JP4174288B2 - Two-dimensional scanning device and scanning image display device - Google Patents

Description

【００７８】
ここで、ｚ；Ｚ軸に平行な面のサグ
ｃ；頂点の曲率
ｋ；コーニック係数
Ｃｊ ；ｘｍｙｎの係数
である。
【００７９】
図１５には、本実施形態の２次元走査装置により走査表示される画像（格子）を示している。また、図１６には、該表示画像のＴＶディストーションおよび台形歪みの量を示している。
【００８０】
図１５に示した画像のＴＶディストーションは、枠の上辺Ｌ１が０．１５（％）、下辺Ｌ２が０．１５（％）、左辺Ｌ３が０．２７（％）、右辺Ｌ４が０．０４（％）であり、比較例で湾曲していた上辺Ｌ１および下辺Ｌ２をほぼ直線に補正している。また、台形歪みは、上辺Ｌ１および下辺Ｌ２がともに０．０５（％）であり、左辺Ｌ３および右辺Ｌ４がともに０（％）であって、比較例で傾斜していた線を垂直な線に補正している。
【００８１】
このように、本実施形態によれば、走査光学系５の光軸を偏向走査軸Ｌｄｃから偏心させ、走査光学系を構成する光学素子としての走査レンズ５ａ，５ｂに適切なチルトやシフトを与え、且つ被走査面６をチルトさせることにより、表示画像のＴＶディストーションおよび台形歪みを良好に補正することができる。
【００８２】
具体的には、走査光学系５に含まれる光学素子のうち少なくとも１つの光学素子（第２走査レンズ５ｂ）を偏向走査軸Ｌｄｃに対して最大画角αよりも大きな角度βでチルトさせ、該光学素子の入射面の面頂点での法線を出射側に延ばしたときに、偏向走査軸Ｌｄｃに対して該面法線が延びる側へシフトさせている。さらに、偏向走査軸Ｌｄｃに対して被走査面６を該光学素子と同一方向にチルトさせている。
【００８３】
ここで、ＴＶディストーションの補正メカニズムについて説明する。走査光学系（走査レンズ５ａ，５ｂ）を偏向走査軸Ｌｄｃから偏心させることにより、表示画像のＴＶディストーションは非対称に発生する。走査光学系５の光軸付近ではＴＶディストーションは小さく、走査光学系５の光軸から離れるにしたがってＴＶディストーションは大きくなる。このとき、第２走査レンズ５ｂをチルトさせることにより、走査光学系５の光軸付近には殆ど影響を与えずに、走査光学系５の光軸から離れた位置のＴＶディストーションを補正することができる。
【００８４】
つまり、走査光学系５を偏向走査軸Ｌｄｃから偏心させて配置したことと走査光学系５を構成する光学素子（第２走査レンズ５ｂ）を走査光学系５の光軸に対してチルトさせることにより、ＴＶディストーションを良好に補正（若しくは問題ない程度に小さく）することができる。
【００８５】
これを言い換えると、走査光学系５を偏向走査軸Ｌｄｃからシフトさせることにより、ＴＶディストーションを非対称に発生させ、走査光学系５を構成する光学素子（第２走査レンズ５ｂ）をチルトさせることにより非対称なＴＶディストーションを補正することができる。このとき、いずれの偏向光束が偏向走査軸Ｌｄｃに対してなる角度よりも大きな角度（最大画角αより大きな角度）で光学素子（第２走査レンズ５ｂ）をチルトさせることにより、ＴＶディストーションの補正効果が大きくなる。
【００８６】
次に、台形歪みの補正メカニズムを説明する。走査光学系５（走査レンズ５ａ，５ｂ）を偏向走査軸Ｌｄｃから偏心させたことにより、台形歪みが発生するが、被走査面６をチルトさせることにより、逆向きの台形歪みを発生させることができる。これによって両者をキャンセルさせて台形歪みを補正することができる。
【００８７】
以上により、本実施形態によれば、被走査面６に形成される表示画像に発生するＴＶディストーションおよび台形歪みを良好に補正し、高品位な画像を表示できる２次元走査装置を実現することができる。
【００８８】
なお、本実施形態の２次元走査装置を、プロジェクタとして使用する場合において、被走査面６をチルトさせることによりスクリーン等の被投射面に対して斜め方向から画像を投射することが可能となる。これにより、プロジェクタの後方等から画像を観察する場合に、画像がプロジェクタの陰になってしまうことを避けることができるとともに、プロジェクタの配置自由度も増すというメリットがある。
【００８９】
また、本実施形態では、チルトさせる第２走査レンズ（反射面を有さない透過型光学素子）５ｂを偏向ユニット４側に凹面を向けたメニスカス形状としているが、これにより、第２走査レンズ５ｂのチルトによるＴＶディストーションおよび台形歪みの補正効果を保ったまま、像面湾曲に与える影響を軽減することができる。つまり、ＴＶディストーションや台形歪みを像面湾曲とは切り分けて補正することが可能となり、ＴＶディストーションおよび台形歪みの補正が容易となる。
【００９０】
また、本実施形態の走査光学系５を構成する２つの光学素子の光学面は、全て透過型の屈折面にて構成している。この場合、屈折面に要求される精度は反射面に対して１／４で足りることから、光学素子の製造が容易となるメリットがある。また、反射面を用いる場合、反射面で光路をチルトさせた（折り曲げた）後、該光路を取り回す上での制約が生じるが、透過型の屈折面はそのような影響を受けないので、配置の自由度が大きいというメリットもある。
【００９１】
さらに、画像を表示する光線に対し、反射率と比べて透過率は高いので、光量損失が非常に少ないというメリットもあり、特に光学面数が多い場合にそのメリットが顕著である。また、反射防止膜を付けることにより透過率は非常に高くなる。
【００９２】
また、屈折面と反射面とが混在する光学素子では、光学素子の内部で光路を確保する必要があり、光学素子自体が大型化する。
【００９３】
しかし、光学面を屈折面のみで構成した光学素子を用いる場合、光学素子内で光路を確保する必要のないことから、該光学素子の薄型化が可能であり、２次元走査装置の小型化に有利である。
【００９４】
従って、走査光学系に被走査面に光を向ける反射面を持たない光学素子を用いると、前述した特開平１１−８４２９１や特開２００１−２８１５８３号公報にて提案されているように、反射面を持つ光学部材を用いるに比べて、様々な効果を享受できる。また、本発明においては、屈折面の代わりに、或いは屈折面と組み合わせて光を透過回折する回折面を用いる光学素子も、被走査面における画像の歪みを補正するのに使用できる。
【００９５】
また、本実施形態では、走査光学系５を構成する２つの光学素子をプラスチックレンズとしたが、プラスチックレンズは、射出成形により安価に製造できるとともに、ガラスに比べて軽いというメリットがある。このため、この２次元走査装置を搭載した画像表示装置を軽量化でき、持ち運びに有利となる。なお、屈折面と反射面とが混在する大型の光学素子をプラスチック成形で作った場合には、屈折率分布や複屈折の影響が大きく出るおそれがあるが、本実施形態のように光学素子を小型化（薄型化）した場合にはそのような影響が少ない。
【００９６】
（実施形態２）
図１７には、本発明の実施形態２における２次元走査装置の水平断面を示している。また、図１８には、本実施形態の２次元走査装置の数値実施例（レンズデータ）を示している。以下、これらの図を用いて本実施形態を説明する。本実施形態において、実施形態１と共通する構成要素には実施形態１と同じ符号を付して説明に代える。
【００９７】
本実施形態は、偏向ユニット４に入射する光束を平行光束とした点および走査光学系の構成において実施形態１と異なる。
【００９８】
本実施形態における走査光学系１５は、実施形態１と同様に、水平方向において偏向走査軸Ｌｄｃから偏心して配置されており、水平方向において最大画角αをなす偏向光束Ｂｄｍの中心光線が走査光学系１５の光軸上を通過するように配置されている。
【００９９】
走査光学系１５は、２枚の走査レンズ（第１走査レンズ１５ａ，第２走査レンズ１５ｂ）で構成されている。偏向ユニット４側に配置された第１走査レンズ１５ａにはチルトやシフトが与えられておらず、第１走査レンズ１５ａは走査光学系５の光軸上に入射面および出射面の面頂点が位置するように（つまりは、第１走査レンズ１５ａの光軸が走査光学系５の光軸上に位置するように）配置されている。
【０１００】
一方、被走査面６側に配置された第２走査レンズ１５ｂは、その入射面の面頂点での法線（面法線）が水平方向において最大画角αをなす偏向光束Ｂｄｍに対して、図１７中の反時計回り方向にβ’＝25.0(deg) をなすようにチルトしており、偏向走査軸Ｌｄｃに対しては該面法線がβ＝45.3(deg) をなすようにチルトしている。本実施形態においても、最大画角αは20.3(deg) であるので、第２走査レンズ１５ｂは、偏向走査軸Ｌｄｃに対して、最大画角αよりも大きな角度βでチルトしていることになる。
【０１０１】
さらに、第２走査レンズ１５ｂは、最大画角αをなす偏向光束Ｂｄｍに対して偏向走査軸Ｌｄｃから遠ざかる方向、つまりは第２走査レンズ１５ｂの入射面の面頂点での法線を出射側に延ばしたときに、偏向走査軸Ｌｄｃに対して該法線が傾いて延びる側（図１７中の右側）へ、その入射面の面頂点が該偏向光束Ｂｄｍに対して20.0(mm)離れるようにシフトしている。よって、第２走査レンズ１５ｂは、その入出射面の面頂点が偏向光束の偏向範囲（２次元偏向範囲）の外側に位置するように配置され、第２走査レンズ１５ｂの入出射面はそれぞれの面頂点から片側の部分のみが使用される。
【０１０２】
また、被走査面６も水平断面において最大画角αをなす偏向光束Ｂｄｍに対して、図１７中の反時計回り方向にγ’＝６．８（ｄｅｇ）チルトしている。これは、被走査面６が偏向走査軸Ｌｄｃに対して、第２走査レンズ１５ｂと同一方向へ最大画角αよりも大きな角度γ＝２７．１（ｄｅｇ） チルトしていることになる。
【０１０３】
このように構成される走査光学系１５において、第１走査レンズ１５ａは、球面レンズである。また、第２走査レンズ１５ｂは、入出射面ともアナモルフィック面で構成されたアナモルフィックレンズであり、両面とも水平断面と垂直断面とで異なる非球面量を有する回転非対称非球面である。
【０１０４】
また、第２走査レンズ１５ｂの出射面は、この出射面の面頂点の法線が偏向走査軸Ｌｄｃに対してなす角度が、入射面の面頂点の法線が偏向走査軸Ｌｄｃに対してなす角度よりも8.1(deg)大きくなるように、入射面の面頂点の法線に対してチルトしており、さらに第２走査レンズ１５ｂの出射面の面頂点は、入射面の面頂点に対して偏向走査軸Ｌｄｃから遠ざかる方向へ49.4(mm)シフトしている。
【０１０５】
図１９には、本実施形態の２次元走査装置により走査表示される画像（格子）を示しており、図２０には、該表示画像のＴＶディストーションと台形歪みの量を示している。
【０１０６】
ＴＶディストーションは、画像の枠の上辺Ｌ１で0.16(％)、下辺Ｌ２で0.16(％)、左辺Ｌ３で0.19(％)、右辺Ｌ４で0.11(％)であり、良好に補正されている。また、台形歪みは、画像の枠の上辺Ｌ１・下辺Ｌ２ともに0.11(％)で、左辺Ｌ３・右辺Ｌ４ともに0.0(％)であり、良好に補正されている。
【０１０７】
このように、第２走査レンズ１５ｂを偏向走査軸Ｌｄｃに対して最大画角αよりも大きな角度でチルトさせつつ、第２走査レンズ１５ｂの入射面および出射面のそれぞれのチルト量ならびにシフト量を異ならせることにより、ＴＶディストーションの補正効果を向上させることができる。
【０１０８】
本発明は常に高品位な画像を表示できる２次元走査装置を提供することを目的としている。ＴＶディストーションとは、表示画像の枠の直線性を示す収差量であるが、高品位な画像を表示するためには、表示画像の枠より内側の位置における直線性を良好に補正する必要がある。しかし、一般に画像の位置や方向によって発生する直線性が異なっており、走査光学系をチルトやシフトさせても枠の内側は補正しきれない場合がある。
【０１０９】
