JP6972642B2 - Display device - Google Patents

Description

The present invention relates to a display device that displays an image to an observer.

Conventionally, a head-mounted display device (HMD) has been proposed, which allows an observer to observe an image from an image source such as an LCD (Liquid Crystal Display) or an organic EL display via an optical system. (For example, Patent Document 1). Such a head-mounted display device magnifies the image light projected from the image source by an optical system such as a lens and displays a clear image to the observer.
The image source used in such a display device is provided with a plurality of pixel areas constituting the image and a non-pixel area provided between the pixel areas and not contributing to the display of the image. When the image light emitted from such an image source is magnified by a lens, not only the image composed of the pixel area but also the non-image area caused by the non-pixel area is enlarged, and only the image is used. In some cases, the non-image area may be visually recognized by the observer, which may hinder the display of a clear image.

Japanese Patent Publication No. 2011-509417

An object of the present invention is to provide a display device capable of suppressing visual recognition of a non-image region caused by a non-pixel region existing between pixel regions of an image source.

と定義し、前記第１単位形状が形成された界面と前記映像源の表示層（１１ｅ）との間の距離をＬ１とし、前記画素領域（Ｇ１）が配列されている画素配列ピッチをＰＰとしたとき、１５≦θａｖｅ１×Ｌ１／ＰＰ≦６０を満たし、さらに、前記第２単位形状（２２ａ，４２ａ）の拡散角θにおける輝度をＩ_２（θ）とし、前記レンズと前記第２単位形状が形成された界面（２０２，４０２）との間の距離をＫ２とし、前記レンズの有効半径をＲ３としたとき、前記第１単位形状の平均拡散角θａｖｅ２を、

と定義し、前記第２単位形状が形成された界面と前記映像源の表示層との間の距離をＬ２とし、前記画素領域が配列されている画素配列ピッチをＰＰとしたとき、１５≦θａｖｅ２×Ｌ２／ＰＰ≦６０を満たすこと、を特徴とする表示装置（１）である。
第３の発明は、第２の発明の表示装置において、２３≦θａｖｅ１×Ｌ１／ＰＰ≦３５、２３≦θａｖｅ２×Ｌ２／ＰＰ≦３５をともに満たすこと、を特徴とする表示装置（１）である。 The present invention solves the above-mentioned problems by the following solution means. In addition, in order to facilitate understanding, the description will be given with reference numerals corresponding to the embodiments of the present invention, but the present invention is not limited thereto.
The first invention comprises an image source (11) in which a plurality of pixel regions (G1) are arranged and emits image light (V), a lens (12) that magnifies the image light and emits it to the observer side. An optical sheet (20, 40) arranged between the image source and the lens or on the observer side of the lens is provided, and the optical sheet has two or more optical layers (21, 22, 2, 40). 41, 42, 43) are laminated, and a plurality of convex or concave first unit shapes (21a, 41a) are formed at the interface (201, 401) between the adjacent optical layers, and the adjacent optical layers are formed. A plurality of convex or concave second unit shapes (22a, 42a) are formed at the other interface (402) between them or the interface (202) between the optical layer and the air, and the first unit shape is the above-mentioned. The second unit shape extends in the first direction in the sheet surface orthogonal to the thickness direction of the optical sheet and is arranged in the second direction orthogonal to the first direction in the sheet surface. It extends in a second direction in the sheet surface orthogonal to the thickness direction of the optical sheet, is arranged in the first direction orthogonal to the second direction in the sheet surface, and is viewed from the thickness direction of the optical sheet. The first unit shape and the second unit shape are display devices (1) characterized in that their extending directions are orthogonal to each other.
In the second aspect of the invention, in the display device of the first invention, the luminance at the diffusion angle θ of the first unit shape (21a, 41a) is I ₁ (θ), and the lens (12) and the first unit shape. When the distance to the interface (201,401) on which the lens is formed is K1 and the effective radius of the lens is R3, the average diffusion angle θave1 of the first unit shape is set to.

The distance between the interface on which the first unit shape is formed and the display layer (11e) of the image source is L1, and the pixel arrangement pitch in which the pixel region (G1) is arranged is PP. Then, 15 ≦ θave1 × L1 / PP ≦ 60 is satisfied, and the brightness at the diffusion angle θ of the second unit shape (22a, 42a) is set to I ₂ (θ), and the lens and the second unit shape are formed. When the distance between the formed interface (202, 402) is K2 and the effective radius of the lens is R3, the average diffusion angle θave2 of the first unit shape is determined.

When the distance between the interface on which the second unit shape is formed and the display layer of the image source is L2 and the pixel arrangement pitch in which the pixel areas are arranged is PP, 15 ≦ θave2. The display device (1) is characterized in that × L2 / PP ≦ 60 is satisfied.
The third invention is the display device (1), characterized in that the display device of the second invention satisfies both 23 ≦ θave1 × L1 / PP ≦ 35 and 23 ≦ θave2 × L2 / PP ≦ 35. ..

The fourth invention is in any of the display devices from the first invention to the third invention, in which the first unit shape (21a, 41a) is parallel to the thickness direction of the optical sheet (20, 40). The cross-sectional shape in the cross section parallel to the second direction is formed in a substantially arc shape, and the second unit shape (22a, 42a) is parallel to the thickness direction of the optical sheet and is in the first direction. The cross-sectional shape in the cross section parallel to is formed in a substantially arc shape, the pitch at which the first unit shapes are arranged is P1, and the radius of refraction of the arc-shaped shape of the cross-sectional shape of the first unit shape is R1. The refractive index of the region adjacent to each other via the interface (201, 401) in which the first unit shape is formed is defined as na, and the refractive index of which is lower than na is defined as na. The refractive index is nb, the distance between the interface on which the first unit shape is formed and the display layer (11e) of the image source (11) is L1, and the image light (V) is determined by the first unit shape. The degree of diffusion D1 as an index indicating the degree of diffusion is defined as D1 = (P1 / R1) × (1- (nb / na)) × L1, and the pitch in which the second unit shape is arranged is P2. Let R2 be the radius of curvature of the arcuate shape of the cross-sectional shape of the first unit shape, and refraction of the region refractions adjacent to each other via the interface (202,402) on which the second unit shape is formed. The refractive index with the higher refractive index is nc, the refractive index with the lower refractive index is nd, and the distance between the interface on which the second unit shape is formed and the display layer of the image source is L2. As the second unit shape, the degree of diffusion D2 as an index indicating the degree to which the video light is diffused is defined as D2 = (P2 / R2) × (1- (nd / nc)) × L1. A display device characterized in that both 1.0 ≦ D1 / PP ≦ 2.0 and 1.0 ≦ D2 / PP ≦ 2.0 are satisfied when the pixel arrangement pitch in which the pixel regions are arranged is PP. (1).
The fifth invention is the display device of the fourth invention, characterized in that 1.2 ≦ D1 / PP ≦ 1.7 and 1.2 ≦ D2 / PP ≦ 1.7 are both satisfied. 1).
In the sixth invention, in any of the display devices from the first invention to the fifth invention, the pitch at which the first unit shapes (21a, 41a) are arranged is set to P1, and the first unit shape is formed. The distance between the interface (201, 401) and the display layer (11e) of the image source (11) is L1, and the pitch at which the second unit shapes (22a, 42a) are arranged is P2. When the distance between the interface (202, 402) on which the second unit shape is formed and the display layer of the image source is L2, 0.005 ≦ P1 / L1 ≦ 0.05, 0.005 ≦ P2 / The display device (1) is characterized in that both L2 ≦ 0.05 are satisfied.
A seventh aspect of the invention is at the interface between the optical layers (21, 22, 41, 42, 43) adjacent to each other in any of the display devices from the first invention to the sixth invention. The display device (1) is characterized in that the difference in refractive index between adjacent regions is 0.005 or more and 0.2 or less.

According to the eighth aspect of the present invention, in any of the display devices from the first invention to the seventh invention, the optical sheet (40) has three or more layers of the optical layers (41, 42, 43). A display device characterized in that a plurality of the first unit shape (41a) and the second unit shape (42a) are provided at different interfaces (401.402) between adjacent optical layers. 1).
A ninth aspect of the present invention is the display device (1) of the eighth invention, wherein the optical sheet (40) has both surfaces flat.
According to the tenth aspect of the present invention, in any of the display devices from the first invention to the seventh invention, the optical sheet (20) is formed by laminating two layers of the optical layers (21, 22). A plurality of first unit shapes (21a) are provided at the interface (201) between the two optical layers, and the second unit shape (22a) is with the optical layer (22) of one of the two layers. It is a display device (1) characterized by being provided at a plurality of interfaces (202) with air.
The eleventh invention is from the display surface (11a) of the image source 11 to the observer side surface of the optical sheet (20, 40) in any of the display devices from the first invention to the tenth invention. The display device is characterized in that no air layer is present in at least the region of the image light through which the light reaching the observer is transmitted.
The twelfth invention is the observation of the optical sheet (20, 40) from the light emitting surface (11a) of the image light of the image source (11) in any of the display devices from the first invention to the eleventh invention. It is characterized in that the difference in refractive index at the interface between the members in the region where the light reaching the observer is transmitted, at least up to the surface on the person side, is less than 0.3. It is a display device.
According to the thirteenth invention, in any of the display devices from the first invention to the twelfth invention, at least one surface of the optical sheet (20, 40) has a reflection suppressing function, an antifouling function, and an antistatic function. The display device (1) is characterized in that a layer having at least one of the functions is provided.
A fourteenth aspect of the present invention is the display device according to any one of the first to thirteenth inventions, wherein the first direction is relative to the arrangement direction of the pixel region when viewed from the thickness direction of the optical sheet. It is a display device characterized by forming an angle of 10 ° or more and 80 ° or less.
According to the fourteenth invention, in any of the display devices from the first invention to the thirteenth invention, the optical sheet (20, 40) is incident from the surface on the image source side at an incident angle of 0 ° and is observed by the observer. A display device characterized in that β ≦ 5 × α is satisfied when the half-value angle α of the transmitted light emitted to the side is defined and the angle at which the brightness of the transmitted light is 1/20 of the maximum brightness is defined as the viewing angle β. (1).
In the sixteenth invention, in any of the display devices from the first invention to the fifteenth invention, the distance between the optical sheet (20, 40) and the image source (11) can be changed and is predetermined. The display device (1) is characterized in that it can be fixed at the position of.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a display device capable of suppressing visual recognition of a non-image region caused by a non-pixel region existing between pixel regions of an image source.

