Construction platform for forming workpieces in layers or continuously

Abstract

To provide a modularly replaceable, autonomous building platform that operates independently of printer control and prevents inadvertent dissociation of a formed layer from the building platform.SOLUTION: There is provided a building platform (100) for forming a workpiece (200) in layers or continuously by stereolithography, comprising: a rear illumination device (101-1) for illuminating a layer (103-n) from a rear side; a photosensor (105) for detecting the light intensity of light from a front illumination device (101-2) through the layer (103-n) and / or a material and / or a deflecting mirror; and a control device (107) for activating the rear illumination device (101-1) when the detected light intensity of the front illumination device (101-2) is above a predetermined threshold.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a construction platform for forming a workpiece in layers or continuously in a stereolithography method, a stereolithography apparatus provided with the construction platform, and a method for forming a workpiece in layers or continuously by the construction platform.

Background Art

[0002] Due to the absorption characteristics of the photocurable material used in the stereolithography process, in order to generate sufficient adhesion of the workpiece on the construction platform that exceeds the separation stress at the bottom of the tank, the light output of the mask projection becomes partially insufficient, and therefore, when separation is performed, the constituent material may adhere to and remain on the bottom of the tank. This can be achieved by an active and temporary increase in the adhesion of the base layer of the construction platform by backside irradiation of the construction platform.

[0003] According to Patent Document 1, an apparatus for processing a photocurable material is disclosed. A rear-side illumination device built into the construction platform is connected to the control device of the printer and is operated by the printer control device for the first layer of the construction process.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] The technical problem of the present invention is to provide a modular, replaceable, and autonomous construction platform that operates independently of printer control and prevents accidental dissociation of the formed layer from the construction platform in a simple manner.

Means for Solving the Problems

[0006] The above problem is solved by the subject matter of the independent claims. Suitable additional configurations are defined by the subject matter of the dependent claims and the detailed description of the invention and the accompanying drawings.

[0007] In a first aspect, the above technical problem is solved by a construction platform for forming a workpiece in layers or continuously in a stereolithography method, the construction platform comprising a rear-side illumination device for irradiating a layer from behind, a light sensor for detecting the light intensity of light from a front-side illumination device through and / or via a deflector mirror through a layer and / or material, and a control device independent of a printer for activating the rear-side illumination device when the detected light intensity of the front-side illumination device exceeds a given threshold value. Thereby, for example, a technical advantage is achieved in that the first layer formed is irradiated from two opposite directions and cured, improving the adhesion to the construction platform.

[0008] According to a second aspect, the above technical problem is solved by a construction platform for forming a workpiece in layers or continuously in a stereolithography method, the construction platform comprising a rear-side illumination device for irradiating a layer from behind, a detection device 106 for detecting the creation of a first layer, and a control device independent of a printer for activating the rear-side illumination device when the creation of the first layer is detected. Thereby, a technical advantage similar to that of the construction platform according to the first aspect is achieved.

[0009] The detection device 106 can include, for example, a mechanical scanner or a distance measuring device, which is built into the construction platform and triggered for the first layer. The detection device 106 can be configured to activate a counter, thereby counting the number of layers formed and activating the rear-side illumination device for, for example, the first five layers when the number is less than a given threshold value. At the start of the manufacturing process, the construction platform can move backward towards the scanner. The activation can be performed up to a predetermined height using near field communication (NFC).

[0010] According to an embodiment of a technically suitable construction platform, the rear-side lighting device is formed from a light-emitting diode matrix. Thereby, for example, technical advantages such as large-area irradiation and curing being carried out with low energy consumption are achieved.

[0011] According to another embodiment of a technically suitable construction platform, the light intensity or irradiation time of the rear-side lighting device can be set using a potentiometer or can be controlled by an internal control device. Thereby, for example, technical advantages such as the light intensity being controllable manually or automatically and adaptable to the materials used are achieved.

[0012] According to another embodiment of a technically suitable construction platform, a counter can be used to control the number of layers irradiated from the rear. Thereby, for example, technical advantages such as the rear lighting device being triggered only for the first layer when other layers absorb too much light and the light sensor is no longer operating are achieved. Even when there is insufficient light, the counter can perform additional rear lighting until a given number of layers is reached.

