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WO2024190458A1 - Image projection device - Google Patents

Image projection device Download PDF

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Publication number
WO2024190458A1
WO2024190458A1 PCT/JP2024/007744 JP2024007744W WO2024190458A1 WO 2024190458 A1 WO2024190458 A1 WO 2024190458A1 JP 2024007744 W JP2024007744 W JP 2024007744W WO 2024190458 A1 WO2024190458 A1 WO 2024190458A1
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WO
WIPO (PCT)
Prior art keywords
image
light
image light
reflecting
unit
Prior art date
Application number
PCT/JP2024/007744
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French (fr)
Japanese (ja)
Inventor
一臣 村上
由莉 濱田
Original Assignee
株式会社小糸製作所
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Publication of WO2024190458A1 publication Critical patent/WO2024190458A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
    • B60K35/20—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor
    • B60K35/21—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor using visual output, e.g. blinking lights or matrix displays
    • B60K35/23—Head-up displays [HUD]
    • 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 image projection device, and in particular to an image projection device for projecting multiple images.
  • dashboards that light up icons have been used as devices to display various types of information inside vehicles. As the amount of information to be displayed increases, it has also been proposed to embed an image display device in the dashboard or to configure the entire dashboard from an image display device.
  • HUDs head-up displays
  • an image projection unit projects light containing an image, which is then reflected by a free-form mirror or the like, and reaches the position of the occupant's viewpoint so that the image is formed in space via a display unit such as a windshield. This allows the occupant to perceive an image as being displayed at the imaging position in the depth direction due to the light incident on the viewpoint. It has also been proposed to project virtual images at multiple depths using a driving assistance HUD device.
  • the present invention has been developed in consideration of the above-mentioned problems with the conventional technology, and aims to provide an image projection device that can project multiple images while suppressing an increase in the number of parts in the projection optical components and miniaturizing the optical components.
  • the image projection device of the present invention is an image projection device that projects a projection image onto a display unit for displaying a virtual image, and includes an image irradiation unit that irradiates first image light and second image light, and a projection optical unit that projects the first image light and the second image light onto the display unit as the projection image, the projection optical unit having a polarizing reflection unit that reflects polarized light in a first direction and transmits polarized light in a second direction perpendicular to the first direction, and a reflection unit that reflects the first image light towards the polarizing reflection unit, the polarizing reflection unit reflects the first image light from a first surface, and the second image light transmits from a second surface opposite the first surface.
  • the projection optical unit includes a polarized reflecting unit and a reflecting unit.
  • the first image light is reflected by the reflecting unit and the polarized reflecting unit, and the second image light is transmitted through the second surface of the polarized reflecting unit, so that the optical paths of the first image light and the second image light can be overlapped.
  • the image irradiation unit irradiates the first image light and the second image light with a polarization direction in the first direction or the second direction
  • the projection optical unit includes a half-wave plate that rotates the polarization direction of the first image light or the second image light by 90 degrees.
  • the image irradiation unit is configured with one display device and has a first region that irradiates the first image light and a second region that irradiates the second image light, with one of the reflecting unit or the polarized reflecting unit being disposed opposite the first region, and the other of the reflecting unit or the polarized reflecting unit being disposed opposite the second region.
  • the projection optical unit has a reflecting prism, and the reflecting unit and the polarizing reflecting unit are provided on opposing surfaces of the reflecting prism.
  • the polarizing reflector is provided with a transmissive prism on the surface opposite the reflecting prism.
  • the first image light and the second image light projected from the projection optical unit have at least a portion of their optical paths overlapping.
  • the imaging position of the virtual image is farther from the viewpoint position for the first image light than for the second image light.
  • the present invention provides an image projection device capable of projecting multiple images while minimizing the number of parts in the projection optical components and miniaturizing the optical components.
  • FIG. 1 is a schematic diagram showing projection of a virtual image using an image projection device 100 according to a first embodiment.
  • FIG. 2 is a schematic cross-sectional view illustrating an overview of an image projection unit 10 in the image projection device 100 according to the first embodiment.
  • 2 is a schematic diagram showing a display area of an image projected from an image display unit 12 in the image projection device 100 according to the first embodiment.
  • FIG. 4A and 4B are schematic perspective views showing the positional relationship between virtual images P1 and P2 projected by the image projection device 100 according to the first embodiment, where FIG. 4A shows a perspective view from the viewpoint position and FIG. 4B shows a front view.
  • 13 is a schematic diagram showing an example of the configuration of a projection optical unit according to a second embodiment.
  • Fig. 1 is a schematic diagram showing the projection of a virtual image using an image projection device 100 according to this embodiment.
  • the dashed line in Fig. 1 indicates the optical path of a first image light, which will be described later, and the dashed line indicates the optical path of a second image light.
  • the image projection device 100 includes an image projection unit 10, a first mirror 20, a second mirror 30, and an external light cut filter 40.
  • the first image light and the second image light projected from the image projection device 100 are reflected by the windshield (display unit) WS and irradiated to the driver's viewpoint.
  • the driver visually recognizes virtual images P1 and P2 formed on the extension of the optical path along which the first image light and the second image light are incident.
  • each part is controlled by a control unit connected to each part so that information can be communicated therewith.
  • the configuration of the control unit is not limited, but one example is one that includes a CPU (Central Processing Unit) for information processing, a memory device, a recording medium, an information communication device, etc.
  • the control unit controls the operation of each part according to a predetermined program, and sends information including an image (image information) to the image projection unit 10.
  • the image irradiation unit 10 is a part that irradiates the first mirror 20 with light containing an image as image light based on image information from the control unit.
  • image information from the control unit In this embodiment, an example is shown in which two image lights displayed in two image display areas are irradiated to the first mirror 20 as the first image light and the second image light.
  • the first mirror 20 is an optical member that reflects the first image light and the second image light arriving from the image irradiation unit 10 in the direction of the second mirror 30.
  • the first mirror 20 is a concave reflecting mirror, but a flat or convex reflecting mirror may also be used.
  • the first mirror 20 is configured with a curved surface, it is not limited to a surface with a constant curvature, and a paraboloid of revolution, an ellipsoid, a free-form surface mirror, etc. may be used.
  • the second mirror 30 is an optical member that reflects the first image light and the second image light arriving from the first mirror 20 in the direction of the windshield WS.
  • the second mirror 30 is a free-form mirror with an optically designed concave shape necessary for projecting the first image light and the second image light as virtual images P1 and P2.
  • the reflective surfaces of the first mirror 20 and the second mirror 30 are designed to expand the light diameter in the driver's viewing direction in order to project the first image light and the second image light as virtual images P1 and P2 through the windshield WS.
  • the expansion of the light diameter in the viewing direction includes not only the case where the light diameter expands consistently after reflection, but also the case where the light diameter shrinks and expands after forming an image at an intermediate point.
  • the optical paths of the first image light and the second image light are depicted as a single straight line.
  • the actual first image light and second image light are displayed in a predetermined area in the image projection unit 10, and have a predetermined area in the direction perpendicular to the traveling direction.
  • the first image light and the second image light are reflected by the first mirror 20, and the light diameter is reduced as they travel, and they may be intermediately imaged at an intermediate imaging position F (not shown) between the first mirror 20 and the second mirror 30.
  • the external light cut filter 40 is disposed between the second mirror 30 and the windshield WS, and cuts out a portion of the external light that reaches the inside of the image projection device 100 from the outside.
  • a wavelength filter that transmits visible light and cuts infrared and ultraviolet light.
  • the windshield WS is a part that is provided in front of the driver's seat of the vehicle and transmits visible light.
  • the windshield WS reflects the first image light and the second image light that are incident from the image projection device 100 toward the viewpoint direction, and transmits light from outside the vehicle toward the viewpoint direction, and therefore corresponds to the display unit in the present invention.
  • a combiner may be provided as a display unit separate from the windshield WS, and the light from the image projection device 100 may be reflected toward the viewpoint direction.
  • the windshield WS is not limited to being located at the front of the vehicle, and may be located to the side or rear as long as it projects an image toward the viewpoint of the passenger.
  • Virtual images P1 and P2 are images that are displayed as if they were formed in space when the first image light and the second image light reflected by the windshield WS reach the passenger's viewpoint (eyebox).
  • the positions at which virtual images P1 and P2 are formed are determined by the composite focal length of the projection optical unit included in the image projection device 100 and the windshield WS.
  • the distant image displayed in the distant display area of the image irradiation unit 10 is irradiated as the first image light
  • the near image displayed in the near display area is irradiated as the second image light.
  • Distant images displayed in the distant display area include auxiliary information related to driving, such as images calling attention and emergency information.
  • Near images displayed in the near display area include speed and volume indicators, driving direction guides, etc.
  • FIG. 2 is a schematic cross-sectional view for explaining an overview of the image projection unit 10 in the image projection device 100 according to this embodiment.
