WO2023188720A1 - 光学系及びそれを備えたヘッドアップディスプレイシステム - Google Patents

光学系及びそれを備えたヘッドアップディスプレイシステム Download PDF

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Publication number
WO2023188720A1
WO2023188720A1 PCT/JP2023/001538 JP2023001538W WO2023188720A1 WO 2023188720 A1 WO2023188720 A1 WO 2023188720A1 JP 2023001538 W JP2023001538 W JP 2023001538W WO 2023188720 A1 WO2023188720 A1 WO 2023188720A1
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WIPO (PCT)
Prior art keywords
region
expansion
light
optical system
amount
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
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PCT/JP2023/001538
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English (en)
French (fr)
Japanese (ja)
Inventor
享 橋谷
聡 葛原
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to JP2024511282A priority Critical patent/JPWO2023188720A1/ja
Publication of WO2023188720A1 publication Critical patent/WO2023188720A1/ja
Priority to US18/899,123 priority patent/US20250020916A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60J—WINDOWS, WINDSCREENS, NON-FIXED ROOFS, DOORS, OR SIMILAR DEVICES FOR VEHICLES; REMOVABLE EXTERNAL PROTECTIVE COVERINGS SPECIALLY ADAPTED FOR VEHICLES
    • B60J1/00—Windows; Windscreens; Accessories therefor
    • B60J1/02—Windows; Windscreens; Accessories therefor arranged at the vehicle front, e.g. structure of the glazing, mounting of the glazing
    • 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
    • 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
    • B60K35/22—Display screens
    • 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]
    • 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]
    • B60K35/232—Head-up displays [HUD] controlling the projection distance of virtual images depending on the condition of the vehicle or the driver
    • 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
    • B60K35/50—Instruments characterised by their means of attachment to or integration in the vehicle
    • 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
    • B60K35/80—Arrangements for controlling instruments
    • 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
    • B60K37/00—Dashboards
    • 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
    • G02B27/0081—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for altering, e.g. enlarging, the entrance or exit pupil
    • 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
    • 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
    • G02B27/0101—Head-up displays characterised by optical features
    • 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
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • 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
    • G02B27/02—Viewing or reading apparatus
    • 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
    • G02B27/10—Beam splitting or combining systems
    • G02B27/106—Beam splitting or combining systems for splitting or combining a plurality of identical beams or images, e.g. image replication
    • 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
    • G02B27/10—Beam splitting or combining systems
    • G02B27/1086—Beam splitting or combining systems operating by diffraction only
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • 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
    • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
    • B60K2360/20—Optical features of instruments
    • B60K2360/23—Optical features of instruments using reflectors
    • 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
    • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
    • B60K2360/77—Instrument locations other than the dashboard
    • B60K2360/785—Instrument locations other than the dashboard on or in relation to the windshield or windows
    • 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
    • B60K35/28—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor characterised by the type of the output information, e.g. video entertainment or vehicle dynamics information; characterised by the purpose of the output information, e.g. for attracting the attention of the driver
    • 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
    • B60K35/60—Instruments characterised by their location or relative disposition in or on vehicles

Definitions

  • the present disclosure relates to an optical system used for displaying images and a head-up display system equipped with the same.
  • a vehicle information projection system that performs augmented reality (AR) display using a head-up display device has been disclosed.
  • a head-up display device projects light representing a virtual image onto the windshield of a vehicle, thereby allowing the driver to view the virtual image along with the actual scene outside the vehicle.
  • Patent Document 1 describes an optical system including a waveguide (light guide) for expanding an exit pupil in two directions.
  • the optical system can expand the exit pupil using a diffractive optical element.
  • Document 2 describes a head-mounted display in which the amount of light diffracted from the diffraction grating is kept constant by modulating the height and duty ratio of the diffraction grating.
  • the present disclosure provides an optical system and a head-up display system that prevent image chipping and improve luminous flux utilization efficiency.
  • the optical system of the present disclosure is an optical system that allows an observer to visually recognize an image, and divides and reproduces a light beam traveling in a first direction into a light beam traveling in a second direction intersecting the first direction.
  • the first extension region has a center region including the center of the first extension region, and an end region on at least one of the end sides of the first extension region, in which the amount of diffracted light is smaller than half of the amount of diffracted light in the center region.
  • a head-up display system of the present disclosure includes the above-mentioned optical system, a display unit that emits a luminous flux before being expanded to the optical system, and a transparent member that reflects the luminous flux emitted from the optical system, An image is displayed as a virtual image superimposed on a real scene that is visible through a transparent member.
  • optical system and head-up display system of the present disclosure it is possible to provide an optical system and a head-up display system that prevent image chipping and improve the efficiency of using light flux.
  • FIG. 1 is a schematic diagram showing the configuration of the light guide 13.
  • a so-called pupil expansion type light guide 13 is used.
  • the pupil-expanding light guide 13 includes a coupling region 21 that receives image light from the display unit 11 and changes the traveling direction, a first expansion region 23 that expands in a first direction, and a first expansion region 23 that expands in a second direction. and a second expansion area 25 that expands.
  • the first direction and the second direction may intersect with each other, for example, may be perpendicular to each other.
  • the coupling region 21, the first extension region 23, and the second extension region 25 each have a diffraction power to diffract image light, and a diffraction structure element such as an embossed hologram or a volume hologram is formed therein.
  • the embossed hologram is, for example, a diffraction grating.
  • a volume hologram is, for example, a periodic refractive index distribution within a dielectric film.
  • the coupling region 21 changes the traveling direction of the image light incident from the outside so that it goes toward the first extension region 23 using diffraction power.
  • a diffraction structure element is disposed in the first expansion area 23, and the incident image light is divided into image light that travels in the first direction and image light that travels to the second expansion area 25 by diffraction power.
  • the image light is duplicated.
  • the diffraction structure elements are arranged at four points 23p lined up in the direction in which the image light travels through repeated total reflection.
