JPH08112863A - Optical formation device - Google Patents

Abstract

PURPOSE: To reduce the size of a device, form an aimed large-sized, three- dimensional model with high accuracy in a short time, and eliminate the process of smoothing the liquid surface by the use of a smoothing plate. CONSTITUTION: Provided in a freely traveling relation in the traveling direction of a liquid shutter 5 is a light source unit 10 that can stop at each passage in the divided sections having a plurality of divided traveling ranges of the liquid shutter 5 capable of traveling in parallel with respect to the liquid surface of an optically curable resin 2. A linear light source 11 is housed in the inner part of the light source unit so that its longitudinal direction intersects the traveling direction of the liquid shutter substantially at right angtes, and a smoothing plate 18 is secured to be movable vertically at the front surface and rear surface in the traveling direction of the light source unit 10, and further a controller 19 is provided which serves to indicate the cross-sectional pattern of three-dimensional patterns corresponding to the divided sections, and during the period of stoppage of the liquid shutter 5 that can stop at each passage of the divided sections, the linear light source 11 passes through on the liquid shutter 5 and performs a dividing exposure operation, thus hardening the curable resin 2 optically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photolithography apparatus for irradiating a liquid photocurable resin with light to form a three-dimensional model having a desired shape.

[0002]

2. Description of the Related Art Conventionally, as a stereolithography apparatus, a surface of a liquid photo-curable resin is exposed to a laser beam in the form of a spot so that a cross-sectional pattern of a target sculpture is drawn.
By curing only the photo-curable resin located in the part exposed to the laser beam to form a thin cured resin layer, and stacking this cured resin layer continuously, it is possible to form a three-dimensional model. Those that have been made known are generally known.

However, in the case of an optical molding apparatus that employs such an exposure method using laser light, scanning with laser light is the same process as drawing a long line by one stroke, and therefore it takes a long time to form. Was needed.

Therefore, instead of the laser light, a stereolithography apparatus using parallel light, that is, a liquid crystal shutter is arranged between a light source of parallel light and a photocurable resin, and a stereoscopic image displayed on the liquid crystal shutter is displayed. Using the cross-sectional pattern of the model (objective object) as a mask pattern (exposure mask pattern),
It is widely known that the photocurable resin is cured at a high speed by collective exposure with parallel light through the mask pattern (for example, JP-A-62-288844 and JP-A-3-227222). , Actual Kaihei 2-317
26).

Further, in Japanese Patent Laid-Open No. 4-305438,
An exposure mask is formed by continuously arranging optical shutters for minute dot areas in a line, and the exposure region is scanned in the scanning direction while scanning the exposure mask integrally with a light source in a direction orthogonal to the arrangement direction of the optical shutters. It has been proposed that one layer of cured resin film be formed while being sequentially changed along with.

Here, in the stereolithography apparatus, before the liquid photocurable resin is exposed to the laser light or parallel light, the liquid surface of the photocurable resin is smoothed or the resin is laminated. For the purpose of keeping the thickness constant, for example, a step of moving a flat plate such as a squeegee on the liquid surface of the photocurable resin while contacting the liquid surface of the photocurable resin has been generalized.

[0007]

However, in the case of the conventional example using the liquid crystal shutter and parallel light, in order to perform collective exposure by parallel light, an area at least equal to the area of the flat plate-shaped liquid crystal shutter is required. It is necessary to use parallel light with uniform irradiation intensity, and as the size of the liquid crystal shutter increases, a large lens or reflector is used to obtain uniform parallel light from a light source such as a high-pressure mercury lamp. There is a problem that a long optical path length is required, and not only the light source, and hence the entire apparatus, becomes large in size, but also the loss of irradiation energy increases.

Further, when the optical shutters are arranged in a row to form an exposure mask and the exposure area is sequentially changed along the traveling direction of the exposure mask, the structure of the optical shutter is considerably complicated and the operation reliability is high. In addition to the lack of performance, there is a certain limit to the miniaturization of the dot area, and it is considered that the exposure mask cannot be configured by arranging the optical shutters in two or more rows, leading to an increase in the exposure time. To be

Further, the step of smoothing the liquid surface of the liquid photocurable resin is necessary in order to shorten the time for smoothing the liquid surface when the viscosity of the photocurable resin is high. Since it always takes a certain amount of time regardless of the exposure time,
This has been an obstacle to shortening the molding time.

