JP2004219500A - Projector device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector device realizing the high efficiency of a reflector. <P>SOLUTION: The reflector is constituted as the assembly of a plurality of section reflectors divided into a plurality of sections based on a distance from an optical axis, and constituted by tilting the section reflectors on a condition that a position where a light beam from a given point light source on the optical axis is reflected by the reflector and crosses with the optical axis is set so that a position where a light beam reflected by the section reflector near the optical axis crosses with the optical axis is more distant from the reflector than a position where a light beam reflected by the section reflector far from the optical axis crosses with the optical axis. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００２５】
次に、点Ｐ１と点Ｐ２の範囲のリフレクタの切片Ｂ１で、受光器３の位置を第２焦点位置を基準にΔＺ＝−２０ｍｍからΔＺ＝１ｍｍまで１ｍｍ刻みに移動させて光線本数を計算した。以下、同様に、点Ｐ２から点Ｐ３の範囲のリフレクタの切片Ｂ２、と順次、点Ｐ４６から点Ｐ４７の範囲のリフレクタの切片Ｂ４６まで各２２回づつの計算を行った。
【００２６】
以下、計算結果を図５から図１１と、表２から表４を用いて説明する。
【００２７】
図５において、光源１の大きさはアーク長（発光部の大きさに相当）１．４ｍｍ、受光器３の大きさは４×３ｍｍである。尚、図５の縦軸は光線本数である。例えば、第１の切片（Ｒ＝８．３００〜９．２５４）ではΔＺ＝−１９ｍｍで光線本数が最大となり、第２０の切片（Ｒ＝２４．２９２〜２４．９９５）ではΔＺ＝−８ｍｍで光線本数が最大となり、第４６の切片（Ｒ＝３８．４０４〜３８．７９１）ではΔＺ＝０ｍｍで光線本数が最大となった。
【００２８】
表２は、楕円リフレクタ２の各切片での光線本数の最大値を、第２焦点位置に受光器３を配置したときの光線本数で割った値を示した表である。
【００２９】
【表２】

【００３０】
例えば、第１の切片（Ｒ＝８．３００〜９．２５４）では１．３６倍、第２０の切片（Ｒ＝２４．２９２〜２４．９９５）では１．１５倍、そして、第４６の切片（Ｒ＝３８．４０４〜３８．７９１）では１．００倍となった。各切片ごとの光線本数の最大値の和を、分割していないリフレクタの場合での光線本数で割った値は、１．１０倍となった。即ち、各切片毎の最大となる光線本数を同じ受光面３上に集光させることができれば、この場合で約１０％の効率改善が期待できる。
【００３１】
尚、分割していない楕円リフレクタの場合も同様に、受光器３を光軸上で移動させて、光線本数の最大値を求めたところ、ΔＺ＝−１ｍｍで最大値が得られた。改めて、この値を分母にとった場合でも、１．０９倍の値となった。この場合でも、約９％の改善効果が期待できる。
【００３２】
受光器３の大きさの違いによる期待される改善効果の関係を把握するために、受光器３の大きさを更に、２種類追加し、同様の計算を行った。図６は受光器３の大きさを５×３．７５ｍｍと大きくし同様の計算をした結果であり、対応する受光器サイズの表２の非分割の場合から約６％（ΔＺ＝−１ｍｍで約５％）の改善効果が期待できる。図７は受光器３の大きさを６×４．５ｍｍと大きくし同様の計算をした結果であり、対応する受光器サイズの表２の非分割の場合から約４％（ΔＺ＝−１ｍｍで約３％）の改善効果が期待できる。受光器３が大きくなると、第２焦点位置でも大部分の光線が受光器３に入射するようになってくるので、本発明による改善効果は小さくなってくる。しかし、実際の照明光学系において、受光器３は例えば、ロッドレンズのようなインレグレータに相当するので、受光器３が大きいとは、ロッドレンズが大きいことであり、照明光学系の大型化が必要となる。仮に、照明光学系を大型化できたとしても、ロッドレンズの出射面の光量分布を、液晶パネルに代表されるライトバルブ面上に写像させる必要があり、ロッドレンズが大きいとその写像倍率が小さくなるので、ライトバルブに入射する光束のＦ値が小さくなり、後続の投射レンズで捕捉することが困難になってくる。
【００３３】
次に、図５の設計パラメータを基準パラメータとして、今度はリフレクタの大きさを更に、２種類追加し、同様の計算を行った。図８はリフレクタ２の大きさを０．７５倍し同様の計算をした結果であり、表３は、この場合に対応する、楕円リフレクタ２の各切片での光線本数の最大値を、第２焦点位置に受光器３を配置したときの光線本数で割った値を示した表である。
【００３４】
【表３】

【００３５】
表３から明らかなように、約１２％（ΔＺ＝−２ｍｍで約１１％）の改善効果が期待できる。図９はリフレクタ２の大きさを０．５倍し同様の計算をした結果であり、表３から約１７％（ΔＺ＝−２ｍｍで約１３％）の改善効果が期待できる。分割の基準となる点Ｐ列には、図５での値を０．７５倍した値を使用した。
本来、リフレクタ底部の穴径は、光源が入っている管球を通すためのもので、あり、比例では小さくできないのだが、リフレクタ２の大きさによる全体傾向を把握することと、おおよその改善効果を知るために、比例処理を行った。
【００３６】
更に、図５の設計パラメータを基準パラメータとして、今度は光源１の大きさを更に、２種類追加し、同様の計算を行った。図１０は光源１の大きさを１．１倍し同様の計算をした結果であり、表４は、この場合に対応する、楕円リフレクタ２の各切片での光線本数の最大値を、第２焦点位置に受光器３を配置したときの光線本数で割った値を示した表である。
