JP2011134560A - Lighting system equipped with shielding structure, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system having improved frontal brightness without narrowing a horizontal viewing angle by shielding the images of optical deflection elements. <P>SOLUTION: The lighting system 3 includes a light source 9, a light guide body 10 having an optical deflection surface 11 on which the optical deflection elements 12 are arranged, and a shielding structure 14 for transmitting light emitted from the light guide body and shielding the images of the optical deflection elements 12. The light guide body 10 has the optical deflection elements 12 arrayed at first and second pitches in first and second directions perpendicular to each other. The shielding structure 14 has a first linear lens 16 as a convex lenticular lens. The direction where the first linear lens 16 extends is approximately parallel to the first direction of the optical deflection elements. On the first main surface of the convex lenticular lens 16, an angle is formed between the tangent of the convex face cross section and the first main surface, as a maximum angle α obtained by (1) Expression. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an illuminating device and a display device including a concealing structure mainly used for controlling an illumination optical path.

  In recent large-sized liquid crystal televisions, flat display panels, etc., direct type illumination devices and edge light illumination devices are mainly employed. In the direct type illumination device, a plurality of cold cathode tubes and LEDs (Light Emitting Diodes) are regularly arranged as light sources on the back surface of the panel. A diffuser plate having a strong light scattering property is disposed between the light source and an image display element such as a liquid crystal panel so that a cold cathode tube or an LED as a light source is not visually recognized.

  On the other hand, in an edge light type illumination device, a plurality of cold cathode fluorescent lamps and LEDs are arranged on an end face of a translucent plate called a light guide plate. In general, a light deflecting surface that efficiently guides incident light incident from the end surface of the light guide plate to the exit surface is formed on the surface facing the exit surface of the light guide plate (the surface facing the image display element). Yes. As the light deflection element formed on the light deflection surface, there are various light deflection elements for efficiently guiding incident light to the emission surface, such as a printed white dot pattern or a lens shape. Proposed.

  However, the edge light type illumination device has a structure in which the light source is disposed only on the light-transmitting end face of the light guide plate, and thus the number of light sources installed is limited. Therefore, it becomes difficult to brighten the entire display as the liquid crystal display device becomes large, and the role of the optical sheet for improving the brightness becomes important.

As means for improving the brightness of the liquid crystal display screen, BEF (Brightness Enhancement Film) “brightness enhancement film”, which is a registered trademark of 3M USA, is widely used as a lens sheet.
26 to 28 show the brightness enhancement films described in Patent Documents 1 and 2 below. 26 schematically shows a surface light source 182, a BEF 185 as a brightness enhancement film on which light emitted from the surface light source 182 is incident, and a liquid crystal panel 184. As shown in FIG. 27, the BEF 185 is an optical film in which unit prisms 187 having a triangular cross section are periodically arranged in one direction on a transparent substrate 186. The unit prism 187 has a size (pitch) larger than the wavelength of light.

  The BEF 185 collects light from “off-axis” and redirects this light “on-axis” or “recycle” toward the viewer. Can be made. That is, the BEF 185 can increase the on-axis brightness by reducing the off-axis brightness when using the liquid crystal display device (when observing). The “on-axis” mentioned here is a direction that coincides with the visual field direction F ′ of the observer in FIG.

When using a lens sheet typified by BEF185, unevenness of light emitted from the light guide plate is reduced by disposing a diffusion film in which a diffusion filler is applied on a transparent substrate between the light guide plate and the lens sheet. Can be suppressed.
Furthermore, when a diffusion film is disposed between the lens sheet and the liquid crystal panel, side lobes of emitted light caused by the prism sheet can be reduced, and regularly arranged lenses and liquid crystal pixels Moire interference fringes generated during the period can be prevented.

Japanese Patent Publication No. 1-378001 JP-A-6-102506 Japanese National Patent Publication No. 10-506500 JP 2004-295080 A

By the way, as described above, the light guide plate used in the edge light type illumination device includes a light deflection surface at a position facing the exit surface, and the light deflection surface has a white dot pattern or a microlens (concave or convex). ), And other lens-shaped light deflection elements are formed.
However, since any light deflection element is formed of a reflection layer or a structure that is regularly or regularly arranged in a pseudo irregular manner, a lens sheet represented by the above-mentioned BEF185 and There are problems such as interference (moire fringes) and unevenness of the light deflection surface. As a means for solving the problem, a method of using a diffusion film as shown in Patent Document 4 between the light guide plate and the lens sheet is generally used.

The BEF 185 is one of the most efficient lens sheets for improving the brightness in the front direction. However, in a medium or large-sized liquid crystal display device exceeding 20 inches, the light collecting function of one BEF 185 is not sufficient. is the current situation. On the other hand, as one of the methods for further improving the luminance, for example, there is a configuration in which two BEF185s are arranged in a direction orthogonal to each other, but there is a problem that the viewing angle of the liquid crystal display device becomes extremely narrow.
Compared with a notebook personal computer, a portable information terminal, or the like, a liquid crystal display device for TV use requires a sufficient viewing angle, particularly in the horizontal direction.

As described above, in the conventional illumination device, in order to conceal the light deflection element formed on the light deflection surface, it is necessary to arrange a diffusion sheet having almost no light collecting function, and the luminance is reduced accordingly. There was a bug. Further, in order to obtain the luminance required for the liquid crystal display device, it is not sufficient to use only one BEF185, and there is a problem that the viewing angle becomes extremely narrow when two are used.
At present, no optical sheet that can solve both of these problems has been proposed.

  The present invention has been made in view of the above circumstances, and conceals the image of the light deflection element provided on the light deflection surface of the light guide plate, and without extremely narrowing the horizontal viewing angle of the screen. An object of the present invention is to provide a lighting device and a display device provided with a concealing structure that improves the luminance in the front direction.

In order to solve the above-mentioned problems, the present invention takes the following measures.
That is, the illumination device according to the present invention includes a light source, an incident surface on which light emitted from the light source is incident, an exit surface that emits incident light to the observer side, and a light deflection element that guides the incident light to the exit surface. An illumination device comprising: a light guide including a light deflecting surface; and a concealing structure configured to transmit light emitted from an exit surface of the light guide to an observer side and conceal an image of the light deflecting element. ,
In the light guide, two light deflection elements are arranged at a _first pitch P1 in a _first direction and at a second pitch P2 in a _second direction substantially orthogonal to the first direction. Has a dimensional array structure,
The concealing structure includes a first main surface that emits incident light and a second main surface that causes the light emitted from the light guide to be incident as incident light, and the first main surface is arranged in at least one direction. 1 linear lens, the direction in which the first linear lens extends and the first direction of the light deflection element are set substantially parallel,
The first linear lens is a convex lenticular lens whose cross-sectional shape is a convex curved surface, and an angle formed by a tangent at an arbitrary point on the convex curved surface and the first principal surface increases from the top to the first principal surface. The maximum angle α is defined by the following equation (1).

但し、ｎ_０、：導光体の屈折率
ｔ：導光体の厚み
ｎ_１：第１の線状レンズの屈折率
θ_ｉ：隠蔽構造体へ入射する光の入射角。

However, n ₀ ,: Refractive index of the light guide t: Thickness of the light guide n ₁ : Refractive index of the first linear lens θ _i : Incident angle of light incident on the concealing structure.

  According to the illuminating device of the present invention, the light incident on the light guide plate from the light source is reflected by the light deflection element on the light deflection surface and emitted from the emission surface, and emitted as illumination light to the outside through the concealment structure. Since the direction in which the linear lens extends and the first direction of the light deflection element are set substantially parallel to each other, the light arranged in the first direction by the convex lenticular lens as the first linear lens The deflecting element can be diffused linearly in the second direction to conceal the image of the light deflecting element as viewed from the light exit direction of the illumination device. In addition, by providing a convex lenticular lens in the concealment structure, it is possible to prevent the viewing angle in a direction substantially perpendicular to the extending direction from being narrowed, and to the concealment structure by the contact angle α defined by the equation (1). The incident light is refracted in the front direction so that the front brightness can be widely controlled and the concealment can be improved.

In the illumination device according to the present invention, the cross-sectional shape of the first linear lens is defined by the following equation (2).
Here, the expression (2) is an expression when the unit lens pitch of the first linear lens is normalized to 1, z is a position function in the height direction of the first linear lens, and r is It is a position variable in the width direction of the first linear lens.

By defining the first linear lens by the expression (2), it is possible to linearize the image of the light deflection element that emits the reflected light and to exhibit the light collecting effect.

Further, it is preferable that P ₂ / P _1, which is a ratio between the _first pitch P ₁ and the second pitch P ₂ of the light deflection element, is defined by the following expression (3).
_{1.0 <P 2 / P 1 <} 3.0 (3)
According to the illuminating device of the present invention, the light deflection element is changed to the second direction by the expression (3) and the extending direction of the first linear lens and the first direction of the light deflection element being substantially parallel. It can be linearized in the direction and further concealed.

Further, the light deflection elements are arranged in the first n times the pitch P ₁ in the first direction, the second sequence m times the pitch P ₂ in a second direction substantially perpendicular to the first direction Preferably, n and m are randomly selected from 1 to 10 integers.
As a result, the pitches P1 and P2 in the first direction and the second direction of the light deflection elements are irregularly arranged. Moire interference fringes with the sheet can be suppressed.

Further, P ₂ / P ₁ which is a ratio of the first pitch P ₁ and the second pitch P ₂ may be defined by the following expression (4).
1.4 <P ₂ / P ₁ <2.2 (4)
Since the expression (4) and the extending direction of the first linear lens and the first direction of the light deflection element are substantially parallel, the light deflection element can be linearized in the second direction. It can be hidden further.

In the illumination device of the present invention, the light deflection element is formed by removing an arbitrary light deflection element from a hexagonal arrangement or a hexagonal arrangement in which a triangle drawn by connecting the three adjacent light deflection elements becomes a substantially regular triangle. It is preferable to constitute the arrangement.
According to this configuration, since the distance between the light deflection elements in the vertical direction, the horizontal direction, and the diagonal direction of the light deflection elements provided on the light deflection surface approaches a uniform distance that does not greatly differ, It becomes easy to make uniform.

