JP2008281938A - Viewing angle controlling device and display equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a viewing angle controlling device with which the viewing angle is restricted without lowering image quality viewed from the front face side (frontal quality), and to provide a display equipped with the same. <P>SOLUTION: The liquid crystal display 1 is equipped with: a liquid crystal panel 10 for displaying an image; and a viewing angle controlling film 20 laminated on the liquid crystal panel 10 and controlling the viewing angle. The viewing angle controlling film 20 has retardation plates (for example, negative C plates 22, 23) which do not exhibit birefringence in in-plane direction and exhibit the birefringence in the thickness direction between linearly polarizing plates 21, 25. At least one of the retardation plates (for example, the negative C plate 23) is a patterned film with through holes 23a or recessions formed thereon. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a viewing angle control element capable of controlling a viewing angle and a display including the viewing angle control element.

  A display is generally required to have a viewing angle as wide as possible so that a clear image can be seen from any viewing angle. In particular, liquid crystal displays that have been widely used recently have been developed with respect to wide viewing angles because the liquid crystal itself has a viewing angle dependency. However, depending on the usage environment, it may be more convenient for the viewing angle to be narrow so that only the user himself can view the display content. In particular, notebook personal computers, personal digital assistants (PDAs), mobile phones, and the like are highly likely to be used in places where an unspecified number of people can exist, such as in trains and airplanes. In such a use environment, it is desirable that the viewing angle of the display is narrow because it is not desirable to look into the display content from other people in the vicinity from the viewpoint of maintaining confidentiality and protecting privacy. Thus, in recent years, there has been an increasing demand for switching the viewing angle of one display between a wide viewing angle and a narrow viewing angle depending on the usage situation. This requirement is not limited to a liquid crystal display, but is a common problem for any display.

  In response to such demands, there is a technology that includes a phase difference control device in addition to a display device that displays an image, and changes the viewing angle characteristics by controlling the voltage applied to the phase difference control device. It has been proposed (for example, Patent Document 1 below). Patent Document 1 exemplifies chiral nematic liquid crystal, homogeneous liquid crystal, random alignment nematic liquid crystal, and the like as a liquid crystal mode used in a liquid crystal display device for phase difference control.

  In addition, a viewing angle control liquid crystal panel is provided above the display liquid crystal panel, and these panels are sandwiched between two polarizing plates, and the applied voltage to the viewing angle control liquid crystal panel is adjusted to control the viewing angle. The structure which performs this is also disclosed conventionally (for example, patent document 2). In Patent Document 2, the liquid crystal mode of the viewing angle control liquid crystal panel is a twisted nematic system.

  However, in the configuration in which the liquid crystal panel is used to control the viewing angle as described in Patent Documents 1 and 2, there is a problem that the thickness of the entire display increases. In addition, since a liquid crystal panel for controlling the viewing angle has to be manufactured and assembled, there is a problem that production costs are increased.

Therefore, a filter generally referred to as a “privacy filter” or the like is known as a mechanism for controlling the viewing angle more easily than the liquid crystal panel for viewing angle control as described above (Patent Document 3, non-patent document). Reference 1). The privacy filter described in Patent Document 3 transmits only light in a direction perpendicular to the filter surface. For this reason, when this privacy filter is pasted on the screen of the display device, the screen display cannot be seen from the horizontal direction. The filter described in Non-Patent Document 1 has a structure in which a louver film is laminated with a film such as PET (polyethylene terephthalate), and controls the direction and visible angle of transmitted light.
Japanese Patent No. 3322197 JP-A-10-268251 JP 2005-173571 A “3M Optical Systems Products (viewing angle adjustment film“ Light Control Film ”)”, [online], Sumitomo 3M Limited, [Search April 5, 2007], Internet, (URL: http: //www.mmm .co.jp / display / light / index.html)

  Here, with reference to FIG. 7, the structure of the louver film used for the filter described in the nonpatent literature 1 is demonstrated. Fig.7 (a) is sectional drawing of a louver film, FIG.7 (b) is a top view of a louver film. As shown in FIGS. 7A and 7B, the louver film 50 has a configuration in which louver light-shielding portions 51 are arranged between transmission portions 52 at regular intervals. The light incident on one surface of the louver film 50 is limited by the louver light-shielding part 51 in the transmission angle (β in FIG. 7A) when passing through the transmission part 52. Accordingly, the viewing angle of the display device is limited by attaching the louver film 50 to the screen of the display device.

