JP4592884B2 - Image display device having three-dimensional eccentric optical path - Google Patents

Description

ここで、（ａ）式の第１項は球面項、第２項は自由曲面項である。
【００２１】
球面項中、
ｃ：頂点の曲率
ｋ：コーニック定数（円錐定数）
ｒ＝√（Ｘ² ＋Ｙ² ）
である。
【００２２】
自由曲面項は、

ただし、Ｃ_j （ｊは２以上の整数）は係数である。
【００２３】
上記自由曲面は、一般的には、Ｘ−Ｚ面、Ｙ−Ｚ面共に対称面を持つことはないが、Ｘの奇数次項を全て０にすることによって、Ｙ−Ｚ面と平行な対称面が１つだけ存在する自由曲面となる。また、Ｙの奇数次項を全て０にすることによって、Ｘ−Ｚ面と平行な対称面が１つだけ存在する自由曲面となる。
【００２４】
また、上記の回転非対称な曲面形状の面である自由曲面の他の定義式として、Ｚｅｒｎｉｋｅ多項式により定義できる。この面の形状は以下の式（ｂ）により定義する。その定義式（ｂ）のＺ軸がＺｅｒｎｉｋｅ多項式の軸となる。回転非対称面の定義は、Ｘ−Ｙ面に対するＺの軸の高さの極座標で定義され、ＲはＸ−Ｙ面内のＺ軸からの距離、ＡはＺ軸回りの方位角で、Ｘ軸から測った回転角で表せられる。
【００２５】

ただし、Ｄ_m （ｍは２以上の整数）は係数である。なお、Ｘ軸方向に対称な光学系として設計するには、Ｄ₄ ，Ｄ₅ ，Ｄ₆ 、Ｄ₁₀，Ｄ₁₁，Ｄ₁₂，Ｄ₁₃，Ｄ₁₄，Ｄ₂₀，Ｄ₂₁，Ｄ₂₂…を利用する。
【００２６】
上記定義式は、回転非対称な曲面形状の面の例示のために示したものであり、他のいかなる定義式に対しても同じ効果が得られることは言うまでもない。
【００２７】
なお、自由曲面の他の定義式の例として、次の定義式（ｃ）があげられる。
【００２８】
Ｚ＝ΣΣＣ_nmＸＹ
例として、ｋ＝７（７次項）を考えると、展開したとき、以下の式で表せる。
【００２９】

