阅读说明：本技术 光学成形装置及成形方法 (Optical molding apparatus and molding method ) 是由 沟口亲明 于 2020-11-02 设计创作，主要内容包括：本申请涉及光学成形装置及成形方法。一种光学成形装置,包括：光源,其发射用于使液态光固化性树脂进行固化的光；以及光调制器,其将用于使液态光固化性树脂进行固化的光调制为基于三维物体的形状的图案,并用调制后的光照射液态光固化性树脂。光调制器包括：液晶装置,其将用于使液态光固化性树脂进行固化的光调制为所述图案,并发射调制后的光作为线性偏振光；以及光延迟装置,其对从液晶装置发射的线性偏振光赋予相位差,并发射赋予了相位差的光。(The present application relates to an optical molding apparatus and a molding method. An optical shaping device, comprising: a light source that emits light for curing the liquid photocurable resin; and an optical modulator that modulates light for curing the liquid photocurable resin into a pattern based on a shape of the three-dimensional object, and irradiates the liquid photocurable resin with the modulated light. The optical modulator includes: a liquid crystal device that modulates light for curing the liquid photocurable resin into the pattern and emits the modulated light as linearly polarized light; and an optical retardation device that gives a phase difference to the linearly polarized light emitted from the liquid crystal device and emits light to which the phase difference is given.)

1. An optical shaping device, comprising:

a light source that emits light for curing a liquid photocurable resin; and

an optical modulator that modulates light for curing the liquid photocurable resin into a pattern based on a shape of a three-dimensional object and irradiates the liquid photocurable resin with the modulated light,

wherein the optical modulator comprises:

a liquid crystal device that modulates light for curing the liquid photocurable resin into the pattern and emits the modulated light as linearly polarized light; and

an optical retardation device that gives a phase difference to the linearly polarized light emitted from the liquid crystal device and emits light to which the phase difference is given.

2. The optical forming apparatus according to claim 1, wherein the light modulator irradiates the liquid photocurable resin with circularly polarized light or elliptically polarized light.

3. Optical shaping device according to claim 1 or 2, wherein the optical retarding means impart to the light emitted by the light source a phase difference of one quarter of the wavelength having the maximum intensity at the wavelength having the maximum intensity.

4. The optical shaping device of any one of claims 1-3, further comprising:

a resin tank having a bottom portion through which light for curing the liquid photocurable resin can pass, the resin tank holding the liquid photocurable resin,

wherein the light modulator irradiates the liquid photocurable resin with the modulated light via the bottom of the resin tank.

5. A method of forming comprising the steps of:

imparting a phase difference to linearly polarized light emitted from a liquid crystal device for modulating light from a light source, and irradiating a liquid photocurable resin with the light to which the phase difference is imparted, thereby curing the liquid photocurable resin; and

the cured photocurable resin is moved in the emission direction of the light to which the phase difference is imparted.

Technical Field

The present application relates to an optical molding apparatus and a molding method.

Background

A technique of forming a three-dimensional object by irradiating a light-curable resin with light based on a cross-sectional shape of the three-dimensional object is known. For example, unexamined japanese patent application publication No. h7-232383 discloses a method of forming a three-dimensional object by selectively irradiating a photocurable resin with light using a liquid crystal shutter.

In the forming method of japanese unexamined patent application publication No. h7-232383, after a single layer of a photocurable resin is cured by selectively irradiating the photocurable resin with light using a liquid crystal shutter, the cured photocurable resin is moved in a direction away from the liquid crystal shutter. Then, the next layer of the photocurable resin is cured by selectively irradiating the photocurable resin that has been ejected onto the cured photocurable resin with light using a liquid crystal shutter. The forming method of unexamined japanese patent application publication No. h7-232383 forms a three-dimensional object by repeating these steps.

In general, a liquid crystal shutter emits linearly polarized light. However, when the vibration direction (polarization direction) of the incident linearly polarized light is parallel to the transition moment of the polymerization initiator, the polymerization initiator contained in the photocurable resin most effectively absorbs the linearly polarized light, thereby starting the polymerization of the monomer, oligomer, and the like contained in the photocurable resin. Therefore, in the molding method of unexamined japanese patent application publication No. h7-232383, unevenness may occur in the density of the cured photocurable resin according to the relationship between the vibration direction of the linearly polarized light emitted from the liquid crystal shutter and the direction of inflow of the photocurable resin after the cured photocurable resin is moved. The unevenness in density of the cured photocurable resin may cause warpage, cracking, and the like of the three-dimensional object. In addition, in the molding method of unexamined japanese patent application publication No. h7-232383, since the light-curable resin is irradiated with linearly polarized light, the light use efficiency is lowered.

