JP2016046239A - Backlight unit and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for reducing coloring of a portion to be displayed darkly, in a liquid crystal display device having a backlight unit including a wavelength conversion layer and capable of controlling local dimming.SOLUTION: A backlight unit includes; a light emitting part including at least a reflection member and a light source; at least one member selected from a group comprising a diffusion member and a light guide member; and a wavelength conversion layer. The backlight unit capable of controlling local dimming further includes a light control layer that is provided between the light emitting part and the wavelength conversion layer, and has a function of reducing linear transmissivity of obliquely incident light made incident from a wavelength conversion layer side oblique direction. Provided is a liquid crystal display device including the backlight unit.SELECTED DRAWING: None

Description

  The present invention relates to a backlight unit and a liquid crystal display device including the backlight unit.

  Flat panel displays such as liquid crystal display devices (hereinafter also referred to as LCDs (Liquid Crystal Displays)) consume less power and are increasingly used as space-saving image display devices year by year. The liquid crystal display device is composed of at least a backlight unit and a liquid crystal cell, and usually further includes members such as a backlight side polarizing plate and a viewing side polarizing plate.

  As a backlight unit, a light source including a white light source such as a white LED (Light-Emitting Diode) is widely used as a light source. On the other hand, in place of a white light source, in recent years, a light source including, for example, a light emitted from a light source such as a blue LED and a phosphor that emits fluorescence when excited by light emitted from the light source is disposed as a separate member. A new backlight unit that embodies white light by emitting light from the wavelength conversion layer is proposed (see Patent Document 1).

  As for drive control of the backlight unit, a technique called local dimming control is proposed in which the emitted light is locally extinguished or dimmed according to the image displayed on the display surface (Patent Document). 2 and 3).

JP 2008-41706 A JP 2004-221503 A JP 2012-199041 A

In the backlight unit described in Patent Literature 1, more specifically, for example, white light is realized as follows.
Light emitted from the light source enters a wavelength conversion layer disposed on the optical path of this light. Of the light incident on the wavelength conversion layer, the light that hits the phosphor excites the phosphor, and the light that has passed through the wavelength conversion layer without hitting the phosphor is emitted outside the wavelength conversion layer (from the light source) Output light).
Further, the excited phosphor emits light (fluorescence) having a wavelength different from that of incident light. For example, if a phosphor that emits yellow light (yellow phosphor) is used as the phosphor, yellow light is emitted from the wavelength conversion layer, and if a phosphor that emits green light (green phosphor) is used, green light is emitted. If a phosphor that emits red light (a red phosphor) is used, red light is emitted. Thus, from the wavelength conversion layer, it is possible to obtain outgoing light (further outgoing light) having a wavelength different from that of the outgoing light derived from the light source. For example, white light is realized by mixing outgoing light derived from a light source and further outgoing light. Regarding the color mixture of each color light, for example, paragraph 0033 of Patent Document 1 includes blue light as outgoing light derived from a light source, yellow light as further outgoing light, yellow light and red light as further outgoing light, or further It has been proposed to realize white light by mixing green light and red light as outgoing light. As described above, the white light is realized by mixing each color light including the light emitted from the phosphor included in the wavelength conversion layer, so that the luminance (degree of brightness per unit area) on the display surface of the liquid crystal display device is reduced. It is effective for improvement and expansion of the color reproduction range.

  On the other hand, according to the local dimming control described in Patent Documents 2 and 3, the light emitted from the backlight unit is directed toward a portion to be displayed darker than other portions such as a black display portion. By locally quenching or dimming the emitted light (local light amount control), it is possible to reduce the luminance of the portion to be displayed dark. Accordingly, the difference in brightness between the portion that should be displayed darkly and the portion that should be displayed brightly can be widened, so that the contrast of the image displayed on the display surface of the liquid crystal display device can be increased (a clear image can be displayed). It becomes possible. Further, the power consumption of the backlight unit can be reduced by locally quenching or dimming.

As described above, the backlight unit including the wavelength conversion layer and the backlight unit capable of local dimming control have various advantages.
Therefore, the present inventors have studied to combine these two technologies to constitute a backlight unit, and in a liquid crystal display device having such a backlight unit, a portion to be displayed darkly becomes tinted (for example, It has been revealed that a phenomenon occurs in which the color coordinates of the portion to be darkly displayed deviate from the color coordinates of the portion to be brightly displayed, resulting in coloring. Such unintentional coloration causes a reduction in the image quality of the displayed image and should be reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a means for reducing the tint of a portion to be displayed darkly in a liquid crystal display device having a backlight unit capable of local dimming control provided with a wavelength conversion layer.

As a result of intensive studies to achieve the above object, the present inventors have obtained the following backlight unit:
A light emitting unit including at least a reflecting member and a light source;
At least one member selected from the group consisting of a diffusion member and a light guide member;
A wavelength conversion layer;
Including
A backlight unit capable of local dimming control, further comprising a light control layer having a function of reducing the linear transmittance of obliquely incident light incident from an oblique direction on the wavelength conversion layer side between the light emitting unit and the wavelength conversion layer;
Was newly found and the present invention was completed.

The wavelength conversion layer is a layer capable of emitting light (wavelength conversion) having a wavelength different from that of the light incident on the layer.
The wavelength conversion layer side oblique direction means a direction other than the vertical direction with respect to the wavelength conversion layer side surface of the light control layer. The transmittance of light incident on the light control layer from this direction in a direction parallel to this direction is defined as the above-described linear transmittance (hereinafter also referred to as “oblique incident light linear transmittance”). The function of reducing the oblique incident light linear transmittance (hereinafter also referred to as “oblique incident light linear transmittance reducing function”) is compared to the case where there is no light control layer due to the presence of the light control layer. The function of reducing the linear transmittance of oblique incident light by 5% or more. If the oblique incident light linear transmittance can be reduced, the amount of light emitted in a direction other than the vertical direction with respect to the light source side surface of the light control layer (hereinafter also referred to as “obliquely emitted light”) is reduced. can do. This point will be further described later. The oblique incident light linear transmittance can be measured by a general spectrophotometer. An example of a spectrophotometer is UV-3150 manufactured by Shimadzu Corporation. The wavelength for measuring the oblique incident light linear transmittance reduction function is an arbitrary wavelength, and preferably one or more wavelengths in the wavelength band of blue light to red light of 430 to 680 nm. This point will also be described later.

  Also, a backlight unit capable of local dimming control refers to the backlight unit from the backlight unit toward the liquid crystal cell in accordance with the image displayed on the display surface of the liquid crystal display device when the backlight unit is incorporated in the liquid crystal display device. A backlight unit having a control mechanism (local dimming control mechanism) capable of locally extinguishing or dimming emitted light emitted in this manner is meant. For example, the control mechanism turns off a light source (for example, LED) located behind a black display portion on the display surface, or lowers the amount of light emitted from this light source below the amount of light emitted from other light sources. Dimming control can be performed. Details will be described later.

  In one embodiment, the light control layer is a layer that exhibits the above function by one or more actions selected from the group consisting of light interference, scattering, refraction, and reflection.

  In one aspect, the light control layer is a reflective polarizer. Here, the reflective polarizer refers to a polarizer that transmits only light that vibrates in a specific polarization direction among incident light that vibrates in all directions, and reflects light that vibrates in other polarization directions. .

  In one embodiment, the reflective polarizer is a polymer layer having cholesteric liquid crystallinity.

  In one embodiment, the reflective polarizer is a multilayer film in which a plurality of layers having different refractive indexes are stacked.

  In one aspect, the light control layer is a light scattering layer.

  In one aspect, the light scattering layer is an anisotropic light scattering layer.

  In one embodiment, the light control layer is a prism layer having a concavo-convex shape on the surface on the light emitting unit side.

  In one aspect, the light source is a light source that emits a single peak of light.

  In one aspect, the light source is a blue light source that emits blue light.

  In one aspect, the wavelength conversion layer includes a phosphor that emits fluorescence when excited by excitation light.

  In one aspect, the wavelength conversion layer includes at least a phosphor that is excited by excitation light and emits red light and a phosphor that is excited by excitation light and emits green light.

  In one aspect, the phosphor is a quantum dot.

  In one aspect, the backlight unit includes at least a diffusion member as at least one member selected from the group consisting of a diffusion member and a light guide member, and has a light control layer between the diffusion member and the wavelength conversion layer. .

  In one aspect, the backlight unit includes at least a diffusion member as at least one member selected from the group consisting of a diffusion member and a light guide member, and has a light control layer between the diffusion member and the light emitting portion.

  In one aspect, the backlight unit is a direct type backlight unit.

  A further aspect of the present invention relates to a liquid crystal display device including at least the backlight unit and a liquid crystal cell.

  According to the present invention, in a liquid crystal display device having a backlight unit having a wavelength conversion layer and capable of local dimming control, it is possible to reduce coloring of a portion that should be darkly displayed like a black display portion.

FIG. 1 is an explanatory diagram illustrating a partial configuration of a liquid crystal display device including a backlight unit according to one embodiment of the present invention. It is explanatory drawing of inference by the present inventors regarding the cause of occurrence of coloring. FIG. 3 is a schematic configuration diagram of an example of a wavelength conversion member manufacturing apparatus. FIG. 4 is a partially enlarged view of the manufacturing apparatus shown in FIG. FIG. 5 illustrates an example of a liquid crystal display device according to one embodiment of the present invention.

The following description may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In the present invention and this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Further, in the present invention and the present specification, the “half-value width” of a peak refers to the width of the peak at a peak height of ½. In addition, light having an emission center wavelength in the wavelength band of 430 to 480 nm is called blue light, light having an emission center wavelength in the wavelength band of 520 to 560 nm is called green light, and the emission center wavelength is in the wavelength band of 600 to 680 nm. The light having a color is called red light.
Further, the angle (for example, an angle such as “90 °”) and the relationship (for example, “orthogonal”, “parallel”, etc.) include the range of errors allowed in the technical field to which the present invention belongs. For example, it means that the angle is within the range of strict angle ± 10 °, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.

[Backlight unit]
One embodiment of the present invention provides:
A light emitting unit including at least a reflecting member and a light source;
At least one member selected from the group consisting of a diffusion member and a light guide member;
A wavelength conversion layer;
Including
A backlight unit capable of local dimming control, further comprising a light control layer having a function of reducing the linear transmittance of obliquely incident light incident from an oblique direction on the wavelength conversion layer side between the light emitting unit and the wavelength conversion layer;
About.

The following is not intended to limit the present invention, but the reason why the backlight unit described above can reduce the tint in the portion that should be darkly displayed is inferred as follows. Yes.
As a result of intensive studies, the present inventors have come to consider that the cause of occurrence of tinting may be in one or both of the following (1) and (2).

(1) The wavelength conversion layer preferably contains a phosphor. The phosphor usually has a property of emitting light isotropically. Therefore, part of the light emitted from the wavelength conversion layer is emitted not to the display surface side of the liquid crystal display device but also to the light emitting unit side. Thus, the light emitted from the wavelength conversion layer toward the light emitting unit is reflected by the reflecting member included in the light emitting unit, and returned to the display surface side as return light. For example, in a liquid crystal display device having a backlight unit that realizes white light by mixing color of blue light emitted from a light source and green light and red light emitted from a wavelength conversion layer, the return is thus returned to the display surface side. The light is, for example, yellow light in which green light and red light due to light emission in the wavelength conversion layer are mixed. When the return light is incident on the dark display portion of the display surface, the dark display portion may be tinted (for example, yellow). thinking.
FIG. 2 shows an explanatory diagram of the inference by the present inventors regarding the cause of the occurrence. FIG. 2 shows a reflector (reflecting member) 111, a light emitting unit 101 including light sources 112a and 112b, a backlight unit 100 including a wavelength conversion layer 113, and a liquid crystal panel 114. The portion to be displayed brightly is 114a, and the portion to be displayed dark is 114b. The wavelength conversion layer 113 includes a phosphor 1000. In FIG. 2, only one portion to be brightly displayed, one portion to be darkly displayed, and two phosphors are shown, but only two light sources are shown. It is not limited. The same applies to the thickness and shape of each layer and component, and the present invention is not limited to the embodiment shown in FIG. In FIG. 2, various members (for example, a liquid crystal cell, a polarizing plate, a diffusion plate (diffusion member), a light guide plate (light guide member), etc.) normally included in the liquid crystal display device are not shown. Of the light sources 112a and 112b, the light source 112b is a light source located behind the portion 114b to be displayed dark, and is turned off by a local dimming control mechanism (not shown) or has a light emission amount that is less than that of the light source 112a. Has been. The phosphor 1000 is excited by light emitted from the light source 112a and emits fluorescence. Typically, the thin arrow indicates that the phosphor 1000 emits light isotropically, and the outgoing light emitted toward the light emitting portion and the return light reflected by the reflecting plate 111 are indicated by thick arrows. As shown in FIG. 2, the return light 1002, which is the light 1001 emitted from the phosphor 1000 and emitted to the light emitting unit 101 side and reflected by the reflecting plate 111, enters the portion 114 b of the liquid crystal panel 114 to be displayed darkly. Is considered to be a cause of occurrence of tint in a portion to be displayed dark as described above. In FIG. 2, only one phosphor is shown for convenience of explanation, but a wavelength conversion layer 113 including two kinds of phosphors having different emission characteristics (for example, a green phosphor and a red phosphor) is shown. As described above, the present inventors have inferred that coloration due to color mixing occurs even in the embodiment having the above.