【００３７】
【表４】

【００３８】
表４から明らかなように、約１３％（ΔＺ＝−２ｍｍで約１１％）の改善効果が期待できる。図１１は光源１の大きさを０．９倍し同様の計算をした結果であり、表４から約７％（ΔＺ＝−２ｍｍで約７％）の改善効果が期待できる。やはり、光源１についても、交流方式か直流方式か、或いは、高圧方式かそうでないか等々で、ある一定のアーク長でも実際の光源１の輝度分布は異なってくるが、光源１の大きさによる全体傾向を把握することと、おおよその改善効果を知るために、比例処理を行った。
【００３９】
次に、表２から表４で求めた改善効果を実現するための手法について、図４を用いて説明する。
【００４０】
図４は、リフレクタ２の切片２１修正前と修正後を、光軸を挟んで図の上下に表した図である。図４の光軸１４から上側がリフレクタ２の切片２１の修正前であり、リフレクタ２の第１焦点位置から出射しリフレクタ２で反射した光線は、リフレクタ２の近軸像位置である第２焦点位置Ｆ２の受光器３に集光する。これに対して、光源１は点光源ではないので、図５から図１１と表２から表４で説明したように、リフレクタ２で光軸に近い部分で反射した場合は、第２焦点位置Ｆ２よりリフレクタ２に近い側に寄った集光位置ＦＡの受光器３に集光する。そこで、第１焦点位置から出射しリフレクタで反射した光線が第２焦点位置Ｆ２よりも、予め、リフレクタ２から遠い側にずれた位置ＦＢに集光（近軸像が結像）するよう設定することによって、点光源でない光源１から出射した光束が、第２焦点位置Ｆ２で受光器３に一番良く集光させることができる。
【００４１】
リフレクタ２のこの修正方法は、大きく分けて２種類の方法がある。先ず、第１の方法の実施形態について述べる。
【００４２】
図１２は、第１の方法の説明図である。各切片を代表する座標としては、例えば、点Ｐｉと点Ｐｉ＋１で定義できる線分の中点を点Ｑｉとして定義する。
【００４３】
第１焦点位置（Ｆ１）から出射した光線がリフレクタ２上の点Ｑｉで反射し、第２焦点位置（Ｆ２）で集光する場合、その光線の傾きは、点ＱｉのＲ座標を、ｆ２から点ＱｉのＺ座標を引いた値で割り、逆正接を取ることで求まる。同様に、ΔＺデフォーカスへの光線の傾きは、分母からΔＺ引いた値で同様の計算をして求まる。従って、図１２のΔθは、求めた２つの角度の差を計算することで求まる。
【００４４】
ここで、リフレクタ２の切片では、反射なので、半分の値Δθ／２分、切片を傾ければ良いことが分かる。
【００４５】
また、点Ｑｉの元々の傾き自体は、楕円の式を微分すれば求まるので、求めた角度をΔθ／２分、逆補正すればよい。点Ｑｉでの傾き（正接と角度）とΔＺとΔθ／２と、逆補正後の正接を表５に示す。
【００４６】
【表５】

【００４７】
もとの基準とした楕円リフレクタの各切片を所定量、それぞれ傾けても良いが、リフレクタ２を十分均等に小さく分割していれば、各切片はＲＺ断面図で直線に近似できるので、その近似した直線を所定量、傾ければ良い。尚、立体的には、光軸に対して回転対称な形状なので、補正後の各切片は、それぞれ円推面の一部となる。
【００４８】
補正後の各円錐面を連続して繋ぐために、隣り合った円錐面どうしの交点（点Ｓ）を求めた。点Ｓ列を表６に示す。尚、Ｓ１は直線Ｒ＝８．３との交点で、Ｓ４７は直線Ｒ＝３８．５との交点で求めた。
【００４９】
【表６】

【００５０】
次に、図１３を用いて、本発明の高効率リフレクタを、ロッドインテグレータを用いた照明光学系に適用した構成について説明する。図１３で、１は光源、２はリフレクタ、４はロッドイングレータとしてロッドレンズを用いた光導波路、１５は１／４波長板、５は平板状のＰ偏光光もしくはＳ偏光光のどちらか一方を透過し他方を反射させる機能を有する反射型偏光板、６は写像レンズ、７はダイクロミラー、８は全反射のミラー、９はフィールドレンズ、１０はリレーレンズ、１１はライトバルブとしてのパネル、１２はクロスプリズム、１３は投射レンズである。光源１から出射した光束は、本発明の光高率なリフレクタ２によりロッドインテグレータ４の入射面に集光し、ロッドインテグレータ４によって一様性を改善される。そして、ロッドインテグレータ４の出射面からの出射光は、後述する１／４波長板１５と反射型偏光板５の作用により所定の偏光方向に揃えられる。一様性が改善されたインテグレータ４の出射側の光量分布は、写像レンズ６によってパネル１１上に写像される。また、パネル直前のフィールドレンズ９は、パネル１１へ入射する光線をテレセントリックとするためのものである。さらに、パネル１１の途中の光路に配置したダイクロミラー７によって白色光は赤色と緑色と青色に分離される。ミラー８によって光路を折り曲げ、光路の長い１色の光路に関しては、リレーレンズ１０を介して、全体として、赤色と緑色と青色の光束は、それぞれ赤用のパネル１１と緑用のパネル１１と青用のパネル１１に照射される。
【００５１】
１／４波長板１５と反射型偏向板５の偏光変換作用について、図１５を用いて以下説明する。図１５は１／４波長板１５と反射型偏向板５の偏光変換作用を説明する図で、（ａ）図は構成を、（ｂ）図はロッドインテグレータ４の一入出射面形状を示す。図１５において、ロッドインテグレータ４は入射面３１に入射面より小さい面積の入射開口部３２が設けられており、該入射開口部３２以外の入射面に反射鏡３３が設けられている。かつ、出射面３４に出射面より小さい面積の出射開口部３５と該出射開口部３５以外の出射面に反射鏡３６が設けられている。また、ロッドインテグレータ４の出射面３４に１／４波長板１５と反射型偏光板５が順に設けられている。本構成においては、入射開口部３２に入射した光束のうち、出射開口部３５以外の反射鏡３６に入射した光束は反射されて入射開口部３２側に戻る。入射開口部３２側に戻ってきた光束のうち、入射開口部３２から漏れていかない光束は反射鏡３３で捕捉されて、出射開口部３５側に折り返される。このような作用が繰り返されて、結局、出射開口部３５を通過する。出射開口部３５を通過した光束は特定の偏向方向の光束のみ反射型偏向板５を透過し、偏向方向が異なる光束は反射される。この反射光のうち入射開口部３２から漏れていかない光束は入射面３１の反射鏡３３で折り返され、再び戻り、反射型偏光板５に入射する。この時、戻ってきた光束は往復で１／４波長板１５を２回通過していることになるので、位相が１／２波長ずれ、偏向方向が所定偏光方向となり、今度は、反射型偏向板５の部分を通過する。このようにして、所定偏光方向に揃えられる。
【００５２】
