JP2006084876A - Viewing angle control sheet and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a viewing angle control sheet which has a proper viewing angle by suppressing a decrease in contrast of an image due to external light, lessening the generation of a ghost, and suppressing a decrease in luminance of a screen by effectively using diffused light from a video side. <P>SOLUTION: Trapezoidally sectioned lens parts are arrayed at designated intervals and a wedgelike part between adjacent lens parts is filled with the same material with or a different material from the lens parts, the wedgelike part having a tip on the video source side and a bottom on an observer side and also having light absorption effects. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is installed on the front face of a display, and the display performance, in particular, a function for preventing a decrease in performance due to a decrease in contrast when external light hits the display, and a visual field by suitably diffusing the effective light of the display. The present invention relates to a viewing angle control sheet having a function of widening a corner and a display device using the same.

In an organic light-emitting diode display (hereinafter referred to as OLED), a liquid crystal display (hereinafter referred to as LCD), and the like, a visual field is usually obtained so that a viewer can obtain a good image from any position. Wide corners are preferred.
On the other hand, for example, when working on a commuter train, it may be difficult to see the screen from people around you. In such a case, it will be visible only to the viewer of the display and not to others. Control of the viewing angle is desired. In response to such a demand, for example, a louver type viewing angle control sheet as shown in FIG. 9 has been developed and used. The louver type viewing angle control sheet has an effect of increasing the contrast by blocking outside light, and for example, a viewing angle control sheet is disclosed in which occurrence of a double image (referred to as a ghost) in the louver is reduced. (See Patent Document 1 to Patent Document 3.) FIG. 5 of Patent Document 1 describes an illustration of a ghost.
Japanese Patent Publication No.58-47681 JP-T 6-504627 JP-A-9-311206

  However, the conventional louver-type viewing angle control sheet described in Patent Documents 1 to 3 simply cuts the image light in an oblique direction, and in a display such as a high-definition LCD, the viewer side There is a problem in that the diffused light of the diffused light source on the video side to be reached is reduced and the brightness of the screen is lowered.

  Therefore, the present invention suppresses a decrease in image contrast due to external light, suppresses the occurrence of ghost, suppresses a decrease in screen brightness by effectively using diffused light from the video side, and provides an appropriate viewing angle. It is an object of the present invention to provide a viewing angle control sheet.

  The present invention will be described below. In addition, in order to make an understanding of this invention easy, the referential mark of an accompanying drawing is appended, but this invention is not limited to the form of illustration by it.

  In the invention of claim 1, lens portions having a trapezoidal cross-sectional shape are arranged at a predetermined interval, and a wedge-shaped portion between adjacent lens portions is filled with the same or different material as the lens portion, and the wedge-shaped portion is filled. The viewing angle control sheet has a tip on the image source side and a bottom surface on the viewer side, and the wedge-shaped portion has a light absorption effect.

  According to a second aspect of the present invention, in the viewing angle control sheet according to the first aspect, a cross-sectional shape of the wedge-shaped portion is a substantially trapezoid having a wide bottom surface on the viewer side. By making the wedge-shaped part into a substantially isosceles trapezoidal shape, the apex angle of the upper and lower surfaces of the wedge-shaped part becomes obtuse, making it possible to easily manufacture a mold for producing the wedge-shaped part, and further improving the strength of the wedge-shaped part. A quality viewing angle control sheet can be manufactured stably.

  According to a third aspect of the present invention, in the viewing angle control sheet according to the first or second aspect, when the angle formed by the inclined surface portion of the wedge-shaped portion and the normal line of the light exit surface is θ, θ is 0 ° to 15 °. It is a range. In the present invention, the above-mentioned angle range is set as a preferable angle in order to totally reflect the image light by the slope portion of the wedge-shaped portion and widen the viewing angle. If the angle θ exceeds 15 degrees, it is necessary to widen the width of the black stripe BS in order to achieve a sufficient contrast enhancement effect or viewing angle control effect, so that the light use efficiency is lowered and the luminance is lowered. End up. Further, when the BS width is wide, there arises a problem that manufacture becomes more difficult. In the present invention, the angle θ between the inclined surface portion of the wedge-shaped portion of the cross-sectional shape and the normal line of the light exit surface does not necessarily have to be the same angle above and below the wedge-shaped portion, and the vertical angle is 0 degrees to 15 degrees. Within the range, it is possible to have different angles, for example 0 degrees and 10 degrees.

