WO2013190959A1

WO2013190959A1 - Head-up display

Info

Publication number: WO2013190959A1
Application number: PCT/JP2013/064789
Authority: WO
Inventors: 和之栗原; 康宏池田; 寛坂本
Original assignee: 旭硝子株式会社
Priority date: 2012-06-22
Filing date: 2013-05-28
Publication date: 2013-12-27
Also published as: JPWO2013190959A1

Abstract

A head-up display is provided with a display means, a transparent member, and a reflection-type polarization element. The head-up display is also provided with a transparent screen capable of displaying a display image by reflecting display light emitted from the display means. The reflection-type polarization element is provided so as to be in contact with either the transparent member or a resin layer. The display light enters from a first surface of either the transparent member or the resin layer provided so as to be in contact with the reflection-type polarization element, said first surface being in contact with air. The display light is p-polarized light parallel with respect to an incidence plane. The reflection-type polarization element is disposed such that the reflection axis is parallel with the display-light polarization axis. If the Brewster's angle at the interface between the air and the material forming the first surface is θ_b1(on condition that θ_b1 is in the range of 0-90˚), the angle of incidence θ₁ on the first surface is substantially in the range θ_b1±20˚.

Description

Head-up display device

The present invention relates to a head-up display device.

Conventionally, a transparent screen capable of displaying a display image without blocking the scenery on the back side has attracted attention.

A typical example of the transparent screen is a head-up display device for moving means such as a vehicle or an aircraft.

For example, a head-up display device for a vehicle can image information such as the vehicle speed in the field of view in front of the driver (for example, Patent Document 1 and Patent Document 2). For this reason, the driver does not need to largely shift his / her line of sight from the front for information confirmation during driving of the vehicle, and safety during driving is improved.

Japanese Patent Laid-Open No. 2-141720 Japanese Utility Model Publication No. 3-59336

Generally, a head-up display device for a vehicle is composed of display means installed on a dashboard or the like in the vehicle, and a semi-transmissive and semi-reflective optical element called a combiner. By irradiating display light toward the combiner and reflecting the display light by the combiner, the driver can visually recognize a display image (virtual image) superimposed on the outside scene. The combiner is used in a form such as being enclosed in a windshield (laminated glass), affixed to the surface of the windshield on the driver side, or installed between the windshield and the driver.

However, in any configuration, part of the display light irradiated to the combiner is transmitted through the combiner and reflected to the driver side at an interface having a different refractive index, such as the surface on the side where the combiner contacts the outside. . For this reason, in the conventional head-up display device, in addition to the reflected light (display light) from the originally required combiner, reflected light from other interfaces also exists. Therefore, the conventional head-up display device has a problem that the display image becomes a double image and visibility is deteriorated.

Note that the above-mentioned Patent Document 1 discloses a measure for reducing the problem of such a double image. In the countermeasure described in Patent Document 1, a semi-transmission mirror and a retardation film are used as a combiner to change the polarized light incident on the surface of the windshield in contact with the outside world, thereby reducing the reflected light from the surface. Yes. However, in general, a retardation film sets a phase difference at a certain wavelength, so that the effect of suppressing double images is small, and it is difficult to apply to a head-up display device for color display. .

The present invention has been made in view of such a background, and the present invention provides a head-up display device that has versatility and can reduce visibility of double images and increase visibility. Objective.

According to one aspect, a transparent screen having a display means, a transparent member and a reflective polarizing element, and capable of displaying a display image by reflecting display light emitted from the display means; The reflective polarizing element is provided in contact with the transparent member or the resin layer, and the display light is in contact with air of the transparent member or the resin layer provided in contact with the reflective polarizing element. The display light is incident from the first surface, and the display light is P-polarized light parallel to the incident surface, and the reflective polarizing element is arranged so that the reflection axis is parallel to the polarization axis of the display light. The incident angle θ _{1 on} the first surface is defined as θ _B1 (where θ _b1 is 0 to 90 °) at the Brewster angle at the interface between air and the material constituting the first surface. In the range of θ _b1 ± 20 ° A head-up display device is provided.

In this embodiment, it is possible to provide a head-up display device capable of reducing the double image and improving the visibility.

It is the figure which showed schematically the structure of the conventional head-up display apparatus. It is the figure which showed schematically the structure of the wire grid type polarizing element as an example of a reflective polarizing element. It is a schematic diagram for demonstrating the optical characteristic at the time of the S-polarized light injecting into the wire grid type polarizing element shown in FIG. It is a schematic diagram for demonstrating the optical characteristic at the time of the P-polarized light injecting into the wire grid type polarizing element shown in FIG. It is the figure which showed schematically the structure of another wire grid type polarizing element. It is the graph which showed typically the influence which the incident angle (theta) of S polarized light and P polarized light has on reflectance (%). It is the figure which showed schematically the example of 1 structure of the transparent screen by this embodiment. It is the figure which showed schematically the example of another structure of the transparent screen by this embodiment. It is the figure which showed schematically the 3rd structural example of the transparent screen by this embodiment. It is the figure which showed schematically the example of a structure of the head-up display apparatus by this embodiment. It is the figure which showed schematically the example of another structure of the head-up display apparatus by this embodiment. It is the figure which showed schematically the 3rd structural example of the head-up display apparatus by this embodiment. 3 is a cross-sectional view schematically showing the structure of a transparent screen according to Example 1. FIG. 5 is a cross-sectional view schematically showing the structure of a transparent screen according to Comparative Example 1. FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and the following embodiments are not departed from the scope of the present invention. Various modifications and substitutions can be made.

First, in order to better understand the characteristics of the present embodiment, the configuration of a conventional transparent screen will be briefly described with reference to FIG. Here, a head-up display device for a vehicle is taken up as an example of the transparent screen, and the configuration thereof will be described.

FIG. 1 schematically shows a configuration of a conventional head-up display device for a vehicle.

As shown in FIG. 1, a conventional head-up display device 10 for a vehicle includes a windshield 20, a combiner 40 installed on at least a part of the windshield 20, or a display unit 45 such as a projector. And have. The display means 45 is usually installed in a part of or inside the dashboard 80 of the vehicle.

The windshield 20 has an inner surface (driver-side surface) 22 and an outer surface (external-side surface) 24. Further, the windshield 20 is usually configured by bonding a first glass substrate 30 and a second glass substrate 35 to each other via an intermediate film 39. In the example of FIG. 1, the first glass substrate 30 is on the inner surface 22 side of the windshield 20, and the second glass substrate 35 is on the outer surface 24 side.

The combiner 40 is formed of a metal layer such as a silver thin film, and is disposed on the first glass substrate 30 side, that is, on the inner surface 22 of the windshield 20.

The display means 45 is installed to emit display light 60 including a display image from the display means 45. The display light 60 emitted from the display means 45 is S-polarized light in a normal case.

Here, S-polarized light means polarized light in which the vibration direction of the electric field of light is perpendicular to the incident surface. (On the other hand, polarized light in which the vibration direction of the electric field of light is parallel to the incident surface is called P-polarized light.) Also, the “incident surface” means a plane including the optical paths of incident light and reflected light. To do.

Generally, the reason why the S-polarized light is used as the display light 60 is that the S-polarized light can reflect more light by the windshield 20 than the P-polarized light, and the display image becomes brighter.

When operating such a head-up display device 10, the display means 45 is activated, and the display light 60 including the display image is emitted from the display means 45. The display light 60 travels toward the combiner 40 installed on the inner surface 22 of the windshield 20. In this case, an optical element (not shown) such as a lens is arranged between the display means 45 and the windshield 20, thereby guiding the display light 60 toward the combiner 40. Or you may enlarge the magnitude | size of an image.

Next, the display light 60 enters the combiner 40 and is reflected here to become reflected light 65. The reflected light 65 is directed toward the driver 90, so that the driver 90 can visually recognize a display image (virtual image) superimposed on the outside scene in front of himself / herself.

However, in reality, not all of the display light 60 that reaches the combiner 40 becomes the reflected light 65, and a part of the display light 60 passes through the combiner 40 to the inner surface 22 of the windshield 20 to transmit the transmitted light. 70 and enters the inside of the windshield 20. Thereafter, the transmitted light 70 is reflected by, for example, the outer surface of the second glass substrate 35 constituting the windshield 20, that is, the outer surface 24 of the windshield 20, and becomes the second reflected light 75. It is emitted toward the driver 90 side.

As a result, both the reflected light 65 and the second reflected light 75 reach the driver 90 side, which causes a problem that the display image becomes a double image. More precisely, from other interfaces in the windshield 20 (for example, the interface between the first glass substrate 30 and the intermediate film 39 and the interface between the second glass substrate 35 and the intermediate film 39). Since reflection also occurs, the display image visually recognized by the driver 90 may be a multiple image that is more than a triple image.

