JP2007286280A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of moire while attaining a prescribed front luminance even when a lens film formed by melt extrusion is used. <P>SOLUTION: A liquid crystal display device is formed by layering a light source 1, a first film 2 having a plurality of lenses provided on one principal surface thereof, a second film 3 having at least a diffusion function and a liquid crystal panel 4 in this order. A lens pitch P (μm) of the first film 2, a haze value H (%) by measurement of backward diffusion and total light transmittance T (%) in the second film 3, and a pixel pitch Pp (μm) of the liquid crystal panel 4 satisfy H/T×Pp/P>1.6 and P≥110 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device. Specifically, the present invention relates to a liquid crystal display device capable of improving front luminance.

  In recent years, liquid crystal display devices have advantages such as thinness, light weight, and low power consumption, and thus are widely used in personal computers, mobile phones, televisions, and the like. Under such circumstances, liquid crystal display devices are required to improve characteristics such as luminance enhancement, viewing angle improvement, high-speed response, and high definition.

  For example, in Patent Document 1, a translucent lens film having a large number of prism shapes provided in parallel to one main surface and a smooth surface on the other main surface is disposed between the light source and the liquid crystal panel. Thus, it is described that the light emitted from the light source is controlled in the normal direction of the liquid crystal panel to improve the brightness of the front of the panel. It is also described that moire fringes due to interference with the pixel pitch of the panel are prevented by setting the prism pitch of the lens film to 100 μm or less.

  However, in the lens film described above, the function of condensing the light from the light source in the normal direction of the liquid crystal panel is performed by the prism-shaped inclined surface formed on the lens film, and theoretically the pitch of the prism is set. Although it does not depend, in practice, it is very difficult to stably form the apex angle or low angle of the prism as a complete edge in the long term at the time of manufacture. Some R portion is generated at the corner, and this R portion does not contribute to the improvement of the front luminance. Therefore, if the pitch of the prisms of the lens film is narrowed to prevent the occurrence of moire, the R portion increases and a predetermined luminance increase rate cannot be obtained. Even when the R portion is positively formed at the apex angle, if the pitch of the prisms of the lens film is narrowed to prevent the occurrence of moiré, a predetermined luminance increase rate cannot be obtained.

  Further, in Patent Document 2, a light-transmitting lens film having a plurality of prism shapes provided in parallel to one main surface and having a smooth surface on the other main surface is disposed between the light source and the liquid crystal panel. Furthermore, a diffusing film is arranged between the lens film and the liquid crystal panel to prevent moire fringes due to interference between the prism shape formed in large numbers and the pixel pitch of the liquid crystal panel while increasing the brightness of the panel. Has been.

  However, if a diffusion film is disposed between the lens film and the liquid crystal panel, the light collected by the prism may not be used effectively depending on the characteristics of the diffusion film, and a predetermined luminance increase rate may not be obtained.

  As the manufacturing method of the lens film described above, (1) casting method, (2) hot pressing, (3) UV method, (4) thermoplastic resin extrusion method, etc. are known. However, from the viewpoint of productivity, (3) the UV method and (4) the extrusion method are advantageous, and the extrusion method is more advantageous in production speed. In terms of cost, the UV method uses an expensive ultraviolet curable resin (UV resin), and an expensive film such as polyethylene terephthalate (PET) must be used as a base material. It can be said that the extrusion method performed is the most excellent production method.

Japanese Patent Laid-Open No. 06-102507 Japanese Patent Laid-Open No. 06-102506

  However, in the formation of the prism shape of the lens film by melt extrusion molding, it is difficult to 100% transfer the prism shape, so that the apex angle is likely to have an R, thereby reducing the light condensing effect and increasing the predetermined front luminance as described above. It may become impossible to achieve. This phenomenon becomes more prominent as the prism pitch is smaller.

  Accordingly, an object of the present invention is to provide a liquid crystal display device capable of suppressing the generation of moire while achieving a predetermined front luminance even when a lens film formed by melt extrusion is used.

