JP2008145890A - Liquid crystal display module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display module having a near-infrared ray absorption function and suppressing ejection of the near-infrared ray and reduction of a function of luminance or the like. <P>SOLUTION: The liquid crystal display module having a liquid crystal display element wherein a liquid crystal cell is interposed between a pair of polarizing plates, an optical sheet stacked on the backside of the liquid crystal display element and a backlight of a surface light source stacked on the backside of the optical sheet includes a light diffusion sheet stacked on the surface side of the backlight. The light diffusion sheet has a transparent base material layer and a light diffusion layer layered on the surface side thereof, contains a near-infrared ray absorbing agent and has ≤50% transmittance of the near-infrared ray. The light diffusion sheet is preferably stacked on the backside of the liquid crystal display element (between the liquid crystal display element and a reflective polarizing plate). The light diffusion sheet may contain the near-infrared ray absorbing agent in the base material layer and the like and may have a near-infrared ray absorbing layer containing the near-infrared ray absorbing agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display module having a near infrared absorption function, and more particularly to a liquid crystal display module including a light diffusion sheet having a near infrared absorption function.

  Liquid crystal display modules (LCDs) are widely used as flat panel displays taking advantage of their features such as thinness, light weight, and low power consumption, and their uses are for information displays such as mobile phones, personal digital assistants (PDAs), personal computers, and televisions. It is expanding year by year as a device. In recent years, characteristics required for liquid crystal display modules vary depending on the application, and examples include bright (higher brightness), easier viewing (wider viewing angle), energy saving, thinner and lighter, and the like.

  As shown in FIG. 7, the conventional general liquid crystal display module has a structure in which a liquid crystal display element 61, various optical sheets 62, and a backlight 63 are superposed in this order from the front surface side to the back surface side. The liquid crystal display element 61 has a structure in which a liquid crystal cell 66 is sandwiched between a pair of polarizing plates 64 and 65, and various display modes such as TN and IPS have been proposed. The backlight 63 illuminates the liquid crystal display element 61 from the back side, and forms such as an edge light type (side light type) and a direct type are widespread. The various optical sheets 62 are superposed between the liquid crystal display element 61 and the backlight 63, and in order to make the light emitted from the surface of the backlight 63 enter the entire surface of the liquid crystal display element 61 efficiently and uniformly, the normal direction A light diffusion sheet, a prism sheet, and the like having optical functions such as refraction to the side and diffusion are provided.

  Since the polarizing plates 64 and 65 of the liquid crystal display element 61 absorb 50% of light in principle due to the absorption dichroism, this is one of the main reasons for reducing the light use efficiency of the liquid crystal display module. In order to improve the reduction in the light utilization efficiency of the polarizing plates 64 and 65, a technique for superimposing a reflective polarizing plate (polarization separator) on the back side of the back side polarizing plate 65 in the liquid crystal display module, or a back side polarizing plate. A technique using a reflective polarizing plate instead of 65 has been developed. In this reflection polarizing plate, the transmission axis component of the back-side polarizing plate 65 is transmitted as it is, and the other polarization components are returned to the lower side to reuse the light rays.

The optical sheet 62 is specifically a light diffusion sheet, a prism sheet or the like, and is generally a transparent base layer made of synthetic resin, and a light diffusion layer or prism laminated on the surface of the base layer. And an optical layer such as a row layer (see, for example, JP 2000-89007 A and JP 2004-4970 A). These conventional optical sheets 62 are configured to perform optical functions such as refraction and diffusion in the normal direction by an optical layer having a predetermined structure, and are intended to control visible light.
JP 2000-89007 A JP 2004-4970 A

  Until now, it was thought that there was no near-infrared emission from the liquid crystal display module, so the above conventional liquid crystal display module was designed with the intention of improving brightness, wide viewing angle, energy saving, thinning and weight reduction, etc. It does not have a function to prevent the emission of near infrared rays.

  However, the present inventor has found that near-infrared rays are emitted from the above-described conventional liquid crystal display module due to a cold cathode tube used as a light source of the backlight 63 or the like. As described above, near infrared rays emitted from the liquid crystal display module may cause malfunction in a remote control system of home appliances such as a television, an air conditioner, and a video that use near infrared rays. There is also a risk of adverse effects on the human body. In particular, today, the increase in the screen size of the liquid crystal display device is promoted, and the output of the backlight 63 tends to increase, so that the influence of the above-described near infrared emission is expected to increase.

  The present invention has been made in view of these disadvantages, and an object thereof is to provide a liquid crystal display module having a near-infrared absorption function and capable of suppressing a decrease in performance such as emission of near-infrared light and luminance. It is.

The invention made to solve the above problems is
A liquid crystal display element having a liquid crystal cell sandwiched between a pair of polarizing plates;
An optical sheet superimposed on the back side of the liquid crystal display element;
A liquid crystal display module equipped with a backlight of a surface light source superimposed on the back side of the optical sheet,
A light diffusion sheet is provided on the surface side of the backlight.
This light diffusion sheet has a transparent base material layer and a light diffusion layer laminated on the surface side thereof, contains a near infrared absorber, and has a near infrared transmittance of 50% or less. To do.

  The liquid crystal display module includes a light diffusion sheet on the surface side of the backlight, the light diffusion sheet contains a near infrared absorber, and the near infrared absorption rate is adjusted to 50% or less. The near infrared ray emitted from the backlight can be effectively absorbed, and the emission of the near infrared ray to the outside can be suppressed. Therefore, the liquid crystal display module can prevent adverse effects on the human body due to the emission of near infrared rays and malfunctions of various home appliance remote control devices. Further, the liquid crystal display module can suppress glare of the screen because the light diffusion sheet is used as a means for expressing the near infrared absorption function.

  The light diffusion sheet is preferably overlapped on the back surface of the liquid crystal display element. In a liquid crystal display module, the intensity of light emitted from the surface of the backlight is not uniform and there is polarized light, so the optical sheet (light diffusion sheet, prism sheet, etc.) placed on the surface side is optically By the action (directional diffusion, refraction to the normal direction side, etc.), the amount of light incident on the liquid crystal display element is increased and made uniform. On the other hand, the light diffusion sheet causes a decrease in light transmittance due to the near infrared absorption function. For this reason, a light diffusing sheet that exhibits a near-infrared absorbing function as in the above means is provided on the back surface of the liquid crystal display element, so that the optical action of the optical sheet is exerted on the light emitted from the surface of the backlight. After that, it is configured to exhibit a near infrared absorption effect by the light diffusing sheet, so that the use efficiency of light rays can be increased and the decrease in luminance of the liquid crystal display module due to the development of the near infrared absorption function can be suppressed. .

  It is preferable that a reflective polarizing plate is provided on the back side of the liquid crystal display element, and the light diffusion sheet is provided between the liquid crystal display element and the reflective polarizing plate. In this way, by overlapping the reflective polarizing plate on the back side of the liquid crystal display element, the transmission axis component of the back side polarizing plate of the liquid crystal display element is transmitted as it is, and the other polarizing components are returned to the lower side, and the light beam The utilization efficiency of can be improved. In addition, a light diffusing sheet that exhibits a near-infrared absorbing function like this means is placed between the liquid crystal display element and the reflective polarizing plate, so that optical control is performed at a relatively high light intensity level as in the above means. Then, as a result of performing the near infrared absorption thereafter, it is possible to increase the light use efficiency and suppress the decrease in luminance of the liquid crystal display module due to the development of the near infrared absorption function.