Thus, the conventional head-up display device 10 has a problem in the visibility of the display image.

The inventors of the present application have made various studies in order to deal with such problems. As a result, by using a reflective polarizing element, by taking advantage of the characteristics of the Brewster angle theta _b, it found that a problem of double image as described above is eliminated or reduced, leading to the present invention.

That is, in the first embodiment,
A head-up display device having display means and a transparent screen capable of displaying a display image by reflecting display light emitted from the display means,
The transparent screen has a transparent member and a reflective polarizing element embedded in the transparent member,
In the transparent member, when two surfaces in contact with air are respectively the first surface and the second surface,
The display light is incident from the first surface;
The display light is P-polarized light parallel to the incident surface,
The reflective polarizing element is arranged such that the reflection axis is parallel to the polarization axis of the display light,
The incident angle θ _{1 at} the first surface is substantially equal to θ _b1 (where θ _b1 is 0 to 90 °) when the Brewster angle at the interface between air and the material forming the first surface is θ _b1. In the range of θ _b1 ± 20 °,
Of the display light, an incident angle θ ₂ on the second surface of transmitted light that travels in the transparent screen without being reflected by the reflective polarizing element is a material that constitutes the second surface. When the Brewster angle at the interface with air is θ _b2 (where θ _b2 is 0 to 90 °), a head-up display device substantially in the range of θ _b2 ± 20 ° is provided.

In the second embodiment,
A head-up display device having display means and a transparent screen capable of displaying a display image by reflecting display light emitted from the display means,
The transparent screen has a transparent member and a reflective polarizing element disposed on the surface of the transparent member,
In the transparent member, when two surfaces in contact with air are respectively the first surface and the second surface,
The display light is incident from the first surface;
The reflective polarizing element is disposed on the second surface;
The display light is P-polarized light parallel to the incident surface,
The reflective polarizing element is arranged such that the reflection axis is parallel to the polarization axis of the display light,
The incident angle θ ₁ of the display light on the first surface is the Brewster angle at the interface between the air and the material constituting the first surface, θ _b1 (where θ _b1 is 0 to 90 °). Then, a head-up display device substantially in the range of θ _b1 ± 20 ° is provided.

(Configuration and operation of reflective polarizing element)
Here, the configuration and operation of the reflective polarizing element used in the configuration of the present embodiment will be briefly described.

As the reflective polarizing element, a wire grid type polarizing element or two kinds of polymer layers having different high refractive index layers and low refractive index layers are made to have the same refractive index in one direction and different in refractive index in the other direction. Examples thereof include an optical film in which several hundred layers are arranged, and an optical element in which a cholesteric liquid crystal and a quarter-wave plate are combined.

An optical film in which two kinds of polymer layers having different high refractive index layers and low refractive index layers are arranged in several hundred layers so that the refractive indexes in one direction are completely matched and the refractive indexes in other directions are different. Used for brightness enhancement in display devices. When used for a transparent screen as in the present embodiment, it is desirable to further reduce the degree of polarization and improve the transmittance as compared with the prior art. Examples of such an optical film include DBEF manufactured by Sumitomo 3M Limited.

An optical element that combines a cholesteric liquid crystal and a quarter-wave plate is an incident light that is incident on a linearly polarized light, converted into circularly-polarized light by a quarter-wave plate, and selectively transmitted and reflected by the cholesteric liquid crystal. The polarized light is an element that passes through the quarter-wave plate again and is converted from circularly polarized light to linearly polarized light.

FIG. 2 shows a wire grid type polarization element as an example of the reflection type polarization element.

As shown in FIG. 2, the wire grid type polarization element 100 includes a transparent substrate 110 and a plurality of metal wires 130 installed on the transparent substrate 110. The transparent substrate 110 is made of, for example, a photocurable resin, a thermoplastic resin, or glass.

The metal wires 130 are arranged at equal intervals and in parallel with each other. For example, in the example of FIG. 2, each metal wire 130 is arranged at a pitch P so as to extend parallel to the Y direction. The pitch P is at least shorter than the wavelength of visible light (about 400 nm), and is about 100 nm to 200 nm, for example. For this reason, each metal wire 130 cannot be visually recognized visually.

In the following, the extending direction of the metal wire 130 is referred to as a reflection axis. The definition of “reflection axis” will be described later.

The wire grid type polarizing element 100 configured as described above operates as follows.

First, the case where S-polarized light is incident on the wire grid type polarizing element 100 as shown in FIG. 2 will be described. Here, as described above, S-polarized light means polarized light in which the vibration direction of the electric field of light is perpendicular to the incident surface.

In this case, there are roughly two types of optical characteristics as shown in FIG.

(A) When the polarization axis of the incident light 140S (the direction perpendicular to the paper surface of FIG. 3A) and the extending direction of the metal wire 130 of the wire grid type polarizing element 100, that is, the direction of the reflection axis, are parallel to each other. As shown in FIG. 3A, the light 140S is reflected to become reflected light 150a.

(B) On the other hand, when the polarization axis of the incident light 140S (the direction perpendicular to the paper surface of FIG. 3A) and the extending direction of the metal wire 130 of the wire grid type polarizing element 100, that is, the direction of the reflection axis, are perpendicular. As shown in FIG. 3B, the light 140S is transmitted to become transmitted light 150b.

Next, a case where P-polarized light is incident on the wire grid type polarizing element 100 will be described. Here, as described above, P-polarized light means polarized light in which the vibration direction of the electric field of light is parallel to the incident surface.

(C) When the polarization axis of incident light 140P (the direction parallel to the paper surface of FIG. 4A) and the extending direction of the metal wire 130 of the wire grid type polarizing element 100, that is, the direction of the reflection axis, are perpendicular to each other. As shown in FIG. 4A, the light 140P is transmitted to become transmitted light 150c.

(D) On the other hand, when the polarization axis of the incident light 140P (the direction parallel to the paper surface of FIG. 4A) and the extending direction of the metal wire 130 of the wire grid type polarizing element 100, that is, the direction of the reflection axis are parallel. As shown in FIG. 3B, the light 140P is reflected to become reflected light 150d.

As described above, the wire grid type polarizing element 100 has a feature that the optical characteristic of incident light can be changed by reflection / transmission according to the positional relationship between the reflection axis of the wire grid type polarization element 100 and the polarization axis of incident polarized light. .

In the example of FIG. 2, each metal wire 130 has a substantially quadrangular prism shape and is disposed on the flat surface 115 of the transparent substrate 110. However, the arrangement form of the metal wires is not limited to this.

FIG. 5 shows a wire grid type polarizing element 101 having another configuration.

In this wire grid type polarizing element 101, the transparent substrate 111 has protrusions 120 arranged at a pitch P along the X direction in FIG. Although not visible from FIG. 5, the protrusions 120 extend parallel to each other along the Y direction (direction perpendicular to the paper surface).

The protrusion 120 may be made of the same material as the transparent substrate 111, or may be made of a light transmissive material different from that of the transparent substrate 111. Examples of the material of the protrusion 120 include a photo-curing resin, a thermoplastic resin, and glass. The refractive index of the material constituting the protrusion 120 is preferably close to the refractive index of the material constituting the transparent substrate 111. Specifically, the refractive index difference (absolute value) is preferably 0.1 or less, and more preferably 0.05 or less. By doing so, it is possible to suppress light loss due to reflection occurring at the interface between the transparent substrate 111 and the protrusion 120.

The pitch P is the sum of the width T of the protrusion bottom and the width S of the protrusion bottom. The pitch P is preferably 100 to 140 nm. If the pitch P is 140 nm or less, the p-polarized light transmittance in the short wavelength region (450 nm or less) is further increased. Moreover, if the pitch P is 100 nm or more, it is easy to form fine metal wires. The width T of the bottom surface of the protrusion may be the same value as the pitch P, but is preferably 70% or less of the pitch P, and more preferably 60% or less of the pitch P. When the width T is smaller than the pitch P, the transmittance increases, and the angle dependency of the transmittance decreases. H represents the height of the protrusion. The height H of the protrusion is preferably 200 nm or less, and more preferably 150 nm or less. When the height H is 200 nm or less, creation by nanoimprint or the like becomes easy. L represents the height of the metal wire, and t represents the width of the metal wire. It is this metal wire portion that exhibits polarization separation characteristics in the wire grid polarization element. The width t is preferably 5 nm to 70 nm, and more preferably 5 nm to 60 nm. By setting the width t to 5 nm or more, it is possible to exhibit desired optical characteristics while suppressing deterioration of the metal film quality. By setting the width t to 70 nm or less, both the transmittance and the reflectance can be appropriately achieved as a transparent screen.

In addition, as described above, since the polarization separation characteristic is exhibited in the metal wire portion, it is possible to adopt a configuration using only the metal wire without a protrusion as shown in FIG.