  • the diffraction structure element splits the image light at each point 23p, and causes the split image light to proceed to the second expansion region 25.
  • the incident image light beam is expanded by being duplicated into four image light beams in the first direction.
  • the second extension region 25 is provided with, for example, a diffraction structure element, and converts the incident image light into image light that travels in the second direction due to diffraction power and image light that exits from the second extension region 25 to the outside. Duplicate the image light by dividing it into For example, in FIG. 1, three points 25p are arranged in each row in the direction in which the image light travels through repeated total reflection in the second expansion region 25, and a total of 12 points 25p in four rows each have a diffraction structure. elements are arranged. The image light is divided at each point 25p, and the divided image light is emitted to the outside. As a result, the image light beams incident in four rows are each expanded by being duplicated into three image light beams in the second direction.
  • the light guide 13 can replicate 12 image light beams from one incident image light beam, and duplicate the light beams in the first direction and the second direction.
  • the viewing area can be expanded by The observer can visually recognize each of the 12 image light beams as a virtual image, and the viewing area in which the observer can visually recognize the image light can be widened.
  • FIG. 2 is an explanatory diagram showing incident light and outgoing light of the HMD.
  • FIG. 3 is an explanatory diagram showing incident light and outgoing light of the HUD.
  • the light guide 13 in the HMD is approximately directly facing the viewing area Ac where the viewer can view the virtual image.
  • the image light vertically incident from the display section 11 is divided within the light guide 13, and the divided image light is vertically emitted from the output surface 27 of the light guide 13 toward the viewing area Ac.
  • the image light emitted from the light guide 13 is reflected by the windshield 5 and enters the viewing area Ac, so the divided image light is guided.
  • the light is emitted from the light emitting surface 27 of the light body 13 in an oblique direction.
  • the optical system for the HUD will be described below.
  • FIG. 4 is a diagram showing a cross section of a vehicle 3 equipped with a HUD system 1 according to the present disclosure.
  • FIG. 5 is an explanatory diagram showing the optical path of the light beam emitted from the display section.
  • a HUD system 1 mounted on a vehicle 3 will be described as an example.
  • the Z1-axis direction is a direction in which the observer visually recognizes the virtual image Iv from the viewing area Ac where the observer can visually recognize the virtual image Iv.
  • the X1-axis direction is a horizontal direction orthogonal to the Z1-axis.
  • the Y1-axis direction is a direction perpendicular to the X1Z1 plane formed by the X1-axis and the Z1-axis. Therefore, the X1-axis direction corresponds to the horizontal direction of the vehicle 3, the Y1-axis direction corresponds to the substantially vertical direction of the vehicle 3, and the Z1-axis direction corresponds to the substantially forward direction of the vehicle 3.
  • a display section 11 and a light guide 13 are arranged inside a dashboard (not shown) below the windshield 5 of the vehicle 3.
  • An observer D sitting in the driver's seat of the vehicle 3 recognizes the image projected from the HUD system 1 as a virtual image Iv.
  • the HUD system 1 displays the virtual image Iv superimposed on the real scene visible through the windshield 5. Since the plurality of duplicated images are projected onto the viewing area Ac, the virtual image Iv can be viewed even if the eye position of the observer D shifts in the Y-axis direction and the X-axis direction within the viewing area Ac. I can do it.
  • the observer D is a passenger riding in a moving object like the vehicle 3, and is, for example, a driver or a passenger sitting in a passenger seat.
  • the HUD system 1 includes a display section 11, a light guide 13, a control section 15, and a windshield 5.
  • the display unit 11 emits a light beam L1 that forms an image that is visually recognized by an observer as a virtual image Iv.
  • the light guide 13 divides and duplicates the light beam L1 emitted from the display section 11 and guides the duplicated light beam L4 to the windshield 5.
  • the luminous flux L4 reflected by the windshield 5 is displayed as a virtual image Iv, superimposed on the real scene visible through the windshield 5.
  • the display unit 11 emits a luminous flux before being expanded to the light guide 13, and displays an image under the control of, for example, an external control unit.
  • a liquid crystal display with a backlight an organic light-emitting diode display, a plasma display, or the like can be used.
  • an image may be generated using a screen that diffuses or reflects light, a projector, or a scanning laser.
  • the display unit 11 can display image content including various information such as a road progress guide display, the distance to the vehicle in front, the remaining battery level of the car, and the current vehicle speed. In this way, the display unit 11 emits the light beam L1 containing the image content that is visually recognized by the observer D as the virtual image Iv.
  • the control unit 15 can be realized by a circuit composed of semiconductor elements or the like.
  • the control unit 15 can be configured with, for example, a microcomputer, CPU, MPU, GPU, DSP, FPGA, or ASIC.
  • the control unit 15 implements predetermined functions by reading data and programs stored in the built-in storage device 17 and performing various arithmetic operations.
  • the storage device 17 is a storage medium that stores programs and data necessary to implement the functions of the control unit 15.
  • the storage device 17 can be realized by, for example, a hard disk (HDD), SSD, RAM, DRAM, ferroelectric memory, flash memory, magnetic disk, or a combination thereof.
  • the storage device 17 further stores a plurality of image data representing the virtual image Iv.
  • the control unit 15 determines the virtual image Iv to be displayed based on vehicle-related information acquired from the outside.
  • the control unit 15 reads out the image data of the determined virtual image Iv from the storage unit and outputs it to the display unit 11.
  • FIG. 6 is a transparent perspective view showing the configuration of the light guide 13.
  • the normal direction to the surface of the light guide 13 at the center or center of gravity of the first expansion region 23 is the Z-axis direction
  • the tangential plane is the XY plane.
  • the traveling direction of the central ray of light entering the first expansion region from the coupling region is the X-axis direction
  • the direction perpendicular to the X-axis direction is the Y-axis direction.
  • the light guide 13 has a first main surface 13a and a second main surface 13b, which are surfaces.