そこで、本実施形態では、第２走査レンズ１５ｂの入出射面を回転非対称非球面で構成している。このようにレンズ面を非球面とすることによって、画像内の各位置における直線性を確保できるレンズ面形状とすることができ、回転非対称非球面とすることで、画像内の各方向における直線性を確保できるレンズ面形状とすることができる。このように、チルトした第２走査レンズ１５ｂを回転非対称レンズとすることにより、第２走査レンズ１５ｂ自体のチルトでは補正しきれない画像内の各位置や各方向における直線性を補正することができる。さらには、ＴＶディストーションも効果的に補正することができる。
【０１１０】
また、第２走査レンズ１５ｂは、入射面および出射面がいずれも水平方向と垂直方向とで光学パワーが異なるアナモルフィック面として構成されたアナモルフィックレンズである。これにより、第２走査レンズ１５ｂをチルトさせたときに発生するアスを補正することができる。
【０１１１】
本実施形態では、チルトもしくはシフトさせた第２走査レンズ１５ｂの回転非対称非球面に、(m+n)≦４ までの非球面係数を使用しているが、これに限ったものではなく、より高次(m+n)≧６ の非球面係数を用いることにより、ＴＶディストーションおよび台形歪みの補正をより効果的に行うことが可能となる。
【０１１２】
また、本実施形態のように、チルトならびにシフトさせたレンズを、使用する部分のみを残してそれ以外の部分をカットすることで、２次元走査装置をコンパクト化することができる。
【０１１３】
（実施形態３）
図２１には、本発明の実施形態３である２次元走査装置の水平断面を示している。また、図２２には、本実施形態における２次元走査装置の数値実施例（レンズデータ）を示している。以下、これらの図を用いて本実施形態を説明する。なお、本実施形態において、他の実施形態と共通する構成要素には他の実施形態と同じ符号を付して説明に代える。
【０１１４】
本実施形態は、走査光学系２５を構成する２つの光学素子（２５ａ，２５ｂ）が、最大画角αをなす偏向光束Ｂｄｍに対して、偏向走査軸Ｌｄｃから遠ざかる方向にシフトし、両光学素子のすべての面頂点が偏向光束が偏向される２次元偏向範囲の外に配置されている点で実施形態２と異なる。また、本実施形態では、両光学素子の各光学面のシフト量が互いに異なっている。
【０１１５】
本実施形態においても、実施形態２と同様に、走査光学系２５は２枚のガラスレンズ２５ａ，２５ｂにより構成されており、偏向ユニット４側から第１走査レンズ２５ａ、第２走査レンズ２５ｂとする。
【０１１６】
第１走査レンズ２５ａは、偏向ユニット４側に凹面を向けたメニスカスレンズであり、入出射面ともに球面で構成されている。ここで、本実施形態では、第１走査レンズ２５ａは、その入射面の面頂点が、最大画角αをなす偏向光束Ｂｄｍに対して偏向走査軸Ｌｄｃから遠ざかる方向に、該偏向光束Ｂｄｍから32.1(mm)離れるようにシフトしている。また、第１走査レンズ２５ａの出射面の面頂点は、入射面の面頂点に対して最大画角αをなす偏向光束Ｂｄｍに近づく方向に26.0(mm)シフトしている。
【０１１７】
第２走査レンズ２５ｂは、偏向ユニット４側に凹面を向けたメニスカスレンズであり、入出射面ともに回転対称軸を有さない回転非対称非球面で構成されている。ここで、第２走査レンズ２５ｂは、その入射面の面頂点での法線（面法線）が、最大画角αをなす偏向光束Ｂｄｍに対してβ’＝30(deg) をなすようにチルトしており、偏向走査軸Ｌｄｃに対しては該面法線がβ＝50.3(deg) をなすようにチルトしている。本実施形態においても、実施形態１，２と同様に、水平方向の最大画角αは20.3deg であり、第２走査レンズ２５ｂの偏向走査軸Ｌｄｃに対するチルト量（β）は、最大画角αよりも大きくなっている。
【０１１８】
また、第２走査レンズ２５ｂは、その入射面の面頂点の法線を出射側に延ばしたときに、偏向走査軸Ｌｄｃに対して該面法線が傾いている側、つまり最大画角αをなす偏向光束Ｂｄｍに対して偏向走査軸Ｌｄｃから遠ざかる方向（図２１中の右側）に、その入射面の面頂点が該偏向光束Ｂｄｍから13.4(mm)離れるようにシフトしており、さらに第２走査レンズ２５ｂの出射面の面頂点は、入射面の面頂点に対して偏向走査軸Ｌｄｃから遠ざかる方向に135.7(mm) シフトしている。
【０１１９】
よって、走査光学系２５に含まれる全ての光学素子（走査レンズ２５ａ，２５ｂ）の全ての光学面（入出射面）は、偏向光束が偏向される２次元偏向範囲の外側に配置され、全ての光学素子における光軸に対して片側の部分のみが使用される。このような構成によって、ＴＶディストーションをより良好に補正することが可能となる。
【０１２０】
このとき、第２走査レンズ２５ｂの入射面および出射面における偏向光束の通過領域（偏向光束の導光に使用される部分）の全域における法線は、偏向走査軸Ｌｄｃに対して最大画角αよりも大きな角度で傾いている。これにより、ＴＶディストーションをより効果的に補正することができる。
【０１２１】
また、被走査面６も水平断面において最大画角αをなす偏向光束Ｂｄｍに対して、図２１中の反時計回り方向にγ’＝５．０（ｄｅｇ）チルトしている。これは、被走査面６が偏向走査軸Ｌｄｃに対して、第２走査レンズ２５ｂと同一方向へ最大画角αよりも大きな角度γ＝２５．３（ｄｅｇ） チルトしていることになる。
【０１２２】
図２３には、本実施形態の２次元走査装置により走査表示される画像（格子）を示しており、図２４には、該表示画像のＴＶディストーションと台形歪みの量を示している。
【０１２３】
ＴＶディストーションは、画像の枠の上辺Ｌ１で0.04(％)、下辺Ｌ２で0.04(％)、左辺Ｌ３で0.06(％)、右辺Ｌ４で0.11(％)であり、きわめて良好に補正されている。また、台形歪みは、画像の枠の上辺Ｌ１・下辺Ｌ２ともに0.01(％)、左辺Ｌ３・右辺Ｌ４ともに0.00(％)であり、ほとんど台形歪みがなくなるように補正されている。
【０１２４】
このように、走査光学系に含まれる光学素子のうち２つ以上の光学素子を偏向光束が偏向される２次元偏向範囲外に配置することにより、ＴＶディストーションおよび台形歪みを補正する効果が大きくなる。よって、きわめて高品位な２次元画像を表示することが可能な２次元走査装置を実現することができる。
【０１２５】
なお、本実施形態では、第１走査レンズ２５ａを球面レンズとしたが、アナモルフィックレンズや回転非対称非球面レンズとすることで、ＴＶディストーションの補正効果をさらに高めることができる。また、光源１に互いに異なる波長（色光）を発する複数の光源を用いた場合には、回折格子を備えたレンズを用いることで色消しを行うことも可能である。
【０１２６】
（実施形態４）
図２５には、本発明の実施形態４である２次元走査装置の水平断面を示している。また、図２６には、本実施形態における２次元走査装置の数値実施例（レンズデータ）を示している。以下、これらの図を用いて本実施形態を説明する。なお、本実施形態において、他の実施形態と共通する構成要素には他の実施形態と同じ符号を付して説明に代える。
【０１２７】
本実施形態は、走査光学系３５を構成する２つの光学素子（３５ａ，３５ｂ）が偏向走査軸Ｌｄｃに対して最大画角αよりも大きな角度でチルトしている点で実施形態３と異なる。また、本実施形態では、各光学素子のレンズ面のチルト量も互いに異なっている。
【０１２８】
本実施形態でも、実施形態２と同様に、走査光学系３５は２枚のガラスレンズ３５ａ，３５ｂで構成されており、偏向ユニット４側から第１走査レンズ３５ａ、第２走査レンズ３５ｂとする。
【０１２９】
第１走査レンズ３５ａは、偏向ユニット４側に凹面を向けたメニスカスレンズであり、入出射面とも回転対称軸を有さない回転非対称非球面で構成されている。ここで、第１走査レンズ３５ａは、その入射面の面頂点が、最大画角αをなす偏向光束Ｂｄｍに対して偏向走査軸Ｌｄｃから遠ざかる方向（入射面の面頂点における法線を出射側に延ばしたときに、偏向走査軸Ｌｄｃに対して該法線が延びる側）に、該偏向光束Ｂｄｍから27.2(mm)離れるようにシフトしている。また、第１走査レンズ３５ａの出射面の面頂点は、入射面の面頂点に対して、最大画角αをなす偏向光束Ｂｄｍに近づく方向へ34.2(mm)シフトしている。
【０１３０】
さらに、第１走査レンズ３５ａは、その入射面の面頂点での法線（面法線）が、最大画角αをなす偏向光束Ｂｄｍに対してβ１’＝7.5(deg) をなすようにチルトしており、偏向走査軸Ｌｄｃに対しては該面法線がβ１＝27.8(deg)をなすようにチルトしている。また、第１走査レンズ３５ａの出射面は、その面法線が入射面の面法線に対して -9.3(deg)の角度をなすようにチルトしている。
【０１３１】
第２走査レンズ３５ｂは、偏向ユニット４側に凹面を向けたメニスカスレンズであり、入出射面ともに回転対称軸を有さない回転非対称非球面である。ここで、第２走査レンズ３５ｂは、その入射面の面頂点での法線（面法線）が、最大画角αをなす偏向光束Ｂｄｍに対してβ２’＝28.2(deg)をなすようにチルトしており、偏向走査軸Ｌｄｃに対しては該面法線がβ２＝48.5(deg)をなすようにチルトしている。本実施形態においても、実施形態１〜３と同様に、水平方向の最大画角αは20.3 (deg)であり、第１走査レンズ３５ａ、第２走査レンズ３５ｂとも偏向走査軸Ｌｄｃに対するチルト量（β１，β２）は最大画角αよりも大きい。
【０１３２】
また、第２走査レンズ３５ｂは、その入射面の面頂点が、最大画角αをなす偏向光束Ｂｄｍに対して偏向走査軸Ｌｄｃから遠ざかる方向（入射面の面頂点における法線を出射側に延ばしたときに、偏向走査軸Ｌｄｃに対して該法線が延びる側）に、該偏向光束Ｂｄｍから11.3(mm)離れるようにシフトしている。また、第２走査レンズ３５ｂの出射面の面頂点は、入射面の面頂点に対して偏向走査軸Ｌｄｃから遠ざかる方向に108.4(mm) シフトしている。
【０１３３】
このように、本実施形態では、走査光学系３５に含まれる２つの光学素子（３５ａ，３５ｂ）を偏向走査軸Ｌｄｃに対して最大画角αよりも大きな角度でチルトさせている。また、各光学素子の光学面のシフト量ならびにチルト量を互いに異ならせている。特に、偏向走査軸Ｌｄｃに対して最大画角αよりも大きな角度でチルトしている第２走査レンズ３５ｂの出射面に関し、そのチルト量を入射面のチルト量よりも大きくし、シフト量も入射面のシフト量よりも大きくしている。
【０１３４】
これらの構成の１つ１つには、ＴＶディストーションを良好に補正する効果があり、これらを１つにまとめた構成を採ることにより、ＴＶディストーションをきわめて良好に補正することが可能となる。
【０１３５】
図２７には、本実施形態の２次元走査装置により走査表示される画像（格子）を示しており、図２８には、該表示画像のＴＶディストーションと台形歪みの量を示している。
【０１３６】
ＴＶディストーションは、画像の枠の上辺Ｌ１で0.06(％)、下辺Ｌ２で0.06(％)、左辺Ｌ３で0.07(％)、右辺Ｌ４で0.06(％)であり、きわめて良好に補正されている。また、台形歪みは、画像の枠の上辺Ｌ１・下辺Ｌ２とも0.01(％)、左辺Ｌ３・右辺Ｌ４とも0.00(％)であり、ほとんど台形歪みがなくなるように補正されている。
【０１３７】
このように、走査光学系に含まれる光学素子のうち２つ以上の光学素子を、偏向走査軸に対して最大画角よりも大きな角度でチルトさせることにより、ＴＶディストーションおよび台形歪みの補正効果を向上させることができる。また、各光学素子の光学面ごとにチルト量やシフト量を異ならせることにより、ＴＶディストーションや台形歪みの補正効果をさらに高めることができる。したがって、きわめて高品位な２次元画像を表示することが可能な２次元走査装置を実現することができる。
【０１３８】
なお、本実施形態では、チルトおよびシフトさせる光学素子を２つとしたが、本発明はこれに限られず、例えば３つ以上の光学素子をチルトさせたりシフトさせたりしても同様の効果を得ることができる。
【０１３９】
（実施形態５）