Each metal wire 131 is disposed on the inclined surface of the corresponding protrusion 120 of the transparent substrate 111.

Also in the wire grid type polarizing element 101 having such a configuration, when the pitch P is sufficiently shorter than the wavelength of visible light, the same characteristics as those of the wire grid type polarizing element 100 shown in FIG. It will be apparent to those skilled in the art.

Furthermore, this feature is not limited to the wire grid type polarizing element 100, but is applicable to all reflective polarizing elements. That is, the same can be said based on the relationship between the reflection axis of the reflective polarizing element and the polarization axis of the incident light (polarization vibration direction).

Here, in the present embodiment, the “reflection axis” of the reflective polarizing element is determined as follows.

When light in a non-polarized state is incident on the reflective polarizing element, it is separated into two light beams, a transmitted light beam and a reflected light beam, in which the vibration direction of the electric field of the light is orthogonal. A direction parallel to the vibration direction of the reflected light is referred to as a reflection axis, and a direction parallel to the vibration direction of the transmitted light is referred to as a transmission axis.

The first and second inventions of the present embodiment have a feature that the reflection axis of the reflective polarizing element having such characteristics is arranged to be parallel to the polarization axis of the incident P-polarized light.

In this case, the optical characteristics of the incident light are in a reflection state as shown in FIG. 4B, and most of the incident light 140P can be reflected.

The wire grid type polarizing element having the above-mentioned characteristics is manufactured by, for example, preparing a resin grid substrate having a plurality of parallel fine grooves and forming a thin metal wire in the grooves. Can do.

The resin grid substrate can be formed by, for example, a nanoimprint (optical imprint, thermal imprint) process or the like. Alternatively, the resin grid substrate may be directly manufactured by interference exposure. On the other hand, the fine metal wire can be formed by using a general film forming technique such as vapor deposition or sputtering.

Alternatively, the wire grid type polarizing element is formed by, for example, forming a metal film on a substrate having a flat surface by using a general film forming technique such as a vapor deposition method and a sputtering method, and then photolithography the metal film. Or you may manufacture by patterning to a wire form using techniques, such as an electron beam drawing method.

In addition, a wire grid type polarizing element can be manufactured by various methods.

(About Brewster angle θ _b )
Next, referring to FIG. 6, it will be described Brewster angle theta _b.

FIG. 6 schematically shows the influence of the incident angle θ of S-polarized light and P-polarized light on the reflectance (%). As described above, S-polarized light refers to polarized light whose vibration direction of the electric field of light is perpendicular to the incident surface, and P-polarized light refers to polarized light whose vibration direction of the electric field of light is parallel to the incident surface. means. FIG. 6 assumes that S-polarized light or P-polarized light is incident from the air layer (first medium) toward the resin or glass layer (second medium).

6 that in the case of S-polarized light, the reflectance tends to increase almost monotonically as the incident angle θ increases.

On the other hand, in the case of P-polarized light, there is an incident angle θ at which the reflectance is almost zero. In addition, the reflectance of P-polarized light becomes extremely small before and after this angle. The incident angle theta such reflectance is zero or a minimum, referred to as Brewster angle theta _b. For example, when the first transparent substrate is made of glass, the Brewster angle θ _b is

In the example of this figure, air (n ₁ = 1.0) and glass (n ₂ = 1.52), so θ _b = 56.7 ° is obtained.

Here, in the first embodiment, P-polarized light is used as display light incident on the first surface of the transparent screen. In the first embodiment, the incident angle θ ₁ of the display light on the first surface of the transparent screen is adjusted to a value close to the Brewster angle θ _b1 . For this reason, reflection of the display light on the first surface is suppressed to a minimum.

Furthermore, in the first embodiment, the incident angle θ ₂ when the transmitted light that has passed through the reflective polarizing element is applied to the second surface of the transparent screen is set to a value close to the Brewster angle θ _b2. It is adjusted to. For this reason, reflection of the transmitted light on the second surface is minimized.

Therefore, in 1st Embodiment, it can suppress that lights other than the light reflected by the reflective polarizing element reflect toward an observer, and can improve the problem of a double image significantly. it can.

Similarly, in the second embodiment, P-polarized light is used as display light incident on the first surface of the transparent screen. In the second embodiment, the incident angle θ ₁ of the display light on the first surface of the transparent screen is adjusted to a value close to the Brewster angle θ _b1 . For this reason, reflection of the display light on the first surface is suppressed to a minimum.

Therefore, also in the second embodiment, light other than the light reflected by the reflective polarizing element can be prevented from being reflected toward the viewer, and the problem of double images can be significantly improved. Can do.

Here, the effect of suppressing the double image according to the present embodiment as described above can be similarly obtained for color display light. Therefore, in the first embodiment and the second embodiment, it is possible to significantly improve the problem related to the above-described Patent Document 1, that is, the problem that the effect can be obtained only with monochromatic display light. Therefore, the transparent screen according to the present embodiment can be applied to a head-up display device for color display.

However, this embodiment is not limited to the configuration using color display light, and may use monochromatic display light.

(Transparent screen in this embodiment)
Hereinafter, a configuration example of the transparent screen in the present embodiment will be described in detail with reference to the drawings.

FIG. 7 schematically shows a configuration example of the transparent screen in the present embodiment.

As shown in FIG. 7, the transparent screen 700 includes a first transparent substrate 730, a second transparent substrate 735, and an intermediate film 750 disposed between the transparent substrates. A reflective polarizing element 740 is disposed in the intermediate film 750.

The transparent screen 700 has a first surface 722 and a second surface 724. One surface of the first transparent substrate 730 constitutes the first surface 722 of the transparent screen 700, and one surface of the second transparent substrate 735 constitutes the second surface 724 of the transparent screen 700.

The material of the first transparent substrate 730 and the second transparent substrate 735 is not particularly limited, and any material may be used as long as it is made of a transparent member. The first and second

transparent substrates

730 and 735 may be glass substrates or resin substrates, for example.

The material of the intermediate film 750 is not particularly limited as long as it is transparent. For example, an intermediate film used for a known laminated glass such as polyvinyl butyral or ethylene vinyl cetate can be used.

The reflective polarizing element 740 is installed between the first and second

transparent substrates

730 and 735 so that the reflection axis is parallel to the polarization axis of the incident display light. The reflective polarizing element 740 is not particularly limited as long as it is a polarizing element having the above-described effects, and may be, for example, the wire grid

type polarizing elements

100 and 101 as shown in FIG. 2 or FIG. .

The transparent screen 700 in this embodiment, from the side of the first surface 722 of the transparent screen 700, when the display light 760 is irradiated, the angle of incidence at the first surface 722 is theta ₁ (except theta ₁ Is configured to be 0-90 °.

Here, the incident angle θ ₁ is the Brewster angle at the interface between air and the material constituting the first surface 722 of the transparent screen 700 (that is, the first transparent substrate 730), θ _b1 (where θ _b1 is , 0 to 90 °), it is selected so that it is substantially in the range of θ _b1 ± 20 °.

The incident angle θ ₁ is preferably in the range of θ _b1 ± 15 °, more preferably θ _b1 ± 10 °, further preferably θ _b1 ± 5 °, and θ ₁ ≈θ _b1 . Most preferably it is.

Further, the transparent screen 700 in the present embodiment passes through the reflective polarizing element 740 and the transmitted light 770 traveling through the second transparent substrate 735 is incident on the second surface 724 of the transparent screen 700. The incident angle is configured to be θ ₂ (where θ ₂ is 0 to 90 °). Here, the incident angle θ ₂ is the Brewster angle at the interface between the material constituting the second surface 724 (that is, the second transparent substrate 735) of the incident-side transparent screen 700 and the air θ _b2 (where θ _b2 is selected to be substantially in the range of θ _b2 ± 20 ° when 0 to 90 °).

The incident angle θ ₂ is preferably in the range of θ _b2 ± 15 °, more preferably θ _b2 ± 10 °, further preferably θ _b2 ± 5 °, and θ ₂ ≈θ _b2 Most preferably it is.

(Operation of Transparent Screen 700 in the Present Embodiment)
Next, the operation of the transparent screen 700 in the present embodiment having such a configuration will be described.

First, the transparent screen 700 is irradiated with display light 760 that is P-polarized light from the first surface 722 side. That is, in the present embodiment, the display means (not shown) emits P-polarized display light 760.

As described above, in the transparent screen 700 according to the present embodiment, when the display light 760 is incident on the first surface 722 of the transparent screen 700, the incident angle θ1 on the _first surface 722 is substantially equal to It is configured to have a range of θ _b1 ± 20 °.

For this reason, most of the display light 760 is not reflected by the first surface 722 but becomes the first transmitted light 762 and enters the transparent screen 700 as it is.