  However, in the conventional louver film, since the transmitted light is limited by the louver shading unit 51, light that is blocked by the louver shading unit 51 and cannot be transmitted is generated, and the luminance of the screen viewed from the front is reduced. There's a problem. Further, as can be seen from FIG. 7B, since the stripe pattern of the louver shading part 51 can be visually recognized, there arises a problem that the image quality is deteriorated.

  Further, when the display device includes a color filter, in order to prevent interference between the louver light shielding portion 51 and the color filter, as shown in FIG. The louver film is arranged so as to be inclined with respect to the vertical and horizontal directions of the screen (the x and y directions shown in FIGS. 7A and 7B). This is because if the stripe pattern of the louver shading part 51 is parallel to the vertical or horizontal direction of the screen of the display device, moire fringes are generated at a specific period due to interference with the color filter of the display device. Because. However, when a louver film is arranged as shown in FIG. 7B, there is a problem that it is impossible to control the viewing angle that is symmetrical to the left and right (or up and down) of the screen.

  In view of the above problems, the present invention provides a viewing angle control element capable of limiting a viewing angle without deteriorating image quality (front quality) when viewed from the front, and a display including the viewing angle control element. With the goal.

  In order to achieve the above object, a display according to the present invention includes an image display device that displays an image, and a viewing angle control element that is stacked on the image display device and controls the viewing angle of the image display device. The viewing angle control element includes a pair of polarizing plates and at least one retardation plate disposed between the pair of polarizing plates, wherein the at least one retardation plate is a surface. A first retardation plate that does not exhibit birefringence in the inward direction and exhibits birefringence in the thickness direction, birefringence in the in-plane direction and thickness direction, and an in-plane slow axis A pattern including at least one of a second retardation plate that is parallel or perpendicular to the polarization absorption axis of the polarizing plate, wherein at least one of the at least one retardation plate has a through hole or a recess. Fill And characterized in that.

  According to said structure, (1) 1st phase difference plate which does not show birefringence in an in-plane direction, and shows birefringence in a thickness direction between a pair of polarizing plates, (2) In-plane direction And at least one phase difference including at least one of a second retardation plate that exhibits birefringence in the thickness direction and has an in-plane slow axis parallel or perpendicular to the polarization absorption axis of the polarizing plate. By providing the plate, it is possible to realize a state in which a phase difference is generated when viewed from an oblique direction and the display content of the image display device is difficult to see. Further, since at least one of the retardation plates is a patterned film in which a through hole or a recess is formed, the light transmitted through the through hole or the recess when passing through the retardation plate, and the through hole Alternatively, a phase shift occurs between the light transmitted through a portion other than the concave portion. As a result, when these lights pass through the retardation plate and then enter the polarizing plate, the amount of polarized light components that pass through the polarizing plate are different from each other. It is possible to realize a state where it is difficult to see the contents. In addition, according to the above configuration, since the conventional louver film and the liquid crystal panel for controlling the viewing angle are not used, the viewing angle in the display is reduced without deteriorating the image quality (front quality) when viewed from the front. It becomes possible to restrict.

  In the above display, a retardation plate satisfying a relationship of three-dimensional refractive index nx = ny> nz can be used as the first retardation plate. Further, as the second retardation plate, a retardation plate satisfying the relationship of three-dimensional refractive index nx> ny> nz or a retardation plate satisfying the relationship of three-dimensional refractive index nx> nz> ny is used. be able to.

