JP2023178056A

JP2023178056A - Optical element, eyepiece optical system having the same, and image display device

Info

Publication number: JP2023178056A
Application number: JP2022091103A
Authority: JP
Inventors: 洋輔酒井; Yosuke Sakai
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2022-06-03
Filing date: 2022-06-03
Publication date: 2023-12-14

Abstract

To provide an optical element that can enable a light beam with a wide angle of view to reach the pupil of an observer.SOLUTION: An optical element guides a light beam from an image display element to the pupil of an observer, and the optical element has a first deflection unit that makes the light beam incident on an inner face of the optical element; a second deflection unit that deflects the light beam totally reflected on the inner face multiple times to emit the light beam toward the pupil; and a semi-transmission and reflection unit that includes a first semi-transmission and reflection surface and a second semi-transmission and reflection surface, which are arranged in order from a side of the first deflection unit to a side of the second deflection unit. The second semi-transmission and reflection surface reflects part of the light beam from the first semi-transmission and reflection surface to the side of the first semi-transmission and reflection surface.SELECTED DRAWING: Figure 4

Description

本発明は、画像表示素子からの光束を観察者の瞳に導光する光学素子に関する。 The present invention relates to an optical element that guides a luminous flux from an image display element to an observer's pupil.

従来、画像表示素子からの光束を観察者の瞳に導光する導光板（光学素子）を備える画像表示装置が提案されている。図１０は、従来の導光板１００内を伝搬する光束の概念図である。画像表示素子から射出された光束は、第１偏向部１１０に入射し、偏向された後、全反射条件を満たすため導光板１００内を伝搬し、第２偏向部１２０に入射する。第２偏向部１２０に入射した光束の一部は偏向されて観察者の瞳ＳＰに向かい、他の一部は反射し、導光板１００内を伝搬し、第２偏向部１２０に入射する。このような構成により、観察者が光束を観察可能な領域を拡大することができる。 2. Description of the Related Art Conventionally, image display devices have been proposed that include a light guide plate (optical element) that guides a light beam from an image display element to an observer's pupil. FIG. 10 is a conceptual diagram of a light beam propagating within a conventional light guide plate 100. The light beam emitted from the image display element enters the first deflection section 110 and is deflected, then propagates within the light guide plate 100 to satisfy the total reflection condition and enters the second deflection section 120. A portion of the light beam incident on the second deflection unit 120 is deflected and directed toward the observer's pupil SP, and the other portion is reflected, propagates within the light guide plate 100, and enters the second deflection unit 120. With such a configuration, it is possible to expand the area where the observer can observe the light flux.

特許文献１には、画像表示装置の広視野化を実現するために、高い屈折率を有する材料によって形成された導光板が開示されている。 Patent Document 1 discloses a light guide plate formed of a material having a high refractive index in order to realize a wide field of view of an image display device.

特開２０１９－０２０７２３号公報JP 2019-020723 Publication

しかしながら、特許文献１の導光板を使用して広画角の光束を導光する際に、導光板から射出される光束間の幅が大きくなり、観察者の瞳まで光が到達しない場合がある。 However, when the light guide plate of Patent Document 1 is used to guide a light beam with a wide angle of view, the width between the light beams emitted from the light guide plate becomes large, and the light may not reach the viewer's eyes. .

本発明は、広画角の光束を観察者の瞳まで到達させることが可能な光学素子を提供することを目的とする。 SUMMARY OF THE INVENTION An object of the present invention is to provide an optical element that allows a light beam with a wide angle of view to reach an observer's pupil.

本発明の一側面としての光学素子は、画像表示素子からの光束を観察者の瞳に導光する光学素子であって、光束を偏向して光学素子の内面に入射させる第１偏向部と、内面で全反射した光束を複数回偏向することで瞳の側へ射出する第２偏向部と、第１偏向部の側から第２偏向部の側へ順に配置された、第１半透過反射面と第２半透過反射面とを備える半透過反射部とを有し、第２半透過反射面は、第１半透過反射面からの光束の一部を第１半透過反射面の側へ反射することを特徴とする。 An optical element according to one aspect of the present invention is an optical element that guides a light flux from an image display element to an observer's pupil, and includes a first deflection section that deflects the light flux and makes it enter the inner surface of the optical element. a second deflection section that deflects the light beam totally reflected on the inner surface multiple times to emit it to the pupil side; and a first semi-transmissive reflection surface arranged in order from the first deflection section side to the second deflection section side. and a second semi-transmissive reflective surface, the second semi-transparent reflective surface reflects a part of the luminous flux from the first semi-transparent reflective surface toward the first semi-transparent reflective surface. It is characterized by

本発明によれば、広画角の光束を観察者の瞳まで到達させることが可能な光学素子を提供することができる。 According to the present invention, it is possible to provide an optical element that allows a light beam with a wide angle of view to reach an observer's pupil.

本発明の実施形態に係る導光板を用いた画像表示装置の構成を示す図である。1 is a diagram showing the configuration of an image display device using a light guide plate according to an embodiment of the present invention. 第１の実施形態の導光板の構成を示す図である。It is a figure showing the composition of the light guide plate of a 1st embodiment. 第１偏向部と第２偏向部の変形例を示す図である。It is a figure which shows the modification of a 1st deflection part and a 2nd deflection part. 第１の実施形態の導光板内を伝搬する光束の概念図である。FIG. 3 is a conceptual diagram of a light beam propagating within the light guide plate of the first embodiment. 射出される光束の光束径と光束間の幅の概念図である。FIG. 3 is a conceptual diagram of the diameter of the emitted light beam and the width between the light beams. 第１の実施形態の導光板の構成を示す図である。It is a figure showing the composition of the light guide plate of a 1st embodiment. 第２の実施形態の導光板内を伝搬する光束の概念図である。FIG. 7 is a conceptual diagram of a light beam propagating within the light guide plate of the second embodiment. 数値実施例１乃至３の導光板への入射光束の入射角と射出される光束間の幅の関係とを示す図である。FIG. 3 is a diagram showing the relationship between the incident angle of a light beam entering a light guide plate and the width between emitted light beams in Numerical Examples 1 to 3; 数値実施例４乃至６の導光板への入射光束の入射角と射出される光束間の幅の関係とを示す図である。FIG. 7 is a diagram showing the relationship between the incident angle of the light beam entering the light guide plate and the width between the emitted light beams in Numerical Examples 4 to 6; 導光板内を伝搬する光束の概念図である（従来例）。FIG. 2 is a conceptual diagram of a light beam propagating within a light guide plate (conventional example). 導光板から射出される光束間の幅の説明図である（従来例）。FIG. 3 is an explanatory diagram of the width between light beams emitted from a light guide plate (conventional example).

以下、本発明の実施形態について、図面を参照しながら詳細に説明する。各図において、同一の部材については同一の参照番号を付し、重複する説明は省略する。 Embodiments of the present invention will be described in detail below with reference to the drawings. In each figure, the same reference numerals are given to the same members, and duplicate explanations will be omitted.

まず、図１１を参照して、従来の導光板１００から射出される光束間の幅について説明する。図１１は、従来の導光板１００から射出される光束間の幅Ｄ０の説明図である。光束間の幅Ｄ０は、導光板１００への入射光束の入射角θによって変化する。入射角θが最も大きい光束、すなわち広画角（最周辺画角）の光束が導光板１００に入射する場合に光束間の幅は最大となる。光束間の幅Ｄ０が大きすぎる場合、観察者の瞳ＳＰまで広画角の光束が到達しない可能性がある。 First, with reference to FIG. 11, the width between the light beams emitted from the conventional light guide plate 100 will be described. FIG. 11 is an explanatory diagram of the width D0 between the light beams emitted from the conventional light guide plate 100. The width D0 between the light beams changes depending on the incident angle θ of the light beam incident on the light guide plate 100. When the light beam with the largest incident angle θ, that is, the light beam with a wide angle of view (the most peripheral angle of view) enters the light guide plate 100, the width between the light beams becomes maximum. If the width D0 between the light beams is too large, the wide-angle light beam may not reach the viewer's pupil SP.

