JP6065144B1 - Light control film - Google Patents

Abstract

In a light control film by a VA method, a product having a large area can be efficiently produced by improving the viewing angle characteristics and the light shielding ratio during black display. A first linearly polarizing plate, a liquid crystal cell, a retardation film, and a second linearly polarizing plate are provided in order, and the liquid crystal cell is connected to the liquid crystal cell from the side of the first linearly polarizing plate. The first transparent body 16 formed by laminating the first transparent electrode 16 and the first alignment layer 17 on the first base material 15, the liquid crystal layer 8, and the second transparent material on the second base material 10. A second stacked body 5 formed by stacking the electrode 11 and the second alignment layer 12 is provided. The amount of transmitted light is controlled by varying the orientation of the liquid crystal layer 8 by driving with the transparent electrodes 16 and 11 provided in the first and second laminates 6 and 5. The slow axes of the base materials 15 and 10 of the first and second laminates 6 and 5, the slow axis of the retardation film 2 </ b> A, and the absorption axis of the first linear polarizing plate 3 are parallel, and the linear polarizing plate 3. The two absorption axes were arranged so as to be orthogonal. [Selection] Figure 1

Description

  The present invention relates to a light control film that is attached to a window or the like of a passenger car to control the transmission of extraneous light.

  Conventionally, for example, various devices relating to a light control film that is attached to a window to control the transmission of external light have been proposed (Patent Documents 1 and 2). One such light control film uses liquid crystal. The light control film using the liquid crystal is produced by sandwiching a liquid crystal material with a transparent film material on which a transparent electrode is produced, and producing the liquid crystal cell with a linear polarizing plate. As a result, in this light control film, the orientation of the liquid crystal is changed by changing the electric field applied to the liquid crystal, thereby blocking or transmitting the extraneous light, and further changing the amount of transmitted light. To control.

  Various driving methods proposed for liquid crystal display panels can be applied to driving the liquid crystal cell in such a light control film. Specifically, for example, a driving method such as a TN (Twisted Nematic) method, an IPS (In-Place-Switching) method, or a VA (Virtual Alignment) method can be applied. Here, the VA method is a method of controlling the transmitted light by changing the alignment of the liquid crystal between vertical alignment and horizontal alignment. Generally, the liquid crystal layer is vertically aligned by vertically aligning the liquid crystal when no electric field is applied. A liquid crystal cell is formed by being sandwiched between layers, and the liquid crystal material is horizontally aligned by application of an electric field.

  Here, in the light control film, for example, by sticking to a window glass or the like to shield outside light, the transmittance at the time of shielding is sufficiently reduced to shield the extraneous light (hereinafter referred to as a light shielding rate). From the viewpoint of sufficiently ensuring, driving by the VA method can be considered. In addition, as a result, the light control film is required to efficiently mass-produce a large area product.

  However, it has been found that when the light control film is formed by the VA method, the viewing angle characteristic is deteriorated and the light shielding rate is deteriorated when displaying black, which is light shielding, unlike the liquid crystal display panel.

JP 03-47392 A Japanese Patent Laid-Open No. 08-184273

  The present invention has been made in view of such circumstances, and in a VA-type light control film, a large-area product can be efficiently produced by improving the viewing angle characteristics and the light-shielding rate during black display. The purpose is to do so.

  The present inventor has intensively studied to solve the above-mentioned problems, and the base material made of the transparent film material for the liquid crystal cell has a slow phase of the base material under the condition that the slow axis is held in parallel. The idea of selecting the direction of the linearly polarizing plate with respect to the axis, etc. was reached, and the present invention was completed.

  Specifically, the present invention provides the following.

(1) A first linear polarizing plate, a liquid crystal cell, a retardation film functioning as an A plate, and a second linear polarizing plate are sequentially provided.
From the side of the first linear polarizing plate to the liquid crystal cell,
The 1st laminated body formed by laminating | stacking a 1st transparent electrode and a 1st orientation layer on a 1st base material, a liquid crystal layer, a 2nd transparent electrode and a 2nd orientation layer on a 2nd base material Are sequentially provided.
The amount of transmitted light is controlled by changing the orientation of the liquid crystal layer by the VA method by driving with the first and second transparent electrodes,
The slow axes of the first and second substrates, the slow axis of the retardation film, and the absorption axis of the first linear polarizing plate are parallel,
The light control film arrange | positioned so that the absorption axis of the said 1st and 2nd linear polarizing plate may orthogonally cross.

