JP2016122041A - Head-up display device - Google Patents

Abstract

Provided is a head-up display device in which an observer using polarized sunglasses can visually recognize a virtual image without causing unnecessary stray light and deterioration of video quality. SOLUTION: In a light path of display light from a liquid crystal display element 14 to a transparent reflection member 11, a transmission / reflection member 40 and a reflection type polarization separation property that reflects one polarized light and transmits the other polarized light. A polarizing optical member 41, the transmission / reflection member is perpendicular to the optical path of the display light, and the polarization separation layer of the polarizing optical member is inclined, and the polarization direction of the image displayed by the transparent reflection member Is other than horizontal. [Selection] Figure 2

Description

  The present invention relates to a head-up display device that displays an image (virtual image).

  So far, various head-up display devices that display an image on a windshield or the like of a vehicle have been proposed (for example, Patent Document 1). In the head-up display device described in Patent Document 1, a polarizing member is attached to the rear surface of a transmissive reflecting member that transmits display light emitted from the liquid crystal display panel and reflects infrared rays, and the transmissive reflecting member is a liquid crystal display panel. Are spaced apart from the front side of the liquid crystal display panel (the direction in which the display light travels) in a state that is not parallel to the liquid crystal display panel. The head-up display device includes a transparent reflecting member (a windshield or a combiner), and displays the display light reflected by the transparent reflecting member as an image (virtual image).

  In a head-up display device using a liquid crystal display panel, sunlight (external light) often enters the device, and the liquid crystal display panel is also exposed. In general, an absorption polarizing plate having protective layers made of triacetyl cellulose (TAC) on both sides of polyvinyl alcohol (PVA) containing a substance exhibiting polarization separation is used on the front surface of the liquid crystal display panel. However, there is a problem that the front-side absorption polarizing plate is melted by sunlight. In order to solve this problem, in Patent Document 1, the above-described transmissive reflecting member is arranged.

Japanese Patent No. 4788882

  By the way, the transmission / reflection member is formed by laminating dielectrics so as to transmit visible light and reflect infrared light which is a heat generation factor. However, the polarization dependency varies depending on the incident direction and the incident angle. There is. Therefore, when the polarization direction of the display light reflected by the transparent reflecting member is set to other than horizontal, assuming that the vehicle driver wears polarized sunglasses, in order to avoid deterioration of the image quality, the transmitting / reflecting member is set to display light. It was necessary to rotate the uniaxially in the direction parallel to or perpendicular to the polarization direction. When the transmission / reflection member is used as described above, there is a problem that a further problem relating to the image quality such as generation of unnecessary stray light occurs due to a design limitation.

  The present invention has been made in view of the above points, and provides a head-up display device that allows an observer using polarized sunglasses to visually recognize a virtual image without causing unnecessary stray light and lowering image quality. With the goal.

  As a result of intensive studies, the inventors of the present invention have used a polarizing optical member having a reflective polarization separation property, and arranged the polarization direction of the image and the transmission / reflection member and the polarization separation layer of the polarizing optical member with respect to the optical path of the display light. It has been found that by optimizing the direction, it is possible to provide a head-up display device in which an observer using polarized sunglasses can visually recognize a virtual image without causing generation of unnecessary stray light and deterioration of image quality. That is, the present invention is as follows.

  The present invention is a head-up display device that has a liquid crystal display element that emits display light and displays the image by projecting the display light onto a transparent reflecting member, and displays from the liquid crystal display element to the transparent reflecting member In the optical path of light, a transmission / reflection member and a polarizing optical member having a reflective polarization separation property of reflecting one polarized light and transmitting the other polarized light are arranged to transmit the display light, The transmission / reflection member is perpendicular to the optical path of the display light, and the polarization separation layer of the polarization optical member is inclined, and the polarization direction of the image displayed by the transparent reflection member is other than horizontal. Features.