In view of the above, it is an object of the present invention to provide an optical molding apparatus and a molding method capable of preventing or suppressing density unevenness of a cured photocurable resin. It is still another object of the present invention to provide an optical molding apparatus and a molding method having high light use efficiency.

Disclosure of Invention

In order to achieve the above object, an optical shaping device of a first aspect of the present invention includes:

a light source that emits light for curing a liquid photocurable resin;

an optical modulator that modulates light for curing the liquid photocurable resin into a pattern based on a shape of the three-dimensional object and irradiates the liquid photocurable resin with the modulated light,

wherein the optical modulator comprises:

a liquid crystal device that modulates light for curing a liquid photocurable resin into the pattern and emits the modulated light as linearly polarized light; and

and an optical retardation device that gives a phase difference to the linearly polarized light emitted from the liquid crystal device and emits light given the phase difference.

A forming method according to a second aspect of the present invention includes the steps of:

imparting a phase difference to linearly polarized light emitted from a liquid crystal device for modulating light from a light source, and irradiating a liquid photocurable resin with the light to which the phase difference is imparted, thereby curing the liquid photocurable resin; and

the cured photocurable resin is moved in the emission direction of the light that imparts the phase difference.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

According to the present invention, since a phase difference is given to linearly polarized light emitted from the liquid crystal device, it is possible to prevent or suppress density unevenness of a cured photocurable resin. In addition, since a phase difference is given to linearly polarized light emitted from the liquid crystal device, high light use efficiency can be achieved.

Drawings

A more complete understanding of the present application may be derived when the following detailed description is considered in conjunction with the following figures, wherein:

fig. 1 is a diagram showing a structure of an optical molding apparatus according to embodiment 1;

fig. 2 is a schematic view showing an optical molding apparatus according to embodiment 1;

fig. 3 is a schematic view showing a state of light according to embodiment 1;

fig. 4 is a flowchart showing a method of forming a three-dimensional object according to embodiment 1;

fig. 5 is a schematic view showing an optical molding apparatus according to embodiment 2; and

fig. 6 is a schematic view showing a resin tank according to a modification.

Detailed Description

An optical shaping device according to various embodiments is described below with reference to the accompanying drawings.

Embodiment mode 1

An optical shaping device 100 according to the present embodiment is described with reference to fig. 1 to 4. The optical molding apparatus 100 forms the three-dimensional object Ob from the liquid photocurable resin RL.

As shown in fig. 1 and 2, the optical molding apparatus 100 includes a resin tank 10, a molding plate 20, a moving unit 30, a light source 40, an optical modulator 50, and a controller 60, all of which are housed in a housing 5 of the optical molding apparatus 100. The resin tank 10 holds a liquid photocurable resin RL. The three-dimensional object Ob is formed on the surface 20a of the forming plate 20. The moving section 30 moves the forming plate 20. The light source 40 emits light for curing the liquid photocurable resin RL. The light modulator 50 modulates light for curing the liquid photocurable resin RL into a pattern based on the shape of the three-dimensional object Ob. The light modulator 50 comprises a liquid crystal device 52 and an optical retardation device 54. The controller 60 controls each component of the optical forming device 100.

In the present invention, for ease of understanding, the longitudinal rightward direction (direction toward the right side of fig. 2) of the optical forming device 100 in fig. 2 is defined as the + X direction, the upward direction (direction toward the top of fig. 2) is defined as the + Z direction, and the direction perpendicular to the + X direction and the + Z direction (direction toward the front of fig. 2) is defined as the + Y direction.

As shown in fig. 2, the resin tank 10 of the optical molding apparatus 100 holds a liquid photocurable resin RL. The resin tank 10 is a box-shaped container having an opening on the + Z-side surface of the resin tank 10. The resin tank 10 includes a bottom 12 and a wall 14.

