JP2004233938A - Light deflection element and light source device - Google Patents

Abstract

Provided is a light deflecting element and a light source device in which the distribution of emitted light is controlled to be narrow, the utilization efficiency of the light amount of a primary light source can be improved, and the image quality can be easily improved with a simplified configuration.
A light guide having a primary light source (1) and a light incident surface (31) on which light emitted from the primary light source is incident, and a light exit surface (33) for guiding the incident light and emitting the guided light. 3. A surface light source device comprising: a light guide element 3; The light deflecting element 4 has a light incident surface 41 on which light is incident and a light exit surface 42 which is located on the opposite side and emits incident light, and the light incident surface has a prism array composed of two prism surfaces. Are arranged in parallel with each other, at least one of these two prism surfaces is formed of a non-single plane, and the top distribution angle α of one of the prism surfaces constituting the prism array is 2 to 25 degrees and the other prism surface is The top distribution angle β is 33 to 40 degrees.
[Selection diagram] Fig. 1

Description

【０１１３】
【発明の効果】
以上説明したように、本発明によれば、光偏向素子の入光面に形成されるプリズム列を構成するプリズム面の少なくとも一方を非単一平面とし、かつ一方のプリズム面の頂部振り分け角αを２〜２５度とし、他方のプリズム面の頂部振り分け角βを３３〜４０度とすることで、一次光源から発せられる光を所要の観察方向へ集中して出射させる効率（一次光源の光量の利用効率）のよい光源装置を提供することができる。
【図面の簡単な説明】
【図１】本発明による光源装置を示す模式的斜視図である。
【図２】本発明の光偏向素子の入光面のプリズム列の形状の説明図である。
【図３】光偏向素子からの各種出射光分布を示す説明図である。
【図４】光偏向素子からの各種出射光分布を示す説明図である。
【図５】光偏向素子からの各種出射光分布を示す説明図である。
【図６】光偏向素子からの各種出射光分布を示す説明図である。
【図７】光偏向素子からの各種出射光分布を示す説明図である。
【図８】光偏向素子からの各種出射光分布を示す説明図である。
【図９】光偏向素子からの各種出射光分布を示す説明図である。
【図１０】光偏向素子からの各種出射光分布を示す説明図である。
【図１１】光偏向素子からの各種出射光分布を示す説明図である。
【図１２】光偏向素子からの各種出射光分布を示す説明図である。
【図１３】光偏向素子からの各種出射光分布を示す説明図である。
【図１４】光偏向素子からの各種出射光分布を示す説明図である。
【図１５】プリズム面の傾斜角の違いによる光の屈折およびプリズム断面の長さの違いを示す説明図である。
【図１６】プリズム面の傾斜角の違いによる光の屈折およびプリズム断面の長さの違いを示す説明図である。
【図１７】本発明の光偏向素子の入光面のプリズム列の形状の説明図である。
【図１８】略点状光源を導光体のコーナー部に隣接配置した斜視図である。
【図１９】出射光分布の半値全幅の説明図である。
【図２０】本発明の光偏向素子の入光面のプリズム列の形状の説明図である。
【符号の説明】
１ 一次光源
２ 光源リフレクタ
３ 導光体
４ 光偏向素子
５ 光反射素子
６ 光拡散素子
３１ 光入射端面
３２ 端面
３３ 光出射面
３４ 裏面
４１ 入光面
４２ 出光面
４３ プリズム列形成平面
４４ 第１のプリズム面
４５ 第２のプリズム面
４６〜５０ 平面
５１，５２ 凸曲面
５９ 平坦部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an edge light type light source device constituting a liquid crystal display device or the like used as a display unit in a notebook computer, a liquid crystal television, a mobile phone, a portable information terminal, and the like, and a light deflection element used therein. In particular, the present invention relates to an improvement in a light deflecting element disposed on a light exit surface side of a light guide of a light source device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, color liquid crystal display devices have been widely used in various fields as monitors of portable notebook personal computers and personal computers, or as display units of liquid crystal televisions and video-integrated liquid crystal televisions, mobile phones, personal digital assistants, and the like. I have. In addition, with an increase in information processing volume, diversification of needs, multimedia support, and the like, a large screen and high definition of a liquid crystal display device have been actively promoted.