図１は、本発明の実施形態に係る画像表示装置の構成を示す図である。画像表示装置は、導光板（光学素子）１０、画像表示素子を含む画像形成装置８１、及び画像形成装置８１から射出された光束を導光板１０に導光する光学系８２を有する。導光板１０は、画像表示素子からの光束を観察者の瞳ＳＰに導光する。本実施形態では、導光板１０と光学系８２により接眼光学系が構成される。なお、画像形成装置８１、及び光学系８２はそれぞれ、２次状に配列されたパネル、及びコリメート光学系から構成されてもよいし、レーザープロジェクタ、及びＭＥＭＳミラーとリレーレンズ光学系から構成されてもよい。 FIG. 1 is a diagram showing the configuration of an image display device according to an embodiment of the present invention. The image display device includes a light guide plate (optical element) 10 , an image forming device 81 including an image display element, and an optical system 82 that guides the light flux emitted from the image forming device 81 to the light guide plate 10 . The light guide plate 10 guides the light flux from the image display element to the viewer's pupil SP. In this embodiment, the light guide plate 10 and the optical system 82 constitute an eyepiece optical system. Note that the image forming device 81 and the optical system 82 may each be composed of panels arranged in a quadratic manner and a collimating optical system, or may be composed of a laser projector, a MEMS mirror, and a relay lens optical system. Good too.

以下、各実施形態の導光板１０の構成について説明する。
［第１の実施形態］
図２は、本実施形態の導光板１０の構成を示す図である。図２（ａ）は、本実施形態の導光板１０内を伝搬する第１光束を示している。図２（ｂ）は、本実施形態の導光板１０内を伝搬する第２光束を示している。図２（ｃ）は、本実施形態の導光板１０内を伝搬する光束を示している。 The configuration of the light guide plate 10 of each embodiment will be described below.
[First embodiment]
FIG. 2 is a diagram showing the configuration of the light guide plate 10 of this embodiment. FIG. 2(a) shows the first light flux propagating within the light guide plate 10 of this embodiment. FIG. 2(b) shows the second light flux propagating within the light guide plate 10 of this embodiment. FIG. 2(c) shows a light beam propagating within the light guide plate 10 of this embodiment.

導光板１０は、第１偏向部１１及び第２偏向部１２を有する。第１偏向部１１は、導光板１０への入射光束を偏向して導光板１０の内面に入射させる。第２偏向部１２は、導光板１０の内面で全反射した光束を複数回偏向することで瞳ＳＰの側へ射出する。 The light guide plate 10 has a first deflection section 11 and a second deflection section 12. The first deflection unit 11 deflects the light beam incident on the light guide plate 10 and makes it enter the inner surface of the light guide plate 10 . The second deflection unit 12 deflects the light beam totally reflected on the inner surface of the light guide plate 10 multiple times to emit it toward the pupil SP.

なお、第１偏向部１１及び第２偏向部１５は、図３（ａ）に示されるように、回折格子１５１から構成されてもよい。また、第１偏向部１１及び第２偏向部１５は、図３（ｂ）に示されるように、ホログラム回折素子１６１から構成されてもよい。回折格子１５１及びホログラム回折素子１６１は、透過型であってもよいし、反射型であってもよい。また、第１偏向部１１及び第２偏向部１５は、図３（ｃ）に示されるように、反射面１７１を備えていてもよい。更に、また、第１偏向部１１及び第２偏向部１５は、図３（ｄ）に示されるように、プリズム１８１から構成されてもよい。第１偏向部１１及び第２偏向部１２は、上述した構成の一つから構成されてもよいし、複数から構成されてもよい。 Note that the first deflection section 11 and the second deflection section 15 may be composed of a diffraction grating 151, as shown in FIG. 3(a). Further, the first deflection section 11 and the second deflection section 15 may be composed of a hologram diffraction element 161, as shown in FIG. 3(b). The diffraction grating 151 and the hologram diffraction element 161 may be of a transmission type or a reflection type. Furthermore, the first deflection section 11 and the second deflection section 15 may include a reflective surface 171, as shown in FIG. 3(c). Furthermore, the first deflection section 11 and the second deflection section 15 may be composed of a prism 181, as shown in FIG. 3(d). The first deflection section 11 and the second deflection section 12 may be composed of one of the above-mentioned structures, or may be composed of a plurality of them.

また、本実施形態の導光板１０は、第１偏向部１１と第２偏向部１２との間の光路上に配置された、半透過反射部を有する。本実施形態では、半透過反射部は、第１偏向部１１の側から第２偏向部１２の側へ順に配置された、第１半透過反射部３１、第２半透過反射部３２を備える。第１半透過反射部３１は第１半透過反射面を備え、第２半透過反射部３２は第２半透過反射面を備える。 Moreover, the light guide plate 10 of this embodiment has a semi-transmissive reflective part arranged on the optical path between the first deflecting part 11 and the second deflecting part 12. In this embodiment, the transflective section includes a first transflective section 31 and a second transflective section 32, which are arranged in this order from the first deflecting section 11 side to the second deflecting section 12 side. The first semi-transmissive reflective section 31 includes a first semi-transmissive reflective surface, and the second semi-transmissive reflective section 32 includes a second semi-transmissive reflective surface.

導光板１０の内面を全反射により伝搬する光束は、第１半透過反射部３１の第１半透過反射面に入射する。第１半透過反射面を透過した光束は、第２半透過反射部３２の第２半透過反射面を透過する第１光束３３と、第２半透過反射面で反射する第２光束３４とに分けられる。 The light beam propagating through the inner surface of the light guide plate 10 by total reflection is incident on the first semi-transmissive reflective surface of the first semi-transmissive reflective section 31 . The light beam that has passed through the first semi-transparent reflective surface is divided into a first light beam 33 that passes through the second semi-transparent reflective surface of the second semi-transparent reflective section 32 and a second light beam 34 that is reflected by the second semi-transparent reflective surface. Can be divided.

第１光束３３は、図２（ａ）に示されるように、導光板１０の内面を全反射により伝搬し、第２偏向部１２によって複数回偏向される。 As shown in FIG. 2A, the first light beam 33 propagates through the inner surface of the light guide plate 10 by total reflection, and is deflected multiple times by the second deflection section 12.

第２光束３４は、図２（ｂ）に示されるように、第１半透過反射面で反射し、第２半透過反射部面を透過した後、導光板１０の内面を全反射により伝搬し、第２偏向部１２によって複数回偏向される。 As shown in FIG. 2B, the second light beam 34 is reflected by the first semi-transparent reflective surface, transmitted through the second semi-transparent reflective surface, and then propagated through the inner surface of the light guide plate 10 by total reflection. , are deflected multiple times by the second deflection section 12.

本実施形態では、導光板１０の内面に複数の半透過反射面を設けることで、図２（ｃ）に示されるように、従来の射出される光束間の幅Ｄ０と比較して、射出される光束間の幅Ｄ１を小さくすることができる。したがって、高画角の光束が観察者の瞳に到達することができるため、画像表示装置の広視野化を実現することができる。 In this embodiment, by providing a plurality of transflective surfaces on the inner surface of the light guide plate 10, as shown in FIG. The width D1 between the light beams can be reduced. Therefore, since the light beam with a high angle of view can reach the viewer's eyes, it is possible to realize a wide field of view of the image display device.

