JP6549817B2 - Combiner - Google Patents

Description

  The present invention relates to a combiner that is an optical member, and is used, for example, in a head up display (HUD) apparatus mounted on a vehicle.

  In a HUD device mounted on a vehicle, as disclosed in Patent Document 1, an image of light projected from the main body of the HUD device is made incident on a flat plate-like combiner, and the light reflected by the plane of the combiner is It is led to the eye point which is the driver's observation position. Therefore, the image that can be observed at the eye point is imaged as a virtual image as if it exists at a position ahead of the combiner. In addition, since the combiner is transparent, the driver can view the real image such as a landscape outside the vehicle seen through the combiner and the displayed virtual image superimposed on each other.

  Further, as disclosed in Patent Document 2, a reflective screen having a function equivalent to a combiner for a HUD device is also known. That is, in a see-through display device, an image can be projected on a reflective / transmissive screen, and the background of the screen and the projected image can be observed.

JP-A-8-11580 JP, 2009-237351, A

  By the way, the reflection of light is mainly caused by a rapid change of refractive index. Therefore, in the case of a HUD device using a plate-like combiner, light reflection occurs on both the front and back sides of the combiner. That is, the image of the light projected from the body of the HUD device is reflected by the surface on the front side of the combiner and directed to a predetermined eye point, while the light reflected on the surface on the back side of the combiner is also directed to the eye point. That is, two images having different optical paths can be observed at a common eye point, and it may be seen as an overlap of two images whose display positions are mutually shifted due to the difference in optical paths. This significantly reduces the visibility of the display and the display quality.

  In particular, in the case of a HUD device for vehicles, a combiner having a certain thickness is often used, and the optical path difference between the image reflected on the front side and the image reflected on the rear side tends to be large. Therefore, the positional deviation between the two overlapping images also becomes large. Therefore, various anti-reflection processes are performed in the combiner disclosed in Patent Document 1 and the like.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a combiner that is subjected to a new anti-reflection processing that can display a clearer image.

In order to achieve the objective mentioned above, the combiner concerning the present invention is characterized by following (1)-(4).
(1) A combiner body which is a transparent plate-like optical member,
A film disposed on the surface of the combiner body;
Equipped with
In the film, a recess or a protrusion is periodically and continuously formed on the other surface opposite to the one surface adjacent to the surface of the combiner main body, and the interval between the recess or the protrusion for one cycle Is shorter than the wavelength of visible light,
As the position in the height direction of the convex portion moves from the bottom side to the top side, the cross-sectional area of the convex portion gradually decreases, and the average refractive index of the material of the film and the air in the convex portion is the height Correspondingly, it changes continuously and gradually, and no reflection occurs at the boundary between the material of the film and the adjacent air at the convex portion,
about.
(2) It is a combiner of the structure of said (1), Comprising:
The combiner body has two planes intersecting a straight line connecting an eye point, which is a position at which the reflected light from the combiner body is observed, and the combiner body,
The film is disposed on one of two sides of the combiner body,
about.
(3) It is a combiner of the composition of said (2),
The film is disposed on one of the two sides of the combiner body which is at a greater distance from the eye point.
about.
(4) It is a combiner of the composition of the above (3),
The film is adhered to the surface of the combiner body via a predetermined adhesive layer having a refractive index equal to the refractive index of the film, with one surface close to the surface of the combiner body being bonded. Placed on the surface of the body,
about.

According to the combiner of the structure of said (1), since the space | interval is shorter than the wavelength of visible light, the said recessed part or the convex part formed in the said film can reflect without transmitting visible light. That is, reflection of light generated on the surface of the combiner body can be prevented.
According to the combiner of the above configuration (2), since the film prevents reflection of any one of the two surfaces of the combiner main body, only one of the optical paths of the light image directed to the eye point is To prevent double reflection of the displayed image.
According to the combiner of the structure of said (3), the image of the light which is reflected by one surface of the said combiner main body and goes to the said eye point is displayed in a clearer state.
According to the combiner of the structure of said (4), the frequency | count that the light which is reflected by one surface of the said combiner main body and which goes to the said eye point passes the said contact bonding layer reduces. Therefore, the influence of slight light reflection and the like in the adhesive layer can be suppressed, and the image can be displayed in a clearer state.