  According to (1), since the slow axis of the base material of the said 1st and 2nd laminated body is parallel, a large area product can be produced efficiently. Furthermore, the slow axis of the retardation film and the absorption axis of the first linear polarizing plate are parallel to the slow axis of the base material of the first and second laminates, and the first and second By arrange | positioning so that the absorption axis of a linearly-polarizing plate may orthogonally cross, in the light control film by a VA system, the influence on the transmitted light by the optical anisotropy of a base material can be reduced. As a result, it is possible to prevent the transmitted light from being polarized by the base material, and as a result, it is possible to improve the viewing angle characteristics and the light shielding rate during black display.

(2) In (1),
A retardation film functioning as a C plate is provided between the first linear polarizing plate and the first base material and / or between the second linear polarizing plate and the retardation film. Light control film.

  According to (2), the viewing angle characteristics can be further improved, and the light shielding rate can be further improved.

  According to the present invention, in a VA type light control film, a large-area product can be efficiently produced so as to improve the viewing angle characteristics and the light shielding rate during black display.

It is a figure which shows the light control film which concerns on 1st Embodiment of this invention. It is a figure where it uses for description of the light control film of FIG. It is a figure where it uses for description of a comparative example. It is a figure where it uses for description of the characteristic of the light control film of FIG. It is a flowchart which shows the manufacturing process of the light control film of FIG. It is a figure which shows the light control film which concerns on 2nd Embodiment of this invention. It is a figure which shows the light control film which concerns on 3rd Embodiment of this invention.

[First Embodiment]
[Light control film]
FIG. 1 is a cross-sectional view showing a light control film according to an embodiment of the present invention. This light control film 1 is used by being attached to an area for light control such as a window glass of a building, a showcase, an indoor transparent partition, etc. by using an adhesive layer or the like. Control and further block out extraneous light.

  The light control film 1 is a film material that controls transmitted light using liquid crystal, and is configured by sandwiching a liquid crystal cell 4 for light control film between linear polarizing plates 2 and 3. Here, the linear polarizing plates 2 and 3 are formed by impregnating polyvinyl alcohol (PVA) with iodine or the like, and then stretched to form an optical functional layer that performs an optical function as a linear polarizing plate. TAC (triacetyl cellulose) The optical functional layer is sandwiched between base materials made of a transparent film material such as the above. The linearly polarizing plates 2 and 3 are arranged in the liquid crystal cell 4 by an adhesive layer made of an ultraviolet curable resin or the like in a crossed Nicol arrangement. As the linear polarizing plates 2 and 3, a so-called coating type linear polarizing plate may be applied.

  The light control film 1 is provided with a retardation film 2 </ b> A for optical compensation between the linearly polarizing plate 2 and the liquid crystal cell 4. Here, as the retardation film 2A, an optical film having an A plate component is applied, and thereby various configurations that function as an A plate can be widely applied. In this embodiment, however, the retardation film 2A is made of a COP film material or the like. A biaxially stretched transparent film material is applied. For the A plate, in addition to such a biaxially stretched transparent film material, a cured product of polymerizable liquid crystal whose major axis direction is aligned in the in-plane direction can be applied. The light control film 1 improves a viewing angle characteristic and a light shielding rate by the retardation film 2A. Here, the in-plane main refractive index is nx (slow axis direction), ny is (fast axis direction), and the refractive index in the thickness direction is nz. The A plate is a positive uniaxial retardation optical element whose refractive index distribution satisfies nx> ny = nz or nx = nz> ny.

  The liquid crystal cell 4 controls the polarization plane of transmitted light by an applied voltage to a transparent electrode described later. Thereby, the light control film 1 is comprised so that a transmitted light can be controlled and various light control can be aimed at, and also external light can be shielded.

