JP2016170374A - Transflective sheet, display device, and manufacturing method for transflective sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transflective sheet, a display device, and a manufacturing method for a transflective sheet, which can suppress the phenomenon that external light becomes unclear.SOLUTION: A transflective sheet 20 transmits the external light from a rear surface and reflects the video light, and emits the video light and the external light from an emission surface. The transflective sheet 20 includes: a first optical shape layer 22 on which a plurality of first inclined surfaces 30 inclined relative to the emission surface is aligned; a second optical shape 23 stacked on a surface of the first optical shape layer 22 on the first inclined surface side; a reflection layer 25 provided for at least a part on the first inclined surface 30, reflecting part of the video light, and transmitting the other; and an intermediate layer 32 disposed between the adjacent first inclined surfaces 30 and at the boundary between the first optical shape layer 22 and the second optical shape layer 23. The refractive index n1 of the first optical shape layer 22, the refractive index n2 of the second optical shape layer 23, and the refractive index n3 of the intermediate layer 32 satisfy the relation of n2<n3<n1 or n1<n3<n2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a transflective sheet, a display device, and a method for producing a transflective sheet that transmit external light such as a background and reflect video light.

Conventionally, there has been proposed a head-mounted display device that allows an observer to observe an image source such as an LCD (Liquid Crystal Display) via an optical system (for example, Patent Document 1).
In such a head-mounted display device, for example, a light guide plate is arranged at a position facing the image source, and the image light displayed by the image source is positioned at the position corresponding to the eyes of the observer by the light guide plate. To the viewer side through the reflective layer. In such a display device, the viewer's field of view is blocked by the displayed image, so a magic mirror is used for the reflective layer, etc., so that the image light and the external light can be seen so as to overlap each other. There is a case.

Here, the light guide plate is provided with a plurality of unit optical shapes arranged in the light guide direction. The unit optical shape is formed in a substantially triangular shape in cross section parallel to the arrangement direction and parallel to the thickness direction of the light guide plate. It consists of a surface.
The light guide plate having such a unit optical shape is manufactured, for example, by forming another layer on the surface of the layer having the unit optical shape so as to cover the unit optical shape. Therefore, the light guide plate is composed of a layer on the back side and a layer on the viewer side (light output side) with each surface of the unit optical shape as a boundary. The back side layer and the viewer side layer are formed with the same refractive index in order to avoid refraction of transmitted light, etc., but even if the same material is used, the refractive index is very small. Differences can occur. In addition, depending on the configuration of the light guide plate, the same resin cannot be used or it cannot be molded under the same conditions, so the refractive index may not be completely the same.

  Here, external light incident from the back surface of the light guide plate may be incident on the facing surface facing the reflecting surface of the unit optical shape, and a minute amount is formed between the back surface layer and the viewer side layer. When there is a large difference in refractive index, the external light is totally reflected on the surface and reaches the observer side in a state inclined with respect to the normal direction of the light exit surface, resulting in a double image, that is, a ghost. In some cases, however, the light from the outside world becomes unclear.

Special table 2011-509417 gazette

  An object of the present invention is to provide a transflective reflection sheet, a display device, and a method of manufacturing a transflective reflection sheet that can prevent the outside light from becoming unclear.

