JP2016151764A - Light transmission plate having protrusions - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light transmission plate having high luminance and high luminance uniformity.SOLUTION: A light transmission plate 1 includes a main body part 10 having a first surface 101, and a protrusions 20 formed on the first surface so as to protrude from the first surface 101. The protrusion 20 includes a top surface 201 having an irregular shape, and a sloped surface which connects the first surface 101 and the top surface of the protrusion 20. A height Hp from the top surface 201 of the protrusion 20 having the irregular shape to the first surface 101 is 5 - 40 μm. The maximum width Wm of the top surface is 0.15 - 8 mm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light transmissive plate, and more particularly to a light transmissive plate provided with protrusions that can be used as a diffusion plate.

  The diffusion plate is an optical plate used for electrical appliances such as a display, and diffuses light from the light source to make the luminance of the display screen uniform. In order to satisfy various requirements for images displayed on the appliances, diffusion plates having various light transmittances are manufactured by manufacturers. For example, an edge light type backlight module used for a display (for example, an LCD) includes a light guide plate made of a light-transmitting material and a light source (for example, a cold light) disposed on the side of the light guide plate. A linear light source comprising a cathode fluorescent tube (CCFL), a light guide plate and a reflective film disposed under the linear light source, and a light diffuser disposed on the light guide plate to form a light exit surface (Film or plate) and / or lens film.

  In recent years, in order to improve the brightness of color liquid crystal displays and reduce power consumption, the light from the light guide plate is condensed on the diffuser plate or between the diffuser plate and the light guide plate. In some cases, one or two prism sheets for increasing the brightness of the screen are arranged. In addition, as a technique for improving luminance non-uniformity caused by a difference in distance from a light source, a technique for printing a dot pattern whose area continuously increases as the distance from the light source becomes longer is known. Yes. For example, Patent Document 1 discloses a light emitting unit including a light guide plate having a reflection pattern (such as a dot pattern) that scatters and reflects light incident on the light guide plate. The diffusion plate on the light guide plate diffuses light so that the dot pattern on the light guide plate is not visible. The prism sheet can be manufactured by laminating a decorated layer on a plate made of a thermoplastic resin, or by treating the radiation curable resin with a prism mold.

US Published Patent Application 2012/0002138

  However, since the manufacturing cost of these prism sheets is very expensive, the backlight module is also expensive. Furthermore, the selection range of the raw material for manufacturing a known prism sheet is limited to the manufacturing method. Moreover, since it is necessary to combine the prism sheet which does not have a light-diffusion function with a light-diffusion body (film or board), there also exists a problem that an assembly process becomes complicated. In addition to the diffusion film, prism sheet, and luminance enhancement film used in the above-described diffusion plate for improving the luminance or luminance uniformity of the display, the display is reduced in weight, thickness, and manufacturing cost. For this purpose, research and development of optical plates having various functions such as a function of improving the light diffusion effect of the diffusion plate and a function of improving the light collecting effect of the brightness enhancement film (BEF) are required. ing. Consumers are also demanding displays with larger screen sizes (such as liquid crystal televisions), and hope to develop light diffusing plates that not only reduce the number of optical films but also improve brightness and diffusion characteristics. It is rare.

  The present invention has been made in view of the above-described problems, and the object thereof is to provide a projection that can be used as a diffuser plate with improved luminance uniformity while maintaining high luminance. The object is to provide a light transmission plate.

  One embodiment of the present invention includes a main body having a first surface and a protrusion formed on the first surface so as to protrude from the first surface, and the protrusion has an irregular shape. And a slope H connecting the first surface and the upper surface of the protrusion, and a height Hp from the upper surface of the protrusion having an irregular shape to the first surface is not less than 5 μm and not more than 40 μm. The maximum width Wm of the upper surface having a regular shape is not less than 0.15 mm and not more than 8 mm.

  One embodiment of the present invention provides a backlight module including the light transmission plate.

  One embodiment of the present invention provides a display device including a backlight module including the light transmission plate.

  ADVANTAGE OF THE INVENTION According to this invention, the light transmissive board which improved the uniformity of the brightness | luminance while maintaining a high brightness | luminance can be provided. Similarly, a backlight module and a display device having high luminance and high luminance uniformity can be provided.

  In addition, although this invention is demonstrated referring an figure in embodiment mentioned later, this invention is not limited to the embodiment.

It is a partial top view of the light transmission board concerning one Embodiment of this invention. It is a figure which shows the protrusion of the light transmissive board concerning the said embodiment of this invention. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 1 with the optical microscope. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 2 with the optical microscope. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 5 with the optical microscope. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 6 with the optical microscope. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 7 with the optical microscope. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 8 with the optical microscope. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 9 with the optical microscope. It is a figure which shows the image which image | photographed a part of light transmissive board concerning Example 10 with the optical microscope. It is the surface roughness curve of a part of diffuser plate concerning a comparative example measured using a 3D laser scanning confocal microscope. It is the surface roughness curve of the upper surface of the processus | protrusion in the diffusion plate concerning Example 1 measured using the 3D laser scanning confocal microscope. It is the surface roughness curve of parts other than the protrusion in the 1st surface of the main-body part of the diffusion plate concerning Example 1 measured using the 3D laser scanning confocal microscope. It is the surface roughness curve of the upper surface of the processus | protrusion in the diffusion plate concerning Example 2 measured using the 3D laser scanning confocal microscope. It is the surface roughness curve of parts other than the protrusion in the 1st surface of the main-body part of the diffusion plate concerning Example 2 measured using the 3D laser scanning confocal microscope. 1 is a schematic view of a backlight module according to an embodiment of the present invention. It is a figure which shows the measurement result of Examples 1-10 and a comparative example. It is a figure which shows the measurement result of the distance between the adjacent protrusions in Example 1 and Example 2. It is a figure which shows the measurement result of the maximum width Wm of the upper surface of the protrusion in Example 1 and Example 2.

