Rapid prototyping apparatus and method of rapid prototyping

BACKGROUND OF THE TECHNIQUE

The invention relates to a so-called rapid prototyping device for producing three-dimensional objects by additive treatment of cross-sections of the three-dimensional object that entirely a or partially light-sensitive or light-sensitive material , wherein the device comprises at least a light source, as set out in the preamble of Claim first

The invention also relates to a method for producing three-dimensional objects by means of a rapid prototyping device, in which a completely or partially light-sensitive material of at least one light source is treated, at least a cross-section of the material with a spatial Light modulator arrangement of individually and individually controllable Light modulators illuminated, as in the preamble of claim 15 forth.

BACKGROUND THE INVENTION

In connection with the preparation of mechanical prototypes, and especially during the production design processes or production design processes, have been in recent years various Types of rapid prototyping techniques (RP) introduced, in which three-dimensional objects by sequential cross-sectional layers be prepared, by a given illumination, sintering, Setting or depositing material, etc. generated at each cross-section will. The individual cross sections, for example, as computer-aided design (computer-aided-designs) generated. The advantage of RP is that the manufacturing of expensive molds for the design or the design of the device for their preparation is superfluous, just as difficult and time-consuming modifications of a molding tool almost complete can be avoided.

Additionally, a multitude were techniques for the production of a relatively inexpensive and fast prototype or initial series molds based on a prepared Rapid prototype available made.

One type of RP technique is used for example in stereolithography devices, which are also called SLAs, Use. This technique is based on the individual layers or cross sections of a prototype, the photosensitive of a Medium is prepared, and by means of a computer-aided illumination is cured in a monolithic prototype.

Apparatus and techniques of the above mentioned Type are described for example in US Patent Number 4,575,330, in which certain of the cross section of illumination as a laser drawing each cross-section or a screening mask is described, the desired cross-section exposed.

Meanwhile, one of the disadvantages the aforementioned System is that the distribution of light over the cross section, the design flexibility of the system limited, since settings of existing lighting sources on certain limited system dimensions are.

Consequently, it is in the preparation of large models scale required a given desired prototype into several to divide prototype parts, these parts individually in separate runs produce, and then eventually the prototype by joining the parts to be completed by, for example, gluing.

However, this process involves a significant risk that technical problems and complications occur. It is necessary that, for example, minor problems for considered each prototype part be because the tolerance level between adjacent prototype parts differs from the tolerance levels that between each of the prepared layers are present, comprising the individual prototype parts. Meanwhile, this can be prevented by the proper precautions be made in relation to the illumination algorithms or by an actual mechanical manufacturing of the individual prototype parts if necessary. This compensation strategy would in particular the "vertical plane" difficult and may For example, both in under- and overexposure and consequently to tolerance or connection failures between the individual layers of lead.

Furthermore, in connection with the Bonding of prototype parts problems occur because the curing of cause adhesive contraction or expansion in places may, at which place the adhesive use. These changes during the curing would often have a nonlinear character and would therefore be difficult to estimate in advance or predict.

Another problem is that this compound generally cause stability problems, when they at large models scale be used.

An additional and important or significant problem is that common RPA materials (Materials for Rapid prototyping devices), such as acrylic acid ester and epoxy quite dangerous are what manual runs undesirable power. In this connection it should be mentioned that the compound the individual prototypes must be done manually, which is to the costs added and designed working conditions difficult. Furthermore designed to encapsulation of the device, due to be executed manual labor, such as <?page 3?>according to the foregoing described methods for producers even more difficult to carry out their work. This Problem is in relation to the use of, for example dangerous or directly toxic materials even more obvious.

Finally, it should also be mentioned that the known method is quite time consuming, which dependent the size of the prototype many hours and sometimes includes several days.

<patcit><text>EP 0676275</text></patcit> discloses a DMD-based stereolithography Device, that a plurality of lighting modules, wherein each Module comprises an assigned or dedicated light source. By Change the number of modules used may be of any size and shape the lighting head can be obtained. However, the device has the disadvantage in that it voluminous and is quite expensive. In addition, the mutual variation results of the light sources in a different degree of illumination of the various illuminated subregions and consequently in both underexposure and overexposure of both the vertical and the horizontal plane of the illuminated surface.