  • the first main surface 13a and the second main surface 13b face each other.
  • the light guide 13 has an entrance surface 20 , a coupling region 21 , a first extension region 23 , a second extension region 25 , and an exit surface 27 .
  • the entrance surface 20, the coupling region 21, the first extension region 23, and the second extension region 25 are included in the second main surface 13b, and the output surface 27 is included in the first main surface 13a. Therefore, the first expansion area 23 and the second expansion area 25 are arranged on the same plane.
  • the output surface 27 faces the second expansion region 25.
  • the coupling region 21, the first expansion region 23, and the second expansion region 25 may exist between the first main surface 13a and the second main surface 13b.
  • the first main surface 13a faces the windshield 5.
  • the incident surface 20 is included in the coupling region 21, but it may be a surface facing the coupling region 21 and included in the first main surface 13a.
  • the output surface 27 may be included in the second expansion region 25.
  • the coupling region 21, the first extension region 23, and the second extension region 25 have different diffraction powers, and each has a diffraction structure element formed therein.
  • the coupling region 21, the first extension region 23, and the second extension region 25 each have a different diffraction angle of image light.
  • the light guide 13 is configured such that the incident light beam is totally reflected inside. In this way, the light guide 13 partially includes a diffraction structure element, such as a volume hologram, that diffracts light.
  • the combined region 21, the first expansion region 23, and the second expansion region 25 become three-dimensional regions when they include a volume hologram.
  • the coupling region 21 is a region where the light beam L1 emitted from the display section 11 enters from the entrance surface 20 and changes the traveling direction of the light beam L1.
  • the coupling region 21 has diffraction power, changes the propagation direction of the incident light beam L1 to the direction of the first extension region 23, and emits it as a light beam L2.
  • coupling is a state in which light propagates within the light guide 13 under total internal reflection conditions.
  • the first expansion region 23 extends the light beam L2 in a first direction corresponding to the horizontal direction of the virtual image Iv, and is located in a second direction ( ⁇ Y-axis direction) that intersects the first direction (X-axis direction). The light is emitted to the second expansion area.
  • the length in the first direction is larger than the length in the second direction.
  • the light guide 13 is arranged so that the first direction is the horizontal direction (the direction of the X1 axis), but the first direction is not limited to the horizontal direction. It doesn't have to match.
  • the light beam L2 propagated from the coupling region 21 is propagated in the first direction while repeating total reflection on the first main surface 13a and the second main surface 13b, and then reaches the first expansion region 23 formed on the second main surface 13b.
  • the light beam L2 is duplicated by the diffraction structure and output to the second extension region 25.
  • the second expansion region 25 expands the light beam L3 in a second direction corresponding to the vertical direction of the virtual image Iv, and outputs the expanded light beam L4 from the exit surface 27.
  • the second direction is, for example, perpendicular to the first direction.
  • the second direction of the light guide 13 is arranged in the Z1 axis direction.
  • the light beam L3 propagated from the first expansion region 23 is propagated in the second direction while repeating total reflection on the first main surface 13a and the second main surface 13b.
  • the diffraction structure of the expansion region 25 duplicates the light beam L3 and outputs it to the outside of the light guide 13 via the output surface 27.
  • the light guide 13 directs the light beam L1 whose traveling direction has been changed by entering the incident surface 20 in the horizontal direction (direction of the X1 axis) of the virtual image Iv that the observer D visually recognizes.
  • the light beam L4 is emitted from the output surface 27.
  • replicating an image in the horizontal direction is not limited to replicating only in a complete horizontal direction, but also includes replicating in a substantially horizontal direction.
  • copying an image in the vertical direction is not limited to copying only in a complete vertical direction, but also includes copying in a substantially vertical direction.
  • FIG. 7A is an explanatory diagram showing the optical path at the center of the luminous flux emitted from the display section.
  • FIG. 7(b) is an explanatory diagram showing the wave number vector given to the light beam by the diffraction grating in each region in FIG. 7(a).
  • the light beam L1 of the image light incident on the light guide 13 changes its propagation direction to the first expansion region 23, which expands the pupil in the horizontal direction (X-axis direction). change. Therefore, after the light beam L1 obliquely enters the coupling region 21, it is propagated in the direction of the first expansion region 23 as a light flux L2 under the action of the wave number vector k1 shown in FIG.
  • the light beam L2 that propagates to the first expansion region 23 extending in the first direction is duplicated with the light beam L2 propagating in the first direction by the diffraction structure formed in the first expansion region 23 while repeating total reflection.
  • the light beam L3 is divided into a light beam L3 whose propagation direction is changed to the second expansion region 25. At this time, the duplicated light beam L3 propagates in the direction of the second expansion region 25 under the action of the wave number vector k2 shown in FIG.
  • the light beam L3 whose propagation direction has been changed to the second extension region 25 extending along the negative direction of the Z1 axis as the second direction is propagated in the second direction by the diffraction structure formed in the second extension region 25. and a light beam L4 that is duplicated and exits from the second expansion region 25 to the outside of the light guide 13 via the exit surface 27.
  • the duplicated light beam L4 is propagated toward the exit surface 27 (see FIG. 6) under the action of the wave number vector k3 shown in FIG.
  • the first expansion region 23 includes a first end region 23a, a center region 23b, and a second end region 23c.
  • the first end region 23a and the second end region 23c are regions that do not overlap with the second expansion region 25 when viewed from the second direction. Therefore, the second expansion area 25 exists in the second direction of the center area 23b, and the area without the second expansion area 25 exists in the second direction of the first end area 23a and the second end area 23c. .
  • the size of the second expansion area 25 is determined in accordance with the size of the visible area Ac.
  • the luminous flux L1 that enters the coupling area 21 has an incident angle other than 0 degrees (normal incidence) and an inclination angle. This includes the incident light flux. If this luminous flux L1 with an incident angle other than 0 degrees is not guided to the second extension area 25, a portion of the virtual image Iv will be chipped in the viewing area Ac. Therefore, by making the length Lga of the first expansion region 23 in the first direction longer than the length Lgb of the second expansion region 25 in the first direction, it is possible to prevent the virtual image Iv from being chipped.