(2) Light emitted from the light source (for example, blue light) is emitted from the wavelength conversion layer and various members (for example, prism sheets) provided on the emission side of the wavelength conversion layer to improve brightness arbitrarily. Can be reflected or backscattered. Similar to the above (1), such light is reflected by the reflecting member included in the light-emitting portion, and enters the wavelength conversion layer as return light (in other words, so-called stray light), resulting in a dark display surface. Exciting the phosphor of the wavelength conversion layer behind the portion to be displayed to emit fluorescence also causes the portion to be darkly colored (for example, the green phosphor and red phosphor excited by the stray light emit light). The present inventors believe that this may cause yellowing due to the mixed color of fluorescent light).

Accordingly, as a result of further intensive studies, the present inventors have newly found the backlight unit in which the light control layer is provided between the light emitting portion and the wavelength conversion layer. The reason why the backlight unit can reduce the tint in the portion to be darkly displayed as described above is that the light amount of the return light can be reduced by the light control layer. The present inventors think. More specifically, an example will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram illustrating a partial configuration of a liquid crystal display device including a backlight unit according to one embodiment of the present invention. The reference numerals and components in the figure are the same as those in FIG. 2 unless otherwise specified.
The difference between FIG. 2 and FIG. 1 is the presence or absence of the light control layer 120. Of the fluorescence emitted from the phosphor 1000, the light (obliquely incident light) 1001 emitted to the light emitting unit 101 side provides the return light 1002, as shown in FIG. 2, without the light control layer 120. By the light control layer 120 having the function described above, the light amount of the obliquely emitted light 2001 is reduced as compared with the case where the light control layer 120 is not provided. Therefore, the amount of return light 1002 can also be reduced. The present inventors consider that this is the reason why it is possible to suppress the occurrence of tinting in a portion that should be displayed dark due to the above (1).

  Further, the present inventors have found that the light control layer can reduce the amount of light that is emitted or reflected from the wavelength conversion layer side toward the light emitting unit side in an oblique direction or backscattered. It is assumed that it contributes to reducing the amount of light. As a result, the present inventors consider that it is possible to suppress the occurrence of tinting in a portion that should be darkly displayed due to the above (2).

However, the above description includes inferences by the present inventors and does not limit the present invention.
Hereinafter, the backlight unit will be described in more detail.

<1. Light emitting part, diffusion member, light guide member>
The light emitting unit includes at least a reflecting member and a light source. Further, in the backlight unit, one or more members selected from the group consisting of a diffusing member and a light guide member are usually arranged on the emission side (liquid crystal panel side) of the light emitting unit. The backlight unit is classified into a direct type and an edge light type depending on the configuration of the light emitting unit. The direct type backlight unit is usually called a reflecting member, a plurality of light sources arranged on the reflecting member, and a diffusing member that diffuses and emits light emitted from the light source (usually called a diffusing plate, a diffusing sheet, or the like). And at least. On the other hand, in an edge light type backlight unit, a light source is usually disposed on a side surface side of a light guide member (usually referred to as a light guide plate), and a reflection member is disposed on the opposite side to the light exit surface side of the light guide member. . Further, a diffusion member may be disposed on the light exit surface side of the light guide member.
For the light emitting section, the diffusing member, and the light guiding member in the backlight unit, for example, a known configuration such as the configuration described in Japanese Patent No. 3416302, Japanese Patent No. 3363565, Japanese Patent No. 4091978, and Japanese Patent No. 3448626 may be adopted without any limitation. Can do. Details of the light source will be described later.

<2. Local dimming control mechanism>
The backlight unit is capable of local dimming control, and includes a control mechanism (local dimming control mechanism) therefor. The local dimming control mechanism receives, for example, information related to an image displayed on the display surface and generates a local dimming signal according to the received information. Included in a known local dimming control mechanism such as a local light amount control means for receiving and controlling the local light amount of the light source based on the received localing signal (for example, turning off some light sources in the direct type backlight unit) Various configurations can be provided. For example, regarding a local dimming control mechanism in a direct type backlight unit, for example, Japanese Patent No. 4914481 and Japanese Patent Application Laid-Open No. 2004-212503, etc. For a local dimming control mechanism in an edge light type backlight unit, Japanese Patent Application Laid-Open No. 2012-199041 Reference can be made to publicly known techniques such as Japanese Patent Publication. From the viewpoint of ease of local dimming control, direct dimming backlight units are preferable because local dimming control can be performed by turning off some of the plurality of light sources or reducing the amount of light.

<3. Wavelength conversion layer>
(3-1. Phosphor)
The wavelength conversion layer preferably contains at least one phosphor. The phosphor can be excited by excitation light to emit fluorescence. For example, the phosphor is excited by light emitted from a light source and incident on a wavelength conversion layer to emit fluorescence. Since the phosphor can emit fluorescence (wavelength conversion) having a wavelength different from that of the excitation light, the wavelength conversion layer can emit light having a wavelength different from that of the incident light.

In one aspect, the light source included in the light emitting unit is a light source that emits light having a single peak. Here, to emit light having a single peak means that in the emission spectrum, two or more peaks do not appear as in the case of a white light source, but there is only one peak having the emission center wavelength as an emission maximum. means. In one aspect, white light can be realized by mixing monochromatic light emitted from such a light source with light of other colors emitted from the phosphor of the wavelength conversion layer. In a specific embodiment, a light source that emits blue light having an emission center wavelength in a wavelength band of 430 nm to 480 nm, for example, a blue light emitting diode (blue LED) that emits blue light can be used. When using a light source that emits blue light, the wavelength conversion layer preferably includes at least a phosphor that is excited by excitation light and emits green light, and a phosphor that emits red light. Thereby, white light can be embodied by blue light emitted from the light source and passed through the wavelength conversion layer, and green light and red light emitted from the wavelength conversion layer.
Alternatively, in another aspect, a light source that emits ultraviolet light having an emission center wavelength in a wavelength band of 300 nm to 430 nm, for example, an ultraviolet light emitting diode can be used. In this case, the wavelength conversion member includes a phosphor that is excited by excitation light and emits green light, a phosphor that is excited by excitation light and emits red light, and a phosphor that is excited by excitation light and emits blue light. It is preferred that Thereby, white light can be embodied by blue light, green light, and red light emitted from the wavelength conversion layer.
In another embodiment, a laser light source can be used instead of the light emitting diode.
In another embodiment, a light source in which two or more peaks appear in the emission spectrum may be used. As such a light source, for example, a light source that emits a single-peak light as described above, and a phosphor that is incidentally added to provide a longer waveband emission band can be used. Specific examples include a light source (for example, LED) that emits blue light and yellow light by combining a light emitting element that emits blue light with a small amount of yellow phosphor.
In this way, in the backlight unit that realizes white light by mixing each color light, the inference by the present inventors regarding the point that a portion to be displayed darkly becomes tinted when local dimming control is performed is described above. Street. Such coloring can be reduced by disposing a light control layer between the light emitting portion and the wavelength conversion layer. Details of the light control layer will be described later.

  Any phosphor can be used without any limitation as long as it is excited by excitation light and emits fluorescence. The phosphor may be an organic phosphor or an inorganic phosphor, and one or more of these can be used. Examples of inorganic phosphors include oxide phosphors, sulfide phosphors, rare earth phosphors, quantum dot phosphors, and quantum rod phosphors. Among various phosphors, quantum dots are said to be excellent in terms of improving color reproducibility and the like, and are preferable as phosphors included in the wavelength conversion layer. The quantum dot (also referred to as quantum dot, QD, quantum dot) is, for example, a semiconductor crystal (semiconductor nanocrystal) particle having a nano-order size, a particle whose surface is modified with an organic ligand, or a semiconductor nanocrystal. A particle whose crystal surface is coated with a polymer layer. The emission wavelength of the quantum dots can usually be adjusted by the composition and size of the particles, and the composition and size. Quantum dots can be synthesized by known methods, and are also commercially available. For details, for example, US2010 / 123155A1, Special Table 2012-509604, US Patent 8425803, JP2013-136754, WO2005 / 022120, Special 2006-521278, Special 2010-535262. JP, 2010-540709, etc. can be referred to.

(3-2. Method for producing wavelength conversion layer)
The phosphor described above is usually contained in the matrix in the wavelength conversion layer. The matrix is usually a polymer (organic matrix) obtained by polymerizing the polymerizable composition by light irradiation or the like. The shape of the wavelength conversion member is not particularly limited. For example, the wavelength conversion layer may be included in the backlight unit as it is, and is included in the backlight unit as a laminate (wavelength conversion member) with one or more other layers such as a barrier film described later. It may be. Specifically, the wavelength conversion layer can be obtained by applying a polymerizable composition (curable composition) containing a phosphor on a suitable substrate and then performing a curing treatment by light irradiation or the like.

  The phosphor may be added to the polymerizable composition (coating liquid) for forming the wavelength conversion layer in the form of particles, or may be added in the form of a dispersion dispersed in a solvent. Addition in the state of a dispersion is preferable from the viewpoint of suppressing aggregation of phosphor particles. The solvent used here is not particularly limited. For example, about 0.01 to 10 parts by mass of the phosphor can be added to 100 parts by mass of the total amount of the coating solution.

  The polymerizable compound used for preparing the polymerizable composition is not particularly limited. One type of polymerizable compound may be used, or two or more types may be mixed and used. The content of all polymerizable compounds in the total amount of the polymerizable composition is preferably about 10 to 99.99% by mass. As an example of a preferable polymerizable compound, monofunctional or polyfunctional (monofunctional or polyfunctional (meth) acrylate monomer, its polymer, prepolymer, etc.) from the viewpoint of transparency and adhesion of the cured film after curing. Mention may be made of (meth) acrylate compounds. In addition, in this invention and this specification, description with "(meth) acrylate" shall be used by the meaning of at least one of an acrylate and a methacrylate, or either. The same applies to “(meth) acryloyl” and the like.

  Monofunctional (meth) acrylate monomers include acrylic acid and methacrylic acid, derivatives thereof, and more specifically, monomers having one polymerizable unsaturated bond ((meth) acryloyl group) of (meth) acrylic acid in the molecule Can be mentioned. Reference can be made to WO2012 / 0777807A1 paragraph 0022 for specific examples thereof.

  Polyfunctional (meth) acrylate monomer having two or more (meth) acryloyl groups in the molecule together with a monomer having one polymerizable unsaturated bond ((meth) acryloyl group) in one molecule. Can also be used together. The details can be referred to WO2012 / 0777807A1 paragraph 0024. Moreover, what is described in Unexamined-Japanese-Patent No. 2013-043382 Paragraphs 0023-0036 can also be used as a polyfunctional (meth) acrylate compound. Furthermore, it is also possible to use an alkyl chain-containing (meth) acrylate monomer represented by general formulas (4) to (6) described in paragraphs 0014 to 0017 of Japanese Patent No. 5129458.

  The amount of the polyfunctional (meth) acrylate monomer used is preferably 5 parts by mass or more from the viewpoint of coating strength with respect to 100 parts by mass of the total amount of polymerizable compounds contained in the polymerizable composition. From the viewpoint of suppressing the gelation of the product, it is preferably 95 parts by mass or less. From the same viewpoint, the amount of the monofunctional (meth) acrylate monomer used is 5 parts by mass or more and 95 parts by mass or less with respect to 100 parts by mass of the total amount of the polymerizable compounds contained in the polymerizable composition. Is preferred.

  Preferred examples of the polymerizable compound include compounds having a cyclic group such as a cyclic ether group capable of ring-opening polymerization such as an epoxy group and an oxetanyl group. More preferable examples of such a compound include compounds having an epoxy group-containing compound (epoxy compound). JP, 2011-159924, A paragraphs 0029-0033 can be referred to for an epoxy compound.

