JP7240635B2 - Optical member and display device with optical member - Google Patents

Description

The present invention relates to an optical member facing a display surface of a display device and a display device with an optical member having the optical member.

2. Description of the Related Art As a display device for displaying images, for example, an organic EL display device for displaying an image by causing a light-emitting layer based on organic electroluminescence (organic EL) to emit light is known. Organic EL display devices are used in various display devices because of their high luminous efficiency, low voltage drive, light weight, and the like. In particular, in recent years, organic EL display devices have been adopted as display devices for small portable terminals.

In particular, in a small portable terminal, a displayed image may be observed from an oblique direction that is greatly inclined with respect to the front direction of the display device. In an organic EL display device, when the displayed image is viewed obliquely, the image may appear bluish. If the image becomes bluish, the color reproducibility of the image is impaired. That is, when observed from an oblique direction, the image is observed with deterioration.

In order to prevent an image from appearing bluish when viewed obliquely, for example, Patent Document 1 proposes providing a diffusion layer so as to face an organic EL light-emitting layer. By diffusing the light from the light-emitting layer with the diffusion layer, light of various wavelengths is emitted even in oblique directions, thereby preventing images from appearing bluish.

JP-A-2005-322489

However, the provision of the diffusion layer is not preferable because it blurs the image displayed on the display surface and deteriorates the image. Further, when a member having an uneven shape as in Patent Document 1 is provided, light is diffracted by the uneven shape, and rainbow unevenness as a diffraction image can be observed superimposed on the image. Iridescence can degrade the image displayed on the display surface.

SUMMARY OF THE INVENTION The present invention has been made in consideration of such points, and an object of the present invention is to suppress the occurrence of iridescent unevenness and to suppress the deterioration of image visibility.

An optical member of the present invention is an optical member facing a display surface of a display device,
a circularly polarizing plate;
and an optical sheet laminated on the circularly polarizing plate,
The optical sheet includes a plurality of first portions arranged in a first direction and each extending in a second direction intersecting the first direction, and the first portions and the first portions alternately arranged along the first direction. a second portion;
The first portion has a width along the first direction that increases as it approaches the circularly polarizing plate,
The refractive index of the first portion is greater than the refractive index of the second portion.

In the optical member of the present invention, the second portion may have adhesiveness.

The optical member of the present invention further comprises a second optical sheet provided between the circularly polarizing plate and the optical sheet,
the second optical sheet includes a plurality of third portions arranged in a third direction intersecting the first direction and each extending in a fourth direction intersecting the third direction; and fourth portions alternately arranged along a direction,
The third portion has a larger width along the third direction on a side closer to the circularly polarizing plate,
The refractive index of the third portion may be greater than the refractive index of the fourth portion.

In the optical member of the present invention, the fourth portion may have adhesiveness.

In the optical member of the present invention, the first direction and the third direction may be orthogonal.

The display device with an optical member of the present invention is
a display device having a display surface;
any one of the optical members described above arranged facing the display surface,
In the optical member, the side on which the optical sheet is provided faces the display surface.

In the display device with an optical member of the present invention, the pitch of arrangement of the first portions in the first direction may be smaller than the pitch of pixels of the display device.

In the display device with an optical member of the present invention, the display device may be an organic EL display device.

According to the present invention, it is possible to suppress the occurrence of iridescent unevenness and suppress deterioration of image visibility.

FIG. 1 is a perspective view of a display device with an optical member according to one embodiment of the invention. FIG. 2 is a cross-sectional view of the display device with an optical member in FIG. 1 taken along line II-II. FIG. 3 is a cross-sectional view of the display device with an optical member in FIG. 1 taken along line III-III. FIG. 4 is a cross-sectional view of an optical member included in a display device with an optical member, and is a diagram for explaining the action of light passing through the optical member. FIG. 5 is a graph showing the color change of light emitted from the display device with the optical member with respect to the tilt angle of the display device with the optical member with respect to the front direction.

An embodiment of the present invention will be described below with reference to the drawings. In the drawings attached to this specification, for the convenience of illustration and ease of understanding, the scale and the ratio of vertical and horizontal dimensions are changed and exaggerated from those of the real thing.

In addition, "sheet surface (plate surface, film surface)" refers to the target sheet-shaped member (plate-shaped, film-shaped) when viewed as a whole and broadly. member, film-like member).