  • the center region 23b of the first expansion region 23 includes the center of the first expansion region 23 in the first direction, and is located between the first end region 23a and the second end region 23c.
  • the first end region 23a is the end region closer to the bonding region 21, and the second end region 23c is the end region farther from the bonding region 21.
  • the length of the first expansion region 23 in the first direction is Lga
  • the length of the first end region 23a in the first direction is Lgaa
  • the length of the center region 23b in the first direction is Lgab.
  • the length of the second end region 23c in the first direction is Lgac.
  • the first end region 23a is a region having a length of less than 1/4 from the end of the first expansion region 23 on the coupling region 21 side in the first direction
  • the second end region 23c is This is a region having a length less than 1/4 from the end of the first expansion region 23 on the opposite side to the coupling region 21 in the direction of .
  • expanding the luminous flux means increasing the number of luminous fluxes by dividing and duplicating the luminous flux and expanding the visible area Ac.
  • the first expansion area 23 expands the visibility area Ac in the horizontal direction
  • the second expansion area 25 expands the visibility area Ac in the vertical direction.
  • the light beam L2 traveling in the first direction from the coupling region 21 through the first extension region 23 includes a light beam L2a, a light beam L2b, and a light beam L2c.
  • the light beam L3 traveling in the second direction from the first expansion region 23 includes a light beam L3aa, a light beam L3ab, a light beam L3ac, a light beam L3ba, a light beam L3bb, a light beam L3bc, a light beam L3ca, and a light beam L3cb. , and a luminous flux L3cc.
  • a light beam L2a whose traveling direction has been changed from the component of the light beam L1 that is perpendicularly incident on the coupling region 21 travels in the first direction through the first extension region 23, and is divided and diffracted at the first end region 23a.
  • the light beam L3ab, the light beam L3aa divided and diffracted by the central region 23b, and the light beam L3ac divided and diffracted by the second end region 23c each travel in the second direction.
  • the light beam L3aa can travel into the second expansion region 25, the light beams L3ab and L3ac cannot travel into the second expansion region 25, resulting in a loss of light quantity.
  • the light beam L2b whose traveling direction has been changed from the component of the light beam L1 that is incident on the coupling region 21 at a positive angle, travels through the first expansion region 23 in the first direction, and travels through the first end region 23a.
  • a light beam L3bb that is divided and diffracted by the center region 23b, a light beam L3ba that is divided and diffracted by the second end region 23c, and a light beam L3bc that is divided and diffracted by the second end region 23c each proceed in the second direction. do.
  • the light beam L3bc travels into the second expansion region 25 to prevent the virtual image Iv from being chipped, but part of the light beam L3ba and the light beam L3bb cannot travel into the second expansion region 25, so the amount of light decreases. loss occurs.
  • the light beam L2c whose traveling direction has been changed from the component of the light beam L1 that is incident on the coupling region 21 at a negative angle, travels through the first extension region 23 in the first direction, and travels through the first end region 23a.
  • a luminous flux L3cb that is divided and diffracted at the central region 23b, a luminous flux L3ca that is divided and diffracted at the central region 23b, and a luminous flux L3cc that is divided and diffracted at the second end region 23c each proceed in the second direction. do.
  • the light beam L3cb travels into the second expansion region 25 to prevent the virtual image Iv from being chipped, but part of the light beam L3ca and the light beam L3cc cannot travel into the second expansion region 25, so the amount of light decreases. loss occurs.
  • the light beams L3bc and L3cb have a smaller number of diffractions within the second extension region 25 than the light beam L3aa, repeat total reflection within the light guide 13, and propagate with less loss of light quantity. Therefore, the luminous flux L3bc and the luminous flux L3cb have a larger light quantity than the luminous flux L3aa, which propagates while being divided by diffraction within the second extension region 25, and cause uneven brightness of the image light emitted from the second extension region 25.
  • the transition in the first direction of the amount of light diffracted from the first extension region 23 loss of the amount of light and uneven brightness are reduced while preventing image chipping. Specifically, the diffraction efficiency of the first end region 23a and the second end region 23c is modulated so that the amount of light beams L3ab, L3bb, L3ac, and L3cc becomes smaller.
  • the light flux emitted from the second expansion area 25 within the length Lgb of the second expansion area 25 in the first direction shown in FIG. 8(a) is visually recognized as shown in FIG. 8(b).
  • the horizontal viewing angle ⁇ is incident on the area Ac in the range of ⁇ .
  • the light beam L3aa is diffracted to generate a light beam L4aa
  • the light beam L3cb is diffracted to generate a light beam L4cb
  • the light beam L3bc is diffracted to generate a light beam L4bc.
  • These light beams L4aa, L4cb, and L4bc reach the viewing area Ac.
  • the light beams diffracted from the light beams L3ab, L3bb, L3ac, L3cc, L3ba, and L3ca that do not emit within the length Lgb of the second expansion region 25 in the first direction do not reach the viewing area Ac.
  • the windshield 5 is omitted for ease of understanding.
  • the second expansion region 25 extends in a region 41 and a region 41 extending in the positive direction (X-axis positive direction) and the negative direction (X-axis negative direction) of the first direction, respectively. 43 may be formed.
  • the HUD system 1 may include a light guide 13F in which an expansion area 45 having a second expansion area 25, areas 41, and 43 is arranged in a second direction of the first expansion area 23.
  • the light beams L4aa, L4cb, and L4bc reach the viewing area Ac.
  • the light diffracted from the light beams L3ab, L3bb, L3ac, and L3cc which are not emitted within the length Lgb in the first direction of the second extension region 25 of the light guide 13F, leaves the light guide 13F in the visible area. Ac is not reached.