It is a figure explaining the head-mounted display device 1 of 1st Embodiment. FIG. 1 is a view of the display device 1 as viewed from above in the vertical direction. It is a figure explaining the detail of the optical sheet 20 used for the display device 1 of 1st Embodiment. It is a figure which shows the example of the image displayed by the display device 1 of 1st Embodiment. It is a figure explaining the display device 5 of the comparative example. It is a figure which shows an example of the relationship between the diffusion angle and the luminance by the unit shape of the optical sheet 20 of 1st Embodiment. It is a figure which shows the distance K1, K2, the distance L1, L2, and the effective radius R3 of a lens 12. It is a figure which shows an example of the manufacturing process of an optical sheet 20. It is a figure explaining the optical sheet 40 of the 2nd Embodiment. It is a figure explaining the deformation form of an optical sheet 20. It is a figure explaining the modification form of the display device 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. In addition, each figure shown below including FIG. 1 is a diagram schematically shown, and the size and shape of each part are exaggerated as appropriate for easy understanding.
In the present specification, numerical values such as dimensions of each member and material names described are examples of embodiments, and the present invention is not limited to these, and may be appropriately selected and used.
In the present specification, terms that specify a shape or a geometric condition, for example, terms such as parallel and orthogonal, have the same optical function in addition to their strict meanings and can be regarded as parallel or orthogonal. The state with the error of is also included.

In the present specification, the sheet surface refers to a surface of a sheet-shaped member that is in the plane direction of the sheet when viewed as a whole.
In this specification, terms such as board and sheet are used, but as a general usage, these are used in the order of thickness, board, sheet, and film, and these are used in this specification. Above all, it is used following that. However, since there is no technical meaning in such proper use, these words can be replaced as appropriate.

(First Embodiment)
FIG. 1 is a diagram illustrating a head-mounted display device 1 of the first embodiment. FIG. 1 shows a state in which the display device 1 is viewed from the upper side in the vertical direction.
FIG. 2 is a diagram illustrating details of the optical sheet 20 used in the display device 1 of the first embodiment. FIG. 2A is a cross-sectional view of the unit shape 21a of the optical sheet 20 parallel to the arrangement direction and the thickness direction, and FIG. 2B is a cross-sectional view taken along the line b of FIG. 2A. 2 (c) is a diagram showing the details of the c portion of FIG. 2 (a), and FIG. 2 (d) is a diagram showing the details of the d portion of FIG. 2 (b).
FIG. 3 is a diagram showing an example of an image displayed by the display device 1 of the first embodiment.
FIG. 4 is a diagram illustrating a display device 5 of a comparative example. FIG. 4A is a diagram for explaining the configuration of the display device 5 of the comparative example, and is a diagram corresponding to FIG. 1. In FIG. 4A, only the image source 51 and the lens 52 are shown as the display device 5 for easy understanding. FIG. 4B is a diagram showing an example of an image displayed by the display device 5 of the comparative example.

In addition, in the figure shown below including FIG. 1 and in the following description, in order to facilitate understanding, the vertical direction (vertical direction) is the Z direction with the display device 1 attached to the head of the observer. The horizontal direction is the X direction and the Y direction. Further, in this horizontal direction, the thickness direction of the optical sheet is the Y direction, and the left-right direction orthogonal to the thickness direction is the X 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 (HMD) that the observer wears on the head and displays an image in front of the observer's eyes. As shown in FIG. 1, the head-mounted display device 1 of the present embodiment includes a video source 11, a lens 12, and an optical sheet 20 inside the housing 30, and the housing 30 is provided. By attaching the image to the head of the observer so as to be in front of the observer's eyes, the image displayed on the image source 11 can be visually recognized by the observer's eye E via the optical sheet 20 and the lens 12.
In FIG. 1, the display device 1 will be described with reference to an example in which an image is displayed to both eyes E1 and E2 of the observer, but the present invention is not limited to this, and for example, one side of the observer is used. It may be arranged with respect to the eye E1 and display an image to the eye E1.

The housing 30 is a rectangular box-shaped housing that is horizontally long in the left-right direction, and inside the housing 30, a holding portion 31 that holds the image source 11, a holding portion 32 that holds the optical sheets 20 (20A, 20B), and a lens. A holding portion 33 for holding the 12 (12A, 12B) is provided. The housing 30 can be attached to the observer's head by, for example, a belt (not shown).
The holding portion 31 is a member that holds the image source 11, and is positioned on the surface of the image source 11 on the display surface 11a side corresponding to the observer's eyes E (E1, E2) and the lens 12 (12A, 12B). Has an opening 311 (311A, 311B). In the present embodiment, the image source 11 is detachably held by the holding unit 31 (that is, the display device 1). The image light V emitted from the image source 11 enters the optical sheet 20 (20A, 20B) through the openings 311 (311A, 311B).

The holding portion 32 is a member that is located on the observer side (−Y side) of the holding portion 31 and the image source 11 and holds the optical sheet 20. The holding portion 32 is held by fitting the optical sheet 20 (20A, 20B) into the openings 321 (321A, 321B) provided at the positions corresponding to the openings 311 (311A, 311B).
The holding portion 32 and the above-mentioned holding portion 31 can be integrally moved in the Y direction, and can be fixed at a desired position in the Y direction. Therefore, the distance (position in the Y direction with respect to the lens 12) between the image source 11 and the optical sheet 20 and the lens 12 can be adjusted (focus can be adjusted) according to the visual acuity of the observer and the like. Further, the holding portion 32 and the holding portion 31 can move independently in the Y direction, and can be fixed at a desired position in the Y direction. Thereby, the distance between the image source 11 and the optical sheet 20 (the distance between the image source 11 and the optical sheet 20 in the Y direction) can be adjusted.
Not limited to this, the holding portion 31 and the holding portion 32 may be in a form in which the positions in the Y direction are fixed.

The holding portion 33 is a member located on the observer side (−Y side) of the holding portion 32 and the optical sheet 20 and holds the lens 12 (12A, 12B). The holding portion 33 has an opening 331 (331A, 331B) at a position corresponding to the optical sheet 20 (20A, 20B), and the lens 12 (12A, 12B) is placed in the opening 331 (331A, 331B). It is fitted and held.

The image source 11 is a microdisplay that emits image light V and displays an image on the display surface 11a. For example, a transmissive liquid crystal display device, a reflective liquid crystal display device, an organic EL, or the like can be used. can. As the image source 11 of the present embodiment, for example, an organic EL display having a diagonal of 5 inches is used.
The image source 11 is held by the holding unit 31 so that the display surface 11a is on the observer side (−Y side).
In the present embodiment, the display device 1 is provided with one image source 11, but the display device 1 is not limited to this, and corresponds to, for example, the lenses 12A and 12B described later and the observer's eyes E1 and E2, respectively. It may be in the form of having two video sources.

The lens 12 (12A, 12B) is a convex lens that magnifies the image light V emitted from the image source 11 and emits it to the observer side. In this embodiment, the image source 11 and the optical sheet 20 (20A, 20B) are arranged on the observer side (−Y side). The lens 12 is made of highly translucent glass or resin.
A reflection suppression layer 12a is formed on the surface of the lens 12 on the image source side (back surface side, + Y side). The antireflection layer 12a is coated with, for example, a material having a general-purpose antireflection function (for example, magnesium fluoride (MgF ₂ ), silicon dioxide (SiO ₂ ), a fluorine-based optical coating agent, etc.) with a predetermined film thickness. A layer that exerts a reflection suppression function by having a moth-eye structure having a minute uneven shape formed at a pitch smaller than the wavelength of light on the surface on the incident side of light is provided as an image source of the lens 12. It may be integrally laminated on the side. Further, as the reflection suppression layer 12a, one formed by a multilayer film in which a plurality of high refractive index layers and low refractive index layers are laminated may be used.

By providing such a reflection suppression layer 12a, the light incident on the lens 12 is reflected on the image source side of the lens 12 toward the optical sheet 20 side, and is reflected again on the surface of the optical sheet 20 to become stray light. This can be suppressed and the contrast and brightness of the image can be improved.
Further, the reflection suppression layer 12a may be further provided on the surface of the lens 12 on the observer side (−Y side). By further providing the reflection suppression layer 12a at this position, when the image light is emitted from the lens 12, it can be suppressed from being reflected at the interface between the lens 12 and the air and becoming stray light in the lens 12, and the contrast of the image can be suppressed. Etc. can be improved.

In this embodiment, the optical sheet 20 is arranged between the image source 11 and the lens 12 as shown in FIG. The optical sheet 20 is a light-transmitting sheet having a diffusion function of slightly diffusing the image light V emitted from the image source 11.
In this embodiment, lenses 12A and 12B and optical sheets 20A and 20B are provided corresponding to the observer's binoculars E1 and E2, respectively. However, the present invention is not limited to this, and for example, one optical sheet 20 large enough to cover the regions of the lenses 12A and 12B may be arranged on the image source side (back side, −Y side) of the lens 12. good.