  The polymerizable composition can contain a known radical polymerization initiator or cationic polymerization initiator as a polymerization initiator. About a polymerization initiator, JP, 2013-043382, A paragraph 0037 and JP, 2011-159924, A paragraphs 0040-0042 can be referred to, for example. The polymerization initiator is preferably 0.1 mol% or more, more preferably 0.5 to 5 mol% of the total amount of the polymerizable compounds contained in the polymerizable composition.

  As long as the wavelength conversion layer is a layer containing the components described above and known additives that can be optionally added, the formation method is not particularly limited. Polymerization such as light irradiation and heating after applying the composition described above and one or more known additives added as necessary, simultaneously or sequentially onto a suitable substrate. A wavelength conversion layer containing a phosphor in the matrix can be formed by performing treatment and polymerizing and curing. The amount of additive used is not particularly limited and can be set as appropriate. Moreover, you may add a solvent as needed for the viscosity etc. of a composition. In this case, the type and amount of the solvent used are not particularly limited. For example, one or a mixture of two or more organic solvents can be used as the solvent.

  The polymerizable composition is applied onto a suitable substrate, dried as necessary to remove the solvent, and then polymerized and cured by light irradiation or the like to obtain a wavelength conversion layer. Application methods include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, wire bar method, etc. A well-known coating method is mentioned. The curing conditions can be appropriately set according to the type of polymerizable compound used and the composition of the polymerizable composition.

  The polymerization treatment of the polymerizable composition may be performed by any method, but as one aspect, it can be performed in a state where the polymerizable composition is sandwiched between two substrates. One aspect of the manufacturing process of the wavelength conversion member including such a polymerization process will be described below with reference to the drawings. However, the present invention is not limited to the following embodiments.

FIG. 3 is a schematic configuration diagram of an example of the wavelength conversion member manufacturing apparatus 100, and FIG. 4 is a partial enlarged view of the manufacturing apparatus shown in FIG. The manufacturing process of the wavelength conversion member using the manufacturing apparatus 100 shown in FIGS.
Applying a polymerizable composition containing a phosphor to the surface of a first substrate (hereinafter also referred to as “first film”) that is continuously conveyed to form a coating film;
A second substrate (hereinafter also referred to as “second film”) that is continuously conveyed is laminated (overlapped) on the coating film, and the first film and the second film are coated. A process of sandwiching
In a state where the coating film is sandwiched between the first film and the second film, either the first film or the second film is wound around a backup roller and irradiated with light while being continuously conveyed. A step of polymerizing and curing to form a wavelength conversion layer (cured layer);
At least. By using a barrier film having a barrier property against oxygen or moisture as either the first base material or the second base material, a wavelength conversion member having one surface protected by the barrier film can be obtained. Moreover, the wavelength conversion member by which both surfaces of the wavelength conversion layer were protected by the barrier film can be obtained by using a barrier film as a 1st base material and a 2nd base material, respectively.

  More specifically, first, the first film 10 is continuously conveyed to the coating unit 20 from a delivery machine (not shown). For example, the first film 10 is sent out from the sending machine at a conveying speed of 1 to 50 m / min. However, it is not limited to this conveyance speed. When delivered, for example, a tension of 20 to 150 N / m, preferably 30 to 100 N / m, is applied to the first film 10.

  In the coating unit 20, a polymerizable composition containing a phosphor (hereinafter also referred to as “coating liquid”) is applied to the surface of the first film 10 that is continuously conveyed, and the coating film 22 (see FIG. 4). Is formed. In the coating unit 20, for example, a die coater 24 and a backup roller 26 disposed to face the die coater 24 are installed. The surface of the first film 10 opposite to the surface on which the coating film 22 is formed is wound around the backup roller 26, and the coating liquid is applied from the discharge port of the die coater 24 onto the surface of the first film 10 that is continuously conveyed. As a result, the coating film 22 is formed. Here, the coating film 22 refers to a coating solution applied on the first film 10 before the polymerization treatment.

  In the present embodiment, the die coater 24 to which the extrusion coating method is applied is shown as the coating apparatus, but the present invention is not limited to this. For example, a coating apparatus to which various methods such as a curtain coating method, an extrusion coating method, a rod coating method, or a roll coating method are applied can be used.

  The first film 10 that has passed through the coating unit 20 and has the coating film 22 formed thereon is continuously conveyed to the laminating unit 30. In the laminating unit 30, the second film 50 that is continuously conveyed is laminated on the coating film 22, and the coating film 22 is sandwiched between the first film 10 and the second film 50.

  The laminating unit 30 is provided with a laminating roller 32 and a heating chamber 34 surrounding the laminating roller 32. The heating chamber 34 is provided with an opening 36 for allowing the first film 10 to pass therethrough and an opening 38 for allowing the second film 50 to pass therethrough.

  A backup roller 62 is disposed at a position facing the laminating roller 32. The first film 10 on which the coating film 22 is formed is wound around the backup roller 62 on the surface opposite to the surface on which the coating film 22 is formed, and is continuously conveyed to the laminating position P. The laminating position P means a position where the contact between the second film 50 and the coating film 22 starts. The first film 10 is preferably wound around the backup roller 62 before reaching the laminating position P. This is because even if wrinkles occur in the first film 10, the wrinkles are corrected by the backup roller 62 before reaching the laminate position P and can be removed. Accordingly, the position where the first film 10 is wound around the backup roller 62 (contact position) and the distance L1 to the laminating position P are preferably longer, for example, 30 mm or more is preferable, and the upper limit is usually It is determined by the diameter of the backup roller 62 and the pass line.

  In the present embodiment, the second film 50 is laminated by the backup roller 62 and the laminating roller 32 used in the polymerization processing unit 60. That is, the backup roller 62 used in the polymerization processing unit 60 is also used as a roller used in the laminating unit 30. However, the present invention is not limited to the above form, and a laminating roller may be installed in the laminating unit 30 in addition to the backup roller 62 so that the backup roller 62 is not used.

  By using the backup roller 62 used in the polymerization processing unit 60 in the laminating unit 30, the number of rollers can be reduced. The backup roller 62 can also be used as a heat roller for the first film 10.

  The second film 50 delivered from a delivery machine (not shown) is wound around the laminating roller 32 and continuously conveyed between the laminating roller 32 and the backup roller 62. The second film 50 is laminated on the coating film 22 formed on the first film 10 at the laminating position P. Accordingly, the coating film 22 is sandwiched between the first film 10 and the second film 50. Lamination refers to laminating the second film 50 on the coating film 22.

  The distance L2 between the laminating roller 32 and the backup roller 62 is a value of the total thickness of the first film 10, the wavelength conversion layer (cured layer) 28 obtained by polymerizing and curing the coating film 22, and the second film 50. The above is preferable. Moreover, it is preferable that L2 is below the length which added 5 mm to the total thickness of the 1st film 10, the coating film 22, and the 2nd film 50. FIG. By setting the distance L2 to be equal to or shorter than the total thickness plus 5 mm, it is possible to prevent bubbles from entering between the second film 50 and the coating film 22. Here, the distance L <b> 2 between the laminating roller 32 and the backup roller 62 refers to the shortest distance between the outer peripheral surface of the laminating roller 32 and the outer peripheral surface of the backup roller 62.

  The rotational accuracy of the laminating roller 32 and the backup roller 62 is 0.05 mm or less, preferably 0.01 mm or less in radial runout. The smaller the radial runout, the smaller the thickness distribution of the coating film 22.

  Further, in order to suppress thermal deformation after the coating film 22 is sandwiched between the first film 10 and the second film 50, the temperature of the backup roller 62 of the polymerization processing unit 60 and the temperature of the first film 10 are The difference and the difference between the temperature of the backup roller 62 and the temperature of the second film 50 are preferably 30 ° C. or less, more preferably 15 ° C. or less, and most preferably the same.

  In order to reduce the difference from the temperature of the backup roller 62, when the heating chamber 34 is provided, it is preferable to heat the first film 10 and the second film 50 in the heating chamber 34. For example, hot air is supplied to the heating chamber 34 by a hot air generator (not shown), and the first film 10 and the second film 50 can be heated.

  The first film 10 may be heated by the backup roller 62 by being wound around the temperature-adjusted backup roller 62.

On the other hand, the second film 50 can be heated by the laminating roller 32 by using the laminating roller 32 as a heat roller.
However, the heating chamber 34 and the heat roller are not essential and can be provided as necessary.

  Next, the film 22 is continuously conveyed to the polymerization processing unit 60 in a state where the coating film 22 is sandwiched between the first film 10 and the second film 50. In the embodiment shown in the drawing, the polymerization treatment in the polymerization treatment unit 60 is performed by light irradiation, but when the polymerizable compound contained in the coating liquid is polymerized by heating, by heating such as blowing hot air, A polymerization process can be performed.

A light irradiation device 64 is provided at a position facing the backup roller 62 and the backup roller 62. The first film 10 and the second film 50 sandwiching the coating film 22 are continuously conveyed between the backup roller 62 and the light irradiation device 64. What is necessary is just to determine the light irradiated by a light irradiation apparatus according to the kind of photopolymerizable compound contained in a coating liquid, and an ultraviolet-ray is mentioned as an example. As a light source that generates ultraviolet rays, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. What is necessary is just to set the light irradiation amount to the range which can advance the polymerization hardening of a coating film, for example, the ultraviolet-ray of the irradiation amount of 100-10000mJ / cm < ² > can be irradiated toward the coating film 22 as an example.

  In the polymerization processing unit 60, the first film 10 and the second film 50 sandwich the coating film 22, the first film 10 is wound around the backup roller 62, and the light irradiation device 64 is continuously conveyed. The wavelength conversion layer (cured layer) 28 can be formed by irradiating with light and curing the coating film 22.

  In the present embodiment, the first film 10 side is wound around the backup roller 62 and continuously conveyed, but the second film 50 may be wound around the backup roller 62 and continuously conveyed.

  Wrapping around the backup roller 62 means a state in which either the first film 10 or the second film 50 is in contact with the surface of the backup roller 62 at a certain wrap angle. Accordingly, the first film 10 and the second film 50 move in synchronization with the rotation of the backup roller 62 while being continuously conveyed. Winding around the backup roller 62 may be at least during the irradiation of ultraviolet rays.

  The backup roller 62 includes a cylindrical body and rotation shafts disposed at both ends of the body. The main body of the backup roller 62 has a diameter of φ200 to 1000 mm, for example. There is no restriction on the diameter φ of the backup roller 62. In consideration of curl deformation, equipment cost, and rotation accuracy, the diameter is preferably 300 to 500 mm. The temperature of the backup roller 62 can be adjusted by attaching a temperature controller to the main body of the backup roller 62.

  The temperature of the backup roller 62 takes into consideration the heat generation during light irradiation, the curing efficiency of the coating film 22, and the occurrence of wrinkle deformation on the backup roller 62 of the first film 10 and the second film 50. Can be determined. For example, the backup roller 62 is preferably set to a temperature range of 10 to 95 ° C, and more preferably 15 to 85 ° C. Here, the temperature related to the roller refers to the surface temperature of the roller.

  A distance L3 between the laminate position P and the light irradiation device 64 can be set to, for example, 30 mm or more.

  The coating film 22 becomes the cured layer 28 by light irradiation, and the wavelength conversion member 70 including the first film 10, the cured layer 28, and the second film 50 is manufactured. The wavelength conversion member 70 is peeled from the backup roller 62 by the peeling roller 80. The wavelength conversion member 70 is continuously conveyed to a winder (not shown), and then the wavelength conversion member 70 is wound into a roll by the winder.

  As mentioned above, although the one aspect | mode of the manufacturing process of the wavelength conversion member was demonstrated, this invention is not limited to the said aspect. For example, a wavelength conversion is performed by applying a polymerizable composition containing a phosphor on a base material, and performing a polymerization process after a drying process as needed without laminating a further base material on the base material. A layer (cured layer) may be produced. One or more other layers may be laminated on the prepared wavelength conversion layer by a known method. Moreover, it is also possible to use the light control layer whose details will be described later as a base material.

  The total thickness of the wavelength conversion layer is preferably in the range of 1 to 500 μm, more preferably in the range of 10 to 120 μm. Further, the wavelength conversion layer may have a laminated structure in which two or more layers of phosphors having different emission characteristics are included in different layers, and two or more types of phosphors having different emission characteristics are included in the same layer. Also good.