尚、１／４波長板１５としてはフィルム波長板，水晶板，蒸着膜による波長板などが利用可能であるが、耐熱性の観点から水晶や蒸着膜の方が信頼性や性能が高い。反射型偏光板５としては、金属，無機物もしくはガラス材のワイヤーグリッド型偏光板が適切である。これらを用いれば、反射効率も高くなり、光効率向上が望める。また、偏向方向が問題とならない、ミラー反射のライトバルブ素子との組み合わせにおいては、偏向変換素子（１／４波長板１５と反射型偏光板５）は不要となる。
【００５３】
本発明によれば、リフレクタ２で反射された広がりを有する光源１からの光束は、特開２００２−２４４１９９号公報や特開２００１−１１０２１７号公報で指摘されているような光源像の広がりがなく、インテグレータ４の入射開口面に集光するので、インテグレータ４への入射効率が従来に比べ向上し、高効率なリフレクタを実現することが可能となる。
【００５４】
図１３では、本発明の高効率リフレクタを、ロッドインテグレータを用いた照明光学系に適用したが、一対のレンズアレイを用いたレンズアレイ方式のインテグレータ照明光学系に適用してもよいことは明らかである。特開２００２−２４４１９９号公報の図１０において、リフレクタ６２０を本発明によるリフレクタ２に置き換えれば、広がりを有する光源からの反射光線は、光線６１１のような光線を生じることなく、第２焦点位置Ｆ２に集光するように向かうので、平行化レンズ６４０により光源光軸６００ａＸに略平行とすることができる。
【００５５】
次に、図１４を用いて、本発明の第２の方法の実施の形態について説明する。
【００５６】
図１４は本発明の第２の方法の実施の形態による高効率リフレクタを示す説明図である。図１４において、第２の実施形態のリフレクタ１０２は、第１焦点距離ｆ１＝１６ｍｍ、第２焦点距離ｆ２＝１３７ｍｍ、リフレクタ反射面の有効範囲８．３ｍｍから３８．５ｍｍ（半径表示）の楕円リフレクタを、反射面がφ４０ｍｍからφ７７ｍｍである光軸から離れた側の楕円リフレクタ１０２Ｂはそのままの形状とし、反射面がφ１６．６ｍｍからφ４０ｍｍである光軸に近い側の楕円リフレクタを第１焦点距離ｆ１＝１６ｍｍ、第２焦点距離ｆ２＝１５３ｍｍの楕円リフレクタ１０２Ａで構成したものである。第１焦点距離から出射した光線のうち、光軸から離れた楕円リフレクタ１０２Ｂで反射した光線はリフレクタ頂点（光軸との交点）から１３７ｍｍの第２焦点位置Ｆ２Ｂで集光し、光軸から近い楕円リフレクタ１０２Ａで反射した光線はリフレクタ頂点から１５３ｍｍの第２焦点位置Ｆ２Ａで集光している。このとき、図４で示したように、点光源とは異なるある大きさをもった光源モデルの場合では、光軸に近い楕円リフレクタ１０２Ａの光量最大となる位置が第２焦点位置Ｆ２Ａからリフレクタ側に寄るので、楕円リフレクタ１０２Ａの光量最大となる位置を光軸から離れた楕円リフレクタ１０２Ｂの第２焦点位置Ｆ２Ｂの近傍に一致させることができる。
【００５７】
また、以上のように、本発明によれば、リフレクタの径が大きい部分の修正を実施していないので、楕円リフレクタからロッドレンズへ入射する最大角度が一定のままである。この意味について以下、説明する。
【００５８】
楕円リフレクタの第２焦点距離と第１焦点距離の比で定義できる楕円リフレクタの倍率を小さくすれば、光源の楕円リフレクタによる像の大きさを小さくできるので、ロッドレンズへの入射効率は向上する。しかしながら、このとき、ロッドレンズへ入射する光束の最大角度が大きくなる。即ち、ロッドレンズへ入射する光束のＦ値が小さくなる。この結果、後続の投射レンズでの光束の補足率が劣化する。
【００５９】
従って、本発明では照明光学系のＦ値を変更することなく、高効率なリフレクタを実現しており、照明光学系全体としての光線通過率の改善を実現している。また、本文中で説明したロッドレンズタイプのインテグレータとしては、ロッドレンズに限らず内側に鏡面を有する四角柱、或いは、四角錐の一部でも本発明が成立することは明らかである。
【００６０】
【発明の効果】
以上述べたように、本発明によれば、リフレクタを光軸からの距離で分割し、点光源とは異なる大きさを持った光源による集光位置を、リフレクタの各切片で一致させた高効率リフレクタおよび、及び、それを用いた投射方プロジェクタ装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１における高効率リフレクタの光線図である。
【図２】本発明の実施の形態１におけるリフレクタの各切片での反射光量が最大となる光軸上の位置の求める方を示す説明図である。
【図３】本発明の実施の形態１におけるリフレクタの分割の方法を示す説明図である。
【図４】本発明の実施の形態１のリフレクタの各切片の補正の考え方の説明図である。
【図５】リフレクタの各切片による反射光量の受光器の位置による変化を示す説明図である。
【図６】リフレクタの各切片による反射光量の受光器の位置による変化を示す説明図である。
【図７】リフレクタの各切片による反射光量の受光器の位置による変化を示す説明図である。
【図８】リフレクタの各切片による反射光量の受光器の位置による変化を示す説明図である。
【図９】リフレクタの各切片による反射光量の受光器の位置による変化を示す説明図である。
【図１０】リフレクタの各切片による反射光量の受光器の位置による変化を示す説明図である。
【図１１】リフレクタの各切片による反射光量の受光器の位置による変化を示す説明図である。
【図１２】リフレクタの各切片による反射角度の補正の方法の説明図である。
【図１３】本発明の実施の形態１による高効率リフレクタを用いた照明光学系の構成を示す説明図である。
【図１４】本発明の実施の形態２による高効率リフレクタを示す説明図である。
【図１５】１／４波長板１４と反射型偏向板５の偏光変換作用を説明する図である。
【符号の説明】
１…光源、２…リフレクタ、３…受光器、４…ロッドインテグレータ、５…反射型偏光板、６…写像レンズ、７…ダイクロミラー、８…ミラー、９…フィールドレンズ、１０…リレーレンズ、１１…パネル、１２…クロスプリズムル、１３…投射レンズ、１４…光軸、１５…１／４波長板、３１…入射面、３２…入射開口部、３３…反射鏡、３４…出射面、３５…出射開口部、３６…反射鏡、１０２…リフレクタ。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal projector using a liquid crystal panel. This liquid crystal projector device can be widely used in fields such as a so-called front-projection liquid crystal projector and a projection television.