  In the present invention, the polarizing optical member is composed of a reflective polarizing plate having a specific polarization axis, and the polarization separation layer of the polarizing optical member is rotated in a multiaxial direction parallel to and orthogonal to the polarization direction of the display light. It is preferable that they are arranged.

  In the present invention, the polarizing optical member has a wire grid layer made of a conductor extending in a predetermined direction at an interval of 150 nm or less on one surface of a flat glass substrate. It is preferable that the resin is filled.

  According to the present invention, a vehicle driver wearing polarized sunglasses can view a high-quality image, and a highly durable head-up display device can be obtained.

It is a conceptual diagram which shows an example of the optical path until the display light which the head-up display apparatus of this Embodiment emits is visually recognized. It is a cross-sectional schematic diagram which shows the head-up display apparatus which concerns on this Embodiment.

  Hereinafter, an embodiment of an image display system of the present invention (hereinafter abbreviated as “embodiment”) will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. Further, as a technical common sense, “linearly polarized light” includes not only perfect linearly polarized light but also slightly elliptical polarized light. In the present invention, elliptically polarized light having a minor axis length of 0.3 or less with respect to the major axis length of the ellipse is regarded as linearly polarized light having the major axis direction as the vibration direction. More preferably, it is elliptically polarized light having a minor axis length of 0.1 or less with respect to the major axis length of the ellipse. Similarly, when a plurality of linearly polarized lights are included, the highest intensity linearly polarized light is used as the linearly polarized light of the present invention.

  As shown in FIG. 1, the head-up display device 1 is provided on a dashboard 2 of a vehicle, for example, and projects a display light (video light) 3 onto a windshield 4 to display driving information as a virtual image 5. Device. The driver 6 can visually recognize the virtual image 5 superimposed on the scenery through the windshield 4.

  As shown in FIG. 2, the head-up display device 1 provided on the dashboard includes at least a liquid crystal display element 14 that emits display light, a transmission / reflection member 40, and a polarization optical member 41. The liquid crystal display element 14 includes a liquid crystal display panel 20, a polarizing plate (not shown), a backlight unit (including the light source 21), and the like.

  As shown in FIG. 2, a transmission / reflection member 40 and a polarizing optical member 41 are arranged in the optical path of display light from the liquid crystal display element 14 to the transparent reflection member (projection plate) 11. In addition, as a transparent reflection member, a combiner can be illustrated other than the windshield 4 of a motor vehicle.

  As shown in FIG. 2, the transmission / reflection member 40 is arranged perpendicular to the optical path of the display light. The transmission / reflection member 40 is manufactured by laminating dielectrics so as to transmit visible light and reflect infrared light that is a heat generation factor. Here, the optical path to the transmission / reflection member 40 is parallel to the second display light L2 until the first display light L1 guided from the liquid crystal display element 14 is reflected by the reflector 15 and reaches the aspherical mirror 16. It is an optical path. Thus, the transmission / reflection member 40 exists in the optical path of the display light, and is disposed so as to transmit the display light. Further, the polarization separation layer of the polarizing optical member is disposed so as to be inclined with respect to the optical path of the display light. The optical path to the polarization separation layer of the polarization optical member 41 is an optical path parallel to the second display light L2 shown in FIG.

  Since the polarizing optical member 41 has a reflective polarization separation property that reflects one polarized light and transmits the other polarized light, it is difficult to absorb sunlight and convert it into heat, and exhibits high durability. Moreover, it is preferable that the polarization optical member 41 has a specific polarization axis, and this can reduce the polarization dependency associated with the light incident direction and the light incident angle.

  When the polarized light separation layer having the reflective polarization separation property separates the incident sunlight and the like and reflects the light so as to travel in the reverse direction, it becomes stray light that can be visually recognized by the vehicle driver. In order to prevent such stray light, the polarization separation layer is inclined with respect to the optical path.