  • the image projection unit 10 includes a backlight 11, an image display unit 12, a half-wave plate 13, a reflecting prism 14, and a polarizing reflecting unit 15.
  • the backlight 11 is a part that irradiates light onto the image display unit 12, and may be, for example, a light-emitting diode (LED) that irradiates light.
  • the light irradiated by the backlight 11 is preferably white, but it may also be a light that emits a single color such as blue, green, or red.
  • the backlight 11 is not limited to an LED, and may be a semiconductor laser, an organic EL (Electro Luminescence) element, or the like.
  • the image display unit 12 is a part that displays a projected image in response to an image signal from the control unit. When light from the backlight 11 is irradiated onto the projected image displayed on the image display unit 12, a first image light and a second image light are irradiated from the image display unit 12.
  • the specific configuration of the image display unit 12 is not limited, and for example, a liquid crystal display device or the like can be used.
  • the image display unit 12 is configured to include a far display area (first area) and a near display area (second area) that display a far image and a near image, respectively.
  • the half-wave plate 13 is an optical element arranged in the far display area or near display area of the image display unit 12, and is made of a birefringent material with different refractive indices in the slow axis and the fast axis.
  • the half-wave plate 13 is designed so that a phase difference of half the wavelength of the light occurs between the slow axis and the fast axis before the incident light is emitted.
  • the slow axis and the fast axis of the half-wave plate 13 are arranged in directions that differ by 45 degrees with respect to the polarization direction of the light irradiated from the image display unit 12. In the example shown in FIG. 2, the half-wave plate 13 is arranged overlapping the near display area, but it may also be arranged overlapping the far display area.
  • the polarizing reflector 15 is an optical member that is bonded to the transmissive reflector 14b of the reflecting prism 14 and reflects polarized light in a first direction and transmits polarized light in a second direction perpendicular to the first direction.
  • the polarized light direction transmitted by the polarizing reflector 15 is not limited, and must be adapted to the polarization direction required for the first image light or the second image light that is ultimately irradiated.
  • the polarized light may be reflected in a direction perpendicular to the paper surface in FIG. 1 (e.g., s-polarized light).
  • the polarizing reflector 15 is disposed at a predetermined angle with respect to the traveling direction of the light irradiated from the backlight 11. In the example shown in FIG. 2, the second image light irradiated from the near display area is incident on the rear surface of the polarizing reflector 15, but the first image light irradiated from the far display area may also be incident thereon.
  • the light entrance surface 14c of the reflecting prism 14 is arranged so as to overlap the far display area 12c of the image display unit 12, and the half-wave plate 13, the transmission reflection unit 14b, and the polarizing reflection unit 15 are arranged in a position facing the near display area 12b. Therefore, the reflection surface 14a is arranged facing the far display area 12c, and the polarizing reflection unit 15 is arranged facing the near display area 12b.
  • the polarization direction of the light irradiated from the image display unit 12 is approximately the same as the direction reflected by the polarizing reflection unit 15.
  • placing the reflecting prism 14 on the image display unit 12 means that the area in which the reflecting prism 14 is placed overlaps with the image display area of the image display unit 12 in a planar view.
  • the overlapping arrangement also includes cases where the reflecting prism 14 and the image display unit 12 are in contact and cases where they are not in contact.
  • the overlapping arrangement also includes cases where a light-transmitting optical member or a holding member for maintaining the distance between the reflecting prism 14 and the image display unit 12 is interposed between the reflecting prism 14 and the image display unit 12.
  • the optical path until it is irradiated from the light exit surface 14d is longer than that of the second image light.
  • the imaging distance of the virtual image P1 formed by the first image light from the windshield WS is greater than the imaging distance of the virtual image P2 formed by the second image light.
  • the first and second image lights irradiated from the light exit surface 14d of the reflecting prism 14 are reflected by the first mirror 20, the second mirror 30, and the windshield WS, respectively, and reach the driver's viewpoint. Because the first and second image lights reach the viewpoint with their light diameters expanded by the first and second mirrors 20 and 30, the driver visually recognizes virtual images P1 and P2 formed by the first and second image lights as if they were formed at a predetermined distance.
  • the imaging positions of the virtual images P1 and P2 are such that the first image is farther from the viewpoint than the second image.
  • the optical paths of the first image light and the second image light irradiated from the light exit surface 14d of the reflecting prism 14 at least partially overlap. This reduces the space of the optical paths required to project the first image light and the second image light, making it possible to miniaturize the image projection device 100.
  • FIG. 4 is a schematic perspective view showing the positional relationship of virtual images P1 and P2 projected by the image projection device 100 according to this embodiment, where FIG. 4(a) shows a perspective view from the viewpoint position and FIG. 4(b) shows a front view.
  • the image positions of virtual images P1 and P2 are at different depths and have approximately the same depression angle.
  • the depression angle of virtual image P1 formed by the first image light as viewed from the viewpoint position and the depression angle of virtual image P2 formed by the second image light are approximately the same, making it possible to view virtual images P1 and P2 without moving the line of sight.
  • the optical paths of the first image light and the second image light coincide with each other, and the centers of the virtual images P1 and P2 are on the same line of sight, but the optical paths of the first image light and the second image light may be slightly different so that the centers of the virtual images P1 and P2 are on different lines of sight.
  • the virtual images P1 and P2 overlap when viewed from the front, so visibility is reduced when the virtual images P1 and P2 are formed simultaneously. Therefore, when the image positions of the virtual images P1 and P2 overlap when viewed from the front, it is preferable to exclusively switch the display in the far display area 12c and the near display area 12b of the image display unit 12, and switch the image formation of the virtual images P1 and P2.
  • the projection optical unit includes a polarized reflecting unit 15 and a reflecting surface 14a.
  • the first image light is reflected by the reflecting surface 14a and the polarized reflecting unit 15, and the second image light is transmitted through the rear surface of the polarized reflecting unit 15, thereby overlapping the optical paths of the first image light and the second image light.
  • Fig. 5 is a schematic diagram showing an example of the configuration of a projection optical unit according to this embodiment.
  • the projection optical unit of this embodiment includes a reflecting prism 14, a polarizing reflecting unit 15, and a transmitting prism 16.
  • the transmitting prism 16 is an optical member made of a light-transmitting material, and is disposed on the surface of the polarizing reflecting section 15 opposite the reflecting prism 14.
  • FIG. 5 shows an example of the shape of the transmitting prism 16 having a cross section of a right-angled triangle, the shape is not limited.
  • the transmitting prism 16 is provided with a light exit surface 16a and a light entrance surface 16b, and the polarizing reflecting section 15 is sandwiched between the light exit surface 16a of the transmitting prism 16 and the transmitting reflecting section 14b of the reflecting prism 14.
  • the light entrance surface 16b of the transmitting prism 16 and the light entrance surface 14c of the reflecting prism 14 are preferably disposed in parallel, and more preferably disposed flush.
  • the first image light irradiated from the far display area 12c enters the light entrance surface 14c of the reflecting prism 14, is reflected by the reflecting surface 14a, is reflected again by the polarizing reflector 15, and is irradiated from the light exit surface 14d to the first mirror 20.
  • the second image light irradiated from the near display area 12b passes through the half-wave plate 13, has its polarization direction rotated by 90 degrees, enters the light entrance surface 16b of the transmitting prism 16, enters the back surface of the polarizing reflector 15 from the light exit surface 16a, passes through the polarizing reflector 15 and the transmitting reflector 14b, and is irradiated from the light exit surface 14d to the first mirror 20.
  • the transmission prism 16 By arranging the transmission prism 16 on the back side of the polarized reflection section 15, the difference in refractive index between the second image light and the air when it enters the reflection prism 14 is eliminated, and the refraction of the second image light at the transmission reflection section 14b can be suppressed.
  • the traveling directions of the first image light and the second image light irradiated from the light exit surface 14d can be made the same, making it easier to carry out optical design for matching the light paths.
  • a third embodiment of the present invention will be described. Descriptions of contents overlapping with the first embodiment will be omitted.
  • the first embodiment an example was shown in which a near display region 12b and a far display region 12c are provided in one image display unit 12, and a half-wave plate 13 is arranged in one of them, but two or more liquid crystal display devices may be used as the image display unit 12.
  • the two liquid crystal display devices may be arranged so that the polarization directions of the first image light and the second image light irradiated from the two liquid crystal display devices differ by 90 degrees, and the half-wave plate 13 may be omitted.
  • the first image light irradiated from one liquid crystal display device has a polarization direction that is reflected by the polarizing reflector 15, enters the light entrance surface 14c of the reflecting prism 14, is reflected by the reflecting surface 14a, is reflected again by the polarizing reflector 15, and is irradiated from the light exit surface 14d to the first mirror 20.
  • the second image light irradiated from the other liquid crystal display device has a polarization direction that transmits through the polarizing reflector 15, enters the back surface of the polarizing reflector 15, transmits through the polarizing reflector 15 and the transmission reflector 14b, and is irradiated from the light exit surface 14d to the first mirror 20.
