JP2016194986A - Backlight device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight device and a display device capable of preventing hue of a peripheral edge portion of a light emission region from being distinctive in comparison with hue of a central portion in light emission.SOLUTION: A quantum dot sheet has a light incident face 50A receiving light from a light source, and a light emission face 50B positioned at a side opposite to the light incident face 50A, and includes quantum dots 56 and a binder resin 57. At least a part of the light L1 from the light source incident by a reflector disposed along at least a part of a peripheral edge portion of the quantum dot sheet, is reflected to at least one of an incident face 50A side and a light emission face 50B side of the quantum dot sheet through which a part of the light L1 from the light source incident to the quantum dot sheet is transmitted, and in which another part of the light L1 from the light source is converted into light of a wavelength different from the light from the light source by the quantum dots 56, so that the light L1 from the light source transmitted through the quantum dot sheet and the wavelength-converted light L2 are emitted from the light emission face 50B.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a backlight device and a display device.

  2. Description of the Related Art A transmissive image display device such as a liquid crystal display device generally includes a backlight device that is disposed on the back side of a transmissive image display panel such as a liquid crystal display panel and illuminates the transmissive image display panel. As the backlight device, an edge light type or a direct type backlight device is known.

  Currently, in order to improve color reproducibility, it has been studied to incorporate quantum dots into a backlight device (see Patent Document 1). Quantum dots 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, a backlight device incorporating quantum dots can reproduce various colors while using a light source that projects light in a single wavelength region. For example, when a light source that emits blue light is used, the quantum dot sheet can absorb blue light and emit green light and red light. Since such a backlight device is excellent in color purity, a display device using this backlight device has excellent color reproducibility.

JP 2013-218953 A

  As a method of incorporating quantum dots into a backlight device, an on-chip method of incorporating quantum dots in a light source, an on-edge method of arranging a transparent tube containing quantum dots between a light source and a light guide plate, and a light output side of the light guide plate An on-surface method is also known in which a sheet containing quantum dots is arranged on a light source.

  However, in the on-chip method, since the quantum dots are incorporated in the light source, the quantum dots are exposed to a high temperature, and the conversion efficiency of the quantum dots is inferior. In the on-edge method, the transparent tube containing the quantum dots is disposed between the light source and the light guide plate, so that the size increases. In particular, in mobile devices, miniaturization is required, so it is difficult to cope with the on-edge method.

  On the other hand, the on-surface method does not have the above-mentioned problem, and it is also possible to use a conventionally used backlight device. For this reason, it is currently considered to incorporate quantum dots into the backlight device by the on-surface method. However, in the on-surface method, the light source emits light from the light source at the periphery of the light-emitting area of the backlight device. There is a problem that the color of emitted light appears stronger than the central portion of the light emitting region. This phenomenon becomes more prominent when a light emitting material having a small size (nm size) such as a quantum dot is used. For example, when a light source that emits blue light is used as the light source, the peripheral portion of the light emitting region of the backlight device appears more bluish than the central portion of the light emitting region (blueing).

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a backlight device and a display device that can suppress the color of the peripheral portion of the light emitting region from being noticeable when compared with the color of the central portion of the light emitting region.

  According to one aspect of the present invention, a quantum source comprising a light source, a light incident surface that receives light from the light source, and a light exit surface that is located on the opposite side of the light incident surface, and includes quantum dots and a binder resin. A dot sheet that transmits a part of the light from the light source incident on the quantum dot sheet, and another part of the light from the light source has a wavelength different from the light from the light source by the quantum dot. A quantum dot sheet for converting the light from the light source that has passed through the quantum dot sheet from the emission surface and the wavelength-converted light, and a light incident surface side and a light emission surface side of the quantum dot sheet At least one of the reflectors is a reflector disposed along at least a part of the peripheral edge of the quantum dot sheet, and reflects at least a part of the light from the light source incident on the reflector And a reflector, the backlight apparatus is provided.

  According to another aspect of the present invention, there is provided a display device comprising the above backlight device and a display panel disposed on the light output side of the backlight device.

  According to the backlight device of one embodiment of the present invention and the display device of another embodiment, it is possible to suppress the color tone of the peripheral portion of the light emitting region from standing out compared to the color tone of the central portion of the light emitting region.

1 is a schematic configuration diagram of a display device including a backlight device according to a first embodiment. It is a schematic block diagram of the other backlight apparatus which concerns on 1st Embodiment. It is the figure which showed the light emission area | region in the backlight apparatus shown by FIG. It is the figure which planarly viewed the backlight apparatus shown by FIG. It is sectional drawing of the quantum dot sheet which concerns on 1st Embodiment. It is the figure which planarly viewed the reflector and quantum dot sheet which concern on 1st Embodiment from the reflector side. It is sectional drawing along the II line | wire of the reflector of FIG. 6, and a quantum dot sheet. It is a perspective view of the prism sheet which concerns on 1st Embodiment. It is sectional drawing along the II-II line of the prism sheet of FIG. It is sectional drawing of the reflective polarization separation sheet which concerns on 1st Embodiment. It is a schematic block diagram of the display apparatus containing the backlight apparatus which concerns on 2nd Embodiment. It is the figure which planarly viewed the backlight apparatus shown by FIG. 11 from upper direction. It is the figure which planarly viewed the reflector and quantum dot sheet which concern on 2nd Embodiment from the reflector side. It is sectional drawing along the III-III line of the reflector of FIG. 13, and a quantum dot sheet. It is a schematic block diagram of the display apparatus containing the backlight apparatus which concerns on 3rd Embodiment. It is the figure which planarly viewed the backlight apparatus shown by FIG. 15 from upper direction. It is the figure which planarly viewed the reflector and quantum dot sheet which concern on 3rd Embodiment from the reflector side. It is sectional drawing along the IV-IV line of the reflector of FIG. 17, and a quantum dot sheet. It is a schematic block diagram of the display apparatus containing the backlight apparatus which concerns on 4th Embodiment. FIG. 20 is a plan view of the backlight device shown in FIG. 19 from above. It is the figure which planarly viewed the reflector and quantum dot sheet which concern on 4th Embodiment from the reflector side. It is sectional drawing along the VV line | wire of the reflector of FIG. 21, and a quantum dot sheet.

[First Embodiment]
Hereinafter, a backlight device and a display device according to a first embodiment of the present invention will be described with reference to the drawings. In the present specification, terms such as “sheet”, “film”, and “plate” are not distinguished from each other only based on the difference in designation. Therefore, for example, “plate” is used to include a member called a sheet or a plate, and “sheet” is used to include a member that can also be called a film or a plate. FIG. 1 is a schematic configuration diagram of a display device including a backlight device according to this embodiment, FIG. 2 is a schematic configuration diagram of another backlight device according to this embodiment, and FIG. 3 is shown in FIG. FIG. 4 is a view showing a light emitting region in the backlight device, and FIG. 4 is a plan view of the backlight device shown in FIG. 1 from above. FIG. 5 is a cross-sectional view of the quantum dot sheet according to the present embodiment, FIG. 6 is a plan view of the reflector and quantum dot sheet according to the present embodiment from the reflector side, and FIG. 7 is the reflector of FIG. It is sectional drawing along the II line | wire of a quantum dot sheet. 8 is a perspective view of the prism sheet according to the present embodiment, FIG. 9 is a cross-sectional view taken along the line II-II of the prism sheet of FIG. 8, and FIG. 10 is a reflective polarization separation sheet according to the present embodiment. FIG.

[Display device]
A display device 10 shown in FIG. 1 includes a backlight device 20 and a display panel 30 disposed on the light output side of the backlight device 20. The display device 10 has a display surface 10A for displaying an image. In the display device 10 shown in FIG. 1, the surface of the display panel 30 is a display surface 10A.

  The backlight device 20 illuminates the display panel 30 from the back side. The display panel 30 functions as a shutter that controls transmission or blocking of light from the backlight device 20 for each pixel, and is configured to display an image on the display surface 10A.

<<< Display Panel >>>
A display panel 30 shown in FIG. 1 is a liquid crystal display panel, and a polarizing plate 31 disposed on the light incident side, a polarizing plate 32 disposed on the light exit side, and between the polarizing plate 31 and the polarizing plate 32. The liquid crystal cell 33 is provided. Polarizing plates 31 and 32 decompose incident light into two linearly polarized light components (S-polarized light and P-polarized light) orthogonal to each other and vibrate in one direction (direction parallel to the transmission axis) (for example, P It has a function of transmitting a linearly polarized component (for example, S-polarized light) that transmits polarized light and vibrates in the other direction (direction parallel to the absorption axis) perpendicular to the one direction.