  Further, the polarization direction of the image displayed on the transparent reflecting member (projection plate such as the windshield 4 or the combiner) 11 may be other than horizontal so that the driver 6 of the vehicle wearing the polarized sunglasses can visually recognize the virtual image 5. It is effective. On the other hand, from the viewpoint of preventing stray light, it is preferable that the degree of freedom in design related to the direction of light reflected by the polarization separation layer can be widened. In this case, when the polarization separation layer has a specific polarization axis, it is not dependent on the polarization according to the light incident direction or the light incident angle, so that the setting range of the tilt direction or tilt angle of the polarization separation layer with respect to the optical path can be widened. . Therefore, the polarization separation layer of the polarization optical member 41 can be arranged so as to rotate in a multiaxial direction parallel to and orthogonal to the polarization direction of the display light. In this specification, “polarization axis” means a polarization transmission axis or a polarization reflection axis. Here, in the present specification and claims, “the polarization direction is other than horizontal” means that the linearly polarized light whose vibration direction of the electric field is parallel to the horizontal plane is a linearly polarized light having a vibration direction of 0 ° and is orthogonal to the horizontal plane. When linearly polarized light is linearly polarized light having a vibration direction of 90 °, it means linearly polarized light having a vibration direction of 1 to 90 °. Preferably, it refers to linearly polarized light having a vibration direction of 5 to 90 °, more preferably 10 to 90 °, and most preferably 20 to 90 °.

  Here, the intrinsic polarization axis includes a polarization transmission axis and a polarization reflection axis. If the polarization separation layer of the polarization optical member 41 can be rotated by these two axes (multi-axis), the direction of light that is separated by polarization and reflected can be freely controlled. Here, “rotation” will be described. For example, it is assumed that the polarization separation layer of the polarization optical member is on a predetermined plane, and the polarization transmission axis and the polarization reflection axis exist on this plane. Of these, first, when the polarizing optical member is rotated (tilted) with the polarization transmission axis as the center of rotation, it is rotated (tilted) in one axis. Further, when the polarization reflection axis is rotated (inclined) about the center of rotation, the rotation (inclination) is biaxial. Accordingly, the polarization separation layer can be tilted in all directions without depending on the polarization transmission axis and the polarization reflection axis, and as a result, the design for preventing the generation of stray light is facilitated. On the other hand, since a polarization separation layer such as a dielectric layer does not have a specific polarization axis, it includes part of the polarization axis regardless of how it is tilted, and undesirably reflected light is generated, resulting in reduced brightness. Cause a defect.

  Examples of the polarizing optical member 41 include a wire grid polarizer and a laminate film in which birefringent films having different birefringence are laminated. In particular, since the polarization separation layer is a single layer, polarization transmission and polarization reflection intensity change when the incident light angle changes is small, and wire-grid polarization that can separate and split broadband light from visible light to infrared light A child is preferred.

  The wire grid polarizer preferably has a wire grid layer made of a conductor extending in a predetermined direction at intervals of 150 nm or less on one surface of a flat glass substrate. Moreover, it is preferable that resin is filled between the conductors. The present embodiment is a head-up display device 1 used in a vehicle, and from the viewpoint of providing a highly durable polarizing optical member, a resin is filled between conductors (metal wires) of a wire grid layer as a polarization separation layer. However, it is preferable to prevent the conductor from being damaged by an external force or the like. On the other hand, when the metal wire is filled with resin without being in contact with air (refractive index 1.0), considering the influence of the refractive index of the resin, the period of the metal wire is set as the wavelength of the target light. It is preferable to set it to 1/4 or less. Therefore, when considering the use of light in the visible light region, the period of the metal wire is preferably 150 nm or less, more preferably the period of the metal wire is 130 nm or less, and most preferably The period is 100 nm or less.

  Here, as an example of a wire grid polarizer, a structure having a base material, a fine concavo-convex structure provided on the surface of the base material, and a metal wire formed on at least a convex portion of the fine concavo-convex structure (hereinafter, referred to as a “wire concavo-convex structure”) And a wire grid polarizing plate).

