JP2016181474A - Light guide member, surface light source device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide member into which a quantum dot layer containing quantum dots is assembled, in an excellently practical mode.SOLUTION: A light guide member 22 includes: a glass-based light guide plate 30 having a light emission surface 31 and a light incident surface 33 facing a direction different from the light emission surface 31; a low refractive index layer 80 connected to the light emission surface 31 of the light guide plate 30 and having a refractive index lower than that of the light guide plate 30; a quantum dot layer 60 connected to a surface on the opposite side to the surface connected to the light guide plate 30, of the low refractive index layer 80, and containing quantum dots 61; and a barrier layer 85 covering a surface on the opposite side to the surface connected to the low refractive index layer 80, of the quantum dot layer 60.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light guide member having a light guide plate and a quantum dot layer, and more particularly to a light guide member excellent in practicality. Moreover, this invention relates to the surface light source device and display apparatus which have this light guide member.

  2. Description of the Related Art A surface light source device that irradiates light in a planar shape is widely used as a backlight that is incorporated in, for example, a liquid crystal display device and illuminates a liquid crystal display panel from the back side. Surface light source devices for liquid crystal display devices can be broadly divided into a direct type in which a light source is disposed directly under a light guide member, and an edge light type (also referred to as a side light type) in which a light source is disposed on a side of the light guide member. ,are categorized.

  The edge light type surface light source device has a structural feature that enables the surface light source device to be thinner than a direct type surface light source device. Due to this structural feature, the edge light type surface light source device has been mainly applied to a display device for a notebook personal computer (hereinafter, also simply referred to as “notebook PC”).

  Mobile devices represented by notebook PCs are required to have high color reproducibility in addition to thinning. In this regard, for example, Patent Document 1 describes that a quantum dot sheet including quantum dots having excellent color reproducibility is incorporated into a light guide member or a surface light source device. The quantum dots function as phosphors and can absorb light and emit light of different wavelengths. The wavelength of the light emitted from the quantum dot mainly depends on the particle size of the quantum dot. Therefore, in a surface light source device incorporating a quantum dot layer, various colors can be reproduced while using a light source that projects light in a single wavelength region. For example, the light source can project blue light, and the quantum dots can absorb blue light and emit red light and green light. Since such a surface light source device is excellent in color purity, a display device using this surface light source device has excellent color reproducibility.

Special table 2013-539170 gazette

  In particular, the surface light source device described in Patent Document 1 employs an on-edge method in which a quantum dot sheet is disposed between a light source and a light guide plate. However, in the on-edge method, since the quantum dot sheet is positioned adjacent to the light source, a decrease in light emission efficiency due to the influence of heat cannot be avoided. In addition, a method of accommodating and protecting the quantum dot sheet in a glass tube in consideration of heat resistance is also used, but a space is required for the arrangement of the glass tube, so that the surface light source device becomes large. .

  Thinning and high color reproducibility are strongly demanded in applications such as mobile devices that are evolving day by day. However, as described above, a light guide member and a surface light source device incorporating a quantum dot sheet with excellent practicality have not yet been realized.

  This invention is based on such knowledge, and it aims at providing the light guide member in which the quantum dot layer containing a quantum dot was integrated in the aspect excellent in practicality. Another object of the present invention is to provide a surface light source device and a display device in which the light guide member is incorporated.

  The first light guide member according to the present invention includes a light guide surface, a glass light guide plate having a light incident surface facing in a direction different from the light output surface, and the light guide plate joined to the light output surface of the light guide plate. A low refractive index layer having a lower refractive index, a quantum dot layer including a quantum dot bonded to a surface of the low refractive index layer opposite to a surface bonded to the light guide plate, and the quantum dot layer A barrier layer covering a surface opposite to the surface bonded to the low refractive index layer.

  In the first light guide member according to the present invention, the light guide plate includes a back surface facing the light output surface and a plurality of extraction elements arranged in a pattern, and the extraction element includes at least light incident from a certain angle. A part of the light may be directed in a direction different from the direction in which the light incident on the back surface other than the region where the extraction element is disposed is reflected from the certain angle.

  The second light guide member according to the present invention includes a light guide plate having a light exit surface and a light incident surface facing in a direction different from the light exit surface, and is arranged in a pattern on the light exit surface of the light guide plate. A low refractive index pattern layer having a low refractive index, a quantum dot layer including quantum dots bonded to the light exit surface of the light guide plate in which the low refractive index pattern layer is disposed, and the light guide plate of the quantum dot layer A barrier layer that covers a surface opposite to the bonded surface.

  A third light guide member according to the present invention includes a light guide surface, a light guide plate having a light incident surface facing in a direction different from the light output surface, a pattern array on the light output surface of the light guide plate, and quantum dots. A quantum dot pattern layer; and a low refractive index layer having a refractive index lower than that of the light guide plate and covering the light output surface of the light guide plate on which the quantum dot pattern layer is disposed.

  In the third light guide member according to the present invention, the low refractive index layer may also function as a barrier layer for the quantum dot pattern layer.

  In the second or third light guide member according to the present invention, the light guide plate may be made of glass.

  The display device according to the present invention includes any one of the light guide members according to the present invention described above and a light source disposed to face the light incident surface of the light guide member.

  A display device according to the present invention includes the above-described surface light source device according to the present invention and a display panel disposed to face the surface light source device.

  ADVANTAGE OF THE INVENTION According to this invention, the light guide member in which the quantum dot layer was integrated is realizable in the aspect excellent in practicality.

1 is a cross-sectional view illustrating a schematic configuration of a display device according to a first embodiment. Sectional drawing which shows the surface light source device and light guide member which comprise the display apparatus shown in FIG. FIG. 3 is a perspective view showing a prism sheet incorporated in the display device shown in FIG. 1. Sectional drawing which shows the cross section of the prism sheet along line IV-IV shown in FIG. FIG. 3 is a cross-sectional view illustrating how light is extracted from a light guide member incorporated in the surface light source device illustrated in FIG. 2. Sectional drawing which shows the other example of the extraction element of the light guide member shown in FIG. Sectional drawing which shows the example in which the side surface barrier material was further provided in the light guide member shown in FIG. Sectional drawing which shows schematic structure of the surface light source device by 2nd Embodiment. Sectional drawing which expands and shows the light guide member integrated in the surface light source device shown in FIG. Sectional drawing which shows schematic structure of the surface light source device by 3rd Embodiment. Sectional drawing which expands and shows the light guide member integrated in the surface light source device shown in FIG.

  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.

<< First Embodiment >>
1 to 7 are diagrams for explaining the first embodiment. Among these, FIG. 1 is a perspective view showing a schematic configuration of the liquid crystal display device 10 and the surface light source device 20.

  As shown in FIG. 1, the display device 10 includes a liquid crystal display panel 15 and a surface light source device 20 that is disposed on the back side of the liquid crystal display panel 15 and illuminates the liquid crystal display panel 15 in a planar shape from the back side. . The display device 10 has a display surface 10a for displaying an image. The liquid crystal display panel 15 functions as a shutter that controls transmission or blocking of light from the surface light source device 20 for each pixel, and is configured to display an image on the display surface 10a.

