JP2010008896A - Optical member and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member for obscuring moire (interference fringe) without significantly degrading the image quality. <P>SOLUTION: A display device 10 comprises a display section 20, and the sheet-like optical member 30 that is arranged on an observer side of the display section while creating clearance from the display section and transmits video light from the display section to the observer side. The optical member has: an optical function layer 50 having a plurality of light transmission sections 52 formed so as to allow transmission of light; and a plurality of light absorption sections 54 that are formed so as to allow absorption of light and arranged alternately with light transmission sections along the sheet surface of the optical member. An antireflection function is provided to a surface layer 25 facing the optical member of the display device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical member used in a display device in order to improve the contrast of an image, and more particularly to an optical member capable of making moire (interference fringes) inconspicuous without greatly degrading image quality.

  In addition, the present invention is an optical member used in a display device for improving the contrast of an image, and includes an optical member capable of making moiré (interference fringes) inconspicuous without greatly degrading image quality. Relates to the device.

Various studies have been made on optical members used in display devices in order to improve the contrast of images. For example, Patent Document 1 discloses an optical member in which light transmitting portions having light transmittance and light absorbing portions having light absorption properties are alternately arranged. According to the optical member disclosed in Patent Document 1, it is possible to improve the contrast of an image displayed on the display device by absorbing environmental light (external light) such as illumination.
JP 2006-189867 A

  By the way, when the optical member disclosed in Patent Document 1 is used, interference fringes (moire) according to the arrangement pitch of the light transmitting portions may occur. In order to suppress the generation of interference fringes, it is generally considered effective to provide a diffusion layer that diffuses light. However, if the degree of diffusion of the diffusion layer is increased in order to suppress interference fringes, image quality deteriorates due to image blurring and double image (ghost).

  In addition, as a technique for preventing the occurrence of interference fringes, it is conceivable to adjust the arrangement pitch of the light transmission parts. However, in the display device using the optical member disclosed in Patent Document 1, the occurrence of interference fringes may not be effectively prevented even if the arrangement pitch of the light transmission parts is adjusted.

  The present invention has been made in consideration of such points, and an object thereof is to provide an optical member that can make interference fringes (moire) inconspicuous without greatly degrading image quality. Another object of the present invention is to provide a display device that can make interference fringes (moire) inconspicuous without degrading image quality.

  A first display device according to the present invention is a sheet-shaped display unit that is disposed on the viewer side of the display unit with a gap from the display unit, and transmits image light from the display unit to the viewer side. An optical member, wherein the optical member is formed so as to be able to transmit light, and is formed so as to be able to absorb light, and alternately with the light transmitting portion along the sheet surface of the optical member. And an optical function layer having a plurality of light absorption portions arranged side by side, and a surface layer facing the optical member of the display portion is provided with an antireflection function.

  In the first display device according to the present invention, the display unit includes a display unit main body that emits image light, and an antireflection layer that is laminated on the display unit main body and forms a surface of the display unit on the optical member side. You may make it have. Alternatively, in the first display device according to the present invention, the display unit has a display unit main body that emits image light, and performs processing on the surface of the display unit main body on the optical member side, thereby An antireflection function may be provided.

  A second display device according to the present invention is a sheet-shaped display unit that is disposed on the viewer side of the display unit with a gap from the display unit, and transmits image light from the display unit to the viewer side. An optical member, wherein the optical member is formed so as to be able to transmit light, and is formed so as to be able to absorb light, and alternately with the light transmitting portion along the sheet surface of the optical member. It has an optical function layer having a plurality of light absorption parts arranged side by side, and a light diffusion function is given to a surface layer which faces the optical member of the display part.

  In the second display device according to the present invention, the display unit includes a display unit main body that emits image light, a light diffusion layer that is stacked on the display unit main body and forms a surface of the display unit on the optical member side, You may make it have. Alternatively, in the second display device according to the present invention, the display unit includes a display unit main body that emits image light, and performs processing on the surface of the display unit main body on the optical member side, thereby A light diffusion function may be added. In the second display device according to the present invention, the light diffusion layer may have an uneven surface that forms a surface of the display unit on the optical member side.

  In the first or second display device according to the present invention, the optical member may have a haze value of 3 or more and 10 or less.

  In the first or second display device according to the present invention, the display unit may include a plasma display panel.

  Furthermore, in the first or second display device according to the present invention, a gap between the optical member and the display unit may be larger than 0 mm and not larger than 10 mm.

  According to the present invention, interference fringes (moire) can be made inconspicuous without greatly degrading the image quality.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, a first embodiment and a second embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

[First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS.