  The wire grid polarizing plate has a plurality of convex portions and a plurality of concave portions provided as a fine concavo-convex structure so as to continuously extend in the in-plane direction of the reference surface of the substrate.

  The substrate only needs to be substantially transparent in the target wavelength region, and a resin material is preferably used. By using a resin base material as the base material, there are merits such that a roll process is possible and the wire grid polarizing plate can have flexibility.

  Examples of the resin that can be used for the substrate include polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, cycloolefin resin (COP), cross-linked polyethylene resin, polyvinyl chloride resin, polyarylate resin, polyphenylene ether resin, modified Amorphous thermoplastic resins such as polyphenylene ether resin, polyetherimide resin, polyether sulfone resin, polysulfone resin, polyether ketone resin, polyethylene terephthalate (PET) resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, Crystalline thermoplastic resins such as polybutylene terephthalate resin, aromatic polyester resin, polyacetal resin, and polyamide resin, and ultraviolet rays such as acrylic, epoxy, and urethane ( Etc. V) curable resin or thermosetting resin. In addition, UV curable resins and thermosetting resins can be combined with the above thermoplastic resins and triacetate resins, or can be used alone to form a base material, and inorganic materials such as glass (for example, glass It is also possible to combine fillers). In order to cure the UV curable resin, it is possible to use a light source that emits UV light or a light source that emits an electron beam.

  A metal wire can be formed by selectively providing a metal film on the convex portion of the fine concavo-convex structure provided on the substrate. At this time, it is preferable to have a wire grid layer made of a metal wire (conductor) extending in a predetermined direction with an interval (period) of 150 nm or less. In general, the wire grid polarizing plate shows better polarization characteristics in a wider wavelength band as the period of the metal wire becomes smaller. When the metal wire is in contact with air (refractive index 1.0) and is not covered with an adhesive substance, it is practically sufficient to set the period of the metal wire to 1/3 or less of the wavelength of the target light. In the case where the metal wire is coated with an adhesive substance, the period of the metal wire is set to 1/4 of the wavelength of the target light in consideration of the influence of the refractive index of the adhesive substance. More preferably, it is as follows. Therefore, when considering the use of light in the visible light region, the period of the metal wire is preferably 150 nm or less as described above, and more preferably the period of the metal wire is 130 nm or less. Preferably, the period of the metal wire is 100 nm or less. In addition, the minimum of the period of a metal wire is 50 nm on a manufacturing process.

  Examples of the cross-sectional shape of the fine concavo-convex structure formed on the substrate surface include a trapezoidal shape, a rectangular shape, a rectangular shape, a prism shape, and a sine wave shape such as a semicircular shape. Here, the sinusoidal shape means having a curved portion formed by repetition of a concave portion and a convex portion. In addition, the curved part should just be a curved curve, for example, the shape with a constriction in a convex part is also included in a sine wave form. From the viewpoint of transmittance, the cross-sectional shape of the fine concavo-convex structure is preferably rectangular or sinusoidal.

  In addition, a base material is configured by combining a resin film such as an ultraviolet curable resin or a thermosetting resin and an inorganic base material such as glass (for example, a glass filler) or a resin base material such as a thermoplastic resin or a triacetate resin. May be. In this case, a fine concavo-convex structure having a predetermined cycle can be formed on the surface of the resin coating formed on the inorganic substrate or the resin substrate. From the viewpoint of obtaining a highly smooth surface with excellent specularity, the film thickness of the resin film is preferably 0.005 μm or more and 3 μm or less.

  The metal wire is formed on at least the convex portion of the fine concavo-convex structure. In this case, a metal wire extending continuously in a predetermined direction can be provided by depositing a metal partially on at least the side surface of the convex portion.

  The metal wire can be formed using a conductive material such as aluminum, silver, copper, platinum, gold, or an alloy containing each of these metals as a main component. In particular, the absorption loss in the visible region can be reduced by forming a metal wire using aluminum or silver.