FIG. 1 shows a form in which the optical sheet 20 and the display surface 11a of the image source 11 are separated by a predetermined dimension, but the present invention is not limited to this, and the optical sheet 20 and the display surface 11a of the image source 11 are not limited to this. Light that reaches the observer's eye E at least among the image light V, which is between the display surface 11a of the image source 11 and the surface of the optical sheet 20 on the observer side, with an intermediate layer located between them. The form may be such that the air layer does not exist in the region through which the light (light seen by the observer) is transmitted. In this case, at least the light that reaches the observer's eye E of the image light V (the light that the observer sees) is between the display surface 11a of the image source 11 and the surface of the optical sheet 20 on the observer side. The difference in refractive index at the interface between the members in the transmissive region is preferably less than 0.3. With such a form, it is possible to reduce the light amount loss of the image light V due to interfacial reflection, suppress stray light, and the like.
As such an intermediate layer, it can be appropriately adopted depending on the desired optical performance and the like, and examples thereof include a resin for index matching and the like.

As shown in FIG. 4A, the head-mounted display device 5 (hereinafter referred to as the display device 5 of the comparative example) mainly used conventionally is in a form not provided with the above-mentioned optical sheet 20. There, the image light V emitted from the image source 51 was magnified by the lens 52, and the image was displayed to the observer.
A display such as an organic EL used for the image source 51 and the image source 11 has a plurality of pixel regions G1 forming an image arranged in the display unit thereof, and does not contribute to the formation of an image between the pixel regions G1. A non-pixel region G2 is provided. Therefore, in the display device 5 of the comparative example, when the image displayed by the image light V emitted from the image source 51 is magnified through the lens 52, as shown in FIG. 4B, the pixel region G1 Not only the image F1 due to the above, but also the non-image area F2 caused by the non-pixel area G2 is enlarged. Then, the non-image area F2 is also clearly visible to the observer, which may interfere with a clear image display.

On the other hand, in the display device 1 of the present embodiment, by providing the above-mentioned optical sheet 20, the image light emitted from the image source 11 is slightly diffused, and as shown in FIG. 3, the diffused image is diffused. It is possible to prevent the observer from visually recognizing the non-video region F2 caused by the non-pixel region G2 due to the light.

As shown in FIG. 2, in the optical sheet 20 of the present embodiment, the first optical layer 21 and the second optical layer 22 are laminated in order from the image source side (back surface side, + Y side). The optical sheet 20 has a plurality of unit shapes 21a and a plurality of unit shapes 22a formed at the interface 201 of the first optical layer 21 and the second optical layer 22 and the interface 202 between the second optical layer 22 and air, respectively. ..
In FIG. 2 and the like, each direction in the optical sheet will be described using the xyz Cartesian coordinate system. The y direction is a direction parallel to the thickness direction (Y direction) of the above-mentioned optical sheet 20 (normal direction of the sheet surface of the optical sheet 20), and the x direction and the z direction are parallel to the sheet surface of the optical sheet 20. Direction and are orthogonal to each other.
The angles formed by the x-direction and the z-direction with the X-direction (left-right direction) and the Z-direction (vertical direction) are not particularly limited here.

The first optical layer 21 is located on the image source side (+ Y side, + y side) with respect to the second optical layer 22 in the thickness direction (Y direction) of the optical sheet 20, and is a layer having light transmittance. The surface of the first optical layer 21 on the image source side is formed substantially flat. As shown in FIG. 2A, the surface of the first optical layer 21 on the observer side (−Y side), that is, the interface 201 between the first optical layer 21 and the second optical layer 22 is convex. A plurality of unit shapes 21a are formed. In the present embodiment, the unit shape 21a is convex toward the observer side (−Y side, −y side).

The unit shape 21a extends in the first direction (z direction) along the surface of the first optical layer 21 on the observer side, and a plurality of unit shapes 21a extend in the second direction (x direction) orthogonal to the extending direction. It is arranged. Further, the unit shape 21a is a lenticular lens shape having a substantially arcuate cross-sectional shape on a plane (xy plane) parallel to the arrangement direction and the thickness direction of the optical sheet 20. Here, the substantially arcuate shape means not only a perfect circular arc but also a curved shape including a part such as an ellipse or an ellipse. In the present embodiment, the cross-sectional shape of the unit shape 21a is substantially arcuate as described above, but this is an example and is not limited thereto.
The array pitch of the unit shape 21a is P1, and the radius of curvature of the arc shape is R1. Further, the width W1 in the arrangement direction of the unit shape 21a is equal to the arrangement pitch P1.

The second optical layer 22 is a layer having light transmittance located on the observer side (−Y side, −y side) of the first optical layer 21. The surface of the second optical layer 22 on the observer side is a surface (interface 202 with air) from which the image light transmitted through the optical sheet 20 is emitted, and has a convex unit shape as shown in FIG. 2 (b). A plurality of 22a are formed. In the present embodiment, the unit shape 22a is convex toward the observer side (−Y side, −y side).
The unit shape 22a extends in the second direction (x direction) along the surface of the second optical layer 22 on the observer side, and extends in the first direction (z direction) orthogonal to the extending direction. A plurality of arrangements are made, and the cross-sectional shape on the plane (yz plane) parallel to the arrangement direction and the thickness direction of the optical sheet 20 is a lenticular lens shape formed in a substantially arc shape. In the present embodiment, the cross-sectional shape of the unit shape 22a is substantially arcuate as described above, but this is an example and is not limited thereto.
The array pitch of the unit shape 22a is P2, and the radius of curvature of the arc shape is R2. Further, the width W2 in the arrangement direction of the unit shape 22a is equal to the arrangement pitch P2.

When viewed from the thickness direction of the optical sheet 20 (normal direction of the sheet surface, Y direction, y direction), the extending direction (z direction) of the unit shape 21a provided on the first optical layer 21 and the second optical layer 22. The unit shape 22a provided in the above is orthogonal to the extending direction (x direction).
Further, when viewed from the thickness direction of the optical sheet 20, the arrangement direction (x direction) of the unit shape 21a and the arrangement direction (z direction) of the unit shape 22a are orthogonal to each other.
When viewed from the thickness direction of the optical sheet 20 (normal direction of the sheet surface, Y direction, y direction), the extending direction (x direction) of the unit shape 22a and the extending direction (z direction) of the unit shape 21a. Is not limited to orthogonality, and may intersect so as to form an angle of 80 to 100 °. Similarly, when viewed from the thickness direction of the optical sheet 20, the arrangement direction (x direction) of the unit shape 21a and the arrangement direction (z direction) of the unit shape 22a are not limited to orthogonal but form an angle of 80 to 100 °. It may intersect like this.

Further, the intensity of the diffusing action required for the optical sheet 20 changes depending on the distance between the optical sheet 20 and the image source 11. That is, the preferable range of the arrangement pitches P1 and P2 of the unit shapes 21a and 22a changes depending on the distance between the optical sheet 20 and the image source 11. Therefore, the arrangement pitches P1 and P2 may be appropriately set according to the distance between the optical sheet 20 and the image source 11 and the desired intensity of the diffusion action.
If the arrangement pitches P1 and P2 are smaller than the preferable range set according to the distance between the optical sheet 20 and the image source 11 and the desired intensity of the diffusion action, it is difficult to manufacture the unit shapes 21a and 22a. In addition, it is not preferable because the diffraction phenomenon of light is likely to occur and the image becomes unclear due to the influence of the diffracted light. When the arrangement pitches P1 and P2 are larger than a preferable range set according to the distance between the optical sheet 20 and the image source 11 and the desired intensity of the diffusion action, lines between adjacent unit shapes are visually recognized in a streak pattern. It is not preferable because it may end up.
In the present embodiment, the unit shape 21a and the unit shape 22a have the same arrangement pitch and P1 = P2, but the radius of curvature is different, and R1 <R2.

The first optical layer 21 is formed on one side of a base material layer made of a highly light-transmitting PC (polycarbonate) resin, MS (methylmethacrylate / styrene) resin, PET (polyethylene terephthalate) resin, acrylic resin, or the like. A plurality of unit shapes 21a are shaped and formed by an ultraviolet curable resin such as a highly permeable urethane acrylate resin or an epoxy acrylate resin.
The second optical layer 22 is formed of a urethane acrylate resin having high light transmittance, an ultraviolet curable resin such as an epoxy acrylate resin, or the like.
In the present embodiment, the unit shape 21a of the first optical layer 21 is made of a material having a higher refractive index than the second optical layer 22.

Further, in the optical sheet 20 of the present embodiment, the refractive index difference between the regions adjacent to each other via the interface 201, that is, the refractive index difference Δn1 between the unit shape 21a and the second optical layer 22 is 0.005 ≦ Δn1 ≦. It is formed to satisfy 0.2.
When this refractive index difference Δn1 is less than 0.005, the refractive index difference at the interface 201 becomes too small, the refraction of the image light at the interface 201 becomes difficult to occur, and a sufficient diffusion action cannot be exhibited, which is desirable. No. Further, when the refractive index difference Δn1 is less than 0.005, the variation in the refractive index of the resin in the adjacent region at the interface 201 has a large influence on the diffusion characteristics and is preferable because the influence of the wavelength dispersion is large. No.
When the refractive index difference Δn1 is larger than 0.2, the refraction of light at the interface 201 becomes too large, the diffusion action becomes too large, and the image becomes unclear, which is not desirable. Further, when the refractive index difference Δn1 is larger than 0.2, the material cost for realizing the layer structure having such a refractive index difference increases.

Further, the optical sheet 20 of the present embodiment is provided with a reflection suppression layer (not shown) on the image source side (+ Y side, + y side) and the observer side (−Y side, −y side) of the first optical layer 21. Has been done.
The antireflection layers provided on both sides of the optical sheet 20 are, for example, a material having a general-purpose antireflection function (for example, magnesium fluoride (MgF)), similarly to the antireflection layer 12a provided on the image source side of the lens 12. ₂ ), silicon dioxide (SiO ₂ ), fluorine-based optical coating agent, etc.) may be provided by coating with a predetermined film thickness.
Further, when the image source 11 is fixed to the display device and cannot be attached or detached, a moth-eye structure having a minute uneven shape formed at a pitch smaller than the wavelength of the light is provided on the surface on the incident side of the light. A layer that exhibits a reflection suppression function may be integrally laminated on the image source side of the optical sheet 20.