  • the light beam L3ab is diffracted to generate a light beam L4ab
  • the light beam L3bb is diffracted to generate a light beam L4bb
  • the light beam L3ac is diffracted to generate a light beam L4ac
  • the light beam L3cc is diffracted to generate a light beam L4cc is generated.
  • the second expansion region 25 is an expansion region within a length Lgb that is incident within the viewing angle ⁇ in the range ⁇ .
  • FIG. 10 is a graph showing changes in the proportion of the amount of light to be diffracted when modulation of diffraction efficiency is not performed in the comparative example.
  • FIG. 11 is a graph showing modulation of the diffraction efficiency so that the change in the proportion of the amount of light diffracted in the comparative example becomes constant.
  • FIG. 12 is a graph showing changes in the modulation of diffraction efficiency and the ratio of the amount of diffracted light in the embodiment.
  • the ratio of the amount of light to be diffracted Lr1 is smaller at the first end where the number of diffractions is smaller. It is highest in the region 23a and decreases as the number of diffraction increases in the first direction. Therefore, this causes uneven brightness of the virtual image Iv.
  • the diffraction efficiency De2 is modulated in the first direction and gradually increased, so that the ratio Lr2 of the amount of light to be diffracted is adjusted to the number of diffraction times. It can be kept constant regardless of the However, in the present embodiment, since the length Lga of the first expansion region 23 in the first direction is longer than the length Lgb of the second expansion region 25 in the first direction, light amount loss and brightness may be reduced due to the above-mentioned reason. Unevenness occurs.
  • the diffraction efficiency is modulated as shown in FIG. 12.
  • the diffracted light amount ratio Lr3 gradually increases along the first direction, and the flat portion Lr3a has a light amount ratio Lr3 within a certain range Rc within a specific range of the number of diffraction times. has.
  • the certain range Rc in the flat portion Lr3a is within ⁇ 10% of the designed value Va of the proportion of the amount of light diffracted in the central region 23b.
  • the design value Va is a specific value designed based on the number of diffraction within the central region 23b. In this embodiment, the design value Va is approximately 13%.
  • the ratio Lr3 of the amount of light diffracted in the first end region 23a with a small number of diffraction times and the second end region 23c with a large number of diffraction times is changed from the light amount ratio Lr3 that is diffracted in the central region 23b.
  • the light amount ratio is set lower than Lr3.
  • the diffraction efficiency De3 in the first extension region 23 is increased as the number of diffraction increases, and when the number of diffraction exceeds a specific number, the diffraction efficiency De3 is decreased.
  • the diffraction efficiency De3 increases along the first direction from the first end region 23a to the center region 23b, and decreases along the first direction in the second end region 23c.
  • the amount Le of diffracted light within the first end region 23a and the second end region 23c of the first extension region 23 is smaller than half the amount Lc of diffracted light within the center region 23b of the first extension region 23. Therefore, the following conditional expression (4) holds true. Le ⁇ Lc/2...Equation (4)
  • the light amount of the light beam L3aa can be increased by the reduced light amount.
  • the loss of the amount of light at high viewing angles such as the light beam L3bb and the light beam L3cc
  • the amount of light of the light beam L3bc and the light beam L3cb and propagating them to the second expansion area 25C the occurrence of image chipping can be prevented. In addition to preventing this, it is possible to improve the brightness unevenness of the virtual image Iv.
  • FIG. 13 is a longitudinal cross-sectional view of the diffraction grating 31 arranged in the first expansion region 23. As shown in FIG. 13
  • a diffraction grating 31 that diffracts the incident light beam is arranged in the first expansion region 23 .
  • the diffraction grating 31 is, for example, a transparent resin layer, and is formed by nanoimprinting.
  • the diffraction grating 31 may be formed by stacking SiO 2 on the glass substrate 35 and performing dry etching. Note that a diffraction grating 31 is similarly arranged in the second expansion region 25 as well.
  • the diffraction grating 31 is periodically formed with a pitch P.
  • the diffraction grating 31 has structural characteristics determined by a height h from the surface, a width W, and a duty ratio Dr defined by width W/pitch P. Note that the diffraction grating 37 may have a slant angle.
  • the height h1 of the grating 31a in the first end region 23a and the second end region 23c of the first expansion region 23 is lower than the height h2 of the grating 31a in the central region 23b.
  • the absolute value of the difference between the duty ratio Dr1 of the diffraction gratings of the first end region 23a and the second end region 23c of the first expansion region 23 and 0.5 is the same as that of the central region 23b. It is larger than the absolute value of the difference between the duty ratio Dr2 of the diffraction grating and 0.5. Therefore, the following conditional expression (5) holds true.
  • the duty ratio Dr2 of the diffraction grating in the central region 23b is closer to 0.5 than the duty ratio Dr1 of the diffraction gratings in the first end region 23a and the second end region 23c.
  • the duty ratio Dr2 of the diffraction grating in the central region 23b is closer to 0.5 than the duty ratio Dr1 of the diffraction gratings in the first end region 23a and the second end region 23c.
  • the amount of light diffracted at the first end region 23a and the second end region 23c can be made smaller than the amount of light diffracted at the center region 23b. good.
  • FIG. 15A is an explanatory diagram showing the optical path of a light beam traveling through the first expansion area 23A and the second expansion area 25A of the light guide 13A in Modification 1 of the embodiment.
  • FIG. 15(b) is an explanatory diagram showing wave number vectors given to the light beam by the diffraction gratings of the coupling region 21 and each extension region 23A, 25A in FIG. 15(a).
  • the second expansion region 25A has a first end region 23Aa and a center region 23Ab.
  • the diffraction gratings of the first expansion region 23A and the second expansion region 25A are designed so that the wave number vector k5 due to the diffraction grating of the second expansion region 25A is slightly oblique. .
  • the sum of the wave number vector k1 of the coupling region 21, the wave number vector k4 of the first extension region 23A, and the wave number vector k5 of the second extension region 25A can be made zero.