  As one embodiment of the present invention, a light transmission plate that can be applied to a diffusion plate of a backlight module of a display device will be described. In this embodiment, by forming protrusions on the surface of the main body portion of the light transmission plate, the luminance uniformity is improved while the luminance of the light emitting area of the display device is maintained high. Thereby, in the present embodiment, a light transmission plate having high luminance and improved diffusion characteristics is realized. By providing the display device with the light transmissive plate according to the present embodiment, it is possible to reduce the optical film generally used in the conventional display device, thereby reducing the manufacturing cost and making the display device lighter and thinner. (Especially large display devices) can be manufactured. When the light transmission plate according to the present embodiment is applied to a display device, the surface of the main body portion on which the protrusion is formed is disposed so as to face the light source of the backlight module.

  The present embodiment will be described with reference to the drawings showing related structures and configurations. However, the present invention is not limited to these drawings. The same and / or similar members are denoted by the same and / or similar reference numerals. Also, not all embodiments of the invention are shown. Modifications and modifications can be made as appropriate within a range that does not depart from the intent of the present invention so as to satisfy the conditions required in actual application. Other embodiments of the present invention that are not particularly illustrated can also be implemented. Also, the invention is not limited to the dimensions shown. In other words, the drawings and descriptions are not intended to limit the present invention, but merely illustrate one embodiment.

  FIG. 1 is a top view of a part of a light transmission plate according to an embodiment of the present invention. FIG. 2 is a diagram illustrating protrusions of the light transmission plate according to the present embodiment. The present embodiment will be described with reference to FIGS. 1 and 2. The light transmission plate 1 according to the present embodiment includes a main body 10 and a protrusion 20 that is formed on the first surface 101 of the main body 10 and protrudes from the first surface 101. The main body 10 and the protrusion 20 may be integrally formed. Description will be made by paying attention to one protrusion 20. The protrusion 20 is formed in an island shape having an upper surface 201 having an irregular shape, and an inclined surface (for example, the inclined surfaces 203, 204) connecting the upper surface 201 and the first surface 101.

  The upper surface 201 of the protrusion has an irregular shape as shown in FIG. 2 when the protrusion 20 protruding from the first surface 101 along the thickness direction of the main body 10 is vertically projected onto the first surface 101. It means that the shape is irregular. When the distance from the upper surface 201 having an irregular shape to the first surface 101 is defined as a height Hp, the height Hp is set in a range of, for example, 5 μm or more and 40 μm or less. The height Hp may be set in the range of 10 μm to 35 μm. In the light transmission plate 1 according to the embodiment of the present invention, the upper surface 201 of the protrusion 20 is substantially parallel to the first surface 101 of the main body 10.

  The thickness of the light transmission plate 1 is the sum of the thickness Hm of the main body 10 and the thickness Hp of the protrusions 20. When the light transmissive plate 1 according to the present embodiment is used as a diffuser plate of a backlight module (BLM), the thickness of the light transmissive plate 1 may be in the range of 0.5 mm to 6 mm. When the thickness of the light transmission plate 1 is larger than 6 mm, the light transmission plate 1 becomes too heavy to meet the demand for the current display in which lightening and thinning are pursued. On the other hand, if the thickness of the light transmission plate 1 is less than 0.5 mm, the rigidity becomes insufficient and the diffusion characteristics are adversely affected. The thickness of the light transmission plate 1 may be in the range of 0.6 mm to 5 mm (that is, 600 μm to 5000 μm). Further, the thickness of the light transmission plate 1 may be in the range of 0.8 mm to 3 mm, or in the range of 0.8 mm to 2.5 mm.

  The thickness of the light transmission plate 1 is mathematically “the thickness Hm of the main body 10” + “the thickness Hp of the protrusion 20”, but the thickness Hp of the protrusion 20 is larger than the thickness Hm of the main body 10. Can be regarded as being equal to the thickness Hm of the main body 10.

  As shown in FIG. 2, the vertical projection width Ws of the inclined surfaces 203 and 204 of the protrusion 20 with respect to the first surface 101 is 10 μm or more and 160 μm or less. The vertical projection width Ws may be in the range of 12 μm to 150 μm. The vertical projection width Ws may be in the range of 90 μm to 150 μm. Further, the angle of the slopes 203 and 204 with respect to the first surface 101 may be within a range of 120 ° to 177 ° (for example, within a range of 125 ° to 175 °).