  1 to 3 are diagrams for explaining a first embodiment of an optical member and a display device according to the present invention. Among these, FIG. 1 is a schematic diagram showing the configuration of the display device and the optical member in the first embodiment, and FIGS. 2 and 3 explain the operation of the optical member and the display device in the first embodiment. It is a figure for doing.

  As illustrated in FIG. 1, the display device 10 includes a display unit 20 and a sheet-like optical member 30 that is disposed to face the display unit 20 with a gap from the display unit 20. First, the display unit 20 will be described.

  The display unit 20 is configured as a device that emits video light that forms a predetermined image toward an observer. The surface layer facing the optical member 30 of the display unit 20 is provided with an antireflection function for preventing light coming from the optical member 30 side from being reflected on the surface layer. As shown in FIG. 1, in the present embodiment, the display unit 20 includes a display unit main body 22 that emits image light, and an antireflection layer 25 stacked on the display unit main body 22. The antireflection layer 25 is a layer having an antireflection function, and forms a light exit surface of the display unit 20 on which the optical member side surface of the display unit 20, in other words, image light is emitted.

  As the display unit body 22, various devices such as a liquid crystal display panel and an EL display panel can be used as the display unit 20. In the present embodiment, a plasma display panel (PDP panel) is used as the display unit main body 22. The optical member 30 also functions as a front filter provided on the observer side of the plasma display panel.

  As shown in FIG. 1, the display unit main body 22 as a plasma display panel has two substrates (typically glass substrates) 22a and 22b arranged with a gap therebetween. A large number of discharge cells corresponding to the respective pixels of the plasma display are formed between the two substrates 22a and 22b. Each discharge cell is filled with a rare gas such as helium, neon, argon, or xenon, and the inner wall of each discharge cell is coated with a phosphor. Further, a voltage can be applied to each discharge cell. In the discharge cell to which voltage is applied, discharge occurs and ultraviolet rays are generated. The generated ultraviolet light hits the phosphor in the discharge cell, so that visible light is emitted from the discharge cell. In this way, by controlling the emission of visible light from each discharge cell, a desired image can be displayed by the PDP.

  The antireflection layer 25 is a sheet-like member having a function of preventing reflection, and can be configured using, for example, various commercially available films, for example, Realak 7700S (Nippon Yushi). As shown in FIG. 1, the antireflection layer 25 is stacked on a substrate (hereinafter also referred to as a front plate) 22 a on the optical member 30 side of the pair of substrates 22 a and 22 b of the display unit main body 22. An adhesive layer (not shown) may be provided between the antireflection layer 25 and the front plate 22a, and the antireflection layer 25 may be bonded to the front plate 22a via this adhesive layer. . Further, instead of forming the antireflection layer 25 on the display unit body 22 by lamination, the antireflection layer 25 may be formed on the display unit body 22 by coating. As the coating liquid to be coated, for example, a coating liquid containing a fluorine-based low refractive index resin can be used.

  In the present case, the terms “sheet”, “film”, and “plate” are not distinguished from each other only based on the difference in names. Therefore, for example, a “sheet” is a concept including a member that can also be called a film or a plate. The adhesive layer (adhesive) is a concept including an adhesive layer (adhesive).

  Next, the sheet-like optical member 30 that transmits the image light from the display unit 20 to the viewer side will be described. As described above, the optical member 30 is disposed to face the display unit 20 with a gap from the display unit 20. The gap between the display unit 20 and the optical member 30 according to the present embodiment is preferably greater than 0 mm and less than or equal to 10 mm along the normal direction to the display surface of the display device 10.

  As a result of repeated research by the present inventors, it has been found that when the gap is 0 mm, that is, when the display unit 20 and the optical member 30 are stacked, interference fringes are conspicuous. Further, when the display unit 20 and the optical member 30 are overlapped, the optical member 30 and the display unit 20 are partially separated due to a change in temperature or humidity of an environment where the display device 10 is installed. Become. As a result, not only the interference fringes (moire) are noticeable, but also Newton rings (Newton rings) are visually recognized. For these reasons, it is preferable that the gap between the display unit 20 and the optical member 30 exceeds 0 mm, that is, the gap is reliably formed between the display unit 20 and the optical member 30.

  On the other hand, when the gap exceeds 10 mm, defects such as ghost (double image) and image blur become noticeable. In addition, in a situation where a reduction in the thickness of the display device 10 is strongly demanded, it is very undesirable to increase the thickness of the display device 10. From these things, it is preferable that the clearance gap between the display part 20 and the optical member 30 is 10 mm or less.

  Further, in order to effectively prevent conspicuous fringes (moire), image blur, ghost, and the like, the haze value of the optical member 30 is preferably set to 3 or more, while excellent contrast. It has also been found that the haze value of the optical member 30 is preferably 10 or less in order to ensure the above. In addition, the haze value here means the value obtained based on JIS K-7361-1.