  • the center of the second expansion region 25A in the first direction is aligned with the center of the first expansion region 23A in the first direction, as shown in FIG. 15(a).
  • the sizes of the first end region 23Aa and the center region 23Ab in the first expansion region 23A are larger than the sizes of the first end region 23a and the center region 23b of the first embodiment, and are expanded in the first direction. ing.
  • the second expansion region 25A By arranging the second expansion region 25A on the opposite side of the first expansion region 23A from the joint region 21 so as to overlap the first expansion region 23A when viewed from the second direction, the second expansion region 25A can be The edge space on the first direction side can be reduced.
  • FIG. 16 is a graph showing the modulation of the diffraction efficiency of the first extension region 23A and the change in the ratio of the amount of diffracted light in Modification 1 of the embodiment.
  • the light amount ratio Lr3A diffracted in the first end region 23Aa with a small number of diffraction times is set lower than the light amount ratio Lr3A diffracted in the center region 23Ab.
  • the diffraction efficiency De3A is increased as the number of diffraction increases.
  • the diffraction efficiency De3A is increased along the first direction from the first end region 23Aa to the center region 23Ab.
  • the amount of diffracted light Le within the first end region 23Aa of the first extension region 23A is smaller than half the amount of diffracted light Lc within the center region 23Ab of the first extension region 23.
  • FIG. 17A is an explanatory diagram showing the optical path of a light flux traveling through the first extension region 23B and the second extension region 25B of the light guide 13B in Modification 2 of the embodiment.
  • FIG. 17(b) is an explanatory diagram showing wave number vectors given to the light beam by the diffraction gratings of the coupling region 21 and each extension region 23B, 25B in FIG. 17(a).
  • the second expansion region 25B has a center region 23Bb and a second end region 23Bc.
  • the diffraction gratings of the first expansion region 23B and the second expansion region 25B are designed so that the wave number vector k7 of the diffraction grating of the second expansion region 25B is oblique.
  • the sum of the wave number vector k1 of the coupling region 21, the wave number vector k6 of the first extension region 23B, and the wave number vector k7 of the second extension region 25B can be made zero.
  • the center of the second expansion region 25B in the first direction is aligned with the center of the first expansion region 23B in the first direction, as shown in FIG. 17(a). Instead of being placed together, they can be placed on the bonding area 21 side.
  • the size of the center region 23Bb and the second end region 23Bc is larger than the size of the center region 23b and the second end region 23c of the first embodiment, and each Expanded.
  • the first expansion area 25B of the second expansion area 25B can be The space on the opposite edge can be reduced.
  • FIG. 18 is a graph showing the modulation of the diffraction efficiency of the first extension region 23B and the change in the ratio of the amount of light to be diffracted in Modification 2 of the embodiment.
  • the ratio Lr3B of the amount of light diffracted in the second end region 23Bc which has a large number of diffraction times, is made lower than the ratio Lr3B of the amount of light diffracted in the center region 23Bb.
  • the diffraction efficiency De3B is increased as the number of diffraction increases, and when a specific number of diffraction is exceeded, the diffraction efficiency De3B is decreased.
  • the diffraction efficiency De3B is increased along the first direction in the central region 23Bb and decreased along the first direction in the second end region 23Bc.
  • the amount Le of diffracted light within the second end region 23Bc of the first extension region 23B is smaller than half the amount Lc of diffracted light within the center region 23Bb of the first extension region 23B.
  • FIG. 19A is an explanatory diagram showing the optical path of a light beam traveling through the first extension region 23C and the second extension region 25C of the light guide 13C in Modification 3 of the embodiment.
  • FIG. 19(b) is an explanatory diagram showing wave number vectors given to the light beam by the diffraction gratings of the coupling region 21C and each extension region 23C, 25C in FIG. 19(a).
  • the first direction of the first expansion region 23C is the negative direction of the Y-axis
  • the second direction of the second expansion region 25C is the direction of the X-axis.
  • the light beam incident on the coupling region 21C is propagated in the direction in which the first extension region 23C is arranged under the action of the wave number vector k1 by the diffraction grating of the coupling region 21C.
  • the light flux propagating to the first extension region 23C is duplicated with the light flux propagating in the first direction due to the diffraction structure formed in the first extension region 23 while repeating total reflection, and is directed toward the second extension region 25C.
  • the beam is split into a light beam that changes its propagation direction.
  • the duplicated light flux is propagated in the direction in which the second expansion region 25C is arranged under the action of the wave number vector k9.
  • the light flux whose propagation direction has been changed toward the second extension region 25C is duplicated with the light flux propagating in the second direction due to the diffraction structure formed in the second extension region 25 and is guided from the second extension region 25C.
  • the light beam is divided into a light beam emitted to the outside of the light body 13C.
  • the duplicated light flux is emitted to the outside of the light guide 13C under the action of the wave number vector k10 by the diffraction grating of the second extension region 25C.
  • the light amount ratio Lr3C diffracted in the first end region 23Ca with a small number of diffraction times and the second end region 23Cc with a large number of diffraction times is calculated from the light amount ratio Lr3C diffracted in the central region 23b. also lower.
  • the diffraction efficiency De3C is increased as the number of diffraction increases, and when a specific number of diffraction is exceeded, the diffraction efficiency De3C is decreased. As shown in FIG.
  • the diffraction efficiency De3C increases along the first direction from the first end region 23Ca to the center region 23Cb, and decreases along the first direction in the second end region 23Cc.
  • the amount Le of diffracted light in the first end region 23Ca and the second end region 23Cc of the first extension region 23C is smaller than half the amount Lc of diffracted light in the center region 23Cb of the first extension region 23.
  • FIG. 21A is an explanatory diagram showing the optical path of a light beam traveling through the first extension region 23D and the second extension region 25D of the light guide 13D in Modification 4 of the embodiment.
  • FIG. 21(b) is an explanatory diagram showing wave number vectors given to the light beam by the diffraction gratings of the coupling region 21D and each extension region 23D, 25D in FIG. 21(a).