The present invention has been made in view of the above problems, and has a simple structure and does not increase in size, and a large target three-dimensional model can be shaped accurately and in a shorter time. An object is to provide a stereolithography apparatus.

[0011]

In order to achieve the above object, the present invention provides, above a container containing a photocurable resin,
Liquid crystal shutters that selectively transmit or block light are arranged so that they can travel in parallel to the liquid surface of the photocurable resin, and the travel points of the liquid crystal shutters are divided into a plurality of divided points. A light source unit that can be stopped in the direction of travel of the liquid crystal shutter is arranged so that it can travel freely inside the light source unit so that the longitudinal direction above the liquid crystal shutter is substantially orthogonal to the direction of travel of the liquid crystal shutter. A smooth plate that accommodates a linear light source and is vertically movable on the front surface and the rear surface in the traveling direction of the light source unit and extends orthogonally to the traveling direction of the light source unit to smooth the surface of the photocurable resin. And a control unit for displaying a sectional pattern of a three-dimensional model corresponding to the divided section on the liquid crystal shutter, the liquid crystal shutter being stoppable at each passage point of the divided section, By further repeating a series of operations in which the linear light source passes over the liquid crystal shutter and performs divided exposure while the crystal shutter is stopped in the traveling range in one direction of the liquid crystal shutter, further curing of the photocurable resin is performed. It is characterized by performing.

[0012]

When the liquid crystal shutter in which the sectional pattern of the stereo model corresponding to the divided section is displayed is stopped, the linear light source passes over the liquid crystal shutter to perform a divided exposure. The model can be molded in a relatively short time. Further, since the smoothing plate attached to the light source unit smoothes the surface of the photocurable resin prior to the divided exposure when the light source unit is running, it is not necessary to provide a separate smoothing step, and thus the step can be omitted. As time goes by, the time can be shortened.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a container (resin tank) having a rectangular cross-section that opens upward, and inside the container 1, a liquid photocurable resin 2 that cures from a liquid to a solid when exposed to light.
Is satisfied. The photocurable resin 2 is a resin having a characteristic that a liquid undergoes a polymerization reaction by light energy to change into a solid, and for example, a photopolymerizable polymer,
It may contain a photoinitiator, an additive for improving characteristics, and the like.

On one side of the container 1, there is arranged a position-controllable elevator elevating mechanism 4 provided with a flat plate-shaped elevator 3 which is located in the container 1 and can be raised and lowered. A cured resin layer 2a obtained by curing the photocurable resin 2 is sequentially laminated.

On both sides of the container 1 facing each other,
As shown in FIG. 2, inner rails 6 are arranged in parallel with each other, and a linear movement mechanism 7 that is positionally controllable to travel by a driving device such as air pressure or a stepping motor is arranged on the inner rails 6. This moving mechanism 7 includes a container 1
A horizontal frame member 7a and a vertical frame member 7b extending downward from both ends of the horizontal frame member 7a and traveling on the rail 6. One side end of the liquid crystal shutter 5 is a liquid surface of the photocurable resin. It is held so as to be parallel to.

The liquid crystal shutter 5 may be any one as long as it can divide the cross-sectional pattern of the target stereo model into a direction orthogonal to the moving direction of the linear moving mechanism 7 and display it with a transmitting portion and a light shielding portion, for example, STN. Type liquid crystal panel, TN type liquid crystal panel, polymer dispersion type liquid crystal panel and the like can be used.

Further, outer rails 8 which are parallel to the inner rails are arranged on both sides of the inner rails 6, and a linear movement mechanism 9 which can be moved by a driving device such as air pressure or a stepping motor is positionally controllable. It is installed so that it can run freely. The moving mechanism 9 is composed of a horizontal portion 9a that straddles the container 1 and a support column 9b that extends downward from both ends of the horizontal portion 9a and travels on a rail. The horizontal portion 9a forms a light source unit 10. Inside the light source unit 10, a rectangular window portion 10 a through which the liquid crystal shutter 5 is inserted is formed.