In the illuminating device according to the present invention, a point light source that emits substantially Lambertian light from one point is disposed on the second main surface side of the concealing structure, and the main axis of the emitted light substantially coincides with the normal direction of the second main surface. In this arrangement, the light that is incident from the second main surface and is emitted from the first main surface in the normal direction of the first main surface is an arrangement of the first linear lenses centering directly on the point light source. A concealing structure is provided so that the light is converted into linear light spreading in a direction, and the peak luminance position of the linear light is directly above the point light source.
According to the configuration of the present invention, the light that is reflected by the light deflection element and incident on the concealing structure can be converted into linear light that extends in the arrangement direction of the convex lenticular lens around the point light source. The concealability of the light deflection element can be further improved.
Alternatively, when the peak luminance position of the linear light, instead of directly above the point light source, are present in the off-position immediately above, where L ₀ immediately above luminance of the point light _source, the peak intensity was L _1, L ₁ / L ₀ may be 200% or less.
When this configuration is adopted, the light incident on the concealing structure is converted into linear light that spreads in the arrangement direction of the convex lenticular lenses centering directly on the point light source, thereby improving the concealing property of the light deflection element. On the other hand, if L ₁ / L ₀ exceeds 200%, even if the point light source composed of the light deflecting element is extended to linear light, the peak luminance position looks very shining, so that sufficient concealment cannot be exhibited. .

Moreover, it is preferable that a concealment structure is provided with the 2nd linear lens arranged substantially orthogonally to the 1st linear lens.
Therefore, the first linear lens of the concealing structure can improve the concealing property by widening the linearity of the light deflecting element, and if the second linear lens is a triangular prism lens shape, the condensing property of the front is improved. A convex lenticular lens can further improve the concealment of the image of the light deflection element.

In addition, a condensing sheet may be arranged on the first main surface side of the concealing structure, thereby improving the light condensing property and preventing the field of view from being narrowed.
The condensing sheet includes a third linear lens arranged in at least one direction, and the arrangement direction of the third linear lens and the arrangement direction of the first linear lens in the concealing structure are substantially orthogonal to each other. It is preferable to do.
The third linear lens can improve the light condensing property and can prevent the field of view from being narrowed.

The condensing sheet may further include a fourth linear lens that is substantially orthogonal to the third linear lens.
If one or both of the third linear lens and the fourth linear lens is a triangular prism lens, it is possible to improve the concealability of the light deflection element by splitting the condensing function and the image of the light deflection element. If one or both of the third linear lens and the fourth linear lens is a lenticular lens, the concealability of the light deflection element can be improved by linearizing the image of the light deflection element. If the third linear lens and the fourth linear lens are a combination of a lenticular lens and a triangular prism lens, concealment performance and light condensing performance can be improved simultaneously.

A display device according to the present invention includes the illumination device according to any one of claims 1 to 12, and an image display element that is disposed on a side on which light emitted from the illumination device is incident and defines a display image. It is characterized by having.
According to the present invention, the unevenness of the light reflected by the light deflecting element is suppressed and the concealing structure is transmitted, so that the light deflecting element is concealed while being linearized by the spread of the image of the light deflecting element. The brightness can be improved. And when the condensing sheet | seat is further arrange | positioned, condensing property can also be improved and front brightness can be made high.

The display device according to the present invention is characterized in that the first linear lens of the concealing structure extends in the vertical direction of the image display element.
According to the present invention, the extending direction of the convex lenticular lens that is the first linear lens and the first direction of the light deflecting element are substantially parallel, so that the light deflecting element is expanded in the second direction. In addition to being able to be linearized and further concealed, the convex lenticular lens extends in the vertical direction, so that the horizontal field of view of the image display element can be secured and condensed. .

In addition, when the first linear lens of the concealing structure extends in the horizontal direction of the image display element, the third linear lens of the condenser lens extends in the vertical direction of the image display element. It is characterized by being arranged.
In this case, the third linear lens can exhibit the light collecting performance without narrowing the visual field in the horizontal direction.

In addition, when the first linear lens of the concealing structure extends in the horizontal direction of the image display element, the fourth linear lens of the condenser lens extends in the vertical direction of the image display element. It is characterized by being arranged.
In this case, the concealability of the light deflection element is enhanced by the third linear lens, and the light condensing performance can be exhibited without narrowing the visual field in the horizontal direction by the fourth linear lens.

In addition, a polarization separation / reflection sheet may be provided between the illumination device and the image display element, and the light reflection / transmission / reflection, light diffusion and light collection effect by the polarization reflection / separation sheet. Can be demonstrated.
Further, the image display element defines a display image in accordance with transmission / shielding in pixel units.

According to the illumination device and the display device of the present invention, the light incident on the light guide plate from the light source is reflected by the light deflection element on the light deflection surface and emitted, and emitted as illumination light through the concealment structure. Since the extending direction of the lens and the first direction of the light deflection element are set substantially parallel to each other, the light deflection element arranged in the first direction by the convex lenticular lens as the first linear lens Can be diffused linearly in the second direction to conceal the image of the light deflection element when viewed from the light exit direction side of the illumination device.
In addition, by providing a convex lenticular lens in the concealing structure, it is possible to suppress the front viewing angle in a direction substantially orthogonal to the extending direction from being narrowed, and to conceal the concealing structure by the contact angle α defined by the equation (1). The front luminance can be widely controlled by refracting light incident on the body in the front direction.

It is a cross-sectional schematic diagram which shows the structure of the display apparatus by the 1st Embodiment of this invention. It is a principal part top view which shows the example of arrangement | positioning of the light deflection | deviation element in the light arrangement | positioning surface of the light guide shown in FIG. FIG. 3 is a plan view of a principal part showing an arrangement example of light deflection elements different from FIG. 2. It is a perspective view of the concealment structure shown in FIG. It is principal part sectional drawing of the concealment structure shown in FIG. It is explanatory drawing which shows the arrangement configuration and optical path of a light guide and a concealment structure. It is a figure which shows the state in which the image of the light deflection | deviation element in the light deflection surface of a light guide was linearized. It is a schematic diagram which shows the optical path and luminance distribution of a normal direction at the time of entering Lambertian light into a concealing structure. It is explanatory drawing which shows the relationship between the outline shape of the 1st linear lens provided in the concealment structure, and (2) Formula. It is explanatory drawing which shows the convex curved surface which makes the cross section of a 1st linear lens. It is a perspective view which shows the 1st modification of a concealment structure. It is a perspective view which shows the 2nd modification of a concealment structure. It is a perspective view which shows the 3rd modification of a concealment structure. It is a perspective view which shows the 4th modification of a concealment structure. It is a cross-sectional schematic diagram which shows the structure of the display apparatus by the 2nd Embodiment of this invention. It is a perspective view of the condensing sheet in 2nd Embodiment. FIG. 17 shows the condensing sheet shown in FIG. 16, wherein (a) is a schematic cross-sectional view showing a third linear lens, (b) is a schematic cross-sectional view showing a fourth linear lens, and (c) is a schematic plan view. FIG. It is a perspective view which shows the 1st modification of a condensing sheet. It is a perspective view which shows the 2nd modification of a condensing sheet. It is a perspective view which shows the 3rd modification of a condensing sheet. It is a perspective view which shows the 4th modification of a condensing sheet. It is a perspective view which shows the 5th modification of a condensing sheet. It is a perspective view which shows the 6th modification of a condensing sheet. It is a perspective view which shows the 7th modification of a condensing sheet. It is a table | surface which shows the evaluation result of the Example and comparative example of this invention. It is a cross-sectional schematic diagram of the display apparatus containing BEF in a prior art. It is a perspective view of BEF shown in FIG. It is a graph which shows the relationship between light intensity and the angle with respect to a visual field direction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present specification, when the same member is represented by a superordinate concept and a subordinate concept, the same reference numeral may be used for both.
FIG. 1 shows a display device 1 according to a first embodiment of the present invention.
A display device 1 shown in FIG. 1 is of an edge light type including an image display element 2 and a lighting device 3 arranged on the light incident side of the image display element 2.
The image display element 2 is composed of a pair of polarizing plates (polarizing films) 5 and 6 and a liquid crystal panel 7 sandwiched therebetween. The liquid crystal panel 7 is configured, for example, by filling a liquid crystal layer between two glass substrates.

In FIG. 1, the illumination device 3 uses, for example, a point light source as the light source 9. As the point light source, for example, an LED is used. A white LED, RGB-LED, or the like is used as the LED. A linear light source may be used as the light source. As the linear light source, for example, a fluorescent tube represented by CCFL is used. In the illuminating device 3 shown in FIG. 1, for example, a rectangular plate-shaped light guide plate 10 is provided, and a light source 9 is disposed on two opposing end surfaces of the light guide plate 10 in the thickness direction.
However, the present invention is not limited to such a configuration, and the light source 9 may be disposed only on one end surface of the light guide plate 10, or the light source 9 may be disposed on four end surfaces of the light guide plate 10. In addition, the light guide plate 10 is not limited to a flat plate shape as shown in FIG.
In the light guide plate 10, a light deflection surface 11 is formed on the surface opposite to the emission surface 10 a that emits light directed toward the image display element 2. The light deflection surface 11 is provided with a light deflection element 12 that reflects and deflects incident light from the light source 9 toward the exit surface 10a (see FIG. 2). As the light deflection element 12, for example, as shown in FIG. 2, white diffuse reflection dots are printed on the light deflection surface 11. As another example of the light deflection element 12, a structure such as a microlens shape or a prism shape may be formed on the light deflection surface 11.

Since the light guide plate 10 is generally a transparent plate, the light deflection element 12 can be viewed from the observer side F through the display device 1. Further, unlike the direct backlight type display device, in the edge light type display device 1, the light emitted from the light guide plate 10 has a lot of unevenness and is greatly different from the uniform diffused light.
Therefore, in a general edge light type illumination device, a diffusion film having strong diffusibility is arranged on the light guide plate 10 in order to conceal the light deflection element 12 and reduce unevenness of the emitted light. It is installed. However, since such a diffusion film has almost no light collecting performance, it causes a decrease in luminance and is not preferable.

