KR101911488B1 - Combiner attached to windshield for head-up-display - Google Patents

Abstract

A combiner attached to a windshield for an HUD according to the present invention is attached to an inner side of the windshield of a vehicle and reflects display light emitted from an image output device to the inside of the vehicle toward a driver. Wherein, the combiner attached to a windshield for an HUD includes: a transmitting layer for transmitting the display light to the outer side by refracting the display light which is incident to the inner side from the image output device; and a selective reflection layer whose inner side is attached to the outer side of the transmitting layer and which reflects a specific polarization beam in the display light which is transmitted, to the transmitting layer. Accordingly, the present invention can minimize the degradation of visibility.

Description

{COMBINER ATTACHED TO WINDSHIELD FOR HEAD-UP-DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an optical member for a head-up display (HUD), and more particularly, to a combiner with a windshield for a HUD capable of preventing a double image and minimizing visibility due to external light .

The first HUD system was developed for fighter aircraft, and the image display light is reflected from a combiner placed in front of the cockpit and incident on the pilot side, allowing the pilot to recognize various information by the image display light. In recent years, the HUD system has been actively applied to the automobile industry. By displaying the surrounding environment information and safety information necessary for driving the vehicle in front of the driver's view, the driver does not have to move his / her eyes while driving, .

Since the combiner-type HUD is required to install a reflector-mounted combiner on the vehicle panel, it is inefficient in terms of space efficiency, has low visibility for the display image and has low transparency to the external image. Recently, a windshield type HUD is in the spotlight.

1 and 2 are reference views showing a conventional windshield type HUD system for a vehicle. Referring to FIG. 1, a vehicular HUD system 10 includes a video output device 11 and a reflection mirror 12. Here, the video output device 11 outputs video display light including various video information to the reflection mirror 12, and the video display light is reflected by the reflection mirror 12 and is reflected on the inner surface of the windshield 13 of the vehicle I will join. Here, the image display light reflected by the inner surface of the windshield 13 is incident on the sight line (eye box) of the driver, and the image display light is recognized as a virtual image located at a position a certain distance from the outer surface of the windshield 13 .

In the conventional windshield type HUD system, when external light (such as sun light) enters the HUD optical system from the outer surface of the windshield 13, the external light is reflected and scattered by the HUD optical system, As the light enters the field of view, the visibility of the image display light may be lowered, such as causing the driver's eyes to feel tired. 1, the sunlight incident on the outer surface of the windshield 13 is transmitted through the windshield 13, reflected by the reflecting mirror 12, and then incident on the inner surface of the windshield 13, The visual field of the image display light outputted from the display device 11 is reached together with the visibility of the driver.

In addition, in the conventional windshield type HUD system, visibility of the image display light may be lowered due to the generation of the double phase due to the light reflected from the inner side surface and the outer side surface of the windshield 13, respectively. For example, referring to FIG. 2, the image display light output from the video output device 11 is reflected by the inner surface of the windshield and travels to the eye box, , The driver recognizes the image information in a finely superimposed state.

However, in a windshield type HUD system, there is not provided a technique for simultaneously solving a problem of low visibility due to external light incident unintentionally and a dual-phase problem caused by image display light reflected from both sides of the windshield to be.

Japanese Patent No. 5,081,953

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-described problems, and it is an object of the present invention to minimize the visibility degradation due to external light incident on the HUD system and reflected by the eye box, Which is capable of preventing the occurrence of a double phase due to the windshield of the HUD.

Other objects of the present invention will become apparent from the following description of preferred embodiments.

According to one aspect of the present invention, a combiner with a windshield for HUD is attached to the inner surface of a windshield of a vehicle, and reflects the display light emitted from the video output device toward the inside of the vehicle toward a driver. Here, the combiner with a windshield for HUD includes a transmissive layer that refracts display light incident on the inner side from the image output device and transmits the display light to the outer side; And a selective reflection layer for attaching the inner side surface to the outer side surface of the transmissive layer and reflecting a specific polarized beam from the transmissive display light to the transmissive layer.

In one embodiment, the transmissive layer may include a wedge optical layer having a first refractive index and an inner side formed obliquely with the selective reflective layer.

In one embodiment, the wedge-shaped optical layer has an inner surface formed with a predetermined angle with the selective reflection layer so that the incident display light forms a Brewster angle and enters the inner surface of the selective reflection layer. .