  The illustrated liquid crystal display panel 15 is disposed between the upper polarizing plate 13 disposed on the light output side, the lower polarizing plate 14 disposed on the light incident side, and the upper polarizing plate 13 and the lower polarizing plate 14. And a liquid crystal layer cell 12. The polarizing plates 14 and 13 decompose the incident light into two orthogonal polarization components (P wave and S wave) and vibrate in one direction (direction parallel to the transmission axis) (for example, P wave). ) And absorbs a linearly polarized light component (for example, S wave) that vibrates in the other direction (direction parallel to the absorption axis) perpendicular to the one direction.

  An electric field can be applied to the liquid crystal layer 12 for each region where one pixel is formed. Then, the alignment direction of the liquid crystal molecules in the liquid crystal layer 12 changes depending on whether or not an electric field is applied. As an example, a polarization component in a specific direction that has passed through the lower polarizing plate 14 disposed on the light incident side rotates the polarization direction by 90 ° when passing through the liquid crystal layer 12 to which an electric field is applied. When passing through the liquid crystal layer 12 that is not applied, the polarization direction is maintained. In this case, depending on whether or not an electric field is applied to the liquid crystal layer 12, does the polarized light component that vibrates in a specific direction transmitted through the lower polarizing plate 14 further pass through the upper polarizing plate 13 disposed on the light output side of the lower polarizing plate 14? Alternatively, it is possible to control whether the light is absorbed and blocked by the upper polarizing plate 13.

  The liquid crystal display panel 15 further includes a brightness enhancement layer 11 on the light incident side of the lower polarizing plate 14. The brightness enhancement layer 11 converts a linearly polarized light component (for example, an S wave) that vibrates in a direction to be absorbed by the lower polarizing plate 14 into a linearly polarized light component (for example, an S wave) that vibrates in the direction to be transmitted by the lower polarizing plate 14 , P wave) and transmitting. Examples of such a brightness enhancement layer 11 include the DBEF series manufactured by Sumitomo 3M.

  In this manner, the liquid crystal panel (liquid crystal display unit) 15 can control transmission or blocking of light from the surface light source device 20 for each pixel. The details of the liquid crystal display panel 15 are described in various publicly known documents (for example, “Flat Panel Display Dictionary (supervised by Tatsuo Uchida, Hiraki Uchiike)” published in 2001 by the Industrial Research Council). The detailed description above is omitted.

  Next, the surface light source device 20 will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the surface light source device 20. The surface light source device 20 has a light emitting surface 21 that emits light in a planar shape, and is used as a device that illuminates the liquid crystal display panel 15 from the back side in the present embodiment.

  As shown in FIG. 2, the surface light source device 20 is configured as an edge light type surface light source device, and the side of the light guide member 22 and one side (left side in FIG. 1) of the light guide member 22. And the two prism sheets 71 and 72 disposed on the light output side of the light guide plate 30, and the reflective layer 28 disposed on the back surface side of the light guide plate 30. In the illustrated example, the second prism sheet 72 is arranged facing the liquid crystal display panel 15. The light emitting surface 21 of the surface light source device 20 is defined by the light emitting side surface 72 a of the second prism sheet 72 arranged on the light emitting side of the two prism sheets 71 and 72.

  The light guide member 22 is configured to uniformly irradiate the liquid crystal display panel 15 with excellent color purity from the light source 24, and includes a light guide plate 30 that guides the light from the light source 24 as a main configuration. It is out.

  As shown in FIG. 2, the light guide plate 30 includes a light output surface 31 formed by one main surface on the liquid crystal display panel 15 side, a back surface 32 formed of the other main surface facing the light output surface 31, and a light output surface. And a side surface extending between the rear surface 32 and the rear surface 32. One of the two surfaces facing the first direction d <b> 1 of the side surfaces forms the light incident surface 33. As shown in FIG. 1, a light source 24 is provided facing the light incident surface 33. Light that has entered the light guide plate 30 from the light incident surface 33 is directed in the first direction (light guide direction) d1 toward the opposite surface 34 that faces the light incident surface 33 along the first direction (light guide direction) d1. The light is guided through the light guide plate 30.

  In the illustrated example, the light exit surface 31 of the light guide plate 30 has a plan view shape (looking down from above in FIG. 1), like the display surface 10 a of the liquid crystal display device 10 and the light emitting surface 21 of the surface light source device 20. (Viewed shape) is formed in a square shape. As a result, the light guide plate 30 is generally configured as a rectangular parallelepiped member having a pair of main surfaces (light-emitting surface 31 and back surface 32) in which the sides in the thickness direction are smaller than the other sides. A side surface defined between the pair of main surfaces includes four surfaces. Similarly, the prism sheets 71 and 72 and the reflection sheet 28 are generally configured as rectangular parallelepiped members having relatively smaller sides in the thickness direction than other sides.

  The light source 24 may be configured in various modes such as a fluorescent lamp such as a linear cold cathode tube, a point LED (light emitting diode), an incandescent lamp, and the like. In the present embodiment, the light source 24 has a large number of dots arranged side by side along the longitudinal direction of the light incident surface 33 (in FIG. 1, the direction orthogonal to the paper surface, that is, the front and back direction of the paper surface). The light emitter 25, specifically, a plurality of light emitting diodes (LEDs). In the surface light source device 20 described here, the light source 24 can include only the light emitter 25 that emits light in a single wavelength region, in association with the later-described quantum dot layer 60. For example, the light emitter 25 can include only a light emitting diode that emits blue light with high color purity as the light emitter 25.

  Further, the reflective layer 28 is disposed so as to face the back surface 32 of the light guide plate 30. The reflection layer 28 is a member for reflecting light leaking from the back surface 32 of the light guide plate 30 and returning it to the light guide plate 30 side again. The reflection layer 28 includes a white scattering reflection layer, a sheet made of a material having a high reflectance such as metal, a sheet containing a thin film (for example, a metal thin film) made of a material having a high reflectance as a surface layer, and the like. obtain. The reflection at the reflection layer 28 may be regular reflection (specular reflection) or diffuse reflection. When the reflection at the reflection layer 28 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

  By the way, in this specification, the “light exit side” refers to the light source 24, the light guide member 22, the first prism sheet 71, the second prism sheet 72, the liquid crystal display panel 15, and the components of the display device 10. It is the downstream side (observer side, for example, the upper side of the paper surface in FIG. 1) in the traveling direction of the light that travels from the display device 10 and travels toward the observer, and the “light incident side” is a light source 24, the light guide member 22, the first prism sheet 71, the second prism sheet 72, the liquid crystal display panel 15, and the components of the display device 10 are moved back without going back, and emitted from the display device 10 to the observer. It is the upstream side in the traveling direction of the light to go.

  Further, in the present specification, terms such as “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.

  Further, in this specification, the “sheet surface (plate surface, film surface)” corresponds to the planar direction of the target sheet-like member when the target sheet-like member is viewed as a whole and globally. Refers to the surface. In the present embodiment, the plate surface of the light guide plate 30, the sheet surface of the first prism sheet 71, the sheet surface of the second prism sheet 72, the sheet surface of the reflection sheet 28, the panel surface of the liquid crystal display panel, and the display device The display surface 10a of 10 and the light emitting surface 21 of the surface light source device 20 are parallel to each other.