  According to the combiner of the present invention, reflection of light in the combiner main body can avoid a situation where an image looks double, and enables clearer display in a HUD device or the like.

  The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the modes for carrying out the invention described below (hereinafter referred to as "embodiments") with reference to the attached drawings. .

FIG. 1 is a side view showing a configuration example of a combiner. FIG. 2 is a side view showing a configuration example of a HUD device using the combiner of FIG. FIG. 3 is a side view showing an optical path in the combiner shown in FIG. FIG. 4 is an enlarged side view showing a cross-sectional structure of the film shown in FIG. FIG. 5 is a side view showing incident light and reflected light in the absence of a film. FIG. 6 is a graph showing the distribution of the refractive index of each part in the film shown in FIG. FIG. 7 is a side view showing incident light and reflected light in a combiner provided with a film. FIG. 8 is a side view showing the light path in a HUD device utilizing a film-free combiner. FIG. 9 is a front view showing a specific example of an image projected onto an eye point in the situation shown in FIG. FIG. 10 is a side view showing the configuration of a modification of the combiner shown in FIG. FIG. 11 is a front view showing a specific example of an image projected on an eye point in the HUD device using the combiner shown in FIGS. 1 and 10. FIG. 12 is a side view showing the configuration and light path of a combiner including an adhesive layer. FIG. 13 is a side view showing a modification of the combiner shown in FIG.

  Specific embodiments of the combiner of the present invention will be described below with reference to the drawings.

First Embodiment
<Description of the outline of the whole system>
The structural example of the combiner 10 in this embodiment is shown in FIG. Moreover, the structural example of the HUD apparatus which utilizes the combiner 10 of FIG. 1 is shown in FIG.

  In the present embodiment, as shown in FIG. 1, it is assumed that the combiner 10 is used as a part of a HUD device mounted on a vehicle. Of course, it is also possible to use the combiner 10 in applications other than a HUD device.

  In the example shown in FIG. 2, the HUD unit 100, which is the main body of the HUD device, is disposed in the vicinity of the dashboard of the vehicle. Inside the HUD unit 100, components such as a display unit 110, a mirror 120, and an angle adjustment mechanism 130 are provided.

  The display unit 110 is configured of, for example, a transmissive liquid crystal display panel, and can display visible information to be displayed by the HUD device. Specifically, "60 km / h" can be displayed as character information for speed display, "D" of characters can be displayed as the state of the transmission, and a special pattern for warning can be displayed. (See Figure 11).

  The visible information displayed by the display unit 110 is illuminated by a backlight disposed in the vicinity thereof and projected as an image of light. That is, the image of the light emitted from the display unit 110 is projected onto the combiner 10 via the mirror 120 and is further reflected by the surface of the combiner 10 to be directed to a predetermined eye point 20 which is the driver's observation position.

  Since the reflection of light by the surface of the combiner 10 is used, the display image 30 seen at the position of the eye point 20 exists at a predetermined position in front of the combiner 10 and the window glass of the vehicle as shown in FIG. It is displayed as a virtual image as it is.

<Configuration of the combiner>
The combiner 10 shown in FIG. 1 is composed of a combiner body 11 and a film 12. The combiner body 11 is formed in a plate shape using an optically transparent material. As a specific example, an acrylic resin can be used as a material. Moreover, the combiner main body 11 has sufficient thickness so that a bending or a deformation | transformation may not arise.

  The film 12 is configured using a transparent material having a refractive index equivalent to that of the combiner body 11. For example, the film 12 can be made of polycarbonate. The thickness of the film 12 is sufficiently thinner than the combiner body 11. The film 12 is disposed so as to overlap with one side of the combiner body 11. In the configuration shown in FIG. 3, of the two surfaces (11a and 11b) in the thickness direction of the combiner main body 11, the film 12 is disposed so as to overlap the surface (11b) which is far from the eye point 20. .