  As shown in FIG. 1, the optical member 30 includes an optical functional layer 50 for improving contrast and a substrate 31. The optical functional layer 50 is formed integrally with the base layer 58 and constitutes one optical sheet 40 together with the base layer 58. The substrate 31 functions as a support for the optical member 30. The substrate 31 is made of a highly rigid material having excellent light transmittance, such as glass.

  As shown in FIG. 1, the optical member 30 further includes a plurality of layers supported by the base material 31 in addition to the optical sheet 40. As described above, in this embodiment, the optical member 30 functions as a front filter of the PDP. Therefore, an electromagnetic wave shielding sheet that shields electromagnetic waves in a specific wavelength band, a near infrared shielding sheet that absorbs near infrared light (for example, light having a wavelength of 800 nm to 1200 nm), neon light that absorbs light emitted from neon atoms and improves color reproducibility. A shielding sheet, a UV light shielding sheet that absorbs UV light (ultraviolet rays), and the like may be provided as appropriate as layers included in the optical member 30. Further, the optical member 30 includes a layer that exerts various optical effects on the image light, for example, an antireflection layer 35 for preventing reflection of illumination or the like, and a color tone correction layer for correcting color tone. As a layer to be provided, it can be provided as appropriate.

  Here, the optical sheet 40 having the optical functional layer 50 that exerts an optical action on the image light and the base layer 58 will be described in more detail.

  First, the optical functional layer 50 will be described. The optical function layer 50 includes a plurality of light transmission portions 52 configured to transmit light and a plurality of light absorption portions 54 configured to absorb light. In the present embodiment, the optical functional layer 50 is disposed adjacent to the base layer 58 on the display unit side of the base layer 58. As shown in FIG. 1, the optical sheet 40 is disposed on the display unit 20 side of the optical member, and the optical sheet 40 forms the surface of the optical member 30 on the display unit side.

  As shown in FIG. 1, the plurality of light transmission parts 52 and the plurality of light absorption parts 54 are alternately arranged along the sheet surface of the optical sheet 40. In the present embodiment, the plurality of light transmission parts 52 are formed in the same shape. The plurality of light absorbing portions 54 are also formed in the same shape. Each light transmission part 52 and each light absorption part 54 are linearly extended on the sheet | seat surface of the optical sheet 40 along the direction orthogonal to the arrangement direction.

  Here, the “sheet surface (layer surface)” refers to a surface coinciding with the planar direction when the target sheet-like member is viewed as a whole and globally. In the present embodiment, the sheet surface of the optical member 30, the sheet surface of the optical sheet 40, the layer surface of each layer, and the display surface of the display device 10 are parallel to each other. 1 to 3 (and FIGS. 4 to 9 to be described later) are all normal to the sheet surface of the optical sheet 40 and the arrangement direction of the light absorbing portion 54 (the arrangement direction of the light transmitting portion 52). , Each component is shown in a cross section (hereinafter, also simply referred to as a main cut surface).

  In the present embodiment, as shown in FIG. 1, the width of the light absorbing portion 54 along the sheet surface of the optical sheet 40 gradually decreases from the light incident side toward the light outgoing side. More specifically, the light absorbing portion 54 has a trapezoidal shape at the main cut surface. In the main cut surface, the bottom of the trapezoidal shape that forms the light absorbing portion 54 is located on the light incident side (display side) along the transmission path of the image light, and the trapezoidal shape that forms the light absorbing portion 54 Is located on the light output side (observer side). On the other hand, the light transmission part 52 is disposed between the two light absorption parts 54 so as to be adjacent to the two light absorption parts 54. Therefore, as shown in FIG. 1, the light transmission part 52 has a trapezoidal shape at the main cut surface. In the main cut surface, the upper base of the cross-sectional trapezoidal shape forming the light transmission part 52 is located on the light incident side, and the lower bottom of the cross-sectional trapezoidal shape forming the light transmission part 52 is located on the light output side.

  And the light absorption part 54 has a light transmittance lower than the light transmission part 52, and has the effect | action which actively absorbs light. That is, in the optical functional layer 50 (optical sheet 40) according to the present embodiment, the light absorbing portion 54 functions as a light absorbing region, while the light transmitting portion 52 is integrally formed with the light transmitting portion 52. Together with the base layer 58, it functions as a light transmitting region.

  The light transmitting portion 52 that transmits light is made of a highly transparent material, ideally a transparent material. As a specific example, the light transmission part 52 can be formed using urethane type ultraviolet curable resin etc. with high light transmittance.