A problem of the illustrated System, however, is that the system in accordance with a size Number of illumination sources requires, 1-to-1 and that the uniformity lighting by example, a non-uniform adjustment the different applied illumination sources are at risk can.

<patcit><text>US 4575330</text></patcit> discloses a rapid prototyping device with an illumination system for illuminating a light-sensitive adapted medium. The disclosed system is to the effect configured to generate a three-dimensional object so by successive, adjacent, thin Cross-sectional laminae of that object at the surface of liquid Medium are formed, the response to appropriate synergistic Stimulation is able to change its physical state. On Problem of the illustrated system is that the illumination system includes a single-point illumination head, whereby a fairly time consuming illumination procedure is caused, in particular if it is large scale rapid prototyping.

<patcit><text>US 4801477</text></patcit> discloses a rapid prototyping with a single source illumination system as a special feature an optical guide or an optical having conductors at the output of the modulator used. On Problem of the illustrated system is that due the use of a single illumination modulator not for a large scale use can be extended.

The aim of the invention is to create an RP technique and an RP apparatus for the production can be used, for example, large-scale prototypes, while also the object of the invention, a design system to provide that in applied with respect to the design of various types of RPA systems can be without significant or significant design modifications required are.

THE INVENTION

The invention relates to a Rapid prototyping apparatus for the Producing three-dimensional objects by additive treatment of cross-sections of the three-dimensional object that entirely a or partially light-sensitive or light-sensitive material , wherein the device has at least one light source for illuminating of a cross section of the light-sensitive material having at least one spatial Light modulator arrangement of individually and individually controllable comprises light modulators, wherein at least one light source optically with a plurality of light guides is coupled or light conductors in view of the spatial Light modulator array are arranged in such a manner, that each light guide a Subregion of the section illuminated.

Particular embodiments of the rapid prototyping apparatus according to the invention are the subject of the dependent claims 2 to 14.

The invention provides the possibility to disposal, a given RP system for handling prototypes of any to design size, since the number of light emitters and thereby individual to be covered increased areas can be reduced or, until the size of the issue Prototype match, as the same illumination source of at least two different Subregions can be shared. In this way, it is possible and easy to design a lighting system for an RP system, that as a module system having a number of illumination modules is constructed, the suitable added with respect to the system design, or can be arranged. This flexibility can, in principle, for both the design or the design of RPs for large-scale prototypes as also for more customer-oriented RPs for Small scale models be used.

In addition, the multiple filters Light emitters the opportunity to disposal, to use light sources in the form of dots. By using a system according to the invention Is it possible, such a small diameter of the dot-shaped illumination point as 10 μ to obtained in comparison with the existing technology with a nadir of 80 μ. This means a large Advantageous when prototypes are produced, in which high precision properties required are. This example includes the manufacture of&lt;?page 4?&gt;tools, in which the prototype after preparation with a metal coating or coating is provided before for molding a tool is used.

Certain areas of this technology set a prolonged or extended light source such as a fluorescent Lamp or an excimer lamp in order to be able, prototypes to produce in a certain dimension. However filters, according to the optical Laws extended, Light sources alone only option to disposal, an extended to create and spread illuminating point, which in turn the Potential for making of details and details in the prototype significantly limited. additionally subject to extended Light sources relatively large Losses.

According to the invention is the definition of light broad and includes electromagnetic radiation, both inside and outside the visible spectrum.

Alternatively need in conjunction with the extended Light sources quite a few optical instruments are used, to adjust the shape of the illumination point. naturally, designed so the system more expensive, while also a high degree of accuracy is required when the optical instruments monitored will.

The multiple or many light emitters questions also the possibility to disposal, the lighting effect on to increase the illuminated cross section, since each area by illuminates a single light emitter or even an illuminant can be. This constitutes an advantage, since it becomes possible to the illumination effect to the individual prototype in such a Way measure tailoring, that it is provided with optimal lighting effect.

is as specified in claim 1, is it by lighting the subregions possible an effective amount the number of sub-regions to acquire.

