EP0361847A2
Expired / Lapsed
EP
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Recoating of stereolithographic layers
Assignee: 3D Systems Inc
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Filing: 1989-09-26
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Granted: —
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Expires: 2009-09-26
Abstract
Abstract A stereolithography method and system for producing three-dimensional plastic objects by forming a plurality of thin layers of partially cured plastic material which are thin cross sections of the desired object. A layer of polymerizable resin is applied to a support surface and the excess is struck off, such as with a doctor blade, to form a smoothed layer. The smoothed layer is subjected to radiation in a predetermined pattern to form the cross-sectional layer into the desired shape. A plurality of layers are subsequently applied, leveled, then cured in the same manner to produce the desired three-dimensional object. Apparatus for measuring the level of the surface of a fluid is also provided. Variations in the level of fluid will be detected and may be used to drive a pump, diaphragm, or plunger in order to maintain the level of the fluid.
Inventors
- 👤 Thomas A. Almquist
- 👤 Charles W. Hull
- 👤 Borzo Modrek
- 👤 Andrzej R. Serkuczewski
- 👤 Paul F. Jacobs
- 👤 Charles W. Lewis
- 👤 Mark A. Lewis
- 👤 Abraham Liran
- 👤 Dennis R. Smalley
- 👤 Adam L. Cohen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 23:37
CPC Classifications
B; B29; B29C; B29C35/00; B29C35/02; B29C35/08; G; G05; G05D; G05D9/00; G05D9/12; B29C41/00; B29C41/02; B29C41/12; B29C64/00; B29C64/10; B29C64/106; B29C64/124; B29C64/129; B29C64/135; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; G01F23/2921; G01F23/30; G01F23/32; G01F23/36; G01F23/366; B29K; B29K2995/00; B29K2995/0037; B29K2995/0072; B29K2995/0073
Claims Analysis
Total Claims: 58
Claim 1
Independent Claim
75 words
A stereolithography system for forming three-dimensional objects, comprising: (a) an object support means; (b) a means to apply a thin layer of polymerizable liquid to a surface on the object support means; (c) means to strike off excess polymerizable liquid from the applied layer thereof to provide a smoothed layer of polymerizable liquid of desired thickness; and (d) means to apply a curing media in a predetermined pattern to the smoothed layer of polymerizable liquid.
Claim 2
Dependent Claim
75 words
A stereolithography system for forming three-dimensional objects, comprising: (a) an object support means; (b) a means to apply a thin layer of polymerizable liquid to a surface on the object support means; (c) means to strike off excess polymerizable liquid from the applied layer thereof to provide a smoothed layer of polymerizable liquid of desired thickness; and (d) means to apply a curing media in a predetermined pattern to the smoothed layer of polymerizable liquid.
Claim 3
Dependent Claim
18 words
The stereolithography system of claim 1 including a tank adapted to contain a bath of polymerizable liquid therein.
Claim 4
Dependent Claim
19 words
The stereolithography system of claim 2 including means to raise and lower the object support means within the tank.
Claim 5
Dependent Claim
14 words
The stereolithography system of claim 1 wherein the strike-off means is a doctor blade.
Claim 6
Dependent Claim
19 words
The stereolithography system of claim 1 wherein means are provided to move the doctor blade in a horizontal plane.
Claim 7
Dependent Claim
49 words
The stereolithography system of claim 3 wherein the means to raise and lower the object support means includes means to lower the object support means within a bath of polymerizable liquid to form a thin layer of said polymerizable liquid on a surface provided on the object support means.
Claim 8
Dependent Claim
41 words
The stereolithography system of claim 6 wherein the means to raise and lower the object support means includes means to raise the layer of polymerizable liquid on the surface of the object support means above the upper surface of the bath.
Claim 9
Dependent Claim
14 words
The stereolithography system of claim 7 wherein the strike-off means is a doctor blade.