In one embodiment, the transmissive layer may further include an anti-reflection coating layer formed on an inner surface of the wedge-shaped optical layer.

In one embodiment, the selective reflection layer may include a selective reflection film having a second refractive index greater than the first refractive index and forming an Brewster angle, and reflecting the S polarized light to the transmissive layer in incident display light.

In one embodiment, the selective reflection film forms the Brewster's angle and can refract the P-polarized beam from the incident display light to transmit the P-polarized beam to the outer surface.

In one embodiment, the selective reflection layer may further include an S polarizing film which has an inner surface attached to an outer surface of the selective reflection film, and absorbs at least a part of the transmitted P polarized light beam.

In one embodiment, the S polarizing film may reflect external light incident from the outside of the vehicle to the outside of the vehicle.

In one embodiment, the wedge-shaped optical layer is formed of a SiO ₂ nanoload, and the selective reflection film may be formed of any one of SiO ₂ , Si ₃ N _4, and amorphous Si.

According to the present invention, it is possible to minimize the visibility degradation due to external light incident on the HUD system and reflected by the eye box, and to prevent the occurrence of a double image due to the image display light reflected from both sides of the windshield have.

In addition, the present invention can be easily designed corresponding to various windshield shapes, and the design cost can be lowered compared with the conventional HUD combiner, and the space efficiency can be greatly improved.

1 and 2 are reference views for explaining a windshield type HUD system according to the prior art.
3 and 4 are reference views for explaining a combiner equipped with a windshield for a HUD according to an embodiment of the present invention.
5 is a reference view for explaining a wedge-shaped optical layer according to the present invention.
6 to 13 are reference views for explaining a material applicable to a combiner with a windshield for a HUD according to an embodiment of the present invention.

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The present invention relates to an optical member for a HUD, and more particularly, to an optical member for an HUD which minimizes visibility degradation due to external light incident on the HUD system and reflected by an eye box, To a combiner with a windshield for HUD that can prevent the occurrence of a double phase due to light.

As a result of intensive efforts to solve the above-described problems, the inventors of the present invention have found that a combiner attached to the inner surface of a windshield is composed of a plurality of layers, and the optical layer on the inner side (video output device side) It is confirmed that the above-mentioned effect can be obtained by spatially separating light and selectively configuring the optical layer on the outer side (windshield side) to selectively transmit a specific polarized light beam through the inner optical layer Thus completing the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 and 4 are reference views for explaining a windshield attachment type combiner (hereinafter referred to as an attachment type combiner) according to the present invention. On the other hand, among the terms used in the following description, the inner side means the surface facing the inside (or the driver) of the vehicle, and the outer side means the surface facing the outside (or windshield) of the vehicle.

Referring to FIG. 3, the attachable combiner is attached to a side surface of the windshield 110 and reflects the display light emitted from the video output device (not shown) to the inside of the vehicle toward the driver.

The video output device (not shown) outputs a predetermined video display light. The video output device may be located in a lower direction of the attachable combiner shown in FIG. 3 and may be connected to a video signal providing device (not shown) And outputs the generated image display light to the outside.

The attachable combiner includes a transmissive layer 120 and a selective reflective layer 130.

Each of the transmissive layer 120 and the selective reflective layer 130 is a thin film having a predetermined area. The transmissive layer 120 and the selective reflective layer 130 may have various areas and thickness depending on design conditions.

3 is an enlarged view of a part of the windshield 110 formed on the front surface of the vehicle for a clear understanding of the present invention. The attachment combiner according to the present invention includes a windshield 110, And should not be construed as limited to the area of attachment.

Each of the transmissive layer 120 and the selective reflective layer 130 has an inner side surface and an outer side surface. The outer surface of the selective reflection layer 130 may be adhered to the inner surface of the selective reflection layer 130 and the outer surface of the selective reflection layer 130 may be bonded to the inner surface of the windshield 110. [ .

Each of the transmissive layer 120 and the selective reflective layer 130 may have a predetermined refractive index and the transmissive layer 120 and the selective reflective layer 130 may have different refractive indices.

The transmissive layer 120 refracts the display light incident on the inner surface from the image output device and transmits the display light to the outer surface.