By providing the reflection suppression layer on the image source side of the optical sheet 20, the light incident on the optical sheet 20 is reflected by the surface of the optical sheet 20 on the image source side and directed toward the image source 11 side. The decrease can be suppressed.
Further, by providing the reflection suppression layer on the image source side of the optical sheet 20, the light incident on the optical sheet 20 is reflected by the surface of the optical sheet 20 on the image source side and heads toward the image source 11, and the image source 11 It is possible to suppress stray light due to reflection on the display surface 11a again and to improve the contrast of the image.
Further, by providing the reflection suppression layer on the surface of the optical sheet 20 on the observer side, when the image light is emitted from the optical sheet 20, it is reflected at the interface between the optical sheet 20 and the air, and stray light is emitted in the optical sheet 20. It is possible to reduce the amount of light and improve the contrast and brightness of the image.
The reflection suppression layer is not limited to the above example, and may be provided on only one side of the optical sheet 20, for example, only on the image source side.

Further, a layer having a hard coat function, an antifouling function, an antistatic function, etc. is provided on the surface of the optical sheet 20 on the image source side (+ Y side, + y side) and the observer side (−Y side, −y side). It may be provided as appropriate.
By providing such a layer, for example, when the image source 11 is detachable from the housing 30, the optical sheet 20 is damaged or soiled when the image source 11 is removed from the housing 30. It is possible to prevent the optics, dust, dust, etc. from adhering to the image and hinder the visual recognition of the image.

Next, the action of diffusing the image light V of the optical sheet 20 and the like will be described.
As described above, the optical sheet 20 suppresses the non-image region F2 caused by the non-pixel region G2 from being visually recognized by the observer due to the action of diffusing the image light V.
If the diffusion action of the optical sheet 20 is too strong, the image light V is diffused more than necessary, and the quality of the image is deteriorated. On the other hand, if the diffusion action of the optical sheet 20 is too weak, the non-image region F2 will be visually recognized by the observer. Therefore, the optical sheet 20 must have an appropriate diffusing action.
Further, the optimum strength of the diffusing action of the optical sheet 20 also changes depending on the positional relationship with the image source 11 and the lens 12.

Since the image light V from the image source 11 is diffused by the optical sheet 20, further magnified by the lens 12 and observed by the observer, the component of the light diffused in the range actually observed by the lens 12 is important. Is. Further, the optical sheet 20 has an interface in which a plurality of unit shapes 21a are arranged (interface 201 between the first optical layer 21 and the second optical layer 22) and an interface in which a plurality of unit shapes 22a are arranged (second optical). It has an interface 202) between the layer 22 and air, and is diffused at each interface.

(Index 1 related to diffusion action)
FIG. 5 is a diagram showing an example of the relationship between the diffusion angle and the brightness according to the unit shape of the optical sheet 20 of the first embodiment.
Assuming that the relationship between the brightness of the light passing through either of the interfaces in which a plurality of unit shapes of the optical sheet 20 are arranged and the diffusion angle is as shown in FIG. 5, for example, the light reaches the observer through the lens 12. It is assumed that the component is a component in which the diffusion angle θ is in the range of −φ to +φ. If the component of light diffused in this range is used as an index of the degree of diffusion of the interface, an appropriate diffusion action can be evaluated as an interface in which a plurality of unit shapes are arranged.
Further, when the pixel arrangement pitch PP in which the pixel region G1 of the image source 11 is arranged changes, the degree of the required diffusion action also changes, so this pixel arrangement pitch PP is also an important parameter.
Further, if the distance between the lens 12 and the interface on which the plurality of unit shapes of the optical sheet 20 are formed changes, the effect of the interface on which the plurality of unit shapes are formed diffuses the image light V also changes.

Therefore, the brightness at the diffusion angle θ at the interfaces 201 and 202 on which the unit shapes 21a and 22a are formed is set to I ₁ (θ) and I ₂ (θ), respectively, and the lens 12 and the unit shapes 21a and 22a are formed. When the distances between the interfaces 201 and 202 are K1 and K2 and the effective radius of the lens 12 is R3, the interface 201 and 202 in which the unit shapes 21a and 22a are formed with respect to the components in the range of −φ to +φ. The average diffusion angles θave1 and θave2, respectively.

Is defined as. The distances between the interfaces 201 and 202 on which the unit shapes 21a and 22a are formed and the display layer 11e of the image source 11 are L1 and L2, the pixel arrangement pitch in which the pixel regions G1 are arranged is PP, and θave1 × To the extent that the non-image region F2, which is the cause of the non-pixel region G2, is not visually recognized by the observer due to the action of diffusing the image light V by the unit shapes 21a and 22a of L1 / PP and θave2 × L2 / PP. Is set as an index indicating the degree of blurring, that is, an index of the degree of blurring.
The pixel arrangement pitch PP of the pixel region G1 of the image source 11 used in the display device 1 is 400 to 500 ppi (pixel per inch), and in this embodiment, PP = 0.0508 mm (500 ppi).

FIG. 6 is a diagram showing distances K1 and K2, distances L1 and L2, and an effective radius R3 of the lens 12.
The unit shapes 21a and 22a are both convex in the thickness direction (Y direction, y direction) of the optical sheet 20. Further, as for the lens 12, it is possible to use a plurality of lenses. Therefore, with respect to the distances K1 and K2 between the lens 12 and the interfaces 201 and 202 in which a plurality of unit shapes 21a and 22a are formed, the center of the lens 12 (single) from the position where the average height of the unit shapes 21a and 22a is obtained. If it is one lens, it is the distance to the principal point).

Further, when the image source 11 is, for example, an organic EL display, as illustrated in FIG. 6, the transparent substrate 11b, the transparent electrode 11c, the organic hole transport layer 11d, and the organic light emitting layer (from the observer side). A plurality of layers are laminated, such as the display layer) 11e, the organic electron transport layer 11f, and the metal electrode 11g. The non-pixel region G2 is formed on the display layer 11e.
Therefore, the above-mentioned distances L1 and L2 may be set from the display layer 11e to a position where the average height of the unit shapes 21a and 22a is reached.

When a plurality of types of optical sheets 20 were created by changing various parameters and the actual appearance was evaluated, the degree of suppressing the non-image area F2 from being visually recognized by the observer and θave1 × L1 / PP, θave2 There is a good correlation with × L2 / PP,
15 ≦ θave1 × L1 / PP ≦ 60 ・ ・ ・ (Equation 1)
15 ≦ θave2 × L2 / PP ≦ 60 ・ ・ ・ (Equation 2)
If it meets both of the above two equations, hardly non image area F2 is visually recognized in the viewer, invisible independently pixel regions G1 (pixels), and the image is not a too blurred, to observe a good image did it.
Also, more stringent conditions, ie
23 ≦ θave1 × L1 / PP ≦ 35 ・ ・ ・ (Equation 3)
23 ≦ θave2 × L2 / PP ≦ 35 ・ ・ ・ (Equation 4)
When both of the above two equations were satisfied, it was possible to observe the optimum image.

When at least one of θave1 × L1 / PP and θave2 × L2 / PP is less than 15, the pixel region G1 (pixel) is seen independently by the observer, and the non-video region F2 is conspicuously visible. When both θave1 × L1 / PP and θave2 × L2 / PP are 15 or more, the pixel region G1 cannot be seen independently due to the diffusion action, and the non-video region F2 is difficult to see. When both θave1 × L1 / PP and θave2 × L2 / PP are 23 or more, the pixel region G1 (pixel) is optimally blurred, and the observer can hardly confirm the non-video region F2.
Further, when at least one of θave1 × L1 / PP and θave2 × L2 / PP exceeds 35, the pixel region G1 cannot be seen independently, but the sharpness of the image is compared with the case where both satisfy 23 or more and 35 or less. Is slightly reduced. When at least one of θave1 × L1 / PP and θave2 × L2 / PP is larger than 60, the pixel region G1 is not conspicuous to the observer, but the resolution of the image is lowered and its sharpness is reduced. It is significantly damaged and details cannot be confirmed.
Therefore, it is preferable to satisfy both (Equation 1) and (Equation 2), and it is more preferable to satisfy both (Equation 3) and (Equation 4).

(Index 2 related to diffusion action)
Further, by considering the relative positional relationship between the optical sheet 20, the image source 11, and the lens 12, the non-image area F2 caused by the non-pixel area G2 due to the action of diffusing the image light V by the optical sheet 20. It is possible to set an index indicating the degree to which the observer is prevented from being visually recognized by the observer.

Here, the refractive index of the region (unit shape 21a and the second optical layer 22) adjacent to each other via the interface 201 on which the unit shape 21a is formed is defined as na, and the refractive index is high. Let nb be the refractive index lower than na. Further, the refractive index of the region (second optical layer 22 and air) adjacent to each other via the interface 202 on which the unit shape 22a is formed is defined as nc, and the refractive index is higher than that of nc. Let the lower refractive index be nd. At this time, the diffusivity D1 and D2 are used as an index indicating the degree to which the image light V is diffused by the unit shapes 21a and 22a.
D1 = (P1 / R1) x (1- (nb / na)) x L1
D2 = (P2 / R2) x (1- (nd / nc)) x L2
Can be defined as.
In the present embodiment, the refractive index n1 of the unit shape 21a is larger than the refractive index n2 of the second optical layer 22, so na = n1 and nb = n2, and nc = n2 and nd = 1.

The diffusivity D1 and D2 represent the degree to which light is diffused at the interfaces 201 and 202 formed in the unit shapes 21a and 22a. If the ratio of the pixel array pitch PP in which the pixel region G1 is arranged and the diffusivity D1 and D2, that is, D1 / PP and D2 / PP is obtained, the interfaces 201 and 202 in which the unit shapes 21a and 22a are formed are obtained. It can be used as an index showing the degree of suppressing the non-pixel region G2 from being visually recognized by the observer due to the non-pixel region G2.

