JP2000043148A - Light shaping method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the amount of light energy to be emitted to a photo-setting liquid uniform. SOLUTION: When one of the sections obtained by slicing a desired shape into plural layers is formed, a radiation, point deciding means 34 decides a single or plural radiation points to which a light is emitted for setting the section based on the shape data of the section. Further optical apparatuses 6, 8, 10 arranged between a light source and a photo-setting liquid are regulated so that the light is emitted from the light source to one of the emission points. After regulating the optical apparatuses 6, 8, 10, the light is emitted to the one emission point and then is emitted to all of the radiation points for light shaping.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereolithography method and an apparatus therefor.

[0002]

2. Description of the Related Art An optical molding method is a method of irradiating a photocurable liquid with light, curing the photocurable liquid to form a hardened layer having a predetermined thickness, and sequentially stacking the hardened layers. This is a method of forming an object having a three-dimensional shape. The stereolithography method will be described with reference to FIG. Here, the object 110 to be formed has a three-dimensional shape, but for convenience of explanation, FIG. 1 shows only the height direction and the horizontal direction. First, the inside of the container 104 is filled with the photocurable liquid 108, and the table 106 disposed in the photocurable liquid 108 is submerged from the liquid surface by the thickness of the photocurable liquid to be cured (moved in the Z direction). . In this state, the light 100 from the light source is scanned and cured on the surface of the photo-curable liquid 108 by changing the angle of the deflector (galvanometer mirror) 102. Next, the table 106 is moved in the Z direction by the thickness of the layer to be cured next. And similarly, the light 10 from the light source
0 is scanned and cured on the surface of the photocurable liquid 108.
As described above, by stacking the cured layers having a certain thickness, an object having a desired shape is formed on the table 106.

Here, in FIG. 11, a case where the light 100 is scanned from the point a to the point b to cure the photocurable liquid 108 is considered. FIG. 12 shows the scanning speed of the light 100 at each position from point a to point b in the upper part, and the depth of the photocurable liquid to be cured in the lower part. As shown in the upper part of FIG.
The scanning speed of 00 is accelerated near the point a (starting point) (acceleration range), passes through a period of moving at a constant speed (constant speed range), and is decelerated near point b (end point) (deceleration range). In this case, if the light intensity of the light 100 is constant, the irradiation time by the light 100 becomes longer in the acceleration region and the deceleration region,
The amount of light energy applied to this area increases. For this reason, as shown in the lower part of FIG. 12, the depth of the photocurable liquid cured by the light 100 is deeper in the acceleration region and the deceleration region than in the constant velocity region. Therefore, this is a major problem in improving the shape accuracy of the modeled object. As described above, in the conventional optical shaping method of curing the photocurable liquid by scanning light, the amount of light energy applied to the photocurable liquid is non-uniform due to the above-described acceleration / deceleration region. There was a problem.

Therefore, a technique described in Japanese Patent Application Laid-Open No. 9-9940 is known for controlling and uniformizing the amount of light energy applied to the photocurable liquid. In this method, an optical modulator is installed between the light source and the container containing the photocurable liquid, the optical modulator is controlled in synchronization with the deflector, and the irradiation time of light applied to each point is changed. Let it. For example, in FIG. 11, when scanning from point a to point b, first,
The scanning speed (speed information) of light at each point from point a to point b is determined in advance. Next, the angle of the deflector (galvanometer mirror) 102 is controlled so that the scanning speed at each point is in accordance with the speed information, and at the same time, the optical modulator is controlled based on the speed information. That is, when the scanning speed is low, the light intensity of the light is reduced, and when the scanning speed is high, the light intensity of the light is increased. By doing this,
The deflector and the optical modulator can be controlled synchronously, and the control is performed so that the amount of light energy applied to each point becomes uniform.

[0005]

However, in order to synchronize the deflector and the optical modulator, a delay in response to an actual command signal (transient characteristic) as shown in FIG. ) Must be checked in advance, and a control signal must be output to the optical modulator in consideration of this response delay. In particular,
Even if the deflectors have the same specifications, there are individual differences (variations) in the transient characteristics, so it is necessary to consider the transient characteristics for each deflector used in each device. It was difficult to do. For this reason, the conventional method,
The apparatus has a problem that the amount of light energy applied to the photocurable liquid becomes non-uniform.

[0006]

Therefore, in order to solve the above-mentioned problems, the optical shaping method according to the first aspect of the present invention provides at least one of a cross-sectional group obtained by slicing a desired shape into a plurality of layers. A method of modeling a partial region of a cross section, comprising: determining one or more irradiation points to be irradiated with light to cure the region from shape data of the region; In the meantime, as the light from the light source is irradiated, an adjusting step of adjusting the optical device disposed between the light source and the photocurable liquid, and after the optical device is adjusted, the light is irradiated to one of the irradiation points. And an irradiation step of irradiating light, and the region is formed by repeating the adjustment step and the irradiation step at all of the irradiation points. According to the above method, each of the determined irradiation points is aligned so that light is irradiated, and the points are irradiated with light to form this area. Since light is not scanned during irradiation with light, there is no need to consider a delay in response when moving the irradiation point, and the amount of irradiated light energy can be made uniform.