なお、本実施形態では、第１半透過反射部３１及び第２半透過反射部３２は、第１半透過反射面と第２半透過反射面とが平行となるように配置されていることが好ましい。これにより、第２偏向部１２から射出される複数の光束が平行になるため、第２偏向部１２から射出される光束による観察像が一致するようになる。ここで、平行とは、厳密に平行である場合だけでなく、実質的に平行（略平行）である場合も含んでいるものとする。 In addition, in this embodiment, the first semi-transmissive reflective section 31 and the second semi-transmissive reflective section 32 may be arranged such that the first semi-transmissive reflective surface and the second semi-transmissive reflective surface are parallel to each other. preferable. As a result, the plurality of light beams emitted from the second deflection section 12 become parallel, so that the observed images of the light beams emitted from the second deflection section 12 coincide. Here, parallel includes not only strictly parallel but also substantially parallel (substantially parallel).

また、本実施形態では、第１半透過反射部３１及び第２半透過反射部３２は、第１半透過反射面と第２半透過反射面とが導光板１０の入射光束が入射する面に対して垂直となるように配置されることが好ましい。これにより、第１半透過反射部３１及び第２半透過反射部３２の製造を容易にすると共に、第１半透過反射面と第２半透過反射面の平行度を高めることができる。ここで、垂直とは、厳密に垂直である場合だけでなく、実質的に垂直（略垂直）である場合も含んでいるものとする。 Furthermore, in the present embodiment, the first semi-transmissive reflective section 31 and the second semi-transmissive reflective section 32 have the first semi-transmissive reflective surface and the second semi-transmissive reflective surface on the surface on which the incident light beam of the light guide plate 10 enters. It is preferable that they be arranged perpendicularly to each other. This makes it possible to easily manufacture the first semi-transmissive reflective section 31 and the second semi-transmissive reflective section 32, and to increase the parallelism between the first semi-transmissive reflective surface and the second semi-transmissive reflective surface. Here, "vertical" includes not only strictly vertical, but also substantially vertical (substantially vertical).

また、本実施形態では、導光板１０は、以下の条件式（１）を満足することが好ましい。 Moreover, in this embodiment, it is preferable that the light guide plate 10 satisfies the following conditional expression (1).

０．２０＜Ｌ／（ｔ・ｔａｎ（α））－ｎ＜０．８０（１）
ここで、ｔは、導光板１０の厚さ（）である。Ｌは、第１半透過反射面と第２半透過反射面との間隔である。αは、導光板１０への入射光束の最大入射角である。ｎは、０以上の整数である。 0.20<L/(t・tan(α))−n<0.80 (1)
Here, t is the thickness () of the light guide plate 10. L is the distance between the first semi-transmissive reflective surface and the second semi-transmissive reflective surface. α is the maximum angle of incidence of the light beam incident on the light guide plate 10. n is an integer greater than or equal to 0.

条件式（１）は、導光板１０の厚さ及び第１半透過反射面と第２半透過反射面との間隔を規定する。図４は、本実施形態の導光板１０内を伝搬する光束の概念図である。ここで、導光板１０の厚さ及び第１半透過反射面と第２半透過反射面との間隔に応じた導光板１０から射出される光束間の幅の変化について説明するため、間隔Ｌを以下の式（２）で表す。 Conditional expression (1) defines the thickness of the light guide plate 10 and the interval between the first semi-transparent reflective surface and the second semi-transparent reflective surface. FIG. 4 is a conceptual diagram of a light beam propagating within the light guide plate 10 of this embodiment. Here, in order to explain the change in the width between the light beams emitted from the light guide plate 10 according to the thickness of the light guide plate 10 and the interval between the first semi-transparent reflective surface and the second semi-transparent reflective surface, the interval L is It is expressed by the following formula (2).

Ｌ＝Ｌ０＋ｎ・ｔ・ｔａｎ（α）（０≦Ｌ０＜ｔ・ｔａｎ（α））（２）
間隔Ｌがｔ・ｔａｎ（α）の整数倍分変化しても光束間の幅は変わらないため、値Ｌ０の範囲で光束間の幅を議論してよい。第２偏向部１２から射出される光束による第１の間隔をｄ１、第２の間隔をｄ２とするとき、第１の間隔ｄ１と第２の間隔ｄ２はそれぞれ、以下の式（３），（４）で表される。 L=L0+n・t・tan(α) (0≦L0<t・tan(α)) (2)
Since the width between the luminous fluxes does not change even if the interval L changes by an integral multiple of t·tan(α), the width between the luminous fluxes may be discussed within the range of the value L0. When the first interval between the light beams emitted from the second deflection unit 12 is d1 and the second interval is d2, the first interval d1 and the second interval d2 are expressed by the following equations (3) and ( 4).

ｄ１＝２・ｔ・ｔａｎ（α）－２・Ｌ０（３）
ｄ２＝２・Ｌ０（４）
導光板１０が条件式（１）を満足することで、第１の間隔ｄ１及び第２の間隔ｄ２を小さくすることができる。すなわち、射出される光束間の幅を小さくすることができる。条件式（１）の下限値を下回ると、第１の間隔ｄ１が大きくなりすぎ、射出される光束間の幅を小さくすることができない。条件式（１）の上限値を上回ると、第２の間隔ｄ２が大きくなりすぎ、射出される光束間の幅を小さくすることができない。 d1=2・t・tan(α)−2・L0 (3)
d2=2・L0 (4)
When the light guide plate 10 satisfies conditional expression (1), the first distance d1 and the second distance d2 can be reduced. That is, the width between the emitted light beams can be reduced. If the lower limit of conditional expression (1) is exceeded, the first interval d1 becomes too large, making it impossible to reduce the width between the emitted light beams. If the upper limit of conditional expression (1) is exceeded, the second interval d2 becomes too large, making it impossible to reduce the width between the emitted light beams.

なお、条件式（１）の数値範囲を以下の条件式（１ａ）の数値範囲とすることが好ましい。 Note that it is preferable that the numerical range of conditional expression (1) be the numerical range of conditional expression (1a) below.

０．２５＜Ｌ／（ｔ・ｔａｎ（α））－ｎ＜０．７５（１ａ）
また、条件式（１）の数値範囲を以下の条件式（１ｂ）の数値範囲とすることが更に好ましい。 0.25<L/(t・tan(α))−n<0.75 (1a)
Furthermore, it is more preferable that the numerical range of conditional expression (1) be the numerical range of conditional expression (1b) below.

０．３０＜Ｌ／（ｔ・ｔａｎ（α））－ｎ＜０．７０（１ｂ）
また、本実施形態では、導光板１０は、以下の条件式（５）を満足することが好ましい。 0.30<L/(t・tan(α))−n<0.70 (1b)
Further, in the present embodiment, it is preferable that the light guide plate 10 satisfies the following conditional expression (5).

０．５０＜Φ／（ｔ・ｔａｎ（β））＜２．００（５）
ここで、Φは、導光板１０の入射面における導光板１０への入射光束の光束径である。βは、導光板１０の入射面における導光板１０への入射光束の最小入射角である。 0.50<Φ/(t・tan(β))<2.00 (5)
Here, Φ is the diameter of the light beam incident on the light guide plate 10 at the incident surface of the light guide plate 10. β is the minimum incident angle of the light beam incident on the light guide plate 10 on the incident surface of the light guide plate 10.

条件式（５）は、導光板１０の厚さ及び入射光束の光束径を規定する。図５は、射出される光束の光束径Φと光束間の幅Ｄの概念図である。導光板１０が条件式（５）を満足することで、第２偏向部１２から射出される光束による間隔ｄと入射光束の光束径Φとの差分である射出される光束間の幅Ｄを小さくすることができる。条件式（５）の下限値を下回ると、入射光束の光束径Φが小さくなりすぎ、射出される光束間の幅Ｄを小さくすることができず好ましくない。条件式（５）の上限値を上回ると、入射光束が導光板１０の内面で全反射した後、再度導光板１０に入射するため好ましくない。 Conditional expression (5) defines the thickness of the light guide plate 10 and the diameter of the incident light beam. FIG. 5 is a conceptual diagram of the luminous flux diameter Φ of the emitted luminous flux and the width D between the luminous fluxes. When the light guide plate 10 satisfies conditional expression (5), the width D between the emitted light beams, which is the difference between the distance d between the light beams emitted from the second deflection unit 12 and the light beam diameter Φ of the incident light beam, is reduced. can do. If the lower limit of conditional expression (5) is not reached, the diameter Φ of the incident light beam becomes too small, making it impossible to reduce the width D between the emitted light beams, which is not preferable. If the upper limit of conditional expression (5) is exceeded, the incident light beam will be totally reflected on the inner surface of the light guide plate 10 and then enter the light guide plate 10 again, which is not preferable.