  The liquid crystal cell 33 is configured such that a voltage can be applied to each region where one pixel is formed. Then, the alignment direction of the liquid crystal molecules in the liquid crystal layer 33 changes depending on the presence or absence of voltage application. As an example, the linearly polarized light component in a specific direction transmitted through the polarizing plate 31 disposed on the light incident side rotates the polarization direction by 90 ° when passing through the liquid crystal cell 33 to which a voltage is applied, When passing through the liquid crystal cell 33 to which no voltage is applied, the polarization direction is maintained. In this case, depending on whether or not a voltage is applied to the liquid crystal cell 33, the linearly polarized light component oscillating in a specific direction transmitted through the polarizing plate 31 is transmitted through the polarizing plate 32 or absorbed and blocked by the polarizing plate 32. it can. In this way, the display panel 30 is configured to control transmission or blocking of light from the backlight device 20 for each pixel. The details of the liquid crystal display panel are described in various known literatures (for example, “Flat Panel Display Dictionary” (published by Tatsuo Uchida, Hiraki Uchiike), 2001, Industrial Research Council). The detailed description of is omitted.

<<<< Backlight Device >>>>
The backlight device 20 shown in FIG. 1 is configured as an edge light type backlight device, and is disposed on a light source 35, a light guide plate 40 disposed on the side of the light source 35, and a light output side of the light guide plate 40. The quantum dot sheet 50, the reflector 60 disposed on the light exit surface 50B side of the quantum dot sheet 50, the prism sheet 70 disposed on the light exit surface 50B side of the quantum dot sheet 50, and the light exit side of the prism sheet 70 The prism sheet 75, the reflective polarization separation sheet 80 disposed on the light output side of the prism sheet 75, and the reflection sheet 90 disposed on the opposite side of the light guide plate 40 from the light output side are provided. The backlight device 20 includes the light guide plate 40, the prism sheets 70 and 75, the reflective polarization separation sheet 80, and the reflective sheet 90, but these members may not be included. The backlight device may be a direct type backlight device as shown in FIG. In the backlight device 100 shown in FIG. 2, the light source 35 is positioned immediately below the quantum dot sheet 50, and the light diffusion plate 110 is disposed between the light source 35 and the quantum dot sheet 50. Note that the backlight device 100 does not include a light guide plate. Moreover, the light diffusing plate 110 will not be specifically limited if the light from the light source 35 can be diffused. In the present specification, the “light exit side” means a side from which light is emitted from each member in the direction of exiting the backlight device.

  The backlight device 20 has a light emitting region R1 that emits light in a planar shape. In the present embodiment, since the region where the reflector 60 exists also emits light, the region where the reflector 60 exists is also included in the light emitting region R1. That is, as shown in FIGS. 3 and 4, the light emitting region R <b> 1 in the present embodiment is a region obtained by combining the region where the reflector 60 exists and the region inside the reflector 60. In the present embodiment, the peripheral portion P of the light emitting region R1 described later means a portion near the region where the reflector 60 exists in the light emitting region R1, as shown in FIG. 4, and the light emitting region R1. As shown in FIG. 4, the central portion C means a portion near the center of the light emitting region R1.

<< light source >>
The light source 35 may be configured in various modes such as a fluorescent lamp such as a linear cold cathode tube, a point light emitting diode (LED), an incandescent lamp, and the like. In the present embodiment, the light sources 35 are arranged side by side along the longitudinal direction of a light incident surface 40C (to be described later) of the light guide plate 40 (in FIG. 1, the direction orthogonal to the paper surface, that is, the front and back direction of the paper surface). It is comprised by many point-like light-emitting bodies, specifically, many light-emitting diodes (LED).

  As the quantum dot sheet 50 is disposed in the backlight device 20, the light source 35 can use only a light emitter that emits light in a single wavelength region. For example, only a blue light emitting diode that emits blue light with high color purity can be used as the light source.

<< Light guide plate >>
The light guide plate 40 is formed in a quadrangular shape in plan view (in FIG. 1, the shape viewed from above). The light guide plate 40 extends between the light output surface 40A formed by one main surface on the display panel 30 side, the back surface 40B formed of the other main surface facing the light output surface 40A, and the light output surface 40A and the back surface 40B. And a side surface. The side surface on the light source 35 side of the side surfaces is a light incident surface 40C that receives light from the light source. The light that has entered the light guide plate 40 from the light incident surface 40C is guided in the light guide plate in a direction (light guide direction) connecting the light incident surface 40C and the opposite surface opposite to the light incident surface 40C. Is emitted from 40A. The side surface of the light guide plate 40 is covered with a frame (not shown).

  As a material constituting the light guide plate 40, it is widely used as a material for an optical sheet incorporated in a display device, and has excellent mechanical characteristics, optical characteristics, stability, workability and the like, and can be obtained at low cost. For example, transparent resins mainly composed of one or more of acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, polyacrylonitrile, etc., and epoxy acrylate or urethane acrylate reactive resins (ionizing radiation curable resins, etc.) are preferably used. obtain. Note that a diffusion material having a function of diffusing light may be added to the light guide plate 40 as necessary. As the diffusing material, for example, particles made of a transparent substance such as silica (silicon dioxide), alumina (aluminum oxide), acrylic resin, polycarbonate resin, or silicone resin having an average particle size of 0.5 μm to 100 μm can be used. .

<< Quantum dot sheet >>
As shown in FIGS. 1 and 5, the quantum dot sheet 50 includes a light incident surface 50A that receives light from the light source 35 via the light guide plate 40A and a light exit surface 50B that is located on the opposite side of the light incident surface 50A. Have. The quantum dot sheet 50 includes a quantum dot layer 51 including quantum dots 56 and a binder resin 57, barrier films 52 and 53 formed on the light incident surface 51A and the light outgoing surface 51B of the quantum dot layer 51, and barrier films 52 and 53. And light diffusing layers 54 and 55 disposed thereon. The quantum dot sheet 50 only needs to include the quantum dots 56 and the binder resin 57, and may not include the barrier films 52 and 53 and the light diffusion layers 54 and 55.

  When light from the light source 35 enters the light incident surface 50A of the quantum dot sheet 50 through the light guide plate 40, a part of the light L1 from the light source 35 passes between the quantum dots 56 as shown in FIG. Then, the quantum dot sheet 50 is transmitted without being wavelength-converted by the quantum dot 56. For this reason, a part of the light L1 from the light source 35 is emitted as it is from the light exit surface 50B of the quantum dot sheet 50. On the other hand, as shown in FIG. 5, another part of the light L1 from the light source 35 is converted into light L2 having a wavelength different from that of the light from the light source 35 by the quantum dots 56. For this reason, the wavelength-converted light L <b> 2 is emitted from the light exit surface 50 </ b> B of the quantum dot sheet 50. In this specification, “light from a light source” is light emitted from a light source and means light whose wavelength is not converted, and is a concept that does not include wavelength-converted light.

<Quantum dot layer>
As shown in FIG. 5, the quantum dot layer 51 is a layer including quantum dots 56 and a binder resin 57. The quantum dot layer 51 may further include a light scattering material. The film thickness of the quantum dot layer 51 is preferably 10 μm or more and 150 μm or less. If the film thickness of the quantum dot layer 51 is within this range, it is suitable for reducing the weight and thickness of the display device, and color unevenness due to fluctuations in the thickness (manufacturing tolerance) of the quantum dot layer can be suppressed. The film thickness of the quantum dot layer is measured, for example, by measuring the thickness of 20 locations from an image of a cross section taken using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM). , And can be calculated from the average value of the values at 20 locations. Since the film thickness of the quantum dot layer is on the order of μm, among these, it is preferable to measure the film thickness of the quantum dot layer using SEM.

(Quantum dot)
The quantum dots 56 are nano-sized semiconductor particles having a quantum confinement effect. The particle size of the quantum dots 56 is preferably 1 nm or more and 20 nm or less. When the quantum dot 56 absorbs light from the excitation source and reaches an energy excitation state, the quantum dot 56 releases energy corresponding to the energy band gap of the quantum dot 56. Therefore, by adjusting the particle size of the quantum dots 56 or the composition of the substance, the energy band gap can be adjusted, and energy of various levels of wavelength bands can be obtained. In particular, the quantum dot 56 can generate strong fluorescence in a narrow wavelength band.

  Specifically, the energy band gap of the quantum dot 56 increases as the particle size decreases. That is, as the crystal size decreases, the light emission of the quantum dots shifts to the blue side, that is, to the high energy side. Therefore, by changing the particle size of the quantum dots, the emission wavelength can be adjusted over the entire wavelength range of the ultraviolet region, visible region, and infrared region. For example, depending on the material, blue light is emitted when the quantum dot particle size is 1.5 nm or more and 2.5 nm or less, and green light is emitted when the quantum dot particle size is more than 2.5 nm and 4.5 nm or less. When the particle size of the quantum dots is more than 4.5 nm and not more than 7.5 nm, red light is emitted.

  In this specification, “blue light” is light having a wavelength range of 380 nm or more and less than 480 nm, “green light” is light having a wavelength range of 480 nm or more and less than 590 nm, and “red light” is It is light having a wavelength range of 590 nm to 750 nm.