[0002]
[Prior art]
Liquid crystal projectors for business use have been widely spread. Further, as an alternative to the conventional image display device of the type in which an image displayed on a cathode ray tube is projected on a screen, a projection type television using a liquid crystal display element has been developed.
[0003]
As a liquid crystal projector for business use, a 0.9-inch liquid crystal panel having a brightness exceeding 2000 lumens has been commercialized. However, from the viewpoint of miniaturization and low cost, use of a smaller liquid crystal panel is desired. At this time, as the size of the liquid crystal panel is reduced, the brightness basically decreases. Therefore, the practical use of a more efficient illumination optical system is desired.
[0004]
On the other hand, projection televisions for home use are required to have more faithful color reproducibility, high contrast performance, and quick moving image display performance than liquid crystal projectors for business use. A general method for improving the chromaticity performance is to cut off the light at the wavelengths of the three primary colors of red, green, and blue, and the brightness is greatly deteriorated. Therefore, even in this case, practical use of a more efficient illumination optical system is desired.
[0005]
Conventionally, an elliptical reflector has been used to improve the light use efficiency. In a liquid crystal projector using an elliptical reflector, a light beam emitted from a light source disposed at a first focal position of the elliptical reflector is reflected by the reflector and condensed at a second focal position of the reflector. However, this only holds true strictly when the point light source is arranged at the first focal position of the reflector. Actually, the light source has a certain spread (size) that cannot be regarded as a point light source, and the light beam emitted from the light source is collected near the second focal position of the reflector.
[0006]
Although it is not a method of improving the reflector itself, in the following Patent Document 1, in an elliptical reflector, a concave shape for correcting a light beam having an optical path passing near the light source optical axis to light substantially parallel to the light source optical axis. A method of disposing a correction surface between an elliptical reflector and a second focal point is disclosed.
[0007]
[Patent Document 1]
JP-A-2002-244199
[0008]
[Problems to be solved by the invention]
As described above, the light emitted from the light source arranged at the first focal position of the elliptical reflector is focused at the second focal position when the light source can be regarded as a point light source. Actually, the light source has two bright spots slightly separated from each other, and has a spread. Therefore, as shown in FIG. Light rays emitted from the three bright spots 610b and 610c are condensed at their respective light condensing positions Fb and Fc, and a light source image 614 having a spread around the second focal point F2 is formed.
[0009]
When a lens array type integrator illumination optical system using a pair of lens arrays is used, a convergent reflected light beam from an elliptical reflector is used as a light source substantially parallel to the optical axis, which is shown in FIG. Such a collimating lens 640 is used. However, when the light source cannot be regarded as a point light source, as shown in FIG. 10 of Patent Document 1, for example, the light beam 611 passing near the optical axis cannot be parallelized by the parallelizing lens 640. Therefore, in Patent Document 1, a concave correction surface for correcting a light beam having an optical path passing near the optical axis of the light source to light substantially parallel to the optical axis of the light source is disposed between the elliptical reflector and the second focal point. A method for doing so is disclosed. In FIG. 1 of Patent Document 1, the reflected light beam 11 emitted from the bright spot 20b of the light source and reflected at the bottom of the elliptical reflector 30 is made substantially parallel to the optical axis of the light source by the correction lens 50.
[0010]
However, if there is no physical shielding from the luminescent spot 20b, light rays are emitted in the 360-degree direction, so that the light is reflected even near the maximum aperture diameter of the elliptical reflector 30, for example. In this case, the reflected light from the vicinity of the maximum aperture diameter has a large inclination with respect to the optical axis of the light source (even larger than the light ray 13). It cannot be parallelized to the optical axis.
[0011]
In Patent Document 1, a lens array type integrator illumination optical system is considered, but a rod integrator illumination optical system using a so-called kaleidoscope (kaleidoscope) such as a rod lens is not considered.
[0012]
An object of the present invention is to provide a projector device which solves the above-mentioned problem and achieves high efficiency of a reflector.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, according to the present invention, a light source that emits white light, a reflector that reflects a light beam emitted from the light source to be a convergent light beam directed in an optical axis direction, and a light beam condensed by the reflector And an optical waveguide for equalizing the light flux, a light valve for injecting the light flux uniformized by the optical waveguide, and a projection lens for projecting an optical image formed on the light valve, The reflector is configured as an aggregate of a plurality of segment reflectors divided into a plurality of segments based on the distance from the optical axis, and a light beam from a predetermined point light source on the optical axis is reflected by the reflector and the optical axis is reflected. The position at which the light intercepts the light reflected at the intercept reflector closer to the optical axis than the light reflected at the intercept reflector far from the optical axis is higher than the light intercepted at the intercept reflector. As the position, constitutes tilting the said sections reflector.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the high-efficiency reflector of the present invention will be described with reference to FIGS. 1 to 4 and FIGS. Further, specific grounds for higher efficiency will be described with reference to FIGS. 5 to 11 and Tables 1 to 3. In each of the drawings, common parts are denoted by the same reference numerals, and those that have been described once will not be described repeatedly, and description thereof will be omitted.
[0015]
FIG. 1 illustrates the operation of the reflector of the present invention. In FIG. 1, 1 is a light source, and 2 is a reflector. Generally, in the case of an elliptical reflector, the light emitted from the light source 1 disposed at the first focal position is reflected by the elliptical reflector 2 and focused at the second focal position if the light source is a point light source. However, actually, since the light source 1 cannot be regarded as a point light source, the details will be described later. To deal with this, in the reflector 2 of the present invention, the light beam emitted from the first focal position of the reflector 2 is reflected. The light beam 203 reflected at the portion of the reflector 2 closer to the optical axis 14 is closer to the position where the light beam 203 reflected at the point and intersects the optical axis 14 is reflected at the portion of the reflector 2 closer to the optical axis 14 than the position at which the light beam 203 reflected at the portion of the reflector 2 far from the optical axis 14 intersects. However, it is characterized in that the shape of the reflector 2 is defined so as to be located at a position distant from the reflector 2.
