KR101812025B1 - Optical member and liquid crystal display including the same - Google Patents

Abstract

Provided is an optical member with an excellent color viewing angle and an excellent color reproduction range. The optical member comprises: a narrowband reflection polarized part; and a broadband reflection polarized part laminated on the narrowband reflection polarized part, wherein the width of a reflection polarized wave band of the narrowband reflection polarized part is smaller than the width of the reflection polarized wave band of the broadband reflection polarized part, and a reflection wavelength center wavelength of the narrowband reflection polarized part is placed in a wavelength band equal to or greater than a red wavelength.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical member and a liquid crystal display including the optical member.

The present invention relates to an optical member and a liquid crystal display including the optical member.

A liquid crystal display (LCD) is a device for displaying an image by injecting liquid crystal between two glass plates and applying power to the upper and lower glass plate electrodes to change the arrangement of liquid crystal molecules in each pixel. Unlike a cathode ray tube (CRT), a plasma display panel (PDP) or the like, a display using a liquid crystal display device is not usable in a place where there is no light because the display itself is non-luminous. In order to compensate for these drawbacks, a backlight assembly that is uniformly irradiated on the information display surface is mounted for the purpose of enabling use in a dark place.

In the liquid crystal display panel, the transmittance differs according to the alignment direction of the liquid crystal. Since the direction of the liquid crystal passing through the light coming from the front and the light coming out from the side are different, a difference in basic color coordinates occurs between the front and the side. In addition, when a wide-band reflective polarizing film is employed for improving the luminance, the difference in color coordinates between the side surfaces is further increased, and the display quality may be degraded.

An object of the present invention is to provide an optical member exhibiting excellent color viewing angle and color reproduction ratio.

Another object of the present invention is to provide a liquid crystal display device which exhibits excellent color viewing angle and color reproduction ratio.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an optical member including a narrowband reflective polarizer and a broadband reflective polarizer stacked on the narrowband reflective polarizer, The width of the band is smaller than the width of the reflection polarized wavelength band of the broadband reflective polarizing section, and the reflected wavelength center wavelength of the narrowband reflective polarizing section is located in the wavelength band greater than or equal to the red wavelength.

According to another aspect of the present invention, there is provided a liquid crystal display device including the optical member, and a liquid crystal display panel disposed on the optical member.

The details of other embodiments are included in the detailed description and drawings.

According to the optical member and the liquid crystal display device according to the embodiments of the present invention, the color viewing angle can be improved while exhibiting excellent brightness and color reproduction ratio.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.
2 is a cross-sectional view of an optical member according to an embodiment of the present invention.
3 is a graph showing the optical spectrum of the cholesteric liquid crystal layer.
4 is a graph showing a light spectrum of a broadband reflective polarizing layer according to an embodiment of the present invention.
5 is a cross-sectional view of an optical member according to another embodiment of the present invention.
6 is a cross-sectional view of an optical member according to another embodiment of the present invention.
7 is a cross-sectional view of an optical member according to another embodiment of the present invention.
8 is a schematic diagram of a backlight unit according to an embodiment of the present invention.
Figs. 9 to 11 are graphs showing the variation of the color coordinates according to the viewing angle in the liquid crystal display device according to the comparative example and the production examples 1 to 10. Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

It is to be understood that elements or layers are referred to as being "on " other elements or layers, including both intervening layers or other elements directly on or in between. On the other hand, a device being referred to as "directly on" refers to not intervening another device or layer in the middle. Like reference numerals refer to like elements throughout the specification. "And / or" include each and any combination of one or more of the mentioned items.

Although the first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical scope of the present invention.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms " comprises "and / or" comprising "used in the specification do not exclude the presence or addition of one or more other elements in addition to the stated element.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

The terms spatially relative, "below", "beneath", "lower", "above", "upper" And can be used to easily describe a correlation between an element and other elements. Spatially relative terms should be understood in terms of the directions shown in the drawings, including the different directions of components at the time of use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element . Thus, the exemplary term "below" can include both downward and upward directions. The components can also be oriented in different directions, so that spatially relative terms can be interpreted according to orientation.

As used herein, the terms "to sheet "," to film ", "to plate ", and the like may be used interchangeably. In addition, the optical member, which is a term in this specification, can be used to mean an optical sheet, an optical film, an optical plate, an optical film package and the like. In the present specification, the term " transmission axis "means a transmission axis.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

1, a liquid crystal display device 50 according to an exemplary embodiment of the present invention includes a light source 30, an optical member 10 disposed on the light source 30, a liquid crystal display panel 20 ). 1 illustrates a case where the liquid crystal display device 50 includes a direct-type backlight unit, but may also include an edge-type backlight unit with the light source on the side.

The light source 30 serves to provide light to the optical member 10. The light source 30 may be a light emitting diode (LED), but the present invention is not limited thereto. A cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electro fluorescent lamp (EEFL) .