  Further, in the present specification, the normal direction of the sheet-like (plate-like) member refers to the normal direction to the sheet surface (plate surface) of the target sheet-like (plate-like) member. Further, in the present specification, the “front direction” is a normal direction to the light emitting surface 21 of the surface light source device 20, and in this embodiment, the normal to the light emitting surface 21 of the surface light source device 20. Direction, normal direction to the plate surface of the light guide plate 30, normal direction to the sheet surface of the first prism sheet 71, normal direction to the sheet surface of the second prism sheet 72, to the display surface 10a of the display device 10. (For example, see FIG. 2).

  Next, each component constituting the light guide member 22 will be further described in detail. As shown in FIG. 2, the light guide member 22 includes the light guide plate 30, the low refractive index layer 80, the quantum dot layer 60, and the barrier layer 85 from the light incident side toward the light outgoing side. Includes in order.

  The low refractive index layer 80 is made of a material having a lower refractive index than the material forming the light guide plate 30. The low refractive index layer 80 is bonded to the light output surface 31 of the light guide plate 30 and covers the entire area of the light output surface 31 without a gap. The low refractive index layer 80 covers the light exit surface 31 of the light guide plate 30 without a gap, so that an interface having a refractive index difference is formed between the low refractive index layer 80 and the light exit surface 31 of the light guide plate 30. This interface functions as an interface for selectively extracting light guided through the light guide plate 30. That is, when the incident angle of light guided through the light guide plate 30 to the light exit surface 31 is equal to or greater than the total reflection critical angle, the light guided is totally reflected at the interface and enters the light guide plate 30. Returned. On the other hand, when the incident angle of the light guided through the light guide plate 30 to the light exit surface 31 is less than the total reflection critical angle, the light is transmitted through the interface and taken out from the light guide plate 30.

  Further, as shown in FIG. 2, a plurality of extraction elements 40 are arranged in a pattern on the back surface 32 of the light guide plate 30. The extraction element 40 functions to extract light guided in the light guide plate 30 along the first direction d1. In the present embodiment, the plurality of extraction elements 40 are arranged at intervals in the first direction d1 that is the light guide direction, and each extraction element 40 intersects the first direction d1 along the back surface 32. Specifically, it extends in the orthogonal direction.

  The extraction element 40 of the present embodiment has a function of diffusing and reflecting incident light. As an example, the extraction element 40 having a diffuse reflection function can be obtained by screen printing, inkjet printing, or photolithography processing on the back surface 32 with white ink having a diffuse reflection function.

  When the extraction element 40 has a diffuse reflection function, light incident on the extraction element 40 is diffusely reflected by the extraction element 40 and travels in various directions. Part of the light diffusely reflected by the extraction element 40 has an incident angle on the light output surface 31 that is equal to or greater than the total reflection critical angle, and is totally reflected by the light output surface 31 and returns to the back surface 32 again. Another part of the light diffusely reflected at 40 has an incident angle on the light exit surface 31 that is less than the total reflection critical angle, and is transmitted through the light exit surface 31.

  On the other hand, when the light guided through the light guide plate 30 enters the region 32b of the back surface 32 other than the region 32a where the extraction element 40 is disposed, the light is totally reflected by the region 32b and then incident. The incident angle to the outgoing light exit surface 31 is also maintained. Therefore, the light totally reflected by the region 32b other than the region 32a where the extraction element 40 is disposed is then totally reflected by the light output surface 31 and guided toward the opposite surface 34.

  In other words, when the direction in which the light L21 incident on the region 32b other than the region 32a of the back surface 32 of the back surface 32 is reflected from any given direction dx is dy, the extraction element 40 is At least a part of the light L22 incident from the certain direction dx is directed to a direction dz different from the direction dy to which the light L21 reflected by the region 32b is directed. A part of the light L <b> 22 heading in the different direction dz is extracted from the light exit surface 31.

  In particular, in the present embodiment, the plurality of extraction elements 40 are arranged at a constant pitch along the first direction d1, and are arranged close to the opposite surface 34 along the first direction d1. The extraction element 40 tends to have a longer length along the first direction d1. Therefore, as the distance from the incident surface 33 to the opposite surface 34 approaches the first direction d1, the ratio of the region of the back surface 32 where the extraction element 40 is disposed increases. According to such a configuration, emission of light from the light guide plate 30 in a region separated from the incident surface 33 along the light guide direction is promoted, and the amount of emitted light decreases as the distance from the incident surface 33 increases. Can be effectively prevented.

  In this way, the light extracted without deviation from the light exit surface 31 of the light guide plate 30 passes through the low refractive index layer 80 and enters the quantum dot layer 60. The quantum dot layer 60 is bonded to the surface opposite to the surface bonded to the light guide plate 30 of the low refractive index layer 80, and covers the entire area of the surface without a gap.

  The quantum dot layer 60 functions as a layer that converts the wavelength of transmitted light. That is, the quantum dot layer 60 converts the wavelength of light from the light emitter 25 to a different wavelength even when the light source 24 has only the light emitter 25 that emits light in a single wavelength region. Therefore, the surface light source device 20 can emit light in a color different from the light emitted from the light emitter 25 of the light source 24.

  As illustrated in FIG. 2, the quantum dot layer 60 described here includes a binder resin 62 and quantum dots 61 dispersed in the binder resin 62. The quantum dot 61 is a semiconductor particle of a predetermined size having a quantum confinement effect. When the quantum dot 61 absorbs light from the excitation source and reaches an energy excitation state, the quantum dot 61 releases energy corresponding to the energy band gap of the quantum dot 61. Therefore, by adjusting the size of the quantum dots 61 or the composition of the substance, the energy band gap can be adjusted, and energy in various levels of wavelength bands can be obtained. In particular, the quantum dot 61 can generate strong fluorescence in a narrow wavelength band.

  Therefore, even when the light source 24 has only the light emitter 25 that emits light in a single wavelength region, the use of the quantum dots 61 allows various types including red, green, and blue due to the quantum size effect. Can be easily obtained. For example, when the size of the quantum dot is 5.5 to 6.5 nm (nanometer), a red color is emitted. When the size of the quantum dot is 4.0 to 5.0 nm, a green color is emitted. When the size of the quantum dot is 2.0 to 3.5 nm, a blue color is emitted, and yellow has an intermediate size between a quantum dot emitting red and a quantum dot emitting green.

  When the light projected from the light emitter 25 is blue light, the quantum dot layer 60 can include red quantum dots and green quantum dots. The red quantum dots in the quantum dot layer 60 convert part of the blue light into red light having a wavelength range of 620 to 750 nm, and the green quantum dots have a part of blue light having a wavelength range of 495 to 570 nm. Convert to green light. And the blue light which is not converted into red light and green light permeate | transmits the quantum dot layer 60 as it is. According to this example, illumination with white light using the surface light source device 20 can be realized by mixing blue light, red light, and green light. In particular, the quantum dot 61 can generate strong fluorescence in a desired narrow wavelength region. For this reason, the surface light source device 20 can illuminate the liquid crystal display panel 15 with light of three primary colors having excellent color purity. In this case, the liquid crystal display panel 15 has excellent color reproducibility.

