JP2010008895A - Optical member and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member making moire (interference fringe) inconspicuous without significantly degrading image quality. <P>SOLUTION: The optical member 30 is a sheet-like member which is disposed on an observer side of a display section 20 and apart a space from the display section and transmits video light from the display section to the observer side. The optical member includes: an optical function layer 50 having a plurality of light transmission sections 52 formed so as to transmit light, and a plurality of light absorption sections 54 formed so as to absorb light and disposed to line up alternately with the light transmission sections along the sheet plane of the optical member; and an optical control layer having a rugged surface forming the display section-side surface of the optical member. <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, the image quality deteriorates due to a decrease in the contrast of the image.

  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.

  An optical member according to the present invention is 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. An optical device having a plurality of light transmission portions formed so as to be transmissive and a plurality of light absorption portions formed so as to be capable of absorbing light and arranged alternately with the light transmission portions along the sheet surface of the optical member. A functional layer; and a light control layer having an uneven surface forming a surface of the optical member on the display unit side.

  In the optical member according to the present invention, the optical functional layer may be disposed on the viewer side of the light control layer so as to be adjacent to the light control layer. In such an optical member according to the present invention, the light control layer may be a layer made of a resin molded on the surface of the optical function layer on the display unit side. In the optical member according to the present invention, the light control layer may be made of the same type of resin as the resin that forms the light transmitting portion of the optical function layer.

  In the optical member according to the present invention, the light control layer may be a light diffusion layer made of a single material.

  In the optical member according to the present invention, the haze value of the optical member is preferably 3 or more and 10 or less.

  A display device according to the present invention includes any one of the optical members described above, and a display unit disposed to face the optical member.

  In the display device according to the present invention, the display unit may be configured as a plasma display panel.

  Moreover, the display apparatus by this invention WHEREIN: It is preferable that the clearance gap between the said optical member and the said display part is more than 0 mm and 10 mm or less.

  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, an 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.

  1 to 4 are diagrams for explaining an 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, and FIGS. 2 to 4 are diagrams for explaining the operation of the optical member and the display device.

  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. The display unit 20 is a device that emits video light that forms a predetermined image toward an observer.

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

  The plasma display panel has two glass substrates 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 glass substrates. 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.

  Next, the sheet-like optical member 30 that transmits the image light from the display unit 20 to the viewer side will be described. 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.

  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 a light control layer 45 having a concavo-convex surface 45 a, an optical functional layer 50 for improving contrast, and a substrate 31. The light control layer 45 is formed on the optical function layer 50, and the optical function layer 50 is configured integrally with the base layer 58. The base layer 58, the optical function layer 50, and the light control layer 45 constitute a single optical sheet 40.

  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 light control layer 45 and the optical function layer 50 that exert various optical actions on the image light 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 on the viewer side of the light control layer 45 so as to be adjacent to the light control layer 45.

  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 4 (and FIGS. 5 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 portions 54 (the arrangement direction of the light transmitting portions 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 resin as the resin 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, the light control layer 45 will be described. As described above, the light control layer 45 has the uneven surface 45a. As shown in FIG. 1, the uneven surface 45 a of the light control layer 45 forms the surface of the optical member 30 on the display unit side (the incident light incident side of the optical member with respect to the image light). That is, the light control layer 45 constitutes the surface of the optical member 30 closest to the display unit. The light control layer 45 is formed on the light incident side of the optical function layer 50 (light incident side in the transmission direction of the image light). In other words, the optical function layer 50 described above is disposed on the viewer side of the light control layer 45 so as to be adjacent to the light control layer 45 in the present embodiment.

As shown in FIG. 1, the uneven surface 45a of the light control layer 45 is formed by recesses and protrusions arranged side by side along at least the arrangement direction of the light transmission parts 52 (the arrangement direction of the light absorption parts 54). Yes. In the present embodiment, each concave portion and each convex portion extend linearly on the layer surface of the light control layer 45 along a direction orthogonal to the arrangement direction. Therefore, the uneven surface (surface on the display unit side) 45a in the present embodiment has a function of diffusing light in a plane along the arrangement direction of the light transmission parts 52 (the arrangement direction of the light absorption parts 54). ing. In this embodiment,
The irregularities forming the irregular surface 45a may be irregular irregularities, or regular irregularities in arrangement pitch, shape, and the like. However, when the arrangement pitch of the irregularities forming the irregular surface 45a is made regular, interference fringes are not generated in consideration of the arrangement pitch of the light transmission parts 52 of the optical functional layer 50, the pixel pitch of the display part 20, and the like. The arrangement pitch should be set as follows. As a specific example, it is effective to make the arrangement pitch of the unevenness sufficiently smaller than the arrangement pitch of the light transmission parts 52 and sufficiently larger than the pixel pitch of the display part 20.