In the present embodiment, the light deflection elements 12 are provided at predetermined intervals on the light deflection surface 11 of the light guide plate 10 shown in FIG. In FIG. 2, the light deflection element 12 is shown in a circular shape, but is not limited thereto, and may be an elliptical shape, a prism shape, a polygonal shape, or the like.
Light deflection elements 12, as shown in FIG., Are arranged at a pitch of P ₁ in a first direction, the two-dimensional arrangement and made are arranged at a pitch of P ₂ in a second direction perpendicular to the first direction Has been. Here, the first direction and the second direction can be arbitrarily selected for the vertical visual field and the horizontal visual field of the display device 1.
A reflective sheet 13 is provided on the surface of the light guide plate 10 that faces the light deflection surface 11.

FIG. 3 shows another arrangement example of the light deflection element 12.
Light deflection elements 12, like the structure shown in FIG. 2, in a first direction are arranged at a pitch of P _1, but in a second direction is a two-dimensional arrangement which are arranged at a pitch of P _2, optionally The light deflection element 12 is removed. The light deflection element 12 that can be removed is indicated by a black circle 12A.
That is, when there is no light deflection element 12 to be removed, the arrangement is exactly the same as the arrangement of the light deflection elements 12 shown in FIG. 2, and the light deflection elements 12 are regularly arranged. However, by removing the light deflection elements 12 arbitrarily selected as the black circles 12A, a pseudo irregular arrangement can be obtained. By arbitrarily removing the light deflection element 12, moire interference fringes with the concealment structure 14, the light collecting sheet 20, and the like, which are other optical members described later, disposed on the exit surface 10 a side of the light guide plate 10 are suppressed. I can do it.
Thus, at the appropriate removal of the light deflection elements 12 regions, the arrangement pitch in the first direction is set as an integer (n) times of P1, the arrangement pitch in the second direction is set at an integer (m) times P ₂ Can be done. Here, n and m are set to arbitrary integers in the range of 1 to 10. If n and m exceed 10, the distance between the deflecting elements 12 becomes too large, which is visually recognized as unevenness of light intensity, which is not desirable.

In the illuminating device 3 according to the present embodiment, a concealing structure 14 is disposed so as to face the exit surface 10 a of the light guide 10. As shown in FIG. 4, the concealment structure 14 is formed by smoothly connecting a rounded top portion and a curved side surface to the first main surface 15a on the light emitting surface side of the light-transmitting sheet-like base material 15. A plurality of convex lenticular lenses 16 each having a convex curved surface extending in one direction are arranged in the same direction.
In the example shown in FIG. 4, microlenses 17 are dispersedly provided on the second main surface 15 b that is the light incident surface of the base material 15. Since the light emission surface 10a of the light guide 10 is generally a flat surface, the microlens 17 is provided on the second main surface 15b of the concealment structure 14 so that the light guide 10 and the concealment structure 14 are in close contact with each other. Can be prevented. Further, the second main surface 15b may be roughened, and in the case of roughening, the microlens 17 may not be provided.

FIG. 5 is a longitudinal sectional view of the hiding structure 14. The angle formed between the tangent S drawn to an arbitrary point on the curved side surface of the convex lenticular lens 16 and the first main surface 15a gradually increases as the contact moves from the top of the convex lenticular lens 16 toward the first main surface 15a. . Accordingly, the angle formed between the tangent S of the curved side surface of the first main surface 15a and the first main surface 15a is the largest angle, and when this angle is defined as the tangent angle α, the tangent angle α is expressed by the following equation (1). It is prescribed.
In Equation (1), P ₁ is the pitch at which the above-described light deflection elements 12 are arranged in the first direction, and P ₂ is the pitch at which the light deflection elements 12 are also arranged in the second direction. The light guide plate 10 and the convex lenticular lens 16 are arranged so that the direction in which the convex lenticular lens 16 extends and the first direction in which the light deflection elements 12 are arranged are substantially parallel.

但し、ｎ_０、：導光体の屈折率
ｔ：導光体の厚み
ｎ_１：凸レンチキュラーレンズ１６の屈折率
θ_ｉ：隠蔽構造体１４へ入射する光の入射角

However, n ₀ ,: Refractive index of light guide t: Thickness of light guide n ₁ : Refractive index of convex lenticular lens 16 θ _i : Incident angle of light incident on concealment structure 14

The expression (1) will be described in more detail with reference to FIG. In FIG. 6, for simplicity of explanation, the second main surface 15 b is a flat surface and the microlens 17 is omitted.
On the light deflection surface 11 of the light guide plate 10, the light deflection elements 12 are arranged at a pitch of P2 in the _second direction. Of the incident light incident on the light guide plate 10 from the light source 9, the light incident on the light deflecting element 12 is reflected by the light deflecting element 12 to change its path. Of the light reflected by the light deflection elements 12, the light emitted reaches to the light exit plane 10a of the distance P _2/2 only the light guide plate 10 at a distance from the reflection point of the light deflecting element 12 is L when the incident angle theta _i of the second main surface 15b of the concealed structure 14 is determined from the distance _P 2/2 about (1) by the refractive index of the light guide plate 10 _{n 0} and thickness t and the light L .
Equation (1) defines the tangential angle α of the convex lenticular lens 16 necessary for refracting the light incident on the concealment structure 14 at the incident angle θ _i in the front direction.

The convex lenticular lens 16 has a convex curved surface forming a cross section formed smoothly with a rounded top and a curved side surface. The angle of the tangent S at the top with respect to the first major surface 15a is 0 degree, and the tangent angle of the tangent S at the contact point with the first major surface 15a is α. The tangent angle increases as the position of the tangent S shifts from the top to the first main surface 15a.
Accordingly, assuming that a point light source that emits substantially Lambertian light is installed from the second main surface 15b side of the concealing structure 14 in which a large number of convex lenticular lenses 16 are arranged, the first main surface 15a side of the concealing structure 14 When a point light source is observed, the light source is visually recognized as a linear light source.
Of the light whose direction is changed in all directions by the light deflection element 12 formed on the light deflection surface 11 of the light guide plate 10, the light distribution of the light emitted from the light emission surface 10a of the light guide plate 10 is Lambert light. Can be treated as synonymous with a point light source.

  That is, for example, when each of the plurality of circular light deflection elements 12 as shown in FIG. 2 or FIG. 3 is viewed as a point light source, the concealment in which the convex lenticular lenses 16 are arranged on the light exit surface 10a side of the light guide plate 10 When the structure 14 is disposed and observed from the first main surface 15a side, the dotted light deflecting elements 12 appear to expand linearly. At this time, if the tangent angle α at the contact point with the first main surface 15a of the convex lenticular lens 16 satisfies the expression (1), the adjacent light deflection elements 12 appearing to expand linearly as shown in FIG. Therefore, the concealability of the light deflection element 12 is improved.

The convex lenticular lens 16 that improves the concealing property of the light deflection element 12 will be described using the configuration shown in FIG. Here, the point light source 9A that emits approximately Lambertian light from one point is disposed on the second main surface 15b side of the concealing structure 14 so that the main axis of the emitted light substantially coincides with the normal direction of the second main surface 15b. Arranged. At this time, the light emitted from the first main surface 15a in the normal direction of the first main surface 15a is converted into linear light that extends in the arrangement direction of the convex lenticular lenses 16 around the point light source 9A.
Here, in FIG. 8, only the light refracted in the normal direction of the first major surface 15a by the convex lenticular lens 16 is illustrated. Although not shown in FIG. 8, the light emitted from the convex lenticular lens 16 includes not only light in the normal direction but also light emitted in an oblique direction with respect to the first main surface 15a.
Here, as shown in FIG. 8, it is desirable that the peak luminance position of the linear light emitted from the convex lenticular lens 16 is a luminance distribution indicated by the solid line in the figure, which is directly above the point light source 9A. Therefore, it is desirable to arrange a convex lenticular lens 16 that exhibits such a luminance distribution.
Alternatively, in FIG. 8, the peak luminance position of the linear light emitted from the convex lenticular lens 16 may be set to exhibit a luminance distribution indicated by a one-dot chain line that exists on both sides immediately above the point light source. In this case, _{L 0} directly above the brightness of the point light source 9A, when the peak luminance was _{L 1,} disposing the L 1 / _{L 0} is convex lenticular lens 16 having a shape such that 200% or less than 100% It is desirable.

The convex lenticular lens 16 in which the peak luminance position does not exist immediately above the point light source 9A and L ₁ / L ₀ exceeds 200% can be achieved even if the point light source 9A can be extended to a linear light source. The position looks very shining. As an extreme example, a triangular prism lens can be presented. Using a lens sheet in which triangular prism lenses are arranged instead of the convex lenticular lens 16 on the first main surface 15a of the hiding structure 14, the point light source 9A is disposed on the second main surface 15b side in the same manner as described above.
When this illumination device is observed from the first main surface 15a side of the concealing structure 14, the point light source 9A can only observe an image of light divided into two point light sources. Such a concealing structure 14 does not improve the concealing property of the light deflection element 12 even if it is disposed on the light guide plate 10.
Therefore, when the peak luminance is directly above the point light source 9A or the peak luminance is on both sides other than directly above the point light source, the ratio between the peak luminance and the luminance directly above the point light source 9A is 100% or more and 200% or less. Thus, the concealment structure 14 formed with the convex lenticular lens 16 in which light linearly spreads is desirable in order to improve the concealability of the light deflection element 12.

The shape of the convex lenticular lens 16 that can exhibit the functions as described above is defined by the following equation (2).
Here, the following expression (2) is an expression when the unit lens pitch of the convex lenticular lens 16 is normalized to 1. The convex curved surface shown in FIG. 9 shows the cross-sectional shape of the unit lens of the convex lenticular lens 16, and satisfies the definition of the formula (2). In the equation (2), z is a position function in the height direction of the convex lenticular lens 16, and r is a position variable in the width direction.
In FIG. 9, the hatched portion is the shape of the convex lenticular lens 16 alone. Here, the convex curved surface shape of the convex lenticular lens 16 defined by the expression (2) may be enlarged or reduced in the height direction or the width direction of the convex lenticular lens 16 as fine adjustment. In the expression (2), when the values of the coefficients k, 1 / R, A, B, and C do not fall within the set value range, the effect of linearizing the point light source as described above cannot be obtained. Or it is not desirable because the light collecting effect is lowered.