  The quantum dot 61 can be composed of a central body having a size of about 2 to 10 nm and a shell made of ZnS (zinc sulfide). Usually, since the polymer coating is applied to the outer surface of the shell, the quantum dots 61 are nanoparticles having a size of 10 to 15 nm. As the central body of the quantum dot 61, CdSe (cadmium selenide), CdTe (cadmium telluride), CdS (cadmium sulfide) can be used. On the other hand, the binder resin 62 may be composed of a silicon resin, an epoxy resin, and an acrylic resin, either singly or in combination.

  However, the quantum dot layer 60 is likely to deteriorate due to moisture and oxygen in the atmosphere and cause a decrease in luminous efficiency. Therefore, in the present embodiment, the barrier layer 85 covers the quantum dot layer 60 in order to protect the surface of the quantum dot layer 60 opposite to the surface bonded to the low refractive index layer 80. The barrier layer 85 shown in FIG. 2 is bonded to the surface opposite to the surface bonded to the low refractive index layer 80 of the quantum dot layer 60, and covers the entire area of the surface without any gap. The barrier layer 85 is a layer disposed on the most liquid crystal display panel 15 side of the light guide member 22. Therefore, the surface of the barrier layer 85 facing the liquid crystal display panel 15 side defines the light emitting surface 22 a of the light guide member 22.

  The barrier layer 85 has a function of protecting the quantum dot layer 60 from moisture and oxygen. That is, the barrier layer 85 has a vapor barrier property that prevents the permeation of water vapor and a gas barrier property that prevents the permeation of gas such as oxygen gas.

  The barrier layer 85 may be a material having a function of blocking moisture and oxygen, and examples thereof include organic polymers such as polyethylene terephthalate or oxides such as silicon oxide, titanium oxide, and aluminum oxide.

  Thus, one surface of the quantum dot layer 60 is protected from moisture and oxygen by the barrier layer 85. The other surface of the quantum dot layer 60 also needs to be protected from moisture and oxygen. However, when the other surface of the quantum dot layer 60 is protected by another barrier layer, the thickness increases, so that it can be used as a mobile device. Will reduce the attractiveness of. Therefore, in the present embodiment, the other surface of the quantum dot layer 60 is protected from moisture and oxygen by making the light guide plate 30 made of glass. That is, the glass-made light guide plate 30 is excellent in vapor barrier properties and gas barrier properties, so that moisture and oxygen are hardly transmitted from the back surface 32 to the light exit surface 31 of the light guide plate 30. As a result, it is possible to prevent moisture and oxygen from reaching the other surface of the quantum dot layer 60 via the light guide plate 30 and the low refractive index layer 80.

  As the glass material forming the light guide plate 30, silicate glass is typically used, but any material can be used as long as it can be stretch-molded, such as soda glass, borosilicate glass, aluminum silicate glass, and silica glass. Can also be used. Further, as the glass material forming the light guide plate 30, crystallized glass that can be stretch-molded can also be used. Crystallized glass is excellent in that it imparts heat resistance to the light guide member 22.

  Further, the material forming the low refractive index layer 80 bonded to the light output surface 31 of the light guide plate 30 is not particularly limited as long as the material has a lower refractive index than the material forming the light guide plate 30, but as an example, a display device Widely used as a material for optical sheets to be incorporated in, and from the viewpoint of having excellent mechanical properties, optical properties, stability and processability and being available at low cost, acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, poly A transparent resin mainly composed of one or more of acrylonitrile and the like can be suitably used.

  Next, the first prism sheet 71 and the second prism sheet 72 provided on the light output side of the light guide member 22 will be described with reference to FIGS. 3 and 4. 3 and 4 are a perspective view and a sectional view showing the prism sheets 71 and 72, respectively.

  The first prism sheet 71 and the second prism sheet 72 have a function of adjusting the luminance distribution by changing the traveling direction of the transmitted light. The illustrated first prism sheet 71 and second prism sheet 72 change the traveling direction of the light incident from the light incident side and emit the light from the light output side so as to intensively improve the luminance in the front direction (condensing function). )have. The first prism sheet 71 and the second prism sheet 72 are different in arrangement and can have the same configuration. Therefore, the description common to the first prism sheet 71 and the second prism sheet 72 will be described using the reference numerals “71, 72” without distinguishing between “first” and “second”. Hereinafter, the configuration of each component will be described.

  As shown in FIG. 3 and FIG. 4, the prism sheets 71 and 72 are arranged in a sheet-like main body 73 and a light emitting side surface of the main body 73 arranged in a direction (arrangement direction) parallel to the sheet surface of the main body 73. And a large number of unit prisms 75 arranged on 73a.

  The “unit prism” in the present specification refers to an element having a function of changing the traveling direction of the light by exerting an optical action such as refraction or reflection on the light, and the “unit shape element”. , Also called “unit optical element” and “unit lens”.

  The main body 73 functions as a sheet-like member that supports the unit prism 75. As shown in FIGS. 3 and 4, in the present embodiment, unit prisms 75 are arranged on the light output side surface 73 a of the main body 73 without a gap. Therefore, the light exit side surface 70 a of the prism sheets 71 and 72 is formed by the two prism surfaces 76 of the unit prism 75. On the other hand, as shown in FIG. 4, the main body 73 has a smooth surface that forms the light incident side surface 70b of the prism sheets 71 and 72 as the light incident side surface 73b facing the light output side surface 73a.

  As described above, the unit prisms 75 are arranged side by side on the light exit side surface 73 a of the main body 73. As shown in FIG. 4, the unit prism 75 extends linearly in a direction intersecting with the arrangement direction da of the unit prisms 75, more specifically in a direction orthogonal thereto. In the cross section shown in FIG. 4, the cross sectional shape of each unit prism 75 is a substantially triangular shape protruding toward the light output side.

  As can be understood from FIGS. 1 and 2, the arrangement direction of the first prism sheet 71 and the arrangement direction of the unit prisms 45 of the second prism sheet 72 intersect, more specifically, are orthogonal. When the prism sheets 71 and 72 are observed from the front direction nd, the longitudinal direction db of the unit prism 75 of the first prism sheet 71 is parallel to the second direction d2, and the unit prism 75 of the second prism sheet 72 The longitudinal direction db is parallel to the first direction d1.

  The prism sheets 71 and 72 having the above-described configuration can be manufactured by molding the unit prism 75 on a base material or by extrusion molding. Various materials can be used as the material constituting the main body 73 and the unit prism 75 of the unit prism 75, and for example, one or more of acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, polyacrylonitrile, or the like is a main component. Transparent resins, epoxy acrylate and urethane acrylate-based reactive resins (such as ionizing radiation curable resins) can be suitably used.

  Next, the operation of the display device 10 and the surface light source device 20 configured as described above will be described.