The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.
The invention of claim 1 is a transflective reflection sheet (20) that transmits external light from the back and reflects image light, and emits the image light and external light from a light exit surface. A first optical shape layer (22) in which a plurality of first inclined surfaces (30) inclined with respect to the light exit surface are arranged, and a layer on the side of the first optical shape layer on which the first inclined surface is provided. The second optical shape layer (23) to be formed and the reflection layer (25) that is formed on at least a part of the first inclined surface, reflects a part of the image light, and transmits the other, and is adjacent to the reflection layer (25). An intermediate layer (32) provided between the first inclined surfaces and at the boundary between the first optical shape layer and the second optical shape layer, wherein the refractive index of the first optical shape layer is n1, When the refractive index of the second optical shape layer is n2, the refractive index n3 of the intermediate layer is n1> n For satisfies n2 <n3 <n1, the case of n1 <n2, a semi-transmission type reflection sheet according to claim, to satisfy n1 <n3 <n2.
According to a second aspect of the present invention, in the transflective reflection sheet (20) according to the first aspect, the refractive index n3 of the intermediate layer (32) is the second optical shape from the first optical shape layer (22) side. The transflective sheet is characterized in that the refractive index fluctuates from the refractive index n1 side to the refractive index n2 side toward the shape layer (23) side.
A third aspect of the present invention is a display device comprising: the transflective reflection sheet (20) according to the first or second aspect; and an image source (11) that emits image light to the transflective reflection sheet. (1).
Invention of Claim 4 is a manufacturing method of the semi-transmissive reflection sheet which forms the semi-transmissive reflection sheet (20) of Claim 1 or Claim 2, Comprising: Said 1st optical shape layer (22) is made. A first molding step of filling a resin to be formed into a mold to form the first optical shape layer (22 ') in a semi-cured state, and the first optical in a semi-cured state formed by the first molding step A reflective layer forming step of forming the reflective layer (25) on the first inclined surface (30) of the shape layer; and the second optical shape layer on the first inclined surface side surface of the first optical shape layer. The resin forming (23) is filled and cured to form the second optical shape layer, and the semi-cured first optical shape layer is cured to be between the adjacent first inclined surfaces. The intermediate layer (32) is formed at the boundary between the first optical shape layer and the second optical shape layer. And a second forming step to be manufactured.

  According to the present invention, it is possible to prevent external light from becoming unclear.

It is a figure explaining the head mounting type display device of an embodiment. It is a figure explaining the detail of the light-guide plate of embodiment. It is a figure which shows an example of the locus | trajectory of the external light which injects into the light-guide plate of a comparative example. It is a figure which shows an example of the manufacturing method of the light-guide plate of embodiment. It is a figure explaining the transflective reflection sheet of a deformation | transformation form.

Embodiments of the present invention will be described below with reference to the drawings. In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
Numerical values such as dimensions and material names of the respective members described in the present specification are examples of the embodiment, and the present invention is not limited thereto, and may be appropriately selected and used.
In this specification, terms that specify shape and geometric conditions, for example, terms such as parallel and orthogonal, are strictly meanings, have similar optical functions, and can be regarded as parallel and orthogonal It also includes a state having an error of.

(Embodiment)
FIG. 1 is a diagram illustrating a head-mounted display device 1 according to this embodiment. FIG. 1 is a view of the display device 1 as viewed from above in the vertical direction.
In addition, in the figure shown below including FIG. 1 and the following description, in order to make an understanding easy, the vertical direction in the state where the observer has mounted the display device 1 on the head is defined as the Z direction, and the horizontal direction is defined as X. Direction and Y direction. Of these horizontal directions, the direction in which the video light entering the light guide plate is guided (the left-right direction of the light guide plate) is the X direction, and the direction perpendicular to the direction (thickness direction of the light guide plate) is the Y direction. . The −Y side in the Y direction is the observer side, and the + Y side is the back side.

The display device 1 is a so-called head mounted display that an observer wears on the head and displays an image in front of the eyes of the observer. As shown in FIG. 1, the head-mounted display device 1 of the present embodiment includes a video source 11, a projection optical system 12, and a light guide plate 20 inside a glasses frame (not shown). When the observer wears the eyeglass frame on the head, the image of the image source 11 can be visually recognized by the observer via the light guide plate (semi-transmissive reflection sheet) 20 or the like. Specifically, the display device 1 enters video light displayed on the video source 11 into the light guide plate 20 through the projection optical system 12 and guides it in the + X direction within the light guide plate 20. The image information is displayed in front of the eyes E of the observer who wears the display device 1 on the head by reflecting in the -Y direction orthogonal to the light direction.
In addition, the display device 1 has a so-called see-through function that allows a part of light from the outside world to pass through the light guide plate 20 and reach the observer side so that the image and the light from the outside world can be seen superimposed. In the present embodiment, an example in which a transflective reflection sheet is applied to the light guide plate 20 will be described. The transflective reflection sheet is a generic term for a sheet that transmits a part of incident light and reflects others, and is not limited to a sheet having a transmittance and a reflectance of 50%.

The video source 11 is a micro display that displays video light. For example, a transmissive liquid crystal display device, a reflective liquid crystal display device, an organic EL, or the like can be used. For example, a micro display having a diagonal of 1 inch or less is used as the video source 11.
The projection optical system 12 is an optical system composed of a plurality of lens groups that project image light emitted from the image source 11 as parallel light.
The light guide plate 20 is a substantially flat transparent member that guides light. In this embodiment, the light guide plate 20 is formed in a trapezoidal column shape in which the shape viewed from the vertical direction (Z direction) is formed in a substantially trapezoidal shape. . As shown in FIG. 1, the light guide plate 20 is parallel to each other and faces the first total reflection surface 20 b and the second total reflection surface 20 c facing each other, and the first total reflection surface 20 b and A reflecting surface 20a inclined with respect to the second total reflection surface 20c is provided.