なお、条件式（５）の数値範囲を以下の条件式（５ａ）の数値範囲とすることが好ましい。 Note that it is preferable that the numerical range of conditional expression (5) be the numerical range of conditional expression (5a) below.

０．５５＜Φ／（ｔ・ｔａｎ（β））＜１．９５（５ａ）
また、条件式（５）の数値範囲を以下の条件式（５ｂ）の数値範囲とすることが更に好ましい。 0.55<Φ/(t・tan(β))<1.95 (5a)
Furthermore, it is more preferable that the numerical range of conditional expression (5) be the numerical range of conditional expression (5b) below.

０．６０＜Φ／（ｔ・ｔａｎ（β））＜１．９０（５ｂ）
［第２の実施形態］
図６は、本実施形態の導光板１０の構成を示す図である。図６（ａ）は、本実施形態の導光板１０内を伝搬する第１光束を示している。図６（ｂ）は、本実施形態の導光板１０内を伝搬する第２光束を示している。図６（ｃ）は、本実施形態の導光板１０内を伝搬する光束を示している。 0.60<Φ/(t・tan(β))<1.90 (5b)
[Second embodiment]
FIG. 6 is a diagram showing the configuration of the light guide plate 10 of this embodiment. FIG. 6(a) shows the first light flux propagating within the light guide plate 10 of this embodiment. FIG. 6(b) shows the second light flux propagating within the light guide plate 10 of this embodiment. FIG. 6(c) shows a light beam propagating within the light guide plate 10 of this embodiment.

本実施形態の導光板１０は、第１の実施形態と同様に、第１偏向部１１及び第２偏向部１２を有する。また、本実施形態の導光板１０は、第１偏向部１１と第２偏向部１２との間の光路上に配置された、半透過反射部を有する。本実施形態では、半透過反射部は、第１偏向部１１の側から第２偏向部１２の側へ順に配置された、第１半透過反射部５１、第３半透過反射部５２、第２半透過反射部５３を備える。第１半透過反射部５１は偏光選択性半透過反射機能による第１半透過反射面を備え、第３半透過反射部５２は第３半透過反射面を備え、第２半透過反射部５３は偏光選択性半透過反射機能による第２半透過反射面を備える。また、本実施形態の導光板１０は、第１半透過反射面と第３半透過反射面との間の光路上に配置された第１四分の一波長板５４、及び第３半透過反射面と第２半透過反射面との間の光路上に配置された第２四分の一波長板５５を有する。第１四分の一波長板５４と第２四分の一波長板５５は、それぞれの遅相軸が９０°傾くように配置される。第１半透過反射部５１と第２半透過反射部５３は、第１半透過反射面の偏光透過軸と第２半透過反射面の偏光透過軸とが平行となるように配置される。第１半透過反射部５１と第１四分の一波長板５４は、第１半透過反射面の偏光透過軸に対して第１四分の一波長板５４の遅相軸が４５°傾くように配置される。 The light guide plate 10 of this embodiment has a first deflection section 11 and a second deflection section 12, similarly to the first embodiment. Moreover, the light guide plate 10 of this embodiment has a semi-transmissive reflective part arranged on the optical path between the first deflecting part 11 and the second deflecting part 12. In the present embodiment, the transflective sections include a first transflective section 51, a third transflective section 52, and a second transflective section arranged from the first deflecting section 11 side to the second deflecting section 12 side in this order. A transflective section 53 is provided. The first transflective section 51 includes a first transflective surface with a polarization selective transflective function, the third transflective section 52 includes a third semitransmissive reflective surface, and the second transflective section 53 includes a third semitransmissive reflective surface. A second transflective surface with a polarization selective transflective function is provided. The light guide plate 10 of this embodiment also includes a first quarter-wave plate 54 disposed on the optical path between the first semi-transmissive reflective surface and the third semi-transmissive reflective surface, and a third semi-transmissive reflective surface. A second quarter-wave plate 55 is disposed on the optical path between the surface and the second transflective surface. The first quarter-wave plate 54 and the second quarter-wave plate 55 are arranged such that their respective slow axes are inclined by 90 degrees. The first transflective section 51 and the second semi-transmissive reflective section 53 are arranged such that the polarized light transmission axis of the first semi-transmissive reflective surface and the polarized light transmission axis of the second semi-transmissive reflective surface are parallel to each other. The first semi-transmissive reflecting section 51 and the first quarter-wave plate 54 are configured such that the slow axis of the first quarter-wave plate 54 is inclined by 45 degrees with respect to the polarized light transmission axis of the first semi-transmissive reflecting surface. will be placed in

第１偏向部１１により導光板１０の内面を全反射により伝搬する光束は、第１半透過反射面に入射する。第１半透過反射面を透過した光束は、直線偏光となり、第１四分の一波長板５４によって円偏光となり、第３半透過反射面に入射する。第３半透過反射面に入射した光は、第３半透過反射面を透過する第１光束５６と、第３半透過反射面で反射する第２光束５７とに分けられる。 The light beam that propagates through the inner surface of the light guide plate 10 by total reflection by the first deflection unit 11 is incident on the first semi-transmissive reflective surface. The light beam transmitted through the first semi-transmissive reflective surface becomes linearly polarized light, becomes circularly polarized light by the first quarter-wave plate 54, and enters the third semi-transmissive reflective surface. The light incident on the third semi-transmissive reflective surface is divided into a first beam 56 that passes through the third semi-transmissive reflective surface and a second beam 57 that is reflected by the third semi-transmissive reflective surface.

第１光束５６はまず、第２四分の一波長板５５によって第１半透過反射面を透過した際の方向と直交した方向へ偏光した直線偏光になる。次に、第１光束５６は、第２半透過反射面で反射し、第２四分の一波長板５５によって最初に第１四分の一波長板５４によって円偏光となった際と逆回りの円偏光となり第３半透過反射面に入射する。次に、第１光束５６は、第３半透過反射面で反射し、第２四分の一波長板５５によって第１半透過反射面を透過した際の方向と同じ方向へ偏光した直線偏光になる。その後、第１光束５６は、第２半透過反射面を透過して第２偏向部１２によって複数回偏向される。 The first light beam 56 first becomes linearly polarized light by the second quarter-wave plate 55 in a direction perpendicular to the direction in which it passes through the first semi-transmissive reflective surface. Next, the first light beam 56 is reflected by the second semi-transmissive reflective surface, and is turned into circularly polarized light by the second quarter-wave plate 55 and first by the first quarter-wave plate 54 in the opposite direction. becomes circularly polarized light and enters the third semi-transmissive reflective surface. Next, the first light beam 56 is reflected by the third semi-transmissive reflective surface, and converted into linearly polarized light by the second quarter-wave plate 55 in the same direction as the direction in which it was transmitted through the first semi-transmissive reflective surface. Become. Thereafter, the first light beam 56 passes through the second transflective surface and is deflected multiple times by the second deflection section 12.