The bottom portion 12 of the resin tank 10 passes therethrough the light emitted from the light source 40 for curing the liquid photocurable resin RL. In addition, the bottom portion 12 is capable of passing therethrough a gas that inhibits curing of the liquid photocurable resin RL, more specifically, a gas (for example, oxygen) that inhibits polymerization of monomers, oligomers, and the like contained in the liquid photocurable resin RL. The base 12 is formed of a porous membrane that allows oxygen to permeate therethrough. The porous membrane includes Polytetrafluoroethylene (PTFE), Polyethylene (PE), and the like. The wall portion 14 blocks light to cure the liquid photocurable resin RL. The wall portion 14 is formed of resin, metal, or the like.

Here, the liquid photocurable resin RL is described. The liquid photocurable resin RL is a liquid resin cured by irradiation with light of a predetermined wavelength. In the present embodiment, the liquid photocurable resin RL is cured by being irradiated with light emitted from the light source 40. The liquid photocurable resin RL includes monomers, oligomers, polymerization initiators, and the like. The polymerization initiator absorbs light emitted from the light source 40 to generate active species such as radicals, ions, etc., thereby starting polymerization of monomers, oligomers, etc. In the present embodiment, the liquid photocurable resin RL is a liquid Ultraviolet (UV) curable resin.

The forming plate 20 of the optical forming device 100 is a flat plate made of resin or made of metal. As shown in fig. 2, the forming plate 20 is disposed on the + Z side with respect to the bottom 12 of the resin tank 10. In the initial state of the optical molding apparatus 100, the molding plate 20 is located inside the resin tank 10 (initial position of the molding plate 20). The forming plate 20 is moved in the + Z direction and the-Z direction by the moving section 30. The forming plate 20 forms a three-dimensional object Ob on a surface 20a facing the bottom 12 of the resin tank 10.

The moving unit 30 of the optical molding apparatus 100 moves the molding plate 20 in the + Z direction and the-Z direction. The moving section 30 includes an arm 32 and a moving mechanism 34. The arm 32 of the moving part 30 is connected to the shaping plate 20 and the moving mechanism 34. The moving mechanism 34 of the moving section 30 moves the forming plate 20 in the + Z direction and the-Z direction via the arm 32. The moving mechanism 34 is equipped with a motor, a ball screw, a slider, and the like (not shown).

The light source 40 of the optical molding apparatus 100 emits light for curing the liquid photocurable resin RL (+ Z direction) toward the liquid photocurable resin RL (+ Z direction). In the present embodiment, the light source 40 is disposed on the-Z side with respect to the resin tank 10. As shown in fig. 3, the light source 40 emits unpolarized UV light L1 in the + Z direction from the upper surface 40a on the resin tank 10 side. The light source 40 is equipped with a reflective sheet, a Light Emitting Diode (LED) emitting UV light, a diffusion sheet, and the like. The wavelength having the maximum intensity in the unpolarized UV light L1 emitted from the light source 40 is, for example, 405 nm.

As shown in fig. 2, the optical modulator 50 of the optical molding apparatus 100 is disposed between the resin tank 10 and the light source 40. The light modulator 50 modulates light emitted from the light source 40 for curing the liquid photocurable resin RL into a pattern based on the shape of the three-dimensional object Ob, and irradiates the liquid photocurable resin RL with the modulated light. In the present embodiment, as shown in fig. 3, the light modulator 50 irradiates the liquid photocurable resin RL with light for curing the liquid photocurable resin RL in a circularly polarized state or an elliptically polarized state via the bottom portion 12 of the resin tank 10. As shown in fig. 1 and 2, the light modulator 50 includes a liquid crystal device 52 and a light retarding device 54.

The liquid crystal device 52 of the light modulator 50 modulates light emitted from the light source 40 for curing the liquid photocurable resin RL based on the shape of the three-dimensional object Ob. As shown in fig. 3, the liquid crystal device 52 emits the modulated light L2 as linearly polarized light. The liquid crystal device 52 is an active matrix driven Twisted Nematic (TN) type liquid crystal device and has a plurality of liquid crystal cells. The liquid crystal cells are arranged in a matrix. The liquid crystal cell blocks or passes light for curing the liquid photocurable resin RL.

