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JP3578176B2 - Stereolithography - Google Patents

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JP3578176B2
JP3578176B2 JP25107194A JP25107194A JP3578176B2 JP 3578176 B2 JP3578176 B2 JP 3578176B2 JP 25107194 A JP25107194 A JP 25107194A JP 25107194 A JP25107194 A JP 25107194A JP 3578176 B2 JP3578176 B2 JP 3578176B2
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JPH08112862A (en
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輝一 小久保
房澄 真坂
直樹 柳通
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JSR Corp
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Description

【0001】
【産業上の利用分野】
本発明は、液状の光硬化性樹脂に光を照射し、所望の形状を持つ立体モデルを形成する光造形装置に関する。
【0002】
【従来の技術】
光造形装置としては、液状の光硬化性樹脂の表面にスポット状のレーザ光を平面的に走査させて目的造形物の断面パターンを描く露光を行って、レーザ光が当たった部分に位置する光硬化性樹脂のみを硬化させて薄膜の硬化樹脂層を形成し、この硬化樹脂層を連続的に幾層にも積層することで、立体モデルを形成するようにしたものが一般に知られている。
【0003】
しかしながら、このようなレーザ光による露光方式を採用した光造形装置の場合、レーザ光での走査は、一筆書きによる長い線を描くのと同様の工程となるため、造形に長時間が必要であった。
【0004】
このため、レーザ光の代わりに、平行光を用いた光造形装置、即ち、平行光の光源と光硬化性樹脂との間に液晶シャッタを配置し、この液晶シャッタ上に表示した立体モデル(目的造形物)の断面パターンをマスクパターン(露光マスクパターン)として使用して、このマスクパターンを介した平行光による一括露光で高速に光硬化性樹脂を硬化させるようにしたものが広く知られている(例えば、特開昭62−288844号公報、特開平3−227222号公報、実開平2−31726号公報等参照)。
【0005】
しかし、液晶シャッタと平行光を用いた従来例の場合、一括露光を行うためには、液晶シャッタのサイズと少なくとも同じだけの面積を照射する照射強度の均一な平行光が必要となり、液晶シャッタのサイズが大きいほど、高圧水銀ランプ等の光源から均一な平行光を得るために、大型のレンズや反射板等を使用し、しかも長い光路長が必要となって、光源、ひいては装置全体が大型化してしまうといった問題があった。
【0006】
そこで、大型のレンズや反射板、長い光路長を必要としない造形方法として、平行光による一括露光を用いる代わりに、ロングアークの水銀ランプ等を使用した線状光源と液晶シャッタ等を組み合わせ、線状光源を移動させることにより、液晶シャッタのマスクパターンを介した線露光で光硬化性樹脂を硬化させるようにしたものが一般に知られている(特開平4−284227号公報、特開平4−305438号公報、特願平6−88337号、特願平6−120257号) 。
【0007】
【発明が解決しようとする課題】
しかしながら、線状光源を用いた従来例の場合、光源からミラー等で反射集光され液晶シャッタ面に入射する線状光は、平行光でなくシャッタ面に対して様々な角度成分を有するが、実際に液晶シャッタのマスクパターンに忠実な光硬化性樹脂の硬化層形成に利用できる光は、液晶シャッタの視野角依存性の為に、液晶シャッタ面から垂直に近い角度で出射する平行光に近い光成分のみで、この光を等倍結像素子等の光学系で選択的に利用する。この結果、液晶シャッタ面に入射する光の大半は非利用光となり、この非利用光が液晶シャッタの急激な昇温を招き、コントラストを著しく低下させるばかりか、液晶シャッタを劣化させ、寿命を短くするという問題があった。
【0008】
また、線状光源は使用する光源自体あるいは光源種類やロットの違いによっても光源長さ方向の発光強度に分布があり、且つその分布がばらつくため、その結果、光硬化性樹脂を硬化する際、硬化樹脂の膜厚が不均一となり、造形精度の低下を招くという問題があった。
【0009】
本発明は上記問題点を解消すべくなされたもので、液晶シャッタの昇温によるコントラスト低下やシャッタ性能の劣化を抑制し、光源照度分布を均一化し得る光造形装置を提供することを目的とする。
【0010】
【課題を解決するための手段】
上記目的を達成するため、本発明は、液状の光硬化性樹脂の上方であって巾方向に走行自在に配置した線状光源からの光線を、光透過部と遮光部とからなる液晶シャッタ及び該液晶シャッタの透過光を光硬化性樹脂面に結像する等倍結像素子を経て、前記光硬化性樹脂の液面に照射して、目的立体モデルの断面パターンに対応する薄膜の硬化樹脂層を形成し、この樹脂層を順次積層して立体モデルを形成するようにした光造形装置において、