  • Reference Signs List 100 ...Image projection device 10
  • Image irradiation section 11 ...Backlight 12
  • Image display section 12a ...Total display area 12b
  • Near display area 12c ...Far display area 13
  • Reflecting prism 14a ...Reflecting surface 14b
  • Transmitting and reflecting section 14c 16b...Light entrance surface 14d, 16a...Light exit surface 15
  • Polarizing reflecting section 16 ...Transmitting prism 20
  • First mirror 30 ...Second mirror 40...External light cut filter

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  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
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Abstract

Provided is an image projection device that is capable of projecting a plurality of images while minimizing an increase in the number of components for a projecting optical member and achieving downsizing of optical members. An image projection device projects a projection image onto a display part on which a virtual image is displayed, and comprises: an image emitting unit (10) that emits first image light and second image light; and a projecting optical unit (14) for projecting, as projection images, the first image light and the second image light onto the display part. The projecting optical unit (14) has: a polarized light reflection part (15) for reflecting polarized light in a first direction and for transmitting therethrough polarized light in a second direction orthogonal to the first direction; and a reflection part (14a) for reflecting the first image light toward the polarized light reflection part (15). The polarized light reflection part (15) reflects the first image light at a first surface thereof, and transmits the second image light through a second surface thereof, opposite to the first surface.

Description

画像投影装置Image Projection Device
　本発明は、画像投影装置に関し、特に複数の画像を投影するための画像投影装置に関する。 The present invention relates to an image projection device, and in particular to an image projection device for projecting multiple images.
　従来から、車両内に各種情報を表示する装置として、アイコンを点灯表示する計器盤が用いられている。また、表示する情報量の増加とともに、計器盤に画像表示装置を埋め込むことや、計器盤全体を画像表示装置で構成することも提案されている。 Traditionally, dashboards that light up icons have been used as devices to display various types of information inside vehicles. As the amount of information to be displayed increases, it has also been proposed to embed an image display device in the dashboard or to configure the entire dashboard from an image display device.
　しかし、計器盤は車両のフロントガラス（ウィンドシールド）より下方に位置しているため、計器盤に表示された情報を運転者等の搭乗者が視認するには、運転中に視線を下方に移動させる必要があり好ましくない。そこで、フロントガラスに画像を投影して、搭乗者が車両の前方を視認したときに情報を読み取れるようにするヘッドアップディスプレイ（以下ＨＵＤ：Ｈｅａｄ　Ｕｐ　Ｄｉｓｐｌａｙ）のような画像投影装置が提案されている。（例えば、特許文献１，２を参照）。 However, because the instrument panel is located below the vehicle's windshield, in order for the driver or other passengers to see the information displayed on the instrument panel, they must move their gaze downward while driving, which is undesirable. Therefore, image projection devices such as head-up displays (hereinafter referred to as HUDs) have been proposed that project images onto the windshield so that passengers can read information when they look ahead of the vehicle (see, for example, Patent Documents 1 and 2).
　従来の画像投影装置は、画像照射部が画像を含んだ照射光を照射し、自由曲面ミラー等で照射光を反射させて、ウィンドシールド等の表示部を介して空間中に画像が結像するように搭乗者の視点の位置に到達させる。これにより、搭乗者は視点に入射した照射光によって、奥行き方向における結像位置に画像が表示されているように認識することができる。また、運転支援ＨＵＤ装置を用いて複数の奥行に虚像を投影することも提案されている。 In conventional image projection devices, an image projection unit projects light containing an image, which is then reflected by a free-form mirror or the like, and reaches the position of the occupant's viewpoint so that the image is formed in space via a display unit such as a windshield. This allows the occupant to perceive an image as being displayed at the imaging position in the depth direction due to the light incident on the viewpoint. It has also been proposed to project virtual images at multiple depths using a driving assistance HUD device.
特開２０１９－１１９２４８号公報JP 2019-119248 A 特開２０１９－１１９２６２号公報JP 2019-119262 A
　しかし、複数の画像を異なる奥行に虚像として投影して結像し、結像される距離を制御するためには投影光学系の構造が複雑になり、部品点数が多くなるため小型化が困難になるという問題があった。また、複数の虚像を異なる奥行と高さに結像する場合には、虚像を視認するために搭乗者が視線を移動させる必要があり、運転支援情報を視認する快適さが損なわれる可能性も生じる。 However, in order to project multiple images as virtual images at different depths and control the imaging distance, the structure of the projection optical system becomes complex and the number of parts increases, making miniaturization difficult. In addition, when multiple virtual images are formed at different depths and heights, the passenger must move their line of sight to view the virtual images, which may reduce the comfort of viewing the driving assistance information.
　そこで本発明は、上記従来の問題点に鑑みなされたものであり、投影光学部材の部品点数の増加を抑制し、光学部材の小型化を図りながら、複数の画像を投影することが可能な画像投影装置を提供することを目的とする。 The present invention has been developed in consideration of the above-mentioned problems with the conventional technology, and aims to provide an image projection device that can project multiple images while suppressing an increase in the number of parts in the projection optical components and miniaturizing the optical components.
　上記課題を解決するために、本発明の画像投影装置は、虚像を表示するための表示部に対して投影画像を投影する画像投影装置であって、第１画像光および第２画像光を照射する画像照射部と、前記表示部に対して前記第１画像光および前記第２画像光を前記投影画像として投影する投影光学部を備え、前記投影光学部は、第１方向の偏光を反射し前記第１方向と直交する第２方向の偏光を透過する偏光反射部と、前記第１画像光を前記偏光反射部に向けて反射する反射部と、を有し、前記偏光反射部は、第１面で前記第１画像光を反射し、前記第１面と反対側の第２面から前記第２画像光が透過することを特徴とする。 In order to solve the above problem, the image projection device of the present invention is an image projection device that projects a projection image onto a display unit for displaying a virtual image, and includes an image irradiation unit that irradiates first image light and second image light, and a projection optical unit that projects the first image light and the second image light onto the display unit as the projection image, the projection optical unit having a polarizing reflection unit that reflects polarized light in a first direction and transmits polarized light in a second direction perpendicular to the first direction, and a reflection unit that reflects the first image light towards the polarizing reflection unit, the polarizing reflection unit reflects the first image light from a first surface, and the second image light transmits from a second surface opposite the first surface.
　このような本発明の画像投影装置では、投影光学部が偏光反射部と反射部を備えており、第１画像光を反射部と偏光反射部で反射し、第２画像光を偏光反射部の第２面から透過させることで、第１画像光と第２画像光の光路を重ねることができ、投影光学部材の部品点数の増加を抑制し、光学部材の小型化を図りながら、複数の画像を投影することが可能となる。 In the image projection device of the present invention, the projection optical unit includes a polarized reflecting unit and a reflecting unit. The first image light is reflected by the reflecting unit and the polarized reflecting unit, and the second image light is transmitted through the second surface of the polarized reflecting unit, so that the optical paths of the first image light and the second image light can be overlapped. This makes it possible to project multiple images while suppressing an increase in the number of parts in the projection optical components and miniaturizing the optical components.
　また、本発明の一態様では、前記画像照射部は、前記第１方向または前記第２方向の偏光方向で前記第１画像光および前記第２画像光を照射し、前記投影光学部は、前記第１画像光または前記第２画像光の偏光方向を９０度回転させる二分の一波長板を備える。 In one aspect of the present invention, the image irradiation unit irradiates the first image light and the second image light with a polarization direction in the first direction or the second direction, and the projection optical unit includes a half-wave plate that rotates the polarization direction of the first image light or the second image light by 90 degrees.
　また、本発明の一態様では、前記画像照射部は、一つの表示装置で構成されており、前記第１画像光を照射する第１領域と、前記第２画像光を照射する第２領域を備え、前記反射部または前記偏光反射部の一方が前記第１領域に対向して配置され、前記反射部または前記偏光反射部の他方が前記第２領域に対向して配置されている。 In one aspect of the present invention, the image irradiation unit is configured with one display device and has a first region that irradiates the first image light and a second region that irradiates the second image light, with one of the reflecting unit or the polarized reflecting unit being disposed opposite the first region, and the other of the reflecting unit or the polarized reflecting unit being disposed opposite the second region.
　また、本発明の一態様では、前記投影光学部は反射プリズムを有し、前記反射部および前記偏光反射部は前記反射プリズムの対向する面に設けられている。 In one aspect of the present invention, the projection optical unit has a reflecting prism, and the reflecting unit and the polarizing reflecting unit are provided on opposing surfaces of the reflecting prism.
　また、本発明の一態様では、前記偏光反射部の前記反射プリズムと反対側の面に透過プリズムを備える。 In one embodiment of the present invention, the polarizing reflector is provided with a transmissive prism on the surface opposite the reflecting prism.