Specifically, the liquid crystal device 52 modulates light for curing the liquid photocurable resin RL into a pattern corresponding to the cross-sectional shape of the three-dimensional object Ob based on cross-sectional shape data indicating the shape of the cross-section of the three-dimensional object Ob perpendicular to the + Z direction. The liquid crystal device 52 emits light for curing the liquid photocurable resin RL as linearly polarized light in a pattern corresponding to the cross-sectional shape of the three-dimensional object Ob.

The optical retardation device 54 of the optical modulator 50 imparts a phase difference to the linearly polarized light emitted from the liquid crystal device 52. As shown in fig. 3, the optical retardation device 54 also irradiates the liquid photocurable resin RL with the light L3 to which a phase difference is given. Since the optical retardation device 54 gives a phase difference to the linearly polarized light, the vibration direction of the light with which the liquid photocurable resin RL is to be irradiated is rotated with respect to the flow direction of the liquid photocurable resin RL. Therefore, the optical molding apparatus 100 can cure the liquid photocurable resin RL without depending on the flow direction of the liquid photocurable resin RL, and thus can prevent or suppress the density unevenness of the cured photocurable resin RS. The optical molding apparatus 100 can also achieve high light utilization efficiency independent of the direction of the transition moment of the polymerization initiator. Further, since interference of light for curing the liquid photocurable resin RL can be prevented or suppressed at the bottom portion 12 formed of a film, the optical forming apparatus 100 can uniformly irradiate the liquid photocurable resin RL with light for curing the liquid photocurable resin RL.

In the present embodiment, the light retardation device 54 is a quarter-wave plate that imparts a quarter-wavelength phase difference, and thus the liquid photocurable resin RL is irradiated with circularly polarized light or elliptically polarized light. For example, at the wavelength (405nm) of the light emitted by the light source 40 having the maximum intensity, the optical retardation device 54 imparts a phase difference of one quarter of the wavelength having the maximum intensity to the light.

The controller 60 of the optical molding apparatus 100 controls the moving unit 30, the light source 40, and the light modulator 50. The controller 60 also generates cross-sectional shape data representing the shape of a cross section of the three-dimensional object Ob perpendicular to the + Z direction based on the three-dimensional shape data representing the three-dimensional shape of the three-dimensional object Ob. Cross-sectional shape data indicating the shape of a cross section perpendicular to the + Z direction is generated at predetermined intervals in the + Z direction.

As shown in fig. 1, the controller 60 includes: a Central Processing Unit (CPU)62 for executing various types of processing; a Read Only Memory (ROM)64 for storing programs and data in advance; a Random Access Memory (RAM)66 for storing data; and an input-output interface 68 for inputting and outputting signals between the components. The functions of the controller 60 are realized by the CPU 62 executing programs stored in the ROM 64. The input/output interface 68 inputs and outputs signals among the CPU 62, the moving unit 30, the light source 40, the optical modulator 50, and an external device not shown.

Next, a forming method of the three-dimensional object Ob is described with reference to fig. 4. In the present embodiment, the three-dimensional object Ob is formed by stacking layers of the cured photocurable resin RS at predetermined intervals by the optical molding apparatus 100.

Fig. 4 is a flowchart of a method of forming a three-dimensional object Ob. The method for forming the three-dimensional object Ob includes: a step of preparing a liquid photocurable resin RL and sectional shape data (step S10); a step of setting the forming board 20 at an initial position (step S20); a step of curing the liquid photocurable resin RL by: (i) imparting a phase difference to linearly polarized light emitted from a liquid crystal device 52 that modulates light from the light source 40, and then (ii) irradiating the liquid photocurable resin RL with the light L3 imparted with a phase difference (step S30); and a step of moving the cured photocurable resin RS in the emission direction of the light L3 to which the phase difference is given (step S40). In the present embodiment, steps S30 and S40 are repeated a number of times equal to the number of layers of the cured photocurable resin RS.

In step S10, a liquid photocurable resin RL for forming the three-dimensional object Ob and cross-sectional shape data indicating the shape of a cross section of the three-dimensional object Ob perpendicular to the + Z direction are prepared. In the present embodiment, the liquid photocurable resin RL is a liquid UV curable resin. The liquid photocurable resin RL is stored in the resin tank 10 of the optical molding apparatus 100. The sectional shape data is generated by the controller 60 of the optical shaping apparatus 100 at predetermined intervals in the + Z direction based on three-dimensional shape data representing the three-dimensional shape of the three-dimensional object Ob input from an external apparatus. The three-dimensional data is, for example, a three-dimensional Computer Aided Design (CAD) of the three-dimensional object Ob.