  On the other hand, the light absorption part 54 can be formed from resin colored with a pigment or dye as an example. Moreover, as shown in FIG. 1, the light absorption part 54 may be formed also from resin 54b containing the light absorption particle 54a which has a light absorption function. As the light absorbing particles 54a, black resin particles having a particle size of about several μm to several tens of μm can be used. As the resin 54b in which the light-absorbing particles 54a are dispersed, the same type of material as the material forming the light transmission part 52 can be used. In the drawings other than FIG. 1, illustration of the light absorbing particles 54a and the binder resin 54b is omitted.

  Further, it is not necessary to positively develop an optical action such as refraction at the interface between the light transmission part 52 and the light absorption part 54. Therefore, the difference in refractive index between the light transmitting portion 52 and the light absorbing portion 54 is preferably in the range of 0 to 0.1, more preferably in the range of 0 to 0.01. Most preferably, it is in the range of 0.005 or less. Moreover, it is preferable that the refractive indexes of the light transmission part 52 and the light absorption part 54 are 1.49 or more and 1.56 or less considering the ease of material acquisition, cost, etc.

  Next, the base layer 58 will be described. The base layer 58 functions as a layer that supports the optical function layer 50. Therefore, when the optical functional layer 50 is formed on another layer included in the optical member 30, the base layer 58 can be omitted. The base layer 58 can be suitably formed from PET, MS resin, or the like having excellent translucency. However, it is not necessary to form an optical interface (interface that can exert an optical action) between the base layer 58 and the light transmission part 52 of the optical function layer 50. For this reason, the base layer 58 may be formed of the same material as the material forming the light transmission portion 52.

  Next, an example of a method for manufacturing the optical member 30 will be described. The optical sheet 40 having the optical functional layer 50 and the base layer 58 can be manufactured very easily and inexpensively, for example, as follows. First, the light transmission part 52 is formed on the base layer 58 by molding using, for example, a radiation curable resin (UV curable resin or the like). Next, a material that forms the light absorbing portion 54 is applied on the formed light transmitting portion 52 in a fluid state. Thereafter, wiping is performed so that the space between the adjacent light transmission parts 52 is filled with the material having the fluidity. Next, the optical functional layer 50 can be formed on the base layer 58 by curing the material between the light transmission portions 52. As described above, the optical sheet 40 can be obtained easily and inexpensively. Next, the optical member 30 is obtained by bonding the obtained optical sheet 40, the other plurality of layers 33 and 35, and the substrate 31 using an adhesive layer made of an adhesive as appropriate.

  The above manufacturing method is merely an example, and various modifications can be made. For example, instead of molding using a radiation curable resin (UV curable resin or the like), the base layer 58 and the light transmitting portion 52 having a desired shape may be integrally molded by extrusion molding.

  Next, an operation when displaying an image by the display device 10 having the above configuration will be described.

  The image light emitted from the display unit 20 of the display device 10 enters the optical member 30, passes through the light transmission unit 52 of the optical function layer 50, and is emitted from the optical member 30. As a result, the observer can observe the video.

  Incidentally, there is also light incident on the optical member 30 from the observer side. Such light includes ambient light (external light) such as sunlight and indoor lamp light. This ambient light is reflected by the optical member 30 and the display unit 20, and the traveling direction thereof is directed toward the observer side (the light exit side in the image light transmission path). Thus, the light that has been reversed in the traveling direction and is visually recognized by the observer causes a decrease in the contrast of the image displayed on the display device 10. Furthermore, when there is a large amount of ambient light that is specularly reflected (regularly reflected) in the optical member 30 or the display unit 20 and whose traveling direction is reversed, the contrast decreases and the image quality deteriorates significantly. (External image (for example, illumination) reflection).

  On the other hand, in the present embodiment, as shown in FIG. 2, the ambient light L21 has a display surface in a cross section in which the traveling direction is along the arrangement direction of the light absorbing portions 54 (light transmitting portions 52). When it is greatly inclined from the normal line direction, it enters the light absorbing portion 54 and is absorbed by the light absorbing portion 54. By such an action of the light absorbing portion 54, the amount of light that can be viewed by an observer by reversing the traveling direction can be reduced, and the contrast can be greatly improved.

  By the way, in the optical functional layer 50, the light transmitting portions 52 through which light is transmitted are arranged at a predetermined pitch along the sheet surface of the optical functional layer 50. When such an optical functional layer 50 is used together with the display unit 20 having a large number of pixels arranged at a predetermined pitch, interference fringes (moire) may be conspicuous. In general, it is expected that interference fringes are generated due to the arrangement pitch of the pixels of the display unit 20 and the arrangement pitch of the light transmission parts 52 of the optical function layer 50. As a method for making the interference fringes inconspicuous, it is known to set the ratio between the pixel arrangement pitch and the light transmission portion 52 arrangement pitch within a predetermined range. It is also known that such interference fringes can be made inconspicuous by providing a layer having a strong light diffusion function.