The stereolithography method according to the second aspect is the first aspect of the invention.
In the optical modeling method described above, a step of determining the irradiation point is performed on an outer peripheral region of a cross section to be formed, and the irradiation point obtained in the step is formed by repeating the adjustment step and the irradiation step. The inner region of the cross section to be formed is formed by scanning light from a light source on the photocurable liquid surface. According to the above method, the outer peripheral region of the cross section of the modeled object where the shape accuracy of the modeled object is required is formed by repeating the alignment process and the irradiation process, and the inner region where the accuracy is not so much required is scanned with light. It is shaped by doing. Therefore, it is possible to make the amount of light energy applied to the outer peripheral region of the modeled object uniform and improve the shape accuracy of the modeled product without prolonging the modeling time.

[0008] The stereolithography method according to the third aspect is the first aspect of the invention.
In the stereolithography method described above, the time for irradiating the photocurable liquid with light in the irradiating step is determined based on the measured light intensity of the light irradiated from the light source.
According to the above method, the light intensity of the light applied to the photocurable liquid is measured, and the irradiation time is determined based on this value. Irradiation time is determined in consideration of the fluctuation.
Therefore, the amount of irradiated light energy can be made more uniform.

According to a fourth aspect of the present invention, there is provided an optical shaping apparatus, wherein, in one cross section of a cross section group obtained by slicing a desired shaping shape into a plurality of layers, based on shape data of the entire cross section or a designated region. Irradiation point determining means for determining one or more irradiation points on the photocurable liquid surface to be irradiated with light from the light source, disposed between the light source and the photocurable liquid, the light source at the irradiation point Irradiation position control means for controlling the irradiation position of light so that the light emitted from the light is irradiated, disposed between the light source and the photocurable liquid, the light intensity of the light irradiated to the irradiation point and And / or light energy control means for controlling the irradiation time. In the above device, the irradiation point determined by the irradiation point determination unit is irradiated with light from the light source by the irradiation position control unit, and the irradiation point is irradiated with a predetermined amount of light energy by the light energy control unit. Can be. Therefore, it is not necessary to consider the response delay when the irradiation point is moved, so that the amount of light energy applied to each irradiation point can be easily set to the same value.

According to a fifth aspect of the present invention, in the optical forming apparatus according to the fourth aspect, a light intensity of light emitted from the light source is measured between the light source and the photocurable liquid. The light energy control means controls the light intensity and / or irradiation time of the light applied to the irradiation point based on the value detected by the light detector. In the above device, even if the light intensity of the light emitted from the light source changes with time, this change can be detected by the photodetector arranged between the light source and the photocurable liquid, and the change is detected by the light energy. It can be compensated by the control means. Therefore, the amount of irradiated light energy can be made more uniform.

According to a sixth aspect of the present invention, in the optical forming apparatus according to the fourth aspect, the irradiation position control means is a deflecting mirror, and the coordinates of each irradiation point determined by the irradiation point determination means. A reflection efficiency calculating means for calculating the reflection efficiency of the deflecting mirror from the angle of incidence of the light on the deflecting mirror when irradiating each irradiation point, and taking into account the reflection efficiency obtained by the reflection efficiency calculating means. The light energy control means controls the light intensity and / or irradiation time of the light applied to each irradiation point. In the above device, the reflection efficiency of the deflecting mirror is calculated from the angle of incidence of the light on the deflecting mirror when irradiating each irradiation point, and based on the calculated value, the light energy control means controls the energy of the light irradiating the photocurable liquid. Control the amount. Therefore, the amount of irradiated light energy can be made more uniform.

[0012] In the stereolithography method according to claim 7, a moving step of moving the light irradiation point in a state where the light is not irradiated to the photocurable liquid; An irradiation step of irradiating the liquid with an ionic liquid, wherein the moving step and the irradiation step are repeated, and the area to be cured is filled with a beam spot formed by the irradiated light to form the object. According to the above method, the light irradiation point moves in a state where the light irradiation is not performed, and the light irradiation point does not move when the light irradiation is performed.
Therefore, it is not necessary to consider a response delay when the light irradiation point is moved, so that the amount of irradiated light energy can be made uniform.

In the optical shaping apparatus according to the present invention, a moving means for moving the light irradiation point in a state where the light is not irradiated to the photocurable liquid; Irradiating means for irradiating the liquid, and shaping the area to be cured with a beam spot formed by the irradiated light. According to the above apparatus, the light irradiation point moves by the moving means in a state where the light is not irradiated, and the light is irradiated by the irradiation means when the light irradiation point does not move. Therefore, it is not necessary to consider a response delay when the light irradiation point is moved, so that the amount of irradiated light energy can be made uniform.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 shows an overall configuration diagram of an optical shaping apparatus according to the present invention. In this optical shaping apparatus, a laser oscillator 2 such as a He-Cd laser or an Ar laser is used as a light source. The laser beam 26 emitted from the laser oscillator 2 is
The direction can be changed by the reflection mirror 20, and it is an optical modulator.
The light enters an AOM (acousto-optic light modulator) 4. A part of the laser light 26 emitted from the AOM 4 is transmitted by the semi-transmissive mirror 22, and the rest can be changed in direction. Transflective mirror 2
The light intensity of the laser beam 27 that has passed through 2 is measured by the photodetector 18. On the other hand, the redirected laser light 26
The light enters the focus lens 6. The laser light 26 emitted from the focus lens 6 is changed in its direction by galvanometer mirrors 8 and 10 as deflectors, passes through the fθ lens 12, and is incident on the photocurable liquid in the container 14. Have been. Further, the AOM 4, the focus lens 6, and the galvanometer mirrors 8 and 10 are controlled by the control device 16, and the light intensity detected by the photodetector 18 is transmitted to the control device 16 as a signal. .