The shape of the convex lenticular lens 16 will be described in more detail with reference to FIG.
FIG. 10 is a cross-sectional view of the convex lenticular lens 16. The pitch of the convex lenticular lens 16 is PL ₁ , the height is TL ₁ , the tangent angle α of the tangent S with the first main surface 15 a, and the top fitting curvature radius is RL ₁ .
Here, the top fitting radius of curvature RL ₁ represents the radius of curvature of the top of the convex lenticular lens 16 having an aspherical shape. In this embodiment, the top fitting radius of curvature RL ₁ is defined as being formed in a width region of 10% with respect to the unit lens pitch PL ₁ .
Further, it is desirable that the top fitting curvature radius RL ₁ is less than ½ the unit lens pitch PL ₁ . That is, it is desirable that the aspherical lens shape has a smaller radius of curvature at the top than the spherical lens. Thereby, a condensing performance increases.
On the other hand, if the curvature radius PL ₁ at the top of the convex lenticular lens 16 is too small, the unit lens height TL ₁ becomes a very large aspherical shape, and the concealing performance of the light deflection element 12 is lowered, which is not desirable. The top fitting radius of curvature RL ₁ is desirably 0.1 or more with respect to the unit lens pitch PL ₁ .
The unit lens height TL ₁ is desirably 0.3 or more and less than 1.0 with respect to the unit lens pitch PL ₁ . If it is lower than 0.3, the light collecting performance is low. On the other hand, if it is 1.0 or more, not only the light collecting performance but also the concealing performance of the light deflecting element 12 is low.

In the display device 1 shown in FIG. 1, a concealment structure body 14 including a convex lenticular lens 16 determined by the above design is installed on a light guide plate 10, and a condensing sheet 20 and a polarization reflection separation sheet 21 are further provided. They are arranged sequentially.
As shown in FIG. 1, the condensing sheet 20 has third linear lenses 23 arranged in parallel in the same direction on the first main surface 22a side, which is the exit surface of the sheet-like translucent substrate 22. It has substantially the same configuration as the conventional BEF. The incident surface facing the first main surface 22a of the light collecting sheet 20 is a second main surface 22b. The second main surface 22b may be a flat surface or a roughened surface. Or the microlens 17 similar to what was formed in the 2nd main surface 15b of the concealment structure 14 may be provided in the 2nd main surface 22b, and it may be further roughened.
The third linear lens 23 is preferably a highly condensing lens, for example, a triangular prism lens 23 having an apex angle in the range of 70 degrees to 110 degrees. The top of the triangular prism lens 23 may be rounded, and the rounded range is preferably 20% or less of the unit pitch of the triangular prism lens 23, and more preferably 10% or less. This is because the light condensing performance of the triangular prism lens 23 is greatly impaired when it is rounded exceeding 20%.

Further, the third linear lens 23 may be a curved prism lens 23 in which both side surfaces of the triangular prism lens are convexly curved. The curved prism lens 23 further improves the concealability of the light deflecting element 12 while increasing the front luminance in order to achieve both high light condensing properties and diffusibility.
As the curved side surface of the curved prism lens 23, it is desirable that the angle formed between the tangent line at each point of the curved side surface and the first main surface 22a of the condensing sheet 20 changes in the range of 20 degrees to 70 degrees, and more desirably. Is in the range of 30 to 60 degrees. When the angle between the tangent and the first main surface 22a is less than 20 degrees, both the diffusion performance and the light collection performance are weakened, and when it exceeds 70 degrees, the light collection performance is lowered although the diffusion performance is strong.

In the display device 1 according to the present embodiment, the convex lenticular lens 16 constituting the concealing structure 14 and the triangular prism lens 23 constituting the condensing sheet 20 are preferably arranged in a substantially orthogonal direction (see FIG. 1). ). In particular, when the display device 1 is viewed from the observer side, it is desirable that the triangular prism lenses 23 are arranged in the vertical visual field direction of the screen and the convex lenticular lenses 16 are arranged in the horizontal visual field direction.
In general, the display device 1 is desired to have a certain range of vertical field of view and horizontal field of view, but particularly when the large display device 1 is used as a television, it is desired that the horizontal field of view is wide. The triangular prism lens 23 narrows the field of view because of its high light collecting performance. On the other hand, the convex lenticular lens 16 can achieve both diffusion performance and light collection performance. Therefore, by arranging the convex lenticular lenses 16 in the horizontal visual field direction, the horizontal visual field is condensed without extremely narrowing, and by arranging the triangular prism lens 23 in the vertical visual field direction, the vertical visual field becomes narrow, but high The light condensing effect can be exhibited.

As shown in FIG. 2, the light deflection elements 12 formed on the light deflection surface 11 of the light guide plate 10 in the display device 1 according to the present embodiment are disposed at the pitch P1 in the _first direction, and the second It is formed by a two-dimensional array structure disposed at a pitch P ₂ in the direction. At this time, it is desirable that the ratio between the pitches P ₁ and P ₂ is in a range defined by the following expression (3).
1.0 <P ₂ / P ₁ <3.0 (3)
Moreover, it is further desirable that the extending direction of the convex lenticular lens 16 formed on the first main surface 15a of the concealing structure 14 substantially coincides with the first direction in which the light deflection element 12 is disposed. As shown by the equation (3), the light deflection elements 12 are arranged so that the arrangement pitch P _{2 in} the second direction is larger than the arrangement pitch P ₁ in the first direction. Therefore, when the extending direction of the convex lenticular lens 16 substantially coincides with the first direction, as shown in FIG. 7, the light deflection element 12 extends in the second direction and is observed as a line. As a result, concealment is improved.

Furthermore, it is desirable that the ratio between the pitch P ₁ in the first direction and the pitch P _{2 in} the second direction is in a range defined by the following equation (4). Most preferably, a triangle formed by connecting three adjacent light deflecting elements 12 as apexes is configured in a hexagonal arrangement that is a substantially equilateral triangle. By making the arrangement configuration of the light deflection elements 12 close to a hexagonal arrangement, the distances between the light deflection elements 12 are uniformly different in the longitudinal direction, the lateral direction, and the oblique direction in the plane of the light deflection surface 11. This is because the unevenness is easily uniformed.
1.4 <P ₂ / P ₁ <2.2 (4)

As described above, the extending direction of the convex lenticular lens 16 constituting the concealing structure 14 with respect to the light deflecting element 12 disposed on the light deflecting surface 11 is the first direction in which the light deflecting elements 12 are arranged. To be linear in the second direction substantially orthogonal to the first direction.
Therefore, it is desirable that the first direction in which the light deflection element 12 is arranged substantially coincides with the vertical direction of the display device 1. By doing so, since the extending direction of the convex lenticular lens 16 substantially coincides with the vertical direction of the screen of the display device 1 and is arranged in the horizontal direction, it can be condensed without extremely narrowing the horizontal visual field. .

On the other hand, when the first direction in which the light deflection elements 12 are arranged on the light deflection surface 11 substantially coincides with the horizontal direction of the display device 1, the convex lenticular lens 16 constituting the concealing structure 14 extends. The direction is preferably substantially parallel to the first direction in which the light deflection elements 12 are arranged.
Since the arrangement pitch P ₂ in the second direction is larger than the arrangement pitch P ₁ in the first direction, the convex lenticular lens is set so as to be in the direction of linearizing the light deflection elements 12 with respect to the second direction. It is desirable that the 16 extending directions substantially coincide with the first direction.

At this time, it is desirable that the third linear lens 23 constituting the condensing sheet 20 extends substantially orthogonal to the convex lenticular lens 16 constituting the concealing structure 14. In this case, since the third linear lens 23 extends in the vertical direction and collects the horizontal field of view of the display device 1, the third linear lens 23 has not only a condensing performance but also a field of view. It is important to choose a lens shape that does not narrow.
For example, the third linear lens 23 may have the same shape as the convex lenticular lens 16 constituting the concealing structure 14, or a lens having a convex curved surface of another shape determined from the equation (2). Also good. Alternatively, the third linear lens 23 is formed by extending a rounded triangular prism lens, a triangular prism lens having an apex angle of about 100 degrees to 120 degrees, and the like in a vertical direction without narrowing the field of view. It can be used as a lens that can obtain light collecting performance.

Further, the third linear lens 23 constituting the condensing sheet 20 and the convex lenticular lens 16 constituting the concealing structure 14 may be disposed substantially in parallel. At this time, if the pitch between the third linear lens 23 and the convex lenticular lens 16 is approximately the same, moire interference fringes are generated, which is not desirable.
For this reason, the pitch ratio between the third linear lens 23 and the convex lenticular lens 16 is set to a ratio that is at least greater than 1: 2, preferably greater than 1: 3, and is set to a pitch at which moire interference fringes are most unlikely to occur. Is desirable. Furthermore, the third linear lens 23 and the convex lenticular lens 16 may be arranged so as to cross each other at an angle of several degrees. The tilting range is preferably more than 0 degree and 20 degrees or less, and more preferably 10 degrees or less. Inclination exceeding 20 degrees is not desirable because the visual field distribution of the display device 1 becomes distorted.

In addition, a polarization reflection separation sheet 21 is disposed at a position facing the first main surface 22a that is the light emission surface of the light collecting sheet 20. The polarization reflection separating sheet 21 is a reflective polarizer having a multilayer thin film structure such as DBEF, a wire grid structure, or a structure using a birefringent material typified by liquid crystal, and the polarizing plate 5 constituting the image display element 2. Is a film material that has a linearly polarized light transmission axis in a direction substantially coincident with the other, reflects the other linearly polarized light, and exhibits a brightness enhancement effect, and further preferably has a diffusion layer.
The light transmitted through the condensing sheet 20 is transmitted through the image display element 2 through the polarization reflection separating sheet 21, so that a horizontal viewing angle by diffusion of the transmitted image and high luminance by condensing can be ensured.