図２９には、本発明の実施形態５である２次元走査装置の水平断面を示している。また、図３０には、本実施形態における２次元走査装置の数値実施例（レンズデータ）を示している。以下、これらの図を用いて本実施形態を説明する。なお、本実施形態において、他の実施形態と共通する構成要素には他の実施形態と同じ符号を付して説明に代える。
【０１４０】
本実施形態は、走査光学系４５を１つの光学素子（４５ａ）で構成した点で他の実施形態と異なる。
【０１４１】
本実施形態における走査光学系４５は、ガラスモールドで成形された１枚の走査レンズ４５ａにより構成されている。走査レンズ４５ａは、偏向走査軸Ｌｄｃに対して偏心して配置されている。走査レンズ４５ａは、その入射面の面頂点での法線（面法線）が、最大画角αをなす偏向光束Ｂｄｍに対して図２９中の反時計回り方向にβ１’＝25.0(deg)をなすようにチルトしており、偏向走査軸Ｌｄｃに対しては該面法線が反時計回りにβ１＝45.3(deg)をなすようにチルトしている。
【０１４２】
さらに、走査レンズ４５ａの出射面は、その面頂点の法線（面法線）が入射面の面法線に対して反時計回り方向にβ２’＝11.0(deg) をなすようにチルトしており、偏向走査軸Ｌｄｃに対しては射出面の面法線が反時計回り方向にβ２＝56.3(deg)をなすようにチルトしている。本実施形態においても、実施形態１〜４と同様に、水平方向の最大画角αは偏向走査軸Ｌｄｃを基準として±20.3deg であり、走査レンズ４５ａは、偏向走査軸Ｌｄｃに対して最大画角αよりも大きなチルト量を有している。このことは走査レンズ４５ａの入出射面とも同様である。
【０１４３】
また、走査レンズ４５ａは、入射面の面法線を出射側に延ばしたときに、偏向走査軸Ｌｄｃに対して該面法線が傾いて延びる側、つまり最大画角αをなす偏向光束Ｂｄｍに対して偏向走査軸Ｌｄｃから遠ざかる方向に、その入射面の面頂点が該偏向光束Ｂｄｍから１２．９（ｍｍ）離れるようにシフトしている。さらに、出射面の面頂点は、入射面の面頂点に対して偏向走査軸Ｌｄｃから遠ざかる方向へ５５．４（ｍｍ）シフトしている。これにより、走査レンズ４５ａの入出射面（すべての光学面）の面頂点は、偏向光束が偏向される２次元偏向範囲の外側に配置されていることになる。
【０１４４】
また、被走査面６も最大画角αをなす偏向光束Ｂｄｍに対して図２９中の反時計回り方向にγ’＝8.4(deg) チルトしており、偏向走査軸Ｌｄｃに対しては、最大画角αより大きいγ＝28.7(deg) チルトしている。なお、被走査面６のチルト方向は、偏向走査軸Ｌｄｃに対する走査レンズ４５ａのチルト方向と同じである。
【０１４５】
このように、本実施形態では、走査光学系４５を１枚の走査レンズ４５ａのみで構成しているので、部品点数を削減することができ、コストダウンや製造の容易化を図ることができる。
【０１４６】
また、本実施形態では、走査レンズ４５ａは、その入出射面をアナモルフィック面で構成したアナモルフィックレンズとしており、さらに入出射面は水平断面と垂直断面とで異なる非球面量を有する回転非対称非球面で構成している。
【０１４７】
図３１には、本実施形態の２次元走査装置により走査表示される画像（格子）を示し、図３２には該表示画像のＴＶディストーションと台形歪みの量を示している。
【０１４８】
ＴＶディストーションは、画像の上辺Ｌ１で0.17(％)、下辺Ｌ２で0.17(％)、左辺Ｌ３で0.13(％)、右辺Ｌ４で0.20(％)であり、十分に補正されている。また、台形歪みは、上辺Ｌ１・下辺Ｌ２ともに0.10(％)、左辺Ｌ３・右辺Ｌ４とも0.00(％)であり、良好に補正されている。
【０１４９】
このように、走査光学系４５を１つの光学素子（４５ａ）によって構成した場合においても、光学素子を偏向走査軸Ｌｄｃに対して最大画角αよりも大きな角度でチルトさせ、入射面の面頂点での法線を出射側に延ばしたときに、偏向走査軸Ｌｄｃに対して該法線が延びる側へ光学素子をシフトさせ、かつ被走査面を偏向走査軸Ｌｄｃに対して光学素子と同じ方向へチルトさせることによって、ＴＶディストーションを良好に補正することができる。
【０１５０】
さらに、チルトする光学素子に回転非対称非球面を用いたり、偏向光束が偏向される２次元偏向範囲外に光学素子の面頂点を配置したり、光学素子の各光学面のチルト量やシフト量を互いに異ならせたりすることにより、ＴＶディストーションおよび台形歪みの補正効果を格段に向上させることができる。
【０１５１】
なお、上記各実施形態では、走査光学系を構成する光学素子としてガラスレンズを用いた場合について説明したが、ガラスレンズ以外の光学素子、例えば射出成型により作られたプラスチックレンズを用いることにより、製造が容易になり、コストダウンが図れると共に、２次元走査装置の軽量化を図ることができる。
【０１５２】
また、光源に青、緑、赤の３色の発光部を備えることにより、２次元カラー画像を表示させることもできる。この場合、回折格子を備えた光学素子を用いて色消しを行えばよい。これにより、高品位のカラー画像を走査表示できる走査型画像表示装置を実現することができる。この場合、例えば、青、緑、赤の３色の光を順次（フィールドシーケンシャルに）又は同時に偏向ユニットに向けるようにすればよい。これ以外にも、白色の光源と青、緑、赤の３色のフィルタを回転可能なターレット上に配置したものとを組み合わせて、青、緑、赤の３色の光を順次、偏向ユニットに向けるようにすることができる。
【０１５３】
このように光源から青、緑、赤の３色の光を偏向ユニットへ向けつつ、偏向ユニットと走査光学系を使ってカラーの２次元画像を形成する際の光源や偏向ユニットの制御方法についての説明は省略する。
【０１５４】
また、上記各実施形態では、偏向ユニットとして、１次元方向に共振揺動が可能なＭＥＭＳデバイスを用いた偏向器を２つ備えた場合について説明したが、図３３に示すようなＭＥＭＳデバイスを１つ用いてもよい。このＭＥＭＳデバイスを用いた偏向器は、反射面５４ａをトーションバー５４ｂを介して振動枠５４ｃに支持させ、さらにこの振動枠５４ｃをトーションバー５４ｂに直交する方向に延びるトーションバー５４ｄを介して筐体５４ｅに支持させることにより、反射面５４ａをトーションバー５４ｂ，５４ｄ（偏向軸）を中心として、２次元方向に共振揺動させる。
【０１５５】
また、ＭＥＭＳデバイスを用いた偏向器に代えて、反射面が回転運動するガルバノミラーやポリゴンミラーを用いてもよい。
【０１５６】
また、前述した特開平８−１４６３２０号公報にて提案されているように、電気的にＴＶディストーションを補正する技術もあるが、この種の電気的な補正と本発明における走査光学系による光学的な補正とを組み合わせて画像の歪みを補正する構成を採ることも可能である。
【０１５７】
ＴＶディストーションを電気的に補正する場合、偏向手段を制御する駆動回路（不図示）により２次元走査の際の反射面の傾斜角度を、光学的補正後の残存ディストーションを補正するように制御する。
【０１５８】
（第６実施形態）
図３４には、本実施形態の２次元走査装置を備えた走査型画像表示装置の例を示している。図３４（Ａ）には、壁面等に設けられたスクリーン１０５に画像を表示するプロジェクタ１００を示しており、筐体１０１内に本実施形態の２次元走査装置１０２が収納されている。
【０１５９】
また、図３４（Ｂ）には、パーソナルコンピュータのディスプレイの代わり等として、机面上に画像を表示するスタンド型のプロジェクタ１１０を示しており、机面の上方に支持された雲台１１１内に本実施形態の２次元走査装置１１２が収納されている。
【０１６０】
いずれのプロジェクタ１００，１１０にも、パーソナルコンピュータ、ビデオ、ＤＶＤプレーヤー等の画像情報供給装置１５０が接続され、画像表示システムが構成されている。プロジェクタ１００，１１０内には、画像情報供給装置１５０から入力された画像情報に基づいて光源１から発せられる単色光又は複数色光を変調する駆動回路が設けられている。これにより、プロジェクタ１００，１１０は、画像情報供給装置１５０から供給された画像情報に応じた画像をスクリーン１０５上や机面１１５上に走査表示することができる。
【０１６１】
以上説明した各実施形態は、被走査面上にスクリーン等があり、その画像を直接観察する形態の画像表示装置（例えば、プロジェクター）を例にとって説明したが、例えば被走査面に形成した画像をリレー光学系等を介して観察する形態の画像表示装置（例えば、ファインダー）にも、本発明は適用できる。
【０１６２】
さらに、本発明は、偏向手段の反射面に、光源からの光束が該反射面の揺動軸（偏向軸）に対して斜め方向から入射する場合にも、適用することができる。
【０１６３】
【発明の効果】
以上説明したように、本発明によれば、光束を２次元方向に偏向走査して２次元画像を形成する場合に生じるＴＶディストーションや台形歪みを含むディストーションを容易かつ良好に補正することができる。これにより、歪みが少ない高品位な画像を表示することが可能な２次元走査装置および走査型画像表示装置を実現することができる。
【図面の簡単な説明】
【図１】本発明の実施形態１である２次元走査装置の斜視図。
【図２】上記実施形態１の２次元走査装置の要部概要図。
【図３】２次元走査装置で用いられる１次元偏向器の要部概要図。
【図４】本発明の比較例１である２次元走査装置の水平断面図。
【図５】上記比較例１の２次元走査装置の数値例を示す表図。
【図６】ＴＶディストーションおよび台形歪みを説明する図
【図７】上記比較例１における表示画像（格子）の説明図。
【図８】上記比較例１におけるＴＶディストーションと台形歪みの量を示す表図。
【図９】本発明の比較例２である２次元走査装置の水平断面図。
【図１０】上記比較例２における表示画像（格子）の説明図。
【図１１】上記比較例２におけるＴＶディストーションと台形歪みの量を示す表図。
【図１２】上記実施形態１の２次元走査装置の水平断面図。
【図１３】上記実施形態１の２次元走査装置の要部拡大図。
【図１４】上記実施形態１の２次元走査装置の数値実施例を示す表図。
【図１５】上記実施形態１における表示画像（格子）の説明図。
【図１６】上記実施形態１におけるＴＶディストーションと台形歪みの量を示す表図。
【図１７】本発明の実施形態２である２次元走査装置の水平断面図。
【図１８】上記実施形態２の２次元走査装置の数値実施例を示す表図。
【図１９】上記実施形態２における表示画像（格子）の説明図。
【図２０】上記実施形態２におけるＴＶディストーションと台形歪みの量を示す表図。
【図２１】本発明の実施形態３である２次元走査装置の水平断面図。
【図２２】上記実施形態３の２次元走査装置の数値実施例を示す表図。
【図２３】上記実施形態３における表示画像（格子）の説明図。
【図２４】上記実施形態３におけるＴＶディストーションと台形歪みの量を示す表図。
【図２５】本発明の実施形態４である２次元走査装置の水平断面図。
【図２６】上記実施形態４の２次元走査装置の数値実施例を示す表図。
【図２７】上記実施形態４における表示画像（格子）の説明図。
【図２８】上記実施形態４におけるＴＶディストーションと台形歪みの量を示す表図。
【図２９】本発明の実施形態５である２次元走査装置の水平断面図。
【図３０】上記実施形態５の２次元走査装置の数値実施例を示す表図。
【図３１】上記実施形態５における表示画像（格子）の説明図。
【図３２】上記実施形態５におけるＴＶディストーションと台形歪みの量を示す表図。
【図３３】２次元走査装置で用いられる２次元偏向器の要部概要図。
【図３４】上記各実施形態の２次元走査装置を備えたプロジェクタを示す概略図。
【符号の説明】
１ 光源
２ 集光レンズ
３ 開口絞り
４ 偏向ユニット
５，１５，２５，３５，４５ 走査光学系
６ 被走査面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-dimensional scanning device used in a scanning image display device that displays a two-dimensional image by scanning light in a two-dimensional direction.