As described above, the light source unit 10 is located above the container 1 and, so to speak, sandwiches the liquid crystal shutter 5 and is driven by the linear movement mechanism 9 to drive the light source unit 10.
However, the liquid crystal shutter 5 travels horizontally in the width direction, and the travel is not obstructed by the liquid crystal shutter 5.

In this embodiment, as the linear movement mechanism, an example of using air pressure or a stepping motor whose position and speed are relatively easy to control is shown, but an arbitrary one such as a hydraulic cylinder is used. Needless to say, the linear movement mechanism 7 needs a positioning accuracy higher than at least the pixel size of the liquid crystal shutter.

At a position above the liquid crystal shutter 5 inside the light source unit 10, a line extending in a direction orthogonal to the traveling direction of the light source unit, that is, along the length direction of the unit and extending substantially along the entire length thereof is linear. The light source 11 is arranged and housed in parallel with the liquid surface of the photocurable resin 2.

The linear light source 11 has at least 80% of the liquid crystal shutter 5 in the length direction of the linear light source 11.
It suffices that light can be emitted with the above illuminance distribution, and for example, a krypton long arc lamp, a xenon long arc lamp, a metal halide long arc lamp, a mercury long arc lamp, or the like can be used.

Above the linear light source 11, as shown in FIG. 3, the light emitted from the linear light source 11 is reflected, and the reflected light is focused on the liquid crystal shutter 5. A reflection mirror 12 is arranged, and the linear light source 11 is provided below the reflection mirror 12 and above the liquid crystal shutter 5.
A heat ray absorption filter 13 for preventing damage to the liquid crystal due to heat energy or light energy from the above, and a mechanical shutter 14 for switching between transmission and blocking of light are arranged in this order in parallel in the vertical direction. It is housed in the unit 10.

As shown in FIG. 4, the linear light source 1
The light source 1 and the heat ray absorption filter 1 are provided with a light blocking plate assembly 17 that blocks a light component having an incident angle that cannot pass through a unity-magnification imaging element 16 to be described later and adjusts the amount of light.
It may be arranged between 3 and 3.

The light-shielding plate assembly 17 is composed of a plurality of rectangular thin plates 17a, and shields angle component light larger than the aperture angle of the equal-magnification image-forming element, as shown in FIGS.
, A rectangular thin plate having a height of 1 is set upright and spaced at intervals d so that the respective surfaces of the thin plate are parallel to each other, and a slit or linear shape is formed in the length direction of the linear light source. The light sources are arranged in a lattice shape in the length direction and the width direction, and the height l and the interval d of the thin plates are adjusted to adjust the incident angle tan ⁻¹ (d / l).
The above light ray components are shielded.

The light shield assembly 17 also has a function of equalizing the amount of light in the lengthwise direction of the linear light source. A rectangular thin plate having a height of 1 is erected vertically, and the respective faces of the thin plates are parallel to each other. Are arranged in a slit shape in the lengthwise direction of the linear light source or in a grid shape in the lengthwise and widthwise directions of the linear light source, and are arranged in the lengthwise direction of the linear light source. By partially changing the distance d between the thin plates, the amount of light transmitted through the light shield plate can be partially adjusted.

Normally, the amount of light is adjusted by changing the distance d, but it is also possible to change the height 1 independently, or by changing both the distance d and the height 1. Is also possible.

The arrangement of the light shielding plate assembly 17 is not limited to the slit shape or the grid shape, but may be a honeycomb shape.
Here, the light-shielding plate means that it is as thin as possible in order to reduce the reflection of light, that is, to easily absorb the light and reduce the loss of the transmitted light, for example, a black anodized aluminum plate or a black ironed thin iron plate. Etc. can be used.

Further, as shown in FIGS. 3 and 4, the light source unit 10 is located below the liquid crystal shutter 5 and above the photocurable resin 2 so as to photocur the transmitted light of the liquid crystal shutter 5. An equal-magnification image forming element 16 for forming an image on the liquid surface of the resin 2.
Is arranged.