  The period (pitch P) of the metal wire is as described above. In the cross-sectional view in the direction perpendicular to the direction in which the metal wire continuously extends, the duty ratio of the metal wire (the width of the metal wire and the metal wire) The ratio of the width of the metal wire to the sum of the widths of the portions having no gap is preferably 0.2 or more and 0.8 or less. The aspect ratio of the metal wire (ratio of the height of the metal wire to the width of the metal wire) is preferably 0.5 or more and 2.0 or less. Thereby, the total light transmittance can be improved. The width of the metal wire is the width at the midpoint in the height direction of the metal wire.

  There is no restriction | limiting in particular in the formation method of a metal wire. For example, a method of forming by mask patterning by electron beam lithography or interference exposure and dry etching, a method of forming by oblique deposition, and the like can be mentioned. Since it is necessary to form the metal wire very thinly, it is preferable to use an oblique vapor deposition method from the viewpoint of productivity.

  Further, from the viewpoint of optical characteristics, unnecessary portions of the metal wire may be removed by etching. The etching method is not particularly limited as long as the metal part can be selectively removed without adversely affecting the substrate and the dielectric layer described later, but a method of immersing in an alkaline aqueous solution is preferable from the viewpoint of productivity. . However, since the metal wire is formed very thin, the above etching removal is not essential.

  In order to improve the adhesion between the material constituting the substrate and the metal wire, a dielectric material having a high adhesion between them may be interposed therebetween. When the adhesion between the base material and the metal wire is high, peeling of the metal wire from the base material can be prevented, and a decrease in the degree of polarization can be suppressed.

  Examples of dielectrics that can be suitably used include silicon (Si) oxides, nitrides, halides, carbides, or composites thereof (dielectrics in which other elements, simple substances, or compounds are mixed in the dielectric alone). Body), aluminum (Al), chromium (Cr), yttrium (Y), zirconia (Zr), tantalum (Ta), titanium (Ti), barium (Ba), indium (In), tin (Sn), zinc (Zn), magnesium (Mg), calcium (Ca), cerium (Ce), copper (Cu) and other metal oxides, nitrides, halides, carbides alone or a composite thereof can be used. The dielectric material is preferably substantially transparent in a wavelength region where transmission polarization performance is to be obtained.

  There are no particular limitations on the method of laminating the dielectric material, and physical vapor deposition methods such as vacuum vapor deposition, sputtering, and ion plating can be suitably used.

  The present embodiment is, for example, a head-up display device 1 used in a vehicle, and from the viewpoint of providing a highly durable polarization optical member, a resin between metal wires (conductors) of a wire grid layer as a polarization separation layer is used. It is preferable to prevent the conductor from being damaged by external force or the like. The polarization separation layer is a layer including a metal wire (conductor).

  The resin filled between the conductors is not particularly limited, but is preferably substantially transparent in the target wavelength region. For example, as the resin, it is possible to use a UV curable resin that is cured by UV irradiation, a thermosetting resin that is cured by heat treatment, or a pressure sensitive adhesive sheet in the form of a pressure sensitive adhesive. In addition, although the same properties as the pressure-sensitive adhesive sheet are exhibited before the curing treatment, an adhesive substance such as an adhesive sheet that is cured by changing the crosslinking density by the curing treatment can also be used. In addition, it is preferable to use a material that does not contain an acid component as much as possible and hardly generates an acid component due to deterioration. By using a material that does not contain an acid component as much as possible, the possibility of deterioration of the conductor can be reduced. It should be noted that filling the resin between the conductors is sufficient if it is substantially filled, and does not deny the presence of air or the like.

The transmission / reflection member in the present embodiment is manufactured by laminating thin films such as dielectrics in a single layer or in multiple layers so that light having a predetermined wavelength can be transmitted and has a function of reflecting light having an unnecessary wavelength. Can do. Examples of the material of the transmission / reflection member include, but are not limited to, a material selected from the group consisting of ITO, TiO ₂ , ZnO, ZnS, SnO ₂ , Al, Al alloy, Ag, and Ag alloy.