A particular advantage of an illumination system according to the invention is also in that the illumination of the sub-areas, the possibility to disposal represents, subregions to design separate lighting modules, which can be exchanged easily, since the individual lighting modules can be aligned with each other or together.

This should, under the light of the fact be considered that the lighting modules to a wide variety in terms RP technologies must be considered quite vulnerable because the Lighting system will be permanently damaged when it is brought into contact with certain types of media, which is why the ability to Creating a fairly simple process to replace the lighting normally desirable is.

In addition, have a number of existing lighting technologies a limited useful life on. This includes the LCD-based light valves where the strong light excitation, in particular with UV light, a risk of gradual Defect of the active crystals has the result that also in the micromechanical turnkey the case wherein in accordance with a embodiment the invention is expected that the micromechanical normally a limited have number of on / off switches.

Treatment is in its broadest Meaning defined and includes, for example curing or decomposition of the photosensitive Material.

As specified in claim 2, there by allowing each spatial Modulator arrangement translucent comprises light valves, according to the invention possible, an additional advantageous embodiment to get. is Using light guides or optical fibers the mentioned above its advantage of easy replacement of the lighting modules pronounced since the mutual alignment of the illumination modules only an additional uncritical assembling or disassembling the light emitting requires end of a light source. Consequently, no critical Calibration of the illumination system is necessary.

by by distribution of light a plurality of light guides, illuminating each of a number of light valves, it is also possible to have more to use light sources in a simple manner as each light source a specific light guide can be assigned, so that the effect is maximized.

Another advantage of distributing light by a light guide is that the light in optical couplers or similar suitable devices can be mixed to the individual light guide a greater total transmission effect gain.

Yet another advantage of the invention is that it gradually possible is increased power inputs to obtain, for example, lamps in the ultraviolet region, resulting in that the transmitted to the light valves Effect is so great, that the individual light guides can emit a light, having sufficient energy to simultaneously more light valves to illuminate.

In connection with the use of for example, W lamps have also found that the introduction of "macro illumination areas", i.e. areas, illuminated by a single optical fiber per area, No significant edge effects between each illumination area the consequence has, just as it was found that potential and significant Variations between the emitted effects of each light guide (resulting from a varying intensity profile a connected lamp Example&lt;?page 5?&gt;as a result of various Arrangements of the optical coupling of the individual instruments, and Fibers with respect to the lamp) by a suitable mixing the light guides can be compensated, whereby the result of lighting a visible homogeneous leaves an impression, without any significant differences in intensity in the edge regions available.

The aforesaid mixing can for example be executed in relation to the adjacent macro illumination areas, which can be equipped with an optical effect, does not vary significantly while relatively far apart to exploiting dividend macro illumination areas in intensity may vary without significant visible disruption to the illumination area to to have a result.

An additional advantage of the invention is that it is possible is emitted to or from the individual optical fibers light filtering, so that the illumination intensity for all or part of the optical fibers is homogeneous.

According to the invention such a device compared with the existing techniques, a relatively simple Technology is based, while also a high resolution, high lighting speed, good precision properties and uniform illumination intensity over a very big created lighting area.

The invention is particularly in With respect to light valves advantageous that with a relatively large loss being related. An example of such light valves can For example, spatial be such as LCD, PDLC, PLZT, FELCD light modulators and Kerr cells. Other types of light valves, for example, electromechanical reflection-based light valves of the DMD type be.

Consequently, it is according to the invention possible light in a simple manner via a big area with sum up the use of relatively few light guides, as well as possible is to orient the light emitters of the illumination system relatively freely, since the light emitting from the light guide ends and not from an optical system, drivers and cooling means consist.

A particularly advantageous embodiment, of the invention is obtained with transmissive light valves, because they produce little optical losses, which some of the functionality of Applications may be imperative.

As specified in claim 3, it by allowing the apparatus comprises a first lens arrangement , said first lens array, at least one respect on each light valve are arranged in such a manner microlens includes, that the emitted light by the (the) light guide (s) (8) on or near the optical axis of the individual light valves focused possible, a high Verwendungsmaß of Light effect and rapid generated by the light source overpace to get.

As specified in claim 4, there by allowing the rapid prototyping device between the light valves and the illumination area a second microlens array includes in such a manner that through the light channels of the individual Light valves through transmitted light is focused suitably on the illumination surface is possible, the light from each channel in smaller dots with high intensity on the illumination area pass therethrough.