A fourth aspect of the present invention is the viewing angle control sheet according to any one of the first to third aspects, wherein the refractive index Nx of the material constituting at least the slope portion of the wedge-shaped portion and the material constituting the lens portion. Nx−Ny ≧ −0.01 between the refractive index Ny of
It has the relationship which becomes. In the present invention, by eliminating the refractive index difference between the refractive index Nx and the refractive index Ny, light incident on the wedge-shaped portion at a small angle is absorbed by the wedge-shaped portion without being totally reflected, and a ghost is substantially generated. It can be suppressed. In the case of Nx−Ny = −0.01, the image light incident at an angle of about 84 ° or more with respect to the inclined surface is totally reflected. However, if it is within this range, the ghost does not substantially cause a problem level. . Nx−Ny = less than −0.01 is not preferable because a ghost effect is generated around 10 ° to 30 ° on the observer side.

  The invention according to claim 5 is the viewing angle control sheet according to any one of claims 1 to 4, wherein light absorbing particles are added to the wedge-shaped portion.

  A sixth aspect of the present invention is the viewing angle control sheet according to the fifth aspect, wherein the wedge-shaped portion has a substantially trapezoidal shape having a wide bottom surface on the viewer side, and the average particle diameter of the light absorbing particles is 1 μm or more. The width is not more than the width of the upper bottom surface of the trapezoid.

  The invention according to claim 7 is the viewing angle control sheet according to claim 5 or 6, characterized in that the addition amount of the light absorbing particles is 10 to 50% by volume.

  The invention according to claim 8 is the viewing angle control sheet according to any one of claims 1 to 7, wherein at least one of AR, AS, AG, touch sensor, or a plurality of these is provided on at least one surface side. The additional function is provided.

  According to a ninth aspect of the present invention, in the viewing angle control sheet according to any one of the first to eighth aspects, the angles formed by the two inclined surface portions of the wedge-shaped portion and the normal line of the light exit surface are different. It is characterized by.

  A tenth aspect of the present invention solves the above problem by a display device using the viewing angle control sheet according to any one of the first to ninth aspects in a horizontal stripe.

  The invention of claim 11 is characterized in that the viewing angle control sheet according to any one of claims 1 to 9 is laminated on the observer side of the image source, or two sheets are laminated substantially orthogonally. The above-mentioned problem is solved by a display device.

  According to a twelfth aspect of the present invention, in the viewing angle control sheet used in the display device according to the eleventh aspect, each angle formed by the two slope portions of the wedge-shaped portion and the normal line of the light exit surface is an upper angle on a lower side. The above-mentioned problem is solved by a display device characterized in that the angle is larger than the angle.

  According to the present invention, the lens portions having a trapezoidal cross-sectional shape are arranged at a predetermined interval, and the cross-sectional shape of the wedge-shaped portion between adjacent lens portions is a substantially trapezoid having a wide bottom surface on the viewer side. As a result, the wedge-shaped portion can be easily manufactured, and a high-quality viewing angle control sheet with improved strength of the wedge-shaped portion can be obtained. Further, according to the viewing angle control sheet of the present invention, it is possible to effectively reduce the brightness of the screen by effectively using the diffused light from the image source, to have an appropriate viewing angle, and to suppress the occurrence of ghost. A viewing angle control sheet can be obtained. In addition, according to the viewing angle control sheet of the present invention, it is possible to suppress a decrease in image contrast due to external light.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a view showing a cross section in one direction of the viewing angle control sheet S1 according to the first embodiment of the present invention. In FIG. 1, an image light source is arranged on the right side of the drawing to emit diffused light, and an observer is located on the left side of the drawing. This viewing angle control sheet S1 is formed by laminating an observer-side base sheet 11, a lens unit 12, and an image source-side base sheet 13 in order from the observer side to the image source direction. The lens unit 12 is made of a material having a refractive index of N1. Furthermore, in the drawing, the cross-sectional shape of the portion sandwiched between the oblique sides of the two lens parts 12 adjacent in the vertical direction forms a wedge-shaped part having a wide lower bottom surface 17 on the observer side, and is the same or different material from the lens part 12. And filled with a material having a refractive index N2. In the following description, the portion filled with the material having the refractive index N2 is referred to as “wedge shaped portion 14”. The cross-sectional shape of the wedge-shaped portion 14 is preferably a substantially triangular or substantially trapezoidal shape having a wedge-shaped tip on the image source side in order to efficiently reflect diffused light from the image source. In FIG. 1, the wedge-shaped portion 14 has a substantially trapezoidal shape, and includes a lower bottom surface 17 on the observer side and a narrow upper bottom surface 18 that is a tip on the image source side.