  The difference between the light transmissive plate 1 according to the present embodiment and the conventional diffuser plate is that the light transmissive plate 1 according to the present embodiment has a protrusion 20 larger than the fine structure formed on the conventional diffuser plate. It is a point. The maximum width Wm of the irregularly shaped upper surface 201 of the protrusion 20 is in the range of 0.15 mm to 8 mm (that is, 150 μm to 8000 μm). The maximum width Wm may be in the range of 0.175 mm to 7 mm, or may be in the range of 0.2 mm to 6 mm.

  Further, the upper surface 201 having an irregular shape in the protrusion 20 may have a minimum length Dm perpendicular to the maximum width Wm of 0.03 mm or more and 1.5 mm or less.

  Further, the surface roughness (Ra) of the first surface 101 (that is, the portion outside the protrusion 20 on the first surface 101) is set to be smaller than 0.1 μm (for example, less than 0.085 μm, or 0. Within the range of 01 μm or more and 0.08 μm or less). Further, the surface roughness (Ra) of the upper surface 201 of the projection having an irregular shape is set to be smaller than 0.5 μm (for example, within a range of 0.3 μm or less, or 0.01 μm or more and 0.3 μm or less). ). In one embodiment, the surface roughness (Ra) of the outer portion of the protrusion 20 in the main body 10 is in the range of 0.02 μm or more and 0.07 μm or less, and the surface roughness of the upper surface 201 having an irregular shape ( Ra) may be 0.03 μm or more and 0.25 μm or less. Further, the main body 10 has a second surface 102 on the opposite side of the first surface 101. The surface roughness (Ra) of the second surface 102 in the main body 10 is in the range of 3 μm to 30 μm. In addition, you may set the surface roughness (Ra) of the 2nd surface 102 in the main-body part 10 in the range of 4 micrometers or more and 25 micrometers or less. The surface roughness (Ra) is obtained by measuring a cross section or a surface using a three-dimensional (3D) profile meter.

  Although the present embodiment will be described in detail with reference to FIGS. 1 and 2, the present invention is not limited to this.

  As shown in FIG. 1, the light transmission plate 1 includes a plurality of protrusions 20 formed on the first surface 101 of the main body 10 so as to protrude from the first surface 101. The minimum distance d between adjacent protrusions 20 is within a range of 0.01 mm to 1 mm (10 μm to 1000 μm), for example. The minimum distance d may be within a range of 0.015 mm to 0.95 mm (15 μm to 950 μm).

  As shown in FIG. 2, the protrusion 20 according to the present embodiment includes a first slope 203 and a second slope 204 in addition to the upper surface 201 having an irregular shape. The first slope 203 and the second slope 204 are set at both ends of the maximum width (Wm) on the upper surface 201 of the projection having an irregular shape, that is, at positions opposite to each other on the upper surface 201. The first inclined surface 203 and the second inclined surface 204 connect the first surface 101 and the upper surface 201 of the protrusion 20, respectively. Further, the first slope 203 and the first surface 101 form a first angle (180-α1) °, and the second slope 204 and the first surface 101 form a second angle (180-α2) °. The first angle (180−α1) ° and the second angle (180−α2) ° may be different (that is, α1 ≠ α2) or substantially the same (that is, α1). = Α2).

  However, the present invention is not limited to these parameters. The numerical values shown in this specification can be changed as appropriate. The angle with respect to the 1st surface 101 of another part of the slope of the protrusion 20 may be the same as the angle mentioned above, and may differ. Further, the angle formed between the slope of the protrusion 20 and the first surface 101 may be the same or different. These conditions may be modified or changed as appropriate according to the requirements for practical use. For example, the first angle (180-α1) ° and the second angle (180-α2) ° may be within a range of 120 ° to 177 °. Further, the angle formed by the other surface of the slope of the protrusion 20 and the first surface 101 may be in the range of 120 ° to 177 °. Further, the upper surface 201 of the protrusion 20 may be substantially parallel to the first surface 101 of the main body 10.

  In the present embodiment, the light transmission plate is formed of a transparent material such as a transparent resin. Examples of the transparent resin include polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA), methyl methacrylic acid styrene copolymer (MS copolymer), and acrylonitrile styrene copolymer (AS copolymer). ), Cycloolefin copolymer, polyolefin copolymer (such as poly (4-methyl 1-pentane)), polyethylene terephthalate (PET), polyester (PES), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) , Ionomers and the like can be used. For example, polycarbonate (PC), polystyrene (PS), polymethyl methacrylate resin (PMMA), and methyl methacrylate styrene copolymer (MS copolymer) may be used as the material for the light transmission plate.

  In the present embodiment, the light transmission plate 1 has a plurality of light diffusing particles dispersed as a light diffusing agent (ODA) in the main body 10 and the protrusions 20. As the light diffusing agent added to the main body 10 and the protrusions 20, for example, light transmissive particles can be used.