The light source 30 may be a white light source, but a light source that emits light of a specific wavelength such as blue or ultraviolet light may be used. For example, when a blue LED is used as the light source 30, the light conversion material can be converted to white light by being disposed on the optical path. The photo-conversion material may be arranged immediately adjacent to the light source 30 or on the side of the optical member 10 or on the inside or outside of the liquid crystal display panel 20. [ In the following embodiments, the blue LED is used as the light source 30, and the light conversion material is disposed on the optical member 10, but the present invention is not limited thereto.

The optical member 10 includes a light wavelength conversion member 16 and a reflective polarizing member 15.

The light wavelength converting member 16 may be disposed between the light source 30 and the reflective polarizing member 15. [ The light wavelength converting member 16 receives blue light from the light source 30 and converts the blue light into white light.

The light wavelength conversion member 16 includes a wavelength conversion material. The wavelength converting material may be a quantum dot. The quantum dot may be a spherical semiconductor nanomaterial having a size of several nanometers to several hundreds of nanometers, and may include a core composed of a material having a small band gap and a shell arranged to surround the core. Quantum dots have discontinuous band gap energies unlike bulk materials due to the quantum confinement effect. When a quantum dot absorbs light, it emits light of a wavelength different from the incident light as the energy level is lowered inside the quantum dot. The details of the light wavelength converting member 16 will be described later.

The reflective polarizing member 15 has a reflection polarizing characteristic, and can transmit specific polarized light and reflect other specific polarized light. Light that has passed through the light source 30 and / or the light wavelength conversion member 16 is provided to the reflective polarizing member 15, and is converted into light of a specific polarized light. That is, the optical member 10 can convert non-polarized light into specific polarized light and emit it. As described above, the light having the specific polarized light emitted by the optical member 10 can be effectively utilized for display and the like.

The reflective polarizing member 15 includes a narrowband reflective polarizing section 11 and a broadband reflective polarizing section 13 laminated (for example, on top) on the narrowband reflective polarizing section 11. The narrow-band reflection polarizing section 11 and the wide-band reflective polarizing section 13 are respectively reflected and polarized with respect to light of at least some wavelengths.

The narrow-band reflection polarizing section 11 and the wide-band reflective polarizing section 13 may have different types of polarized light to be reflected and polarized. For example, the broadband reflective polarizer 13 is a linearly polarized reflection polarizer that reflects linearly polarized light. Specifically, the broadband reflection polarizing section 13 can transmit either the p-wave or the s-wave in the reflection wavelength band and reflect the other. On the other hand, the narrow-band reflection polarizing section 11 is a circularly polarization-type reflection polarizing section that reflects and circularly polarizes circularly polarized light. Specifically, the narrowband reflection polarizing section 11 transmits either the left circularly polarized light or the right circularly polarized light in the reflection polarized wavelength band and reflects the other. However, the present invention is not limited to this, and the narrow-band reflection polarizing section 11 and the wide-band reflective polarizing section 13 may reflectively polarize the same kind of polarized light.

The narrow-band reflection polarizing section 11 and the wide-band reflective polarizing section 13 may have different wavelength bands as well as types of wavelengths to be reflected and polarized.

For example, the broadband reflective polarizer 13 has a reflective polarizing function for light in most visible wavelength bands. For example, the broadband reflective polarizing section 13 can reflect and polarize light in the entire visible light wavelength band ranging from 380 nm to 780 nm.

On the other hand, the narrowband reflection polarizing section 11 has a reflection polarizing function only for a specific wavelength band that is significantly narrower than that of the broadband reflection polarizing section 13. That is, the width of the reflection polarized light wavelength band of the narrowband reflection polarized light section 11 is smaller than the width of the reflection polarized light wavelength band of the wideband reflection polarized light section 13.

More specifically, the narrowband reflection polarizing section 11 transmits light other than the wavelength band having the reflective polarizing function as it is. For example, the narrow-band reflection polarizing section 11 can transmit visible light of a short wavelength such as blue or green without a reflective polarizing function, and can transmit visible light of a long wavelength such as red or a near-infrared wavelength band of reflection polarized light. That is, the center wavelength of the reflection polarized light of the narrowband reflection polarizing section 11 may be equal to or greater than the red wavelength.

In a preferred embodiment, the reflection central wavelength of the narrow-band reflection polarizing portion 11 may be 660 nm or more. For example, the narrowband reflection polarizing section 11 may have a reflection polarizing function with respect to light near 680 nm. Herein, the half width of the reflection wavelength band of light may be 70 nm or less. When the narrow-band reflection polarizing section 11 has a circularly polarized-type reflection polarizing function with respect to light near 680 nm and its half-value width is 70 nm, the wavelength range in which the narrow-band reflective polarizing section 11 effectively reflects the polarized light is 645 nm To 715 nm. In this case, the narrowband reflection polarizing section 11 substantially transmits light in a wavelength range other than 645 nm to 715 nm as it is.