  According to the head-up display device 1 of the present embodiment, a polarizing optical member having reflective polarization separation is used, and the polarization direction of the image and the transmission / reflection member with respect to the optical path of the display light, and the polarizing optical member By optimizing the arrangement direction of the polarization separation layer, an observer using polarized sunglasses can visually recognize a virtual image appropriately without causing generation of unnecessary stray light and deterioration of image quality.

  The head-up display device 1 can include a plane mirror, a curved aspherical mirror, and the like in the optical path in addition to the liquid crystal display element 14, the polarizing optical member, and the transmission / reflection member. In addition, a heat sink can be provided to cool a light source composed of an LED or the like.

  A more specific structure of the head-up display device 1 and the video display system 10 using the head-up display device 1 according to the present embodiment will be described with reference to FIG.

  The head-up display device 1 accommodates a liquid crystal display element 14, a reflector 15, a transmission / reflection member 40, a polarizing optical member 41, an aspherical mirror 16, and the like as a video display in a housing 17, and displays light (display light). A transparent window portion 18 for taking out L is provided in the housing 17.

  The display light L is emitted from the liquid crystal display element 14 and enters the reflector 15 until it is reflected by the first display light L1 and the reflector 15 and then enters the transparent reflecting member (projection plate) 11. Is the second display light L4 from the time it is reflected by the transparent reflecting member 11 until it enters the polarized sunglasses 44. In particular, when the aspherical mirror 16 is provided between the reflector 15 and the transparent reflecting member 11, the second display light L <b> 2 and the aspherical mirror 16 until the light enters the aspherical mirror 16 after being reflected by the reflector 15. The second display light L <b> 3 is from the time when the light is reflected to the time when the light enters the transparent reflecting member 11.

  The liquid crystal display element 14 emits linearly polarized first display light L1. The liquid crystal display element 14 includes a liquid crystal display panel 20, a light source 21, and a holding body 22 that holds the liquid crystal display panel 20 while accommodating the light source 21 therein.

  The liquid crystal display panel 20 is affixed to a liquid crystal cell 24 in which liquid crystal is sealed in a pair of translucent substrates on which a transparent electrode film is formed, and a light output side of the liquid crystal display panel 20, that is, a side opposite to the light source 21 of the liquid crystal cell 24. The first linearly polarizing plate 25 is attached, and the second linearly polarizing plate 26 is attached to the light source 21 side of the liquid crystal cell 24.

  The first linearly polarizing plate 25 preferably has a specific polarization axis, and is provided so as to polarization separate the light source light modulated by the liquid crystal cell 24 along this polarization axis.

  In order to align the polarization state of the light source light entering the liquid crystal cell 24, a second linearly polarizing plate 26 having a specific polarization axis may be provided. The second linear polarizing plate 26 is preferably a reflective polarizing plate. Since the light source light can be recycled, not only high brightness can be achieved, but also the generation of heat when external light collected by the aspherical mirror 16 enters the second linearly polarizing plate 26 can be prevented. The second linearly polarizing plate 26 can be inclined with respect to the liquid crystal cell 24 without being attached to the liquid crystal cell 24 of the liquid crystal display element 14, or can be in a curved shape. In the case of a curved shape, it is preferable to incline or curve in the polarization axis direction. Thereby, not only the image quality deterioration due to the multiple reflection of the external light but also the heat generated by the absorption of the light source light can be radiated.

  The light source 21 is not particularly limited, and one or more light emitting diodes that emit white light can be used. It should be noted that a reflector that reflects light is provided around the light source 21 to improve the light utilization rate, or a diffuser plate, a prism sheet, or the like is provided between the light source 21 and the liquid crystal display element 14 so as to be within the surface of the liquid crystal display element 14. The uniformity of the illuminance can be improved.