[0003]
The liquid crystal display device basically includes a backlight unit and a liquid crystal display element unit. As the backlight portion, there are a direct type in which a primary light source is disposed directly below a liquid crystal display element portion, and an edge light type in which a primary light source is disposed so as to face a side end surface of a light guide, and a liquid crystal display device. The edge light method is frequently used from the viewpoint of downsizing.
[0004]
By the way, in recent years, in a liquid crystal display device used as a display unit of a mobile phone, for example, which is a display device having a relatively small screen size and a viewing direction range is relatively narrow, from the viewpoint of reducing power consumption, an edge light type is used. In order to effectively use the amount of light emitted from the primary light source, a backlight unit that reduces the spread angle of a light beam emitted from a screen as much as possible and emits light concentrated on a required angle range has been used. I have.
[0005]
As a display device in which the range of observation directions is limited as described above, a light source device that concentrates light in a relatively narrow range in order to increase the use efficiency of the light amount of the primary light source and reduce power consumption is disclosed in Japanese Patent Application Laid-Open No. 2001-143515 (Patent Document 2) proposes to use a prism sheet having a prism forming surface on both surfaces adjacent to a light exit surface of a light guide. In this double-sided prism sheet, a plurality of prism rows parallel to each other are formed on each of a light incident surface, which is one surface, and a light emitting surface, which is the other surface. And the prism rows are arranged at corresponding positions. Thereby, the light emitted from the light exit surface of the prism sheet has a peak of the emitted light in a direction inclined with respect to the light exit surface, and is emitted in an appropriate angle range. The light can enter from the prism surface, be reflected internally by the other prism surface, and be refracted by the prism on the light exit surface, so that light can be concentrated and emitted in a relatively narrow required direction.
[0006]
[Problems to be solved by the invention]
However, according to such a light source device, concentrated emission in a narrow angle range is possible. However, a plurality of prism rows parallel to each other on both sides as a prism sheet used as a light deflecting element are provided on a light entrance surface and a light exit surface. It is necessary to make the prism row directions coincide with each other and to arrange the prism rows at corresponding positions, and this molding becomes complicated.
[0007]
In Japanese Patent Application Laid-Open No. H10-254371 (Patent Document 1), the inclination angle α of one surface constituting a prism array is 4.7 to 5.7 degrees, and the inclination angle β of the other surface is 34.2 to 35 degrees. In this case, the luminance in the normal direction is improved, but a sufficient effect is not obtained because the other surface is flat.
[0008]
Therefore, an object of the present invention is to control the distribution of the emitted light to be very narrow and to improve the efficiency of using the light amount of the primary light source (that is, to concentrate the light emitted from the primary light source in a required observation direction). It is an object of the present invention to provide a light deflecting element and a light source device in which the image quality can be easily improved with a simplified configuration.
[0009]
[Patent Document 1]
JP-A-10-254371
[Patent Document 2]
JP 2001-143515 A
[0010]
[Means for Solving the Problems]
According to the present invention, to achieve the above object,
It has a light incident surface on which light is incident and a light exit surface which is located on the opposite side and emits incident light, and the light incident surface has a plurality of prism rows each composed of two prism surfaces arranged in parallel with each other. And at least one of the two prism surfaces is formed of a non-single plane, and the apex distribution angle α of one of the prism surfaces constituting the prism array is 2 to 25 degrees and the apex distribution angle β of the other prism surface Is 33 to 40 degrees, a light deflecting element,
Is provided. In the present invention, a non-single plane refers to a plane other than a plane composed of a single plane.
[0011]
In one embodiment of the present invention, one of the two prism surfaces is formed of a non-single plane and the other is formed of a single plane.
[0012]
In one aspect of the invention, the non-single plane comprises at least one convexly curved surface.
[0013]
In one embodiment of the present invention, the non-single plane includes two or more planes having different inclination angles from each other, or includes two or more convex curved surfaces having different inclination angles from each other, or one or more planes. It consists of one or more convex surfaces. In one embodiment of the present invention, the non-single plane has a larger inclination angle as the plane or the convex curved surface located closer to the light emitting surface.