[0016]
This basic idea consists of the following three steps.
[0017]
{Circle around (1)} First, the reflector is divided into a plurality of sections at a distance from the optical axis, and the reflector is defined as an aggregate of each section reflector.
[0018]
(2) Next, a light source model having a size at the first focal position of the elliptical reflector is arranged, and the light is irradiated onto the optical receiver while moving the optical receiver on the optical axis near the second focal position of the elliptical reflector. The position (ΔZ) of the photodetector at which the number of light beams becomes maximum is determined.
[0019]
{Circle around (3)} Finally, the light receiving positions (ΔZ) are inversely corrected, so that the condensing positions of the light beams reflected by all the intercept reflectors are made the same on the optical axis.
[0020]
This will be described below.
[0021]
FIG. 2 shows a state in which a light source model corresponding to the light source 1 having a size at the first focal position of the elliptical reflector 2 is arranged, and the elliptical reflector 2 is divided into a plurality of sections, and the sections 21 of each reflector 2 are used. FIG. 3 is a schematic diagram illustrating a state of condensing a light beam. At this time, the number of light beams received by the light receiver 3 was calculated and compared by moving the position of the light receiver 3 on the optical axis.
[0022]
The method of dividing the slice of the elliptical reflector 2 will be described with reference to FIG. In FIG. 3, an initial point P1 is defined on the elliptical reflector 2, a point at which the linear distance ΔL from the point P1 is constant is defined as P2, and a point having the same linear distance ΔL from the point P2 is defined as a point P3. The elliptical reflector 2 was divided by sequentially obtaining points Pi at which the curve distance ΔL becomes constant. The reason for this is that the effect of high efficiency, which is the object of the present invention, is great by dividing into smaller pieces. However, if the size of the section of the reflector is too small, it becomes difficult to process the section of the small reflector. . Therefore, in order to make the size of the sections of the reflector uniform, the dividing method shown in FIG. 3 was adopted.
[0023]
As the reflector, the reference shape is an ellipse, the first focal length is f1 = 16 mm, the second focal length is f2 = 137 mm, and the effective range of the reflector reflecting surface is 8.3 mm in radius notation (the bottom opening of the elliptical reflector 2). (Part hole diameter) was set to 38.5 mm. On the surface of the elliptical reflector 2, points Pi having a linear distance ΔL of 1 mm ± 0.0005 mm were sequentially obtained. Hereinafter, a point sequence Pi is shown in Table 1. As shown in FIG. 2, the coordinate system is such that the optical axis 14 is the Z axis, the vertical direction from the optical axis is the R axis, and the vertex of the elliptical reflector 2 is set as a reference. This is a coordinate display when (intersection with the optical axis) is set as the origin.
[0024]
[Table 1]

[0025]
Next, at the intercept B1 of the reflector in the range between the points P1 and P2, the number of light rays was calculated by moving the position of the light receiver 3 from ΔZ = −20 mm to ΔZ = 1 mm in increments of 1 mm based on the second focal position. . Hereinafter, similarly, calculation was performed 22 times for each of the intercept B2 of the reflector in the range from the point P2 to the point P3 and the intercept B46 of the reflector in the range from the point P46 to the point P47.
[0026]
Hereinafter, the calculation results will be described with reference to FIGS. 5 to 11 and Tables 2 to 4.
[0027]
In FIG. 5, the size of the light source 1 is 1.4 mm in arc length (corresponding to the size of the light emitting portion), and the size of the light receiver 3 is 4 × 3 mm. The vertical axis in FIG. 5 is the number of light rays. For example, in the first section (R = 8.300 to 9.254), the number of light beams becomes maximum at ΔZ = −19 mm, and in the twentieth section (R = 24.292 to 24.995), ΔZ = −8 mm. The number of light beams became the maximum, and in the 46th section (R = 38.404 to 38.791), the number of light beams became the maximum when ΔZ = 0 mm.
[0028]
Table 2 is a table showing a value obtained by dividing the maximum value of the number of light rays at each section of the elliptical reflector 2 by the number of light rays when the light receiver 3 is arranged at the second focal position.
[0029]
[Table 2]

[0030]
For example, the first section (R = 8.300-9.254) is 1.36 times, the twentieth section (R = 24.292-249.95) is 1.15 times, and the 46th section. (R = 38.404 to 38.791), it was 1.00 times. The value obtained by dividing the sum of the maximum values of the number of light beams for each section by the number of light beams in the case of an undivided reflector was 1.10 times. That is, if the maximum number of light beams for each section can be converged on the same light receiving surface 3, an efficiency improvement of about 10% can be expected in this case.
[0031]
In the case of an undivided elliptical reflector, similarly, when the light receiver 3 was moved on the optical axis to find the maximum value of the number of light beams, the maximum value was obtained at ΔZ = -1 mm. Again, even when this value was taken as the denominator, the value was 1.09 times. Even in this case, an improvement effect of about 9% can be expected.
[0032]
In order to grasp the relationship between the expected improvement effect due to the difference in the size of the light receiver 3, two more sizes of the light receiver 3 were added, and the same calculation was performed. FIG. 6 shows the result of a similar calculation with the size of the photodetector 3 increased to 5 × 3.75 mm, which is approximately 6% (ΔZ = −1 mm) from the corresponding non-divided photoreceiver size in Table 2. An improvement effect of about 5%) can be expected. FIG. 7 shows the result of a similar calculation with the size of the photodetector 3 increased to 6 × 4.5 mm, which is approximately 4% (ΔZ = −1 mm) from the corresponding non-divided photoreceiver size in Table 2. About 3%). As the size of the light receiver 3 increases, most of the light rays enter the light receiver 3 even at the second focal position, and the improvement effect of the present invention decreases. However, in an actual illumination optical system, the light receiver 3 corresponds to, for example, an integrator such as a rod lens. Therefore, a large light receiver 3 means a large rod lens, and it is necessary to increase the size of the illumination optical system. It becomes. Even if the illumination optical system can be made larger, it is necessary to map the light amount distribution on the exit surface of the rod lens onto a light valve surface represented by a liquid crystal panel. Therefore, the F value of the light beam incident on the light valve becomes small, and it becomes difficult to capture the light beam by the subsequent projection lens.