In one embodiment, the transmissive layer 120 may include a wedge optical layer 121 whose inner surface is sloped with the selective reflective layer 130. That is, according to one embodiment of the present invention, the transmissive layer 120 may include an optical layer 121 formed in a wedge shape as shown in FIG.

Here, the inner surface of the wedge-shaped optical layer 121 is formed to have a predetermined angle with the selective reflection layer 130, and the wedge-shaped optical layer 121 is made of a material It is possible to refract at a predetermined angle and transmit the light to the outer side.

On the other hand, the display light incident from the video output device is reflected by the first optical path A reflected from the inner side of the wedge-shaped optical layer 121 into the interior of the vehicle, and the second optical path A reflected from the inner side of the wedge- And then divided into a second optical path B which is reflected by the outer side surface and is refracted from the inner side surface and enters into the interior of the vehicle. Here, as shown in Fig. 5, as the transmissive layer 120 is formed in a wedge shape, the display light proceeding along the first optical path A and the display proceeding along the second optical path B The light can be processed at a predetermined angle without being parallel to each other. The wedge-shaped optical layer 121 is arranged such that the display light proceeding along the second optical path B is incident on the eye box, and the display light proceeding along the first optical path A is incident on the lower portion of the eye box As shown in FIG.

According to the present embodiment, since the transmissive layer 120 is formed in a wedge shape, the display image can be spatially separated, thereby solving the double-phase problem that occurs in the conventional wind type HUD of FIG.

On the other hand, the display light traveling along the second optical path A corresponds to the light not incident on the line of sight of the driver, and therefore, the following description will be omitted for the sake of clear understanding of the present invention.

In one embodiment, the transmissive layer 120 may further include an anti-reflection coating 122 formed on an inner surface of the wedge-shaped optical layer 121. Here, as shown in FIG. 4, the anti-reflective coating layer 122 can transmit the display light incident from the video output device into the wedge-shaped optical layer 121 without reflecting it into the interior of the vehicle. Thus, the anti-reflective coating layer 122 can increase the overall light efficiency of the attachable combiner and prevent the display light from proceeding along the second optical path B from being generated, thereby solving the dual phase problem.

)을 이루며 입사할 수 있도록 쐐기형 광학층(121)의 내측면은 선택 반사층(130)과 각도θ를 이루도록 형성될 수 있다. 한편, 쐐기형 광학층(121)의 경사 각도θ에 대한 설계 범위에 대하여는 후술한다.In one embodiment, the wedge-shaped optical layer 121 is formed such that the incident light is incident on the inner surface of the selective reflection layer 130 as a Brewster angle, Can be formed at an angle. 4, the display light transmitted through the wedge-shaped optical layer 121 is reflected by the inner surface of the selective reflection layer 130 and the Brewster's angle

The inner surface of the wedge-shaped optical layer 121 may be formed to form an angle &thetas; with the selective reflection layer 130. On the other hand, the design range for the inclination angle? Of the wedge-shaped optical layer 121 will be described later.

The selective reflection layer 130 has an inner surface attached to the outer surface of the transmissive layer 120. Here, the selective reflection layer 130 may reflect a specific polarized beam to the transmissive layer 120 in the display light transmitted through the transmissive layer 120.

In one embodiment, the selective reflective layer 130 may include a selective reflective film 131 having a refractive index greater than that of the wedge-shaped optical layer 121. That is, the selective reflection film 131 may be configured to have a refractive index (n2, second refractive index) larger than the refractive index (n1, first refractive index) of the wedge-shaped optical layer 121. [

In one embodiment, the selective reflection film 131 transmits the wedge-shaped optical layer 121 to form a Brewster angle, and can reflect the S polarized beam to the wedge-shaped optical layer 121 in the incident display light. 4, the display light incident on the image display device passes through the wedge-shaped optical layer 121 and forms the Brewster's angle by the physical properties and the inclination angle of the wedge-shaped optical layer 121, As shown in FIG. As the display light enters the inner surface of the selective reflection film 131 with a Brewster angle, the P-polarized light beam is transmitted and refracted into the selective reflection film 131, and the S- To the wedge-shaped optical layer (121).

That is, according to the present embodiment, when outside light (e.g., sunlight) is incident on the HUD optical system from outside the windshield 110, the incident external light is reflected and scattered by the HUD optical system, 110), only the S-polarized light beam can be selectively transmitted to the eye box, thereby improving visibility.