  First, as shown in FIG. 2, the light emitter 25 that forms the light source 24 emits light. In the present embodiment, corresponding to the provision of the quantum dot layer 60, the light emitter 25 emits only light in the blue wavelength region. The light emitted from the light emitter 25 enters the light guide plate 30 through the light incident surface 33. As shown in FIG. 2, the lights L <b> 21 and L <b> 22 that have entered the light guide plate 30 are repeatedly reflected on the light exit surface 31 and the back surface 32 of the light guide plate 30, thereby connecting the light incident surface 33 and the opposite surface 34 of the light guide plate 30. It proceeds in the first direction (light guide direction) d1.

  FIG. 5 shows how light is extracted from the light guide member 22. As described above, the extraction element 40 that diffuses and reflects the guided light is arranged on the back surface 32 of the light guide plate 30. As shown in FIG. 5, when the light L <b> 22 guided through the light guide plate 30 enters the extraction element 40, it is diffusely reflected by the extraction element 40 and travels in various directions. Part of the light L221 diffusely reflected by the extraction element 40 has an incident angle on the light output surface 31 that is equal to or greater than the total reflection critical angle, and is totally reflected again by the light output surface 31 and returns to the back surface 32. On the other hand, another part L222 of the light diffusely reflected by the extraction element 40 has an incident angle on the light exit surface 31 that is less than the total reflection critical angle, and passes through the light exit surface 31.

  On the other hand, when the light L21 guided in the light guide plate 30 is incident on the region 32b other than the region 32a of the back surface 32 where the extraction element 40 is disposed, the light L21 is totally reflected in the region 32b, and thereafter The incident angle to the incident light exit surface 31 is also maintained. Therefore, the light L21 totally reflected by the region 32b other than the region 32a where the extraction element 40 is disposed on the back surface 32 is then totally reflected by the light exit surface 31 and guided toward the opposite surface 34. .

  In particular, in the illustrated example, as the distance from the incident surface 33 to the opposite surface 34 approaches the opposite direction 34 along the first direction d1 that is the light guide direction, the proportion of the region 32a in which the extraction element 40 is arranged in the back surface 32 is increased. It is high. This ensures a sufficient amount of light emitted from the light exit surface 31 of the light guide plate 30 in a region separated from the light incident surface 33 where the amount of emitted light tends to decrease, and the amount of emitted light uniform along the light guide direction. Can be achieved.

  The light L222 emitted from the light guide plate 30 then enters the quantum dot layer 60. The quantum dot layer 60 includes quantum dots 61 that can function as a fluorescent material. Therefore, the quantum dot layer 60 functions as a color conversion layer that converts the wavelength of light from the light source 24. Specifically, the quantum dot layer 60 converts a part of blue light into red light having a wavelength range of 620 to 750 nm in response to only light in the blue wavelength range being emitted from the light source 24. The quantum dot and the green quantum dot which converts a part of blue light into the green light which has a wavelength range of 495-570 nm are included. Therefore, part of the blue light transmitted through the quantum dot layer 60 is converted to green light, and the other part of the blue light is converted to red light, while the quantum dots 61 convert the light into red light and green light. Blue light that is not converted passes through the quantum dot layer 60 as it is.

  The light L222 emitted from the light guide plate 30 is light that travels mainly in a direction greatly inclined from the front direction nd. Since the quantum dots 61 included in the quantum dot layer 60 absorb the incident light L222 and emit light of different wavelengths, the light emitted from the quantum dots 61 is not only in a direction greatly inclined from the front direction nd. It spreads in various directions without deviation.

  In the present embodiment, the quantum dot layer 60 has a light diffusing function, for example, by mixing light diffusing particles. Incidence probability of light passing through the quantum dot layer 60 to the quantum dots 61 is significantly increased by being diffused inside the quantum dot layer 60.

  As described above, the blue, green, and red light transmitted through the quantum dot layer 60 travels to the prism sheets 71 and 72 disposed on the light output side of the quantum dot layer 60. As shown in FIG. 4, the light beams L <b> 71 and L <b> 72 that pass through the prism sheets 71 and 72 are refracted by the prism surface 76 of the unit prism 75. Due to this refraction, the traveling direction (outgoing direction) of the lights L71 and L72 traveling in the direction inclined from the front direction nd is mainly compared to the traveling direction of the light when entering the prism sheets 71 and 72. 71 and 72 are bent toward the side where the angle with respect to the normal direction to the sheet surface becomes smaller. By such an action, the unit prism 75 can narrow the traveling direction of the transmitted light to the front direction nd side. As a result, the luminance in the front direction can be effectively improved.

  The light condensing function by the unit prism 75 is mainly exhibited in the arrangement direction of the unit prisms 75 (left and right direction in FIG. 5) da. The arrangement direction of the unit prisms 75 of the first prism sheet 71 is not parallel to the arrangement direction of the unit prisms 75 of the second prism sheet 72, and is particularly orthogonal. Therefore, the emission direction of the light transmitted through the two prism sheets 71 and 72 is narrowed down within a narrow angle range centering on the front direction in two different directions.

  As understood from FIG. 1, the light emitted from the second prism sheet 72 that forms the light emitting surface 21 of the surface light source device 20 is then incident on the liquid crystal display panel 15 and the lower polarization through the brightness enhancement layer 11. It passes through the plate 14. The light transmitted through the lower polarizing plate 14 selectively passes through the upper polarizing plate 13 according to the state of electric field application to each pixel. In this manner, the liquid crystal display panel 15 selectively transmits light from the surface light source device 20 for each pixel, so that an observer of the liquid crystal display device 10 can observe an image.

  As described above, according to the present embodiment, the light exit surface 31 and the light guide surface 30 made of glass having the light entrance surface 33 facing in a direction different from the light exit surface 31 and the light exit surface 31 of the light guide plate 30 are provided. A low-refractive index layer 80 having a lower refractive index than that of the light guide plate 30, and a quantum dot layer including a quantum dot 61 that is bonded to a surface opposite to the surface of the low refractive index layer 80 that is bonded to the light guide plate 30. 60 and a barrier layer 85 that covers the surface of the quantum dot layer 60 opposite to the surface bonded to the low refractive index layer 80. According to such a form, the light extracted uniformly from the light exit surface 31 of the light guide plate 30 is absorbed by the quantum dots 61 and emitted as light of different wavelengths. The light emitted from the quantum dots 61 can illuminate the liquid crystal display panel 15 with excellent color purity. As a result, the liquid crystal display panel 15 can display an image with excellent color reproducibility.

  However, the quantum dot layer 60 is likely to deteriorate due to moisture and oxygen in the atmosphere and cause a decrease in luminous efficiency. In this regard, according to the present embodiment, the quantum dot layer 60 is sandwiched between the light guide plate 30 made of glass and the barrier layer 85 having a function of preventing the transmission of moisture and oxygen. Therefore, the quantum dot layer 60 can be protected from moisture and oxygen by sandwiching the quantum dot layer 60 between the glass light guide plate 30 and the barrier layer 85. That is, it is not necessary to prepare a separate barrier layer for the quantum dot layer 60 by using the light guide plate 30 made of glass as a barrier layer for the quantum dot layer 60. As a result, the total thickness of the light guide member 22 can be reduced. From the above, according to the present embodiment, the light guide member 22 in which the quantum dot layer 60 is incorporated can be realized in a mode excellent in practicality that achieves both high color reproducibility and thinning. .