The reflection surface 20a is inclined at a predetermined angle with respect to the first total reflection surface 20b and the second total reflection surface 20c, and a reflection film 27 is formed on the entire surface. The reflection surface 20 a reflects the image light incident in the light guide plate 20 to the first total reflection surface 20 b side by the reflection film 27. Here, the reflection film 27 is formed of a metal having high light reflectivity, for example, aluminum, silver, nickel, or the like. In the present embodiment, the reflective film 27 is formed by evaporating aluminum. The reflective film 27 is not limited to this, and may be formed by sputtering a metal having high light reflectivity, transferring a metal foil, or applying a paint containing a metal thin film.
The reflection surface 20a is inclined in the range of 25 ° to 40 ° with respect to the first total reflection surface 20b in order to cause the first total reflection surface 20b to totally reflect the image light reflected by the reflection film 27.

The first total reflection surface 20 b is a surface that is parallel to the XZ plane and that is located on the viewer side (−Y side) among the surfaces that form the light guide plate 20, and the image light reflected by the reflection film 27 is the first. 2 Total reflection is performed toward the total reflection surface 20c side. The first total reflection surface 20b totally reflects the image light totally reflected on the second total reflection surface 20c toward the second total reflection surface 20c again.
As for the 1st total reflection surface 20b, the edge part of the -X side becomes a light-incidence surface which injects the image light projected from the image source 11, and the edge part of + X side is the 1st inclination. It is a light exit surface that emits image light reflected by the surface 30 and the second inclined surface 31 (described later) to the outside of the light guide plate 20.
The second total reflection surface 20c is a surface (surface on the side away from the observer side) that is parallel to the XZ plane and located on the back side (+ Y side) among the surfaces that form the light guide plate 20. The image light totally reflected on the first total reflection surface 20b is totally reflected toward the first total reflection surface 20b side.
As described above, the image light reflected by the reflection film 27 is guided in the + X direction (light guide direction) in the light guide plate 20 by repeating total reflection between the first total reflection surface 20b and the second total reflection surface 20c. It will be illuminated.

Next, the layer configuration of the light guide plate 20 will be described.
FIG. 2 is a diagram illustrating details of the light guide plate 20 of the present embodiment.
As shown in FIG. 2, the light guide plate 20 includes, in order from the observer side (−Y side), a base material portion 26, a bonding layer 24, a second optical shape layer 23, a first optical shape layer 22, and a base material portion 21. Are stacked.
The base material part 21 and the base material part 26 are flat members that serve as the basis of the light guide plate 20. For example, highly transparent acrylic resin, styrene resin, acrylic styrene resin, polycarbonate resin, and alicyclic polyolefin resin. Etc. are formed.

The base material portion 21 is a layer provided on the most back side of the light guide plate 20, and the back side (+ Y side) surface is the above-described second total reflection surface 20 c. The surface on the back side of the base member 21 is desirably formed smoothly (for example, 90 or more with a glossiness of 60 degrees) from the viewpoint of suppressing the diffusion of incident light.
Moreover, the base material part 26 is a layer provided on the most observer side of the light guide plate 20, and the surface on the observer side (−Y side) is the first total reflection surface 20b described above. The surface on the back side of the base material part 26 is desirably formed to be smooth (for example, 90 or more with a glossiness of 60 degrees) from the viewpoint of suppressing the diffusion of incident light.

The first optical shape layer 22 is a layer provided on the surface on the viewer side (−Y side) of the base material portion 21. The first optical shape layer 22 is made of an ultraviolet curable resin such as epoxy acrylate having high light transmittance or urethane acrylate, and its refractive index is the same as that of the base material portion 21 and the base material portion 26 described above. Refractive index. For the first optical shape layer 22, in addition to the above-described resin, a heat polymerization type resin (acrylic resin (PMMA)), a two-component curable resin, or the like can be used.
As shown in FIG. 1, the first optical shape layer 22 is a surface on the viewer side (−Y side), and a plurality of first inclined surfaces 30 are provided in the vicinity of the end on the + X side.

