JP2014238593A - Optical laminate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical laminate where dimensional change ratio due to temperature change is extremely small, distortion of a lens array is suppressed, and it is possible to appropriately control a traveling direction of light emitted from the lens array over a long period of time.SOLUTION: An optical laminate 10 is obtained by laminating: a polarizing film 13 having a thin polarizing film 12 laminated on one major surface of a substrate 11; and an optical element (a lens array 14). The thin polarizing film 12 has thickness of 8 μm or less. The substrate 11 has thickness of 20 μm to 80 μm. Otherwise, the optical element is a patterned retardation plate 114 having a plurality of regions having different directions of slow axes.

Description

  The present invention relates to an optical laminate having a thin polarizing film and a liquid crystal display device including the optical laminate.

  Liquid crystal display devices are thin, lightweight, and have low power consumption, so they are widely used in liquid crystal televisions, computer monitors, mobile phones, car navigation systems, portable game machines, and the like.

  However, the liquid crystal display device has a problem that the viewing angle dependency of display quality is large. The viewing angle dependency is, for example, a normal color and a high-contrast image when viewed from the front, but the color is different, the gradation is inverted, or the contrast is lowered when viewed from an oblique direction. That means. An angle range in which a normal image can be observed is called a viewing angle, and a large viewing angle dependency means a narrow viewing angle.

  The viewing angle dependency is caused by various causes such as the alignment mode and refractive index anisotropy of the liquid crystal molecules, the characteristics of the polarizing film, and the directivity of the light source. In order to reduce the viewing angle dependency of the liquid crystal display device, there is known a liquid crystal display device in which, for example, a lens array locked to a polarizing plate is arranged on the viewer side of the liquid crystal display panel. The lens array is also called a lens sheet, and is a periodic array of a plurality of minute lenses.

  Although the viewing angle characteristics are improved by arranging the lens array on the liquid crystal display panel, the periodic structure formed by the pixels of the liquid crystal panel and the periodic structure of the lens array interfere with each other, resulting in moiré fringes. May decrease.

  In order to prevent the occurrence of such moire fringes, the pixel pitch of the liquid crystal panel and the lens pitch of the lens array are controlled with high accuracy, and an appropriate angle is provided between the pixel arrangement direction of the liquid crystal panel and the lens arrangement direction of the lens array. There is a need (for example, Patent Document 1).

  In addition, stereoscopic display devices that can enhance the realistic sensation of display have been developed. There are several methods for stereoscopic display. In Patent Document 2, a plurality of right-eye pixel groups and left-eye pixel groups that are two-dimensionally arranged are alternately arranged in a column direction on a liquid crystal panel, and each pixel is arranged on the front polarizing film of the liquid crystal panel. There is described a stereoscopic display device in which a pattern phase difference plate corresponding to a group is formed and a lenticular lens is arranged on the front surface thereof.

  To obtain an appropriate 3D display, use a lenticular lens that matches the periodic structure of the pixel group and retardation plate, and control the periodic structure of the pixel group and retardation plate and the periodic structure of the lenticular lens with high accuracy. Need to be placed.

  Some 3D display devices do not have a pattern phase difference plate. However, since the structure other than the pattern phase difference plate is the same as that of the 3D display device, it has the same problem as the 3D display device.

JP 2001-42310 A JP-A-9-304740

  In the liquid crystal display panel, the pixel pitch of the liquid crystal panel and the lens pitch of the lens array are controlled with high precision in order to prevent the occurrence of moiré fringes, color unevenness, and blurring of the three-dimensional display. It is necessary to provide an appropriate angle in the lens arrangement direction.

  There is a polarizing film between the substrate of the liquid crystal panel and the lens array, and the lens array is bonded to the polarizing film. If the size of the polarizing film changes due to heat generated when the backlight is turned on or temperature / humidity due to the external environment, the lens array may be distorted due to the influence of the polarizing film.

  When the lens array is distorted, the lens pitch and the lens arrangement direction are changed, moire fringes and color unevenness are generated, and the display quality may be deteriorated. Further, the lens array may be peeled off from the polarizing film due to distortion of the lens array.

  In the stereoscopic display device, when the dimension of the polarizing film changes due to the heat generated when the backlight is turned on, the temperature and humidity due to the external environment, the pattern retardation plate attached to the polarizing film, the pixel group, A positional deviation occurs between the lens array. As a result, stereoscopic display blur may occur.

  Further, when the lens array is bonded to the pattern phase difference plate, distortion may occur in the lens array and color unevenness may occur, and the lens array may be peeled off from the pattern phase difference plate.

  In a conventional polarizing film used for a liquid crystal display panel and a stereoscopic display device, a transparent protective film is bonded to both surfaces of a film called a polarizer having a thickness of about 30 μm. Conventional polarizing films typically exhibit a dimensional change (shrinkage) of about −0.5% under an environment of 80 ° C. and 120 hours. When a dimensional change of -0.5% occurs, the lens array and the pattern phase difference plate are affected, and there is a possibility that moire fringes, color unevenness, and stereoscopic display blur may occur. That is, since the conventional polarizing film has low dimensional stability, it is difficult to prevent the occurrence of moire fringes, color unevenness, and stereoscopic display blur.

  In the present invention, a polarizing film with little dimensional change was produced. The polarizing film and the lens array were laminated to produce an optical laminate. And the liquid crystal display device provided with the optical laminated body was produced.

  In the present invention, the dimensional change rate of the polarizing film is typically −0.2% or less in an environment of 80 ° C. and 120 hours (−0.2% or less means −0.2% to Meaning 0%). In the liquid crystal display panel and the stereoscopic display device using the polarizing film of the present invention, since the dimensional change rate of the polarizing film is small, the distortion of the lens array is small, and there is little possibility of generating moire fringes, color unevenness, and stereoscopic display blur.