  Further, on the surface of the film 12 in contact with the outside air (the surface at a distance from the eye point 20), the fine asperities 12a are formed uniformly over the entire area of the surface. The details of the fine uneven portion 12a will be described later.

<Description of light path>
The optical path in the combiner 10 shown in FIG. 1 is shown in FIG.
The light emitted from the HUD unit 100 shown in FIG. 2 enters the surface 11 a of the combiner main body 11 as incident light 21 as shown in FIG. 3. In this surface 11a, since there is a large difference between the refractive index of the combiner main body 11 and the refractive index of the outside air (air), reflection of light occurs at the boundary between the surface 11a and the outside air. Therefore, a part (about 4%) of the incident light 21 is reflected and travels to the eye point 20 as the reflected light 22.

  Further, a part of the incident light 21 passes through the combiner body 11 and travels to the other surface 11 b. Since the film 12 having the same refractive index is disposed so as to overlap with the surface 11 b, no light reflection occurs at the boundary between the surface 11 b and the film 12. Further, since the fine concavo-convex portion 12a is formed on the surface of the film 12 on the side in contact with the outside air, light is not reflected even on the boundary of the side of the film 12 in contact with the outside air and the outside air All of the light transmitted through the combiner body 11 and the film 12 passes through the combiner 10 as the transmitted light 23, which will be described later.

  Therefore, the light incident on the eye point 20 is not affected by the reflection on the surface 11 b of the combiner body 11 or the film 12. As a result, a plurality of images with different light paths do not overlap, and a clear display is realized.

<Description of the detailed configuration of the film>
The cross-sectional structure of a portion of the film 12 shown in FIG. 1 is shown enlarged in FIG.
As shown in FIG. 4, fine asperities 12 a are formed on the surface of the film 12 in contact with the outside air. The fine asperities 12a are formed by periodically and continuously forming a large number of fine recesses or protrusions at a constant interval smaller than the wavelength of visible light (about 300 nm to 800 nm). It is. In the example shown in FIG. 4, the interval of the unevenness to be formed is set to 100 [nm].

  In addition, each of the large asperities constituting the fine asperities 12a has slopes as shown in FIG. 4 so that the cross-sectional area changes gradually and gradually in response to changes in the height of the film 12 in the thickness direction. It has a surface shape.

<Description of the principle to prevent unnecessary reflections>
<Optical path when the minute uneven portion 12a does not exist>
The incident light and the reflected light in the combiner when the fine asperity 12a of the film 12 is not present are shown in FIG.

  As shown in FIG. 5, when light is incident on the base material of the combiner, a part of the incident light is reflected at the boundary between the outside air and the front surface (incident surface) of the substrate. Furthermore, a portion of the light transmitted through the substrate is reflected at the boundary between the back surface (exit surface) of the substrate and the outside air, and the remaining light passes through the substrate.

The ratio of reflected light of each part can be determined from the Fresnel equation shown below.
R = {(n ₀ cos θ ₀ −n ₁ cos θ ₁ ) / (n ₀ cos θ ₀ + n ₁ cos θ ₁ )} ²
R: reflectance n ₀ : refractive index of air n ₁ : refractive index of substrate (in the case of polycarbonate: 1.585)
θ: angle of incidence

For example, in the case where the refractive index of the base material is 1.5 and the incident angle θ is 0 degree, as shown in FIG. 5, the ratio of reflected light of each part is about 4%.
As shown in FIG. 5, when light is reflected on each of two surfaces of the substrate, a plurality of light beams having different optical paths are projected overlappingly while being misaligned. This reduces the visibility of the display and the display quality. In order to prevent such unnecessary reflection, the above-mentioned fine asperity 12a is provided.

<Distributed state of refractive index on film 12>
The distribution state of the refractive index of each part in the film 12 shown in FIG. 4 is shown in FIG.