  In the display described above, it is preferable that the viewing angle control element further includes a ¼ wavelength phase difference plate between the pair of polarizing plates. Furthermore, it is preferable that the ¼ wavelength phase difference plate is arranged so that its optical axis forms an angle of 45 ° or 135 ° with respect to the polarization absorption axis of the polarizing plate. According to these preferable configurations, the light shielding performance of the viewing angle control element can be improved.

  In the above display, the image display device is, for example, a transmissive or semi-transmissive liquid crystal display device having a liquid crystal layer between an incident side polarizing plate and an outgoing side polarizing plate. In this case, the viewing angle control element is disposed closer to the viewer than the liquid crystal display device, and the polarizing plate disposed on the liquid crystal display device side of the pair of polarizing plates of the viewing angle control element is the liquid crystal. It is also preferable to serve as the incident side polarizing plate of the display device. Alternatively, the viewing angle control element is disposed on the back side of the liquid crystal layer of the liquid crystal display device with respect to an observer, and the polarized light disposed on the liquid crystal display device side of the pair of polarizing plates of the viewing angle control element It is also preferable that the plate also serves as the output side polarizing plate of the liquid crystal display device. According to these preferable configurations, one polarizing plate is sufficient, which is advantageous in terms of the thickness of the entire apparatus, manufacturing cost, transmittance, and the like.

  In order to achieve the above object, a viewing angle control element according to the present invention is a viewing angle control element that is stacked on an image display device and controls the viewing angle of the image display device, and includes a pair of polarizing plates. And at least one retardation plate disposed between the pair of polarizing plates, wherein the at least one retardation plate does not exhibit birefringence in the in-plane direction and is birefringent in the thickness direction. A first retardation plate exhibiting a property, and a second position which exhibits birefringence in the in-plane direction and the thickness direction, and whose in-plane slow axis is parallel or perpendicular to the polarization absorption axis of the polarizing plate. It includes at least one of a phase difference plate, and at least one of the at least one phase difference plate is a patterned film in which a through hole or a recess is formed.

  ADVANTAGE OF THE INVENTION According to this invention, the viewing angle control element which can restrict | limit a viewing angle without reducing the image quality (front quality) when it sees from the front, and a display provided with the same can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, each figure referred below demonstrates only the main member required in order to demonstrate this invention among the structural members of embodiment of this invention, for simplification. Therefore, the display according to the present invention may include arbitrary components not shown in the drawings referred to in this specification. Moreover, the dimension of the member in each figure does not necessarily represent the dimension of an actual structural member, the dimension ratio of members, etc. faithfully.

  Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described with reference to the drawings. Here, as an example of the display according to the present invention, a configuration including a liquid crystal display device as an image display device is illustrated.

  1, (a) is a schematic cross-sectional view showing a schematic configuration of a liquid crystal display 1 (display) according to the present embodiment, and (b) is a viewing angle control film 20 (viewing angle control) provided in the liquid crystal display 1. It is a disassembled perspective view which shows schematic structure of an element. Note that FIG. 1A is intended to show the stacking order of the main constituent members of the liquid crystal display 1, and does not show the actual cross-sectional structure.

  As shown in FIG. 1A, a liquid crystal display 1 is arranged on a viewer side of a liquid crystal panel 10 (image display device) for displaying an image and the liquid crystal panel 10, and controls the viewing angle of the liquid crystal panel 10. A viewing angle control film 20 (viewing angle control element).

  In the example of FIG. 1A, the viewing angle control film 20 is disposed on the viewer side of the liquid crystal panel 10. As the liquid crystal panel 10, any type of liquid crystal panel can be used, and the liquid crystal mode, the driving method, and the like are not limited. The liquid crystal panel 10 may be a monochrome display panel or a color display panel. The liquid crystal panel 10 includes a backlight 11, a liquid crystal cell 12, and a linear polarizing plate 13. 1A is a transmissive liquid crystal panel having a backlight 11, but may be a transflective liquid crystal panel or a reflective liquid crystal panel. When the liquid crystal panel 10 is a reflective liquid crystal panel, no backlight is necessary.