なお、回転非対称な曲面形状の面としては、アナモフィック面、トーリック面を用いることもできる。
【００３０】
また、本発明においては、前記のように、観察光学系をプリズム部材にて形成し、反射面の何れもがプリズム部材の表面に形成された裏面反射面にて構成するようにしてもよい。
【００３１】
この場合、観察光学系は、３次元光路振り分け部を構成する３次元光路振り分けプリズムと、３次元光路振り分けプリズムと空気間隔を挟んで分離され、左接眼部を構成する左接眼プリズムと右接眼部を構成する右接眼プリズムとを含んで構成されているようにすることができる。
【００３２】
そして、光路振り分けプリズムが、少なくとも画像表示素子に対向し左眼用光路を形成する画像光束と右眼用光路を形成する画像光束の両方の光束をプリズム内に入射させる入射面と、左眼用光路の光束をプリズム外に射出する左側射出面と、入射面と左側射出面との間の光路上に配置されかつ左眼用光路の光束をプリズム内で反射する少なくとも３面以上の左側反射面と、右眼用光路の光束をプリズム外に射出する右側射出面と、入射面と右側射出面との間の光路上に配置されかつ右眼用光路の光束をプリズム内で反射する少なくとも３面以上の右側反射面とを含んで構成され、
その少なくとも３面以上の左側反射面の中の入射面に対して左眼用光路上最も近い位置に配置された反射面に入射する軸上主光線とそこから反射する軸上主光線とを含む左第１平面と、その少なくとも３面以上の右側反射面の中の入射面に対して右眼用光路上最も近い位置に配置された反射面に入射する軸上主光線とそこから反射する軸上主光線とを含む右第１平面とが、同一の第１平面内に一致するように構成されていることが望ましい。
【００３３】
この場合、その第１平面が、左接眼部の偏心光路面と右接眼部の偏心光路面とを含む略同一平面である第２平面に対して、異なる平面からなり、かつ、第１平面と第２平面とが平行な位置関係を形成するように、観察光学系が構成されていることが望ましい。
【００３４】
なお、ここで、左右の接眼部の偏心光路面が略同一平面にあるとは、製作誤差等による微小角度のずれを包含する意味であり、±１°とする。
【００３５】
また、少なくとも３面以上の左側反射面の中、２つの左側反射面が、第１平面に対して垂直方向に隣接配置され、かつ、少なくとも３面以上の右側反射面の中、２つの右側反射面が、第１平面に対して垂直方向に隣接配置されるように光路振り分けプリズムが構成されていることが望ましい。
【００３６】
また、第２平面に対して垂直な方向の成分をも含めた３次元偏心方向に左右各々の光束の軸上主光線を反射させる少なくとも左右２組の反射面の中、１組の左側反射面と右側反射面について、左側反射面と左側射出面とが第１平面に対して垂直方向に隣接配置され、かつ、右側反射面と右側射出面とが第１平面に対して垂直方向に隣接配置されているようにすることができる。
【００３７】
また、入射面に対して左眼用光路上最も近い位置に配置された反射面と、入射面に対して右眼用光路上最も近い位置に配置された反射面とが共に、画像表示素子と入射面の双方に対して対向するように隣接配置されていることが望ましい。
【００３８】
この場合に、光路振り分けプリズムが、入射面に対して光路上最も近い位置に配置された左右の反射面の境界部分を含む領域に対して、画像表示素子の中心領域から垂直に放射された光線がゴースト光として反射しないように反射防止部材を設けることが望ましい。
【００３９】
また、画像表示素子と３次元光路振り分け部との間に、その１枚の画像表示素子の少なくとも中央部分に位置する各画素から放射される所定の射出角度を持った画像光束の光強度を各画素面の垂直方向に放射される光束強度より強くするような振り分け光増強部材を配置することが望ましい。
【００４０】
また、光路振り分けプリズムは、少なくとも３面以上の左側反射面によって画像表示素子から放射された左眼用光路の軸上主光線をプリズム内で回転交差させると共に、少なくとも３面以上の右側反射面によって前記画像表示素子から放射された右眼用光路の軸上主光線を前記プリズム内で回転交差させ、かつ、左側反射面による回転方向と右側反射面による回転方向とが逆回転となるように構成されていることが望ましい。
【００４１】
この場合に、光路振り分けプリズムが、左側反射面によって形成された左眼用光路の軸上主光線の回転交差平面が左第１平面と同一平面内に形成され、かつ、右側反射面によって形成された右眼用光路の軸上主光線の回転交差平面が右第１平面内に形成されるように構成されていることが望ましい。
【００４２】
また、３次元光路振り分け部に含まれる左右対称な複数組の反射面が、画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも第１反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることが望ましい。
【００４３】
また、３次元光路振り分け部に含まれる左右対称な複数組の反射面が、画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも第２反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることが望ましい。
【００４４】
また、３次元光路振り分け部に含まれる左右対称な複数組の反射面が、画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも第３反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることが望ましい。
【００４５】
また、３次元光路振り分け部に含まれる左右対称な複数組の反射面が、画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも第４反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることが望ましい。
【００４６】
これらの場合、３次元光路振り分け部の左眼用光路の第３反射面に入射する軸上主光線とそこから反射する軸上主光線と左眼用光路の第４反射面で反射する軸上主光線とが同一の左第２平面内に含まれ、右眼用光路の第３反射面に入射する軸上主光線とそこから反射する軸上主光線と右眼用光路の第４反射面で反射する軸上主光線とが同一の右第２平面内に含まれ、左第２平面と右第２平面は、第１平面に垂直に設定されていることが望ましい。
【００４７】
また、３次元光路振り分け部に含まれる回転非対称形状の曲面反射面が、対称面を１面のみ備えた自由曲面形状にて構成されていることが望ましい。
【００４８】
また、左接眼プリズムと右接眼プリズムが共に、３次元光路振り分けプリズム側から順に、入射面と第１反射面と第２反射面と射出面とからなり、第１反射面と射出面は同一面からなり、第１反射面はその面での全反射による反射面であるようなものとすることができる。
【００４９】
【発明の実施の形態】
以下、本発明の３次元偏心光路を備えた画像表示装置を実施例に基づいて説明する。
【００５０】
以下の実施例の座標の取り方は、観察者の視軸方向（正面方向）をＺ軸、水平方向をＹ軸、垂直方向をＸ軸としている。
【００５１】
後記する各実施例の数値データにおいては、右眼用の観察光学系について示してあり、右眼用の瞳１からの画像表示素子（像面）３に至る逆光線追跡のデータで示してある。左眼用の観察光学系については、数値データは省いてあるが、両眼を結ぶ直線の中心を通る対称面に対して面対称の関係である。なお、以下の構成の説明もその逆光線追跡の順で説明する。
【００５２】
以下に示す実施例１〜２において、接眼プリズム１０はＹ−Ｚ面内における２次元元偏心の偏心プリズムからなり、画像表示素子３側に配置される光路振り分けプリズム２０は３次元元偏心の偏心プリズムであり、光路振り分けプリズム２０内の軸上主光線は同一平面内に存在せずＹ−Ｚ面とそれに平行な２つの平面とそれに直交する１つの平面内に存在する。以下、図面を参照にして説明する。
【００５３】
実施例１
図１に実施例１の画像表示装置の光学系の主として右眼用部分の斜視図、図２に実施例１の光学系の軸上主光線２を示す透視斜視図、図３に異なる角度から見た実施例１の光学系の軸上主光線２を示す透視斜視図をそれぞれ示す。ただし、図１〜図３において面はメッシュで表現してある。また、図４に実施例１の画像表示装置の光学系の主として右眼用部分の光学面と光路を示す図を示す。ただし、（ａ）はＺ軸正方向から見た右眼用光路の正面図、（ｂ）はＸ軸負方向から見た右眼用光路の平面図、（ｃ）はＸ軸負方向から見た第１の水平面内での両眼の光路を示す図、（ｄ）はＸ軸負方向から見た第１の水平面と平行で第１の水平面より上（Ｘ軸の負側）の第２の水平面内での両眼の光路を示す図である。
【００５４】
この光学系は、両眼装着型の頭部装着式画像表示装置として構成する場合の右眼用の光学系であり、左眼用の光学系は、Ｘ−Ｚ面に平行で、両眼を結ぶ直線の中心を通る面に対して面対称に構成される。以下の実施例２も同様。なお、図１〜図４には、左眼用の接眼プリズム１０’も図示してある。
【００５５】
この実施例の観察光学系は、頭部装着式画像表示装置として構成する場合に観察者の右眼の瞳が位置すべき瞳１から出た逆光線追跡の軸上主光線（光軸）２は、保護ガラス４（図１〜図３においては図示略）を経て、接眼プリズム１０の第１１面１１で屈折されて接眼プリズム１０内に入り、第１２面１２で内部反射され、第１１面１１が兼ねる第１３面１３に臨界角を越える角度で入射して全反射され、第１４面１４で屈折されて接眼プリズム１０から出て、光路振り分けプリズム２０の第２１面２１で屈折されて光路振り分けプリズム２０内に入り、第２２面２２で内部反射され、第２３面２３で内部反射され、第２４面２４で内部反射され、第２５面２５で内部反射され、第２６面２６で屈折されて光路振り分けプリズム２０から出て、画像表示素子３に至る。
【００５６】
ここで、接眼プリズム１０の第１１面１１〜第１４面１４はＹ−Ｚ面に対して面対称に構成されており、各面はこのＹ−Ｚ面内で２次元的に偏心して構成されている。
【００５７】
接眼プリズム１０から出た軸上主光線は、第２１面２１から光路振り分けプリズム２０内に入射し、接眼プリズム１０の偏心面（Ｙ−Ｚ面：第１の水平面Ｈ１（図４（ｃ）の面））内を進み、その第２２面２２の反射面で接眼プリズム１０の偏心面（Ｙ−Ｚ面）と垂直な面Ｈ３（Ｘ軸と平行な面）内に反射され、その反射光は第２３面２３の反射面で反射され、その反射光は第１の水平面Ｈ１と平行でそれより上（Ｘ軸の負側）の第２の水平面Ｈ２（図４（ｄ）の面）内を進み、第２４面２４の反射面で反射されて第２の水平面Ｈ２内を進み、第２５面２５の反射面で反射されてその第２の水平面Ｈ２内で第２４面２４に入射する軸上主光線と交差した後、第２６面２６で屈折されて画像表示素子３の中心に、画像表示素子３の中心を通る法線に対して−１９．５７°（図６（ｂ））の角度をなして入射する。光路振り分けプリズム２０の第２１面２１の上方（Ｘ軸の負側）に第２３面２３が、第２２面２２の上方（Ｘ軸の負側）に第２４面２４が配置されており、画像表示素子３の表示面はＸ−Ｙ面に平行で、左右の瞳の間の中心を通る対称面にその中心が一致するように配置されている。
【００５８】
そして接眼プリズム１０、光路振り分けプリズム２０共に正のパワーを有するように、それぞれの少なくとも１つの反射面は正パワーを有するように構成され、画像表示素子３の中間像を光路振り分けプリズム２０の第２１面２１と第２２面２２の間に結像する。
【００５９】
このように、観察光学系を３次元的に偏心させることで、光学系を自由な方向に折り畳むことができ、画像表示装置全体を小型化することができ、他の部材を考慮してデットスペースの少ない画像表示装置を提供することができる。さらには、デザインの自由度が大きくなる。また、光路振り分けプリズム２０内の反射面を垂直方向に２段に配置するようにして、画角を広くした場合でも、両眼の反射面の有効径を確保できるようにしている。
【００６０】
この実施例においては、光路振り分けプリズム２０の第２２面２２の反射面を、接眼プリズム１０の偏心面と垂直方向（本実施例ではＸ方向）に偏心させることで、第２２面２２で反射した像はＸ軸方向に傾く。その後、第２３面２３の反射面でＸ軸方向の像の傾きを０にするように反射面を構成することで、像の傾きが発生しないようにしている。このような構成にすることで、両眼の画像がＹ軸方向の傾きのみとなり、融像して観察することが可能となる。像面３上にてＸ方向とＹ方向の両方に対して像の傾きが発生した場合、画像表示素子３上に射影される像は軸上主光線を軸として左右逆方向に回転した像となり、両眼の画像を融像することができなくなる。また、第２３面２３から第２５面２５までの反射面は、第２１面２１及び第２２面２２の上下方向（Ｘ軸方向）に配置することができるため、光路振り分けブリズム２０内の各反射面の干渉を防ぐことができる。さらに、上記Ｘ軸方向は、瞳の長手方向とは垂直方向になるため、大きく偏心させずに各面を構成することができ、Ｘ軸に非対称な偏心収差の発生量を小さく抑えることができる。
【００６１】
実施例１の構成における瞳座標に対する像の傾きを図示したものが図５、図６（ａ）〜（ｂ）である（図５は図４（ｃ）に対応、図６（ａ）は図４（ａ）に対応、図６（ｂ）は図４（ｄ）に対応）。これらの図中、Ｘ、Ｙは像の方向、Ｚは光の進行方向を示す。図５は、瞳１から第２２面２２までの両眼の光路図で、Ｙ−Ｚ平面内で偏心させている。図６（ａ）は、第２４面２４までの右眼用光路を示した図で、第２１面２１から第２４面２４までは、Ｙ−Ｚ面に垂直なＸ方向に偏心させている。図６（ｂ）は、第２３面２３から像面（画像表示素子）３までの両眼の光路図で、Ｙ−Ｚ平面内で偏心させている。ただし、これらの図は、簡単のため、各面を平面の反射鏡としたときの像の方向を図示したものであり、結像作用は考慮していない。実際には、この実施例では中間像を形成しているため、途中の中間像の位置でＸ方向、Ｙ方向が逆向きの像が形成されることとなる。
【００６２】
本実施例においては、接眼プリズム１０の偏心面を水平方向になるようにしているので、接眼プリズム１０の縦方向の寸法が非常に小さくでき、小型軽量化が達成できる。また、光路振り分けプリズム２０を３次元的に偏心させているため、より広い画角が達成できる。また、中間像を１回結像しているため、光路振り分けプリズム２０の高さは、接眼プリズム１０の高さよりも小さく、光路振り分けプリズム２０を３次元的に偏心させても、装置の小型化が達成できる。また、中間像から画像表示素子３までの物像間距離が長くとれ、光路振り分けプリズム２０の各面のパワーを弱く設定することができる。そのため、画像表示素子３の表示面上で良好な性能を確保することができる。また、この実施例においては、画像表示素子３を光路振り分けプリズム２０に対して観察者と反対側に配置できるため、画像表示素子３及びそのためのバックライトを配置するスペース上の問題は発生し難い。
【００６３】
さらに、この実施例においては、光路振り分けプリズム２０に４つの反射面２２〜２５があり、その中の２つの反射面２２、２３はＸ軸方向に偏心させ、２つの反射面２４、２５はＹ軸方向に偏心させているため、３次元的に光路をとっても良好な偏心収差補正が可能となる。
【００６４】
なお、接眼プリズム１０と瞳１の間にある平行平板４は保護ガラス用として挿入したものである。この保護ガラス４に正のパワーを付けることで、より広い画角がとれることは言うまでもない。
【００６５】
実施例２
図７に実施例２の図４と同様の図を示す。この実施例の観察光学系は、頭部装着式画像表示装置として構成する場合に観察者の右眼の瞳が位置すべき瞳１から出た逆光線追跡の軸上主光線（光軸）２は、保護ガラス４を経て、接眼プリズム１０の第１１面１１で屈折されて接眼プリズム１０内に入り、第１２面１２で内部反射され、第１１面１１が兼ねる第１３面１３に臨界角を越える角度で入射して全反射され、第１４面１４で屈折されて接眼プリズム１０から出て、光路振り分けプリズム２０の第２１面２１で屈折されて光路振り分けプリズム２０内に入り、第２２面２２で内部反射され、第２３面２３で内部反射され、第２４面２４で内部反射され、第２５面２５で屈折されて光路振り分けプリズム２０から出て、画像表示素子３に至る。
【００６６】
ここで、接眼プリズム１０の第１１面１１〜第１４面１４はＹ−Ｚ面に対して面対称に構成されており、各面はこのＹ−Ｚ面内で２次元的に偏心して構成されている。
【００６７】
接眼プリズム１０から出た軸上主光線は、第２１面２１から光路振り分けプリズム２０内に入射し、接眼プリズム１０の偏心面（Ｙ−Ｚ面：第１の水平面Ｈ１（図４（ｃ）の面））内を進み、その第２２面２２の反射面で接眼プリズム１０の偏心面（Ｙ−Ｚ面）と垂直な面Ｈ３（Ｘ軸と平行な面）内に反射され、その反射光は第２３面２３の反射面で反射され、その反射光は第１の水平面Ｈ１と平行でそれより上（Ｘ軸の負側）の第２の水平面Ｈ２（図４（ｄ）の面）内を進み、第２４面２４の反射面で反射されて第２の水平面Ｈ２内を進み、第２５面２５で屈折されて画像表示素子３の中心に、画像表示素子３の中心を通る法線に対して−３１．３２°の角度をなして入射する。光路振り分けプリズム２０の第２１面２１の上方（Ｘ軸の負側）に第２３面２３が、第２２面２２の上方（Ｘ軸の負側）に第２４面２４が配置されており、画像表示素子３の表示面はＸ−Ｙ面に平行で、左右の瞳の間の中心を通る対称面にその中心が一致するように配置されている。
【００６８】
そして接眼プリズム１０、光路振り分けプリズム２０共に正のパワーを有するように、それぞれの少なくとも１つの反射面は正パワーを有するように構成され、画像表示素子３の中間像を光路振り分けプリズム２０の第２１面２１と第２２面２２の間に結像する。
【００６９】
このように、観察光学系を３次元的に偏心させることで、光学系を自由な方向に折り畳むことができ、画像表示装置全体を小型化することができ、他の部材を考慮してデットスペースの少ない画像表示装置を提供することができる。さらには、デザインの自由度が大きくなる。また、光路振り分けプリズム２０内の反射面を垂直方向に２段に配置するようにして、画角を広くした場合でも、両眼の反射面の有効径を確保できるようにしている。
【００７０】
実施例２においても、実施例１と同様、光路振り分けプリズム２０の第２２面２２の反射面を、接眼プリズム１０の偏心面と垂直方向（本実施例ではＸ方向）に偏心させることで、第２２面２２で反射した像はＸ軸方向に傾く。その後、第２３面２３の反射面でＸ軸方向の像の傾きを０にするように反射面を構成することで、像の傾きが発生しないようにしている。このような構成にすることで、両眼の画像がＹ軸方向の傾きのみとなり、融像して観察することが可能となる。像面３上にてＸ方向とＹ方向の両方に対して像の傾きが発生した場合、画像表示素子３上に射影される像は軸上主光線を軸として左右逆方向に回転した像となり、両眼の画像を融像することができなくなる。また、第２３面２３から第２４面２４までの反射面は、第２１面２１及び第２２面２２の上下方向（Ｘ軸方向）に配置することができるため、光路振り分けブリズム２０内の各反射面の干渉を防ぐことができる。さらに、上記Ｘ軸方向は、瞳の長手方向とは垂直方向になるため、大きく偏心させずに各面を構成することができ、Ｘ軸に非対称な偏心収差の発生量を小さく抑えることができる。
【００７１】
本実施例においては、接眼プリズム１０の偏心面を水平方向になるようにしているので、接眼プリズム１０の縦方向の寸法が非常に小さくでき、小型軽量化が達成できる。また、光路振り分けプリズム２０を３次元的に偏心させているため、より広い画角が達成できる。また、中間像を１回結像しているため、光路振り分けプリズム２０の高さは、接眼プリズム１０の高さよりも小さく、光路振り分けプリズム２０を３次元的に偏心させても、装置の小型化が達成できる。また、中間像から画像表示素子３までの物像間距離が長くとれ、光路振り分けプリズム２０の各面のパワーを弱く設定することができる。そのため、画像表示素子３の表示面上で良好な性能を確保することができる。また、この実施例においては、画像表示素子３を光路振り分けプリズム２０の観察者側に配置しているが、画像表示素子３が眼の位置に対して少し上側に存在するため（光路振り分けプリズム２０が２段構成の３次元構成にしてあるため) 、画像表示素子３と観察者の鼻との干渉は起こり難い。
【００７２】
さらに、この実施例においては、光路振り分けプリズム２０に３つの反射面２２〜２４があり、その中の２つの反射面２２、２３はＸ軸方向に偏心させ、１つの反射面２４はＹ軸方向に偏心させているため、３次元的に光路をとっても良好な偏心収差補正が可能となる。
【００７３】
なお、接眼プリズム１０と瞳１の間にある平行平板４は保護ガラス用として挿入したものである。この保護ガラス４に正のパワーを付けることで、より広い画角がとれることは言うまでもない。
【００７４】
次に、上記実施例１〜２の構成パラメータを示す。各実施例の構成パラメータにおいては、逆光線追跡で、軸上主光線２を、光学系の射出瞳１の中心を垂直に通り、画像表示素子３中心に至る光線で定義する。そして、逆光線追跡において、瞳１の中心を偏心光学系の偏心光学面の原点として、軸上主光線２に沿う方向をＺ軸方向とし、瞳１から第１１面１１に向かう方向をＺ軸正方向とし、接眼プリズム１０内で光軸が折り曲げられる平面をＹ−Ｚ平面とし、原点を通りＹ−Ｚ平面に直交し、垂直方向の上から下へ向かう方向をＸ軸正方向とし、Ｘ軸、Ｚ軸と右手直交座標系を構成する軸をＹ軸とする。この座標系は、図４、図７に図示してある座標系と同じである。
【００７５】
偏心面については、光学系の原点の中心からその面の面頂位置の偏心量（Ｘ軸方向、Ｙ軸方向、Ｚ軸方向をそれぞれＸ，Ｙ，Ｚ）と、その面の中心軸（自由曲面については、前記（ａ）式のＺ軸、非球面については、後記の（ｄ）式のＺ軸）のＸ軸、Ｙ軸、Ｚ軸それぞれを中心とする傾き角（それぞれα，β，γ（°））とが与えられている。その場合、αとβの正はそれぞれの軸の正方向に対して反時計回りを、γの正はＺ軸の正方向に対して時計回りを意味する。なお、面の中心軸のα，β，γの回転のさせ方は、面の中心軸とそのＸＹＺ直交座標系を、まずＸ軸の回りで反時計回りにα回転させ、次に、その回転した面の中心軸を新たな座標系のＹ軸の回りで反時計回りにβ回転させると共に１度回転した座標系もＹ軸の回りで反時計回りにβ回転させ、次いで、その２度回転した面の中心軸を新たな座標系の新たな座標系のＺ軸の回りで時計回りにγ回転させるものである。
【００７６】
また、各実施例の光学系を構成する光学作用面の中、特定の面とそれに続く面が共軸光学系を構成する場合には面間隔が与えられており、その他、媒質の屈折率、アッベ数が慣用法に従って与えられている。
【００７７】
また、本発明で用いられる自由曲面の面の形状は前記（ａ）式により定義し、その定義式のＺ軸が自由曲面の軸となる。
【００７８】
また、非球面は、以下の定義式で与えられる回転対称非球面である。
【００７９】

ただし、Ｚを光の進行方向を正とした光軸（軸上主光線）とし、ｙを光軸と垂直な方向にとる。ここで、Ｒは近軸曲率半径、Ｋは円錐定数、Ａ、Ｂ、Ｃ、Ｄ、…はそれぞれ４次、６次、８次、１０次の非球面係数である。この定義式のＺ軸が回転対称非球面の軸となる。
【００８０】
なお、データの記載されていない自由曲面、非球面に関する項は０である。屈折率については、ｄ線（波長５８７．５６ｎｍ）に対するものを表記してある。
長さの単位はｍｍである。
【００８１】
なお、実施例１〜２は、観察光学系とした場合に、観察画角は、水平半画角１２．５°、垂直半画角９．４°、画像表示素子３の大きさは１０．２×７．６ｍｍであり、瞳径４ｍｍある。
【００８２】
なお、以下の構成パラメータの表中の“ＦＦＳ”は自由曲面、“ＡＳＳ”は非球面、“ＲＥ”は反射面をそれぞれ示す。
【００８３】