The refractive index N1 of the lens portion 12 and the refractive index N2 of the wedge-shaped portion 14 are set within a predetermined range represented by the following formula (1) in order to obtain the optical characteristics of the viewing angle control sheet S1.
(Formula 1) N2-N1 ≧ −0.01
In addition, the angle between the inclined surface where the wedge-shaped portion 14 and the lens portion 12 are in contact with the normal V of the light exit surface (a line parallel to the perpendicular incident light with respect to the viewing angle control sheet S1) is formed at a predetermined angle θ _1. Yes. θ ₁ is in the range of 0 ° to 15 °.

  The wedge-shaped portion 14 is colored to a predetermined concentration with a pigment such as carbon or a predetermined dye. Further, the observer-side base sheet 11 and the image source-side base sheet 13 are made of a material having substantially the same refractive index as that of the lens unit 12. The outer surface of the observer-side base sheet 11 has at least one function among AR, AS, and AG on the observer side. Here, “AR” is an abbreviation for anti-reflection, and refers to a function of suppressing the reflectance of light incident on the lens surface. “AS” is an abbreviation for anti-static and refers to an antistatic function. “AG” is an abbreviation for anti-glare and refers to the anti-glare function of the lens. The viewing angle control sheet S1 according to the first embodiment may have only one of these functions or may have a plurality of functions.

  Next, the optical path of light entering the lens unit 12 of the viewing angle control sheet S1 will be briefly described with reference to FIG. In FIG. 1, the optical paths of the lights L11 to L14 are schematically shown. Now, the vertical light L11 incident on the vicinity of the center of the lens unit 12 from the image source side passes straight through the inside of the viewing angle control sheet S1, and reaches the observer. Incident light L12 that has entered the vicinity of the end of the lens unit 12 perpendicularly from the image source side is reflected on the inclined surface by the difference in refractive index between the lens unit 12 having a refractive index N1 and the wedge-shaped unit 14 having a refractive index N2, and is given a predetermined value. Light is emitted to the observer side at an angle. The light L13 incident at an angle near the end of the lens unit 12 from the image source side is reflected by the inclined surface, and is emitted to the observer side at a larger angle in the opposite direction to the incident time. Further, the light L14 incident on the inclined surface from the image source side with a small angle of a predetermined angle or less enters the wedge-shaped portion 14 without being totally reflected. Since the wedge-shaped portion 14 is colored, the light L14 is absorbed by the colored wedge-shaped portion 14, does not reach the observer side, and no ghost is generated. Further, external light L15 incident on the bottom surface 17 of the wedge-shaped portion 14 from the observer side enters the wedge-shaped portion 14 and is absorbed by the wedge-shaped portion 14 having a light absorption effect. In this way, the viewing angle can be controlled in the cross-sectional direction, and the viewing angle control sheet S1 having an appropriate viewing angle, high brightness and contrast, and suppressed ghost can be obtained.

(Second embodiment)
FIG. 2 is a view showing a cross section in one direction of the viewing angle control sheet S2 according to the second embodiment. Also in FIG. 2, an image light source is arranged on the right side of the drawing, and an observer is located on the left side of the drawing. The viewing angle control sheet S2 is formed by adhering an observer-side base sheet 21, a lens unit 22, and an image source-side base sheet 23 in order from the observer side to the image source direction. The lens unit 22 is made of a material having a refractive index of N1. Further, in the drawing, a trapezoidal section having a cross-sectional shape sandwiched between the slopes of two lens parts 22 adjacent in the vertical direction is filled with a material having a refractive index N2. In the following description, the portion filled with the material having the refractive index N2 is referred to as “wedge shaped portion 24”. The wedge-shaped portion 24 includes a wide lower bottom surface 27 on the viewer side and a narrow upper bottom surface 28 that is the tip on the image side.

The refractive index N1 of the lens portion 22 and the refractive index N2 of the wedge-shaped portion 24 are set within a predetermined range represented by the above formula (1) in order to obtain the optical characteristics of the viewing angle control sheet S2. Further, the angle formed by the inclined surface where the wedge-shaped portion 24 and the lens portion 22 are in contact with the normal V of the light exit surface (a line parallel to the perpendicular incident light with respect to the viewing angle control sheet S2) is formed at a predetermined angle θ _2. Yes. θ ₂ is in the range of 0 ° to 15 °.