  The light diffusion sheet is preferably laminated on the back side of the base material layer and has a sticking prevention layer in which beads are dispersed in the binder. Thus, by providing the sticking prevention layer on the back surface side of the base material layer, in the liquid crystal display module, the sticking with the prism sheet, the light guide plate and the like disposed on the back surface side of the light diffusion sheet is prevented.

  The said light-diffusion sheet is good to contain a near-infrared absorber in a base material layer, a light-diffusion layer, and / or a sticking prevention layer. By kneading the near-infrared absorber in the basic constituent layer of the light diffusing sheet in this way, the near-infrared absorbing function is expressed without increasing the number of layers, contributing to the thinning of the light diffusing sheet and the prevention of luminance reduction. .

  On the other hand, the light diffusion sheet may have a near-infrared absorbing layer containing a near-infrared absorbing agent in addition to the base material layer and the light diffusing layer. By separately providing the near-infrared absorbing layer in this manner, optical design such as light diffusibility of the light diffusing sheet becomes easy, and control of the near-infrared absorbing function becomes easy and reliable.

  The light diffusion sheet preferably has a visible light transmittance of 50% or more and a total light transmittance of 50% or more. Thus, the fall of the brightness | luminance of the liquid crystal display module resulting from the said light-diffusion sheet having a near-infrared absorption function can be suppressed by making visible light transmittance and total light transmittance into the said range.

  The retardation value of the base material layer of the light diffusion sheet is preferably 50 nm or less. In the liquid crystal display module, in order to improve the light use efficiency, the polarization direction of the incident light beam (the maximum plane direction of the polarization component of the light beam) in the transmission direction of the back side polarizing plate (or the reflective polarizing plate on the back side) of the liquid crystal display element ) Are designed to match the polarization characteristics of the backlight and various optical sheets. Therefore, by reducing the retardation value of the base material layer in this way, the action of converting the polarization direction of the transmitted light by the light diffusion sheet is suppressed, and the polarization is optimized and controlled in the direction of the transmission axis of the polarizing plate or the like. The influence which the said light-diffusion sheet has with respect to can be suppressed.

  Polyethylene terephthalate or polycarbonate may be used as the matrix resin constituting the base material layer of the light diffusion sheet. Since such polyethylene terephthalate is inexpensive and excellent in various functions such as strength and heat resistance, the base layer is formed using polyethylene terephthalate as the main polymer, thereby reducing the cost, strength, heat resistance, and thermal properties of the light diffusion sheet. Dimensional stability and the like are promoted. In addition, since the retardation value of polycarbonate is easy to control, the retardation value of the light diffusion sheet can be easily and reliably adjusted to the above-mentioned small range by forming the base material layer with polycarbonate as the main polymer. Can do.

  The average thickness of the base material layer of the light diffusion sheet is preferably 25 μm or more and 1000 μm or less. As described above, the adverse effect of near-infrared rays emitted from the liquid crystal display module is considered to be as large as that of a large-screen liquid crystal display device. Thus, by setting the average thickness of the base material layer in the above range, the light diffusion is performed. Properties such as sheet strength and anti-bending properties are improved, and it is possible to cope with an increase in the screen of a liquid crystal display device.

  The surface roughness (Ra) of the light diffusion layer of the light diffusion sheet is preferably from 0.1 μm to 0.5 μm, and the surface roughness (Ry) is preferably from 1 μm to 20 μm. Thus, by setting the surface roughness (Ra) and the surface roughness (Ry) of the light diffusing layer in the above ranges, the screen glare of the liquid crystal display module is suppressed while suppressing a decrease in the total light transmittance of the light diffusing sheet. Can be effectively prevented.

  As the light diffusing layer of the light diffusing sheet, (a) one having a light diffusing agent and its binder (bead coating layer, etc.), and (b) one having a minute uneven shape (mat layer, microlens array) Layer, prism row layer of prism sheet, etc.). Such optical sheets such as bead coated sheets, mat sheets, microlens sheets, and prism sheets are usually used in liquid crystal display modules. Therefore, the light diffusion sheet is used as an optical sheet that is generally provided as the means. As a result, the near-infrared emission can be prevented without causing an increase in the number of optical sheets of the liquid crystal display module, and malfunction of the home appliance remote control device can be prevented.

  In the present invention, the “back side” means the side opposite to the display side of the display of the liquid crystal display module. “Near-infrared transmittance” means the transmittance of light having a wavelength of 900 nm to 1100 nm, and “visible transmittance” means the transmittance of light having a wavelength of 400 nm to 700 nm. “Surface roughness (Ra)” means arithmetic mean roughness, and “surface roughness (Ry)” means maximum roughness. The “retardation value (Re)” is a value calculated by Re = (ny−nx) * d.

  As described above, the liquid crystal display module of the present invention prevents the near-infrared emission by overlapping the light diffusion sheet having the near-infrared absorption function, and the home appliance remote control device error caused by the near-infrared emission. It is possible to prevent adverse effects such as operation, and to suppress a decrease in performance such as luminance.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. 1 is a schematic cross-sectional view showing a liquid crystal display module according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view showing a liquid crystal display module according to a form different from the liquid crystal display module of FIG. 1, and FIGS. 6 is a schematic cross-sectional view showing a light diffusion sheet according to a different form from the light diffusion sheet provided in the liquid crystal display module of FIGS. 1 and 2.

  The liquid crystal display module of FIG. 1 is a direct type, and includes a liquid crystal display element 1, a light diffusion sheet 2, an optical sheet 3, and a backlight 4. The liquid crystal display element 1, the light diffusion sheet 2, the optical sheet 3, and the backlight 4 (light exit surface) have substantially the same and rectangular planar shape, and are overlapped in this order from the front surface side to the back surface side.

  The liquid crystal display element 1 includes a front surface side polarizing plate 5 and a back surface side polarizing plate 6 which are arranged substantially in parallel and at a predetermined interval, and a liquid crystal cell 7 sandwiched therebetween. The polarizing plates 5 and 6 are not particularly limited, and in general, polarizers such as iodine polarizers, dye polarizers, and polyene polarizers, and two transparent protective films disposed on both sides thereof. Consists of The transmission axis directions of the front surface side polarizing plate 5 and the back surface side polarizing plate 6 are configured to be orthogonal to each other, and the transmission axis direction of the back surface side polarizing plate 6 is parallel to the short side direction (that is, parallel to the lamp 12). It is comprised so that it may become.

  The liquid crystal cell 7 has a function of controlling the amount of transmitted light, and various known ones are employed. The liquid crystal cell 7 is generally a laminated structure including a substrate, a color filter, a counter electrode, a liquid crystal layer, a pixel electrode, a substrate, and the like. A transparent conductive film such as ITO is used for the pixel electrode. As the display mode of the liquid crystal cell 7, currently proposed, for example, TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), Bumper Ot. , STN (Super Twisted Nematic), VA (Vertically Aligned), HAN (Hybrid Aligned Nematic), and the like.