[0013] According to another embodiment of a technically suitable construction platform, the construction platform comprises an electrical energy storage device for storing energy for the rear-side lighting device. Thereby, for example, technical advantages such as the construction platform being able to supply the required energy autonomously and without an external connection cable are achieved.

[0014] According to another embodiment of a technically suitable construction platform, the energy storage device consists of a rechargeable and / or replaceable battery. Thereby, for example, technical advantages such as the energy storage device being recyclable are achieved.

[0015] According to another embodiment of a technically suitable construction platform, the optical sensor is a photodiode adapted to the wavelength range of the front-side illumination. The photodiode is, for example, a silicon carbide photodiode or a silicon photodiode. Thereby, for example, a technical advantage is achieved that the light intensity can be measured with high accuracy.

[0016] According to another embodiment of a technically suitable construction platform, the photodiode is sensitive in the wavelength range of ultraviolet A waves or blue light regions of the front-side illumination device. Thereby, for example, a technical advantage is achieved that a wavelength range suitable for curing of materials can be captured.

[0017] According to another embodiment of a technically suitable construction platform, a given threshold for activating the rear-side illumination device can be set by the user. Thereby, for example, a technical advantage is achieved that the threshold can be adapted to the material used.

[0018] According to another embodiment of a technically suitable construction platform, the construction platform can be modularly installed in the stereolithography apparatus together with the rear-side illumination device. Thereby, for example, a technical advantage is achieved that the construction platform can be replaced.

[0019] According to another embodiment of a technically suitable construction platform, the rear-side illumination device can be detachably or pushably mounted on the construction platform in a modular manner. Thereby, for example, a technical advantage is achieved that the illumination device can be selectively used or replaced, and an illumination device extremely suitable for the material can be used.

[0020] According to another embodiment of a technically suitable construction platform, the construction platform can operate wirelessly. Thereby, for example, a technical advantage is achieved that the structure and handling of the construction platform are simplified.

[0021] According to a third aspect, a technical problem is solved by a stereolithography apparatus including the construction platforms according to the first and second aspects. By this stereolithography apparatus, technical advantages similar to those of the construction platforms according to the first and second aspects are achieved.

[0022] According to a technically preferred embodiment of the stereolithography apparatus, the stereolithography apparatus is configured in such a manner that part of the light of the front-side illumination device used for irradiating the first layer is deflected toward a photosensor, thereby activating the back-side illumination device. Thereby, for example, technical advantages such as the back-side illumination being autonomously and indirectly activated by the manufacturing process / illumination process and the need for direct control by a printer being eliminated are achieved.

[0023] According to a fourth aspect, a technical problem is solved by a stereolithography method of forming a workpiece in layers or continuously by a construction platform including steps of irradiating a layer from the front by a front-side illumination device; detecting, by a photosensor, the light intensity of light from the front-side illumination device that has passed through the layer and / or material and / or via a deflection mirror; and activating the back-side illumination device by a control device independent of the printer when the detected light intensity of the front-side illumination device exceeds a given threshold. By this method, technical advantages similar to those of the construction platform according to the first aspect described above are achieved.

[0024] According to a fifth aspect, a technical problem is solved by a stereolithography method of forming a workpiece in layers or continuously by a construction platform including steps of detecting, by a detection device 106, the creation of a first layer; and activating the back-side illumination device by a control device independent of the printer when the creation of the first layer is detected.

[0025] According to a technically preferred embodiment of the above method, the activation of the back-side illumination device is performed according to an irradiation time adjusted for a given number of layers and / or for each layer. Thereby, for example, technical advantages such as the degree of polymerization of the material cured at the back side being controllable with high precision are achieved.

[0026] According to another technically preferred embodiment of the method described above, the height of the construction platform in the construction process is incorporated into the calculation to determine the initial position of the construction platform and to set a given layer thickness of the layer. Thereby, for example, a technical advantage is achieved that the target layer thickness can be maintained even when the construction platform is replaced.