The gist of the present invention is as follows.
(1) The optical layered body of the present invention comprises an optical element comprising a lens array having a plurality of lenses for controlling the traveling direction of light, and a polarizing film in which a thin polarizing film is laminated on one principal surface of a substrate. Have. The thin polarizing film is made of a polyvinyl alcohol-based resin that has been subjected to longitudinal stretching at the free end together with the substrate and dyed with iodine. The optical element and the polarizing film are laminated, and the thickness of the thin polarizing film is 8 μm or less. In the polarizing film, the dimensional change rate in the MD (longitudinal) direction and the TD (width) direction are both −0.2% or less (−0.2% to 0%).
(2) In the optical layered body of the present invention, the base material stretched together with the polyvinyl alcohol resin has a thickness of 20 μm to 80 μm.
(3) The optical laminate of the present invention is a polarizing film obtained by transferring a thin polarizing film having a thickness of 8 μm or less made of a polyvinyl alcohol resin stretched together with a base material and dyed with iodine to another base material and laminating it. And an optical element composed of a lens array having a plurality of lenses for controlling the traveling direction of light.
(4) In the optical laminated body of this invention, the thickness of said another base material is 20 micrometers-80 micrometers.
(5) The liquid crystal display device of the present invention includes a liquid crystal panel and the optical laminate described above.

  The optical layered body formed by laminating the polarizing film and the optical element according to the present invention has, for example, an extremely small dimensional change rate due to a temperature change and suppresses distortion of the lens array. The traveling direction can be appropriately controlled.

  In addition, the liquid crystal display device of the present invention provided with this optical laminate can appropriately control the traveling direction of light emitted from the optical laminate even when left in a high temperature state for a long time. Unevenness and stereoscopic display blur are unlikely to occur, and high-quality display can be achieved.

  In addition, optical laminates that have a patterned phase difference plate for 3D display have very little dimensional change due to temperature changes, so they can be kept from shifting with pixel groups and lens arrays, and there is no 3D display blur. Display.

Schematic diagram of the optical laminate of the present invention Schematic diagram of the optical laminate of the present invention (A) Schematic diagram of conventional polarizing film, (b) Schematic diagram of polarizing film used in the present invention, (c) Schematic diagram of polarizing film used in the present invention, (d) Polarizing film used in the present invention Schematic diagram, (e) Schematic diagram of polarizing film used in the present invention, (f) Schematic diagram of polarizing film used in the present invention (A) Schematic diagram of lens array used in the present invention, (b) Schematic diagram of fly-eye lens used in the present invention. (A) Schematic diagram of the liquid crystal display device of the present invention, (b) Schematic diagram of the liquid crystal display device of the present invention. (A) Schematic diagram of the liquid crystal display device of the present invention, (b) Schematic diagram of the liquid crystal display device of the present invention. Schematic diagram of a conventional liquid crystal display device Schematic diagram of the liquid crystal display device of the present invention

[Optical laminate]
In FIG. 1, the cross section of an example of the optical laminated body 10 of this invention is shown typically. A polarizing film 13 formed by laminating a thin polarizing film 12 and a lens array 14 are laminated and integrated on one main surface of the substrate 11 via an adhesive layer 15. The thickness of the thin polarizing film 12 is 8 μm or less. Further, the thin polarizing film 12 is stretched together with the base material so that an absorption axis and a transmission axis are expressed and functions as a polarizing element. The lens array 14 is typically a sheet and is also called a lens sheet.

  At this time, the main surface of the lens array 14 on the lens 14 a side is disposed so as to face the thin polarizing film 12, and the adjacent lenses 14 a are bonded so as not to be filled with the adhesive layer 15. This is because if the adhesive layer 15 enters the gaps between the lenses 14a, the refractive action of the lenses 14a becomes weak, and the viewing angle compensation effect by the lens array 14 becomes small.

  In FIG. 2, the cross section of the other example of the optical laminated body 20 of this invention is typically shown. A polarizing film 24 in which a thin polarizing film 23 is sandwiched between two substrates 21 and 22 and a lens array 25 are laminated and integrated through an adhesive layer 26. The thickness of the thin polarizing film 23 is 8 μm or less. At this time, the main surface of the lens array 25 on the lens 25a side is opposed to the polarizing film 24, and the adjacent lenses 25a are bonded so as not to be filled with the adhesive layer 26.

  In the polarizing film 24, one of the two base materials 21 and 22 and the thin polarizing film 23 may be stretched and bonded to the other after stretching. Alternatively, the thin polarizing film 23 may be stretched after being sandwiched (bonded) by the two base materials 21 and 22. Thus, by bonding the base materials 21 and 22 to the front and back of the thin polarizing film 23, for example, when only the polarizing film 24 is handled, the thin polarizing film 23 can be prevented from being damaged.

[Polarized film]
The polarizing film used in the liquid crystal display device of the present invention typically has little dimensional change even when placed at a high temperature (for example, 80 ° C.) for a long time (for example, 120 hours). The dimensional change rate is typically −0.2% or less (−0.2% to 0%).

  In FIG. 3, the example of the polarizing film used for the optical laminated body of this invention and a liquid crystal display device is shown and demonstrated with the conventional polarizing film.

  FIG. 3A shows a conventional polarizing film 30, in which a protective film 31 is bonded to the front and back of a polarizer 32. The protective film 31 is typically a 40 μm thick triacetyl cellulose (TAC) film. The polarizer 32 is typically a polyvinyl alcohol (PVA) film having a thickness of 30 μm.

  FIG. 3B is an example of the polarizing film 40 used in the present invention, and a thin polarizing film 42 is laminated on the surface of the substrate 41. The substrate 41 is typically a triacetyl cellulose (TAC) film, an amorphous PET film, a polymethylpentene (TPX) film, an acrylic resin film, a norbornene resin film, or the like having a thickness of 20 μm to 80 μm. The thin polarizing film 42 is typically a polyvinyl alcohol (PVA) film having a thickness of 8 μm or less.