  As the light transmissive particles, for example, inorganic particles such as glass particles, organic particles such as polystyrene resin, methacrylic resin, and silicon resin can be used. As the light transmissive particles, organic particles are preferably used, and cross-linked organic particles are more preferably used. The organic particles are preferably maintained in the form of particles during the treatment of the light-transmitting resin by at least partly cross-linking during the production process. Therefore, it is preferable to use organic particles that do not melt into the light transmitting resin at the molding temperature of the light transmitting resin, and cross-linked methacrylic resin and cross-linked silicon resin are particularly preferable. As a suitable example of the light-transmitting particles, a structure including a partially cross-linked methacrylic resin as a base material and having an inner core made of poly (butyl acrylate) and an outer shell made of poly (methyl methacrylate) And polymer particles (polymer particles). Alternatively, polymer particles having a core / shell structure having a core and an outer shell made of polyethylene rubber (Rohm and Haas, product name: Paraloid EXL-5136) may be used. Alternatively, polymer particles containing a silicon resin such as cross-linked siloxane (silicon-oxygen) (manufactured by Toshiba Silicone, product name: Tospearl 120) may be used.

  In the present embodiment, the average particle diameter (average particle size) of the diffusion particles added to the light transmission plate 1 is in the range of 0.1 μm or more and 30 μm or less. The average particle diameter of the diffusing particles added to the light transmission plate 1 may be in the range of 0.5 μm to 20 μm. The average particle diameter of the diffusing particles added to the light transmission plate 1 may be in the range of 1 μm or more and 5 μm or less. It is preferable that the diffusion particles do not protrude from the surface of the main body 10 and / or the surface of the protrusion 20. Further, the light transmittance of the light transmission plate 1 may be in the range of 50% to 70% (for example, in the range of 55% to 65%).

  Moreover, the average particle diameter of the light transmissive particles (light transmissive particles added as diffusing particles) can be obtained by measuring the weight average particle diameter using a particle counting method. The particle diameter can be analyzed using a particle number / particle distribution analyzer MODEL-Zm (manufactured by Nikka Ki Bios). When the weight average particle diameter of the diffusing particles is smaller than 0.1 μm, the diffusion becomes insufficient, and the light emission from the light emitting surface of the light transmission plate becomes insufficient. On the other hand, even when the weight average particle diameter of the diffusing particles is larger than 30 μm, the diffusion becomes insufficient and light emission from the light emitting surface of the light transmitting plate becomes insufficient, resulting in a decrease in light transmittance.

  Further, the amount of the light transmissive particles (light transmissive particles added to the light transmissive plate 1 as diffusion particles) may be in the range of 0.1 wt% or more and 20 wt% or less with respect to the weight of the transparent resin. In the present embodiment, the light transmissive particles are arbitrarily added within a range of 0.5 wt% to 12 wt% with respect to the weight of the transparent resin. When the amount of the light transmissive particles is less than 0.1 wt% with respect to the weight of the transparent resin, the diffusion becomes insufficient, and the light source disposed under the light transmissive plate is visually recognized. On the other hand, when the amount of the light transmissive particles is larger than 20 wt% with respect to the weight of the transparent resin, the light transmittance and the luminance are lowered.

  The light-transmitting plate 1 is made of light-transmitting polystyrene (PS) resin (for example, GPPS PG-383D, manufactured by Chimi Jitsugyo Co., Ltd.) and light-transmitting particles (light-transmitting particles functioning as the diffusing particles described above). It may be produced by addition. Various methods and apparatuses can be used to manufacture a single-layer plate (that is, the light transmission plate 1). For example, the above single-layer plate may be manufactured by a melt extrusion method used to form a plate-like structure having a predetermined thickness. In the melt extrusion process, the polymer mixture begins to soften in the melt zone of the extruder and the melt is extruded at a predetermined pressure. The pressure in the dissolution zone is reduced from 1.33 kPa to 66.5 kPa before extruding the lysate. If the pressure in the dissolution region is not lowered before the melt is pushed out, oxygen affects the light-transmitting particles (particularly acrylic polymer particles), damages the surface of the particles, and the light diffusing properties deteriorate. In addition, you may form the light transmissive board 1 not only by melt | dissolution extrusion method but using other known methods, such as injection molding, injection compression molding, blow molding, compression molding, powder injection molding.

  The light transmission plate 1 is not limited to a single layer plate, and a multilayer plate may be used. For example, the light transmission plate 1 may have a coating layer laminated on a light transmission resin layer. The thickness of the coating layer may be in the range of 0.01 mm to 0.5 mm, may be in the range of 0.02 mm to 0.4 mm, and is in the range of 0.03 mm to 0.3 mm. It may be within. When the thickness of the coating layer exceeds 0.5 mm, a display device having a backlight module (BLM) becomes too thick to meet the requirements for weight reduction and thinning required for recent displays. The coating layer on the light transmissive resin layer may have high transparency and a lens effect. The coating layer is selected from acrylic resins such as polymethyl methacrylate (PMMA), methyl methacrylate copolymer (MS copolymer), acrylonitrile copolymer (AS copolymer), or a combination thereof. It may be formed of a material. The coating layer is particularly preferably formed of polymethyl methacrylate (PMMA) and methyl methacrylate copolymer (MS copolymer).

  One or more ultraviolet light absorbers may be added to the light transmitting substrate 1 in order to improve weather resistance, light resistance, and ultraviolet resistance. In addition, one or a plurality of phosphors that absorb ultraviolet rays and re-emerge visible light may be added to the light transmission plate 1.