Claim 10
Dependent Claim
57 words
The stereolithography system of claim 7 wherein the means to raise and lower the object support means includes means to lower the smoothed layer of polymerizable liquid on the surface of the object support means into the bath with the upper surface of said layer being level with the upper surface of the bath within the tank.
Claim 11
Dependent Claim
18 words
The stereolithography system of claim 2 including means to control the level of the bath in the tank.
Claim 12
Dependent Claim
32 words
The stereolithography system of claim 10 wherein the means to control the level of bath in the tank includes a piston disposed within the bath which can be raised or lowered therein.
Claim 13
Dependent Claim
37 words
The stereolithography system of claim 11 including means to sense the level of polymerizable liquid in the tank and means to adjust the vertical position of the piston within the bath in response to the level sensed.
Claim 14
Dependent Claim
57 words
The stereolithography system of claim 12 including means to generate a signal representing the bath level sensed and means to compare said level signal with a reference signal representing the desired bath level and further means to adjust the vertical position of the piston in response to the difference between the sensed signal and the reference signal.
Claim 15
Dependent Claim
18 words
The stereolithography system of claim 1 including a laser to generate ultraviolet light to cure the polymerizable liquid.
Claim 16
Dependent Claim
13 words
The stereolithographic system of claim 14 wherein the laser is a HeCd laser.
Claim 17
Dependent Claim
20 words
The stereolithography system of claim 14 including a computer control system to control the movement and output of the laser.
Claim 18
Dependent Claim
20 words
The stereolithography system of claim 16 including a computer control system to control the movement of the object support means.
Claim 19
Independent Claim
84 words
A method of forming three-dimensional objects by stereolithography comprising: (a) applying a layer of polymerizable liquid onto a surface provided on an object support means; (b) leveling the layer of polymerizable liquid on said surface to a desired thickness by striking off any excess polymerizable liquid from the applied layer; and (c) applying a curing media in a preselected pattern onto the leveled layer of polymerizable liquid to sufficiently cure the layer so that it supports one or more subsequent layers of polymerizable liquid.
Claim 20
Independent Claim
84 words
A method of forming three-dimensional objects by stereolithography comprising: (a) applying a layer of polymerizable liquid onto a surface provided on an object support means; (b) leveling the layer of polymerizable liquid on said surface to a desired thickness by striking off any excess polymerizable liquid from the applied layer; and (c) applying a curing media in a preselected pattern onto the leveled layer of polymerizable liquid to sufficiently cure the layer so that it supports one or more subsequent layers of polymerizable liquid.
Claim 21
Dependent Claim
29 words
The method of claim 18 wherein the curing media is radiation selected from the group consisting of ultraviolet radiation, infrared radiation, visible light, electron beams, x-rays, and gamma rays.
Claim 22
Dependent Claim
21 words
The method of claim 19 wherein the polymerizable liquid is curable with ultraviolet radiation and the curing media is ultraviolet radiation.
Claim 23
Dependent Claim
31 words
The method of claim 18 wherein the layer of polymerizable liquid is applied to a surface on the object support means by submerging the surface into a bath of polymerizable liquid.
Claim 24
Dependent Claim
49 words
The method of claim 18 wherein the applied layer of polymerizable liquid is raised out of the bath and excess polymerizable liquid is struck off therefrom by means of a horizontally moving doctor blade to form a smoothed layer of polymerizable liquid of the desired thickness on said surface.
Claim 25
Dependent Claim
44 words
The method of claim 18 wherein the object support means is lowered into the bath after the layer of polymerizable liquid is smoothed so that the upper surface of the smoothed layer of polymerizable liquid is level with the upper surface of the bath.
Claim 26
Dependent Claim
33 words
The method of claim 23 wherein after the upper surface of the smoothed layer of polymerizable liquid is disposed at the same level of the bath, the layer is subjected to curing media.
Claim 27
Dependent Claim
43 words
The method of claim 24 wherein after the smoothed layer is subjected to curing media, the object support means is further lowered into the bath of polymerizable liquid so that a subsequent layer of polymerizable liquid can flow onto the previously cured layer.