Furthermore, the terms used herein to specify shapes and geometric conditions and their degrees, such as "parallel", "perpendicular", "identical", length and angle values, etc., are not strictly defined. It shall be interpreted to include the extent to which similar functions can be expected without being bound by the meaning.

FIG. 1 is an exploded perspective view schematically showing a display device 1 with an optical member according to one embodiment of the invention. A display device 1 with an optical member has a display device 10 having a display surface 11 and an optical member 20 arranged to face the display surface 11 . The display device 10 and the optical member 20 are stacked in the stacking direction dL. The display device 1 with an optical member allows an external observer to observe an image displayed on the display surface 11 of the display device 10 through the optical member 20 .

The display device 10 can display an image or the like on the display surface 11 . The display device 10 includes multiple pixels. Each pixel includes, for example, three sub-pixels of red, green and blue. In this embodiment, the display device 10 is an organic EL display device. An organic EL display device includes a pair of electrodes and a light-emitting layer made of an organic material provided between the pair of electrodes. At least one of the pair of electrodes is divided for each sub-pixel. Since at least one of the electrodes is divided for each subpixel, the voltage applied to the light emitting layer can be controlled for each subpixel. By controlling the voltage applied to the electrode for each sub-pixel, the light-emitting layer can emit light for each sub-pixel. As sub-pixels, red, green, and blue light emitting layers may be used, and red, green, and blue color filters may be provided on white light emitting layers. By controlling the light emission color of each sub-pixel, each pixel can emit light of a desired color. Thus, an image can be displayed on the organic EL display device. The pixel pitch of the display device 10 is determined by the size of the display device 10 and the number of pixels required for the display device 10, and is, for example, 30 μm or more and 70 μm or less.

The optical member 20 exerts an optical action on the image light emitted from the display surface 11 of the display device 10 to suppress deterioration of the image. The optical member 20 is arranged facing the display surface 11 of the display device 10 . The optical member 20 is a flat member. The optical member 20 includes a circular polarizer 25, an optical sheet 30 laminated on the circular polarizer 25, a second optical sheet 40 provided between the circular polarizer 25 and the optical sheet 30, and the circular polarizer 25. and an adhesive layer 27 that adheres the second optical sheet 40 to the second optical sheet 40 . In other words, the circularly polarizing plate 25, the adhesive layer 27, the second optical sheet 40, and the optical sheet 30 are laminated in this order in the lamination direction dL. In the illustrated example, the circularly polarizing plate 25 forms the surface of the display device 1 with an optical member. Note that the second optical sheet 40 may be omitted without being limited to the illustrated example. In this case, the adhesive layer 27 bonds the circularly polarizing plate 25 and the optical sheet 30 together.

The circularly polarizing plate 25 suppresses external light that has entered the optical member 20 and is reflected inside the optical member 20 from exiting to the viewer side. The circularly polarizing plate 25 has a polarizing member and a retardation member that are laminated to each other. The side on which the retardation member is provided is the side to be adhered to the second optical sheet 40 by the adhesive layer 27 . The polarizing member is, for example, an absorptive polarizing plate, which decomposes incident light into two orthogonal polarized components (a p-polarized component and an s-polarized component), and a straight line oscillating in one direction (direction parallel to the transmission axis). It has a function of transmitting a polarized component (e.g., p-polarized component) and absorbing a linearly polarized component (e.g., s-polarized component) vibrating in the other direction (direction parallel to the absorption axis) perpendicular to the one direction. are doing. The retardation member is, for example, a 1/4 wavelength retardation plate, and modulates the phase of transmitted light by 1/4 wavelength. Therefore, the light incident from the polarizing member side and transmitted through the circularly polarizing plate 25 becomes only a linearly polarized component that oscillates in one direction by the polarizing member, and the linearly polarized component is changed to a right circularly polarized component or a left circularly polarized component by the phase difference member. It becomes the light of the circularly polarized component.