  As the quantum dots 56 included in the quantum dot sheet 50, one type of quantum dot may be used, but at least two types of quantum dots having different particle diameters or materials may be used. The quantum dot sheet 50 shown in FIG. 5 includes, as quantum dots 56, first quantum dots 56A and second quantum dots 56B having a larger particle size than the first quantum dots.

  As described above, since the light emitted from the light exit surface 50B of the quantum dot sheet 50 also includes light from the light source 35, a light source that emits blue light is used as the light source 35, and blue light is used as the first quantum dot 56A. When a quantum dot that converts green light is used and a quantum dot that converts blue light to red light is used as the second quantum dot 56B, blue light, green light, and red light are mixed from the quantum dot sheet 50. White light can be emitted.

  The quantum dot 56 can generate strong fluorescence in a desired narrow wavelength region. For this reason, the backlight device 20 can illuminate the display panel 30 with light of three primary colors excellent in color purity. In this case, the display panel 30 has excellent color reproducibility.

  The quantum dots 56 may have a core-shell structure mainly having a core made of a semiconductor compound having a thickness of about 2 nm to 10 nm and a shell made of a semiconductor compound different from the core. The shell functions as a protective layer that protects the core.

  Examples of the core material include MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe. II-VI group semiconductor compounds such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs and TiSb , Semiconductor compounds such as group IV semiconductors such as Si, Ge and Pb, or semiconductor crystals containing semiconductors. Alternatively, a semiconductor crystal including a semiconductor compound containing three or more elements such as InGaP can be used. Among these, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are preferable from the viewpoints of ease of fabrication, controllability of the particle size for obtaining light emission in the visible region, and the like.

  The shell can increase the light emission efficiency of the quantum dots by using a semiconductor compound having a band gap higher than that of the semiconductor compound forming the core so that excitons are confined in the core. Examples of the core-shell structure (core / shell) having such a bandgap relationship include CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, Gap / ZnS, Si / ZnS, Examples include InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InGaP / ZnSTe, and InGaP / ZnSSe.

  The quantum dots 56 may have an organic polymer called a ligand outside the shell. The organic polymer has a function of increasing the compatibility between the quantum dots and the binder resin, and is appropriately selected depending on the type of the binder resin.

  The shape of the quantum dot 56 is not particularly limited, and may be, for example, a spherical shape, a rod shape, a disk shape, or other shapes. When the quantum dots 56 are not spherical, the particle size of the quantum dots 56 can be a true spherical value having the same volume.

  Information such as the particle size, shape, and dispersion state of the quantum dots 56 can be obtained by a transmission electron microscope (TEM). The crystal structure and particle size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, the information regarding the particle diameter etc. of a quantum dot can also be obtained with an ultraviolet-visible (UV-Vis) absorption spectrum.

(Binder resin)
The binder resin 57 is not particularly limited, and examples thereof include a polymer of a photopolymerizable compound (crosslinked product), a polymer of a thermosetting compound such as an epoxy resin (crosslinked product), a thermoplastic resin, and a silicone resin. The photopolymerizable compound has at least one photopolymerizable functional group. In the present specification, the “photopolymerizable functional group” is a functional group capable of undergoing a polymerization reaction by light irradiation. Examples of the photopolymerizable functional group include ethylenic double bonds such as a (meth) acryloyl group, a vinyl group, and an allyl group. The “(meth) acryloyl group” means to include both “acryloyl group” and “methacryloyl group”. The light irradiated when polymerizing the photopolymerizable compound includes visible light and ionizing radiation such as ultraviolet rays, X-rays, electron beams, α rays, β rays, and γ rays.

  Examples of the photopolymerizable compound include a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable prepolymer, which can be appropriately adjusted and used. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or photopolymerizable prepolymer is preferable.

  The photopolymerizable monomer has a weight average molecular weight of 1000 or less. Examples of the photopolymerizable monomer include monomers containing a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethylene glycol di (meth) acrylate, Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) Acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol Tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol (meth) (meth) acrylic acid esters such as acrylate.

  The photopolymerizable oligomer has a weight average molecular weight of more than 1000 and 10,000 or less. As the photopolymerizable oligomer, a polyfunctional oligomer having two or more functions is preferable, and a polyfunctional oligomer having three (trifunctional) or more photopolymerizable functional groups is preferable. Examples of the polyfunctional oligomer include polyester (meth) acrylate, urethane (meth) acrylate, polyester-urethane (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and isocyanurate. (Meth) acrylate, epoxy (meth) acrylate, etc. are mentioned.

  The photopolymerizable prepolymer has a weight average molecular weight exceeding 10,000, and the weight average molecular weight is preferably from 10,000 to 80,000, and more preferably from 10,000 to 40,000. When the weight average molecular weight exceeds 80,000, the viscosity is high, so that the coating suitability is lowered, and the appearance of the obtained quantum dot layer may be deteriorated. Examples of the polyfunctional prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

<Light scattering material>
The light scattering material is not particularly limited as long as it has an effect of changing the traveling direction of light entering the quantum dot layer 51 by reflection or refraction, and for example, light scattering particles can be used. As the light scattering particles, inorganic particles are preferable, and antimony-doped tin oxide (ATO) particles, indium tin oxide (ITO) particles, MgO particles, Al ₂ O ₃ particles, TiO ₂ particles, BaTiO ₃ particles, Sb ₂ O ₅ particles. More preferably, it is at least one selected from the group consisting of SiO ₂ particles, ZrO ₂ particles and ZnO particles. By adding these light scattering materials to the quantum dot layer 51, the utilization efficiency of light entering the quantum dot layer 51 can be increased, and light wavelength conversion can be promoted.

<Barrier film>
The barrier films 52 and 53 only need to have a function of blocking moisture, oxygen, and the like. For example, as the constituent material of the barrier films 52 and 53, organic polymers such as polyester, silicon oxide, titanium oxide, aluminum oxide, and the like are used. An oxide etc. are mentioned. Examples of the polyester include polyethylene terephthalate.

  The average thickness of the barrier films 52 and 53 is preferably 10 μm or more and 150 μm or less. If the average thickness of the barrier films 52 and 53 is within this range, the quantum dots 56 can be reliably protected from moisture and oxygen by the barrier films 52 and 53, and the adhesion strength with the quantum dot layer 51 can be ensured. Can do. In addition, by setting the average thickness of the barrier films 52 and 53 within this range, generation of wrinkles and creases during the assembly and handling of the quantum dot sheet can be suppressed, and it is advantageous for weight reduction and thinning of the display. .

  The average thickness of the barrier films 52 and 53 can be calculated using, for example, a cross-sectional image taken with a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM).

  The barrier films 52 and 53 may have a multilayer structure of two or more layers. For example, the barrier films 52 and 53 may be composed of a base film made of polyester and a barrier layer provided on the base film.

  As a constituent material of the base film, for example, polyester (for example, polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyester, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, Examples thereof include thermoplastic resins such as polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, and polyurethane. The constituent material of the base film is preferably a polyester (for example, polyethylene terephthalate, polyethylene naphthalate) or a cellulose triacetate thermoplastic resin.

  Although the thickness of the said base film is not specifically limited, It is preferable that they are 10 micrometers or more and 150 micrometers or less. If the thickness is less than 10 μm, there is a risk of wrinkling and breaking during assembly and handling of the quantum dot sheet. If the thickness exceeds 150 μm, the display may be unsuitable for light weight and thinning. The minimum with more preferable thickness of the said base film is 50 micrometers or more, and a more preferable upper limit is 125 micrometers or less.

  The constituent material of the barrier layer is not particularly limited as long as the above-described barrier properties can be obtained, and examples thereof include inorganic oxides, metals, and sol-gel materials. Specifically, examples of the inorganic oxide include silicon oxide, aluminum oxide, titanium oxide, yttrium oxide, boron oxide, calcium oxide, silicon oxynitride carbide, and the metal includes, for example, Ti, Examples of the sol-gel material include siloxane-based sol-gel materials. These materials may be used alone or in combination of two or more.

  The thickness of the barrier layer is not particularly limited, but is preferably 0.01 μm or more and 1 μm or less. If the thickness is less than 0.01 μm, the barrier performance of the barrier layer may be insufficient, and if it exceeds 1 μm, the barrier performance may be easily deteriorated due to cracks in the barrier layer. A more preferable lower limit of the thickness of the barrier layer is 0.03 μm or more, and a more preferable upper limit is 0.5 μm or less.

  The thickness of the barrier layer can be obtained as an average value of the thickness of the barrier layer measured at 20 locations in the cross-sectional microscope observation. Further, the barrier layer may be a single layer or may be a laminate of a plurality of layers. When the barrier layer is formed by stacking a plurality of layers, each layer constituting the barrier layer may be directly stacked or bonded.

  An anchor layer may be formed as a base layer for the barrier layer. Thereby, barrier property and a weather resistance can be improved. Examples of the material for forming the anchor layer include an adhesive resin, an inorganic oxide, an organic oxide, and a metal.