In one embodiment, the selective reflection layer 130 may further include an S polarizing film 132 whose inner surface is attached to the outer surface of the selective reflection film 131. Here, the S polarizing film 132 can absorb at least a part of the P polarized light beam transmitted through the selective reflection film 131.

In one embodiment, the S polarizing film 132 may be configured to reflect external light incident from the outside of the windshield 110 to the outside of the windshield 110 on the outer surface.

According to the present embodiment, the S polarizing film 132 absorbs the P polarized light beam transmitted through the selective reflection film 131 so that the P polarized light beam is not further reflected, So that the visibility can be further improved.

Hereinafter, the design conditions of the attachable combiner according to one embodiment of the present invention will be described in more detail with reference to FIG.

1. The inclination angle? Of the wedge-

The Snell's law is applied to the inner surface (n ₀ -> n ₁ ) of the wedge-shaped optical layer 121 to induce the tilt angle θ of the wedge-shaped optical layer 121, (N ₁ - > n ₂ ), the following is applied.

Here, the inclination angle &thetas; of the wedge-shaped optical layer 121 is given by the following equation.

에 의존한다. That is, the inclination angle of the wedge-shaped optical layer (121) (θ) is n _1, n _2, and the angle of incidence

Lt; / RTI >

)2. The incident angle of the display light incident on the eye box (

)

)를 유도하기 위하여, 쐐기형 광학층(121)의 내측면(n₁ -> n₀)에서 스넬의 법칙을 적용하면 다음과 같다.The incident angle of the display light incident on the eye box (

(N ₁ -> n ₀ ) of the wedge-shaped optical layer 121, Snell's law is applied as follows.

)는 n₁, n₂ 및 입사각

에 의존한다. That is, the incident angle of the display light incident on the eye box (

) Are n ₁ , n _2, and the incident angle

Lt; / RTI >

However, the following conditions shall be satisfied.

The above conditions are summarized as follows.

or,

3. Light efficiency of the attachable combiner L _eff

According to the Fresnel equation, the reflectance and transmittance at the interface are as follows.

(R _{s - pol: s} reflectance of the polarized beam, R _{p - pol;} reflectance of p-polarized beam, T _{s - pol:} transmittance of s-polarized beam, T _{p - pol:} the transmittance of the p-polarized beam)

Here, the transmittance at n ₀ and n ₁ , the reflectance at n ₁ and n ₂ , and the transmittance at n ₁ and n ₀ are respectively derived as follows.

The final optical efficiency of the attached combiner is given by the product of the transmittance at n ₀ and n ₁ , the reflectance at n ₁ and n ₂ , the transmittance at n ₁ and at n ₀ , and the transmittance at n ₁ medium.

([T] _n1 : Transmittance of n1 medium)

에 의존한다.That is, the light efficiency L _{eff of the} attachable combiner N ₁ , n ₂ and the incident angle

Lt; / RTI >

On the other hand, when the anti-reflective coating layer 122 is formed on the inner surface of the wedge-shaped optical layer 121 according to an embodiment of the present invention, the transmittance at n ₀ and n ₁ and the transmittance at n ₁ and n ₀ are 1 Therefore, considering only the reflectance at n ₁ and n ₂ , the light efficiency L _eff Is as follows.

4. Material of attachable combiner

An embodiment of the material applicable to each structure will be described in detail considering the design conditions of the attachable combiner according to the present invention described in the first to third aspects. It is to be understood that the following embodiments are not intended to limit the scope of the present invention and that various known materials satisfying the above conditions can be applied.

In one embodiment, the wedge-shaped optical layer 121 is formed of a SiO ₂ nanoload, and the selective reflection film 131 may be formed of any one of SiO ₂ , Si ₃ N _4, and amorphous Si.

6 to 8, at a wavelength of 632.8 nm, SiO ₂ nanorods have a refractive index of about 1.05, SiO ₂ has a refractive index of about 1.45, Si ₃ N ₄ has a refractive index of about 2.04, amorphous Si has a refractive index of about 4.5 . It can be seen that SiO ₂ , Si ₃ N ₄ and amorphous Si (n ₂ ) exhibit a relatively high refractive index as compared with the SiO ₂ nanorod (n ₁ ). In addition, SiO ₂ nanorods (n ₁ ) exhibit good transmittance in the visible region, and SiO ₂ , Si ₃ N ₄ and amorphous Si (n ₂ ) can be thin coated (about several tens nm) Is not generated.