　また、本発明の一態様では、前記投影光学部から投影される前記第１画像光と前記第２画像光は、少なくとも一部の光路が重なっている。 In one aspect of the present invention, the first image light and the second image light projected from the projection optical unit have at least a portion of their optical paths overlapping.
　また、本発明の一態様では、前記虚像の結像位置は、前記第１画像光のほうが前記第２画像光よりも視点位置から遠い。 In one embodiment of the present invention, the imaging position of the virtual image is farther from the viewpoint position for the first image light than for the second image light.
　本発明では、投影光学部材の部品点数の増加を抑制し、光学部材の小型化を図りながら、複数の画像を投影することが可能な画像投影装置を提供することができる。 The present invention provides an image projection device capable of projecting multiple images while minimizing the number of parts in the projection optical components and miniaturizing the optical components.
第１実施形態に係る画像投影装置１００を用いた虚像の投影を示す模式図である。1 is a schematic diagram showing projection of a virtual image using an image projection device 100 according to a first embodiment. 第１実施形態に係る画像投影装置１００における画像照射部１０の概要を説明する模式図断面図である。FIG. 2 is a schematic cross-sectional view illustrating an overview of an image projection unit 10 in the image projection device 100 according to the first embodiment. 第１実施形態に係る画像投影装置１００における、画像表示部１２から照射される画像の表示領域を示す模式図である。2 is a schematic diagram showing a display area of an image projected from an image display unit 12 in the image projection device 100 according to the first embodiment. FIG. 第１実施形態に係る画像投影装置１００で投影された虚像Ｐ１，Ｐ２の位置関係を示す模式斜視図であり、図４（ａ）は視点位置からの斜視図を示し、図４（ｂ）は正面視を示している。4A and 4B are schematic perspective views showing the positional relationship between virtual images P1 and P2 projected by the image projection device 100 according to the first embodiment, where FIG. 4A shows a perspective view from the viewpoint position and FIG. 4B shows a front view. 第２実施形態に係る投影光学部の構成例を示す模式図である。13 is a schematic diagram showing an example of the configuration of a projection optical unit according to a second embodiment. FIG.
　（第１実施形態）
　以下、本発明の実施形態について、図面を参照して詳細に説明する。各図面に示される同一または同等の構成要素、部材、処理には、同一の符号を付すものとし、適宜重複した説明は省略する。図１は、本実施形態に係る画像投影装置１００を用いた虚像の投影を示す模式図である。図１中に示した一点鎖線は後述する第１画像光の光路を示し、二点鎖線は第２画像光の光路を示している。 First Embodiment
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be given the same reference numerals, and duplicated descriptions will be omitted as appropriate. Fig. 1 is a schematic diagram showing the projection of a virtual image using an image projection device 100 according to this embodiment. The dashed line in Fig. 1 indicates the optical path of a first image light, which will be described later, and the dashed line indicates the optical path of a second image light.
　図１に示すように、画像投影装置１００は、画像照射部１０と、第１ミラー２０と、第２ミラー３０と、外光カットフィルター４０を備えている。図１に示すように、画像投影装置１００から投影された第１画像光と第２画像光は、ウィンドシールド（表示部）ＷＳで反射されて運転者の視点位置に照射される。運転者は、第１画像光と第２画像光が入射してきた光路の延長上に結像された虚像Ｐ１，Ｐ２を視認する。 As shown in FIG. 1, the image projection device 100 includes an image projection unit 10, a first mirror 20, a second mirror 30, and an external light cut filter 40. As shown in FIG. 1, the first image light and the second image light projected from the image projection device 100 are reflected by the windshield (display unit) WS and irradiated to the driver's viewpoint. The driver visually recognizes virtual images P1 and P2 formed on the extension of the optical path along which the first image light and the second image light are incident.
　図１に示した画像投影装置１００では、各部と情報通信可能に接続された制御部を用いて、各部を制御している。制御部の構成は限定されないが、一例として情報処理を行うためのＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）や、メモリ装置、記録媒体、情報通信装置等を備えるものが挙げられる。制御部は、予め定められたプログラムに従って各部の動作を制御し、画像を含んだ情報（画像情報）を画像照射部１０に送出する。 In the image projection device 100 shown in FIG. 1, each part is controlled by a control unit connected to each part so that information can be communicated therewith. The configuration of the control unit is not limited, but one example is one that includes a CPU (Central Processing Unit) for information processing, a memory device, a recording medium, an information communication device, etc. The control unit controls the operation of each part according to a predetermined program, and sends information including an image (image information) to the image projection unit 10.
　画像照射部１０は、制御部からの画像情報に基づいて、画像を含んだ光を画像光として第１ミラー２０に対して照射する部分である。本実施形態では、二つの画像表示領域で表示された二つの画像光が第１画像光と第２画像光として第１ミラー２０に照射された例を示している。 The image irradiation unit 10 is a part that irradiates the first mirror 20 with light containing an image as image light based on image information from the control unit. In this embodiment, an example is shown in which two image lights displayed in two image display areas are irradiated to the first mirror 20 as the first image light and the second image light.
　第１ミラー２０は、画像照射部１０から到達した第１画像光と第２画像光を第２ミラー３０方向に反射する光学部材である。図１に示した例では第１ミラー２０を凹面形状の反射鏡として例を示しているが、平面または凸面の反射鏡を用いるとしてもよい。また、第１ミラー２０を曲面で構成する場合には、曲率が一定なものに限定されず、回転放物面や楕円面、自由曲面ミラー等を用いることができる。 The first mirror 20 is an optical member that reflects the first image light and the second image light arriving from the image irradiation unit 10 in the direction of the second mirror 30. In the example shown in FIG. 1, the first mirror 20 is a concave reflecting mirror, but a flat or convex reflecting mirror may also be used. Furthermore, when the first mirror 20 is configured with a curved surface, it is not limited to a surface with a constant curvature, and a paraboloid of revolution, an ellipsoid, a free-form surface mirror, etc. may be used.
　第２ミラー３０は、第１ミラー２０から到達した第１画像光と第２画像光をウィンドシールドＷＳ方向に反射する光学部材である。図１に示した例では、第２ミラー３０として第１画像光および第２画像光を虚像Ｐ１，Ｐ２として投影するために必要な光学設計された凹面形状の自由曲面ミラーを示している。 The second mirror 30 is an optical member that reflects the first image light and the second image light arriving from the first mirror 20 in the direction of the windshield WS. In the example shown in FIG. 1, the second mirror 30 is a free-form mirror with an optically designed concave shape necessary for projecting the first image light and the second image light as virtual images P1 and P2.
　第１ミラー２０および第２ミラー３０の反射面は、ウィンドシールドＷＳを介して第１画像光および第２画像光を虚像Ｐ１，Ｐ２として投影するために、運転者の視点方向に光径が拡大するように設計されている。ここで、視点方向に光径が拡大するとは、反射後に光径が一貫して拡大する場合だけでなく、光径が縮小して中間地点において結像した後に拡大する場合も含む。 The reflective surfaces of the first mirror 20 and the second mirror 30 are designed to expand the light diameter in the driver's viewing direction in order to project the first image light and the second image light as virtual images P1 and P2 through the windshield WS. Here, the expansion of the light diameter in the viewing direction includes not only the case where the light diameter expands consistently after reflection, but also the case where the light diameter shrinks and expands after forming an image at an intermediate point.
　また図１では、第１画像光と第２画像光の光路を一本の直線として描いている。しかし、実際の第１画像光と第２画像光は、画像照射部１０において所定の面積で表示されたものであり、進行方向に垂直な方向に所定の面積をもっている。また、第１画像光と第２画像光は、第１ミラー２０で反射されて光径が縮小されながら進行し、第１ミラー２０と第２ミラー３０の間の中間結像位置Ｆ（図示省略）において中間結像されるとしてもよい。 In addition, in FIG. 1, the optical paths of the first image light and the second image light are depicted as a single straight line. However, the actual first image light and second image light are displayed in a predetermined area in the image projection unit 10, and have a predetermined area in the direction perpendicular to the traveling direction. In addition, the first image light and the second image light are reflected by the first mirror 20, and the light diameter is reduced as they travel, and they may be intermediately imaged at an intermediate imaging position F (not shown) between the first mirror 20 and the second mirror 30.
　外光カットフィルター４０は、第２ミラー３０とウィンドシールドＷＳの間に配置され、外部から画像投影装置１００の内部に到達する外光の一部をカットする部分である。特に、ウィンドシールドＷＳの上方から画像照射部１０に太陽光が到達して、画像表示部１２の温度が上昇することを防止するために、可視光を透過して赤外光や紫外光をカットする波長フィルタを用いることが好ましい。 The external light cut filter 40 is disposed between the second mirror 30 and the windshield WS, and cuts out a portion of the external light that reaches the inside of the image projection device 100 from the outside. In particular, to prevent sunlight from reaching the image projection unit 10 from above the windshield WS and causing the temperature of the image display unit 12 to rise, it is preferable to use a wavelength filter that transmits visible light and cuts infrared and ultraviolet light.