  The light diffusion sheet 2 includes a base material layer 8, a light diffusion layer 9 laminated on the surface of the base material layer 8, and a near infrared absorption layer 10 laminated on the back surface of the base material layer 8. Since the light diffusing sheet 2 includes the near-infrared absorbing layer 10, it has a function of effectively absorbing near-infrared rays among transmitted light rays.

  Since the base material layer 8 needs to transmit light, it is made of a synthetic resin that is transparent, particularly colorless and transparent. The synthetic resin used for the base material layer 8 is not particularly limited, and examples thereof include polyethylene terephthalate, polyethylene naphthalate, acrylic resin, polycarbonate, polystyrene, polyolefin, cellulose acetate, and weather resistant vinyl chloride. . Among them, polyethylene terephthalate which is excellent in transparency, strength, heat resistance, thermal dimensional stability and anti-bending property is preferable, and polycarbonate which is excellent in retardation value controllability is preferable.

  Although it does not specifically limit as average thickness of the base material layer 8, 25 micrometers or more and 1000 micrometers or less, Especially 150 micrometers or more and 800 micrometers or less, Furthermore, 188 micrometers or more and 500 micrometers or less are preferable. When the average thickness of the base material layer 8 is less than the above range, characteristics such as strength and anti-bending property of the light diffusion sheet 2 are deteriorated, and there is a possibility that it becomes impossible to cope with an increase in the screen size of the liquid crystal display module. . On the other hand, when the thickness of the base material layer 8 exceeds the above range, the luminance of the liquid crystal display module may be lowered, and the liquid crystal display module may be contrary to the demand for thickness reduction.

  The light diffusion layer 9 has a minute and random uneven shape on the surface. The function of diffusing transmitted light is achieved by the fine uneven shape on the surface of the light diffusion layer 9. The light diffusion layer 9 may be integral with or separate from the base material layer 8. The light diffusing layer 9 is formed of the same synthetic resin as that of the base material layer 8, and is an active energy ray curable resin such as an ultraviolet curable resin or an electron beam curable resin excellent in moldability of an uneven shape, transparency. Polyethylene terephthalate having excellent strength and polycarbonate having excellent controllability of retardation value are particularly preferred. Moreover, it is also preferable to use a polyethylene terephthalate film, a polyethylene naphthalate film, or a polycarbonate film as the base material layer 8 and to form the light diffusion layer 9 with an ultraviolet curable resin or the like thereon.

  The surface roughness (Ra) of the light diffusion layer 9 is preferably 0.1 μm or more and 0.5 μm or less, and particularly preferably 0.2 μm or more and 0.4 μm or less. Further, the surface roughness (Ry) of the light diffusion layer 9 is preferably 1 μm or more and 20 μm or less, and particularly preferably 5 μm or more and 15 μm or less. As described above, by setting the surface roughness (Ra) and the surface roughness (Ry) of the light diffusion layer 9 in the above ranges, it is possible to suppress the decrease in the total light transmittance of the light diffusion sheet 2 while suppressing the decrease in the total light transmittance. Screen glare can be effectively prevented.

  The lower limit of the refractive index of the material constituting the light diffusion layer 9 is preferably 1.3 and particularly preferably 1.45. On the other hand, the upper limit of the refractive index of this material is preferably 1.8, and particularly preferably 1.6. Among these ranges, the refractive index of the material constituting the light diffusion layer 9 is most preferably 1.5. Thus, by making the refractive index of the material constituting the light diffusing layer 9 within the above range, the lens-like refracting action on the uneven surface shape is effectively achieved, and the diffusing function of the light diffusing sheet 2 is enhanced.

  In addition to the above synthetic resin, for example, a filler, a plasticizer, a stabilizer, a deterioration inhibitor, a dispersant, and the like may be blended in the base material layer 8 and the light diffusion layer 9.

  The near-infrared absorbing layer 10 has a synthetic resin that is a matrix (binder) and a near-infrared absorber mixed in the synthetic resin. The synthetic resin used for the near-infrared absorbing layer 10 is not particularly limited as long as it is transparent, particularly colorless and transparent so as to transmit light. Specifically, the above-described active energy ray-curable resin, Examples thereof include polycarbonate resins, poly (meth) acrylate resins, cyclic olefin resins, polyester resins, polystyrene, polyvinyl chloride, and polyvinyl acetate. Of these, active energy ray-curable resins having good moldability, acrylic resins having high transparency, and polycarbonate resins having good retardation value controllability are preferable.

  As a near-infrared absorber, what has a high transmittance | permeability with respect to visible light and absorbs a lot of near-infrared light is preferable, and specifically, (a) an imonium compound, a diimonium compound, an aluminum salt compound, Organic near-infrared absorbers such as nitroso compounds and their metal complex salts, cyanine compounds, squarylium compounds, thiol nickel complex compounds, phthalocyanine compounds, triallylmethane compounds, naphthoquinone compounds, anthraquinone compounds, amino compounds, (B) Tin oxide doped with carbon black, antimony oxide or indium oxide, inorganic near infrared absorbers such as oxides, carbides or borides of metals belonging to Group 4, 5 or 6 of the periodic table, and these These compounds can be used in appropriate combination. Among them, an imonium compound, a diimonium compound, or an aluminum salt compound that is excellent in near-infrared absorptivity, visible light transmittance, heat resistance, light resistance and the like is particularly preferable.

  When the near-infrared absorbing layer 10 is formed into a film (sheet), the amount of the near-infrared absorbing agent is 0.01 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass (solid content conversion) of the matrix synthetic resin. Preferably, 0.03 to 1 part by mass is particularly preferable. On the other hand, as the blending amount of the near-infrared absorber when the near-infrared absorbing layer 10 is coated and molded, the amount is preferably 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass (converted to solid content) of the matrix synthetic resin 2 parts by mass or more and 15 parts by mass or less is particularly preferable. If the blending amount of the near-infrared absorber is smaller than the above range, a sufficient near-infrared absorbing function may not be obtained. Conversely, if the blending amount of the near-infrared absorbing agent exceeds the above range, the visible light transmittance decreases. There is a fear.

  The average thickness of the near-infrared absorbing layer 10 is appropriately determined so that the visible light transmittance and the near-infrared absorbing property are suitably balanced from the relationship with the blending amount of the near-infrared absorber. Specifically, the average thickness of the near-infrared absorbing layer 10 when forming a film (sheet) is preferably 10 μm or more and 500 μm or less, and particularly preferably 50 μm or more and 100 μm or less. On the other hand, the average thickness of the near-infrared absorbing layer 10 when coating is formed is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 20 μm or less.

  The near-infrared absorbing layer 10 includes, in addition to the above synthetic resin and near-infrared absorber, for example, an antioxidant, a halogen agent, a phosphoric acid-based flame retardant, a heat-resistant anti-aging agent, an ultraviolet absorber, a lubricant, an antistatic agent. An agent or the like can be blended.