<Light diffusion layer>
The light diffusion layers 54 and 55 have a function of diffusing light incident on the quantum dot sheet 50 and light emitted from the quantum dot sheet 50. By providing the light diffusion layers 54 and 55, the light conversion efficiency in the quantum dot sheet 50 can be increased. The light diffusion layers 54 and 55 include light diffusion particles (not shown) and a binder resin (not shown).

  The quantum dot sheet 50 can be manufactured as follows, for example. First, two barrier films 52 and 53 are prepared, and one side of the barrier films 52 and 53 (for example, when the barrier films 52 and 53 are composed of a base film and a barrier layer, the surface on the barrier layer side) The light curable composition for light diffusion layer is applied to the surface opposite to the surface and dried to form a coating film of the composition for light diffusion layer. Then, the coating film is irradiated with ultraviolet rays to cure the coating film, thereby forming the light diffusion layers 54 and 55, whereby the barrier film 52 with the light diffusion layer 54 and the barrier film 53 with the light diffusion layer 55 are formed. Form. Next, a quantum dot layer composition containing quantum dots, a photopolymerization compound, a solvent, and the like is applied to the surface opposite to the light diffusion layer 54 side of the barrier film 52 with one light diffusion layer 54 and dried. To form a coating film of the quantum dot layer composition. Next, the barrier film 53 with the light expansion layer 55 is disposed on the coating film so that the surface opposite to the surface of the barrier film 53 with the light diffusion layer 55 on the light diffusion layer 55 side is in contact with the coating film, The quantum dot layer 51 is formed by irradiating ultraviolet rays to cure the coating film, whereby the quantum dot sheet 50 is obtained.

<< Reflector >>
As shown in FIG. 6, the reflector 60 is disposed along at least a part of the peripheral portion 50 </ b> C of the quantum dot sheet 50 on the light output side of the quantum dot sheet 50. As shown in FIG. 6, the reflector 60 is preferably arranged in a frame shape along the peripheral edge portion 50 </ b> C of the quantum dot sheet 50. In the backlight device 20 shown in FIG. 1, the reflector 60 is disposed on the light exit surface 50 </ b> B of the quantum dot sheet 50. However, it is not essential that the reflector 60 is disposed on the light exit surface 50B side of the quantum dot sheet 50, and the reflector 60 is on the light entrance surface 50A side of the quantum dot sheet 50 as described in the third embodiment. Alternatively, the quantum dot sheet 50 may be disposed on both the light incident surface 50A side and the light emitting surface 50B side.

  As shown in FIGS. 6 and 7, the reflector 60 is preferably arranged in a region R2 corresponding to the frame region of the display device. By disposing the reflector 60 in this region R, it is possible to reliably suppress the reflector 60 from being visually recognized when the backlight device 20 is incorporated into the display device 10. The “frame region” of the display device in this specification means a region outside the display region of the display device and not visually recognized by an observer.

  Depending on the size of the display device 10, the region R2 is, for example, a region from the end of the quantum dot sheet 50 to a position 3 mm away from the end of the quantum dot sheet 50 in the center direction of the quantum dot sheet. Is possible.

  The reflector 60 reflects at least part of the light from the light source 35 incident on the reflector 60. As shown in FIG. 7, the reflector 60 in the present embodiment includes a plurality of light reflecting portions 61 spaced apart from each other that reflect not only the light L1 from the light source 35 but also the light L2 that has been wavelength-converted by the quantum dots. Has been. Here, when the reflector 60 is composed of a plurality of light reflectors 61, the shape of the reflector 60 may become unclear, but the outer edge of the reflector 60 is located on the outside. Are obtained by connecting the outermost portions of each of the light reflecting portions with straight lines (the edge portion of the quantum dot sheet 50 in FIG. 6), and the inner edge of the reflector 60 is the innermost portion of the light reflecting portion 61 located on the inner side. It is obtained by connecting with a straight line (part indicated by a one-dot chain line in FIG. 6). Between the light reflecting portions 61, there is a light transmitting portion 62 that transmits the light L1 from the light source 35 and the wavelength-converted light L2.

  As shown in FIG. 7, in the region inside the reflector 60, the light L1 emitted from the light emitting surface 50B of the quantum dot sheet 50 and the light L2 wavelength-converted by the quantum dots 56 are Proceed toward the sheet 70. On the other hand, in the region where the reflector 60 exists, as shown in FIG. 7, the light L1 from the light source 35 incident on the light reflecting portion 61 of the reflector 60 and the light L2 wavelength-converted by the quantum dots are Reflected by the light reflecting portion 61. Since the light L2 from the light source reflected by the light reflecting portion 61 is returned again to the quantum dot sheet 50, this increases the chance of wavelength conversion by the quantum dots 56. Further, the light L2 wavelength-converted by the quantum dots 56 reflected by the light reflecting portion 61 is repeatedly reflected and emitted from a region where the light reflecting portion 60 does not exist (a region inside the light transmitting portion 62 and the reflector 60). To do. On the other hand, as shown in FIG. 7, the light L1 from the light source 35 incident on the light transmission unit 62 and the light L2 wavelength-converted by the quantum dots 56 pass through the light transmission unit 62 as they are.

  A light source that emits blue light is used as the light source 35, a quantum dot that converts the wavelength of blue light into green light as the quantum dot 56, and a quantum dot that converts the wavelength of blue light into red light, and blue light as the light reflecting portion. When a light reflecting part that reflects green light and red light is used, blue light from the light source incident on the light reflecting part and green light and red light converted by the quantum dot are reflected by the light reflecting part. The Since the blue light reflected by the light reflecting portion is returned again to the quantum dot sheet, this increases the chance of wavelength conversion by the quantum dots. Further, the green light and the red light reflected by the light reflecting portion are repeatedly reflected and emitted from a region where there is no light reflecting portion (a region inside the light transmitting portion or the reflector). On the other hand, the blue light, the green light, and the red light incident on the light transmissive portions between the light transmissive portions pass through the light transmissive portions as they are.

<Light reflection part>
For example, as shown in FIG. 6, the light reflecting portions 61 may be arranged in a line along the peripheral edge portion 50 </ b> C of the quantum dot sheet 50. Although the light reflecting portions 61 are separated from each other, by separating the light reflecting portions 61 from each other, the light L1 from the light source 35 and the light L2 wavelength-converted by the quantum dots 56 are transmitted from the light transmitting portion 62 that is a gap. And the light reflecting portion 61 becomes inconspicuous.

  Examples of the shape of the light reflecting portion 61 include a circle and a quadrangle. Further, from the viewpoint of obtaining a uniform appearance, when each light reflecting portion is circular, the diameter of the light reflecting portion is preferably 0.1 mm or more and 0.5 mm or less, and when each light reflecting portion is a quadrangle, The length of one side of the light reflecting portion is preferably 0.1 mm or more and 0.5 mm or less.

  The light reflecting portion 61 is not particularly limited as long as at least a part of the light L1 from the light source 35 can be reflected. However, from the viewpoint of preventing a color change by the light reflecting portion 61, a white light reflecting portion is preferable. The light reflecting portion 61 can be formed by printing. Examples of the material used for the light reflecting portion 61 include pearl pigments in which mica is coated with a metal oxide such as titanium oxide and iron oxide, calcium carbonate, and zinc oxide. Among these, pearl pigments are preferable from the viewpoint of reflection characteristics.

<< light transmission part >>
The light transmission part 62 is located between the light reflection parts 61. The light transmission part 62 shown in FIGS. 6 and 7 is a gap between the light reflection parts 61. 6 and FIG. 7 is a space between the light reflecting portions 61, but is not limited to the space, and transmits light L1 from the light source 35 and light L2 wavelength-converted by the quantum dots 56. If possible, it may be a transparent resin or the like.

<< Lens sheet >>
As shown in FIGS. 8 and 9, the lens sheets 70 and 75 change the traveling direction of the incident light L <b> 3 and emit it from the light output side, thereby improving the luminance in the front direction intensively (light collection). Function) and the function of reflecting incident light L4 and returning it to the quantum dot sheet 50 side (retroreflection function). The lens shape of the lens sheet may be a triangular prism shape, or a wavy shape or, for example, a hemispherical bowl shape. In the present embodiment, a lens sheet having a triangular lens shape will be described as a lens sheet. Note that the lenticular sheets 70 and 75 are different in arrangement and can have the same configuration. Therefore, the description common to the lens sheet will be described using reference numerals “70, 75”. Hereinafter, the configuration of each component will be described.

  The lens sheets 70 and 75 include a sheet-like main body 71 and a plurality of unit lenses 72 arranged side by side on the light output side of the main body 71.

  The main body 71 functions as a sheet-like member that supports the unit lens 72. As shown in FIG. 8, the unit lenses 72 are arranged on the light exit side surface 71 </ b> A of the main body 71 without leaving a gap. Therefore, the light exit surfaces of the lens sheets 70 and 75 are formed by the lens surface 72 A of the unit lens 72. On the other hand, as shown in FIG. 9, in the present embodiment, the main body 71 has a smooth surface that forms the light incident side surface of the lens sheets 70 and 75 as the light incident side surface 71B that faces the light emitting side surface 71A. doing.