  The polarizing film 40 used in the present invention shown in FIG. 3 (b) is coated with a polyvinyl alcohol aqueous solution on the surface of a base material 41 and dried to form a polyvinyl alcohol film, and then stretched together with the base material 41. The thin polarizing film 42 is formed by staining with iodine or the like. Since the polarizing film 40 used in the present invention is based on this manufacturing method, the thin polarizing film 42 is very thin compared to the conventional polarizing film 30. (The thickness of the conventional polarizer 32 is about 30 μm, and the thickness of the thin polarizing film 42 of the present invention is 8 μm or less).

  FIG. 3C shows another example of the polarizing film 50 used in the present invention. Both surfaces of the thin polarizing film 51 are sandwiched between the base materials 52 and 53. The base materials 52 and 53 are typically a triacetyl cellulose (TAC) film, an amorphous PET film, a polymethylpentene (TPX) film, an acrylic resin film, a norbornene resin film, and the like having a thickness of 20 μm to 80 μm. The thin polarizing film 51 is typically a polyvinyl alcohol (PVA) film having a thickness of 8 μm or less.

  A polarizing film 50 used in the present invention shown in FIG. 3C is formed by applying a polyvinyl alcohol aqueous solution to the surface of one base material 52 and drying it to form a polyvinyl alcohol film. The thin polarizing film 51 is formed by stretching together and dyeing with iodine or the like, and the other base material 53 is bonded to the thin polarizing film 51. Since the polarizing film 50 used in the present invention is based on this manufacturing method, the thin polarizing film 51 is very thin compared to the conventional polarizing film 30. (The thickness of the conventional polarizer 32 is about 30 μm, and the thickness of the thin polarizing film 51 of the present invention is 8 μm or less).

The reason why the polarizing films 40 and 50 used in the present invention have a small dimensional change at a high temperature is considered as follows.
(1) The thin polarizing films 42 and 51 are thin. The conventional polarizer 32 has a thickness of about 30 μm, but the thin polarizing films 42 and 51 used in the present invention have a thickness of 8 μm or less. In general, a thin film or film has less dimensional change than a thick film or film.
(2) The base materials 41, 52 and 53 are made of a material whose dimensional change due to high temperature is very small compared to the thin polarizing films 42 and 51. In the polarizing films 40 and 50 used in the present invention, when the contraction stress of the thin polarizing films 42 and 51 is generated, the base materials 41, 52, and 53 are thicker and more rigid than the thin polarizing films 42 and 51. The influence of the stress of the polarizing films 42 and 51 is small, and the polarizing films 40 and 50 are difficult to shrink.

  In the polarizing films 40 and 50 used in the present invention, an appropriate thickness of the thin polarizing films 42 and 51 is 8 μm or less, and an appropriate thickness of the base materials 41, 52 and 53 is 20 μm to 80 μm. If the thickness of the base materials 41, 52, and 53 is less than 20 μm, the rigidity of the base materials 41, 52, and 53 may be insufficient, and the polarizing films 40 and 50 may be easily contracted. When the thickness of the base materials 41, 52, 53 exceeds 80 μm, the polarizing films 40, 50 become too thick and poor in flexibility, and lack of practicality such as ease of sticking to the panel.

  On the other hand, in the conventional polarizing film 30, a material having a very small dimensional change due to high temperature as compared with the polarizer 32 is selected as the protective film 31. Typically, the dimensional change rate of the protective film 31 is about -0.03%.

  However, since the thicknesses of the polarizer 32 and the protective film 31 are approximately the same, when the contraction stress of the polarizer 32 is generated, the protection film 31 does not have sufficient rigidity to resist the contraction stress. Therefore, it is difficult to prevent the polarizing film 30 from shrinking. Actually, according to experiments by the inventors, the dimensional shrinkage rate of the polarizing film 30 tends to increase as the thickness of the protective film 31 decreases.

[Production method of polarizing film]
The polarizing films 40 and 50 used in the present invention are each composed of a laminate of base materials 41, 52 and 53 and thin polarizing films 42 and 51, and the manufacturing method thereof can be obtained by the steps described later.

  In the polarizing film 40 of the present invention, a thin film of a vinyl alcohol polymer is applied and formed on the surface of a base material 41, and after the thin film is stretched together with the base material 41, for example, iodine is dyed so that the thin film has a polarizing function. In addition, it is manufactured by forming a laminated body of the base material 41 and the thin polarizing film 42.

  In the polarizing film 50 of the present invention, a thin film of a vinyl alcohol polymer is applied and formed on the surface of a base material 52, and the thin film is stretched together with the base material 52. In addition, a laminated body of the base material 52 and the thin polarizing film 51 is manufactured, and further, the base material 53 is laminated on the thin polarizing film 51.

  The polarizing films 40 and 50 obtained as described above are hardly affected by temperature and humidity, and have very little dimensional change due to temperature and humidity. Usually, the dimensional change of the polarizing film is dominated by the polarizer that is most easily expanded and contracted. Therefore, the polarizing films 40 and 50 of the present invention including the thin polarizing films 42 and 51 with little dimensional change have a small dimensional change rate.

  Specifically, the dimensional change rate of the polarizing films 40 and 50 should be at least −0.2% or less (−0.2% to 0%) when stored in a constant temperature environment test chamber at 80 ° C. for 120 hours. Preferably, it can be made into -0.1% or less (-0.1%-0%).