The image display element 2 is a liquid crystal display element configured by sandwiching a liquid crystal panel 7 between a pair of polarizing plates 5 and 6. The image display element 2 is preferably an element that displays an image by transmitting / blocking light in pixel units. If the image is displayed by transmitting / blocking light in pixel units, the luminance of the image emitted to the observer side F by the illumination device 3 is improved, and the viewing angle dependency of the light intensity is reduced. Furthermore, it is possible to display an image with high image quality by effectively using the light whose visibility of the light deflection element 12 is reduced.
A liquid crystal display element is a typical element that transmits / shields light in pixel units and displays an image, and can improve image quality and reduce manufacturing cost compared to other display elements. Can do. Therefore, the image display element 2 is preferably a liquid crystal display element.

As described above, according to the display device 1 and the illumination device 3 according to the present embodiment,
Since the convex lenticular lenses 16 of the concealment structure 14 are arranged in the same direction as the first direction of the light deflection element 12 arranged on the light deflection surface 11 of the light guide 10, the image of the light deflection element 12 is optically deflected. Since the light is diffused and linearized in a second direction orthogonal to the first direction of the element 12, the image of the light deflection element 12 can be concealed and cannot be visually recognized from the observer side. In addition, when the light deflection element 12 is concealed, it is not necessary to dispose a diffusion sheet having almost no light collecting function, so that it is possible to suppress a decrease in luminance.
Further, the convex lenticular lens 16 of the obscuring structure body 14 has a tangential angle α satisfying the expression (1) and a convex lenticular lens 16 having a convex curved surface defined by the expression (2). Since it extends in the horizontal direction and is arranged in the horizontal direction, a sufficient viewing angle can be exhibited without narrowing the viewing angle in the horizontal direction.
Furthermore, since the triangular prism lenses 23 are arranged in the direction substantially orthogonal to the convex lenticular lens 16 as the condensing sheet 20, the spread of the viewing angle in the vertical direction is suppressed, but it is high in combination with the convex lenticular lens 16. Brightness can be demonstrated. Therefore, particularly when used for a medium-sized or large-sized liquid crystal display device or the like, it is preferable because a sufficient horizontal viewing angle and high luminance can be secured.

  The present invention is not limited to the first embodiment described above, and appropriate changes, additions, and deletions can be made without departing from the spirit of the present invention. Next, modified examples and other embodiments of the present invention will be described with reference to the accompanying drawings, but the same or similar parts and members as those of the above-described embodiments will be described using the same reference numerals.

First, a modified example of the arrangement configuration of the light deflection element 12 and the concealment structure 14 in the illumination device 3 according to the present invention will be described.
The display device 1 in the first modification is configured such that the first direction in which the light deflection elements 12 provided on the light deflection surface 11 are arranged substantially coincides with the horizontal direction of the display device 1. In this case, it is desirable that the extending direction of the convex lenticular lens 16 constituting the concealing structure 14 is substantially parallel to the second direction in which the light deflection elements 12 are arranged.
The third linear lens 23 constituting the condensing sheet 20 is preferably substantially orthogonal to the convex lenticular lens 16 constituting the concealing structure 14.
By setting it as such a structure, the brightness | luminance to a front direction can be improved most, without narrowing the horizontal visual field direction of the display apparatus 1. FIG.

However, in this case, since the convex lenticular lens 16 constituting the concealing structure 14 linearizes the light deflection element 12 in the first direction, the pitch in the second direction larger than the pitch P _{1 in the first} direction. can not be linearized P _2, shielding property is lowered. At this time, since the extending direction of the third linear lens 23 constituting the light collecting sheet 20 substantially coincides with the first direction, the third linear lens 23 is effective in enhancing the concealing property. is there.
Accordingly, the third linear lens 23 may have a triangular prism lens shape as shown in FIG. 1, but it is more preferable that the top portion is rounded or a prism lens shape having a curved side surface. The most preferable shape is a lenticular lens shape having a convex cross-section with a curved top and side surfaces, but can be appropriately selected from the concealment performance and light collection performance required for the display device 1.

Next, a modified example of the hiding structure 14 will be described.
The concealment structure 14 according to the present embodiment includes a convex lenticular lens 16 as the first linear lens 16 on the first main surface 15 a, and further includes a second in a direction substantially orthogonal to the first linear lens 16. The linear lens 25 may be provided. This will be described with reference to FIG. 11 as a first modification.
In the concealment structure 14 according to the first modification shown in FIG. 11, a plurality of second linear lenses 25 are arranged in a substantially orthogonal direction so as to fill a gap between two adjacent first linear lenses 16. Yes. A triangular prism lens is disclosed as the second linear lens 25. Note that the height of the second linear lens 25 from the first major surface 15 a is lower than the height of the first linear lens 16.

According to this configuration, the concealability of the image of the light deflection element 12 can be enhanced by the first linear lens 16 and the light condensing property in the front direction can be enhanced by the second linear lens 25.
However, when the ratio of the second linear lens 25 to the area of the first main surface 15a in the base material 15 of the concealing structure 16 increases, the concealing property by the first linear lens 16 is deteriorated. Therefore, it is necessary to appropriately select the occupation ratio of the first linear lens 16 and the second linear lens 25 based on the concealment performance and light condensing performance necessary for the display device 1 according to the present embodiment. The ratio of the second linear lens 25 to the area of the first major surface 15a is desirably 60% or less, and more desirably 30% or less.

Next, the concealment structure 14 according to the second modification will be described with reference to FIG.
As in the first modification, the concealing structure 14 includes a plurality of second linear lenses 26 in a substantially orthogonal direction so as to fill a gap between two adjacent first linear lenses 16 (convex lenticular lenses). It is arranged. The second linear lens 26 has a lenticular lens shape having a convex curved surface.
According to the second modification, the light deflection element 12 formed on the light deflection surface 11 of the light guide 10 is linearized in the second direction by the first linear lens 16, and the second line The lens 26 can be linearized in the first direction, and the concealing property is further improved.
The lenticular lens 26 formed by the second linear lens 26 may have the same shape as the first linear lens 16 or may have a relatively small lens shape similar to the first linear lens 16. Alternatively, the lens shape may be completely different from that of the first linear lens 16, but when the pitch P2 in the _second direction of the light deflection element 12 is replaced with the pitch P1 in the _first direction in the equation (1). It is desirable to have a tangent angle greater than or equal to the required tangent angle α.

Next, the concealment structure 14 according to the third modification and the fourth modification will be described with reference to FIGS.
In the concealment structure 14 shown in FIG. 13, a plurality of substantially hemispherical microlenses 27 are disposed in the gap between the adjacent first linear lenses 16. Alternatively, as in the fourth modification shown in FIG. 14, the first linear lenses 16 including the convex lenticular lenses 16 are arranged in close contact with each other in the same direction, and the first linear lenses 16, 16 are arranged. Microlenses 28 may be formed so as to cover the valleys between them.
These microlenses 27 and 28 have a feature of diffusing light in all directions of the convex curved surface and condensing light in all directions.

Therefore, according to the concealment structure 14 according to the third and fourth modified examples, the optical deflection element 12 formed on the optical deflection surface 11 by the first linear lens 16 is linearized in the second direction, and the micro Concealment is improved by diffusing light in all directions by the lenses 27 and 28. On the other hand, the first linear lens 16 can exhibit light condensing properties in one direction, and the micro lenses 27 and 28 can exhibit light condensing properties in all directions.
When the concealment structure 14 has a configuration in which the first linear lens 16 and the microlenses 27 and 28 are combined, the first linear lens 16 is partially applied as in the fourth modification shown in FIG. It is preferable to adopt a configuration in which the microlens 28 is formed so as to cover the surface. According to this configuration, not only optical characteristics such as concealing property and light collecting property can be obtained, but also the abrasion resistance is improved by the microlenses 28 arranged in a dot shape.

  Here, the ratio of the microlenses 27 and 28 to the area of the first main surface 15a of the concealment structure 14 is desirably 3% or more in order to obtain sufficient abrasion resistance, and further concealment. In order to enhance the properties, it is desirable that the content is 10% or more. On the other hand, when the area occupied by the microlenses 27 and 28 increases, there is a problem that the concealing effect due to the linearization of the light deflection element 12 by the first linear lens 16 is reduced. Therefore, the area occupied by the microlenses 27 and 28 is desirably 60% or less, and more desirably 40% or less.

Although the lighting device 3 and the display device 1 according to the first embodiment of the present invention have been described in detail above, particularly the concealing structure 14, the configurations of the lighting device 3 and the display device 1 are not limited to the configuration shown in FIG. .
That is, in the first embodiment, the lighting device 3 in which the concealment structure 14 is disposed on the light guide plate 10 and the light collecting sheet 20 and the polarization separation reflection sheet 21 are disposed thereon has been described. The invention is not limited to such a configuration. In particular, in the concealment structure 14, the concealability and light condensing performance are improved by disposing the second linear lens 25 in a direction orthogonal to the first linear lens 16.
In this way, the light collecting sheet 20 can be omitted by adding the second linear lens 25. Alternatively, the polarization separation / reflection sheet 21 may be omitted or replaced with a general diffusion sheet.
In addition, as a general example of the light guide plate 10, the case where the light guide plate 10 is a transparent plate and the light emission surface 10 a is substantially flat has been described. For the purpose of improving the efficiency of the light guide plate 10 or eliminating unevenness, for example It is not deviated from the gist of the present invention to disperse and arrange the diffusing particles inside the optical plate 10 or to provide the light exit surface 10a with an uneven shape.

In the concealment structure 14 according to the present embodiment, the first linear lens 16, the second linear lenses 25 and 26, the microlenses 27 and 28 provided on the first main surface 15 a of the translucent substrate 15, The microlens 17 provided on the second main surface 15b is molded using the following material. The material is, for example, UV curable resin, radiation curable resin, PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), COP (cycloolefin polymer), PAN (polyacrylonitrile copolymer), AS (acrylonitrile). Styrene copolymer).
The concealment structure 14 is integrally formed using these materials by an extrusion molding method, an injection molding method, or a hot press molding method well known in the art. Alternatively, the translucent substrate 15 may be molded by the above molding method, and each lens may be molded by a UV curing method or a radiation curing method using a UV curable resin or a radiation curable resin. The condensing sheet 20 can also be produced by the same manufacturing method as the concealing structure 14.