The adhesive layer 27 bonds the circularly polarizing plate 25 and the second optical sheet 40 together. As such an adhesive layer 27, a layer made of a material having various adhesiveness or cohesiveness can be used. Moreover, it is preferable to use a material having a high visible light transmittance for the adhesive layer 27 . As a typical adhesive layer 27, for example, a layer made of acrylic resin, acrylic-modified silicone resin, or silicone resin can be exemplified. In order to make the optical member 20 thinner and to increase the visible light transmittance of the adhesive layer 27, it is preferable that the adhesive layer 27 is not too thick. On the other hand, in order to properly bond the circularly polarizing plate 25 and the second optical sheet 40, it is preferable that the adhesive layer 27 is not too thin. Specifically, the thickness of the adhesive layer 27 is preferably 5 μm or more and 25 μm or less.

The optical sheet 30 includes a substrate 31, a plurality of first portions 33 provided on the substrate 31 and arranged in the first direction d1, and the first portions 33 and the first portions 33 are alternately arranged along the first direction d1. a second portion 35; The first direction d1 is a direction non-parallel to the stacking direction dL, and is a direction orthogonal to the stacking direction dL in the illustrated example. An optical interface is formed between the first portion 33 and the second portion 35 of the optical sheet 30 . Due to the optical action at this interface, the optical sheet 30 can easily emit image light in a direction inclined in the first direction d1 with respect to the front direction (normal direction) of the display device 1 with an optical member. . Note that the base material 31 may be omitted. Alternatively, the base material 31 may be made of the same material as the first portion 33 and formed integrally with the first portion 33 .

As shown in FIG. 1, the first portion 33 and the second portion 35 linearly or curvedly extend in a second direction d2 intersecting the first direction d1. The second direction d2 is a direction non-parallel to the stacking direction dL, and is a direction orthogonal to the stacking direction dL in the illustrated example. Also, in the illustrated example, the first direction d1 and the second direction d2 are orthogonal to each other. In the illustrated example, the second portion 35 covers the first portion 33 in the stacking direction dL. That is, the first portion 33 is positioned between the base material 31 and the second portion 35 in the stacking direction dL. As a result, in the illustrated example, the first portion 33 is entirely covered by the substrate 31 and the second portion 35 . The optical sheet 30 has the substrate 31 side closer to the circularly polarizing plate 25 . Therefore, the side of the optical sheet 30 opposite to the substrate 31 , that is, the side of the second portion 35 faces the display device 10 .

The base material 31 is a support base material that supports the first portion 33 . The base material 31 has a high visible light transmittance. Triacetyl cellulose (TAC) can be exemplified as a material of such base material 31 . The base material 31 preferably has a thickness of 20 μm or more and 80 μm or less in consideration of light transmittance, appropriate supportability of the first portion 33, and the like.

As shown in FIG. 2 , the cross-sectional shape of the first portion 33 is a substantially trapezoidal shape with a long bottom on the base material 31 side and a short bottom on the side facing the base material 31 . That is, the cross-sectional shape of the first portion 33 increases in width along the first direction d1 as it approaches the circularly polarizing plate 25 . Here, "the width along the first direction d1 increases as it approaches the circularly polarizing plate 25" means that the width along the first direction d1 increases continuously according to the distance from the circularly polarizing plate 25. It means not only that it keeps changing, but also that it does not include a portion where the width along the first direction d1 becomes smaller as it approaches the circularly polarizing plate 25. It also includes a stepwise change in width along one direction d1. However, it is preferable that the cross-sectional shape of the first portion 33 continue to change continuously according to the distance from the circularly polarizing plate 25 .

As for the cross-sectional shape of the first portion 33, the leg portions of the trapezoidal shape may be curved lines instead of straight lines. By changing the cross-sectional shape of the first portion 33, the optical interface between the first portion 33 and the second portion 35 is changed, and desired optical characteristics can be exhibited depending on the shape of the interface. The length of the base material 31 side of the first portion 33 in the cross section shown in FIG. The length of the side opposite to (the length of the upper base of the trapezoidal cross section) is, for example, 0.1 μm or more and 20 μm or less. Also, the height of the first portion 33, that is, the length along the stacking direction dL is, for example, 0.1 μm or more and 20 μm or less.

In addition, the pitch at which the plurality of first portions 33 are arranged in the first direction d<b>1 is smaller than the pitch of the pixels of the display device 10 . In particular, the ratio of the pitch of the arrangement of the first portions 33 in the first direction d1 to the pitch of the pixels of the display device 10 is preferably 1/5 or less, more preferably 1/10 or less. Specifically, the pitch of the arrangement of the first portions 33 in the first direction d1 is, for example, 20 μm or less, preferably 5 μm or less, and more preferably 2.5 μm or less.