  For example, an ultraviolet light absorber may be added to the light-transmitting plate 1 having a multilayer structure within a range of 0.5 wt% to 15 wt% with respect to the weight of the coating layer made of acrylic resin. The light transmission plate 1 has a light transmission particle having an average particle diameter of 0.1 μm or more and 30 μm or less in a range of 0.1 wt% or more and 20 wt% or less with respect to the weight of the coating layer made of an acrylic resin (preferably It may be arbitrarily added in a range of 0.5 wt% to 12 wt% with respect to the weight of the coating layer made of acrylic resin. In the light transmission plate 1, the phosphor may be added in the range of 0.001 wt% to 0.1 wt% with respect to the weight of the acrylic resin coating layer.

  Examples of the ultraviolet light absorber include benzophenone ultraviolet light absorbers such as 2,2′-dihydroxy-4-methoxybenzophenone, and 2- (4,6-diphenyl-1,3,5-triazine-2-substituent. ) Triazine ultraviolet light absorbers such as 5-hydroxy chlorophenol, 2- (2H-benzotriazole-2-substituent) -4-methylphenol, 2- (2H-benzotriazole-2-substituent) -4- t-octylphenol, 2- (2H-benzotriazole-2-substituent) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2- (2H-benzotriazole-2-substituent) -4 , 6-Bis-t-pentylphenol, 2- (5-chloro-2H-benzotriazole-2-substituent) -4-methyl-6-t-butylphenol , 2- (5-chloro-2H-benzotriazole-2-substituent) -2,4-t-butylphenol, and 2,2′-methylene-bis [6- (2H-benzotriazole-2-substituted) Benzotriazole ultraviolet light absorbers such as group-4- (1,1,3,3-tetramethylbutyl) phenol] and the like can be used.

  Examples of the ultraviolet light absorber include 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-octylphenol) benzotriazole, 2- (2-hydroxy-3, 5-diisopropylbenzene) phenylbenzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2,2′-methylene-bis [4- (1,1,1 3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-substituent) phenol], 2- [2-hydroxy-3- (3,4,5,6-tetrahydrophthalic acid succinimide methyl)- 5-methylphenyl] benzotriazole and the like are suitable. Further, 2- (2-hydroxy-5-t-octylphenol) benzotriazole (manufactured by Ciba Geigy, product name: Tinuvin 329) and 2,2′-methylene-bis [4- (1,1,3,3-tetra Methylbutyl) -6- (2H-benzotriazole-2-substituent) phenol] is also suitable.

  Moreover, the ultraviolet light absorber mentioned above may be used alone or in combination of two or more. The addition amount of the ultraviolet light absorber is preferably in the range of 0.5 wt% to 15 wt% with respect to the weight of the coating layer made of the acrylic resin, and is in the range of 1 wt% to 10 wt%. It is more preferable. When the addition amount of the ultraviolet light absorber is less than 0.5 wt%, the weather resistance is insufficient and the resin is greatly discolored. Moreover, when there is more addition amount of an ultraviolet light absorber than 15 wt%, the hue of resin and the brightness | luminance of light will deteriorate.

  In addition, with the phosphor that absorbs ultraviolet light and emits visible light, a white resin or a bluish white resin can be formed by changing the color of the resin without reducing light resistance. Examples of such phosphors include diphenylethylene-base compound, benzimidazole-base compound, benzoxazole-base compound, phthalimide-base compound, rhodamine-base compound, coumarin-base compound, oxazole-base compound and the like. It is done. The added amount of the phosphor may be, for example, in the range of 0.001 wt% to 0.1 wt% with respect to the weight of the coating layer made of acrylic resin, and is 0.002 wt% to 0.08 wt%. It is more preferable to be within the range. The phosphor can be arbitrarily added within the above-described range so that the luminance and color of light can be improved.

[Experimental example]
Examples and comparative examples related to the present embodiment are shown below. The structure of the light transmission plate 1 is as described in FIGS. 1 and 2 and described above. Comparative examples and Examples 1 to 10 are shown below.

  As a comparative example, a commercially available diffusion plate DS601A (manufactured by Kitami Business Co., Ltd., Taiwan) that does not have island-like protrusions protruding from the surface of the main body was used.

  In Examples 1, 2, 5-7, and 9, the thickness of the light transmission plate was 1.2 mm. In Examples 3, 4, 8, and 10, the thickness of the light transmission plate was set to 2.2 mm. In addition, the light transmission plates in Examples 1 to 10 include a plurality of protrusions 20 formed on the first surface 101 of the main body 10 so as to protrude from the first surface 101. The protrusion 20 and the main body 10 are integrally formed.

Measuring method:
(1) Luminance and luminance uniformity at four corners:
The luminance was measured using a BM-7A color luminance meter (Topcon Corporation, Japan). The light transmissive plates of Examples 1 to 10 and the comparative example were placed on a light emitting module on which LEDs were arranged for luminance measurement. The central luminance of Examples 1 to 10 is normalized by dividing by the central luminance of the comparative example. That is, the central luminance in Examples 1 to 10 is a value when the central luminance in the comparative example is 100%. The luminance uniformity at the four corners is obtained by calculating an average value of four values obtained by dividing the luminance values at the four corners of the module to be measured by the central luminance of the module.

(2) Surface roughness:
The surface roughness was measured using a 3D laser scanning confocal microscope (model: VK-X100 series, Keyence Corporation). Based on the method defined in JIS B0601-2001, the sampling position is randomly selected within a region of 10 mm × 10 mm, and the surface roughness parameter (Ra Alternatively, Rz) was detected. The average roughness depth Rz is the difference between the maximum value and the minimum value in the surface roughness distribution.