Next, the display device 30 and the illumination device 31 according to the second embodiment of the present invention will be described. Here, the same or similar parts and members as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.
FIG. 15 is a schematic cross-sectional view of the display device 1 according to the second embodiment of the present invention. The display device 30 according to the second embodiment includes an image display element 2 and a lighting device 31.
In the illumination device 31, the light source 9, the light guide plate 10, and the concealment structure 14 are the same as those in the first embodiment described above, and are different in the light collecting sheet 32. The condensing sheet 32 disposed in the illuminating device 31 is arranged on the first main surface 22 a of the translucent substrate 22 in a direction substantially orthogonal to the third linear lens 33 and the third linear lens 33. And a fourth linear lens 34 formed.

  As shown in FIG. 16, the condensing sheet 32 includes a plurality of trapezoidal prism lenses 33 having a trapezoidal cross section extending in one direction as a third linear lens 33 on the first main surface 22 a of the substrate 22. They are arranged in parallel. On the top of the trapezoidal prism lens 33, a plurality of triangular prism lenses 34 having a cross-sectional triangle are formed in parallel as a fourth linear lens 34 in a direction substantially orthogonal to the direction in which the trapezoidal prism lens 33 is disposed. A group of the plurality of triangular prism lenses 34 arranged on the top of the trapezoidal prism lens 33 is referred to as a fourth linear prism array 34A.

FIG. 17 shows the condensing sheet 32, where (a) is a cross-sectional view orthogonal to the longitudinal direction of the trapezoidal prism lens 33, and FIG. 17 (b) is a cross-sectional view orthogonal to the longitudinal direction of the triangular prism lens 34. FIG. 17C is a top view of the light collecting sheet 32.
As shown in FIG. 17, the trapezoidal prism lens 33 and the triangular prism lens 34 are arranged substantially orthogonally, but the crossing angle range of the lenses 33 and 34 is not limited to 90 degrees, but 70 degrees. It can be selected within a range of ˜110 degrees. If the angle is out of this angular range, the viewing angle characteristic of the display device 30 is distorted in an oblique direction, which is not desirable.
Also, the top width L ₃ of the trapezoidal prism lens 33 can be arbitrarily selected according to desired optical properties. Intensified optical performance of the trapezoidal prism lens 33 Reducing the top width L _3, the optical performance of the triangular prism lens 34 is increased by increasing the top width L ₃ in reverse. According to the optical characteristic which the display apparatus 30 calculates | requires, the effect by the combination with other optical sheets, such as the concealment structure 14, can also be selected suitably.

The trapezoidal prism lens 33 which is the third linear lens 33 of the condensing sheet 32 has an apex angle set in a range of 70 degrees to 110 degrees, and a unit pitch is arranged in PL ₃ (FIG. 17A). reference). On the other hand, the fourth linear lens 34 has an apex angle in the range of 70 to 110 degrees and a unit pitch of PL ₄ (see FIG. 17B).
And the ratio between the unit pitch PL ₄ units pitch PL ₃ and the triangular prism lens 25 of the trapezoidal prism lens 33,
0.05 ≦ PL ₄ / PL ₃ ≦ 2.0 (5)
It is desirable that

Here, the apex angle of the trapezoidal prism lens 33 for example 70 °, when the apex angle of the triangular prism lens 34 and 110 degrees, the pitch PL ₄ of the unit triangular prism lens 34 is pitch PL ₃ of the unit trapezoidal prism lens 33 If it exceeds twice, the height of the triangular prism lens 34 becomes higher than the height of the trapezoidal prism lens 33, and the effect of the triangular prism lens 34 disappears. Therefore, it is desirable that PL ₄ / PL ₃ is 2 or less.
Further, when the pitch PL ₄ of the triangular prism lens 34 is smaller than the pitch PL ₃ of the trapezoidal prism lens 33, the luminance and the half-value angle are not a problem, but for example, when the pitch PL ₄ of the triangular prism lens 34 is 20 μm, When PL ₄ / PL ₃ is 0.05, the pitch PL ₃ of the trapezoidal prism lens 33 is 400 μm. When the pitch PL ₃ of the trapezoidal prism lens 33 too large, since the Moire interference fringes are likely to occur between the periodic structure of the periodic structure and the trapezoidal prism lens 33 of the image display device 2, not desirable.
However, reducing the pitch PL ₃ of the unit lenses constituting the third linear lens 33, the pitch PL ₄ of the unit lenses constituting the fourth linear lens 34 becomes too small, undesirably. Therefore, it is desirable that PL ₄ / PL ₃ is 0.05 or more.

More preferably, the apex angle of the trapezoidal prism lens 33 and the apex angle of the triangular prism lens 34 constituting the condensing sheet 32 are in the range of 80 degrees to 100 degrees. In this case, a unit pitch PL ₃ of the trapezoidal prism lens 33, the ratio _PL 4 / PL ₃ between the unit pitch PL ₄ of the triangular prism lens 34, for the same reason as described above,
0.05 ≦ PL ₄ / PL ₃ ≦ 1.4 (6)
It is desirable to be in the range. More preferably,
0.05 ≦ PL ₄ / PL ₃ ≦ 1.0 (7)
Range. Since the triangular prism lens 34 formed on top of the trapezoidal prism lens 33, it is desirable unit pitch PL ₄ of the triangular prism lens 33 is equal to or a unit pitch PL ₃ of the trapezoidal prism lens 33 is less.

Next, the concealment property of the light deflection element 12 by the light collecting sheet 32 will be described.
In general, it is known that the triangular prism lens shape splits the light of one point light source into two. The light collecting sheet 32 according to the present embodiment includes a trapezoidal prism lens 33 as the third linear lens 33, and a plurality of triangular prism lenses 34 are arranged as the fourth linear lens 34 on the top of the trapezoidal prism lens 33. Has a structured. Therefore, the split effect by the trapezoidal prism lens 33 and the split effect by the triangular prism lens 34 can exhibit the effect of splitting the light of one point light source (light deflection element 12) in four directions.
On the other hand, the concealment is improved by linearizing the image of the light deflection element 12 formed on the light deflection surface 11 of the light guide plate 10 by the concealment structure 14 disposed on the light exit surface side of the light guide plate 10. Further, by concentrating the light, that is, the image of the light deflecting element 12 in four directions by the condensing sheet 32 having the two-dimensionally arranged prism lens configuration including the trapezoidal prism lens 33 and the triangular prism lens 34 described above, the concealing property is achieved. Further improvement.

Next, modified examples of the light collecting sheet 32 in the second embodiment described above will be described with reference to FIGS.
FIG. 18 shows a condensing sheet 32 according to the first modification, in which the third linear lens 36 is a triangular prism lens, and the fourth linear lens 37 is also a triangular prism lens. The shaped lenses 36 and 37 are formed at the same height and substantially orthogonally. With this configuration, an inverted pyramid-shaped concave mold 38 is formed in a space partitioned by the third and fourth linear lenses 36 and 37.

In the condensing sheet 32 according to the second modification shown in FIG. 19, the third linear lens 40 is a triangular prism lens, and the fourth linear lens 41 is also a triangular prism lens. The fourth linear lens 41 is disposed in the gap between the third linear lenses 40 arranged in parallel and spaced apart from each other on the first main surface 22a in a direction substantially orthogonal to the fourth linear lens. A plurality of lenses 41 are arranged in parallel with the extending direction of the third linear lens 40.
Moreover, the fourth linear lens 41 is formed lower than the height of the third linear lens 40. However, in this modification, it is not limited to such a structure, For example, the 3rd linear lens 40 and the 4th linear lens 41 may be formed in the same height.

  In the light collecting sheet 32 according to the third modification shown in FIG. 20, convex lenses 43 each having a substantially regular quadrangular pyramid are arranged in close contact with the first main surface 22 a of the substrate 22. The unit convex lens 43 is formed in a pyramid shape.

  In the condensing sheet 32 according to the fourth modification shown in FIG. 21, the third linear lens 45 has a lenticular lens shape having a convex curved surface having a substantially semicircular or semi-elliptical cross section, and the fourth line The lens 46 is a triangular prism lens having a triangular cross section. The third linear lens 45 is arranged in a direction substantially orthogonal to the fourth linear lens 46. Moreover, the fourth linear lens 46 is configured to be lower in height than the third linear lens 45 and arranged in parallel in the extending direction of the third linear lens 45.

In the illumination device 31 according to the second embodiment, the relationship between the obscuring structure 14 and the condensing lens 32 will be described. The first linear lens 16 (convex lenticular lens) formed on the obscuring structure 14 and the book. It is desirable that the third linear lens 45 (lenticular lens) formed on the light collecting sheet 32 according to the third modification is disposed in a substantially orthogonal direction.
If such a configuration is adopted, the first linear lens 16 of the concealing structure 14 extends the image of the light deflection element 12 formed on the light deflection surface 11 of the light guide plate 10 in the second direction to form a line. Since the third linear lens 45 of the light collecting sheet 32 extends the image of the light deflection element 12 in the first direction and linearizes it, the concealability of the light deflection element 12 can be improved.
And since the 4th linear lens 46 formed in the condensing sheet | seat 32 is a triangular prism lens, since condensing performance improves, it is desirable.

The condensing sheet 32 according to the fifth modification shown in FIG. 22 has a configuration opposite to that of the example shown in FIG.
In this condensing sheet 32, the third linear lens 48 is a triangular prism lens having a substantially triangular cross section, and the fourth linear lens 49 is a lenticular lens having a convex curved surface such as a semicircular or semi-elliptical cross section. is there. The third linear lens 48 is arranged in a direction substantially orthogonal to the fourth linear lens 49. Moreover, the fourth linear lens 49 is configured to be lower in height than the third linear lens 48 and arranged in parallel in the extending direction of the third linear lens 48.
Also in this case, similarly to the display device 1 including the condensing sheet 32 according to the fourth modification, the first linear lens 16 of the concealing structure 14 and the fourth linear lens 49 of the condensing sheet 32 Are arranged in a substantially orthogonal direction. As a result, the image of the light deflection element 12 is stretched in the first and second directions to be linearized, so that the concealability of the light deflection element 12 is improved.
Depending on the light distribution visual field characteristics required by the display device 1, the first linear lens 16 provided on the concealing structure 14 and the third linear lens 48 provided on the light collecting sheet 32 are in a direction substantially orthogonal to each other. It may be arranged.