The same-magnification image forming element 16 is provided in the liquid crystal shutter 5.
Of the transmission pattern light that has passed through, the light having a width and a length that can efficiently form only the light having an angle component close to vertical on the liquid surface of the photocurable resin 2 may be used. It is possible to use a self-hook lens array in which the cells are arranged in rows.

As shown in FIGS. 1 to 4, on the front and rear surfaces of the light source unit 10 in the traveling direction, that is, on both sides in the width direction, along the length direction of the light source unit 10 substantially linearly. A pair of smooth plates 18 that extend to smooth the liquid surface of the photocurable resin 2 is attached.

The smooth plate 18 is configured to be movable up and down via an elevating mechanism that can be independently driven, and the lower end of one of the smooth plates 18 located on the front side in the traveling direction of the light source unit 10 is photocured. The liquid surface of the photocurable resin 2 is smoothed as the light source unit 10 travels by lowering the liquid surface of the photocurable resin 2 until it comes into contact with the liquid surface.

As shown in FIG. 1, the positions and speeds of the elevator lifting mechanism 4, the linear moving mechanisms 7 and 9, and the liquid crystal shutter 5 are used.
Is displayed, the mechanical shutter 14 is turned on and off, the smoothing plate 18 is moved up and down, and the like. A computer 19 is provided as a control device. (Data) is connected to the data file 20 storing the data.

Then, the computer 19 calls the cross-sectional pattern of the target stereo model from the data file 20, divides this cross-sectional pattern into a plurality of divided patterns in the direction orthogonal to the moving direction of the liquid crystal shutter 5, and divides this divided pattern. A division pattern corresponding to the position of the liquid crystal shutter 5 on the container 1 is displayed on the liquid crystal shutter 5 in black and white.
It is designed to be displayed with a gradation mask pattern.

As described above, under the control of the computer 19, the cured resin layer 2a obtained by curing the liquid photocurable resin 2 on the surface of the elevator 3 is sequentially laminated, and the cured resin layer 2a is formed. A three-dimensional model is formed, which is performed as follows.

First, the elevator elevating mechanism 4 is driven so that the photocurable resin 2 located on the uppermost cured resin layer 2a (or the surface of the elevator 4) has a predetermined depth Δh. To do.

Next, the cross-sectional pattern (cross-sectional shape data) of the target stereo model stored in the data file 20 is called, and this cross-sectional pattern is divided into a plurality of division patterns in the direction orthogonal to the moving direction of the liquid crystal shutter 5. The division pattern corresponding to the position of the liquid crystal shutter 5 on the container 1 among the division patterns is a division pattern corresponding to the position of the liquid crystal shutter 5 on the container 1 on the liquid crystal shutter 5 with a black and white two-tone mask. A pattern is displayed on the liquid crystal shutter 5.

In this state, the light source unit 10 is opened from one end side of the liquid crystal shutter 5 to the other end side of the mechanical shutter 14, and the linear movement mechanism 9 is driven to move the light source unit 10 in parallel at a constant speed. The photocurable resin 2 of h is cured to form a part of the cured resin layer 2a of one layer corresponding to the position of the liquid crystal shutter 5.

Further, by driving the linear movement mechanism 7, the liquid crystal shutter 5 is moved to the next divided pattern display position,
The light source unit 10 is moved to one end of the liquid crystal shutter 5 while the mechanical shutter 14 is closed.
After returning by driving the mechanical shutter 14, the mechanical shutter 14 is opened to the other end of the liquid crystal shutter 5 to the light source unit 10.
This operation, that is, divided exposure is repeated while moving the liquid crystal, and the liquid crystal shutter 5 is sequentially partially cured while controlling the position of the liquid crystal shutter 5 corresponding to the position where the photocurable resin 2 is cured. To form.

Only when the light source unit 10 moves from one end side to the other end side of the liquid crystal shutter, one lower end of the one smooth plate 17 attached to the front side in the traveling direction of the light source unit 10 is photo-cured. The liquid level of the photocurable resin 2 is lowered so as to come into contact with the liquid level of the photocurable resin 2, whereby the liquid level of the photocurable resin 2 is smoothed as the light source unit 10 moves in parallel, and at the same time, the cured resin layer 2a is formed. can do.