[0033]
Next, using the design parameters of FIG. 5 as reference parameters, two more reflector sizes were added, and the same calculation was performed. FIG. 8 shows the result of a similar calculation with the size of the reflector 2 multiplied by 0.75. Table 3 shows the maximum value of the number of light rays at each section of the elliptical reflector 2 corresponding to this case. It is the table | surface which showed the value which divided | divided by the number of light rays when the photodetector 3 was arrange | positioned at a focal position.
[0034]
[Table 3]

[0035]
As is clear from Table 3, an improvement effect of about 12% (about 11% when ΔZ = −2 mm) can be expected. FIG. 9 shows the result of a similar calculation with the size of the reflector 2 multiplied by 0.5. From Table 3, an improvement effect of about 17% (about 13% when ΔZ = −2 mm) can be expected. The value obtained by multiplying the value in FIG. 5 by 0.75 was used for the point P column serving as a reference for division.
Originally, the diameter of the hole at the bottom of the reflector is for the passage of the bulb containing the light source, and cannot be reduced in proportion. However, it is important to understand the overall tendency due to the size of the reflector 2 and roughly improve the effect. To find out, a proportional process was performed.
[0036]
Further, two types of the size of the light source 1 were added using the design parameters of FIG. 5 as reference parameters, and the same calculation was performed. FIG. 10 shows the result of the same calculation with the size of the light source 1 multiplied by 1.1. Table 4 shows the maximum value of the number of light rays at each section of the elliptical reflector 2 corresponding to this case. It is the table | surface which showed the value which divided | divided by the number of light rays when the photodetector 3 was arrange | positioned at a focal position.
[0037]
[Table 4]

[0038]
As is clear from Table 4, an improvement effect of about 13% (about 11% when ΔZ = −2 mm) can be expected. FIG. 11 shows the result of a similar calculation with the size of the light source 1 multiplied by 0.9, and an improvement effect of about 7% (about 7% at ΔZ = −2 mm) can be expected from Table 4. As for the light source 1, the actual brightness distribution of the light source 1 differs depending on the AC type, the DC type, the high voltage type, or the like. Proportional processing was performed to grasp the overall trend and to know the approximate improvement effect.
[0039]
Next, a method for realizing the improvement effects obtained from Tables 2 to 4 will be described with reference to FIG.
[0040]
FIG. 4 is a diagram showing before and after the correction of the section 21 of the reflector 2 at the top and bottom of the drawing with the optical axis interposed therebetween. The upper side from the optical axis 14 in FIG. 4 is before the correction of the section 21 of the reflector 2, and the light beam emitted from the first focal point position of the reflector 2 and reflected by the reflector 2 is the second focal point which is the paraxial image position of the reflector 2. The light is focused on the light receiver 3 at the position F2. On the other hand, since the light source 1 is not a point light source, as described with reference to FIGS. 5 to 11 and Tables 2 to 4, when light is reflected by the reflector 2 at a portion close to the optical axis, the second focal position F2 The light is condensed on the light receiver 3 at the light condensing position FA closer to the side closer to the reflector 2. Therefore, it is set in advance that the light beam emitted from the first focal position and reflected by the reflector is condensed (a paraxial image is formed) at a position FB shifted farther from the reflector 2 than the second focal position F2. Thus, the light beam emitted from the light source 1 that is not a point light source can be best focused on the light receiver 3 at the second focal position F2.
[0041]
This method of correcting the reflector 2 is roughly classified into two types. First, an embodiment of the first method will be described.
[0042]
FIG. 12 is an explanatory diagram of the first method. As coordinates representing each intercept, for example, the midpoint of a line segment defined by points Pi and Pi + 1 is defined as point Qi.
[0043]
When the light beam emitted from the first focal position (F1) is reflected at the point Qi on the reflector 2 and condensed at the second focal position (F2), the inclination of the light beam is calculated by changing the R coordinate of the point Qi from f2. It is obtained by dividing by the value obtained by subtracting the Z coordinate of the point Qi and taking the arc tangent. Similarly, the inclination of the light beam to ΔZ defocus is obtained by performing the same calculation using a value obtained by subtracting ΔZ from the denominator. Therefore, Δθ in FIG. 12 can be obtained by calculating the difference between the obtained two angles.
[0044]
Here, since the intercept of the reflector 2 is reflected, it can be seen that the intercept should be tilted by half the value Δθ / 2.
[0045]
Further, since the original inclination itself of the point Qi can be obtained by differentiating the elliptic equation, the obtained angle may be inversely corrected by Δθ / 2. Table 5 shows the inclination (tangent and angle), ΔZ and Δθ / 2 at the point Qi, and the tangent after the inverse correction.
[0046]
[Table 5]

[0047]
Each section of the elliptical reflector used as the original reference may be inclined by a predetermined amount. However, if the reflector 2 is divided into small portions evenly, each section can be approximated to a straight line in the RZ sectional view. What is necessary is just to incline the drawn straight line by a predetermined amount. Note that, since the shape is three-dimensionally rotationally symmetric with respect to the optical axis, each of the corrected slices is a part of a circular surface.
[0048]
In order to continuously connect the corrected conical surfaces, an intersection (point S) between adjacent conical surfaces was obtained. Table 6 shows the point S column. Note that S1 was determined at the intersection with the straight line R = 8.3, and S47 was determined at the intersection with the straight line R = 38.5.