[0027] Next, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0029] FIG. 1 is a cross-sectional view schematically showing the state of the construction platform 100 in the stereolithography method. The construction platform 100 acts to form the workpiece 200 in layers or continuously in the stereolithography apparatus. Therefore, the lower surface of the construction platform 100 is present in the viscous material 109 that can be cured by light. When one layer is cured, the construction platform moves from the irradiation level and is set again to the subsequent layer thickness, so that the viscous material can flow in again and then cures. The material 109 is, for example, a ceramic slurry for manufacturing dental prostheses. However, generally other materials can also be processed.

[0030] The construction platform 100 includes a rear-side lighting device 101-1 that irradiates the layer 103-n of the material 109 from the rear. The lighting device 101-1 includes a plurality of light-emitting diodes 113 disposed on the rear side of the transparent surface 117. The light-emitting diodes 113 can emit light in a wavelength range of, for example, 220 to 500 nm. The maximum of the spectrum can be, for example, 365 nm, 385 nm, 405 nm, or 460 nm. However, generally other wavelengths can also be used.

[0031] By the rear-side illumination, the material 109 cures directly on the transparent surface 117 of the construction platform 100, forming a layer (burn-in layer) that adheres firmly to the construction platform. In this way, accidental detachment of the workpiece from the construction platform 100 can be prevented. The light intensity and / or irradiation time of the rear-side lighting device 101-1 can be set for each layer by a potentiometer or automatically adjusted for each layer by an internal control device.

[0032] The construction platform 100 includes an electrical energy storage device 115 for storing the energy of the rear-side lighting device 101-1. With this energy storage device 115, electrical energy can be autonomously supplied to the rear-side lighting device 101-1 without the need to connect a cable to the construction platform 100 for that purpose. The electrical energy storage device 115 can be, for example, a battery pack or a rechargeable battery pack.

[0033] The stereolithography apparatus 300 includes a front-side lighting device 101-2 on the side opposite to the construction platform 100. The front-side lighting device 101-2 includes a digital projection unit 113 disposed below the transparent bottom floor 111. The front-side lighting device 101-2 acts to cure the material layer by layer from the opposite side of the construction platform through the transparent tank bottom surface. An arbitrary pattern can be projected onto the material by the projection unit 113. Therefore, the projection unit 113 can include a digital micromirror device (DMD) or a liquid crystal display (LCD).

[0034] The construction platform 100 includes a light sensor 105 suitable for detecting the light intensity of the light from the front-side lighting device 101-2 via the material 109. The light sensor 105 can be formed, for example, by a photodiode. The more layers the formed workpiece has, the lower the light intensity detected by the light sensor 105. The light sensor 105 is arranged at the corner of the construction field (= irradiation field) and can respond to the illumination of the layer 103.

[0035] The effect can be utilized to activate the back-side lighting device 101-1 exclusively for the first layer 103-n only, thereby preventing unnecessary irradiation of the already cured layers on the transparent surface 117 on the one hand, and eliminating the wasteful consumption of materials by curing an unnecessarily large number of layers over a large area on the other hand. In addition, power is saved. Therefore, the construction platform 100 includes an electronic control device 107 that activates the back-side lighting device 101-1 only when the detected light intensity of the front-side lighting device 101-2 exceeds a given threshold value. The above-mentioned threshold value can be set to any numerical value. As a result, the energy storage device 115 of the construction platform 100 can be used longer. When the detected light intensity is below a given threshold value, that is, when a specific number of layers already exist, the back-side lighting device 101-1 is not activated. In addition, the number of layers irradiated from the back can be controlled by an adjustable counter. The counter counts the number of layers formed from the beginning. The back-side lighting device 101-1 is activated until the number of formed layers reaches a given number.

[0036] Figure 2 shows another state of the construction platform 100 in the stereolithography method. In this case, the first layer of the workpiece is formed. A part of the light from the front-side lighting device 101-2 penetrates the material and irradiates the light sensor 105.

[0037] If only a single-layer material layer exists, the photosensor 105 detects the high light intensity of the front-side illumination device 101-2. The light traveling through the material layer is absorbed by the material layer in a very small proportion. The light intensity decreases significantly as the number of layers increases. When the light intensity exceeds a given threshold due to a small number of layers, the back-side illumination device 101-1 is activated accordingly. As a result, the layer is irradiated entirely from both the front-side illumination device 101-2 and the back-side illumination device 101-1. Thereby, a layer (burn-in layer) that adheres firmly to the construction platform 100 is formed.