  According to "the principle of resonance and sub-wavelength", when the period of the structure becomes short, diffraction and light wave resonance do not occur, and the fine structure can be regarded as a material of the material constituting the period and the average refractive index of air. That is, the refractive index of each part is determined by the average refractive index of the material of the film 12 and the air at the location of the unevenness formed at an interval shorter than the wavelength of visible light, as in the fine unevenness 12a. Moreover, since the slope is formed in the location of the asperity, the cross-sectional area of the asperity changes in accordance with the difference in the position in the height (thickness) direction. Furthermore, the change in cross-sectional area is gradual and continuous. With such a change in cross sectional area, the ratio of the area of the material of the film 12 to the air changes, and the average refractive index changes.

  For the above reasons, the refractive index of each part in the fine concavo-convex part 12a changes continuously and gently according to the height as shown in FIG. That is, in the boundary between the material of the film 12 and the adjacent air in the fine asperity 12a, the refractive index does not change rapidly at any position. Since the reflection of light mainly occurs due to the rapid change of the refractive index, the reflection hardly occurs at the boundary where the refractive index changes only gently, like each part of the fine concavo-convex portion 12a.

<Optical path in the presence of the minute uneven portion 12a>
The incident light and the reflected light in the combiner 10 provided with the film 12 having the fine asperities 12a are shown in FIG.

  As shown in FIG. 7, when light is incident in the direction from the top toward the film 12, the entire incident light directly enters the film 12 and is reflected at the boundary between the fine uneven portion 12 a and the outside air due to the above reasons. Hardly occurs. The light transmitted through the combiner body 11 is partially (eg, 4%) reflected at the boundary between the surface 11 a and the outside air, and the remaining light is emitted from the surface 11 a to the outside air side. The light reflected by the surface 11a passes through the combiner main body 11 and the film 12 again, and is emitted to the outside air side without being reflected also at the boundary between the fine uneven portion 12a and the outside air.

<Specific example of the displayed image>
<When there is no fine uneven portion 12a>
The optical path in the HUD device using the combiner without the fine asperity 12a is shown in FIG. Further, FIG. 9 shows a specific example of the image projected onto the eye point in the situation shown in FIG.

  In the situation shown in FIG. 8, incident light projected from the HUD unit 100 and incident on the combiner is reflected at the boundary between each of the two planes in the thickness direction of the combiner and the outside air. Therefore, the light passing through the plurality of light paths travels to the eye point 20, respectively. Therefore, images of light passing through a plurality of light paths are projected in a state where they are misaligned and overlapped.

  In the display image 30A shown in FIG. 9, two images are displayed overlapping each other in a state in which the positions are shifted in the vertical direction due to the difference in the optical path. That is, the “60 km / h”, “D”, and warning patterns overlap each other in two shifted positions. For this reason, it is necessary to improve visibility and display quality.

<When there is a minute uneven portion 12a>
A specific example of the image projected on the eye point in the HUD device using the combiner 10 shown in FIG. 1 is shown in FIG. 11 as a display image 30B.

  In the case of using the combiner 10 shown in FIG. 1, since the optical path is formed as shown in FIG. 3, only one optical path of the reflected light toward the eye point 20 is provided. Therefore, overlapping of the images as shown in FIG. 9 does not occur, and a clear image can be visually recognized at the eye point 20 as shown in the display image 30B shown in FIG.

  Note that, for example, with respect to a component of light having a wavelength smaller than the interval (100 nm) of the concavo-convex portion 12a, such as ultraviolet light, reflection of about several% may occur at the boundary between the micro concavo-convex portion 12a and the outside air is there. However, since a person who visually recognizes the display of the HUD device can not recognize the components of light other than visible light, no change occurs in the display content even if light such as ultraviolet light is reflected at the location of the fine uneven portion 12a. .

<Modification>
<Description of configuration>
The configuration of a modification of the combiner 10 shown in FIG. 1 is shown in FIG. The combiner 10B shown in FIG. 10 is provided with the combiner main body 11 and the film 12 similarly to the combiner 10 of FIG.