前記線状光源と前記液晶シャッタとの間に、前記線状光源から発せられる光のうち、前記等倍結像素子を通過できない入射角を有する光成分を遮断する遮光板組立体を装着したことを特徴とするものである。
【0011】
【作用】
巾方向に走行する光源から出た光は、液晶シャッタに向かうが、この際、遮光板組立体の調節により、等倍結像素子の開口角よりも大きい角度をもって液晶シャッタに入射する光、すなわち、光硬化性樹脂の硬化に利用されない光を遮光することができ、これにより、液晶シャッタの昇温が防止される。また、遮光板組立体の調節により光源の長さ方向の光量を均一化することができ、この結果、光源の照度分布が均一化される。
【0012】
【実施例】
以下、本発明の実施例を図面を参照して説明する。
図1において、付番1は、上方に開口した矩形ボックス状の容器(樹脂槽)で、この容器1の内部には、光が当たると液体から固体に硬化する液状の光硬化性樹脂2が満たされている。この光硬化性樹脂2は、光エネルギーによって重合反応を起こして、液体が固体に変化するという特性を持った樹脂で、例えば光重合性ポリマー、光開始剤、特性改善のための添加剤等を含むことができる。
【0013】
前記容器1の一側方には、前記容器1内に位置して上下に昇降する平板状のエレベータ3を備えた位置制御可能なエレベータ昇降機構4が配置され、このエレベータ3の上に光硬化樹脂2が硬化することによって得られる硬化樹脂層2aが順次積層されるようになっている。
【0014】
また、前記容器1の他側方には、平面状に拡がって前記容器1内に収容された光硬化性樹脂2の液面のほぼ全域を覆う液晶シャッタ5を、その一端において水平に保持する液晶シャッタ保持機構6が立設されている。
【0015】
前記液晶シャッタ5は、目的立体モデルの断面パターンを透過部と遮断部で表示できるものであれば良く、例えば、STN型液晶パネル、TN型液晶パネル、ポリマー分散型液晶パネル等を使用することができる。
【0016】
更に、前記容器1の該容器1を挟んだ両側には、図2に示すように、レール7上をエアー圧やステッピングモータ等の駆動装置によって走行する支柱8を備えた位置制御可能な一対の直線移動機構9が平行かつ水平に配置され、この支柱8の上端に、容器1を跨がって直線状に延びる光源ユニット10の端部が連結されている。そして、前記光源ユニット10の内部には、前記液晶シャッタ5が挿通する矩形枠状の窓部10aが形成されている。
【0017】
これにより、光源ユニット10は、容器1の上方に位置し、液晶シャッタ5を挟んだ状態で、直線移動機構9の駆動に伴う支柱8の互いに同期した移動に伴って、その幅方向に水平に走行し、しかもこの走行が液晶シャッタ5によって阻害されないようになっている。
【0018】
なお、この実施例では、直線移動機構として、位置及び速度の制御が比較的容易なエアー圧やステッピングモータ等を使用した例を示しているが、油圧シリンダ等、任意のものを使用しても良いことは勿論である。
【0019】
前記光源ユニット10の内部の前記液晶シャッタ5の上方位置には、この長さ方向に沿ってこのほぼ全長に亘って直線状に延びる線状光源11が前記光硬化性樹脂2の液面と水平に配置されて収容されている。
【0020】
この線状光源11としては、例えば、クリプトンロングアークランプ、キセノンロングアークランプ、メタルハライドロングアークランプ、水銀ロングアークランプ等を使用することができる。
【0021】
前記線状光源11の上方には、図3に示すようにこの線状光源11から出た光を反射して、この反射光を前記液晶シャッタ5上に集光させる円弧状の反射ミラー12が、この反射ミラー12の下方で前記液晶シャッタ5の上方位置には、前記線状光源11からの光の内、等倍結像素子16を通過できない入射角を有する光成分を遮断し、光量を調節する遮光板組立体13と光硬化性樹脂の硬化反応に寄与しない波長域の熱エネルギーや光エネルギーを遮光し、液晶へのダメージを防止するための熱線吸収フィルタ14と光の透過と遮光を切り替えるためのメカニカルシャッタ15とが上下に平行に順に配置されて前記光源ユニット10内に収容されている。
【0022】
前記遮光板組立体13は、複数の長方形の薄板13aから構成され、等倍結像素子の開口角より大きな角度成分光を遮光するもので、図4(a)、(b)に示すように、高さlの長方形の薄板を垂直に立て、該薄板のそれぞれの面が平行になるように間隔dを置いて、線状光源の長さ方向にスリット状に、或いは線状光源の長さ方向と幅方向に格子状に配列され、前記薄板の高さlと間隔dを調節して、入射角tan−1(d/l)以上の光線成分を遮光する。
【0023】
また、遮光体組立体13は、線状光源の長さ方向の光量を均一化する機能をも果たし、高さlの長方形の薄板を垂直に立て、該薄板のそれぞれの面が平行になるように間隔dを置いて、線状光源の長さ方向にスリット状に、或いは線状光源の長さ方向と幅方向に格子状に配列され、線状光源の長さ方向に並んだ前記薄板の間隔dを部分的に変えることにより、遮光板を透過する光量を部分的に調節することができる。
【0024】
通常、光量の調節は間隔dを変えることにより行うが、高さlを単独で変えることにより行うことも可能であり、あるいは間隔dと高さlとの双方を変えることにより行うことも可能である。
