US5096530A — Resin film recoating method and apparatus

Claim 1

Independent Claim 127 words

A method of creating a three-dimensional object through stereolithography comprising the steps of: a) first creating one thin liquid film or a plurality of thin liquid films, said film or films comprising a liquid polymerizable resin capable of solidifying upon exposure to synergistic stimulation and being supported by the force of surface tension and by a frame and then applying said film or films to a previously solidified layer; and b) forming a next layer of said object by at least partially solidifying at least one selected portion of said film or films applied to said previously solidified layer by exposing said at least one portion to said synergistic stimulation, said at least one portion corresponding to the cross-sectional shape at a given point of said object.

Claim 2

Independent Claim 127 words

A method of creating a three-dimensional object through stereolithography comprising the steps of: a) first creating one thin liquid film or a plurality of thin liquid films, said film or films comprising a liquid polymerizable resin capable of solidifying upon exposure to synergistic stimulation and being supported by the force of surface tension and by a frame and then applying said film or films to a previously solidified layer; and b) forming a next layer of said object by at least partially solidifying at least one selected portion of said film or films applied to said previously solidified layer by exposing said at least one portion to said synergistic stimulation, said at least one portion corresponding to the cross-sectional shape at a given point of said object.

Claim 3

Dependent Claim 19 words

The method of claim 1 further comprising the additional step of removing uncured resin from said film or films.

Claim 4

Dependent Claim 53 words

The method of claim 3 further comprising the steps of: loading liquid polymerizable resin in a tank; forming a film formed from said resin on a narrow end of a funnel; adjusting and monitoring the thickness of said film; flattening said film; checking for film disintegration; and stripping uncured resin from said film.

Claim 5

Dependent Claim 74 words

The method of claim 3 further comprising the steps of: applying a liquid polymerizable resin to a narrow end of a first funnel; and forming a first film of said resin applied to said narrow end across said narrow end and moving said first film to a wide end of said first funnel at about the same time as selectively exposing a second film which was similarly formed and moved in a second funnel.

Claim 6

Dependent Claim 49 words

The method of claim 4 further comprising the additional steps of: creating an air pressure difference between said narrow end and said wide end; applying said second film to said previously formed layer of said object; and stripping uncured resin from said second film after said selectively exposing step.

Claim 7

Dependent Claim 28 words

The method of claim 3 further comprising the steps of: forming said film across a film carrier; and applying said film to a working plane in a vat.

Claim 8

Dependent Claim 26 words

The method of claim 3 wherein said creating step includes: separately creating a flat film of said resin, said flat film having a small aspect ratio.

Claim 9

Dependent Claim 19 words

The method of claim 1, in which said film or films, once created are stretched to increase their area.

Claim 10

Dependent Claim 40 words

The method of claim 1, in which a plurality of films are used in the formation of at least one layer, such that the films have certain edges in common and are supported along these common edges by a frame.

Claim 11

Dependent Claim 20 words

The method of claim 9, further comprising the step of preventing exposure in the immediate vicinity of said common edges.

Claim 12

Dependent Claim 62 words

The method of claim 1, in which a plurality of films are used in the formation of at least one layer, such that a subset of film is created, applied, selectively cured and then stripped, followed by a similar process with remaining subsets of films, such that the total area covered by all subsets is as large as the desired working surface.

Claim 13

Dependent Claim 19 words

The method of claim 1, comprising the additional step of minimizing evaporation of volatiles from said film or films.

Claim 14

Dependent Claim 20 words

The method of claim 1 further comprising the additional step of adjusting the surface tension of said film or films.

Claim 15

Dependent Claim 19 words

The method of claim 13 wherein said adjusting step comprises the addition of a surfactant to said liquid resin.

Claim 16

Dependent Claim 32 words

The method of claim 1 further comprising the additional step of selecting the thickness of said film or films and wavelength of said exposure such that said thickness substantially exceeds said wavelength.

Claim 17

Dependent Claim 17 words

The method of claim 1 further comprising the additional step of condensing resin vapor prior to exposure.

Claim 18

Dependent Claim 24 words

The method of claim 1 further comprising the additional step of counteracting a tendency of said film or films to sag due to privacy.

Claim 19

Dependent Claim 16 words

The method of claim 17, wherein said counteracting step comprises vertically orienting said film or films.

Claim 20

Dependent Claim 22 words

The method of claim 1, in which said film is exposed immediately after stretching of the film, while in a non-equilibrium state.

Claim 21

Dependent Claim 28 words

The method of claim 1, in which stereolithographic parts are formed from at least one non-flat layer, which is the result of using gravitationally-sagged resin film or films.

Claim 22

Dependent Claim 34 words

The method of claim 1 further comprising the additional steps of sensing the integrity of said film prior to exposure, and regenerating a new film if the present one is sensed to have disintegrated.

Claim 23

Dependent Claim 39 words

The method of claim 1 further comprising the additional step of providing a film which is larger than that required to form the layer, such that exposure of said film in the vicinity of said frame can be avoided.

Claim 24

Dependent Claim 22 words

The method of claim 1 further comprising the additional step of flowing excess resin to a region outside a potentially-exposed film area.

Claim 25

Dependent Claim 38 words

The method of claim 23 wherein said flowing step comprises tilting said frame from the horizontal, such that the lowest point of said film or at least one of said films is outside the potentially exposed film area.

Claim 26

Dependent Claim 50 words

The method of claim 23 wherein said flowing step comprises providing greater gas pressure on a lower surface of said film or at least one of said films than on an upper surface, so as to make the upper surface convex to allow excess resin to flow to said frame.

Claim 27

Dependent Claim 27 words

The method of claim 1 further comprising the additional step of measuring an actual film thickness while draining, followed by exposure once the correct thickness is obtained.