[Liquid crystal cell]
The liquid crystal cell 4 is configured by sandwiching a liquid crystal layer 8 between a lower laminated body 5 and an upper laminated body 6 which are first and second laminated bodies having a film shape. The lower laminate 5 is formed by producing a transparent electrode 11, an alignment layer 12, and a spacer 13 on a base material 10 made of a transparent film material. The upper laminate 6 is formed by laminating a transparent electrode 16 and an alignment layer 17 on a base material 15 made of a transparent film material. The liquid crystal cell 4 controls the orientation of the liquid crystal material provided in the liquid crystal layer 8 by the VA method by driving the transparent electrodes 11 and 16 provided in the lower laminate 5 and the upper laminate 6, thereby transmitting the liquid crystal cell 4. Controls the plane of polarization of light.

  Although various transparent film materials applicable to this kind of film material can be applied to the base materials 10 and 15, it is desirable to apply a film material having a small optical anisotropy. In this embodiment, the base materials 10 and 15 are made of the same material and transparent film material having the same thickness, and more specifically, a polycarbonate film is applied, but a COP (cycloolefin polymer) film or the like is applied. May be.

  Various electrode materials applied to this kind of film material can be applied to the transparent electrodes 11 and 16, and in this embodiment, the transparent electrodes 11 and 16 are formed of a transparent electrode material made of ITO (Indium Tin Oxide).

  The alignment layers 12 and 17 are formed of a photo-alignment layer. Here, as the photo-alignment material applicable to the photo-alignment layer, various materials to which the photo-alignment technique can be applied can be widely applied. However, in this embodiment, for example, a light dimerization type material is used. . The light dimerization type material is described in “M. Schadt, K. Schmitt, V. Kozinkov and V. Chigrinov: Jpn. J. Appl. Phys., 31, 2155 (1992)”, “M. Schadt, H. Seiberle and A. Schuster: Nature, 381, 212 (1996). The alignment layers 12 and 17 may be formed by preparing a resin layer such as polyimide instead of the photo-alignment layer and rubbing the resin layer. Further, the alignment layer may be produced by performing a shape-processing on the line-shaped fine irregularities by rubbing. The alignment layers 12 and 17 are set so that the direction in which the alignment regulating force is expressed is the same over the entire surface, whereby the light control film 1 drives the liquid crystal layer 8 by a single domain.

  The spacer 13 is provided to define the thickness of the liquid crystal layer 8 and various resin materials can be widely applied. However, in this embodiment, the spacer 13 is made of a photoresist, and the alignment layer 12 is produced. 10 is applied by applying a photoresist, exposing, and developing. The spacer 13 may be provided on the upper laminate 6 or may be provided on both the upper laminate 6 and the lower laminate 5. The spacer 13 may be provided on the transparent electrode 11. The spacer 13 may be a so-called bead spacer.

  Various liquid crystal materials applicable to this type of light control film can be widely applied to the liquid crystal layer 8. In the liquid crystal cell 4, a sealing material is disposed so as to surround the liquid crystal layer 8, and the lower stacked body 5 and the upper stacked body 6 are integrally held by the sealing material, and leakage of the liquid crystal material is prevented.

  FIG. 2 is a diagram for explaining the arrangement of the linearly polarizing plates 2 and 3, the retardation film 2 </ b> A, and the base materials 10 and 15. In FIG. 2, the absorption axis direction of the linearly polarizing plates 2 and 3 is indicated by arrows. Similarly, the slow axis directions of the base materials 10 and 15 are indicated by arrows.

  In the light control film 1, the base materials 10 and 15 of the lower laminate 5 and the upper laminate 6 are arranged so that the slow axes are parallel. More specifically, the direction extending in parallel with the long side or the short side of the rectangular shape related to the outer shape of the light control film 1 is the direction of the slow axis of the substrate 10 of the lower laminate 5. Further, they are arranged so as to be in the direction of the slow axis of the base material 15 of the upper laminate 6. Thereby, in this light control film 1, in the case where the lower laminated body 5 and the upper laminated body 6 were produced using the base materials 10 and 15 by a long film shape, the longitudinal direction in a long film shape corresponds. In this way, the lower laminate 5 and the upper laminate 6 are laminated so that the liquid crystal cell 4 can be produced, whereby a large-area light control film can be mass-produced efficiently.