The first portion 33 has a high visible light transmittance. Such a first portion 33 can be formed, for example, by arranging an ultraviolet curable resin such as urethane acrylate at a position on the substrate 31 where the first portion 33 is to be formed, and irradiating ultraviolet rays to cure the resin. can.

As shown in FIG. 2 , the second portion 35 flattens the uneven shape formed by the base material 31 and the first portion 33 . That is, the second portion 35 fills the space between the adjacent first portions 33 . Also, the second portion 35 has a high visible light transmittance. Furthermore, the second part 35 has adhesiveness. The adhesiveness of the second portion 35 allows the optical sheet 30 and the display device 10 to adhere to each other. Such a second portion 35 can be formed of, for example, an acrylic adhesive film or an ultraviolet curable adhesive.

The refractive index of the first portion 33 is higher than that of the second portion 35 . The difference between the refractive index of the first portion 33 and the refractive index of the second portion 35 is preferably 0.11 or more. Specifically, the refractive index of the first portion 33 is 1.6 or more, and the refractive index of the second portion 35 is 1.49 or less. It should be noted that the comparison between the refractive index of the first portion 33 and the refractive index of the second portion 35 depends on, for example, the refraction direction and total reflection conditions of light incident on the interface between the first portion 33 and the second portion 35. can be confirmed. A specific value of the refractive index can be measured, for example, with an Abbe refractometer (eg, RX-7000α manufactured by Atago Co., Ltd.).

The second optical sheet 40 includes a second substrate 41, a plurality of third portions 43 provided on the second substrate 41 and arranged in the third direction d3, and a and fourth portions 45 interleaved with each other. The third direction d3 is a direction non-parallel to the stacking direction dL, and is a direction orthogonal to the stacking direction dL in the illustrated example. Also, in the illustrated example, the third direction d3 is a direction orthogonal to the first direction d1 and the same direction as the second direction d2. An optical interface is formed between the third portion 43 and the fourth portion 45 of the second optical sheet 40 . Due to the optical action at this interface, the second optical sheet 40 facilitates emission of image light in a direction inclined in the third direction d3 with respect to the front direction (normal direction) of the display device 1 with an optical member. Note that the second base material 41 may be omitted. Alternatively, the second base material 41 may be made of the same material as the third portion 43 and may be formed integrally with the third portion 43 .

The third portion 43 and the fourth portion 45 linearly or curvedly extend in a fourth direction d4 intersecting the third direction d3. The fourth direction d4 is a direction non-parallel to the stacking direction dL, and is a direction orthogonal to the stacking direction dL in the illustrated example. Also, in the illustrated example, the third direction d3 and the fourth direction d4 are orthogonal to each other. Therefore, the fourth direction d4 is a direction perpendicular to the second direction d2 and the same direction as the first direction d1. In the illustrated example, the fourth portion 45 covers the third portion 43 in the stacking direction dL. That is, the third portion 43 is positioned between the second base material 41 and the fourth portion 45 in the stacking direction dL. As a result, in the illustrated example, the third portion 43 is entirely covered by the second base material 41 and the fourth portion 45 . The second optical sheet 40 has the second substrate 41 side closer to the circularly polarizing plate 25 . Therefore, the second optical sheet 40 faces the optical sheet 30 on the side opposite to the second substrate 41 , that is, on the side of the fourth portion 45 .

The second base material 41 is a support base material that supports the third portion 43 . The second base material 41 has a high visible light transmittance. Triacetyl cellulose (TAC) can be exemplified as a material of such second base material 41 . The second base material 41 preferably has a thickness of 25 μm or more and 80 μm or less in consideration of light transmittance, appropriate supportability of the third portion 43, and the like.

As shown in FIG. 3 , the cross-sectional shape of the third portion 43 is a substantially trapezoidal shape with a long bottom on the side facing the second base material 41 and a short bottom on the side facing the second base material 41 . That is, the cross-sectional shape of the third portion 43 increases in width along the third direction d3 as it approaches the circularly polarizing plate 25 . Here, "the width along the third direction d3 increases as it approaches the circularly polarizing plate 25" means that the width along the third direction d3 is continuously increased according to the distance from the circularly polarizing plate 25. It means that not only does it continue to change, but it does not include a portion where the width along the third direction d3 decreases as it approaches the circularly polarizing plate 25. It also includes a stepwise change in width along the three directions d3. However, it is preferable that the cross-sectional shape of the third portion 43 continues to change continuously according to the distance from the circularly polarizing plate 25 .