Thereafter, the first transmitted light 762 travels in the first transparent substrate 730 and reaches the reflective polarizing element 740.

As described above, the reflective polarizing element 740 is arranged so that the reflection axis is parallel to the polarization axis of the incident light. Therefore, most of the P-polarized transmitted light 762 incident on the reflective polarizing element 740 is reflected here to become reflected light 765. The reflected light 765 is emitted toward the viewer 790 in front of the transparent screen 700, and the viewer 790 can recognize the display image by the reflected light 765.

Note that a part of the transmitted light 762 incident on the reflective polarizing element 740 may not enter the second transmitted light 770 and may enter the transparent screen 700 as it is. In this case, the second transmitted light 770 travels through the second transparent substrate 735 and is irradiated onto the second surface 724 of the transparent screen 700 at an incident angle θ ₂ .

Here, in the transparent screen 700 in the present embodiment, as described above, the incident angle θ ₂ of the second transmitted light 770 on the second surface 724 is substantially in the range of θ _b2 ± 20 °. It is comprised so that it may become.

In this case, the reflection of the second transmitted light 770 at the second surface 724 is minimized. That is, most of the second transmitted light 770 becomes the light 774 as it is, and is emitted from the rear of the transparent screen 700 to the outside. For this reason, even if the second transmitted light 770 exists, it is significantly suppressed that the second transmitted light 770 becomes the second reflected light and returns toward the viewer 790.

As described above, in the transparent screen 700 in the present embodiment, the reflected light other than the reflected light 765 reflected by the reflective polarizing element 740 is significantly suppressed. Thus, in the transparent screen 700 in the present embodiment, display is performed. The problem of double image formation can be significantly suppressed.

(Another configuration of the transparent screen in this embodiment)
The configuration example of the transparent screen 700 according to the present embodiment has been described above with reference to FIG. 7. However, the configuration of the transparent screen according to the present embodiment is not limited to the transparent screen 700 illustrated in FIG. 7. .

FIG. 8 shows another configuration example of the transparent screen in the present embodiment.

As shown in FIG. 8, another transparent screen 800 (hereinafter referred to as “second transparent screen 800”) in the present embodiment includes a first transparent substrate 830 and a reflective polarizing element 840.

Here, unlike the transparent screen 700 shown in FIG. 7, the second transparent screen 800 does not have the second transparent substrate 735.

That is, the second transparent screen 800 has a first surface 822 and a second surface 824, and the first surface 822 of the second transparent screen 800 is one of the first transparent substrates 830. The second surface 824 of the second transparent screen 800 is composed of the other surface of the first transparent substrate 830 on which the reflective polarizing element 840 is installed.

The material of the first transparent substrate 830 is not particularly limited, and any material may be used as long as it is made of a transparent member. The first transparent substrate 830 may be, for example, a glass substrate or a resin substrate.

The reflective polarizing element 840 is bonded to the first transparent substrate 830 through the adhesive layer 850.

The reflective polarizing element 840 is disposed on the other surface of the first transparent substrate 830 so that the reflection axis is parallel to the polarization axis of the incident display light. The reflective polarizing element 840 is not particularly limited as long as it is a polarizing element having the above-described effects, and may be, for example, the wire grid

type polarizing elements

100 and 101 as shown in FIG. 2 or FIG. .

As the adhesive layer 850, a known pressure-sensitive adhesive or the like used when sticking various films to the transparent substrate 830 may be used. When the reflective polarizing element 101 shown in FIG. 5 is used as the reflective polarizing element 840 and the transparent substrate 111 of the reflective polarizing element 101 is disposed so as to be in contact with the adhesive layer 850, the material constituting the adhesive layer 850 The refractive index is preferably close to the refractive index of the material constituting the transparent substrate 111. Specifically, the refractive index difference (absolute value) is preferably 0.1 or less, and more preferably 0.05 or less. By doing so, it is possible to suppress light loss due to reflection occurring at the interface between the transparent substrate 111 and the protrusion 120.

Here, when the second transparent screen 800 is irradiated with the display light 860 from the first surface 822 side of the second transparent screen 800, the incident angle on the first surface 822 is θ _1. (Where θ ₁ is 0 to 90 °).

Here, the incident angle θ ₁ is the Brewster angle at the interface between air and the material constituting the first surface 822 of the second transparent screen 800 (that is, the first transparent substrate 830), θ _b1 (where θ _b1 is selected to be substantially in the range of θ _b1 ± 20 ° when θ _b1 is 0 to 90 °.

In the second transparent screen 800 configured as described above, first, the display light 860 having P-polarized light is irradiated onto the transparent screen 800 from the first surface 822 side. That is, in this embodiment, the display means (not shown) emits P-polarized display light 860.

As described above, when the display light 860 is incident on the first surface 822 of the second transparent screen 800, the second transparent screen 800 has an incident angle θ ₁ substantially equal to the first surface 822. And θ _b1 ± 20 °.

For this reason, most of the display light 860 is not reflected by the first surface 822 but becomes transmitted light 862, and enters the second transparent screen 800 as it is.

Thereafter, the transmitted light 862 travels through the first transparent substrate 830 and reaches the reflective polarizing element 840.

As described above, the reflective polarizing element 840 is arranged so that the reflection axis is parallel to the polarization axis of incident light. For this reason, most of the P-polarized transmitted light 862 incident on the reflective polarizing element 840 is reflected here to become reflected light 865. The reflected light 865 is emitted toward the viewer 890 in front of the second transparent screen 800, and the viewer 890 can recognize the display image by the reflected light 865.

In this case as well, it is obvious that the problem of the double image of the display image can be significantly suppressed as in the case of the transparent screen 700 shown in FIG.
(Third configuration of transparent screen in this embodiment)
In FIG. 9, the 3rd structural example of the transparent screen in this embodiment is shown.

As shown in FIG. 9, the third transparent screen 1300 in the present embodiment includes a first transparent substrate 1330, a second transparent substrate 1335, and an intermediate film 1350 disposed between the two transparent substrates. . The third transparent screen 1300 includes a reflective polarizing element 1340 disposed on the opposite side of the first transparent substrate 1330 from the second transparent substrate 1335, and a resin layer covering the reflective polarizing element 1340. 1310.

The transparent screen 1300 has a first surface 1322 and a second surface 1324. One surface of the resin layer 1310 constitutes the first surface 1322 of the transparent screen 1300, and one surface of the second transparent substrate 1335 constitutes the second surface 1324 of the transparent screen 1300.

The reflective polarizing element 1340 is disposed on the surface of the first transparent substrate 1330 so that the reflection axis is parallel to the polarization axis of the incident display light. The reflective polarizing element 1340 is not particularly limited as long as it is a polarizing element having the effects described above, and may be, for example, the wire grid

type polarizing elements

100 and 101 as shown in FIG. 2 or FIG. .

Resin layer 1310 is made of a transparent resin. The resin layer 1310 may be made of any resin as long as the reflective polarizing element 1340 can be properly protected.

The first transparent substrate 1330, the second transparent substrate 1335, and the intermediate film 1350 are the first transparent substrate 730, the second transparent substrate 735, and the intermediate film 1350 of the first transparent screen 700, respectively. The same film as the film 750 can be used.

Here, when the third transparent screen 1300 is irradiated with the display light 1360 from the first surface 1322 side of the transparent screen 1300, the incident angle on the first surface 1322 is θ ₃ (however, θ ₃ Is configured to be 0-90 °.

Here, the incident angle θ ₃ is the Brewster angle at the interface between air and the material constituting the first surface 1322 of the transparent screen 1300 (that is, the resin layer 1310), θ _b3 (where θ _b3 is 0 to 90 °), it is selected so that it is substantially in the range of θ _b3 ± 20 °.

The incident angle θ ₃ is preferably in the range of θ _b3 ± 15 °, more preferably θ _b3 ± 10 °, further preferably θ _b3 ± 5 °, and θ ₃ ≈θ _b3 Most preferably it is.

Further, the third transparent screen 1300 passes through the reflective polarizing element 1340, and in the transmitted light 1370 traveling through the first transparent substrate 1330 to the second transparent substrate 1335, the second surface 1324 of the transparent screen 1300. The incident angle when incident on the light is configured to be θ ₄ (where θ ₄ is 0 to 90 °). Here, the incident angle θ ₄ is the Brewster angle at the interface between the material constituting the second surface 1324 (that is, the second transparent substrate 1335) of the incident-side transparent screen 1300 and air and θ _b4 (where θ _b4 is selected to be substantially in the range of θ _b4 ± 20 °, where 0 _b is 0 to 90 °.

The incident angle θ ₄ is preferably in the range of θ _b4 ± 15 °, more preferably θ _b4 ± 10 °, further preferably θ _b4 ± 5 °, and θ ₄ ≈θ _b4 . Most preferably it is.