  As shown in FIG. 1B, the viewing angle control film 20 is formed by laminating and bonding a pair of linearly polarizing plates 21 and 25, negative C plates 22 and 23, and a quarter-wave retardation film 24. Is made up of. The linear polarizing plate 25 is disposed on the side closest to the liquid crystal panel 10, and the quarter-wave retardation film 24, the negative C plate 23, the negative C plate 22, and the linear polarizing plate 21 are sequentially stacked thereon. ing. In addition, in FIG.1 (b), although the structural member of the viewing angle control film 20 is shown apart, in fact, these structural members are adhere | attached with the adhesive agent etc.

  As shown in FIG. 1B, the negative C plate 23 is a patterned film in which substantially rectangular through holes 23a are formed on the entire surface at a predetermined interval. Such a pattern can be easily formed by punching a negative C plate film. On the other hand, the negative C plate 22 is formed with a uniform thickness. The three-dimensional refractive index of the negative C plates 22 and 23 is nx = ny> nz. That is, each of the negative C plates 22 and 23 functions as a retardation plate that does not exhibit birefringence in the in-plane direction and exhibits birefringence in the thickness direction.

In the example shown in FIG. 1B, the linearly polarizing plates ₂₁ and ₂₅ are arranged such that their polarization absorption axes X ₂₁ and X ₂₅ are substantially parallel to each other. The quarter-wave retardation plate 24 has an optical axis (slow axis) X ₂₄ that forms an angle of approximately 45 ° (or 135 °) with respect to the polarization absorption axis X _{25 of} the linearly polarizing plate 25. Is arranged. However, the arrangement of the polarization absorption axes X ₂₁ and X ₂₅ and the optical axis (slow axis) X ₂₄ may have an error of about ± 10 °, and substantially the same effect can be obtained.

  In the liquid crystal display 1 shown in FIGS. 1A and 1B, the linear polarizing plate 25 provided on the liquid crystal panel 10 side in the viewing angle control film 20 also serves as the output side polarizing plate of the liquid crystal panel 10. . That is, the liquid crystal panel 10 converts the polarization state of the linearly polarized light emitted from the backlight 11 and transmitted through the linear polarizing plate 13 (incident side polarizing plate) into the liquid crystal cell 12 to be applied to the liquid crystal layer in the liquid crystal cell 12. Further change according to. As a result, only the polarization component that coincides with the polarization transmission axis of the linearly polarizing plate 25 (outgoing side polarizing plate) is transmitted through the liquid crystal cell 12 and is emitted to the viewer side through the linear polarizing plate 25. To do. Therefore, a desired image can be displayed by driving each pixel of the liquid crystal panel 10 according to a gradation to be displayed in a known manner.

  As shown in FIG. 2, the liquid crystal is aligned so that the linearly polarizing plate 25 and the polarization transmission axis coincide between the linearly polarizing plate 25 of the viewing angle control film 20 and the liquid crystal cell 12 of the liquid crystal panel 10. It is good also as a structure by which the output side polarizing plate 14 of the panel was provided separately. That is, the liquid crystal display 1a shown in FIG. 2 is a modification of the liquid crystal display 1 shown in FIG. 1, and a liquid crystal panel 10a as an image display device includes a backlight 11, a liquid crystal cell 12, and two pieces of linearly polarized light. Plates 13 and 14 are provided. However, as in the liquid crystal display 1 shown in FIG. 1, the configuration in which the linear polarizing plate 25 of the viewing angle control film 20 also serves as the output-side polarizing plate of the liquid crystal panel 10 has one polarizing plate than the configuration in FIG. This is advantageous in terms of the thickness of the entire apparatus, manufacturing cost, transmittance, and the like.

  Hereinafter, the principle that the viewing angle is limited by the viewing angle control film 20 when the liquid crystal display 1 according to the present embodiment is viewed from an oblique direction will be described with reference to FIGS.