As for the cross-sectional shape of the third portion 43, the leg portions of the trapezoidal shape may be curved lines instead of straight lines. By changing the cross-sectional shape of the third portion 43, the optical interface between the third portion 43 and the fourth portion 45 is changed, and desired optical characteristics can be exhibited depending on the shape of the interface. The length of the third portion 43 on the side of the second substrate 41 in the cross section shown in FIG. The length of the side facing the second base material 41 (the length of the upper base of the trapezoidal cross section) is, for example, 0.1 μm or more and 20 μm or less. Further, the height of the third portion 43, that is, the length along the stacking direction dL is, for example, 0.1 μm or more and 20 μm or less.

Also, the pitch of the arrangement of the plurality of third portions 43 in the third direction d<b>3 is smaller than the pitch of the pixels of the display device 10 . The ratio of the pitch of the arrangement of the third portions 43 in the third direction d3 to the pitch of the pixels of the display device 10 is preferably 1/5 or less, more preferably 1/10 or less. Specifically, the pitch of the arrangement of the third portions 43 in the third direction d3 is, for example, 20 μm or less, preferably 5 μm or less, and more preferably 2.5 μm or less.

The third portion 43 has a high visible light transmittance. Such a third portion 43 is formed, for example, by arranging an ultraviolet curable resin such as urethane acrylate at a position on the second substrate 41 where the third portion 43 is to be formed, and curing the resin by irradiating ultraviolet rays. be able to.

As shown in FIG. 3 , the fourth portion 45 flattens the irregularities formed by the second base material 41 and the third portion 43 . That is, the fourth portion 45 fills the space between the adjacent third portions 43 . Also, the fourth portion 45 has a high visible light transmittance. Furthermore, the fourth portion 45 has adhesiveness. The adhesiveness of the fourth portion 45 allows the second optical sheet 40 and the optical sheet 30 to be adhered. Such a fourth portion 45 can be formed of, for example, an acrylic adhesive film or an ultraviolet curable adhesive.

The refractive index of the third portion 43 is higher than that of the fourth portion 45 . The difference between the refractive index of the third portion 43 and the refractive index of the fourth portion 45 is preferably 0.11 or more. Specifically, the refractive index of the third portion 43 is 1.6 or more, and the refractive index of the fourth portion 45 is 1.49 or less. Note that the comparison between the refractive index of the third portion 43 and the refractive index of the fourth portion 45 depends on, for example, the refraction direction and total reflection conditions of light incident on the interface between the third portion 43 and the fourth portion 45. can be confirmed. A specific value of the refractive index can be measured, for example, with an Abbe refractometer (eg, RX-7000α manufactured by Atago Co., Ltd.).

Next, the operation of the display device 1 with an optical member will be described.

Light entering the display device 1 with an optical member from the outside enters the circularly polarizing plate 25 of the optical member 20 . The light incident on the circularly polarizing plate 25 becomes only a linearly polarized component that oscillates in one direction by the polarizing member, and the linearly polarized component becomes right circularly polarized light or left circularly polarized light by the phase difference member. Most of the light that has passed through the circularly polarizing plate 25 passes through the optical sheet 30 and the second optical sheet 40 and is reflected by, for example, the display surface 11 of the display device 10 . Reflection reverses the polarization components of the light. That is, the light of the right circularly polarized light component becomes the light of the left circularly polarized light component, and the light of the left circularly polarized light component becomes the light of the right circularly polarized light component. After that, the light passes through the optical sheet 30 and the second optical sheet 40 again and enters the circularly polarizing plate 25 . The retardation member of the circularly polarizing plate 25 converts the circularly polarized component into a linearly polarized component. Since the polarization component is reversed by the reflection on the display surface 11, the linear polarization component is perpendicular to the direction of transmission through the polarizing member. Therefore, the light does not pass through the polarizing member of the circularly polarizing plate 25 and is absorbed. In this way, even if the light incident on the display device 1 with an optical member from the outside is reflected inside the display device 1 with an optical member, it is difficult for the light to be emitted to the outside. That is, deterioration of the image due to reduction in the contrast of the image displayed on the display device 1 with an optical member due to external light is suppressed.