In step S20, the forming plate 20 is moved by the moving unit 30. In this way, the forming plate 20 is set at the initial position. Specifically, the forming plate 20 is provided in the following positions within the liquid photocurable resin RL: (i) the interval between the surface 20a on which the three-dimensional object Ob is formed and (ii) the bottom 12 of the resin tank 10 is the thickness of a single layer of the cured photocurable resin RS (predetermined interval).

In step S30, UV light is emitted from the light source 40. The emitted UV light is modulated by the liquid crystal device 52 based on the cross-sectional shape data of the first layer, so that the modulated UV light is emitted from the liquid crystal device 52 as linearly polarized light. Then, the optical retardation device 54 gives a phase difference to the linearly polarized light emitted from the liquid crystal device 52. The light retardation device 54 irradiates the liquid photocurable resin RL with the light L3 given a phase difference through the bottom portion 12 of the resin tank 10. In this manner, the liquid photocurable resin RL is cured, thereby forming a cured photocurable resin RS of the first layer.

In the present embodiment, since the optical retardation device 54 gives a phase difference to linearly polarized light, the vibration direction of light to be emitted onto the liquid photocurable resin RL is rotated with respect to the flow direction of the liquid photocurable resin RL. Therefore, in the molding method of the present embodiment, the liquid photocurable resin RL is cured without depending on the flow of the liquid photocurable resin RL caused by the movement of the molding plate 20 to the initial position, and thus the density unevenness of the cured photocurable resin RS can be prevented or suppressed. The molding method of the present embodiment can also achieve high light use efficiency without depending on the direction of the transition moment of the polymerization initiator.

Further, since the bottom portion 12 of the resin tank 10 in the present embodiment is formed of a porous film that is capable of allowing oxygen to permeate therethrough, a liquid photocurable resin RL layer (polymerization-inhibited liquid photocurable resin RL layer) is formed between the cured photocurable resin RS and the bottom portion 12. Therefore, the cured photocurable resin RS can be prevented from coming into close contact with the bottom portion 12.

In step S40, the cured photocurable resin RS (forming plate 20) is moved by the moving section 30 in the emission direction (+ Z direction) of the light L3 to which the phase difference is given, by a distance equal to the thickness of the cured photocurable resin RS. In this manner, the liquid photocurable resin RL flows between the cured photocurable resin RS and the bottom 12 of the resin tank 10.

Next, returning to step S30, the UV light emitted from the light source 40 is modulated by the liquid crystal device 52 based on the cross-sectional shape data of the second layer, so that the modulated UV light is emitted from the liquid crystal device 52 as linearly polarized light. Then, the optical retardation device 54 gives a phase difference to the linearly polarized light emitted from the liquid crystal device 52. The optical retardation device 54 irradiates the liquid photocurable resin RL with the light L3 given a phase difference. In this manner, the cured photocurable resin RS of the second layer is formed. In a manner similar to the previous repetition of step S30, the vibration direction of the light with which the liquid photocurable resin RL is to be irradiated is rotated with respect to the flow direction of the liquid photocurable resin RL. Therefore, the method of the present embodiment can prevent or suppress the density unevenness of the cured photocurable resin RS by curing the liquid photocurable resin RL without depending on the flow of the liquid photocurable resin RL caused by the movement of the forming plate 20 in step S40. The molding method of the present embodiment can also achieve high light use efficiency.

In the present embodiment, step S30 and step S40 are alternately executed. Once both the step S30 and the step S40 are repeated the number of times equal to the number of layers of the cured photocurable resin RS of the three-dimensional object Ob, the formation of the three-dimensional object Ob is completed. Through this process, the optical shaping apparatus 100 can shape the three-dimensional object Ob.

As described above, since the optical molding apparatus 100 irradiates the liquid photocurable resin RL with light whose oscillation direction rotates with respect to the flow direction of the liquid photocurable resin RL, the liquid photocurable resin RL can be cured without depending on the flow direction of the liquid photocurable resin RL, and thus, unevenness in the density of the cured photocurable resin RS can be prevented or suppressed. The optical molding apparatus 100 can also achieve high light use efficiency without depending on the direction of the transition moment of the polymerization initiator.