In order to solve the above-described problems, the present invention provides a light source, a first film provided with a plurality of lenses on one main surface, a second film having at least a diffusion function, and a liquid crystal panel in this order. A liquid crystal display device laminated with
The lens pitch P (μm) of the first film, the haze value H (%) and total light transmittance T (%) by the back diffusion measurement of the second film, and the pixel pitch Pp (μm) of the liquid crystal panel , H / T · Pp / P> 1.6 and P ≧ 110 μm.

  In the present invention, the lens pitch P (μm) of the first film, the haze value H (%) and total light transmittance T (%) of the backscattering measurement of the second film, and the pixel pitch Pp ( μm) preferably satisfies the relationship of H / T · Pp / P> 1.9 and P ≧ 110 μm.

  In the present invention, the second film is preferably a reflective polarizer or a diffusion film, a layer having a diffusion function layer, or an adhesive material having a diffusion function.

  In the present invention, the lens is a lens array having a prism shape, a hyperboloid shape, or an aspherical cross section, and is preferably a substantially columnar direction or a lens array shape having a different size in the columnar direction.

  In this invention, the second film having the diffusion function is incident on the measured value of the haze value with respect to the light source side when installed on the liquid crystal panel and the light output side when installed on the liquid crystal panel. When comparing the haze values of the surfaces, it is preferable to have a function of diffusing different haze values.

  In this invention, the second film having the diffusion function is incident on the measured value of the haze value with respect to the light source side when installed on the liquid crystal panel and the light output side when installed on the liquid crystal panel. When comparing the haze values when the surfaces are used, it is preferable that the haze value when the light exit side when installed on the liquid crystal panel is the incident surface has a larger diffusion function.

  As described above, according to the present invention, the lens pitch P (μm) of the first film, the haze value H (%) and the total light transmittance T (%) by the back diffusion measurement of the second film, Since the pixel pitch Pp (μm) of the liquid crystal panel satisfies the relationship of H / T · Pp / P> 1.6 and P ≧ 110 μm, generation of moire can be suppressed while achieving a predetermined front luminance. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.

(1) First Embodiment (1-1) Configuration of Liquid Crystal Display Device FIG. 1 shows a configuration example of a liquid crystal display device according to a first embodiment of the present invention. The liquid crystal display device is provided on the light source 1, the first film 2 provided on the light source 1, the second film 3 provided on the first film 2, and the second film 3. And a liquid crystal panel 4.

  The light source 1 is for supplying light to the liquid crystal panel 4 and is, for example, a fluorescent lamp (FL), an EL (Electro Luminescence), an LED (Light Emitting Diode) or the like. The first film 2 is a lens film for improving the directivity of light emitted from the light source 1.

  FIG. 2 shows a configuration example of the first film 2. Hereinafter, one main surface on the side on which light from the light source 12 enters is referred to as a back surface, and the other main surface on the side from which light from the light source 12 is output is referred to as a front surface. Here, the film means a thin film or a thin plate, and the film includes a sheet, a substrate and the like.

  A flat surface is provided on the back surface side of the first film 2, and a lens array is provided on the front surface side. This lens array is provided with a large number of columnar unit lenses continuously in a direction perpendicular to the generatrix, and the columnar unit lenses include, for example, a triangular prism (prism) shape, a cylindrical shape, a hyperbolic columnar shape, a parabolic columnar shape, It has an aspherical shape. That is, the lens surface of the columnar unit lens is, for example, a triangular prism surface, a cylindrical surface, a hyperboloid, a parabolic column, or an aspherical surface. The unit lens 11 has a focal point fa on the side from which the light from the light source 12 is emitted.

  The second film 3 is a film having at least a diffusion function, and is, for example, a diffusion film or a reflective polarizer. The diffusion film is for diffusing the light transmitted through the first film 2. Further, the reflective polarizer allows only one of the orthogonal polarization components to pass through and reflects the other of the light transmitted through the first film 2.

  Further, the lens pitch P (μm) of the first film 2, the haze value H (%) and total light transmittance T (%) of the second film 3, and the pixel pitch Pp (μm) of the liquid crystal panel 4 However, it preferably satisfies the relationship of H / T · Pp / P> 1.6, more preferably H / T · Pp / P> 1.9.