【００８４】

【００８５】
ところで、本発明の画像表示装置においては、単一の画像表示素子３から射出されたある程度広がりのある射出角度の表示光束を左右の光路に分離して光路振り分けプリズム２０の入射面２６（実施例１）又は２５（実施例２）に入射させ、左右の接眼光学系１０、１０’を通して両眼で観察可能にするものであるが、図８（ａ）に示すように、そのための左右共通の画像表示素子３としては、白色バックライト３２で均一に照明され、左右の光路の光軸間のなす角度φより大きな射出角度で表示光束を射出させる液晶表示素子３１からなる画像表示素子３が用いられる。また、表示の射出角度が大きなＥＬ素子のような自己発光型素子を画像表示素子３として用いることもできる。
【００８６】
また、表示の射出角度が小さな画像表示素子３３を画像表示素子３として用いる場合には、図８（ｂ）に示すように、各画素３４から放射される表示の射出角度を垂直方向でなく左右の光路方向に射出角度を増やす振り分け光増強部材として、例えば図示のような断面の光束振り分けマイクロプリズム３５を各画素３４に対応して配置することが望ましい。その代わりに、０次透過光の強度を弱め、±１次回折光を強める構成の透過型回折格子を画像表示素子３の表示面に近接して配置してもよい。
【００８７】
ところで、光路振り分けプリズム２０の入射面２６（実施例１）又は２５（実施例１）に対して光路上最も近い位置に配置された左右の反射面２５（実施例１）又は２４（実施例２）の境界部分２９に画像表示素子３から射出された表示光束が当たると、そこで反射されてゴースト光となる恐れがある。そこで、図８（ｃ）に示すように、その境界部分２９近傍にこのような反射を防止する反射防止部材３６として黒色塗料を塗布するか拡散処理等をして、画像表示素子３から射出された表示光束３７中の境界部分２９に入射する破線で示した光束部分を吸収等させることが望ましい。なお、表示光束３７中の実線で示した光束部分が左右の光路に導かれ、有効に表示に使用される光束を表す。
【００８８】
さて、以上に説明したような観察光学系を支持することにより、両眼装着用の画像表示装置に構成することができ、両眼で観察できる据え付け型又はポータブル型の画像表示装置として構成することができる。
【００８９】
その様子を図９に示す。図中、１３１は表示装置本体部を示し、観察者の顔面の両眼の前方に保持されるよう支持部材が頭部を介して固定している。その支持部材としては、一端を表示装置本体部１３１に接合し、観察者のこめかみから耳の上部にかけて延在する左右の前フレーム１３２と、前フレーム１３２の他端に接合され、観察者の側頭部を渡るように延在する左右の後フレーム１３３と、左右の後フレーム１３３の他端に挟まれるように自らの両端を一方づつ接合し、観察者の頭頂部を支持する頭頂フレーム１３４とから構成されている。
【００９０】
また、前フレーム１３２における上記の後フレーム１３３との接合近傍には、弾性体からなり例えば金属板バネ等で構成されたリヤプレート１３５が接合されている。このリヤプレート１３５は、上記支持部材の一翼を担うリヤカバー１３６が観察者の後頭部から首のつけねにかかる部分で耳の後方に位置して支持可能となるように接合されている。リヤプレート１３５又はリヤカバー１３６内にの観察者の耳に対応する位置にスピーカー１３９が取り付けられている。
【００９１】
映像・音声信号等を外部から送信するためのケーブル１４１が表示装置本体部１３１から、頭頂フレーム１３４、後フレーム１３３、前フレーム１３２、リヤプレート１３５の内部を介してリヤプレート１３５あるいはリヤカバー１３６の後端部より外部に突出している。そして、このケーブル１４１はビデオ再生装置１４０に接続されている。なお、図中、１４０ａはビデオ再生装置１４０のスイッチやボリュウム調整部である。
【００９２】
なお、ケーブル１４１は先端をジャックして、既存のビデオデッキ等に取り付け可能としてもよい。さらに、ＴＶ電波受信用チューナーに接続してＴＶ鑑賞用としてもよいし、コンピュータに接続してコンピュータグラフィックスの映像や、コンピュータからのメッセージ映像等を受信するようにしてもよい。また、邪魔なコードを排斥するために、アンテナを接続して外部からの信号を電波によって受信するようにしても構わない。
【００９３】
また、本発明の画像表示装置の観察光学系は、瞳１側から被写体からの光を導入し、画像表示素子３の位置に撮像素子を配することにより結像光学系として用いることも可能である。図１０に本発明の観察光学系の左右の片側のみの光学系を電子カメラ４０の撮影部の撮影用対物光学系４２に組み込んだ構成の概念図を示す。もちろん、本発明の観察光学系の左右の両方の光学系を用いてもよい（入射瞳が２個の光学系になる。）。この例の場合は、撮影用光路４１上に配置された撮影用対物光学系４２は、実施例１と同様の光学系を光路を逆にして用いており、瞳１の位置に絞り１’を配置している。この撮影用対物光学系４２により形成された物体像は、ローパスフィルター、赤外カットフィルター等のフィルター４４を介してＣＣＤ４５の撮像面４６上に形成される。このＣＣＤ４５で受光された物体像は、処理手段５１を介し、液晶表示素子（ＬＣＤ）５２上に電子像として表示される。また、この処理手段５１は、ＣＣＤ４５で撮影された物体像を電子情報として記録する記録手段５４の制御も行う。ＬＣＤ５２に表示された画像は、接眼プリズム１０と同様な偏心プリズムからなる接眼光学系５３を介して観察者眼球Ｅに導かれる。この接眼光学系５３としては、本発明による片側の接眼プリズム１０と光路振り分けプリズム２０からなる３次元偏心光学系を用いてもよい。なお、この撮影用対物光学系４２は他のレンズ（正レンズ、負レンズ）をプリズム１０の物体側あるいはプリズム２０の像側にその構成要素として含んでいてもよい。
【００９４】
このように構成されたカメラ４０は、撮影用対物光学系４２を少ない光学部材で構成でき、装置全体を小型化することができ、低価格で、他の部材を考慮してデットスペースの少ないカメラとすることができると共に、デザインの自由度が大きなものとなる。
【００９５】
なお、本例では、撮影用対物光学系４２のカバー部材４３はとして、平行平面板を配置しているが、パワーを持ったレンズを用いてもよい。
【００９６】
また、本発明の観察光学系の左右の片側のみの光学系は、画像表示素子３の位置に投影用の像面を配置し、瞳１の前方にスクリーンを配置することにより投影光学系としても用いることができる。もちろん、この場合も、本発明の観察光学系の左右の両方の光学系を用いてもよい（射出瞳が２個の光学系になる。）。図１１に、パソコン９０と液晶プロジェクタ９１とを組み合わせたプレゼンテーションシステムの投影光学系９６に本発明による偏心プリズム光学系を用いた構成の概念図を示す。この例の場合は、投影光学系９６に実施例１と同様の光学系を用いている。同図において、パソコン９０上で作成された画像・原稿データは、モニタ出力から分岐して液晶プロジェクタ９１の処理制御部９８に出力される。液晶プロジェクタ９１の処理制御部９８では、この入力されたデータが処理され、液晶パネル（ＬＣＰ）９３に出力される。液晶パネル９３では、この入力画像データに応じた画像が表示される。そして、光源９２からの光は、液晶パネル９３に表示した画像の階調によってその透過量が決定された後、液晶パネル９３直前に配置したフィールドレンズ９５と本発明の光学系を構成するプリズム２０、１０と正レンズのカバーレンズ９４とからなる投影光学系９６を介してスクリーン９７に投影される。
【００９７】
このように構成されたプロジェクタは、少ない光学部材で構成でき、低コスト化が実現できると共に、小型化が可能である。
【００９８】
以上の本発明の３次元偏心光路を備えた画像表示装置は、例えば次のように構成することができる。
【００９９】
〔１〕 観察画像を画像表示部に形成する画像表示素子と、前記画像表示素子が形成した画像を観察者眼球位置に相当する瞳に導く観察光学系とを含んだ画像表示装置において、
前記画像表示素子が、複数の画素を単板上に並設させた１枚の画像表示素子を有して構成され、
前記１枚の画像表示素子の少なくとも中央部分に位置する各画素が、観察者の左右の眼球に光束を導けるような射出角度で画像光束を放射するように構成され、
前記観察光学系が、少なくとも、観察者の左眼に光束を導く左接眼部と、観察者の右眼に光束を導く右接眼部と、前記画像表示素子から前記射出角度を持って放射された画像光束を前記左右の接眼部に導く３次元光路振り分け部とを含み、
前記左接眼部が、少なくとも２面以上の反射面を有し、その中の少なくとも１つの反射面が偏心収差補正機能を有した回転非対称な曲面反射面にて構成され、
前記右接眼部が、少なくとも２面以上の反射面を有し、その中の少なくとも１つの反射面が偏心収差補正機能を有した回転非対称な曲面反射面にて構成され、
前記左接眼部の有する前記２面以上の反射面にて形成される軸上主光線の偏心光路面（Ｙ−Ｚ面）と、前記右接眼部の有する前記２面以上の反射面にて形成される軸上主光線の偏心光路面（Ｙ−Ｚ面）とが、同一平面（Ｙ−Ｚ面）に形成されるように、前記左右接眼部が構成され、
前記３次元光路振り分け部は、左右対称な光路を形成できるように、左右対称に光学面が配置され、かつ、前記光学面の中、少なくとも左右２組の反射面が、前記左右の接眼部によって形成される偏心光路面（Ｙ−Ｚ面）に対して垂直な方向（Ｘ方向）の成分をも含めた３次元偏心方向に左右各々の光束の軸上主光線を反射させるように構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１００】
〔２〕 上記１において、
前記３次元光路振り分け部が、偏心収差補正機能を有した回転非対称な曲面形状の反射面を少なくとも１組備えていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０１】
〔３〕 上記２において、
前記の少なくとも１組の偏心収差補正機能を有した回転非対称な曲面形状の反射面は、前記の３次元偏心方向に左右各々の光束の軸上主光線を反射させる少なくとも左右２組の反射面の中の１組に配置されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０２】
〔４〕 上記２において、
前記の少なくとも１組の偏心収差補正機能を有した回転非対称な曲面形状の反射面は、対称面を１面のみ有する自由曲面にて形成され、
前記の少なくとも１組の自由曲面の各々の唯一の対称面が同一平面内に一致するように構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０３】
〔５〕 上記１〜４の何れか１項において、
前記観察光学系が、プリズム部材にて形成され、前記反射面の何れもが前記プリズム部材の表面に形成された裏面反射面にて構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０４】
〔６〕 上記５において、
前記観察光学系は、前記３次元光路振り分け部を構成する３次元光路振り分けプリズムと、前記３次元光路振り分けプリズムと空気間隔を挟んで分離され、前記左接眼部を構成する左接眼プリズムと前記右接眼部を構成する右接眼プリズムとを含んで構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０５】
〔７〕 上記６において、
前記光路振り分けプリズムが、少なくとも前記画像表示素子に対向し左眼用光路を形成する画像光束と右眼用光路を形成する画像光束の両方の光束をプリズム内に入射させる入射面と、前記左眼用光路の光束を前記プリズム外に射出する左側射出面と、前記入射面と前記左側射出面との間の光路上に配置されかつ前記左眼用光路の光束を前記プリズム内で反射する少なくとも３面以上の左側反射面と、前記右眼用光路の光束を前記プリズム外に射出する右側射出面と、前記入射面と前記右側射出面との間の光路上に配置されかつ前記右眼用光路の光束を前記プリズム内で反射する少なくとも３面以上の右側反射面とを含んで構成され、
前記少なくとも３面以上の左側反射面の中の前記入射面に対して前記左眼用光路上最も近い位置に配置された反射面に入射する軸上主光線とそこから反射する軸上主光線とを含む左第１平面と、前記少なくとも３面以上の右側反射面の中の前記入射面に対して前記右眼用光路上最も近い位置に配置された反射面に入射する軸上主光線とそこから反射する軸上主光線とを含む右第１平面とが、同一の第１平面内に一致するように構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０６】
〔８〕 上記７において、
前記第１平面が、前記左接眼部の前記偏心光路面と前記右接眼部の前記偏心光路面とを含む同一平面である第２平面に対して、異なる平面からなり、かつ、前記第１平面と前記第２平面とが平行な位置関係を形成するように、前記観察光学系が構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０７】
〔９〕 上記８において、
前記少なくとも３面以上の左側反射面の中、２つの左側反射面が、前記第１平面に対して垂直方向に隣接配置され、かつ、前記少なくとも３面以上の右側反射面の中、２つの右側反射面が、前記第１平面に対して垂直方向に隣接配置されるように前記光路振り分けプリズムが構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０８】
〔１０〕 上記９において、
前記第２平面に対して垂直な方向の成分をも含めた３次元偏心方向に左右各々の光束の軸上主光線を反射させる少なくとも左右２組の反射面の中、１組の左側反射面と右側反射面について、前記左側反射面と前記左側射出面とが第１平面に対して垂直方向に隣接配置され、かつ、前記右側反射面と前記右側射出面とが前記第１平面に対して垂直方向に隣接配置されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１０９】
〔１１〕 上記７〜１０の何れか１項において、
前記入射面に対して前記左眼用光路上最も近い位置に配置された反射面と、前記入射面に対して前記右眼用光路上最も近い位置に配置された反射面とが共に、前記画像表示素子と前記入射面の双方に対して対向するように隣接配置されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１０】
〔１２〕 上記１１において、
前記光路振り分けプリズムが、前記入射面に対して光路上最も近い位置に配置された左右の反射面の境界部分を含む領域に対して、前記画像表示素子の中心領域から垂直に放射された光線がゴースト光として反射しないように反射防止部材を設けたことを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１１】
〔１３〕 上記１〜１２の何れか１項において、
前記画像表示素子と前記３次元光路振り分け部との間に、前記１枚の画像表示素子の少なくとも中央部分に位置する各画素から放射される所定の射出角度を持った画像光束の光強度を前記各画素面の垂直方向に放射される光束強度より強くするような振り分け光増強部材を配置したことを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１２】
〔１４〕 上記７〜１３の何れか１項において、
前記光路振り分けプリズムは、前記少なくとも３面以上の左側反射面によって前記画像表示素子から放射された前記左眼用光路の軸上主光線を前記プリズム内で回転交差させると共に、前記少なくとも３面以上の右側反射面によって前記画像表示素子から放射された前記右眼用光路の軸上主光線を前記プリズム内で回転交差させ、かつ、前記左側反射面による回転方向と前記右側反射面による回転方向とが逆回転となるように構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１３】
〔１５〕 上記１４において、
前記光路振り分けプリズムが、前記左側反射面によって形成された前記左眼用光路の軸上主光線の回転交差平面が前記左第１平面と同一平面内に形成され、かつ、前記右側反射面によって形成された前記右眼用光路の軸上主光線の回転交差平面が前記右第１平面内に形成されるように構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１４】
〔１６〕 上記１〜１５の何れか１項において、
前記３次元光路振り分け部に含まれる左右対称な複数組の反射面が、前記画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも前記第１反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１５】
〔１７〕 上記１〜１６の何れか１項において、
前記３次元光路振り分け部に含まれる左右対称な複数組の反射面が、前記画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも前記第２反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１６】
〔１８〕 上記１〜１７の何れか１項において、
前記３次元光路振り分け部に含まれる左右対称な複数組の反射面が、前記画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも前記第３反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１７】
〔１９〕 上記１〜１８の何れか１項において、
前記３次元光路振り分け部に含まれる左右対称な複数組の反射面が、前記画像表示素子側から順に、左右１組の第１反射面と、左右１組の第２反射面と、左右１組の第３反射面と、左右１組の第４反射面とから構成され、
少なくとも前記第４反射面が、光束にパワーを与える曲面反射面形状にて構成され、かつ、偏心収差補正機能を有した回転非対称形状にて構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１８】
〔２０〕 上記１６〜１９の何れか１項において、
前記３次元光路振り分け部の左眼用光路の第３反射面に入射する軸上主光線とそこから反射する軸上主光線と左眼用光路の第４反射面で反射する軸上主光線とが同一の左第２平面内に含まれ、右眼用光路の第３反射面に入射する軸上主光線とそこから反射する軸上主光線と右眼用光路の第４反射面で反射する軸上主光線とが同一の右第２平面内に含まれ、前記左第２平面と前記右第２平面は、前記第１平面に垂直に設定されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１１９】
〔２１〕 上記１〜２０の何れか１項において、
前記３次元光路振り分け部に含まれる回転非対称形状の曲面反射面が、対称面を１面のみ備えた自由曲面形状にて構成されていることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１２０】
〔２２〕 上記６〜２１の何れか１項において、
前記左接眼プリズムと前記右接眼プリズムが共に、前記３次元光路振り分けプリズム側から順に、入射面と第１反射面と第２反射面と射出面とからなり、前記第１反射面と前記射出面は同一面からなり、前記第１反射面はその面での全反射による反射面であることを特徴とする３次元偏心光路を備えた画像表示装置。
【０１２１】
【発明の効果】
以上の説明から明らかに、本発明によると、画像表示素子が１枚で両眼視できるため、コストが非常に安くなる。また、両眼に画像を振り分ける光路振り分けプリズムに自由曲面を用いているため、良好に収差補正ができる。また、ハーフミラーを使用していないため、明るい画像が観察できる。さらに、光路振り分けプリズムを３次元的に偏心させているため、画像表示素子が１枚で両眼視できる非常に広い画角の表示装置を提供することができる。さらに、接眼プリズムの偏心面を水平にしているため、幅の非常に小さい画像表示装置が提供でき、広いシーアラウンドが可能となる。
【図面の簡単な説明】
【図１】本発明の実施例１の画像表示装置の光学系の主として右眼用部分の斜視図である。
【図２】実施例１の光学系の軸上主光線を示す透視斜視図である。
【図３】異なる角度から見た実施例１の光学系の軸上主光線を示す透視斜視図である。
【図４】実施例１の画像表示装置の光学系の主として右眼用部分の光学面と光路を示す図である。
【図５】実施例１の構成における瞳座標に対する像の傾きを示した図である。
【図６】実施例１の構成における瞳座標に対する像の傾きを示した図である。
【図７】実施例２の画像表示装置の光学系の主として右眼用部分の光学面と光路を示す図である。
【図８】本発明において使用可能な画像表示素子、そのための振り分け光増強部材、反射防止部材を説明するための図である。
【図９】本発明の画像表示装置を両眼に装着する構成にした場合の様子を示す図である。
【図１０】本発明の光学系を電子カメラの撮影部の撮影用対物光学系に組み込んだ構成の概念図である。
【図１１】本発明による光学系をプレゼンテーションシステムの投影光学系に用いた構成の概念図である。
【符号の説明】
Ｅ…観察者の眼
１…瞳
１’…絞り
２…軸上主光線（光軸）
３…画像表示素子
４…保護ガラス
１０、１０’…接眼プリズム