[0014]
In one aspect of the present invention, in the non-single plane, the difference between the inclination angle of the surface closest to the top of the prism row and the inclination angle of the surface closest to the light exit surface is 1 ° to 15 °. In one embodiment of the present invention, in the light emitted from the light emitting surface after being totally reflected on each of the planes and / or the convex curved surfaces constituting the non-single plane, the distribution of the emitted light distribution for each of the surfaces is defined. The direction of the peak is substantially the normal direction of the plane on which the prism rows are formed.
[0015]
In one embodiment of the present invention, when the prism row has the coordinates of the vertices as its origin in its cross section and the length of the pitch P of the prism row is normalized to 1, the point 1 (−0.111, 1 .27), point 2 (0.0, 0.0), point 3 (0.159, 0.195), point 4 (0.212, 0.260), point 5 (0.265, 0.328) ), Point 6 (0.319, 0.398), point 7 (0.372, 0.470), point 8 (0.425, 0.544), point 9 (0.478, 0.621), Point 10 (0.531, 0.699), Point 11 (0.584, 0.780), Point 12 (0.637, 0.861), Point 13 (0.690, 0.945), Point 14 (0.743, 1.030), point 15 (0.796, 1.117), point 16 (0.889, 1.27) Consisting of the connected shape in the vicinity point.
[0016]
In one embodiment of the present invention, when the prism row has its origin at the coordinates of the vertex in the cross section and the length of the pitch P of the prism row is normalized to 1, the point 1 (−0.206, 1 .168), point 2 (0.000, 0.000), point 3 (0.159, 0.204), point 4 (0.212, 0.273), point 5 (0.265, 0.343) ), Point 6 (0.319, 0.416), point 7 (0.372, 0.490), point 8 (0.425, 0.567), point 9 (0.478, 0.646), 13 points of point 10 (0.531, 0.727), point 11 (0.584, 0.810), point 12 (0.637, 0.897), and point 13 (0.794, 1.168) It consists of a shape that connects.
[0017]
In one embodiment of the present invention, the prism row has a point 1 (−0.284, 1) when the coordinates of a vertex are set as an origin and the length of the pitch P of the prism row is normalized to 1 in the cross section. .059), point 2 (0.000, 0.000), point 3 (0.212, 0.278), point 4 (0.265, 0.350), point 5 (0.319, 0.423) ), Point 6 (0.372, 0.501), point 7 (0.425, 0.581), point 8 (0.478, 0.663), point 9 (0.531, 0.748), The shape is formed by connecting 12 points 10 (0.584, 0.834), 11 (0.637, 0.922), and 12 (0.716, 1.059).
[0018]
In one embodiment of the present invention, when the length of the pitch P of the prism array is normalized to 1 in the cross section of the prism array, at least 5 points selected from the 16 points, 13 points, or 12 points Has a shape connected by using the above-mentioned neighboring points within a circle having a radius of 0.021 around the point.
[0019]
In one embodiment of the present invention, the pitch P of the prism array and the length L2 of a virtual straight line connecting the prism apex and the valley in the cross-sectional shape of the prism surface at the apex distribution angle β constituting the prism array. Satisfy the relationship of L2 / P = 1.1 to 1.7. In one embodiment of the present invention, the length L1 of a virtual straight line connecting the prism top and the valley in the cross-sectional shape of the prism surface at the top distribution angle α, and the prism in the cross-sectional shape of the prism surface at the top distribution angle β The length L2 of the virtual straight line connecting the top and the valley satisfies the relationship of L2 / L1 = 1.1 to 1.3.
[0020]
In one embodiment of the present invention, when the ridge formed by the two prism surfaces constituting the prism array normalizes the length of the pitch P of the prism array to 1, the distance between the ridge and the reference line is 0.018 to 0.018. It is formed in an irregular shape of 0.354. In one embodiment of the present invention, when the two prism surfaces forming the prism array normalize the length of the pitch P of the prism array to 1, the distance between the two prism surfaces is 0.012 to 0.334 with respect to the reference surface. It is formed in an uneven shape.
[0021]
In one embodiment of the present invention, a flat portion is provided between adjacent prism rows. In one embodiment of the present invention, the flat portion is provided at a position of 2 to 10 μm in the height direction of the prism row from the prism valley. In one aspect of the present invention, when the length of the pitch P of the prism rows is normalized to 1 in the flat portion, the flat portions are located at positions 0.035 to 0.18 in the height direction of the prism rows from the prism troughs. It is provided in. In one embodiment of the present invention, when the flat portion normalizes the length L2 of an imaginary straight line connecting the prism top and the prism valley to 1 in the cross-sectional shape of the prism surface at the top distribution angle β, It is provided at a position of 0.022 to 0.16 in the height direction of the prism row from the trough.