  The holding body 22 can have a mechanism for adjusting the installation direction of the liquid crystal display element 14 in the rotation direction with the first display light L1 as the rotation center axis. By adjusting the installation direction, the polarization state of the display light L1 can be adjusted by changing the direction of the polarization axis of the first linear polarizing plate 25. Note that the holding body 22 may include a driving unit that rotationally drives the liquid crystal display element 14, and the polarization state of the display light L1 may be adjusted by controlling the driving.

  The reflector 15 is supported on the inner surface of the housing 17 via a support member 27. The reflector 15 includes a reflecting surface 28, and the image display element 14 and the reflector 15 are arranged so that the first display light L 1 emitted from the liquid crystal display element 14 is incident on the reflecting surface 28 with an inclination. ing. Moreover, it is preferable to provide the heat sink (heat radiating member) 29 in the support member 27 located in the back surface of the reflector 15, for example, it is preferable that the said heat sink 29 is formed with a some heat radiating fin.

  The polarizing optical member 41 preferably has a reflective polarization separation property that reflects one polarized light and transmits the other polarized light, and preferably has a specific polarization axis. In order to prevent stray light, the polarization separation layer is preferably disposed so as to be inclined with respect to the optical path, and is preferably disposed so that the polarization direction of the image displayed by the transparent reflecting member 11 is other than horizontal. There are no restrictions on the optical characteristics and shape, and a reflective polarizing plate, a material obtained by sticking the reflective polarizing plate to a flat glass substrate, a curved shape, or the like can be suitably used.

  As described above, the transmission / reflection member 40 is manufactured by laminating dielectrics so as to transmit visible light and reflect infrared light serving as a heat generation factor. However, such a transmission / reflection member 40 has a polarization dependency that varies depending on the light incident direction and the light incident angle, and thus is preferably arranged so that the display light is incident on the front surface. In addition, since the light which reflects the said permeation | transmission reflection member 40 is infrared light, even if it remains in the optical path of display light, since it is not visually recognized, it does not become stray light. Therefore, the video quality is not deteriorated.

  On the other hand, in Patent Document 1, the transmission / reflection member is inclined with respect to the optical path of the display light. However, in such a case, the transmission / reflection member is not necessary due to design restrictions such as adjusting the transmission / reflection member parallel to the polarization direction of the display light. It was easy to generate stray light. On the other hand, in the present embodiment, since the transmissive reflection member 40 may be arranged perpendicular to the optical path of the display light, there is no design limitation, and generation of unnecessary stray light can be effectively suppressed. it can.

  In this embodiment, it is also possible to reversely arrange the transmission / reflection member 40 and the polarization optical member 41 shown in FIG.

  The aspherical mirror 16 is not particularly limited as long as it can reflect light of a predetermined wavelength. For example, a metal film mirror using aluminum, silver, copper, platinum, gold, or an alloy containing these metals as a main component is preferably used. Can be used. Further, the shape is not limited, and a flat plate shape can be used. However, in order to enlarge display light, it is preferable to have a curved shape such as a concave shape or a convex shape. The aspherical mirror 16 is an optical member used as necessary, and may be omitted if the second display light L2 emitted from the polarizing optical member 41 can be directly projected onto the transparent reflecting member (projection plate) 11. Good.

  The aspherical mirror 16 is supported via the angle adjustment unit 30. The angle adjustment unit 30 includes a support base 31 attached to the inner surface of the housing 17, a stepping motor 32 provided on the support base 31, a gear part 34 attached to the rotation shaft of the stepping motor 32, and the gear part. 34 and a gear portion 36 attached to the aspherical mirror 16 via a shaft portion 35. In the angle adjustment unit 30, by driving the stepping motor 32, the gear units 34 and 36 can be rotated to move the aspherical mirror 16 in the rotation direction, and the projection direction of the second display light L 3 on the windshield 4 can be changed. It is adjustable.