１１…第１１面
１２…第１２面
１３…第１３面
１４…第１４面
２０…光路振り分けプリズム
２１…第２１面
２２…第２２面
２３…第２３面
２４…第２４面
２５…第２５面
２６…第２６面
２９…境界部分
３１…液晶表示素子
３２…白色バックライト
３３…画像表示素子
３４…画素
３５…光束振り分けマイクロプリズム
３６…反射防止部材
３７…表示光束
４０…電子カメラ
４１…撮影用光路
４２…撮影用対物光学系
４３…カバー部材
４４…フィルター
４５…ＣＣＤ
４６…撮像面
５１…処理手段
５２…液晶表示素子（ＬＣＤ）
５３…接眼光学系
５４…記録手段
９０…パソコン
９１…液晶プロジェクタ
９２…光源
９３…液晶パネル（ＬＣＰ）
９４…カバーレンズ
９５…フィールドレンズ
９６…投影光学系
９７…スクリーン
９８…処理制御部
１３１…表示装置本体部
１３２…前フレーム
１３３…後フレーム
１３４…頭頂フレーム
１３５…リヤプレート
１３６…リヤカバー
１３９…スピーカー
１４０…ビデオ再生装置
１４０ａ…ボリュウム調整部
１４１…ケーブル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display device having a three-dimensional eccentric optical path, and more particularly to a head- or face-mounted image display device that can be held on the head or face of an observer.
[0002]
[Prior art]
Conventionally, as a head-mounted image display device using a single image display element common to the left and right eyes, Japanese Patent Application Laid-Open No. 6-110013 guides display light from the image display element to the left and right eyes of an observer. In addition, it is divided by an isosceles triangular prism and mirror and bent. In this arrangement, correction of various aberrations is performed by a lens arranged in front of the pupil of the observer's eye, which makes correction difficult and increases the size of the apparatus.
[0003]
In Japanese Patent Laid-Open No. 7-287185, a plurality of mirrors are used and an image forming action is performed with a single convex lens. Therefore, assembly adjustment is very difficult, and appropriate performance cannot be achieved. Further, although the image display elements are arranged three-dimensionally, the left and right images are rotated in reverse.
[0004]
In JP-A-9-61748, display light from an image display element is divided using a half mirror and observed with both eyes. For this reason, the display light is divided into the left and right eyeballs, so the observation image intensity is weak and dark.
[0005]
Japanese Patent Laid-Open Nos. 9-181998 and 9-181999 use separate reflecting prism optical systems on the left and right sides, but have a problem that the angle of view is narrow.
[0006]
Furthermore, Japanese Patent Publication No. 10-504115 uses a half mirror to divide the display light, but has a very large number of parts and is very complicated to assemble.
[0007]
The present applicant has proposed a head-mounted image display device in which an optical path distribution optical system is arranged at the center and eyepiece prisms are arranged on the left and right sides thereof in Japanese Patent Application No. 2000-48750 and the like.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of such problems of the prior art, and its purpose is to guide a video from one image display element to both eyes without using a half mirror, and to observe brightly, It is another object of the present invention to provide an image display device such as a head-mounted image display device that facilitates correction of various aberrations by providing power to an optical path distribution optical system disposed in the center.
[0009]
Another object of the present invention is to further widen the angle of view of an image display device such as Japanese Patent Application No. 2000-48750 by the present applicant.
[0010]
[Means for Solving the Problems]
An image display device having a three-dimensional eccentric optical path of the present invention that achieves the above object corresponds to an image display element that forms an observation image on an image display unit, and an image formed by the image display element corresponds to an observer eyeball position. In an image display device including an observation optical system that leads to the pupil,
The image display element has a single image display element in which a plurality of pixels are arranged side by side on a single plate,
Each pixel located in at least the central portion of the one image display element is configured to emit an image light beam at an emission angle that can guide the light beam to the left and right eyeballs of an observer,
The observation optical system emits at least the left eyepiece that guides the light flux to the left eye of the observer, the right eyepiece that guides the light flux to the right eye of the observer, and the emission angle from the image display element. A three-dimensional optical path distribution unit that guides the imaged light flux to the left and right eyepieces,
The left eyepiece has at least two reflecting surfaces, and at least one of the reflecting surfaces is composed of a rotationally asymmetric curved reflecting surface having a decentration aberration correcting function,
The right eyepiece has at least two reflecting surfaces, and at least one of the reflecting surfaces is a rotationally asymmetric curved reflecting surface having a decentration correction function,
An eccentric optical path surface (YZ plane) of an axial principal ray formed by the two or more reflecting surfaces of the left eyepiece, and the two or more reflecting surfaces of the right eyepiece The left and right eyepieces are configured so that the decentered optical path surface (YZ plane) of the axial principal ray formed in the above is formed in substantially the same plane (YZ plane),
The three-dimensional optical path allocating unit has optical surfaces arranged symmetrically so as to form a bilaterally symmetric optical path, and at least two sets of right and left reflecting surfaces are the left and right eyepieces. The axial principal rays of the left and right light beams are reflected in the three-dimensional eccentric direction including the component in the direction (X direction) perpendicular to the eccentric optical path surface (YZ plane) formed by It is characterized by that.
[0011]
Hereinafter, the reason and effect | action which take the said structure in this invention are demonstrated.
[0012]
Usually, the distance between human eyes is said to be about 64 mm on average, and there are individual differences. Therefore, in the observation optical system for binocular observation, it is preferable to set the pupil of the optical system to be horizontally long in advance in order to absorb individual differences in eye widths with the observation optical system. That is, it is preferable to use an ellipse (or a rectangle or the like) that is long in the horizontal direction of the observer as the pupil of the observation optical system.
[0013]
At this time, if the longitudinal direction of the pupil and the eccentric direction of the eyepiece are made the same direction, the effective surface of each reflecting surface inevitably needs to ensure a long effective diameter. However, in the case of an optical system that is decentered only in the horizontal direction of the observer as in Japanese Patent Application No. 2000-48750, the optical system cannot be increased in the horizontal direction because of restrictions on the human eye width. Therefore, when the observation angle of view is widened, it becomes difficult to dispose the reflection surface of the optical path distribution unit between the eyepieces of both eyes.
[0014]
Therefore, in the observation optical system of the image display device of the present invention, the entire optical path in the optical path distribution unit is configured in a three-dimensional configuration, so that the reflection surface in the optical path distribution unit is arranged in the vertical direction, and the angle of view is set. Even in the case of widening, the effective diameter of the reflecting surfaces of both eyes can be secured.
[0015]
It should be noted that the left and right eyepieces and the three-dimensional optical path distribution units constituting the observation optical system may be configured by only reflecting mirrors, or the left and right eyepiece units and the three-dimensional optical path distribution units may be configured by eccentric prisms. Alternatively, the left and right eyepieces and the three-dimensional optical path distribution unit may be formed of an integral eccentric prism.
[0016]
The three-dimensional optical path distribution unit preferably includes at least one set of rotationally asymmetric curved surfaces having a decentration aberration correction function.
[0017]
In that case, the rotationally asymmetric curved reflecting surface having at least one set of decentration aberration correction function is at least of two sets of left and right reflecting surfaces that reflect the axial principal rays of the left and right light beams in the three-dimensional eccentric direction. It is desirable to arrange in one set.
[0018]
The rotationally asymmetric curved reflecting surface having at least one set of decentration aberration correction function is formed by a free curved surface having only one symmetrical surface, and each of the at least one set of free curved surfaces is the only one. It is desirable that the symmetry plane is configured to coincide with the same plane.
[0019]
Here, as a surface of a rotationally asymmetric curved surface shape, a free-form surface is typically used in the present invention. The free-form surface is defined by the following equation. The Z axis of this defining formula is the axis of the free-form surface.
[0020]