  The wedge-shaped portion 24 is colored to a predetermined concentration with a pigment such as carbon or a predetermined dye. The observer-side base sheet 21 and the image source-side base sheet 23 are made of a material having substantially the same refractive index as that of the lens unit 22. The outer surface of the observer-side base sheet 21 has at least one function among AR, AS, and AG on the observer side. Also in the present embodiment, only one of these functions may be provided, or a plurality of functions may be provided.

  In the illustrated viewing angle control sheet S <b> 2, a black stripe BS is formed on the lower bottom surface 27 of the trapezoid forming the wedge-shaped portion 24. The wedge-shaped portion 24 is filled with a material having a refractive index N2. Also by the viewing angle control sheet S2 having this configuration, the incident lights L21 to L23 from the image source side follow the same optical paths as the incident lights L11 to L13 in the viewing angle control sheet S1 shown in the first embodiment. Furthermore, the light L24 incident on the inclined surface from the image source side with a small angle of a predetermined angle or less enters the wedge-shaped portion 24 without being totally reflected and is absorbed, and ghosting is suppressed. Further, the external light L25 incident on the black stripe BS on the bottom surface 27 is absorbed by the black stripe BS. Therefore, the contrast of the image according to the visual field from the observer side is improved. As described above, the viewing angle control sheet S2 also has the same effect as the viewing angle control sheet S1 in the first embodiment, that is, the viewing angle can be controlled in the cross-sectional direction, and has an appropriate viewing angle. In addition, it is possible to obtain the viewing angle control sheet S2 with high brightness and contrast and suppressed ghost.

(Third embodiment)
FIG. 3 shows a viewing angle control sheet S3 of the third embodiment of the present invention. This viewing angle control sheet S3 is arranged by adhering an image source side base sheet 31, a lens unit 32, and an observer side base sheet 33 in order from the observer side to the image source side direction. The lens part 32 is made of a material having a refractive index N1. The wedge-shaped part 34 sandwiched between the lens parts 32 adjacent in the vertical direction has a tip on the image source side, and the wedge-shaped part 34 has a refractive index substantially the same as the refractive index N1 of the lens part 32. The substance is filled. Further, in the drawing, the slope and the upper bottom surface 38 of the wedge-shaped portion 34 are formed by a layer 35 (hereinafter referred to as “transparent refractive index layer 35”) made of a transparent material having a refractive index N2.

The refractive index N1 of the lens unit 32 and the refractive index N2 of the transparent low-refractive index layer 35 are set within a predetermined range represented by the above formula (1) in order to obtain the optical characteristics of the viewing angle control sheet S3. Yes. Further, the angle formed by the inclined surface where the transparent refractive index layer 35 and the lens part 32 are in contact with the normal line V of the light exit surface (a line parallel to the perpendicular incident light with respect to the viewing angle control sheet S3) is formed at a predetermined angle θ ₃ . Has been. θ ₃ is in the range of 0 ° to 15 °.

  The lens portion 32 is usually made of a material such as epoxy acrylate having ionizing radiation curability. The wedge-shaped portion 34 is colored with a predetermined concentration with carbon, a pigment, a predetermined dye, or the like. Further, the observer-side base sheet 31 and the video source-side base sheet 33 are made of a material having substantially the same refractive index as that of the lens unit 32. Similar to the viewing angle control sheet S1 according to the first embodiment, the observer side base sheet 31 is provided with at least one of the AR, AS, and AG functions on the viewer side.

  Also by the viewing angle control sheet S3 having such a configuration, the incident lights L31 to L33 from the image source side follow the same optical paths as the incident lights L11 to L13 in the viewing angle control sheet S1 according to the first embodiment. Further, the light L34 incident on the inclined surface from the image source side with a small angle of a predetermined angle or less enters the wedge-shaped portion 34 without being totally reflected. The light L34 is absorbed by the colored wedge-shaped portion 34, and ghost generation is suppressed. Further, the external light L35 incident on the bottom surface 37 of the wedge-shaped portion 34 from the observer side enters the wedge-shaped portion 34 and is absorbed by the wedge-shaped portion 34 having a light absorption effect. Therefore, the contrast of the image according to the visual field from the observer side is improved. Therefore, the viewing angle control sheet S3 also has the same effect as the viewing angle control sheet S1 in the first embodiment, that is, the viewing angle can be controlled in the cross-sectional direction, has an appropriate viewing angle, and It is possible to obtain the viewing angle control sheet S3 with high brightness and contrast and suppressed ghost.