  In addition, according to the present embodiment, the light guide plate 30 includes the back surface 32 facing the light output surface 31 and in which a plurality of extraction elements 40 are arranged in a pattern, and the extraction element 40 is light incident from a certain direction dx. At least a part of L22 is directed in a direction dz different from the direction dy in which the light L21 incident on the region 32b other than the region 32a of the back surface 32 other than the region 32a in the rear surface 32 is reflected. Dodge (see FIG. 2). According to such a form, the extraction element 40 for extracting the light guided through the light guide plate 30 can be realized in a practical manner.

  Note that various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above-described embodiment are used for the parts that can be configured in the same manner as in the above-described embodiment, and overlapping. Description to be omitted is omitted.

  In the above-described embodiment, the example in which the light exit surface 31 of the light guide plate 30 is a flat surface has been described. However, the present invention is not limited to such an example. For example, a plurality of prism elements that adjust the direction of outgoing light may be arranged on the light outgoing surface 31 of the light guide plate 30.

  In the above-described embodiment, the example in which the display device 10 includes the brightness enhancement layer 11 and the two prism sheets 71 and 72 has been described. However, these may be appropriately provided according to specifications. That is, the brightness enhancement layer 11 and the prism sheets 71 and 72 may not be provided.

  In the above-described embodiment, as shown in FIG. 2, the example in which the extraction element 40 is made of white ink having a diffuse reflection function is shown, but the form of the extraction element 40 is not limited to such an example. FIG. 6 shows another example of the extraction element 40. In the example illustrated in FIG. 6, the plurality of extraction elements 40 includes a plurality of inclined surfaces 40 arranged in the first direction d1 that is the light guide direction. In the example shown in FIG. 6, the plurality of inclined surfaces 40 are arranged at intervals in the first direction d <b> 1 and extend in the plate surface of the light guide plate 30 in the direction orthogonal to the first direction d <b> 1, more specifically in the orthogonal direction. ing.

  In the example shown in FIG. 6, the inclined surface 40 approaches the light exit surface 31 along the front direction nd from the light incident surface 33 side toward the opposite surface 34 side. Inclined against both. That is, the inclined surface 40 has both the front direction nd and the first direction d1 so that the end E1 located on the opposite surface 34 side is closer to the light exit surface 31 than the end E2 located on the light incident surface 33 side. It is inclined with respect to.

  According to the inclined surface 40 as such an extraction element, in the light 32 that repeatedly reflects between the light output surface 31 and the back surface 32, in the region 32 b other than the region 32 a of the back surface 32 where the extraction element 40 is disposed. With respect to the reflected light, the incident angle at the time of subsequent incidence on the light exit surface 31 is maintained, and the light reflected on the region 32a of the back surface 32 where the extraction element 40 is disposed is subsequently incident on the light exit surface 31. The incident angle when doing so becomes smaller. When the incident angle on the light exit surface 31 becomes less than the total reflection critical angle due to reflection on the inclined surface 40, the light is emitted from the light guide plate 30.

  Although not specifically mentioned in the above-described embodiment, the side surface 60c of the quantum dot pattern layer 60 may be exposed to the outside or may be protected. FIG. 7 shows an example in which the side surface of the quantum dot layer 60 is protected by the side barrier material 86. As shown in FIG. 7, the quantum dot layer 60 includes an entrance surface 60a joined to the low refractive index layer 80, an exit surface 60b covered with a barrier layer 85, an outer edge of the entrance surface 60a, and an exit surface 60b. And a side surface 60c extending between the outer edges. The side barrier material 86 is bonded to the side surface 60c of the quantum dot layer 60 and covers the entire side surface 60c.

  The side barrier material 86 has a function of protecting the quantum dot layer 60 from moisture and oxygen. In other words, the side barrier material 86 has a vapor barrier property that prevents the permeation of water vapor and a gas barrier property that prevents the permeation of gas such as oxygen gas. Since the composition of the side barrier material 86 can be configured in substantially the same manner as the barrier layer 85 described above, detailed description thereof is omitted here.

  According to the embodiment shown in FIG. 7, the side barrier material 86 can protect the side surface 60 c of the quantum dot layer 60 from moisture and oxygen, and thus further suppresses a decrease in power generation efficiency of the quantum dot layer 60 due to moisture and oxygen. can do.

<< Second Embodiment >>
Next, a second embodiment will be described with reference to FIG. FIG. 8 is a cross-sectional view illustrating a schematic configuration of the surface light source device 20 according to the second embodiment. The second embodiment described with reference to FIG. 8 is different in that the arrangement of the low refractive index layer 80 and the extraction element 40 are not provided, but the other configurations are the same as in the first embodiment. Can be configured. In the following description of the second embodiment and the drawings used in the following description, the parts that can be configured in the same manner as in the first embodiment described above are the same as the corresponding parts in the first embodiment described above. The same reference numerals as those used above will be used, and redundant explanation will be omitted.

  In the surface light source device 20 shown in FIG. 8, the low refractive index layer is configured as a low refractive index pattern layer 80 arranged in a pattern on the light exit surface 31 of the light guide plate 30. The low refractive index pattern layer 80 is made of a material having a lower refractive index than the material forming the light guide plate 30. The low refractive index pattern layer 80 is bonded to the light exit surface 31 of the light guide plate 30 and partially covers the light exit surface 31 without a gap. An interface having a difference in refractive index is formed between the low refractive index pattern layer 80 and the portion of the light exit surface 31 of the light guide plate 30 covered with the low refractive index pattern layer 80. This interface acts to reflect the light guided through the light guide plate 30 and guide it toward the opposite surface 34. That is, when light guided through the light guide plate 30 enters the interface with the low refractive index pattern layer 80, the light is totally reflected at the interface and travels toward the back surface 32.

  In the present embodiment, the low refractive index pattern layer 80 includes a plurality of low refractive unit elements 81 arranged at intervals in the first direction d1 that is the light guide direction. Each low-refractive unit element 81 extends along the light exit surface 31 in a direction that intersects the first direction d1, more specifically, in the orthogonal direction.

  In particular, in the present embodiment, the plurality of low-refractive unit elements 81 are arranged at a constant pitch along the first direction d1, and are arranged close to the opposite surface 34 along the first direction d1. The lower the refractive index unit element 81, the shorter the length along the first direction d1. Therefore, as the incident surface 33 approaches the opposite surface 34 along the first direction d1, the proportion of the region of the light exit surface 31 in which the low refraction unit element 81 is disposed decreases. According to such a configuration, emission of light from the light guide plate 30 in a region separated from the incident surface 33 along the light guide direction is promoted, and the amount of emitted light decreases as the distance from the incident surface 33 increases. Can be effectively prevented.