(3-3. Layer that can be laminated with wavelength conversion layer, support)
The wavelength conversion layer may be included in the backlight unit only as a wavelength conversion layer or as a laminate having a support described later in addition to the wavelength conversion layer. Or it can also have at least one layer chosen from the group which consists of an inorganic layer and an organic layer in the at least one main surface of a wavelength conversion layer. As such an inorganic layer and an organic layer, the inorganic layer and organic layer which comprise the below-mentioned barrier film can be mentioned.

-Support-
The laminate (wavelength conversion member) including the wavelength conversion layer may have a support for improving strength, easiness of film formation, and the like. The support may be included as a layer adjacent to or directly in contact with the wavelength conversion layer, or may be included as a base film of a barrier film described later. In the wavelength conversion member, the support may be included so that the inorganic layer described below and the support are in this order, and the wavelength conversion layer, the inorganic layer described below, the organic layer described below, and the support include They may be included in order. A support may be disposed between the organic layer and the inorganic layer, between the two organic layers, or between the two inorganic layers. One or more supports may be included in the wavelength conversion member, and the wavelength conversion member has a structure in which the support, the wavelength conversion layer, and the support are laminated in this order. May be. The support is preferably a transparent support that is transparent to visible light. Here, being transparent to visible light means that the light transmittance in the visible light region is 80% or more, preferably 85% or more. The light transmittance used as a measure of transparency is measured by measuring the total light transmittance and the amount of scattered light using the method described in JIS-K7105, that is, using an integrating sphere light transmittance measuring device, and diffusing transmission from the total light transmittance. It can be calculated by subtracting the rate. JP, 2007-290369, A paragraphs 0046-0052 and JP, 2005-096108, A paragraphs 0040-0055 can be referred to for a support. The thickness of the support is preferably in the range of 10 to 500 μm, more preferably in the range of 20 to 400 μm, and particularly in the range of 25 to 150 μm, from the viewpoints of gas barrier properties, impact resistance and the like.
The support can also be used as the substrate described above. Moreover, a support body can also be used for either the above-mentioned 1st film and 2nd film, or both. When both the first film and the second film are supports, they may be the same or different.

-Barrier film-
The wavelength conversion member preferably includes a barrier film. A barrier film is a film having a gas barrier function of blocking oxygen. It is also preferable that the barrier film has a function of blocking water vapor.
The barrier film is preferably contained in the wavelength conversion member as a layer adjacent to or directly in contact with the wavelength conversion layer. In addition, one or more barrier films may be included in the wavelength conversion member, and the wavelength conversion member has a structure in which a barrier film, a wavelength conversion layer, and a barrier film are laminated in this order. Preferably it is.
In the wavelength conversion member, the wavelength conversion layer may be formed using a barrier film as a base material. The barrier film can also be used for either or both of the first film and the second film described above. When both the first film and the second film are barrier films, they may be the same or different.

The barrier film may be any known barrier film, for example, a barrier film described below.
The barrier film usually only needs to include at least an inorganic layer, and may be a film including a base film and an inorganic layer. For the base film, the description of the support can be referred to. The barrier film may include a barrier laminate including at least one inorganic layer and at least one organic layer on the base film. Thus, by laminating a plurality of layers, the barrier property can be further enhanced. On the other hand, as the number of layers to be stacked increases, the light transmittance of the wavelength conversion member tends to decrease. Therefore, it is desirable to increase the number of layers within a range in which good light transmittance can be maintained. Specifically, the barrier film preferably has a total light transmittance of 80% or more in the visible light region and an oxygen permeability of 1 cm ³ / (m ² · day · atm) or less. Here, the oxygen permeability is a value measured using an oxygen gas permeability measuring device (manufactured by MOCON, OX-TRAN 2/20: trade name) under the conditions of a measurement temperature of 23 ° C. and a relative humidity of 90%. It is. The visible light region means a wavelength region of 380 to 780 nm, and the total light transmittance indicates an average value of light transmittance over the visible light region.
The oxygen permeability of the barrier film is more preferably 0.1 cm ³ / (m ² · day · atm) or less, and more preferably 0.01 cm ³ / (m ² · day · atm) or less. The total light transmittance in the visible light region is more preferably 90% or more. The lower the oxygen permeability, the better, and the higher the total light transmittance in the visible light region, the better.

-Inorganic layer-
The “inorganic layer” is a layer mainly composed of an inorganic material, and is preferably a layer formed only from an inorganic material. On the other hand, the organic layer is a layer mainly composed of an organic material, and preferably refers to a layer in which the organic material occupies 50% by mass or more, more preferably 80% by mass or more, and particularly 90% by mass or more. To do.
The inorganic material constituting the inorganic layer is not particularly limited, and for example, various inorganic compounds such as metals or inorganic oxides, nitrides, oxynitrides, and the like can be used. As an element constituting the inorganic material, silicon, aluminum, magnesium, titanium, tin, indium and cerium are preferable, and one or two or more of these may be included. Specific examples of the inorganic compound include silicon oxide, silicon oxynitride, aluminum oxide, magnesium oxide, titanium oxide, tin oxide, indium oxide alloy, silicon nitride, aluminum nitride, and titanium nitride. As the inorganic layer, a metal film such as an aluminum film, a silver film, a tin film, a chromium film, a nickel film, or a titanium film may be provided.

Among the above materials, silicon nitride, silicon oxide, or silicon oxynitride is particularly preferable. This is because the inorganic layer made of these materials has a good adhesion to the organic layer, and thus the barrier property can be further enhanced.
A method for forming the inorganic layer is not particularly limited, and various film forming methods that can evaporate or scatter the film forming material and deposit it on the deposition surface can be used.

  Examples of the method for forming the inorganic layer include a vacuum evaporation method in which an inorganic material such as an inorganic oxide, an inorganic nitride, an inorganic oxynitride, or a metal is heated and evaporated; an inorganic material is used as a raw material, and oxygen gas is introduced. Oxidation reaction vapor deposition method for oxidizing and vapor-depositing; Sputtering method for vapor deposition by introducing and sputtering argon gas and oxygen gas using an inorganic material as a target raw material; When a vapor deposition film of silicon oxide is formed by a physical vapor deposition method (Physical Vapor Deposition method) such as ion plating, which is heated by a heated plasma beam, the plasma chemical vapor is generated from an organosilicon compound. Examples thereof include a phase growth method (Chemical Vapor Deposition method). Vapor deposition may be performed on the surface of a substrate, a base film, a wavelength conversion layer, an organic layer, or the like as a substrate.

  The thickness of the inorganic layer is, for example, 1 nm to 500 nm, preferably 5 nm to 300 nm, and more preferably 10 nm to 150 nm. When the film thickness of the inorganic layer is within the above-described range, it is possible to suppress reflection in the inorganic layer while realizing good barrier properties, and to provide a wavelength conversion member with higher light transmittance. Because it can.

  The wavelength conversion member preferably includes at least one inorganic layer adjacent to the wavelength conversion layer, preferably in direct contact with the wavelength conversion layer. It is also preferable that the inorganic layer is in direct contact with both surfaces of the wavelength conversion layer.

-Organic layer-
JP, 2007-290369, A paragraphs 0020-0042 and JP, 2005-096108, A paragraphs 0074-0105 can be referred to as an organic layer. The organic layer preferably contains a cardo polymer. Thereby, the adhesiveness between the organic layer and the adjacent layer, particularly the adhesiveness with the inorganic layer is improved, and a further excellent gas barrier property can be realized. JP, 2005-096108, A paragraphs 0085-0095 can be referred to for the details of a cardo polymer. The thickness of the organic layer is preferably in the range of 0.05 μm to 10 μm, and more preferably in the range of 0.5 to 10 μm. When the organic layer is formed by a wet coating method, the film thickness of the organic layer is preferably in the range of 0.5 to 10 μm, and more preferably in the range of 1 μm to 5 μm. Moreover, when formed by the dry coating method, it is preferable that it exists in the range of 0.05 micrometer-5 micrometers, especially in the range of 0.05 micrometer-1 micrometer. This is because when the film thickness of the organic layer formed by the wet coating method or the dry coating method is within the above-described range, the adhesion with the inorganic layer can be further improved.

  Regarding other details of the inorganic layer and the organic layer, reference can be made to JP-A-2007-290369, JP-A-2005-096108 and US2012 / 0113672A1.

  A known adhesive layer may be bonded between the organic layer and the inorganic layer, between the two organic layers, or between the two inorganic layers. From the viewpoint of improving light transmittance, it is preferable that the number of adhesive layers is small, and it is more preferable that no adhesive layer is present.

<4. Light control layer>
Next, details of the light control layer disposed between the light emitting unit and the wavelength conversion layer described above will be described.
The oblique incident light linear transmittance reduction function exhibited by the light control layer is as described above. The light control layer may have a function of reducing the total light transmittance as well as the function of reducing the oblique incident light linear transmittance. The oblique incident light linear transmittance reduction function is preferably realized by one or more actions selected from the group consisting of light interference, scattering, refraction, and reflection by the light control layer.

A specific aspect of the light control layer capable of exhibiting the function of reducing the obliquely incident light linear transmittance by one or more selected from the group consisting of the above actions will be described below. However, the present invention is not limited to the following specific modes, and various types of light control layers having a function of reducing the oblique incident light linear transmittance can be included in the backlight unit.
In one aspect, the backlight unit includes at least a diffusion member as at least one member selected from the group consisting of a diffusion member and a light guide member, and has a light control layer between the diffusion member and the wavelength conversion layer. .
In another aspect, the backlight unit includes at least a diffusion member as at least one member selected from the group consisting of a diffusion member and a light guide member, and performs light control between the diffusion member and the light emitting unit. Has a layer.
The arrangement of the light control layer, the wavelength conversion layer, and the like will be further described later.

(4-1. Light control layer mainly using light interference)
One aspect of the light control layer is mainly a layer that can exhibit a function of reducing the linearly incident light linear transmittance by light interference. As such a light control layer, for example, a layer that causes a plurality of light beams to interfere with each other by a refractive index distribution or a dielectric constant distribution provided with regularity can be used. In addition, the interference effect is usually dependent on the wavelength of the light that acts, and a layer that selectively interferes only with light in a specific wavelength band can be formed by a known optical design. It can also be used as a control layer.

  In one embodiment, the light control layer is a reflective polarizer. Note that the polarizers (viewing-side polarizer and backlight-side polarizer) normally arranged on the liquid crystal panel with respect to the reflective polarizer are polarizers for turning on and off the light transmitted through the liquid crystal cell. A polarizer (absorbing polarizer) having the property of absorbing light that does not pass through. Hereinafter, unless otherwise specified, the polarizer refers to an absorbing polarizer. Moreover, a polarizing plate shall mean the member which contains a reflective polarizer or an absorption polarizer, and may contain other components, such as a protective film. Unless otherwise specified, the polarizing plate refers to a polarizing plate including an absorbing polarizer.

(4-1-1. Polymer layer having cholesteric liquid crystallinity)
As one embodiment of a light control layer that mainly uses light interference, a polymer layer having cholesteric liquid crystallinity (hereinafter also referred to as a cholesteric liquid crystal layer) can be given. A cholesteric liquid crystal compound appropriately adjusts its spiral direction and spiral pitch by utilizing the fact that wavelength selectivity differs between when light is incident on the compound perpendicularly and when the incident angle is inclined. Thus, it is possible to show a characteristic of reflecting only a specific circularly polarized light component and transmitting the other circularly polarized light component. A cholesteric liquid crystal layer containing a cholesteric liquid crystal compound having such characteristics is suitable as a light control layer. For the formation of the cholesteric liquid crystal layer, for example, Fujifilm Research Report No. 50 (2005) pp. The cholesteric liquid crystal compound described in No. 60 can be suitably used. Further, for example, the helical pitch can be easily adjusted by changing the addition amount of the chiral agent. Specifically, Fujifilm research report No. 50 (2005) pp. There is a detailed description in 60-63. In addition, by combining the cholesteric liquid crystal layer with a retardation film or other optical film, it exhibits high linear transmittance for light incident at a specific range of incident angles, and exhibits reflectivity at other incident angles. It is also possible to add various functions.

  Examples of the chiral agent include chiral agents described in “Liquid Crystal Device Handbook”, Chapter 3-4-3, TN, chiral agent for STN, 199 pages, edited by Japan Society for the Promotion of Science, First 42nd Committee (1989). A known chiral agent can be used. Moreover, description of Unexamined-Japanese-Patent No. 2014-119605 paragraph 0054-0055 can also be referred about a chiral agent.