The first inclined surface 30 extends in the vertical direction (Z direction), and a plurality of the first inclined surfaces 30 are arranged along the light guide direction (X direction) of the video light.
The first inclined surface 30 is a surface on which image light totally reflected from the first total reflection surface 20b is directly incident, and a light exit surface (first total reflection surface 20b, surface on the observer side of the second optical shape layer 23). ) And the end portion t1 on the + X side is positioned closer to the observer (light emission) side (−Y side) than the end portion v1 on the −X side. A reflection layer 25 is formed on the entire surface of the first inclined surface 30, that is, between the first inclined surface 30 and the second inclined surface 31 (described later).

The second optical shape layer 23 is a layer provided on the viewer-side surface of the first optical shape layer 22 so as to cover the surface of the first optical shape layer 22 on the first inclined surface 30 side. The 2nd optical shape layer 23 is formed from ultraviolet curable resin, such as epoxy acrylate with high light transmittance, and urethane acrylate. For the second optical shape layer 23, it is also possible to use a heat polymerization type resin (acrylic resin (PMMA)), a two-component curable resin, or the like in addition to the above-described resin.
The surface on the observer side of the second optical shape layer 23 is a surface bonded to the base material portion 26 via the bonding layer 24, and light that passes from the second optical shape layer 23 to the base material portion 26. The light exit surface. The light output surface of the second optical shape layer 23 is parallel to the first total reflection surface 20 b (light output surface, XZ plane) of the light guide plate 20.
The base part 26 provided on the observer side of the second optical shape layer 23 may be omitted, and the surface on the observer side of the second optical shape layer 23 may be the light exit surface of the light guide plate 20.

In the second optical shape layer 23, a second inclined surface 31 corresponding to the first inclined surface 30 described above is formed on the surface (back surface, + Y side surface) facing the first optical shape layer 22.
The second inclined surface 31 extends in the vertical direction (Z direction), and a plurality of second inclined surfaces 31 are arranged along the light guide direction (X direction) of the video light. The second inclined surface 31 is a surface on which the image light totally reflected from the first total reflection surface 20b is directly incident, and a light exit surface (first total reflection surface 20b, surface on the observer side of the second optical shape layer 23). The + X side end t2 is positioned closer to the observer (light emission) side (−Y side) than the −X side end v2. The second inclined surface 31 faces the first inclined surface 30 and is a surface parallel to the first inclined surface 30, and as described above, between the second inclined surface 31 and the first inclined surface 30. A reflective layer 25 is provided throughout.

Here, an angle between the first inclined surface 30 and the second inclined surface 31 and a surface (XZ plane) parallel to the first total reflection surface 20b (light-emitting surface) is α. The arrangement pitch of the first inclined surface 30 and the second inclined surface 31 is P. Further, the height of the first inclined surface 30 (the dimension from the end t1 on the observer side to the end v1 on the back side of the first inclined surface 30 in the thickness direction (Y direction) of the light guide plate) is h1. The height of the second inclined surface 31 (the dimension from the end t2 on the observer side to the end v2 on the back side of the second inclined surface 31 in the thickness direction (Y direction) of the light guide plate) is h2. In the present embodiment, h1 = h2.
In the present embodiment, an example in which the arrangement pitch P is equal to the width dimension in the arrangement direction (X direction) of the first inclined surface 30 and the second inclined surface 31 is shown, but is larger than the width dimension of each inclined surface. It may be made larger.

The first inclined surface 30 and the second inclined surface 31 of the present embodiment have a constant arrangement pitch P and the like, but the angle α gradually increases toward the image light traveling side (+ X side). A description will be given of an example in which the heights h1 and h2 are also increased. However, the present invention is not limited to this. For example, the arrangement pitch P, the angle α, and the heights h1 and h2 may be formed constant.
In the present embodiment, the first optical shape layer 22 and the second optical shape layer 23 are each formed of an ultraviolet curable resin of epoxy acrylate.

FIG. 3 is a diagram illustrating an example of a trajectory of external light incident on the light guide plate of the comparative example.
Here, the first optical shape layer 22 and the second optical shape layer 23 are basically formed by using the same material so that the refractive indexes of both layers are equal. May cause a difference in refractive index (for example, 1/1000 or less). In that case, as in the light guide plate of the comparative example shown in FIG. 3, the first optical shape layer 22 and the second optical shape layer 23 become a boundary between the adjacent first inclined surfaces (third inclined surfaces). A boundary surface is formed.