  The light control layer 45 is preferably a light diffusion layer made of a single material. This is because light diffusion by a light diffusing agent (light diffusing particles) may cause in-plane variation in luminance. In particular, when the layer containing the light diffusing particles is arranged away from the display device 20 via a gap, the in-plane luminance non-uniformity tends to be remarkable. The light diffusing layer made of a single material means a layer that does not contain fine particles that may affect the light diffusibility of a light diffusing agent or the like. Therefore, a layer containing an additive such as a near-infrared absorber that cannot positively affect the light diffusibility of the light control layer 45 is handled as a light diffusing layer made of a single material.

  The light control layer 45 can be suitably formed from a resin having excellent translucency. However, it is not necessary to form an optical interface (interface that can exert an optical action) between the light control layer 45 and the light transmission portion 52 of the optical function layer 50. For this reason, the light control layer 45 may be formed of the same material as the material forming the light transmission portion 52 of the optical function layer 50. In this case, in particular, when the material forming the light transmitting portion 52 and the material forming the base layer 58 of the optical functional layer 50 and the material forming the light control layer 45 are made of the same type of resin, the optical sheet 40 as a whole The linear expansion coefficient becomes substantially constant, so that deformation (for example, warping or bending) of the optical sheet 40 accompanying changes in environmental conditions (for example, temperature or humidity) can be effectively suppressed.

  Next, an example of a method for manufacturing the optical member 30 will be described.

  The optical sheet 40 having the light control layer 45, 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. Thereafter, the light control layer 45 is formed on the optical function layer 50 by molding using a mold. 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. Here, the adhesive (adhesive layer) is a concept including an adhesive (adhesive layer).

  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.

  Further, in the present embodiment, the display unit side of the optical member 30 (the light incident side in the image light transmission path) is formed as an uneven surface 45a having a light diffusion function. Therefore, as shown in FIG. 2, the light L22 that reaches the uneven surface 45a and is reflected by the uneven surface 45a is scattered and reflected. That is, the specular reflection of ambient light can be suppressed and the contrast can be effectively improved.

  In addition, in the present embodiment, the light control layer 45 is disposed adjacent to the optical function layer 50. For this reason, the light L22a scattered and reflected by the uneven surface 45a can be effectively captured by the light absorbing portion 54 of the optical functional layer 50. Thereby, contrast can be improved more effectively.

  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.

  On the other hand, the light control layer 45 having a light diffusion function is provided on the display unit 20 side of the optical function layer 50, and the light diffusion function of the light control layer 45 is expressed by the uneven surface 45a facing the display unit 20. If so, the interference fringes can be effectively made inconspicuous as supported by the evaluation results in the examples described later. 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 FIGS. However, the present invention is not limited to the following mechanism.

  As described above, part of the environmental light L21, 22a 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 further control the light. It passes through the uneven surface 45 a of the layer 45 and proceeds to the display unit 20. 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, when a layer having a light diffusing function is provided, it is presumed that self-moire can be made inconspicuous although there is a possibility that the contrast may be lowered.

  On the other hand, in the optical member 30 (optical sheet 40) in the present embodiment described above, the light control layer 45 is disposed between the optical function layer 50 and the display unit 20. The light control layer 45 has a light diffusion function. Therefore, as shown in FIG. 3, the light L31 transmitted through the optical functional layer 50 and incident on the light control layer 45 is diffused as indicated by a dotted line (light L31a). Further, the light L32 reflected by the display unit 20 and incident again on the light control layer 45 of the optical member 30 is further diffused (light L32a) as indicated by a dotted line. For this reason, the light causing the self moire is diffused twice by the light control layer 45, and as a result, the periodicity of the light L32 re-entering the optical function layer 50 is assumed to be weak. Is done. That is, by diffusing twice by the optical functional layer 50, it is considered possible to weaken the periodicity of light and prevent the occurrence of interference fringes (self-moire) itself.

  Note that the image light emitted from the display unit 20 is diffused when passing through the light control layer 45, but is not diffused twice like the ambient light. Therefore, the ambient light L31 and L32 that cause self-moire can be effectively diffused by the light control layer 45 while preventing the image light from being diffused excessively. That is, according to the present embodiment, self-moire (interference fringes) can be made inconspicuous without greatly degrading the image quality.