  In addition, the second film 3 having the diffusing function includes a measured value of a haze value with respect to a light source side when the light source side is installed on the liquid crystal panel 4 and a light output side when the liquid crystal panel 4 is installed. When the haze values are compared with each other as the incident surface, a diffusion function of different haze values is provided.

  In addition, the second film 3 having the diffusing function includes a measured value of a haze value with respect to a light source side when the light source side is installed on the liquid crystal panel 4 and a light output side when the liquid crystal panel 4 is installed. When the haze value is compared with the incident surface, the haze value when the light exit side when installed on the liquid crystal panel 4 is the incident surface is larger.

  The liquid crystal panel 4 is for displaying information by temporally and spatially modulating light supplied from the light source 1. Polarizers (not shown) are provided on both surfaces of the liquid crystal panel 4. This polarizing plate allows only one of orthogonally polarized components of incident light to pass through and blocks the other by absorption. The polarizing plates on both sides of the liquid crystal panel 4 are provided, for example, so that their transmission axes are orthogonal to each other.

(1-2) Configuration of Film Forming Device FIG. 3 shows a configuration example of the film forming device for forming the first film 2 described above. The film forming apparatus includes an extruder 21, a T die 22, a forming roll 23, and an elastic roll 24.

  For forming the first film 2, at least one kind of transparent thermoplastic resin is used. In consideration of the function of controlling the light emission direction, it is preferable to use a thermoplastic resin having a refractive index of 1.4 or more. Examples of such resins include polycarbonate resins, acrylic resins typified by polymethyl methacrylate resins, polyester resins typified by polyethylene terephthalate, amorphous copolymer polyester resins, polystyrene resins, and polyvinyl chloride resins. It is done. In consideration of the transferability of the lens pattern by the extrusion molding method, the melt viscosity in the vicinity of the molding temperature is preferably 1000 Pa or more and 10,000 Pa or less.

  Furthermore, it is preferable to contain at least one type of release agent for the thermoplastic resin. Thus, by including a mold release agent, the adhesiveness between the forming roll 23 and the film 25 when the film 25 is peeled from the forming roll 23 can be adjusted, and the film 25 can be prevented from having a peeling line. The amount of the release agent added to the thermoplastic resin is preferably in the range of 0.02 wt% or more and 0.4 wt% or less after peeling. If it is less than 0.02 wt%, the releasability deteriorates and a peeling line enters the film 25, and if it exceeds 0.4 wt%, the releasability becomes too good before the transparent thermoplastic resin solidifies. It peels on the molding roll 23, and the malfunction which the shape of the unit lens 11 collapses will generate | occur | produce.

  Moreover, it is preferable to contain at least one ultraviolet absorber or light stabilizer for the thermoplastic resin. Thus, by containing the ultraviolet absorber or the light stabilizer, the hue change due to the light irradiation from the light source 1 can be suppressed. Examples of the ultraviolet absorber include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers. ), Cyasorb UV-5411 (manufactured by Sun Chemical Co., Ltd.), Tinuvin P, Tinuvin 234, Tinuvin 320, Tinuvin 327, Tinuvin 327 (manufactured by Ciba Geigy), Sumisorb 110, Sumisorb 140 (manufactured by Sumitomo Chemical Co., Ltd.), 110, 140 , Kemisorb 13 (Kemipro Kasei Co., Ltd.), Uvinul X-19, Uvinul Ms 140 (BASF), Tomissorb 100 Tomissorb 600 (manufactured by Yoshitomi Pharmaceutical Co., Ltd.), Biosorb-80, Biosorb-90 (manufactured by Kyodo Pharmaceutical Co., Ltd.), and the like. Examples of the light stabilizer include hindered amines. Specifically, for example, ADK STAB LA-52 (Asahi Denka Kogyo Co., Ltd.), Sanol LS-770, Sanol LS-765, Sanol LS774 (Sankyo Corporation) ), Sumisorb ™ -061 (manufactured by Sumitomo Chemical Co., Ltd.), and the like. The amount of the ultraviolet absorber or light stabilizer added to the thermoplastic resin is preferably 0.02 wt% or more and 0.4 wt% or less. If it is less than 0.02 wt%, the hue change cannot be suppressed, and if it exceeds 0.4 wt%, the film 25 becomes yellowish.