At this time, the order of curing by the divided exposure may be that all the portions corresponding to the sectional pattern of the target stereo model are cured. Then, the cured resin layers 2a having a predetermined shape are sequentially laminated, and when a desired three-dimensional image is obtained, this is taken out of the container 1, washed to remove the uncured photocurable resin, and then post-cured. To complete the three-dimensional image.

Here, a method of controlling the angular component of the linear light by the light shielding plate and adjusting the light quantity will be described with reference to FIG. If thin plates having a height of 1 are arranged in a slit shape at intervals d under the linear light source, the angle θ of the light that can pass through the slit with respect to the light diverging in the length direction of the linear light source is It can be limited to about tan ^-1 (d / l) or less, and
According to the illuminance distribution in the length direction of the linear light source, the distance d between the thin plates
Can be partially changed to adjust the light amount, so that the light amount after passing through the light shielding plate can be made uniform. Further, if the light shielding plates are arranged in a grid pattern in the length and width directions of the light source and the height l and the interval d of the thin plates are adjusted in the length and width directions of the light source, respectively, the loss of light becomes large, but the slit Throughout the transmitted light, that is,
The angle component and the amount of light incident on the liquid crystal shutter can be controlled more precisely.

[0042]

As described above, according to the present invention, a liquid crystal shutter is used as an exposure mask and divided exposure is performed while alternately moving the shutter and the linear light source, thereby forming a large target stereo model. Moreover, not only does a large light source, a lens, etc. equivalent to the target three-dimensional model become unnecessary, but the optical path length from the light source to the irradiation surface of the photocurable resin can be shortened to reduce light loss, As a result, the size of the device can be reduced, and a large target three-dimensional model can be shaped accurately and in a shorter time.

Moreover, smooth plates are provided on the front and rear surfaces of the light source unit in the traveling direction, and one of the smooth plates located in front of the light source unit in the traveling direction is brought to a position where the lower end thereof contacts the liquid surface of the photocurable resin. By lowering, the liquid level of the photocurable resin can be smoothed as the light source unit travels, whereby the process for smoothing the liquid level can be omitted.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a moving mechanism of the light source unit.

FIG. 3 is an enlarged sectional view of the light source unit.

FIG. 4 is an enlarged cross-sectional view of a light source unit according to another embodiment of the present invention.

5A is a diagram illustrating a light amount adjustment method using a light-shielding plate assembly, which is an explanatory view seen from the side of FIG. 4. FIG. (B) is the explanatory view seen from the front of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container 2 ... Photocurable resin 2a ... Cured resin layer 5 ... Liquid crystal shutter 10 ... Light source unit 11 ... Linear light source 16 ... 1x imaging element 18 ... Smoothing plate 19 ... Computer (control part)

Claims (1)

[Claims] 1. A three-dimensional model is formed by selectively irradiating a liquid photocurable resin with light corresponding to a cross-sectional pattern of an intended three-dimensional model to form a thin cured resin layer, and successively laminating the cured resin layers. In the stereolithography apparatus configured to form, a liquid crystal shutter that selectively transmits or blocks light is run in parallel with the liquid surface of the photocurable resin above the container containing the photocurable resin. A light source unit which is arranged so as to obtain and which can be stopped at each passage point of a divided section obtained by dividing the traveling range of the liquid crystal shutter in a traveling direction of the liquid crystal shutter is arranged inside the light source unit. A linear light source is housed above the liquid crystal shutter so that the longitudinal direction thereof is substantially orthogonal to the traveling direction of the liquid crystal shutter, and the front and rear surfaces of the light source unit in the traveling direction are arranged in the traveling direction of the light source unit. Mounting a smooth plate to smooth the surface of the photocurable resin extends perpendicularly to the vertically movable,
A control unit that displays a cross-sectional pattern of a stereo model corresponding to the divided section on the liquid crystal shutter is provided, and the liquid crystal shutter can be stopped at each passage point of the divided section, and the line is displayed while the liquid crystal shutter is stopped. Shaping by further repeating a series of operations in which a linear light source passes over the liquid crystal shutter and performs divided exposure in a traveling range in one direction of the liquid crystal shutter to further cure the photocurable resin. apparatus.