  The unit lenses 72 are arranged side by side on the light exit side surface 71A of the main body 71. As shown in FIG. 9, the unit lenses 72 extend linearly in the direction intersecting with the arrangement direction A of the unit lenses 72, particularly linearly in the present embodiment. In the present embodiment, a large number of unit lenses 72 included in one lens sheet 70, 75 extend in parallel to each other. Further, the longitudinal direction L of the unit lenses 72 of the lens sheets 70 and 75 is orthogonal to the arrangement direction A of the unit lenses 72 in the lens sheets 70 and 75.

  As can be understood from FIG. 1, the arrangement direction of the unit lenses 72 of the lens sheet 70 and the arrangement direction of the unit lenses 72 of the lens sheet 75 intersect, and more specifically, are orthogonal to each other.

  The unit lens 72 has a triangular prism shape whose width becomes narrower toward the light output side. Accordingly, the shape of the cross section (also referred to as the main cutting surface of the lens sheet) parallel to both the normal direction N of the sheet surface of the main body 72 and the arrangement direction A of the unit lenses 72 is a triangular shape protruding to the light output side. ing. In particular, from the viewpoint of intensively improving the luminance in the front direction, the cross-sectional shape of the unit lens 72 in the main cut surface is an isosceles triangle shape, and the apex angle located between the equilateral sides is the light exit side surface 71A of the main body 71. Each unit lens 72 is configured to project from the light to the light exit side.

  From the viewpoint of improving the retroreflective function of the lens sheets 70 and 75, the unit lens 72 preferably has an apex angle of 80 ° or more and 100 ° or less, and more preferably has an apex angle of about 90 °.

  As an example, the dimensions of the lens sheets 70 and 75 can be set as follows. First, as a specific example of the unit lenses 72, the arrangement pitch of the unit lenses 72 (corresponding to the width of the unit lenses 72 in the illustrated example) can be set to 10 μm or more and 200 μm or less. However, in recent years, the definition of the arrangement of the unit lenses 72 is rapidly increasing, and the arrangement pitch of the unit lenses 72 is preferably set to 10 μm or more and 50 μm or less. Moreover, the protrusion height of the unit lens 72 from the main body 71 along the normal direction N to the sheet surface of the lens sheets 70 and 75 can be set to 5 μm or more and 100 μm or less. Further, the apex angle θ of the unit lens 72 can be set to 60 ° or more and 120 ° or less.

  The lens sheets 70 and 75 can be manufactured by molding the unit lens 72 on a base material or by extrusion molding. As a constituent material of the main body 71 and the unit lens 72, various materials can be used. However, it is widely used as a material for an optical sheet incorporated in a display device, and has excellent mechanical properties, optical properties, stability, workability, etc., and can be obtained at low cost, such as acrylic resin, polystyrene, polycarbonate, etc. A transparent resin mainly composed of one or more of polyethylene terephthalate, polyacrylonitrile, etc., and an epoxy acrylate or urethane acrylate photopolymerizable compound can be suitably used.

  When producing the lens sheets 70 and 75 by curing the photopolymerizable compound on the substrate, together with the unit lens 72, a sheet-like land portion that is positioned between the unit lens 72 and the substrate, You may make it form on a base material. In this case, the main body 71 is composed of a base and a land formed by a cured product of a photopolymerizable compound. On the other hand, in the lens sheets 70 and 75 manufactured by extrusion molding, the main body 71 and the plurality of unit lenses 72 on the light exit side surface 71A of the main body 71 can be integrally formed.

<< Reflection type polarization separation sheet >>
As shown in FIG. 10, the reflective polarization separation sheet 80 transmits only the first linearly polarized light component (for example, P-polarized light) L5 out of the light emitted from the lens sheet 75, and the first polarized light. The second linearly polarized light component (for example, S-polarized light) L6 orthogonal to the component L5 has a function of reflecting without absorbing it. The second linearly polarized light component L6 reflected by the reflective polarization separation sheet 80 is reflected by the reflective sheet 90 and the like, and the polarization is canceled (the first linearly polarized light component L5 and the second linearly polarized light component L6 are reflected). In a state in which both are included, the light again enters the reflective polarization separation sheet 80. Therefore, the reflective polarization separating sheet 80 transmits the first linearly polarized light component L5 out of the incident light again, and the second linearly polarized light component L6 orthogonal to the first linearly polarized light component L5 is reflected again. Hereinafter, by repeating the above process, about 70 to 80% of the light emitted from the lens sheet 75 at the beginning is emitted as the light source light that has become the first linearly polarized light component L5. Therefore, by making the polarization direction of the first linearly polarized light component (transmission axis component) L5 of the reflective polarization separation sheet 80 coincide with the transmission axis direction of the polarizing plate 31 of the display panel 30, the light is emitted from the backlight device 20. All the incident light can be used for image formation on the display panel 30. Therefore, even when the light energy input from the light source 35 is the same, it is possible to form an image with higher brightness than in the case where the reflective polarization separation sheet 80 is not disposed, and the energy utilization efficiency of the light source 35 is improved. To do. In particular, the light reflected by the reflective polarization separation sheet 80 can be wavelength-converted by the quantum dots 56 of the quantum dot sheet 50. Therefore, the conversion efficiency of the quantum dot sheet 50 can be further increased by arranging the reflective polarization separation sheet 80. Therefore, further improvement in the utilization efficiency of the light source light can be expected.

  As the reflective polarization separation sheet 80, “DBEF” (registered trademark) available from 3M Company can be used. In addition to “DBEF”, a high-intensity polarizing sheet “WRPS” or a wire grid polarizer available from Shinwha Intertek can be used as the reflective polarization separating sheet 80.

<< Reflective sheet >>
The reflection sheet 90 has a function of reflecting light leaking from the back surface 40 </ b> B of the light guide plate 40 and entering the light guide plate 40 again. The reflection sheet 90 includes a white scattering reflection sheet, 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 on the reflection sheet 90 may be regular reflection (specular reflection) or diffuse reflection. When the reflection on the reflection sheet 90 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

  In the present embodiment, the quantum dot sheet 50 is disposed on the light exit surface 50B side along at least a part of the peripheral portion 50C of the quantum dot sheet 50 and wavelength-converted by the light L1 from the light source 35 and the quantum dots 56. Light transmission that is positioned between the light reflector 61 and a reflector 60 that includes a plurality of light reflectors 61 that are spaced apart from each other to reflect the light L2, and that transmits the light L1 from the light source 35 and the wavelength-converted light L2. Since the part 62 is provided, it can suppress that the color of the peripheral part P of light emission area | region R1 stands out compared with the color of the center part C at the time of light emission. That is, the reason why the color of the peripheral portion P of the light emitting region R1 becomes more prominent than the color of the central portion during light emission is considered to be due to the following. First, since the light from the light source becomes light that travels toward the light output side by the light guide plate, the light is emitted from the peripheral edge of the quantum dot sheet toward the light output side. On the other hand, since the quantum dot is an nm-size particle and emits isotropically, the light subjected to wavelength conversion by the quantum dot is light directed in various directions. For this reason, the light wavelength-converted by the quantum dots is more likely to leak from the peripheral edge of the quantum dot sheet than the light from the light source. In addition, when a phosphor sheet is used instead of the quantum dot sheet, the phosphor contained in the phosphor sheet is μm-sized and extremely larger than the quantum dot. Light emission forward in the light traveling direction becomes stronger. Therefore, most of the light wavelength-converted by the phosphor travels forward in the light traveling direction from the light source, and the light leaking from the peripheral edge of the phosphor sheet becomes light leaking from the peripheral edge of the quantum dot sheet. There are few compared. Therefore, the problem that the wavelength-converted light easily leaks from the peripheral edge of the quantum dot sheet is a specific problem caused by using the quantum dot sheet. Further, since the end face of the quantum dot sheet is usually exposed, the quantum dots near the peripheral edge of the quantum dot sheet are deteriorated, and the conversion efficiency tends to be lowered. For these two reasons, the color of the light from the light source becomes strong at the peripheral part of the light emitting region, so that the color of the peripheral part of the light emitting region becomes the color of the central part of the light emitting region during light emission. It is thought that it will stand out in comparison. On the other hand, in the present embodiment, the light emitting surface 50B side of the quantum dot sheet 50 includes a plurality of light reflecting portions 61 spaced apart from each other that reflect the light L1 from the light source 35 and the light L2 wavelength-converted by the quantum dots. The reflected reflector 60 is disposed along the peripheral edge portion 50C of the quantum dot sheet 50, and the reflector 60 reflects the light L1 from the light source 35 incident on the reflector 60 and the light L2 wavelength-converted by the quantum dot 56. Yes. Therefore, since the light L1 from the light source reflected by the reflector 60 is returned to the quantum dot sheet 50 again, the opportunity of wavelength conversion by the quantum dots 56 increases. Thereby, in the peripheral part P of light emission area | region R1, while the quantity of the light L1 from the light source 35 can be reduced, the quantity of the light L2 wavelength-converted by the quantum dot 56 can be increased. Moreover, since the light transmission part 62 which permeate | transmits the light L1 from the light source 35 and the wavelength-converted light L2 is provided between the light reflection parts 61, the light L1 from the light source 35 in the peripheral part P of light emission area | region R1 is received. It won't be too weak. Thereby, it can suppress that the color of the peripheral part P of light emission area | region R1 stands out compared with the color of the center part C at the time of light emission.