The broadband reflective polarizer 13 recycles light in the visible light wavelength band according to the polarization state, thereby increasing the overall luminance efficiency. More specifically, for example, the liquid crystal display panel 20 displays an image by controlling the transmittance of light. The liquid crystal display panel 20 typically controls the transmittance using polarized light. The liquid crystal display panel includes polarizing elements such as polarizing plates 21 and 22, a wire grid, etc. in order to use polarized light. The incident-side polarizing plate 21 blocks the unpolarized light in a specific direction before the light passes through the liquid crystal layer, thereby allowing the polarized light to be incident on the liquid crystal layer. Therefore, the light polarized in a direction different from that of the incidence-side polarizer 21 of the liquid crystal display panel 20 is blocked and can not be used in the liquid crystal display panel 20, resulting in a loss in luminance.

In the present embodiment, the light reflected by the broadband reflective polarizing section 13 travels in the direction opposite to the direction of emission of the optical member 10. The reflected light is refracted and reflected by the optical recycling structure inside the backlight assembly, and can be reentered upward again. The phase of the light is changed in the recycling process, and the polarized light when the light is reflected is not maintained, and the various polarized lights are converted into the mixed unpolarized state. Therefore, the re-entered light passes through the wide-band reflective polarizing section 13 again and is transmitted or reflected according to the polarized state. This recycling process can be repeated.

As a result of the recycling process, the amount of light having a specific polarized light emitted through the optical member 10 is amplified. When the transmission axis of the broadband reflective polarizing section 13 is aligned in the same direction as the transmission axis of the incident-side polarizing plate 21 of the liquid crystal display panel 20, the light blocked by the incidence-side polarizing plate 21 of the liquid crystal display panel 20 And the overall luminance efficiency can be increased.

On the other hand, in the liquid crystal display panel 20, the transmissivity is different according to the alignment direction of the liquid crystal, and the orientation of the liquid crystal through which light emitted in the front (direction perpendicular to the light exit surface) Since the directions are different, a difference in basic color coordinates occurs between the front side and the side surface. In addition, when the light wavelength converting member 11 is applied, the larger the viewing angle of the display screen, that is, the viewing angle becomes larger, that is, the color changes toward the side rather than the front, thereby causing deterioration of image quality. That is, the application of the light wavelength conversion member 11 can cause a color deviation in the viewing angle of the liquid crystal display device 50.

After repeated research and experiment to improve the color viewing angle, it has been found that the color viewing angle can be improved by further laminating the narrowband reflection polarizing portion 11 having the minimum transmittance in a specific wavelength band. As a result of the experiment, it was confirmed that the effect of improving the color viewing angle differs for each wavelength band having the maximum reflection efficiency of the narrowband reflection polarizing section 11. When the maximum reflection central wavelength is 660 nm or more and the half width is 70 nm or less, the color viewing angle is improved and the luminance drop is also minimized. More specific details thereof will be described later with reference to Production Examples and Experimental Examples.

Hereinafter, the optical member 10 will be described in more detail.

2 is a cross-sectional view of an optical member according to an embodiment of the present invention. In this embodiment, a case is described in which the optical member includes only the reflective polarizing member without the light wavelength converting member.

2, the optical member 100 includes a narrow band liquid crystal film 110 and a wide band reflective polarizer film 130 stacked on the narrow band liquid crystal film 110. [ The narrow band liquid crystal film 110 corresponds to the narrow band reflection polarizing portion 11 of Fig. 1 and the broad band reflective polarizing film 130 corresponds to the wide band reflective polarizing portion 13 of Fig. In the figure, the main travel path of light through the optical member 100 is from the bottom to the top.

The narrow band liquid crystal film 110 may include a substrate 112 and a cholesteric liquid crystal layer 111 formed on the substrate 112. 2, the substrate 112 is disposed on the outermost side where light is incident, and the cholesteric liquid crystal layer 111 is disposed on the emission side. However, the present invention is not limited thereto, and the substrate 112 and the cholesteric liquid crystal The position of the layer 111 may be changed with each other or may be incident on the cholesteric liquid crystal layer 111 after light is incident on the functional layer such as the antireflection layer. In addition, the substrate 112 may be omitted as the case may be.

The cholesteric liquid crystal layer 111 is a layer that transmits either the left-handed circularly polarized light or the right-handed circularly polarized light with respect to light of a specific wavelength band and reflects the other. The cholesteric liquid crystal layer 111 includes a cholesteric liquid crystal. The wavelength band that the cholesteric liquid crystal transmits and reflects can be controlled by the pitch of the cholesteric liquid crystals.

For example, the cholesteric liquid crystal layer 111 may include a cholesteric liquid crystal having a pitch having a minimum transmittance in a wavelength band of 670 nm to 690 nm.