Claim 28

Dependent Claim 34 words

The method of claim 26, in which any inaccuracies in film thickness are permitted to accumulate over a plurality of successive films before the net inaccuracy is corrected by a film of carefully-controlled thickness.

Claim 29

Independent Claim 87 words

An apparatus for creating a three-dimensional object through stereolithography comprising: means for supporting a previously formed portion of said object; means for creating and supporting a thin liquid resin film by the force of surface tension; means for applying said film to said previously formed portion of said object; a source of synergistic stimulation; and means for selectively exposing said film while in contact with said previously formed portion to said synergistic stimulation from said source to effect formation of an additional solid layer of said object.

Claim 30

Independent Claim 87 words

An apparatus for creating a three-dimensional object through stereolithography comprising: means for supporting a previously formed portion of said object; means for creating and supporting a thin liquid resin film by the force of surface tension; means for applying said film to said previously formed portion of said object; a source of synergistic stimulation; and means for selectively exposing said film while in contact with said previously formed portion to said synergistic stimulation from said source to effect formation of an additional solid layer of said object.

Claim 31

Dependent Claim 16 words

The apparatus of claim 28 further comprising removing means for removing uncured resin from said film.

Claim 32

Dependent Claim 129 words

The apparatus of claim 1 further comprising: a tank for holding liquid curable resin, said tank having a window; wherein said means for creating and supporting said thin liquid film comprises a funnel with a narrow end in said tank and with a wide end; detecting means for detecting integrity of a film formed at said narrow end of said funnel and moved to said wide end; wherein said means for supporting said previously formed portion of said object comprises a platform for supporting said previously formed portion of said object just outside said wide end and for moving said previously formed portion of said object to said wide end; wherein said source of synergistic stimulation is selectively applicable to said film at said wide end through said window.

Claim 33

Dependent Claim 22 words

The apparatus of claim 30 further comprising a valve in said tank for letting resin stripper into said tank and said funnel.

Claim 34

Dependent Claim 16 words

The apparatus of claim 30 further comprising air-pressure regulating means for regulating air-pressure in said tank.

Claim 35

Dependent Claim 16 words

The apparatus of claim 30 further comprising an interferometer for measuring the thickness of said film.

Claim 36

Dependent Claim 20 words

The apparatus of claim 30 further comprising drainage means for draining excess liquid from said funnel away from said window.

Claim 37

Dependent Claim 14 words

The apparatus of claim 30 further comprising a reverse taper at said wide end.

Claim 38

Dependent Claim 21 words

The apparatus of claim 30 wherein said window and said source are positioned to create a guard band on said film.

Claim 39

Dependent Claim 40 words

The apparatus of claim 1 wherein: said means for creating and forming said thin liquid film comprises a selected one of a plurality of rotatable funnels; and wherein said apparatus further comprises rotating means for rotating said plurality of funnels.

Claim 40

Dependent Claim 18 words

The apparatus of claim 37 further comprising a frame capable of receiving said film from said selected funnel.

Claim 41

Dependent Claim 20 words

The apparatus of claim 38 further comprising a mechanism for vertically moving said selective exposing means to contact said frame.

Claim 42

Dependent Claim 23 words

The apparatus of claim 37 further comprising a plurality of ridges on the inside of at least one of said plurality of funnels.

Claim 43

Dependent Claim 18 words

The apparatus of claim 37 wherein at least one of said plurality of funnels has a circular cross-section.

Claim 44

Dependent Claim 34 words

The apparatus of claim 37 further comprising a tank in which a narrow end of one of said plurality can be at least partially inserted, for initially forming said film across said narrow end.

Claim 45

Dependent Claim 26 words

The apparatus of claim 42 further comprising air pressure adjustment means for causing a difference in air pressure between said narrow end and said wide end.

Claim 46

Dependent Claim 21 words

The apparatus of claim 43 wherein said applying means applies a stretched film to said previously formed portion of said object.

Claim 47

Dependent Claim 85 words

The apparatus of claim 1 wherein said means for creating and supporting said film includes: a first film carrier; a delivery system for delivering a liquid resin to said film carrier; and a squeegee for creating said film from said portion across said film carrier; and wherein said apparatus further comprises a vat with a resin-tight piston for changing the vertical position of an object being formed; and a drive mechanism for moving said film carrier into position for transferring said film to said vat.

Claim 48

Dependent Claim 32 words

The apparatus of claim 45 wherein said means for creating and supporting said film further includes a second film carrier movable by said drive mechanism approximately simultaneously with said first film carrier.

Claim 49

Dependent Claim 22 words

The apparatus of claim 46 further comprising drip-catching means over which said drive mechanism can move said first and second film carriers.

Claim 50

Dependent Claim 20 words

The apparatus of claim 47 further comprising a retractable drip needle on each of said first and second film carriers.

Claim 51

Dependent Claim 18 words

The apparatus of claim 47 wherein said drip-catching means is below a tapered top edge of said vat.

Claim 52

Dependent Claim 19 words

The apparatus of claim 45 further comprising air pressure means for creating an air pressure differential across said film.

Claim 53

Dependent Claim 16 words

The apparatus of claim 45 further comprising an interferometer for measuring the thickness of said film.

Claim 54

Dependent Claim 28 words

The apparatus of claim 1 wherein said means for creating and supporting said film comprises means for creating and supporting a flat film having a small aspect ratio.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1995-03-17	1995-09-16	1996-03-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1999-03-17	1999-09-16	2000-03-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2003-03-17	2003-09-16	2004-03-17	$7700.00	Window Closed / Lapsed

Resin film recoating method and apparatus

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