  Further, in addition to the mold release agent and the ultraviolet absorber described above, additives such as an antioxidant, an antistatic agent, a colorant, a plasticizer, a compatibilizing agent and a flame retardant can be added. However, since most of the additives cause gas generation during the heating of melt extrusion such as the T-die 22 and deteriorate the film-forming property and work environment, it is preferable that the total amount of additives is small. The amount of addition to the plastic resin is preferably 2 wt% or less.

  The extruder 21 melts the resin material supplied from a hopper (not shown) and supplies it to the T die 22. The T-die 22 is a die having a letter-shaped opening, and discharges the resin material supplied from the extruder 21 to the width of the film to be molded.

  The forming roll 23 has a columnar shape, and is configured to be rotationally driven with the central axis as a rotation axis. The cylindrical surface of the forming roll 23 is provided with an engraving shape for transferring a fine pattern onto the film 25 discharged from the T die 22. This engraving shape is, for example, a fine concavo-convex shape for transferring the unit lens 11 to the film, and is formed in the circumferential direction or the width direction (height direction) of the forming roll 23 having a cylindrical shape. The uneven shape is formed, for example, by precision cutting with a diamond bite. The forming roll 23 is configured to be cooled. Specifically, the forming roll 23 has one or more flow paths for flowing a cooling medium therein. As the cooling medium, for example, an oil medium can be used.

  The elastic roll 24 has a columnar shape, and is configured to be rotationally driven with the central axis as a rotation axis. Further, the surface of the elastic roll 24 is configured to be elastically deformable, and when the film 25 is nipped by the forming roll 23 and the elastic roll 24, the surface in contact with the forming roll 23 is crushed.

  The elastic roll 24 is covered with a seamless tube made of, for example, Ni plating, and an elastic body for allowing the surface of the elastic roll 24 to be elastically deformed is provided therein. The configuration and material of the elastic roll 24 are not limited as long as the elastic roll 24 is elastically deformed when contacting the forming roll 23 with a predetermined pressure. As the material, for example, a rubber material, a metal, or a composite material can be used. The elastic roll 24 is configured to be cooled. Specifically, the elastic roll 24 has one or more flow paths for flowing a cooling medium therein. For example, water can be used as the cooling medium.

(1-3) First Film Manufacturing Method Next, an example of a film manufacturing method using the film forming apparatus having the above-described configuration will be described. First, the resin material is melted by the extruder 21 and sequentially supplied to the T die 22, and the film 25 is continuously discharged from the T die 22. Next, the film 25 discharged from the T die 22 is nipped by the forming roll 23 and the elastic roll 24. Thereby, the engraving shape of the forming roll 23 is transferred to the surface of the film 25. Then, after peeling the film 25 from the forming roll 23, the film 25 is cut according to the size of the liquid crystal panel 4. As described above, the intended first film 2 can be obtained.

  As described above, in the first embodiment, the liquid crystal display device includes a light source 1, a first film 2 including a large number of lens bodies provided in parallel with one main surface, and at least a diffusion function. 2 and the liquid crystal panel 4 are laminated in this order. The pitch of the unit lenses 11 of the first film 2 is P (μm), the panel pitch is Pp (μm), and the second film 3 When the haze value is H (%) and the total light transmittance of the second film is T, preferably H / T · Pp / P> 1.6, more preferably H / T · Pp / P> 1. By setting the number to 9, it is possible to achieve a liquid crystal display device free from moire while achieving a predetermined front panel luminance.

  Further, in the film manufacturing method according to the first embodiment, since the first film 2 is formed by the extrusion molding method, the material of the first film 2 can be made inexpensive, and the productivity of the first film 2 can be increased. The effect that generation | occurrence | production of the curvature of the 1st film 2 which can be improved can also be suppressed can be acquired.

(2) Second Embodiment Next, a second embodiment will be described. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 4 shows an example of the configuration of the liquid crystal display device according to the second embodiment of the present invention. The liquid crystal display device includes a light source 1, a first film 2 provided on the light source 1, and a liquid crystal panel 4, and the second film 3 is integrated on the first film 2 side of the liquid crystal panel 4. The configuration is as described above.