  FIG. 3 is an explanatory diagram for defining the direction of the viewing angle with respect to the liquid crystal display 1. In FIG. 3, an arrow D <b> 1 indicates the direction of the observer's line of sight when the liquid crystal display 1 is viewed from the normal direction (front direction). Arrows D <b> 2 to D <b> 5 indicate the directions of the observer's line of sight when the liquid crystal display 1 is viewed from the viewpoint of a predetermined polar angle in four directions having azimuth angles that are 90 ° apart from each other. Note that the azimuth is the center of the screen, which is a line connecting the leg of the perpendicular line dropped from the viewpoint to the plane including the screen of the liquid crystal display 1 (in FIG. 3, the linearly polarizing plate 21) and the screen center of the liquid crystal display 1. The rotation angle around. The polar angle is an angle formed by a straight line connecting the center of the screen of the liquid crystal display 1 and the viewpoint to a normal line to the screen of the liquid crystal display 1.

  FIG. 4 is a cross-sectional view of a laminate of the negative C plate 22 and the negative C plate 23 in the viewing angle control film 20. As described above, since the through hole 23a is patterned on the entire surface of the negative C plate 23, as shown in FIG. 4, the light transmitted through the laminate of the negative C plate 22 and the negative C plate 23 There are two types of light: light that passes only through the negative C plate 22 (for example, L1 shown in FIG. 4) and light that passes through both the negative C plate 22 and the negative C plate 23 (for example, L2 shown in FIG. 4). Exists.

  FIG. 5 is an explanatory diagram showing changes in the polarization state when light emitted from the liquid crystal panel 10 passes through the viewing angle control film 20 for each viewing angle indicated by arrows D1 to D5 in FIG. As shown in the leftmost column of FIG. 5, the viewing angle passes through both of the negative C plates 22 and 23 toward an observer whose line of sight is facing the front direction (arrow D1 in FIG. 3). The light transmitted through the control film 20 first becomes linearly polarized light when passing through the linear polarizing plate 25, and then becomes circularly polarized light when transmitted through the quarter-wave retardation plate 24. Then, the negative C plates 23 and 22 are transmitted as circularly polarized light as they are, and the components that coincide with the polarization transmission axis of the linearly polarizing plate 21 are transmitted through the linearly polarizing plate 21 and emitted to the viewer side. As shown in the second column from the left in FIG. 5, only the negative C plate 22 is passed toward the observer whose direction of line of sight is facing the front direction (arrow D1 in FIG. 3) (that is, The polarization state of light transmitted through the viewing angle control film 20 (through the through hole 23a of the negative C plate 23) is the same as described above. This is because the negative C plate does not give a phase difference to light transmitted in the normal direction.

  On the other hand, for the light transmitted through the viewing angle control film 20 toward the observer facing the direction of the arrow D2 or D5 in FIG. 3, the light is incident on the ¼ wavelength phase difference plate 24 from an oblique direction. The shift of the phase difference when passing through the ¼ wavelength phase difference plate 24 becomes large. In addition, a phase difference due to the influence of the nz component of the refractive index of the negative C plate 22 (and the negative C plate 23) also occurs. Therefore, for the viewing angle of the arrow D2 or D5, if the sum of the phase differences generated in the quarter-wave retardation plate 24 and the negative C plate 22 (and the negative C plate 23) is λ / 2, The light cannot be transmitted through the linearly polarizing plate 21 but is shielded, and the screen of the liquid crystal display 1 appears black to the observer.

  Even if the linearly polarizing plate 21 is not completely shielded from light, the viewing angle control film 20 of this embodiment has the through-holes 23a provided in the pattern on the negative C plate 23. This has the effect of making the display content difficult to see. That is, as shown in FIG. 5, light passing through both negative C plates 22 and 23 passes only through the negative C plate 22 (that is, through the through hole 23a of the negative C plate 23). Since the negative C plate 23 is affected by the phase difference, the amount of the polarization component that can be transmitted through the linearly polarizing plate 21 is different. As a result, the light shielding degree of the viewing angle control film 20 is locally different according to the distribution pattern of the through holes 23 a of the negative C plate 23. Therefore, when viewed from the direction of the arrow D2 or D5 in FIG. 3, even if the viewing angle control film 20 is not sufficiently shielded from light, the display content of the liquid crystal panel 10 is hardly visible.