-Cholesteric liquid crystal compounds-
In one embodiment, the cholesteric liquid crystal compound can be a rod-like liquid crystal compound. In another embodiment, it can be a discotic liquid crystal compound. The cholesteric liquid crystal compound may be a polymerizable cholesteric liquid crystal compound. The polymerizable cholesteric liquid crystal compound is a cholesteric liquid crystal compound having one or more polymerizable groups in one molecule, and may be a polyfunctional compound having two or more polymerizable groups in one molecule, It may be a monofunctional compound having one polymerizable group in one molecule. The polymerizable group possessed by the polymerizable cholesteric liquid crystal compound is not particularly limited as long as it is a group capable of undergoing a polymerization reaction.

  Examples of the rod-like liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  Examples of the polymerizable rod-like liquid crystal compound include those described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648, 5,770,107, WO 95/22586, 95/24455, 97/97. No. 0600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and JP-A-2001-328773. Can be used.

  As the rod-like liquid crystal compound, for example, those described in JP-A-11-513019 and JP-A-2007-279688 can be preferably used.

  The discotic liquid crystal compound is not particularly limited, and examples thereof include compounds described in JP2007-108732A and JP2010-244038A as preferable compounds.

  Although the preferable example of a disk shaped liquid crystal compound is shown below, this invention is not limited to these.

  Moreover, a liquid crystal polymer can also be used as a cholesteric liquid crystal compound. As the liquid crystal polymer, for example, main chain type liquid crystal polymer such as polyester, side chain type liquid crystal polymer composed of acrylic main chain, methacryl main chain, siloxane main chain, etc., low molecular chiral agent-containing nematic liquid crystal polymer, chiral component introduced liquid crystal Appropriate ones such as a polymer, a mixed liquid crystal polymer of nematic type and cholesteric type can be used. A glass transition temperature of 30 to 150 ° C. is preferable from the viewpoint of handleability.

  The cholesteric liquid crystal layer can be formed by applying it directly to the polarization separator through an appropriate alignment film such as polyimide, polyvinyl alcohol, or obliquely deposited layer of SiO, or the alignment temperature of the liquid crystal polymer comprising a transparent film. It can be carried out by an appropriate method such as a method of applying to an unaltered support through an alignment film, if necessary. As the support, it is preferable to use a support having a phase difference as small as possible from the viewpoint of preventing the change of the polarization state. A superposition method of a cholesteric liquid crystal layer through an alignment film can also be employed.

  The liquid crystal polymer can be applied by a method in which a liquid material such as a solvent solution or a molten liquid is heated by an appropriate method such as a roll coating method, a gravure printing method, or a spin coating method.

-Other ingredients-
The composition used for forming the cholesteric liquid crystal layer may contain other components such as a chiral agent, an alignment controller, a polymerization initiator, and an alignment aid in addition to the cholesteric liquid crystal compound.

  Examples of the orientation control agent include compounds exemplified in paragraphs 0092 and 0093 of JP-A-2005-99248, and paragraphs 0076 to 0078 and paragraphs 0082 to 0085 of JP-A-2002-129162. Examples thereof include compounds, compounds exemplified in paragraphs 0094 and 0095 of JP-A-2005-99248, and compounds exemplified in paragraph 0096 of JP-A-2005-99248.

  Further, as the alignment control agent, a fluorine-based alignment control agent can also be used. As a fluorine-type orientation control agent, the compound represented by general formula (I) shown by Unexamined-Japanese-Patent No. 2013-203827 paragraph 0100 can be mentioned as a preferable thing, for example. JP, 2013-203827, A paragraphs 0101-0108 can be referred to for the details of such a compound.

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970), acylphosphine Oxide compounds (Japanese Patent Publication No. 63-40 No. 799, JP-B-5-29234, JP-A-10-95788, JP-A-10-29997) and the like.

  As a method for producing the cholesteric liquid crystal layer, known techniques can be applied without any limitation. For example, the cholesteric liquid crystal layer can be produced by the methods described in JP-A-1-133003, JP-A-3416302, JP-A-3363565, and JP-A-8-271731. As an example, reference can be made to paragraphs 0012 to 0015 of JP-A-8-271731.

The cholesteric liquid crystal layer described above can function as a reflective polarizer in one embodiment. The reflective polarizer can be a selective reflection polarizer (narrowband reflective polarizer) that selectively functions as a reflective polarizer for light in a certain wavelength band.
On the other hand, a normal reflective polarizer is a reflective polarizer (broadband reflective polarizer) that can function as a reflective polarizer for light in a wider wavelength range than a selective reflective polarizer. Such a reflective polarizer (broadband reflective polarizer) can also be used as the light control layer. It is more preferable to use the broadband reflective polarizer as a member disposed at a position closest to the light-emitting portion side of the wavelength conversion layer or the wavelength conversion member including this layer.
In addition, in this invention and this specification, a broadband reflective polarizer means the reflective polarizer which shows a reflectance of 15% or more over the whole wavelength band of 430-680 nm. On the other hand, a narrow-band reflective polarizer refers to a reflective polarizer having a wavelength or wavelength range in which the reflectance is less than 15% in the wavelength band of 430 to 680 nm.

  As the selective reflection polarizer, for example, a selective reflection polarizer (blue light selective reflection polarizer) having a reflection maximum wavelength in the wavelength band of blue light, and a selective reflection polarizer (green) having a reflection maximum wavelength in the wavelength band of green light. Light selective reflection polarizer) and a selective reflection polarizer (red light selective reflection polarizer) having a reflection maximum wavelength in the wavelength band of red light. Also, two or more kinds of selective reflection polarizers can be laminated and used as a light control layer.

  In one aspect, it is preferable to use a selective reflection polarizer capable of selectively reflecting light emitted from the phosphor contained in the wavelength conversion layer as the light control layer from the viewpoint of reducing tint. Furthermore, such a selective reflection polarizer can be used as a member disposed at a position closest to the wavelength conversion member on the light source side of the wavelength conversion layer or the wavelength conversion member including this layer. From the viewpoint, it is more preferable.

  In another aspect, the selective reflection polarizer preferably has at least one reflection peak having a reflection maximum wavelength in the wavelength band of blue light to green light of 430 to 560 nm in the reflection spectrum. In the present invention and the present specification, unless otherwise specified, the reflection characteristic is a reflection characteristic defined for normal incidence light (light incident from the front). On the other hand, in the selective reflection polarizer, generally, the reflection peak for obliquely incident light tends to shift to the shorter wavelength side than the reflection peak for directly incident light. Therefore, for example, when using a light source that emits blue light, in order to reduce the tint caused by the occurrence of the above (2), the maximum reflected wavelength in the wavelength band of blue light to green light with respect to the direct incident light It is thought that the light quantity of the stray light described above can be reduced by the selective reflection polarizer having at least one reflection peak having the above.

  By the way, in order to reduce both coloring due to the causes of occurrence of the above (1) and (2), in one aspect, it is considered that a light control layer having a light control action in a wide band is effective. On the other hand, from the viewpoint of coexistence of the luminance control of the portion to be displayed darkly and the front luminance of the portion to be displayed brightly, the wavelength dependence of the light control layer having the light control function in a narrow band is appropriately set. It has been newly found by the present inventors that it is preferable to do this. Considering this point, it is preferable to use a selective reflection polarizer as the light control layer. As an example, the selective reflection polarizer has a single reflection peak in the wavelength band of blue light to red light of 430 to 680 nm, and the reflection maximum wavelength of this reflection peak is in the wavelength band of green light of 520 to 560 nm. It is preferable. This is because such a reflective polarizer is considered to be capable of reducing the amount of blue stray light for the reasons described above.

  The details of the reflective polarizer and the selective reflection polarizer described above are applied to modes other than the cholesteric liquid crystal layer. For example, the reflective polarizer and the selective reflection polarizer are also applied to an embodiment in which a multilayer film is formed by laminating a plurality of layers having different refractive indexes, which will be described later.

(4-1-2. Multilayer film in which a plurality of layers having different refractive indexes are laminated)
An example of a light control layer that mainly uses light interference is a multilayer film in which a plurality of layers having different refractive indexes are stacked. In one embodiment, such a multilayer film can function as a reflective polarizer. A multilayer film having a function as a reflective polarizer can be obtained by laminating a plurality of layers in a combination having in-plane anisotropy in the interlayer refractive index difference. Note that the plurality of layers included in the multilayer film only need to have at least two adjacent layers having different refractive indexes, and a plurality of layers having the same refractive index may be included through other one or more layers. Such an embodiment is also preferable. In the present invention, the refractive index means a refractive index with respect to Fraunhofer's e-line (546.1 nm).
The layer constituting the multilayer film may be an inorganic layer or an organic layer. For example, a dielectric multilayer film formed by sequentially laminating materials having different refractive indexes (high refractive index material, low refractive index material) can be suitably used. Furthermore, a metal / dielectric multilayer film obtained by adding a metal film to the layer structure of the dielectric multilayer film may be used. The multilayer film can be formed by depositing a plurality of film forming materials on a substrate by a known film forming method such as EB (Electron Beam) evaporation (electron beam co-evaporation) or sputtering.
A multilayer film including an organic layer can be formed by a known film formation method such as coating or laminating. As the organic layer, for example, a stretched film can be used.

  For a laminate (multilayer film) of stretched films of two or more layers, for example, U.S. Pat. No. 5,882,774 and JP 2012-237853 A can be referred to. Moreover, as such a laminated body, you may use commercial items, such as DBEF (trademark) by Sumitomo 3M, for example. By using a stretched film having an anisotropic refractive index, a multilayer film that can function as a reflective polarizer can be obtained. In particular, a multilayer film in which two layers of stretched films with different refractive index anisotropies are superimposed exhibits a function of reducing the oblique incident light linear transmittance by controlling the thickness direction refractive index difference between the two layers of stretched films. Can be designed as

  In addition, for example, a multilayer film in which two inorganic layers having different refractive indexes are alternately superimposed is known as a bandpass filter or a cold mirror. A multilayer film in which two organic layers having different refractive indexes are alternately superimposed is also known. These multilayer films are also suitable as the light control layer. Examples of such a multilayer film include those disclosed as a viewing angle control film in JP2011-39277A, and those disclosed as multicolor interference coating in JP8-332450A. . In particular, a multilayer film in which two organic layers having different refractive indexes are alternately superposed has a function of reducing the oblique incident light linear transmittance by controlling the difference in refractive index in the thickness direction between the two organic layers. Can be designed to

  When producing a selective reflection polarizer as a multilayer film, once the wavelength band to be reflected is determined, the layer structure of the multilayer film that selectively reflects light in this wavelength band (combination of film forming materials, film of each layer) (Thickness) can be determined by a known film design method.

(4-1-3. Other Specific Mode of Light Control Layer Mainly Utilizing Light Interference)
As another specific embodiment of the light control layer mainly utilizing light interference, the light control layer has a refractive index different from that of the substrate on or in the substrate (preferably a substrate transparent to visible light). It is also possible to provide a reflective polarization separation element capable of exhibiting a light interference effect by arranging a material or a reflective material such as a metal to be miniaturized and aligning them. Examples of such a reflective polarizing molecular element include those disclosed in JP 2002-502503A as direction control polarizers, and JP 2011-53705A as direction control polarizers. The thing etc. can be mentioned. Such a reflective polarization separation element includes what is called a wire grid polarizer. What is marketed as a wire grid polarizer can also be used as the light control layer.

(4-2. Light control layer mainly using light scattering)
Another embodiment of the light control layer may include a light scattering layer. The light scattering layer is a layer that can exhibit a function of reducing the linearly incident light linear transmittance mainly by light scattering.

  One aspect of the light scattering layer is a light scattering film having a function of emitting incident light as scattered light having a distribution obtained by changing the direction of light in a random direction, or a laminate of two or more layers of such a film. It is. As such a light scattering film, various known films can be used. For example, a film in which a mixture of light scattering particles and a binder is coated on a substrate (preferably on a substrate transparent to visible light), or light scattering particles are placed in the substrate (preferably visible light). The surface of a film or substrate (preferably a substrate transparent to visible light) contained in a transparent substrate is roughened by a blasting method or a transfer method to impart light scattering properties. Examples of the film include a film, a layer separation structure formed by self-generation using layer separation, and the like, and a light scattering property. A light-scattering film is a film that can define specular reflection, diffuse reflection, linear transmission, diffuse transmission, and absorption components for incident light. The above components are specular reflectance, diffuse reflectance, linear transmittance, diffuse transmittance (the sum of linear transmittance and diffuse transmittance is referred to as total light transmittance), absorptance, as defined by Japanese Industrial Standards. These values may be set as appropriate so that the function of reducing the linearly incident light linear transmittance can be exhibited. As a specific embodiment of the light scattering layer, a known light scattering film (also referred to as a light diffusing film or sheet, a light diffuser, etc.), for example, disclosed as a light diffusing sheet in JP-A No. 2003-107214 Disclosed in Japanese Patent Application Laid-Open No. 2007-249185 as a light diffuser, disclosed in Japanese Patent Application Laid-Open No. 2009-223135 as a light diffusion film, and described in Japanese Patent Application Laid-Open No. 7-216328. Examples of the layer formed from the light diffusable pressure-sensitive adhesive composition, those disclosed as a light diffusable sheet in WO2011 / 074648, and the like.