Claim 28
Dependent Claim
24 words
The method of claim 18 wherein a plurality of thin layers of polymerizable liquid are applied, leveled, and cured to form a three-dimensional object.
Claim 29
Dependent Claim
35 words
The method of claim 18 wherein the curing media is ultraviolet radiation emitted from an HeCd laser at a wavelength approximately 300 to 350 nanometers and from about 10 to about 30 milliwatts of power.
Claim 30
Dependent Claim
23 words
The method of claim 19 wherein the horizontal speed of the doctor blade ranges from about 0.25 to about 10 inches per second.
Claim 31
Dependent Claim
32 words
The method of claim 18 wherein the thickness of the layer of polymerizable liquid which is polymerized by the application thereto of curing media ranges from about 0.005 to about 0.04 inch.
Claim 32
Dependent Claim
108 words
Apparatus for measuring the level of a surface of a fluid, comprising: (a) means for generating and directing a beam of electromagnetic radiation along a first optical path to impinge upon the surface of the fluid so that a detectable portion of the beam is reflected off the surface of the fluid along a second optical path; (b) a sensor that varies an electrical signal in response to movement of an impinging electromagnetic beam across the sensor; and (c) means for mounting the sensor at a distance perpendicular to the level of the fluid and along the second optical path so that the reflected beam intersects the sensor.
Claim 33
Dependent Claim
108 words
Apparatus for measuring the level of a surface of a fluid, comprising: (a) means for generating and directing a beam of electromagnetic radiation along a first optical path to impinge upon the surface of the fluid so that a detectable portion of the beam is reflected off the surface of the fluid along a second optical path; (b) a sensor that varies an electrical signal in response to movement of an impinging electromagnetic beam across the sensor; and (c) means for mounting the sensor at a distance perpendicular to the level of the fluid and along the second optical path so that the reflected beam intersects the sensor.
Claim 34
Dependent Claim
24 words
The apparatus according to claim 30 further comprising means for altering the level of the fluid responsive to the electrical signal from the sensor.
Claim 35
Dependent Claim
24 words
The apparatus according to claim 30 further comprising means for displaying the level of the fluid responsive to the electrical signal from the sensor.
Claim 36
Dependent Claim
145 words
Apparatus for measuring the level of a surface of a fluid, comprising: (a) a laser, the output from the laser being directed from above the surface of the fluid along a first optical path to the surface of the fluid so that the output of the laser reflects from the surface of the fluid along a second optical path; (b) a plurality of linked photocells, each photocell having an output and producing an electrical signal on the output which varies with the intensity of light impinging on the photocell; and (c) means for mounting the plurality of linked photocells above the surface of the fluid along the second optical path, the linked photocells being aligned one above each other in a direction perpendicular to the level of the surface of the fluid wherein the laser output impinges upon one or more of the linked photocells.
Claim 37
Dependent Claim
145 words
Apparatus for measuring the level of a surface of a fluid, comprising: (a) a laser, the output from the laser being directed from above the surface of the fluid along a first optical path to the surface of the fluid so that the output of the laser reflects from the surface of the fluid along a second optical path; (b) a plurality of linked photocells, each photocell having an output and producing an electrical signal on the output which varies with the intensity of light impinging on the photocell; and (c) means for mounting the plurality of linked photocells above the surface of the fluid along the second optical path, the linked photocells being aligned one above each other in a direction perpendicular to the level of the surface of the fluid wherein the laser output impinges upon one or more of the linked photocells.
Claim 38
Dependent Claim
64 words
The apparatus according to claim 33 further comprising a comparison circuit having a plurality of inputs and an output, wherein each input is coupled to a different output of one of the plurality of linked photocells, to compare the relative amplitudes of the electrical signals produced by each of the linked photocells and generate a signal responsive to the output of said comparison circuit.
Claim 39
Dependent Claim
29 words
The apparatus according to claim 34 further comprising means coupled to the comparison circuit for making the level of the fluid responsive to the output of the comparison circuit.