[0049]
[Table 6]

[0050]
Next, a configuration in which the high-efficiency reflector of the present invention is applied to an illumination optical system using a rod integrator will be described with reference to FIG. In FIG. 13, 1 is a light source, 2 is a reflector, 4 is an optical waveguide using a rod lens as a rod integrator, 15 is a 1/4 wavelength plate, and 5 is either a plate-shaped P-polarized light or an S-polarized light. A reflective polarizing plate having a function of transmitting light and reflecting the other, 6 is a mapping lens, 7 is a dichroic mirror, 8 is a total reflection mirror, 9 is a field lens, 10 is a relay lens, 11 is a panel as a light valve, 12 is a cross prism, and 13 is a projection lens. The light beam emitted from the light source 1 is condensed on the incident surface of the rod integrator 4 by the light-efficient reflector 2 of the present invention, and the rod integrator 4 improves the uniformity. Then, the light emitted from the emission surface of the rod integrator 4 is aligned in a predetermined polarization direction by the function of a 波長 wavelength plate 15 and a reflective polarizer 5 described later. The light amount distribution on the emission side of the integrator 4 having improved uniformity is mapped on the panel 11 by the mapping lens 6. The field lens 9 immediately before the panel is for making the light beam incident on the panel 11 telecentric. Further, the white light is separated into red, green and blue by the dichroic mirror 7 arranged on the optical path in the middle of the panel 11. The optical path is bent by the mirror 8, and the red, green, and blue luminous fluxes of the red, green, and blue light beams as a whole are transmitted through the relay lens 10 with respect to the light path of one color having a long optical path. To the panel 11 for use.
[0051]
The polarization conversion operation of the quarter-wave plate 15 and the reflective deflecting plate 5 will be described below with reference to FIG. FIGS. 15A and 15B are views for explaining the polarization conversion action of the 波長 wavelength plate 15 and the reflective deflecting plate 5. FIG. 15A shows the configuration, and FIG. In FIG. 15, the rod integrator 4 has an entrance surface 31 provided with an entrance opening 32 having an area smaller than the entrance surface, and a reflection mirror 33 provided on an entrance surface other than the entrance opening 32. In addition, an exit opening 35 having an area smaller than the exit surface is provided on the exit surface 34, and a reflecting mirror 36 is provided on the exit surface other than the exit opening 35. The イ ン テ グ wavelength plate 15 and the reflective polarizer 5 are sequentially provided on the emission surface 34 of the rod integrator 4. In this configuration, of the light beams incident on the entrance opening 32, the light beams incident on the reflecting mirrors 36 other than the exit opening 35 are reflected and return to the entrance opening 32 side. Of the light flux returning to the entrance opening 32 side, the light flux not leaking from the entrance opening 32 is captured by the reflecting mirror 33 and turned back to the exit opening 35 side. Such an operation is repeated, and eventually passes through the emission opening 35. With respect to the light beam that has passed through the emission opening 35, only the light beam in a specific deflection direction is transmitted through the reflective deflecting plate 5, and the light beams having different deflection directions are reflected. Of the reflected light, the light flux that does not leak from the entrance opening 32 is turned back by the reflecting mirror 33 on the incident surface 31, returns again, and enters the reflective polarizing plate 5. At this time, since the returned light beam has passed through the quarter-wave plate 15 twice in a reciprocating manner, the phase is shifted by 波長 wavelength and the deflection direction is the predetermined polarization direction. It passes through the part of the plate 5. In this way, the light is aligned in a predetermined polarization direction.
[0052]
In addition, as the quarter-wave plate 15, a film wave plate, a quartz plate, a wave plate made of a vapor-deposited film, or the like can be used, but from the viewpoint of heat resistance, quartz or a vapor-deposited film has higher reliability and performance. As the reflective polarizer 5, a wire grid polarizer made of metal, inorganic material, or glass material is suitable. If these are used, the reflection efficiency is increased, and improvement in light efficiency can be expected. Further, in a combination with a mirror-reflecting light valve element in which the deflection direction does not matter, the deflection conversion element (the quarter-wave plate 15 and the reflective polarizing plate 5) becomes unnecessary.
[0053]
According to the present invention, the light flux from the light source 1 having the spread reflected by the reflector 2 does not have the spread of the light source image as pointed out in JP-A-2002-244199 and JP-A-2001-110217. Since the light is condensed on the entrance aperture surface of the integrator 4, the incidence efficiency on the integrator 4 is improved as compared with the conventional case, and a highly efficient reflector can be realized.
[0054]
In FIG. 13, the high-efficiency reflector of the present invention is applied to an illumination optical system using a rod integrator. However, it is obvious that the reflector may be applied to a lens array type integrator illumination optical system using a pair of lens arrays. is there. In FIG. 10 of JP-A-2002-244199, if the reflector 620 is replaced with the reflector 2 according to the present invention, the reflected light from the divergent light source does not generate a light like the light 611, and the second focal position F2 Therefore, the light can be made substantially parallel to the light source optical axis 600aX by the collimating lens 640.
[0055]
Next, an embodiment of the second method of the present invention will be described with reference to FIG.
[0056]
FIG. 14 is an explanatory diagram showing a high-efficiency reflector according to an embodiment of the second method of the present invention. In FIG. 14, the reflector 102 of the second embodiment has an elliptical reflector having a first focal length f1 = 16 mm, a second focal length f2 = 137 mm, and an effective range of the reflector reflecting surface of 8.3 mm to 38.5 mm (radius display). The elliptical reflector 102B on the side away from the optical axis having a reflecting surface of φ40 mm to φ77 mm has the same shape, and the elliptical reflector on the side near the optical axis having a reflecting surface of φ16.6 mm to φ40 mm has a first focal length f1. = 16 mm and a second focal length f2 = 153 mm. Of the light rays emitted from the first focal length, the light rays reflected by the elliptical reflector 102B away from the optical axis are condensed at a second focal position F2B 137 mm from the reflector vertex (intersection with the optical axis) and are close to the optical axis. The light beam reflected by the elliptical reflector 102A is collected at a second focal position F2A 153 mm from the top of the reflector. At this time, as shown in FIG. 4, in the case of the light source model having a certain size different from the point light source, the position where the amount of light of the elliptical reflector 102A near the optical axis becomes maximum is from the second focal position F2A to the reflector side. Therefore, the position where the amount of light of the elliptical reflector 102A becomes maximum can be made to coincide with the vicinity of the second focal position F2B of the elliptical reflector 102B far from the optical axis.
[0057]
Further, as described above, according to the present invention, since the correction of the portion where the diameter of the reflector is large is not performed, the maximum angle of incidence from the elliptical reflector to the rod lens remains constant. The meaning will be described below.