第２光束５７はまず、第１四分の一波長板５４によって第１半透過反射面を透過した際の方向と直交した方向へ偏光した直線偏光になる。次に、第２光束５７は、第１半透過反射面で反射し、第１四分の一波長板５４によって最初に第１四分の一波長板５４によって円偏光となった際と逆回りの円偏光となり第３半透過反射面に入射する。次に、第２光束５７は、第３半透過反射面を透過し、第２四分の一波長板５５によって第１半透過反射面を通過した際の方向と同じ方向へ偏光した直線偏光になる。その後、第２光束５７は、第２半透過反射面を透過して第２偏向部１２によって複数回偏向される。 The second light beam 57 first becomes linearly polarized light by the first quarter-wave plate 54 in a direction perpendicular to the direction in which it passes through the first semi-transmissive reflective surface. Next, the second light beam 57 is reflected by the first semi-transmissive reflective surface and rotates in the opposite direction to that when it first became circularly polarized light by the first quarter-wave plate 54. becomes circularly polarized light and enters the third semi-transmissive reflective surface. Next, the second light beam 57 is transmitted through the third semi-transmissive reflective surface, and converted into linearly polarized light by the second quarter-wave plate 55 in the same direction as the direction in which it passed through the first semi-transmissive reflective surface. Become. Thereafter, the second light beam 57 passes through the second transflective surface and is deflected multiple times by the second deflection section 12.

本実施形態では、導光板１０の内面に複数の半透過反射面を設けることで、図７に示されるように、従来の射出される光束間の幅Ｄ０と比較して、射出される光束間の幅Ｄ２を小さくすることができる。したがって、高画角の光束が観察者の瞳に到達することができるため、画像表示装置の広視野化を実現することができる。 In this embodiment, by providing a plurality of transflective surfaces on the inner surface of the light guide plate 10, as shown in FIG. width D2 can be made smaller. Therefore, since the light beam with a high angle of view can reach the viewer's eyes, it is possible to realize a wide field of view of the image display device.

なお、本実施形態では、第１偏向部１１及び第１半透過反射部５１は、第１偏向部１１によって導光板１０の内面を全反射により伝搬する光束の偏光方向と第１半透過反射面の偏光透過軸とが平行となるように配置されることが好ましい。これにより、導光板１０の内面を全反射により伝搬する光束の第１半透過反射面を透過する効率が高くなる。 In the present embodiment, the first deflection section 11 and the first semi-transmissive reflection section 51 are configured to adjust the polarization direction of the light beam propagated by total reflection on the inner surface of the light guide plate 10 by the first deflection section 11 and the first semi-transmission reflection surface. It is preferable that the polarized light transmission axes of the polarized light beams and the polarized light transmission axes thereof be parallel to each other. This increases the efficiency with which the light flux propagating through the inner surface of the light guide plate 10 by total reflection is transmitted through the first semi-transparent reflection surface.

また、導光板１０は、以下の条件式（３）を満足することが好ましい。 Further, it is preferable that the light guide plate 10 satisfies the following conditional expression (3).

０．２０＜｜ａ－ｂ｜／（ｔ・ｔａｎ（α））－ｎ＜０．８０（６）
ここで、ｔは、導光板１０の厚さである。ａは、第１半透過反射面と第３半透過反射面との間隔である。ｂは、第３半透過反射面と第２半透過反射面との間隔である。αは、導光板１０への入射光束の最大入射角である。ｎは、０以上の整数である。 0.20<|a-b|/(t・tan(α))-n<0.80 (6)
Here, t is the thickness of the light guide plate 10. a is the distance between the first semi-transmissive reflective surface and the third semi-transmissive reflective surface. b is the distance between the third semi-transmissive reflective surface and the second semi-transmissive reflective surface. α is the maximum angle of incidence of the light beam incident on the light guide plate 10. n is an integer greater than or equal to 0.

条件式（６）は、導光板１０の厚さ及び半透過反射面の間隔を規定する。図１０は、本実施形態の導光板１０内を伝搬する光束の概念図である。ここで、導光板１０の厚さと半透過反射面の間隔に応じた導光板１０から射出される光束間の幅の変化について説明するため、絶対値｜ａ－ｂ｜を以下の式（７）で表す。 Conditional expression (6) defines the thickness of the light guide plate 10 and the interval between the transflective surfaces. FIG. 10 is a conceptual diagram of a light beam propagating within the light guide plate 10 of this embodiment. Here, in order to explain the change in the width between the light beams emitted from the light guide plate 10 according to the thickness of the light guide plate 10 and the interval between the transflective surfaces, the absolute value |a−b| is expressed by the following equation (7). Expressed as

｜ａ－ｂ｜＝Ｌ０＋ｎ・ｔ・ｔａｎ（α）（０≦Ｌ０＜ｔ・ｔａｎ（α））（７）
絶対値｜ａ－ｂ｜がｔ・ｔａｎ（α）の整数倍分変化しても光束間の間隔は変わらないため、値Ｌ０の範囲で光束間の間隔を議論してよい。第２偏向部１２から射出される光束による第１の間隔をｄ１、第２の間隔をｄ２とするとき、第１の間隔ｄ１と第２の間隔ｄ２はそれぞれ、以下の式（８），（９）で表される。 |a-b|=L0+n・t・tan(α) (0≦L0<t・tan(α)) (7)
Since the interval between luminous fluxes does not change even if the absolute value |ab| changes by an integral multiple of t·tan(α), the interval between luminous fluxes may be discussed within the range of value L0. When the first interval between the light beams emitted from the second deflector 12 is d1 and the second interval is d2, the first interval d1 and the second interval d2 are expressed by the following equations (8) and ( 9).

ｄ１＝２・ｔ・ｔａｎ（α）－２・Ｌ０（８）
ｄ２＝２・Ｌ０（９）
導光板１０が条件式（６）を満足することで、第１の間隔ｄ１及び第２の間隔ｄ２を小さくすることができる。すなわち、射出される光束間の幅を小さくすることができる。条件式（６）の下限値を下回ると、第１の間隔ｄ１が大きくなりすぎ、射出される光束間の幅を小さくすることができない。条件式（６）の上限値を上回ると、第２の間隔ｄ２が大きくなりすぎ、射出される光束間の幅を小さくすることができない。 d1=2・t・tan(α)−2・L0 (8)
d2=2・L0 (9)
When the light guide plate 10 satisfies conditional expression (6), the first distance d1 and the second distance d2 can be reduced. That is, the width between the emitted light beams can be reduced. If the lower limit of conditional expression (6) is not reached, the first interval d1 becomes too large, making it impossible to reduce the width between the emitted light beams. If the upper limit of conditional expression (6) is exceeded, the second interval d2 becomes too large, making it impossible to reduce the width between the emitted light beams.

なお、条件式（６）の数値範囲を以下の条件式（６ａ）の数値範囲とすることが好ましい。 Note that it is preferable that the numerical range of conditional expression (6) be the numerical range of conditional expression (6a) below.

０．２５＜｜ａ－ｂ｜／（ｔ・ｔａｎ（α））－ｎ＜０．７５（６ａ）
また、条件式（６）の数値範囲を以下の条件式（６ｂ）の数値範囲とすることが更に好ましい。 0.25<|a-b|/(t・tan(α))-n<0.75 (6a)
Furthermore, it is more preferable that the numerical range of conditional expression (6) be the numerical range of conditional expression (6b) below.

０．３０＜｜ａ－ｂ｜／（ｔ・ｔａｎ（α））－ｎ＜０．７０（６ｂ）
以下、各実施形態の導光板１０の具体的な構成について説明する。 0.30<|a-b|/(t・tan(α))-n<0.70 (6b)
Hereinafter, the specific configuration of the light guide plate 10 of each embodiment will be described.

数値実施例１乃至３の導光板１０は、第１の実施形態の導光板１０と同様の構成を有する。 The light guide plates 10 of Numerical Examples 1 to 3 have the same configuration as the light guide plate 10 of the first embodiment.