(Fourth embodiment)
FIG. 4 shows a cross section of the viewing angle control sheet S4 according to the fourth embodiment of the present invention. The viewing angle control sheet S4 is arranged by adhering an image source side base sheet 41, a lens unit 42, and an observer side base sheet 43 in order from the observer side to the image source side. The lens part 42 is made of a material having a refractive index N1. Further, in a trapezoidal section having a cross-sectional shape sandwiched between two lens portions 42 adjacent in the vertical direction in the drawing, the transparent material having a refractive index N2 (hereinafter referred to as “transparent refractive index material 46”). The material is filled with a material to which light absorbing particles 49 are added. In the following description, the portion filled with the transparent refractive index substance 46 is referred to as “wedge shaped portion 44”. The wedge-shaped portion 44 having a trapezoidal cross section has a lower bottom surface 47 on the observer side and an upper bottom surface 48 that is a tip on the image source side.

In the present embodiment, the refractive index N1 of the lens portion 42 and the refractive index N2 of the transparent refractive index substance 46 are predetermined as shown in the above formula (1) in order to obtain the optical characteristics of the viewing angle control sheet S4. Set to range. In addition, the angle between the inclined surface where the wedge-shaped portion 44 and the lens portion 42 are in contact with the normal V of the light exit surface (a line parallel to the perpendicular incident light with respect to the viewing angle control sheet S4) is formed at a predetermined angle θ _4. Yes. θ ₄ is in the range of 0 ° to 15 °.

  The lens part 42 is usually made of a material such as epoxy acrylate having ionizing radiation curability. In addition, a material such as urethane acrylate having ionizing radiation curability is usually used as the transparent refractive index substance 46. Commercially available colored resin fine particles can be used as the light absorbing particles 49. Further, the observer-side base sheet 41 and the image source-side base sheet 43 are made of a material having substantially the same refractive index as that of the lens unit 42. In the present embodiment, the observer side base sheet 43 has at least one function among AR, AS, and AG on the observer side, similarly to the viewing angle control sheet S1 in the first embodiment. It has.

  Next, the optical path of light entering the lens unit 42 of the viewing angle control sheet S4 will be briefly described with reference to FIG. In FIG. 4, the optical paths of the lights L41 to L43 and L44 are schematically shown. In FIG. 4, the vertical light L41 incident on the vicinity of the center of the lens unit 42 from the image source side passes straight through the view angle control sheet S4 as it is and reaches the observer. The vertical light L42 incident on the vicinity of the end of the lens unit 42 from the image source side is reflected on the slope due to the refractive index difference between the lens unit 42 and the transparent refractive index substance 46, and is emitted to the viewer side at a predetermined angle. The The light L43 incident at an angle from the image source side to the vicinity of the end of the lens unit 42 is reflected by the inclined surface, and is emitted to the observer side at a larger angle in the opposite direction to the incident time. Light L44 that enters the inclined surface from the image source side with a small angle of a predetermined angle or less enters the wedge-shaped portion 44. The light L44 is absorbed by the light-absorbing particles 49 of the wedge-shaped portion 44, and ghosting is suppressed. Further, external light L45 incident on the bottom surface 47 of the wedge-shaped portion 44 from the observer side enters the wedge-shaped portion 44 and is absorbed by the light-absorbing particles 49 having a light absorption effect. Thus, also by the viewing angle control sheet S4, the same effect as the viewing angle control sheet S1 in the first embodiment, that is, the viewing angle can be controlled in the cross-sectional direction, and has an appropriate viewing angle, In addition, it is possible to obtain the viewing angle control sheet S4 with high brightness and contrast and suppressed ghost.

(Fifth embodiment)
FIG. 5 shows a viewing angle control sheet S5 of the fifth embodiment of the present invention. The viewing angle control sheet S5 is also arranged by adhering the observer side base sheet 51, the lens unit 52, and the image source side base sheet 53 in order from the observer side to the image source direction. The lens part 52 is made of a material having a refractive index N1. The portion sandwiched between the lens portions 52 adjacent in the vertical direction forms a wedge-shaped portion 54 having a trapezoidal cross-sectional shape and has a tip on the image source side. The slope of the wedge-shaped portion 54 and the upper bottom surface 58 have a refractive index. The layer 55 is formed of a transparent material including N2 (hereinafter referred to as “transparent refractive index layer 55”). Further, the wedge-shaped portion 54 is filled with a material to which light absorbing particles 59 are added.