Here, the first term of the equation (a) is a spherical term, and the second term is a free-form surface term.
[0021]
In the spherical term,
c: vertex curvature
k: Conic constant (conical constant)
r = √ (X ² + Y ² )
It is.
[0022]
The free-form surface term is

However, C _j (J is an integer of 2 or more) is a coefficient.
[0023]
In general, the free-form surface does not have a symmetric surface in both the XZ plane and the YZ plane, but by setting all odd-order terms of X to 0, the plane of symmetry is parallel to the YZ plane. Is a free-form surface with only one. Further, by setting all odd-numbered terms of Y to 0, a free-form surface having only one symmetry plane parallel to the XZ plane is obtained.
[0024]
Further, another defining formula of the free-form surface which is a surface of the rotationally asymmetric curved surface can be defined by a Zernike polynomial. The shape of this surface is defined by the following formula (b). The Z axis of the defining formula (b) is the axis of the Zernike polynomial. The definition of the rotationally asymmetric surface is defined by polar coordinates of the height of the Z axis with respect to the XY plane, R is the distance from the Z axis in the XY plane, A is the azimuth around the Z axis, and the X axis It is expressed by the rotation angle measured from.
[0025]

However, D _m (M is an integer of 2 or more) is a coefficient. To design an optical system that is symmetric in the X-axis direction, D _Four , D _Five , D ₆ , D _Ten , D ₁₁ , D ₁₂ , D ₁₃ , D ₁₄ , D ₂₀ , D _{twenty one} , D _{twenty two} Use….
[0026]
The above definition formula is shown for illustration of a rotationally asymmetric curved surface, and it goes without saying that the same effect can be obtained for any other definition formula.
[0027]
In addition, the following definition formula (c) is mention | raise | lifted as an example of the other definition formula of a free-form surface.
[0028]
Z = ΣΣC _nm XY
As an example, when k = 7 (seventh order term) is considered, when expanded, it can be expressed by the following expression.
[0029]