The AOM 4 has a function of controlling the light intensity and the irradiation time of the laser light applied to the photocurable liquid. That is, the AOM 4 modulates the incident laser light and goes straight.
It decomposes into zero-order light and slightly deflected primary light. The primary light is
Since the light is slightly deflected with respect to the 0th-order light, either component of this decomposed light is cut off by the slit so that the light emitted from the AOM 4 becomes only the 0th-order light or the 1st-order light. Can be. Therefore, by changing the voltage of the ultrasonic wave applied to the AOM 4, the ratio of the zero-order light to the primary light can be changed, and the light intensity of the light emitted from the AOM 4 can be changed. Also, by adjusting the voltage applied to the AOM 4 so that the laser light decomposed by the AOM 4 is only the 0th-order light or the 1st-order light, the laser light may or may not pass through the AOM4. it can. Therefore, AOM
4 has a function as a shuttering device, and can control a time for transmitting light through the AOM 4 by switching an applied voltage, and as a result, the photocurable liquid is irradiated with laser light. Time can be controlled. Therefore, since the AOM 4 can change the light intensity and irradiation time of the laser light, the AOM 4 can control the energy amount of light irradiated on the photocurable liquid. That is, A
OM4 corresponds to light energy control means. In addition, EOM (Electro-Optical Light Modulator)
Can perform a similar function. Thus, AO
M4 has a function of controlling the light intensity and irradiation time of the laser beam. In the present embodiment, the transmittance is 100% or 0%.
(Shutter fully open or fully closed), and only the irradiation time is controlled.

The semi-transmissive mirror 22 is adjusted to transmit about several percent of the laser light 26 emitted from the laser oscillator 2. The light intensity of the transmitted laser light 27 is detected by the photodetector 18. Photodetector 18
Measures the light intensity from the start of modeling to the end of modeling. This is because the output of the laser oscillator 2 gradually decreases with time, and the transmittance of the AOM 4 also changes with time. Therefore, at the photodetector 18,
The controller 1 measures the light intensity of the laser light transmitted through the AOM 4
6 and the information is transmitted. The control device 16 compensates for this change by controlling the time of the laser light passing through the AOM 4, that is, controlling the irradiation time of the laser light applied to the photocurable liquid. As a method of compensating for this change, there is a method of using a laser oscillator having a mechanism for keeping the output of the laser oscillator constant, but there is a disadvantage that the laser oscillator becomes expensive. Also, even if such a thing is used as a laser oscillator,
A case where the transmittance of AOM 4 changes with time cannot be handled. Further, the reflection mirror 20 can be a semi-transmissive mirror, and the light intensity can be measured at this location. In this case, AO
Although the change over time of M4 cannot be compensated, even when the AOM 4 does not transmit laser light, the light intensity of the laser light emitted from the laser oscillator can be measured, so that the change over time of the laser oscillator can be compensated more accurately.

The focus lens 6 adjusts the laser beam 26 emitted from the laser oscillator 2 so as to irradiate the surface of the photocurable liquid in the container 14 with a predetermined laser focus diameter. That is, when the angle of the mirrors of the galvanometer mirrors 8 and 10 changes and the position irradiated with the laser light changes, the optical path length from the laser oscillator 2 to the photocurable liquid changes. Therefore, the change is corrected by the focus lens 6. In the present embodiment,
Since the laser focus diameter of the irradiated laser beam 26 is variable, the focus lens 6 controls the laser focus diameter. The laser focus diameter of the laser beam is an important factor that determines the shape of the photocurable liquid to be cured. That is, when the laser focus diameter is increased, the peak intensity decreases, and the curing width increases, while the curing depth decreases. Therefore, by controlling the laser focus diameter, it is possible to obtain a cured shape that matches the shape of the modeled object.

Each of the galvanometer mirrors 8 and 10 comprises a deflecting mirror and a motor for rotating the deflecting mirror. That is, when the motor rotates, the deflection mirror rotates, and the incident angle with respect to the laser beam is changed.
Therefore, by changing the rotation angle of the deflecting mirror,
The position where the laser beam is irradiated on the photocurable liquid surface can be changed. In the present embodiment, the irradiation position in the Y direction can be changed by the galvanometer mirror 8 and the irradiation position in the X direction can be changed by the galvanometer mirror 10. Therefore, in the present embodiment, the galvanometer mirrors 8 and 10 serve as irradiation position control means. In addition, galvanometer mirror 8
By rotating the angle of the galvanometer mirror 10 without changing the angle of the deflecting mirror, the laser beam can be scanned in the X direction on the surface of the photocurable liquid. vice versa,
By rotating the angle of the galvanometer mirror 8 without changing the angle of the deflecting mirror of the galvanometer mirror 10, laser light can be scanned in the Y direction on the liquid surface of the photocurable liquid.

The fθ lens 12 is formed by combining several lenses, and is for condensing light with a uniform laser focus diameter over the entire surface of the photocurable liquid.

The container 14 contains a photo-curable liquid, and the photo-curable liquid is cured by irradiating the photo-curable liquid with light having a predetermined light energy or more. Further, a table 15 for supporting the modeled object 24 is provided in the container 14. The depth of the table 15 from the liquid level is adjusted based on the value of a high-precision distance sensor (not shown) that detects the height of the liquid level.