  In the present embodiment, the light control layer 45 is disposed closer to the display unit 20 than the optical function layer 50 capable of absorbing ambient light that causes self-moire. On the other hand, even if the light control layer 45 is disposed closer to the viewer than the optical function layer 50, ambient light that can cause self-moire is transmitted twice through the light control layer 54 and diffused twice. Will come to be. However, in this case, the second diffusion in the light control layer 45 only acts to make the generated interference fringes (self moire) inconspicuous, and does not cause the interference fringes (self moire) to occur. Does not work. For this reason, according to the present embodiment in which the light control layer 45 is disposed on the display unit 20 side with respect to the optical function layer 50 as supported in the examples described later, self-moire is effective. Can be made inconspicuous.

  Further, according to the present embodiment, the light diffusing function of the light control layer 45 is expressed by the uneven surface 45a that forms the surface of the optical member 30 on the display unit side. As shown in FIG. 4, according to such an uneven surface 45a, the environmental light L41 traveling toward the display unit 20 in the optical member 30 is reflected by the uneven surface 45a, and the traveling direction of the environmental light L41 is changed. It becomes easy to be reversed. Further, as already described with reference to FIG. 3, since the light control layer 45 is disposed adjacent to the optical function layer 50, the light L41 whose traveling direction is changed by the uneven surface 45a is the optical function layer. 50 light absorbing portions 54 are easily absorbed. By such a reflective action on the concavo-convex surface 45a, the amount of light that causes self-moire is reduced, and self-moire can be effectively reduced.

  By the way, the reflection of the ambient light L41 on the uneven surface 45a is mainly caused by the refractive index of the light control layer 45 and the refractive index (= 1) of the gap between the optical member 30 and the display unit 20. This is caused by total reflection due to the difference in refractive index. On the other hand, the image light from the display unit 20 travels toward the light control layer 45 having a high refractive index from a gap having a low refractive index. Therefore, it is not promoted that the image light traveling toward the viewer is reflected by the uneven surface 45a and the traveling direction of the image light is reversed to the display unit 20 side.

  Further, the light control layer 45 is a light diffusing layer made of a single material, and the light diffusing function of the light control layer 45 is expressed by an uneven surface 45 a forming the surface of the optical member 30 on the display unit side. Therefore, there is no in-plane variation in luminance due to light diffusion. Thereby, in-plane uniformity of luminance can be secured.

According to the present embodiment as described above, interference fringes (moire) can be made inconspicuous without greatly degrading image quality. Various modifications can be made to the above-described embodiment. is there. Hereinafter, an example of modification will be described with reference to FIGS. 5 to 9 as appropriate. 5 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. 5 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 a pentagonal shape as shown in FIG. 8, for example, or may be another polygonal shape.

  Moreover, the manufacturing method of the optical member 30 and the manufacturing method of the optical sheet 40 which were demonstrated in embodiment mentioned above are only illustrations, Comprising: It can change suitably. As an example, an example in which the light control layer 45 is formed on the optical function layer 50 by molding has been shown, but the present invention is not limited thereto. For example, as shown in FIG. 9, a light control layer 45 having a concavo-convex surface 45 a may be prepared, and the light control layer 45 may be bonded to the optical function layer 50 by an adhesive layer 56.

  Furthermore, in the above-described embodiment, the example in which the light control layer 45 is provided adjacent to the optical function layer 50 has been described. However, the present invention is not limited to this, and the light control layer 45 is provided between the light control layer 45 and the optical function layer 50. A layer having another function may be provided.

  Furthermore, 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.

  Similarly, in the above-described embodiment, the concave portions and the convex portions forming the concave and convex surface 45a of the light control layer 45 are arranged along one direction, and the concave portions and the convex portions are arranged in other directions intersecting the one direction. Although the example extended along was shown, it is not restricted to this. Each concave part and each convex part may be arranged side by side along two directions intersecting each other.

  Further, in the above-described embodiment, the example in which the uneven surface 45a of the light control layer 45 is formed by molding is shown, but the present invention is not limited to this. For example, the light control layer 45 having an anisotropic light diffusion function may be formed by hairline processing. Further, the uneven surface 45a of the light control layer 45 may be formed on the surface of the optical function layer 50 on the display unit 20 side by performing a hairline process. In this example, the optical function layer 50 and the light control layer 45 are formed as the same layer.

  Furthermore, in the above-described embodiment, the example in which the light control layer 45 is configured as a light diffusion layer made of a single material has been described, but the present invention is not limited thereto. For example, the light diffusion particles may be dispersed in the light control layer 45 to the extent that the image quality is not adversely affected.

  In addition, although the some modification with respect to embodiment mentioned above was demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

  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 plasma display panel (PDP) taken out from a commercially available television and an optical member arranged to face the PDP. All plasma TVs share the same PDP. The optical members of each plasma television are described below.