[0002]
[Prior art]
Various two-dimensional scanning devices that scan a light spot in a two-dimensional direction and form a two-dimensional image by the afterimage effect have been proposed.
[0003]
By the way, it is generally known that a so-called distortion is generated in a two-dimensional image on a surface to be scanned by deflecting and scanning the light beam two-dimensionally. Distortion includes trapezoidal distortion, constant-speed scanning distortion, straight-scanning distortion, and TV distortion that refers to the curvature of an image frame drawn on the surface to be scanned.
[0004]
In Patent Document 1, a light beam emitted from a light source is deflected in a two-dimensional direction by a deflecting unit, and a light spot is scanned in a two-dimensional direction through a scanning lens having f · sin θ characteristics as distortion characteristics to form an image. A scanning device has been proposed.
[0005]
This is because TV distortion, which is image distortion that occurs when an image is formed by two-dimensional scanning of light, can be corrected by the f · sin θ characteristic of the scanning lens and electrical correction. .
[0006]
Further, in Patent Documents 2 and 3, a two-dimensional scanning device using an optical element including a refracting surface and a reflecting surface and turning back an optical path inside the optical element, and refracting to correct decentration aberrations. There has been proposed a structure in which a surface or a reflection surface is composed of a rotationally asymmetric surface that does not have a rotational symmetry axis both outside and inside the surface.
[0007]
Although this is a two-dimensional scanning device configured using one optical element, the constant velocity of the scanning light on the surface to be scanned is well corrected over a wide scanning angle. It is also possible to achieve telecentricity necessary for high-precision drawing.
[0008]
[Patent Document 1]
JP-A-8-146320
[Patent Document 2]
JP 11-84291 A
[Patent Document 3]
Japanese Patent Laid-Open No. 2000-28183
[0009]
[Problems to be solved by the invention]
However, in the two-dimensional scanning apparatus proposed in Patent Document 1, the TV distortion is corrected by the f · sin θ characteristic of the scanning lens and the electrical correction, but the TV distortion is actually corrected electrically. It is difficult to do.
[0010]
Further, the two-dimensional scanning device proposed in Patent Documents 2 and 3 does not correct TV distortion in the first place. In addition, a reflection surface having optical power is provided in the optical element constituting the two-dimensional scanning device, and the surface accuracy is very strict, so that it is difficult to stably correct TV distortion. In addition, since it is necessary to secure a folded optical path inside the optical element, the thickness of the optical element tends to increase. Furthermore, when the optical element is made of plastic, it is greatly affected by the distribution of internal refractive index and birefringence.
[0011]
Therefore, an object of the present invention is to provide a two-dimensional scanning apparatus that can easily and satisfactorily correct distortion including TV distortion and trapezoidal distortion.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a two-dimensional scanning device of the present invention includes a deflecting unit that deflects a light beam from a light source in a two-dimensional direction, and a light beam deflected by the deflecting unit is directed toward a surface to be scanned. From one or two lenses Scanning light system, and the light beam from the light source Orthogonal A scanning optical system that enters at least one of the deflection axes from an oblique direction. 1 lens or a lens on the side closer to the scanning surface among the 2 or less lenses The deflection means Immediately after reflecting An incident surface tilted so as to make an angle larger than the maximum field angle of the two-dimensional deflection range with respect to the central axis of the two-dimensional deflection range of the light beam, and an angle larger than the incident surface with respect to the central axis With tilted exit surface And Of the entrance and exit surfaces , Which is the center of each face The normal at the surface vertex One lens or near the surface to be scanned When extended to the exit side of the lens, it shifts to the side where the normal extends with respect to the central axis. The scanned surface is tilted in the same direction as the incident surface and the exit surface are tilted. It is characterized by being.
[0014]
Also, the tilted direction of the entrance surface and the exit surface is , the above Same as one of two orthogonal deflection axes You may do it.
[0019]
Also, above Entrance surface and exit surface In order to guide the light beam deflected by the deflecting means to the surface to be scanned. Entrance surface and exit surface Only the part on one side from the coordinate center (surface vertex) of may be used.
[0024]
Also, above Entrance surface and exit surface May be an anamorphic surface.
[0025]
Also, above Entrance surface and exit surface May be a rotationally asymmetric surface.
[0026]
Also, above lens May be a meniscus lens having a concave surface facing the deflecting means.
[0032]
Also, above Each of the two orthogonal deflection axes The angle of view in the direction is Different You may do it.
[0034]
Further, the light beam incident on the deflecting unit may be a convergent light beam.
[0035]
Further, the distortion on the scanned surface is scanning Optically corrected by the optical system or above scanning You may make it correct | amend by the combination of the optical correction by an optical system, and the electrical correction by the circuit which controls a deflection | deviation means.
[0036]
A scanning image display device such as an electronic viewfinder provided in a projector, a video camera, a digital still camera, or the like can be configured using the above two-dimensional scanning device.
[0037]
In this case, a color image may be formed on the surface to be scanned by causing a plurality of light beams having different wavelengths from the light source to enter the deflecting unit.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 shows the overall configuration of a two-dimensional scanning apparatus that is Embodiment 1 of the present invention. FIG. 2 is an enlarged view of the two-dimensional scanning device. The present embodiment and each embodiment described later are examples when the apparatus is used in an image display apparatus such as a projector.
[0039]
In these figures, reference numeral 1 denotes a laser diode, LED, lamp, and the like, and a drive circuit (not shown) that operates in accordance with an image signal input from an image information supply device such as a personal computer, a video, or a DVD player described later. It is a light source whose emission is controlled. The divergent light beam emitted from the light source 1 is converted into a convergent light beam by the condensing lens 2 in which the two condensing lenses 2 a and 2 b are bonded together, and the light beam width is limited by the aperture stop 3.
[0040]
Reference numeral 4 denotes a polarization unit, and in this embodiment, includes two deflectors (a first deflector 4a and a second deflector 4b) having a reflecting surface that can swing in a one-dimensional direction. The two reflecting surfaces of these deflectors 4a and 4b can swing around two axes orthogonal to each other. The deflectors 4a and 4b are configured using, for example, a MEMS (Micro-Electro-Mechanical Systems) device. As will be described later, the deflectors 4a and 4b using the MEMS device can oscillate the reflecting surface by the resonance motion. In addition, the MEMS device is manufactured by, for example, a MEMS technique using a semiconductor manufacturing technique or the like, and has an advantage that it can be reduced in size and weight.
[0041]
The light beam emitted from the light source 1 is deflected in the horizontal direction by the first deflector 4a, and the light beam deflected by the first deflector 4a is deflected in the vertical direction by the second deflector 4b. Thus, the light beam emitted from the light source 1 is deflected in a two-dimensional direction by the deflection unit 4.
[0042]
Reference numeral 5 denotes a scanning optical system having fθ characteristics. The scanning optical system 5 has two aspherical lenses 5 a and 5 b, guides the light beam (deflected light beam) deflected in the two-dimensional direction by the deflection unit 4 to the scanned surface 6, and also scans the scanned surface 6. To form an image as a spot. This imaging spot is the first deflection vessel Second deflection in the horizontal direction by 4a vessel By scanning in the vertical direction by 4b, a two-dimensional image using the afterimage effect of light is formed on the scanned surface 6.
[0043]
Here, FIG. A ) Shows a schematic configuration of the first deflector 4a as the MEMS device. FIG. A ), The reflecting surface 4c is supported by the housing 4e by the torsion bar 4d, and the magnet provided on the back surface of the reflecting surface 4c reacts to the magnetic force generated from the coil (not shown) to respond to the torsion bar 4d (deflection shaft). Resonantly oscillates (oscillates) in a one-dimensional direction around the center. The direction of the first deflector 4a is set so that the light beam incident and reflected on the oscillating reflecting surface 4c is deflected in the horizontal direction (X direction).
[0044]
FIG. B ) Shows a schematic configuration of the second deflector 4b as the MEMS device. FIG. B ), The reflection surface 4c ′ is supported by the casing 4e ′ by the torsion bar 4d ′, and the magnet provided on the back surface of the reflection surface 4c ′ reacts to the magnetic force generated from the coil (not shown) to generate the torsion bar 4d. Resonant vibration (oscillates) in a one-dimensional direction around '(deflection axis). The direction of the second deflector 4b is set so that the light beam incident and reflected on the vibrating reflecting surface 4c ′ is deflected in the vertical direction (Y direction).
[0045]
The first polarizer 4a and the second deflector 4b constitute a deflection unit 4 that can deflect the light beam from the light source 1 in two dimensions around two deflection axes. In the present embodiment, the interval between the first deflector 4a and the second deflector 4b is set to 3.0 (mm).
[0046]
FIG. 4 shows a two-dimensional scanning apparatus as Comparative Example 1 used for comparison with the present embodiment. Horizontal A cross section (XZ cross section) is shown.
[0047]
In Comparative Example 1, as in the present embodiment, the divergent light beam emitted from the light source 1 is converted into a convergent light beam by the condenser lens 2, the light beam width is limited by the aperture stop 3, and the deflection unit 4 horizontally and vertically It is deflected in a two-dimensional direction. In Comparative Example 1, a scanning optical system 5 ′ having an fθ characteristic is provided. The scanning optical system 5 ′ includes two plastic asymmetric aspherical lenses 5a ′ and 5b ′ that do not have a rotationally symmetric axis, and scans a light beam deflected by the deflection unit 4 (a deflected light beam). An image is formed as a spot on the surface 6. At this time, the deflection unit 4 is deflected in the horizontal and vertical directions, so that the deflected light beam is scanned on the scanned surface 6 via the scanning optical system 5 ′.
[0048]
Here, a range in which the light beam is deflected in the two-dimensional direction by the deflection unit 4 is referred to as a two-dimensional deflection range, and an axis (center axis) positioned at the center in the horizontal direction and the vertical direction in the two-dimensional deflection range is implemented in this embodiment. In the form, it is called a deflection scanning axis Ldc. FIG. 5 shows a numerical example (lens data) of the two-dimensional scanning device in Comparative Example 1.
[0049]
In the first comparative example shown in FIG. 4, the deflection scanning axis Ldc and the optical axis of the scanning optical system 5 ′ are coincident. The two scanning lenses (the first scanning lens 5a and the second scanning lens 5b) constituting the scanning optical system 5 ′ are not tilted or shifted with respect to the deflection scanning axis Ldc, and are all surfaces. The vertex is arranged on the optical axis (deflection scanning axis Ldc). Further, the tilted light beam that has passed through the optical axis of the scanning optical system 5 ′ is incident on the scanned surface 6 perpendicularly without tilting the scanned surface 6.
[0050]
At this time, in the image drawn on the scanned surface 6, TV distortion resulting from the deflection in the two-dimensional direction by the deflection unit 4 occurs.
[0051]
A method for calculating TV distortion and trapezoidal distortion will be described with reference to FIGS.
[0052]
FIG. 6A is a diagram illustrating a method for calculating TV distortion. TV distortion is an amount of aberration that indicates the amount of curvature of the frame of the displayed image (screen), and is along an axis (horizontal axis, vertical axis) passing through the center of the image indicated by a dashed line in the figure. Displacement The amount is divided by the width of the image (horizontal width A, vertical width B). Therefore, the TV distortion at each side of the image frame is expressed by the following equation.