Further, the method of molding the three-dimensional object Ob of the present embodiment enables the production of the three-dimensional object Ob in which the density unevenness of the cured photocurable resin RS is prevented or suppressed.

Embodiment mode 2

The optical molding apparatus 100 according to embodiment 1 irradiates the liquid photocurable resin RL with light for curing the liquid photocurable resin through the bottom 12 of the resin tank 10. The liquid photocurable resin RL may be irradiated with light for curing the liquid photocurable resin RL from the opening 16 of the resin tank 10.

An optical shaping device 100 of the present invention is described with reference to fig. 5. The optical molding apparatus 100 of the present invention includes a resin tank 10, a molding plate 20, a moving section 30, a light source 40, an optical modulator 50, and a controller 60, similarly to the optical molding apparatus 100 of embodiment 1.

The resin tank 10 of the present embodiment holds the liquid photocurable resin RL, similarly to the resin tank 10 of embodiment 1. The resin tank 10 of the present embodiment is a box-shaped container having an opening 16 on the + Z-side surface of the resin tank 10. In the present embodiment, the liquid photocurable resin RL is irradiated with light for curing the liquid photocurable resin RL from the opening 16. The bottom portion 12 and the wall portion 14 of the resin tank 10 of the present embodiment are integrally formed of a resin, a metal, or the like that blocks light to cure the liquid photocurable resin RL. Similarly to embodiment 1, the liquid photocurable resin RL of the present embodiment is a liquid UV curable resin.

The formed plate 20 of the present embodiment is a flat plate made of resin or made of metal, similarly to the formed plate 20 of embodiment 1. The forming plate 20 of the present embodiment is located inside the resin tank 10. The forming plate 20 of the present embodiment is moved in the + Z direction and the-Z direction by the moving section 30. As shown in fig. 5, the forming plate 20 of the present invention forms a three-dimensional object Ob on a surface 20b opposite to the bottom 12 of the resin tank 10.

The moving section 30 of the present embodiment moves the forming plate 20 in the + Z direction and the-Z direction, similarly to the moving section 30 of embodiment 1. The moving unit 30 of the present embodiment has the same configuration as the moving unit 30 of embodiment 1.

The light source 40 of the present embodiment emits light for curing the liquid photocurable resin RL (-Z direction) to the liquid photocurable resin RL. In the present embodiment, the light source 40 is provided on the + Z side with respect to the resin tank 10. The light source 40 emits unpolarized UV light L1 in the-Z direction from the lower surface 40b on the side of the resin tank 10. Other features of the light source 40 of the present embodiment are the same as those of the light source 40 of embodiment 1.

The optical modulator 50 of the present embodiment is disposed between the resin tank 10 and the light source 40, similarly to the optical modulator 50 of embodiment 1. The features of the optical modulator 50 of the present embodiment are the same as those of the optical modulator 50 of embodiment 1, except that the liquid photocurable resin RL is irradiated with the light L3 with a phase difference applied thereto from the opening 16 of the resin tank 10. In the present embodiment, the vibration direction of the light with which the liquid photocurable resin RL is to be irradiated is also rotated with respect to the direction in which the liquid photocurable resin RL flows. Therefore, the optical molding apparatus 100 can cure the liquid photocurable resin RL without depending on the flow direction of the liquid photocurable resin RL, and thus can prevent or suppress the density unevenness of the cured photocurable resin RS. The optical molding apparatus 100 according to embodiment 1 can also achieve high light utilization efficiency without depending on the direction of the transition moment of the polymerization initiator.

The controller 60 of the present embodiment controls the moving section 30, the light source 40, and the light modulator 50, similarly to the controller 60 of embodiment 1. The controller 60 of the present embodiment generates cross-sectional shape data indicating the shape of a cross section perpendicular to the + Z direction of the three-dimensional object Ob based on three-dimensional shape data indicating the three-dimensional shape of the three-dimensional object Ob. The features of the controller 60 of the present embodiment are the same as those of the controller 60 of embodiment 1, except for the feature of generating the cross-sectional data at predetermined intervals in the-Z direction.