[0058]
If the magnification of the elliptical reflector, which can be defined by the ratio of the second focal length to the first focal length of the elliptical reflector, is reduced, the size of the image formed by the elliptical reflector of the light source can be reduced, so that the efficiency of incidence on the rod lens is improved. However, at this time, the maximum angle of the light beam incident on the rod lens becomes large. That is, the F value of the light beam incident on the rod lens becomes small. As a result, the rate at which the light beam is captured by the subsequent projection lens deteriorates.
[0059]
Therefore, in the present invention, a highly efficient reflector is realized without changing the F value of the illumination optical system, and the light transmittance of the entire illumination optical system is improved. It is apparent that the present invention is not limited to the rod lens but may be a quadratic prism having a mirror surface inside or a part of a quadrangular pyramid as the rod lens type integrator described in the text.
[0060]
【The invention's effect】
As described above, according to the present invention, the reflector is divided by the distance from the optical axis, and the light-collecting position of the light source having a size different from that of the point light source is matched by each section of the reflector. It is possible to provide a reflector and a projector using the same.
[Brief description of the drawings]
FIG. 1 is a ray diagram of a high-efficiency reflector according to Embodiment 1 of the present invention.
FIG. 2 is an explanatory diagram showing how to find a position on the optical axis where the amount of reflected light at each section of the reflector according to the first embodiment of the present invention is maximum.
FIG. 3 is an explanatory diagram showing a method of dividing the reflector according to the first embodiment of the present invention.
FIG. 4 is an explanatory diagram of a concept of correcting each intercept of the reflector according to the first embodiment of the present invention.
FIG. 5 is an explanatory diagram showing a change in the amount of light reflected by each section of the reflector depending on the position of a light receiver;
FIG. 6 is an explanatory diagram showing a change in the amount of light reflected by each section of the reflector depending on the position of the light receiver;
FIG. 7 is an explanatory diagram showing a change in the amount of light reflected by each section of the reflector depending on the position of the light receiver;
FIG. 8 is an explanatory diagram showing a change in the amount of light reflected by each section of the reflector depending on the position of the light receiver;
FIG. 9 is an explanatory diagram showing a change in the amount of light reflected by each section of the reflector depending on the position of the light receiver;
FIG. 10 is an explanatory diagram showing a change in the amount of light reflected by each section of the reflector depending on the position of the light receiver;
FIG. 11 is an explanatory diagram showing a change in the amount of light reflected by each section of the reflector depending on the position of the light receiver;
FIG. 12 is an explanatory diagram of a method of correcting a reflection angle by each section of the reflector.
FIG. 13 is an explanatory diagram showing a configuration of an illumination optical system using the high-efficiency reflector according to the first embodiment of the present invention.
FIG. 14 is an explanatory diagram showing a high-efficiency reflector according to a second embodiment of the present invention.
FIG. 15 is a diagram for explaining the polarization conversion action of the 波長 wavelength plate 14 and the reflection type deflection plate 5;
[Explanation of symbols]
REFERENCE SIGNS LIST 1 light source 2 reflector 3 light receiver 4 rod integrator 5 reflection polarizer 6 mapping lens 7 dichroic mirror 8 mirror 9 field lens 10 relay lens 11 ... panel, 12 ... cross prism, 13 ... projection lens, 14 ... optical axis, 15 ... 1/4 wavelength plate, 31 ... entrance surface, 32 ... entrance aperture, 33 ... reflecting mirror, 34 ... exit surface, 35 ... Outgoing aperture, 36 ... Reflector, 102 ... Reflector.

Claims (5)

A light source that emits white light,
A reflector that reflects a light beam emitted from the light source and makes the light beam a convergent light beam directed in the optical axis direction.
An optical waveguide that receives the light beam condensed by the reflector and makes the light beam uniform,
A light valve for injecting a light beam uniformized by the optical waveguide;
Having a projection lens that projects an optical image formed on the light valve,
The reflector is configured as an aggregate of a plurality of segment reflectors divided into a plurality of segments based on a distance from the optical axis,
The position at which the light beam from a predetermined point light source on the optical axis is reflected by the reflector and intersects the optical axis is closer to the optical axis than the position at which the light beam reflected by the intercept reflector far from the optical axis intersects the optical axis. A projector apparatus characterized in that the section reflector is inclined so that a light ray reflected by a close section reflector is located farther from the reflector. A light source that emits white light,
A reflector that reflects a light beam emitted from the light source and has an elliptical surface as a basic shape to be a convergent light beam directed in the optical axis direction,
An optical waveguide that receives the light beam condensed by the reflector and makes the light beam uniform,
A light valve for injecting a light beam uniformized by the optical waveguide;
Having a projection lens that projects an optical image formed on the light valve,
The reflector is configured as an aggregate of a plurality of conical reflectors divided into a plurality of sections based on a distance from the optical axis,
The position where the light beam emitted from the first focal position of the elliptical surface is reflected by the reflector and intersects the optical axis is closer to the optical axis than the position where the light beam reflected by the conical reflector far from the optical axis intersects the optical axis. A projector device having a configuration in which the inclination of the conical reflector is determined such that a light beam reflected by a near conical reflector is located at a position farther from the reflector. A light source that emits white light,
A reflector that reflects a light beam emitted from the light source and has an elliptical surface as a basic shape to be a convergent light beam directed in the optical axis direction,
An optical waveguide that receives the light beam condensed by the reflector and makes the light beam uniform,
A light valve for injecting a light beam uniformized by the optical waveguide;
Having a projection lens that projects an optical image formed on the light valve,
The reflector is configured as an aggregate of a plurality of elliptical reflectors divided into a plurality of sections based on a distance from the optical axis,
A projector device, wherein a second focal length of the elliptical reflector closer to the optical axis is longer than a second focal length of the elliptical reflector farther from the optical axis. The optical waveguide has an entrance opening having an area smaller than the entrance surface on the entrance surface, and a reflecting mirror provided on the entrance surface other than the entrance opening, and an exit opening having an area smaller than the exit surface on the exit surface. 4. The projector device according to claim 1, wherein a reflection mirror is provided on the emission surface other than the emission opening. 5. The projector device according to claim 4, wherein the optical waveguide includes a quarter-wave plate and a polarizing plate provided in this order on the emission surface. 6.

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