[0053]
Upper side L1; a / B × 100 (%)
Lower side L2; b / B × 100 (%)
Left side L3; c / A × 100 (%)
Right side L4; d / A × 100 (%)
FIG. 6B is a diagram for explaining a method for calculating the trapezoidal distortion. Trapezoidal distortion is the amount of aberration that indicates the amount by which the frame of the displayed image is tilted. Displacement The amount divided by the width of the image. Therefore, the trapezoidal distortion at each side of the image frame is expressed by the following equation.
[0054]
Upper side L1; e / 2 / B × 100 (%)
Lower side L2; f / 2 / B × 100 (%)
Left side L3; g / 2 / A × 100 (%)
Right side L4; h / 2 / A × 100 (%)
FIG. 7 shows an image (lattice) scanned and displayed by the two-dimensional scanning device of Comparative Example 1. FIG. 8 shows the amount of TV distortion and trapezoidal distortion in the display image.
[0055]
As shown in FIG. 7, the four lines (sides) constituting the frame of the image should ideally all be straight lines, but the upper side L1 and the lower side L2 of the frame are substantially straight lines. It can be seen that the central portions of the left side L3 and the right side L4 are curves that are recessed toward the center of the image, and that a large amount of TV distortion occurs. At this time, the TV distortion was 0.12 (%) on the upper side, 0.12 (%) on the lower side, 1.53 (%) on the left side, and 1.53 (%) on the right side (see FIG. 8). In Comparative Example 1, since the scanning optical system 5 ′ is arranged symmetrically with respect to the deflection scanning axis Ldc, trapezoidal distortion does not occur.
[0056]
As described above, in a general optical arrangement in which the optical axis of the scanning optical system 5 ′ is overlapped with the deflection scanning axis Ldc, TV distortion due to deflection scanning in the two-dimensional direction is greatly generated. Then, the occurrence of TV distortion distorts the image and degrades the quality of the display image.
[0057]
FIG. 9 shows the two-dimensional scanning device in Comparative Example 2. Horizontal A cross section (XZ cross section) is shown. In Comparative Example 2, the scanning optical system 5 ″ is composed of two scanning lenses (a first scanning lens 5a ″ and a second scanning lens 5b ″), and each scanning lens 5a ″, 5b ″ is a scanning optical system. It is arranged on the 5 ″ optical axis. Scanning optical system 5 ″ Horizontal In the cross section, it is decentered with respect to the deflection scanning axis Ldc.
[0058]
In particular, Horizontal The orientation and position of the deflection unit 4 are set so that the deflected light beam Bdm having the maximum field angle (the largest deflection angle with respect to the deflection scanning axis Ldc) at the end in the cross section passes through the optical axis of the scanning optical system 5 ″. Thus, the maximum angle of view and the tilt amount of each scanning lens 5a ″, 5b ″ are made to coincide.
[0059]
Thus, on the optical axis of each scanning lens 5a ", 5b" Horizontal Because the deflected light beam at the end of the cross section passes, Horizontal In the cross section, only one part of the scanning lenses 5a "and 5b" from the optical axis is used, and the scanning lenses 5a "and 5b" are used asymmetrically with respect to the optical axis.
[0060]
FIG. 10 shows an image (lattice) scanned and displayed by the two-dimensional scanning device of Comparative Example 2. FIG. 11 shows the amount of TV distortion and trapezoidal distortion in the display image.
[0061]
In Comparative Example 2, as shown in FIG. 10, TV distortion occurs asymmetrically in the left-right direction (horizontal direction). That is, on the left side where the deflected light beam passes near the optical axis of the scanning lens 5a ″, 5b ″, the amount of TV distortion is small, and the right side where the deflected light beam passes through a position away from the optical axis of the scanning lens 5a ″, 5b ″. Then, the amount of TV distortion generated is large.
[0062]
As shown in FIG. 11, the TV distortion was 0.90 (%) on the upper side, 0.90 (%) on the lower side, 0.00 (%) on the left side, and 1.70 (%) on the right side (see FIG. 11). The trapezoidal distortion was 1.02 (%) on the upper side, 1.02 (%) on the lower side, 0.00 (%) on the left side, and 0.00 (%) on the right side (see FIG. 11).
[0063]
Also in the comparative example 2, TV distortion and trapezoidal distortion are greatly generated, and the quality of the display image is deteriorated.
[0064]
Therefore, in the present embodiment, the arrangement of the scanning optical system 5 and the surface to be scanned 6 is devised to correct TV distortion and trapezoidal distortion.
[0065]
FIG. 12 shows the two-dimensional scanning apparatus according to Embodiment 1 of the present invention. Horizontal A cross section (XZ cross section: the same applies to the following embodiments) is shown. FIG. 13 shows an enlarged part of the two-dimensional scanning device. FIG. 14 shows a numerical example (lens data) of the two-dimensional scanning device of the present embodiment. In FIG. 14, the coordinates representing the position of the surface vertex of the optical surface are the deflections having the maximum angle of view with the origin at the point where the deflected light beam Bdm having the maximum angle of view is reflected and deflected by the second deflector 4b in FIG. The direction in which the light beam Bdm travels is the Z axis, the horizontal direction perpendicular to the Z axis is the X axis (the direction away from the deflection scanning axis Ldc, which is the right side in FIG. 13), and the Z axis and the X axis are The vertical direction is shown as the Y axis. In addition, the surface interval indicates the coordinate position of each surface vertex as a distance along the Z-axis direction.
[0066]
Hereinafter, the arrangement of the scanning optical system 5 and the scanned surface 6 in this embodiment will be described with reference to these drawings.
[0067]
The scanning optical system 5 of the present embodiment is composed of two scanning lenses, and is defined as a first scanning lens 5a and a second scanning lens 5b from the deflection unit 4 side.
[0068]
In the present embodiment, the maximum horizontal field angle α is ± 20.3 (deg) centered on the deflection scanning axis Ldc, and the maximum vertical field angle is ± 15.2 (deg) centered on the deflection scanning axis Ldc.
[0069]
First, the scanning optical system 5 is arranged eccentrically with respect to the deflection scanning axis Ldc so that the central beam LBdm of the deflected light beam Bdm having the maximum field angle α in the horizontal direction (X direction) passes on the optical axis. Yes.
[0070]
The first scanning lens 5a disposed on the deflection unit 4 side is disposed so that the surface vertices of the incident surface and the exit surface are positioned on the optical axis of the scanning optical system 5 (the central light beam LBdm of the deflected light beam Bdm). Yes.
[0071]
On the other hand, the second scanning lens 5b disposed on the scanned surface 6 side is disposed with a tilt and a shift applied to the optical axis of the scanning optical system 5 in the horizontal direction. In the present embodiment, the second scanning lens 5b is deflected from the optical axis L5b of the second scanning lens 5b (the normal at the surface vertex Asi of the incident surface and the normal at the surface vertex Ase of the exit surface: surface normal). The angle β ′ formed with the light beam Bdm (center ray LBdm) is tilted so as to be 15.6 (deg). As a result, the second scanning lens 5b is tilted such that the optical axis L5b forms an angle β = 35.9 (deg) with respect to the deflection scanning axis Ldc. This angle β is 15.6 (deg) larger than the maximum angle of view α = 20.3 (deg).
[0072]
The second scanning lens 5b is disposed on the deflected light beam Bdm having the maximum field angle α, and the optical axis L5b (surface normal of the incident surface) of the second scanning lens 5b is extended to the emission side. On the side extending the optical axis L5b with respect to the deflection scanning axis Ldc, that is, on the right side in FIGS. 12 and 13, the surface vertex Asi (that is, the optical axis L5b) of the incident surface is 10.5 with respect to the deflection scanning axis Ldc. (mm) Shifting away.
[0073]
Therefore, the surface vertex of the incident surface of the second scanning lens 5b is arranged on the deflected light beam having the maximum angle of view, and the surface vertex of the outgoing surface of the second scanning lens 5b is outside the deflection range (two-dimensional deflection range) of the deflected light beam. The incident / exit surfaces of the second scanning lens 5b are only used on one side from the apex of each surface.
[0074]
Furthermore, in this embodiment, Horizontal In the cross section, the scanned surface 6 (normal line thereof) is tilted by γ ′ = 10.1 (deg) in the counterclockwise direction in FIG. 12 with respect to the deflected light beam Bdm having the maximum angle of view α. Γ = 30.4 (deg) is tilted with respect to the deflection scanning axis Ldc. At this time, the scanned surface 6 is tilted in the same direction as the second scanning lens 5b with respect to the deflection scanning axis Ldc. Further, the scanned surface 6 is also tilted at an angle larger than the maximum field angle α.
[0075]
The two scanning lenses 5a and 5b of the scanning optical system 5 configured as described above are both rotationally asymmetric aspheric surfaces having no rotational symmetry axis, and the first scanning lens 5a has negative optical power (focal length). Is a meniscus lens having a concave surface facing the deflection unit 4 side. The second scanning lens 5b is a meniscus lens having a concave surface facing the deflection unit 4 side.
[0076]
In the rotationally asymmetric aspherical surface in the present embodiment, the displacement amount Z in the direction in which the deflected light beam Bdm travels (Z direction) is expressed by the following equation at each position in the horizontal direction (X direction) and the vertical direction (Y direction). It has a shape.
[0077]
[Formula 1]

[0078]
Where z: sag of plane parallel to Z-axis
c: curvature of vertex
k: Conic coefficient
Cj: coefficient of xmyn
It is.
[0079]
FIG. 15 shows an image (lattice) scanned and displayed by the two-dimensional scanning device of the present embodiment. FIG. 16 shows the amount of TV distortion and trapezoidal distortion of the display image.
[0080]
In the TV distortion of the image shown in FIG. 15, the upper side L1 of the frame is 0.15 (%), the lower side L2 is 0.15 (%), the left side L3 is 0.27 (%), and the right side L4 is 0.04 (%). %) And In the comparative example The curved upper side L1 and lower side L2 are corrected to be substantially straight lines. Further, the trapezoidal distortion is such that the upper side L1 and the lower side L2 are both 0.05 (%), the left side L3 and the right side L4 are both 0 (%), and In the comparative example The inclined line is corrected to a vertical line.
[0081]
As described above, according to this embodiment, the optical axis of the scanning optical system 5 is decentered from the deflection scanning axis Ldc, and an appropriate tilt or shift is given to the scanning lenses 5a and 5b as optical elements constituting the scanning optical system. Further, by tilting the scanned surface 6, it is possible to satisfactorily correct TV distortion and trapezoidal distortion of the display image.
[0082]
Specifically, at least one optical element (second scanning lens 5b) among the optical elements included in the scanning optical system 5 is tilted at an angle β larger than the maximum field angle α with respect to the deflection scanning axis Ldc. When the normal line at the surface apex of the incident surface of the optical element is extended to the emission side, it is shifted to the side where the surface normal line extends with respect to the deflection scanning axis Ldc. Further, the scanned surface 6 is tilted in the same direction as the optical element with respect to the deflection scanning axis Ldc.
[0083]
Here, a TV distortion correction mechanism will be described. By displacing the scanning optical system (scanning lenses 5a and 5b) from the deflection scanning axis Ldc, the TV distortion of the display image is generated asymmetrically. The TV distortion is small in the vicinity of the optical axis of the scanning optical system 5, and the TV distortion increases as the distance from the optical axis of the scanning optical system 5 increases. At this time, by tilting the second scanning lens 5b, the TV distortion at a position away from the optical axis of the scanning optical system 5 can be corrected without substantially affecting the vicinity of the optical axis of the scanning optical system 5. it can.
[0084]
That is, the scanning optical system 5 is decentered from the deflection scanning axis Ldc and the optical element (second scanning lens 5b) constituting the scanning optical system 5 is tilted with respect to the optical axis of the scanning optical system 5. TV distortion can be corrected satisfactorily (or small enough to cause no problem).
[0085]
In other words, the TV optical distortion is generated asymmetrically by shifting the scanning optical system 5 from the deflection scanning axis Ldc, and the optical element (second scanning lens 5b) constituting the scanning optical system 5 is tilted to be asymmetrical. TV distortion can be corrected. At this time, the TV distortion is corrected by tilting the optical element (second scanning lens 5b) at an angle (an angle larger than the maximum angle of view α) larger than the angle at which any deflected light beam is made with respect to the deflection scanning axis Ldc. The effect is increased.