  Here, in the light control film 1, by controlling the amount of light transmitted through the linearly polarizing plate by changing the phase difference in the transmitted light of the liquid crystal layer 8 by an electric field, the lower laminated layer related to the sandwiching of the liquid crystal layer 8 is controlled. A transparent film material with small optical anisotropy is applied to the base materials 10 and 15 related to the body 5 and the upper laminate 6. However, even a transparent film material with small optical anisotropy cannot ensure isotropy like a glass substrate, and the longitudinal direction generally becomes the slow axis direction due to stretching in the production process. As described above, optical anisotropy occurs. Thereby, when arrange | positioning so that a slow axis may become parallel with the base materials 10 and 15 like this embodiment, it pulls out the base materials 10 and 15 from a roll, and transparent electrodes 11 and 16 and alignment layer 12 and 17 are sequentially produced to produce the lower laminated body 5 and the upper laminated body 6, and the lower laminated body 5 and the upper laminated body 6 are laminated to produce a liquid crystal cell in a long film shape. And a light control film having a large area can be produced efficiently.

  However, when the orientations of the substrates 10 and 15 are aligned so that the slow axes of the substrates 10 and 15 are parallel above and below the liquid crystal layer 8 in this way, the optical anisotropy of the substrates 10 and 15 is determined. As a result, the viewing angle characteristics and transmittance at the time of black display may be deteriorated.

  Therefore, in this embodiment, on the lower laminate 5 side, the slow axis direction of the substrate 10 and the absorption axis of the linearly polarizing plate 3 are set to be parallel. On the upper laminate 6 side, the slow axis direction of the retardation film 2 </ b> A is set to be the slow axis direction of the substrate 10. Here, the linearly polarizing plate 2 is set so that the absorption axis is orthogonal to the linearly polarizing plate 3. Thereby, in this embodiment, the viewing angle characteristic and the transmittance during black display are improved.

  Here, FIG. 3 is a diagram showing a configuration of a comparative example manufactured for checking the viewing angle characteristics of the light control film 1 according to FIG. In this comparative example, the slow axes of the retardation films 2A and the absorption axis of the linearly polarizing plate 3 are set to be the slow axes of the base material 10 after setting the slow axes of the base materials 10 and 15 to be parallel. The absorption axis of the linearly polarizing plate 2 was set to be parallel to the slow axis of the substrate 10.

  FIG. 4 is a characteristic curve diagram showing measurement results of the light control film 1 and the comparative example. This measurement result is a characteristic curve diagram showing the measurement result of the viewing angle characteristic when light is blocked (when black is displayed), and is a measurement result obtained by measuring the transmittance by changing the azimuth angle at a polar angle of 60 degrees. The vertical axis represents the transmittance of all rays including diffused light components. The azimuth angle of 0 degrees is one side of the direction orthogonal to the absorption axis direction of the linearly polarizing plate 2. Reference symbol L1 represents the transmittance of the light control film of this embodiment. Reference symbol L2 is a measurement result of the comparative example.

  According to this measurement result, it can be seen that the light control film 1 can reduce the change in the transmittance due to the change in the azimuth angle, and even in the transmittance, it is smaller than the comparative example, thereby confirming the improvement of the light shielding rate. be able to. Note that the maximum value of the transmittance is 0.71% for the symbol L2 and 0.47% for the symbol L1, which also confirms the improvement of the light shielding rate.

〔Manufacturing process〕
FIG. 5 is a flowchart showing a manufacturing process of the liquid crystal cell. The production process of the light control film 1 is performed by attaching the retardation film 2A and the linear polarizing plates 2 and 3 to the liquid crystal cell 4 produced in this production process using an adhesive such as an ultraviolet curable resin, A separator film is provided and cut to a desired size to produce a light control film.

  In this manufacturing process, the transparent electrodes 11 and 16 are respectively formed on the transparent substrates 10 and 15 by applying a photolithography technique in the transparent electrode manufacturing process SP2. Subsequently, alignment layers 12 and 17 are formed on the base materials 10 and 15 in an alignment layer manufacturing step SP3. In the subsequent spacer preparation step SP4, a photoresist film is prepared on the transparent substrate 10 on which the alignment layer 12 is prepared, and then exposed and developed, whereby the spacer 013 is prepared.