(Operation of the third transparent screen 1300)
Next, the operation of the third transparent screen 1300 having such a configuration will be described.

First, display light 1360 that is P-polarized light is irradiated onto the transparent screen 1300 from the first surface 1322 side. That is, in this embodiment, the display means (not shown) emits P-polarized display light 860.

As described above, when the display light 1360 is incident on the first surface 1322 of the transparent screen 1300, the third transparent screen 1300 has an incident angle θ ₃ at the first surface 1322 that is substantially θ. It is comprised so that it may become the range of _b3 +/- 20 degree.

For this reason, most of the display light 1360 is not reflected by the first surface 1322 but becomes the first transmitted light 1362 and enters the transparent screen 1300 as it is.

Thereafter, the first transmitted light 1362 travels through the resin layer 1310 and reaches the reflective polarizing element 1340.

As described above, the reflective polarizing element 1340 is arranged so that the reflection axis is parallel to the polarization axis of the incident light. Therefore, most of the P-polarized transmitted light 1362 incident on the reflective polarizing element 1340 is reflected here to become reflected light 1365. The reflected light 1365 is emitted toward the viewer 1390 in front of the transparent screen 1300, and the viewer 1390 can recognize the display image by the reflected light 1365.

Note that part of the transmitted light 1362 incident on the reflective polarizing element 1340 is not reflected, but becomes the second transmitted light 1370 and may enter the transparent screen 1300 as it is. In this case, the second transmitted light 1370 travels through the first transparent substrate 1330 to the second transparent substrate 1335 and is irradiated onto the second surface 1324 of the transparent screen 1300 at an incident angle θ ₄ .

Here, in the transparent screen 1300 in the present embodiment, as described above, the incident angle θ ₄ of the second transmitted light 1370 on the second surface 1324 is substantially in the range of θ _b4 ± 20 °. It is comprised so that it may become.

In this case, the reflection of the second transmitted light 1370 on the second surface 1324 is suppressed to a minimum. That is, most of the second transmitted light 1370 becomes the light 1374 as it is, and is emitted to the outside from the rear of the transparent screen 1300. For this reason, even if the second transmitted light 1370 exists, the second transmitted light 1370 becomes the second reflected light, and the return to the viewer 1390 is significantly suppressed.

As described above, in the transparent screen 1300 in the present embodiment, the reflected light other than the reflected light 1365 reflected by the reflective polarizing element 1340 is significantly suppressed. The problem of double image formation can be significantly suppressed.

In the above embodiment, the emission direction of the display light from the display means (not shown) and the first surface (722, 822, 1322) so that the incident angles (θ ₁ to θ ₄ ) are in the above ranges. ) And the relationship between the display light emission direction from the display means (not shown) and the angle of the second surface (724, 824, 1324). In the present embodiment, for example, the light emission direction from the display means can be controlled so that the incident angles (θ ₁ to θ ₄ ) fall within the above range. Further, for example, the angle of incidence (θ ₁ to θ ₄ ) is adjusted by adjusting the angle of the first transparent substrate (730, 830, 1330), the resin layer 1310, or the second transparent substrate (735, 1335). Can be. The first surface and the (722,822,1322) and the second surface (724,824,1324), but may be parallel, taking into account the value of theta _b1 and theta _b2, the angle of incidence The angle may be different with respect to the light emission direction from the display means so that (θ ₁ to θ ₄ ) falls within the above range.

(Head-up display device in this embodiment)
Next, as a specific example of the transparent screen in the present embodiment, a head-up display device for a vehicle such as an automobile and a train is taken up, and this configuration and characteristics will be described in detail. Note that the head-up display device in the present embodiment is not limited to a vehicle, and is similarly applied to other moving means such as an aircraft, a screen attached to a show window or a showcase, and the like. It should be noted that it can.

FIG. 10 schematically shows a configuration example of a head-up display device for a vehicle in the present embodiment.

As shown in FIG. 10, the head-up display device 900 includes a windshield 920 including a reflective polarizing element 940 and display means 945 such as a projector. The display means 945 may be installed on a part of the dashboard 980 of the vehicle.

The windshield 920 has an inner surface (driver side surface) 922 and an outer surface (external surface side) 924.

The front glass 920 is configured by bonding a first glass substrate 930 and a second glass substrate 935 to each other through an intermediate film 950. In the example of FIG. 10, the first glass substrate 930 is on the inner surface 922 side of the windshield 920 and the second glass substrate 935 is on the outer surface 924 side.

In the intermediate film 950, a reflective polarizing element 940 is disposed.

The display unit 945 is installed to emit display light 960 including a display image from the display unit 945. The display light 960 emitted from the display unit 945 is P-polarized light.

The display means 945 is configured such that when the display light 960 is irradiated onto the inner surface 922 of the windshield 920, the incident angle of the display light 960 is θ ₁ (where θ ₁ is 0 to 90 °). . Here, the incident angle θ ₁ is substantially when the Brewster angle at the interface between the air and the material constituting the first glass substrate 930 is θ _b1 (where θ _b1 is 0 to 90 °). And θ _b1 ± 20 °.

Further, the display means 945 travels in the windshield 920 of the display light 960, and the incident angle of the transmitted light 970 that reaches the outer surface 924 of the windshield 920 at the outer surface 924 is θ ₂ (where θ ₂ is 0 to 90 °). Here, the incident angle θ ₂ is when the Brewster angle at the interface between the material constituting the second glass substrate 935 on the incident side and the air is θ _b2 (where θ _b2 is 0 to 90 °). In this case, it is selected to be substantially in the range of θ _b2 ± 20 °.

Further, the reflective polarizing element 940 is disposed so that the reflection axis is parallel to the polarization axis of the transmitted light 962 that is transmitted through the first glass substrate 930 and incident on the reflective polarizing element 940.

The reflective polarizing element 940 is not particularly limited as long as it is a polarizing element having the effects as described above, and may be, for example, the wire grid

type polarizing elements

100 and 101 as shown in FIG. 2 or FIG. .

Next, the operation of the head-up display device 900 according to this embodiment configured as described above will be described.

First, the display light 960 having P-polarized light is irradiated from the display unit 945 to the head-up display device 900 according to the present embodiment. The display light 960 is incident on the inner surface 922 of the windshield 920 at an incident angle θ ₁ .

Here, in the head-up display device 900 according to the present embodiment, as described above, the incident angle θ ₁ at the inner surface 922 of the display light 960 is substantially in the range of θ _b1 ± 20 °. ing.

For this reason, most of the display light 960 is not reflected by the inner surface 922 of the windshield 920 but becomes the first transmitted light 962 and enters the windshield 920 as it is.

Thereafter, the first transmitted light 962 travels in the first glass substrate 930 and reaches the reflective polarizing element 940.

As described above, the reflective polarizing element 940 is arranged so that the reflection axis is parallel to the polarization axis of the incident light. For this reason, most of the P-polarized first transmitted light 962 incident on the reflective polarizing element 940 is reflected here to become reflected light 965. The reflected light 965 is emitted toward the driver 990 inside the vehicle, and the driver 990 can recognize the display image by the reflected light 965.

Note that a part of the first transmitted light 962 incident on the reflective polarizing element 940 may not enter the second transmitted light 970 and may enter the windshield 920 as it is. In this case, the second transmitted light 970 travels through the second glass substrate 935 and is incident on the outer surface 924 of the windshield 920 at an incident angle θ ₂ .

Here, in the head-up display device 900 according to the present embodiment, as described above, the incident angle θ _{2 of} the second transmitted light 970 on the outer surface 924 of the windshield 920 is substantially θ _b2 ± 20 °. It is comprised so that it may become the range of.

In this case, the reflection of the second transmitted light 970 on the outer surface 924 of the windshield 920 is minimized. That is, most of the second transmitted light 970 becomes the light 974 as it is, and is emitted from the rear of the windshield 920 toward the outside. For this reason, even if the second transmitted light 970 is present, the second transmitted light 970 becomes the second reflected light, and the return to the driver 990 is significantly suppressed.

As described above, in the head-up display device 900 according to the present embodiment, the problem of the double image of the display image can be significantly suppressed.

(Another configuration of the head-up display device in the present embodiment)
In the above description, as an example, the configuration includes the front glass 920 configured by bonding the first glass substrate 930 and the second glass substrate 935 to each other with the reflective polarizing element 940 interposed therebetween. The features of the head-up display device in the present embodiment have been described.

However, the head-up display device in the present embodiment is not limited to such a configuration.

FIG. 11 schematically shows another configuration example of the head-up display device in the present embodiment.

As shown in FIG. 11, the second head-up display device 1000 basically has the same configuration as the head-up display device 900 shown in FIG. Therefore, in FIG. 11, the same reference numerals as those in FIG.