  Also, as shown in FIG. 5, the direction of the arrow D3 or D4 in FIG. 3 is also the same as when viewed from the direction of D2 or D5. Since the phase difference due to the influence of the C plate 23) occurs, the polarization component transmitted through the linearly polarizing plate 21 is reduced. Even if the linearly polarizing plate 21 is not completely shielded from light, the negative C plate 23 is provided with a through hole 23a in a pattern, so that it receives light that is affected by a phase difference caused by the negative C plate 23. The degree of shading differs depending on the light that is not. As a result, similarly to the above, the display content of the liquid crystal panel 10 is hardly visible.

  As described above, the liquid crystal display 1 according to the present embodiment includes the viewing angle control film 20, so that the polar angle is a predetermined viewing angle or more in the four azimuth angles indicated by arrows D2 to D5 in FIG. When viewed from above, the emitted light from the liquid crystal panel 10 is shielded by the viewing angle control film 20. As a result, when the liquid crystal display 1 is viewed from an oblique direction, the display content of the liquid crystal panel 10 cannot be visually recognized, so that it is possible to prevent peeping from others.

  The liquid crystal display 1 according to the present embodiment has the following advantages compared to the above-described conventional configuration in which viewing angle control is performed using a louver film or a viewing angle control liquid crystal panel.

  First, the louver film has a complicated process for forming the louver shading part, whereas the viewing angle control film 20 of the present embodiment can be easily manufactured without including a particularly complicated manufacturing process. Since the through hole 23a of the negative C plate 23 can be easily formed by punching as described above, the manufacturing process is not complicated.

  In addition, in the conventional configuration including the louver film, as described above, the louver shading portion needs to be disposed obliquely with respect to the top, bottom, left and right of the screen to prevent moiré. There is a disadvantage that cannot be provided. On the other hand, the liquid crystal display 1 according to the present embodiment can be shielded in four directions at the azimuth as described above.

  Furthermore, the viewing angle control film 20 according to the present embodiment can be easily attached to the surface of the liquid crystal panel 10 using an adhesive or the like. For this reason, compared with the structure provided with the liquid crystal panel for viewing angle control disclosed by patent document 1, 2, there exists an advantage that productivity is high and manufacturing cost can be low. Further, the entire apparatus can be formed thin.

  The above embodiments are all illustrative and not restrictive. The technical scope of the present invention is defined by the claims, and all the modifications within the scope equivalent to the configurations described therein are also included in the technical scope of the present invention.

  For example, in the above description, an example in which the negative C plate 23 is provided with the substantially rectangular through hole 23a is shown. However, the through-hole 23a is not limited to a rectangle, and can take any shape. Further, since patterning may be performed so that the optical path lengths at the time of transmission through the negative C plates 22 and 23 are locally different, a configuration in which a concave portion is provided instead of the through hole may be obtained, and the same effect can be obtained. Furthermore, the pattern shape may be a geometric pattern, a predetermined logo or character string, or a figure or character. In addition, the size and distribution density of individual patterns of the pattern shape are appropriately determined according to the use or usage of the image display device (liquid crystal panel 10), the size of characters and images displayed on the screen of the image display device, and the like. Just decide.

  Moreover, although the structure which used only the negative C plate 23 as the pattern film was illustrated, on the condition that the optical path length at the time of permeation | transmission of the negative C plates 22 and 23 differs locally, both of the negative C plates 22 and 23 are used. You may comprise a patterned film.

  Further, in the example of FIG. 1B, the configuration in which the negative C plate 23 formed of the patterned film is arranged closer to the liquid crystal panel 10 than the non-patterned negative C plate 22 is exemplified. However, the same effect can be obtained even if the arrangement of the negative C plate 22 and the negative C plate 23 is reversed from that shown in FIG.