  Therefore, for example, when the refractive index of the first optical shape layer is larger than the refractive index of the second optical shape layer, as shown in FIG. 3A, a part of the external light transmitted through the first optical shape layer. G10 is totally reflected at the boundary surface and reaches the observer side in a state slightly inclined with respect to the normal direction of the light exit surface. In addition, when the refractive index of the first optical shape layer is smaller than the refractive index of the second optical shape layer, as shown in FIG. 3B, the external environment transmitted through the first optical shape layer and the second optical shape layer A part of the light G11 is totally reflected at the boundary surface and reaches the observer side with a slight inclination with respect to the normal direction of the light exit surface. In this way, when the external light reaches the observer side with a slight inclination with respect to the normal direction of the light exit surface, the slightly inclined state in the vicinity of the external light G0 emitted in the front direction. The external light G10 and the light G11 are emitted, a double image, so-called ghost, is generated, and the external light visually recognized by the observer becomes unclear.

Therefore, the light guide plate 20 of the present embodiment is between the first inclined surfaces 30 (second inclined surfaces 31) adjacent to each other, and is the boundary between the first optical shape layer 22 and the second optical shape layer 23, that is, the above-described. An intermediate layer 32 is provided at a position where the boundary surface of the light guide plate of the comparative example exists.
The intermediate layer 32 is formed of the same material as the first optical shape layer 22 and the second optical shape layer 23, that is, an ultraviolet curable resin of epoxy acrylate in this embodiment. Further, when the refractive index of the first optical shape layer 22 is n1 and the refractive index of the second optical shape layer 23 is n2, the refractive index n3 of the intermediate layer 32 is n2 <n3 when n1> n2. When <n1 is satisfied and n1 <n2, n1 <n3 <n2 is satisfied.

The refractive index n3 of the intermediate layer 32 gradually varies from the refractive index n1 side to the refractive index n2 side as it goes from the first optical shape layer 22 side to the second optical shape layer 23 side. For example, when the refractive index n1 of the first optical shape layer is n1 = 1.53 and the refractive index n2 of the second optical system image layer is n2 = 1.55, the refractive index n3 of the intermediate layer 32 is It fluctuates so as to gradually increase from the n1 (1.53) side to the n2 (1.55) side as it goes from the first optical shape layer 22 side to the second optical shape layer 23 side.
By providing the intermediate layer 32 in this way, the light guide plate 20 is caused by the above-described boundary surface even if there is a difference in refractive index between the first optical shape layer 22 and the second optical shape layer 23. Total reflection of light can be suppressed, and the above-described double image (ghost) can be prevented from being generated.

  The bonding layer 24 is an adhesive that bonds the base material portion 26 and the second optical shape layer 23. The bonding layer 24 is made of a material having a refractive index equivalent to these layers so as not to refract the image light transmitted between the base material portion 26 and the second optical shape layer 23, for example, a highly light-transmitting urethane acrylate resin, It is formed of an epoxy acrylate resin, an acrylic adhesive, a silicone adhesive, or the like.

The reflective layer 25 is a so-called magic mirror (half mirror) that reflects part of incident light and transmits the other part. The ratio between the reflectance and the transmittance of the reflective layer 25 can be set as appropriate, but the transmittance is in the range of 40 to 60% from the viewpoint of favorably reflecting the image light and favorably transmitting the external light. It is desirable that The reflective layer 25 of the present embodiment is formed in a half mirror shape with both reflectance and transmittance of 50%.
The reflective layer 25 is formed of a highly light reflective metal, for example, aluminum, silver, nickel, or the like, on the surface of the first inclined surface 30, that is, between the first inclined surface 30 and the second inclined surface 31. In the present embodiment, the reflective layer 25 is formed by evaporating aluminum. The reflective layer 25 is not limited to this, and may be formed by sputtering a metal having high light reflectivity, transferring a metal foil, or applying a paint containing a metal thin film.