[0038] Figure 3 shows another state of the construction platform 100 in the stereolithography method. The layer 103-n hardens and adheres onto the transparent surface 117 of the construction platform 100. Subsequently, the construction platform 100 is lifted, and subsequent layers 103-n are formed. The detected light intensity decreases as the number of layers 103-n increases. When the detected light intensity drops below a given threshold or the counter reaches its limit, the back-side illumination device 101-1 is stopped simultaneously. Thereby, the required number of burn-in layers and the degree of polymerization can be accurately controlled without unnecessarily shortening the lifespan of the energy storage device 115 and without eliminating the control by the printer.

[0039] The construction platform 100 can be equipped with a counter that determines how many layers should be irradiated from the back side. Additionally, a deflection mirror can be provided that deflects the light from the front-side illumination device 101-2 directly towards the photosensor 105. The construction platform 100 can also be equipped with a digital memory, in which dimensional values such as height can be recorded as digital numerical values, for example. These digital numerical values can be read by the stereolithography apparatus 300, thereby calculating the initial position (0 position) of the construction platform with the back-side illumination unit relative to the transparent bottom floor 111 and setting it to the required Z value.

[0040] FIG. 4 shows a block diagram of a method of forming a workpiece 200 in layers or continuously by a construction platform 100. In a first step S101, layer 103-n is irradiated from the front by a front-side illumination device 101-2. Thereafter, in a second step S102, the light intensity of light passing through layer 103-n and / or material 109 and / or via a deflection mirror from the front-side illumination device 101-2 is detected by a light sensor 105. In step S103, when the detected light intensity of the front-side illumination device 101-2 exceeds a given threshold, a rear-side illumination device 101-1 is activated by a control device 107. When the detected light intensity is less than the given threshold, the rear-side illumination device 101-1 is stopped.

[0041] Activation of the rear-side illumination device 101-1 can be performed for a given number of layers 103-n. Therefore, a counter can be provided to count the number of formed layers. The height of the construction platform 100 for the construction process can be calculated to perform the construction process, thereby determining the initial position of the construction platform 100 and setting a given layer thickness of layer 103-n.

[0042] The construction platform 100 with the built-in rear-side illumination device 101-1 can be retrofitted and operated without being electrically connected to a stereolithography apparatus 300. The rear-side illumination device 101-1 can be controlled or triggered by mask projection of a general burn-in layer via a built-in light sensor.

[0043] That is, control of the rear-side illumination device 101-1 is performed using a light sensor 105 triggered by irradiation of a base layer by the front-side illumination device 101-2. Therefore, the rear-side illumination device 101-1 can be controlled or activated in synchronization with mask projection.

[0044] The rear - side irradiation is temporarily executed on the first to fifth layers 103 in synchronization with the substantial irradiation of the burn - in layer. The power supply is executed independently of the other parts of the stereolithography apparatus 300 by the energy storage device 115 built into the construction platform 100.

[0045] By indirect control via the optical sensor 105, the rear - side lighting device 101 - 1 can be activated without mechanical contact and electrical connection with the other parts of the stereolithography apparatus 300. The energy storage device 115 enables an independent energy supply, thus eliminating the need for external cables.

[0046] Generally, a stereolithography apparatus 300 such as a stereolithography printer often does not include a construction platform 100 having a rear - side lighting device 101 - 1 connected to a control device. The autonomous construction platform 100 can be retrofitted to the stereolithography apparatus 300 without the need for hardware and / or software modifications. The retrofitted construction platform 100 operates independently of the printer control device and is controlled / triggered only via the irradiation of the front - side lighting device 101 - 2 during construction.

[0047] All the features described in connection with the individual embodiments of the present invention can be applied to the subject matter of the present invention in various combinations, thereby simultaneously realizing their advantageous effects.

[0048] All method steps can be implemented by an apparatus suitable for performing each method step. All functions that can be performed by the target features can be made method steps of the method of the present invention.

[0049] The protection scope of the present invention is defined by the appended claims and is not limited by the features shown in the detailed description of the invention and the appended drawings.