The method for producing the light diffusion sheet 2 is not particularly limited as long as the above structure can be formed, and various methods are employed. As a formation method of the base material layer 8 and the light diffusion layer 9, a method of separately forming the light diffusion layer 9 after creating the base material layer 8, a method of integrally forming the base material layer 8 and the light diffusion layer 9, and Is possible, specifically,
(A) A method in which a synthetic resin is laminated on a sheet mold having an inverted shape of the surface of the light diffusion layer 9 and the sheet mold is peeled off,
(B) an injection molding method in which a molten resin is injected into a mold having an inverted shape of the surface of the light diffusion layer 9;
(C) A method of transferring the shape by re-heating the sheeted resin and pressing between the same mold and metal plate as described above,
(D) An extruded sheet molding method in which a molten resin is passed through a nip between a roll mold having a reverse shape of the surface of the light diffusion layer 9 on the peripheral surface and another roll, and the above shape is transferred.
(E) An ultraviolet curable resin is applied to the base material layer 8, and the shape is transferred to an uncured ultraviolet curable resin by pressing against a sheet mold, a mold, or a roll mold having the same inverted shape as described above. To cure the UV curable resin by applying
(F) An uncured ultraviolet curable resin is filled and applied to a mold or roll having the same inverted shape as described above, pressed by the base material layer 8, leveled, and irradiated with ultraviolet light to cure the ultraviolet curable resin. How to
(G) There is a method of using an electron beam curable resin instead of an ultraviolet curable resin.

Next, as a method for forming the near-infrared absorbing layer 10, specifically,
(A) A coating solution prepared by dissolving or dispersing the above-described synthetic resin and near-infrared absorber in an organic solvent is prepared, and this coating solution is dipped on the back surface of the base material layer 8, a flow coating method, a spray method, Bar coating method, gravure coating method, roll coating method, blade coating method and coating method such as air knife coating method, a method of curing,
(B) A mixture of the above-described synthetic resin and near-infrared absorber is formed into a film or sheet using a method such as photocuring, injection molding, T-die molding, calendar molding, compression molding, or casting, and a base material layer A method of adhering to the back surface of 8,
(C) There is a method of directly laminating a mixture of the above-mentioned synthetic resin and near infrared absorber on the back surface of the base material layer 8 by dry lamination using a T die or the like.

  The optical sheet 3 has optical functions such as refraction in the normal direction side with respect to the transmitted light, diffusion, directional diffusion, and condensing. Specifically, the light sheet 3 is a light diffusion sheet, a prism sheet, and an inverted prism. Sheets, microlens sheets, mat sheets, and the like are applicable. Although the intensity of light emitted from the surface of the backlight 4 is not uniform and has polarization, the liquid crystal display element 1 is caused by optical effects such as directional diffusion by the optical sheet 3 and refraction toward the normal direction. The amount of light incident on the light increases and becomes uniform. Note that a plurality of optical sheets 3 of the same type or different types may be superposed.

  The backlight 4 is a direct type surface light source device, and illuminates the liquid crystal display element 1 from the back side. As the backlight 4, for example, a known one disclosed in JP-A-11-295731 is used. Specifically, the casing 11, the plurality of lamps 12, the diffusion plate 13, and the like are main components. The casing 11 is formed in a square tray shape (thin box shape having an opening on the surface side), and includes a reflective layer such as a metal film on the inner surface so as to emit light on the surface side. The plurality of lamps 12 are linear light sources such as cold-cathode tubes, and are arranged in the casing 11 in parallel and at substantially equal intervals. The diffusion plate 13 is for relaxing the lamp image. For example, a milky white resin plate obtained by mixing an inorganic filler or the like with an acrylic resin or polycarbonate is generally used. The backlight 4 having such a structure is configured to emit light emitted from the lamp 12 from the entire surface.

  Since the liquid crystal display module includes the light diffusion sheet 2 having a near infrared absorption function as described above, it effectively absorbs near infrared rays emitted from the backlight 4 and emits near infrared rays to the outside. Can be suppressed. Therefore, the liquid crystal display module can prevent adverse effects on the human body due to the emission of near infrared rays and malfunctions of various home appliance remote control devices. Further, since the liquid crystal display module has the light diffusion sheet 2 that exhibits a near infrared absorption function superimposed on the back surface of the liquid crystal display element 1, the direction of the optical sheet 3 with respect to the light emitted from the surface of the backlight 4. It is configured to exhibit a near infrared absorption effect after performing optical effects such as diffusive diffusion and refraction in the normal direction side, and as a result, the use efficiency of light rays is increased and the near infrared absorption function is exhibited. A decrease in luminance can be suppressed. Furthermore, the liquid crystal display module can suppress glare of the screen because the light diffusion sheet 2 that exhibits a near infrared absorption function has a light diffusion function.

  The near-infrared transmittance of the light diffusion sheet 2 is 50% or less, preferably 30% or less, particularly preferably 10% or less. By setting the near-infrared transmittance in the above range, it is possible to effectively prevent inconveniences such as malfunction of the remote control system of home appliances and adverse effects on the human body caused by near-infrared rays emitted from the liquid crystal display module. .

  The visible light transmittance in the light diffusion sheet 2 is preferably 50% or more, and the total light transmittance is preferably 50% or more. Thus, the fall of the brightness | luminance of the liquid crystal display module resulting from the said light-diffusion sheet 2 having a near-infrared absorption function can be suppressed by making visible light transmittance and total light transmittance into the said range.

  The retardation value of the base material layer 8 of the light diffusion sheet 2 is preferably 50 nm or less. Thus, by making the retardation value of the base material layer 8 relatively small, the action of converting the polarization direction with respect to the transmitted light of the light diffusion sheet 2 is suppressed, and the polarization in the transmission axis direction of the polarizing plate in the liquid crystal display module is suppressed. The influence of the light diffusion sheet 2 on the optimization and controllability can be suppressed, and as a result, a decrease in the utilization efficiency of light rays can be suppressed, and the liquid crystal display module resulting from having a near infrared absorption function A decrease in luminance can be remarkably suppressed.

  The liquid crystal display module of FIG. 2 includes a liquid crystal display element 1, a light diffusion sheet 2, a reflective polarizing plate 15, an optical sheet 3, and a backlight 4. The liquid crystal display element 1, the light diffusion sheet 2, the reflective polarizing plate 15, the optical sheet 3, and the backlight 4 (light exit surface) have substantially the same and rectangular planar shape, and are stacked in this order from the front surface side to the back surface side. Has been. The liquid crystal display element 1, the light diffusion sheet 2, the optical sheet 3, and the backlight 4 of the liquid crystal display module are the same as the liquid crystal display module of FIG.

  The reflective polarizing plate 15 has a function of separating polarization characteristics between reflected light and transmitted light, and has a transmission axis direction and a reflection axis direction orthogonal to each other on a plane. As the reflective polarizing plate 15, for example, trade name “D-BEF” manufactured by Sumitomo 3M Limited, product name “PCF” manufactured by Nitto Denko Corporation, or the like is used. The reflective polarizing plate 15 is arranged such that the transmission axis direction in the liquid crystal display module is parallel to the transmission axis direction of the back-side polarizing plate 6 of the liquid crystal display element 1, and in particular, in the direct liquid crystal display module, it is usually in the short side direction. It arrange | positions so that it may become parallel (that is, parallel to a linear lamp). Therefore, the reflective polarizing plate 15 transmits the polarization component along the transmission axis direction (parallel to the transmission axis direction of the back-side polarizing plate 6 of the liquid crystal display element 1) among the light rays incident from the back side, and the reflection axis direction. It is configured to reflect and recurse the polarization component along the back side for recycling.