  • Modification 4 of the embodiment is an example in which Modification 1 and Modification 3 are combined.
  • the diffraction gratings in each of the first expansion area 23D and the second expansion area 25D are designed so that the wave number vector k12 due to the diffraction grating in the second expansion area 25D is oblique.
  • the sum of the wave number vector k8 of the coupling region 21D, the wave number vector k11 of the first extension region 23D, and the wave number vector k12 of the second extension region 25D can be made zero.
  • the center of the second expansion region 25D in the first direction is aligned with the center of the first expansion region 23D in the first direction, as shown in FIG. 21(a).
  • the sizes of the first end region 23Da and the center region 23Db in the first expansion region 23D are larger than the sizes of the first end region 23Ca and the center region 23Cb of Modification 3, and are expanded in the first direction. ing.
  • the second expansion region 25D By arranging the second expansion region 25D on the opposite side of the first expansion region 23D from the joint region 21D so as to overlap the first expansion region 23D when viewed from the second direction, the second expansion region 25D The edge space on the first direction side can be reduced.
  • FIG. 22 is a graph showing the modulation of the diffraction efficiency of the first extension region 23D and the change in the ratio of the amount of diffracted light in Modification 4 of the embodiment.
  • the ratio Lr3D of the amount of light diffracted in the first end region 23Da, where the number of diffractions is small, is set lower than the ratio Lr3D of the amount of light diffracted in the center region 23Db.
  • the diffraction efficiency De3D is increased as the number of diffraction increases.
  • the diffraction efficiency De3D is increased along the first direction from the first end region 23Da to the center region 23Db.
  • the amount Le of diffracted light within the first end region 23Da of the first extension region 23D is smaller than half the amount Lc of diffracted light within the center region 23Db of the first extension region 23.
  • FIG. 23A is an explanatory diagram showing the optical path of a light beam traveling through the first expansion area 23E and the second expansion area 25E of the light guide 13E in the fifth modification of the embodiment.
  • FIG. 23(b) is an explanatory diagram showing wave number vectors given to the light beam by the diffraction gratings of the coupling region 21E and each extension region 23E, 25E in FIG. 23(a).
  • Modification 5 of the embodiment is an example in which Modification 2 and Modification 3 are combined.
  • the diffraction gratings in each of the first expansion region 23E and the second expansion region 25E are designed so that the wave number vector k14 due to the diffraction grating in the second expansion region 25E is oblique.
  • the sum of the wave number vector k8 of the coupling region 21E, the wave number vector k13 of the first extension region 23E, and the wave number vector k14 of the second extension region 25E can be made zero.
  • the wave number vector k14 oblique instead of aligning the center of the second expansion region 25E in the first direction with the center of the first expansion region 23E in the first direction, It can be placed on the 21 side.
  • the size of the center region 23Eb and the second end region 23Ec is larger than the size of the center region 23b and the second end region 23c of the first embodiment, and the sizes thereof are opposite to the first direction. Expanded.
  • the first expansion region 25E By arranging the second expansion region 25E on the joint region 21 side with respect to the first expansion region 23E so as to overlap the first expansion region 23E when viewed from the second direction, the first expansion region 25E can be The space on the opposite edge can be reduced.
  • FIG. 24 is a graph showing the modulation of the diffraction efficiency of the first extended region 23E and the change in the ratio of the amount of light to be diffracted in Modification 5 of the embodiment.
  • the ratio Lr3E of the amount of light diffracted in the second end region 23Ec which has a large number of diffraction times, is made lower than the ratio Lr3E of the amount of light diffracted in the center region 23Eb.
  • the diffraction efficiency De3E is increased as the number of diffraction increases, and when a specific number of diffraction is exceeded, the diffraction efficiency De3E is decreased.
  • the diffraction efficiency De3E is increased along the first direction in the central region 23Eb and decreased along the first direction in the second end region 23Ec.
  • the amount Le of diffracted light within the second end region 23Ec of the first extended region 23E is smaller than half the amount Lc of diffracted light within the center region 23Eb of the first extended region 23E.
  • the light guide 13 as an optical system of the present disclosure is an optical system that allows the observer D to visually recognize the virtual image Iv.
  • the light guide 13 expands by dividing and duplicating the light beam L2 traveling in the first direction into a light beam L3 traveling in the second direction intersecting the first direction to increase the number of light beams.
  • the second expansion area 25 corresponds to the visible area Ac of the virtual image Iv.
  • the first expansion region 23 has a center region 23b including the center of the first expansion region 23 and at least one of the end sides of the first expansion region 23. It has at least one of an end region 23a and a second end region 23c.
  • the amount of diffracted light Le in the first end region 23a or the second end region 23c is smaller than half the amount of diffracted light Lc in the center region 23b of the first extension region 23, the first end region 23a or the second end region
  • the amount of light diffracted by the region 23c can be reduced, and the loss of the amount of light can be reduced.
  • the light beam diffracted by the first end region 23a or the second end region 23c and reaching the second extension region 25 has high brightness due to a small number of diffraction times, but the amount of light of this light beam can be reduced. Therefore, uneven brightness can be reduced.
  • the second expansion region 25 exists in the second direction of the center region 23b, and a region without the second expansion region 25 exists in the second direction of the first end region 23a and the second end region 23c. .
  • the area without the second expansion area 25 can reduce the transmission of light flux to the viewer D outside the viewing area Ac.
  • the light beams from the first end region 23a and the second end region 23c are diffracted in this extension region.
  • this diffraction is reduced, The amount of light that reaches the visible area Ac can be increased.
  • the length Lga of the first expansion region 23 in the first direction is longer than the length Lgb of the second expansion region 25 in the first direction. Therefore, it is possible to prevent the image from being chipped due to the light beam diffracted by the first end region 23a or the second end region 23c and reaching the second extension region 25.