Next, the light collection sheet 32 according to the sixth modification shown in FIG. 23 will be described.
The condensing sheet 32 shown in FIG. 23 shows a structure with the highest concealing property. That is, in the condensing sheet 32, the third linear lens 51 and the fourth linear lens 52 disposed on the first main surface 22a of the base material 22 in directions orthogonal to each other have a convex curved section. A lenticular lens shape is formed. The fourth linear lenses 52 are lower in height than the third linear lenses 51 and are arranged in the extending direction of the third linear lenses 51.
With this configuration, in the display device 1 according to the second embodiment, the image of the light deflection element 12 formed on the light deflection surface 11 of the light guide plate 10 is linearized in the first and second directions, respectively, and the concealment property is extremely high. Can be increased. Such a configuration is useful when it is desired to reduce the thickness t of the light guide plate 10 or to increase the arrangement interval of the light deflection elements 12.

Next, the light collection sheet 32 according to a seventh modification shown in FIG. 24 will be described.
The condensing sheet 32 shown in FIG. 24 has a third linear lens 54 formed in a lenticular lens shape having a convex curved section, and is arranged in close contact with and parallel to the first main surface 22a of the substrate 22. Yes. And it has the structure by which the micro lens 55 was disperse | distributed and arrange | positioned so that the valley between the adjacent 3rd linear lenses 54 and the 3rd linear lenses 54 might be covered.
According to the display device 1 according to the second embodiment including the condensing sheet 32 according to the seventh modified example, the microlens 55 increases the diffusibility in all directions, and the third linear lens 54 performs light deflection. The element 12 can be linearized in the second direction.
Further, even when the third linear lens 54 has a triangular prism lens shape, it is possible to reduce the generated side lobes.
The ratio of the microlens 55 to the area of the first main surface 22a of the condensing sheet 32 is desirably 3% or more. In particular, 25% or more is preferable in order to eliminate the side lobe caused by the third linear lens 55. 35% or more.

  As described above, according to the display device 30 according to the second embodiment of the present invention, the condensing sheet 32 disposed between the hiding structure 14 and the image display element 2 is replaced with a lens sheet having a two-dimensional array structure. Thus, the luminance in the front direction of the display device 1 can be improved, and the image of the light deflection element 12 formed on the light deflection surface 11 of the light guide plate 10 can be linearized and concealed.

  The illumination devices 3 and 31 and the display devices 1 and 30 according to the embodiments of the present invention have been described above. However, the illumination devices 3 and 31 of the present invention are applied only to the display devices 1 and 30 such as the image display element 2. It is not a thing. That is, it goes without saying that the illumination devices 3 and 31 having a function of efficiently condensing light emitted from the light source 9 can be used, for example, in illumination equipment.

Examples of the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.
Example 1
The display device 1 according to Example 1 was manufactured as follows.
First, a rectangular plate-shaped light guide plate 10 having a thickness of 4 mm was prepared, and was installed on each end face of four sides of the light guide plate 10 using LEDs as the light source 9. On the light deflection surface 11 of the light guide plate 10, a light deflection element 12 made of white reflective ink was formed into a circle by a printing method. The light deflecting elements 12 of white reflective ink are regularly distributed on the light deflecting surface 11, and the size is reduced as the position is closer to the end face where the light source 9 is installed, and the closer to the center of the light guide plate 10. The size was increased.
The arrangement direction of the light deflection elements 12 is the same as the first direction and the screen vertical direction (vertical direction) for observation of the display device 1, and the arrangement pitch P1 in the _first direction is about 1.35 mm. The arrangement pitch P2 in the _second direction orthogonal to the direction of is about 2.4 mm. A reflection sheet 13 is disposed on the light deflection surface 11 side of the light guide plate 10.

Next, the concealment structure 14 was produced based on the first embodiment shown in FIGS. 4 and 5. A polycarbonate resin was used as the material of the hiding structure 14. Since the polycarbonate resin has a high refractive index n ₁ of about 1.59, the concealing structure 14 with higher light collecting performance and diffusion performance can be obtained.
A convex lenticular lens was formed as the first linear lens 16 on the first main surface 15a by extrusion molding using a polycarbonate resin. The convex lenticular lens 16 is defined by the equation (2), and the unit pitch PL ₁ shown in FIG. 10 is 100 μm, the top fitting radius of curvature RL ₁ is 35 μm, and the unit lens height TL ₁ is 43 μm.

On the other hand, a plurality of microlenses 17 having a diameter of 100 μm and a height of 20 μm are provided on the second main surface 15b of the obscuring structure 14 in an area of about 4% in plan view with respect to the area of the second main surface 15b. It arrange | positioned at random so that it might become.
The direction in which the convex lenticular lens 16 extends coincides with the first direction in which the light deflection elements 12 are arranged, and the concealing structure 14 is placed on the light guide plate 10 so that they extend in the screen vertical direction of the display device 1. Arranged.
Moreover, it produced based on 1st embodiment shown in FIG. BEF (manufactured by 3M) is used as the condensing sheet 20, the extending direction of the triangular prism lens constituting the third linear lens 23, and the convex that is the first linear lens 16 arranged in the concealing structure 14. The illumination device 3 was manufactured by disposing the lenticular lens 16 so as to be orthogonal to the extending direction and further arranging DBEF (manufactured by 3M) as the polarization separation / reflection sheet 21.
The display device 1 was manufactured by disposing the liquid crystal panel 7 as the image display element 2 above the lighting device 3 thus obtained.
(Example 2)

(Example 2)
The display device 1 according to Example 2 was manufactured as follows.
First, a light guide plate 10 having a thickness of 4 mm was prepared and installed on each end face of the four sides of the light guide plate 10 using an LED as the light source 9. On the light deflection surface 11 of the light guide plate 10, white reflective ink was formed as a light deflection element 12 by a printing method. The light deflecting elements 12 are regularly arranged on the light deflecting surface 11, and the size is reduced as it is closer to the end surface where the light source 9 is installed, and the size is increased as it is closer to the center of the light guide plate 10. The arrangement direction of the light deflection elements 12 is such that the first direction coincides with the horizontal direction of the screen of the display device 1, the arrangement pitch P1 in the _first direction is about 1.35 mm, and the arrangement pitch P2 in the _second direction is set. The pitch was about 2.4 mm. A reflection sheet 13 is disposed on the light deflection surface 11 side of the light guide plate 10.

Next, the concealment structure 14 was produced based on the first embodiment shown in FIGS. 4 and 5. A polycarbonate resin was used as the material of the concealing structure 14, and a plurality of convex lenticular lenses 16 were arranged in close contact with each other as first linear lenses 16 on the first main surface 15a by extrusion molding. The convex lenticular lens 16 is defined by the equation (2). The unit pitch PL ₁ is 100 μm, the top fitting curvature radius RL ₁ is 35 μm, and the unit lens height TL ₁ is 43 μm.
On the other hand, a plurality of microlenses 17 having a diameter of 100 μm and a height of 20 μm are formed on the second main surface 15b of the concealment structure 14 in the plan view with respect to the area of the second main surface 15b. Were randomly distributed. The direction in which the convex lenticular lens 16 extends coincides with the first direction in which the light deflection elements 12 are arranged, that is, in the horizontal direction of the screen of the display device 1 so that the concealing structure 14 is placed on the light guide plate 10. Arranged.

Next, the condensing sheet 20 was produced based on the 2nd modification shown in FIG. Using a polycarbonate resin as the material of the light collecting sheet 20, a trapezoidal prism lens 33 having an apex angle of about 90 degrees is formed as a third linear lens 33 on the first main surface 22 a by extrusion molding. A plurality of triangular prism lenses 34 having apex angles of about 90 degrees are arranged in parallel at the top as fourth linear lenses 34.
A triangular prism lens 34 is arranged in a direction orthogonal to the trapezoidal prism lens 33, the unit pitch PL3 of the trapezoidal prism lens 33 is 70 μm, and the unit pitch PL4 of the triangular prism lens 34 is 25 μm. The trapezoidal prism lens 33 of the condensing sheet 32 and the convex lenticular lens 16 of the concealing structure 14 are arranged so as to be substantially orthogonal.
Further, DBEF (manufactured by 3M) was disposed as the polarized light separating / reflecting sheet 21 to manufacture the lighting device 3.
The display device 1 was manufactured by disposing a liquid crystal panel as the image display element 2 above the lighting device 3 obtained in this way.
(Example 3)

A display device 1 according to Example 3 was manufactured as follows.
First, a light guide plate 10 having a thickness of 4 mm was prepared, an LED was used as the light source 9, and each of the light guide plates 10 was installed on the end surfaces of the four sides of the light guide plate 10. On the light deflection surface 11 of the light guide plate 10, white reflective ink was formed as the light deflection element 12 by a printing method. The light deflection elements 12 are regularly distributed on the light deflection surface 11, and the size is reduced as the distance from the end surface on which the light source 9 is installed is increased, and the size is increased as the distance from the center of the light guide plate 10 is increased. The arrangement direction of the light deflection elements 12 is such that the first direction and the screen horizontal direction of the display device 1 coincide with each other, the arrangement pitch P ₁ in the first direction is about 1.35 mm, and the arrangement pitch P _{2 in} the second direction. The pitch was about 2.4 mm. A reflection sheet 13 is disposed on the light deflection surface 11 side of the light guide plate 10.

Next, the concealment structure 14 was produced based on the second modification shown in FIG. A polycarbonate resin is used as the material of the concealing structure 14, and the first main surface 15a is formed by extrusion molding on the first lenticular lens 16 as the first linear lens 16 and the apex angle is 90 degrees as the second linear lens 25. A triangular prism lens was formed. The convex lenticular lens 16 is defined by the equation (2). The unit pitch PL ₁ is 100 μm, the top fitting curvature radius RL ₁ is 35 μm, and the unit lens height TL ₁ is 43 μm.
A plurality of such convex lenticular lenses 16 are arranged parallel to each other with a distance of 40 μm, and triangular prism lenses 25 are arranged in the gap in a direction perpendicular to the convex lenticular lenses 16. The triangular prism lens 25 had a pitch of 20 μm and a height of 10 μm.