(3) Third Embodiment Next, a third embodiment will be described. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 5 shows an example of the configuration of a liquid crystal display device according to the third embodiment of the present invention. The liquid crystal display device includes a light source 1, a first film 2 provided on the light source 1, and a liquid crystal panel 4, and the second film 3 is integrated on the opposite side of the liquid crystal panel 4 from the first film 2. This is a structured configuration.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

<Samples 1-1 to 1-10, 1-14 to 1-15, 2-1 to 2-10, 3-1 to 3-10, 4-1 to 4-10>
A lens film was formed as follows using the film forming apparatus shown in FIG. First, polycarbonate E2000R (manufactured by Mitsubishi Engineering Plastics) was discharged from the T-die 22, nipped by the forming roll 23 and the elastic roll 24, wound around the forming roll 23, and then the film 25 was peeled from the forming roll 23. Next, the peeled film 25 was cut according to the size of the liquid crystal panel. Thus, a lens film in which prismatic unit lenses were continuously provided on one main surface was obtained. The lens pitch (lens width) P was adjusted to the values shown in Table 3 and Table 4.

  Next, a liquid crystal display device provided with a diffusion film was produced as follows. First, a diffusion film having haze H, total light transmittance Tt, diffused light Td, and linear transmission amount Tp shown in Tables 1 and 2 is prepared, and a 19-inch liquid crystal panel having a pixel pitch of 320 μm is prepared. Then, a lens film, a diffusion film, and a liquid crystal panel were laminated in this order to obtain a 19-inch liquid crystal display device.

<Samples 1-11 to 1-13, 2-11 to 2-13, 3-11 to 3-13, 4-11 to 4-13>
First, in the same manner as Samples 1-1 to 1-10, 1-14 to 1-15, 2-1 to 2-10, 3-1 to 3-10, and 4-1 to 4-10, Table 3 and A lens film having a lens pitch shown in Table 4 was obtained.

  Next, a liquid crystal display device in which an adhesive diffusion layer was provided on the liquid crystal panel was produced as follows. First, the adhesive diffusion layer having haze H, total light transmittance Tt, diffused light Td, and linear transmittance Tp shown in Tables 1 and 2 is polarized with respect to the light incident surface side of the liquid crystal panel having a pixel pitch of 320 μm. The plates were bonded to obtain a liquid crystal panel provided with an adhesive diffusion layer. Next, a light source, a lens film, and a liquid crystal panel were laminated in this order to obtain a 19-inch liquid crystal display device.

<Samples 1-16, 2-14, 3-14, 4-14>
First, in the same manner as Samples 1-1 to 1-10, 1-14 to 1-15, 2-1 to 2-10, 3-1 to 3-10, and 4-1 to 4-10, Table 3 and A lens film having a lens pitch shown in Table 4 was obtained.

  Next, a liquid crystal display device without a diffusion film was produced as follows. A liquid crystal panel having a pixel pitch of 320 μm was prepared, and a light source, a lens film, and a liquid crystal panel were laminated in this order to obtain a 19-inch liquid crystal display device.

<Sample 25-1>
A product name ThickBEFIII manufactured by Sumitomo 3M Limited, a diffusion film 2 and a 19-inch liquid crystal panel having a pixel pitch of 320 μm are prepared, and a light source, ThickBEFIII, a diffusion film 2 and a liquid crystal panel are laminated in this order. Thus, a 19-inch liquid crystal display device was obtained.

<Samples 26-1 to 26-4>
First, in the same manner as Samples 1-1 to 1-10, 1-14 to 1-15, 2-1 to 2-10, 3-1 to 3-10, and 4-1 to 4-10, Table 3 And the lens film which has the lens pitch shown in Table 4 was obtained.