The reason why the dimensional change rate of the polarizing films 40 and 50 is small has not been fully clarified, but in addition to the above (1) and (2), matters including the following (A) to (D) are complex. It is presumed that it is acting on.
(A) A thin film of vinyl alcohol polymer.
(A) A thin film of vinyl alcohol polymer is applied and formed, and this thin film is closely adhered to the base materials 41 and 52 without using an adhesive or the like.
(C) Rather than stretching only a vinyl alcohol polymer thin film, this thin film and the substrates 41 and 52 are stretched together.
(D) After the vinyl alcohol polymer thin film and the base materials 41 and 52 are stretched, iodine or the like is dyed.

  The polarizing film 40 includes a base material 41 and a thin polarizing film 42, and the thickness varies depending on the thickness of the base material 41 to be used, but is preferably about 20 μm to 90 μm.

  The polarizing film 50 includes base materials 52 and 53 and a thin polarizing film 51, and the thickness varies depending on the thickness of the base materials 52 and 53 to be used, but is preferably about 40 μm to 170 μm.

  The polarization degree of the thin polarizing films 42 and 51 is preferably 99% or more, and the transmittance is preferably 39% to 46%.

  The base materials 41 and 52 used in the above-described steps are excellent in smoothness capable of uniformly coating and forming a vinyl alcohol polymer thin film. And what was excellent in the drawability which can be extended | stretched in the state which laminated | stacked said thin film on the base materials 41 and 52 is used preferably.

  Examples of the material of the base materials 41 and 52 include olefin polymers, norbornene polymers, acrylic polymers, amorphous PET polymers, and blended polymers thereof. In order to improve the adhesion of the vinyl alcohol polymer thin film, an easy adhesion layer such as a urethane resin may be provided on the base materials 41 and 52.

  The thickness before stretching of the base materials 41 and 52 is preferably 50 μm to 200 μm, and the thickness after stretching is preferably 20 μm to 80 μm. In addition, when the base materials 41 and 52 have an easily bonding layer, the range of this thickness is thickness including an easily bonding layer.

  The vinyl alcohol polymer is typically polyvinyl alcohol or an ethylene vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponification hydrolysis of polyvinyl acetate, and ethylene vinyl alcohol copolymer is obtained by saponification hydrolysis of ethylene vinyl acetate copolymer.

  The vinyl alcohol-based polymer is dissolved in an appropriate solvent (for example, hot water) to form a solution, and is then formed into a thin film on the surfaces of the substrates 41 and 52 by an arbitrary coater. The thickness of the vinyl alcohol polymer thin film before stretching is preferably 1 μm to 20 μm.

  The laminate of the vinyl alcohol polymer thin film and the base materials 41 and 52 is stretched in the longitudinal, lateral, or oblique directions (air stretching) by an arbitrary stretching device (for example, a tenter stretching machine). In this way, by stretching the thin film together with the base materials 41 and 52, the thin film can be stretched uniformly without breaking. The draw ratio at this time is arbitrarily set according to the optical characteristics of the finally obtained thin polarizing films 42 and 51, but is preferably 3 to 6 times. The stretching temperature at this time is preferably 100 ° C to 180 ° C.

  Although the above-mentioned stretching is ordinary air stretching (stretching in the air), as a result of the study by the applicant, the polyvinyl alcohol resin is subjected to a total stretching ratio of 5 times in a boric acid aqueous solution at a low temperature (85 ° C. or lower). It has been found that a thin polarizing film with further excellent optical properties can be obtained by stretching the film as described above (stretching in boric acid in water).

  Boric acid generates a tetrahydroxyborate anion in an aqueous solution. This tetrahydroxyborate anion is presumed to hydrogen bond with the hydroxy group of the vinyl alcohol polymer to crosslink the vinyl alcohol polymer. By this crosslinking, the vinyl alcohol polymer is insolubilized and can be stretched in an aqueous solution.

  If the PVA-based resin is stretched in an aqueous boric acid solution, the PVA-based resin layer can be insolubilized, so that it can be stretched at a high magnification of 5 times or more in terms of the total stretch ratio.

  It is difficult to obtain a high-performance thin polarizing film by a conventional manufacturing method in which a thin PVA-based resin is stretched in the air integrally with a resin base material. The cause is due to the use of a drawing method called “air drawing”. Regardless of the temperature, in the case of stretching in the air, crystallization of the PVA resin proceeds by stretching, and it is difficult to make the total stretching ratio including the resin base material to be stretched 5 times or more of the original length. In addition, a high-order structure (large structure) that does not contribute to orientation, such as a lamellar structure or spherulite, is formed in the PVA-based resin, so that the dichroic substance can be sufficiently adsorbed and oriented in a higher order. Inferred to be impossible.

  By stretching the polyvinyl alcohol resin in boric acid in water at a low temperature, the thin PVA resin can be stretched at a high magnification of 5 times or more while preventing crystallization of the polyvinyl alcohol polymer. As a result, an inference is made that the orientation of the amorphous portion of the thin PVA-based resin is increased. Moreover, by extending | stretching at high magnification, dichroic substances, such as a polyiodine ion complex which exists in PVA-type resin, will be located in a high order in one direction. As a result, a thin polarizing film having high optical characteristics can be obtained.

  The stretched laminate of the base materials 41 and 52 and the thin film is immersed and dyed in a dye bath containing a dichroic substance (for example, iodine or organic dye). Under the present circumstances, if the hydrophobic resin (for example, norbornene-type polymer) which does not have a hydroxyl group is used as a material of the base materials 41 and 52, the base materials 41 and 52 will not be dye | stained. The temperature of the dyeing bath is preferably 10 ° C to 50 ° C. The total time for immersing the stretched laminate in the dyeing bath is preferably 5 seconds to 240 seconds.