Claim 40
Dependent Claim
33 words
The apparatus according to claim 35 in which the level varying means responds to changes in the signal from the comparison circuit to return the level of the fluid to a predetermined level.
Claim 41
Dependent Claim
135 words
A stereolithographic apparatus, comprising: (a) a body of fluid medium capable of transforming its physical state in response to synergistic stimulation; (b) means for generating a beam of electromagnetic radiation; (c) means for directing the beam of electromagnetic radiation from the generating means along a first optical path to impinge upon the surface of the fluid medium so that a detectible portion of the beam is reflected off the surface of the fluid medium along a second optical path; (d) a sensor that varies an electrical signal in response to changes in the position at which an electromagnetic beam impinges upon the sensor; and (e) means for mounting the sensor at a distance perpendicular to the surface of the fluid medium and along the second optical path so that the reflected beam intersects the sensor.
Claim 42
Dependent Claim
135 words
A stereolithographic apparatus, comprising: (a) a body of fluid medium capable of transforming its physical state in response to synergistic stimulation; (b) means for generating a beam of electromagnetic radiation; (c) means for directing the beam of electromagnetic radiation from the generating means along a first optical path to impinge upon the surface of the fluid medium so that a detectible portion of the beam is reflected off the surface of the fluid medium along a second optical path; (d) a sensor that varies an electrical signal in response to changes in the position at which an electromagnetic beam impinges upon the sensor; and (e) means for mounting the sensor at a distance perpendicular to the surface of the fluid medium and along the second optical path so that the reflected beam intersects the sensor.
Claim 43
Independent Claim
87 words
A method for measuring the level of a surface of a fluid, comprising the following steps: (a) generating a beam of electromagnetic radiation; (b) directing the beam of electromagnetic radiation along a first optical path to the surface of the fluid so that a detectible portion of the beam is reflected from the surface along a second optical path; and (c) sensing displacement of the second optical path at a distance perpendicular to the level of the fluid due to changes in the level of the fluid.
Claim 44
Independent Claim
87 words
A method for measuring the level of a surface of a fluid, comprising the following steps: (a) generating a beam of electromagnetic radiation; (b) directing the beam of electromagnetic radiation along a first optical path to the surface of the fluid so that a detectible portion of the beam is reflected from the surface along a second optical path; and (c) sensing displacement of the second optical path at a distance perpendicular to the level of the fluid due to changes in the level of the fluid.
Claim 45
Independent Claim
117 words
A method for applying a substantially smooth layer of polymerizable liquid of a predetermined thickness over a part layer in a stereolithography system, comprising the steps of: dipping said part layer into a body of said liquid by more than said predetermined thickness, and then raising said part layer thereby applying a layer of said liquid over said part layer; and sweeping a doctor blade one or more times over said liquid layer, with a clearance between the blade and part layer, striking off excess liquid at each sweep, such that on the last sweep, the clearance between the blade and the part layer is substantially equal to the predetermined thickness, thereby forming said substantially smooth layer.
Claim 46
Independent Claim
117 words
A method for applying a substantially smooth layer of polymerizable liquid of a predetermined thickness over a part layer in a stereolithography system, comprising the steps of: dipping said part layer into a body of said liquid by more than said predetermined thickness, and then raising said part layer thereby applying a layer of said liquid over said part layer; and sweeping a doctor blade one or more times over said liquid layer, with a clearance between the blade and part layer, striking off excess liquid at each sweep, such that on the last sweep, the clearance between the blade and the part layer is substantially equal to the predetermined thickness, thereby forming said substantially smooth layer.
Claim 47
Dependent Claim
21 words
The method of claim 39 wherein the clearance between the blade and the part layer gets progressively smaller at each sweep.
Claim 48
Dependent Claim
16 words
The method of claim 40 wherein the velocity of the blade can vary at each sweep.