Further, the image light L1 (see FIG. 4) emitted from the display surface 11 of the display device 10 can pass through the optical sheet 30 and the second optical sheet 40 . The image light then enters the circularly polarizing plate 25 . The phase difference member of the circularly polarizing plate 25 shifts the polarized light component by 1/4 wavelength, and the light of the linearly polarized light component oscillating in one direction is transmitted by the polarizing member. That is, the image light emitted from the display surface 11 of the display device 10 is transmitted through the optical member 20 and can be visually recognized by an external observer.

By the way, as described above, in the organic EL display device, when an image is observed from a direction greatly inclined with respect to the front direction, the image light may be observed with a bluish tinge. That is, the image deteriorates in observation from a direction greatly inclined with respect to the front direction. On the other hand, in the display device 1 with an optical member of the present embodiment, the optical member 20 includes the optical sheet 30 having the first portions 33 and the second portions 35 alternately arranged along the first direction d1. .

The width of the first portion 33 along the first direction d1 increases as it approaches the circularly polarizing plate 25 , in other words, as it separates from the display device 10 . Therefore, as shown in FIG. 4, the image lights L2 and L3 traveling in the front direction and the image lights L4 and L5 traveling in directions oblique to the front direction first enter the second portion of the optical sheet, and then In addition, it becomes easier to advance to the interface between the second portion 35 and the side surface of the first portion 33 . Here, the refractive index of the first portion 33 is higher than that of the second portion 35 . Therefore, the image light beams L2 to L5 are refracted at the interface between the second portion 35 and the side surface of the first portion 33 so as to increase the angle of inclination with respect to the front direction. After that, some of the image lights L2 and L4 are emitted from the optical sheet, and some of the image lights L3 and L5 are further refracted at the interface between the side surface of the first portion 33 and the second portion 35, and then Eject from the optical sheet 30 . These image light beams L2 to L5 are refracted at the interface between the first portion and the second portion when passing through the optical sheet, so that they travel in a direction greatly inclined with respect to the front direction. That is, the refraction action at the interface between the first portion 33 and the second portion 35 is such that when the image light is transmitted through the optical sheet 30, the traveling direction of the image light is different from the front direction as shown in FIG. This causes a tendency for the angle of engagement to increase. Therefore, light of various wavelengths forming an image can be easily emitted even in directions inclined from the front direction toward the first direction d1. Therefore, in the direction inclined from the front direction to the first direction d1, the image becomes bluish and difficult to observe.

Further, the display device 1 with an optical member according to the present embodiment further includes the second optical sheet 40 having the third portions 43 and the fourth portions 45 in which the optical members 20 are alternately arranged along the third direction d3. I have. The width of the third portion 43 along the third direction d3 increases as it approaches the circularly polarizing plate 25 , in other words, as it separates from the display device 10 . Furthermore, the refractive index of the third portion 43 is higher than that of the fourth portion 45 . When the image light is transmitted through the second optical sheet 40, the image light incident on the interface between the third portion 43 and the fourth portion 45 is inclined from the front direction to the third direction d3. refract. Therefore, light of various wavelengths forming an image is emitted also in a direction inclined from the front direction to the third direction d3. Therefore, in the direction inclined from the front direction to the third direction d3, the image becomes bluish and difficult to observe.

That is, the optical sheet 30 increases the angle formed by the traveling direction of the image light in the first direction d1 with respect to the front direction, and the second optical sheet 40 makes the traveling direction of the image light in the third direction d3 larger in the front direction. The angle to make is increased. The first direction d1 and the third direction d3 intersect, preferably perpendicular to each other. Therefore, in an arbitrary direction inclined with respect to the front direction, the image becomes bluish and difficult to observe.

A display device with an optical member of an example and a comparative example in which an optical member is arranged in an organic EL display device is created, and in a state where white is displayed on the display device, in-plane and front directions along the front direction and the first direction d1 And the color change in each direction in the plane along the third direction d3 was measured. As an example, the optical member 20 provided with the optical sheet 30 and the second optical sheet 40 laminated on the circularly polarizing plate 25 was arranged facing the display device 10 . As a comparative example, an optical member without the optical sheet and the second optical sheet, that is, only a circularly polarizing plate was arranged facing the display device. The measurement results are shown in the graph of FIG. In the graph of FIG. 5, the horizontal axis represents the inclination angle θ in the first direction d1 and the third direction d3 with respect to the front direction, and the vertical axis represents the color change Δu'v' of the light emitted from the display device with the optical member. represent. A color change Δu'v' indicates a color difference and is calculated from the colors defined by u' and v' in the uniform color space. A value of Δu'v' at an angle θ in a certain viewing angle is expressed by the following equation (1).