[Second Embodiment]
Hereinafter, a backlight device and a display device according to a second embodiment of the present invention will be described with reference to the drawings. 11 is a schematic configuration diagram of a display device including the backlight device according to the present embodiment, FIG. 12 is a plan view of the backlight device shown in FIG. 12 and FIG. 11, and FIG. It is the figure which planarly viewed the reflector and quantum dot sheet which concern on a form from the reflector side, and FIG. 14 is sectional drawing along the III-III line | wire of the reflector and quantum dot sheet | seat of FIG. In the present embodiment, the same members as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  A display device 120 shown in FIG. 11 includes a backlight device 130 and a display panel 30 disposed on the light output side of the backlight device 130. As in the first embodiment, the backlight device 130 shown in FIG. 11 includes a light source 35, a light guide plate 40 disposed on the side of the light source 35, and quantum dots disposed on the light output side of the light guide plate 40. Sheet 50, reflector 140 disposed on the light exit surface 50B side of the quantum dot sheet 50, lens sheet 70 disposed on the light exit surface 50B side of the quantum dot sheet 50, and lens sheet disposed on the light exit side of the lens sheet 70 75, a reflective polarization separating sheet 80 disposed on the light output side of the lens sheet 75, and a reflective sheet 90 disposed on the opposite side of the light guide plate 40 from the light output side. This is different from the reflector 60 described in the first embodiment.

<< Reflector >>
As illustrated in FIGS. 11 to 13, the reflector 140 is disposed on the light exit surface 50 </ b> B side of the quantum dot sheet 50 along at least a part of the peripheral portion 50 </ b> C of the quantum dot sheet 50. As shown in FIG. 13, the reflector 140 is preferably arranged in a frame shape along the peripheral edge 50 </ b> A of the quantum dot sheet 50. The reflector 140 shown in FIG. 11 is disposed on the light exit surface 50 </ b> B of the quantum dot sheet 50. However, it is not essential that the reflector 140 is disposed on the light exit surface 50B side of the quantum dot sheet 50, and the reflector 140 is on the light incident surface 50A side of the quantum dot sheet 50 as described in the fourth embodiment. Alternatively, the quantum dot sheet 50 may be disposed on both the light incident surface 50A side and the light emitting surface 50B side.

  The reflector 140 reflects a part L1 of the light from the light source 35 incident on the reflector 140. The reflector 140 in the present embodiment reflects a part of the light L1 from the light source 35, transmits a part of the light L1 from the light source, and converts the wavelength by the quantum dots 56 as shown in FIG. It has a function of transmitting at least a part of the emitted light L2.

  The reflector 140 has a higher reflectance of light from the light source than the reflectance of light whose wavelength has been converted by the quantum dots 56. That is, the reflector 140 has a lower transmittance of the light L1 from the light source 35 than the transmittance of the light L2 wavelength-converted by the quantum dots 56.

  As shown in FIG. 14, a part of the light L1 from the light source 35 incident on the reflector 140 is reflected and a part thereof is transmitted. Since the light L1 from the light source 35 reflected by the reflector 140 is returned again to the quantum dot sheet 50, this increases the chance of wavelength conversion by the quantum dots 56. On the other hand, as shown in FIG. 14, the light L2 that has been wavelength-converted by the quantum dots 56 incident on the reflector 120 may be partially reflected by the reflector 140, but the reflector 140 may be reflected by the quantum dots 56. Since the reflectance of the light L1 from the light source 35 is higher than the reflectance of the light L2 wavelength-converted by the wavelength L2, the wavelength-converted light L2 incident on the reflector 140 is transmitted more than the light L1 from the light source 35. To do.

  When a light source that emits blue light is used as the light source 35 and a quantum dot that converts the wavelength of blue light into green light and a quantum dot that converts the wavelength of blue light into red light are used as the quantum dots 56, Part of the blue light from the incident light source is reflected and part is transmitted. Since the blue light reflected by the reflector is returned again to the quantum dot sheet, this increases the chance of wavelength conversion by the quantum dots. On the other hand, since the reflectance of the blue light is higher than that of the green light and the red light, the green light and the red light incident on the reflector are transmitted through the blue light.

A band pass filter can be used as the reflector 60. Such a band-pass filter can be composed of, for example, a dielectric multilayer film. As the band-pass filter, for example, a silicon nitride (SiN _x ) layer and a silicon oxide (SiO ₂ ) layer are sequentially laminated so that the uppermost layer and the lowermost layer are made of the same material. Those stacked in 2n + 1 layers can be used. In this case, since the refractive index of silicon nitride is about 1.85 and the refractive index of silicon oxide is about 1.5, a bandpass filter can be formed by adjusting the thickness of the thin film. it can. Note that _x of the SiN _x takes a value of 1 or more and 1.3 or less.

  The reflector 140 has a reflectance of the light L1 from the light source 35 of 30% or more and 90% or less from the viewpoint of reducing the color difference between the peripheral portion P of the light emitting region R1 and the central portion of the light emitting region R1 during light emission. And the reflectance of the light L2 wavelength-converted by the quantum dots 56 is preferably 10% or less.

  As shown in FIGS. 13 and 14, the reflector 140 is preferably arranged in a region R2 corresponding to the frame region of the display device. By disposing the reflector 140 in the region R2, it is possible to reliably suppress the reflector 140 from being visually recognized when the backlight device 130 is incorporated into the display device 120.

  In the present embodiment, the quantum dot sheet 50 is disposed on the light exit surface 50B side along at least a part of the peripheral portion 50A of the quantum dot sheet 50, and the quantum dot 56 is more reflective than the reflectance of the light L1 from the light source 35. Since the reflector 140 having a high reflectance of the wavelength-converted light L2 is provided, the amount of the light L1 from the light source 35 can be reduced and the quantum dots 56 can be reduced at the peripheral edge P of the light emitting region R1 shown in FIG. The amount of wavelength-converted light L2 can be increased. Thereby, it can suppress that the color of the peripheral part P of light emission area | region R1 stands out compared with the color of the center part C at the time of light emission.

[Third Embodiment]
Hereinafter, a backlight device and a display device according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 15 is a schematic configuration diagram of a display device including the backlight device according to the present embodiment, FIG. 16 is a plan view of the backlight device shown in FIG. 15 from above, and FIG. It is the figure which planarly viewed the reflector and quantum dot sheet which concern, and FIG. 18 is sectional drawing along the IV-IV line | wire of the reflector and quantum dot sheet | seat of FIG. In the present embodiment, the same members as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  A display device 150 shown in FIG. 15 includes a backlight device 160 and a display panel 30 disposed on the light output side of the backlight device 160. The backlight device 160 shown in FIG. 15 includes a light source 35, a light guide plate 40 disposed on the side of the light source 35, a quantum dot sheet 50 disposed on the light output side of the light guide plate 40, and an entrance of the quantum dot sheet 50. The reflector 170 disposed on the light surface 50A side, the lens sheet 70 disposed on the light exit surface 50B side of the quantum dot sheet 50, the lens sheet 75 disposed on the light exit side of the lens sheet 70, and the light output of the lens sheet 75 The reflection type polarization separation sheet 80 disposed on the side and the reflection sheet 90 disposed on the side opposite to the light output side of the light guide plate 40 are provided.

<< Reflector >>
The reflector 170 reflects the light L1 from the light source 35 incident on the reflector 170. As shown in FIG. 18, the reflector 170 in the present embodiment includes a plurality of light reflecting portions 171 spaced apart from each other that reflect the light L1 from the light source 35 and the light L2 wavelength-converted by the quantum dots 56. Yes. As shown in FIGS. 17 and 18, there is a light transmission portion 172 that transmits the light L <b> 1 from the light source 35 and the wavelength-converted light L <b> 2 between the light reflection portions 171.

  The reflector 170 has the same configuration, material, and the like as the reflector 60, but is different from the first embodiment in the location of the reflector. Specifically, as shown in FIGS. 15 and 18, the reflector 170 is disposed along at least a part of the peripheral portion 50 </ b> C of the quantum dot sheet 50 on the light incident surface 50 </ b> A side of the quantum dot sheet 50. Yes. As shown in FIG. 17, the reflector 170 is preferably arranged in a frame shape along the peripheral edge portion 50 </ b> C of the quantum dot sheet 50. The reflector 170 is disposed on the light incident surface 50 </ b> A of the quantum dot sheet 50. Since the reflector 170 has the same configuration and material as the reflector 60, description of the configuration and material of the reflector 170 is omitted.