  Thus, when the orientation layers 12 and 17 are produced on the base materials 10 and 15, respectively, and the lower laminate 5 and the upper laminate 6 are produced, this manufacturing process is performed by using a dispenser with a dispenser in the sealing process SP5. Is applied to the lower laminate 5 in a frame shape, and then a liquid crystal material related to the liquid crystal layer 8 is dropped into a predetermined position surrounded by the frame shape using a dispenser. Note that the order of the dropping of the liquid crystal material and the arrangement of the sealing material may be changed. Further, a sealing material or a liquid crystal material may be disposed on the upper laminate 6 instead of the lower laminate 5. Thereafter, in this manufacturing process, after the lower laminate 5 and the upper laminate 6 are laminated, the sealing material is cured by heating and pressing so that the liquid crystal layer 8 is sandwiched between the lower laminate 5 and the lower laminate 5. And the upper laminated body 6 is bonded and integrated with a sealing material.

[Detailed configuration of spacer]
Here, in this embodiment, the spacer 13 is formed in a columnar shape or a truncated cone shape. Further, in this embodiment, the Vickers hardness value Xs of the spacer 13 and the Vickers hardness value Xf of the portion where the tip of the spacer 13 abuts are Vickers hardness value 2 or more and Vickers hardness value 6 or less, and Xs <Xf. Thus, the reliability related to the spacer is further improved as compared with the related art.

  That is, when Xf <Xs, the tip of the spacer 13 penetrates into the opposing surface due to the pressing force during use, and as a result, the cell gap becomes non-uniform or local alignment failure occurs. In a severe case, the leading end of the spacer 13 breaks through the opposite laminated body, and the liquid crystal material leaks. However, by satisfying Xs <Xf, it is possible to reduce the situation where the tip of the spacer penetrates into the opposite surface due to the pressing force during use, etc., thereby making the cell gap non-uniform and local orientation. Generation | occurrence | production of a defect can be reduced and also the leakage of liquid crystal material can be avoided effectively.

  When the Vickers hardness value is smaller than 2, the spacer is crushed by the external pressure and the cell gap is reduced or the desired cell gap cannot be obtained. However, in this embodiment, the Vickers hardness value is 2 or more. The situation can be reduced. Further, when the Vickers hardness value is more than 6, the substrate is easily damaged, and cracks are generated when the whole is bent. In this embodiment, the Vickers hardness value is 6 or less, so that the substrate is damaged. And the occurrence of cracks when the whole is bent can be reduced. By these, the reliability regarding a spacer can be improved further compared with the past.

  Table 1 is a chart showing test results used for confirmation of the configuration related to the spacer. The light control films of Test Examples 1 to 6 in Table 1 are configured identically except that the configurations regarding the spacer and the alignment layer with which the spacer contacts are different. More specifically, in the light control films of Test Examples 1 to 6, the spacer 13 is provided only on the lower laminate 5, and the Vickers hardness value Xs of the spacer 13 is set according to the heat treatment conditions related to the spacer 13. did.

  That is, the spacer 13 is coated with the coating liquid related to the spacer 13 and then dried, and then a portion where the spacer 13 is produced is selectively exposed by mask exposure using an exposure apparatus. Note that this is a case of a positive type photoresist. On the contrary, in the case of a negative type photoresist, a part other than the part for producing the spacer 13 is selectively exposed. Thereafter, the unexposed or exposed portion of the spacer 13 is selectively removed by development processing, and processing such as rinsing is performed, and processing such as drying is performed as necessary.

  In this exposure process, exposure may be performed in a so-called half-cure state by heating in advance or in a heated environment. In the development process, after rinsing or the like is performed, the heat treatment is performed. May accelerate the reaction. The hardness Xs of the spacer 13 can be set by selecting a photoresist material related to the spacer 13, setting the heating temperature and time in the exposure process and the developing process, and setting the exposure light amount and the exposure time.

  In this embodiment, the Vickers hardness value Xs of the spacer 13 in Test Examples 1, 5, and 6 is set to 1.8, 4.2, and 4.2, respectively, by setting the heating temperature and time in the exposure process and the development process. The Vickers hardness value Xs of the spacer 13 in Test Examples 2, 3, and 4 was set to 2.2, 3.7, and 4.2, respectively. The spacer 13 was produced in a cylindrical shape having a diameter of 15 μm and a height of 5 μm.