Next, the configuration of the control device 16 will be described with reference to FIG.
It will be described based on. The control device 16 is configured by a general computer, appropriately calls a program stored in a ROM or the like, processes data stored in various files or the like, and generates a signal for controlling each device. Send to each device. More specifically, a data processing unit 30 that performs various types of data processing, which will be described later, from three-dimensional data or the like of a desired shape to be formed, and an AOM 4 or a galvanometer mirror 8 based on the data processed by the data processing unit 30.
And a control unit 31 for transmitting a control signal to each device such as 10.

The data processing unit 30 includes a three-dimensional modeling data storage unit 32 in which three-dimensional data of a desired shape is stored;
It has an irradiation point determining means 34 for determining an irradiation point to be irradiated with laser light, a reflection efficiency determining means 35 for determining the reflection efficiency of the galvanometer mirrors 8 and 10, and an irradiation time determining means 36 for determining an irradiation time. .

The three-dimensional model data storage means 32 is a three-dimensional model programming device (not shown), for example, a so-called CA.
Connected to D. Then, the three-dimensional shape data of the three-dimensional object programmed by the three-dimensional shape programming device is sent to and stored in the three-dimensional object data storage unit 32. From this three-dimensional shape data, two-dimensional shape data of each section obtained by slicing the desired shape into a plurality of layers can be obtained, and the region of the photocurable liquid to be cured in each section can be determined.

The irradiation point determining means 34 determines an irradiation point to be irradiated with laser light based on the data stored in the three-dimensional printing data storage means 32 and the laser focus diameter appropriately selected by the operator. Here, the laser focus diameter is a range irradiated with laser light, and is a diameter of a beam spot. For the specific procedure, see FIG.
This will be described below with reference to FIG. First, the area that must be cured in each section is stored in the three-dimensional modeling data storage unit 3.
2 is determined from the shape data stored in. Next, a pitch p between adjacent irradiation points is determined. FIG. 3 is a drawing showing the relationship between the irradiation point and the laser focus diameter. FIG.
, Points O 1, O ′ represent irradiation points, and circles surrounding the points O 1, O ′ represent laser focus diameters of laser light when irradiating the irradiation points O 1, O ′. Therefore, the overlapping of the two circles indicates that the laser beams applied to the adjacent irradiation points O 1 and O ′ overlap. The reason why the laser focus diameters of the laser beams applied to the adjacent irradiation points overlap each other is that the photocurable liquid existing between the adjacent irradiation points is cured without interruption. Because
The light intensity of the laser light is highest at the irradiation point (center) and decreases as the distance from the irradiation point increases. Therefore, as the distance from the center of the laser beam increases, the amount of energy incident on the photocurable liquid decreases, and a portion that does not cure even when irradiated with the laser beam occurs. In FIG. 3, when the laser focus diameter is d and the overlapping width is r, the pitch p between the adjacent irradiation points is generally set so that the value of r / d is in the range of 0.3 to 0.5. It is determined. However,
If the accuracy of the desired shape is required to be high (when the thickness of the cross section must be reduced), the width (curing width) and depth (curing depth) of the photocurable liquid that is cured by a single irradiation ) Needs to be smaller. Therefore, the irradiation time is shortened, and the width of the photocurable liquid to be cured is reduced. Since the width is reduced, the pitch p between the irradiation points is further reduced. That is, the value of r / d is 0.5 or more. Conversely, when the precision of the desired shape is not so required (when the thickness of the cross section can be increased), the irradiation time of the laser beam can be lengthened, and the curing width and curing depth by one irradiation can be increased. Therefore, as the width of the photocurable liquid to be cured increases, the pitch p between the irradiation points also increases. That is, the value of r / d is 0.3 or less. Therefore, the irradiation time is determined by the thickness to be cured (cross-section thickness) and the laser focus diameter, and if the irradiation time is determined, the curing width can also be determined. Can be determined.

Next, from the pitch p between the irradiation points determined by the above-described process and the shape data of the region to be cured, the coordinates of the irradiation point for curing the entire region without any gap are determined. This process will be described by taking as an example a case where the area demarcated by the boundary lines 50 and 51 is cured on the XY plane shown in FIG. Here, the pitch between the irradiation points is p. First, the region to be cured is divided into regions 52, 53, and 54 sliced by a straight line parallel to the x-axis.
Next, the coordinates of the irradiation point A in the area 52 are determined. The y coordinate of the irradiation point A in the region 52 can be determined from the y coordinate of the boundary line 50 and the width of the photocurable liquid that is cured by one irradiation.
That is, the value obtained by adding the value of the y-coordinate of the boundary 50 to the width of the photocurable liquid that is cured by one irradiation is the y-coordinate of the point A. Similarly, from the x coordinate of the boundary line 51 and the width of the photocurable liquid that is cured by one irradiation, the irradiation point A in the region 52 is determined.
Can be determined. When the coordinates of the point A are determined, the pitch between the irradiation points is p, so that the coordinates of the point B and the point C can be sequentially determined. Since the y coordinate of the irradiation point in the area 53 is obtained by adding the pitch p to the y coordinate of the irradiation point in the area 52, the y coordinate of the point D can be determined. Similarly, point D,
The coordinates of E and F can be determined. The irradiation point in the area 54 can be determined in the same procedure.

In FIG. 4A, each area 52, 5
The x-coordinate of the irradiation point at 3, 54 (eg, points A, D,
The x-coordinate of G has the same value, but the x-coordinate of the irradiation point in each region may be shifted by p / 2 in the x-direction, as shown in FIG. When each irradiation point is irradiated with the irradiation pattern shown in FIG. 4A, for example, points A, B, D,
In the region surrounded by E, there is a portion where the laser light is irradiated four times in an overlapping manner, although it differs depending on the value of r / d described above.
In such a portion, there is a problem that the curing depth becomes too deep as compared with other portions. However, FIG.
In the case of (b), the number of times of laser irradiation is 3
Times, such problems are alleviated.