(3) The height Hp from the upper surface to the first surface, the vertical projection width Ws of the inclined surface with respect to the first surface, and the angle formed by the inclined surface and the first surface:
For the light transmission plates of Examples 1 to 10 and Comparative Example, two points corresponding to the longest distance on the upper surface of the protrusion (that is, both ends of the maximum width Wm of the upper surface) are measured using a 3D laser scanning confocal microscope. Thus, the profile of the cross section was measured. Further, the height Hp of the cross section was measured from the upper surface 201 of the protrusion 20 to the first surface 101, and the vertical projection width Ws of the inclined surface of the protrusion 20 with respect to the first surface 101 was measured. In Examples 1 to 10, the vertical projection width Ws was the value of the width of the portion extending from the maximum width Wm of the upper surface of the protrusion to the left side of the protrusion. However, the present invention is not limited to this. The vertical projection width Ws may be a width of a portion extending from the maximum width Wm of the upper surface of the protrusion to either side of the protrusion. Further, the angles α1 and α2 can be calculated using the values of Hp and Ws and a trigonometric function, and the angles 180−α1 and 180 between the inclined surface and the first surface using the calculated angles α1 and α2. -Α2 is also obtained.

(4) Distance between adjacent protrusions:
The distance was measured using a 3D laser scanning confocal microscope (model: VK-X100 series, Keyence Corporation). Twenty samples were randomly selected within a measurement area of 10 mm × 10 mm. The “maximum value of the minimum distance between adjacent protrusions” in the measurement result means the maximum value among the minimum distances between adjacent protrusions in the measurement region. The “minimum value of the minimum distance between adjacent protrusions” means the minimum value of the minimum distances between adjacent protrusions in the measurement region. The distance between adjacent protrusions may be in the range of 0.01 mm to 1 mm (10 μm to 1000 μm), preferably 0.015 mm to 0.95 mm (15 μm to 950 μm). .

(5) Maximum width Wm and minimum length Dm of the upper surface 201 of the protrusion:
The width and length were measured using a 3D laser scanning confocal microscope (model: VK-X100 series, Keynence). Twenty samples were randomly selected within a measurement area of 10 mm × 10 mm, and the range of the maximum width Wm on the upper surface of the protrusion and the range of the minimum length Dm perpendicular to the maximum width Wm were measured. The maximum width Wm of the upper surface 201 of the protrusion 20 may be 0.15 mm or more and 8 mm or less (150 μm or more and 8000 μm or less), preferably 0.155 mm or more and 7 mm or less, and more preferably 0.158 mm or more and 6 mm or less. More preferred. The minimum length Dm of the upper surface 201 of the protrusion 20 may be 0.03 mm to 1.5 mm, preferably 0.05 mm to 1.2 mm, and preferably 0.07 mm to 1.05 mm. More preferred.

(6) Protrusion area / protrusion outer peripheral length (μm), protrusion area ratio:
Using an optical microscope (model: Bx-60 F5, Olympus), an image in the measurement area of 6.821 mm × 5.312 mm (area: 36.233 mm ² ) is taken, and analysis software (Image Pro Plus) is used. Thus, the area and outer peripheral length of all the protrusions in the measurement region were calculated. “Protrusion area / projection outer peripheral length” is a value obtained by dividing the total area of the protrusions arranged in the measurement region by the total outer peripheral length of the protrusions arranged in the measurement region. The “protrusion area ratio” is a value obtained by dividing the total area of the protrusions arranged in the measurement region by the area of the measurement region (36.233 mm ² ). FIGS. 3-1 to 3-8 show images obtained by imaging the measurement portions of the light transmission plates of Examples 1, 2, and 5 to 10 with an optical microscope, respectively. Each light transmissive plate according to the embodiment includes a plurality of protrusions formed on the first surface so as to protrude from the first surface of the main body. In addition, the “outer peripheral boundary line” shown in the figure indicates the measurement area of the area of the protrusion and the outer peripheral length. A thick boundary line indicates a slope, and a rough area in the thick boundary line indicates an upper surface of a projection having an irregular shape. The “projection area / projection outer peripheral length” may be in the range of 100 μm to 200 μm, preferably 110 μm to 190 μm, and more preferably 115 μm to 175 μm. Further, the “projection area ratio” may be 35% or more and 70% or less, preferably 38% or more and 68% or less, and more preferably 40% or more and 66% or less.

  The measurement results are shown in FIG.

  FIG. 4 is a surface roughness curve showing a result obtained by measuring a part of the diffusion plate according to the comparative example with a 3D laser scanning confocal microscope. From this measurement result, it can be seen that the upper surface and the lower surface of the diffusion plate according to the comparative example are both rough surfaces having a plurality of depressions with a large difference in height, and the upper surface and the lower surface cannot be clearly distinguished. The results of measuring Rz at two points are 11.99 μm and 9.49 μm, and it can be seen that the surface of the commercially available diffusion plate is quite rough.