　ウィンドシールドＷＳは、車両の運転席前方に設けられて可視光を透過する部分である。ウィンドシールドＷＳは、車両の内側面では画像投影装置１００から入射した第１画像光および第２画像光を視点方向に対して反射し、車両の外部からの光を視点方向に対して透過するため、本発明における表示部に相当している。ここでは表示部としてウィンドシールドＷＳを用いた例を示したが、ウィンドシールドＷＳとは別に表示部としてコンバイナーを用意し、画像投影装置１００からの光を視点方向に反射するとしてもよい。また、車両の前方に位置するものに限定されず、搭乗者の視点に対して画像を投影するものであれば側方や後方に配置するとしてもよい。 The windshield WS is a part that is provided in front of the driver's seat of the vehicle and transmits visible light. On the inside surface of the vehicle, the windshield WS reflects the first image light and the second image light that are incident from the image projection device 100 toward the viewpoint direction, and transmits light from outside the vehicle toward the viewpoint direction, and therefore corresponds to the display unit in the present invention. Here, an example is shown in which the windshield WS is used as the display unit, but a combiner may be provided as a display unit separate from the windshield WS, and the light from the image projection device 100 may be reflected toward the viewpoint direction. In addition, the windshield WS is not limited to being located at the front of the vehicle, and may be located to the side or rear as long as it projects an image toward the viewpoint of the passenger.
　虚像Ｐ１，Ｐ２は、ウィンドシールドＷＳで反射された第１画像光および第２画像光が搭乗者の視点（アイボックス）に到達した際に、空間中に結像されたように表示される画像である。虚像Ｐ１，Ｐ２が結像される位置は、画像投影装置１００に含まれる投影光学部とウィンドシールドＷＳの合成焦点距離によって決まる。 Virtual images P1 and P2 are images that are displayed as if they were formed in space when the first image light and the second image light reflected by the windshield WS reach the passenger's viewpoint (eyebox). The positions at which virtual images P1 and P2 are formed are determined by the composite focal length of the projection optical unit included in the image projection device 100 and the windshield WS.
　本実施形態の画像投影装置１００では、画像照射部１０の遠方表示領域に表示された遠方画像が第１画像光として照射され、近方表示領域に表示された近方画像が第２画像光として照射される。遠方表示領域に表示される遠方画像としては、注意喚起の画像や緊急情報等の運転に関する補助的な情報が挙げられる。また、近方表示領域に表示される近方画像としては、速度と音量インジケータ、進行方向ガイド等が挙げられる。 In the image projection device 100 of this embodiment, the distant image displayed in the distant display area of the image irradiation unit 10 is irradiated as the first image light, and the near image displayed in the near display area is irradiated as the second image light. Distant images displayed in the distant display area include auxiliary information related to driving, such as images calling attention and emergency information. Near images displayed in the near display area include speed and volume indicators, driving direction guides, etc.
　図２は、本実施形態に係る画像投影装置１００における画像照射部１０の概要を説明する模式図断面図である。図２に示した例では、画像照射部１０はバックライト１１、画像表示部１２、二分の一波長板１３、反射プリズム１４、偏光反射部１５を備えている。 FIG. 2 is a schematic cross-sectional view for explaining an overview of the image projection unit 10 in the image projection device 100 according to this embodiment. In the example shown in FIG. 2, the image projection unit 10 includes a backlight 11, an image display unit 12, a half-wave plate 13, a reflecting prism 14, and a polarizing reflecting unit 15.
　バックライト１１は、画像表示部１２に対して照射光を照射する部分であり、例えば発光ダイオード（ＬＥＤ：Ｌｉｇｈｔ　Ｅｍｉｔｔｉｎｇ　Ｄｉｏｄｅ）により光を照射するものを用いることができる。バックライト１１が照射する光は白色が好ましいが、青色や緑色、赤色などの単色を発光するものを用いるとしてもよい。またバックライト１１はＬＥＤに限らず半導体レーザや有機ＥＬ（Ｅｌｅｃｔｒｏ　Ｌｕｍｉｎｅｓｃｅｎｃｅ）素子等であってもよい。 The backlight 11 is a part that irradiates light onto the image display unit 12, and may be, for example, a light-emitting diode (LED) that irradiates light. The light irradiated by the backlight 11 is preferably white, but it may also be a light that emits a single color such as blue, green, or red. The backlight 11 is not limited to an LED, and may be a semiconductor laser, an organic EL (Electro Luminescence) element, or the like.
　画像表示部１２は、制御部からの画像信号に応じて投影画像を表示する部分である。画像表示部１２に表示された投影画像に対して、バックライト１１からの照射光が照射されることで、画像表示部１２から第１画像光および第２画像光が照射される。画像表示部１２の具体的構成は限定されず、例えば液晶表示装置等を用いることができる。後述するように画像表示部１２は、遠方画像と近方画像をそれぞれ表示する遠方表示領域（第１領域）と近方表示領域（第２領域）を含んで構成されている。 The image display unit 12 is a part that displays a projected image in response to an image signal from the control unit. When light from the backlight 11 is irradiated onto the projected image displayed on the image display unit 12, a first image light and a second image light are irradiated from the image display unit 12. The specific configuration of the image display unit 12 is not limited, and for example, a liquid crystal display device or the like can be used. As described below, the image display unit 12 is configured to include a far display area (first area) and a near display area (second area) that display a far image and a near image, respectively.
　画像表示部１２として液晶表示装置を用いる場合には、画像表示部１２から照射される第１画像光と第２画像光は共に所定方向に直線偏光している。画像表示部１２からの第１画像光および第２画像光が直線偏光していない場合には、所定方向の直線偏光だけを透過する偏光板を用いて、第１画像光と第２画像光を同じ方向の直線偏光として照射させることができる。 When a liquid crystal display device is used as the image display unit 12, the first image light and the second image light irradiated from the image display unit 12 are both linearly polarized in a predetermined direction. When the first image light and the second image light from the image display unit 12 are not linearly polarized, a polarizing plate that transmits only linearly polarized light in a predetermined direction can be used to irradiate the first image light and the second image light as linearly polarized light in the same direction.
　二分の一波長板１３は、画像表示部１２の遠方表示領域または近方表示領域に配置され、スロー軸とファスト軸における屈折率が異なる複屈折材料で構成された光学部材である。また、二分の一波長板１３は、入射した光が出射するまでに光の波長の半分だけスロー軸とファスト軸で位相差が生じるように設計されている。また、二分の一波長板１３のスロー軸とファスト軸は、画像表示部１２から照射された光の偏光方向に対して４５度異なる向きに配置されている。図２に示した例では近方表示領域に二分の一波長板１３を重ねて配置した例を示しているが、遠方表示領域に重ねて配置するとしてもよい。 The half-wave plate 13 is an optical element arranged in the far display area or near display area of the image display unit 12, and is made of a birefringent material with different refractive indices in the slow axis and the fast axis. The half-wave plate 13 is designed so that a phase difference of half the wavelength of the light occurs between the slow axis and the fast axis before the incident light is emitted. The slow axis and the fast axis of the half-wave plate 13 are arranged in directions that differ by 45 degrees with respect to the polarization direction of the light irradiated from the image display unit 12. In the example shown in FIG. 2, the half-wave plate 13 is arranged overlapping the near display area, but it may also be arranged overlapping the far display area.
　反射プリズム１４は、透光性材料で構成された断面が平行四辺形の光学部材である。平行四辺形の対向する一対の面は、入射した光が全反射する角度で切り出された反射面１４ａと透過反射部１４ｂであり、反射面１４ａと透過反射部１４ｂに隣接する一対の面は光の光入射面１４ｃおよび光出射面１４ｄである。ここで反射面１４ａは本発明における反射部に相当している。また、透過反射部１４ｂに偏光反射部１５が配置されている。また、反射面１４ａは反射プリズム１４を構成する材料と空気の屈折率差によって光が全反射するとしてもよく、反射率を向上させるために反射面１４ａに金属や誘電体多層膜で反射膜を形成するとしてもよく、反射シートを貼り付けるとしてもよい。また、ここでは反射プリズム１４の反射面１４ａとして全反射する角度で切り出された例を示しているが、反射は全反射でなくともよい。図２では反射プリズム１４として断面が平行四辺形の例を示したが、反射プリズム１４の形状は平行四辺形に限定されない。 The reflecting prism 14 is an optical member made of a light-transmitting material and has a cross section in the shape of a parallelogram. A pair of opposing surfaces of the parallelogram are the reflecting surface 14a and the transmission reflecting section 14b cut at an angle at which the incident light is totally reflected, and a pair of surfaces adjacent to the reflecting surface 14a and the transmission reflecting section 14b are the light incident surface 14c and the light exit surface 14d. Here, the reflecting surface 14a corresponds to the reflection section in the present invention. In addition, the polarized reflection section 15 is disposed in the transmission reflecting section 14b. In addition, the reflecting surface 14a may totally reflect light due to the difference in refractive index between the material constituting the reflecting prism 14 and the air, or a reflection film may be formed on the reflecting surface 14a using a metal or dielectric multilayer film to improve the reflectance, or a reflection sheet may be attached. In addition, an example is shown here where the reflecting surface 14a of the reflecting prism 14 is cut at an angle at which the incident light is totally reflected, but the reflection does not have to be total reflection. In FIG. 2, an example of a reflecting prism 14 with a cross section that is a parallelogram is shown, but the shape of the reflecting prism 14 is not limited to a parallelogram.