  Further, as shown in FIGS. 3D to 3E, the thin polarizing film 42 is transferred to another base material 43 via an adhesive (not shown) to produce the polarizing film 44. be able to. The substrate 43 after transfer can also be used as a protective film, for example. The base material 43 is produced by a casting method or an extrusion method, and the material and thickness can be appropriately selected. Furthermore, as shown in FIG. 3F, a polarizing film 46 in which both sides of the thin polarizing film 42 are protected by laminating a protective film 45 on the thin polarizing film 42 can also be produced.

  A conventionally used base material is a triacetyl cellulose (TAC) film having a thickness of 40 μm and 80 μm. Considering handling, etc., it can be used as a protective film up to a thickness of about 20 μm. Therefore, it can be said that the thickness of the base material 43 used as a protective film after transfer is preferably 20 μm to 80 μm.

  According to the estimation of the present inventors, after stretching a thin film of a vinyl alcohol polymer, the thin film is immersed in a dyeing bath to swell the thin film, reducing the internal stress and reducing the dimensional change rate of the thin polarizing films 42 and 51. Has the effect of reducing the size.

[Lens Array]
FIG. 4A shows an example of a lens array 60 used in the liquid crystal display device of the present invention. On one surface of the transparent substrate 61, a large number of lenticular lenses 62 are periodically arranged at a pitch P _L. Pitch _{P L} is typically of the order of 0.1mm. The direction perpendicular to the optical axis of the lenticular lens 62 is the arrangement direction of the lenticular lenses 62. In addition, the lens to be arranged may be a fly-eye lens 63 shown in FIG. 4B, a linear Fresnel lens, a microprism, a cylindrical lens, a microlens array, or the like.

  Since the optical laminate 10 including the polarizing film 13 and the lens array 14 shown in FIG. 1 has a contraction rate of the polarizing film 13 much smaller than that of the conventional polarizing film, the distortion of the lens array 14 can be suppressed. Therefore, incident light that enters a color filter (not shown) is not shifted, and the occurrence of color unevenness is suppressed.

[Liquid Crystal Display]
FIG. 5A schematically shows an example of the liquid crystal display device 70 of the present invention. The liquid crystal display device 70 includes a liquid crystal panel 71, the optical laminate 10 of the present invention, a polarizing film 72, and a surface light source (backlight) 73.

  The liquid crystal panel 71 includes a liquid crystal layer 71b sandwiched between a pair of substrates 71a. The optical laminate 10 of the present invention is attached to the surface light source 73 side of the liquid crystal panel 71. A polarizing film 72 is attached to the side of the liquid crystal panel 71 opposite to the optical laminate 10.

  FIG. 5B schematically shows another example of the liquid crystal display device 80 of the present invention. The liquid crystal display device 80 includes a liquid crystal panel 81, the optical laminate 10 of the present invention, a polarizing film 82, and a surface light source (backlight) 83. The liquid crystal panel 81 includes a liquid crystal layer 81b sandwiched between a pair of substrates 81a. The difference from the liquid crystal display device 70 of the present invention in FIG. 5A is that the surface light source 83 is on the opposite side of the optical laminate 10 with respect to the liquid crystal panel 81.

  FIG. 6A schematically shows another example of the liquid crystal display device 90 of the present invention. The liquid crystal display device 90 includes a liquid crystal panel 91, the optical laminate 20 of the present invention, a polarizing film 92, and a surface light source (backlight) 93.

  The liquid crystal panel 91 includes a liquid crystal layer 91b sandwiched between a pair of substrates 91a. The optical laminate 20 of the present invention is attached to the surface light source 93 side of the liquid crystal panel 91. A polarizing film 92 is attached to the side of the liquid crystal panel 91 opposite to the optical laminate 20.

  FIG. 6B schematically shows another example of the liquid crystal display device 100 of the present invention. The liquid crystal display device 100 includes a liquid crystal panel 101, the optical laminate 20 of the present invention, a polarizing film 102, and a surface light source (backlight) 103. The liquid crystal panel 101 includes a liquid crystal layer 101b sandwiched between a pair of substrates 101a. The difference from the liquid crystal display device 100 of the present invention in FIG. 6A is that the surface light source 103 is on the opposite side of the optical laminate 20 with respect to the liquid crystal panel 101.

  The present invention can also be applied to a stereoscopic display device using a liquid crystal panel. As an applicable stereoscopic display device, for example, a lenticular type liquid crystal display device 110 shown in FIG. 7 can be cited (Patent Document 2). In general, in order to emit the right circularly polarized light corresponding to the right eye pixel group 111 and the left circularly polarized light corresponding to the left eye pixel group 112 of the liquid crystal cell, the pattern phase difference plate 114 and the lens array are directly above the polarizing film 113. 115 are sequentially stacked, and the pattern retardation plate 114 has a plurality of slow axis patterns corresponding to the cylindrical lenses (lens array 115).

  Various methods for forming the pattern retardation plate 114 are disclosed. For example, a half-wave plate is alternately patterned in a direction parallel to the scanning line using a photolithography process, and a portion having a half-wave phase difference and a portion having no phase difference are formed on the substrate. To form. On top of these, a quarter-wave retardation plate having a slow axis perpendicular to the slow axis of the portion having a half-wave phase difference is laminated on the entire surface of the substrate. Thus, there is a method of forming a stripe-shaped pattern quarter-wave plate having slow axes orthogonal to each other.

  As another method, a rubbing alignment film such as polyimide or polyvinyl alcohol is formed on the substrate. In order to obtain a slow axis alternately in a direction parallel to the scanning line, a mask pattern is produced and the rubbing direction is controlled in a stripe shape. On top of that, there is a method in which a liquid crystal material is aligned to form a striped quarter-wave plate whose slow axes are orthogonal to each other.

  As another method, a photo-alignment film is formed on the substrate, and a mask pattern is produced in order to obtain a slow axis alternately in a direction parallel to the scanning line. When the polarized UV irradiation is performed, the stripe shape is controlled, and the liquid crystal material is aligned thereon. In this way, there is a method of forming a striped quarter-wave plate whose slow axes are orthogonal to each other.