  However, when the present inventors have made extensive studies, interference fringes generated when the optical functional layer 50 is used for the display device 10 are the pixel arrangement pitch of the display unit 20 and the arrangement pitch of the light transmission unit 52. It was not possible to make it inconspicuous simply by adjusting,. Further, if a layer having a strong light diffusion function is provided, interference fringes can be made inconspicuous. However, such a method involves a decrease in overall contrast and image blurring.

  On the other hand, if the surface layer facing the optical member 30 of the display unit 20 is provided with an antireflection function, the image quality is not deteriorated as supported by the evaluation results in Examples described later. The interference fringes can be effectively made inconspicuous. Although the mechanism that makes the interference fringe inconspicuous is not clear, a mechanism that can be considered as one factor will be described below mainly with reference to FIG. However, the present invention is not limited to the following mechanism.

  As described above, part of the ambient light L21 incident on the optical member 30 (optical sheet 40) disposed on the viewer side of the display unit 20 is absorbed by the light absorption unit 54. However, as shown in FIG. 3, at least a part L31 of the environmental light whose inclination angle with respect to the normal of the sheet surface of the optical member 30 (optical sheet 40) is not large is transmitted through the light transmission part 52 to the display part 20. Proceed with Most of such light is reflected by the display unit 20, its traveling direction is reversed, and again proceeds to the viewer side. In particular, when the display unit 20 includes a plasma display panel, since the plasma display panel has a phosphor for emitting visible light, the ambient light L31 incident on the display unit 20 from the observer side is generated. Reflected toward the viewer side with high reflectivity. As shown in FIG. 3, the light L <b> 32 that is reflected and travels toward the optical function layer 50 again has periodic strength along the arrangement direction of the light transmission portions 52, and the pitch of the strength is light transmission portions 52. The pitch generally corresponds to the array pitch.

  Due to the period of the periodic light L32 and the arrangement pitch of the light transmission parts 52, interference fringes (hereinafter, the interference fringes caused by the pixel pitch of the display part 20 and the arrangement pitch of the light transmission parts 52 are distinguished. Therefore, it is expected that “self-moire” will occur. Since the period of the periodic light L32 depends on the arrangement pitch of the light transmission parts 52, it is estimated that it is not effective to make the self-moire inconspicuous by adjusting the arrangement pitch of the light transmission parts 52. The

  On the other hand, according to the present embodiment, the surface layer facing the optical member 30 of the display unit 20 is formed by the antireflection layer 25 having an antireflection function. Therefore, as shown in FIG. 3, the light L <b> 31 that passes through the optical function layer 50 and reaches the display unit 20 is less likely to be reflected on the surface layer 25 of the display unit 20, or in the surface layer 25 of the display unit 20. Does not reflect. As a result, it is estimated that the amount of the light L32 that is reflected by the display unit 20 and re-enters the optical function layer 50 decreases, or that the light L32 that re-enters the optical function layer 50 hardly exists. Accordingly, it is considered that the self-moire is not conspicuous, and the self-moire itself can be prevented from occurring. Since the antireflection layer 25 is a layer for preventing reflection, the progression of the image light emitted from the display unit main body 22 toward the viewer side is not significantly affected by the antireflection layer 25. . Therefore, according to such an antireflection layer 25, self-moire (interference fringes) can be made inconspicuous without greatly degrading the image quality.

  According to the first embodiment as described above, interference fringes (moire) can be made inconspicuous without greatly degrading the image quality.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a view corresponding to FIG. 1 for explaining a second embodiment of the optical member and the display device according to the present invention. FIG. 5 is a diagram corresponding to FIG. 3 for explaining a second embodiment of the optical member and the display device.

  The second embodiment differs from the first embodiment described above in that the surface layer facing the optical member 30 of the display unit 20 is provided with a light diffusion function instead of an antireflection function. Others (for example, the display unit main body 22 and the optical member 30) can be configured identically. For this reason, in FIG. 4 and FIG. 5, the same code | symbol is attached | subjected to the part which can be comprised the same as 1st Embodiment, and the description which overlaps with 1st Embodiment is abbreviate | omitted below.

  As described above, in the second embodiment, a light diffusing function for diffusing light is given to the surface layer facing the optical member 30 of the display unit 20. In the example illustrated in FIG. 4, the display unit 20 includes a display unit main body 22 that emits image light, and a light diffusion layer 26 stacked on the display unit main body 22. The light diffusing layer 26 is a layer having a light diffusing function, and forms a surface on the optical member side of the display unit 20, in other words, a light emitting surface on which video light is emitted.