  In the present embodiment, the quantum dot sheet 50 is disposed on the light incident surface 50A side along at least a part of the peripheral portion 50C of the quantum dot sheet 50, and is wavelength-converted by the light L1 from the light source 35 and the quantum dots 56. The light 170 that is composed of a plurality of light reflectors 171 spaced apart from each other that reflects the light L2 and the light that is located between the light reflectors 171 and that transmits the light L1 from the light source 35 and the wavelength-converted light L2 Since the transmission part 172 is provided, it can suppress that the color of the peripheral part P of the light emission area | region R1 shown by FIG. 16 stands out compared with the color of the part of the center part C at the time of light emission. That is, the reflector 170 along at least a part of the peripheral portion 50A of the quantum dot sheet 50 is disposed on the light incident surface 50A side of the quantum dot sheet 50, and is emitted from the light guide plate 40 and incident on the reflector 170. Since the light L1 from the light source 35 is reflected by the reflector 170, the amount of the light L1 from the light source 35 in the peripheral portion P of the light emitting region R1 can be reduced. Further, since the quantum dots 56 emit light isotropically, the light L2 wavelength-converted by the quantum dots 56 is light directed in various directions. For this reason, as shown in FIG. 18, the light L2 wavelength-converted by the quantum dots 56 is not only light directed to the light exit surface 50B but also light directed to the light incident surface 50A side of the peripheral portion 50C of the quantum dot sheet 50. Exists. In the present embodiment, since the reflector 170 along at least a part of the peripheral portion 50C of the quantum dot sheet 50 is disposed on the light incident surface 50A side of the quantum dot sheet 50, the wavelength is converted by the quantum dots 56, And the light L2 which can reflect the light L2 which goes to the light incident surface 50A side of the peripheral part 50C of the quantum dot sheet 50 is wavelength-converted by the quantum dot 56 from the light incident surface 50A of the peripheral part 50C of the quantum dot sheet 50. Can be prevented from leaking. Moreover, since the light L1 reflected by the reflector 170 is returned to the light guide plate 40 again, reflection is repeated, and enters the quantum dot sheet 50 from a region where the reflector 170 does not exist. This increases the opportunity for wavelength conversion by the quantum dots 56. For this reason, since the amount of the light L2 wavelength-converted by the quantum dots 56 at the peripheral portion P of the light emitting region R1 can be increased, the color of the peripheral portion P of the light emitting region R1 is the central portion during light emission. It can suppress standing out compared with the color of C.

[Fourth Embodiment]
Hereinafter, a backlight device and a display device according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 19 is a schematic configuration diagram of a display device including a backlight device according to the present embodiment, FIG. 20 is a plan view of the backlight device shown in FIG. 19 from above, and FIG. It is the figure which planarly viewed the reflector and quantum dot sheet which concern, and FIG. 22 is sectional drawing along the VV line | wire of the reflector and quantum dot sheet | seat of FIG. In the present embodiment, the same members as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  A display device 180 shown in FIG. 19 includes a backlight device 190 and a display panel 30 disposed on the light output side of the backlight device 190. The backlight device 130 shown in FIG. 19 includes a light source 35, a light guide plate 40 disposed on the side of the light source 35, a quantum dot sheet 50 disposed on the light output side of the light guide plate 40, and a quantum dot sheet 50 input. The reflector 200 disposed on the light surface 50A side, the lens sheet 70 disposed on the light exit surface 50B side of the quantum dot sheet 50, the lens sheet 75 disposed on the light exit side of the lens sheet 70, and the light output of the lens sheet 75 The reflection type polarization separation sheet 80 disposed on the side and the reflection sheet 90 disposed on the side opposite to the light output side of the light guide plate 40 are provided.

<< Reflector >>
The reflector 200 reflects a part of the light L1 from the light source 35 incident on the reflector 200. As shown in FIG. 22, the reflector 200 in the present embodiment reflects a part of the light L1 from the light source 35, transmits the other part of the light L1 from the light source 35, and quantum dots. This has a function of reflecting at least a part of the light L1 wavelength-converted by 56.

  As shown in FIGS. 19, 21, and 22, the reflector 200 is disposed on the light incident surface 50 </ b> A side of the quantum dot sheet 50 along at least a part of the peripheral portion 50 </ b> C of the quantum dot sheet 50. As shown in FIG. 21, the reflector 200 is preferably arranged in a frame shape along the peripheral edge portion 50 </ b> C of the quantum dot sheet 50. The reflector 200 shown in FIGS. 19 and 22 is disposed on the light incident surface 50 </ b> A of the quantum dot sheet 50.

  As shown in FIG. 22, a part of the light L1 from the light source 35 incident on the reflector 200 is reflected and a part is transmitted. Since the light L1 reflected by the reflector 200 is returned to the light guide plate 40 again, the light L1 is repeatedly reflected and enters the quantum dot sheet 50 from a region inside the reflector 200. This increases the opportunity for wavelength conversion by the quantum dots 56. On the other hand, as shown in FIG. 22, at least a part of the light L <b> 2 whose wavelength has been converted by the quantum dots 56 incident on the reflector 200 from the quantum dot sheet 50 side is reflected by the reflector 200.

  When a light source that emits blue light is used as the light source 35 and a quantum dot that converts the wavelength of blue light into green light and a quantum dot that converts the wavelength of blue light into red light are used as the quantum dots 56, Part of the blue light from the incident light source is reflected and part is transmitted. The blue light reflected by the reflector is returned again to the light guide plate and again returned to the light guide plate 40. Therefore, reflection is repeated and enters the quantum dot sheet from a region inside the reflector. This increases the opportunity for wavelength conversion by quantum dots. On the other hand, since the reflector reflects at least part of the green light and red light, at least part of the green light and red light incident on the reflector from the quantum dot sheet side is reflected.

  For example, the reflector 200 preferably has a lower reflectance of light from the light source than the reflectance of light whose wavelength has been converted by the quantum dots 56. A band pass filter can be used as the reflector 200. Such a bandpass filter can be composed of, for example, a dielectric multilayer film.

  In the reflector 200, the reflectance of the light L1 from the light source 35 is 5% or more and 10% or less from the viewpoint of reducing the difference in color between the peripheral portion P of the light emitting region R1 and the central portion of the light emitting region R1 during light emission. It is preferable that the reflectance of the light L2 wavelength-converted by the quantum dots 56 is 30% or more.

  In the present embodiment, the quantum dot sheet 50 is disposed on the light incident surface 50A side along at least a part of the peripheral edge 50A of the quantum dot sheet 50, reflects a part of the light L1 from the light source 35, 20 is provided at the time of light emission because the reflector 200 that transmits another part of the light L1 from the light and reflects at least a part of the light L2 wavelength-converted by the quantum dots 56 is provided. It can suppress that the color of the peripheral part P of the light emission area | region R1 to stand out compared with the color of the center part C part. That is, the reflector 200 along at least a part of the peripheral portion 50A of the quantum dot sheet 50 is disposed on the light incident surface 50A side of the quantum dot sheet 50, and is emitted from the light guide plate 40 and incident on the reflector 200. Since the light L1 from 35 is reflected by the reflector 200, the amount of the light L1 from the light source 35 can be reduced at the peripheral portion P of the light emitting region R1. Further, the reflector 200 can reflect the light L2 that is wavelength-converted by the quantum dots 56 and travels toward the light incident surface 50A side of the peripheral edge 50C of the quantum dot sheet 50. It is possible to reduce leakage of the light L2 wavelength-converted by the quantum dots 56 from the light incident surface 50A. In addition, since the light L1 reflected by the reflector 200 is returned to the light guide plate 40 again, the light L1 is repeatedly reflected and enters the quantum dot sheet 50 from a region inside the reflector 200. This increases the opportunity for wavelength conversion by the quantum dots 56. For this reason, since the amount of the light L2 wavelength-converted by the quantum dots 56 at the peripheral portion P of the light emitting region R1 can be increased, the color of the peripheral portion P of the light emitting region R1 is the central portion during light emission. It can suppress standing out compared with the color of C.

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited to these descriptions.