Claim 49
Dependent Claim
97 words
A stereolithography apparatus for forming a second part layer having a predetermined thickness on top of a first part layer comprising: means for dipping the first layer into a substantially constant volume of polymerizable liquid by more than the predetermined thickness; means for raising said first layer so that a layer of polymerized liquid is on the first layer; a doctor blade for smoothing the liquid layer by sweeping off excess liquid until the liquid layer is at said predetermined thickness; and means for forming the second layer by subjecting the smoothed liquid layer to synergistic stimulation.
Claim 50
Dependent Claim
97 words
A stereolithography apparatus for forming a second part layer having a predetermined thickness on top of a first part layer comprising: means for dipping the first layer into a substantially constant volume of polymerizable liquid by more than the predetermined thickness; means for raising said first layer so that a layer of polymerized liquid is on the first layer; a doctor blade for smoothing the liquid layer by sweeping off excess liquid until the liquid layer is at said predetermined thickness; and means for forming the second layer by subjecting the smoothed liquid layer to synergistic stimulation.
Claim 51
Dependent Claim
72 words
The apparatus of claim 42 further comprising: a vat for containing the substantially constant volume of polymerizable liquid, said volume having a level; means for detecting the level of the polymerizable liquid in the vat and comparing said detected level to a predetermined level; and a plunger responsive to said detecting means for raising or lowering into said liquid in said vat until the liquid level is substantially at said predetermined level.
Claim 52
Dependent Claim
63 words
The apparatus of claim 43 further comprising a side tank coupled to the vat, such that liquid can flow between the vat and side tank, ensuring that the liquid level in the side tank is respresentative of the liquid level in the vat, wherein the level detecting means is a bi-cell detector which detects the level of the liquid in the side tank.
Claim 53
Dependent Claim
93 words
The apparatus of claim 43 wherein the level detecting means comprises: a float which floats in said liquid in said vat; a beam having a first end coupled to said float, and a second end, which beam is rotatably coupled to a fixed point between the ends such that a vertical displacement of the float will result in a magnified vertical displacement of the beam second end; and means for detecting whether the second end is outside a predetermined displacement range indicating that the liquid level is not substantially at said predetermined level.
Claim 54
Dependent Claim
38 words
The apparatus of claim 42 wherein the doctor blade has a cross-section and the cross-section has a non-horizontal edge at the bottom of the blade in the direction of blade movement which makes an angle with the horizontal.
Claim 55
Dependent Claim
16 words
The apparatus of claim 46 wherein said angle is within a range of about 5-8 degrees.
Claim 56
Independent Claim
154 words
A method for setting the gap between a doctor blade, having two ends and a bottom, and a mass, and the surface of a polymerizable liquid in a stereolithography system to a predetermined value, comprising the steps of; releasably attaching two retractable needles to the bottom of the blade at each end such that each needle extends beyond the bottom substantially by said predetermined value; lowering one end of the blade by adjusting a first non-torque inducing screw means until the needle at that end touches the liquid surface; lowering the other end of the blade by adjusting a second non-torque inducing screw means until the needle at that end touches the liquid surface; raising and then lowering the blade and possibly readjusting said non-torque inducing screw means to ensure that both needles touch the liquid surface at about the same time; and retracting said needles without significantly changing the mass of the blade.
Claim 57
Independent Claim
154 words
A method for setting the gap between a doctor blade, having two ends and a bottom, and a mass, and the surface of a polymerizable liquid in a stereolithography system to a predetermined value, comprising the steps of; releasably attaching two retractable needles to the bottom of the blade at each end such that each needle extends beyond the bottom substantially by said predetermined value; lowering one end of the blade by adjusting a first non-torque inducing screw means until the needle at that end touches the liquid surface; lowering the other end of the blade by adjusting a second non-torque inducing screw means until the needle at that end touches the liquid surface; raising and then lowering the blade and possibly readjusting said non-torque inducing screw means to ensure that both needles touch the liquid surface at about the same time; and retracting said needles without significantly changing the mass of the blade.
Claim 58
Dependent Claim
14 words
The method of claim 48 wherein said non-torque inducing screw means are micrometer screws.
References Cited (Backward Citations)
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