  FIG. 8 is a schematic diagram of an example of the liquid crystal display device 120 of the present invention. The liquid crystal display device 120 is capable of stereoscopic display. The liquid crystal display device 120 includes a liquid crystal panel 121, an optical laminate 122 of the present invention, a lens array 123, a polarizing film 124, and a surface light source (backlight) 125.

  The liquid crystal panel 121 includes a liquid crystal layer 121b sandwiched between a pair of substrates 121a. In the liquid crystal cell in the liquid crystal layer 121b, right-eye pixel groups 121c and left-eye pixel groups 121d are alternately arranged.

  The optical laminate 122 of the present invention is obtained by laminating a polarizing film 122c in which a thin polarizing film 122b is laminated on one main surface of a base material 122a and a pattern retardation plate 122d.

  The pitch of the right-eye pixel group 121c and the left-eye pixel group 121d of the liquid crystal cell, the pitch of the pattern phase difference plate 122d, and the pitch of the lens array 123 are the same.

  Although the lens array 123 is disposed on the pattern retardation plate 122d, it may be fixed by a bezel without being adhered to the pattern retardation plate 122d. Alternatively, the lens array 123 may be bonded to the pattern retardation plate 122d with an adhesive or the like.

  When a conventional polarizing film is fixed by a bezel, the dimensions of the polarizing film are likely to change due to changes in temperature and humidity due to heat generated when the surface light source is turned on and the external environment. For this reason, the positions of the pattern phase difference plate and the liquid crystal cell are easily misaligned, and stereoscopic display blur is likely to occur.

  When the conventional polarizing film is bonded to the lens array, the dimensional change of the polarizing film is apparently reduced, but the lens array is distorted due to the contraction stress of the polarizing film, so that stereoscopic display blur is likely to occur.

  When the optical layered body 122 provided with the polarizing film 122c of the present invention is used, even if there is a change in temperature or humidity due to heat when the surface light source 125 is turned on or due to an external environment, the positional shift of the pattern phase difference plate 122d or lens The distortion of the array 123 does not occur. Since the right-eye pixel group 121c and the left-eye pixel group 121d, the pattern phase difference plate 122d, and the lens array 123 are not misaligned, stereoscopic display blur can be suppressed.

When a conventional polarizing film is used for such a liquid crystal display device, moire fringes are unlikely to occur at the beginning of manufacture. However, when the dimensional change of the polarizing film is affected under a high temperature environment such as in a vehicle, the optical element is distorted. If the optical element is a lens array, or shift pitch P _L and the arrangement direction of the lens array, polarizing film is peeled off the lens array. Further, when the optical element is a pattern phase difference plate, a positional deviation occurs between the pattern phase difference plate and the pixel group. As a result, moire fringes, color unevenness, and stereoscopic display blur may occur. However, when the optical laminates 10, 20, and 122 of the present invention are used, the optical element and other optical members can be prevented from being misaligned without causing distortion or peeling in the optical element even in a high temperature environment. Generation of moire fringes, color unevenness, and stereoscopic display blur in the display device is suppressed.

  In Examples 1-14, the liquid crystal display device provided with the optical laminated body of this invention using the film produced by apply | coating polyvinyl alcohol to a base material, extending | stretching and dye | staining was produced.

  In the polarizing film, the thickness of the polyvinyl alcohol coating film was set to 4 levels (3.2 μm, 4.3 μm, 10.0 μm, 18.0 μm). The thickness of the thin polarizing film after stretching and dyeing was set to 4 levels (1.3 μm, 1.7 μm, 4.0 μm, 7.2 μm).

  The type and thickness of the substrate were selected as shown in Table 1 and manufactured.

  Comparative Examples 1-8 are polarizing films obtained by a production method based on a conventional polarizer stretching method.

[Example 1]
A polyvinyl alcohol resin (JC-40 manufactured by Nippon Vinegar Pover Co., Ltd.) was dissolved in hot water and then cooled to prepare a 7% by weight polyvinyl alcohol aqueous solution.

  The surface of a norbornene-based resin film (manufactured by JSR, Arton) is subjected to corona treatment for easy adhesion, and then coated with an aqueous polyvinyl alcohol solution, dried at 100 ° C. for 10 minutes, and coated with a 3.2 μm thick polyvinyl alcohol. A membrane was obtained. Thereby, the laminated body which laminated | stacked the polyvinyl alcohol coating film and the norbornene-type resin film was obtained.

  The obtained laminate is stretched 4.5 times longitudinally by roll-to-roll at 140 ° C. by free-end longitudinal stretching (stretching in the longitudinal direction without holding the widthwise end of the laminate). A laminated body was obtained. The stretched laminate had a film width of 360 mm, a substrate thickness of 40 μm, and a polyvinyl alcohol coating film thickness of 1.3 μm.

  Next, the stretched laminate was immersed in an aqueous iodine solution at 20 ° C. (iodine: potassium iodide: water = 1: 10: 200) for 60 seconds, then immersed in an aqueous 10 wt% boric acid solution at 55 ° C. for 420 seconds, and further 30 After being immersed in a 4 wt% potassium iodide aqueous solution at 10 ° C. for 10 seconds, drying was performed at 60 ° C. for 4 minutes to obtain a polarizing film. The thickness of the thin polarizing film which consists of a polyvinyl alcohol coating film of the completed polarizing film was 1.3 micrometers.

  The optical properties of the obtained polarizing film were measured with a spectrophotometer with an integrating sphere (U-4100 manufactured by Hitachi, Ltd.) in a configuration in which light from the prismatic thin polarizing film was incident on the polyvinyl alcohol coating film surface. The transmittance was 41.5% and the degree of polarization was 99.8%.