【0025】
また、遮光板組立体13の配列は、スリット状又は格子状に限らず、ハニカム状であってもよい。
すなわち、本発明においては、遮光板組立体は、液晶シャッタへの入射光を遮光によって選択的に規制するのであるが、これはより具体的には以下の実施態様のいずれかによって達成される。
(1)線状光源から液晶シャッタへ入射する光線のうち、入射角が等倍結像素子の開口角より大きな角度成分を遮光する。
(2)遮光板組立体の調節により、線状光源の長さ方向の光量を均一化する。
(3)線状光源から液晶シャッタ面へ入射する光線のうち、入射角が等倍結像素子の開口角より大きな角度成分を遮光し、かつ遮光板組立体の調節により、線状光源の長さ方向の光量を均一化する。
【0026】
なお、本発明において、遮光板とは光の反射の少ない、即ち光を吸収し易く且つ透過光のロスを少なくするためできるだけ薄板であればよく、例えば、黒アルマイト処理したアルミ板や黒染めした薄い鉄板等が使用できる。
【0027】
更に、光源ユニット10の前記液晶シャッタ5の下方位置には、光硬化性樹脂2の上方に位置して前記液晶シャッタ5の透過光を光硬化性樹脂2の液面に結像する等倍結像素子16が配置されている。
【0028】
この等倍結像素子16は、液晶シャッタ5を透過した透過パターン光を効率良く光硬化性樹脂2の液面に結像できる幅と長さを有するものであれば良く、例えば、セルホックレンズを列状に並べたセルホックレンズアレー等を使用することができる。
【0029】
図1または図2に示すように、前記光源ユニット10の走行方向の前後面、即ち幅方向の両側には、光源ユニット10の長さ方向に沿ってそのほぼ全長に亘って直線状に延びて光硬化性樹脂2の液面を平滑化する一対の平滑板17が取り付けられている。
【0030】
この平滑板17は、それぞれ独立に駆動できる昇降機構を介して上下動自在に構成され、前記光源ユニット10の進行方向の前方側に位置する一方の平滑板17をこの下端が光硬化性樹脂2の液面に接触するまで下降させることにより、光源ユニット10の走行に伴って、光硬化性樹脂2の液面の平滑化を行うようになっている。
【0031】
図1に示すように、前記エレベータ昇降機構4、直線移動機構9の位置と速度、液晶シャッタ5の表示、メカニカルシャッタ15のオン・オフ、平滑板17の昇降等をそれぞれ独立に制御する制御装置としてのコンピュータ18が備えられ、このコンピュータ(制御装置)18は、目的立体モデルの断面パターン(造形データ)を格納したデータファイル19に接続されている。
【0032】
そして、このコンピュータ18は、データファイル19から目的立体モデルの断面パターンを呼出し、この断面パターンを図形として液晶シャッタ5上に白黒の2階調のマスクパターンで表示させるようになっている。
【0033】
このように、コンピュータ18による制御により、前記エレベータ3の表面に液状の光硬化性樹脂2が硬化することによって得られる硬化樹脂層2aを順次積層して、この硬化樹脂層2aからなる立体モデルを形成するものであるが、これを以下のようにして行う。
【0034】
先ず、エレベータ昇降機構4を駆動させて、最上段に位置する硬化樹脂層2a(またはエレベータ4の表面)の上に位置する光硬化性樹脂2が所定の深さΔhになるようにする。
【0035】
次に、データファイル19に格納されている目的立体モデルの断面パターン(断面形状データ)を呼び出して、この断面パターンを図形として白黒の2階調のマスクパターンで前記液晶シャッタ5に表示させる。
【0036】
この状態で、メカニカルシャッタ15を開き、光源ユニット10を一方の端辺から他方の端辺まで、直線移動機構9の駆動によって一定の速度で平行移動させることにより、光源ユニット10内の線状光源11から出射され、遮光板組立体13を介して液晶シャッタ5を透過した線状光で光硬化層樹脂2の液面を照射して、一層の硬化樹脂層2aを形成する。
【0037】
即ち、液晶シャッタ5に表示された白黒の2諧調のマスクパターンによって、例えば白色の部分で光を透過させ、黒色の部分で光を遮断することにより、液晶シャッタ5に表示されたマスクパターン形状と同様な形状の硬化樹脂層2aを形成することができる。
【0038】
この光源ユニット10の移動の際、光源ユニット10の進行方向の前面側に取り付けられた一方の平滑板17をこの下端が光硬化性樹脂2の液面に接触するよう下降させ、これによって、光源ユニット10の平行移動に伴って光硬化性樹脂2の液面の平滑化を行い、この平滑化と同時に硬化樹脂層2aを形成することができる。
【0039】
そして、これと同様な操作を繰り返すことにより、所定形状の硬化樹脂層2aを順次積層し、所望の立体像が得られた時に、これを容器1から取り出し、洗浄し未硬化の光硬化性樹脂を取り除き、しかる後ポストキュアを施して立体像を完成させる。
【0040】
ここで、遮光板による線状光の角度成分を制御し光量を調節する方法について図1を参照して説明する。
線状光源下に、高さがlの薄板を間隔dをおいてスリット状に配列すれば、線状光源の長さ方向に発散する光に対して、このスリットを通過できる光の角度θはおよそtan−1(d/l)以下に制限でき、また、線光源の長さ方向の照度分布に合わせて、薄板の間隔dを部分的に変え光量を調節すれば遮光板通過後の光量を均一化できる。更に、遮光板を光源の長さ及び幅方向に格子状に配置し、薄板の高さl及び間隔dを光源の長さと幅方向でそれぞれ調節すれば、光のロスは大きくなるものの、スリットを透過する光全般に亘って、つまり、液晶シャッタへ入射する光の角度成分と光量をより精密に制御できる。