  The liquid crystal display module is provided with the reflective polarizing plate 15 that reflects and recurs the polarization component that is not along the transmission axis direction of the liquid crystal display element 1 as described above, thereby improving the utilization efficiency of the light emitted from the lamp. Can do. Further, since the liquid crystal display module includes a light diffusion sheet 2 having a near-infrared absorption function immediately below the liquid crystal display element 1, as in the liquid crystal display module of FIG. 1, brightness reduction and screen glare are suppressed. However, it is possible to prevent the near infrared rays from being emitted to the outside and to prevent inconveniences such as malfunction of the home appliance remote control device. Further, the liquid crystal display module controls the retardation value of the base material layer 8 of the light diffusion sheet 2 to 50 nm or less, thereby suppressing the conversion action of the polarization direction with respect to the transmitted light of the light diffusion sheet 2, as described above. It is possible to prevent the light polarizing efficiency from being increased by the reflective polarizing plate 15.

  The liquid crystal display module can use the light diffusion sheet of FIGS. 3 to 6 instead of the light diffusion sheet 2. These light diffusion sheets will be described in detail below.

  The light diffusion sheet 21 of FIG. 3 includes a base material layer 22 and a light diffusion layer 9 laminated on the surface of the base material layer 22. The light diffusion layer 9 is formed separately from the base material layer 22, and the content thereof is the same as that of the light diffusion sheet 2 provided in the liquid crystal display module of FIG.

  In the base material layer 22, a near-infrared absorber is kneaded in a synthetic resin. The average thickness of the base material layer 22, the synthetic resin used, the retardation value, and the like are the same as those of the base material layer 8 of the light diffusion sheet 2. In addition, the specific content, blending amount, and the like of the near-infrared absorber in the base material layer 22 are the same as those of the near-infrared absorbing layer 10 of the light diffusion sheet 2. Further, the near-infrared transmittance, visible light transmittance and total light transmittance of the light diffusion sheet 21 are the same as those of the light diffusion sheet 2.

  The light diffusion sheet 21 can effectively absorb near infrared rays emitted from the backlight 4 of the liquid crystal display module as in the light diffusion sheet 2 and can suppress the emission of the near infrared rays to the outside. Moreover, since the said light-diffusion sheet 21 can abbreviate | omit a near-infrared absorption layer compared with the said light-diffusion sheet 2, it can accelerate | stimulate the brightness | luminance and thickness reduction of a liquid crystal display module.

  The light diffusion sheet 31 of FIG. 4 includes a base material layer 32 and a light diffusion layer 33 laminated on the surface of the base material layer 32. The base material layer 32 and the light diffusion layer 33 are integrally formed.

  The base material layer 32 and the light diffusion layer 33 are kneaded with a near-infrared absorber in a synthetic resin. The average thickness of the base material layer 32, the synthetic resin used, the retardation value, and the like are the same as those of the base material layer 8 of the light diffusion sheet 2. The shape, surface roughness and the like of the light diffusion layer 33 are the same as those of the light diffusion sheet 2. In addition, the specific content, blending amount, and the like of the near infrared absorber in the base material layer 32 and the light diffusion layer 33 are the same as those of the near infrared absorption layer 10 of the light diffusion sheet 2. Further, the near-infrared transmittance, visible light transmittance and total light transmittance of the light diffusion sheet 31 are the same as those of the light diffusion sheet 2.

  The light diffusion sheet 31 can effectively absorb near-infrared rays emitted from the backlight 4 of the liquid crystal display module similarly to the light diffusion sheet 2 and can suppress the emission of near-infrared rays to the outside. Moreover, since the said light-diffusion sheet 31 can abbreviate | omit a near-infrared absorption layer compared with the said light-diffusion sheet 2, it can accelerate | stimulate the brightness | luminance and thickness reduction of a liquid crystal display module. Furthermore, since the base material layer 32 and the light diffusion layer 33 are integrally formed, the light diffusion sheet 31 has high manufacturability and can promote low cost.

  5 includes a base material layer 8, a light diffusion layer 42 laminated on the surface of the base material layer 8, and a near infrared absorption layer 10 laminated on the back surface of the base material layer 8. Yes. The base material layer 8 and the near-infrared absorbing layer 10 of the light diffusion sheet 41 are the same as the light diffusion sheet 2 of FIG.

  The light diffusing layer 42 includes a light diffusing agent 43 laid substantially uniformly and densely on the surface of the base material layer 8, and a binder 44 that fixes the light diffusing agent 43. The light diffusing agent 43 is covered with a binder 44. Thus, the light diffusing agent 43 contained in the light diffusing layer 42 can uniformly diffuse the light beam that passes through the light diffusing layer 42 from the back side to the front side. Further, the light diffusing agent 43 forms fine convex portions on the surface of the light diffusion layer 42 substantially uniformly and substantially densely. Thus, the light can be diffused better by the lens-like refracting action of fine irregularities formed on the surface of the light diffusion sheet 41. The average thickness of the light diffusion layer 42 is not particularly limited, but is, for example, about 1 μm to 30 μm.

  The light diffusing agent 43 is a particle having a property of diffusing light, and is roughly classified into an inorganic filler and an organic filler. Specifically, silica, aluminum hydroxide, aluminum oxide, zinc oxide, barium sulfide, magnesium silicate, or a mixture thereof can be used as the inorganic filler. Specific examples of the organic filler include acrylic resin, acrylonitrile resin, polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile, polyamide, and the like. Among these, highly transparent acrylic resins are preferable, and polymethyl methacrylate (PMMA) is particularly preferable.

  The shape of the light diffusing agent 43 is not particularly limited, and examples thereof include a spherical shape, a cubic shape, a needle shape, a rod shape, a spindle shape, a plate shape, a scale shape, and a fiber shape, and among them, a spherical shape having excellent light diffusibility. The beads are preferred.

  The lower limit of the average particle diameter of the light diffusing agent 43 is preferably 1 μm, particularly 2 μm, and more preferably 5 μm. The upper limit of the average particle diameter of the light diffusing agent 43 is preferably 50 μm, particularly 20 μm, and more preferably 15 μm. This is because when the average particle diameter of the light diffusing agent 43 is less than the above range, the unevenness of the surface of the light diffusing layer 42 formed by the light diffusing agent 43 becomes small, and does not satisfy the light diffusibility necessary for the light diffusing sheet. On the other hand, if the average particle diameter of the light diffusing agent 43 exceeds the above range, the thickness of the light diffusing sheet 41 increases and uniform diffusion becomes difficult.

  The lower limit of the amount of the light diffusing agent 43 (the amount in terms of solid content relative to 100 parts of the base polymer in the polymer composition that is the forming material of the binder 44) is preferably 10 parts, particularly 20 parts, and more preferably 50 parts. The upper limit of this amount is preferably 500 parts, particularly 300 parts, and more preferably 200 parts. This is because if the blending amount of the light diffusing agent 43 is less than the above range, the light diffusing property becomes insufficient. On the other hand, if the blending amount of the light diffusing agent 43 exceeds the above range, the light diffusing agent 43 is fixed. It is because the effect to do falls. In the case of the so-called upper light diffusion sheet disposed on the surface side of the prism sheet, high light diffusibility is not required, so the amount of the light diffusing agent 43 is 10 parts or more and 40 parts or less, particularly 10 parts. The amount is preferably 30 parts or less.