The invention also provides a very advantageous option of preventing operation errors or improper operation available. consequently it becomes possible to the illumination area as far as possible to move from the light valve arrangement of time, thus reducing the risk, that the relevant media with the light valve array in contact come.

The lighting distance or Lighting distance can through the design and the design of the microlenses be determined.

This property is particularly advantageous because this technique - in Unlike other applications -for position inaccuracies in the z-surface is technically vulnerable.

As specified in claim 5, there by allowing the light guides preferably of multimode fibers made possible, a limited Illumination intensity loss and a large flexibility in the design of the large-scale assembly of each item to obtain.

is by using multimode fiber it also possible, the illumination area with to illuminate a broad spectrum of light.

As specified in claim 6, by allowing at least one of the light sources of a short arc gap lamp there is a high effect light emitted from a region of a limited physical scope attained (high radiation power).

As specified in claim 7, it by allowing the individual light valves in the rows in Cross direction of the surface are arranged at a given mutual distance, wherein the rows are mutually offset in the transverse direction, it is possible that Light Linear and wide divide.

As specified in claim 8, it by arranging the rows in such a manner that the Projection onto the transverse direction of the surface defined by the light valves to disposal is made, a number of illumination points at a given has mutual distance in the transverse direction to the result, it is possible light in points with a significantly improved resolution to emit, as it would have been the case if they by the physical determined extent of the valves laundri&lt;?page 6?&gt;reindeer, and when in a single row in the transverse direction would have been arranged.

As specified in claim 9, According to the invention by Allowing the (the) surface profile (s) the spatial Modulator arrangements are arranged at one or more exposure heads, wherein the exposure heads and the illumination area are designed to make a relative movement, wherein the Rapid prototyping apparatus comprising a control circuit for controlling the spatial Light modulator arrays dependent equipped by the movement between the exposure head and the illumination surface is an advantageous embodiment, obtained.

is as specified in claim 10, is it by allowing the exposure head (the exposure heads) a Beams comprise its movement over the illumination area from a single progressing movement in the transverse direction of the Beam is possible, to create illuminated points, due to the scanning motion all or cover a significant portion of the illumination area.

As specified in claim 11, it is by allowing the illumination device between the spatial Light modulator arrangement and the illumination face additional optical devices for the spreading comprises of light beams by a spatial light modulator arrangement over illumination area to disposal made possible, to expose an area which is physically larger than the area of ​​the of the light channels is covered, whereby non-active edge areas to a Light valve assembly around can be illuminated.

As specified in claim 12, is by allowing the spatial Light modulator arrangement of the illumination unit of spatial Light valves, such as LCD, PDLC, PLZT, FELCD or Kerr cells, is made, with respect to the light modulator principle of individual Applications a large design flexibility achieved what the production of standardized components cheaper designed.

As specified in claim 13, is it by allowing the spatial light modulator array the lighting apparatus of reflective electromechanical light valves, such as DMD, is, possible, a further advantageous embodiment, the invention to achieve that on commercially widespread technologies based.

Allow Through that the light valves the lighting unit from transmitting based electromechanical made light valves is through the modulator resolution with only a small light reduction obtained. This is in relation to even small improvements of the available radiation intensity in particular advantageously, which significantly reduced illumination time for Entails. This must be seen in the light of the fact that an RP prototype is built up by several layers of material, and to winning total time is therefore significant.

As specified in claim 14, is by allowing the light guides of the illumination unit with respect to the spatial Light modulator array are arranged in such a manner, that the delivered optical energy for each subgroup of light modulators does not vary significantly once the subsets of light modulators adjacent Subregions in large proximity on the illumination surface illuminate, the permissible Variation of light intensity obtained between all light sources, and they can no visible to be increased will.

The invention also relates to a method as specified in claim 15 for the preparation of three-dimensional objects by means of a rapid prototyping apparatus, wherein at least one light source having a plurality of light guides is optically coupled, which in relation to the spatial light modulator arrangement are arranged in such a manner that each light guide has a Subregion of the section illuminated.