数値実施例１では、導光板１０の厚さは０．９０ｍｍ、第１半透過反射面と第２半透過反射面との間隔は１．２５ｍｍである。また、導光板１０への入射光束の最大入射角は６５°、導光板１０への入射光束の最小入射角は４５°、導光板１０への入射光束の光束径は１．００ｍｍである。更に、導光板１０から射出される光束間の幅は、１．５０ｍｍ以下である。 In Numerical Example 1, the thickness of the light guide plate 10 is 0.90 mm, and the distance between the first semi-transmissive reflective surface and the second semi-transmissive reflective surface is 1.25 mm. Further, the maximum angle of incidence of the light flux incident on the light guide plate 10 is 65°, the minimum angle of incidence of the light flux incident on the light guide plate 10 is 45°, and the diameter of the light flux incident on the light guide plate 10 is 1.00 mm. Furthermore, the width between the light beams emitted from the light guide plate 10 is 1.50 mm or less.

数値実施例２では、導光板１０の厚さは１．５０ｍｍ、第１半透過反射面と第２半透過反射面との間隔は１．１０ｍｍである。また、導光板１０への入射光束の最大入射角は６１°、導光板１０への入射光束の最小入射角は３５°、導光板１０への入射光束の光束径は１．００ｍｍである。更に、導光板１０から射出される光束間の幅は、２．００ｍｍ以下である。 In Numerical Example 2, the thickness of the light guide plate 10 is 1.50 mm, and the distance between the first semi-transmissive reflective surface and the second semi-transmissive reflective surface is 1.10 mm. Further, the maximum angle of incidence of the light flux incident on the light guide plate 10 is 61°, the minimum angle of incidence of the light flux incident on the light guide plate 10 is 35°, and the diameter of the light flux incident on the light guide plate 10 is 1.00 mm. Furthermore, the width between the light beams emitted from the light guide plate 10 is 2.00 mm or less.

数値実施例３では、導光板１０の厚さは０．８０ｍｍ、第１半透過反射面と第２半透過反射面との間隔は１．４５ｍｍである。また、導光板１０への入射光束の最大入射角は７４°、導光板１０への入射光束の最小入射角は３２°、導光板１０への入射光束の光束径は０．９０ｍｍである。更に、導光板１０から射出される光束間の幅は、２．００ｍｍ以下である。 In Numerical Example 3, the thickness of the light guide plate 10 is 0.80 mm, and the distance between the first semi-transmissive reflective surface and the second semi-transmissive reflective surface is 1.45 mm. Further, the maximum angle of incidence of the light flux incident on the light guide plate 10 is 74°, the minimum angle of incidence of the light flux incident on the light guide plate 10 is 32°, and the diameter of the light flux incident on the light guide plate 10 is 0.90 mm. Furthermore, the width between the light beams emitted from the light guide plate 10 is 2.00 mm or less.

図８は、数値実施例１乃至３の導光板１０への入射光束の入射角と射出される光束間の幅の関係とを示す図である。図８に示されるように、数値実施例１乃至３の導光板１０を用いることで、射出される光束間の幅を小さくすることができる。これにより、高画角の光束が観察者の瞳に到達することができるため、画像表示装置の広視野化を実現することができる。 FIG. 8 is a diagram showing the relationship between the angle of incidence of the light beams incident on the light guide plate 10 and the width between the emitted light beams in Numerical Examples 1 to 3. As shown in FIG. 8, by using the light guide plate 10 of Numerical Examples 1 to 3, the width between the emitted light beams can be reduced. This allows the light beam with a high angle of view to reach the viewer's eyes, making it possible to achieve a wide field of view of the image display device.

数値実施例４乃至６の導光板１０は、第２の実施形態の導光板１０と同様の構成を有する。 The light guide plates 10 of Numerical Examples 4 to 6 have the same configuration as the light guide plate 10 of the second embodiment.

数値実施例４では、導光板１０の厚さは０．９０ｍｍ、第１半透過反射面と第３半透過反射面との間隔は１．００ｍｍ、第３半透過反射面と第２半透過反射面との間隔は２．１０ｍｍである。また、導光板１０への入射光束の最大入射角は６４°、導光板１０への入射光束の最小入射角は４２°、導光板１０への入射光束の光束径は１．００ｍｍである。更に、導光板１０から射出される光束間の幅は、１．５０ｍｍ以下である。 In Numerical Example 4, the thickness of the light guide plate 10 is 0.90 mm, the distance between the first semi-transmissive reflective surface and the third semi-transmissive reflective surface is 1.00 mm, and the distance between the third semi-transmissive reflective surface and the second semi-transmissive reflective surface is 1.00 mm. The distance from the surface is 2.10 mm. Further, the maximum angle of incidence of the light flux incident on the light guide plate 10 is 64°, the minimum angle of incidence of the light flux incident on the light guide plate 10 is 42°, and the diameter of the light flux incident on the light guide plate 10 is 1.00 mm. Furthermore, the width between the light beams emitted from the light guide plate 10 is 1.50 mm or less.

数値実施例５では、導光板１０の厚さは１．４０ｍｍ、第１半透過反射面と第３半透過反射面との間隔は３．００ｍｍ、第３半透過反射面と第２半透過反射面との間隔は１．７５ｍｍである。また、導光板１０への入射光束の最大入射角は６４°、導光板１０への入射光束の最小入射角は４２°、導光板１０への入射光束の光束径は１．００ｍｍである。更に、導光板１０から射出される光束間の幅は、１．７５ｍｍ以下である。 In Numerical Example 5, the thickness of the light guide plate 10 is 1.40 mm, the distance between the first semi-transmissive reflective surface and the third semi-transmissive reflective surface is 3.00 mm, and the distance between the third semi-transmissive reflective surface and the second semi-transmissive reflective surface is 3.00 mm. The distance from the surface is 1.75 mm. Further, the maximum angle of incidence of the light flux incident on the light guide plate 10 is 64°, the minimum angle of incidence of the light flux incident on the light guide plate 10 is 42°, and the diameter of the light flux incident on the light guide plate 10 is 1.00 mm. Furthermore, the width between the light beams emitted from the light guide plate 10 is 1.75 mm or less.

数値実施例６では、導光板１０の厚さは０．８０ｍｍ、第１半透過反射面と第３半透過反射面の間隔は２．５０ｍｍ、第３半透過反射面と第２半透過反射面の間隔は１．０５ｍｍである。また、導光板１０への入射光束の最大入射角は７４°、導光板１０への入射光束の最小入射角は３４°、導光板１０への入射光束の光束径は０．９０ｍｍである。更に、導光板１０から射出される光束間の幅は、２．００ｍｍ以下である。 In Numerical Example 6, the thickness of the light guide plate 10 is 0.80 mm, the distance between the first semi-transmissive reflective surface and the third semi-transmissive reflective surface is 2.50 mm, and the third semi-transmissive reflective surface and the second semi-transmissive reflective surface. The interval between is 1.05 mm. Further, the maximum angle of incidence of the light flux incident on the light guide plate 10 is 74°, the minimum angle of incidence of the light flux incident on the light guide plate 10 is 34°, and the diameter of the light flux incident on the light guide plate 10 is 0.90 mm. Furthermore, the width between the light beams emitted from the light guide plate 10 is 2.00 mm or less.

図９は、数値実施例４乃至６の導光板１０への入射光束の入射角と射出される光束間の幅の関係とを示す図である。図９に示されるように、数値実施例４乃至６の導光板１０を用いることで、射出される光束間の幅を小さくすることができる。これにより、高画角の光束が観察者の瞳に到達することができるため、画像表示装置の広視野化を実現することができる。 FIG. 9 is a diagram showing the relationship between the angle of incidence of the light beams incident on the light guide plate 10 and the width between the emitted light beams in Numerical Examples 4 to 6. As shown in FIG. 9, by using the light guide plate 10 of Numerical Examples 4 to 6, the width between the emitted light beams can be reduced. This allows the light beam with a high angle of view to reach the viewer's eyes, making it possible to achieve a wide field of view of the image display device.

各数値実施例における種々の値を、以下の表１にまとめて示す。 Various values in each numerical example are summarized in Table 1 below.