  The binder 44 is formed by crosslinking and curing a polymer composition containing a base polymer. With this binder 44, the light diffusing agent 43 is arranged and fixed at substantially equal density over the entire surface of the base material layer 8. In addition, the polymer composition for forming the binder 44 includes, for example, a fine inorganic filler, a curing agent, a plasticizer, a dispersant, various leveling agents, an ultraviolet absorber, an antioxidant, a viscosity modifier, A lubricant, a light stabilizer and the like may be appropriately blended.

  The base polymer is not particularly limited, and examples thereof include acrylic resins, polyurethanes, polyesters, fluorine resins, silicone resins, polyamideimides, epoxy resins, ultraviolet curable resins, and the like. Can be used singly or in combination of two or more. In particular, the base polymer is preferably a polyol that has high processability and can easily form the light diffusion layer 42 by means such as coating. In addition, the base polymer used for the binder 44 is preferably transparent from the viewpoint of increasing light transmittance, and is particularly preferably colorless and transparent.

  The polyol used as the base polymer of the polymer composition is obtained by polymerizing a polyester polyol and a monomer component containing the hydroxyl group-containing unsaturated monomer, and a (meth) acryl unit or the like. An acrylic polyol having is preferable. The binder 44 having such a polyester polyol or acrylic polyol as a base polymer has high weather resistance and can suppress yellowing of the light diffusion layer 42 and the like. In addition, any one of this polyester polyol and acrylic polyol may be used, and both may be used.

  The number of hydroxyl groups in the polyester polyol and acrylic polyol is not particularly limited as long as it is 2 or more per molecule, but if the hydroxyl value in the solid content is 10 or less, the number of crosslinking points decreases, and the solvent resistance , Film properties such as water resistance, heat resistance and surface hardness tend to decrease.

  The polymer composition may contain a fine inorganic filler. By containing the fine inorganic filler in the binder 44, the heat resistance of the light diffusion layer 42 and the light diffusion sheet 41 is improved. The inorganic material constituting the fine inorganic filler is not particularly limited, and an inorganic oxide is preferable. This inorganic oxide is defined as various oxygen-containing metal compounds in which a metal element mainly forms a three-dimensional network through bonds with oxygen atoms. In addition, as the metal element constituting the inorganic oxide, for example, an element selected from Groups 2 to 6 of the Periodic Table of Elements is preferable, and an element selected from Groups 3 to 5 of the Periodic Table of Elements is more preferable. In particular, an element selected from Si, Al, Ti, and Zr is preferable, and colloidal silica in which the metal element is Si is most preferable as a fine inorganic filler in terms of heat resistance improvement effect and uniform dispersibility. The shape of the fine inorganic filler may be any particle shape such as a spherical shape, a needle shape, a plate shape, a scale shape, and a crushed shape, and is not particularly limited.

  The lower limit of the average particle size of the fine inorganic filler is preferably 5 nm, and particularly preferably 10 nm. On the other hand, the upper limit of the average particle size of the fine inorganic filler is preferably 50 nm, particularly preferably 25 nm. This is because if the average particle size of the fine inorganic filler is less than the above range, the surface energy of the fine inorganic filler becomes high and aggregation or the like is likely to occur. Conversely, if the average particle size exceeds the above range, This is because it becomes cloudy under the influence of a short wavelength and the transparency of the light diffusion sheet 41 cannot be maintained completely.

  The lower limit of the amount of the fine inorganic filler based on 100 parts of the base polymer (the amount of only the inorganic component) is preferably 5 parts, particularly preferably 50 parts in terms of solid content. On the other hand, the upper limit of the amount of the fine inorganic filler is preferably 500 parts, more preferably 200 parts, and particularly preferably 100 parts. This is because if the blending amount of the fine inorganic filler is less than the above range, the heat diffusion property of the light diffusing sheet 41 may not be sufficiently exhibited. Conversely, the blending amount exceeds the above range. This is because blending into the polymer composition becomes difficult and the light transmittance of the light diffusion layer 42 may be lowered.

  As the fine inorganic filler, a material having an organic polymer fixed on its surface may be used. Thus, by using the organic polymer-fixed fine inorganic filler, the dispersibility in the binder 44 and the affinity with the binder 44 can be improved. The organic polymer is not particularly limited with respect to its molecular weight, shape, composition, presence or absence of a functional group, and any organic polymer can be used. Moreover, about the shape of an organic polymer, the thing of arbitrary shapes, such as a linear form, a branched form, and a crosslinked structure, can be used.

  The fine inorganic filler may contain an organic polymer in the fine particles. As a result, moderate softness and toughness can be imparted to the inorganic material that is the core of the fine inorganic filler.

  The base polymer is preferably a polyol having a cycloalkyl group. Thus, by introducing a cycloalkyl group into the base polymer (polyol) constituting the binder 44, the hydrophobicity of the binder 44, such as water repellency and water resistance, is increased, and the said polymer under high temperature and high humidity conditions. The bending resistance, dimensional stability, etc. of the light diffusion sheet 41 are improved. In addition, the basic properties of the coating film such as the hardness, weather resistance, feeling of holding, and solvent resistance of the light diffusion layer 42 are improved. Furthermore, the affinity with the fine inorganic filler having the organic polymer fixed on the surface and the uniform dispersibility of the fine inorganic filler are further improved.

  The cycloalkyl group is not particularly limited, and examples thereof include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cycloundecyl group, a cyclododecyl group, a cyclotridecyl group, Examples thereof include a cyclotetradecyl group, a cyclopentadecyl group, a cyclohexadecyl group, a cycloheptadecyl group, and a cyclooctadecyl group.

  The polyol having a cycloalkyl group can be obtained by copolymerizing a polymerizable unsaturated monomer having a cycloalkyl group. The polymerizable unsaturated monomer having a cycloalkyl group is a polymerizable unsaturated monomer having at least one cycloalkyl group in the molecule. The polymerizable unsaturated monomer is not particularly limited, and examples thereof include cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, and cyclododecyl (meth) acrylate.

  Moreover, it is good to contain isocyanate as a hardening | curing agent in a polymer composition. Thus, by containing an isocyanate hardening | curing agent in a polymer composition, it becomes a much stronger crosslinked structure and the film physical property of the light-diffusion layer 42 improves further. As this isocyanate, the same substance as the polyfunctional isocyanate compound is used. Of these, aliphatic isocyanates that prevent yellowing of the coating are preferred.