  The light diffusing layer 26 is a sheet-like member having a function of diffusing light, and as an example, various films that are commercially available with names such as “antireflection film” and “antiglare film” are used. Can be configured. As shown in FIG. 4, the light diffusion layer 26 is stacked on the substrate 22 a on the optical member 30 side of the pair of substrates 22 a and 22 b of the display unit body 22. The light diffusion function of the light diffusion layer 26 may be expressed by forming an uneven surface, or may be expressed by containing light diffusion particles (light diffusion agent), Further, it may be expressed by forming an uneven surface and containing light diffusing particles.

  An adhesive layer (not shown) may be provided between the light diffusion layer 26 and the front plate 22a, and the light diffusion layer 26 may be bonded to the front plate 22a via the adhesive layer. .

  Further, instead of forming the light diffusion layer 26 on the display unit body 22 by lamination, the light diffusion layer 26 may be formed on the display unit body 22 by coating. As a coating liquid to be coated, for example, a resin composition containing a filler (acrylic beads or the like) can be used.

  Next, the operation when displaying an image on the display device 10, mainly the operation of the light diffusion layer 26, will be described.

  Similar to the first embodiment, the image light transmitted through the light transmitting portion 52 of the optical functional layer 50 can be observed from the observer side. At this time, as shown in FIG. 2, part of the environmental light L21 incident on the optical member 30 is absorbed by the light absorbing portion 54 of the optical functional layer 50, so that an image can be observed with high contrast.

  As shown in FIG. 5, part of the environmental light L <b> 31 that has not been absorbed by the light absorption unit 54 passes through the optical function layer 50 and proceeds toward the display unit 20. As described above, such light can be reflected by the display unit 20 and cause self-moire (see L32 in FIG. 5).

  However, in the present embodiment, the light diffusing layer 26 having a function of diffusing light is provided on the surface layer of the display unit 20 considered to be most easily reflected by the light L31 directed to the display unit 20. Therefore, as shown in FIG. 5, the reflected light L41 from the surface layer 26 of the display unit 20 is diffused. For this reason, the periodicity of light re-entering the optical functional layer 50 is weakened. That is, according to the light diffusing layer 26, it is considered that the self-moire is not conspicuous but the self-moire itself can be prevented from occurring. In order to expect this effect, the surface layer 26 has an uneven surface that forms the most light emitting side surface (the surface closest to the optical member) of the display unit 20, and the light diffusion function of the surface layer 26 is expressed by the uneven surface. It is preferable to be adapted. In this case, it is possible to effectively prevent regular reflection (specular reflection) on the most light emitting side surface on the display unit 20 and to make the self-moire inconspicuous.

  Further, a part of the light L31 directed from the optical function layer 50 to the display unit 20 is reflected after traveling to the inside of the display unit 20 (for example, a PDP phosphor) instead of the surface layer 26 of the display unit 20. There is also light that can reverse its traveling direction toward the viewer. Such light is diffused when entering the surface layer 26 of the display unit 20 and traveling into the display unit 20. Further, after being reflected inside the display unit 20, it is diffused again when it is emitted from the surface layer 26 of the display unit 20 to the viewer side. That is, by diffusing twice in the light diffusing layer 26, the periodicity of light can be effectively weakened, thereby making it possible to prevent the occurrence of self-moire caused by such light. Conceivable.

  Note that the image light from the display unit main body 22 is diffused only once by the light diffusion layer 26 when emitted from the surface layer 26 of the display unit 20 to the viewer side. However, the light diffusion layer 26 is disposed close to the display unit body 22 without leaving a gap from the display unit body 22. As a result of repeated research by the present inventors, according to such a light diffusion layer 26, it was possible to effectively suppress the diffusion of the image light so as to blur the image. In the present embodiment, the light diffusion layer 26 is provided at a position closest to the display unit main body 22. Therefore, self-moire can be made inconspicuous while effectively preventing the occurrence of image blur, ghost, and the like.

  According to the second embodiment as described above, interference fringes (moire) can be made inconspicuous without greatly degrading the image quality.

[Modification]
Various modifications can be made to the first embodiment or the second embodiment described above. Hereinafter, an example of modification will be described with reference to FIGS. 6 to 9 as appropriate. 6 to 9, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  For example, in the above-described embodiment, the example in which the light absorbing portion 54 of the optical function layer 50 has a trapezoidal cross section is shown, but the present invention is not limited thereto. As an example, in the cross section along the arrangement direction of the light absorbing portions 54, the side portion 54c having a trapezoidal cross section may be configured as a polygonal line as shown in FIG. 6, or a curved line as shown in FIG. It may be configured as. Further, the cross-sectional shape of the light absorbing portion 54 is not limited to a trapezoidal shape, and may be another rectangular shape, for example, a rectangular shape as shown in FIG. Furthermore, the cross-sectional shape of the light absorbing portion 54 is not limited to a quadrangular shape, and may be, for example, a pentagonal shape as shown in FIG. 9 or another polygonal shape.