[0086]
Next, the correction mechanism for trapezoidal distortion will be described. Although the trapezoidal distortion is generated by decentering the scanning optical system 5 (scanning lenses 5a and 5b) from the deflection scanning axis Ldc, the reverse trapezoidal distortion can be generated by tilting the surface to be scanned 6. it can. Thereby, both can be canceled and the trapezoidal distortion can be corrected.
[0087]
As described above, according to the present embodiment, it is possible to realize a two-dimensional scanning device that can satisfactorily correct TV distortion and trapezoidal distortion generated in a display image formed on the scanned surface 6 and display a high-quality image. it can.
[0088]
Note that, when the two-dimensional scanning device of the present embodiment is used as a projector, it is possible to project an image from an oblique direction onto a projection surface such as a screen by tilting the scanning surface 6. Thereby, when observing an image from behind the projector, it is possible to avoid the image from being shaded by the projector and to increase the degree of freedom in arranging the projector.
[0089]
In the present embodiment, the tilted second scanning lens (transmission type optical element having no reflecting surface) 5b has a meniscus shape with a concave surface facing the deflection unit 4, but this allows the second scanning lens 5b to be tilted. The effect on the curvature of field can be reduced while maintaining the effect of correcting the TV distortion and the trapezoidal distortion due to the tilt of. That is, TV distortion and trapezoidal distortion can be corrected separately from curvature of field, and correction of TV distortion and trapezoidal distortion becomes easy.
[0090]
In addition, the optical surfaces of the two optical elements constituting the scanning optical system 5 of the present embodiment are all configured by transmissive refracting surfaces. In this case, the accuracy required for the refracting surface is ¼ that of the reflecting surface, so that there is an advantage that the optical element can be easily manufactured. In addition, when a reflecting surface is used, after the optical path is tilted (bent) on the reflecting surface, there is a restriction on handling the optical path, but the transmissive refracting surface is not affected by this, There is also an advantage that the degree of freedom of arrangement is large.
[0091]
Furthermore, since the transmittance of light rays for displaying an image is higher than the reflectance, there is also a merit that the loss of light amount is very small, especially when the number of optical surfaces is large. Further, the transmittance is very high by applying the antireflection film.
[0092]
In addition, in an optical element in which a refracting surface and a reflecting surface are mixed, it is necessary to secure an optical path inside the optical element, and the optical element itself becomes large.
[0093]
However, in the case of using an optical element whose optical surface is composed only of a refracting surface, it is not necessary to secure an optical path in the optical element, so that the optical element can be thinned and the two-dimensional scanning apparatus can be miniaturized. It is advantageous.
[0094]
Therefore, when an optical element that does not have a reflecting surface that directs light to the surface to be scanned is used in the scanning optical system, the reflecting surface is proposed as disclosed in Japanese Patent Laid-Open Nos. 11-84291 and 2001-28183. Compared to the use of an optical member having the above, various effects can be enjoyed. In the present invention, an optical element that uses a diffractive surface that transmits and diffracts light instead of the refracting surface or in combination with the refracting surface can also be used to correct image distortion on the surface to be scanned.
[0095]
In the present embodiment, the two optical elements constituting the scanning optical system 5 are plastic lenses. However, the plastic lens is advantageous in that it can be manufactured at low cost by injection molding and is lighter than glass. For this reason, an image display device equipped with this two-dimensional scanning device can be reduced in weight, which is advantageous for carrying. In addition, when a large optical element having both a refractive surface and a reflective surface is made by plastic molding, there is a possibility that the influence of the refractive index distribution and birefringence may be greatly increased. There is little such influence when downsizing (thinning).
[0096]
(Embodiment 2)
FIG. 17 shows a two-dimensional scanning device according to Embodiment 2 of the present invention. Horizontal A cross section is shown. FIG. 18 shows a numerical example (lens data) of the two-dimensional scanning device of the present embodiment. Hereinafter, the present embodiment will be described with reference to these drawings. In the present embodiment, the same reference numerals as those in the first embodiment are given to the same components as those in the first embodiment, and the description is omitted.
[0097]
This embodiment is different from the first embodiment in that the light beam incident on the deflection unit 4 is a parallel light beam and the configuration of the scanning optical system.
[0098]
As in the first embodiment, the scanning optical system 15 in the present embodiment is arranged eccentrically from the deflection scanning axis Ldc in the horizontal direction, and the center beam of the deflected light beam Bdm having the maximum field angle α in the horizontal direction is scanning optical. It is arranged so as to pass on the optical axis of the system 15.
[0099]
The scanning optical system 15 includes two scanning lenses (a first scanning lens 15a and a second scanning lens 15b). The first scanning lens 15a disposed on the deflection unit 4 side is not tilted or shifted, and the first scanning lens 15a has the surface vertices of the entrance surface and the exit surface positioned on the optical axis of the scanning optical system 5. (That is, the optical axis of the first scanning lens 15a is positioned on the optical axis of the scanning optical system 5).
[0100]
On the other hand, the second scanning lens 15b arranged on the scanned surface 6 side has a normal line (surface normal line) at the surface vertex of the incident surface with respect to the deflected light beam Bdm having a maximum field angle α in the horizontal direction. In FIG. 17, it is tilted so that β ′ = 25.0 (deg) in the counterclockwise direction, and the surface normal is tilted with respect to the deflection scanning axis Ldc so that β = 45.3 (deg). ing. Also in this embodiment, since the maximum field angle α is 20.3 (deg), the second scanning lens 15b is tilted with respect to the deflection scanning axis Ldc at an angle β larger than the maximum field angle α. Become.
[0101]
Further, the second scanning lens 15b moves the normal line at the surface vertex of the incident surface of the second scanning lens 15b toward the exit side in the direction away from the deflection scanning axis Ldc with respect to the deflected light beam Bdm having the maximum field angle α. When extended, the surface vertex of the incident surface is 20.0 (mm) away from the deflected light beam Bdm toward the side (right side in FIG. 17) whose normal line is inclined with respect to the deflection scanning axis Ldc. There is a shift. Therefore, the second scanning lens 15b is arranged such that the surface vertex of the incident / exit surface is located outside the deflection range (two-dimensional deflection range) of the deflected light beam, and the incident / exit surface of the second scanning lens 15b is the respective one. Only the part on one side from the surface vertex is used.
[0102]
The scanned surface 6 is also Horizontal With respect to the deflected light beam Bdm having the maximum angle of view α in the cross section, γ ′ = 6.8 (deg) is tilted counterclockwise in FIG. This means that the scanned surface 6 is tilted with respect to the deflection scanning axis Ldc by an angle γ = 27.1 (deg) larger than the maximum field angle α in the same direction as the second scanning lens 15b.
[0103]
In the scanning optical system 15 configured as described above, the first scanning lens 15a is a spherical lens. Further, the second scanning lens 15b is an anamorphic lens composed of an anamorphic surface as well as an incident / exit surface. Horizontal It is a rotationally asymmetric aspherical surface having different aspherical amounts in cross section and vertical cross section.
[0104]
Further, the exit surface of the second scanning lens 15b has an angle formed by the normal of the surface vertex of the exit surface with respect to the deflection scanning axis Ldc, and the normal of the surface vertex of the incident surface with respect to the deflection scanning axis Ldc. It is tilted with respect to the normal of the surface vertex of the incident surface so as to be 8.1 (deg) larger than the angle, and the surface vertex of the exit surface of the second scanning lens 15b is relative to the surface vertex of the incident surface. It is shifted by 49.4 (mm) in the direction away from the deflection scanning axis Ldc.
[0105]
FIG. 19 shows an image (grating) scanned and displayed by the two-dimensional scanning apparatus of this embodiment, and FIG. 20 shows the amount of TV distortion and trapezoidal distortion of the display image.
[0106]
The TV distortion is 0.16 (%) on the upper side L1 of the image frame, 0.16 (%) on the lower side L2, 0.19 (%) on the left side L3, and 0.11 (%) on the right side L4, and is corrected well. The trapezoidal distortion is 0.11 (%) for both the upper side L1 and the lower side L2 of the image frame, and 0.0 (%) for both the left side L3 and the right side L4.
[0107]
As described above, the second scanning lens 15b is tilted with respect to the deflection scanning axis Ldc at an angle larger than the maximum field angle α, while the second scanning lens. 1 The TV distortion correction effect can be improved by making the tilt amount and the shift amount of the entrance surface and the exit surface 5b different.
[0108]
An object of the present invention is to provide a two-dimensional scanning device that can always display a high-quality image. TV distortion is an aberration amount indicating the linearity of the frame of the display image, but in order to display a high-quality image, it is necessary to properly correct the linearity at a position inside the frame of the display image. . However, in general, the linearity generated differs depending on the position and direction of the image, and even if the scanning optical system is tilted or shifted, the inside of the frame may not be completely corrected.
[0109]
Therefore, in the present embodiment, the second scanning lens 15b of The entrance / exit surface is composed of a rotationally asymmetric aspheric surface. By making the lens surface an aspherical surface in this way, it is possible to obtain a lens surface shape that can ensure linearity at each position in the image, and by making it a rotationally asymmetric aspherical surface, the linearity in each direction within the image is achieved. The lens surface shape can be secured. Thus, by making the tilted second scanning lens 15b a rotationally asymmetric lens, the second scanning lens 15b. Own It is possible to correct linearity in each position and direction in an image that cannot be corrected by tilt. Furthermore, TV distortion can also be corrected effectively.
[0110]
The second scanning lens 15b is an anamorphic lens that is configured as an anamorphic surface in which the incident surface and the exit surface have different optical powers in the horizontal direction and the vertical direction. As a result, it is possible to correct an asthma generated when the second scanning lens 15b is tilted.
[0111]
In this embodiment, an aspherical coefficient up to (m + n) ≦ 4 is used for the rotationally asymmetric aspherical surface of the tilted or shifted second scanning lens 15b. However, the present invention is not limited to this. By using an aspherical coefficient of higher order (m + n) ≧ 6, it becomes possible to more effectively correct TV distortion and trapezoidal distortion.
[0112]
Further, as in this embodiment, the two-dimensional scanning apparatus can be made compact by cutting the other portions of the lens that is tilted and shifted while leaving only the portion to be used.
[0113]
(Embodiment 3)
FIG. 21 shows a two-dimensional scanning apparatus according to Embodiment 3 of the present invention. Horizontal A cross section is shown. FIG. 22 shows a numerical example (lens data) of the two-dimensional scanning device according to this embodiment. Hereinafter, the present embodiment will be described with reference to these drawings. In the present embodiment, constituent elements common to the other embodiments are denoted by the same reference numerals as those of the other embodiments, and the description is omitted.
[0114]
In the present embodiment, the two optical elements (25a, 25b) constituting the scanning optical system 25 are shifted in the direction away from the deflection scanning axis Ldc with respect to the deflected light beam Bdm having the maximum angle of view α. This is different from the second embodiment in that all the surface vertices are arranged outside the two-dimensional deflection range in which the deflected light beam is deflected. In the present embodiment, the shift amounts of the optical surfaces of the two optical elements are different from each other.
[0115]
Also in the present embodiment, as in the second embodiment, the scanning optical system 25 is configured by two glass lenses 25a and 25b, and the first scanning lens 25a and the second scanning lens 25b are formed from the deflection unit 4 side. .
[0116]
The first scanning lens 25a is a meniscus lens having a concave surface facing the deflection unit 4 side, and both the entrance and exit surfaces are formed as spherical surfaces. Here, in the present embodiment, the first scanning lens 25a has a surface vertex of the incident surface 32.1 away from the deflected light beam Bdm in a direction away from the deflected scanning axis Ldc with respect to the deflected light beam Bdm having the maximum angle of view α. (mm) Shifting away. Further, the surface vertex of the exit surface of the first scanning lens 25a is shifted by 26.0 (mm) in the direction approaching the deflected light beam Bdm having the maximum field angle α with respect to the surface vertex of the incident surface.