Color coordinates u' and v' in the uniform color space in equation (1) are expressed by the following equations (2-1) and (2-2), respectively. In each formula below, x and y are color coordinates defined in the CIE1931 color space (CIE xyY color space).

The graph shown in FIG. 5 was obtained by measuring the color change at each angle with respect to the first direction d1 and the third direction d3. The color change can be measured using, for example, "Spectroradiometer SR-2" manufactured by Topcon Corporation.

As can be seen from the graph of FIG. 5, by providing the optical sheet 30, it is possible to reduce the color change in the direction greatly inclined from the front direction to the first direction d1, especially in the direction inclined by 30° or more. Further, by providing the second optical sheet 40, it is possible to reduce the color change in a direction greatly inclined from the front direction to the third direction d3, particularly in a direction inclined by 30° or more. That is, the image becomes bluish and difficult to observe in the direction inclined from the front direction.

As a result of visual observation, when the optical sheet 30 and the second optical sheet 40 were not provided, the image was observed to be bluish in a direction inclined by 30° or more from the front direction. On the other hand, when the optical sheet 30 and the second optical sheet 40 were provided, the bluish image was not observed even in a direction inclined 30° or more from the front direction.

Further, when parallel light is transmitted through the optical sheet 30 and the second optical sheet 40, the light is diffracted by the first portion 33 of the optical sheet 30 and the third portion 43 of the second optical sheet 40, and the diffracted light has a wavelength diffracted at the same angle each time can cause rainbow mura. Parallel light can be generated, for example, by external light entering the optical member 20 and being reflected by the display surface 11 of the display device 10 . That is, when external light enters the optical member 20, rainbow unevenness may occur. Such rainbow unevenness deteriorates the visibility of an image. However, the side of the optical member 20 on which the optical sheet 30 is provided faces the display surface 11 of the display device 10 . In other words, the circularly polarizing plate 25 is further away from the display device 10 than the optical sheet 30 is. In this embodiment, the circularly polarizing plate 25 forms the surface of the display device 1 with an optical member. As described above, even if external light is reflected by a member inside the circularly polarizing plate 25, the external light is absorbed by the circularly polarizing plate 25 and is difficult to be emitted to the outside. Therefore, it is possible to suppress the occurrence of rainbow unevenness due to external light.

Image light emitted from the display device 10 is emitted as diffused light at a position near the optical sheet 30 and the second optical sheet 40 . Therefore, even if the light is diffracted by the first portion 33 of the optical sheet 30 and the third portion 43 of the second optical sheet 40, the light is diffused and visible. That is, it is difficult to observe the rainbow unevenness caused by the diffracted light being diffracted at the same angle for each wavelength.

As a result of visual confirmation, rainbow unevenness was observed when only the optical sheet was provided and the circularly polarizing plate was not provided. On the other hand, when the side on which the optical sheet 30 is provided faces the display surface 11 of the display device 10 as in the present embodiment, rainbow unevenness is not observed.

Furthermore, moire (interference fringes) may occur due to the arrangement of the first portion 33 of the optical sheet 30 and the arrangement of the third portion 43 of the second optical sheet 40 and the pixels of the display device 10 . Moire degrades the visibility of the displayed image. In the display device 1 with an optical member of the present embodiment, the pitch of arrangement of the first portions 33 in the first direction d1 and the pitch of arrangement of the third portions 43 in the third direction d3 are the same as those of the pixels of the display device 10. smaller than the pitch. Preferably, the ratio of the pitch of the arrangement of the first portions 33 in the first direction d1 to the pitch of the pixels of the display device 10 and the pitch of the arrangement of the third portions 43 in the third direction d3 to the pitch of the pixels of the display device 10 is 1/5 or less, more preferably 1/10 or less. Specifically, the arrangement pitch of the first portions 33 in the first direction d1 and the arrangement pitch of the third portions 43 in the third direction d3 are 20 μm or less, preferably 5 μm or less, and more preferably 5 μm or less. is 2.5 μm or less. Thus, the arrangement pitch of the first portions 33 in the first direction d1 and the arrangement pitch of the third portions 43 in the third direction d3 are sufficiently smaller than the pixel pitch of the display device 10. , interference between the arrangement of the first portion 33 and the arrangement of the third portion 43 and the pixels of the display device 10 is less likely to occur, and the occurrence of moiré can be suppressed.

