WO2020203642A1 - Élément optique et dispositif d'affichage d'image - Google Patents

Élément optique et dispositif d'affichage d'image Download PDF

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Publication number
WO2020203642A1
WO2020203642A1 PCT/JP2020/013655 JP2020013655W WO2020203642A1 WO 2020203642 A1 WO2020203642 A1 WO 2020203642A1 JP 2020013655 W JP2020013655 W JP 2020013655W WO 2020203642 A1 WO2020203642 A1 WO 2020203642A1
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WO
WIPO (PCT)
Prior art keywords
light
diffraction grating
optical element
light incident
incident
Prior art date
Application number
PCT/JP2020/013655
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English (en)
Japanese (ja)
Inventor
洋一 尾形
Original Assignee
株式会社小糸製作所
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Filing date
Publication date
Application filed by 株式会社小糸製作所 filed Critical 株式会社小糸製作所
Priority to CN202080019319.2A priority Critical patent/CN113544569B/zh
Publication of WO2020203642A1 publication Critical patent/WO2020203642A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R11/00—Arrangements for holding or mounting articles, not otherwise provided for
    • B60R11/02—Arrangements for holding or mounting articles, not otherwise provided for for radio sets, television sets, telephones, or the like; Arrangement of controls thereof
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays

Definitions

  • the present invention relates to an optical element and an image display device, and more particularly to an optical element and an image display device using a diffraction grating.
  • an instrument panel that lights and displays an icon has been used. Further, as the amount of information to be displayed increases, it is also proposed to embed an image display device in the instrument panel or to configure the entire instrument panel with the image display device.
  • HUD Head Up Display
  • FIG. 6 is a schematic view showing the structure of the optical element used in the HUD of the prior art.
  • An optical element including a waveguide portion 1, a diffraction grating portion 2, and reflective films 3a and 3b is housed in the HUD.
  • the waveguide portion 1 is formed with an inclined end surface 1a, a back surface 1b, and a front surface 1c, and a diffraction grating portion 2 is provided inside. Further, reflective films 3a and 3b are formed on the back surface 1b and the front surface 1c.
  • the diffraction grating portion 2 is a blazeed grating made of a material having a refractive index different from that of the waveguide portion 1 and having irregularities formed at predetermined intervals.
  • the incident light L in emitted from the light source unit is reflected by the inclined end face 1a after entering the waveguide portion 1.
  • the incident light Lin reflected by the inclined end surface 1a travels in the waveguide portion 1, is repeatedly reflected by the reflective films 3a and 3b of the back surface 1b and the front surface 1c, and reaches the diffraction grating portion 2.
  • the light that has reached the diffraction grating portion 2 is irradiated as emitted light L out in a direction determined by the diffraction conditions of the diffraction grating portion 2.
  • the diffraction condition of the diffraction grating portion 2 is determined by the wavelength of light, the pitch of the diffraction grating portion 2, the difference in refractive index between the waveguide portion 1 and the diffraction grating portion 2, the angle at which the light reaches the diffraction grating portion 2, and the like. Will be done.
  • the conventional in-vehicle HUD an optical device for projecting an image on a wide range of the windshield is required, and it is difficult to reduce the size and weight of the optical device.
  • the projection destination of the image is limited to one direction. Therefore, the conventional image display device using a diffraction grating cannot cope with various situations of the driver when driving the vehicle, and cannot visually recognize the information, for example, when looking back when the vehicle is moving backward. ..
  • an object of the present invention is to provide an optical element and an image display device that are compact, lightweight, and capable of projecting an image in a plurality of directions.
  • the optical element of the present invention includes a light guide portion having a light incident surface, a plurality of side surfaces perpendicular to the light incident surface, and a back surface facing the light incident surface. It is characterized by comprising a plurality of diffraction grating portions formed on at least two or more surfaces selected from the side surface and the back surface.
  • the light incident on the light guide portion from the light incident surface is irradiated in a predetermined direction by a plurality of diffraction grating portions, so that the image can be projected in a plurality of directions with a small size and light weight. Is possible.
  • a reflective film is formed on the side surface and the back surface on which the diffraction grating portion is not formed.
  • the light incident portion has a first light incident portion and a second light incident portion, and the first diffraction that the first light incident from the first light incident portion reaches first.
  • the grating portion and the second diffraction grating portion where the second light incident from the second light incident portion first arrives are different.