3 is a graph showing the optical spectrum of the cholesteric liquid crystal layer. Referring to FIG. 3, the optical spectrum of the cholesteric liquid crystal layer 111 has one valley in the wavelength band near 680 nm. The bottom point of the bone is located at about 680 nm, and the light transmittance may be in the range of 40 to 60%, preferably in the vicinity of 50%. The wavelength band outside the bone may have a light transmittance of 80% or more, and preferably 90% or more.

It is preferable that the cholesteric liquid crystal layer 111 has a narrow reflection polarizing band. The width of the reflection polarized light band is related to the half width. The half width is defined as the distance between two X-coordinates intersecting a straight line passing between the maximum value and minimum value in the downward convex graph. Therefore, the half width of the optical spectrum can be defined as the width between two wavelengths corresponding to the intermediate transmittance which is an intermediate value between the maximum transmittance and the minimum transmittance in the optical spectrum. The half width of the optical spectrum of the cholesteric liquid crystal layer 111 to have the above narrow reflection polarized light band may be 70 nm or less, preferably 60 nm or less, more preferably 30 nm or less, still more preferably 20 nm or less.

In order for the cholesteric liquid crystal layer 111 to have a narrow half width, it is advantageous that the refractive index anisotropy of the cholesteric liquid crystal is small. For example, when a cholesteric liquid crystal having a refractive index anisotropy of 0.16 or less is used, the half width can be reduced to 70 nm or less, and when the refractive index anisotropy of the liquid crystal is 0.12 or less, the half width can be further reduced to 30 nm or less, When the refractive index anisotropy is 0.10 or less, the half width can be further reduced to 20 nm or less, and a narrow reflective polarized light band can be realized.

Referring again to FIG. 2, the optical member 10 may further include a retardation layer 120. The phase difference layer 120 is disposed on the cholesteric liquid crystal layer 111 to change the phase of the light emitted through the cholesteric liquid crystal layer 111. The phase change value of the retardation layer 120 is preferably a value capable of converting circularly polarized light selectively transmitted by the cholesteric liquid crystal layer 111 into linearly polarized light. For example, the retardation layer 120 may have a phase delay value of? / 4. The polarization direction of the linearly polarized light converted by the retardation layer 120 may be different from the transmission axis of the upper broad band reflective polarizing film 130. [ For example, the polarization direction of the linearly polarized light converted by the retardation layer 120 may be perpendicular to the transmission axis of the broadband reflective polarizing film 130, have an inclination angle of 30 to 80, or have an inclination angle of about 45 have.

The cholesteric liquid crystal layer 111 transmits only the specific circularly polarized light for the light in the reflection wavelength band. On the other hand, light other than the reflection wavelength band is transmitted irrespective of the circular polarization. Therefore, the light in the reflection wavelength band of the light passing through the retardation layer 120 is converted into linearly polarized light, but the light in the other wavelength band is only converted in the polarization state at the time of emergence, Polarized light. The light passing through the retardation layer 120 includes the linearly polarized light of the reflection wavelength band more than the linearly polarized light of the other wavelength band. Therefore, if the transmission axis of the upper broadband reflective polarizing film 130 is arranged to be different from the polarizing direction of the linearly polarized light of the reflection wavelength band, for example, vertically, the corresponding light is transmitted through the upper broadband reflective polarizing film 130 Can be effectively reduced or blocked. Therefore, the color viewing angle can be improved.

Although the figure illustrates a case where a film-shaped retardation layer 120 made of uniaxially or biaxially stretched plastic is disposed between the narrow band liquid crystal film 110 and the broadband reflective polarizer film 130, But may be provided in various other forms.

For example, the retardation layer 120 may be formed by coating, applying, or transferring a resin including an A-plate liquid crystal or a C-plate liquid crystal. In this case, the retardation layer 120 may be formed on a separate substrate, but may be formed directly on the narrowband liquid crystal film 110 or the broadband reflective polarizing film 130.

For example, the narrow band liquid crystal film 110 and the retardation layer 120 may be formed by coating a cholesteric liquid crystal layer 111 on one surface of a base material 112 and forming a retardation layer 120 on the other surface of the base material 112 Coating method. Alternatively, the cholesteric liquid crystal layer 111 may be coated with a cholesteric liquid crystal layer 111 on one side of the substrate 112 and the retardation layer 120 may be coated on one side of the cholesteric liquid crystal layer 111. In this case, the substrate 112 will be disposed at the bottom. Conversely, the retardation layer 120 may be coated on one side of the substrate 112 and the cholesteric liquid crystal layer 111 may be coated on one side of the retardation layer 120. In this case, the substrate 112 is disposed so as to face the uppermost portion. In the above examples, an adhesive layer such as a primer layer may be further interposed between the substrate 112, the cholesteric liquid crystal layer 111, and the retardation layer 120.