  However, in the combiner 10B, the film 12 is disposed in a state of being overlapped with the face 11a which is closer to the eye point 20 among the two faces 11a and 11b in the thickness direction of the combiner body 11. The fine asperities 12a of the film 12 are formed on the side which is in contact with the outside air.

<Description of light path>
The light emitted from the HUD unit 100 described above and traveling toward the combiner 10B is incident as incident light 21 on the surface of the film 12 (the surface on which the fine uneven portion 12a is present) as shown in FIG.

  As described above, since light is not reflected at the boundary between the fine uneven portion 12a and the outside air, the entire incident light 21 passes through the film 12 and the combiner body 11 of the combiner 10B as it is. Then, on the boundary between the surface 11 b of the combiner main body 11 and the outside air, reflection of about several% occurs due to the rapid change of the refractive index. This travels from the surface 11 b to the eye point 20 as the reflected light 22. The light traveling from the surface 11 b to the eye point 20 again passes through the boundary between the film 12 and the outside air, but since the fine asperities 12 a are also present at this time, no reflection occurs at this boundary.

<Specific example of the displayed image>
Even in the case of using the combiner 10B shown in FIG. 10, only one optical path of light toward the eye point 20 is provided. Therefore, overlapping of the images as shown in the display image 30A of FIG. 9 does not occur.

Second Embodiment
<Description of configuration>
The configuration and optical path of the combiner 10C in this embodiment are shown in FIG. Moreover, the modification of the combiner shown in FIG. 12 is shown in FIG.

  By the way, when the combiner 10B shown in FIG. 10 is used, the reflected light 22 directed to the eye point 20 passes through the film 12 and the combiner main body 11 twice each, so that the display is displayed as compared with the case of the combiner 10. The quality may be slightly degraded. For example, as in a display image 30C shown in FIG. 11, the sharpness may be slightly reduced compared to the display image 30B. The modification described in the second embodiment can suppress the reduction in the sharpness.

  The combiner 10C shown in FIG. 12 is provided with the combiner main body 11 and the film 12 similarly to the combiner 10 of FIG. Further, the film 12 of the combiner 10C is disposed on the side of the surface 11b of the two surfaces 11a and 11b in the thickness direction of the combiner main body 11, which is the farthest from the eye point 20.

  Further, in the combiner 10C shown in FIG. 12, the film 12 is firmly fixed to the combiner body 11 by adhesion. Therefore, as shown in FIG. 12, the adhesive layer 13 is present at the boundary between the combiner body 11 and the film 12.

  The adhesive layer 13 is transparent, and the thickness of the adhesive layer 13 is much smaller than the combiner body 11 and the film 12. However, the adhesive layer 13 may have a slight optical influence such as light attenuation, scattering, and reflection. That is, as the difference between the two display images 30B and 30C shown in FIG. 11, the sharpness and the display quality may be slightly deteriorated due to the influence of the adhesive layer 13.

  Therefore, in order to suppress the influence of the adhesive layer 13 on the light reaching the eye point 20, as shown in FIG. 12, the film 12 has an eye point 20 out of the two surfaces 11 a and 11 b in the thickness direction of the combiner body 11. Are disposed on the side of the surface 11b which is the farthest from.

<Description of light path>
The light emitted from the HUD unit 100 shown in FIG. 2 enters the surface 11 a of the combiner main body 11 as incident light 21 as shown in FIG. 12. At the boundary between the ambient air and the surface 11a, there is a large difference between the refractive index of the combiner body 11 and the refractive index of the ambient air (air), so that light is reflected. Therefore, a part (about 4%) of the incident light 21 is reflected and travels to the eye point 20 as the reflected light 22.

  Further, a part of the incident light 21 passes through the combiner body 11 and travels to the other surface 11 b. Further, a portion of the incident light 21 passes through the adhesive layer 13 towards the film 12. Since the film 12 having the same refractive index is disposed so as to overlap the adhesive layer 13, no reflection of light occurs at the boundary between the adhesive layer 13 and the film 12. In addition, since the fine asperities 12a are formed on the surface of the film 12 on the side in contact with the outside air, light is not reflected on the boundary between the surface on the side of the film 12 in contact with the outside air and the outside air. The entire light transmitted through 11 and the film 12 passes through the combiner 10 as the transmitted light 23.