  The quantum dot layer 60 is bonded to the light exit surface 31 of the light guide plate 30 on which the low refractive index pattern layer 80 is disposed. In the present embodiment, the quantum dot layer 60 covers the light exit surface 31 of the light guide plate 30 on which the low refractive index pattern layer 80 is disposed. For this reason, the quantum dot layer 60 is also filled between the low refractive unit elements 81 adjacent in the first direction d <b> 1 and is in contact with a part of the light exit surface 31 of the light guide plate 30. In the present embodiment, the refractive index of the quantum dot layer 60 is larger than the refractive index of the low refractive index pattern layer 80 and is substantially the same as the refractive index of the light guide plate 30. Therefore, when light guided through the light guide plate 30 enters the interface with the quantum dot layer 60, the light passes through the interface and enters the quantum dot layer 60.

  A surface of the quantum dot layer 60 opposite to the surface bonded to the light exit surface 31 is covered with a barrier layer 85. The barrier layer 85 shown in FIG. 8 is bonded to the surface of the quantum dot layer 60 opposite to the surface bonded to the light exit surface 31, and covers the entire area of the surface without a gap.

  FIG. 9 shows how light is extracted from the light guide member 22. As shown in FIG. 9, when the light L91 guided in the light guide plate 30 enters the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31, it is totally reflected in the region 31a. The incident angle to the back surface 32 incident thereafter is also maintained. Therefore, the light L91 totally reflected by the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31 is then totally reflected by the back surface 32 and guided toward the opposite surface 34.

  On the other hand, when the light L92 guided through the light guide plate 30 enters the region 31b of the light exit surface 31 covered with the quantum dot layer 60, the light L92 passes through the region 31b and enters the quantum dot layer 60. Enter. In this way, the lights L91 and L92 from the light source 24 are extracted uniformly from the light output surface 31 of the light guide plate 30.

  The light L92 incident on the quantum dot layer 60 is absorbed by the quantum dots 61 and emitted as light of different wavelengths. Thereafter, the emitted light passes through the two prism sheets 71 and 72 and illuminates the liquid crystal display panel 15.

  As described above, according to the present embodiment, the light guide plate 30 having the light exit surface 31 and the light entrance surface 33 facing in a different direction from the light exit surface 31 and the light exit surface 31 of the light guide plate 30 are arranged in a pattern. A low refractive index pattern layer 80 having a refractive index lower than that of the light guide plate 30; a quantum dot layer 60 including the quantum dots 61 that is bonded to the light exit surface 31 of the light guide plate 30 on which the low refractive index pattern layer 80 is disposed; A barrier layer 85 that covers a surface of the dot layer 60 opposite to the surface bonded to the light guide plate 30. According to such a form, when the light L91 guided through the light guide plate 30 enters the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31, it is totally reflected by the region 31a. The incident angle to the back surface 32 incident thereafter is also maintained. Therefore, the light L91 totally reflected by the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31 is then totally reflected by the back surface 32 and guided toward the opposite surface 34. On the other hand, when the light L92 guided through the light guide plate 30 enters the region 31b of the light exit surface 31 covered with the quantum dot layer 60, the light L92 passes through the region 31b and enters the quantum dot layer 60. Enter. In this way, the lights L91 and L92 from the light source 24 are extracted uniformly from the light output surface 31 of the light guide plate 30.

  The light L92 extracted uniformly from the light exit surface 31 of the light guide plate 30 is absorbed by the quantum dots 61 and emitted as light of different wavelengths. The light emitted from the quantum dots 61 can illuminate the liquid crystal display panel 15 with excellent color purity. As a result, the liquid crystal display panel 15 can display an image with excellent color reproducibility. From the above, according to the present embodiment, the light guide member 22 in which the quantum dot layer 60 is incorporated can be realized in a mode excellent in practicality that achieves both high color reproducibility and thinning. .

  Further, according to the present embodiment, the light guide plate 30 is made of glass. Therefore, the quantum dot layer 60 is sandwiched between the glass light guide plate 30 and the barrier layer 85. Since the glass-made light guide plate 30 and the barrier layer 85 prevent moisture and oxygen from being transmitted, the quantum dot layer 60 is sandwiched between the glass-made light guide plate 30 and the barrier layer 85 so that the quantum dot layer 60 is formed. Can be protected from moisture and oxygen. That is, by using the light guide plate 30 made of glass as a barrier layer for the quantum dot layer 60, it is not necessary to prepare a separate barrier layer for the quantum dot layer 60, and the total thickness of the light guide member 22 is reduced. Can do.

<< Third Embodiment >>
Next, a third embodiment will be described with reference to FIG. FIG. 10 is a cross-sectional view showing a schematic configuration of the surface light source device 20 according to the third embodiment. The third embodiment described with reference to FIG. 10 is different from the arrangement of the low refractive index layer 80 and the quantum dot layer 60 in that the extraction element 40 is not provided. It can be configured similarly to the embodiment. In the following description of the third embodiment and the drawings used in the following description, parts that can be configured in the same manner as in the above-described first embodiment will be described with respect to corresponding parts in the above-described first embodiment. The same reference numerals as those used above will be used, and redundant explanation will be omitted.

  In the surface light source device 20 shown in FIG. 10, the quantum dot layer 60 is configured as a quantum dot pattern layer 60 arranged in a pattern on the light exit surface 31 of the light guide plate 30. The quantum dot pattern layer 60 is made of a material having substantially the same refractive index as the material forming the light guide plate 30. The quantum dot pattern layer 60 is bonded to the light exit surface 31 of the light guide plate 30 and partially covers the light exit surface 31 without a gap.

  In the present embodiment, the quantum dot pattern layer 60 includes a plurality of quantum dot unit elements 63 arranged at intervals in the first direction d1 that is the light guide direction. Each quantum dot unit element 63 extends along the light exit surface 31 in a direction that intersects the first direction d1, more specifically in the orthogonal direction.

  In particular, in the present embodiment, the plurality of quantum dot unit elements 63 are arranged at a constant pitch along the first direction d1, while being arranged close to the opposite surface 34 along the first direction d1. The longer the quantum dot unit element 63 is, the longer the length along the first direction d1 tends to be. Therefore, as the distance from the incident surface 33 to the opposite surface 34 approaches the first direction d1, the ratio of the region where the quantum dot unit elements 63 are arranged in the light exit surface 31 increases. According to such a configuration, emission of light from the light guide plate 30 in a region separated from the incident surface 33 along the light guide direction is promoted, and the amount of emitted light decreases as the distance from the incident surface 33 increases. Can be effectively prevented.

  A low refractive index pattern layer 80 is bonded to the light exit surface 31 of the light guide plate 30 on which the quantum dot pattern layer 60 is disposed. In the present embodiment, the low refractive index pattern layer 80 covers the light exit surface 31 of the light guide plate 30 on which the quantum dot pattern layer 60 is disposed. For this reason, the low refractive index pattern layer 80 is also filled between the quantum dot unit elements 63 adjacent in the first direction d1 and is in contact with a part of the light exit surface 31 of the light guide plate 30. In the present embodiment, the refractive index of the low refractive index pattern layer 80 is smaller than the refractive indexes of the light guide plate 30 and the quantum dot pattern layer 60. Therefore, an interface having a difference in refractive index is formed between the low refractive index pattern layer 80 and the portion of the light exit surface 31 of the light guide plate 30 adjacent to the low refractive index pattern layer 80. This interface acts to reflect the light guided through the light guide plate 30 and guide it toward the opposite surface 34. That is, when light guided through the light guide plate 30 enters the interface with the low refractive index pattern layer 80, the light is totally reflected at the interface and travels toward the back surface 32.