  The window portion 18 of the housing 17 has translucency, and the second display light L3 is transmitted through the window portion 18 and is reflected by the transparent reflecting member 11 to become the third display light L4. The driver (observer) 6 can observe the virtual image 5 by viewing the transparent reflecting member 11 with the third display light L4. A light shielding wall 38 is provided in the housing 17, and the light shielding wall 38 can prevent external light such as sunlight from entering and becoming stray light. A plurality of heat radiating fins 39 are provided on the outer peripheral surface of the housing 17.

  Next, the optical path of the display light L in the housing 17 will be described. Light (light source light) from the light source 21 enters the second linearly polarizing plate 26 of the liquid crystal display element 14, is polarized and separated, and linearly polarized light that vibrates in a predetermined direction is mainly polarized and transmitted. The light source light transmitted through the second linearly polarizing plate 26 is modulated by the liquid crystal cell 24 and then polarized and separated by the first linearly polarizing plate 25 to become the first display light L1. The first display light L1 enters the reflection surface 28 of the reflector 15 and becomes the second display light L2 reflected by the reflection surface 28. The second display light L2 is incident on the aspherical mirror 16 and then reflected to become the second display light L3. The second display light L3 is transmitted through the window 18 and reflected by the transparent reflecting member 11 to become the third display light L4. The driver 6 views the transparent reflecting member 11 and visually recognizes it as a virtual image 5. Can do.

  The first display light L1 is incident on the reflecting surface 28 of the reflector 15 in an inclined manner, and is polarized and reflected to become the second display light L2. Here, “tilted incident light” means incidence from a direction other than the vertical direction of the reflecting surface 28, but the angle θ1 of the first display light L1 with respect to the perpendicular P1 of the reflecting surface 28 is 10 to 80 °. The direction is preferable, and incidence from a direction of 20 to 70 ° is more preferable. In the structure of the present embodiment, the angle θ1 is preferably about 45 °. “Polarized reflection” means polarized light (second display light L2 in the present embodiment) that is reflected from the first display light L1 that has been polarized and separated by the reflector 15, and is transmitted after being polarized and separated. This is called polarized light transmission.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. Further, in the above-described embodiment, the size, shape, material, quantity, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. is there. In addition, the present invention can be appropriately modified and implemented without departing from the scope of the object of the present invention.

  The head-up display device of the present invention can be suitably used as a head-up display system for vehicles or for other uses.

DESCRIPTION OF SYMBOLS 1 Head-up display apparatus 3 L (L1-L4) Display light 4 Windshield 5 Virtual image 6 Driver 10 Image | video display system 11 Transparent reflective member 14 Liquid crystal display element 15 Reflector 16 Aspherical mirror 20 Liquid crystal display panel 21 Light source 40 Transflective member 41 Polarizing optical member 44 Polarized sunglasses

Claims (3)

A head-up display device having a liquid crystal display element that emits display light, and displaying the image by projecting the display light onto a transparent reflecting member,
In the optical path of the display light from the liquid crystal display element to the transparent reflecting member, a transmission reflecting member and a polarizing optical member having a reflective polarization separation property of reflecting one polarized light and transmitting the other polarized light Arranged to transmit the display light,
The transmission / reflection member is perpendicular to the optical path of the display light, and the polarization separation layer of the polarizing optical member is inclined,
A head-up display device, wherein a polarization direction of an image displayed by the transparent reflecting member is other than horizontal. The polarizing optical member comprises a reflective polarizing plate having a specific polarization axis,
2. The head-up display device according to claim 1, wherein the polarization separation layer of the polarization optical member is arranged to be rotated in a multiaxial manner in a direction parallel to and orthogonal to the polarization direction of the display light. The polarizing optical member has a wire grid layer made of a conductor extending in a predetermined direction at an interval of 150 nm or less on one surface of a flat glass substrate, and a resin is filled between the conductors. The head-up display device according to claim 2, wherein:

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