An anamorphic surface or a toric surface can also be used as the rotationally asymmetric curved surface.
[0030]
In the present invention, as described above, the observation optical system may be formed by a prism member, and any of the reflection surfaces may be configured by a back surface reflection surface formed on the surface of the prism member.
[0031]
In this case, the observation optical system is separated from the three-dimensional optical path distributing prism constituting the three-dimensional optical path distributing unit and the three-dimensional optical path distributing prism with a space between the left eyepiece prism constituting the left eyepiece unit and the right eyepiece. A right eyepiece prism that constitutes the eye portion may be included.
[0032]
The optical path distribution prism has at least an incident surface for allowing both the image light beam forming the left eye optical path and the image light beam forming the right eye optical path to enter the prism. The left exit surface that emits the light flux of the optical path out of the prism, and the left reflective surface that is disposed on the optical path between the entrance surface and the left exit surface and that reflects the light flux of the optical path for the left eye within the prism. And at least three surfaces arranged on the optical path between the right exit surface and the right exit surface for emitting the light flux of the right eye optical path out of the prism and reflecting the light flux of the right eye optical path within the prism. Including the above right reflective surface,
Including an axial principal ray incident on a reflecting surface disposed at a position closest to the incident surface in the left-eye optical path with respect to an incident surface among at least three left-side reflecting surfaces, and an axial principal ray reflected therefrom An axial principal ray incident on a reflecting surface disposed at a position closest to the right first optical path and an incident surface in the right reflecting surface of at least three or more of the first left plane and an axis reflecting from the axial principal ray It is desirable that the right first plane including the upper chief ray is configured to coincide with the same first plane.
[0033]
In this case, the first plane is different from the second plane which is substantially the same plane including the eccentric optical path surface of the left eyepiece and the eccentric optical path surface of the right eyepiece, and the first plane It is desirable that the observation optical system is configured so that the plane and the second plane form a parallel positional relationship.
[0034]
Here, the fact that the decentered optical path surfaces of the left and right eyepieces are substantially in the same plane means that a slight angle shift due to a manufacturing error or the like is included, and is ± 1 °.
[0035]
Of the at least three left reflective surfaces, the two left reflective surfaces are arranged adjacent to each other in the vertical direction with respect to the first plane, and the two right reflective surfaces are at least three right reflective surfaces. It is desirable that the optical path distribution prism is configured so that the surface is adjacent to the first plane in the vertical direction.
[0036]
Also, one set of left reflecting surfaces among at least two sets of reflecting surfaces that reflect the axial principal rays of the left and right light beams in the three-dimensional eccentric direction including the component perpendicular to the second plane. And the right reflecting surface, the left reflecting surface and the left emitting surface are arranged adjacent to each other in the vertical direction with respect to the first plane, and the right reflecting surface and the right emitting surface are arranged adjacent to each other in the direction perpendicular to the first plane. Can be.
[0037]
In addition, the reflection surface disposed at the closest position on the optical path for the left eye with respect to the incident surface and the reflective surface disposed at the position closest to the optical path for the right eye with respect to the incident surface are both image display elements and It is desirable that they are adjacently arranged so as to face both of the incident surfaces.
[0038]
In this case, the light beam emitted vertically from the central region of the image display element with respect to the region including the boundary portion of the left and right reflecting surfaces arranged at the closest position on the optical path with respect to the incident surface. It is desirable to provide an antireflection member so that the light is not reflected as ghost light.
[0039]
Further, between the image display element and the three-dimensional optical path distribution unit, the light intensity of the image light beam having a predetermined emission angle emitted from each pixel located at least in the central portion of the one image display element is set. It is desirable to arrange a sorting light enhancing member that is stronger than the intensity of light flux emitted in the direction perpendicular to the pixel surface.
[0040]
Further, the optical path distribution prism rotates and intersects the axial principal ray of the optical path for the left eye radiated from the image display element by at least three or more left reflecting surfaces, and at least three or more right reflecting surfaces. The axial principal ray of the optical path for the right eye radiated from the image display element is rotated and intersected in the prism, and the rotation direction by the left reflection surface and the rotation direction by the right reflection surface are reversed. It is desirable that
[0041]
In this case, the optical path distribution prism is formed by the right-side reflecting surface in which the rotation crossing plane of the axial principal ray of the optical path for the left eye formed by the left reflecting surface is formed in the same plane as the left first plane. It is desirable that the rotation intersecting plane of the axial principal ray of the right-eye optical path is formed in the right first plane.
[0042]
Further, a plurality of left and right symmetrical reflecting surfaces included in the three-dimensional optical path distribution unit are arranged in order from the image display element side, one set of left and right first reflecting surfaces, one set of left and right second reflecting surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
It is desirable that at least the first reflecting surface is formed in a curved reflecting surface shape that gives power to the light beam and has a rotationally asymmetric shape having a decentration aberration correcting function.
[0043]
Further, a plurality of left and right symmetrical reflecting surfaces included in the three-dimensional optical path distribution unit are arranged in order from the image display element side, one set of left and right first reflecting surfaces, one set of left and right second reflecting surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
It is desirable that at least the second reflecting surface is formed in a curved reflecting surface shape that gives power to the light beam, and has a rotationally asymmetric shape having a decentration aberration correcting function.
[0044]
Further, a plurality of left and right symmetrical reflecting surfaces included in the three-dimensional optical path distribution unit are arranged in order from the image display element side, one set of left and right first reflecting surfaces, one set of left and right second reflecting surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
It is desirable that at least the third reflecting surface is formed in a curved reflecting surface shape that gives power to the light beam and has a rotationally asymmetric shape having a decentration aberration correction function.
[0045]
Further, a plurality of left and right symmetrical reflecting surfaces included in the three-dimensional optical path distribution unit are arranged in order from the image display element side, one set of left and right first reflecting surfaces, one set of left and right second reflecting surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
It is desirable that at least the fourth reflecting surface is formed in a curved reflecting surface shape that gives power to the light beam, and has a rotationally asymmetric shape having a decentration aberration correcting function.
[0046]
In these cases, the axial principal ray incident on the third reflecting surface of the left-eye optical path of the three-dimensional optical path distribution unit, the axial principal ray reflected therefrom, and the axis reflected by the fourth reflecting surface of the left-eye optical path. An axial chief ray incident on the third reflecting surface of the right-eye optical path, an axial chief ray reflected therefrom, and the fourth reflecting surface of the right-eye optical path are included in the same second left plane. It is desirable that the axial chief ray reflected at 1 is included in the same right second plane, and the left second plane and the right second plane are set perpendicular to the first plane.
[0047]
In addition, it is desirable that the rotationally asymmetric curved reflecting surface included in the three-dimensional optical path distributing unit is configured as a free curved surface having only one symmetric surface.
[0048]
Further, both the left eyepiece prism and the right eyepiece prism are composed of an incident surface, a first reflecting surface, a second reflecting surface, and an exit surface in order from the three-dimensional optical path distribution prism side, and the first reflecting surface and the exit surface are the same surface. The first reflecting surface can be a reflecting surface by total reflection on the surface.
[0049]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an image display device having a three-dimensional eccentric optical path of the present invention will be described based on examples.
[0050]
In the following examples, coordinates are set such that the observer's visual axis direction (front direction) is the Z axis, the horizontal direction is the Y axis, and the vertical direction is the X axis.
[0051]
In the numerical data of each example described later, the observation optical system for the right eye is shown, and it is shown by the data of back ray tracing from the right eye pupil 1 to the image display element (image plane) 3. Regarding the observation optical system for the left eye, although numerical data is omitted, the relationship is plane-symmetric with respect to a symmetry plane passing through the center of a straight line connecting both eyes. The description of the following configuration will also be given in the order of the reverse ray tracing.
[0052]
In Examples 1 and 2 described below, the eyepiece prism 10 includes a two-dimensional original eccentric prism in the YZ plane, and the optical path distributing prism 20 disposed on the image display element 3 side has a three-dimensional original eccentricity. It is a prism, and the axial principal ray in the optical path distribution prism 20 does not exist in the same plane, but exists in the YZ plane, two planes parallel to the YZ plane, and one plane orthogonal thereto. Hereinafter, description will be given with reference to the drawings.
[0053]
Example 1
FIG. 1 is a perspective view mainly showing a right-eye portion of the optical system of the image display apparatus of Embodiment 1, FIG. 2 is a perspective view showing the axial principal ray 2 of the optical system of Embodiment 1, and FIG. The perspective perspective view which shows the axial principal ray 2 of the optical system of Example 1 seen is shown, respectively. However, in FIGS. 1 to 3, the surface is represented by a mesh. FIG. 4 is a diagram showing an optical surface and an optical path mainly for the right eye portion of the optical system of the image display apparatus according to the first embodiment. However, (a) is a front view of the optical path for the right eye viewed from the positive direction of the Z axis, (b) is a plan view of the optical path for the right eye viewed from the negative direction of the X axis, and (c) is viewed from the negative direction of the X axis. The figure which shows the optical path of both eyes in the 1st horizontal surface, (d) is the 2nd above the 1st horizontal surface (X-axis negative side) in parallel with the 1st horizontal surface seen from the X-axis negative direction. It is a figure which shows the optical path of both eyes in the horizontal plane.
[0054]
This optical system is an optical system for the right eye when configured as a binocular head-mounted image display device. The optical system for the left eye is parallel to the XZ plane and The plane is symmetrical with respect to a plane passing through the center of the connecting straight line. The same applies to Example 2 below. 1 to 4 also show an eyepiece prism 10 'for the left eye.
[0055]
When the observation optical system of this embodiment is configured as a head-mounted image display device, an axial principal ray (optical axis) 2 for tracing back rays from the pupil 1 where the pupil of the right eye of the observer should be positioned is: Through the protective glass 4 (not shown in FIGS. 1 to 3), the light is refracted by the eleventh surface 11 of the eyepiece prism 10, enters the eyepiece prism 10, is internally reflected by the twelfth surface 12, and is the eleventh surface 11. Is incident on the thirteenth surface 13 at an angle exceeding the critical angle, totally reflected, refracted by the fourteenth surface 14, exits the eyepiece prism 10, and refracted by the twenty-first surface 21 of the optical path distribution prism 20 to distribute the optical path. It enters the prism 20, is internally reflected by the 22nd surface 22, is internally reflected by the 23rd surface 23, is internally reflected by the 24th surface 24, is internally reflected by the 25th surface 25, and is refracted by the 26th surface 26. Get out of the optical path sorting prism 20 It reaches the image display device 3.
[0056]
Here, the eleventh surface 11 to the fourteenth surface 14 of the eyepiece prism 10 are configured to be plane-symmetric with respect to the YZ plane, and each surface is configured to be two-dimensionally decentered within the YZ plane. ing.
[0057]
The axial principal ray emitted from the eyepiece prism 10 enters the optical path distribution prism 20 from the twenty-first surface 21, and is the eccentric surface (YZ plane: first horizontal plane H1 (FIG. 4C) of the eyepiece prism 10. Surface)) and reflected by the reflecting surface of the 22nd surface 22 into a surface H3 (a surface parallel to the X axis) perpendicular to the eccentric surface (YZ surface) of the eyepiece prism 10, and the reflected light Reflected by the reflecting surface of the 23rd surface 23, the reflected light is parallel to the first horizontal plane H1 and above (on the negative side of the X axis) the second horizontal plane H2 (surface of FIG. 4 (d)). Axis which is reflected by the reflecting surface of the 24th surface 24 and travels in the second horizontal plane H2, reflected by the reflecting surface of the 25th surface 25 and incident on the 24th surface 24 in the second horizontal surface H2. After crossing the principal ray, the light is refracted by the 26th surface 26 and passes through the center of the image display element 3 to the center of the image display element 3. Incident at an angle of -19.57 ° (FIG. 6 (b)) with respect to. The twenty-third surface 23 is disposed above the twenty-first surface 21 (X-axis negative side) of the optical path distribution prism 20, and the twenty-fourth surface 24 is disposed above the twenty-second surface 22 (negative X-axis side). The display surface of the display element 3 is parallel to the XY plane and is arranged so that its center coincides with a symmetrical plane passing through the center between the left and right pupils.
[0058]
The eyepiece prism 10 and the optical path distribution prism 20 are each configured to have a positive power so that both the eyepiece prism 10 and the optical path distribution prism 20 have a positive power, and the intermediate image of the image display element 3 is the 21st of the optical path distribution prism 20. An image is formed between the surface 21 and the 22nd surface 22.
[0059]
Thus, by decentering the observation optical system three-dimensionally, the optical system can be folded in a free direction, the entire image display device can be miniaturized, and dead space in consideration of other members. It is possible to provide an image display device with less image quality. Furthermore, the degree of freedom of design is increased. Further, the reflecting surfaces in the optical path distributing prism 20 are arranged in two steps in the vertical direction so that the effective diameter of the reflecting surfaces of both eyes can be secured even when the angle of view is widened.
[0060]
In this embodiment, the reflection surface of the 22nd surface 22 of the optical path distribution prism 20 is reflected on the 22nd surface 22 by decentering it in the direction perpendicular to the eccentric surface of the eyepiece prism 10 (X direction in this embodiment). The image is tilted in the X-axis direction. Thereafter, the reflecting surface is configured such that the tilt of the image in the X-axis direction is zero on the reflecting surface of the 23rd surface 23, so that the tilt of the image does not occur. With such a configuration, the binocular image has only a tilt in the Y-axis direction, and can be fused and observed. When an image tilt occurs in both the X direction and the Y direction on the image plane 3, the image projected on the image display element 3 is an image rotated in the left-right reverse direction about the axial principal ray. It becomes impossible to fuse the images of both eyes. In addition, since the reflecting surfaces from the 23rd surface 23 to the 25th surface 25 can be arranged in the vertical direction (X-axis direction) of the 21st surface 21 and the 22nd surface 22, each reflection in the optical path distribution prism 20. Surface interference can be prevented. Furthermore, since the X-axis direction is perpendicular to the longitudinal direction of the pupil, each surface can be configured without being greatly decentered, and the amount of decentered aberration that is asymmetric with respect to the X-axis can be kept small. .
[0061]
FIGS. 5 and 6A to 6B illustrate the inclination of the image with respect to the pupil coordinates in the configuration of the first embodiment (FIG. 5 corresponds to FIG. 4C, and FIG. 4 (a), FIG. 6 (b) corresponds to FIG. 4 (d)). In these drawings, X and Y indicate the image direction, and Z indicates the light traveling direction. FIG. 5 is an optical path diagram of both eyes from the pupil 1 to the 22nd surface 22, and is decentered in the YZ plane. FIG. 6A is a diagram showing the optical path for the right eye up to the 24th surface 24. The 21st surface 21 to the 24th surface 24 are decentered in the X direction perpendicular to the YZ plane. FIG. 6B is an optical path diagram of both eyes from the 23rd surface 23 to the image plane (image display element) 3 and is decentered in the YZ plane. However, for the sake of simplicity, these drawings illustrate the direction of an image when each surface is a flat reflecting mirror, and the imaging action is not considered. Actually, in this embodiment, since an intermediate image is formed, an image in which the X direction and the Y direction are opposite to each other is formed at the intermediate image position.
[0062]
In the present embodiment, since the eccentric surface of the eyepiece prism 10 is set in the horizontal direction, the vertical dimension of the eyepiece prism 10 can be made very small, and a reduction in size and weight can be achieved. Further, since the optical path distributing prism 20 is decentered three-dimensionally, a wider angle of view can be achieved. Further, since the intermediate image is formed once, the height of the optical path distribution prism 20 is smaller than the height of the eyepiece prism 10, and the apparatus can be downsized even if the optical path distribution prism 20 is decentered three-dimensionally. Can be achieved. Moreover, the distance between the object images from the intermediate image to the image display element 3 can be increased, and the power of each surface of the optical path distribution prism 20 can be set weak. Therefore, good performance can be ensured on the display surface of the image display element 3. Further, in this embodiment, since the image display element 3 can be arranged on the side opposite to the observer with respect to the optical path distribution prism 20, a problem in the space for arranging the image display element 3 and the backlight therefor hardly occurs. .
[0063]
Further, in this embodiment, the optical path distribution prism 20 has four reflecting surfaces 22 to 25, and the two reflecting surfaces 22 and 23 are decentered in the X-axis direction, and the two reflecting surfaces 24 and 25 are Y. Since it is decentered in the axial direction, good decentration aberration correction can be achieved even if the optical path is taken three-dimensionally.
[0064]
The parallel plate 4 between the eyepiece prism 10 and the pupil 1 is inserted for protective glass. It goes without saying that a wider angle of view can be obtained by applying positive power to the protective glass 4.
[0065]
Example 2
FIG. 7 is a view similar to FIG. 4 of the second embodiment. When the observation optical system of this embodiment is configured as a head-mounted image display device, an axial principal ray (optical axis) 2 for tracing back rays from the pupil 1 where the pupil of the right eye of the observer should be positioned is: Through the protective glass 4, the light is refracted by the eleventh surface 11 of the eyepiece prism 10, enters the eyepiece prism 10, is internally reflected by the twelfth surface 12, and exceeds the critical angle at the thirteenth surface 13 that also serves as the eleventh surface 11. Incident at an angle and totally reflected, refracted by the 14th surface 14, exiting the eyepiece prism 10, refracted by the 21st surface 21 of the optical path distributing prism 20 and entering the optical path distributing prism 20, and by the 22nd surface 22 Internally reflected, internally reflected by the 23rd surface 23, internally reflected by the 24th surface 24, refracted by the 25th surface 25, exits from the optical path distribution prism 20, and reaches the image display element 3.
[0066]
Here, the eleventh surface 11 to the fourteenth surface 14 of the eyepiece prism 10 are configured to be plane-symmetric with respect to the YZ plane, and each surface is configured to be two-dimensionally decentered within the YZ plane. ing.
[0067]
The axial principal ray emitted from the eyepiece prism 10 enters the optical path distribution prism 20 from the twenty-first surface 21, and is the eccentric surface (YZ plane: first horizontal plane H1 (FIG. 4C) of the eyepiece prism 10. Surface)) and reflected by the reflecting surface of the 22nd surface 22 into a surface H3 (a surface parallel to the X axis) perpendicular to the eccentric surface (YZ surface) of the eyepiece prism 10, and the reflected light Reflected by the reflecting surface of the 23rd surface 23, the reflected light is parallel to the first horizontal plane H1 and above (on the negative side of the X axis) the second horizontal plane H2 (surface of FIG. 4 (d)). Then, the light is reflected by the reflecting surface of the 24th surface 24, travels in the second horizontal plane H2, is refracted by the 25th surface 25, and is centered on the image display element 3 with respect to the normal passing through the center of the image display element 3. Incident at an angle of −31.32 °. The twenty-third surface 23 is disposed above the twenty-first surface 21 (X-axis negative side) of the optical path distribution prism 20, and the twenty-fourth surface 24 is disposed above the twenty-second surface 22 (negative X-axis side). The display surface of the display element 3 is parallel to the XY plane and is arranged so that its center coincides with a symmetrical plane passing through the center between the left and right pupils.
[0068]
The eyepiece prism 10 and the optical path distribution prism 20 are each configured to have a positive power so that both the eyepiece prism 10 and the optical path distribution prism 20 have a positive power, and the intermediate image of the image display element 3 is the 21st of the optical path distribution prism 20. An image is formed between the surface 21 and the 22nd surface 22.
[0069]
Thus, by decentering the observation optical system three-dimensionally, the optical system can be folded in a free direction, the entire image display device can be miniaturized, and dead space in consideration of other members. It is possible to provide an image display device with less image quality. Furthermore, the degree of freedom of design is increased. Further, the reflecting surfaces in the optical path distributing prism 20 are arranged in two steps in the vertical direction so that the effective diameter of the reflecting surfaces of both eyes can be secured even when the angle of view is widened.
[0070]
Also in the second embodiment, as in the first embodiment, the reflecting surface of the twenty-second surface 22 of the optical path distribution prism 20 is decentered in the direction perpendicular to the eccentric surface of the eyepiece prism 10 (X direction in this embodiment). The image reflected by the 22 surface 22 is inclined in the X-axis direction. Thereafter, the reflecting surface is configured such that the tilt of the image in the X-axis direction is zero on the reflecting surface of the 23rd surface 23, so that the tilt of the image does not occur. With such a configuration, the binocular image has only a tilt in the Y-axis direction, and can be fused and observed. When an image tilt occurs in both the X direction and the Y direction on the image plane 3, the image projected on the image display element 3 is an image rotated in the left-right reverse direction about the axial principal ray. It becomes impossible to fuse the images of both eyes. In addition, since the reflecting surfaces from the 23rd surface 23 to the 24th surface 24 can be arranged in the vertical direction (X-axis direction) of the 21st surface 21 and the 22nd surface 22, each reflection in the optical path distribution prism 20. Surface interference can be prevented. Furthermore, since the X-axis direction is perpendicular to the longitudinal direction of the pupil, each surface can be configured without being greatly decentered, and the amount of decentered aberration that is asymmetric with respect to the X-axis can be kept small. .
[0071]
In the present embodiment, since the eccentric surface of the eyepiece prism 10 is set in the horizontal direction, the vertical dimension of the eyepiece prism 10 can be made very small, and a reduction in size and weight can be achieved. Further, since the optical path distributing prism 20 is decentered three-dimensionally, a wider angle of view can be achieved. Further, since the intermediate image is formed once, the height of the optical path distribution prism 20 is smaller than the height of the eyepiece prism 10, and the apparatus can be downsized even if the optical path distribution prism 20 is decentered three-dimensionally. Can be achieved. Moreover, the distance between the object images from the intermediate image to the image display element 3 can be increased, and the power of each surface of the optical path distribution prism 20 can be set weak. Therefore, good performance can be ensured on the display surface of the image display element 3. In this embodiment, the image display element 3 is arranged on the viewer side of the optical path distributing prism 20, but the image display element 3 is slightly above the eye position (the optical path distributing prism 20). Therefore, interference between the image display element 3 and the observer's nose is unlikely to occur.
[0072]
Further, in this embodiment, the optical path distribution prism 20 has three reflecting surfaces 22 to 24, and the two reflecting surfaces 22 and 23 are eccentric in the X-axis direction, and one reflecting surface 24 is in the Y-axis direction. Therefore, even when the optical path is taken three-dimensionally, good decentration aberration correction can be performed.
[0073]
The parallel plate 4 between the eyepiece prism 10 and the pupil 1 is inserted for protective glass. It goes without saying that a wider angle of view can be obtained by applying positive power to the protective glass 4.
[0074]
Next, the configuration parameters of Examples 1 and 2 will be shown. In the constituent parameters of each embodiment, the axial principal ray 2 is defined as a ray that passes vertically through the center of the exit pupil 1 of the optical system and reaches the center of the image display element 3 by inverse ray tracing. In reverse ray tracing, the center of the pupil 1 is the origin of the decentered optical surface of the decentered optical system, the direction along the axial principal ray 2 is the Z-axis direction, and the direction from the pupil 1 toward the eleventh surface 11 is the Z-axis normal The plane in which the optical axis is bent in the eyepiece prism 10 is defined as the YZ plane, the direction passing through the origin and orthogonal to the YZ plane, and the direction from the top to the bottom in the vertical direction is defined as the X-axis positive direction. The axis constituting the Z-axis and the right-handed orthogonal coordinate system is taken as the Y-axis. This coordinate system is the same as that shown in FIGS.
[0075]
For the eccentric surface, the amount of eccentricity from the center of the origin of the optical system to the top position of the surface (X, Y, and Z directions are X, Y, and Z, respectively) and the center axis of the surface (free For curved surfaces, the Z-axis in the equation (a), and for aspherical surfaces, the tilt angles (α, β, respectively) about the X-axis, Y-axis, and Z-axis of the later-described equation (d) Z-axis). γ (°)). In this case, positive α and β mean counterclockwise rotation with respect to the positive direction of each axis, and positive γ means clockwise rotation with respect to the positive direction of the Z axis. Note that the α, β, and γ rotations of the central axis of the surface are performed by first rotating the central axis of the surface and its XYZ orthogonal coordinate system by α counterclockwise around the X axis, and then rotating the rotation. The center axis of the surface is rotated β counterclockwise around the Y axis of the new coordinate system, and the coordinate system rotated once is also rotated β counterclockwise around the Y axis and then rotated twice. The center axis of the surface is rotated γ clockwise around the Z axis of the new coordinate system.
[0076]
In addition, among the optical action surfaces constituting the optical system of each embodiment, when a specific surface and a subsequent surface constitute a coaxial optical system, a surface interval is given, and in addition, the refractive index of the medium, Abbe numbers are given according to idioms.
[0077]
Further, the shape of the surface of the free curved surface used in the present invention is defined by the equation (a), and the Z axis of the defining equation becomes the axis of the free curved surface.
[0078]
An aspherical surface is a rotationally symmetric aspherical surface given by the following definition.
[0079]