  On the other hand, the alignment layer 17 of the upper laminated body 6 on which the spacer abuts was manufactured by rubbing treatment instead of the photo-alignment layer. That is, a polyimide film was prepared by applying a coating liquid, drying and curing, and this polyimide film was prepared by rubbing. Moreover, the Vickers hardness value Xf was set by the setting of the heating temperature at the time of hardening at the time of producing this polyimide film and the heating time. Note that the Vickers hardness value Xf may be adjusted by performing another heat treatment after the rubbing treatment. Thus, in Test Examples 1, 5, and 6, the Vickers hardness value Xf was set to 4.9, 6.7, and 3.6, and in Test Examples 2, 3, and 4, the Vickers hardness value Xf was set to 4.9. .

  In this experiment, a load corresponding to 0.8 MPa was applied in a state where the light control film was placed on a smooth surface having high hardness by a surface plate, and then the cell gap was measured to determine the decrease in the cell gap. The weighting time is 24 hours. After weighting in this way, the upper laminate and the lower laminate are peeled off and the spacer is observed with a microscope to check for collapse of the spacer (spacer collapse), and the part where the spacer contacts is observed with a microscope. The penetration of the spacer tip (film penetration) was observed.

  Here, for observation with this microscope, a front view, a perspective view, and a cross-section are observed using a method such as SEM, and the deformation of the spacer is visually confirmed. When the deformation of the spacer is confirmed, according to the situation, “ The presence or absence of “cell gap reduction, spacer crushing” was judged as “Good”. Therefore, in Table 1, “◯” indicates a case where no abnormality related to the corresponding item is observed, and “X” indicates a case where abnormality regarding the corresponding item is observed.

  Similarly, if the part where the spacer abuts is perspective using a technique such as SEM, if a dent (recess) is confirmed, “film penetration” is determined as x, and if no recess is observed, “film penetration” Was rated as ○.

  Moreover, in the state which laminated | stacked the laminated bodies 6 and 5 and applied the load corresponding to 0.1 MPa, the relative position of the laminated bodies 6 and 5 was displaced by 0.1 cm / sec, and generation | occurrence | production of the damage | wound was confirmed visually. Here, when scratches are confirmed in more than half of the multiple samples, “scratch (film)” is indicated by “x”, and conversely, scratches are not confirmed in more than half of the multiple samples. In this case, “scratch (film)” is indicated by “◯”.

  Further, in the state of the light control film, it was wound around a cylindrical mandrel having a diameter of 2 mm in accordance with the bending test of JIS K5600-5-1 to confirm the occurrence of cracks. In this test, when cracks are confirmed in the substrate in more than half of the multiple samples, “crack (film)” is indicated by “x”, and conversely, in more than half of the multiple samples, the substrate In the case where the occurrence of cracks is not confirmed, “crack (film)” is indicated by “◯”.

  In the measurement results of Table 1, in Test Example 1, due to insufficient spacer hardness, cell gap reduction and spacer crushing are observed, and in Test Example 5, the Vickers hardness value Xf of the spacer facing surface exceeds 6. Thus, generation of cracks was observed, and further, cell gap reduction and spacer collapse were observed. In Test Example 6, since the Vickers hardness value Xs of the spacer was larger than the Vickers hardness value Xf of the opposing surface, the substrate was observed to be damaged, and the penetration of the spacer tip was also confirmed. However, in Test Examples 2, 3, and 4, these phenomena are not observed, and the reliability related to the spacer can be further improved as compared with the related art.

  According to the above configuration, the slow axis of the base material is parallel to the upper and lower sides of the liquid crystal cell, and the slow axis direction of the retardation film for optical compensation with respect to the slow axis and the lower laminate side In the VA type light control film, the visual field at the time of black display is arranged such that the absorption axis direction of the linear polarizing plate is parallel and the absorption axis direction of the linear polarizing plate on the upper laminate side is orthogonal. A product with a large area can be efficiently produced by improving the corner characteristics and the light shielding rate.

[Second Embodiment]
FIG. 6 is a diagram showing a light control film according to the second embodiment of the present invention in comparison with FIG. Here, the light control film 31 is provided between the base material 15 of the upper laminate 6 and the linearly polarizing plate 2, and has the characteristics of a retardation film 2 </ b> C having a positive A plate property from the base material 15 side and a negative C plate property. A retardation film 2 </ b> D provided with is disposed. A retardation film 3 </ b> C having the characteristics of a negative C plate is disposed between the base material 10 of the lower laminate 5 and the linearly polarizing plate 3. The positive A plate is a positive uniaxial retardation optical element whose refractive index distribution satisfies nx> ny = nz. As the positive A plate, for example, a COP film, a polymerizable liquid crystal material in which the major axis direction is aligned in the in-plane direction can be applied. The negative C plate is a negative uniaxial retardation optical element whose refractive index distribution satisfies nz <nx = ny. As the negative C plate, for example, a TAC film, a polymerizable cholesteric liquid crystal material laminated on an alignment layer, or the like can be applied.