The reflective layer 25 of the present embodiment is formed to a thickness of about 100 mm by vapor deposition of aluminum. However, if the light reflectance and transmittance can be set within the above-mentioned preferable ranges, the thickness depends on the material and the like. Can be set freely.
Here, from the viewpoint of efficiently reflecting the image light and emitting the light from the light guide plate 20, the angle α of the first inclined surface 30 and the second inclined surface 31 is within the range of 20 ° ≦ α ≦ 35 °. It is desirable that the height h1 of the inclined surface 30 is formed within a range of 20 μm ≦ h1 ≦ 700 μm, and the height h2 of the second inclined surface 31 is formed within a range of 20 μm ≦ h2 ≦ 700 μm. The arrangement pitch P of the first inclined surface 30 and the second inclined surface 31 is preferably formed within a range of 50 μm ≦ P ≦ 1000 μm.

Next, the operation of the image light L and the external light G incident on the light guide plate 20 of the present embodiment will be described.
As shown in FIG. 1, the video light L emitted from the video source 11 enters the first total reflection surface 20 b of the light guide plate 20 through the projection optical system 12. The image light L that has entered the light guide plate 20 enters the reflection film 27 of the reflection surface 20a and is reflected toward the first total reflection surface 20b. Then, the image light L enters the first total reflection surface 20b and is totally reflected toward the second total reflection surface 20c, and then enters the second total reflection surface 20c and enters the first total reflection surface 20b. And totally reflected. Thus, by repeating total reflection between the first total reflection surface 20b and the second total reflection surface 20c, the video light L is guided from the −X side to the + X side of the light guide plate 20, and the first optical The light enters the reflective layer 25 provided between the shape layer 22 and the second optical shape layer 23.

In the light guide plate 20 of the present embodiment, as shown in FIG. 1, the video light L is totally reflected twice on the first total reflection surface 20b and is totally reflected once on the second total reflection surface 20c. However, the present invention is not limited to this, and the total reflection may be repeated more or less on each surface.
Of the image light incident on the reflective layer 25, a part of the image light L1 is reflected in a direction (−Y direction) substantially perpendicular to the first total reflection surface 20b in the reflective layer 25, as shown in FIG. Then, the light is emitted from the first total reflection surface 20b toward the observer's eye E. Further, other image light passes through the reflective layer 25 and enters the first optical shape layer 22, but most of the light is emitted from the back side of the light guide plate 20.

As shown in FIG. 1, the external light G enters the light guide plate 20 from the second total reflection surface 20 c on the back side (+ Y side) of the light guide plate 20. A part of the outside light G that enters the light guide plate 20 enters the reflection layer 25. Then, as shown in FIG. 2, a part of the light G1 passes through the reflection layer 25 and exits from the first total reflection surface 20b (light output surface) toward the observer's eye E. Further, other light is reflected to the back side (+ Y side) at the interface between the reflective layer 25 and the first optical shape layer 22. In addition, the light is inclined in the X direction with respect to the thickness direction of the light guide plate 20. In this case, a part of the external light incident from the back surface of the light guide plate 20 enters the intermediate layer 32. The refractive index n3 of the intermediate layer 32 has a second optical shape from the first optical shape layer 22 side. Since the refractive index n1 gradually changes from the refractive index n1 toward the layer 23 side, most of the light is emitted to the viewer side without being totally reflected by the intermediate layer 32.

Next, a method for manufacturing the light guide plate 20 of the present embodiment will be described.
FIG. 4 is a diagram illustrating a method for manufacturing the light guide plate 20 of the present embodiment. Each drawing in FIG. 4 is a diagram illustrating a process until the light guide plate 20 is manufactured.
As shown in FIG. 4A, an uneven shape having an inclined surface corresponding to the first inclined surface 30 is provided by applying an ultraviolet curable resin of epoxy acrylate to the surface on the viewer side of the base material portion 21. The first optical shape layer 22 ′ in a semi-cured state is formed by pressing the mold and irradiating it with ultraviolet rays to make it semi-cured and then releasing from the mold (first molding step). At this time, a boundary surface 30a is formed between the first inclined surfaces 30 adjacent in the light guide direction (X direction).
Next, as shown in FIG. 4B, the reflective layer 25 is formed by vapor-depositing aluminum on the first inclined surface 30 of the first optical shape layer 22 ′ in the semi-cured state by vacuum vapor deposition (reflection). Layer forming step). The reflective layer 25 may be formed by sputtering or applying a paint containing a light reflecting material.