  In the above-described embodiment, the light absorbing portions 54 of the optical function layer 50 are arranged side by side along one direction, and each light absorbing portion 54 extends along the other direction intersecting the one direction. An example is shown, but the present invention is not limited to this. The light absorption parts 54 may be arranged side by side along two directions intersecting each other.

  Furthermore, in 1st Embodiment mentioned above, although the antireflection layer 25 was laminated | stacked on the display part main body 22, the example which provides an antireflection function to the surface layer by the side of the optical member of the display part 20 was shown, It is not limited to this. For example, an antireflection function may be imparted to the surface layer on the optical member side of the display unit 20 by performing an antireflection treatment on the surface (front plate 22a) of the display unit body 22 on the optical member side. .

  Furthermore, in the second embodiment described above, an example in which a light diffusion function is provided to the surface layer on the optical member side of the display unit 20 by stacking the light diffusion layer 26 on the display unit main body 22 has been shown. It is not limited to this. For example, the optical member side of the display unit 20 is obtained by performing light diffusion processing (for example, roughening processing such as hairline processing or blast processing) on the surface (front plate 22a) of the display unit main body 22 on the optical member side. A light diffusion function may be imparted to the surface layer.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to this Example.

  Each plasma television according to the example and the comparative example was manufactured from a display portion including a plasma display panel (PDP) taken out from a commercially available television as a display portion main body and an optical member arranged to face the display portion. All plasma TVs share the same PDP. The other configurations of each plasma television are described below.

  About each obtained plasma television, the presence or absence of interference fringes, contrast, and the presence or absence of image blur were evaluated.

<Sample>
Example 1
The display part was produced by bonding a commercially available antireflection layer to the surface of the display part main body (PDP) on the optical member side via an adhesive.
The optical member was an optical member laminated in the order of the base layer and the optical functional layer from the observer side. The optical functional layer was integrally formed with the base layer. That is, the optical member was configured the same as the optical sheet in FIG. 1 described above.
The gap between the display unit and the optical member was 2 mm.

(Example 2)
The display part was produced by bonding a commercially available light-diffusion layer through the adhesive to the surface at the side of the optical member of a display part main body (PDP). As the light diffusing layer, a film having a concavo-convex surface, which was configured so that light diffusibility was expressed by the concavo-convex surface was used. In addition, this film was comprised from the single material, and was a film which does not contain the light-diffusion agent. The optical member of Example 2 was the same as the optical member of Example 1. The gap between the display unit and the optical member was 2 mm.

(Example 3)
The display part was produced by bonding a commercially available light-diffusion layer through the adhesive to the surface at the side of the optical member of a display part main body (PDP). As the light diffusing layer, a film containing a light diffusing agent and configured so that light diffusibility is expressed by the light diffusing agent was used. In addition, this film was a film which has the flat surface in which the unevenness | corrugation is not formed. The degree of diffusion of the light diffusion layer of Example 3 was set substantially the same as the degree of diffusion of the light diffusion layer of Example 2. The optical member of Example 3 was the same as the optical member of Example 1. The gap between the display unit and the optical member was 2 mm.

(Comparative Example 1)
The display part was comprised only from the display part main body (PDP). In other words, the display unit has neither an antireflection layer nor a light diffusion layer. The optical member of Comparative Example 1 was the same as the optical member of Example 1. The gap between the display unit and the optical member was 2 mm.

(Comparative Example 2)
The display unit of Comparative Example 2 was the same display unit as Comparative Example 1. The optical member of Comparative Example 2 was the same as the optical member of Example 1. However, the gap between the display unit and the optical member was larger than 10 mm.

(Comparative Example 3)
The display unit of Comparative Example 3 was the same display unit as Comparative Example 1. The optical member of Comparative Example 3 was the same as the optical member of Example 1. However, the display unit and the optical member were arranged so as to be in contact with each other. That is, the gap between the display unit and the optical member was 0 mm.

(Comparative Example 4)
The display unit of Comparative Example 4 was the same display unit as Comparative Example 1. The optical member of Comparative Example 4 was produced by bonding a commercially available light diffusion layer to the surface on the viewer side of the optical member of Example 1 via an adhesive. The light diffusion layer had the same configuration as the light diffusion layer used in Example 3. The diffusion degree of the light diffusion layer used in Comparative Example 4 was substantially the same as the diffusion degree of the light diffusion layer used in Example 3. The gap between the display unit and the optical member was 2 mm.