  Further, in the example of FIG. 1B, a configuration in which two negative C plates 22 and 23 and one quarter wavelength phase difference plate 24 are provided as phase difference plates is illustrated. The number and type of retardation plates included in the film 20 are not limited to this example, and various combinations are conceivable. For example, as long as it is a retardation plate (first retardation plate) that does not exhibit birefringence in the in-plane direction and exhibits birefringence in the thickness direction, the retardation plate is not limited to the negative C plate, but any retardation plate. Can be used. Further, instead of the negative C plate, a retardation plate (second retardation plate) exhibiting birefringence in the in-plane direction and the thickness direction is used, and the slow axis in the plane of the retardation plate is a linearly polarizing plate 21. , 25, the same effect can be obtained even if they are arranged parallel to or perpendicular to the polarization absorption axes. Moreover, you may use combining such a 1st phase difference plate and a 2nd phase difference plate.

  As described above, the second retardation plate exhibiting birefringence in the in-plane direction and the thickness direction is a retardation plate (so-called X plate) that satisfies the relationship of three-dimensional refractive index nx> ny> nz. Alternatively, a retardation plate (so-called NEZ plate) having a three-dimensional refractive index satisfying a relationship of nx> nz> ny can be used.

  Moreover, in said specific example, the structure by which the linearly-polarizing plates 21 and 25 are arrange | positioned in parallel Nicol was illustrated. However, if a half-wave retardation plate is added between the linear polarizers 21 and 25 (the emission side of the quarter-wave retardation plate 24), the linear polarizers 21 and 25 can be arranged in crossed Nicols. The same effect as above can be obtained.

  Moreover, in said description, the structure by which the viewing angle control film 20 was arrange | positioned at the observer side rather than the liquid crystal panel 10 was illustrated. However, as shown in FIG. 6, the liquid crystal display 1b in which the viewing angle control film 20 is provided on the back side of the liquid crystal cell 12 of the liquid crystal panel 10 is also a modification of the liquid crystal display 1 shown in FIG. The same effect as the liquid crystal display 1 can be obtained. In the liquid crystal display 1 b shown in FIG. 6, the viewing angle control film 20 is disposed between the backlight 11 that is the light source of the liquid crystal panel 10 and the liquid crystal cell 12. In this configuration, the linear polarizing plate 25 of the viewing angle control film 20 also serves as the incident side polarizing plate of the liquid crystal panel 10. Further, on the viewer side of the liquid crystal panel 10, a linearly polarizing plate 14 as an output-side polarizing plate is disposed so that the linearly polarizing plate 21 of the viewing angle control film 20 is orthogonal to the polarization transmission axis.

  In the above embodiment, an example in which the viewing angle control film is applied to a display has been described. For example, the display angle control film 20 of the present embodiment is pasted on the display panel for a display that is desirable to prevent the peeping of others from obliquely behind, such as an automatic teller machine (ATM) display panel. It is preferable to use it. Moreover, it can prevent that a monitor screen reflects in the windshield and side glass of a vehicle by using the viewing angle control film 20 of this embodiment also for a vehicle-mounted monitor.

  Furthermore, in the above-described embodiment, the configuration including the liquid crystal display device as the image display device has been exemplified. However, the display according to the present invention can be implemented as a combination of an arbitrary image display device other than the liquid crystal display device and a viewing angle control element. For example, but not limited to, CRT (Cathode Ray Tube), organic EL (Electro Luminescence), inorganic EL, plasma display (PDP), field emission display (FED), fluorescent display tube (VFD: Vacuum Fluorescent Display), Digital Micro-mirror Device (DMD), Electrochromic Display (ECD), Surface-conduction Electron-emitter Display (SED) and other various image display devices On the other hand, the present invention can be applied.

  The use of the viewing angle control element according to the present invention is not limited to a display, and can be used to limit the viewing angle by being attached to various articles such as a window glass of a vehicle or a building or a screen.

  INDUSTRIAL APPLICABILITY The present invention can be industrially used as a viewing angle control element that can limit the viewing angle without deteriorating the image quality (front quality) when viewed from the front, and a display including the viewing angle control element.