  • the first diffraction grating portion and the second diffraction grating portion are formed on the side surface.
  • a prism is arranged on the light incident surface, and a gap is provided between the prism and the light incident surface.
  • the diffraction grating portion is composed of a dielectric material having a refractive index different from that of the light guide portion.
  • the image display device of the present invention includes any one of the above optical elements and a light source unit that irradiates the light incident surface with light, and the diffraction grating unit and the light guide unit formed on the side surface thereof. A part of the light is reflected at the interface with the light and reaches the other diffraction grating portion.
  • the present invention can provide an optical element and an image display device that are compact and lightweight and can project an image in a plurality of directions.
  • FIG. 1 is a schematic perspective view showing the structure of the optical element 10 in the present embodiment.
  • the optical element 10 includes a light guide unit 11, diffraction grating units 12a, 12b, 12c, and a prism 13.
  • FIG. 1 schematically shows the structure of the optical element 10, and the dimensions and angles in the figure do not show the actual size of the optical element 10.
  • the light guide portion 11 is a substantially plate-shaped portion made of a material that transmits light, and includes a light incident surface 11i, side surfaces 11a and 11c, and a back surface 11b as shown in FIG.
  • the material constituting the light guide portion 11 is not limited, but for example, it is preferable to use glass containing SiO 2 as a main component and having a refractive index of about 1.5.
  • the light incident surface 11i is a flat surface on which light from a light source arranged outside the optical element 10 is incident, is formed substantially perpendicular to the side surfaces 11a and 11c, and faces the back surface 11b.
  • the side surfaces 11a and 11c are flat surfaces that face each other and have diffraction grating portions 12a and 12c formed on the front surface, and are formed substantially perpendicular to the light incident surface 11i and the back surface 11b.
  • the back surface 11b is a flat surface on which the diffraction grating portion 12b is formed, and faces the light incident surface 11i.
  • the diffraction grating portions 12a, 12b, and 12c are substantially plate-shaped portions formed on the surfaces of the side surface 11a, the back surface 11b, and the side surface 11c, respectively, and are made of a material having a refractive index different from that of the light guide portion 11.
  • a plurality of convex portions and concave portions are periodically formed on the surface of the diffraction grating portions 12a, 12b, and 12c to form the diffraction grating.
  • the convex portions and concave portions of the diffraction grating portions 12a, 12b, and 12c are formed by extending them in a stripe shape in a direction parallel to the light incident surface 11i, respectively.
  • the diffraction grating portion 12a, 12b, although projections and recesses 12c is an example parallel to the light incident surface 11i, light incident if it is designed to satisfy the diffraction condition of the incident light L 1 to be described later It does not have to be parallel to the surface 11i. For example, it may be stretched in a stripe shape in a direction perpendicular to the incident light L1 incident at an angle. Further, the diffraction grating portions 12a, 12b, and 12c may be made of the same material, or may be made of different materials.
  • the difference in the refractive index at the interface with the light guide portion 11 is different, and the reflectance at the interface and the incident angle into the diffraction grating portions 12a, 12b, 12c are different. Can be changed, and the degree of freedom in optical design is improved.
  • the material constituting the diffraction grating portions 12a, 12b, and 12c is not limited, but it is preferable to use a material having a large difference in refractive index from the light guide portion 11, for example, a refractive index of about 2.5 containing TiO 2 as a main component. It is preferable to use a dielectric.
  • the size of the diffraction grating portions 12a, 12b, and 12c is not particularly limited, but it is preferable that the diffraction grating portions 12a, 12b, and 12c have a thickness capable of guiding light in the in-plane direction.
  • the diffraction grating portions 12a, 12b, and 12c can be formed by a known method, and for example, nanoimprint technology, EBL (Electron Beam Lithography) technology, and the like can be used.
  • the prism 13 is an optical element having a triangular cross section arranged in the vicinity of the light incident surface 11i. Further, a gap is provided between the light incident surface 11i and the prism 13, and an air layer is interposed between the light incident surface 11i and the prism 13.
  • the material constituting the prism 13 is not limited, but in order for the light from the light source to be efficiently incident on the light guide portion 11, it is preferable that the refractive indexes of the prism 13 and the light guide portion 11 are about the same, and the light guide is provided. It is preferable to use the same material as part 11.
  • the width of the gap provided between the light incident surface 11i and the prism 13 is preferably about the wavelength of light.