【0041】
次に、本発明のより具体的な例につき、従来例と比較しつつ説明する。
図5は、遮光板組立体の有無をパラメータとして、光源ユニットを一定のインターバルで移動させたときの液晶シャッタ中央部で測定した該シャッタ表面温度の時間変化を示し、図6は遮光板組立体使用前と使用後における光源長さ方向の照度分布を示すもので、以下に実施条件を示す。
【0042】
図3に示した光源ユニット10において、線状光源11に3.5KWの長さ約300mmのメタルハライドロングアークランプおよび等倍結像素子16として開口角(透過できる入射光の最大角度)が12°のセルホックアレーを使用し、この時の遮光板組立体11を使用例においては、該遮光板組立体は、液晶シャッタへの入射光の角度成分がおよそ12°以下になるよう高さ17mm、厚さ0.3mmの黒染め鉄板を7mm間隔で線状光源の長さ方向にスリット状に配列した。
【0043】
図5の結果は上記条件で、光源ユニット10を連続的に速度15mm/sで液晶シャッタ両端間をそれぞれの端で約20秒のインターバルをおくようにして往復移動させた場合の室温雰囲気での液晶シャッタ中央付近の表面温度を測定したもので、遮光板組立体のない場合、温度は経時的に液晶の等方性温度付近まで上昇し、且つ光源の通過に伴い局所的に急激な温度上昇の為に液晶シャッタのコントラストが低下するばかりか、シャッタとして使用できなくなる一方、遮光板組立体を使用した場合、温度上昇はほとんど見られず、局所的温度上昇も穏やかである。遮光板組立体を用いずに造形をする場合、よりパワーの小さい光源を使用しなければならず、造形に長時間を要していたが、簡便な遮光板を使用するだけで、よりパワーの大きな光源の使用が可能になり造形時間短縮ができる。
【0044】
図6の結果は前記条件で、セルホックレンズを透過し光硬化性樹脂2の位置に届く光の照度分布を光源の長さ方向で測定したもので、遮光板がある場合の照度分布は、遮光板のない場合の照度分布に応じて、遮光板の初期の間隔7mmから場所により間隔を変え、光量を調節することによって照度の均一化を実現したもので、全体的に照度は低下するもののこの実施例では約15%あった照度のばらつきを2%程度に抑えられた。
【0045】
【発明の効果】
以上説明したように、本発明では線状光源と液晶シャッタの間に、簡便な、遮光板を用いた遮光板組立体を配置することにより、光硬化性樹脂の硬化に利用されない角度成分を有する光成分を遮光することによって、液晶シャッタの昇温によるコントラスト低下やシャッタ性能の劣化を抑制し得るとともにより高出力光源の使用が可能になるため、造形時間の短縮が実現できる。また、遮光板組立体を調節することにより、光源照度分布を均一化し、目的立体モデルを精度よく造形することができる。
【図面の簡単な説明】
【図1】本発明の一実施例を示す概要図。
【図2】同じく、光源ユニットの移動機構を示す斜視図。
【図3】同じく、光源ユニットの拡大断面図。
【図4】図4(a)は、遮光板組立体による光量調整方法を示すもので、図3の側面からみた説明図。図4(b)は、図3の正面からみた説明図。
【図5】同じく、遮光板組立体による遮光の効果を示す測定結果図。
【図6】同じく、遮光体組立体による光源光均一化の効果を示す測定結果図。
【符号の説明】
1…容器
2…光硬化性樹脂
2a…硬化樹脂層
5…液晶シャッタ
10…光源ユニット
11…線状光源
13…遮光板組立体
15…等倍結像素子
[0001]
[Industrial applications]
The present invention relates to an optical shaping apparatus that irradiates a liquid photocurable resin with light to form a three-dimensional model having a desired shape.
[0002]
[Prior art]
An optical shaping device is an apparatus that performs an exposure that scans a surface of a liquid photo-curable resin with a spot-shaped laser light in a plane to draw a cross-sectional pattern of a target shaping object, and the light positioned at a portion where the laser light is applied. It is generally known that a three-dimensional model is formed by curing a curable resin alone to form a thin-film cured resin layer, and successively laminating the cured resin layers in layers.