Next, when a plurality of types of optical sheets 20 were created by changing various parameters and the actual appearance was evaluated, the degree of suppressing the non-image region F2 from being visually recognized by the observer and D1 / PP, D2 There is a good correlation with / PP,
1.0 ≤ D1 / PP ≤ 2.0 ... (Equation 5)
1.0 ≤ D2 / PP ≤ 2.0 ... (Equation 6)
If it meets both of the above two equations, hardly non image area F2 is visually recognized in the viewer, invisible independently pixel regions G1 (pixels), and the image is not a too blurred, observing a good image I found that I could do it.
If at least one of D1 / PP and D2 / PP is less than 1.0, the pixel region G1 (pixel) is seen independently by the observer, and the non-video region F2 is also visually recognized by the observer. Further, when at least one of D1 / PP and D2 / PP is larger than 2.0, the image is blurred and visually recognized by the observer. Therefore, it is preferable to satisfy both the above (Equation 5) and (Equation 6).

Also, more stringent conditions, ie
1.2 ≤ D1 / PP ≤ 1.7 ... (Equation 7)
1.2 ≤ D2 / PP ≤ 1.7 ... (Equation 8)
If both of the above two equations are satisfied, it is possible to observe an optimum image in which the non-image area F2 is hardly visible, the pixel area G1 (pixels) cannot be seen independently, and the image is not too blurred. there were.

As described above, by defining the range of the values of D1 / PP and D2 / PP at the interfaces 201 and 202 with respect to the optical sheet 20, the display device 1 of the present embodiment has the image light V emitted from the image source 11. Can be slightly diffused in the arrangement direction (x direction) of the unit shape 21a and the arrangement direction (z direction) of the unit shape 22a. As a result, the display device 1 can display a clear image to the observer and prevent the non-image area F2 of the image source 11 from being visually recognized due to the slight diffusion of the image light V.

If the cross-sectional shapes of the unit shapes 21a and 22a are elliptical or part of an ellipse and are not a perfect arc, the shape is approximated by an arc and the radius of the arc is R1. It may be calculated as R2.

(Index for obtaining diffusion effect)
Next, at the interfaces 201 and 202 in which the unit shapes 21a and 22a are formed, the relationship between the arrangement pitches P1 and P2 of the unit shape and the distances L1 and L2 between each interface and the display layer 11e will be described.
The optical sheet 20 has different preferred arrangement pitches P1 and P2 of the unit shapes 21a and 22a depending on the distances L1 and L2 from the display layer 11e of the image source 11. This is because when the optical sheet 20 is close to the display layer 11e, moire is likely to occur between the pixel (pixel region G1) and the unit shape, and when the optical sheet 20 is far from the display layer 11e, diffraction is likely to occur. be.
The array pitches P1 and P2 of the unit shapes 21a and 22a and the distances L1 and L2 are
0.005 ≤ P1 / L1 ≤ 0.05 ... (Equation 9)
0.005 ≤ P2 / L2 ≤ 0.05 ... (Equation 10)
It is preferable to satisfy both of the above two equations.
0.01 ≤ P1 / L1 ≤ 0.03 ... (Equation 11)
0.01 ≤ P2 / L2 ≤ 0.03 ... (Equation 12)
It is more preferable to satisfy both of the above two equations.
In the present embodiment, P1 / L1 = 0.02 and P2 / L2 = 0.02, which satisfy the above-mentioned preferable range and more preferable range.

When P1 / L1 and P2 / L2 are smaller than 0.005, the distance between the unit shapes 21a and 22a and the pixel (display layer 11e) is too large, and the parallelism of the light entering the optical sheet 20 becomes high. In some cases, the pitch of the unit shapes 21a and 22a becomes too small, diffraction occurs in the unit shapes 21a and 22a, and a sufficient degree of diffusion cannot be obtained.
When P1 / L1 and P2 / L2 are larger than 0.05, the distance between the unit shapes 21a and 22a and the pixel (display layer 11e) is too close, and moire occurs between the pixel and the unit shapes 21a and 22a. It is more likely to occur.
Therefore, it is preferable that both P1 / L1 and P2 / L2 satisfy the above range.

(Regarding viewing angle and half-value angle)
Further, in the optical sheet 20 of the present embodiment, the half-value angle of the transmitted light incident from the surface on the image source side at an incident angle of 0 ° and emitted to the observer side is α, and the brightness of the transmitted light is 1 / of the maximum brightness. When the viewing angle of 20 is β, it is preferably formed so as to satisfy β ≦ 5 × α.
Here, the half-value angle α of the optical sheet 20 means that the brightness of the light is the maximum value in the arrangement direction and the extending direction of the unit shape from the observation position of the sheet surface of the optical sheet 20 where the brightness of the light is the maximum value. The angle with the largest absolute value among the observation angles that are half the value. Further, the viewing angle β is set to a value of 1/20 of the maximum value of the light brightness in the arrangement direction and the extending direction of the unit shape from the observation position of the sheet surface of the optical sheet 20 where the light brightness is the maximum value. The angle with the largest absolute value among the observation angles.

If the viewing angle β is larger than 5 × α, the diffused range of the low-luminance video light becomes too wide, and the sharpness of the video is lowered, which is not desirable.
Further, from the viewpoint of more effectively exerting the effect of making the non-video region F2 caused by the non-pixel region G2 inconspicuous, the viewing angle β is more likely to be substantially equal to or close to the half-value angle α. desirable.

Next, the operation until the image light V emitted from the image source 11 reaches the observer's eyes E (E1, E2) will be described.
As shown in FIG. 1, the image light V emitted from the image source 11 is incident on the surface of the optical sheet 20 (20A, 20B) on the image source side (+ Y side, + y side). Then, the image light V incident on the optical sheet 20 is transmitted through the first optical layer 21 and has a unit formed by a plurality of unit shapes 21a formed at the interface 201 between the first optical layer 21 and the second optical layer 22. It diffuses slightly in the arrangement direction (x direction) of the shape 21a and transmits through the second optical layer 22.
The image light V transmitted through the second optical layer 22 is slightly diffused in the arrangement direction (z direction) of the unit shape 22a by the unit shape 22a formed at the interface 202 with the air of the second optical layer 22 and is optical. It emits light from the surface of the sheet 20 on the observer side (−Y side, −y side).
The image light V transmitted through the optical sheet 20 is incident on the lenses 12 (12A, 12B). Then, the image light V is magnified by the lens 12 and emitted to the observer side (−Y side).

The image light V is slightly diffused by the optical sheet 20 in the arrangement direction (x direction, z direction) of the unit shapes 21a and 22a. Therefore, even if the image is magnified by the lens 12, the image visually recognized by the observer's eye E is, as shown in FIG. 3, as compared with the case of the display device 5 of the comparative example (FIG. 4 (b)). (See), it is possible to prevent the non-image region F2 caused by the non-pixel region G2 of the image source 11 from being noticeably visually recognized by the observer as much as possible, and it is possible to display a clear image.

In order for the optical sheet 20 to obtain a preferable diffusing action, it is preferable to satisfy both the above-mentioned (Equation 9) and (Equation 10), and it is more preferable to satisfy both (Equation 11) and (Equation 12). As a result, the optical sheet 20 can diffuse the image light V without causing moire, diffraction, or the like.
Further, in order to set the diffusing action of the optical sheet 20 in a preferable range, at least one combination of (formula 1) and (formula 2) of index 1 or (formula 5) and (formula 6) of index 2 is used. It is preferable to satisfy, and it is more preferable to satisfy both. As a result, it is possible to observe a good image in which the pixels (pixel region G1) cannot be seen independently and the image is not too blurred.
Further, in order to make the diffusion action of the optical sheet 20 more optimum, the stricter conditions are (Equation 3) and (Equation 4) of the index 1, or (Equation 7) and (Equation 8) of the index 2. ) Satisfying at least one combination is more preferable.
Further, it is preferable that the optical sheet 20 is formed so that the above-mentioned half-value angle α and the viewing angle β satisfy β ≦ 5 × α.

Next, a method of manufacturing the optical sheet 20 used in the display device 1 of the present embodiment will be described.
FIG. 7 is a diagram showing an example of a manufacturing process of the optical sheet 20. FIG. 7 shows a part of the manufacturing apparatus for the optical sheet 20.
The manufacturing apparatus 700 for the optical sheet 20 includes a roll 70 for supplying the sheet-shaped base material 21A wound into a roll shape, a first roll 71, a second roll 72, a third roll 73, a fourth roll 74, and a first roll. It has 5 rolls 75, 6th roll 76, dies 77, 78, and ultraviolet irradiators 79, 80.
The first roll 71 and the fourth roll 74 are pressing rolls. The second roll 72 and the fifth roll 75 are molding dies (roll plates) in which a plurality of concave shapes forming the unit shapes 21a and 22a are formed on the outer peripheral surface thereof. The third roll 73 and the sixth roll 76 are peeling rolls.

The first optical layer 21 of the optical sheet 20 is provided with a concave shape corresponding to the unit shape 21a by applying an ultraviolet curable resin forming the unit shape 21a from the die 77 on one surface of the sheet-shaped base material 21A. The second roll 72, which is a molding mold, is pressed by the first roll, and ultraviolet rays are irradiated by the ultraviolet irradiator 79 to cure the ultraviolet curable resin. Then, the third roll 73 releases the mold from the second roll 72 to form the first optical layer 21.
Subsequently, an ultraviolet curable resin that forms the second optical layer 22 from the die 78 is applied onto the unit shape 21a of the first optical layer 21, and the molding mold has a concave shape corresponding to the unit shape 22a. The 5 rolls 75 are pressed by the 4th roll 74, and the ultraviolet rays are irradiated by the ultraviolet irradiation device 80 to cure the ultraviolet curable resin. Then, the sixth roll 76 is released from the fifth roll 75 to form the second optical layer 22 to which a plurality of unit shapes 22a are shaped.