<Evaluation of interference fringes>
External light was projected at various projection angles on each plasma television not displaying an image, and it was confirmed whether or not interference fringes were visually recognized. The evaluation results for each plasma television are shown in the “moire” column of FIG. In FIG. 10, “x” is displayed for a sample in which interference fringes are conspicuous when external light is projected at any projection angle, and for samples in which interference fringes are not conspicuous even when external light is projected at any projection angle. Is displayed.

<Evaluation of contrast and image blur>
Based on the image displayed on each plasma television under illumination light, the uniformity of contrast and brightness was confirmed.

  The contrast evaluation results for each plasma television are shown in the “Contrast” column of FIG. In FIG. 10, “x” is displayed for a sample that is felt that the contrast is low, and “◯” is displayed for a sample in which the decrease in contrast is not noticed visually.

  Also, the evaluation result of image blur for each plasma television is shown in the column of “image blur” in FIG. In FIG. 10, “x” is displayed for a sample in which image blur is felt, and “◯” is displayed for a sample in which the presence of image blur was not noticed visually. In the video displayed on the plasma television according to Comparative Example 2, not only image blur but also ghost (double image) was confirmed. The length of the gap between the PDP and the optical member was appropriately changed within a range of a value larger than 10 mm (about 10 to 20 mm). However, as the gap between the PDP and the optical member becomes larger, the image quality is improved. Deterioration has progressed.

  Furthermore, Newton rings were visually recognized on the display surface of the plasma television according to Comparative Example 3.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a cross-sectional view schematically showing a configuration of a display device. FIG. 2 is a cross-sectional view for explaining the operation of the optical member incorporated in the display device of FIG. FIG. 3 is a cross-sectional view for explaining the operation of the display device of FIG. FIG. 4 is a cross-sectional view corresponding to FIG. 1 and schematically showing a configuration of a display device according to another embodiment of the present invention. FIG. 5 is a cross-sectional view corresponding to FIG. 3 for explaining the operation of the display device in another embodiment of the present invention. FIG. 6 is a cross-sectional view showing a modification of the optical functional layer of the optical member. FIG. 7 is a cross-sectional view showing another modification of the optical function layer of the optical member. FIG. 8 is a cross-sectional view showing still another modified example of the optical functional layer of the optical member. FIG. 9 is a cross-sectional view showing still another modified example of the optical function layer of the optical member. FIG. 10 is a table showing the configuration of each sample and the evaluation results.

Explanation of symbols

10 Display Device 20 Display Unit 25 Antireflection Layer (Surface Layer)
26 Light diffusion layer (surface layer)
30 Optical member 40 Optical sheet 50 Optical functional layer 52 Light transmission part 54 Light absorption part 54a Light absorption particle 54b Binder resin 58 Base layer

Claims (10)

A display unit;
A sheet-like optical member that is disposed on the viewer side of the display unit with a gap from the display unit, and transmits image light from the display unit to the viewer side,
The optical member includes a plurality of light transmitting portions formed so as to be able to transmit light, and a plurality of lights formed so as to be capable of absorbing light and arranged alternately with the light transmitting portions along a sheet surface of the optical member. An optical functional layer having an absorption part,
An antireflection function is imparted to the surface layer of the display unit that faces the optical member. The display unit includes: a display unit main body that emits image light; and an antireflection layer that is laminated on the display unit main body and forms a surface of the display unit on the optical member side. The display device described in 1. The display unit has a display unit body that emits image light,
The display device according to claim 1, wherein the antireflection function is provided by performing processing on a surface of the display unit main body on the optical member side. A display unit;
A sheet-like optical member that is disposed on the viewer side of the display unit with a gap from the display unit, and transmits image light from the display unit to the viewer side,
The optical member includes a plurality of light transmitting portions formed so as to be able to transmit light, and a plurality of lights formed so as to be capable of absorbing light and arranged alternately with the light transmitting portions along a sheet surface of the optical member. An optical functional layer having an absorption part,
A display device characterized in that a light diffusing function is imparted to a surface layer facing the optical member of the display section. 5. The display unit, comprising: a display unit main body that emits image light; and a light diffusion layer that is laminated on the display unit main body and forms a surface of the display unit on the optical member side. The display device described in 1. The display unit has a display unit body that emits image light,
The display device according to claim 4, wherein the light diffusion function is provided by performing a process on a surface of the display unit main body on the optical member side. The display device according to claim 5, wherein the display unit has an uneven surface that forms a surface of the display unit on the optical member side. The display device according to claim 1, wherein a haze value of the optical member is 3 or more and 10 or less. The display device according to claim 1, wherein the display unit includes a plasma display panel. The display device according to claim 1, wherein a gap between the optical member and the display unit is greater than 0 mm and equal to or less than 10 mm.

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