[0003]
However, in the case of such an optical shaping apparatus that employs such an exposure method using a laser beam, scanning with the laser beam is a process similar to drawing a long line with a single stroke, and thus requires a long time for modeling. Was.
[0004]
For this reason, instead of the laser beam, an optical shaping apparatus using parallel light, that is, a liquid crystal shutter is disposed between the light source of the parallel light and the photocurable resin, and a three-dimensional model (object It is widely known that a cross-sectional pattern of a molded article is used as a mask pattern (exposure mask pattern) to cure a photocurable resin at a high speed by batch exposure using parallel light through the mask pattern. (See, for example, JP-A-62-288844, JP-A-3-227222, and JP-A-2-31726).
[0005]
However, in the case of the conventional example using the liquid crystal shutter and the parallel light, in order to perform the collective exposure, the parallel light having the uniform irradiation intensity for irradiating an area at least as large as the size of the liquid crystal shutter is required. The larger the size, the larger the size of the light source, and thus the larger the device, the larger the light path and the longer the optical path length is required to obtain uniform parallel light from a light source such as a high-pressure mercury lamp. Problem.
[0006]
Therefore, as a modeling method that does not require large lenses, reflectors, and long optical path lengths, instead of using batch exposure with parallel light, a linear light source using a long-arc mercury lamp or the like is combined with a liquid crystal shutter, etc. It is generally known that a photocurable resin is cured by line exposure through a mask pattern of a liquid crystal shutter by moving a liquid crystal light source (Japanese Patent Application Laid-Open Nos. 4-284227 and 4-305438). Gazette, Japanese Patent Application No. 6-88337, Japanese Patent Application No. 6-120257).
[0007]
[Problems to be solved by the invention]
However, in the case of the conventional example using a linear light source, the linear light reflected and condensed by a mirror or the like from the light source and incident on the liquid crystal shutter surface has various angle components with respect to the shutter surface instead of parallel light. Actually, light that can be used for forming a cured layer of a photocurable resin that is faithful to the mask pattern of the liquid crystal shutter is close to parallel light emitted from the liquid crystal shutter surface at an almost perpendicular angle due to the viewing angle dependence of the liquid crystal shutter. This light is selectively used in an optical system such as an equal-magnification imaging element using only the light component. As a result, most of the light incident on the liquid crystal shutter surface is unused light, and this unused light causes a rapid rise in the temperature of the liquid crystal shutter, not only significantly lowering the contrast but also deteriorating the liquid crystal shutter and shortening the life. There was a problem of doing.
[0008]
In addition, the linear light source has a distribution in the luminous intensity in the length direction of the light source depending on the type of light source used or the type of light source and the lot, and the distribution varies. As a result, when curing the photocurable resin, There has been a problem that the thickness of the cured resin becomes non-uniform, resulting in a decrease in modeling accuracy.
[0009]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical shaping apparatus capable of suppressing a decrease in contrast and a deterioration in shutter performance due to a rise in temperature of a liquid crystal shutter and uniforming a light source illuminance distribution. .
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a liquid crystal shutter including a light transmitting portion and a light shielding portion, which receives a light beam from a linear light source disposed above a liquid photocurable resin so as to be able to travel in the width direction. The liquid crystal shutter is irradiated with a liquid surface of the photocurable resin through an equal-magnification imaging element that forms an image of the transmitted light of the liquid crystal shutter on the photocurable resin surface, thereby forming a thin cured resin corresponding to the cross-sectional pattern of the target three-dimensional model. In a stereolithography apparatus in which a layer is formed and this resin layer is sequentially laminated to form a three-dimensional model,
A light- shielding plate assembly is provided between the linear light source and the liquid crystal shutter, the light-shielding plate assembly being configured to block a light component having an incident angle that cannot pass through the same-magnification imaging element, of light emitted from the linear light source. It is characterized by the following.
[0011]
[Action]
Light emitted from the light source traveling in the width direction travels to the liquid crystal shutter. At this time, light incident on the liquid crystal shutter at an angle larger than the aperture angle of the unit-magnification imaging element due to adjustment of the light shielding plate assembly, that is, In addition, light not used for curing the photocurable resin can be shielded, thereby preventing the temperature of the liquid crystal shutter from rising. Further, the light amount in the length direction of the light source can be made uniform by adjusting the light shielding plate assembly, and as a result, the illuminance distribution of the light source is made uniform.
[0012]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a rectangular box-shaped container (resin tank) opened upward, and a liquid photo-curable resin 2 that cures from a liquid to a solid when exposed to light is provided inside the container 1. be satisfied. The photocurable resin 2 is a resin having a property that a polymerization reaction is caused by light energy and a liquid is changed into a solid. For example, a photopolymerizable polymer, a photoinitiator, an additive for improving properties and the like are used. Can be included.