  Furthermore, an antistatic agent may be kneaded in the polymer composition. By forming the binder 44 from the polymer composition in which the antistatic agent is kneaded in this way, an antistatic effect is exhibited in the light diffusion sheet 41, and it is difficult to suck dust or to overlap with the prism sheet or the like. It is possible to prevent inconvenience caused by electrostatic charging. Further, when the surface is coated with an antistatic agent, the surface becomes sticky or contaminated, but such an adverse effect is reduced by kneading into the polymer composition. The antistatic agent is not particularly limited. For example, anionic antistatic agents such as alkyl sulfates and alkyl phosphates, cationic antistatic agents such as quaternary ammonium salts and imidazoline compounds, polyethylene glycol type Nonionic antistatic agents such as polyoxyethylene sorbitan monostearic acid ester and ethanolamides, and high molecular antistatic agents such as polyacrylic acid are used. Among these, a cationic antistatic agent having a relatively large antistatic effect is preferable, and an antistatic effect is exhibited by addition of a small amount.

  Moreover, it is good to contain a ultraviolet absorber in the said polymer composition. By forming the binder 44 from the polymer composition containing the ultraviolet absorber in this way, the light diffusion sheet 41 is given an ultraviolet cut function, and a small amount of ultraviolet rays emitted from the lamp of the backlight unit are cut. It is possible to prevent the liquid crystal layer from being broken.

  The ultraviolet absorber is not particularly limited as long as it is a compound that absorbs ultraviolet rays and can be efficiently converted into heat energy, and is stable to light, and a known one can be used. . Among them, salicylic acid-based UV absorbers, benzophenone-based UV absorbers, benzotriazole-based UV absorbers, and cyano have a high UV-absorbing function, good compatibility with the above-mentioned base polymer, and exist stably in the base polymer. An acrylate ultraviolet absorber is preferable, and one or more selected from these groups may be used. As the ultraviolet absorber, a polymer having an ultraviolet absorbing group in the molecular chain (for example, “Udable UV” series of Nippon Shokubai Co., Ltd.) is also preferably used. By using a polymer having an ultraviolet absorbing group in such a molecular chain, the binder 44 is highly compatible with the main polymer, and deterioration of the ultraviolet absorbing function due to bleeding out of the ultraviolet absorbent can be prevented. It is also possible to use a polymer having an ultraviolet absorbing group in the molecular chain as the base polymer of the binder 44. Further, it is possible to use the polymer to which the ultraviolet absorbing group is bonded as the base polymer of the binder 44, and further to contain an ultraviolet absorber in the base polymer, so that the ultraviolet absorbing function can be further improved.

  The lower limit of the content of the ultraviolet absorber relative to the base polymer of the binder 44 is preferably 0.1% by mass, particularly 1% by mass, and more preferably 3% by mass, and the upper limit of the content of the ultraviolet absorber is 10% by mass. In particular, 8% by mass, and further 5% by mass are preferable. This is because if the mass ratio of the ultraviolet absorber to the base polymer is smaller than the lower limit, the ultraviolet absorption function of the light diffusion sheet 41 cannot be effectively achieved. This is because when the ratio exceeds the above upper limit, the base polymer is adversely affected, and the strength and durability of the binder 44 are lowered.

  It is also possible to use an ultraviolet stabilizer (including a base polymer in which an ultraviolet stabilizing group is bonded to a molecular chain) instead of the ultraviolet absorbent or together with the ultraviolet absorbent. By this ultraviolet stabilizer, radicals generated by ultraviolet rays, active oxygen and the like are inactivated, and ultraviolet stability, weather resistance and the like can be improved. As this ultraviolet stabilizer, a hindered amine ultraviolet stabilizer having high stability against ultraviolet rays is preferably used. In addition, the combined use of an ultraviolet absorber and an ultraviolet stabilizer significantly improves deterioration prevention and weather resistance due to ultraviolet rays.

  Next, a method for manufacturing the light diffusion sheet 41 will be described. The light diffusing sheet 41 is produced by (a) a step of producing a light diffusing layer coating liquid by mixing a light diffusing agent 43 with a polymer composition constituting the binder 44, and (b) the light diffusing layer. It has the process of laminating | stacking the light-diffusion layer 42 by applying the coating liquid for layers on the surface of the base material layer 8, and the process of laminating | stacking the near-infrared absorption layer 10 (c). The means for laminating the near infrared absorption layer 10 is the same as that of the light diffusion sheet 2.

  The light diffusing sheet 41 has a high light diffusing function due to reflection and refraction at the interface of the light diffusing agent 43 contained in the light diffusing layer 42 and refraction at fine irregularities formed on the surface of the light diffusing layer 42. Due to this light diffusion function, it has a refraction function (directional diffusion function) toward the normal direction. Moreover, the light diffusion sheet 41 effectively absorbs near-infrared rays emitted from the backlight 4 of the liquid crystal display module by the near-infrared absorbing layer 10 containing a near-infrared absorber, similar to the light diffusion sheet 2, It is possible to prevent malfunction of the remote control system of home appliances and adverse effects on the human body caused by near infrared rays emitted from the liquid crystal display module. Further, the light diffusing sheet 41 can be replaced with a general light diffusing sheet normally used in a liquid crystal display module, and without increasing the number of optical sheets installed in the liquid crystal display module. Infrared emission is prevented, and as a result, a decrease in luminance of the liquid crystal display module due to the development of the near infrared absorption function can be suppressed.

  6 includes a base material layer 8, a light diffusion layer 42 laminated on the front side of the base material layer 8, a near infrared absorption layer 10 laminated on the back surface of the base material layer 8, and a near infrared light. And an anti-sticking layer 52 laminated on the back surface of the absorption layer 10. The base material layer 8 and the near-infrared absorbing layer 10 in the light diffusion sheet 51 are the same as the light diffusion sheet 2, and the light diffusion layer 42 is the same as the light diffusion sheet 41.

  The anti-sticking layer 52 includes a binder 54 and beads 53 dispersed in the binder 54. The binder 54 is also formed by crosslinking and curing a polymer composition similar to the binder 44 of the light diffusion layer 42. Further, as the material of the beads 53, the same material as the light diffusing agent 43 of the light diffusing layer 42 is used. The thickness of the anti-sticking layer 52 (the thickness of the binder 54 portion where the beads 53 are not present) is not particularly limited, but is, for example, about 1 μm or more and 10 μm or less.

  The blending amount of the beads 53 is relatively small, the beads 53 are separated from each other and dispersed in the binder 54, and most of the beads 53 have a very small amount protruding from the binder 54 at the lower end. Therefore, when this light diffusion sheet 51 is laminated with another optical sheet or the like, the lower end of the protruding bead 53 may come into contact with the surface of the optical sheet or the like, and the entire back surface of the light diffusion sheet 51 may come into contact with the optical sheet or the like. Absent. As a result, sticking between the light diffusion sheet 51 and the optical sheet or the like is prevented, and uneven brightness on the screen of the liquid crystal display module is suppressed.

  Next, a method for manufacturing the light diffusion sheet 51 will be described. The manufacturing method of the light diffusion sheet 51 includes: (a) a step of manufacturing a coating solution for a light diffusion layer by mixing a light diffusion agent 43 into a polymer composition constituting the binder 44; and (b) this light diffusion. A step of laminating the light diffusion layer 42 by coating the surface of the base material layer 8 with a layer coating liquid, (c) a step of laminating the near-infrared absorbing layer 10 on the back surface of the base material layer 8; d) a step of producing an anti-sticking layer coating solution by mixing the beads 53 with the polymer composition constituting the binder 54; and (e) the back surface of the near-infrared absorbing layer 10 using the anti-sticking layer coating solution. And the step of laminating the anti-sticking layer 52 by applying the coating. The means for laminating the near infrared absorption layer 10 is the same as that of the light diffusion sheet 2.