When the retardation layer 120 is provided as a retardation film made of plastic, the retardation layer 120 itself can serve as a base. In this case, the above-described base material 112 may be omitted, a cholesteric liquid crystal may be coated on the retardation film, or a separate cholesteric liquid crystal film may be formed and laminated. In the same way, the retardation layer 120 may be integrated with the broadband reflective polarizing film 130. [

It will be appreciated by those skilled in the art that various other known methods for forming the retardation layer 120 into one integral film with the cholesteric liquid crystal layer 111 and / or the broadband reflective polarizing film 130 can be applied There will be. The retardation layer 120 may be omitted.

A wide band reflective polarizing film 130 is disposed on the narrow band liquid crystal film 110. The wide band reflective polarizing film 130 is disposed on the light emitting side of the narrow band liquid crystal film 110. The wide band reflective polarizing film 130 may be disposed close to the narrow band liquid crystal film 110. [ The broadband reflective polarizing film 130 may be positioned so as to overlap with the narrow band liquid crystal film 110.

The broad-band reflective polarizing film 130 includes a broad-band reflective polarizing layer 131. The broadband reflective polarizing layer 131 has reflective polarizing properties in a wider wavelength band than the cholesteric liquid crystal layer 111.

The broad-band reflective polarizing layer 131 may be a multilayered reflective polarizing layer or a stretched reflective polarizing layer in which a high refractive index layer and a low refractive index layer are elongated and alternately laminated. The wide band reflective polarizing layer 131 may be a polymer dispersion type having a plurality of second polymers having different refractive indexes in the first polymer layer or a polymer type reflective polarizing layer having fibers instead of the second polymer, And may be a wire grid type reflective polarizing layer having a pattern.

The wide-band reflective polarizing layer 131 is a multilayer reflective polarizing layer in which a high refractive index layer and a low refractive index layer are stretched and laminated alternately. The broadband reflective polarizing layer 131 includes a plurality of alternately stacked first refractive layers (131a) and a second refractive layer (131b). The first refraction layer 131a may be a PEN layer, and the second refraction layer 131b may be a COPEN layer.

The refractive indexes of the first refractive layer 131a and the second refractive layer 131b may be different from each other along the first direction and the refractive index may be the same along the second direction perpendicular to the first direction. The linearly polarized light oscillating in the second direction transmits the broadband reflective polarizing layer 131, because the first refractive layer 131a and the second refractive layer 131b have substantially the same refractive index in the second direction. On the other hand, since the refractive indices of the first refractive layer 131a and the second refractive layer 131b are different from each other in the first direction, light oscillating in the first direction is transmitted through the first refractive layer 131a and the second refractive layer 131b Lt; / RTI >

The reflection efficiency at the interface between the first refraction layer 131a and the second refraction layer 131b is correlated with the wavelength and the thickness of the first refraction layer 131a and the thickness of the second refraction layer 131b. There is a thickness of each layer having the maximum reflection efficiency for the wavelength. The longer the wavelength, the greater the thickness of each layer exhibiting the maximum reflection efficiency. Therefore, in order to have excellent reflection efficiency in the entire wavelength range of visible light, the broadband reflective polarizer layer 131 is provided with the first refraction layer 131a and the second refraction layer 131b having various thicknesses. For example, the broadband reflective polarizer layer 131 may include a first refraction layer 131a and a second refraction layer 131b having a first thickness and a maximum reflection efficiency at a blue wavelength, The first refraction layer 131a and the second refraction layer 131b having a second thickness larger than the first thickness and the first refraction layer 131a having a third thickness larger than the second thickness having the maximum reflection efficiency at the red wavelength, And a second refractive layer 131b.

Although not shown in the drawing, the broadband reflective polarizing layer 131 may further include a substrate on which a plurality of first refraction layers 131a and a second refraction layer 131b alternately stacked are formed, and further, And a concavo-convex layer formed on the transparent substrate and performing at least one of a light diffusion function, a close-contact prevention function, and a concealment function.

4 is a graph showing a light spectrum of a broadband reflective polarizing layer according to an embodiment of the present invention. Referring to FIG. 4, the light transmittance of the broadband reflective polarizing layer may be 40 to 60% over the entire visible light wavelength range of 380 nm to 780 nm.

Hereinafter, other embodiments of the present invention will be described.

5 is a cross-sectional view of an optical member according to another embodiment of the present invention. The embodiment of FIG. 5 illustrates that the narrow band liquid crystal film 110, the wideband reflective polarizing film 130 can be integrated.

More specifically, the optical member 102 may further include a bonding layer 150 disposed between the narrow band liquid crystal film 110 and the broadband reflective polarizing film 130. The narrow band liquid crystal film 110 and the wide band reflective polarizing film 130 may be integrated by the bonding layer 150. [ The bonding layer 150 may be composed of a bonding material layer, for example, an adhesive layer, an adhesive layer, or a resin layer. Examples of the material constituting the adhesive layer include a silicone polymer, a urethane polymer, a silicone-urethane hybrid structure, an SU polymer, an acrylic polymer, an isocyanate polymer, a polyvinyl alcohol polymer, a gelatin polymer, a vinyl polymer, a latex polymer, A high-transparency adhesive containing a high molecular substance classified into < RTI ID = 0.0 > An example of the resin layer is a polymer resin including an ultraviolet curable resin or a thermosetting resin. Specifically, it may be composed of an unsaturated fatty acid ester, an aromatic vinyl compound, an unsaturated fatty acid and a derivative thereof, an unsaturated dibasic acid and a derivative thereof, and a vinylcyanide compound such as methacrylonitrile.