Further, as the light scattering layer, a light scattering layer having specific scattering characteristics and outgoing light characteristics only for a specific incident angle or outgoing angle is also preferable. Such a light scattering layer is called an anisotropic light scattering layer. For example, a light scattering layer that is not scattering with respect to light incident perpendicularly to the surface of the layer and that exhibits strong scattering with respect to incident light at an inclined incident angle is an anisotropic light scattering layer that is preferable as a light control layer. is there. As such an anisotropic light scattering layer, for example, in the above-described known light scattering film, the light scattering particles and the layer separation structure are anisotropic, and a film prepared so that they are appropriately oriented, Examples thereof include a film in which a light scattering resin is provided in a pattern inside a substrate (preferably a substrate transparent to visible light). Specific examples include those disclosed as a light control plate in JP-A No. 64-77001, and those disclosed as a viewing angle limiting sheet in JP-A No. 2013-242550.
The anisotropic scattering layer is preferably one that strongly scatters light incident obliquely as compared to light incident vertically on the surface of this layer.

  Moreover, as a light-scattering layer, what a scattering characteristic depends on the wavelength of incident light is preferable. For example, as an example, it is preferable that the scattering characteristics in the light scattering layer of blue light, which is phosphor excitation light derived from the light source, and the scattering characteristics in the light scattering layer of green light and red light emitted from the phosphor are different. The wavelength dependence of such scattering characteristics can be controlled, for example, by adjusting the particle size of the light scattering particles.

(4-3. Light control layer mainly utilizing refraction, reflection, or refraction and reflection of light)
As a light control layer mainly utilizing light refraction, reflection, or refraction and reflection, light is refracted, reflected, or refracted and reflected by the surface structure of at least one of the light emitting portion side surface and the wavelength conversion layer side surface. The layer can be a layer that can refract, reflect, or refract and reflect light depending on the structure within the layer. For example, those that emit a unique light control action by the combination of refraction and reflection due to a regular structure such as a concavo-convex structure provided on the surface of the layer; Those that generate a light control action and combinations thereof can be used as the light control layer.

  Examples of the layer that can refract, reflect, or refract and reflect light depending on the surface structure include a prism layer having a surface uneven shape. Such a prism layer (generally referred to as a prism sheet) generally has directionality in a single layer, but it is also possible to cancel the directionality by stacking two prism layers so that the prism rows are orthogonal to each other. is there. Also, the apex angle of the convex part of the prism row, the refractive index of the prism layer, the light scattering characteristics of the material constituting the prism layer, the adjustment of the prism shape, the surface uneven structure is arranged on the light emitting part side surface, or the wavelength conversion layer side surface The refraction and reflection of light by this layer can be controlled depending on whether it is disposed on the surface. Examples of the prism layer having a surface concavo-convex structure include those disclosed as a brightness enhancement film in JP-T-2008-530346, those disclosed as brightness-enhancing articles in JP-T-2001-524225, and special tables. Examples thereof include those disclosed as microstructure-containing products or brightness enhancement films in JP-A-11-500071.

The prism sheet and a layer having a function similar to or more improved than the use of the prism sheet include, for example, those disclosed as a light control unit in Japanese Patent Application Laid-Open No. 2012-103495 (triangular pyramid surface structure) In Japanese Patent Application Laid-Open No. 6-235804, as a light control plate (having a conical surface structure), and as a viewing angle control optical member in Japanese Patent Application Laid-Open No. 2002-116307. For example, those having an appropriately designed surface structure such as those having a microlens-like surface structure.
However, the surface structure that can be used as the light control layer is not limited to the above-described shape. As long as the surface structure can function as the light control layer, a prismatic shape, a hemispherical shape, a combination of a plurality of different shapes, and a fractal It may be a complicated shape such as a structure.

  As a layer capable of refracting, reflecting, or refracting and reflecting light depending on the surface structure, in the plane direction (in-plane direction) of the substrate on the substrate (preferably a substrate transparent to visible light) The layer which has a partition-like structure which restrict | limits the light propagation of this can be mentioned. In addition, as a layer capable of refracting, reflecting, or refracting and reflecting light depending on the structure in the layer, a plane direction of the substrate (preferably a substrate transparent to visible light) ( And a layer having a partition-like structure that restricts light propagation in the in-plane direction). A layer having such a partition wall can exhibit an action of transmitting only a specific incident angle and emission angle and reflecting other components by the refraction and reflection action of the partition wall. Specific examples of the layer having a partition wall include those disclosed as a viewing angle control sheet in Japanese Patent Application Laid-Open No. 2007-279424 (a layer in which a partition wall is provided on a stripe), and a field of view in Japanese Patent Application Laid-Open No. 2005-338270. What is disclosed as an angle control sheet (a layer having a concave-convex structure as a partition), and those used in combination with an absorbing action, are disclosed as a viewing angle control sheet in JP-A-2006-84876, The thing currently disclosed by Unexamined-Japanese-Patent No. 2013-68855 as an optical path control filter can be illustrated.

  As a light control layer mainly using refraction, reflection, or refraction and reflection of light, there is a layer having a function of condensing light incident from one surface on the other surface side. For example, the prism layer can have a function of condensing light incident from a surface opposite to the surface having the surface uneven structure onto the surface side having the surface uneven structure. From the viewpoint of further reducing the tint, it is preferable that the light control layer is arranged such that the surface on the light collecting side is directed toward the light emitting unit.

Further, as the cholesteric liquid crystal layer or the multilayer film, a reflective layer that does not function as a reflective polarizer can be used as the light control layer. For example, a selective reflection layer that does not function as a reflective polarizer (without polarization selectivity) can be produced by laminating a plurality of layers in a combination having no in-plane anisotropy in the interlayer refractive index difference. Alternatively, by selectively laminating a cholesteric liquid crystal layer that transmits one of right circularly polarized light and left circularly polarized light and reflects the other, and a cholesteric liquid crystal layer that exhibits the opposite transmission and reflection characteristics, a selective reflection layer having no polarization selectivity is laminated. Can be produced.
As such a selective reflection layer, for example, a selective reflection layer (blue light selective reflection layer) having a reflection maximum wavelength in a wavelength band of blue light, and a selective reflection layer (green light having a reflection maximum wavelength in a wavelength band of green light). Selective reflection layer), and a selective reflection layer (red light selective reflection layer) having a reflection maximum wavelength in the wavelength band of red light. Also, two or more selective reflection layers can be laminated and used as a light control layer.
Among these, it is preferable from the viewpoint of reducing tint to use a selective reflection layer that can selectively reflect light emitted from the phosphor contained in the wavelength conversion layer as a light control layer. Further, such a selective reflection layer may be used as a member disposed at a position closest to the wavelength conversion member on the light source side of the wavelength conversion layer or the wavelength conversion member including this layer. Is more preferable.
In the selective reflection layer, the half value width of the reflectance peak is preferably 100 nm or less, more preferably 80 nm or less, and further preferably 70 nm or less.
On the other hand, a normal reflection layer can function as a reflection layer for light in a wider wavelength range than a selective reflection layer. Of course, such a reflective layer is also preferable as the light control layer. Such a reflective layer is also used as a member disposed at a position closest to the wavelength conversion member on the light source side of the wavelength conversion layer or the wavelength conversion member including this layer, from the viewpoint of reduction in tint, More preferred.

  A laminate of layers having different refractive indexes can also be used as the light control layer. As such a light control layer, for example, a layer disclosed as an antireflection film in JP-A-2005-283730 can be used.

(4-4. Light Control Layer Utilizing Two or More Actions of Light Interference, Scattering, Refraction, and Reflection)
The light control layer of each aspect described above is a layer that can mainly exhibit an oblique incident light linear transmittance reduction function by the above-described action. One or more of the actions may contribute.
In addition, for example, a layer exhibiting retroreflectivity due to light refraction, reflection or refraction and reflection, and interference can be used as the light control layer. Examples of the layer exhibiting retroreflectivity include those disclosed as a retroreflective article in JP-T-2002-538485.
Alternatively, a layer (light control layer) having an oblique incident light linear transmittance reduction function can be obtained by using a layer other than those described above, for example, a layer known as a retardation film, a polarizing film, a color filter, or the like. .

  The thickness of the light control layer described above is, for example, 1 to 500 μm, but is not particularly limited as long as it can function as a light control layer. In addition to the constituent members described above, the backlight unit can also include one or more of various members normally included in the backlight unit at any position.

[Liquid Crystal Display]
A liquid crystal display device according to one embodiment of the present invention includes at least the above-described backlight unit and a liquid crystal panel.

  The liquid crystal panel usually includes at least a viewing side polarizer, a liquid crystal cell, and a backlight side polarizer. The driving mode of the liquid crystal cell is not particularly limited, and is twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), and optically compensated bend cell (OCB). Various modes such as can be used. The liquid crystal cell is preferably VA mode, OCB mode, IPS mode, or TN mode, but is not limited thereto. As an example of the configuration of the VA mode liquid crystal display device, the configuration shown in FIG. 2 of Japanese Patent Application Laid-Open No. 2008-262161 is given as an example. However, the specific configuration of the liquid crystal display device is not particularly limited, and a known configuration can be adopted.

  In one embodiment of the liquid crystal display device, a liquid crystal cell having a liquid crystal layer sandwiched between substrates provided with electrodes on at least one opposite side, the liquid crystal cell is arranged between two polarizers. . The liquid crystal display device includes a liquid crystal cell in which liquid crystal is sealed between upper and lower substrates, and displays an image by changing the alignment state of the liquid crystal by applying a voltage. Furthermore, it has an accompanying functional layer such as a polarizing plate protective film, an optical compensation member that performs optical compensation, and an adhesive layer as necessary. Along with (or instead of) a color filter substrate, thin layer transistor substrate, lens film, diffusion sheet, hard coat layer, antireflection layer, low reflection layer, antiglare layer, etc., forward scattering layer, primer layer, antistatic layer Further, a surface layer such as an undercoat layer may be disposed.

FIG. 5 illustrates an example of a liquid crystal display device according to one embodiment of the present invention. The liquid crystal display device 51 illustrated in FIG. 5 includes the backlight side polarizing plate 14 on the surface of the liquid crystal cell 21 on the backlight side. The backlight-side polarizing plate 14 may or may not include the polarizing plate protective film 11 on the backlight-side surface of the backlight-side polarizer 12, but it is preferably included.
The backlight side polarizing plate 14 preferably has a configuration in which the polarizer 12 is sandwiched between two polarizing plate protective films 11 and 13.
In this specification, the polarizing plate protective film on the side closer to the liquid crystal cell with respect to the polarizer is referred to as the inner side polarizing plate protective film, and the polarizing plate protective film on the side farther from the liquid crystal cell with respect to the polarizer is referred to as the outer side polarizing plate. It is called a protective film. In the example shown in FIG. 5, the polarizing plate protective film 13 is an inner side polarizing plate protective film, and the polarizing plate protective film 11 is an outer side polarizing plate protective film.

  The backlight side polarizing plate may have a retardation film as an inner side polarizing plate protective film on the liquid crystal cell side. As such a retardation film, a known cellulose acylate film or the like can be used.

  The liquid crystal display device 51 includes a display side polarizing plate 44 on the surface of the liquid crystal cell 21 opposite to the surface on the backlight side. The display-side polarizing plate 44 has a configuration in which a polarizer 42 is sandwiched between two polarizing plate protective films 41 and 43. The polarizing plate protective film 43 is an inner side polarizing plate protective film, and the polarizing plate protective film 41 is an outer side polarizing plate protective film.

  The backlight unit 1 included in the liquid crystal display device 51 is as described above.

  There is no particular limitation on the liquid crystal cell, the polarizing plate, the polarizing plate protective film, and the like constituting the liquid crystal display device according to one embodiment of the present invention, and those prepared by known methods and commercially available products can be used without any limitation. it can. It is of course possible to provide a known intermediate layer such as an adhesive layer between the layers.

  Hereinafter, the present invention will be described more specifically based on examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. Unless otherwise specified, the temperatures described below are the ambient temperatures at which processing is performed.