  Therefore, although the light reflected in the boundary of the surface 11b and the adhesive layer 13 is slightly contained, the light which has not passed through the adhesive layer 13 becomes dominant as the reflected light 22 incident on the eye point 20. Therefore, there is no influence of the reflection or the like on the surface 11 b of the combiner main body 11 or each part of the film 12. Thereby, clear display is realized.

<Description of the difference from the modification>
On the other hand, in the combiner 10D of the modified example shown in FIG. 13, the film 12 is disposed on the side 11 a of the two faces 11 a and 11 b in the thickness direction of the combiner body 11 closer to the eye point 20. It is

  Therefore, in the case of the combiner 10D of FIG. 13, the incident light 21 emitted from the HUD unit 100 passes through the film 12, the adhesive layer 13 and the combiner body 11 toward the right in FIG. A part is reflected by the surface 11b. Furthermore, the reflected light reflected by the surface 11 b sequentially passes through the combiner body 11, the adhesive layer 13, and the film 12 toward the left in FIG. 13 and travels toward the eye point 20 as the reflected light 22 B. That is, in the case of using the combiner 10D, the reflected light 22B incident on the eye point 20 is dominated by the light passing through the adhesive layer 13 twice.

  Accordingly, in the case of the combiner 10C of FIG. 12, the influence of the adhesive layer 13 on the reflected light 22 can be minimized while in the case of the combiner 10D, the reflected light 22B passes through the adhesive layer 13 twice. Therefore, for example, it is susceptible to the influence of attenuation of light intensity, scattering of light, reflection, and the like. For this reason, the image visually recognized by the reflected light 22B of FIG. 13 is contrasted with the image visually recognized by the reflected light 22B of FIG. 13 while the outline is visually recognized clearly as shown in the display image 30B of FIG. Is blurred as shown in a display image 30C of FIG.

  As a result, even when the film 12 is adhered to fix the film 12 to the combiner body 11, the film 12 may be attached from the eye point 20 among the two surfaces 11a and 11b in the thickness direction of the combiner body 11 like the combiner 10C. By disposing on the side of the surface 11b where the distance is longer, the influence of the adhesive layer 13 on the reflected light 22 can be minimized, and the reduction in the definition of display can be prevented.

DESCRIPTION OF SYMBOLS 10, 10B, 10C, 10D Combiner 11 Combiner main body 12 Film 12a Fine concavo-convex part 13 Adhesive layer 20 Eye point 21 Incident light 22 Reflected light 23 Transmitted light 30, 30A, 30B, 30C Display image 100 HUD unit 110 Display part 120 Mirror 130 Angle adjustment mechanism

Claims (4)

A combiner body which is a transparent plate-like optical member,
A film disposed on the surface of the combiner body;
Equipped with
In the film, a recess or a protrusion is periodically and continuously formed on the other surface opposite to the one surface adjacent to the surface of the combiner main body, and the interval between the recess or the protrusion for one cycle Is shorter than the wavelength of visible light,
As the position in the height direction of the convex portion moves from the bottom side to the top side, the cross-sectional area of the convex portion gradually decreases, and the average refractive index of the material of the film and the air in the convex portion is the height Correspondingly, it changes continuously and gradually, and no reflection occurs at the boundary between the material of the film and the adjacent air at the convex portion,
A combiner characterized by The combiner body has two planes intersecting a straight line connecting an eye point, which is a position at which the reflected light from the combiner body is observed, and the combiner body,
The film is disposed on one of two sides of the combiner body,
The combiner according to claim 1, characterized in that: The film is disposed on one of the two sides of the combiner body which is at a greater distance from the eye point.
A combiner according to claim 2, characterized in that. The film is adhered to the surface of the combiner body via a predetermined adhesive layer having a refractive index equal to the refractive index of the film, with one surface close to the surface of the combiner body being bonded. Placed on the surface of the body,
A combiner according to claim 3, characterized in that.