  About each obtained plasma television, the presence or absence of an interference fringe, the contrast, and the uniformity of a brightness | luminance were evaluated.

<Sample>
Example 1
The optical member of Example 1 was an optical member laminated in the order of the base layer, the optical function layer, and the light control layer from the observer side. That is, the optical member of Example 1 was configured the same as the optical sheet (light control layer / optical function layer / base layer) in FIG. 1 described above. The optical function layer was integrally formed with the base layer. The light control layer was a light diffusion layer made of a single material formed on the optical functional layer by molding. The gap between the PDP and the optical member was 2 mm.
In addition, the laminated body of the optical function layer and the base layer was the same as the following examples and comparative examples.

(Example 2)
The optical member of Example 2 was an optical member (see FIG. 9) laminated in the order of the base layer, the optical functional layer, the adhesive layer, and the light control layer from the observer side. The degree of diffusion of the light control layer was made substantially the same as in Example 1. This light control layer was bonded to the optical functional layer by an adhesive layer. The gap between the PDP and the optical member was 2 mm.

(Comparative Example 1)
The optical member of Comparative Example 1 was an optical member laminated from the observer side in the order of the base layer and the optical functional layer. That is, the plasma television (optical member) of Comparative Example 1 was configured by omitting the light control layer from the plasma television (optical member) of Example 1. The gap between the PDP and the optical member was 2 mm.

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

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

(Comparative Example 4)
The optical member of Comparative Example 4 was an optical member laminated from the observer side in the order of the light diffusion layer, the base layer, and the optical functional layer. The light diffusion layer was formed by curing a resin containing light diffusion particles on the surface of the optical function layer on the viewer side. Therefore, the light diffusion layer was a layer having no uneven surface. The diffusion degree of the light diffusion layer was made substantially the same as the diffusion degree of the light control layer of Example 1. The gap between the PDP and the optical member was 2 mm.

(Comparative Example 5)
The optical member of Comparative Example 5 was an optical member laminated in the order of the base layer, the optical function layer, and the light diffusion layer from the observer side. The light diffusion layer was formed by curing a resin containing light diffusion particles on the surface of the optical functional layer on the display unit side. The light diffusing layer was configured in the same manner as the light diffusing layer included in the optical member of Comparative Example 4 except for which surface of the optical functional layer was formed. The gap between the PDP 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 uniformity of brightness>
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.

  In addition, the evaluation results of the luminance uniformity for each plasma television are shown in the “uniformity” column of FIG. In FIG. 10, “x” is indicated for a sample in which a bright spot is conspicuous in the display surface, and “◯” is indicated for a sample in which the presence of the bright spot in the display surface is not noticed.

  Note that the image displayed on the plasma television according to Comparative Example 2 was blurred. A ghost (double image) was also 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.

  Further, 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 for explaining the operation of the optical member incorporated in the display device of FIG. FIG. 5 is a cross-sectional view showing a modification of the optical functional layer of the optical member. FIG. 6 is a cross-sectional view showing another modification of the optical function layer of the optical member. FIG. 7 is a cross-sectional view showing still another modification of the optical functional 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 a modification of the optical member. FIG. 10 is a table showing the configuration of each sample and the evaluation results.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Display apparatus 20 Display part 30 Optical member 40 Optical sheet 45 Light control layer 45a Uneven surface 50 Optical functional layer 52 Light transmission part 54 Light absorption part 54a Light absorption particle 54b Binder resin 58 Base layer

Claims (9)

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,
A plurality of light transmission portions formed so as to be able to transmit light, and a plurality of light absorption portions formed so as to be capable of absorbing light and arranged alternately with the light transmission portions along the sheet surface of the optical member, An optical functional layer having,
An optical member comprising: a light control layer having an uneven surface that forms a surface of the optical member on the display unit side. The optical member according to claim 1, wherein the optical functional layer is disposed on the viewer side of the light control layer so as to be adjacent to the light control layer. The optical member according to claim 2, wherein the light control layer is a layer made of a resin molded on the surface of the optical function layer on the display unit side. 4. The optical member according to claim 3, wherein the light control layer is made of the same type of resin as the resin that forms the light transmission portion of the optical function layer. The optical member according to any one of claims 1 to 4, wherein the light control layer is a light diffusion layer made of a single material. 6. The optical member according to claim 1, wherein the optical member has a haze value of 3 or more and 10 or less. The optical member according to any one of claims 1 to 6,
A display unit disposed opposite to the optical member. The display device according to claim 7, wherein the display unit is configured as a plasma display panel. The display device according to claim 7 or 8, 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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