In this embodiment, since the films 110 and 130 are made complex, the thin film is formed and the assembly is simplified. In addition, since the spacing between the films 110 and 130 is maintained constant, have.

5, the case where the retardation layer is omitted is exemplified. However, when the retardation layer is included, a bonding layer is disposed between the narrow-band liquid crystal film 110 and the retardation layer and / or between the broadband reflective polarizing film 130 and the retardation layer It is of course possible to integrate them.

6 is a cross-sectional view of an optical member according to another embodiment of the present invention.

6 illustrates that in the embodiment of FIG. 2, the stacking order of the broadband reflective polarizing film 130 and the narrow band liquid crystal film 110 of the optical member 103 can be reversed. That is, the broadband reflective polarizing film 130 may be disposed at the lower portion of the optical path, and the narrow band liquid crystal film 110 may be disposed at the upper portion thereof. Also in this case, the retardation layer 120 is preferably disposed on the narrow band liquid crystal film 110.

7 is a cross-sectional view of an optical member according to another embodiment of the present invention.

FIG. 7 illustrates a case where, in the embodiment of FIG. 2, the optical member 104 further includes another optical film.

7, the optical member 104 according to the present embodiment further includes a narrow wavelength liquid crystal film 110, a broadband reflective polarizing film 130 as well as a light wavelength conversion film 160 and a composite optical film 170 do. In addition, the optical member 104 may further include a retardation layer 120 in a light emitting portion of the narrow band liquid crystal film 110, but FIG. 7 shows an example in which the retardation layer 120 is omitted. An exemplary arrangement order is a light wavelength conversion film 160, a composite optical film 170, a narrow band liquid crystal film 110, and a broadband reflective polarizing film 130.

The composite optical film 170 is disposed under the narrow band liquid crystal film 110. The composite optical film 170 includes a first prism sheet 171, a second prism sheet 172 and a bonding layer 173 disposed between the first prism sheet 171 and the second prism sheet 172 . The composite optical film 170 diffuses light to improve a viewing angle or shielding property, or collects light to increase brightness.

The first prism sheet 171 includes a first base material 171a and a first prism pattern layer 171b disposed on the first base material 171a. The second prism sheet 172 includes a second base material 172a and a second prism pattern layer 172b disposed on the second base material 172a. The prism pattern of the first prism pattern layer 171b may extend in the third direction and the prism pattern of the second prism pattern layer 172b may extend in the fourth direction. Although the third direction and the fourth direction are the same direction for the sake of convenience, the third direction and the fourth direction may be perpendicular to each other and may have an acute angle of intersection.

The bonding layer 173 is disposed on the lower surface of the second substrate 172a. The peak of the first prismatic layer 171b penetrates and bonds at least partially into the bonding layer 173. An air gap is defined between the first prism pattern layer 171b and the bonding layer.

The above-described composite optical film 170 can be replaced with other various types of optical films. For example, the bonding layer of the composite optical film 170 is omitted, and the first prism sheet and the second prism sheet can be laminated without a bonding layer. In addition, the first prism sheet or the second prism sheet of the composite optical film 170 may be replaced with a microlens or a diffusion sheet. Instead of the composite optical film 170, a single prism sheet, a microlens, a diffusion sheet, or the like may be disposed.

The light wavelength conversion film 160 is disposed under the composite optical film 170. The light wavelength conversion film 160 corresponds to the light wavelength conversion member 16 described in Fig.

The wavelength conversion film 160 is disposed on the first barrier film 161, the quantum dot fluorescent film 163 including the quantum dots QD disposed on the first barrier film 161 and the quantum dot fluorescent film 163 The second barrier film 162 may include a first barrier film 162 and a second barrier film 162. [ The quantum dot fluorescent material film 163 is sandwiched between the first barrier film 161 and the second barrier film 162.

The quantum dots QD may comprise a core and at least one shell surrounding the core.

The core may be made of materials such as Group II-VI, Group III-V, and the like. For example, the core may be selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnTe, HgS, HgSe, HgTe, PbS, PbTe, AlN, AlP, AlAs, GaN, GaP, GaAs, InN, InP, InAs, InSb, Or a mixture thereof, or a mixture thereof.