However, in the second head-up display device 1000, the configuration of the windshield 1020 is different from the configuration of the windshield 920 described above.

That is, the windshield 1020 included in the second head-up display device 1000 includes the first glass substrate 930 and the reflective polarizing element 940, and does not have the second glass substrate 935.

One surface of the first glass substrate 930 constitutes an inner surface 922 of the windshield 1020, and the other surface of the first glass substrate 930 constitutes an outer surface 924 of the windshield 1020. The reflective polarizing element 940 is provided on the other surface of the first glass substrate 930 with the adhesive layer 952 interposed therebetween.

In the second head-up display device 1000, a display unit 945, display light 960 having a P-polarized light, the inner surface 922 of the windshield 1020, is incident at an incident angle theta _1.

Further, as described above, the incident angle θ ₁ at the inner surface 922 of the display light 960 is configured to be substantially in the range of θ _b1 ± 20 °.

Therefore, most of the display light 960 is not reflected by the inner surface 922 of the windshield 1020 but becomes the first transmitted light 962 and enters the windshield 1020 as it is.

As described above, the reflective polarizing element 940 is arranged so that the reflection axis is parallel to the polarization axis of the incident light. Therefore, most of the P-polarized transmitted light 962 incident on the reflective polarizing element 940 is reflected here to become reflected light 965. The reflected light 965 is emitted toward the driver 990 inside the vehicle, and the driver 990 can recognize the display image by the reflected light 965.

It will be apparent to those skilled in the art that the problem of the double image of the display image can be significantly suppressed in this case as well.

(Third configuration of the head-up display device in the present embodiment)
FIG. 12 schematically shows a third configuration example of the head-up display device in the present embodiment.

As shown in FIG. 12, the third head-up display device 1400 includes a windshield 1420 having a resin layer 1410 and display means 1445 such as a projector.

In the resin layer 1410, a reflective polarizing element 1440 is embedded. The display means 1445 may be installed on a part of the dashboard 1480 of the vehicle.

The windshield 1420 has an inner surface (driver side surface) 1422 and an outer surface (external surface side surface) 1424.

The front glass 1420 is formed by bonding a first glass substrate 1430 and a second glass substrate 1435 to each other through an intermediate film 1450, and further, what is the second glass substrate 1435 of the first glass substrate 1430? After the reflective polarizing element 1440 is installed on the opposite surface, the reflective polarizing element 1440 is protected by the resin layer 1410.

12, the resin layer 1410 is on the inner surface 1422 side of the windshield 1420, and the second glass substrate 1435 is on the outer surface 1424 side.

The display unit 1445 is installed to emit display light 1460 including a display image from the display unit 1445. Note that the display light 1460 emitted from the display unit 1445 is P-polarized light.

The display means 1445 is configured such that when the display light 1460 is applied to the inner surface 1422 of the windshield 1420, the incident angle of the display light 1460 is θ ₃ (where θ ₃ is 0 to 90 °). . Here, the incident angle θ ₃ is substantially equal to θ _b3 (where θ _b3 is 0 to 90 °) when the Brewster angle at the interface between the air and the material (that is, resin) constituting the resin layer 1410 is θ _b3. Therefore, it is selected to be in the range of θ _b3 ± 20 °.

In addition, the display unit 1445 travels through the windshield 1420 of the display light 1460, and the incident angle of the transmitted light 1470 that reaches the outer surface 1424 of the windshield 1420 at the outer surface 1424 is θ ₄ (where θ ₄ is 0 to 90 °). Here, the incident angle θ ₄ is when the Brewster angle at the interface between the material constituting the second glass substrate 1435 on the incident side and the air is θ _b4 (where θ _b4 is 0 to 90 °). In practice, it is selected to be in the range of θ _b4 ± 20 °.

Further, the reflective polarizing element 1440 is arranged so that the reflection axis is parallel to the polarization axis of the transmitted light 1462 that is transmitted through the resin layer 1410 and incident on the reflective polarizing element 1440.

The reflective polarizing element 1440 is not particularly limited as long as it is a polarizing element having the above-described effects, and may be, for example, the wire grid

polarizing elements

100 and 101 as shown in FIG. 2 or FIG. .

Next, the operation of the third head-up display device 1400 configured as described above will be described.

First, the third head-up display device 1400 is irradiated with display light 1460 having P-polarized light from the display unit 1445. The display light 1460 is incident on the inner surface 1422 of the windshield 1420 at an incident angle θ ₃ .

Here, in the third head-up display device 1400, as described above, the incident angle θ ₃ of the display light 1460 at the inner surface 1422 is substantially in the range of θ _b3 ± 20 °. Yes.

Therefore, most of the display light 1460 is not reflected by the inner surface 1422 of the windshield 1420 but becomes the first transmitted light 1462 and enters the windshield 1420 as it is.

Thereafter, the first transmitted light 1462 travels through the resin layer 1410 and reaches the reflective polarizing element 1440.

As described above, the reflective polarizing element 1440 is arranged so that the reflection axis is parallel to the polarization axis of the incident light. For this reason, most of the P-polarized first transmitted light 1462 incident on the reflective polarizing element 1440 is reflected here to become reflected light 1465. The reflected light 1465 is emitted toward the driver 1490 inside the vehicle, and the driver 1490 can recognize the display image by the reflected light 1465.

Note that a part of the first transmitted light 1462 that has entered the reflective polarizing element 1440 may not be reflected, but may become the second transmitted light 1470 and enter the windshield 1420 as it is. In this case, the second transmitted light 1470 travels through the first glass substrate 1430 to the second glass substrate 1435 and is incident on the outer surface 1424 of the windshield 1420 at an incident angle θ ₄ .

Here, in the third head-up display device 1400, as described above, the incident angle θ _{4 of} the second transmitted light 1470 on the outer surface 1424 of the windshield 1420 is substantially θ _b4 ± 20 °. It is comprised so that it may become a range.

In this case, the reflection of the second transmitted light 1470 on the outer surface 1424 of the windshield 1420 is minimized. That is, most of the second transmitted light 1470 becomes light 1474 as it is, and is emitted from the rear of the windshield 1420 toward the outside. For this reason, even if the second transmitted light 1470 exists, the second transmitted light 1470 becomes the second reflected light, and the return to the driver 1490 is significantly suppressed.

Thus, also in the third head-up display device 1400, the problem of the double image of the display image can be significantly suppressed.

Hereinafter, examples of the present embodiment will be described.

Example 1
Assuming a transparent screen having a wire grid type polarizing element, the reflection / transmission characteristics of light when P-polarized light was irradiated onto the transparent screen were evaluated by simulation.

FIG. 13 schematically shows a cross-sectional view of the transparent screen used.

As shown in FIG. 13, the transparent screen 1100 includes a first transparent resin substrate 1130, a second transparent resin substrate 1135, and a wire grid type polarizing element 1140.

The first transparent resin substrate 1130 has a first surface 1152. The second transparent resin substrate 1135 has a first surface 1162 and a second surface 1164. The first surface 1152 of the first transparent resin substrate 1130 constitutes the first surface 1122 of the transparent screen 1100, and the second surface 1164 of the second transparent resin substrate 1135 is the second surface of the transparent screen 1100. A surface 1124 is formed.

The wire grid type polarization element 1140 is disposed on the first surface 1162 of the second transparent resin substrate 1135.

The wire grid type polarizing element 1140 has protrusions 1120 arranged at a constant pitch P along the same direction (X direction in FIG. 13). Each protrusion 1120 extends in a direction (Y direction) perpendicular to the paper surface in FIG. The length T of the bottom surface of each protrusion 1120 is set to 70 nm, and the interval S between adjacent protrusions 1120 is set to 70 nm (thus, the pitch P = T + S = 140 nm). The vertical height H of each protrusion 1120 is set to 150 nm.

A metal aluminum wire 1131 is installed on the same inclined surface of each protrusion 1120 along the extending direction of the protrusion 1120. The thickness t of the wire 1131 is 55 nm, and the height (vertical length) L of the wire 1131 is 15 nm.

In order to simulate the conditions of a normal vehicle windshield, the transparent screen 1100 has a transmittance of about 70% (with P-polarized light) when light having a wavelength of 550 nm is irradiated onto the transparent screen 1100 at an incident angle of 0 °. The average value of S-polarized light).

Table 1 summarizes parameter values of the wire grid type polarizing element 1110 in such a transparent screen 1100 (referred to as configuration 1).

Under such conditions, the reflection / transmission characteristics of light when P-polarized light having a wavelength of 550 nm was incident on the transparent screen 900 at an incident angle θ ₁ = 60 ° were evaluated by simulation. For the simulation, GSolver software (manufactured by Grafting Solver Development Company) was used. Note that the wire grid type polarizing element 910 is arranged so that the reflection axis, that is, the extending direction of the wire is parallel to the polarization axis of the incident light.