Particular embodiments of the method according to the invention are the subject of the dependent claims . 16 and 17

In this way it is possible to to obtain illumination system that is capable of prototypes to produce at a rate, which is currently up faster times than the existing techniques and procedures is.

The larger the model, the greater the advantage according to the invention.

As specified in claim 16, is by allowing the completely or partially light-sensitive arranged material as a layer on a plate in a container is, and subsequently exposed by the RP device is before a new layer to the previous layer is arranged, a gradual Construction of the desired Prototype attained. According to the invention allows the Method, the construction of a layer and its connection with a preceding layer in a single working process.

As specified in claim 17, is it by allowing the RP machine a computer aided design program includes, which is capable of three-dimensional representations of the convert to be constructed in prototype files, the cross-section a containing the prototype, the contents of the files using find to control the controllable light modulators, it is possible, for example, graphical representations convert it to a given prototype. According to the invention finds this process takes a very slow conversion speed.

&lt;?page 7?&gt;

CHARACTERS

The invention will be under Referring to the figures in detail described. Show it:

<figref idrefs="S31">1</figref> on Example of an SLA application according to the invention and

<figref idrefs="S32">2</figref> on additional Example of the SLA application according to the invention.

DETAILED DESCRIPTION

<figref idrefs="S31">1</figref> shows a schematic diagram of an embodiment of the invention.

Micro contact or light valves are defined in the broadest sense as transmissive light diaphragms, which may be made for example of micromechanical closers. The individual members closer can for example, be of the type described in the French patent application number described 9412928, or be the guy in the corresponding EP-A 709 706 is described, as it for the preferred embodiment the invention of held crucial that the light to be modulated directly by the individual micro-closers is transmitted to provide a minimum transmission loss.

includes the rapid prototyping device shown (RP) device a steady Part whose most significant component of a container <figref>1</figref> consists, which is designed to provide a suitable amount of liquid RP material <figref>2</figref> to contain. An RP material is the material from which the RP prototype is made, such as epoxy, acrylic ester or other RP materials. additionally is the steady- Part with a guide <figref>4</figref> designed, the for various purposes between the stationary part and a movable lighting device <figref>3</figref> arranged can be. The illumination device can also be a (not shown) corresponding guide for example, vertical movement include. The RP apparatus also comprises other (non-shown) computer-controlled means, which are designed to provide a relative movement of the illuminator <figref>3</figref> according to a suitable computer-aided Design of the lighting system of the RP-device control.

The illumination device <figref>3</figref> is also equipped with an illumination system whose most important components are described below.

The illumination device <figref>3</figref> includes one on a frame <figref>5</figref> Inappropriate light source arrangement <figref>6</figref>, the together with a power supply device and a cooling device comprising known necessary means of illumination. In which example shown, the light source illustrated as a W-source. The light source with its aggregates and cooling devices may be stationary or movable be.

The light source arrangement <figref>6</figref> is optically with bundles <figref>7</figref> from multimode optical fibers connected. These bundles<figref>7</figref> splay in eight individual fibers <figref>8th</figref> on, in which each fiber has a Micro closer arrangement illuminated by, for example, 588 micro-mechanical light valves. Consequently, the eight individual fibers in unison illuminate a lighting device <figref>9</figref>. the eight micro closers arrangements which are respectively a single area of ​​the entire micro closer arrangement represent.

The construction itself and the orientation of these Light valves was by the inventor of this invention in the International Application Nos. PCT / DK98 / 00154 and no. PCT / DK98 / 00155 described.

Each area includes a Number of light valves which are connected by a (not shown) Control circuit can be individually controlled electrically. The Light valve arrangement, for example an LCD display with a given desired resolution be. However micromechanical closers are preferable.

The entire range of light valves is a single light guide <figref>8th</figref> illuminated, which is arranged in such a manner that one of the light guide <figref>8th</figref> emitted Beam all a personalized occupying light valves can deliver or dine with optical energy.

It should be noted that the Beam normally through the collimating optical instruments is fed to the sub-areas in such a manner that the light beam with which the spatial light modulator fed has been, over the Modulator region in terms of energy is uniform.