  5A and 5B will be described. FIG. 5A is a surface roughness curve showing a result obtained by measuring the upper surface of the protrusion in the light transmission plate according to Example 1 with a 3D laser scanning confocal microscope. From the result shown in FIG. 5A, it can be seen that the upper surface 201 of the protrusion in Example 1 is generally flat, although there are a few very small holes. When the depth of the hole on the upper surface 201 of the protrusion in Example 1 was measured at two points, Rz was 0.52 μm and 0.41 μm. FIG. 5B is a surface roughness curve showing a result obtained by measuring the first surface of the main body 10 in the light transmission plate according to Example 1 with a 3D laser scanning confocal microscope. From the result shown in FIG. 5B, the portion other than the protrusions 20 on the first surface in Example 1 was also generally flat although there were a few very small holes. When the depth of the hole in the portion other than the protrusion 20 on the first surface of Example 1 was measured at two points, Rz was 0.95 μm and 0.98 μm.

  6A and 6B will be described. FIG. 6A is a surface roughness curve showing a result obtained by measuring the upper surface of the protrusion in the light transmission plate according to Example 2 with a 3D laser scanning confocal microscope. From the results shown in FIG. 6A, it can be seen that the upper surface 201 of the protrusion in Example 2 is generally flat although there are a few very small holes. When the depth of the hole on the upper surface 201 of the protrusion in Example 2 was measured at two points, Rz was 0.49 μm and 0.61 μm. FIG. 6B is a surface roughness curve showing a result obtained by measuring the first surface of the main body 10 in the light transmission plate according to Example 2 with a 3D laser scanning confocal microscope. From the result shown in FIG. 6B, the portion other than the protrusions 20 on the first surface in Example 2 was generally flat although there were a few very small holes. When the depth of the hole in the portion other than the protrusion 20 on the first surface of Example 2 was measured at two points, Rz was 0.48 μm and 0.31 μm.

  FIG. 7 shows a backlight module according to an embodiment of the present invention. The backlight module 700 according to the present embodiment can be used as a direct type backlight module for a flat panel display. The backlight module 700 includes a diffusion plate 710, at least one light source 720 (a plurality of light sources are shown in FIG. 7), and a frame 740. The frame 740 includes a housing portion 742 that houses the diffusion plate 710 and the light source 720, and the diffusion plate 710 is disposed above the light source 720 in the housing portion 742. The diffusion plate 710 is made of the light transmission plate of any one of the above-described Examples 1 to 10, and the main body portion 10 having the first surface 101 and the first surface 101 so as to protrude from the first surface 101 of the main body portion 10. And a protrusion 20 formed thereon. The light source 720 and the first surface 101 are disposed so as to face each other, and the first surface 101 is used as a light incident surface. Each light source 720 includes a substrate portion 722 and a light emitting unit 724 disposed on the substrate portion 722. As the light emitting unit 724, for example, a light emitting diode (LED) or another type of light emitting device can be used. The light emitted from the light emitting unit 724 enters the diffusion plate 710 and exits from the second surface 102 of the diffusion plate 710. Thereby, a surface light source having high brightness and uniform brightness is formed.

  The backlight module 700 can be used as a backlight module of a display device such as a liquid crystal display, for example.

  The measurement results of the distance between adjacent protrusions in Example 1 and Example 2 are shown in FIG. The distance was measured using a 3D laser scanning confocal microscope (model: VK-X100 series, Keyence Corporation). In order to obtain measurement results, a plurality of samples were randomly extracted within a measurement range of 10 mm × 10 mm. “Maximum value” in FIG. 9 indicates the maximum value among the minimum distances between adjacent protrusions in the measurement range, and “Minimum value” indicates the minimum distance between adjacent protrusions in the measurement range. The minimum value is shown.

  FIG. 10 shows the measurement result of the maximum width Wm of the upper surface 201 of the protrusion 20 (protrusion having an irregular shape) in the first and second embodiments. The width was measured using a 3D laser scanning confocal microscope (model: VK-X100 series, Keyence Corporation). In order to obtain measurement results, a plurality of samples were randomly extracted within a measurement range of 10 mm × 10 mm. Further, in FIG. 10, the distance between the recessed holes existing on the surface of the diffusion plate (DS601A, manufactured by Chimi Jitsugyo Co., Ltd.) according to the comparative example is shown as a 3D laser scanning confocal microscope (model: VK-X100 series, The results of measurement using Keyence Corporation are also shown. In the comparative example, the distance between the recessed holes existing on the surface of the diffusion plate was in the range of 5 μm to 50 μm.

  As described above, the light transmission plate according to the present embodiment includes the main body portion and the protrusion protruding from the main body portion. When the light transmission plate according to the present embodiment (the light transmission plate shown in FIG. 1) is used as a diffusion plate, the first surface 101 having the protrusions is disposed so as to face the light source of the backlight module. Thereby, the 1st surface 101 turns into a light-incidence surface, and the 2nd surface 102 of the main-body part 10 turns into a light-projection surface. By using the light transmission plate according to the present embodiment as the diffusion plate of the backlight module in the display device, the luminance of the light emission region is increased compared with the display device using the diffusion plate that is conventionally marketed. Uniformity can be improved. Therefore, by using the light transmissive plate according to the present embodiment for the display device, the display image quality can be remarkably improved, and the number of optical films can be reduced as compared with the conventional display device. The display device (particularly a large display device) can be reduced in weight and thickness. By using the light transmission plate according to the present embodiment, a large effect can be obtained particularly in a large display device.