At this time, the molding mold of the second optical layer 22 is arranged so that the extending direction of the unit shape 22a is orthogonal to the extending direction of the unit shape 21a of the first optical layer 21. That is, the above-mentioned second roll 72 and the fifth roll 75 are formed so that the arrangement direction (extending direction) of the concave shape forming each unit shape is orthogonal to the flow direction.
As a result, the first optical layer 21 and the second optical layer 22 are laminated, and further, a reflection suppression layer (not shown) or the like is appropriately provided, and then the optical sheet is cut into a predetermined shape and size. 20 is completed.

By adopting such a manufacturing method, for example, a sheet-like member having a unit shape 21a formed on one side and a sheet-like member having a unit shape 22a formed on one side are orthogonal to each other in the extending direction of each unit shape. The number of members is smaller and the optical sheet can be easily manufactured as compared with the case where the adhesives having light transmittance or the like are attached so as to be arranged in such a manner. Further, by adopting such a manufacturing method, the number of layers of the optical sheet 20 can be reduced, and unnecessary reflection loss between layers can be reduced.

From the above, according to the present embodiment, the display device 1 can slightly diffuse the image light V emitted from the image source 11, display a clear image to the observer, and the pixel region G1 is formed. It is possible to prevent the observer from seeing the non-image region F2 which cannot be seen independently and is caused by the non-pixel region G2 of the image source 11.

Further, the display device 1 of the present embodiment has the extension direction (z direction) of the unit shape 21a and the unit shape 22a when viewed from the thickness direction of the optical sheet 20 (normal direction of the sheet surface, Y direction, y direction). Since the extending direction (x direction) of is orthogonal to each other and the arrangement direction (x direction) of the unit shape 21a and the arrangement direction (z direction) of the unit shape 22a are orthogonal to each other, the image light emitted from the image source 11 Can be diffused in a plurality of directions (x-direction and z-direction, which are the arrangement directions of the unit shapes 21a and 22a), and the non-video region F2 can be made inconspicuous more effectively.

Further, in the display device 1 of the present embodiment, as described above, since the optical sheet 20 is located on the image source side (+ Y side) of the lens 12, the image source 11 is outside the display device 1 (housing 30). The lens 12 can be protected from foreign matter such as dust and dirt that has entered, and the lens 12 is not damaged or soiled by foreign matter, and the surface of the optical sheet 20 on the image source side is covered. Even if it becomes dirty or cloudy, it can be wiped off without damaging the unit shape.
Further, since the display device 1 of the present embodiment is provided with the reflection suppression layer on both sides of the optical sheet 20 and the reflection suppression layer 12a on the surface of the lens 12 on the image source side, stray light is suppressed and the image is bright. The pod contrast can be improved.

In particular, the reflection-suppressing layer having a moth-eye structure has a high reflection-suppressing effect, but it is easily damaged, so it is important to provide it at a position where the observer's finger or the like does not touch. In the display device 1 of the present embodiment, since the optical sheet 20 is located on the image source side (+ Y side) of the lens 12, such a reflection suppression layer is provided on the observer side of the optical sheet 20 or on the image source side of the lens 12. It can be provided in the like, a higher reflection suppression effect can be obtained, and the contrast and brightness of the image can be improved.

(Second Embodiment)
In the optical sheet 40 shown in the second embodiment, the third optical layer 43 is provided on the observer side (−Y side, −y side) of the second optical layer 22, and the unit shape 42a is the second optical layer 42 and the second optical layer 42. 3 It is different from the optical sheet 20 of the first embodiment in that it is formed at the interface 402 with the optical layer 43. Therefore, in the following description of the second embodiment, the same reference numerals or the same reference numerals are given to the portions having the same functions as those of the first embodiment described above, and duplicate description thereof will be omitted as appropriate.
FIG. 8 is a diagram illustrating the optical sheet 40 of the second embodiment. FIG. 8A is a cross-sectional view of the unit shape 41a of the optical sheet 40 parallel to the arrangement direction and the thickness direction, and FIG. 8B is a cross-sectional view taken along the line b of FIG. 8A. 8 (c) is a diagram showing the details of the c portion of FIG. 8 (a), and FIG. 8 (d) is a diagram showing the details of the d portion of FIG. 8 (b).

As shown in FIG. 8, the optical sheet 40 of the second embodiment has a first optical layer 41, a second optical layer 42, and a third optical layer 43 in order from the image source side (back surface side, + Y side, + y side). Are laminated. Further, the optical sheet 40 has reflection suppression layers (not shown) on both sides thereof.
The optical sheet 40 has a plurality of unit shapes 41a and a plurality of unit shapes 42a formed at the interface 401 of the first optical layer 41 and the second optical layer 42 and the interface 402 of the second optical layer 42 and the third optical layer 43, respectively. Has been done. Further, the optical sheet 40 can be applied to the display device 1 shown in the first embodiment.

The first optical layer 41 is a layer corresponding to the first optical layer 21 of the above-mentioned first embodiment. The first optical layer 41 is observed on the observer side (−Y side, −y side) surface (interface 401 of the first optical layer 41 and the second optical layer 42) as shown in FIG. 8 (a). A plurality of convex unit shapes 41a that are convex on the user side are formed.
The unit shape 41a extends in the first direction (z direction) along the surface of the first optical layer 41 on the observer side, and has a plurality of arrangements in the second direction (x direction) orthogonal to the extending direction. Has been done. Further, the unit shape 41a is a lenticular lens shape having a substantially arcuate cross-sectional shape on a plane (xy plane) parallel to the arrangement direction and the thickness direction.

The second optical layer 42 is a layer having light transmittance provided on the observer side (−Y side) of the first optical layer 21. The second optical layer 42 is observed on the observer side (−Y side, −y side) surface (interface 402 of the second optical layer 42 and the third optical layer 43) as shown in FIG. 7 (b). A plurality of convex unit shapes 42a that are convex on the user side are formed.
The unit shape 42a extends in the second direction (x direction) along the surface of the second optical layer 42 on the observer side, and extends in the first direction (z direction) orthogonal to the extending direction. It is a lenticular lens shape in which a plurality of lenses are arranged in a substantially arc shape in a plane (yz plane) parallel to the arrangement direction and the thickness direction.

The third optical layer 43 is a layer having light transmittance provided on the observer side (−Y side, −y side) of the second optical layer 42. The surface of the third optical layer 43 on the observer side is a surface on which the image light transmitted through the optical sheet 40 is emitted, and is formed substantially flat.

Similar to the optical sheet 20 of the first embodiment, the unit shape 42a provided on the second optical layer 42 is extended when viewed from the thickness direction of the optical sheet 40 (normal direction, Y direction, y direction of the sheet surface). The existing direction (x direction) and the extending direction (z direction) of the unit shape 41a provided on the first optical layer 41 are orthogonal to each other. Further, when viewed from the thickness direction of the optical sheet 40, the arrangement direction (x direction) of the unit shape 41a and the arrangement direction (z direction) of the unit shape 42a are orthogonal to each other.
In the present embodiment, the unit shape 41a and the unit shape 42a have the same arrangement pitch and radius of curvature, P1 = P2, and R1 = R2.

In the present embodiment, the refractive index n1 of the first optical layer 41 and the refractive index n3 of the third optical layer 43 are higher than the refractive index n2 of the second optical layer 42.
Further, in the present embodiment, the refractive index difference between the regions adjacent to each other via the interfaces 401 and 402, that is, the refractive index difference Δn1 between the unit shape 41a of the first optical layer 41 and the second optical layer 42, and the second. The refractive index difference Δn2 between the optical layer 42 and the third optical layer 43 is formed so as to satisfy 0.005 ≦ Δn1 ≦ 0.2 and 0.005 ≦ Δn2 ≦ 0.2, respectively.
When the refractive index difference Δn1 and Δn2 are less than 0.005, the refractive index difference at the interfaces 401 and 402 becomes too small, and the refraction of the image light at the interface 401.402 becomes difficult to occur, so that a sufficient diffusing action is obtained. It is not desirable because it will not be exhibited. Further, when the refractive index difference Δn1 and Δn2 are less than 0.005, the variation in the refractive index of the resin in the adjacent region at the interfaces 401 and 402 has a large influence on the diffusion characteristics, and the influence of the wavelength dispersion becomes large. Therefore, it is not preferable.
When the refractive index difference Δn1 and Δn2 are larger than 0.2, the refraction of light at the interfaces 401 and 402 becomes too large, the diffusion action becomes too large, and the image becomes unclear, which is not desirable. Further, when the refractive index difference Δn1 and Δn2 are larger than 0.2, the material cost for realizing the layer structure having such a refractive index difference increases.

Similar to the first optical layer 21 of the first embodiment, the first optical layer 41 is formed on one side of a base material layer made of a highly light-transmitting PC resin, MS resin, PET resin, acrylic resin, or the like. The unit shape 41a is formed by shaping it with a urethane acrylate resin having high light transmittance, an ultraviolet curable resin such as an epoxy acrylate resin, or the like.
The second optical layer 42 is formed of a urethane acrylate resin having high light transmittance, an ultraviolet curable resin such as an epoxy acrylate resin, or the like, like the second optical layer 22 of the first embodiment.
The third optical layer 43 is made of a resin having high light transmittance and a higher refractive index than the second optical layer 42. The third optical layer 43 of the present embodiment is formed of a urethane acrylate resin having high light transmittance, an ultraviolet curable resin such as an epoxy acrylate resin, or a resin having a higher refractive index than the second optical layer 42. ing.
In the present embodiment, the refractive index n2 of the second optical layer 42 is lower than the refractive index n1 and n3 of the unit shape 41a and the third optical layer 43.

The optical sheet 40 of the present embodiment has reflection suppression layers (not shown) on both sides thereof, similarly to the optical sheet 20 of the first embodiment described above.
Further, a layer having a hard coat function, an antifouling function, an antistatic function and the like is appropriately provided on the image source side (+ Y side, + y side) and the observer side (−Y side, −y side) of the optical sheet 40. The third optical layer 43 may be provided, or may have a hard coat function, an antifouling function, an antistatic function, and the like.