In the above-described method, each of the regions 52, 53, 5 obtained by slicing the region to be cured by a straight line parallel to the x-axis.
Although the irradiation point is determined in four steps, the irradiation point may be determined by slicing a region to be cured by a straight line parallel to the y-axis. Further, the irradiation point may be determined on a scanning line on which the laser beam is scanned in the conventional method of forming a shape by scanning the laser beam. In this method, scan lines are determined in the same manner as before,
The coordinates of the two points closest to the boundary at both ends of the scanning line may be determined, and the remaining irradiation points may be determined. According to this method, the conventional method can be diverted as it is, and software development can be shortened.

The reflection efficiency determining means 35 calculates the reflection efficiency of the galvanometer mirrors 8 and 10 from the XY coordinates of the irradiation point determined by the irradiation point determining means 34. Hereinafter, FIG.
The relationship between the irradiation point and the reflection efficiency will be described based on FIG. Here, FIG. 5 is a diagram schematically showing a state in which the laser beam 28 is incident on the galvanometer mirrors 8 and 10 and is deflected. FIG. 6 shows the relationship between the reflection efficiency η and the incident angle θ. In the optical shaping apparatus shown in FIG. 1, the irradiation position of the laser beam 26 is controlled by changing the mirror angles of the galvanometer mirrors 8 and 10. FIG. 5 (a), FIG.
If the angle of the galvanometer mirrors 8 and 10 changes as shown in FIG. 5B and FIG. 5C, the angle of incidence of the laser beam 26 on the galvanometer mirrors 8 and 10 changes. Therefore, if the irradiation points are different, the incident angles of the laser light 26 on the galvanometer mirrors 8 and 10 will also be different. Therefore, if the irradiation point is determined, the mirror angle of the galvanometer mirrors 8 and 10 can be determined, and the incident angle of the laser beam 26 when the laser beam 26 is irradiated to each irradiation point can be calculated. In addition, galvanometer mirrors 8, 1
Not all of the laser light incident on 0 is reflected, and several percent of the incident laser light disappears.
As shown in FIG. 6, the ratio of reflection by the galvanometer mirror (reflection efficiency) varies from 99.9 to 9 depending on the angle of incidence of the laser beam 26 on the galvanometer mirrors 8 and 10.
A difference of about 7% occurs. Therefore, if the irradiation point is determined, the angle of incidence of the laser beam on the galvanometer mirrors 8 and 10 can be determined, and the reflection efficiency can be determined.

The irradiation time determining means 36 determines the irradiation time at each irradiation point. Specifically, first, assuming that the reflection efficiency of the galvanometer mirror is 100%, a reference irradiation time is determined from the laser focus diameter selected by the operator and the thickness of the photocurable liquid to be cured. Next, the actual irradiation time is calculated in consideration of the reflection efficiencies of the galvanometer mirrors 8 and 10 obtained by the reflection efficiency determining means 35. For example, if the reflection efficiency is 98%, the irradiation time is set to 100/98 times. Also,
The output of the laser oscillator 2 changes with time, and the transmittance of the AOM 4 also changes with time. Therefore, when the light intensity emitted from the laser oscillator 2 and passed through the AOM 4 changes with the elapse of time, the light detector 18 detects this change, corrects the change, and reduces the irradiation time. decide. For example, when the light intensity of the laser beam detected by the photodetector 18 is reduced by 2%, the irradiation time is set to 100/98 times. As described above, the irradiation time determination unit 36 determines the irradiation time by correcting the temporal change of the light intensity of the laser beam 26 and the change of the reflection efficiency due to the change of the irradiation point for each irradiation point.

The controller 31 controls the table 15 in the container 14
A table position control unit 37 for transmitting a signal for controlling the position of the laser beam from the liquid surface, and galvanometer mirrors 8 and 10 so that the laser light is applied to each of the irradiation points determined by the irradiation point determination unit 34. A galvanometer mirror control unit 38 for transmitting a signal for controlling the rotation angle of the lens, and a focusing lens so that each of the irradiation points determined by the irradiation point determining means 34 is irradiated with a laser beam with a predetermined laser focus diameter. A focus lens control unit 39 for transmitting a signal for controlling the AOM 6; and an AOM control unit for transmitting a signal for controlling the AOM 4 for irradiating the laser light for the irradiation time determined by the irradiation time determining means 36. Having.

Next, the operation of the optical shaping apparatus when forming the modeled object 24 using the optical shaping apparatus shown in FIG. 1 will be described. Here, in the optical shaping apparatus, a desired shape is sliced into a plurality of layers, each sliced layer is cured, and the cured layers are stacked to form a desired shape. The procedure of stacking and forming each layer can be performed in the same manner as the existing procedure, and hence the following description will focus on the procedure for forming each section.

First, the procedure for curing one section will be described with reference to FIGS. FIG. 7 is a representation in which shapes that are cured by irradiating each irradiation point with light are superimposed. As shown in FIG. 7, in the present embodiment, the laser focus diameter of the laser light to be irradiated is changed between the outer peripheral region 60 of the modeled object and the inner region 62 thereof. This is because the outer peripheral area is directly related to the shape accuracy, so it is necessary to reduce the laser focus diameter and the curing width of the shape 64 cured by one irradiation.
On the other hand, since it is considered that the internal region does not require much shape accuracy, the laser focus diameter is increased and the curing width of the shape 66 cured by one irradiation is increased. Thus, the number of irradiation points in the internal region 62 can be reduced, and the molding time can be reduced.