  Next, a liquid crystal display device provided with a reflective polarizer was produced as follows. First, a reflection type polarizer (Sumitomo 3M Co., Ltd., trade name: DBEFD) having haze H, total light transmittance Tt, diffused light Td, and linear transmission amount Tp shown in Tables 1 and 2 is prepared, and a pixel pitch. A 19-inch liquid crystal panel having 320 μm was prepared, and a light source, a lens film, a reflective polarizer, and a liquid crystal panel were laminated in this order to obtain a 19-inch liquid crystal display device.

  Next, the liquid crystal display device obtained as described above was evaluated for the occurrence of moire, and the front luminance and the viewing angle were measured. The results are shown in Tables 3-4 and Tables 15-18.

Evaluation of moiré generation: A liquid crystal display device obtained in each configuration in a dark room was input with a white display video, and the occurrence of moiré was observed visually from the front and obliquely. In the table, “◯” in the moire evaluation column indicates that moire has occurred, and “x” indicates that moire has not occurred.
Front luminance measurement: A liquid crystal display device obtained in each configuration in a dark room was input with white display video, turned on for 2 hours, and then a spectral radiance meter CS-1000 made by Konica Minolta at a location 500 mm away from the panel surface. Was installed to evaluate the luminance. The measurement was performed 3 times and an average value was collected.
Viewing angle measurement: Input the white display video to the liquid crystal display device obtained in each configuration in the dark room,
After lighting for 2 hours, the viewing angle was evaluated by installing EZContrast manufactured by ELDIM on the panel surface. The angle in the horizontal direction and the vertical direction with respect to the long side of the panel at the half value of the front luminance was set as the reading viewing angle value.

<Samples 5-1 to 8-14, 26-5 to 26-8>
A 40-inch liquid crystal panel is the same as the above-described samples 1-1 to 4-14 and 26-1 to 26-4 except that a 40-inch liquid crystal panel (full-spec high-definition) having a pixel pitch of 460 μm is used. A display device was obtained. Next, in the same manner as Samples 1-1 to 4-14 and 26-1 to 26-4 described above, the evaluation of the occurrence of moiré and the measurement of front luminance and viewing angle were performed. The results are shown in Tables 5-6 and Tables 17-18.

<Samples 9-1 to 12-14, 26-9 to 26-12>
A 32-inch liquid crystal display device was obtained in the same manner as Samples 1-1 to 4-14 and 26-1 to 26-4 except that a 32-inch liquid crystal panel having a pixel pitch of 510 μm was used. . Next, in the same manner as the above 1-1 to 4-14 and 26-1 to 26-4, the evaluation of the occurrence of moire and the measurement of the front luminance and the viewing angle were performed. The results are shown in Tables 7-8 and Tables 17-18.

<Samples 13-1 to 16-14, 26-13 to 26-16>
Except for molding a lens film in which hyperbolic columnar unit lenses are continuously provided in parallel on one principal surface so that the lens pitch P has the values shown in Tables 8 and 9, Sample 1- A 19-inch liquid crystal display device was obtained in the same manner as in 1-4-14 and 26-1 to 26-4. Next, in the same manner as Samples 1-1 to 4-14 and 26-1 to 26-4 described above, the evaluation of the occurrence of moiré and the measurement of front luminance and viewing angle were performed. The results are shown in Tables 9 to 10 and Tables 17 to 18.

<Samples 17-1 to 20-14, 26-17 to 26-20>
Except that the lens film in which hyperbolic columnar unit lenses are continuously provided in parallel on one main surface is molded so that the lens pitch P has the values shown in Tables 10 and 11, the above sample 5- In the same manner as in 1-8-14 and 26-5 to 26-8, a 40-inch liquid crystal display device was obtained. Next, in the same manner as Samples 5-1 to 8-14 and 26-5 to 26-8 described above, the evaluation of moire generation and the measurement of front luminance and viewing angle were performed. The results are shown in Tables 11-12 and Tables 17-18.

<Samples 21-1 to 24-14, 26-21 to 26-24>
Sample sample 9 described above except that a lens film in which hyperbolic columnar unit lenses are continuously provided in parallel on one main surface is molded so that the lens pitch P becomes a value shown in Tables 12 and 13. A 32-inch liquid crystal display device was obtained in the same manner as -1 to 12-14 and 26-9 to 26-12. Next, in the same manner as in the above sample samples 9-1 to 12-14 and 26-9 to 26-12, the evaluation of the occurrence of moire and the measurement of the front luminance and the viewing angle were performed. The results are shown in Tables 13-14 and Tables 17-18.