Further, from the viewpoint of sufficiently diffusing the image light V in the display device 1 and suppressing diffraction and moire, it is preferable that both (Equation 9) and (Equation 10) are satisfied in this embodiment as well (Equation 11). ) And (Equation 12) are both satisfied. As a result, the optical sheet 40 can satisfactorily diffuse the image light V without causing moire, diffraction, or the like.
Further, also in the present embodiment, in the display device 1, the non-image area F2 is difficult to see, the pixel area G1 (pixels) cannot be seen independently, and the image is not too blurred to provide a good image. From the viewpoint, it is preferable to satisfy at least one combination of (Equation 1) and (Equation 2) of the above-mentioned index 1 or (Equation 5) and (Equation 6) of the index 2, and it is more preferable to satisfy both of them. ..
Further, in order to optimize the diffusion action of the optical sheet 40, the stricter conditions are (Equation 3) and (Equation 4) of the index 1, or (Equation 7) and (Equation 8) of the index 2. ) Satisfying at least one combination is more preferable.
Furthermore, it is preferable that the optical sheet 40 is formed so that the above-mentioned half-value angle α and viewing angle β satisfy β ≦ 5 × α.

Examples of the method for manufacturing the optical sheet 40 of the present embodiment include the following examples.
Similar to the method for manufacturing the optical sheet 20 of the first embodiment described above, a laminated body in which the second optical layer 42 is laminated on the first optical layer 41 is formed. Then, the resin forming the third optical layer 43 is applied and cured on the surface of the second optical layer 42 on the unit shape 42a side so as to fill the unevenness due to the unit shape 42a of the second optical layer 42 and form a flat surface. .. Then, the optical sheet 40 can be manufactured by appropriately providing the reflection suppressing layers on both sides of the laminated body and cutting the laminated body into a predetermined shape and size.
The method for manufacturing the optical sheet 40 is not limited to the above example, and may be appropriately selected and adopted.

From the above, according to the present embodiment, as in the first embodiment, the display device 1 can slightly diffuse the image light V emitted from the image source 11 to provide a clear image to the observer. In addition to displaying, it is possible to prevent the pixel region G1 from being independently visible and the non-image region F2 caused by the non-pixel region G2 of the image source 11 being visually recognized by the observer.

Further, according to the present embodiment, since both sides of the optical sheet 40 are flat, it is easy to handle and the display device 1 can be easily manufactured.
Further, according to the present embodiment, since the third optical layer 43 is provided on the observer side of the second optical layer 42, the third optical layer 43 is provided with a reflection suppression function, a hard coat function, an antistatic function, and the like. The number of layers can be reduced.

(Deformed form)
Not limited to each of the embodiments described above, various modifications and changes are possible, and these are also within the scope of the present invention.
(1) In each embodiment, for example, the arrangement pitches P1 and P2 of the unit shape and the shape widths W1 and W2 in the arrangement direction are equal, and the unit shapes are arranged adjacent to each other. Not limited to this, the array pitches P1 and P2 of the unit shape may be larger than the shape widths W1 and W2, and the plane portion may be located between the unit shapes.
FIG. 9 is a diagram illustrating a modified form of the optical sheet 20. 9 (a) shows a cross section parallel to the arrangement direction and the thickness direction of the unit shape 21a of the modified optical sheet 20, and FIG. 9 (b) is a cross-sectional view taken along the line b of FIG. 9 (a). 9 (c) is a diagram showing the details of the c portion of FIG. 9 (a), and FIG. 9 (d) is a diagram showing the details of the d portion of FIG. 9 (b).

In the modified form of the optical sheet 20 shown in FIG. 9, the surface of the first optical layer 21 on the observer side (−Y side, −y side) is flat with the unit shape 21a as shown in FIG. 9A. Parts 21b are provided alternately. The unit shape 21a and the flat portion 21b extend in the first direction (z direction) along the surface of the first optical layer 21 on the observer side, and a plurality of the unit shapes 21a and the flat portion 21b extend in the second direction (x direction). It is arranged.
Further, as shown in FIG. 9B, a plurality of unit shapes 22a and a plurality of flat portions 22b are alternately formed on the surface of the second optical layer 22 on the observer side. The unit shape 22a and the flat portion 22b extend in the second direction (x direction) along the surface of the second optical layer 22 on the observer side, and a plurality of the unit shapes 22a and the flat portion 22b extend in the first direction (z direction). It is arranged.

In FIG. 9, each unit shape and each flat portion provided on the first optical layer 21 and the second optical layer 22 are formed to have the same dimensions, and W1 = W2, W3 = W4, P1 = P2. However, an example is shown in which R1 <R2 only with respect to the radius of curvature.
The modified form of the optical sheet 20 shown in FIG. 9 is the arrangement pitch P1 of the unit shape 21a, the arrangement pitch P2 of the unit shape 22a, and the difference in the refractive index between the unit shape 21a adjacent to each other at the interface 201 and the second optical layer 22. Δn1 is the same range as that of the first embodiment described above.

Further, as shown in the first embodiment described above, the modified optical sheet 20 shown in FIG. 9 preferably satisfies both (Equation 9) and (Equation 10) in order to obtain a preferable diffusion action. It is more preferable to satisfy both (Equation 11) and (Equation 12). As a result, the optical sheet 20 can diffuse the image light V without causing moire, diffraction, or the like.
Further, in order to make the diffusion action of the modified optical sheet 20 shown in FIG. 9 within a preferable range, the index 1 (formula 1) and (formula 2) or the index 2 (formula 5) and (formula 6) are set. ), It is preferable to satisfy at least one combination, and it is more preferable to satisfy both. As a result, it is possible to observe a good image in which the non-image area F2 is difficult to see, the pixel area G1 cannot be seen independently, and the image is not too blurred.
Further, in order to optimize the diffusing action of the modified optical sheet 20 shown in FIG. 9, the index 1 (Equation 3) and (Equation 4) or the index 2 (Equation 2), which are stricter conditions, are used. It is more preferable to satisfy at least one combination of the formulas 7) and (8).
Furthermore, it is preferable that the modified optical sheet 20 shown in FIG. 9 is formed so that the above-mentioned half-value angle α and viewing angle β satisfy β ≦ 5 × α.

The modified form of the optical sheet 20 shown in FIG. 9 is a direct observer of the light emitted from the image source 11 and incident from the surface of the optical sheet 20 on the image source side and transmitted through the flat portion 21b and the flat portion 22b. In addition to emitting light to the side, the light incident on the unit shape 21a is diffused in the arrangement direction (x direction) of the unit shape 21a, and the light incident on the unit shape 22a is diffused in the arrangement direction (z direction) of the unit shape 22a. It can be emitted to the lens 12 side. Further, since the light transmitted through the flat portion 21b and the flat portion 22b is hardly diffused, the image light reaching the observer can be displayed more clearly.

By adopting such a form, in addition to the effect of suppressing the non-image area F2 shown in the first embodiment from being visually recognized by the observer, the display device 1 has less blurring to the observer. A clear image can be displayed. Further, by adjusting the dimensions of the flat portions 21b and 22b according to the specifications of the display device 1 (pixel arrangement pitch PP and the distance between the observer's eye E and the image source 11), specific diffusion is appropriately performed. Since the range of the corners can be defined, it is possible to more efficiently display a clear image and suppress the visual recognition of the non-image area F2.
Although the modified form of the optical sheet 20 of the first embodiment has been described as an example, the present invention is not limited to this, and this modified form can also be applied to the optical sheet 40 of the second embodiment.

(2) In each embodiment, the optical sheets 20 and 40 are arranged between the image source 11 and the lens 12, but the present invention is not limited to this, and the observer side (-Y side) of the lens 12 is not limited to this. It may be arranged on the −y side).
FIG. 10 is a diagram illustrating a modified form of the display device 1.
As shown in FIG. 10, the optical sheet 20 may be arranged on the observer side (−Y side) of the lens 12. Even if such an arrangement is adopted, the display device 1 can display a clear image with less blurring because the pixel area G1 cannot be seen independently by the observer, the non-image area F2 is difficult to see. ..
Even when the optical sheet 20 is arranged at such a position, the range of the refractive index difference Δn1 and the numerical range of each formula shown in each index may satisfy the range shown in the first embodiment.
In the modified form of the display device 1 shown in FIG. 10, an example in which the optical sheet 20 of the first embodiment is used is shown, but the present invention is not limited to this, and the optical sheet 40 of the second embodiment may be used.

(3) In the first embodiment, the refractive index of the unit shape 21a of the first optical layer 21 is higher than the refractive index of the second optical layer 22, and in the second embodiment, the unit shape 41a of the first optical layer 41 And the example in which the refractive index of the third optical layer 43 is higher than the refractive index of the second optical layer 42 is shown, but the present invention is not limited to this, and for example, in the first embodiment, the first optical layer 21 The refractive index of the first optical layer 41 and the third optical layer 43 is lower than the refractive index of the second optical layer 42 in the form in which the refractive index of the second optical layer 22 is lower than the refractive index of the second optical layer 22 or in the second embodiment. It may be in the form of lowering.
Further, in each embodiment, the first optical layers 21 and 41 show a form in which a plurality of unit shapes are formed on one surface of the base material layer, but the present invention is not limited to this, and the first optical layers 21 and 41 may be a single layer. ..

(4) In each embodiment, each unit shape shows a form that is convex toward the observer side, but the present invention is not limited to this, and any of them may be a form that is convex toward the image source side, and one of them may be convex. It may be a form that is convex toward the observer and the other is convex toward the image source.
More preferably, at the interface where a plurality of unit shapes are formed, the unit shape is preferably formed so as to be convex toward the optical layer having a low refractive index, but the unit shape is not limited to this.