[0022]
Further, according to the present invention, as achieving the above object,
A light guide having a primary light source, a light incident surface on which light emitted from the primary light source is incident, and a light exit surface for guiding the incident light and emitting the guided light; A light source device, comprising: the light deflecting element disposed so that the light incident surface is located opposite to the light exit surface of the light body.
Is provided.
[0023]
In one aspect of the present invention, the light deflecting element is arranged such that the prism surface having a top distribution angle α of the prism array is closer to the primary light source, and the prism surface having a top distribution angle β of the prism array is It is arranged on the side far from the primary light source.
[0024]
In one embodiment of the present invention, the primary light source is disposed adjacent to a corner of the light guide, and a prism array of the light deflecting element is disposed substantially concentrically around the primary light source. .
[0025]
In one embodiment of the present invention, the light deflecting element further includes a light diffusing element disposed adjacent to the light exit surface of the light deflecting element, and the light diffusing element has an anisotropic full width at half maximum of an emitted light distribution when parallel light is incident. Have the property.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
FIG. 1 is a schematic perspective view showing one embodiment of the surface light source device according to the present invention. As shown in FIG. 1, the surface light source device according to the embodiment of the present invention has a light guide in which at least one side end surface is a light incident surface 31 and one surface substantially orthogonal to the light incident surface 31 is a light exit surface 33. The body 3, the linear or rod-shaped primary light source 1 which is arranged to face the light incident surface 31 of the light guide 3 and is covered with the light source reflector 2, and is arranged on the light emitting surface 33 of the light guide 3. The light deflecting element 4 and the light diffusing element 6 disposed thereon, and the light reflecting element 5 disposed opposite to the back surface 34 of the light guide 3 opposite to the light exit surface 33.
[0028]
The light guide 3 is arranged parallel to the XY plane, and has a rectangular plate shape as a whole. The light guide 3 has four side end surfaces, of which at least one side end surface among a pair of side end surfaces parallel to the YZ plane is a light incident surface 31. The light incident surface 31 is disposed to face the primary light source 1, and light emitted from the primary light source 1 enters the light guide 3 from the light incident surface 31. In the present invention, for example, the primary light source may be arranged on another side end surface such as the side end surface 32 opposite to the light incident surface 31.
[0029]
The two main surfaces of the light guide 3 that are substantially perpendicular to the light incident surface 31 are located substantially parallel to the XY plane, respectively, and one of the surfaces (the upper surface in the figure) is a light emitting surface 33. At least one surface of the light emitting surface 33 or the back surface 34 opposite to the light emitting surface 33 has a rough directional light emitting function, and a number of lens rows such as a prism row, a lenticular lens row, and a V-shaped groove. By providing a directional light emitting function portion including a lens surface formed in parallel with the light incident surface 31 in parallel, the light emitted from the light incident surface 31 is guided through the light guide 3 while the light emitting surface is being guided. Light having directivity is emitted from the light distribution surface 33 in a plane (XZ plane) orthogonal to the light incident surface 31 and the light emission surface 33. Assuming that the angle between the direction of the peak of the emission light distribution in the XZ plane distribution and the light emission surface 33 is a, this angle a is preferably 10 to 40 degrees, and the full width at half maximum of the emission light distribution is 10 to 40 degrees. Degree is preferable.
[0030]
The rough surface and the lens array formed on the surface of the light guide 3 should have an average inclination angle θa according to ISO 4287 / 1-1984 in the range of 0.5 to 15 degrees, so that the luminance in the light exit surface 33 can be improved. Is preferable from the viewpoint of achieving uniformity. The average inclination angle θa is more preferably in the range of 1 to 12 degrees, and more preferably in the range of 1.5 to 11 degrees. It is preferable that the optimum range of the average inclination angle θa is set by the ratio (L / t) of the thickness (t) of the light guide 3 and the length (L) in the direction in which the incident light propagates. That is, when using a light guide 3 having an L / t of more than 20 and about 200 or less, the average inclination angle θa is preferably 0.5 to 7.5 degrees, more preferably 1 to 5 degrees. Degree, more preferably in the range of 1.5 to 4 degrees. When the light guide 3 having an L / t of about 20 or less is used, the average inclination angle θa is preferably set to 7 to 12 degrees, more preferably 8 to 11 degrees.