The column of “Simulation results” in Table 1 above shows the simulation results of the obtained reflectance and transmittance. From this result, the reflectance in Configuration 1 was 25.0%, and the transmittance was 57.0%.

The column of “Evaluation Result” in Table 1 described above shows the result of evaluating the degree (strength) of the double image in Configuration 1.

From this result, the following can be inferred.

First, in the transparent screen 1100 shown in FIG. 13, when P-polarized light is incident at an incident angle θ ₁ = 60 ° from the first surface 1122 side, the incident angle is expressed as air (incident side) / The Brewster angle θ _b at the resin interface is close to 55 °, and θ ≦ θ _b ± 20 ° is sufficiently satisfied.

Accordingly, the P-polarized light is not reflected by the first surface 1122 of the transparent screen 1100 but becomes first transmitted light and enters the transparent screen 1100. In other words, light that is reflected by the first surface 1122 of the transparent screen 1100 (hereinafter referred to as “first reflected light”) hardly occurs.

Thereafter, the first transmitted light is incident on the wire grid type polarization element 1140. The wire grid type polarization element 1140 is arranged so that the extending direction of the wire 1131 is parallel to the polarization axis of incident light. Therefore, the first transmitted light is reflected by the wire grid type polarization element 1140 and becomes the second reflected light. Here, the reflectance of the P-polarized light in the wire grid type polarizing element 1140 is 25.0% from the result of simulation.

Of the first transmitted light that is not reflected by the wire grid type polarization element 1140, 57.0% becomes the second transmitted light and further enters the inside of the transparent screen 1100.

Thereafter, the second transmitted light is incident on the second surface 1124 of the transparent screen 1100 at an incident angle θ ₂ . Here, θ ₂ is about 60 °.

This incident angle θ ₂ is close to 55 ° which is the Brewster angle θ _b at the resin (incident side) / air interface, and sufficiently satisfies θ ≦ θ _b ± 20 °. Therefore, the second transmitted light that has entered the second surface 1124 of the transparent screen 1100 passes through the transparent screen 1100 and is emitted outward without being reflected here. In other words, light that is reflected by the second surface 1124 of the transparent screen 1100 (hereinafter referred to as “third reflected light”) hardly occurs.

As described above, in the case of the configuration 1, the first reflected light and the third reflected light reflected at a place other than the wire grid type polarizing element 1140 portion in the transparent screen 1100 hardly occur.

As a result, only the second reflected light is reflected from the transparent screen 1100, and the degree of the double image is expected to be extremely small.

(Examples 2 to 5)
A transparent screen having a wire grid type polarizing element was assumed by the same method as in Example 1, and the reflection / transmission characteristics of light when P-polarized light was irradiated onto the transparent screen were evaluated by simulation.

However, in the transparent screen of Example 2, the thickness t of the wire 1131 was 5 nm, and the height (length in the vertical direction) L of the wire 1131 was 113 nm. Such a transparent screen is hereinafter referred to as “Configuration 2”. In the transparent screen of Example 3, the thickness t of the wire 1131 was 10 nm, and the height (vertical length) L of the wire 1131 was 75 nm. Such a transparent screen is hereinafter referred to as “Configuration 3”. In the transparent screen of Example 4, the thickness t of the wire 1131 was 25 nm, and the height (vertical length) L of the wire 1131 was 38 nm. Such a transparent screen is hereinafter referred to as “Configuration 4”. In the transparent screen of Example 5, the thickness t of the wire 1131 was 40 nm, and the height (vertical length) L of the wire 1131 was 23 nm. Such a transparent screen is hereinafter referred to as “Configuration 5”.

Table 2 summarizes the parameter values of the wire grid type polarizing element in the transparent screens of configurations 2 to 5.

By the same method as in Example 1, the reflection / transmission characteristics of light when P-polarized light was irradiated to each of the transparent screens of Configurations 2 to 5 were evaluated by simulation.

The column of “Simulation results” in Table 2 shows the simulation results of reflectance and transmittance obtained in each configuration.

In the case of Configuration 2, the reflectance was 14.0% and the transmittance was 51.0%. In the case of Configuration 3, the reflectance was 16.0%, and the transmittance was 46.0%. In the case of the structure 4, the reflectance was 28.0% and the transmittance was 42.0%. In the case of the structure 5, the reflectance was 30.0% and the transmittance was 41.0%.

Also, the “Evaluation Result” column in Table 2 shows the results of evaluating the degree (strength) of double images in Configurations 2 to 5.

In the case of Configuration 2 to Configuration 5, for the same reason as in Configuration 1, “first reflected light” and “third reflected light” hardly occur, and only the second reflected light is reflected. Accordingly, also in this case, only the second reflected light is reflected from the transparent screens in the configurations 2 to 5, and the degree of the double image is expected to be extremely small.

(Comparative Example 1)
By the same method as in Example 1, the reflection / transmission characteristics of light when the transparent screen was irradiated with light were evaluated by simulation. However, in Comparative Example 1, a transparent screen having the structure shown in FIG. 14 was assumed.

That is, as shown in FIG. 14, the transparent screen 1200 includes a resin substrate 1250 having a first surface 1205 and a second surface 1206, and a half mirror 1210 installed on the first surface 1205 of the resin substrate 1250. It consists of. The half mirror 1210 was a metal silver thin film having a thickness of 9.5 nm.

The transparent screen 1200 simulates the conditions of a normal vehicle windshield. Therefore, the transmittance when the transparent screen 1100 is irradiated with light having a wavelength of 550 nm at an incident angle of 0 ° is about 70% (with P-polarized light). The average value of S-polarized light).

The reflection / transmission characteristics of light when S-polarized light having a wavelength of 550 nm is incident on such a transparent screen 1200 (configuration 6) at an incident angle of 60 ° were evaluated by simulation.

The column of “Simulation result” in Table 3 shows the simulation result of the obtained reflectance and transmittance. In the column of “Evaluation Result” in Table 3, the result of evaluating the degree (strength) of double images in Configuration 6 is shown.

Here, in the case of the configuration 6, the reflectance of the S-polarized light is 48.7% from the simulation result. Therefore, in the transparent screen 1200 shown in FIG. 14, when S-polarized light is incident at an incident angle of 60 ° from the first surface 1205 side of the resin substrate 1250, the first surface 1205 is reflected. The amount of one reflected light is 48.7%, and the amount of transmitted light that is transmitted without being reflected is expected to be 47.8%.

47.8% of the transmitted light transmitted through the first surface 1205 is then incident on the second surface 1206 of the resin substrate 1250 at an incident angle θ of about 60 °. The transmitted light is reflected here to become second reflected light, and returns to the first surface 1205 side of the resin substrate 1250.

As a result, the first reflected light and the second reflected light are reflected from the transparent screen 1200.

Here, the intensity of the second reflected light is 47.8%, which is equivalent to 48.7% of the intensity of the first reflected light. For this reason, the degree of double images is expected to be very significant.

In this way, it can be seen that in the configuration 6, a remarkable double image is generated.

(Comparative Example 2)
Next, by the same method as in Comparative Example 1, the reflection / transmission characteristics of light when the transparent screen was irradiated with light were evaluated by simulation. However, in Comparative Example 2, the reflection / transmission characteristics of light when P-polarized light having a wavelength of 550 nm is incident on the transparent screen 1200 shown in FIG. ).

Other conditions are the same as in Comparative Example 1.

The column of “Simulation result” in Table 4 shows the simulation result of the obtained reflectance and transmittance. In the column of “Evaluation Result” in Table 4, the result of evaluating the degree (strength) of the double image in Configuration 7 is shown.

In the case of the configuration 7, from the simulation result, the reflectance of the P-polarized light was 14.2%, and the transmittance was 81.7%. Therefore, in the transparent screen 1200 shown in FIG. 14, when P-polarized light is incident at an incident angle of 60 ° from the first surface 1205 side of the resin substrate 1250, the first surface 1205 is reflected. The amount of one reflected light is 14.2%, and the amount of transmitted light that is transmitted without being reflected is expected to be 81.7%.

81.7% of the transmitted light transmitted through the first surface 1205 is then incident on the second surface 1206 of the resin substrate 1250 at an incident angle θ of about 60 °. The transmitted light is reflected here to become second reflected light, and returns to the first surface 1205 side of the resin substrate 1250.

Here, the intensity of the second reflected light is 81.7%, which is extremely large. For this reason, in the case of Configuration 7, due to the influence of the first reflected light and the second reflected light, the degree of the double image is expected to be extremely remarkable.

As described above, it was found that in configurations 6 and 7, a remarkable double image was generated.

This embodiment can be applied to a head-up display device for moving means such as a vehicle or an aircraft.