本実施形態の開示は、以下の構成を含む。
（構成１）
画像表示素子からの光束を観察者の瞳に導光する光学素子であって、
前記光束を偏向して前記光学素子の内面に入射させる第１偏向部と、
前記内面で全反射した前記光束を複数回偏向することで前記瞳の側へ射出する第２偏向部と、
前記第１偏向部の側から前記第２偏向部の側へ順に配置された、第１半透過反射面と第２半透過反射面とを有し、
前記第２半透過反射面は、前記第１半透過反射面からの光束の一部を前記第１半透過反射面の側へ反射することを特徴とする光学素子。
（構成２）
前記第１偏向部により偏向された光束は、前記第１半透過反射面を透過した後、前記第２半透過反射面により前記第２半透過反射面を透過する第１光束と前記第２半透過反射面で反射する第２光束とに分けられ、
前記第１光束は、前記第２偏向部に入射し、
前記第２光束は、前記第１半透過反射面で反射し、前記第２半透過反射面を透過し、前記第２偏向部に入射することを特徴とする構成１に記載の光学素子。
（構成３）
前記第１半透過反射面と前記第２半透過反射面とが互いに平行であることを特徴とする構成１又は２に記載の光学素子。
（構成４）
前記第１半透過反射面と前記第２半透過反射面とが前記第１の偏向部の入射面に対して垂直であることを特徴とする請求項１乃至３の何れか一つの構成に記載の光学素子。
（構成５）
前記光学素子の厚さをｔ、前記第１半透過反射面と前記第２半透過反射面との間隔をＬ、前記第１の偏向部に対する前記光束の最大入射角をα、ｎを０以上の整数とするとき、
０．２０＜Ｌ／（ｔ・ｔａｎ（α））－ｎ＜０．８０
なる条件式を満足することを特徴とする請求項１乃至４の何れか一つの構成に記載の光学素子。
（構成６）
前記光学素子の厚さをｔ、前記光学素子の入射面における前記光束の光束径をΦ、前記第１の偏向部に対する前記光束の最小入射角をβとするとき、
０．５０＜Φ／（ｔ・ｔａｎ（β））＜２．００
なる条件式を満足することを特徴とする請求項１乃至５の何れか一つの構成に記載の光学素子。
（構成７）
前記半透過反射部は、前記第１偏向部の側から前記第２偏向部の側へ順に配置された、偏光選択性半透過反射機能による前記第１半透過反射面、第３半透過反射面、偏光選択性半透過反射機能による前記第２半透過反射面を備えることを特徴とする請求項１に記載の光学素子。
（構成８）
前記内面で全反射した前記光束の偏光方向と前記第１半透過反射面の偏光透過軸とが互いに平行であることを特徴とする請求項７に記載の光学素子。
（構成９）
前記第１半透過反射面と前記第３半透過反射面との間の光路上に配置された第１四分の一波長板と、
前記第３半透過反射面と前記第２半透過反射面の間の光路上に配置された第２四分の一波長板とを更に有し、
前記第１四分の一波長板、及び前記第２四分の一波長板は、それぞれの遅相軸が９０°傾くように配置され、
前記第１半透過反射面の偏光透過軸と前記第２半透過反射面の偏光透過軸とが互いに平行であり、
前記第１半透過反射面の偏光透過軸に対して前記第１四分の一波長板の遅相軸が４５°傾くことを特徴とする請求項７又は８に記載の光学素子。
（構成１０）
前記第１偏向部により偏向された光束は、前記第１半透過反射面を透過し、前記第１四分の一波長板を透過した後、前記第３半透過反射面により前記第３半透過反射面を透過する第１光束と前記第３半透過反射面で反射する第２光束とに分けられ、
前記第１光束は、前記第２四分の一波長板を透過し、前記第２半透過反射面で反射し、前記第２四分の一波長板を透過し、前記第３半透過反射面で反射し、前記第２四分の一波長板を透過し、前記第２半透過反射面を透過し、前記第２偏向部に入射し、
前記第２光束は、前記第１四分の一波長板を透過し、前記第１半透過反射面で反射し、前記第１四分の一波長板を透過し、前記第３半透過反射面を透過し、前記第２四分の一波長板を透過し、前記第２半透過反射面を透過し、前記第２偏向部に入射することを特徴とする請求項９に記載の光学素子。
（構成１１）
前記光学素子の厚さをｔ、前記第１半透過反射面と前記第３半透過反射面との間隔をａ、前記第３半透過反射面と前記第２半透過反射面との間隔をｂ、前記光束の最大入射角をα、ｎを０以上の整数とするとき、
０．２０＜｜ａ－ｂ｜／（ｔ・ｔａｎ（α））－ｎ＜０．８０
なる条件式を満足することを特徴とする請求項７乃至１０の何れか一つの構成に記載の光学素子。
（構成１２）
構成１乃至１１の何れか一つの構成に記載の光学素子と、
画像表示素子からの光束を前記光学素子に導光する光学系とを有することを特徴とする接眼光学系。
（構成１３）
構成１乃至１１の何れか一つの構成の光学素子と、
画像表示素子と、
前記画像表示素子からの光束前記光学素子に導光する光学系とを有することを特徴とする画像表示装置。 The disclosure of this embodiment includes the following configurations.
(Configuration 1)
An optical element that guides a luminous flux from an image display element to an observer's pupil,
a first deflection unit that deflects the light beam and causes it to enter the inner surface of the optical element;
a second deflection unit that deflects the light beam totally reflected on the inner surface multiple times to emit it to the pupil side;
a first semi-transmissive reflective surface and a second semi-transmissive reflective surface arranged in order from the first deflecting section side to the second deflecting section side;
The optical element is characterized in that the second semi-transmissive reflective surface reflects a part of the luminous flux from the first semi-transmissive reflective surface toward the first semi-transmissive reflective surface.
(Configuration 2)
After the light beam deflected by the first deflection unit passes through the first semi-transparent reflective surface, the second semi-transparent reflective surface separates the first light beam that passes through the second semi-transparent reflective surface and the second semi-transparent reflective surface. It is divided into a second beam of light reflected by a transmissive reflective surface,
The first light flux is incident on the second deflection section,
The optical element according to configuration 1, wherein the second light beam is reflected by the first semi-transparent reflective surface, transmitted through the second semi-transparent reflective surface, and enters the second deflection section.
(Configuration 3)
3. The optical element according to configuration 1 or 2, wherein the first semi-transmissive reflective surface and the second semi-transmissive reflective surface are parallel to each other.
(Configuration 4)
4. The configuration according to claim 1, wherein the first semi-transmissive reflective surface and the second semi-transmissive reflective surface are perpendicular to the incident plane of the first deflection section. optical element.
(Configuration 5)
The thickness of the optical element is t, the distance between the first semi-transmissive reflective surface and the second semi-transmissive reflective surface is L, the maximum angle of incidence of the light beam with respect to the first deflection section is α, and n is 0 or more. When it is an integer of
0.20<L/(t・tan(α))−n<0.80
5. The optical element according to claim 1, wherein the optical element satisfies the following conditional expression.
(Configuration 6)
When the thickness of the optical element is t, the diameter of the light beam at the incident surface of the optical element is Φ, and the minimum incident angle of the light beam with respect to the first deflection section is β,
0.50<Φ/(t・tan(β))<2.00
6. The optical element according to claim 1, wherein the optical element satisfies the following conditional expression.
(Configuration 7)
The transflective section includes the first semi-transmissive reflective surface and the third semi-transmissive reflective surface having a polarization selective semi-transmissive reflective function, which are arranged in order from the first deflecting section side to the second deflecting section side. 2. The optical element according to claim 1, further comprising: the second semi-transmissive reflective surface having a polarization selective semi-transmissive reflective function.
(Configuration 8)
8. The optical element according to claim 7, wherein the polarization direction of the light beam totally reflected by the inner surface and the polarization transmission axis of the first semi-transmissive reflective surface are parallel to each other.
(Configuration 9)
a first quarter-wave plate disposed on the optical path between the first semi-transmissive reflective surface and the third semi-transmissive reflective surface;
further comprising a second quarter-wave plate disposed on the optical path between the third semi-transmissive reflective surface and the second semi-transmissive reflective surface,
The first quarter-wave plate and the second quarter-wave plate are arranged such that their respective slow axes are inclined by 90°,
The polarized light transmission axis of the first semi-transparent reflective surface and the polarized light transmission axis of the second semi-transparent reflective surface are parallel to each other,
9. The optical element according to claim 7, wherein the slow axis of the first quarter-wave plate is inclined by 45 degrees with respect to the polarization transmission axis of the first semi-transmissive reflective surface.
(Configuration 10)
The light beam deflected by the first deflector passes through the first semi-transparent reflective surface, passes through the first quarter-wave plate, and then is deflected by the third semi-transmissive reflective surface. divided into a first beam of light that passes through the reflective surface and a second beam of light that is reflected by the third semi-transparent reflective surface;
The first light beam passes through the second quarter-wave plate, is reflected by the second semi-transmissive reflective surface, passes through the second quarter-wave plate, and is reflected by the third semi-transmissive reflective surface. , transmitted through the second quarter-wave plate, transmitted through the second semi-transparent reflective surface, and incident on the second deflection section,
The second light beam passes through the first quarter-wave plate, is reflected by the first semi-transparent reflective surface, passes through the first quarter-wave plate, and is reflected by the third semi-transmissive reflective surface. 10. The optical element according to claim 9, wherein the light passes through the second quarter-wave plate, passes through the second semi-transmissive reflective surface, and enters the second deflection section.
(Configuration 11)
The thickness of the optical element is t, the distance between the first semi-transparent reflective surface and the third semi-transparent reflective surface is a, and the distance between the third semi-transparent reflective surface and the second semi-transparent reflective surface is b. , when the maximum incident angle of the luminous flux is α, and n is an integer of 0 or more,
0.20<|a-b|/(t・tan(α))-n<0.80
11. The optical element according to claim 7, wherein the optical element satisfies the following conditional expression.
(Configuration 12)
The optical element according to any one of configurations 1 to 11,
An eyepiece optical system comprising: an optical system that guides a luminous flux from an image display element to the optical element.
(Configuration 13)
An optical element having any one of configurations 1 to 11,
an image display element;
An image display device comprising: an optical system that guides a luminous flux from the image display element to the optical element.