Tables 1 and 2 show the characteristics of the diffusion film, the reflective polarizer (DBEFD), and the adhesive diffusion layer used in Samples 1-1 to 26-24. In Tables 1 and 2, the haze H, total light transmittance Tt, diffused light Td, and linear transmission amount Tp were measured as follows.
Haze H: Measured using a haze / transmittance meter HM-150 manufactured by Murakami Color Research Laboratory. Of the transmitted light passing through the test piece, the percentage of the transmitted light deviated by 2.5 ° or more from the incident light by back scattering (diffuse surface is on the outgoing side) was measured according to JIS-K-7136 except for the sample installation method. )
Total light transmittance Tt: Measured using a haze / transmittance meter HM-150 manufactured by Murakami Color Research Laboratory. Of the transmitted light passing through the test piece, the ratio of the total transmitted light beam to the parallel incident light beam was measured (measurement based on JIS-K-7316).
Linear transmission amount Tp: Measured using a haze / transmittance meter HM-150 manufactured by Murakami Color Research Laboratory. Of the transmitted light passing through the test piece, the percentage of transmitted light that falls within the range of less than 2.5 ° with respect to the parallel incident light beam was measured (according to JIS-K-7316 noise measurement method).
Diffuse light Td: The transmittance obtained by subtracting the linear transmittance of the linear component from the total flat light transmittance measured using a haze / transmittance meter HM-150 manufactured by Murakami Color Research Laboratory was defined as diffused light.

  Table 3, Table 5, Table 7, Table 9, Table 11, Table 13, Table 15, and Table 17 show the evaluation results of the occurrence of moire in Samples 1-1 to 26-24. Table 4, Table 6, Table 8, Table 10, Table 12, Table 14, Table 16, Table 18 show the front luminance and viewing angle evaluation results of Samples 1-1 to 26-24.

  6 shows Table 3 (Samples 1-3, 1-15, 1-16, 2-3, 3-3, 4-3) and Table 9 (Samples 13-3, 13-15, 13-16, 14). -3, 15-3, 16-3), and the lens pitch interval of the lens sheet having the prism cross-sectional shape and the hyperboloid cross-sectional shape when the diffusion sheet 2 described in Table 15 (Sample 25-1) is used in combination. The relationship of relative frontal luminance to is shown.

  The values in the figure are displayed assuming that the front luminance when using a prism-shaped lens sheet with a pitch of 50 μm is 100%. From the graph, it can be seen that as the lens pitch is decreased, the relative front luminance decreases, but as the lens pitch is increased, the relative front luminance value increases.

Similarly, the front luminance value when using Thick BEFIII (pitch 50 μm) of 3M was 100%, and the effect of improving the front luminance was confirmed compared to the existing products.
When the lens pitch interval is narrow, the number of ridges and valleys per unit area increases. When this part is enlarged, a flat part region always exists. For this reason, it becomes difficult to obtain the effect as a lens, and as a result, scattering in directions other than the front direction increases, and recyclability due to absolute reflection of light due to the inclination of the slope is impaired, leading to a decrease in front luminance. become.

  On the other hand, by increasing the lens pitch, the number of ridge lines and valleys per unit area decreases, and the flat area of this part also decreases. For this reason, the effect as a lens is not impaired, and as a result, it is possible to prevent a decrease in front luminance in order to reduce scattering to other than the front and to make recycling more effective due to the inclination of the slope. Furthermore, the front luminance can be increased. Therefore, it has been found that the front luminance can be improved by widening the lens pitch.

  However, as described in the results when the diffusion sheet of Tables 3 to 14 is not used together, moire (contrast intensity) is generated only by widening the lens pitch due to the action (interference) with the pixel pitch of the liquid crystal panel. Resulting in. Conventionally, as a method for eliminating this moire, a type having a narrow lens pitch is generally used. However, as described above, the luminance is lowered.