  • an air layer is interposed in the gap, but in order to improve the optical coupling efficiency between the prism 13 and the light guide portion 11, a transparent contact liquid having a refractive index close to that of the light guide portion 11 is used.
  • the gap may be filled.
  • FIG. 1 shows an example in which the prisms 13 are arranged with a gap, they may be brought into contact with each other without providing a gap. Further, when the decrease in the light coupling efficiency due to the influence of optical scattering is within the allowable range, the light may be directly incident on the light guide portion 11 from the light incident surface 11i without using the prism 13.
  • FIG. 2 is a schematic cross-sectional view showing the configuration and optical path of an image display device using the optical element 10.
  • the image display device of the present embodiment includes an optical element 10, a collimating lens 14, and a light source 15.
  • a laser beam is emitted from the light source 15 toward the optical element 10, and the collimating light is incident on the prism 13 via the collimating lens 14.
  • the collimated light is incident on one surface of the prism 13, passes through the inside of the prism 13, and escapes from the surface on the gap side to the gap.
  • the region where the collimated light is incident corresponds to the light incident portion in the present invention.
  • the collimated light that has passed through the prism 13 is obliquely incident on the light incident surface 11i of the light guide unit 11 through the gap.
  • the width of the gap about the same as the wavelength, the light reflection at the interface between the prism 13 and the gap and the interface between the gap and the light guide portion 11 is reduced, and the collimated light is efficiently transmitted to the light guide portion 11. Can be taken in.
  • Collimated light incident from the light incident surface 11i is incident at an incident angle ⁇ on the diffraction grating portion 12a of the side surface 11a surface as the incident light L 1 propagating through the light guiding portion 11.
  • ⁇ incident angle
  • part of the incident light L 1 is incident on the diffraction grating portion 12a, a part is reflected in the light guiding portion 11 as reflected light.
  • Light traveling within the diffraction grating portion 12a of the incident light L 1 is advanced angle varies depending on the refractive index of the light guide portion 11 the diffraction grating portion 12a, satisfying the diffraction condition emission angle by the convex and concave portions ⁇ It is emitted as emitted light L 2 in the d1 direction. Further, the light captured in the diffraction grating portion 12a can satisfy the condition of total leakage and total reflection at the interface with air by appropriately selecting the refractive index and the incident angle ⁇ , and in the diffraction grating portion 12a. It is repeatedly reflected and propagates in the diffraction grating portion 12a.
  • the light reflected at the interface of the light guide portion 11 and the diffraction grating portion 12a of the incident light L 1 reaches the rear surface 11b by traveling in the light guide portion 11, the incident angle to the diffraction grating 12b of the back surface 11b surface It is incident on ⁇ , a part is incident on the diffraction grating portion 12b, and a part is re-reflected in the light guide portion 11.
  • the re-reflected light travels in the light guide portion 11 and reaches the side surface 11c, is incident on the diffraction grating portion 12c on the surface of the side surface 11c at an incident angle ⁇ , and a part of the light is incident on the diffraction grating portion 12c.
  • Diffraction grating portion 12b light incident on the 12c, the diffraction satisfies emission angle by protrusion and recess as with the diffraction grating portion 12a theta d2, is emitted as output light L 3, L 4 in the theta d3 direction.
  • the emission angles of the emission lights L 2 , L 3 , and L 4 emitted from the diffraction grating portions 12a, 12b, and 12c to the outside are determined by the pitches of the convex portions and the concave portions, respectively. Therefore, by appropriately setting the diffraction grating portions 12a, 12b, and 12c, the emission directions of the emission lights L 2 , L 3 , and L 4 can be individually set.
  • the light incident on the light guide portion 11 from the light incident surface 11i is partially reflected at the interface between the diffraction grating portions 12a, 12b, 12c and the light guide portion 11. Then, it reaches the side surface 11a, the back surface 11b, and the side surface 11c, and is irradiated to the outside as emitted light L 2 , L 3 , L 4 from the diffraction grating portions 12a, 12b, 12c in three directions.
  • the optical element 10 it is possible to project an image in a plurality of directions with a small size and a light weight.
  • FIG. 3 is a diagram schematically showing an image projection when the optical element 10 is provided in the vehicle 100.
  • the optical element 10 is arranged on the ceiling inside the vehicle 100, and light is incident on the optical element 10 from a separately provided light source.
  • the optical element 10 irradiates the emitted light L 2 , L 3 , and L 4 in three directions (front, lower center, and rear) of the vehicle 100.
  • the forward emission light L 2 is projected onto the windshield 101
  • the rearward emission light L 4 is projected onto the rear glass 102.
  • Outgoing light L 3 to the central lower is projected onto a screen placed in the vehicle.