The transmittance for each linearly polarized light was measured with 100% of the completely polarized light obtained through the Gran Taylor prism thin polarizing film. The transmittance is indicated by the Y value corrected for the visibility calculated based on the CIE 1931 color system. The degree of polarization P is
P = {(k ₁ −k ₂ ) / (k ₁ + k ₂ )} × 100
Calculated with Here, k ₁ and k ₂ represent the transmittance of linearly polarized light in the maximum transmittance direction and the transmittance of linearly polarized light in the orthogonal direction.

The lens array uses a norbornene-based resin film (Artron thickness 150 μm, width 750 mm, manufactured by JSR) as a transparent substrate, and an ultraviolet curable resin (Z9001, manufactured by JSR) filled and cured in a mold having a predetermined concave portion. It was formed by transferring to Lens pitch _{P L} is 0.1 mm, the height of the lens was 0.04 mm.

  As shown in FIG. 6B, a liquid crystal display device for observing moire fringes and color unevenness by laminating the optical laminate of the present invention comprising a lens array and a polarizing film to a liquid crystal panel with an acrylic adhesive. Was made.

  Further, as shown in FIG. 8, the optical layered body of the present invention composed of a pattern retardation plate and a polarizing film is bonded with an acrylic adhesive so as to be interposed between a lens array and a liquid crystal panel, A liquid crystal display device for observing display blur was manufactured. The liquid crystal panel includes a liquid crystal cell including a right-eye pixel group and a left-eye pixel group.

  The liquid crystal display device of Example 1 was subjected to an environmental test at 80 ° C. for 24 hours and examined for display deterioration after the test. As a result, no color unevenness, moire fringes, and three-dimensional display blur occurred, and there was no display deterioration.

  When the polarizing film used in Example 1 was subjected to an environmental test at 80 ° C. for 120 hours using the polarizing film alone, as shown in Table 1, the dimensional change rate was -0.022% in MD (longitudinal direction), TD (width direction) was -0.049%.

[Examples 2 to 6]
The coating amount of the polyvinyl alcohol aqueous solution was adjusted, and the thickness of the thin polarizing film composed of the polyvinyl alcohol coating film and the thickness of the substrate were adjusted as shown in Table 1. Other than that was carried out similarly to Example 1, and produced the polarizing film and the liquid crystal display device.

  As in Example 1, the liquid crystal display device was subjected to an environmental test at 80 ° C. for 24 hours. After the test, there was no occurrence of color unevenness, moire fringes and stereoscopic display blur, and there was no display deterioration. Table 1 shows the dimensional change rate of the polarizing film alone in the environmental test at 80 ° C. for 120 hours.

[Examples 7 to 14]
The coating amount of the polyvinyl alcohol aqueous solution was adjusted, and the thickness of the thin polarizing film composed of the polyvinyl alcohol coating film and the thickness of the substrate were adjusted as shown in Table 1. As shown in FIG. 3C, both surfaces of the thin polarizing film were laminated with a base material to produce a polarizing film. The rest is the same as in the first embodiment.

  As shown in FIG. 6B, the lens array and the polarizing film were bonded to a liquid crystal panel with an acrylic adhesive to produce a liquid crystal display device for observing moire fringes and color unevenness.

  Further, as shown in FIG. 8, the optical laminate of the present invention composed of a pattern phase difference plate and a polarizing film is bonded with an acrylic adhesive so as to be interposed between the lens array and the liquid crystal panel, and is displayed in three dimensions. A liquid crystal display device for observing blur was manufactured. The liquid crystal panel includes a liquid crystal cell including a right-eye pixel group and a left-eye pixel group. (The point that a polarizing film is a double-sided base material is different from FIG. 8.) In Examples 10 and 11, the base material was an acrylic resin film (AC).

  As in Example 1, the liquid crystal display device was subjected to an environmental test at 80 ° C. for 24 hours. After the test, there was no occurrence of color unevenness, moire fringes and stereoscopic display blur, and there was no display deterioration. Table 1 shows the dimensional change rate of the polarizing film alone in the environmental test at 80 ° C. for 120 hours.

[Comparative Example 1]
A lens film and a conventional polarizing film (NPF manufactured by Nitto Denko Corporation) with a protective film (thickness 40 μm) on one side are bonded to a liquid crystal panel with an acrylic adhesive to observe moire fringes and color unevenness. A liquid crystal display device was manufactured. The protective film is a triacetyl cellulose resin film (TAC).

  Furthermore, an optical laminate comprising a pattern phase difference plate and a polarizing film having a conventional polarizing film (NPF manufactured by Nitto Denko Corporation) with a protective film (thickness: 40 μm) on one side is bonded to a lens array and a liquid crystal with an acrylic adhesive. A liquid crystal display device for observing stereoscopic display blur was produced by bonding the panels so as to be interposed between the panels. The liquid crystal panel includes a liquid crystal cell including a right-eye pixel group and a left-eye pixel group.

  The liquid crystal display device of Comparative Example 1 was subjected to an environmental test at 80 ° C. for 24 hours. After the test, color unevenness, moire fringes and stereoscopic display blur occurred, and display characteristics were deteriorated. When the polarizing film used in Comparative Example 1 alone was subjected to an environmental test at 80 ° C. for 120 hours, as shown in Table 1, MD (longitudinal direction) was −0.730%, TD ( Width direction) was −0.406%.

[Comparative Example 2]
A liquid crystal display device was produced in the same manner as in Comparative Example 1 except that the protective film had a thickness of 80 μm. The liquid crystal display device of Comparative Example 2 was subjected to an environmental test at 80 ° C. for 24 hours in the same manner as Comparative Example 1. After the test, color unevenness, moire fringes and stereoscopic display blur occurred, and display characteristics were deteriorated. Table 1 shows the results of an environmental test of the polarizing film alone at 80 ° C. for 120 hours.