Subsequently, as shown in FIG. 4 (c), the surface on the first inclined surface 30 side of the first optical shape layer 22 ′ in the semi-cured state is filled with an ultraviolet curable resin of epoxy acrylate to form a flat surface. The second optical shape layer 23 is formed and the resin constituting the first optical shape layer 22 is cured by, for example, releasing the mold after being pressed by the formed mold and being cured by irradiating with ultraviolet rays. The first optical shape layer 22 is also formed (second molding step).
At this time, the ultraviolet curable resin constituting the second optical shape layer 23 is filled in the surface on the first inclined surface 30 side of the semi-cured first optical shape layer 22 ′, so that The intermediate layer 32 is formed at the site where the boundary surface 30a is mixed with the resin of the one optical shape layer 22 ′. By forming the intermediate layer 32 in this way, the refractive index n3 of the intermediate layer 32 satisfies n1 <n3 <n2 or n2 <n3 <n1, and the second optical shape layer from the first optical shape layer 22 side. As it goes to the 23rd side, it gradually changes from the n1 side to the n2 side.
In addition, a solvent (for example, an organic solvent) is mixed in advance with the ultraviolet curable resin constituting the second optical shape layer 23, and the resin of the first optical shape layer 22 ′ and the second optical shape layer 23 are mixed at the boundary surface 30 a. The intermediate layer 32 may be formed more efficiently so that the resin is more easily mixed.

Next, as shown in FIG. 4 (d), the second optical shape layer 23 formed on the first optical shape layer 22 and the flat substrate portion 26 are bonded together via the bonding layer 24. Then, a laminated body in which the base material portion 26, the bonding layer 24, the second optical shape layer 23, the first optical shape layer 22, and the base material portion 21 are sequentially laminated is completed.
Finally, after cutting this laminate into a predetermined shape, the corner on the back side (+ Y side) on the −X side (the side opposite to the side where the reflective layer 25 is formed) is processed and reflected. A reflective film 27 is formed by forming a surface 20a and depositing aluminum on the reflective surface 20a by vacuum deposition or the like. Thus, the light guide plate 20 is completed.
In the above description, the example in which the reflective layer 25 and the second optical shape layer 23 are sequentially formed on the surface of the manufactured first optical shape layer 22 on the viewer side is shown, but the present invention is not limited to this. Alternatively, the second optical shape layer 23 may be formed first, and the reflective layer 25 and the first optical shape layer 22 may be sequentially formed on the back surface of the second optical shape layer 23.

As described above, in the light guide plate 20 of the present embodiment, when the refractive index of the first optical shape layer 22 is n1 and the refractive index of the second optical shape layer 23 is n2, the refractive index n3 of the intermediate layer 32 is When n1> n2, n2 <n3 <n1 is satisfied, and when n1 <n2, n1 <n3 <n2 is satisfied. As a result, even if light from the outside is incident on the intermediate layer 32 from the back side, the light guide plate 20 can transmit most of the light to the viewer side without being totally reflected, and a double image (ghost) is generated. Therefore, it is possible to prevent the external light visually recognized by the observer from becoming unclear.
In the light guide plate 20, the refractive index n3 of the intermediate layer 32 varies from the refractive index n1 to the refractive index n2 as it goes from the first optical shape layer 22 side to the second optical shape layer 23 side. Can be gradually changed, and the occurrence of total reflection in the intermediate layer 32 can be more efficiently reduced.
In the method of manufacturing the light guide plate 20, the first optical shape layer 22 ′ in a semi-cured state is filled with a resin that forms the second optical shape layer 23 on the surface on the first inclined surface 30 side and cured to form the second optical shape. Since the layer 23 is formed and the semi-cured first optical shape layer 22 ′ is cured, the intermediate layer 32 can be easily and efficiently formed between the adjacent first inclined surfaces 30.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made as in the modifications described later, and these are also included in the present invention. Within the technical scope. In addition, the effects described in the embodiments are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments. It should be noted that the above-described embodiment and modifications described later can be used in appropriate combination, but detailed description thereof is omitted.