A forming method of the three-dimensional object Ob of the present embodiment is described with reference to fig. 4. Similar to the forming method of embodiment 1, the forming method of the three-dimensional object Ob includes: a step of preparing a liquid photocurable resin RL and sectional shape data (step S10); a step of setting the forming board 20 at an initial position (step S20); a step of curing the liquid photocurable resin RL by: (i) imparting a phase difference to linearly polarized light emitted from the liquid crystal device 52 for modulating light from the light source 40, and then (ii) irradiating the liquid photocurable resin RL with light L3 imparted with a phase difference (step S30); and a step of moving the cured photocurable resin RS in the emission direction of the light L3 to which the phase difference is given (step S40). Steps S30 and S40 are repeated a number of times equal to the number of layers of the cured photocurable resin RS.

In step S10, similarly to step S10 of embodiment 1, a liquid photocurable resin RL for forming the three-dimensional object Ob and cross-sectional shape data representing the shape of a cross section of the three-dimensional object Ob perpendicular to the + Z direction are prepared. In the present embodiment, the cross-sectional shape data is generated by the controller 60 of the optical shaping apparatus 100 at predetermined intervals in the-Z direction based on three-dimensional shape data representing the three-dimensional shape of the three-dimensional object Ob input from an external apparatus. Otherwise, this step is the same as step S10 of embodiment 1.

In step S20, the forming plate 20 is set at the initial position by the moving section 30, similarly to step S20 in embodiment 1. Specifically, the forming plate 20 is provided in the following positions within the liquid photocurable resin RL: (i) the interval between the surface 20b on which the three-dimensional object Ob is formed and (ii) the liquid surface of the liquid photocurable resin RL is the thickness of a single layer of the cured photocurable resin RS.

In step S30, UV light is emitted from the light source 40. The emitted UV light is modulated by the liquid crystal device 52 based on the cross-sectional shape data of the first layer, so that the modulated UV light is emitted from the liquid crystal device 52 as linearly polarized light. Then, the optical retardation device 54 gives a phase difference to the linearly polarized light emitted from the liquid crystal device 52. The optical delay device 54 irradiates the liquid photocurable resin RL from the opening 16 of the resin tank 10 with the light L3 to which a phase difference is applied. In this manner, the cured photocurable resin RS of the first layer is formed. Similarly to step S30 of embodiment 1, the vibration direction of the light with which the liquid photocurable resin RL is to be irradiated is rotated with respect to the flow direction of the liquid photocurable resin RL. Therefore, the molding method of the present embodiment can cure the liquid photocurable resin RL without depending on the direction of the flow of the liquid photocurable resin RL caused by the movement of the molding plate 20 to the initial position, and thus can prevent or suppress the density unevenness of the cured photocurable resin RS. The molding method of the present embodiment can also achieve high light use efficiency.

In step S40, the cured photocurable resin RS (forming plate 20) is moved by the moving section 30 in the emission direction (-Z direction) of the light L3 that imparts the phase difference by a distance equal to the thickness of the cured photocurable resin RS. In this manner, the liquid photocurable resin RL flows onto the cured photocurable resin RS.

Returning to step S30, similarly to embodiment 1, the photocurable resin RS of the second layer is formed based on the cross-sectional shape data of the second layer. In this step, the vibration direction of the light with which the liquid photocurable resin RL is to be irradiated is also rotated with respect to the flow direction of the liquid photocurable resin RL. Therefore, the molding method of the present embodiment can cure the liquid photocurable resin RL without depending on the direction of the flow of the liquid photocurable resin RL caused by the movement of the molding plate 20 in step S40, and thus can prevent or suppress the density unevenness of the cured photocurable resin RS. The molding method of the present embodiment can also achieve high light use efficiency.

In the present embodiment, step S30 and step S40 are also alternately executed. Once both the step S30 and the step S40 are repeated the number of times equal to the number of layers of the cured photocurable resin RS of the three-dimensional object Ob, the formation of the three-dimensional object Ob is completed. Through this process, the optical shaping apparatus 100 can form the three-dimensional object Ob.