[0013]
On one side of the container 1, a position-controllable elevator lifting mechanism 4 including a flat elevator 3 that is located in the container 1 and that moves up and down is arranged. A cured resin layer 2a obtained by curing the resin 2 is sequentially laminated.
[0014]
On the other side of the container 1, a liquid crystal shutter 5, which spreads in a plane and covers substantially the entire liquid surface of the photocurable resin 2 accommodated in the container 1, is held horizontally at one end. A liquid crystal shutter holding mechanism 6 is provided upright.
[0015]
The liquid crystal shutter 5 only needs to be capable of displaying the cross-sectional pattern of the target three-dimensional model in the transmission part and the blocking part. For example, an STN type liquid crystal panel, a TN type liquid crystal panel, a polymer dispersion type liquid crystal panel, or the like can be used. it can.
[0016]
Further, as shown in FIG. 2, a pair of position-controllable pairs of columns 8 are provided on both sides of the container 1 with the container 1 interposed therebetween by a driving device such as air pressure or a stepping motor. A linear moving mechanism 9 is arranged in parallel and horizontally, and an end of a light source unit 10 extending linearly across the container 1 is connected to an upper end of the support 8. Further, inside the light source unit 10, a rectangular frame-shaped window portion 10a through which the liquid crystal shutter 5 is inserted is formed.
[0017]
As a result, the light source unit 10 is positioned above the container 1, and, in a state where the liquid crystal shutter 5 is sandwiched between the light source units 10, horizontally moves in the width direction with the synchronized movement of the columns 8 accompanying the driving of the linear moving mechanism 9. It travels, and the traveling is not hindered by the liquid crystal shutter 5.
[0018]
Note that, in this embodiment, an example is shown in which an air pressure or a stepping motor whose position and speed are relatively easily controlled is used as the linear moving mechanism. The good thing is, of course.
[0019]
At a position above the liquid crystal shutter 5 inside the light source unit 10, a linear light source 11 extending linearly over substantially the entire length along the length direction is horizontal to the liquid surface of the photocurable resin 2. Are placed and housed.
[0020]
As the linear light source 11, 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.
[0021]
Above the linear light source 11, an arc-shaped reflecting mirror 12 for reflecting the light emitted from the linear light source 11 and condensing the reflected light on the liquid crystal shutter 5 as shown in FIG. At a position below the reflection mirror 12 and above the liquid crystal shutter 5, a light component having an incident angle that cannot pass through the equal-magnification imaging element 16 out of the light from the linear light source 11 is blocked, and the light amount is reduced. A heat ray absorption filter 14 for blocking heat energy and light energy in a wavelength range that does not contribute to the curing reaction of the light-shielding resin with the light-shielding plate assembly 13 to be adjusted, and a light-ray absorbing filter 14 for preventing damage to the liquid crystal. A mechanical shutter 15 for switching is arranged vertically in parallel in order and accommodated in the light source unit 10.
[0022]
The light-shielding plate assembly 13 is composed of a plurality of rectangular thin plates 13a and shields an angle component light larger than the aperture angle of the unit-magnification imaging element, as shown in FIGS. 4 (a) and 4 (b). , A rectangular thin plate having a height of l is set up vertically, and at intervals d such that the respective surfaces of the thin plate are parallel, a slit is formed in the length direction of the linear light source, or the length of the linear light source is It is arranged in a grid pattern in the direction and the width direction, and adjusts the height l and the interval d of the thin plate to shield light components having an incident angle of tan -1 (d / l) or more.
[0023]
The light-shielding body assembly 13 also has a function of equalizing the amount of light in the length direction of the linear light source, and vertically sets a rectangular thin plate having a height l so that the respective surfaces of the thin plate are parallel. At intervals d, in a slit shape in the length direction of the linear light source, or arranged in a lattice shape in the length direction and the width direction of the linear light source, and the thin plates arranged in the length direction of the linear light source. By partially changing the distance d, the amount of light transmitted through the light-shielding plate can be partially adjusted.
[0024]
Normally, the adjustment of the light amount is performed by changing the distance d, but it is also possible to perform the adjustment by changing the height l alone, or by changing both the distance d and the height l. is there.
[0025]
The arrangement of the light shielding plate assemblies 13 is not limited to the slit shape or the lattice shape, but may be a honeycomb shape.
That is, in the present invention, the light-shielding plate assembly selectively restricts the light incident on the liquid crystal shutter by blocking the light, which is more specifically achieved by any of the following embodiments.
(1) Among light rays incident on the liquid crystal shutter from the linear light source, an angle component whose incident angle is larger than the aperture angle of the unity magnification imaging element is shielded.
(2) The light amount in the length direction of the linear light source is made uniform by adjusting the light shielding plate assembly.
(3) Of the light rays incident on the liquid crystal shutter surface from the linear light source, an angle component whose incident angle is larger than the aperture angle of the unit magnification imaging element is shielded, and the length of the linear light source is adjusted by adjusting the light shielding plate assembly. The light amount in the vertical direction.