FIG. 8 is a flowchart for curing each section. First, a region to be cured in the cross section is divided into one or a plurality of regions (S1). In the case of FIG. 7, the object is divided into an outer peripheral area 60 and an inner area 62. This division is performed by an operator inputting data to the control device 16 from an input device (not shown). Next, S1
One of the areas divided by is selected (S2). In the case of FIG. 7, either the outer peripheral area 60 or the inner area 62 of the modeled object is selected. This selection may be made by inputting by the operator himself or automatically by a program. Next, in the region selected in S2, the laser focus diameter of the laser beam to be irradiated is determined (S3). The laser focus diameter is set by an operator inputting to the control device 16 from an input device (not shown). In the case of FIG. 7, different values are set for the outer peripheral area 60 and the inner area 62. When the laser focus diameter is set, the irradiation point in the selected area is determined by the irradiation point determination unit 34.
It is determined by the above-described procedure (S4).

When the irradiation point is determined, one of the irradiation points is selected (S5). Next, the angles of the galvanometer mirrors 8 and 10 are adjusted so that the selected irradiation point is irradiated with the laser beam (S6). At this time,
At the same time, the focus lens 6 is adjusted (controlled) so that the laser beam is irradiated on the photocurable liquid with the laser focus diameter determined in S3. Galvanometer mirror 8,
After the adjustment of the focus lens 6 and the adjustment of the focus lens 6, the irradiation time of the irradiation point aligned in S6 is set to the irradiation time determination unit
6 (S7). In the present embodiment, S6
Was performed after S7, but S7 may be performed before S6 or may be performed simultaneously. Once the irradiation time is determined, S5
The laser beam is irradiated to the irradiation point that has been aligned in step S6 for the irradiation time determined in step S6 (S8). Here, the irradiation time is controlled by controlling the AOM 4. This cures the photocurable liquid within a predetermined range around the irradiation point. In the case of FIG.
The shape indicated by 4 is hardened, and the shape indicated by 66 is hardened in the inner region 62. When the irradiation is completed, it is determined whether there is an irradiation point that has not been irradiated in the area selected in S2 (S9). If there is an irradiation point that has not been irradiated, the steps from S5 to S9 are sequentially repeated. Will be.

At this time (when the steps S5 to S9 are repeated), the operation of each device of the optical molding apparatus shown in FIG.
A description will be given based on FIG. In the lower part of FIG. 9, the horizontal axis represents time passage, and the vertical axis represents the position (angle of the galvanometer mirror) where the laser beam is irradiated.
FIG. The lower part of FIG.
The light energy applied to the photocurable liquid by the irradiation shown in (1) and the shape of the photocurable liquid cured by the irradiation are shown in the upper part in an overlapping manner. According to the method,
First, the voltage applied to AOM4 is adjusted so that the laser light
OM4 does not transmit (shutter closed)
Then, the angles of the galvanometer mirrors 8 and 10 are adjusted so that the first irradiation point is irradiated with the laser beam. At this time, the laser focus diameter is simultaneously adjusted to a predetermined laser focus diameter by the focus lens 6. Next, A
The voltage applied to the OM 4 is changed so that the laser light emitted from the laser oscillator 2 passes through the AOM 4 for a predetermined time t1 (the shutter is opened), and the photocurable liquid is irradiated with the laser light. This predetermined time t1 is the time determined in S7. Here, the photodetector 18 considered in S7
Is the value detected by the photodetector 18 when irradiating the previous irradiation point. This is because the light is not transmitted through the AOM 4 while the position is adjusted so that each irradiation point is irradiated. In addition, if the photodetector is installed before the AOM 4, the irradiation time can be determined based on the value immediately before the irradiation, but in this case, it is not possible to compensate for the aging of the AOM 4. When the first irradiation point is irradiated for a predetermined time t1, the AOM 4 is closed, and the galvanometer mirrors 8, 10 are adjusted so that the second irradiation point is irradiated with the laser beam. Hereinafter, each device repeats the same operation as described above. With this shaping, the galvanometer mirror is not operated while the AOM 4 is open, so that the amount of light energy applied to each irradiation point is controlled only by the AOM 4. Therefore, since the AOM 4 does not need to be synchronized with another device, the amount of light energy applied to each irradiation point becomes uniform as shown in the lower part of FIG. Since the amount of light energy to be irradiated becomes uniform, the cured shape becomes the same as shown in the upper part of FIG. Therefore, the accuracy of the formed object is also improved.

When the irradiation has been completed for all the irradiation points in the selected area, the process proceeds to the next step (S10). S10
Then, it is determined whether or not all the divided areas have been irradiated on the cross section. If all the areas have not been irradiated, the steps from S2 to S9 are repeated for the non-irradiated areas. In the case of FIG. 7, for example, irradiation is first performed on the outer peripheral region 60, and then irradiation is performed on the inner region 62. When the irradiation is completed for all the regions, there is no longer any region to be cured in the cross section, and the irradiation in the cross section is terminated.

When the curing of one section is completed by the above-described procedure, the table 15 in the container 14 is sunk from the surface of the photocurable liquid by a predetermined depth to cure the next section. In this way, the three-dimensional shape is formed by stacking the cured layers of each cross section.

