exposure field (3) along successive layers (2) varies by a layer-dependent target value.

7. The method according to claim 6, characterized in that the variation is at least 5%, preferably at least 10% of the target value.

8. The method according to claim 6 or 7, characterized in that the variation in a second portion (4 ') is lower than in a third portion (4 ").

9. The method according to any one of claims 1 to 8, characterized in that the exposure fields (3) are exposed simultaneously.

10. The method according to any one of claims 1 to 8, characterized in that the exposure fields are exposed in chronological order.

1 1. Method according to one of claims 1 to 10, characterized in that the partial areas (4, 4 ', 4 ") have a substantially rectangular shape.

12. The method according to any one of claims 1 to 10, characterized in that the partial areas (4, 4 ', 4 ") have any geometric shape.

13. The method according to any one of claims 1 to 12, characterized in that an arbitrary number, preferably two or four, subregions (4 ', 4 ") overlap, wherein the exposure intensity in the overlapping subregions is adjusted accordingly to in the overlapping subregions to achieve a target value of the exposure intensity.

14. The method according to any one of claims 1 to 13, characterized in that in individual or all subregions (4, 4 ', 4 ") a plurality of exposures of the same or different intensity are performed in chronological order.

5. The method according to any one of claims 1 to 14, characterized in that the exposure is carried out continuously by an exposure field in constant or variable speed over the area to be exposed, wherein the projected exposure pattern is continuously adjusted.

A three-dimensional object generated using a method of exposure according to any one of claims 1 to 15.