　偏光反射部１５は、反射プリズム１４の透過反射部１４ｂに貼り合わせて配置され、第１方向の偏光を反射し、第１方向に直交する第２方向の偏光を透過する光学部材である。偏光反射部１５が透過する偏光方向は限定されず、最終的に照射される第１画像光または第２画像光に要求される偏光方向に適合させる必要がある。一例としては図１における紙面に垂直な方向の偏光（例えばｓ偏光）を反射するとしてもよい。偏光反射部１５は、バックライト１１から照射される光の進行方向に対して所定角度だけ傾斜して配置されている。図２に示した例では、偏光反射部１５の裏面に近方表示領域から照射された第２画像光を入射させる例を示しているが、遠方表示領域から照射された第１画像光を入射させるとしてもよい。 The polarizing reflector 15 is an optical member that is bonded to the transmissive reflector 14b of the reflecting prism 14 and reflects polarized light in a first direction and transmits polarized light in a second direction perpendicular to the first direction. The polarized light direction transmitted by the polarizing reflector 15 is not limited, and must be adapted to the polarization direction required for the first image light or the second image light that is ultimately irradiated. As an example, the polarized light may be reflected in a direction perpendicular to the paper surface in FIG. 1 (e.g., s-polarized light). The polarizing reflector 15 is disposed at a predetermined angle with respect to the traveling direction of the light irradiated from the backlight 11. In the example shown in FIG. 2, the second image light irradiated from the near display area is incident on the rear surface of the polarizing reflector 15, but the first image light irradiated from the far display area may also be incident thereon.
　上述した例では、反射プリズム１４、偏光反射部１５、第１ミラー２０および第２ミラー３０の組み合わせが、ウィンドシールドＷＳを介して第１画像光および第２画像光を投影する機能を有しており、本発明における照射光学部に相当している。また、本実施形態では投影光学部の一部に反射プリズム１４を用いた例を示したが、反射部を反射鏡で構成し、偏光反射部１５と所定の位置関係で保持して、反射鏡で反射した光が偏光反射部１５に入射するとしてもよい。 In the above example, the combination of the reflecting prism 14, the polarizing reflecting section 15, the first mirror 20, and the second mirror 30 has the function of projecting the first image light and the second image light through the windshield WS, and corresponds to the irradiation optical section in the present invention. Also, in this embodiment, an example has been shown in which the reflecting prism 14 is used as part of the projection optical section, but the reflecting section may be configured as a reflecting mirror and held in a predetermined positional relationship with the polarizing reflecting section 15, so that the light reflected by the reflecting mirror is incident on the polarizing reflecting section 15.
　図３は、本実施形態に係る画像投影装置１００における、画像表示部１２から照射される画像の表示領域を示す模式図である。全表示領域１２ａは、画像表示部１２の画像を表示する領域全体である。全表示領域１２ａの一部は近方表示領域１２ｂであり、他の一部は遠方表示領域１２ｃである。遠方表示領域１２ｃは第１画像が表示され、本発明における第１領域に相当している。近方表示領域１２ｂは第２画像が表示され、本発明における第２領域に相当している。 FIG. 3 is a schematic diagram showing the display area of the image projected from the image display unit 12 in the image projection device 100 according to this embodiment. The full display area 12a is the entire area in which the image of the image display unit 12 is displayed. A part of the full display area 12a is the near display area 12b, and another part is the far display area 12c. The far display area 12c displays the first image and corresponds to the first area in the present invention. The near display area 12b displays the second image and corresponds to the second area in the present invention.
　図２および図３に示した例では、画像表示部１２の遠方表示領域１２ｃに重ね合わせて反射プリズム１４の光入射面１４ｃが配置され、近方表示領域１２ｂに対向する位置に二分の一波長板１３、透過反射部１４ｂおよび偏光反射部１５が配置されている。したがって、反射面１４ａは遠方表示領域１２ｃに対向して配置され、偏光反射部１５は近方表示領域１２ｂに対向して配置されている。また、画像表示部１２から照射される光の偏光方向は、偏光反射部１５で反射される方向と略一致している。 In the example shown in Figures 2 and 3, the light entrance surface 14c of the reflecting prism 14 is arranged so as to overlap the far display area 12c of the image display unit 12, and the half-wave plate 13, the transmission reflection unit 14b, and the polarizing reflection unit 15 are arranged in a position facing the near display area 12b. Therefore, the reflection surface 14a is arranged facing the far display area 12c, and the polarizing reflection unit 15 is arranged facing the near display area 12b. In addition, the polarization direction of the light irradiated from the image display unit 12 is approximately the same as the direction reflected by the polarizing reflection unit 15.
　ここで、反射プリズム１４を画像表示部１２に重ねて配置するとは、平面視において反射プリズム１４を配置した領域が画像表示部１２の画像表示領域と重複することを意味している。また、反射プリズム１４と画像表示部１２が接触している場合も非接触の場合も重ねて配置に含まれるものとする。また、反射プリズム１４と画像表示部１２の間に光を透過する光学部材や、両者の間隔を維持するための保持部材を介在させている場合も、重ねて配置に含まれる。 Here, placing the reflecting prism 14 on the image display unit 12 means that the area in which the reflecting prism 14 is placed overlaps with the image display area of the image display unit 12 in a planar view. The overlapping arrangement also includes cases where the reflecting prism 14 and the image display unit 12 are in contact and cases where they are not in contact. The overlapping arrangement also includes cases where a light-transmitting optical member or a holding member for maintaining the distance between the reflecting prism 14 and the image display unit 12 is interposed between the reflecting prism 14 and the image display unit 12.
　図２に示した例では、遠方表示領域１２ｃから照射された第１画像光は、反射プリズム１４の光入射面１４ｃに入射し、反射面１４ａで反射された後に偏光反射部１５によって再反射され、光出射面１４ｄから第１ミラー２０に照射される。また、近方表示領域１２ｂから照射された第２画像光は、二分の一波長板１３を透過して偏光方向が９０度回転され、偏光反射部１５の裏面に入射し、偏光反射部１５および透過反射部１４ｂを透過して、光出射面１４ｄから第１ミラー２０に照射される。第１画像光は反射面１４ａと偏光反射部１５で反射される間に、反射プリズム１４の内部を通過するため、光出射面１４ｄから照射されるまでの光路は第２画像光よりも長くなる。これにより、第１画像光で結像される虚像Ｐ１のウィンドシールドＷＳからの結像距離は、第２画像光で結像される虚像Ｐ２よりも遠くなる。 In the example shown in FIG. 2, the first image light irradiated from the far display area 12c enters the light incident surface 14c of the reflecting prism 14, is reflected by the reflecting surface 14a, is reflected again by the polarizing reflector 15, and is irradiated from the light exit surface 14d to the first mirror 20. The second image light irradiated from the near display area 12b passes through the half-wave plate 13, has its polarization direction rotated by 90 degrees, enters the back surface of the polarizing reflector 15, passes through the polarizing reflector 15 and the transmissive reflector 14b, and is irradiated from the light exit surface 14d to the first mirror 20. Because the first image light passes through the inside of the reflecting prism 14 while being reflected by the reflecting surface 14a and the polarizing reflector 15, the optical path until it is irradiated from the light exit surface 14d is longer than that of the second image light. As a result, the imaging distance of the virtual image P1 formed by the first image light from the windshield WS is greater than the imaging distance of the virtual image P2 formed by the second image light.
　反射プリズム１４の光出射面１４ｄから照射された第１画像光と第２画像光は、それぞれ第１ミラー２０、第２ミラー３０およびウィンドシールドＷＳで反射されて運転者の視点に到達する。第１画像光および第２画像光は、第１ミラー２０および第２ミラー３０によって光径が拡大して視点に到達するため、運転者は第１画像光および第２画像光による虚像Ｐ１，Ｐ２が所定距離に結像されているように視認する。ここで、虚像Ｐ１，Ｐ２の結像位置は、第１画像のほうが第２画像よりも視点位置から遠いものとなっている。 The first and second image lights irradiated from the light exit surface 14d of the reflecting prism 14 are reflected by the first mirror 20, the second mirror 30, and the windshield WS, respectively, and reach the driver's viewpoint. Because the first and second image lights reach the viewpoint with their light diameters expanded by the first and second mirrors 20 and 30, the driver visually recognizes virtual images P1 and P2 formed by the first and second image lights as if they were formed at a predetermined distance. Here, the imaging positions of the virtual images P1 and P2 are such that the first image is farther from the viewpoint than the second image.