  On the other hand, a microlens 17 having a diameter of 100 μm and a height of 20 μm is randomly formed on the second main surface 15b of the obscuring structure 14 so that the area is approximately 4% of the area of the second main surface 15b. Distributed. The concealing structure 14 is placed on the light guide plate 10 so that the direction in which the convex lenticular lens 16 extends and the first direction in which the light deflection elements 12 are arranged coincide with each other in the horizontal direction of the screen of the display device 1. Arranged.

Next, the condensing sheet 20 was produced based on the modification of the condensing sheet 20 shown in FIG.
A polycarbonate resin is used as the material of the light collecting sheet 20, and a curved prism lens is formed on the first main surface 22a by extrusion molding as a third linear lens 23 with the side surfaces of the triangular prism shown in FIG. . The curved prism lens was designed to have a shape in which the angle formed between the tangent line at each point on the curved side surface and the first main surface 22a changes in the range of about 30 degrees to 60 degrees. The unit pitch PL ₃ was set to 30μm. The curved prism lens of the condensing sheet 20 and the convex lenticular lens 16 of the concealing structure 14 were arranged so as to be substantially parallel.
Further, DBEF (manufactured by 3M) was prepared as the polarization separating / reflecting sheet 21, and the lighting device 3 was manufactured.
The display device 1 was manufactured by disposing a liquid crystal panel as the image display element 2 above the lighting device 3 obtained in this way.

As a comparison, with respect to the configurations of Example 1, Example 2, and Example 3, a structure in which BS912 (manufactured by Keiwa) is arranged as a diffusion sheet instead of the respective concealment structure 14 is compared with Comparative Example 1 and Comparative Example, respectively. 2 and Comparative Example 3.
Moreover, as Comparative Example 4, in place of the concealment structure 14 in the configuration of Example 1, BEF185 (manufactured by 3M) shown in FIG. The triangular prism lens of BEF (manufactured by 3M) was arranged so as to be orthogonal.
Further, as Comparative Example 5, the condensing sheet 20 composed of a two-dimensional lens is removed from the configuration of Example 2, and the convex prisms 187 of the BEF185 (manufactured by 3M) shown in FIG. The lenticular lens 16 was arranged so as to be orthogonal.

Using the display device 1 including Examples 1 to 3 and Comparative Examples 1 to 5, the light source 9 is turned on and irradiated, and the front luminance, the luminance difference, the vertical half-value angle, the horizontal half-value angle, and the concealment property are obtained. evaluated. The evaluation results are shown in FIG.
For evaluation, SR-3A (manufactured by Topcon Corporation) was used as a spectral radiance meter for measuring front luminance, and EZContrast (manufactured by ELDIM) was used for measuring vertical and horizontal half-value angles. The hiding property was evaluated visually.

  In Example 1, the luminance was improved by 11% compared to Comparative Example 1, and the concealment property was good and there was no problem. In Example 1, the horizontal half-value angle is slightly narrower than that in Comparative Example 1, but the display device 1 has no problem. In Comparative Example 4, although the luminance was significantly improved, the horizontal half-value angle was remarkably narrow, and the light deflection element 12 formed on the light deflection surface 11 of the light guide plate 10 was visually recognized through the screen.

In Example 2, the luminance was improved by about 5% compared to Comparative Example 2, and the horizontal half-value angle was also widened. Moreover, the level of concealment was at a level with no problem. On the other hand, in Comparative Example 5, although the luminance was high, the horizontal half-value angle was remarkably narrow, and the concealability was also lowered.
In Example 3, the luminance was improved by about 8% compared to Comparative Example 3, and there was no problem with the concealing property. Although the horizontal half-value angle is slightly narrower than that of Comparative Example 3, the display device 1 was at a level causing no problem.

  Conventionally, in order to conceal the image of the light deflection element 12 formed on the light deflection surface 11 of the light guide plate 10, a diffusion sheet having almost no light collecting property was used. The illuminating device 3 provided with the concealing structure 14 and the light collecting sheets 20 and 32 that greatly improve the luminance while maintaining the same concealing property as in the case of using the diffusion sheet, and the display device provided with the illuminating device 3 I was able to make one.

DESCRIPTION OF SYMBOLS 1, 30 Display device 2 Image display element 3, 31 Illumination device 5, 6 Polarizing plate 7 Liquid crystal panel 9 Light source 9A Point light source 10 Light guide plate 10a Light guide plate exit surface 11 Light deflection surface 12 Light deflection element 13 Reflection sheet 14 Concealment structure Body 15 Base material 15a First main surface 15b Second main surface 16 First linear lens, convex lenticular lens 17 Micro lens 20, 32 Light collecting sheet 21 Polarized light separation / reflection sheet 22 Base material 22a First main surface 22b Second Main surfaces 23, 36, 40, 48 Third linear lens, triangular prism lens 25 Second linear lens, triangular prism lens 26 Second linear lens, lenticular lenses 27, 28, 55 Micro lens 33 Third Linear lens, trapezoidal prism lens 34, 37, 41, 46 Fourth linear lens, triangular prism lens 36, 40, 48 Third linear lens Triangular prism lens 38 concave 43 convex 45,51,54 third linear lens, a lenticular lens 49 and 52 a fourth linear lenses, a lenticular lens

Claims (18)

A light source; an incident surface on which light emitted from the light source is incident; an emission surface that emits incident light toward an observer; and a light deflection surface on which a light deflection element that guides incident light to the emission surface is disposed. An illumination device comprising: a light guide; and a concealing structure that conceals an image of the light deflection element while transmitting light emitted from an exit surface of the light guide to an observer side,
In the light guide, the light deflection elements are arranged at a _first pitch P1 in a _first direction and at a second pitch P2 in a _second direction substantially orthogonal to the first direction. Having a two-dimensional array structure,
The concealing structure includes a first main surface that emits incident light and a second main surface that causes the light emitted from the light guide to be incident as incident light, and the first main surface is arranged in at least one direction. The first linear lens is set, and the direction in which the first linear lens extends and the first direction of the light deflection element are set to be substantially parallel,
The first linear lens is a convex lenticular lens whose cross-sectional shape is a convex curved surface, and an angle formed between a tangent at an arbitrary point of the convex curved surface and the first principal surface extends from the top to the first principal surface. The lighting device is characterized in that the maximum angle α is defined by the following equation (1).

Where, n ₀ ,: refractive index of light guide t: thickness of light guide n ₁ : refractive index of first linear lens θ _i : incident angle of light incident on concealment structure The lighting device according to claim 1, wherein a cross-sectional shape of the first linear lens is defined by the following expression (2).
Here, the expression (2) is an expression when the unit lens pitch of the first linear lens is normalized to 1, z is a position function in the height direction of the first linear lens, and r is It is a position variable in the width direction of the first linear lens.

_3. The ratio P ₂ / P _1, which is a ratio between the _first pitch P ₁ and the second pitch P ₂ of the light deflection element, is defined by the following expression (3): 3. The lighting device described in 1.
_{1.0 <P 2 / P 1 <} 3.0 (3) The light deflection element, wherein the first direction is a first sequence n times the pitch P _1, the first direction and the second in the second direction substantially perpendicular to the pitch P ₂ m Arranged in a two-dimensional array of doubles,
4. The lighting device according to claim 1, wherein n and m are each selected from an integer of 1 to 10 at random. 5. The method according to claim 1, wherein P ₂ / P _1, which is a ratio between the _first pitch P ₁ and the second pitch P ₂ , is defined by the following expression (4): The lighting device described in the item.
1.4 <P ₂ / P ₁ <2.2 (4)   The light deflection element constitutes a hexagonal arrangement in which a triangle drawn by connecting three adjacent light deflection elements becomes a substantially regular triangle, or an arrangement obtained by removing an arbitrary light deflection element from a hexagonal arrangement. The illumination device according to any one of claims 1 to 5, wherein On the second main surface side of the concealing structure,
When a point light source that emits substantially Lambertian light from one point is arranged so that the principal axis of the emitted light and the normal direction of the second principal surface substantially coincide with each other,
The light that is incident from the second main surface and is emitted from the first main surface in the normal direction of the first main surface is the arrangement direction of the first linear lenses centering on the point light source. Converted into linear light that spreads
The lighting device according to claim 1, wherein the concealing structure is provided so that a peak luminance position of the linear light is directly above the point light source. The peak luminance position of the linear light is present at a position that is off directly above instead of directly above the point light source,
_{L 0} just above the brightness of the point light source, when the peak luminance was _{L 1,} an illumination apparatus according to claim 7, characterized in that L 1 / _{L 0} is less than 200% 100% or more.   The lighting device according to any one of claims 1 to 8, wherein the concealing structure includes a second linear lens arranged substantially orthogonal to the first linear lens.   The lighting device according to claim 1, wherein a condensing sheet is disposed on the first main surface side of the concealing structure. The condensing sheet includes a third linear lens arranged in at least one direction,
The lighting device according to claim 10, wherein an arrangement direction of the third linear lenses and an arrangement direction of the first linear lenses in the concealing structure are substantially orthogonal to each other.   12. The lighting device according to claim 10, wherein the condensing sheet further includes a fourth linear lens substantially orthogonal to the third linear lens. The lighting device according to any one of claims 1 to 12,
An image display element that is disposed on a side on which light emitted from the illumination device is incident and defines a display image;
A display device comprising:   The display device according to claim 13, wherein the first linear lens of the concealing structure extends in a vertical direction of the image display element.   When the first linear lens of the concealing structure extends in the horizontal direction of the image display element, the third linear lens of the condenser lens is in the vertical direction of the image display element. The display device according to claim 13, wherein the display device is disposed so as to extend.   When the first linear lens of the concealing structure extends in the horizontal direction of the image display element, the fourth linear lens of the condenser lens is in the vertical direction of the image display element. The display device according to claim 13, wherein the display device is disposed so as to extend.   The display device according to any one of claims 13 to 16, wherein a polarization separation / reflection sheet is disposed between the illumination device and the image display element.   18. The display device according to claim 13, wherein the display element defines a display image in accordance with transmission / shielding in pixel units.

Images