It is a cross-sectional schematic diagram which shows schematic structure of the liquid crystal display concerning one Embodiment of this invention. It is a cross-sectional schematic diagram which shows schematic structure of the modification of the liquid crystal display concerning this embodiment. It is explanatory drawing which defines the direction of the viewing angle with respect to the liquid crystal display of this embodiment. It is sectional drawing of the laminated body of the negative C plate (without pattern) and the negative C plate (with pattern) in the viewing angle control film of this embodiment. It is explanatory drawing showing the change of the polarization state when the light radiate | emitted from the liquid crystal panel permeate | transmits a viewing angle control film for every viewing angle. It is a cross-sectional schematic diagram which shows schematic structure of the further modification of the liquid crystal display concerning this embodiment. The structure of the conventional louver film is shown, (a) is sectional drawing of a louver film, (b) is a top view of a louver film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display 10 Liquid crystal panel 11 Backlight 12 Liquid crystal cell 13 Linear polarizing plate 14 Linear polarizing plate 20 Viewing angle control film 21 Linear polarizing plate 22 Negative C plate 23 Negative C plate 24 1/4 wavelength phase difference plate 25 Linear polarizing plate

Claims (10)

A display comprising an image display device for displaying an image, and a viewing angle control element that is stacked on the image display device and controls a viewing angle of the image display device,
The viewing angle control element,
A pair of polarizing plates;
Including at least one retardation plate disposed between the pair of polarizing plates,
The at least one retardation plate is
A first retardation plate that does not exhibit birefringence in the in-plane direction and exhibits birefringence in the thickness direction;
A second retardation plate that exhibits birefringence in the in-plane direction and the thickness direction, and whose in-plane slow axis is parallel or perpendicular to the polarization absorption axis of the polarizing plate;
Including at least one of
The display according to claim 1, wherein at least one of the at least one retardation plate is a patterned film having a through hole or a recess.   The display according to claim 1, wherein a three-dimensional refractive index of the first retardation plate satisfies a relationship of nx = ny> nz.   The display according to claim 1, wherein a three-dimensional refractive index of the second retardation plate satisfies a relationship of nx> ny> nz.   The display according to claim 1, wherein a three-dimensional refractive index of the second retardation plate satisfies a relationship of nx> nz> ny.   The display according to claim 1, wherein the viewing angle control element further includes a ¼ wavelength phase difference plate between the pair of polarizing plates.   The display according to claim 5, wherein the ¼ wavelength phase difference plate is arranged such that an optical axis thereof forms an angle of 45 ° or 135 ° with respect to a polarization absorption axis of the polarizing plate.   The display according to any one of claims 1 to 6, wherein the image display device is a transmissive or semi-transmissive liquid crystal display device having a liquid crystal layer between an incident side polarizing plate and an outgoing side polarizing plate. . The viewing angle control element is disposed closer to the viewer than the liquid crystal display device;
The display according to claim 7, wherein a polarizing plate disposed on the liquid crystal display device side of the pair of polarizing plates of the viewing angle control element also serves as an incident-side polarizing plate of the liquid crystal display device. The viewing angle control element is disposed on the back side of the liquid crystal layer of the liquid crystal display device with respect to an observer;
The display according to claim 7, wherein a polarizing plate disposed on the liquid crystal display device side of the pair of polarizing plates of the viewing angle control element also serves as an output-side polarizing plate of the liquid crystal display device. A viewing angle control element that is stacked on the image display device and controls the viewing angle of the image display device,
A pair of polarizing plates;
Including at least one retardation plate disposed between the pair of polarizing plates,
The at least one retardation plate is
A first retardation plate that does not exhibit birefringence in the in-plane direction and exhibits birefringence in the thickness direction;
A second retardation plate that exhibits birefringence in the in-plane direction and the thickness direction, and whose in-plane slow axis is parallel or perpendicular to the polarization absorption axis of the polarizing plate;
Including at least one of
A viewing angle control element, wherein at least one of the at least one retardation plate is a patterned film having a through hole or a recess.

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