　図２に示したように、反射プリズム１４の光出射面１４ｄから照射された第１画像光と第２画像光の光路は、少なくとも一部の光路が重なっている。これにより、第１画像光と第２画像光を投影するために確保する光路の空間を小さくして、画像投影装置１００の小型化を図ることができる。 As shown in FIG. 2, the optical paths of the first image light and the second image light irradiated from the light exit surface 14d of the reflecting prism 14 at least partially overlap. This reduces the space of the optical paths required to project the first image light and the second image light, making it possible to miniaturize the image projection device 100.
　図４は、本実施形態に係る画像投影装置１００で投影された虚像Ｐ１，Ｐ２の位置関係を示す模式斜視図であり、図４（ａ）は視点位置からの斜視図を示し、図４（ｂ）は正面視を示している。図４（ａ）（ｂ）に示したように、虚像Ｐ１，Ｐ２の結像位置は奥行きが異なり、俯角が同程度となる。ここで、光出射面１４ｄから照射される第１画像光と第２画像光の光路を略同一とすることがより好ましい。これより、視点位置からみた第１画像光で結像される虚像Ｐ１の俯角と、第２画像光で結像される虚像Ｐ２の俯角が略同一となり、視線移動をせずに虚像Ｐ１と虚像Ｐ２を視認することが可能となる。 FIG. 4 is a schematic perspective view showing the positional relationship of virtual images P1 and P2 projected by the image projection device 100 according to this embodiment, where FIG. 4(a) shows a perspective view from the viewpoint position and FIG. 4(b) shows a front view. As shown in FIGS. 4(a) and 4(b), the image positions of virtual images P1 and P2 are at different depths and have approximately the same depression angle. Here, it is more preferable to make the optical paths of the first image light and the second image light irradiated from the light exit surface 14d approximately the same. As a result, the depression angle of virtual image P1 formed by the first image light as viewed from the viewpoint position and the depression angle of virtual image P2 formed by the second image light are approximately the same, making it possible to view virtual images P1 and P2 without moving the line of sight.
　図４（ａ）（ｂ）に示した例では、第１画像光と第２画像光の光路が一致して、虚像Ｐ１と虚像Ｐ２の中心が同じ視線上となっているが、第１画像光と第２画像光の光路を少し異ならせて、虚像Ｐ１と虚像Ｐ２の中心が異なる視線上になるとしてもよい。 In the example shown in Figures 4(a) and (b), the optical paths of the first image light and the second image light coincide with each other, and the centers of the virtual images P1 and P2 are on the same line of sight, but the optical paths of the first image light and the second image light may be slightly different so that the centers of the virtual images P1 and P2 are on different lines of sight.
　また、図４（ａ）（ｂ）に示した例では、虚像Ｐ１と虚像Ｐ２が正面視において重なり合っているため、虚像Ｐ１と虚像Ｐ２を同時に結像させると視認性が低下する。したがって、虚像Ｐ１と虚像Ｐ２の正面視における結像位置が重なり合う場合には、画像表示部１２における遠方表示領域１２ｃと近方表示領域１２ｂでの表示を排他的に切り替え、虚像Ｐ１と虚像Ｐ２の結像を切り替えることが好ましい。 In the example shown in Figures 4(a) and (b), the virtual images P1 and P2 overlap when viewed from the front, so visibility is reduced when the virtual images P1 and P2 are formed simultaneously. Therefore, when the image positions of the virtual images P1 and P2 overlap when viewed from the front, it is preferable to exclusively switch the display in the far display area 12c and the near display area 12b of the image display unit 12, and switch the image formation of the virtual images P1 and P2.
　上述したように、本実施形態の画像投影装置１００では、投影光学部が偏光反射部１５と反射面１４ａを備えており、第１画像光を反射面１４ａと偏光反射部１５で反射し、第２画像光を偏光反射部１５の裏面から透過させることで、第１画像光と第２画像光の光路を重ねることができ、投影光学部材の部品点数の増加を抑制し、光学部材の小型化を図りながら、複数の画像を投影することが可能となる。 As described above, in the image projection device 100 of this embodiment, the projection optical unit includes a polarized reflecting unit 15 and a reflecting surface 14a. The first image light is reflected by the reflecting surface 14a and the polarized reflecting unit 15, and the second image light is transmitted through the rear surface of the polarized reflecting unit 15, thereby overlapping the optical paths of the first image light and the second image light. This makes it possible to project multiple images while suppressing an increase in the number of parts in the projection optical components and miniaturizing the optical components.
　（第２実施形態）
　次に、本発明の第２実施形態について図５を用いて説明する。第１実施形態と重複する内容は説明を省略する。図５は、本実施形態に係る投影光学部の構成例を示す模式図である。図５に示すように、本実施形態の投影光学部は、反射プリズム１４と、偏光反射部１５と、透過プリズム１６を備えている。 Second Embodiment
Next, a second embodiment of the present invention will be described with reference to Fig. 5. Descriptions of contents overlapping with those of the first embodiment will be omitted. Fig. 5 is a schematic diagram showing an example of the configuration of a projection optical unit according to this embodiment. As shown in Fig. 5, the projection optical unit of this embodiment includes a reflecting prism 14, a polarizing reflecting unit 15, and a transmitting prism 16.
　透過プリズム１６は、透光性材料で構成された光学部材であり、偏光反射部１５の反射プリズム１４とは反対側の面に配置されている。図５では透過プリズム１６の形状として断面が直角三角形の例を示しているが、形状は限定されない。透過プリズム１６には光出射面１６ａと光入射面１６ｂが設けられており、透過プリズム１６の光出射面１６ａと反射プリズム１４の透過反射部１４ｂとの間に偏光反射部１５が挟み込まれている。透過プリズム１６の光入射面１６ｂと、反射プリズム１４の光入射面１４ｃは、平行に配置されることが好ましく、さらに好ましくは面一に配置されることが好ましい。 The transmitting prism 16 is an optical member made of a light-transmitting material, and is disposed on the surface of the polarizing reflecting section 15 opposite the reflecting prism 14. Although FIG. 5 shows an example of the shape of the transmitting prism 16 having a cross section of a right-angled triangle, the shape is not limited. The transmitting prism 16 is provided with a light exit surface 16a and a light entrance surface 16b, and the polarizing reflecting section 15 is sandwiched between the light exit surface 16a of the transmitting prism 16 and the transmitting reflecting section 14b of the reflecting prism 14. The light entrance surface 16b of the transmitting prism 16 and the light entrance surface 14c of the reflecting prism 14 are preferably disposed in parallel, and more preferably disposed flush.
　本実施形態では、遠方表示領域１２ｃから照射された第１画像光は、反射プリズム１４の光入射面１４ｃに入射し、反射面１４ａで反射された後に偏光反射部１５によって再反射され、光出射面１４ｄから第１ミラー２０に照射される。また、近方表示領域１２ｂから照射された第２画像光は、二分の一波長板１３を透過して偏光方向が９０度回転され、透過プリズム１６の光入射面１６ｂに入射し、光出射面１６ａから偏光反射部１５の裏面に入射し、偏光反射部１５および透過反射部１４ｂを透過して、光出射面１４ｄから第１ミラー２０に照射される。 In this embodiment, the first image light irradiated from the far display area 12c enters the light entrance surface 14c of the reflecting prism 14, is reflected by the reflecting surface 14a, is reflected again by the polarizing reflector 15, and is irradiated from the light exit surface 14d to the first mirror 20. The second image light irradiated from the near display area 12b passes through the half-wave plate 13, has its polarization direction rotated by 90 degrees, enters the light entrance surface 16b of the transmitting prism 16, enters the back surface of the polarizing reflector 15 from the light exit surface 16a, passes through the polarizing reflector 15 and the transmitting reflector 14b, and is irradiated from the light exit surface 14d to the first mirror 20.
　透過プリズム１６を偏光反射部１５の裏面側に配置することで、第２画像光が反射プリズム１４に入射する際の空気との屈折率差を解消し、透過反射部１４ｂで第２画像光が屈折されることを抑制できる。これにより、画像表示部１２から照射される第１画像光および第２画像光の進行方向に対して、反射面１４ａ、透過反射部１４ｂおよび光出射面１６ａを同じ角度で傾斜させるだけで、光出射面１４ｄから照射される第１画像光と第２画像光の進行方向を同じにすることができ、光路を合わせるための光学設計が容易となる。 By arranging the transmission prism 16 on the back side of the polarized reflection section 15, the difference in refractive index between the second image light and the air when it enters the reflection prism 14 is eliminated, and the refraction of the second image light at the transmission reflection section 14b can be suppressed. As a result, simply by tilting the reflection surface 14a, the transmission reflection section 14b, and the light exit surface 16a at the same angle with respect to the traveling directions of the first image light and the second image light irradiated from the image display section 12, the traveling directions of the first image light and the second image light irradiated from the light exit surface 14d can be made the same, making it easier to carry out optical design for matching the light paths.