The emission center wavelength (emission maximum) described below was determined with a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation).
The following average molecular weight shall mean the average molecular weight calculated | required by converting the measured value by gel permeation chromatography (GPC) into polystyrene. The measurement conditions are as follows.
GPC device: HLC-8120 (manufactured by Tosoh Corporation):
Column: TSK gel Multipore HXL-M (Tosoh, 7.8 mm ID (inner diameter) × 30.0 cm)
Eluent: Tetrahydrofuran (THF)

1. Preparation of Barrier Film 10 An organic layer and an inorganic layer were sequentially formed on one side of a polyethylene terephthalate film (PET film, manufactured by Toyobo Co., Ltd., trade name: Cosmo Shine (registered trademark) A4300, thickness 50 μm) by the following procedure.
Prepare trimethylolpropane triacrylate (TMCTA manufactured by Daicel Cytec Co., Ltd.) and a photopolymerization initiator (manufactured by Lamberti Co., ESACURE KTO46), and weigh them so that the former: latter = 95: 5. It was dissolved in methyl ethyl ketone to obtain a coating solution having a solid concentration of 15%. This coating solution was applied onto the PET film with a roll toe roll using a die coater, and passed through a drying zone at 50 ° C. for 3 minutes. Thereafter, the sample was irradiated with ultraviolet rays (integrated irradiation amount: about 600 mJ / cm ² ) in a nitrogen atmosphere, cured by ultraviolet curing, and wound up. The thickness of the first organic layer formed on the support was 1 μm.

  Next, an inorganic layer (silicon nitride layer) was formed on the surface of the first organic layer using a roll-to-roll CVD (Chemical Vapor Deposition) apparatus. Silane gas (flow rate 160 sccm), ammonia gas (flow rate 370 sccm), hydrogen gas (flow rate 590 sccm), and nitrogen gas (flow rate 240 sccm) were used as source gases. A high frequency power supply having a frequency of 13.56 MHz was used as the power supply. The film formation pressure was 40 Pa, and the ultimate film thickness was 50 nm. Thus, the barrier film 10 in which the inorganic layer was laminated on the surface of the first organic layer was produced.

2. Preparation of Quantum Dot-Containing Polymerizable Composition As a quantum dot-containing polymerizable composition, the following quantum dot dispersion liquid A is prepared, filtered through a polypropylene filter having a pore size of 0.2 μm, and then dried under reduced pressure for 30 minutes. Used as. The quantum dot concentration in the following toluene dispersion was 1% by mass.
──────────────────────────────────────
Quantum dot dispersion A
──────────────────────────────────────
17. Toluene dispersion of quantum dots 1 (emission maximum: 520 nm) 10.0 parts by mass Toluene dispersion of quantum dots 2 (emission maximum: 630 nm) 1.0 part by weight lauryl methacrylate 80.8 parts by weight trimethylolpropane triacrylate 2 parts by mass photopolymerization initiator 1.0 part by mass (Irgacure 819 (manufactured by BASF))
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3. Production of Wavelength Conversion Member A The barrier film 10 produced by the above-described procedure was used as the first and second films, and the wavelength conversion member A was obtained by the production process described with reference to FIGS. 3 and 4. Specifically, the barrier film 10 is prepared as the first film, and the quantum dot-containing polymerizable composition is applied on the inorganic layer surface with a die coater while continuously transporting at a tension of 1 m / min and 60 N / m. A coating film having a thickness of 50 μm was formed. Next, the barrier film 10 with the coating film formed is wound around a backup roller, and another barrier film 10 is laminated on the coating film as a second barrier film in such a direction that the inorganic layer surface is in contact with the coating film. The film was wound around a backup roller in a state where the coating film was sandwiched between the barrier films 10 (first and second films) and irradiated with ultraviolet rays while being continuously conveyed. The diameter of the backup roller was φ300 mm, and the temperature of the backup roller was 50 ° C. The irradiation amount of ultraviolet rays was 2000 mJ / cm ² . L1 was 50 mm, L2 was 1 mm, and L3 was 50 mm.

  The coating film was cured by irradiation with the ultraviolet rays to form a cured layer (wavelength conversion layer), and a wavelength conversion member A was produced. The thickness of the cured layer of the wavelength conversion member was about 50 μm. Thus, the wavelength conversion member A having the barrier films 10 on both surfaces of the wavelength conversion layer and having both main surfaces of the wavelength conversion layer in direct contact with the inorganic layer of the barrier film was obtained.

4). Preparation and Preparation of Light Control Layer (1) Preparation of Cholesteric Liquid Crystal Layer A (Reflective Polarizer) First, a terminal fluorinated alkyl group-containing polymer (compound A) having an optically active site according to the procedure described in paragraph 0065 of Japanese Patent No. 4570377. ) Specifically, Compound A was obtained as follows.
To a four-necked flask equipped with a condenser, a thermometer, a stirrer, and a dropping funnel, a fluorinated solvent AK-225 (Asahi Glass Co., Ltd., 1,1,1,2,2-pentafluoro-3,3-dichloropropane: 1 , 1,2,2,3-pentafluoro-1,3-dichloropropane = 1: 1.35 (molar ratio) mixed solvent)) 50 parts by mass, a reactive chiral agent (compound) having optical activity of the following structure 7. In the formula, * indicates an optically active site) 5.22 parts by mass are charged, the reaction vessel is heated to 45 ° C., and then 10 mass of diperfluoro-2-methyl-3-oxahexanoyl peroxide / AK225 6.58 parts by mass of a% solution was added dropwise over 5 minutes. After completion of dropping, the reaction is carried out in a nitrogen stream at 45 ° C. for 5 hours, and then the product is concentrated to 5 ml, reprecipitated with hexane, and dried to contain a terminal fluorinated alkyl group-containing polymer. (Compound A) 3.5 parts by mass (yield 60%) was obtained.
When the molecular weight of the obtained polymer was measured using gel permeation chromatography (GPC) and tetrahydrofuran (THF) as a developing solvent, Mn = 4,000 (Mw / Mn = 1.77), and the fluorine content was When measured, the fluorine content was 5.89% by mass.

An alignment film coating solution consisting of 10 parts by weight of polyvinyl alcohol and 371 parts by weight of water was applied to a glass 7059 manufactured by Corning Co., Ltd. on one side of the glass and dried to form an alignment film having a thickness of 1 μm. Next, a rubbing treatment was performed on the alignment film continuously in a direction parallel to the longitudinal direction of the glass.
On the alignment film, a composition having the following composition was applied using a bar coater, dried at room temperature for 10 seconds, heated in an oven at 100 ° C. for 2 minutes (alignment aging), and further irradiated with ultraviolet rays for 30 seconds. A cholesteric liquid crystal layer A having a thickness of 5.0 μm was formed.

<Composition for forming cholesteric liquid crystal layer A>
Compound 8 8.2 parts by mass of Compound 9 0.3 parts by mass of a terminal fluorinated alkyl group-containing polymer having an optically active site prepared earlier (Compound A)
1.9 parts by mass Methyl ethyl ketone 24.0 parts by mass A cross section of the cholesteric liquid crystal layer A was observed with a scanning electron microscope. As a result, the cholesteric liquid crystal layer A had a helical axis in the layer normal direction and a structure in which the cholesteric pitch was continuously changed. Was. Here, regarding the cholesteric pitch, when the cross section of the cholesteric liquid crystal layer is observed with a scanning electron microscope, the width in the layer normal direction of the light portion and the dark portion repeated twice (brightness, darkness, and darkness) is counted as one pitch.
When the short wavelength side is defined as the x plane and the long wavelength side is defined as the y plane in the thickness direction of the cholesteric pitch, the cholesteric transmission spectrum was measured using AXOSCAN manufactured by AXOMETRIX, and the reflection maximum wavelength was obtained. The cholesteric reflection maximum wavelength near the x-plane side was 410 nm, and the cholesteric reflection maximum wavelength near the y-plane side was 700 nm.

(2) Preparation of Cholesteric Liquid Crystal Layer B (Selective Reflective Polarizer) A solution was prepared by dissolving Sunever SE-130 (manufactured by Nissan Chemical Co., Ltd.) as an alignment layer in N-methylpyrrolidone.
Adjust the concentration and the coating amount of the prepared solution so that the dry film thickness becomes 0.5 μm, and heat the coating film obtained by bar coating on Corning glass 7059 at 100 ° C. for 5 minutes. Heated at 250 ° C. for 1 hour. Thereafter, the surface of the coating film was rubbed to obtain an alignment layer.
Subsequently, a solute having the following composition was dissolved in methyl ethyl ketone (MEK) to prepare a coating solution for forming a first cholesteric liquid crystal layer containing a discotic liquid crystal compound. The coating solution was adjusted so that the concentration and the coating amount were the following film thicknesses, coated on the alignment layer with a bar, kept at 70 ° C. for 2 minutes to evaporate the solvent, and then heated at 100 ° C. for 4 minutes. A uniform alignment state was obtained by heating and aging for one minute.
Thereafter, the coating film was kept at 45 ° C. and then irradiated with ultraviolet rays using a high-pressure mercury lamp in a nitrogen atmosphere to form a cholesteric liquid crystal layer B. The film thickness of the cholesteric liquid crystal layer B was 2.4 μm.
As a result of measuring the pitch of cholesteric using AXOSCAN manufactured by AXOMETRIX, the reflection maximum wavelength was 600 nm.

<Solute composition of coating solution for forming cholesteric liquid crystal layer B>
Discotic liquid crystal compound 1 56.0 parts by mass Discotic liquid crystal compound 2 14.0 parts by mass alignment aid (compound 3) 1.0 part by mass alignment aid (compound 4) 1.0 part by mass polymerization initiator (compound 5) ) 3.0 parts by mass chiral agent (compound 6) 3.0 parts by mass

  Instead of Corning glass 7059, a film such as a cellulose acylate film (for example, TD80UL manufactured by Fuji Film), preferably a long film having a total length of 100 meters or more may be used. The use of a film in this manner is more preferable from the viewpoint of production suitability because it enables production with a so-called roll-to-roll. The film to be used is not limited to the cellulose acylate film as long as it can transfer the cholesteric liquid crystal layer, and various films can be used.

(3) Production of multilayer film C (reflective polarizer) in which a plurality of layers having different refractive indexes are laminated A total of 256 different two types of thermoplastic resin films are alternately laminated and multilayer coextruded to form a laminated film. . The following polyethylene terephthalate (PET) film has a refractive index of 1.84 in the stretching direction for stretching described below, a refractive index in the direction orthogonal to the stretching direction in the plane of 1.57, and a refractive index of 1 in the thickness direction. .57. On the other hand, the refractive index of the following copolyester (coPEN) film of naphthalene dicarboxylic acid and terephthalic acid or isophthalic acid was 1.57 isotropically. Specifically, the PET film is used as the first layer, and the coPEN film is stacked as the second layer on the first layer. Thereafter, the PET film (odd number layer) and the coPEN film (even number layer) are alternately stacked. .
In multilayer coextrusion, the laminated film is divided into a total of 8 regions (membrane units), and the thickness of the odd layers, the even layers, and the total thickness of each membrane unit are adjusted by adjusting the spacing of the coextrusion slots. Each was controlled.
Thereafter, the produced laminated film was stretched only in the longitudinal direction at a stretching ratio of 4.0 times while being transported in the longitudinal direction of the film in an atmosphere of 90 ° C. Table 1 below shows the number of odd-numbered layers (PET film), the number of even-numbered layers (coPEN), the thickness of one layer, and the total thickness in each film unit in the laminated film (multilayer film C) thus obtained. In the table, the membrane units are numbered as membrane units 1, 2,... From the lowermost layer to the outermost layer during lamination.

(4) Production of multilayer film D (selective reflective polarizer) in which a plurality of layers having different refractive indexes are laminated An odd-numbered layer is a polyethylene terephthalate (PEN) film, an even-numbered layer is a polyethylene terephthalate (PET) film, and the layer structure is shown in the following table. A multilayer film was obtained by performing multilayer co-extrusion in the same manner as in the production of the multilayer film C except for the points changed as shown in FIG.
Thereafter, the multilayer film D was obtained by stretching the produced laminated film only in the longitudinal direction at a stretching ratio of 4.0 times while being conveyed in the longitudinal direction of the film in an atmosphere of 90 ° C.

(5) Preparation of Light Scattering Layer E As the light scattering layer E, a commercially available light diffusive sheet (Kimoto light up 100SXE) was prepared.

(6) Preparation of Anisotropic Light Scattering Layer F As the anisotropic light scattering layer F, a commercially available light diffusive sheet (Lumisty Model No. MFZ-2555 manufactured by Sumitomo Chemical Co., Ltd.) was prepared.