However, Z is an optical axis (axial principal ray) with the light traveling direction being positive, and y is a direction perpendicular to the optical axis. Here, R is a paraxial radius of curvature, K is a conic constant, A, B, C, D,... Are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively. The Z axis of this defining formula is the axis of a rotationally symmetric aspherical surface.
[0080]
Note that terms relating to free-form surfaces and aspheric surfaces for which no data is described are zero. The refractive index is shown for d-line (wavelength 587.56 nm).
The unit of length is mm.
[0081]
In Examples 1 and 2, when the observation optical system is used, the observation field angle is 12.5 ° horizontal half angle, 9.4 ° vertical half field angle, and the size of the image display element 3 is 10. It is 2 × 7.6 mm and has a pupil diameter of 4 mm.
[0082]
In the following configuration parameter tables, “FFS” indicates a free-form surface, “ASS” indicates an aspheric surface, and “RE” indicates a reflective surface.
[0083]

[0084]

[0085]
By the way, in the image display device of the present invention, the incident light beam 26 (example of embodiment) of the optical path distribution prism 20 is separated by separating the display light beam emitted from the single image display element 3 and having a certain degree of emission angle into left and right optical paths. 1) or 25 (Embodiment 2), which allows observation with both eyes through the left and right eyepiece optical systems 10, 10 ′. As shown in FIG. As the image display element 3, an image display element 3 comprising a liquid crystal display element 31 that is uniformly illuminated by a white backlight 32 and emits a display light beam at an emission angle larger than an angle φ formed between the optical axes of the left and right optical paths is used. It is done. In addition, a self-luminous element such as an EL element having a large display emission angle can be used as the image display element 3.
[0086]
Further, when the image display element 33 having a small display emission angle is used as the image display element 3, as shown in FIG. As a sorting light enhancing member that increases the emission angle in the optical path direction, it is desirable to arrange, for example, a beam sorting microprism 35 having a cross section as shown in correspondence with each pixel 34. Instead, a transmission diffraction grating having a configuration in which the intensity of the 0th-order transmitted light is weakened and the ± 1st-order diffracted light is strengthened may be disposed close to the display surface of the image display element 3.
[0087]
By the way, the left and right reflecting surfaces 25 (Embodiment 1) or 24 (Embodiment 2) arranged at positions closest to the incident surface 26 (Embodiment 1) or 25 (Embodiment 1) of the optical path distribution prism 20 on the optical path. If the display light beam emitted from the image display element 3 hits the boundary portion 29), it may be reflected there to become ghost light. Therefore, as shown in FIG. 8C, black paint is applied as an antireflection member 36 for preventing such reflection in the vicinity of the boundary portion 29 or is subjected to diffusion treatment or the like, and is emitted from the image display element 3. It is desirable to absorb the light beam portion indicated by a broken line incident on the boundary portion 29 in the display light beam 37. Note that a light beam portion indicated by a solid line in the display light beam 37 is guided to the left and right optical paths and represents a light beam that is effectively used for display.
[0088]
Now, by supporting the observation optical system as described above, it can be configured as a binocular wearing image display device, and can be configured as a stationary or portable image display device that can be observed with both eyes. Can do.
[0089]
This is shown in FIG. In the figure, reference numeral 131 denotes a display device main body, and a support member is fixed via the head so as to be held in front of both eyes on the face of the observer. As the supporting member, one end is joined to the display device main body 131 and joined to the left and right front frames 132 extending from the viewer's temple to the upper part of the ear, and the other end of the front frame 132, A left and right rear frame 133 that extends across the head, and a parietal frame 134 that supports the observer's head by joining both ends one by one so as to be sandwiched between the other ends of the left and right rear frames 133; It is composed of
[0090]
Also, a rear plate 135 made of an elastic body and made of, for example, a metal plate spring is joined to the front frame 132 in the vicinity of the joint with the rear frame 133. The rear plate 135 is joined so that a rear cover 136 serving as one wing of the support member can be positioned and supported behind the ear at a portion of the observer from the back of the head to the neck. A speaker 139 is attached to the rear plate 135 or the rear cover 136 at a position corresponding to the observer's ear.
[0091]
A cable 141 for transmitting video / audio signals and the like from the outside is provided from the display device main body 131 to the rear plate 135 or the rear cover 136 through the top frame 134, the rear frame 133, the front frame 132, and the rear plate 135. Projects outward from the end. The cable 141 is connected to the video playback device 140. In the figure, reference numeral 140a denotes a switch or volume adjustment unit of the video playback device 140.
[0092]
The cable 141 may be attached to an existing video deck or the like by jacking the tip. Further, it may be connected to a TV radio wave receiving tuner for TV viewing, or may be connected to a computer to receive computer graphics video, message video from the computer, or the like. Further, in order to eliminate a disturbing cord, an antenna may be connected to receive an external signal by radio waves.
[0093]
In addition, the observation optical system of the image display device of the present invention can be used as an imaging optical system by introducing light from the subject from the pupil 1 side and arranging an image sensor at the position of the image display element 3. is there. FIG. 10 shows a conceptual diagram of a configuration in which the optical system on only one of the left and right sides of the observation optical system of the present invention is incorporated in the photographing objective optical system 42 of the photographing unit of the electronic camera 40. Of course, both the left and right optical systems of the observation optical system of the present invention may be used (the entrance pupil becomes two optical systems). In the case of this example, the photographing objective optical system 42 arranged on the photographing optical path 41 uses the same optical system as that of the first embodiment with the optical path reversed, and the stop 1 ′ is located at the position of the pupil 1. It is arranged. The object image formed by the photographing objective optical system 42 is formed on the imaging surface 46 of the CCD 45 through a filter 44 such as a low-pass filter or an infrared cut filter. The object image received by the CCD 45 is displayed as an electronic image on a liquid crystal display element (LCD) 52 via the processing means 51. The processing means 51 also controls the recording means 54 that records the object image photographed by the CCD 45 as electronic information. The image displayed on the LCD 52 is guided to the observer's eyeball E through an eyepiece optical system 53 formed of a decentered prism similar to the eyepiece prism 10. As the eyepiece optical system 53, a three-dimensional decentered optical system including the eyepiece prism 10 on one side and the optical path distributing prism 20 according to the present invention may be used. The photographing objective optical system 42 may include other lenses (positive lens, negative lens) as components on the object side of the prism 10 or the image side of the prism 20.
[0094]
The camera 40 configured as described above can configure the photographing objective optical system 42 with a small number of optical members, can reduce the size of the entire apparatus, is inexpensive, and has a small dead space in consideration of other members. And the degree of freedom in design is large.
[0095]
In this example, a plane-parallel plate is disposed as the cover member 43 of the photographing objective optical system 42, but a lens having power may be used.
[0096]
Further, the optical system of only one of the left and right sides of the observation optical system of the present invention can be used as a projection optical system by disposing an image plane for projection at the position of the image display element 3 and a screen in front of the pupil 1. Can be used. Of course, in this case as well, both the left and right optical systems of the observation optical system of the present invention may be used (the exit pupil becomes two optical systems). FIG. 11 shows a conceptual diagram of a configuration in which a decentered prism optical system according to the present invention is used for the projection optical system 96 of a presentation system in which a personal computer 90 and a liquid crystal projector 91 are combined. In the case of this example, the same optical system as that of the first embodiment is used for the projection optical system 96. In the figure, image / document data created on the personal computer 90 is branched from the monitor output and output to the processing control unit 98 of the liquid crystal projector 91. In the processing control unit 98 of the liquid crystal projector 91, the input data is processed and output to the liquid crystal panel (LCP) 93. On the liquid crystal panel 93, an image corresponding to the input image data is displayed. Then, after the transmission amount of light from the light source 92 is determined by the gradation of the image displayed on the liquid crystal panel 93, the field lens 95 disposed immediately before the liquid crystal panel 93 and the prism 20 constituting the optical system of the present invention. 10 and a positive lens cover lens 94 through a projection optical system 96.
[0097]
The projector configured as described above can be configured with a small number of optical members, can realize cost reduction, and can be downsized.
[0098]
The image display apparatus provided with the above-described three-dimensional eccentric optical path of the present invention can be configured as follows, for example.
[0099]
[1] In an image display device including an image display element that forms an observation image on an image display unit, and an observation optical system that guides an image formed by the image display element to a pupil corresponding to an observer's eyeball position.
The image display element has a single image display element in which a plurality of pixels are arranged side by side on a single plate,
Each pixel located in at least the central portion of the one image display element is configured to emit an image light beam at an emission angle that can guide the light beam to the left and right eyeballs of an observer,
The observation optical system emits at least the left eyepiece that guides the light flux to the left eye of the observer, the right eyepiece that guides the light flux to the right eye of the observer, and the emission angle from the image display element. A three-dimensional optical path distribution unit that guides the imaged light flux to the left and right eyepieces,
The left eyepiece has at least two reflecting surfaces, and at least one of the reflecting surfaces is composed of a rotationally asymmetric curved reflecting surface having a decentration aberration correcting function,
The right eyepiece has at least two reflecting surfaces, and at least one of the reflecting surfaces is a rotationally asymmetric curved reflecting surface having a decentration correction function,
An eccentric optical path surface (YZ plane) of an axial principal ray formed by the two or more reflecting surfaces of the left eyepiece, and the two or more reflecting surfaces of the right eyepiece The left and right eyepieces are configured such that the eccentric optical path surface (YZ plane) of the axial principal ray formed in the same plane (YZ plane) is formed,
The three-dimensional optical path allocating unit has optical surfaces arranged symmetrically so as to form a bilaterally symmetric optical path, and at least two sets of right and left reflecting surfaces are the left and right eyepieces. The axial principal rays of the left and right light beams are reflected in the three-dimensional eccentric direction including the component in the direction (X direction) perpendicular to the eccentric optical path surface (YZ plane) formed by An image display device having a three-dimensional eccentric optical path.
[0100]
[2] In 1 above,
An image display device having a three-dimensional eccentric optical path, wherein the three-dimensional optical path distribution unit includes at least one set of rotationally asymmetric curved reflecting surfaces having a function of correcting decentration aberrations.
[0101]
[3] In 2 above,
The rotationally asymmetric curved reflecting surfaces having at least one set of decentration aberration correcting function are at least two sets of left and right reflecting surfaces that reflect the axial principal rays of the left and right light beams in the three-dimensional eccentric direction. An image display device having a three-dimensional eccentric optical path, wherein the image display device is arranged in one set.
[0102]
[4] In 2 above,
The rotationally asymmetric curved reflecting surface having at least one set of decentration aberration correcting function is formed of a free curved surface having only one symmetrical surface,
An image display apparatus having a three-dimensional eccentric optical path, characterized in that each of the at least one set of free-form surfaces has a single symmetry plane that coincides within the same plane.
[0103]
[5] In any one of the above items 1 to 4,
The observation optical system is formed by a prism member, and all of the reflection surfaces are configured by a back surface reflection surface formed on the surface of the prism member. Image display device.
[0104]
[6] In the above item 5,
The observation optical system includes: a three-dimensional optical path distribution prism that constitutes the three-dimensional optical path distribution unit; a left eyepiece prism that is separated from the three-dimensional optical path distribution prism with an air interval; An image display device having a three-dimensional decentered optical path, comprising a right eyepiece prism constituting a right eyepiece.
[0105]
[7] In the above item 6,
The optical path distribution prism is at least a light incident surface that faces both the image display element and forms a left-eye optical path and an image light beam that forms a right-eye optical path and enters the prism. At least 3 which is arranged on the optical path between the left exit surface for exiting the light beam for the optical path out of the prism and between the incident surface and the left exit surface and reflects the light beam for the optical path for the left eye within the prism. A right-side reflecting surface disposed on an optical path between the incident surface and the right-side exit surface, and a left-side reflecting surface that is equal to or greater than the surface, a right-side exit surface that emits the light flux of the right-eye optical path out of the prism, and the right-eye optical path Including at least three or more right-hand reflecting surfaces that reflect the luminous flux within the prism,
An axial chief ray incident on a reflecting surface disposed at a position closest to the incident surface among the at least three left reflecting surfaces on the optical path for the left eye, and an axial chief ray reflected therefrom; And an axial principal ray incident on a reflecting surface disposed at a position closest to the incident surface among the at least three right reflecting surfaces on the right-eye optical path, and An image display device having a three-dimensional eccentric optical path, wherein a right first plane including an axial principal ray reflected from the same coincides with the same first plane.
[0106]
[8] In the above item 7,
The first plane is different from the second plane which is the same plane including the eccentric optical path surface of the left eyepiece and the eccentric optical path surface of the right eyepiece, and the first plane An image display device having a three-dimensional decentered optical path, wherein the observation optical system is configured so that a plane and a second plane form a parallel positional relationship.
[0107]
[9] In the above item 8,
Among the at least three or more left reflecting surfaces, two left reflecting surfaces are arranged adjacent to each other in the vertical direction with respect to the first plane, and two right sides among the at least three right reflecting surfaces. An image display apparatus having a three-dimensional eccentric optical path, wherein the optical path distributing prism is configured such that a reflecting surface is arranged adjacent to the first plane in a direction perpendicular to the first plane.
[0108]
[10] In the above 9,
A pair of left reflecting surfaces among at least two pairs of left and right reflecting surfaces that reflect the axial principal rays of the left and right light beams in a three-dimensional eccentric direction including a component perpendicular to the second plane; Regarding the right reflecting surface, the left reflecting surface and the left emitting surface are arranged adjacent to each other in a direction perpendicular to the first plane, and the right reflecting surface and the right emitting surface are perpendicular to the first plane. An image display device provided with a three-dimensional eccentric optical path, which is adjacently arranged in the direction.
[0109]
[11] In any one of the above 7 to 10,
Both of the reflection surface arranged at the closest position on the left-eye optical path with respect to the incident surface and the reflection surface arranged at the closest position on the right-eye optical path with respect to the incident surface An image display device having a three-dimensional eccentric optical path, wherein the image display device is adjacently disposed so as to face both the display element and the incident surface.
[0110]
[12] In the above item 11,
With respect to the region including the boundary portion of the left and right reflecting surfaces, where the optical path distribution prism is disposed at the closest position on the optical path with respect to the incident surface, the light beam emitted vertically from the central region of the image display element An image display device having a three-dimensional eccentric optical path, wherein an antireflection member is provided so as not to reflect as ghost light.
[0111]
[13] In any one of the above items 1 to 12,
Between the image display element and the three-dimensional optical path distribution unit, the light intensity of an image light beam having a predetermined emission angle emitted from each pixel located at least in the central portion of the one image display element is An image display apparatus having a three-dimensional eccentric optical path, characterized in that a sorting light enhancing member is arranged so as to be stronger than the intensity of light flux emitted in the vertical direction of each pixel surface.
[0112]
[14] In any one of 7 to 13 above,
The optical path distribution prism rotates and intersects the axial principal ray of the optical path for the left eye radiated from the image display element by the at least three or more left-side reflecting surfaces in the prism, and the at least three or more surfaces. The axial principal ray of the optical path for the right eye radiated from the image display element by the right reflection surface is rotated and intersected in the prism, and the rotation direction by the left reflection surface and the rotation direction by the right reflection surface are An image display device having a three-dimensional eccentric optical path, wherein the image display device is configured to be reversely rotated.
[0113]
[15] In the above 14,
The optical path distribution prism is formed by the right-side reflecting surface, and a rotation crossing plane of the axial principal ray of the left-eye optical path formed by the left-side reflecting surface is formed in the same plane as the left first plane. An image display device having a three-dimensional eccentric optical path, wherein a rotation crossing plane of an axial principal ray of the right-eye optical path is formed in the right first plane.
[0114]
[16] In any one of the above items 1 to 15,
A plurality of left and right symmetrical reflective surfaces included in the three-dimensional optical path distribution unit are, in order from the image display element side, one set of left and right first reflective surfaces, one set of left and right second reflective surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
A three-dimensional decentered optical path characterized in that at least the first reflecting surface has a curved reflecting surface shape that gives power to a light beam, and has a rotationally asymmetric shape having a decentration aberration correcting function. An image display device provided.
[0115]
[17] In any one of the above items 1 to 16,
A plurality of left and right symmetrical reflective surfaces included in the three-dimensional optical path distribution unit are, in order from the image display element side, one set of left and right first reflective surfaces, one set of left and right second reflective surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
A three-dimensional decentered optical path characterized in that at least the second reflecting surface has a curved reflecting surface shape that gives power to a light beam, and has a rotationally asymmetric shape having a decentration aberration correcting function. An image display device provided.
[0116]
[18] In any one of the above items 1 to 17,
A plurality of left and right symmetrical reflective surfaces included in the three-dimensional optical path distribution unit are, in order from the image display element side, one set of left and right first reflective surfaces, one set of left and right second reflective surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
A three-dimensional decentered optical path characterized in that at least the third reflecting surface has a curved reflecting surface shape that gives power to a light beam, and has a rotationally asymmetric shape having a decentration aberration correcting function. An image display device provided.
[0117]
[19] In any one of the above items 1 to 18,
A plurality of left and right symmetrical reflective surfaces included in the three-dimensional optical path distribution unit are, in order from the image display element side, one set of left and right first reflective surfaces, one set of left and right second reflective surfaces, and one set of left and right sets. The third reflecting surface and a pair of left and right fourth reflecting surfaces,
A three-dimensional decentered optical path characterized in that at least the fourth reflecting surface has a curved reflecting surface shape that gives power to a light beam and has a rotationally asymmetric shape having a decentration aberration correcting function. An image display device provided.
[0118]
[20] In any one of the above 16 to 19,
An axial principal ray incident on the third reflecting surface of the left-eye optical path of the three-dimensional optical path distribution unit, an axial principal ray reflected therefrom, and an axial principal ray reflected by the fourth reflecting surface of the left-eye optical path; Are included in the same second left plane and reflected by the axial principal ray incident on the third reflecting surface of the right-eye optical path, the axial principal ray reflected therefrom, and the fourth reflecting surface of the right-eye optical path. An axial principal ray is included in the same right second plane, and the left second plane and the right second plane are set perpendicular to the first plane. An image display device comprising:
[0119]
[21] In any one of the above items 1 to 20,
An image display apparatus having a three-dimensional eccentric optical path, wherein the rotationally asymmetric curved reflecting surface included in the three-dimensional optical path distributing unit is configured as a free-form surface having only one symmetric surface. .
[0120]
[22] In any one of the above 6-21,
The left eyepiece prism and the right eyepiece prism both include an entrance surface, a first reflection surface, a second reflection surface, and an exit surface in order from the three-dimensional optical path distribution prism side, and the first reflection surface and the exit surface. The image display device having a three-dimensional eccentric optical path, wherein the first reflection surface is a reflection surface by total reflection on the surface.
[0121]
【The invention's effect】
As is apparent from the above description, according to the present invention, since the image display element can be viewed with both eyes, the cost is very low. In addition, since a free-form surface is used for the optical path distribution prism that distributes images to both eyes, aberration correction can be performed satisfactorily. In addition, since a half mirror is not used, a bright image can be observed. Furthermore, since the optical path distributing prism is decentered three-dimensionally, it is possible to provide a display device with a very wide angle of view that allows binocular viewing with a single image display element. Furthermore, since the eccentric surface of the eyepiece prism is horizontal, an image display device with a very small width can be provided, and a wide sea-around is possible.
[Brief description of the drawings]
FIG. 1 is a perspective view mainly showing a right-eye portion of an optical system of an image display apparatus according to Embodiment 1 of the present invention.
2 is a perspective view showing an axial principal ray of the optical system of Example 1. FIG.
FIG. 3 is a perspective view showing an axial principal ray of the optical system of Example 1 viewed from a different angle.
4 is a diagram illustrating an optical surface and an optical path mainly of a right-eye portion of the optical system of the image display apparatus according to Embodiment 1. FIG.
FIG. 5 is a diagram illustrating the inclination of an image with respect to pupil coordinates in the configuration of the first embodiment.
6 is a diagram showing the inclination of an image with respect to pupil coordinates in the configuration of Embodiment 1. FIG.
7 is a diagram illustrating an optical surface and an optical path mainly of a right-eye portion of the optical system of the image display apparatus according to Embodiment 2. FIG.
FIG. 8 is a diagram for explaining an image display element that can be used in the present invention, a sorting light enhancing member, and an antireflection member therefor.
FIG. 9 is a diagram showing a state in which the image display device of the present invention is configured to be worn on both eyes.
FIG. 10 is a conceptual diagram of a configuration in which the optical system of the present invention is incorporated in a photographing objective optical system of a photographing unit of an electronic camera.
FIG. 11 is a conceptual diagram of a configuration in which an optical system according to the present invention is used in a projection optical system of a presentation system.
[Explanation of symbols]
E ... Observer's eyes
1 ... Hitomi
1 '... Aperture
2 ... On-axis chief ray (optical axis)
3. Image display element
4 ... Protective glass
10, 10 '... eyepiece prism
11 ... 11th page
12 ... Twelfth surface
13 ... 13th page
14 ... 14th page
20 ... Optical path distribution prism
21 ... 21st page
22 ... 22nd surface
23 ... 23rd page
24 ... 24th page
25. 25th surface
26 ... 26th page
29 ... Boundary part
31 ... Liquid crystal display element
32 ... White backlight
33. Image display element
34 ... Pixels
35 ... Light beam distribution microprism
36 ... Antireflection member
37 ... Display light flux
40 ... Electronic camera
41. Optical path for photographing
42 ... Objective optical system for photographing
43 ... Cover member
44 ... Filter
45 ... CCD
46: Imaging surface
51. Processing means
52 ... Liquid crystal display (LCD)
53 ... Eyepiece optical system
54. Recording means
90 ... PC
91 ... Liquid crystal projector
92 ... Light source
93 ... Liquid crystal panel (LCP)
94: Cover lens
95 ... Field lens
96 ... projection optical system
97 ... Screen
98 ... Processing control unit
131 ... Display device main body
132 ... Previous frame
133 ... rear frame
134 ... Parietal frame
135 ... Rear plate
136 ... Rear cover
139 ... Speaker
140 ... Video playback device
140a ... Volume adjuster
141 ... cable