Explanation of Reference Numerals

[0050] 100 Construction platform 101-1 Rear-side lighting device 101-2 Front-side lighting device 103 Layer 105 Optical sensor 107 Electronic control device 109 Material 111 Bottom bed 113 Light-emitting diode 115 Energy storage device 117 Transparent surface 200 Workpiece 300 Stereolithography apparatus

Claims

1. A construction platform (100) for forming a workpiece (200) in a layered or continuous manner in a stereolithography method, comprising: a rear-side illumination device (101-1) for irradiating a layer (103-n) from the rear; a light sensor (105) for detecting the light intensity of light from a front-side illumination device (101-2) through the layer (103-n) and / or material and / or via a deflection mirror; a control device (107) independent of a printer for activating the rear-side illumination device (101-1) when the detected light intensity of the front-side illumination device (101-2) exceeds a given threshold.

2. A construction platform (100) for forming a workpiece (200) in a layered or continuous manner in a stereolithography method, comprising: a rear-side illumination device (101-1) for irradiating a layer (103-n) from the rear, a detection device (106) for detecting the creation of a first layer (103-1), a control device (107) independent of a printer for activating the rear-side illumination device (101-1) when the creation of the first layer (103-1) is detected.

3. The construction platform (100) according to claim 1 or 2, wherein the rear-side illumination device (101-1) is formed from a light-emitting diode matrix.

4. The construction platform (100) according to any one of claims 1 to 3, wherein the light intensity or irradiation time of the rear-side illumination device (101-1) is settable using a potentiometer or controllable by an internal control device and / or the number of layers (103-n) irradiated from the rear is controllable using a counter.

5. The construction platform (100) according to any one of claims 1 to 4, wherein the construction platform (100) comprises an electrical energy storage device (115) for storing energy for the rear-side illumination device (101-1) and / or the energy storage device consists of a rechargeable and / or replaceable battery.

6. The construction platform according to any one of claims 1 to 5, wherein the light sensor (105) is a photodiode tuned to the wavelength range of the front-side illumination.

7. The construction platform (100) according to claim 6, wherein the photodiode is sensitive in the wavelength range of ultraviolet A wave or blue light region of the front-side illumination device.

8. The construction platform (100) according to any one of claims 1 to 7, wherein a given threshold value for activating the rear-side lighting device is settable by a user.

9. The construction platform (100) according to any one of claims 1 to 8, wherein the construction platform (100) can be modularly installed in the stereolithography apparatus (300) together with the rear-side lighting device (101-1), or the rear-side lighting device (101-1) can be modularly attached or pushed onto the construction platform (100).

10. A stereolithography apparatus (300) comprising the construction platform according to claims 1 to 9.

11. The stereolithography apparatus (300) according to claim 10, characterized in that the stereolithography apparatus (300) is configured in such a way that part of the light of the front-side lighting device used for irradiating the first layer is deflected towards a light sensor, thereby activating the rear-side lighting device.

12. A stereolithography method of forming a workpiece (200) layer by layer or continuously by means of a construction platform (100): Irradiating a layer (103-n) from the front by means of a front-side lighting device (101-2) (S101); Detecting the light intensity of the light from the front-side lighting device (101-2) through the layer (103-n) and / or the material and / or via a deflection mirror by means of a light sensor (105) (S102); Activating the rear-side lighting device (101-1) by means of a control device (107) independent of the printer when the detected light intensity of the front-side lighting device (101-2) exceeds a given threshold value (S103), the method consisting of each step.

13. A stereolithography method of forming a workpiece (200) layer by layer or continuously by means of a construction platform (100): Detecting the creation of the first layer by means of a detection device (106); Activating the rear-side lighting device (101-1) by means of a control device (107) independent of the printer when the creation of the first layer is detected, the method consisting of each step.

14. The method according to claim 12 or 13, wherein the activation of the rear-side lighting device (101-1) is carried out according to an irradiation time adjusted for a given number of layers and / or for each layer.

15. The method according to any one of claims 12 to 14, which incorporates the height of the construction platform (100) in the construction process to determine the initial position of the construction platform (100) and to set a given layer thickness of the layer (103-n).

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