  • the divided and duplicated light beam L2 is reflected by the windshield 5 to make the virtual image Iv visible to the observer D, but the present invention is not limited to this.
  • a combiner may be used instead of the windshield 5, and the divided and duplicated luminous flux L2 may be reflected by the combiner to allow the observer D to visually recognize the virtual image Iv.
  • the HUD system 1 is applied to a vehicle 3 such as an automobile.
  • the object to which the HUD system 1 is applied is not limited to the vehicle 3.
  • the object to which the HUD system 1 is applied may be, for example, a train, motorcycle, ship, or aircraft, or may be an amusement machine that does not involve movement.
  • the light beam from the display section 11 is reflected by a transparent curved plate serving as a light-transmitting member that reflects the light beam emitted from the display section 11 instead of the windshield 5.
  • the actual scene that can be viewed by the user through the transparent curved board may be an image displayed from another image display device.
  • the virtual image produced by the HUD system 1 may be displayed superimposed on a video displayed from another video display device.
  • any one of the windshield 5, the combiner, and the transparent curved plate may be employed as the light-transmitting member in the present disclosure.
  • the light guide 13 is used in the HUD system 1 that displays the virtual image Iv, but the invention is not limited thereto.
  • the light guide 13 may be used for HMD.
  • the light guide 13 is used in the HUD system 1 that displays the virtual image Iv, but the invention is not limited thereto.
  • the light guide 13 may be used in an image display system in which, for example, an observer directly observes the light beam emitted from the output surface 27 instead of viewing a virtual image through a light-transmitting member.
  • the observer is a person who directly views the image formed by the emitted light flux, and is therefore not limited to the passenger of the moving body.
  • the optical system of the present disclosure is an optical system that allows an observer to visually recognize an image, and divides and reproduces a light beam traveling in a first direction into a light beam traveling in a second direction intersecting the first direction.
  • the first expansion area has an amount of diffracted light that is less than half of the amount of diffracted light in the central area in at least one of the central area including the center of the first expansion area and the end side of the first expansion area. and a small end area.
  • the amount of diffracted light in at least one end region is smaller than half of the amount of diffracted light in the central region of the first extended region, the amount of light diffracted in the end region can be reduced, and loss in light amount can be reduced. I can do it. Furthermore, the light flux that is diffracted at the end region and reaches the second extension region has high brightness due to a small number of diffraction times, but since the amount of light of this light flux can be reduced, it is possible to reduce uneven brightness. can.
  • the second extension region exists in the second direction of the central region, and the region without the second extension region exists in the second direction of the end region.
  • the area without the second expansion area can reduce the transmission of light flux to the viewer outside the viewing area, and the area other than the second expansion area where the light flux from the end area does not reach the viewing area. It is possible to reduce the amount of light that reaches the visible area and increase the amount of light that reaches the visible area.
  • the length of the first extension region in the first direction is longer than the length of the second extension region in the first direction. Therefore, it is possible to prevent the image from being chipped due to the light beam diffracted at the end region and reaching the second extension region.
  • the second expansion area In any one of the optical systems (1) to (3), in the transition of the ratio of the amount of diffracted light along the first direction in the first expansion area, the second expansion area
  • any one of the optical systems (1) to (4) within the end region of the first expansion region, from the end opposite to the center region side in the end region to the center of the first expansion region.
  • the amount of diffracted light increases toward the area.
  • the amount of diffracted light increases toward the center region within the end region of the first expansion region, so the amount of light diffracted at the end within the end region can be reduced, reducing loss of light amount. be able to.
  • the central area of the first expansion area is an area with a length of 1/4 or more and 3/4 or less from the end in the first direction.
  • the end region is a region having a length less than 1/4 from the end in the first direction.
  • the optical system of any one of (1) to (5) includes a coupling region that changes the traveling direction of the incident light beam toward the first expansion region, and the end region of the first expansion region is This is the area closer to the bond area.
  • the optical system of any one of (1) to (6) includes a coupling region that changes the traveling direction of the incident light beam toward the first expansion region, and the end region of the first expansion region is This is the area farthest from the bond area.
  • the first extension region has a diffraction grating, and the height of the diffraction grating in the end region of the first extension region is higher than that of the center region. lower than the height of the diffraction grating. Thereby, the diffraction efficiency of the first extension region can be modulated to a desired transition.
  • the first extension region has a diffraction grating, and the duty ratio of the diffraction grating in the end region of the first extension region is equal to or less than 0. 5 is larger than the difference between the duty ratio value of the diffraction grating in the central region and 0.5. Thereby, the diffraction efficiency of the first extension region can be modulated to a desired transition.
  • the first extension region has a diffraction grating, and the duty ratio of the diffraction grating in the end region of the first extension region is equal to or less than 0. 5 is different from the difference between the duty ratio value of the diffraction grating in the central region and 0.5, and the difference between the height of the diffraction grating in the end region of the first expansion region and the height of the diffraction grating in the central region is different from the difference between the duty ratio value of the diffraction grating in the central region and 0.5. different.
  • the diffraction efficiency of the first extension region can be modulated to a desired transition.
  • the head-up display system of the present disclosure includes any one of the optical systems (1) to (11), a display unit that emits a luminous flux before being expanded to the optical system, and a luminous flux emitted from the optical system. and a transparent member that reflects the image, and displays the image as a virtual image superimposed on a real scene that is visible through the transparent member.
  • the light-transmitting member is a windshield of a moving body.
  • the present disclosure is applicable to optical systems and head-up display systems that reproduce and display images.

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PCT/JP2023/001538 2022-03-31 2023-01-19 光学系及びそれを備えたヘッドアップディスプレイシステム Ceased WO2023188720A1 (ja)

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JP2015049376A (ja) * 2013-09-02 2015-03-16 セイコーエプソン株式会社 光学デバイス及び画像表示装置
US20170363871A1 (en) * 2016-06-20 2017-12-21 Tuomas Vallius Extended field of view in near-eye display using optically stitched imaging
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