  Although the present invention has been described based on typical embodiments, the present invention is not limited to the above-described embodiments. The present invention includes various modifications and similar configurations and methods, and the invention described in the claims includes those modifications and similar configurations and methods.

Claims (26)

A main body having a first surface;
A protrusion formed on the first surface so as to protrude from the first surface;
The protrusion has an upper surface having an irregular shape, and a slope connecting the first surface and the upper surface,
A light transmission plate, wherein a height Hp from the upper surface to the first surface is 5 μm or more and 40 μm or less, and a maximum width Wm of the upper surface is 0.15 mm or more and 8 mm or less.   The light transmission plate according to claim 1, wherein the thickness is 0.5 mm or more and 6 mm or less.   The light transmission plate according to claim 1, wherein a vertical projection width Ws of the inclined surface with respect to the first surface is 10 μm or more and 160 μm or less.   The light transmission plate according to any one of claims 1 to 3, wherein an angle formed by the slope and the first surface is 120 ° or more and 177 ° or less.   5. The upper surface having an irregular shape in the protrusion has an irregular shape when vertically projected onto the first surface along the thickness direction of the main body. The light transmissive plate according to any one of the above.   It consists of transparent resin, The light transmissive board of any one of Claims 1-5 characterized by the above-mentioned.   The plurality of diffusion particles are dispersed in the main body and the protrusion, and the average particle size of the diffusion particles is 0.1 μm or more and 30 μm or less. Light transmission plate.   The light transmission plate according to claim 7, wherein an average particle diameter of the plurality of diffusion particles is 0.5 μm or more and 20 μm or less.   The light transmission plate according to claim 7, wherein an average particle diameter of the plurality of diffusion particles is 1 μm or more and 5 μm or less. A plurality of protrusions protruding from the first surface of the main body,
The light transmission plate according to claim 1, wherein a minimum distance between the adjacent protrusions is in a range of 10 μm to 1000 μm.   The surface roughness (Ra) of portions other than the protrusions on the first surface is less than 0.1 μm, and the surface roughness (Ra) of the upper surface having an irregular shape is less than 0.5 μm. The light transmission plate according to any one of claims 1 to 10.   The surface roughness (Ra) of portions other than the protrusions on the first surface is 0.01 μm or more and 0.08 μm or less, and the surface roughness (Ra) of the upper surface having an irregular shape is 0.01 μm or more and 0. The light transmission plate according to claim 1, wherein the light transmission plate is 3 μm or less.   The surface roughness (Ra) of portions other than the protrusions on the first surface is 0.02 μm or more and 0.07 μm or less, and the surface roughness (Ra) of the upper surface having an irregular shape is 0.03 μm or more and 0. The light transmission plate according to claim 1, wherein the light transmission plate has a thickness of .25 μm or less. The main body includes a second surface opposite to the first surface;
14. The light transmission plate according to claim 1, wherein the second surface has a surface roughness (Ra) of 3 μm or more and 30 μm or less.   The light transmission plate according to claim 14, wherein the first surface is a light incident surface, and the second surface is a light emission surface.   The light transmittance plate according to any one of claims 1 to 15, wherein the light transmittance is 50% or more and 70% or less.   The light transmission plate according to claim 1, wherein the main body and the protrusion are integrated.   The light transmission plate according to claim 1, wherein the upper surface of the protrusion is substantially parallel to the first surface of the main body. The protrusion has a first inclined surface and a second inclined surface located on both end sides of the maximum width Wm of the upper surface of the protrusion having an irregular shape, and the first inclined surface and the second inclined surface are the first inclined surface and the second inclined surface, respectively. 1 surface is connected to the upper surface,
The first angle, which is an angle formed by the first slope and the first surface, and a second angle, which is an angle formed by the second slope and the first surface, are different from each other. The light transmissive plate according to any one of -18. The protrusion has a first inclined surface and a second inclined surface located on both end sides of the maximum width Wm of the upper surface of the protrusion having an irregular shape, and the first inclined surface and the second inclined surface are the first inclined surface and the second inclined surface, respectively. 1 surface is connected to the upper surface,
A first angle that is an angle formed by the first inclined surface and the first surface, and a second angle that is an angle formed by the second inclined surface and the first surface are within a range of 120 ° to 177 °, respectively. The light transmission plate according to claim 1, wherein the light transmission plate is a light transmission plate.   21. The minimum length in a direction perpendicular to the maximum width of the upper surface of the protrusion having an irregular shape is 0.03 mm or more and 1.5 mm or less, wherein the protrusion has an irregular shape. Light transmission plate.   The ratio of the area of the said protrusion with respect to the area of the said 1st surface is 35% or more and 70% or less, The light transmissive board of any one of Claims 1-21 characterized by the above-mentioned.   The light transmission plate according to claim 1, wherein a value obtained by dividing the area of the protrusion by the outer peripheral length of the protrusion is 100 μm or more and 180 μm or less. A light source and the light transmissive plate according to any one of claims 1 to 23,
The backlight module, wherein the first surface is arranged to face the light source.   The backlight module according to claim 24, wherein the first surface is a light incident surface.   A display device comprising the backlight module according to claim 24 or 25.

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