  In particular, in the present embodiment, the low refractive index pattern layer 80 also functions as a barrier layer for the quantum dot layer 60. That is, the low refractive index pattern layer 80 has a function of protecting the quantum dot layer 60 from moisture and oxygen. In other words, the low-refractive index pattern layer 80 has a vapor barrier property that prevents the transmission of water vapor and a gas barrier property that prevents the transmission of gas such as oxygen gas.

  Such a low refractive index pattern layer 80 can be obtained by appropriately adding a component for adjusting the refractive index with the material constituting the barrier layer 85 described in the first embodiment as a main component.

  FIG. 11 shows how light is extracted from the light guide member 22. As shown in FIG. 11, when the light L11 guided in the light guide plate 30 enters the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31, it is totally reflected in the region 31a. The incident angle to the back surface 32 incident thereafter is also maintained. Therefore, the light L11 totally reflected by the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31 is then totally reflected by the back surface 32 and guided toward the opposite surface 34.

  On the other hand, when the light L12 guided through the light guide plate 30 enters the region 31b of the light exit surface 31 covered with the quantum dot layer 60, the light L12 passes through the region 31b and enters the quantum dot layer 60. Enter. In this way, the lights L11 and L12 from the light source 24 are uniformly extracted from the light output surface 31 of the light guide plate 30.

  Lights L11 and L12 incident on the quantum dot layer 60 are absorbed by the quantum dots 61 and emitted as light of different wavelengths. Thereafter, the emitted light passes through the two prism sheets 71 and 72 and illuminates the liquid crystal display panel 15.

  As described above, according to the present embodiment, the light guide plate 30 having the light exit surface 31 and the light entrance surface 33 facing in a different direction from the light exit surface 31 and the light exit surface 31 of the light guide plate 30 are arranged in a pattern. A quantum dot pattern layer 60 including quantum dots 61, and a low refractive index layer 80 having a lower refractive index than the light guide plate 30 and covering the light exit surface 31 of the light guide plate 30 on which the quantum dot pattern layer 60 is disposed. . According to such a form, when the light L11 guided in the light guide plate 30 enters the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31, it is totally reflected by the region 31a. The incident angle to the back surface 32 incident thereafter is also maintained. Therefore, the light L11 totally reflected by the region 31a covered by the low refractive index pattern layer 80 in the light exit surface 31 is then totally reflected by the back surface 32 and guided toward the opposite surface 34. On the other hand, when the light L12 guided through the light guide plate 30 enters the region 31b of the light exit surface 31 covered with the quantum dot layer 60, the light L12 passes through the region 31b and enters the quantum dot layer 60. Enter. In this way, the lights L11 and L12 from the light source 24 are uniformly extracted from the light output surface 31 of the light guide plate 30.

  Lights L11 and L12 that are uniformly extracted from the light exit surface 31 of the light guide plate 30 are absorbed by the quantum dots 61 and emitted as light of different wavelengths. The light emitted from the quantum dots 61 can illuminate the liquid crystal display panel 15 with excellent color purity. As a result, the liquid crystal display panel 15 can display an image with excellent color reproducibility. From the above, according to the present embodiment, the light guide member 22 in which the quantum dot layer 60 is incorporated can be realized in a mode excellent in practicality that achieves both high color reproducibility and thinning. .

  Further, according to the present embodiment, the low refractive index layer 80 also functions as a barrier layer for the quantum dot pattern layer 60, and the light guide plate 30 is made of glass. Therefore, the quantum dot layer 60 is sandwiched between the light guide plate 30 made of glass and the low refractive index layer 80 having a barrier function. Since the light guide plate 30 and the low refractive index layer 80 made of glass hinder the transmission of moisture and oxygen, the quantum dot layer 60 is sandwiched between the light guide plate 30 made of glass and the low refractive index layer 80 so that the quantum The dot layer 60 can be protected from moisture and oxygen. That is, by using the light guide plate 30 made of glass and the low refractive index layer 80 as a barrier layer for the quantum dot layer 60, it is not necessary to prepare a separate barrier layer for the quantum dot layer 60, and the total of the light guide members 22 is eliminated. The thickness can be reduced.

  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.

DESCRIPTION OF SYMBOLS 10 Display apparatus 10a Display surface 15 Liquid crystal display panel 20 Surface light source device 21 Light emission surface 22 Light guide member 24 Light source 25 Light emitter 30 Light guide plate 31 Light emission surface 32 Back surface 33 Light incident surface 34 Opposite surface 40 Extraction element 60 Quantum dot layer, quantum Dot pattern layer 61 Quantum dot 62 Binder resin 80 Low refractive index layer, low refractive index pattern layer 85 Barrier layer 86 Side barrier material

Claims (8)

A light guide plate made of glass having a light exit surface and a light entrance surface facing a direction different from the light exit surface;
A low refractive index layer bonded to the light exit surface of the light guide plate and having a lower refractive index than the light guide plate;
A quantum dot layer including a quantum dot bonded to a surface opposite to the surface bonded to the light guide plate of the low refractive index layer;
A barrier layer that covers a surface of the quantum dot layer opposite to a surface bonded to the low refractive index layer;
A light guide member. The light guide plate includes a back surface facing the light exit surface and a plurality of extraction elements arranged in a pattern,
The extraction element has a direction in which at least a part of light incident from a certain direction is reflected and directed to a region of the back surface other than the region where the extraction element is disposed. The light guide member according to claim 1, wherein the light guide members are directed in different directions. A light guide plate having a light exit surface and a light entrance surface facing a direction different from the light exit surface;
A low-refractive-index pattern layer that is patterned on the light exit surface of the light guide plate and has a lower refractive index than the light guide plate;
A quantum dot layer including quantum dots bonded to the light exit surface of the light guide plate in which the low refractive index pattern layer is disposed;
A barrier layer covering a surface opposite to the surface bonded to the light guide plate of the quantum dot layer;
A light guide member. A light guide plate having a light exit surface and a light entrance surface facing a direction different from the light exit surface;
A quantum dot pattern layer that is arranged in a pattern on the light exit surface of the light guide plate and includes quantum dots;
A low refractive index layer having a refractive index lower than that of the light guide plate, covering the light output surface of the light guide plate in which the quantum dot pattern layer is disposed;
A light guide member.   The light guide member according to claim 4, wherein the low refractive index layer also functions as a barrier layer for the quantum dot pattern layer.   The light guide member according to claim 3, wherein the light guide plate is made of glass. The light guide member according to any one of claims 1 to 6,
A surface light source device, comprising: a light source disposed opposite to the light incident surface of the light guide member. A surface light source device according to claim 7;
A display device, comprising: a display panel disposed to face the surface light source device.

Images