The refractive index N1 of the lens unit 52 and the refractive index N2 of the transparent refractive index layer 55 are set within a predetermined range represented by the above formula (1) in order to obtain the optical characteristics of the viewing angle control sheet S5. Yes. Further, the angle formed by the hypotenuse where the transparent low refractive index layer 55 and the lens portion 52 are in contact with the normal V of the light exit surface (a line parallel to the perpendicular incident light with respect to the viewing angle control sheet S5) is a predetermined angle θ ₅ . Is formed. θ ₅ is in the range of 0 ° to 15 °.

  The lens portion 52 is usually made of a material such as an epoxy acrylate having ionizing radiation curability. Commercially available colored resin fine particles can be used as the light absorbing particles 59. The image source side base sheet 51 and the observer side base sheet 53 are formed of a material having substantially the same refractive index as that of the lens portion 52. In the present embodiment, the observer side base sheet 53 has at least one function among AR, AS, and AG on the observer side, similarly to the viewing angle control sheet S1 according to the first embodiment. It has.

  Next, the optical path of light entering the lens unit 2 of the viewing angle control sheet S5 will be briefly described with reference to FIG. Also in FIG. 5, the optical paths of the lights L51 to L54 are schematically shown. In FIG. 5, the vertical light L51 incident on the vicinity of the center of the lens unit 52 from the image source side passes straight through the inside of the viewing angle control sheet S5 as it is and reaches the observer.

  The vertical light L52 incident near the end of the lens unit 52 from the image source side is totally reflected on the hypotenuse due to the refractive index difference between the lens unit 52 and the transparent low-refractive index layer 54, and reaches the observer side at a predetermined angle. Idemitsu. The light L53 incident at an angle from the image source side to the vicinity of the end of the lens unit 52 is reflected by the inclined surface, and is emitted to the observer side at a larger angle in the opposite direction to the incident time. Further, the light L54 that enters the inclined surface from the image source side with a small angle of a predetermined angle or less enters the wedge-shaped portion 54. The light L54 is absorbed by the light-absorbing particles 59 of the wedge-shaped portion 54, and ghosting is suppressed. Further, external light L55 incident on the bottom surface 57 of the wedge-shaped portion 54 from the observer side enters the wedge-shaped portion 54 and is absorbed by the light-absorbing particles 59 having a light absorption effect. In this way, it is possible to obtain a viewing angle control sheet S5 that has an appropriate viewing angle, suppresses a decrease in luminance, has high contrast, and suppresses ghosting.

  The light-absorbing particles 49 and 59 in the viewing angle control sheets S4 and S5 in the fourth embodiment and the fifth embodiment have an average particle diameter of 1 μm or more and the wedge-shaped portion is substantially trapezoidal. The width is preferably equal to or smaller than the width of the upper bottom surface of 54. If the size of the light absorbing particles 49 and 59 is too small, less than 1 μm, a sufficient light absorbing effect cannot be obtained. On the other hand, if the size of the light-absorbing particles 49 and 59 is too large and exceeds the width of the upper bottom surface, which is the tip portion, it is difficult to fill the inside of the wedge-shaped portions 44 and 54 during manufacturing.

  Further, the light absorption particles 49 and 59 in the viewing angle control sheets S4 and S5 in the fourth embodiment and the fifth embodiment are 10 to 50% by volume with respect to the entire volume of the wedge-shaped portions 44 and 54. Is preferred. By maintaining this ratio, it is possible to provide easy manufacturing conditions while maintaining a sufficient light absorption effect.

  In the present invention, the case where the cross-sectional shape of the wedge-shaped portion is a substantially isosceles trapezoid is described. However, even when the cross-sectional shape of the wedge-shaped portion is a substantially isosceles triangle, a good viewing angle control sheet can be obtained. Furthermore, the present invention is applicable even if the cross-sectional shape forming the wedge-shaped portion is a substantially trapezoidal shape or a substantially triangular shape, and the respective angles between the two slope portions of the wedge-shaped portion and the normal line of the light exit surface are different. . Next, a description will be given with reference to FIG.

FIG. 6 is a cross-sectional view of the viewing angle control sheet S6 in which the shape of the slope portion of the wedge-shaped portion 64 is different. The wedge part 64 is cross-sectional shape forms a trapezoid, two ramp portions of the wedge portion 64 have different respective angle between the normal of the light output surface, in FIG. 6, the sheet surface of the upper angle theta ₆₁ greater than the lower angle theta _62, for example, in FIG. 6, the upper angle theta ₆₁ is 10 degrees, the angle theta ₆₂ of the lower illustrates the case of zero degrees. As shown in FIG. 6, when the upper angle of the slope portion of the wedge-shaped portion 64 is larger than the lower angle, the wedge-shaped portion is used in a display device in a horizontal stripe in which the wedge-shaped portions are arranged in the horizontal direction. Since the apparatus is often viewed from slightly above, the transmittance is high with respect to the upward light from the image source, and the luminance on the viewer side can be further improved.