Claims (5)

An image display element that forms an observation image on an image display unit, and an observation optical system that guides the image formed by the image display element to a pupil corresponding to the position of the eyeball of the observer
The image display element has a single image display element in which a plurality of pixels are arranged side by side on a single plate,
Each pixel located in at least the central portion of the one image display element is configured to emit an image light beam at an emission angle that can guide the light beam to the left and right eyeballs of an observer,
The observation optical system emits at least the left eyepiece that guides the light flux to the left eye of the observer, the right eyepiece that guides the light flux to the right eye of the observer, and the emission angle from the image display element. In an image display device including an optical path distribution unit that guides the image light flux that has been performed to the left and right eyepieces,
The left eyepiece has at least two reflecting surfaces, and at least one of the reflecting surfaces is composed of a rotationally asymmetric curved reflecting surface having a decentration aberration correcting function,
The right eyepiece has at least two reflecting surfaces, and at least one of the reflecting surfaces is a rotationally asymmetric curved reflecting surface having a decentration correction function,
In inverse ray tracing, the axial principal ray is a ray that passes vertically through the center of the pupil and reaches the center of the image display element,
The left decentered light when the virtual plane including the axial principal ray in the left eyepiece is a left decentered optical path surface, and the virtual plane including the axial principal ray in the right eyepiece is a right decentered optical path surface. The left and right eyepieces are configured such that each of the road surface and the right eccentric optical path surface coincides with the first plane,
The optical path allocating unit has a pair of optical surfaces symmetrically arranged so as to form a bilaterally symmetric optical path, and corresponding to each optical path passing through at least the left and right eyepieces in the optical surface . One reflecting surface is configured to reflect the left and right axial principal rays in a three-dimensional eccentric direction including a component in a direction perpendicular to the left and right eccentric optical path surfaces. An image display device having a three-dimensional eccentric optical path. In claim 1,
The optical path distribution unit is a set corresponding to each of optical paths passing through the left and right eyepieces different from the transmission surface provided at a position facing the image display element and the left and right set of first reflection surfaces . Having a second reflective surface;
A virtual plane including the axial principal ray in an optical path formed by the transmission surface and the left second reflection surface is a left second plane, and the axis is in an optical path formed by the transmission surface and the right second reflection surface. The virtual plane including the principal ray is the right second plane, and the left second plane and the right second plane coincide with each other in the second plane,
The transmission surface and the pair of left and right second reflection surfaces are arranged so that the second plane is positioned parallel to the first plane and at a predetermined interval. An image display device having a dimensional eccentric optical path. In claim 2,
The axial principal ray reflected by the pair of left and right first reflecting surfaces is disposed in a space between the first plane and the second plane, and has a three-dimensional eccentric optical path. Image display device. In claim 2 or 3,
The rotationally asymmetric curved reflecting surfaces in the left and right eyepieces have only one symmetry plane, and the symmetry plane is parallel to the first plane,
The pair of second reflecting surfaces is a rotationally asymmetric curved reflecting surface having only one symmetry surface, and the symmetry surface is parallel to the second plane;
The image display apparatus having a three-dimensional eccentric optical path, wherein the pair of left and right first reflecting surfaces is a rotationally asymmetric curved reflecting surface having no symmetry surface. In any one of Claims 1-3,
Increasing the emission angle from the vertical direction to the left and right optical path directions for the luminous flux emitted with the emission angle from each pixel located at least in the central portion of the image display element between the image display element and the optical path distribution unit. An image display apparatus provided with a three-dimensional eccentric optical path, characterized in that an appropriate sorting light enhancing member is disposed.

Images