A shell is a semiconductor quantum dot which forms a coating layer on the surface of a core semiconductor by bonding with the core semiconductor quantum dots. The core / shell structure has a higher luminous efficiency than the single core structure due to the core / shell structure. Nanoparticles can be obtained. The shell has a band gap larger than that of the core semiconductor and functions as a passivation layer for protecting the core semiconductor from the outside. As such a shell, a II-VI group semiconductor having a high bandgap is used. For example, ZnS, CdS or ZnSe can be preferably used. In the combination of the core / shell structure using this, when the core is composed of CdSe or CdS, the shell can use ZnS, and when the core is CdSe, CdS or ZnSe is used as the shell, Various combinations can be used without limitation.

In some embodiments, there may be a plurality of shells surrounding the core. For example, the quantum dot may include a core, a first shell surrounding the core, and a second shell surrounding the first shell.

The first shell may be a semiconductor quantum dot that forms a coating layer on the surface of the core semiconductor in combination with the core semiconductor quantum dots as described above.

The second shell surrounds the first shell, and can act to block moisture and moisture. The second shell may comprise a single layer or multiple layers of inorganic layers. The inorganic material in the inorganic coating layer may include an inorganic oxide such as silica, alumina, titania, zirconia, or a combination thereof. The moisture permeability of the second shell is preferably measured by the ASTM F 1249 method at a temperature of 38 ° C and a relative humidity of 90% M2 / day, less than 0.7 g / m2 / day, less than 0.6 g / m2 / day, a water vapor transmission rate (WVTR) of less than about 1 g / Less than 0.5 g / m2 / day, less than 0.4 g / m2 / day, less than 0.3 g / m2 / day, less than 0.2 g / m2 / day, less than 0.1 g / m2 / day, less than 0.09 g / m2 / day, less than 0.07 / m2 / day, less than 0.06 g / m2 / day, less than 0.05 g / m2 / day, less than 0.04 g / m2 / day, less than 0.03 g / day or less.

The positions of the first shell and the second shell may be changed. That is, a structure may be employed in which a second shell, which serves to block moisture or moisture, surrounds the core and the first shell surrounds the second shell.

Hereinafter, embodiments of the present invention will be described in more detail with reference to Production Examples and Experimental Examples.

≪ Preparation Example 1 &

8 is a schematic diagram of a backlight unit according to an embodiment of the present invention.

A blue LED light source 250 is disposed on both sides of the light guide plate 200 and a reflective sheet 210 is disposed under the light guide plate 200 as shown in FIG. A light wave length conversion film 160, a composite optical film 170, a narrow band liquid crystal film 110 and a broadband reflection polarizing film 130 are sequentially stacked on the upper side of the light guide plate 200. As a result, a backlight unit 300 having a laminated structure as shown in FIG. 8 was completed.

The narrow band liquid crystal film 110 was formed by aligning a liquid crystal composition blended with a chiral dopant on a liquid crystal so as to have a minimum transmittance at 610 nm (i.e., a reflection central wavelength 610 nm) and a half width of 60 nm on a PET substrate, No retardation film was applied. The broadband reflective polarizing film 130 has a reflective polarizing function over the entire visible light wavelength range of 380 nm to 780 nm.

≪ Production Examples 2 to 10 &

A backlight unit was manufactured in the same manner as in Production Example 1 except that a liquid crystal composition having a center wavelength of 620 nm, 630 nm, 640 nm, 650 nm, 660 nm, 670 nm, 680 nm, 690 nm and 700 nm was used as a narrow band liquid crystal film.

<Comparative Example>

A backlight unit was completed in the same manner as in Production Example 1, except that the narrow band liquid crystal film was omitted.

&Lt; Production Example 11 &

A backlight unit was produced in the same manner as in Production Example 8 except that a retardation film was further disposed on the narrow band liquid crystal film in order to examine the effect when the retardation film was used in the narrow band liquid crystal film. The retardation film having a retardation value of 140 nm was used, and the retardation axis was disposed at an angle of 45 degrees with respect to the transmission axis of the broadband reflective polarizing film.

Experimental Example

The backlight units according to Production Examples 1 to 11 and Comparative Examples were mounted on a liquid crystal display panel of an LCD TV (product name: UN55JS8500F). The liquid crystal display panel was driven in the white mode, and the CIE color coordinates according to the viewing angle were measured and shown in FIGS. 9 to 11. FIG. In addition, the luminance in a normal direction of the display surface and a viewing angle of 40 degrees and 60 degrees (that is, an inclined angle with respect to the surface vertical direction) with respect to the normal was measured and shown in Table 1, The difference in color coordinates at a viewing angle of 40 ° and 60 ° is measured and shown in Table 2 below.