  • a non-transmissive white screen or transmissive glass may be separately provided, or the interior of the vehicle may be used as the screen.
  • the optical element 10 and the image display device of the present embodiment are smaller and lighter than those using a mirror or an optical lens, and can simultaneously project images in a plurality of directions.
  • FIG. 4 is a schematic cross-sectional view showing the structure and optical path of the optical element 10 in the present embodiment.
  • the present embodiment is different from the first embodiment in that a reflective film 16 is formed on the front surface of the back surface 11b.
  • the reflective film 16 is a highly reflective film formed so as to cover the back surface 11b.
  • the material constituting the reflective film 16 is not limited, but it is preferably formed by depositing a high-reflectivity metal such as silver. Since the emitted light is not emitted to the outside from the surface on which the reflective film 16 is formed, the projection direction of the image can be limited. Further, the light reaching the back surface 11b is reflected at the interface side 11a and the diffraction grating portion 12a can be reflected with high efficiency to the side surface 11c, the outgoing light L 4 emitted to the outside from the diffraction grating portion 12c The strength can be improved.
  • FIG. 4 shows an example in which the reflective film 16 is formed only on the back surface 11b, but all the surfaces other than the light incident surface 11i of the light guide portion 11 on which the diffraction grating portions 12a to 12c are not formed are all. It is preferable to form the reflective film 16.
  • FIG. 5 is a schematic top view showing the structure of the optical element 10 in the present embodiment.
  • the present embodiment is different from the first embodiment in that two systems of light are incident on the light guide portion 11 to form a diffraction grating portion on all of the side surfaces.
  • the diffraction grating portions 12d and 12e are also formed on the surfaces of the side surfaces 11d and 11e orthogonal to the side surfaces 11a and 11c.
  • two prisms 13a and 13b are arranged in the vicinity of the light incident surface 11i.
  • the prisms 13a and 13b are optical elements having a triangular cross section, and are arranged so that their ridges are orthogonal to each other.
  • two light sources 15 are prepared, and the prisms 13a and 13b of the optical element 10 are irradiated with light.
  • the regions where the collimated light is incident through the prisms 13a and 13b correspond to the first light incident portion and the second light incident portion in the present invention, respectively.
  • the light incident on the light guide portion 11 via the prism 13a is emitted from the diffraction grating portions 12a, 12b, 12c as emitted light L 2 , L 3 , L 4 in three directions as described in FIG.
  • the light incident on the light guide portion 11 via the prism 13b reaches the side surface 11d, a part of the light enters the diffraction grating portion 12d, and a part of the light is reflected in the light guide portion 11 as reflected light. Will be done.
  • the light reflected by the side surface 11d is reflected again by the back surface 11b and reaches the side surface 11e, and a part of the light is incident on the diffraction grating portion 12e.
  • the light incident on the diffraction grating portions 12d and 12e is emitted as emitted light L 5 and L 6 in the direction satisfying the diffraction condition by the convex portion and the concave portion as in the first embodiment.
  • the light incident on the light guide portion 11 via the prism 13a first reaches the diffraction grating portion 12a, and the light incident on the light guide portion 11 via the prism 13b first reaches. It is different from the diffraction grating portion 12d. Further, the side surface 11a on which the diffraction grating portion 12a is formed and the side surface 11d on which the diffraction grating portion 12d is formed are orthogonal to each other.
  • the light incident from the prism 13a and the light incident from the prism 13b are irradiated to the outside from the diffraction grating units 12a, 12b, 12c and the diffraction grating units 12d, 12e, respectively, via different paths in the light guide unit 11. ..
  • an image can be projected in five directions of the side surfaces 11a, 11c, 11d, 11e perpendicular to the light incident surface 11i and the back surface 11b.
  • an image can also be projected on the left and right side glasses.
  • the optical element 10 and the image display device of the present embodiment can simultaneously project images in a plurality of directions in a maximum of five directions while being compact and lightweight.
  • the light guide portion 11 is a rectangular parallelepiped, but the shape of the light guide portion 11 is not limited.
  • the back surface 11b may not be parallel to the light incident surface 11i but may be inclined by a predetermined angle.
  • the side surfaces 11a, 11c, 11d, 11e do not have to be perpendicular to the light incident surface 11i.
  • L1 Incident light L2 to L6 ... Emission light 10 ...
  • Optical element 100 Vehicle 101 ... Windshield 102 ... Rear glass 11 ...
  • Light guide unit 11i Light incident surface 11a, 11c, 11d, 11e ... Side surface 11b ... Back surface 12a to 12e ... Diffraction grating portions 13, 13a, 13b ... Prism 14 ... Collimating lens 15 ... Light source 16 ... Reflective film