The micro closers in the lighting modules <figref>9</figref> were designed to be a scan over a Scanning line 25-30 cm in the lighting arrangement shown perform.

From the example it can be seen that the length of the scanning line to be used, that is, one of the maximum dimensions a manufactured RP prototype, in contrast to existing techniques as requested can be formed, since the "local or local "lighting individual lighting modules oriented in any direction on the illumination surface can be. Besides, it is also immediately apparent, that the illumination method by means of a central light source and the coupled optical guides a huge advantage in terms of the design provides, what is naturally financially and in the quality the finished design reflects. The design shown is therefore extremely robust, and any defects or damaged light modulators can be easily replaced.

Additionally, the apparatus is equipped with a (not shown) control circuit, which is designed to provide a relative Z positioning (Vertika&lt;?page 8?&gt;le movement) and orientation between the illumination system and a material <figref>2</figref> to disposal deliver. An example of such materials has been in the example one in <figref idrefs="S32">2</figref> the embodiment shown in detail described.

<figref idrefs="S32">2</figref> shows an RP device with a stationary part of a rigid attached bar is, the mobile with a on the x and Y plane carriage <figref>27</figref> is equipped. This carriage is with a holding device <figref>28</figref> equipped for fixing a lighting device, wherein the illumination device is horizontally movable or movable, while the device is vertically is fixed.

includes the lighting device also a light modulator <figref>21</figref>Consisting of a number of Light valves is. The supply of light from a light source to the valves is by mounting points for optical fibers <figref>22</figref> to disposal provided, wherein the light-emitting ends of the optical fibers having a Connectors are equipped, the design is simple and easy, a connection without an actual to provide calibration request.

The stationary part of the RP device also includes an elevator <figref>20</figref>, With which a carriage <figref>29</figref> vertical is moved. The carriage is mechanically connected to a plate<figref>24</figref> connected, thereby making it possible is, to move the plate vertically. Place the plate in a container<figref>23</figref> submerged which is designed to provide a suitable amount of liquid RP material to contain, and it can be kept below the surface.

The container <figref>23</figref> is under the lighting apparatus arranged that the carriage assembly <figref>26</figref> to <figref>28</figref> horizontally across the container can be moved while the RP-material to the appropriate manner by the light valves lighting device is illuminated. If it illuminates, the exposed amount of RP-material from the surface and down to harden there, where the plate is submerged. After curing, the plate is again in the liquid Material submerged, and because the plate having a number of perforations <figref>23</figref> equipped is the submersion occurs rapidly, while an unnecessary stirring or churning of the material is avoided.

Once the plate again vertically was positioned, it is submerged just enough to make it possible to make a new layer of liquid RP material on the previously cured to create layers. Then, an illumination of the new layer executed.

This technique is, for example, in <patcit><text>US 4,575,3.30</text></patcit> and <patcit><text>US 5,174,931</text></patcit> described.

Of course, it goes without saying that, in another embodiment, the container movable and the lighting modules can be stationary, or that both units may be movable, there take place a relative movement between the two units have to be. However, in the first embodiment, with the movable container the RP material most likely viscous or solid to a braking or damping and to avoid the formation of waves.

List of the drawings / Figures Reference numbers used:

<dl><dt>1.</dt><dd>container</dd><dt>. 2</dt><dd>Liquid RP material</dd><dt>. 3</dt><dd>lighting device</dd><dt>. 4</dt><dd>guide</dd><dt>. 5</dt><dd>frame</dd><dt>. 6</dt><dd>Light source assembly</dd><dt>. 7</dt><dd>bundle of optical fibers</dd><dt>8th.</dt><dd>light guides or light guide</dd><dt>. 9</dt><dd>lighting modules</dd><dt>20th</dt><dd>elevator</dd><dt>21st</dt><dd>lighting modules</dd><dt>22nd</dt><dd>attachment points for light End up</dd><dt>23rd</dt><dd>Container for RP material</dd><dt>24th</dt><dd>plate</dd><dt>25th</dt><dd>perforations in plate</dd><dt>26th</dt><dd>bar</dd><dt>27th</dt><dd>carriage lighting device</dd><dt>28th</dt><dd>holding device lighting device</dd><dt>29th</dt><dd>carriage board</dd></dl>