Manufacturing example Reflective central wavelength Brightness (cd / m2) normal Viewing angle 40 ° Viewing angle 60 ° Comparative Example - 570 274 120 Production Example 1 610 nm 543 263 117 Production Example 2 620 nm 550 263 117 Production Example 3 630 nm 549 266 118 Production Example 4 640 nm 559 268 118 Production Example 5 650 nm 563 271 118 Production Example 6 660 nm 565 270 118 Production Example 7 670 nm 567 269 117 Production Example 8 680 nm 568 271 118 Production Example 9 690 nm 567 271 118 Production Example 10 700 nm 568 271 118 Production Example 11 680 nm 549 266 118

Manufacturing example Reflective central wavelength Viewing angle 40 ° Viewing angle 60 ° X Y Xy X Y Xy Comparative Example - 0.014 0.016 0.021 0.027 0.026 0.038 Production Example 1 610 nm 0.025 0.011 0.027 0.039 0.024 0.046 Production Example 2 620 nm 0.026 0.010 0.028 0.041 0.023 0.047 Production Example 3 630 nm 0.024 0.010 0.026 0.039 0.022 0.045 Production Example 4 640 nm 0.024 0.010 0.026 0.039 0.020 0.044 Production Example 5 650 nm 0.019 0.010 0.022 0.035 0.020 0.043 Production Example 6 660 nm 0.017 0.010 0.020 0.032 0.019 0.037 Production Example 7 670 nm 0.015 0.010 0.018 0.031 0.019 0.036 Production Example 8 680 nm 0.013 0.011 0.018 0.029 0.020 0.036 Production Example 9 690 nm 0.013 0.011 0.018 0.029 0.020 0.036 Production Example 10 700 nm 0.013 0.011 0.018 0.029 0.020 0.036 Production Example 11 680 nm 0.004 0.011 0.014 0.025 0.019 0.024

In Table 2, x and y indicate the CIE chromaticity coordinate values, and x and y represent the differences of the corresponding chromaticity coordinate values with respect to the front chromaticity coordinates. DELTA xy is a value reflecting the values of DELTA x and y together, and represents the length of a hypotenuse of a right triangle having DELTA x and y as two sides.

Referring to Tables 1, 2 and 9 to 11, in the production examples in which the narrow-band liquid crystal film is additionally applied, the production examples having a reflection central wavelength of 660 nm or more can be applied to a case where only a broadband reflective polarizing film And the variation of the side color coordinate is smaller than that of the case. In addition, it can be confirmed that the production examples having a reflection central wavelength of 660 nm or more minimize the luminance degradation while improving the lateral color viewing angle.

Production Example 11 in which a retardation film was applied to a narrow band liquid crystal film used a liquid crystal film having the same central reflection wavelength but it was confirmed that the side color viewing angle was significantly improved as compared to Production Example 8 in which a retardation film was not applied.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: optical member
110: narrow band liquid crystal film
130: Broadband reflective polarizing film

Claims (13)

A narrowband reflection polarizer;
A broadband reflective polarizer stacked on the narrowband reflective polarizer; And
And a retardation layer disposed between the narrowband reflective polarizer and the wideband reflective polarizer,
The width of the reflection polarized light wavelength band of the narrowband reflection polarized portion is smaller than the width of the reflection polarized light wavelength band of the wideband reflection polarized portion,
The reflected wavelength center wavelength of the narrowband reflection polarizing section is located in a wavelength band greater than or equal to the red wavelength,
The light transmitted through the narrowband reflection polarizing section and the retardation layer is converted into linearly polarized light,
And the direction of the converted linearly polarized light crosses the transmission axis of the broadband reflective polarizer. The method according to claim 1,
And a reflection polarized wavelength band of the narrowband reflection polarized portion is contained within a wavelength band of reflected polarized light of the wideband reflective polarized portion. 3. The method of claim 2,
And the wavelength range in which the broad-band reflection polarized light is reflected and polarized is 380 nm to 780 nm. 3. The method of claim 2,
And the reflection central wavelength of the narrow-band reflection polarizing portion is 660 nm or more. 5. The method of claim 4,
And the center wavelength of the reflection polarized light of the narrowband reflection polarizing section is in the range of 670 nm to 690 nm. 5. The method of claim 4,
And a reflection half-width of the narrow-band reflection polarizing portion is 70 nm or less. The method according to claim 1,
Wherein the narrowband reflection polarizing section reflects circularly polarized light and the broadband reflective polarizing section reflects linearly polarized light. 8. The method of claim 7,
And the narrowband reflection polarizing section includes a cholesteric liquid crystal layer. 9. The method of claim 8,
The light transmitted through the cholesteric liquid crystal layer is converted into circularly polarized light,
And the retardation layer converts circularly polarized light having passed through the cholesteric liquid crystal layer into linearly polarized light. 10. The method of claim 9,
And the direction of the converted linearly polarized light is perpendicular to the transmission axis of the broadband reflective polarizer. The method according to claim 1,
And a coupling layer interposed between the narrow-band reflective polarizer and the wide-band reflective polarizer to integrate the narrow-band reflective polarizer and the wide-band reflective polarizer. The method according to claim 1,
And the wide-band reflective polarizer is disposed on a light-emitting portion side of the narrow-band reflective polarizer. An optical member according to any one of claims 1 to 12; And
And a liquid crystal display panel disposed on the optical member.

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