The preferred embodiments and examples of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments and examples described above, and is based on the gist of the present invention described in the claims. Various modifications and changes can be made within the range.

The present invention includes the following measures.

A head-up display device having display means and a transparent screen capable of displaying a display image by reflecting display light emitted from the display means, wherein the transparent screen includes a transparent member, A reflective polarizing element embedded in the transparent member, and in the transparent member, when two surfaces in contact with air are respectively a first surface and a second surface, the display light is The display light is incident from the first surface, and the display light is P-polarized light parallel to the incident surface, and the reflective polarizing element is arranged so that the reflection axis is parallel to the polarization axis of the display light. The incident angle θ _{1 on} the first surface is defined as θ _B1 (where θ _b1 is 0 to 90 °) at the Brewster angle at the interface between air and the material constituting the first surface. , Substantially θ _b1 ± The incident angle θ _{2 at} the second surface of transmitted light that travels in the transparent screen without being reflected by the reflective polarizing element out of the display light is within the range of 20 °. The head-up display is substantially in the range of θ _b2 ± 20 ° when the Brewster angle at the interface between the material constituting the surface and air is θ _b2 (where θ _b2 is 0 to 90 °). An apparatus is provided.

A head-up display device having display means and a transparent screen capable of displaying a display image by reflecting display light emitted from the display means, wherein the transparent screen includes a transparent member, A reflective polarizing element disposed on the surface of the transparent member, and in the transparent member, when the two surfaces in contact with air are respectively the first surface and the second surface, the display light is: Incident from the first surface, the reflective polarizing element is disposed on the second surface, the display light is P-polarized light parallel to the incident surface, and the reflective polarizing element is The reflection axis is arranged so as to be parallel to the polarization axis of the display light, and the incident angle θ ₁ of the display light on the first surface is an interface between air and the material constituting the first surface. The Brewster angle of θ _b1 ( However, when θ _b1 is 0 to 90 °), a head-up display device substantially in the range of θ _b1 ± 20 ° is provided.

A head-up display device having display means and a transparent screen capable of displaying a display image by reflecting display light emitted from the display means, wherein the transparent screen includes a transparent member, A reflective polarizing element disposed on the surface of the transparent member, the reflective polarizing element is covered with a resin layer, the surface of the resin layer covering the reflective polarizing element is a first surface, In the transparent member, when the surface opposite to the side where the reflective polarizing element is disposed is the second surface, the display light is incident from the first surface, and the display light is P-polarized light parallel to the incident surface, and the reflective polarizing element is disposed such that the reflection axis is parallel to the polarization axis of the display light, and the display light on the first surface the incident angle theta ₁ is air and the first The Brewster angle at the interface theta _{b1 (although} theta _b1 is 0-90 °) between the material constituting the surface when the substantially located at theta _b1 ± 20 ° range, of the display light The incident angle θ _{2 at} the second surface of the transmitted light that travels in the transparent screen without being reflected by the reflective polarizing element is an interface between the material constituting the second surface and air. When the Brewster angle is θ _b2 (where θ _b2 is 0 to 90 °), a head-up display device substantially in the range of θ _b2 ± 20 ° is provided.

This international application claims priority based on Japanese Patent Application No. 2012-141163 filed on June 22, 2012, the entire contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Head-up display apparatus for conventional vehicles 20 Windshield 22 Inner surface (driver side surface)
24 External surface (surface on the outside world)
30 First glass substrate 35 Second glass substrate 39 Intermediate film 40 Combiner 45 Display means 60 Display light 65 Reflected light 70 Transmitted light 75 Second reflected light 80 Dashboard 90 Driver 100 Wire grid type polarizing element 101 Another Wire grid type polarization element 110 Transparent substrate 111 Transparent substrate 115 Flat surface 120 Projection 130, 131 Metal wire 140S, 140P Light 150a Reflected light 150b Transmitted light 150c Transmitted light 150d Reflected light 700 Transparent screen 722 First surface according to the present invention 724 second surface 730 first transparent substrate 735 second transparent substrate 740 reflective polarizing element 750 intermediate film 760 display light 762 first transmitted light 765 reflected light 770 second transmitted light 774 light 790 viewer 800 Second transparent screen 822 First surface 824 Second surface 830 First transparent substrate 840 Reflective polarizing element 850 Adhesive layer 860 Display light 862 Transmitted light 865 Reflected light 890 Viewer 900 Head-up display device 920 according to the present invention Front glass 922 inner surface 924 outer surface 930 first glass substrate 935 second glass substrate 940 reflective polarizing element 945 display means 950 intermediate film 952 adhesive layer 960 display light 962 first transmitted light 965 reflected light 970 second transmitted light 974 Light 980 Dashboard 990 Driver 1000 Second head-up display device 1020 Windshield 1100 Transparent screen 1120 Projection 1122 Transparent screen first surface 1124 Transparent screen second surface 1 130 1st transparent resin substrate 1131 Wire 1135 2nd transparent resin substrate 1140 Wire grid type polarization element 1152 1st surface of 1st transparent resin substrate 1162 1st surface of 2nd transparent resin substrate 1164 2nd Second surface of transparent resin substrate 1200 Transparent screen according to comparative example 1205 First surface 1206 Second surface 1210 Half mirror 1250 Resin substrate 1300 Third transparent screen 1310 Resin layer 1322 First surface 1324 Second Surface 1330 First transparent substrate 1335 Second transparent substrate 1340 Reflective polarizing element 1350 Intermediate film 1360 Display light 1362 First transmitted light 1365 Reflected light 1370 Second transmitted light 1374 Light 1390 Viewer 1400 Third head-up Display device 1410 Resin layer 142 Front glass 1422 Inner surface 1424 Outer surface 1430 First glass substrate 1435 Second glass substrate 1440 Reflective polarizing element 1445 Display means 1450 Intermediate film 1460 Display light 1462 First transmitted light 1465 Reflected light 1470 Second transmitted light 1474 Light 1480 Dashboard 1490 Driver

Claims

Display means;
A transparent screen having a transparent member and a reflective polarizing element and capable of displaying a display image by reflecting display light emitted from the display means;
Have
The reflective polarizing element is provided in contact with the transparent member or the resin layer, and the display light is in contact with the air of the transparent member or resin layer provided in contact with the reflective polarizing element. Incident from
The display light is P-polarized light parallel to the incident surface,
The reflective polarizing element is arranged such that the reflection axis is parallel to the polarization axis of the display light,
The incident angle θ 1 at the first surface is substantially equal to θ b1 (where θ b1 is 0 to 90 °) when the Brewster angle at the interface between air and the material forming the first surface is θ b1. In particular, a head-up display device having a range of θ b1 ± 20 °.
In the transparent screen, the reflective polarizing element is embedded in the transparent member,
The first surface is a surface in contact with air of the transparent member,
In the transparent member, when the surface in contact with air on the opposite side to the first surface is the second surface,
Of the display light, an incident angle θ 2 on the second surface of transmitted light that travels in the transparent screen without being reflected by the reflective polarizing element is a material that constitutes the second surface. 2. The Brewster angle at the interface with the air is θ b2 (where θ b2 is 0 to 90 °), and is substantially in the range of θ b2 ± 20 °. Head up display device.
The transparent member includes two transparent substrates and an intermediate layer disposed between the transparent substrates, and the reflective polarizing element is embedded in the intermediate layer. The head-up display device according to 2.
The first surface is a surface where the transparent member is in contact with air,
In the transparent member, when the surface in contact with air on the opposite side to the first surface is the second surface,
The head-up display device according to claim 1, wherein the reflective polarizing element is disposed on the second surface of the transparent member in the transparent screen.
In the transparent screen, the reflective polarizing element is disposed on the surface of the transparent member and covered with a resin layer,
The first surface is a surface in contact with air of the resin layer covering the reflective polarizing element,
In the transparent member, when the surface opposite to the side where the reflective polarizing element is disposed is the second surface,
Of the display light, an incident angle θ 2 on the second surface of transmitted light that travels in the transparent screen without being reflected by the reflective polarizing element is a material that constitutes the second surface. 2. The Brewster angle at the interface with the air is θ b2 (where θ b2 is 0 to 90 °), and is substantially in the range of θ b2 ± 20 °. Head up display device.
The said transparent member is comprised from one transparent substrate, or is comprised from two transparent substrates and the intermediate | middle layer arrange | positioned between both transparent substrates, The Claim 4 or 5 characterized by the above-mentioned. Head up display device.
The head-up display device according to claim 3 or 6, wherein the transparent substrate is made of resin or glass.
The head-up display device according to any one of claims 1 to 7, wherein the reflective polarizing element is a wire grid polarizing element.
The head-up display device according to any one of claims 1 to 8, wherein the transparent screen is a windshield for transportation equipment.