Abstract

L'invention concerne un élément optique de petite taille et léger permettant de projeter une image dans une pluralité de directions, et un dispositif d'affichage d'image. La présente invention concerne un élément optique comprenant une surface d'incidence de lumière, une pluralité de surfaces latérales perpendiculaires à la surface d'incidence de lumière, une partie de guidage de lumière ayant une surface arrière faisant face à la surface d'incidence de lumière, et une pluralité de parties de réseau de diffraction formées sur au moins deux surfaces sélectionnées parmi les surfaces latérales et la surface arrière.
PCT/JP2020/013655 2019-04-05 2020-03-26 Élément optique et dispositif d'affichage d'image WO2020203642A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202080019319.2A CN113544569B (zh) 2019-04-05 2020-03-26 光学元件和图像显示装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019072494A JP7373292B2 (ja) 2019-04-05 2019-04-05 光学素子および画像表示装置
JP2019-072494 2019-04-05

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WO2020203642A1 true WO2020203642A1 (fr) 2020-10-08

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CN (1) CN113544569B (fr)
WO (1) WO2020203642A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0720321A (ja) * 1993-06-30 1995-01-24 Nissan Motor Co Ltd 表示装置
JPH10268307A (ja) * 1997-03-28 1998-10-09 Sharp Corp 前方照明装置およびこれを備えた反射型液晶表示装置
JP2006228596A (ja) * 2005-02-18 2006-08-31 Toppan Printing Co Ltd 照明装置および液晶表示装置
US20120113679A1 (en) * 2009-07-10 2012-05-10 Koninklijke Philips Electronics N.V. Free form lighting module
JP2015526864A (ja) * 2012-08-13 2015-09-10 スリーエム イノベイティブ プロパティズ カンパニー 回折照明器具
US20160147000A1 (en) * 2014-11-24 2016-05-26 Electronics And Telecommunications Research Institute Apparatus for controlling light beam path

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2986773B2 (ja) * 1998-04-01 1999-12-06 嶋田プレシジョン株式会社 点光源用の導光板
JP2010093078A (ja) 2008-10-08 2010-04-22 Hamamatsu Photonics Kk 光学素子、レーザ光発振装置及びレーザ光増幅装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0720321A (ja) * 1993-06-30 1995-01-24 Nissan Motor Co Ltd 表示装置
JPH10268307A (ja) * 1997-03-28 1998-10-09 Sharp Corp 前方照明装置およびこれを備えた反射型液晶表示装置
JP2006228596A (ja) * 2005-02-18 2006-08-31 Toppan Printing Co Ltd 照明装置および液晶表示装置
US20120113679A1 (en) * 2009-07-10 2012-05-10 Koninklijke Philips Electronics N.V. Free form lighting module
JP2015526864A (ja) * 2012-08-13 2015-09-10 スリーエム イノベイティブ プロパティズ カンパニー 回折照明器具
US20160147000A1 (en) * 2014-11-24 2016-05-26 Electronics And Telecommunications Research Institute Apparatus for controlling light beam path

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Publication number Publication date
CN113544569B (zh) 2024-02-13
JP7373292B2 (ja) 2023-11-02
CN113544569A (zh) 2021-10-22
JP2020170125A (ja) 2020-10-15

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