(5) In each embodiment, a region between the optical sheets 20 and 40 and the display surface 11a through which at least the image light V that reaches the observer's eye E (light that the observer sees) passes through. There may be no air layer in the air layer.
Examples of such a form include a form in which the optical sheets 20 and 40 are integrally laminated on the display surface 11a, and an index matching between the display surface 11a of the image source 11 and the optical sheets 20 and 40. Examples thereof include a form in which a resin layer or the like is filled. The resin for index matching may have a function of determining the positions of the optical sheets 20 and 40 and supporting the positions.
In such a form, at least the light (observation) that reaches the observer's eye E of the image light V between the display surface 11a of the image source 11 and the surface of the optical sheets 20 and 40 on the observer side. The difference in refractive index at the interface between the members in the region through which the light (light that is visually recognized by a person) is transmitted is preferably less than 0.3. With such a form, the interface through which the image light is transmitted is reduced, and the light amount loss due to reflection at the interface can be reduced.

(6) In each embodiment, the extending direction (z direction) of the unit shape 21a is the vertical direction (vertical direction) when viewed from the thickness direction of the optical sheet 20 (normal direction of the sheet surface, Y direction, y direction). ) May be formed at an angle of 10 ° or more and 80 ° or less. By arranging them so as to form such an angle, for example, the pixel regions G1 (pixels) arranged in the vertical direction and the horizontal direction as shown in FIG. 4 and the extending direction (z direction) of the unit shapes 21a and 22a. , X direction) and at an angle of 10 ° or more and 80 ° or less. This makes it possible to reduce moire with pixels and effectively suppress color unevenness.

(7) In the second embodiment, the optical sheet 40 shows a form in which three optical layers of a first optical layer 41, a second optical layer 42, and a third optical layer 43 are sequentially laminated, but the present invention is limited to this. However, the form may include four or more optical layers depending on the desired optical performance and the like.

(8) In each embodiment, the optical sheets 20 and 40 show a form of being held by the holding portion 32, but the present invention is not limited to this, and for example, the observer of the opening 311 of the holding portion 31 that holds the image source 11. It may be joined to the side or the like so as to close the opening 311, or it may be attached to the image source side of the opening 331 of the holding portion 33 holding the lens 12 so as to close the opening 331. good.

(10) In each embodiment, the image source 11 may be fixed to the display device 1 in advance and may be non-detachable.

Although the present embodiment and the modified form can be used in combination as appropriate, detailed description thereof will be omitted. Further, the present invention is not limited to the above-described embodiments and the like.

1 Display device 11 Image source 11a Display surface 11e Display layer 12 Lens 12a Reflection suppression layer 20, 40 Optical sheet 21, 41 First optical layer 21a, 41a Unit shape 22, 42 Second optical layer 22a, 42a Unit shape 43 Third Optical layer 30 housing

Claims (15)

A video source in which multiple pixel areas are arranged and emits video light,
A lens that magnifies the image light and emits it to the observer side.
An optical sheet arranged between the image source and the lens or on the observer side of the lens.
Is a display device equipped with
In the optical sheet, two or more optical layers are laminated, a plurality of convex or concave first unit shapes are formed at an interface between adjacent optical layers, and another interface between adjacent optical layers is formed. Alternatively, a plurality of convex or concave second unit shapes are formed at the interface between the optical layer and air.
The first unit shape extends in a first direction in the sheet surface orthogonal to the thickness direction of the optical sheet and is arranged in a second direction orthogonal to the first direction in the sheet surface.
The second unit shape extends in a second direction in the sheet surface orthogonal to the thickness direction of the optical sheet and is arranged in a first direction orthogonal to the second direction in the sheet surface.
When viewed from the thickness direction of the optical sheet, the first unit shape and the second unit shape are orthogonal to each other in the extending direction.
The brightness at the diffusion angle θ of the first unit shape is I ₁ (θ), the distance between the lens and the interface on which the first unit shape is formed is K1, and the effective radius of the lens is R3. When, the average diffusion angle θave1 of the first unit shape is set to

When the distance between the interface on which the first unit shape is formed and the display layer of the image source is L1, and the pixel arrangement pitch in which the pixel areas are arranged is PP.
15 ≦ θave1 × L1 / PP ≦ 60
Meet, and more
The brightness at the diffusion angle θ of the second unit shape is I ₂ (θ), the distance between the lens and the interface on which the second unit shape is formed is K2, and the effective radius of the lens is R3. When, the average diffusion angle θave2 of the first unit shape is set to

When the distance between the interface on which the second unit shape is formed and the display layer of the image source is L2, and the pixel arrangement pitch in which the pixel areas are arranged is PP.
15 ≦ θave2 × L2 / PP ≦ 60
To meet,
A display device characterized by. In the display device according to claim 1,
23 ≦ θave1 × L1 / PP ≦ 35
23 ≦ θave2 × L2 / PP ≦ 35
To meet together,
A display device characterized by. A video source in which multiple pixel areas are arranged and emits video light,
A lens that magnifies the image light and emits it to the observer side.
An optical sheet arranged between the image source and the lens or on the observer side of the lens.
Is a display device equipped with
In the optical sheet, two or more optical layers are laminated, a plurality of convex or concave first unit shapes are formed at an interface between adjacent optical layers, and another interface between adjacent optical layers is formed. Alternatively, a plurality of convex or concave second unit shapes are formed at the interface between the optical layer and air.
The first unit shape extends in a first direction in the sheet surface orthogonal to the thickness direction of the optical sheet and is arranged in a second direction orthogonal to the first direction in the sheet surface.
The second unit shape extends in a second direction in the sheet surface orthogonal to the thickness direction of the optical sheet and is arranged in a first direction orthogonal to the second direction in the sheet surface.
When viewed from the thickness direction of the optical sheet, the first unit shape and the second unit shape are orthogonal to each other in the extending direction.
In the first unit shape, the cross-sectional shape in the cross section parallel to the thickness direction of the optical sheet and parallel to the second direction is formed in a substantially arc shape.
The second unit shape has a substantially arcuate cross-sectional shape in a cross section parallel to the thickness direction of the optical sheet and parallel to the first direction.
The pitch at which the first unit shapes are arranged is P1, the radius of curvature of the arcuate shape of the cross-sectional shape of the first unit shape is R1, and they are adjacent to each other via the interface on which the first unit shape is formed. The refractive index of the region having the higher refractive index is defined as na, the refractive index of the region having the refractive index lower than na is defined as nb, and the interface on which the first unit shape is formed and the image source are displayed. Let L1 be the distance between the layers, and the degree of diffusion D1 as an index indicating the degree to which the image light is diffused by the first unit shape.
D1 = (P1 / R1) x (1- (nb / na)) x L1
Defined as
The pitch at which the second unit shape is arranged is P2, the refractive index of the arcuate shape of the cross-sectional shape of the first unit shape is R2, and they are adjacent to each other via the interface on which the second unit shape is formed. The refractive index of the region having a higher refractive index is defined as nc, and the refractive index of the region having a lower refractive index than nc is defined as nd. Let L2 be the distance between the layers, and the degree of diffusion D2 as an index indicating the degree to which the image light is diffused by the second unit shape.
D2 = (P2 / R2) x (1- (nd / nc)) x L1
Defined as
When the pixel arrangement pitch in which the pixel areas are arranged is PP,
1.0 ≤ D1 / PP ≤ 2.0
1.0 ≤ D2 / PP ≤ 2.0
To meet together,
A display device characterized by. In the display device according to claim 3,
1.2 ≤ D1 / PP ≤ 1.7
1.2 ≤ D2 / PP ≤ 1.7
To meet together,
A display device characterized by. In the display device according to any one of claims 1 to 4.
The pitch at which the first unit shape is arranged is P1, and the distance between the interface on which the first unit shape is formed and the display layer of the image source is L1.
When the pitch at which the second unit shape is arranged is P2 and the distance between the interface on which the second unit shape is formed and the display layer of the image source is L2.
0.005 ≤ P1 / L1 ≤ 0.05
0.005 ≤ P2 / L2 ≤ 0.05
To meet together,
A display device characterized by. In the display device according to any one of claims 1 to 5.
At the interface between the optical layers adjacent to each other, the difference in refractive index in the region adjacent to the interface is 0.005 or more and 0.2 or less.
A display device characterized by. In the display device according to claim 1 to claim 6 or 1.
The optical sheet has three or more layers of the optical layer.
A plurality of the first unit shape and the second unit shape are provided at different interfaces between adjacent optical layers.
A display device characterized by. In the display device according to claim 7,
The optical sheet has flat surfaces on both sides.
A display device characterized by. In the display device according to any one of claims 1 to 6.
The optical sheet has two layers of the optical layers laminated on each other.
A plurality of the first unit shapes are provided at the interface between the two optical layers.
A plurality of the second unit shapes are provided at the interface between the optical layer and air of one of the two layers.
A display device characterized by. In the display device according to any one of claims 1 to 9.
There is no air layer between the display surface of the image source and the surface of the optical sheet on the observer side, at least in the region of the image light through which the light reaching the observer is transmitted. ,
A display device characterized by. In the display device according to any one of claims 1 to 10.
The difference in refractive index at the interface between the members in the region between the display surface of the image source and the surface of the optical sheet on the observer side, at least in the region of the image light through which the light reaching the observer is transmitted, is. Must be less than 0.3
A display device characterized by. In the display device according to any one of claims 1 to 11.
A layer having at least one of an antireflection function, an antifouling function, and an antistatic function is provided on at least one surface of the optical sheet.
A display device characterized by. The display device according to any one of claims 1 to 12.
The first direction is an angle of 10 ° or more and 80 ° or less with respect to the arrangement direction of the pixel region when viewed from the thickness direction of the optical sheet.
A display device characterized by. In the display device according to any one of claims 1 to 13.
The optical sheet has a half-value angle α of transmitted light incident from the surface on the image source side at an incident angle of 0 ° and emitted to the observer side, and the angle of view is such that the brightness of the transmitted light is 1/20 of the maximum brightness. When the angle β
Satisfying β ≦ 5 × α,
A display device characterized by. The display device according to any one of claims 1 to 14.
The distance between the optical sheet and the image source can be changed and can be fixed at a predetermined position.
A display device characterized by.

Images