<Preparation of composition for quantum dot layer>
First, each component was mix | blended so that it might become a composition shown below, and the composition for quantum dot layers was obtained.
(Composition for quantum dot layer)
Epoxy acrylate (product name “Unidic V-5500”, manufactured by DIC): 99 parts by mass Green light emitting quantum dot (product name “CdSe / ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass Red light emitting quantum dot (product name “CdSe / ZnS 610”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5. 2 nm): 0.2 parts by mass Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan Ltd.): 1 part by mass

<Preparation of composition for light diffusion layer>
Each component was mix | blended so that it might become a composition shown below, and the composition for light diffusion layers was obtained.
(Composition for light diffusion layer)
Pentaerythritol triacrylate: 99 parts by mass Light-diffusing particles (cross-linked acrylic resin beads, product name “SSX-105”, manufactured by Sekisui Plastics Co., Ltd., average particle size 5 μm): 158 parts by mass Photoinitiator ( 1-hydroxycyclohexyl phenyl ketone, product name “Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.”: 1 part by mass / solvent (methyl isobutyl ketone: cyclohexanone = 1: 1 (mass ratio)): 387 parts by mass

<Composition for reflector>
An ink containing a pearl pigment (manufactured by Showa Ink Industries, Ltd.) was used as the reflector composition. The particle size of the pearl pigment was in the range of 10 to 50 μm, and the content of the pearl pigment in the ink was about 15% by weight.

<Example 1>
First, two barrier films were produced by the following method. In a high-frequency sputtering apparatus, a high-frequency power with a frequency of 13.56 MHz and a power of 5 kW is applied to the electrode to cause discharge in the chamber, and on one side of a polyethylene terephthalate film (product name “Lumirror T60”, manufactured by Toray Industries, Inc.) A silica vapor deposition layer having a thickness of 50 nm and a refractive index of 1.46 made of a target material (silica) was formed, whereby two barrier films made of a polyethylene terephthalate film and a silica vapor deposition layer were formed. Subsequently, the composition for light diffusion layers was apply | coated to the surface on the opposite side to the surface at the side of the silica vapor deposition layer in both barrier films, respectively, and the coating film was formed. Next, the solvent in the coating film was evaporated by allowing the formed coating film to dry by passing dry air at 80 ° C. for 30 seconds. Then, the light diffusion layer with a film thickness of 10 μm was formed by irradiating with ultraviolet rays so that the integrated light amount was 500 mJ / cm ² to cure the coating film, thereby forming a barrier film with a light diffusion layer. Subsequently, the composition for quantum dot layers was apply | coated to the silica vapor deposition layer side of one barrier film with a light-diffusion layer, and the coating film was formed. Next, the solvent in the coating film was evaporated by allowing the formed coating film to dry by passing dry air at 80 ° C. for 30 seconds. Then, by placing the other barrier film with a light diffusion layer so that the silica vapor deposition layer is in contact with the coating film surface, by irradiating ultraviolet rays so that the integrated light amount becomes 500 mJ / cm ² , the coating film is cured, A quantum dot layer with a film thickness of 80 μm was formed, thereby obtaining a quantum dot sheet. And the composition for reflectors is printed in the area | region from the end of the quantum dot sheet in the light emission surface of this quantum dot sheet to 2 mm so that the composition for reflectors may become dot shape, 80 degreeC dry air is 30 It was circulated for a second and dried to form a reflector composed of a plurality of light reflecting portions having a size of 800 μm, and a quantum dot sheet with a reflector was obtained.

  On the other hand, a Kindle Fire (registered trademark) HDX7 backlight (a blue light emitting diode having an emission peak wavelength of 450 nm), a light guide plate, two prism sheets, and a reflection sheet were prepared as light sources. The two prism sheets each include a sheet-like main body portion and a plurality of triangular prism-like unit prisms arranged side by side on the main body portion and extending in a direction intersecting the arrangement direction. The angle was 90 °.

  And while arrange | positioning a light-guide plate so that a backlight side may become a light-incidence surface, the quantum dot sheet | seat with a reflector, a prism sheet, and a prism sheet are arrange | positioned in this order on the light emission surface of a light-guide plate, A reflective sheet was placed on the back to obtain a backlight device. The quantum dot sheet with a reflector was disposed such that the reflector was on the light exit side from the quantum dot sheet. Further, the prism sheet on the observer side was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the prism sheet.

<Example 2>
In Example 2, a backlight device is manufactured in the same manner as in Example 1 except that a band pass filter is disposed as a reflector instead of a plurality of light reflecting parts on the light exit surface of the quantum dot sheet. did. The band-pass filter reflects 40% of light in the wavelength region of 380 nm or more and 490 nm or less, and transmits 90% of light in the wavelength region of 500 nm or more.

<Example 3>
In Example 3, a backlight device was produced in the same manner as in Example 1 except that a bandpass filter was disposed in an area from the end of the quantum dot sheet on the light incident surface of the quantum dot sheet to 2 mm. . The band-pass filter reflects 90% of light in the wavelength range of 500 nm to 700 nm and transmits 90% of light in the wavelength range of 380 nm to 490 nm.

<Comparative example>
In the comparative example, a backlight device was manufactured in the same manner as in Example 1 except that no reflector was disposed.

<Measurement of chromaticity in light emitting area>
In the backlight device according to Examples 1 to 3 and the backlight device according to the comparative example, the chromaticity of the peripheral portion and the central portion of the light emitting region at the time of light emission was measured using a spectroradiometer (product name “SR-UL2”, Topcon Corporation). Measured respectively using

<Visual evaluation of light emitting area>
In the dark room, the peripheral portion (the portion between the end and a position near 5 mm from the end) and the central portion of the light emitting region at the time of light emission in the backlight devices according to Examples 1 to 3 and the backlight device according to the comparative example are visually observed. It was observed whether or not the color of the peripheral portion was more prominent than the color of the central portion. The evaluation criteria were as follows.
◯: The color of the peripheral part was the same as or slightly different from the color of the central part, but it was at a level causing no practical problem.
X: The color of a peripheral part was conspicuous compared with the color of a center part.

The results are shown in Table 1.

  From the above results, in the comparative example, the color of the peripheral portion of the light emitting region was more prominent at the time of light emission than the central portion of the light emitting region. On the other hand, in Examples 1-3, the difference of the color of the peripheral part of the light emission area | region at the time of light emission and the color of the center part was reduced compared with the comparative example. Therefore, in Example 1 and 2, it was confirmed that it was possible to suppress the color tone of the peripheral portion of the light emitting region from being distinguished from the color tone of the central portion of the light emitting region at the time of light emission.

10, 120, 150, 180 ... display devices 20, 100, 130, 160, 190 ... backlight device 30 ... display panel 35 ... light source 40 ... light guide plate 40A ... light exit surface 40C ... light entrance surface 50 ... quantum dot sheet 50A ... Light entrance surface 50B ... Light exit surface 50C ... Peripheral part 56 ... Quantum dots 60, 140, 170, 200 ... Reflectors 61, 171 ... Light reflection parts 62, 172 ... Light transmission parts 70, 75 ... Lens sheet 71 ... Main body part 72 ... Unit lens 80 ... Reflective polarization separation sheet

Claims (10)

A light source;
A quantum dot sheet having a light incident surface for receiving light from the light source and a light exit surface located on the opposite side of the light incident surface, and including quantum dots and a binder resin, and is incident on the quantum dot sheet A part of the light from the light source is transmitted, and another part of the light from the light source is converted into light having a wavelength different from that of the light from the light source by the quantum dots, and the quantum from the emission surface. A quantum dot sheet that emits light from the light source and wavelength-converted light transmitted through the dot sheet;
A reflector disposed along at least a part of the peripheral edge of the quantum dot sheet on at least one of the light incident surface side and the light exit surface side of the quantum dot sheet, and is incident on the reflector And a reflector that reflects at least part of light from the light source. The reflector is disposed on the light exit surface side of the quantum dot sheet, and the reflector is composed of a plurality of light reflecting portions spaced apart from each other for reflecting light from the light source,
2. The backlight device according to claim 1, further comprising a light transmission unit that is located between the light reflection units and transmits the light from the light source and the wavelength-converted light.   The backlight according to claim 1, wherein the reflector is disposed on a light exit surface side of the quantum dot sheet, and the reflector has a reflectance of light from the light source higher than a reflectance of the wavelength-converted light. apparatus. The reflector is arranged on the light incident surface side of the quantum dot sheet, and the reflector is composed of a plurality of light reflecting portions spaced apart from each other that reflect the light from the light source and the wavelength-converted light,
2. The backlight device according to claim 1, further comprising a light transmission unit that is located between the light reflection units and transmits the light from the light source and the wavelength-converted light.   The reflector is disposed on the light incident surface side of the quantum dot sheet, and the reflector reflects a part of the light from the light source incident on the reflector and at least a part of the wavelength-converted light, The backlight device according to claim 1, wherein another part of the light from the light source incident on the reflector is transmitted.   The light source emits blue light, and the quantum dots include first quantum dots that convert the blue light into green light, and second quantum dots that convert the blue light into red light. The backlight device according to 1.   The backlight device according to claim 1, wherein the backlight device is used in a display device, and the reflector is disposed in a region corresponding to a frame region of the display device.   The backlight device according to claim 1, further comprising a lens sheet that is disposed on a light exit surface side of the quantum dot sheet and has a light collecting function and a retroreflection function.   The backlight device according to claim 1, further comprising a reflective polarization separation sheet disposed on a light exit surface side of the quantum dot sheet. The backlight device according to claim 1;
And a display panel disposed on the light output side of the surface backlight device.

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