[0026]
In the present invention, the light-shielding plate may be a thin plate as much as possible to reduce light reflection, that is, easily absorb light and reduce loss of transmitted light, for example, a black anodized aluminum plate or black dyed. A thin iron plate or the like can be used.
[0027]
Further, at a position below the liquid crystal shutter 5 of the light source unit 10, it is positioned above the photocurable resin 2 and forms an equal magnification to form an image of the transmitted light of the liquid crystal shutter 5 on the liquid surface of the photocurable resin 2. An image element 16 is arranged.
[0028]
The unit-magnification imaging element 16 may be any element having a width and a length capable of efficiently forming the transmission pattern light transmitted through the liquid crystal shutter 5 on the liquid surface of the photocurable resin 2. May be used in a cell array.
[0029]
As shown in FIG. 1 or FIG. 2, the front and rear surfaces of the light source unit 10 in the running direction, that is, both sides in the width direction, extend linearly over substantially the entire length thereof along the length direction of the light source unit 10. A pair of smoothing plates 17 for smoothing the liquid surface of the photocurable resin 2 are attached.
[0030]
The smoothing plate 17 is configured to be vertically movable via an elevating mechanism that can be driven independently of each other, and the lower end of one of the smoothing plates 17 located on the front side in the traveling direction of the light source unit 10 is a light curable resin 2. As the light source unit 10 travels, the liquid surface of the photocurable resin 2 is smoothed by lowering it until it comes into contact with the liquid surface.
[0031]
As shown in FIG. 1, a control device for independently controlling the position and speed of the elevator elevating mechanism 4, the linear moving mechanism 9, the display of the liquid crystal shutter 5, the on / off of the mechanical shutter 15, the elevation of the smoothing plate 17, and the like. The computer (control device) 18 is connected to a data file 19 storing a cross-sectional pattern (modeling data) of the target three-dimensional model.
[0032]
Then, the computer 18 calls up the cross-sectional pattern of the target three-dimensional model from the data file 19, and displays the cross-sectional pattern as a graphic on the liquid crystal shutter 5 with a two-tone mask pattern of black and white.
[0033]
As described above, under the control of the computer 18, the cured resin layer 2a obtained by curing the liquid photocurable resin 2 on the surface of the elevator 3 is sequentially laminated, and a three-dimensional model including the cured resin layer 2a is formed. This is performed as follows.
[0034]
First, the elevator raising / lowering 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.
[0035]
Next, a cross-sectional pattern (cross-sectional shape data) of the target three-dimensional model stored in the data file 19 is called, and the liquid crystal shutter 5 is displayed as a monochrome two-tone mask pattern using the cross-sectional pattern as a graphic.
[0036]
In this state, the mechanical shutter 15 is opened, and the light source unit 10 is moved in parallel from one end to the other end at a constant speed by driving the linear moving mechanism 9, thereby obtaining a linear light source in the light source unit 10. The liquid surface of the photocurable resin layer 2 is irradiated with linear light emitted from the liquid crystal panel 11 and transmitted through the liquid crystal shutter 5 through the light shielding plate assembly 13 to form one cured resin layer 2a.
[0037]
That is, for example, the mask pattern of two gradations of black and white displayed on the liquid crystal shutter 5 transmits light in a white portion and blocks light in a black portion, thereby changing the shape of the mask pattern displayed on the liquid crystal shutter 5. A cured resin layer 2a having a similar shape can be formed.
[0038]
When the light source unit 10 is moved, one of the smoothing plates 17 attached to the front side in the traveling direction of the light source unit 10 is lowered so that its lower end contacts the liquid surface of the photocurable resin 2, whereby the light source With the parallel movement of the unit 10, the liquid surface of the photocurable resin 2 is smoothed, and simultaneously with this smoothing, the cured resin layer 2a can be formed.
[0039]
Then, by repeating the same operation, the cured resin layers 2a of a predetermined shape are sequentially laminated, and when a desired three-dimensional image is obtained, this is removed from the container 1, washed, and washed to form an uncured photocurable resin. Is removed and then post-cured to complete the three-dimensional image.
[0040]
Here, a method of controlling the angle component of the linear light by the light shielding plate to adjust the light amount will be described with reference to FIG.
If thin plates having a height of l are arranged in a slit shape at intervals d under a linear light source, the angle θ of light that can pass through this slit with respect to light diverging in the length direction of the linear light source is The light amount after passing through the light-shielding plate can be limited to approximately tan -1 (d / l) or less, and if the light amount is adjusted by partially changing the distance d between the thin plates according to the illuminance distribution in the length direction of the linear light source. It can be made uniform. Furthermore, if the light-shielding plates are arranged in a lattice shape in the length and width directions of the light source, and the height l and the interval d of the thin plate are adjusted in the length and width directions of the light source, respectively, the light loss increases, but the slits are formed. It is possible to more precisely control the angle component and the light amount of the light that enters the liquid crystal shutter over the entire transmitted light.