(7) Preparation of Prism Layer G A prism sheet extracted from a commercially available liquid crystal television (42LA7400 manufactured by LGE) was used as the prism layer G.

(8) Production of Cholesteric Liquid Crystal Layer H (Selective Reflective Polarizer) A cellulose acylate film (TD80UL manufactured by Fuji Film) was used in place of Corning glass 7059, and a chiral agent (compound 6) in the solute composition of the coating solution The cholesteric liquid crystal layer H described above was produced in the same manner as in the production of the cholesteric liquid crystal layer B, except that the amount of) was 3.5 parts by mass.
As a result of measuring the pitch of cholesteric using AXOSCAN manufactured by AXOMETRIX, the reflection maximum wavelength was 450 nm.

(9) Preparation of Cholesteric Liquid Crystal Layer I (Selective Reflective Polarizer) Except that the amount of the chiral agent (Compound 6) in the solute composition of the coating solution was 3.2 parts by mass, the same as the preparation of the cholesteric liquid crystal layer C. Thus, a cholesteric liquid crystal layer I was produced.
As a result of measuring the pitch of cholesteric using AXOSCAN of AXOMETRIX, the reflection maximum wavelength was 530 nm.

  The cholesteric liquid crystal layer H and the cholesteric liquid crystal layer I are selective reflection polarizers having a single reflection peak (reflection maximum wavelength: see above) in the wavelength band of 430 to 680 nm in the reflection spectrum.

(10) Production of Cholesteric Liquid Crystal Layer J (Reflective Polarizer) A cellulose acylate film (TD80UL manufactured by Fuji Film Co., Ltd.) is used instead of Corning glass 7059, and the thickness of the cholesteric liquid crystal layer after UV irradiation is set to 2. A cholesteric liquid crystal layer J was produced in the same manner as in the production of the cholesteric liquid crystal layer A except that the thickness was 9 μm.
The cholesteric reflection maximum wavelength near the x-plane side of the cholesteric liquid crystal layer J obtained by the same method as the measurement method performed on the cholesteric liquid crystal layer A was 410 nm, and the cholesteric reflection maximum wavelength near the y-plane side was 580 nm.

(11) Production of Laminate L of Cholesteric Liquid Crystal Layer Using a polyethylene terephthalate (PET) film (Cosmo Shine A4100 manufactured by Toyobo Co., Ltd.) as a base material, a rubbing treatment is applied to the surface of the PET film on which the easy adhesion layer is not applied. Carried out.
A composition used for forming the cholesteric liquid crystal layer J was prepared, and a coated film was prepared by applying the composition on a surface of the substrate that had been rubbed with a bar coater. A cholesteric liquid crystal layer K was prepared by irradiating this coating film with ultraviolet rays using a high-pressure mercury lamp in a nitrogen atmosphere after being kept at 45 ° C.
As a result of measuring the pitch of cholesteric using AXOSCAN manufactured by AXOMETRIX, the reflection maximum wavelength was 450 nm.
Cholesteric liquid crystal layer I and cholesteric liquid crystal layer K were bonded using an adhesive (SK2057 manufactured by Soken Chemical Co., Ltd.). At that time, the cholesteric liquid crystal layers I and K were bonded so that they were in contact with the adhesive. Thereafter, the PET film that is the base material of the cholesteric liquid crystal layer K was peeled off to obtain a laminate L in which two layers of cholesteric layers I and K were laminated on the cellulose acylate film.

  Of the light control layers, the cholesteric liquid crystal layer A was a broadband reflection polarizer, and the cholesteric liquid crystal layers B, H, I, J, and the laminate L were confirmed to be narrow band reflection polarizers from the reflection spectrum. .

5. Example, assembly of backlight unit of comparative example

[Comparative Example 1]
A commercially available liquid crystal television (REGZA (registered trademark) 50Z9X manufactured by Toshiba) equipped with a direct type backlight unit was disassembled, and the backlight unit was taken out. The extracted backlight unit is equipped with a white LED as a light source, and is provided with a diffusion plate on the light emission side (liquid crystal panel side) and a reflection plate on the opposite side.
After replacing all the white LEDs of the taken-out backlight unit with blue LEDs, after assembling the reflector plate, the light source, and the diffusing plate in this order toward the liquid crystal panel side, similar to the above-mentioned commercial television, 3. above the diffusion plate. The wavelength conversion member A produced in the above is disposed, and the two prism sheets and the brightness enhancement film (DBEF (registered trademark) manufactured by 3M Co., Ltd.) included in the above-mentioned commercially available television are placed on the wavelength conversion member A, the prism sheet, The backlight unit of Comparative Example 1 was produced by arranging the prism sheet and the brightness enhancement film in this order.

[Examples 1 to 11]
4. above. Backlight units of Examples 1 to 11 were produced in the same manner as in Comparative Example 1 except that the constituent members including the respective light control layers produced in 1 were arranged as shown in Table 3 below.

6). Examples 1 to 7 and Evaluation of Colored Black Display Parts of Comparative Example 1 Each of the above backlight units was incorporated into a commercially available liquid crystal television (REGZA (registered trademark) 50Z9X manufactured by Toshiba). This commercially available liquid crystal television is provided with a local dimming control mechanism for dimming a light source located behind a portion where black is displayed on the display surface of the liquid crystal television.
The color of the peripheral portion (black display portion) was measured using a luminance meter (SR3 manufactured by TOPCON) when the entire surface was black and a 3 cm square white square was displayed on the display surface of the liquid crystal television. . Similarly, the hue of the central portion (white display portion) is measured, and the difference in hue (Δu′v ′) between the central portion and the peripheral portion in the chromaticity space is defined as a change in the hue of the dark portion. evaluated. The results are shown in Table 3.
A: Δu′v ′ <0.01
B: 0.01 ≦ Δu′v ′ <0.02
C: 0.02 ≦ Δu′v ′ <0.03
D: 0.03 ≦ Δu′v ′

  From the results shown in Table 3, it can be confirmed that the coloring of the black display portion was reduced in the examples.

7). Evaluation of Examples 1, 2, 8 to 11 and Comparative Example 1 (1) Evaluation of the black display portion with the color tone 6. Each backlight unit was incorporated into the commercial LCD TV used in the evaluation.
On the display surface of the liquid crystal television, a white square of 3 cm square was displayed in the center and black, and black paper was pasted on the white square to block white light. In this state, the surrounding black display portion was visually observed in the dark room and the bright room, and the following sensory scores were assigned.
A: The black part was sufficiently dark even in the dark room, and no coloring was felt.
B: In the dark room, the coloring was slightly visible, but not in the bright room.
C: Although the coloring of the black part was visually recognized in the dark room, it was not visually recognized in the bright room.
D: The coloring of the black part was visually recognized in the dark room and the bright room.

(2) Brightness measurement of dark area The brightness of the peripheral part (black display part) when a white square of 3 cm square is displayed in the center on the entire display surface of the above liquid crystal television is a luminance meter (manufactured by TOPCON). SR3) and scored as follows. In the measurement, a point 3 cm away from the edge of the white square was taken as the measurement point.
A: The luminance was less than 95% with respect to Comparative Example 1.
B: The brightness was 95% or more and less than 100% with respect to Comparative Example 1.
C: The luminance was 100% or more with respect to Comparative Example 1.

(3) Luminance measurement of bright part In the state which displayed the white square like said (2), the brightness | luminance of the center of a white square was measured with the luminance meter (Topcon SR3), and the following ratings were attached.
A: The luminance was 101% or more compared to Comparative Example 1.
B: The brightness was 95% or more and less than 101% with respect to Comparative Example 1.
C: The luminance was less than 95% with respect to Comparative Example 1.

  The results are shown in Table 4.

8). Confirmation of the function of reducing the linear incident light transmittance of the light control layer Using a spectrophotometer (UV-3150, manufactured by Shimadzu Corporation), incident light having a wavelength of 550 nm and 450 nm with respect to incident light having a polar angle of 45 ° of the constituent member including the light control layer The linear transmittance for light was measured.
For the light control layer provided on the base material, only the base material is blank, and for the light control layer without the base material and the light control layer integrated with the base material, no sample (air) is blank, and oblique Table 5 shows that the linear light transmittance of the incident light is 5% or more lower than that of the blank, and A is less than 5%, and B is B. Specifically, glass is used for the cholesteric liquid crystal layers A and B, no sample is used for the multilayer films C and D, and no sample is used for the light scattering layer E, the anisotropic light scattering layer F, and the prism layer G. For H, I, J and laminate L, a cellulose acylate film was used as a blank.

When Example 1 and Example 2 are compared, the evaluation result with the tint of the black display portion shown in Table 4 is as follows in Example 1 having the function of reducing the oblique incident light linear transmittance in the wavelength band of blue light. A better dark portion luminance reduction effect is obtained. The present inventors consider that this is because light leakage to a dark display portion is suppressed by reducing the amount of blue stray light.
In Example 2, Example 8, and Example 9 using cholesteric liquid crystal layers having different reflection maximum wavelengths, the reflection maximum wavelength is the wavelength band of the green light with respect to the evaluation result of the black display portion shown in Table 4 (Example 9) showed the best results. On the other hand, with respect to the dark portion luminance, the better the result, the closer the reflection maximum wavelength is to the short wavelength side. This is because the cholesteric liquid crystal layer has different reflection characteristics with respect to direct incident light and reflection characteristics with respect to light incident from an oblique direction, and the light incident from an oblique direction shifts the reflection band toward the short wavelength side with respect to the direct incident light (so-called The present inventors presume that this is caused by the blue shift phenomenon.
Further, Example 10 and Example 11 using a cholesteric liquid crystal layer (narrowband reflective polarizer) exhibiting a function of reducing the linear transmittance of oblique incident light with respect to blue light and green light are implemented using a broadband reflective polarizer. Compared to Example 1, it showed a better tinting reduction effect. In particular, when Example 10 and Example 11 are compared, a light control layer in which the blue shift phenomenon of the multilayer film described above is adjusted by using two kinds of materials, a disc-shaped cholesteric liquid crystal compound and a rod-shaped cholesteric liquid crystal compound reflective layer in combination ( Example 11 having the laminate L) is also considered to be a particularly preferred embodiment, since the brightness of the bright part is also improved.

  The present invention is useful in the field of manufacturing liquid crystal display devices.

Claims (17)

A light emitting unit including at least a reflecting member and a light source;
At least one member selected from the group consisting of a diffusion member and a light guide member;
A wavelength conversion layer;
Including
A backlight unit capable of local dimming control further including a light control layer having a function of reducing the linear transmittance of obliquely incident light incident from an oblique direction on the wavelength conversion layer side between the light emitting unit and the wavelength conversion layer. The backlight unit according to claim 1, wherein the light control layer is a layer that exhibits the function by one or more actions selected from the group consisting of interference, scattering, refraction, and reflection of light. The backlight unit according to claim 1, wherein the light control layer is a reflective polarizer. The backlight unit according to claim 3, wherein the reflective polarizer is a polymer layer having cholesteric liquid crystallinity. The backlight unit according to claim 3, wherein the reflective polarizer is a multilayer film in which a plurality of layers having different refractive indexes are stacked. The backlight unit according to claim 1, wherein the light control layer is a light scattering layer.
The backlight unit according to claim 6, wherein the light scattering layer is an anisotropic light scattering layer. The backlight unit according to claim 1, wherein the light control layer is a prism layer having a concavo-convex shape on a surface on the light emitting unit side. The backlight unit according to claim 1, wherein the light source is a light source that emits light having a single peak. The backlight unit according to claim 9, wherein the light source is a blue light source that emits blue light. The backlight unit according to claim 1, wherein the wavelength conversion layer includes a phosphor that emits fluorescence when excited by excitation light. The backlight according to any one of claims 1 to 11, wherein the wavelength conversion layer includes at least a phosphor that is excited by excitation light and emits red light and a phosphor that is excited by excitation light and emits green light. unit. The backlight unit according to claim 11, wherein the phosphor is a quantum dot. The at least one member selected from the group consisting of the diffusion member and the light guide member includes at least a diffusion member, and the light control layer is provided between the diffusion member and the wavelength conversion layer. The backlight unit according to claim 1. The at least one member selected from the group consisting of the diffusion member and the light guide member includes at least a diffusion member, and the light control layer is provided between the diffusion member and the light emitting unit. The backlight unit according to item 1. It is a direct type backlight unit, The backlight unit of any one of Claims 1-15. A liquid crystal display device comprising at least the backlight unit according to claim 1 and a liquid crystal panel.