  The light diffusion sheet 51 has a high light diffusion function (directional diffusion function) due to the light diffusion layer 42 as in the light diffusion sheet 41. In addition, the light diffusion sheet 51 effectively absorbs near infrared rays emitted from the backlight 4 of the liquid crystal display module by the near infrared absorption layer 10 containing a near infrared absorber, similar to the light diffusion sheet 2, It is possible to prevent malfunction of the remote control system of home appliances and adverse effects on the human body caused by near infrared rays emitted from the liquid crystal display module. Further, the light diffusion sheet 51 is prevented from sticking to other components by the anti-sticking layer 52 laminated on the back surface side, and the brightness unevenness of the screen of the liquid crystal display module is suppressed.

  The liquid crystal display module of the present invention is not limited to the above embodiment. For example, the present invention can be applied to a liquid crystal display module including an edge light type (also referred to as a side light type) backlight, and emission of near infrared rays can be prevented. Specifically, the edge light type backlight has a rectangular plate-shaped light guide plate having a substantially wedge-shaped cross-sectional shape that is thick on one end surface (light incident surface) side and thin on the opposite end surface side, and extends along the light incident surface of the light guide plate. A linear lamp disposed on the back surface of the light guide plate, a reflector disposed on the back side of the light guide plate, a reflector disposed so as to surround the side of the lamp (excluding the light incident surface side of the light guide plate), and the light guide plate A light reflecting film deposited on the opposite end surface of the light incident surface, an upper opening casing for housing these components, etc., and configured to emit light emitted from the lamp from the entire surface of the light guide plate. Yes.

  In addition, the light diffusion sheet provided in the liquid crystal display module of the present invention may be laminated with other layers such as an ultraviolet absorber layer, an antistatic agent layer, a top coat layer, and an anchor coat layer.

  In the light diffusing sheet 2 or the light diffusing sheet 21, the light diffusing layer 9 may also contain a near infrared absorber. Further, in the light diffusion sheet 2 or the light diffusion sheet 21, instead of the light diffusion layer 9 having a minute and random uneven shape on the surface, a light diffusion layer having a microlens array composed of a plurality of microlenses on the surface, It can be set as the light-diffusion layer etc. which have a triangular prism-shaped prism in many strips.

  In the light diffusion sheet 41 or the light diffusion sheet 51, the near-infrared absorbing layer 10 can be omitted, and the base material layer 22 of the light diffusion sheet 21 can be used in place of the base material layer 8. Further, in the light diffusion sheet 41 or the light diffusion sheet 51, the near infrared absorption layer 10 is omitted, the binder 44 of the light diffusion layer 42, the light diffusion agent 43 of the light diffusion layer 42, the binder 54 of the sticking prevention layer 52 and / or sticking. A near-infrared absorber can also be contained in the beads 53 of the prevention layer 52. This means also provides a near infrared absorption function.

  As described above, the liquid crystal display module of the present invention is useful as a component of a liquid crystal display device, and is particularly suitable for use in a large screen liquid crystal display device.

1 is a schematic cross-sectional view showing a liquid crystal display module according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a liquid crystal display module according to a different form from the liquid crystal display module of FIG. FIG. 1 is a schematic cross-sectional view showing a light diffusion sheet according to a different form from the light diffusion sheet provided in the liquid crystal display module of FIG. Typical sectional drawing which shows the light-diffusion sheet which concerns on the form different from the light-diffusion sheet of FIG.1, FIG2 and FIG.3 Typical sectional drawing which shows the light-diffusion sheet which concerns on the form different from the light-diffusion sheet of FIGS. 1-4 Typical sectional drawing which shows the light-diffusion sheet which concerns on the form different from the light-diffusion sheet of FIGS. Schematic sectional view showing a general liquid crystal display module

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2 Light diffusion sheet 3 Optical sheet 4 Backlight 5 Front surface side polarizing plate 6 Back surface side polarizing plate 7 Liquid crystal cell 8 Base material layer 9 Light diffusion layer 10 Near-infrared absorption layer 11 Casing 12 Lamp 13 Diffusing plate 15 Reflected polarization Plate 21 Light diffusing sheet 22 Base material layer 31 Light diffusing sheet 32 Base material layer 33 Light diffusing layer 41 Light diffusing sheet 42 Light diffusing layer 43 Light diffusing agent 44 Binder 51 Light diffusing sheet 52 Sticking preventing layer 53 Beads 54 Binder

Claims (13)

A liquid crystal display element having a liquid crystal cell sandwiched between a pair of polarizing plates;
An optical sheet superimposed on the back side of the liquid crystal display element;
A liquid crystal display module equipped with a backlight of a surface light source superimposed on the back side of the optical sheet,
A light diffusion sheet is provided on the surface side of the backlight.
This light diffusion sheet has a transparent base material layer and a light diffusion layer laminated on the surface side thereof, contains a near infrared absorber, and has a near infrared transmittance of 50% or less. LCD module.   The liquid crystal display module according to claim 1, wherein the light diffusion sheet is provided on the back surface of the liquid crystal display element. A reflective polarizing plate is provided on the back side of the liquid crystal display element.
The liquid crystal display module according to claim 1, wherein the light diffusion sheet is provided between the liquid crystal display element and the reflective polarizing plate.   4. The liquid crystal display module according to claim 1, wherein the light diffusion sheet has a sticking prevention layer laminated on the back surface side of the base material layer, and beads are dispersed in the binder.   The liquid crystal display module according to any one of claims 1 to 4, wherein the light diffusion sheet contains a near-infrared absorber in the base material layer, the light diffusion layer, and / or the anti-sticking layer.   The liquid crystal display module according to any one of claims 1 to 4, wherein the light diffusion sheet has a near-infrared absorbing layer containing a near-infrared absorber.   The liquid crystal display module according to any one of claims 1 to 6, wherein the light diffusion sheet has a visible light transmittance of 50% or more and a total light transmittance of 50% or more.   The liquid crystal display module according to any one of claims 1 to 7, wherein a retardation value of the base material layer of the light diffusion sheet is 50 nm or less.   The liquid crystal display module according to any one of claims 1 to 8, wherein polyethylene terephthalate or polycarbonate is used as a matrix resin constituting the base material layer of the light diffusion sheet.   The liquid crystal display module according to any one of claims 1 to 9, wherein an average thickness of the base material layer of the light diffusion sheet is 25 µm or more and 1000 µm or less.   The surface roughness (Ra) of the light diffusion layer of the light diffusion sheet is from 0.1 µm to 0.5 µm, and the surface roughness (Ry) is from 1 µm to 20 µm. The liquid crystal display module according to item.   The liquid crystal display module according to any one of claims 1 to 11, wherein the light diffusion layer of the light diffusion sheet includes a light diffusion agent and a binder thereof.   The liquid crystal display module according to any one of claims 1 to 11, wherein the light diffusion layer of the light diffusion sheet has a minute uneven shape on a surface thereof.

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