As described above, the optical molding apparatus 100 of the present embodiment can cure the liquid photocurable resin RL without depending on the flow direction of the liquid photocurable resin RL, and therefore, can prevent or suppress the density unevenness of the cured photocurable resin RS. The optical molding apparatus 100 of the present embodiment can also achieve high light use efficiency regardless of the direction of the transition moment of the polymerization initiator. Further, the method of molding the three-dimensional object Ob of the present embodiment enables the production of the three-dimensional object Ob in which the density unevenness of the cured photocurable resin RS is prevented or suppressed.

Modification examples

The above-described embodiments may be modified in various ways without departing from the gist of the present invention.

For example, the bottom 12 of the resin tank 10 of embodiment 1 is formed of a porous film. The bottom portion 12 of the resin tank 10 of embodiment 1 may be formed of glass, resin, or the like that allows light for curing the liquid photocurable resin RL to pass therethrough. The bottom portion 12 formed of glass, resin, or the like may be subjected to a peeling treatment (e.g., a silicone coating treatment). In this manner, the bottom portion 12 and the cured photocurable resin RS can be prevented from being in close contact with each other.

Further, as shown in fig. 6, the bottom portion 12 of the resin tank 10 of embodiment 1 may include a transmission portion 18. In this case, the bottom portion 12 and the wall portion 14 are integrally formed of metal, resin, or the like that blocks light to cure the liquid photocurable resin RL. The transmission portion 18 is formed of a member that allows light for curing the liquid photocurable resin RL to pass therethrough. The liquid photocurable resin RL is irradiated with the light L3 with the phase difference imparted thereto through the transmission portion 18.

The liquid photocurable resin RL is not limited to the liquid UV curable resin. The liquid photocurable resin RL may be, for example, a liquid resin cured by irradiation with visible light. Further, the liquid photocurable resin RL may include a polymerization inhibitor, metal nanoparticles, a pigment, and the like.

The light emitted from the light source 40 is not limited to UV light. The light source 40 emits light for curing the liquid photocurable resin RL. The light source 40 can emit visible light in accordance with the wavelength at which the polymerization initiator contained in the liquid photocurable resin RL generates an active substance.

Alternatively, the light source 40 may be equipped with a lamp instead of an LED. Further, from the viewpoint of improving the forming accuracy, the light source 40 is preferably equipped with a collimator that collimates emitted light for curing the liquid photocurable resin RL to produce collimated light.

The liquid crystal device 52 is not limited to a TN-type liquid crystal device. The liquid crystal device 52 may be a Vertical Alignment (VA) type liquid crystal device, a Fringe Field Switching (FFS) type liquid crystal device, or the like. The liquid crystal device 52 may modulate the amount of light for curing the liquid photocurable resin RL that passes therethrough, in addition to passing therethrough light for curing the liquid photocurable resin RL or blocking the passage of such light therethrough.

Preferably, the optical retarding device 54 is in intimate contact with the liquid crystal device 52. For example, it is sufficient if (i) the optical retardation device 54 is stacked on the light polarizing layer on the emission side of the liquid crystal device 52, and (ii) the optical retardation device 54 and the liquid crystal device 52 are integrally formed. Thus, the light use efficiency can be improved. Also, the light emitted from the liquid crystal device 52 can be suppressed or prevented from being diffused. From the viewpoint of more uniform intensity of the light with which the liquid photocurable resin RL is irradiated, the range of variation of the phase difference imparted by the light retardation device 54 at the wavelength of the light emitted by the light source 45 having the maximum intensity is preferably less than or equal to plus 10% or minus 10% of one-fourth of the wavelength having the maximum intensity.

Further, it is preferable that the optical delay device 54 of the optical forming device 100 of embodiment 1 is in close contact with the bottom 12 of the resin tank 10.

In embodiments 1 and 2, the optical molding apparatus 100 forms the three-dimensional object Ob by sequentially stacking a plurality of layers of the cured photocurable resin RS. The optical molding apparatus 100 can continuously form the three-dimensional object Ob by continuously irradiating the liquid photocurable resin RL with light for curing the liquid photocurable resin RL while continuously moving the molding plate 20.

The foregoing description of certain exemplary embodiments has been presented for purposes of illustration. Although the foregoing discussion has given particular embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

The present application claims priority from japanese patent application No.2019-201028, filed on 5.11.2019, the entire disclosure of which is incorporated herein by reference.