As described above, in the optical shaping method according to the present embodiment, the angle control of the galvanometer mirrors 8 and 10, the control of the focus lens 6, and the control of the irradiation time (AOM)
4) is performed separately, so that it is not necessary to synchronize each device, so that the control device can be realized simply and at low cost. Further, the amount of light energy applied to the photocurable liquid only needs to keep the output of the laser oscillator 2 constant (light intensity constant) and control only the irradiation time (control of the AOM 4). Therefore, the amount of energy applied to the photocurable liquid can be easily controlled to an arbitrary value, and the amount of applied light energy can be uniformly applied over the entire region to be cured. Since the amount of light energy applied to each irradiation point is the same, the shape cured by one irradiation also has the same shape, and a desired curing width and desired effect depth can be obtained. Therefore, the shape accuracy of the modeled object can be improved. In particular, the galvanometer mirror has poor dynamic control characteristics, but has extremely high static position accuracy.
It has a position accuracy of about μm. Therefore, according to the above-described method, since the laser light is irradiated while the galvanometer mirror is stationary, the laser light is irradiated to an accurate location, and the shape accuracy of the object is improved.

In the above-described method, the irradiation time at each point is changed in consideration of the influence of the reflection efficiency of the galvanometer mirror, so that the amount of light energy applied to the photocurable liquid is made more uniform. Can be. That is, in the conventional method of scanning laser light, since the angle of the galvanometer mirror changes every moment, it is not possible to calculate the reflection efficiency from the angle of the galvanometer mirror at each point and control the irradiation time at each point. Realistically difficult. However, in the above-described method, since the laser light is irradiated after the angle of the galvanometer mirror is adjusted so that the laser light is irradiated to the irradiation point, the reflection efficiency is calculated in advance from the coordinates of the irradiation point, and May be determined in consideration of the irradiation time. Therefore, the present method makes it possible to consider the reflection efficiency of the galvanometer mirror.
In the method described above, the laser output changes with time and A
The change with time of the transmittance of OM4 can be considered. In a conventional method of scanning a laser beam, a method of detecting such a temporal change and feeding back to the AOM to increase or decrease the irradiation time may be considered, but a command is actually issued to the AOM after detecting the temporal change. By the time there is always a time delay. Therefore, in the method of scanning with laser light,
There is always a range irradiated without compensating for the change with time. However, according to the above-described method, since the laser beam is irradiated after the angle adjustment of the galvanometer mirror is performed, such a change amount based on the light intensity immediately before the irradiation of the laser beam at each irradiation point is performed. Can be compensated for. In the above-described method, even when the laser beam is irradiated to the previous irradiation point and the temporal change appears during the alignment of the next irradiation point, such a temporal change is caused. Cannot be compensated. However, since such time is short in practice, it is possible to substantially compensate for the change with time of the laser output and the change with time of the transmittance of the AOM 4.

The cured shape of the photocurable liquid is determined by the amount of light energy applied to the photocurable liquid. Therefore, assuming that the output of the laser oscillator is constant (constant light intensity), parameters for setting the cured shape of the photocurable liquid include laser energy distribution, laser focus diameter, and irradiation time. Here, it is known that the energy distribution of a laser generally differs greatly for each laser oscillator even if the output is the same. Therefore, when trying to improve the accuracy of the cured shape, it is important to consider what range (the size of the laser focus diameter) and what energy distribution is to be applied. Therefore,
It is preferable to appropriately change the laser focus diameter on one scanning line depending on the place to be formed. However, with the conventional method of scanning with laser light, it was difficult to change the laser focus diameter during scanning and control the cured shape. However, in the method of the present embodiment, the laser focus diameter can be changed at each irradiation point. Therefore, if the energy distribution of the laser oscillator is checked in advance by experiments or the like, the optimum laser focus can be adjusted in accordance with this energy distribution. The diameter can be selected.

Next, a modified example of the above-described embodiment will be described. In the above-described embodiment, the amount of light energy applied to the photocurable liquid is controlled by changing the irradiation time while keeping the light intensity of the laser beam constant (AOM 4 is fully opened or completely closed). By changing the light intensity, that is, by changing the light intensity while keeping the irradiation time constant, the amount of light energy to be irradiated may be controlled. Also,
Control may be performed by changing both (light intensity and irradiation time). In the above-described embodiment, the irradiation is performed while changing the laser focus diameter of the laser light to be irradiated in the outer peripheral area and the inner area. However, it is needless to say that the entire area may be irradiated with a single laser focus diameter. This is because, when small objects such as connectors are required and high-precision modeling is required, high-precision irradiation is also required in the internal region. Conversely, only the outer peripheral region is formed by the forming method according to the present invention,
The internal region may be formed by a method of scanning with a laser beam as in the related art. The outer peripheral region is formed by the shaping method according to the present invention because shape accuracy is required, but the inner region is formed by the same method of scanning with laser light as in the related art since the shape accuracy is not so affected. . In this case, since the exposed area of the inner region is often considerably larger than the exposed area of the outer peripheral region, the molding time can be reduced. In addition, modeling may be performed using a different irradiation pattern in each cross section. For example, when one section is formed by the irradiation pattern shown in FIG. 5A, the next section is formed by the irradiation pattern shown in FIG. 5B, or the coordinates of the irradiation point shown in FIG. In the x direction (or y
Direction) with a half pitch shift. In this case, since the irradiation point is different for each cross section, it is possible to prevent a warp generated when forming the modeled object. In addition,
In the above-described embodiment, the galvanometer mirror is used as a device for controlling the position where the laser beam is irradiated. However, the present invention is not limited to this, and the present method is also effective for an optical shaping apparatus using an XY plotter. is there.