[0117]
The second scanning lens 25b is a meniscus lens having a concave surface directed toward the deflection unit 4, and is composed of a rotationally asymmetric aspherical surface that does not have a rotationally symmetric axis on both the entrance and exit surfaces. Here, in the second scanning lens 25b, the normal line (surface normal line) at the surface vertex of the incident surface forms β ′ = 30 (deg) with respect to the deflected light beam Bdm having the maximum field angle α. It is tilted and tilted so that the surface normal is β = 50.3 (deg) with respect to the deflection scanning axis Ldc. Also in this embodiment, as in the first and second embodiments, the horizontal maximum field angle α is 20.3 deg, and the tilt amount (β) with respect to the deflection scanning axis Ldc of the second scanning lens 25b is the maximum field angle α. Is bigger than.
[0118]
Further, when the normal line of the surface vertex of the incident surface is extended to the output side, the second scanning lens 25b has a side on which the normal line is inclined with respect to the deflection scanning axis Ldc, that is, the maximum angle of view α. In the direction away from the deflection scanning axis Ldc (right side in FIG. 21) with respect to the deflected light beam Bdm, the surface vertex of the incident surface is shifted so as to be 13.4 (mm) away from the deflected light beam Bdm. The surface vertex of the exit surface of the scanning lens 25b is shifted 135.7 (mm) in the direction away from the deflection scanning axis Ldc with respect to the surface vertex of the incident surface.
[0119]
Therefore, all optical surfaces (incident / exit surfaces) of all optical elements (scanning lenses 25a and 25b) included in the scanning optical system 25 are arranged outside the two-dimensional deflection range in which the deflected light beam is deflected. Only the part on one side of the optical axis in the optical element is used. With such a configuration, it is possible to correct TV distortion better.
[0120]
At this time, the second scanning lens 2 The normal line in the entire area of the deflected light beam passage area (the portion used for guiding the deflected light beam) on the entrance surface and the exit surface 5b is inclined at an angle larger than the maximum field angle α with respect to the deflection scanning axis Ldc. Yes. Thereby, TV distortion can be corrected more effectively.
[0121]
The scanned surface 6 is also Horizontal The cross section is tilted by γ ′ = 5.0 (deg) in the counterclockwise direction in FIG. 21 with respect to the deflected light beam Bdm having the maximum angle of view α. This means that the scanned surface 6 is tilted with respect to the deflection scanning axis Ldc by an angle γ = 25.3 (deg) larger than the maximum field angle α in the same direction as the second scanning lens 25b.
[0122]
FIG. 23 shows an image (lattice) scanned and displayed by the two-dimensional scanning apparatus of this embodiment, and FIG. 24 shows the amount of TV distortion and trapezoidal distortion of the display image.
[0123]
The TV distortion is 0.04 (%) at the upper side L1 of the image frame, 0.04 (%) at the lower side L2, 0.06 (%) at the left side L3, and 0.11 (%) at the right side L4, and is corrected very well. The trapezoidal distortion is 0.01% for both the upper side L1 and the lower side L2 of the image frame, and 0.00% for both the left side L3 and the right side L4, and is corrected so that the trapezoidal distortion is almost eliminated.
[0124]
As described above, by arranging two or more optical elements of the optical elements included in the scanning optical system outside the two-dimensional deflection range in which the deflected light beam is deflected, the effect of correcting TV distortion and trapezoidal distortion is increased. . Therefore, it is possible to realize a two-dimensional scanning apparatus capable of displaying a very high-quality two-dimensional image.
[0125]
In the present embodiment, the first scanning lens 25a is a spherical lens. However, the TV distortion correction effect can be further enhanced by using an anamorphic lens or a rotationally asymmetric aspheric lens. Further, when a plurality of light sources emitting different wavelengths (colored light) are used as the light source 1, it is possible to perform achromaticity by using a lens provided with a diffraction grating.
[0126]
(Embodiment 4)
FIG. 25 shows a two-dimensional scanning apparatus according to Embodiment 4 of the present invention. Horizontal A cross section is shown. FIG. 26 shows a numerical example (lens data) of the two-dimensional scanning device in the present embodiment. Hereinafter, the present embodiment will be described with reference to these drawings. In the present embodiment, constituent elements common to the other embodiments are denoted by the same reference numerals as those of the other embodiments, and the description is omitted.
[0127]
This embodiment is different from Embodiment 3 in that the two optical elements (35a, 35b) constituting the scanning optical system 35 are tilted with respect to the deflection scanning axis Ldc at an angle larger than the maximum field angle α. In the present embodiment, the tilt amounts of the lens surfaces of the optical elements are also different from each other.
[0128]
Also in the present embodiment, as in the second embodiment, the scanning optical system 35 includes two glass lenses 35a and 35b, and the first scanning lens 35a and the second scanning lens 35b are formed from the deflection unit 4 side.
[0129]
The first scanning lens 35a is a meniscus lens having a concave surface directed toward the deflection unit 4, and is composed of a rotationally asymmetric aspherical surface that does not have a rotationally symmetric axis on both the entrance and exit surfaces. Here, in the first scanning lens 35a, the surface vertex of the incident surface is away from the deflection scanning axis Ldc with respect to the deflected light beam Bdm having the maximum angle of view α (the normal line at the surface vertex of the incident surface is directed to the output side). When extended, it is shifted to the side where the normal line extends with respect to the deflection scanning axis Ldc so as to be 27.2 (mm) away from the deflection light beam Bdm. Further, the surface vertex of the exit surface of the first scanning lens 35a is shifted by 34.2 (mm) from the surface vertex of the incident surface in a direction approaching the deflected light beam Bdm having the maximum field angle α.
[0130]
Further, the first scanning lens 35a is tilted such that the normal (surface normal) at the surface vertex of the incident surface forms β1 ′ = 7.5 (deg) with respect to the deflected light beam Bdm having the maximum angle of view α. The surface normal is tilted with respect to the deflection scanning axis Ldc so that β1 = 27.8 (deg). Further, the exit surface of the first scanning lens 35a is tilted such that the surface normal forms an angle of -9.3 (deg) with respect to the surface normal of the incident surface.
[0131]
The second scanning lens 35b is a meniscus lens having a concave surface directed toward the deflection unit 4, and is a rotationally asymmetric aspherical surface that does not have a rotationally symmetric axis on both the entrance and exit surfaces. Here, the second scanning lens 35b is configured such that the normal (surface normal) at the surface vertex of the incident surface forms β2 ′ = 28.2 (deg) with respect to the deflected light beam Bdm having the maximum angle of view α. It is tilted and tilted so that the surface normal is β2 = 48.5 (deg) with respect to the deflection scanning axis Ldc. Also in the present embodiment, as in the first to third embodiments, the horizontal maximum field angle α is 20.3 (deg), and both the first scanning lens 35a and the second scanning lens 35b are tilted with respect to the deflection scanning axis Ldc ( β1, β2) is larger than the maximum angle of view α.
[0132]
Further, the second scanning lens 35b extends in the direction in which the surface vertex of the incident surface moves away from the deflection scanning axis Ldc with respect to the deflected light beam Bdm having the maximum angle of view α (the normal line at the surface vertex of the incident surface extends to the emission side. At the time when the normal line extends with respect to the deflection scanning axis Ldc) so as to be separated from the deflection light beam Bdm by 11.3 (mm). Further, the surface vertex of the exit surface of the second scanning lens 35b is shifted by 108.4 (mm) in the direction away from the deflection scanning axis Ldc with respect to the surface vertex of the incident surface.
[0133]
Thus, in this embodiment, the two optical elements (35a, 35b) included in the scanning optical system 35 are tilted with respect to the deflection scanning axis Ldc at an angle larger than the maximum field angle α. Further, the shift amount and tilt amount of the optical surface of each optical element are made different from each other. In particular, with respect to the exit surface of the second scanning lens 35b tilted at a larger angle than the maximum field angle α with respect to the deflection scanning axis Ldc, the tilt amount is made larger than the tilt amount of the entrance surface, and the shift amount is also incident. It is larger than the shift amount of the surface.
[0134]
Each of these configurations has an effect of satisfactorily correcting TV distortion. By adopting a configuration in which these are combined into one, TV distortion can be corrected extremely well.
[0135]
FIG. 27 shows an image (lattice) scanned and displayed by the two-dimensional scanning apparatus of this embodiment, and FIG. 28 shows the amount of TV distortion and trapezoidal distortion of the display image.
[0136]
The TV distortion is 0.06 (%) on the upper side L1 of the image frame, 0.06 (%) on the lower side L2, 0.07 (%) on the left side L3, and 0.06 (%) on the right side L4, and is corrected very well. The trapezoidal distortion is 0.01 (%) for both the upper side L1 and the lower side L2 of the frame of the image, and 0.00 (%) for both the left side L3 and the right side L4, and is corrected so that the trapezoidal distortion is almost eliminated.
[0137]
In this way, by tilting two or more of the optical elements included in the scanning optical system at an angle larger than the maximum field angle with respect to the deflection scanning axis, the effect of correcting TV distortion and trapezoidal distortion can be obtained. Can be improved. Further, by making the tilt amount and the shift amount different for each optical surface of each optical element, it is possible to further enhance the effect of correcting TV distortion and trapezoidal distortion. Therefore, it is possible to realize a two-dimensional scanning device capable of displaying a very high-quality two-dimensional image.
[0138]
In this embodiment, two optical elements are tilted and shifted. However, the present invention is not limited to this. For example, the same effect can be obtained by tilting or shifting three or more optical elements. Can do.
[0139]
(Embodiment 5)
FIG. 29 shows a two-dimensional scanning apparatus according to Embodiment 5 of the present invention. Horizontal A cross section is shown. FIG. 30 shows a numerical example (lens data) of the two-dimensional scanning device in the present embodiment. Hereinafter, the present embodiment will be described with reference to these drawings. In the present embodiment, constituent elements common to the other embodiments are denoted by the same reference numerals as those of the other embodiments, and the description is omitted.
[0140]
This embodiment is different from the other embodiments in that the scanning optical system 45 is composed of one optical element (45a).
[0141]
The scanning optical system 45 in the present embodiment is configured by a single scanning lens 45a formed by a glass mold. The scanning lens 45a is arranged eccentrically with respect to the deflection scanning axis Ldc. In the scanning lens 45a, the normal line (surface normal line) at the surface vertex of the incident surface is β1 ′ = 25.0 (deg) in the counterclockwise direction in FIG. 29 with respect to the deflected light beam Bdm having the maximum field angle α. The surface normal is tilted counterclockwise with respect to the deflection scanning axis Ldc so that β1 = 45.3 (deg).
[0142]
Further, the exit surface of the scanning lens 45a is tilted so that the normal of the surface vertex (surface normal) forms β2 ′ = 11.0 (deg) counterclockwise with respect to the surface normal of the incident surface. Thus, the surface normal of the exit surface is tilted with respect to the deflection scanning axis Ldc so that β2 = 56.3 (deg) in the counterclockwise direction. Also in the present embodiment, as in the first to fourth embodiments, the maximum horizontal angle of view α is ± 20.3 deg with respect to the deflection scanning axis Ldc, and the scanning lens 45a has a maximum image angle with respect to the deflection scanning axis Ldc. The tilt amount is larger than the angle α. This is the same as the incident / exit surface of the scanning lens 45a.
[0143]
Further, when the surface normal of the incident surface is extended to the exit side, the scanning lens 45a is directed to the side where the surface normal extends while being inclined with respect to the deflection scanning axis Ldc, that is, the deflected light beam Bdm having the maximum field angle α. On the other hand, in the direction away from the deflection scanning axis Ldc, the surface vertex of the incident surface is shifted so as to be 12.9 (mm) away from the deflected light beam Bdm. Furthermore, the surface vertex of the exit surface is shifted 55.4 (mm) in the direction away from the deflection scanning axis Ldc with respect to the surface vertex of the entrance surface. Thereby, the entrance / exit surface (all optical surfaces) of the scanning lens 45a. Face vertex Is arranged outside the two-dimensional deflection range in which the deflected light beam is deflected.
[0144]
Further, the scanned surface 6 is also tilted by γ ′ = 8.4 (deg) in the counterclockwise direction in FIG. 29 with respect to the deflected light beam Bdm having the maximum angle of view α, and the maximum with respect to the deflected scanning axis Ldc. Γ is greater than angle of view α = 28.7 (deg) Tilt. The tilt direction of the scanned surface 6 is the same as the tilt direction of the scanning lens 45a with respect to the deflection scanning axis Ldc.