[Comparative Examples 3 to 8]
As shown in FIG. 3A, a liquid crystal display device was produced in the same manner as in Comparative Example 1 except that a protective film was laminated on both sides of the polarizer and the thickness of the protective film was as shown in Table 1. In Comparative Example 6, an acrylic resin film (AC) was used as the protective film.

  The liquid crystal display device of each comparative example was subjected to an environmental test at 80 ° C. for 24 hours in the same manner as the liquid crystal display device of comparative example 1. After the test, color unevenness, moire fringes and stereoscopic display blur occurred, and display characteristics were deteriorated. Table 1 shows the results of an environmental test of the polarizing film alone at 80 ° C. for 120 hours.

[Evaluation method]
[Dimensional change rate of polarizing film]
An acrylic pressure-sensitive adhesive having a thickness of 20 μm was formed on the produced polarizing film. The obtained polarizing film with pressure-sensitive adhesive is cut into a size of 100 mm × 100 mm so that the stretching direction is 0 °, and bonded to a glass plate with a thickness of 1 mm to obtain a measurement sample, and marks are formed at the four corners of the polarizing film. Wearing.

The Mitutoyo machine vision (Quick Vision) and measuring the length L ₀ between marks at the four corners of the polarizing film.

After the measured sample was put in a heating oven at 80 ° C. for 120 hours, the length L ₁₂₀ between the marks at the four corners of the polarizing film was measured again.

The dimensional change rate was calculated by the following equation.
Dimensional change rate (%) = {(L ₁₂₀ −L ₀ ) / L ₀ } × 100

[Moire stripes and color unevenness]
A liquid crystal display device for observing moire fringes and color unevenness was prepared and exposed to a heating environment (80 ° C., 24 hours), and then moire fringes and color unevenness were visually observed.

[3D blurring]
A liquid crystal display device for observing stereoscopic display blur was prepared, and after exposure to a heated environment (80 ° C., 24 hours), the stereoscopic display blur was visually observed.

  The optical layered body formed by laminating the polarizing film and the optical element according to the present invention has, for example, an extremely small dimensional change rate due to a temperature change and suppresses distortion of the lens array. The traveling direction can be appropriately controlled.

  In addition, the liquid crystal display device of the present invention provided with this optical laminate can appropriately control the traveling direction of light emitted from the optical laminate even when left in a high temperature state for a long time. Unevenness and stereoscopic display blur are unlikely to occur, and high-quality display can be achieved.

  For this reason, the liquid crystal display device of the present invention is particularly suitable for use in an environment with severe temperature conditions such as in-vehicle, FA (Factory Automation), and the outdoors.

DESCRIPTION OF SYMBOLS 10 Optical laminated body 11 Base material 12 Thin polarizing film 13 Polarizing film 14 Lens array 14a Lens 15 Adhesive layer 20 Optical laminated body 21 Base material 22 Base material 23 Thin polarizing film 24 Polarizing film 25 Lens array 25a Lens 26 Adhesive layer 30 Polarizing film DESCRIPTION OF SYMBOLS 31 Protective film 32 Polarizer 40 Polarizing film 41 Base material 42 Thin polarizing film 43 Base material 44 Polarizing film 45 Protective film 46 Polarizing film 50 Polarizing film 51 Thin polarizing film 52 Base material 53 Base material 60 Lens array 61 Transparent substrate 62 Lenticular lens 63 Fly-eye lens 70 Liquid crystal display device 71 Liquid crystal panel 71a Substrate 71b Liquid crystal layer 72 Polarizing film 73 Surface light source 80 Liquid crystal display device 81 Liquid crystal panel 81a Substrate 81b Liquid crystal layer 82 Polarizing film 83 Surface light source 90 Liquid crystal display device 91 Liquid crystal panel 91a Plate 91b Liquid crystal layer 92 Polarizing film 93 Surface light source 100 Liquid crystal display device 101 Liquid crystal panel 101a Substrate 101b Liquid crystal layer 102 Polarizing film 103 Surface light source 110 Liquid crystal display device 111 Right-eye pixel group 112 Left-eye pixel group 113 Polarizing film 114 Pattern retardation plate 115 lens array 120 liquid crystal display device 121 liquid crystal panel 121a substrate 121b liquid crystal layer 121c pixel group for right eye 121d pixel group for left eye 122 optical laminate 122a base material 122b thin polarizing film 122c polarizing film 122d pattern retardation plate 123 lens array 124 polarizing film 125 surface light source

Claims (5)

An optical element comprising a lens array having a plurality of lenses for controlling the traveling direction of light;
Having a polarizing film in which a thin polarizing film is laminated on one main surface of a substrate;
The thin polarizing film is made of a polyvinyl alcohol-based resin that is stretched at the free end along with the base material and dyed with iodine.
The optical element and the polarizing film are laminated,
The thin polarizing film has a thickness of 8 μm or less,
The polarizing film is an optical laminate in which the dimensional change rate in the MD (longitudinal) direction and the TD (width) direction are both −0.2% or less.   The optical laminate according to claim 1, wherein the base material stretched together with the polyvinyl alcohol-based resin has a thickness of 20 µm to 80 µm.   A polarizing film formed by transferring and laminating a thin polarizing film having a thickness of 8 μm or less, which is made of a polyvinyl alcohol resin stretched together with a base material and dyed with iodine, and a plurality of layers for controlling the traveling direction of light An optical laminate formed by laminating an optical element comprising a lens array having a lens.   The optical layered body according to claim 3 whose thickness of said another substrate is 20 micrometers-80 micrometers.   A liquid crystal display device comprising a liquid crystal panel and the optical laminate according to claim 1.

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