9 to 11 show the case where the wedge-shaped optical layer 121 is formed of SiO ₂ nanorod and the selective reflection film 131 is formed of SiO ₂ , Si ₃ N ₄ and amorphous Si. θ _i and 1 / sin (θ + θ _b) according to the attached combiners your design conditions described, is a reference showing the relationship between θ _t2.

9 to 11, an angle range of θ _i , θ _t2 and θ for the case where each of the materials is applied can be confirmed.

9 shows the relationship between the incident angle θ _i and 1 / sin (θ _b + θ). FIG. 10 shows θ _t2 in the range of θ _i satisfying the following condition in FIG.

Here, referring to Fig. 11, the incident angle &thetas; _i Θ _i in the range And θ (inclination angle of the attachable combiner). For example, if n ₂ is formed of SiO ₂ , the wedge angle θ of the attachment combiner can be formed at 7 ° at an incident angle θ _i = 50 °. For another example, if n ₂ is formed of Si ₃ N ₄ , the wedge angle θ of the attachment combiner can be formed at 7 ° at an incident angle θ _i = 60 °. For another example, if n ₂ is formed of amorphous Si, the wedge angle θ of the attachment combiner can be formed at 34 ° at an incident angle θ _i = 45 °.

12 to 13 show the case where the wedge-shaped optical layer 121 is formed of SiO ₂ nanorod and the selective reflection film 131 is formed of SiO ₂ , Si ₃ N _4, and amorphous Si, and the wedge-shaped optical layer 121 In the case where the antireflection coating layer 122 is formed on the inner surface of the antireflection coating layer 122. FIG.

Referring to Figures 12-13, the final light efficiency L _eff of the attachable combiner with anti-reflective coatings is about 0.1 for SiO ₂ , about 0.34 for Si ₃ N ₄ , and about 0.8 for amorphous silicon in the visible region Can be confirmed. Considering that the light efficiency of a typical windshield is less than 0.1, it can be seen that the light efficiency of the mount combiner according to an embodiment of the present invention is very good.

It will be apparent to those skilled in the relevant art that various modifications, additions and substitutions are possible, without departing from the spirit and scope of the invention as defined by the appended claims. The appended claims are to be considered as falling within the scope of the following claims.

10: Conventional HUD system
11: Video output device
12: reflection mirror
13: Windshield
110: Windshield
120: transmissive layer
121: wedge-shaped optical layer
122: Non-reflective coating layer
130: selective reflection layer
131: Selective reflective film
132: S polarizing film

Claims (9)

A combiner with a windshield for HUD which is attached to the inner surface of a windshield of a vehicle and reflects the display light emitted from the video output device to the inside of the vehicle toward the driver,
A transmissive layer for refracting the display light incident on the inner surface from the image output device and transmitting the display light to the outer surface; And
A selective reflection layer for attaching the inner side surface to the outer side surface of the transmissive layer and reflecting a specific polarized beam from the transmissive display light to the transmissive layer;
≪ / RTI >
The transmissive layer
And a wedge optical layer having a first refractive index and an inner side formed obliquely with the selective reflection layer,
The wedge-
Wherein the incident light is incident on an inner surface of the selective reflection layer at a Brewster angle, the inner surface of the selective reflection layer is formed at a predetermined angle with the selective reflection layer,
The selective reflection layer
And a selective reflection film having a second refractive index greater than the first refractive index and reflecting the S polarized light beam to the transmissive layer at the Brewster's angle and entering the display light,
Wherein the wedge-shaped optical layer is formed of SiO ₂ nanorods, and the selective reflection film is formed of any one of SiO ₂ , Si ₃ N _4, and amorphous Si.
delete delete 2. The method of claim 1, wherein the transmissive layer
And an antireflection coating layer formed on the inner surface of the wedge-shaped optical layer.
delete The reflective film according to claim 1,
And the B polarizing beam refracts the P polarized beam from the incident display light and transmits the B polarized light to the outer side.
The optical information recording medium according to claim 6,
And an S polarizing film attached to an outer surface of the selective reflection film to absorb at least a part of the transmitted P polarized light beam. The method as claimed in claim 7, wherein the S polarizing film
And the external surface reflects external light incident from the outside of the vehicle to the outside of the vehicle. delete

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