The display device 1 with an optical member in which such an optical member 20 is arranged to face the display device 10 is an organic EL display device in which an image becomes bluish when observed from a direction in which the display device 10 is tilted from the front direction. Especially useful in some cases. However, even if the display device 10 is a display device other than the organic EL display device, it is possible to improve the color unevenness in the direction inclined from the front direction and to suppress the rainbow unevenness.

As described above, the optical member 20 of the present embodiment is an optical member facing the display surface 11 of the display device 10, and includes the circularly polarizing plate 25, the optical sheet 30 laminated on the circularly polarizing plate 25, , the optical sheet 30 includes a plurality of first portions 33 arranged in the first direction d1 and each extending in a second direction d2 intersecting the first direction d1; and second portions 35 arranged alternately in the direction of the circularly polarizing plate 25, the width of the first portion 33 along the first direction d1 increases as it approaches the circularly polarizing plate 25, and the refractive index of the first portion 33 is greater than the refractive index of the second portion 35 . According to such an optical member 20, the image light incident on the interface between the first portion 33 and the second portion 35 is refracted in a direction inclined from the front direction to the first direction d1. Therefore, light of various wavelengths forming an image is emitted also in directions inclined from the front direction toward the first direction d1. Therefore, in the direction inclined from the front direction to the first direction d1, the image becomes bluish and difficult to observe. In addition, even if external light is reflected by a member inside the circularly polarizing plate 25, the external light is absorbed by the circularly polarizing plate 25 and is difficult to be emitted to the outside. Therefore, it is possible to suppress the deterioration of the visibility of the image.

Aspects of the present invention are not limited to the individual embodiments described above, but include various modifications that can be conceived by those skilled in the art, and the effects of the present invention are not limited to the above-described contents. That is, various additions, changes, and partial deletions are possible without departing from the conceptual idea and spirit of the present invention derived from the content defined in the claims and equivalents thereof.

1 Display device with optical member 10 Display device 11 Display surface 20 Optical member 25 Circularly polarizing plate 27 Adhesive layer 30 Optical sheet 31 Base material 33 First part 35 Second part 40 Second optical sheet 41 Second base material 43 Third part 45 Part 4

Claims (6)

a display device having a display surface;
an optical member arranged facing the display surface,
The optical member comprises a circularly polarizing plate and an optical sheet laminated on the circularly polarizing plate,
In the optical member, the side on which the optical sheet is provided faces the display surface,
The optical sheet includes a plurality of first portions arranged in a first direction and each extending in a second direction intersecting the first direction, and the first portions and the first portions alternately arranged along the first direction. a second portion;
The first portion has a width along the first direction that increases as it approaches the circularly polarizing plate,
the refractive index of the first portion is greater than the refractive index of the second portion;
The pitch of the arrangement of the first portions in the first direction is smaller than the pitch of the pixels of the display device,
A display device with an optical member, wherein a ratio of a pitch of the pixels of the display device to a pitch of the arrangement of the first portion in the first direction is 1/10 or less. 2. The display device with an optical member according to claim 1, wherein said second portion has adhesiveness. further comprising a second optical sheet provided between the circularly polarizing plate and the optical sheet;
the second optical sheet includes a plurality of third portions arranged in a third direction intersecting the first direction and each extending in a fourth direction intersecting the third direction; and fourth portions alternately arranged along a direction,
The third portion has a larger width along the third direction on a side closer to the circularly polarizing plate,
3. The display device with an optical member according to claim 1, wherein said third portion has a higher refractive index than said fourth portion. 4. The display device with an optical member according to claim 3, wherein said fourth portion has adhesiveness. 5. The display device with an optical member according to claim 3, wherein said first direction and said third direction are orthogonal. 6. The display device with an optical member according to claim 1, wherein said display device is an organic EL display device.

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