  FIG. 7 is a diagram showing an example of the configuration of the viewing angle control sheet of the present invention. The viewing angle control sheet S7 shown in FIG. 7 includes a unit lens portion 72 whose vertical cross-sectional shape is constant in the horizontal direction. A base sheet 71 is disposed on the observer side, and a base sheet 73 is disposed on the video source side. In the drawing, these three are shown apart for the sake of understanding, but they are actually bonded together.

  FIG. 8 shows a configuration of a display device 80 provided with a viewing angle control sheet according to the present invention. In FIG. 8, the lower left direction on the front side of the paper is the image source side, and the upper right direction on the back side of the paper is the observer side. The display device 80 of the present invention includes, in order from the video source side, a liquid crystal display panel 81, a viewing angle control sheet 82 in which lens portions are arranged in a vertical direction, and a viewing angle control sheet 83 in which lens portions are arranged in a horizontal direction. And a functional sheet 84 provided with at least one of the functions of AR, AS, and AG on the observer side. The base sheets of the viewing angle control sheet 82 and the viewing angle control sheet 83 are omitted in the drawing. The arrangement of the viewing angle control sheet 82 and the viewing angle control sheet 83 may be interchanged. In FIG. 8, they are shown separated from each other, but this is for the purpose of understanding the drawing, and in fact they are in contact with each other or bonded together.

Example 1
As shown in FIG. 4, a viewing angle control sheet having a wedge-shaped portion with an isosceles trapezoidal cross-sectional shape and a black stripe BS provided on the lower bottom surface of the trapezoidal portion was prepared according to the following specifications. . The BS ratio indicates the area ratio of the black stripe BS formed on the bottom surface of the wedge-shaped portion of the viewing angle control sheet, and the trapezoidal taper angle is the angle (θ) between the slope of the trapezoid and the normal line of the light exit surface.
BS rate: 25%
Lens pitch: 0.1 mm
Lens part material (resin) Refractive index: 1.56
Wedge material refractive index: 1.56
Wedge-shaped upper base width: 7 μm
Trapezoid taper angle: 5 °
Black light absorbing particle diameter: 5 μm
Black light absorbing particle concentration: 25%
The viewing angle of the above sheet can be controlled to approximately 40 °, and the image light incident on the effective portion is reflected and converged, the diffused light from the image light is effectively used, the contrast is high, and the wedge-shaped portion slopes. Since the light having a small incident angle is absorbed by the wedge-shaped portion, a viewing angle control sheet with suppressed ghost was obtained.

(Example 2)
A viewing angle control sheet is produced under the same conditions as in Example 1 except that the BS rate is 50%, the viewing angle is approximately 20 °, and the image light incident on the effective portion is reflected and converged. The diffused light from the light was used effectively, the contrast was high, the light with a small incident angle on the wedge-shaped slope was absorbed by the wedge-shaped part, and a viewing angle control sheet with suppressed ghost was obtained.

(Example 3)
The field of view has a trapezoidal wedge-shaped section in cross section, and as shown in FIG. 6, the trapezoidal upper slope has a taper of 10 ° and the lower slope has a taper of 0 °. An angle control sheet was prepared.
This viewing angle control sheet can also control the viewing angle to about 40 °, the image light incident on the effective portion is totally reflected and focused, the diffused light from the image light is effectively used, the contrast is high, and the wedge shape Since the light having a small incident angle on the inclined surface is absorbed by the wedge-shaped portion, a viewing angle control sheet in which ghost is suppressed is obtained.

Example 4
A viewing angle control sheet was produced under the same conditions as in Example 1 except that the wedge-shaped portion material refractive index was 1.565.

(Example 5)
A viewing angle control sheet was produced under the same conditions as in Example 1 except that the wedge-shaped portion material refractive index was 1.57.

(Comparative Example 1)
A viewing angle control sheet was produced under the same conditions as in Example 1 except that the wedge-shaped portion material refractive index was 1.58.

  The viewing angle control sheets prepared in Examples 1, 4, 5 and Comparative Example 1 were sequentially installed on the front surface of the liquid crystal display device, and the presence / absence of ghost of image light and the quality of contrast were compared by visual check. . The results and overall evaluation are shown in Table 1. In the lower part of Table 1, the numerical values of Nx-Ny are also shown.