[0145]
Thus, in the present embodiment, since the scanning optical system 45 is composed of only one scanning lens 45a, the number of parts can be reduced, and the cost can be reduced and the manufacturing can be facilitated.
[0146]
Further, in the present embodiment, the scanning lens 45a is an anamorphic lens having an anamorphic surface on the entrance / exit surface, and the entrance / exit surface is Horizontal It is composed of a rotationally asymmetric aspherical surface having different aspherical amounts in the cross section and the vertical cross section.
[0147]
FIG. 31 shows an image (grating) scanned and displayed by the two-dimensional scanning apparatus of this embodiment, and FIG. 32 shows the amount of TV distortion and trapezoidal distortion of the display image.
[0148]
The TV distortion is 0.17 (%) on the upper side L1 of the image, 0.17 (%) on the lower side L2, 0.13 (%) on the left side L3, and 0.20 (%) on the right side L4, and is sufficiently corrected. The trapezoidal distortion is 0.10 (%) for both the upper side L1 and the lower side L2, and is 0.00 (%) for both the left side L3 and the right side L4.
[0149]
As described above, even when the scanning optical system 45 is constituted by one optical element (45a), the optical element is tilted with respect to the deflection scanning axis Ldc at an angle larger than the maximum field angle α, and the surface vertex of the incident surface is obtained. When the normal line is extended to the exit side, the optical element is shifted to the side where the normal line extends with respect to the deflection scanning axis Ldc, and the surface to be scanned is directed to the deflection scanning axis Ldc in the same direction as the optical element. By tilting to the TV distortion, the TV distortion can be corrected satisfactorily.
[0150]
Furthermore, a rotationally asymmetric aspherical surface is used for the tilting optical element, the surface apex of the optical element is arranged outside the two-dimensional deflection range where the deflected light beam is deflected, and the tilt amount and shift amount of each optical surface of the optical element are set. By making them different from each other, the effect of correcting TV distortion and trapezoidal distortion can be remarkably improved.
[0151]
In each of the above embodiments, the case where a glass lens is used as an optical element constituting the scanning optical system has been described. However, by using an optical element other than a glass lens, for example, a plastic lens made by injection molding, manufacturing is performed. Thus, the cost can be reduced and the weight of the two-dimensional scanning device can be reduced.
[0152]
Further, a two-dimensional color image can be displayed by providing the light source with light emitting portions of three colors of blue, green, and red. In this case, achromatization may be performed using an optical element including a diffraction grating. Accordingly, it is possible to realize a scanning image display device that can scan and display a high-quality color image. In this case, for example, light of three colors of blue, green, and red may be directed to the deflection unit sequentially (field sequential) or simultaneously. In addition to this, a combination of a white light source and blue, green, and red filters arranged on a rotatable turret allows the blue, green, and red light to be sequentially applied to the deflection unit. Can be directed.
[0153]
As described above, the light source and the deflection unit control method for forming a color two-dimensional image using the deflection unit and the scanning optical system while directing light of three colors of blue, green, and red from the light source to the deflection unit. Description is omitted.
[0154]
In each of the above embodiments, the case where two deflectors using MEMS devices capable of resonant oscillation in a one-dimensional direction are provided as the deflection unit has been described. However, the MEMS device shown in FIG. May be used. In the deflector using the MEMS device, the reflecting surface 54a is supported by the vibration frame 54c via the torsion bar 54b, and the vibration frame 54c is further supported by the casing via the torsion bar 54d extending in a direction perpendicular to the torsion bar 54b. By being supported by 54e, the reflecting surface 54a is resonantly oscillated in a two-dimensional direction around the torsion bars 54b and 54d (deflection axes).
[0155]
Further, instead of the deflector using the MEMS device, a galvanometer mirror or polygon mirror whose reflecting surface rotates may be used.
[0156]
Further, as proposed in the above-mentioned Japanese Patent Laid-Open No. 8-146320, there is a technique for electrically correcting TV distortion. However, this kind of electrical correction and optical by the scanning optical system according to the present invention are also available. It is also possible to adopt a configuration in which image distortion is corrected by combining various corrections.
[0157]
When the TV distortion is electrically corrected, a drive circuit (not shown) that controls the deflection means controls the tilt angle of the reflecting surface during two-dimensional scanning so as to correct the remaining distortion after optical correction.
[0158]
(Sixth embodiment)
FIG. 34 shows an example of a scanning image display device provided with the two-dimensional scanning device of the present embodiment. FIG. 34A shows a projector 100 that displays an image on a screen 105 provided on a wall surface or the like, and the two-dimensional scanning device 102 of this embodiment is housed in a housing 101.
[0159]
FIG. 34B shows a stand-type projector 110 that displays an image on a desk surface as a substitute for a display of a personal computer, etc., and is mounted in a pan head 111 supported above the desk surface. The two-dimensional scanning device 112 of this embodiment is accommodated.
[0160]
Both projectors 100 and 110 are connected to an image information supply device 150 such as a personal computer, a video, a DVD player, etc., and an image display system is configured. In the projectors 100 and 110, a drive circuit that modulates single color light or multiple color light emitted from the light source 1 based on image information input from the image information supply device 150 is provided. Accordingly, the projectors 100 and 110 can scan and display an image corresponding to the image information supplied from the image information supply device 150 on the screen 105 or the desk surface 115.
[0161]
Each of the embodiments described above has been described by taking an example of an image display device (for example, a projector) that has a screen or the like on the surface to be scanned and directly observes the image. The present invention can also be applied to an image display device (for example, a finder) that is observed through a relay optical system or the like.
[0162]
Furthermore, the present invention can also be applied to the case where the light beam from the light source is incident on the reflecting surface of the deflecting means from an oblique direction with respect to the swing axis (deflection axis) of the reflecting surface.
[0163]
【The invention's effect】
As described above, according to the present invention, it is possible to easily and satisfactorily correct TV distortion and distortion including trapezoidal distortion that occur when a light beam is deflected and scanned in a two-dimensional direction to form a two-dimensional image. Thereby, it is possible to realize a two-dimensional scanning device and a scanning image display device capable of displaying a high-quality image with little distortion.
[Brief description of the drawings]
FIG. 1 is a perspective view of a two-dimensional scanning apparatus that is Embodiment 1 of the present invention.
FIG. 2 is a schematic diagram of a main part of the two-dimensional scanning apparatus according to the first embodiment.
FIG. 3 is a schematic diagram of a main part of a one-dimensional deflector used in a two-dimensional scanning device.
FIG. 4 shows a two-dimensional scanning apparatus according to Comparative Example 1 of the present invention. Horizontal Sectional drawing.
FIG. 5 is a table showing numerical examples of the two-dimensional scanning device of Comparative Example 1;
FIG. 6 is a diagram for explaining TV distortion and trapezoidal distortion.
FIG. 7 is an explanatory diagram of a display image (lattice) in the comparative example 1;
FIG. 8 is a table showing the amount of TV distortion and trapezoidal distortion in Comparative Example 1;
FIG. 9 shows a two-dimensional scanning apparatus according to Comparative Example 2 of the present invention. Horizontal Sectional drawing.
10 is an explanatory diagram of a display image (lattice) in the comparative example 2. FIG.
FIG. 11 is a table showing the amount of TV distortion and trapezoidal distortion in Comparative Example 2;
FIG. 12 shows the two-dimensional scanning apparatus according to the first embodiment. Horizontal Sectional drawing.
FIG. 13 is an enlarged view of a main part of the two-dimensional scanning device according to the first embodiment.
FIG. 14 is a table showing numerical examples of the two-dimensional scanning apparatus according to the first embodiment.
15 is an explanatory diagram of a display image (grid) in the first embodiment. FIG.
FIG. 16 is a table showing the amount of TV distortion and trapezoidal distortion in the first embodiment.
FIG. 17 shows a two-dimensional scanning apparatus according to Embodiment 2 of the present invention. Horizontal Sectional drawing.
FIG. 18 is a table showing a numerical example of the two-dimensional scanning device according to the second embodiment.
FIG. 19 is an explanatory diagram of a display image (grid) in the second embodiment.
FIG. 20 is a table showing the amount of TV distortion and trapezoidal distortion in the second embodiment.
FIG. 21 shows a two-dimensional scanning apparatus according to Embodiment 3 of the present invention. Horizontal Sectional drawing.
FIG. 22 is a table showing numerical examples of the two-dimensional scanning device according to the third embodiment.
FIG. 23 is an explanatory diagram of a display image (grid) in the third embodiment.
FIG. 24 is a table showing the amount of TV distortion and trapezoidal distortion in the third embodiment.
FIG. 25 shows a two-dimensional scanning apparatus according to Embodiment 4 of the present invention. Horizontal Sectional drawing.
FIG. 26 is a table showing numerical examples of the two-dimensional scanning device according to the fourth embodiment.
FIG. 27 is an explanatory diagram of a display image (grid) in the fourth embodiment.
FIG. 28 is a table showing the amount of TV distortion and trapezoidal distortion in the fourth embodiment.
FIG. 29 shows a two-dimensional scanning apparatus according to Embodiment 5 of the present invention. Horizontal Sectional drawing.
FIG. 30 is a table showing numerical examples of the two-dimensional scanning device according to the fifth embodiment.
FIG. 31 is an explanatory diagram of a display image (grid) in the fifth embodiment.
FIG. 32 is a table showing the amount of TV distortion and trapezoidal distortion in the fifth embodiment.
FIG. 33 is a main part schematic diagram of a two-dimensional deflector used in a two-dimensional scanning apparatus.
FIG. 34 is a schematic diagram showing a projector provided with the two-dimensional scanning device of each of the embodiments.
[Explanation of symbols]
1 Light source
2 Condensing lens
3 Aperture stop
4 Deflection unit
5, 15, 25, 35, 45 Scanning optical system
6 Surface to be scanned

Claims (10)

Deflecting means for deflecting the light beam from the light source in a two-dimensional direction;
Wherein the light beam deflected by the deflecting means toward the surface to be scanned, and a one or two Ru scanning optical system name from the lens,
The light beam from the light source is incident on at least one of the two orthogonal deflection axes in the deflection unit from an oblique direction,
One lens of the scanning optical system , or a lens closer to the scanning surface among the two or less lenses, is 2 with respect to the central axis of the two-dimensional deflection range of the light beam immediately after being reflected by the deflecting means. possess an entrance surface which is tilted to form an angle larger than the maximum angle dimension deflection range, an exit surface which is tilted to form an angle larger than the incident surface to the central axis,
And when the normal line at the surface vertex that is the center of each of the entrance surface and the exit surface is extended to the exit side of the one lens or the lens close to the scanned surface , In contrast, the normal is shifted to the extending side ,
The two-dimensional scanning apparatus characterized in that the surface to be scanned is tilted in the same direction as the direction in which the incident surface and the exit surface are tilted . 2. The two-dimensional scanning apparatus according to claim 1, wherein a direction in which the incident surface and the exit surface are tilted is the same as one of the two orthogonal deflection axes . Surface vertices of the entrance surface and the exit surface are located outside the two-dimensional deflection range;
3. The method according to claim 1, wherein only a portion on one side of the incident surface and the exit surface is used to guide the light beam deflected by the deflecting unit to the surface to be scanned. The two-dimensional scanning device described.   The two-dimensional scanning apparatus according to claim 1, wherein the incident surface and the emission surface are anamorphic surfaces.   The two-dimensional scanning device according to any one of claims 1 to 3, wherein the entrance surface and the exit surface are rotationally asymmetric surfaces. Two-dimensional scanning apparatus according to any one of claims 1 to 5, characterized in that said lens is a meniscus lens having a concave surface facing to the deflecting means side. The two-dimensional scanning apparatus according to claim 2, wherein the angle of view in each direction of the two orthogonal deflection axes is different. Two-dimensional scanning apparatus according to any one of claims 1 to 7, the light beam incident on the deflecting means is characterized in that it is a convergent light beam. Scanning image display apparatus characterized by having a two-dimensional scanning apparatus according to any one of claims 1 to 8. The scanning image display apparatus according to claim 9 , wherein a color image is formed on the surface to be scanned by causing a plurality of light beams having different wavelengths to enter the deflecting unit from the light source.

Images