[0041]
Next, a more specific example of the present invention will be described in comparison with a conventional example.
FIG. 5 shows a temporal change of the shutter surface temperature measured at the center of the liquid crystal shutter when the light source unit is moved at a constant interval, with the presence or absence of the light-shielding plate assembly as a parameter. It shows the illuminance distribution in the length direction of the light source before and after use, and the execution conditions are shown below.
[0042]
In the light source unit 10 shown in FIG. 3, the linear light source 11 has a metal halide long arc lamp having a length of 3.5 KW and a length of about 300 mm and an aperture ratio (maximum angle of incident light that can be transmitted) of 12 ° as a 1 × imaging element 16. In the example of using the light-shield plate assembly 11 at this time, the light-shield plate assembly has a height of 17 mm so that the angle component of the light incident on the liquid crystal shutter is approximately 12 ° or less. Black-dyed iron plates having a thickness of 0.3 mm were arranged in slits in the length direction of the linear light source at intervals of 7 mm.
[0043]
The results in FIG. 5 show that the light source unit 10 was reciprocated between the two ends of the liquid crystal shutter continuously at a speed of 15 mm / s with an interval of about 20 seconds at each end under the above-mentioned conditions. The surface temperature near the center of the liquid crystal shutter was measured. In the absence of the light-shielding plate assembly, the temperature rose to near the isotropic temperature of the liquid crystal over time, and the temperature rapidly increased locally as the light source passed. For this reason, not only does the contrast of the liquid crystal shutter decrease, but the liquid crystal shutter cannot be used as a shutter. On the other hand, when the light-shielding plate assembly is used, the temperature rise is hardly observed, and the local temperature rise is moderate. When molding without using the light-shielding plate assembly, a light source with lower power had to be used, and it took a long time for modeling. A large light source can be used, and the molding time can be reduced.
[0044]
The result of FIG. 6 is a result of measuring the illuminance distribution of light that passes through the cell hook lens and reaches the position of the photocurable resin 2 in the length direction of the light source under the above-described conditions. According to the illuminance distribution without the light-shielding plate, the uniformity of the illuminance is realized by changing the distance from the initial interval of the light-shielding plate of 7 mm and by adjusting the amount of light, thereby reducing the overall illuminance. In this embodiment, the variation of the illuminance, which was about 15%, was suppressed to about 2%.
[0045]
【The invention's effect】
As described above, in the present invention, a simple, light-shielding plate assembly using a light-shielding plate is disposed between a linear light source and a liquid crystal shutter, thereby having an angle component that is not used for curing the photocurable resin. By blocking the light component, it is possible to suppress a decrease in contrast and a deterioration in shutter performance due to a rise in the temperature of the liquid crystal shutter, and to use a higher-output light source, thereby shortening the modeling time. Further, by adjusting the light-shielding plate assembly, the illuminance distribution of the light source can be made uniform, and the target three-dimensional model can be accurately formed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing one 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 (a) shows a light amount adjusting method using a light shielding plate assembly, and is an explanatory diagram viewed from the side in FIG. 3; FIG. 4B is an explanatory diagram viewed from the front of FIG. 3.
FIG. 5 is a measurement result diagram showing the effect of light shielding by the light shielding plate assembly.
FIG. 6 is a measurement result diagram showing the effect of equalizing the light source light by the light-shielding body assembly.
[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 13 ... Shield plate assembly 15 ... 1: 1 image forming element

Claims (1)

液状の光硬化性樹脂の上方であって巾方向に走行自在に配置した線状光源からの光線を、光透過部と遮光部とからなる液晶シャッタ及び該液晶シャッタの透過光を光硬化性樹脂面に結像する等倍結像素子を経て、前記光硬化性樹脂の液面に照射して、目的立体モデルの断面パターンに対応する薄膜の硬化樹脂層を形成し、この樹脂層を順次積層して立体モデルを形成するようにした光造形装置において、
前記線状光源と前記液晶シャッタとの間に、前記線状光源から発せられる光のうち、前記等倍結像素子を通過できない入射角を有する光成分を遮断する遮光板組立体を装着したことを特徴とする光造形装置。
A liquid crystal shutter composed of a light transmitting portion and a light shielding portion is used to transmit a light beam from a linear light source disposed above the liquid photocurable resin so as to be able to run in the width direction and a light curable resin. Irradiate the liquid surface of the photo-curable resin through a 1: 1 imaging element that forms an image on the surface to form a cured resin layer of a thin film corresponding to the cross-sectional pattern of the target three-dimensional model, and sequentially laminate the resin layers In a stereolithography device that forms a three-dimensional model by
A light- shielding plate assembly is provided between the linear light source and the liquid crystal shutter, the light-shielding plate assembly being configured to block a light component having an incident angle that cannot pass through the same-magnification imaging element, of light emitted from the linear light source. An optical shaping apparatus characterized by the above-mentioned.
JP25107194A 1994-10-17 1994-10-17 Stereolithography Expired - Lifetime JP3578176B2 (en)

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