  As shown in Table 1, the viewing angle control sheets shown in Examples 1, 4, and 5 did not cause ghost and exhibited good contrast. On the other hand, the viewing angle control sheet of Comparative Example 1 was unsuitable due to ghosting.

While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. Instead, the present invention can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification.

It is a figure which shows the cross section of the one direction of the viewing angle control sheet | seat in 1st embodiment of this invention. It is a figure which shows the cross section of the one direction of the viewing angle control sheet | seat in 2nd embodiment. It is a figure which shows the cross section of the one direction of the viewing angle control sheet in 3rd embodiment. It is a figure which shows the cross section of the one direction of the viewing angle control sheet | seat in 4th embodiment. It is a figure which shows the cross section of the one direction of the viewing angle control sheet | seat in 5th embodiment. It is sectional drawing of the viewing angle control sheet | seat in which the shape of the slope part of a wedge-shaped part shows another aspect. It is a figure which shows an example of a structure of a viewing angle control sheet. It is a figure which shows an example of a structure of the display apparatus provided with the viewing angle control sheet | seat of this invention. It is a figure which shows an example of the conventional viewing angle restriction sheet.

Explanation of symbols

S1, S2, S3, S4, S5, S6, S7 Viewing angle control sheet 11, 21, 31, 41, 51, 61, 71 Observer side base sheet 12, 22, 32, 42, 52, 62, 72 Lens part 13, 23, 33, 43, 53, 63, 73 Image source side base sheet 14, 24, 34, 44, 54, 64, 74 Wedge shaped part 35, 55 Transparent refractive index layer 17, 27, 37, 47, 57, 67 Lower bottom surface 18, 28, 38, 48, 58, 68 Upper bottom surface 46 Transparent refractive index material 49, 59 Light-absorbing particle 80 Display device L11, L12, L13, L21, L22, L23, L31, L32, L33, L41, L42, L43, L51, L52, L53, L6 Rays L14, L24, L34, L44, L54 Light incident on the slope at a small angle L15, L25, L35, L45, 55 external light

Claims (12)

The lens portions having a trapezoidal cross-sectional shape are arranged at a predetermined interval, and the wedge-shaped portion between the adjacent lens portions is filled with the same or different material as the lens portion, and the wedge-shaped portion is distal to the image source side. And a bottom surface on the viewer side, and the wedge-shaped portion has a light absorption effect. The viewing angle control sheet according to claim 1, wherein a cross-sectional shape of the wedge-shaped portion is a substantially trapezoidal shape having a wide bottom surface on the viewer side. 3. The viewing angle control sheet according to claim 1, wherein θ is in a range of 0 to 15 degrees, where θ is an angle formed by a slope portion of the wedge-shaped portion and a normal line of a light exit surface. Nx−Ny ≧ −0.01 between the refractive index Nx of the material constituting at least the slope portion of the wedge-shaped portion and the refractive index Ny of the material constituting the lens portion.
The viewing angle control sheet according to claim 1, wherein the viewing angle control sheet has the following relationship. The viewing angle control sheet according to claim 1, wherein light absorbing particles are added to the wedge-shaped portion. 6. The wedge-shaped portion according to claim 5, wherein the wedge-shaped portion has a substantially trapezoidal shape having a wide lower bottom surface on an observer side, and an average particle diameter of the light absorbing particles is 1 μm or more and not more than a width of the upper bottom surface of the trapezoid. A characteristic viewing angle control sheet. The viewing angle control sheet according to claim 5 or 6, wherein the addition amount of the light absorbing particles is 10 to 50% by volume. At least one surface side of the viewing angle control sheet according to any one of claims 1 to 7 is provided with one of AR, AS, AG, and a touch sensor, or a plurality of additional functions thereof. A viewing angle control sheet. The viewing angle control sheet according to any one of claims 1 to 8, wherein each of the two slope portions of the wedge-shaped portion has a different angle with a normal line of the light exit surface. A display device using the viewing angle control sheet according to claim 1 in a horizontal stripe. 10. A display device, wherein one viewing angle control sheet according to claim 1 is used on a viewer side of an image source, or two substantially perpendicular layers are stacked. The viewing angle control sheet used for the display device according to claim 10 or 11, wherein each of the angles formed by the two slope portions of the wedge-shaped portion and the normal line of the light exit surface is such that the upper angle is larger than the lower angle. A display device.

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