  The light control film of this embodiment is further optically compensated by these retardation films 2C, 2D, and 3C, further reducing the transmittance and improving the viewing angle characteristics. In this light control film 31, absorption of the linearly polarizing plate 3 on the lower laminate 5 side is such that the slow axes of the base materials 10 and 15 are parallel to the upper and lower sides of the liquid crystal cell 4 and the slow axis. Further, the linearly polarizing plates 2 on the upper laminate 6 side are arranged so that the absorption axis directions thereof are orthogonal so that the axial directions are parallel. Further, among the retardation films 2C, 2D, and 3C, the retardation film 2C according to the A plate is set so that the slow axis direction thereof is parallel to the slow axes of the base materials 10 and 15.

  The light control film 31 is configured in the same manner as in the first embodiment except that the configurations related to the retardation films 2C, 2D, and 3C are different.

  As in this embodiment, phase difference films 2C and 2D using a positive A plate and a negative C plate are provided on the linear polarizing plate of the upper laminate, and phase difference film 3C using a negative C plate is provided on the linear polarizing plate of the lower laminate. Even in the case where the viewing angle characteristics and the transmittance are further improved as provided, the same effects as in the first embodiment can be obtained.

[Third Embodiment]
FIG. 7 is a view showing a light control film according to a third embodiment of the present invention in comparison with FIG. Here, in the light control film 41, the retardation film 2 </ b> C having the characteristics of a positive A plate is disposed between the base material 15 of the upper laminate 6 and the linearly polarizing plate 2. A retardation film 3 </ b> C having the characteristics of a negative C plate is disposed between the base material 10 of the lower laminate 5 and the linearly polarizing plate 3.

  The light control film of this embodiment reduces the transmittance by optical compensation using the retardation films 2C and 3C, and improves the viewing angle characteristics. This embodiment is configured in the same manner as the first embodiment and the second embodiment, except that the configuration relating to the retardation films 2C and 3C is different.

  Even if the viewing angle characteristics and transmittance are further improved by providing retardation films 2C and 3C with positive A plate and negative C plate respectively on the linear polarizing plate as in this embodiment, the first implementation The same effect as the state can be obtained.

[Other Embodiments]
The specific configuration suitable for the implementation of the present invention has been described in detail above, but the present invention is combined with the above-described embodiments and further modified in various ways without departing from the spirit of the present invention. can do.

DESCRIPTION OF SYMBOLS 1, 31, 41 Light control film 2, 3 Linear polarizing plate 2B-2D, 3A-3C Retardation film 4 Liquid crystal cell 5 Lower laminated body 6 Upper laminated body 8 Liquid crystal layer 10 2nd base material 11 2nd transparency Electrode 12 Second alignment layer 13 Spacer 15 First substrate 16 First transparent electrode 17 First alignment layer

Claims (2)

A first linear polarizing plate, a liquid crystal cell, a retardation film functioning as an A plate, and a second linear polarizing plate are sequentially provided.
From the side of the first linear polarizing plate to the liquid crystal cell,
The 1st laminated body formed by laminating | stacking a 1st transparent electrode and a 1st orientation layer on a 1st base material, a liquid crystal layer, a 2nd transparent electrode and a 2nd orientation layer on a 2nd base material Are sequentially provided.
The amount of transmitted light is controlled by changing the orientation of the liquid crystal layer by the VA method by driving with the first and second transparent electrodes,
The slow axes of the first and second substrates, the slow axis of the retardation film, and the absorption axis of the first linear polarizing plate are parallel,
The light control film arrange | positioned so that the absorption axis of the said 1st and 2nd linear polarizing plate may orthogonally cross. A retardation film functioning as a C plate is provided between the first linear polarizing plate and the first base material and / or between the second linear polarizing plate and the retardation film. The light control film of Claim 1.

Images