[0042]

As described above in detail, in the optical shaping method according to the present invention, since the light is not scanned while the light is being irradiated, the amount of light energy applied to the photocurable liquid is controlled. For this purpose, it is only necessary to control the light intensity and irradiation time of the irradiation light, and the amount of irradiation energy can be made uniform.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical shaping apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control device of the optical shaping apparatus shown in FIG.

FIG. 3 is a drawing showing a relationship between an irradiation point and a pitch between irradiation points.

FIG. 4 is a drawing for explaining a procedure when determining an irradiation point.

FIG. 5 is a diagram illustrating a state in which laser light is incident on and reflected by a galvanometer mirror.

FIG. 6 is a drawing showing a relationship between an incident angle of a galvanometer mirror and reflection efficiency.

FIG. 7 is a drawing for explaining a cured shape in a case where a cross section is formed by an optical shaping method according to an embodiment of the present invention, and when a laser focus diameter is changed between an outer peripheral region and an inner region. is there.

FIG. 8 is a flowchart showing a procedure for forming each section by the optical shaping method according to one embodiment of the present invention.

FIG. 9 is a drawing for explaining the operation of each device when forming each cross section in the optical shaping method according to one embodiment of the present invention.

FIG. 10 shows a stereolithography method according to an embodiment of the present invention,
4 is a diagram illustrating a relationship between light energy applied to a photocurable liquid and a cured shape.

FIG. 11 is a drawing for explaining the principle of the optical shaping apparatus.

FIG. 12 is a drawing showing the relationship between the moving speed of laser light and the curing depth at each point when scanning with laser light by a conventional optical shaping method.

FIG. 13 is a diagram for explaining a response delay existing in a device.

[Explanation of symbols]

 2. Laser oscillator 4. AOM (acoustic optical modulator) 6. Focus lens 8, 10, Galvanometer mirror 12, fθ lens 14, Vessel 15, Table 16, Controller 18. · Photodetector 30 · · · Data processing unit 31 · · · Control unit 32 · · · 3D modeling data storage means 34 · · · Irradiation point determination means 35 · · · Reflection efficiency determination means 36 · · · Irradiation time determination means 37 · · · Table position control Section 38 galvanometer mirror control section 39 focus lens control section 40 AOM control section

Claims (8)

[Claims] 1. A method of forming at least a partial region of at least one cross section of a cross-sectional group obtained by slicing a desired shape into a plurality of layers, wherein the region is hardened based on shape data of the region. A step of determining one or a plurality of irradiation points to be irradiated with light; and an optical device disposed between the light source and the photocurable liquid so that light from the light source is irradiated to one of the irradiation points. And adjusting the optical device, after the optical device is adjusted, has an irradiation step of irradiating one of the irradiation points with light, the adjustment step and the irradiation step to all of the irradiation points The stereolithography method in which the region is formed by repeating the above. 2. The stereolithography method according to claim 1, wherein a step of determining the irradiation point is performed for an outer peripheral region of a cross section to be formed, and the irradiation step obtained in the step is adjusted and the irradiation step is performed. A stereolithography method in which the molding is performed by repeating the process, and the inner region of the cross section to be molded is formed by scanning light from a light source on a photocurable liquid surface. 3. The stereolithography method according to claim 1, wherein the time for irradiating the photocurable liquid with light in the irradiating step is determined based on a measured light intensity of light irradiated from a light source and based on the value. Stereolithography method. 4. A light irradiated with light from a light source based on shape data of a whole or a specified region in one cross section of a cross section group obtained by slicing a desired shape into a plurality of layers. Irradiating point determining means for determining one or more irradiating points on the curable liquid surface, disposed between the light source and the photocurable liquid, and the irradiating point is irradiated with light emitted from the light source. Position control means for controlling the irradiation position of light as described above, and light energy disposed between the light source and the photocurable liquid, for controlling the light intensity and / or irradiation time of the light irradiated to the irradiation point An optical shaping apparatus including a control unit. 5. An optical shaping apparatus according to claim 4, wherein a light detector for measuring light intensity of light emitted from the light source is arranged between the light source and the photocurable liquid. An optical shaping apparatus for controlling the light intensity and / or irradiation time of light applied to the irradiation point, based on a value detected by a light detector. 6. An optical shaping apparatus according to claim 4, wherein said irradiation position control means is a deflecting mirror, and from the coordinates of each irradiation point determined by said irradiation point determination means,
It is provided with reflection efficiency calculation means for calculating the reflection efficiency of the deflection mirror from the angle of incidence of light on the deflection mirror when irradiating each irradiation point, taking into account the reflection efficiency obtained by the reflection efficiency calculation means,
The optical shaping apparatus wherein the light energy control means controls light intensity and / or irradiation time of light applied to each irradiation point. 7. A moving step of moving an irradiation point of light without irradiating the photocurable liquid with light, and an irradiation step of fixing the irradiation point of light and irradiating the photocurable liquid with light. An optical shaping method comprising: repeating the moving step and the irradiating step, and shaping an area to be hardened with a beam spot formed by irradiated light. 8. A moving means for moving an irradiation point of light without irradiating the photocurable liquid with light, and an irradiation means for fixing the irradiation point of light and irradiating the photocurable liquid with light. An optical shaping device that has a beam spot created by irradiating light and shapes an area to be cured by filling the area.