(Deformation)
FIG. 5 is a diagram illustrating a modified transflective reflection sheet.
(1) In the above-described embodiment, the example in which the transflective reflection sheet is applied to the light guide plate 20 has been described. However, the present invention is not limited to this. For example, as shown in FIG. 5, the transflective reflective sheet 20 reflects the image light from the image source 11 of the display device 1 directly to the viewer side in the reflective layer 25 without guiding the image light. It can also be applied to. In this case, the angle α of the first inclined surface 30 and the second inclined surface 31 is in the range of 5 ° ≦ α ≦ 35 °, and the height h1 of the first inclined surface 30 is in the range of 5 μm ≦ h1 ≦ 700 μm. The height h2 of the second inclined surface 31 is preferably in the range of 5 μm ≦ h2 ≦ 700 μm, and the arrangement pitch P of the first inclined surface 30 is preferably in the range of 50 μm ≦ P ≦ 1000 μm.
The transflective reflection sheet can also be applied to a head-up display mounted on a front window of an automobile or the like, a screen that transmits light from the outside such as a background, and the like.

(2) In the above-described embodiment, either or both of the back surface of the light guide plate 20 (the back surface of the base material portion 21) and the viewer side surface of the light guide plate 20 (the surface on the viewer side of the base material portion 26). The surface may be subjected to a hard coat treatment for the purpose of preventing scratches. In this hard coat treatment, for example, an ultraviolet curable resin (for example, urethane acrylate) having a hard coat function is applied to one or both of the back surface and the viewer side surface of the light guide plate 20 to form a hard coat layer. May be formed.

(3) In the above-described embodiment, the example in which the reflective layer 25 is provided on the entire surface of the first inclined surface 30, that is, between the first inclined surface 30 and the second inclined surface 31, is illustrated. However, it may be provided on a part of the first inclined surface 30. For example, the reflective layer 25 may be provided only in a region on the + X side of the first inclined surface 30, that is, a region that contributes to reflection of video light.

(4) In the above-described embodiment, the light guide plate 20 has an example in which the first total reflection surface 20b and the surface on which the image light enters are formed in the same plane. However, the present invention is not limited to this. The first total reflection surface and the surface on which the image light enters may be formed as different surfaces.
In the above-described embodiment, the light guide plate 20 has an example in which the first total reflection surface 20b and the light exit surface from which the image light exits are formed in the same plane. However, the present invention is not limited to this. The first total reflection surface and the surface from which the image light exits may be formed as different surfaces.

DESCRIPTION OF SYMBOLS 1 Display apparatus 11 Image source 12 Projection optical system 20 Light guide plate 20a Reflective surface 20b 1st total reflection surface 20c 2nd total reflection surface 21 Base material part 22 1st optical shape layer 23 2nd optical shape layer 24 Bonding layer 25 Reflection layer 26 Base material portion 27 Reflective film 30 First inclined surface 31 Second inclined surface 32 Intermediate layer E Eye of observer

Claims (4)

A transflective reflective sheet that transmits external light from the back and reflects video light, and emits the video light and external light from a light exit surface;
A first optical shape layer in which a plurality of first inclined surfaces inclined with respect to the light exit surface are arranged;
A second optical shape layer laminated on a surface of the first optical shape layer on which the first inclined surface is provided;
A reflective layer formed on at least a part of the first inclined surface, reflecting a part of the image light and transmitting the other;
An intermediate layer provided between the first inclined surfaces adjacent to each other and at the boundary between the first optical shape layer and the second optical shape layer;
When the refractive index of the first optical shape layer is n1 and the refractive index of the second optical shape layer is n2, the refractive index n3 of the intermediate layer is n2 <n3 <n1 when n1> n2. And if n1 <n2, satisfy n1 <n3 <n2.
A transflective reflective sheet characterized by The transflective sheet according to claim 1,
The refractive index n3 of the intermediate layer varies from the refractive index n1 side to the refractive index n2 side as it goes from the first optical shape layer side to the second optical shape layer side.
A transflective reflective sheet characterized by The transflective reflection sheet according to claim 1 or 2,
An image source for emitting image light to the transflective reflection sheet;
A display device comprising: A method of producing a transflective sheet for forming the transflective sheet according to claim 1 or 2,
Filling a mold for forming the first optical shape layer in a mold, and forming the first optical shape layer in a semi-cured state; and
A reflective layer forming step of forming the reflective layer on the first inclined surface of the first optical shape layer in a semi-cured state formed by the first molding step;
The surface of the first optical shape layer on the first inclined surface side is filled with a resin that forms the second optical shape layer and cured to form the second optical shape layer, and the semi-cured first state A second molding step of curing one optical shape layer and forming the intermediate layer at a boundary between the first optical shape layer and the second optical shape layer between the adjacent first inclined surfaces;
A method for producing a transflective reflective sheet.

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