  In contrast, in the present invention, the panel pitch is Pp, the lens pitch is P, the haze value at the time of backscattering measurement of the diffusion functional layer is He, and the total light transmittance measured simultaneously with the backscattering measurement is Tt. In addition, by using a system with a Pp / P · He / Tt value of 1.6 or more, it is possible to improve the brightness while eliminating the moiré that occurred in a single lens with a wide lens pitch. Become.

  Usually, the haze value in JIS or ASTM is expressed by forward scattering measurement with the diffusion function surface as the light incident side, and the haze value obtained by this method is shown in Table 2. Is difficult to find, and the above relationship can be satisfied by using the haze measurement value of the diffusion function surface by backscattering.

  Moreover, when the haze value by backscattering and the haze value by forward scattering are compared, it turns out that a brightness improvement rate becomes high when the measured value by backscattering is larger than the measured value by forward scattering (the diffusion sheet 6 of Table 1). Sample 2-6 to 24-6) as a result of the product used. Therefore, the front luminance can be further improved by using a diffusion functional layer having a high haze value by backscattering measurement.

  Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and examples, and various modifications based on the technical idea of the present invention are possible. It is.

  For example, the numerical values given in the above-described embodiments and examples are merely examples, and different numerical values may be used as necessary.

  In the above-described embodiment, the case where the diffusion film is provided between the first film and the liquid crystal panel has been described. However, the position where the diffusion film is provided is between the first film and the black matrix of the liquid crystal panel. The present invention is not limited to the embodiment described above. For example, you may make it give the diffusion function similar to a diffusion film to the adhesion layer which sticks a polarizing plate to a liquid crystal panel.

It is sectional drawing which shows one structural example of the liquid crystal display device by 1st Embodiment of this invention. It is a perspective view which shows one structural example of a 1st film. It is a schematic diagram which shows one structural example of the film forming apparatus which shape | molds a 1st film. It is sectional drawing which shows one structural example of the liquid crystal display device by 2nd Embodiment of this invention. It is sectional drawing which shows the example of 1 structure of the liquid crystal display device by 3rd Embodiment of this invention. It is a graph which shows the relationship between a lens pitch and a front luminance relative value.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... 1st film, 3 ... 2nd film, 4 ... Liquid crystal panel, 11 ... Unit lens, 21 ... Extruder, 22 ... T Die, 23 ... Forming roll

Claims (6)

A liquid crystal display device in which a light source, a first film provided with a plurality of lenses on one main surface, a second film having at least a diffusion function, and a liquid crystal panel are laminated in this order,
The lens pitch P (μm) of the first film, the haze value H (%) and the total light transmittance T (%) by the back diffusion measurement of the second film, and the pixel pitch Pp (μm) of the liquid crystal panel ) Satisfy the relationship of H / T · Pp / P> 1.6 and P ≧ 110 μm.   The lens pitch P (μm) of the first film, the haze value H (%) and the total light transmittance T (%) by backscattering measurement of the second film, and the pixel pitch Pp (μm) of the liquid crystal panel 2) satisfies the relationship of H / T · Pp / P> 1.9 and P ≧ 110 μm.   The liquid crystal display device according to claim 1, wherein the second film is a reflective polarizer or a diffusion film, a layer having a diffusion function layer, or an adhesive material having a diffusion function.   2. The lens according to claim 1, wherein the lens is a lens array having a prismatic shape, a hyperboloid shape, or an aspherical cross-sectional shape, and has a substantially columnar direction or a lens array shape having different sizes in the columnar direction. The liquid crystal display device described.   The second film having the diffusion function is incident on the measured value of the haze value with respect to the light source side when installed on the liquid crystal panel as a reference, and on the light output side when installed on the liquid crystal panel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a function of diffusing different haze values when comparing the haze values of the surfaces.   The second film having the diffusion function is incident on the measured value of the haze value with respect to the light source side when installed on the liquid crystal panel as a reference, and on the light output side when installed on the liquid crystal panel. When comparing the haze value at the time of making the surface, the haze value at the time of setting the light-emitting side when installed in the liquid crystal panel as the incident surface has a larger diffusion function. Item 2. A liquid crystal display device according to item 1.

Images