以上、本発明の好ましい実施形態について説明したが、本発明はこれらの実施形態に限定されず、その要旨の範囲内で種々の変形及び変更が可能である。 Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the invention.

１０導光板（光学素子）
１１第１偏向部
１２第２偏向部
３１，５１第１半透過反射部
３２，５３第２半透過反射部
10 Light guide plate (optical element)
11 First deflection section 12 Second deflection section 31, 51 First semi-transparent reflection section 32, 53 Second semi-transmission reflection section

Claims

An optical element that guides a luminous flux from an image display element to an observer's pupil,
a first deflection unit that deflects the light beam and causes it to enter the inner surface of the optical element;
a second deflection unit that deflects the light beam totally reflected on the inner surface multiple times to emit it to the pupil side;
a semi-transmissive reflective section including a first semi-transmissive reflective surface and a second semi-transmissive reflective surface arranged in order from the first deflecting section side to the second deflecting section side;
The optical element is characterized in that the second semi-transmissive reflective surface reflects a part of the luminous flux from the first semi-transmissive reflective surface toward the first semi-transmissive reflective surface.

After the light beam deflected by the first deflection unit passes through the first semi-transparent reflective surface, the second semi-transparent reflective surface separates the first light beam that passes through the second semi-transparent reflective surface and the second semi-transparent reflective surface. It is divided into a second beam of light reflected by a transmissive reflective surface,
The first light flux is incident on the second deflection section,
The optical element according to claim 1, wherein the second light beam is reflected by the first semi-transparent reflective surface, transmitted through the second semi-transparent reflective surface, and enters the second deflection section.

3. The optical element according to claim 1, wherein the first semi-transmissive reflective surface and the second semi-transmissive reflective surface are parallel to each other.

3. The optical element according to claim 1, wherein the first semi-transmissive reflective surface and the second semi-transmissive reflective surface are perpendicular to an incident surface of the first deflection section.

The thickness of the optical element is t, the distance between the first semi-transmissive reflective surface and the second semi-transmissive reflective surface is L, the maximum angle of incidence of the light beam with respect to the first deflection section is α, and n is 0 or more. When it is an integer of
0.20<L/(t・tan(α))−n<0.80
3. The optical element according to claim 1, wherein the optical element satisfies the following conditional expression.

When the thickness of the optical element is t, the diameter of the light beam at the incident surface of the optical element is Φ, and the minimum incident angle of the light beam with respect to the first deflection section is β,
0.50<Φ/(t・tan(β))<2.00
3. The optical element according to claim 1, wherein the optical element satisfies the following conditional expression.

The transflective section includes the first semi-transmissive reflective surface and the third semi-transmissive reflective surface having a polarization selective semi-transmissive reflective function, which are arranged in order from the first deflecting section side to the second deflecting section side. 2. The optical element according to claim 1, further comprising: the second semi-transmissive reflective surface having a polarization selective semi-transmissive reflective function.

8. The optical element according to claim 7, wherein the polarization direction of the light beam totally reflected by the inner surface and the polarization transmission axis of the first semi-transmissive reflective surface are parallel to each other.

a first quarter-wave plate disposed on the optical path between the first semi-transmissive reflective surface and the third semi-transmissive reflective surface;
further comprising a second quarter-wave plate disposed on the optical path between the third semi-transmissive reflective surface and the second semi-transmissive reflective surface,
The first quarter-wave plate and the second quarter-wave plate are arranged such that their respective slow axes are inclined by 90°,
The polarized light transmission axis of the first semi-transparent reflective surface and the polarized light transmission axis of the second semi-transparent reflective surface are parallel to each other,
8. The optical element according to claim 7, wherein the slow axis of the first quarter-wave plate is inclined by 45 degrees with respect to the polarization transmission axis of the first semi-transmissive reflective surface.

The light beam deflected by the first deflector passes through the first semi-transparent reflective surface, passes through the first quarter-wave plate, and then is deflected by the third semi-transmissive reflective surface. divided into a first beam of light that passes through the reflective surface and a second beam of light that is reflected by the third semi-transparent reflective surface;
The first light beam passes through the second quarter-wave plate, is reflected by the second semi-transmissive reflective surface, passes through the second quarter-wave plate, and is reflected by the third semi-transmissive reflective surface. , transmitted through the second quarter-wave plate, transmitted through the second semi-transparent reflective surface, and incident on the second deflection section,
The second light beam passes through the first quarter-wave plate, is reflected by the first semi-transparent reflective surface, passes through the first quarter-wave plate, and is reflected by the third semi-transmissive reflective surface. 10. The optical element according to claim 9, wherein the light passes through the second quarter-wave plate, passes through the second semi-transmissive reflective surface, and enters the second deflection section.

The thickness of the optical element is t, the distance between the first semi-transparent reflective surface and the third semi-transparent reflective surface is a, and the distance between the third semi-transparent reflective surface and the second semi-transparent reflective surface is b. , when the maximum incident angle of the luminous flux is α, and n is an integer of 0 or more,
0.20<|a-b|/(t・tan(α))-n<0.80
The optical element according to claim 8, wherein the optical element satisfies the following conditional expression.

The optical element according to claim 1 or 2,
An eyepiece optical system comprising: an optical system that guides a luminous flux from an image display element to the optical element.

The optical element according to claim 1 or 2,
an image display element;
An image display device comprising: an optical system that guides a luminous flux from the image display element to the optical element.