　（第３実施形態）
　次に、本発明の第３実施形態について説明する。第１実施形態と重複する内容は説明を省略する。第１実施形態では、一つの画像表示部１２において近方表示領域１２ｂと遠方表示領域１２ｃを設け、どちらか一方に二分の一波長板１３を配置した例を示したが、画像表示部１２として二つ以上の液晶表示装置を用いるとしてもよい。この場合には、二つの液晶表示装置から照射される第１画像光と第２画像光の偏光方向が９０度異なるように配置し、二分の一波長板１３を省略するとしてもよい。 Third Embodiment
Next, a third embodiment of the present invention will be described. Descriptions of contents overlapping with the first embodiment will be omitted. In the first embodiment, an example was shown in which a near display region 12b and a far display region 12c are provided in one image display unit 12, and a half-wave plate 13 is arranged in one of them, but two or more liquid crystal display devices may be used as the image display unit 12. In this case, the two liquid crystal display devices may be arranged so that the polarization directions of the first image light and the second image light irradiated from the two liquid crystal display devices differ by 90 degrees, and the half-wave plate 13 may be omitted.
　本実施形態では、一方の液晶表示装置から照射された第１画像光は、偏光反射部１５で反射される偏光方向であり、反射プリズム１４の光入射面１４ｃに入射し、反射面１４ａで反射された後に偏光反射部１５によって再反射され、光出射面１４ｄから第１ミラー２０に照射される。また、他方の液晶表示装置から照射された第２画像光は、偏光反射部１５を透過する偏光方向であり、偏光反射部１５の裏面に入射し、偏光反射部１５および透過反射部１４ｂを透過して、光出射面１４ｄから第１ミラー２０に照射される。 In this embodiment, the first image light irradiated from one liquid crystal display device has a polarization direction that is reflected by the polarizing reflector 15, enters the light entrance surface 14c of the reflecting prism 14, is reflected by the reflecting surface 14a, is reflected again by the polarizing reflector 15, and is irradiated from the light exit surface 14d to the first mirror 20. The second image light irradiated from the other liquid crystal display device has a polarization direction that transmits through the polarizing reflector 15, enters the back surface of the polarizing reflector 15, transmits through the polarizing reflector 15 and the transmission reflector 14b, and is irradiated from the light exit surface 14d to the first mirror 20.
　本発明は上述した各実施形態に限定されるものではなく、請求項に示した範囲で種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本発明の技術的範囲に含まれる。 The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments.
　本国際出願は、２０２３年３月１０日に出願された日本国特許出願である特願２０２３－０３８１７３号に基づく優先権を主張するものであり、当該日本国特許出願である特願２０２３－０３８１７３号の全内容は、本国際出願に援用される。 This international application claims priority based on Japanese patent application No. 2023-038173, filed on March 10, 2023, the entire contents of which are incorporated herein by reference.
　本発明の特定の実施の形態についての上記説明は、例示を目的として提示したものである。それらは、網羅的であったり、記載した形態そのままに本発明を制限したりすることを意図したものではない。数多くの変形や変更が、上記の記載内容に照らして可能であることは当業者に自明である。 The above descriptions of specific embodiments of the present invention are presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the precise forms described. It will be apparent to one of ordinary skill in the art that numerous modifications and variations are possible in light of the above description.
１００…画像投影装置
１０…画像照射部
１１…バックライト
１２…画像表示部
１２ａ…全表示領域
１２ｂ…近方表示領域
１２ｃ…遠方表示領域
１３…二分の一波長板
１４…反射プリズム
１４ａ…反射面
１４ｂ…透過反射部
１４ｃ,１６ｂ…光入射面
１４ｄ, １６ａ…光出射面
１５…偏光反射部
１６…透過プリズム
２０…第１ミラー
３０…第２ミラー
４０…外光カットフィルター 
  Reference Signs List 100...Image projection device 10...Image irradiation section 11...Backlight 12...Image display section 12a...Total display area 12b...Near display area 12c...Far display area 13...Half-wavelength plate 14...Reflecting prism 14a...Reflecting surface 14b...Transmitting and reflecting section 14c, 16b... Light entrance surface 14d, 16a...Light exit surface 15...Polarizing reflecting section 16...Transmitting prism 20...First mirror 30...Second mirror 40...External light cut filter

Claims (7)

  1. 　虚像を表示するための表示部に対して投影画像を投影する画像投影装置であって、
    　第１画像光および第２画像光を照射する画像照射部と、
    　前記表示部に対して前記第１画像光および前記第２画像光を前記投影画像として投影する投影光学部を備え、
    　前記投影光学部は、第１方向の偏光を反射し前記第１方向と直交する第２方向の偏光を透過する偏光反射部と、前記第１画像光を前記偏光反射部に向けて反射する反射部と、を有し、
    　前記偏光反射部は、第１面で前記第１画像光を反射し、前記第１面と反対側の第２面から前記第２画像光が透過することを特徴とする画像投影装置。     An image projection device that projects a projection image onto a display unit for displaying a virtual image,
    an image irradiating unit that irradiates the first image light and the second image light;
    a projection optical unit that projects the first image light and the second image light onto the display unit as the projection image,
    the projection optical unit includes a polarizing reflecting unit that reflects polarized light in a first direction and transmits polarized light in a second direction perpendicular to the first direction, and a reflecting unit that reflects the first image light toward the polarizing reflecting unit,
    The polarizing reflector reflects the first image light from a first surface and transmits the second image light from a second surface opposite the first surface.
  2. 　請求項１に記載の画像投影装置であって、
    　前記画像照射部は、前記第１方向または前記第２方向の偏光方向で前記第１画像光および前記第２画像光を照射し、
    　前記投影光学部は、前記第１画像光または前記第２画像光の偏光方向を９０度回転させる二分の一波長板を備えることを特徴とする画像投影装置。     2. The image projection device according to claim 1,
    the image irradiating unit irradiates the first image light and the second image light in a polarization direction of the first direction or the second direction,
    The image projection device according to claim 1, wherein the projection optical unit includes a half-wave plate that rotates the polarization direction of the first image light or the second image light by 90 degrees.
  3. 　請求項１に記載の画像投影装置であって、
    　前記画像照射部は、一つの表示装置で構成されており、前記第１画像光を照射する第１領域と、前記第２画像光を照射する第２領域を備え、
    　前記反射部または前記偏光反射部の一方が前記第１領域に対向して配置され、
    　前記反射部または前記偏光反射部の他方が前記第２領域に対向して配置されていることを特徴とする画像投影装置。     2. The image projection device according to claim 1,
    the image irradiating unit is configured with one display device and includes a first region that irradiates the first image light and a second region that irradiates the second image light,
    one of the reflective section and the polarizing reflective section is disposed opposite to the first region,
    The image projection device, wherein the other of the reflecting section or the polarizing reflecting section is disposed opposite the second area.
  4. 　請求項１に記載の画像投影装置であって、
    　前記投影光学部は反射プリズムを有し、前記反射部および前記偏光反射部は前記反射プリズムの対向する面に設けられていることを特徴とする画像投影装置。     2. The image projection device according to claim 1,
    13. An image projection device, comprising: a projection optical section having a reflecting prism; and a reflecting section and a polarizing reflecting section provided on opposing surfaces of the reflecting prism.
  5. 　請求項４に記載の画像投影装置であって、
    　前記偏光反射部の前記反射プリズムと反対側の面に透過プリズムを備えることを特徴とする画像投影装置。     5. The image projection device according to claim 4,
    an optical transmission prism provided on a surface of the polarizing reflector opposite to the reflecting prism;
  6. 　請求項１に記載の画像投影装置であって、
    　前記投影光学部から投影される前記第１画像光と前記第２画像光は、少なくとも一部の光路が重なっていることを特徴とする画像投影装置。     2. The image projection device according to claim 1,
    An image projection device, characterized in that the first image light and the second image light projected from the projection optical unit have at least a part of their optical paths overlapping each other.
  7. 　請求項１から６の何れか一つに記載の画像投影装置であって、
    　前記虚像の結像位置は、前記第１画像光のほうが前記第２画像光よりも視点位置から遠いことを特徴とする画像投影装置。      7. The image projection device according to claim 1,
    An image projection device, characterized in that the imaging position of the virtual image is farther from a viewpoint position for the first image light than for the second image light.
PCT/JP2024/007744 2023-03-10 2024-03-01 Image projection device WO2024190458A1 (en)

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JP2010528323A (en) * 2007-05-09 2010-08-19 リアルディー インコーポレイテッド Polarization conversion system and method for stereoscopic projection
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