[0031]
The average inclination angle θa of the rough surface formed on the light guide 3 is obtained by measuring the rough surface shape using a stylus type surface roughness meter according to ISO 4287 / 1-1984, and setting the coordinates in the measurement direction as x. It can be obtained from the obtained inclination function f (x) using the following equations (1) and (2). Here, L is the measured length, and Δa is the tangent of the average inclination angle θa.
[0032]
Δa = (1 / L) ∫₀ ^L| (D / dx) f (x) | dx (1)
θa = tan^-1(Δa) (2)
Further, the light guide 3 preferably has a light emission rate in the range of 0.5 to 5%, more preferably 1 to 3%. This is because if the light emission rate is less than 0.5%, the amount of light emitted from the light guide 3 tends to be small and sufficient luminance cannot be obtained, and if the light emission rate is more than 5%, the vicinity of the primary light source 1 This causes a large amount of light to be emitted, and the attenuation of light in the X direction in the light emission surface 33 becomes remarkable, and the uniformity of luminance on the light emission surface 33 tends to decrease. By setting the light emission rate of the light guide 3 to 0.5 to 5% in this manner, the angle of the peak light (peak angle) in the emission light distribution of the light emitted from the light emission surface becomes normal to the light emission surface. With a high directivity such that the full width at half maximum of the emission light distribution on the XZ plane perpendicular to both the light incidence surface and the light emission surface is 10 to 40 degrees. Can be emitted from the light guide 3, the emission direction can be efficiently deflected by the light deflecting element 4, and a surface light source element having high luminance can be provided.
[0033]
In the present invention, the light emission rate from the light guide 3 is defined as follows. At the edge of the light exit surface 33 on the light incident surface 31 side, the light intensity (I₀  ) And the emitted light intensity (I) at a position at a distance L from the edge on the light incident surface 31 side, assuming that the thickness (dimension in the Z direction) of the light guide 3 is t, the following (3) Satisfies the relationship as in the equation.
[0034]
I = I₀・ A (1-A)^{L / t}  ... (3)
Here, the constant A is the light emission rate, and the light guide 3 per unit length (length corresponding to the light guide thickness t) in the X direction orthogonal to the light incidence surface 31 on the light emission surface 33. Out of the light. The light emission rate A is obtained from the gradient by plotting the logarithm of the light intensity of the light emitted from the light emission surface 23 on the vertical axis and (L / t) on the horizontal axis, and plotting these relationships. Can be.
[0035]
In addition, on another main surface to which the directional light emission function unit is not provided, in order to control the directivity on a plane (YZ plane) parallel to the primary light source 1 of the light emitted from the light guide 3, It is preferable to form a lens surface in which a number of lens rows extending in a direction (X direction) substantially perpendicular to the light incident surface 31 are arranged. In the embodiment shown in FIG. 1, a rough surface is formed on the light exit surface 33, and a lens surface formed of an array of a large number of lens rows extending substantially perpendicularly to the light incident surface 31 (X direction) on the back surface 34. Is formed. In the present invention, contrary to the embodiment shown in FIG. 1, a lens surface may be formed on the light emitting surface 33 and the back surface 34 may be roughened.
[0036]
As shown in FIG. 1, when a lens array is formed on the back surface 34 or the light emitting surface 33 of the light guide 3, the lens array includes a prism array extending substantially in the X direction, a lenticular lens array, and a V-shaped groove. And the like, but it is preferable to form a prism array having a substantially triangular cross section in the YZ section.
[0037]
When this prism row is formed, the apex angle is preferably in the range of 70 to 150 degrees. This is because by setting the apex angle in this range, the light emitted from the light guide 3 can be sufficiently collected, and the luminance of the surface light source device can be sufficiently improved. In other words, by setting the prism apex angle within this range, the focused outgoing light having the full width at half maximum of 35 to 65 degrees of the outgoing light distribution on the plane perpendicular to the XZ plane including the peak light in the outgoing light distribution is emitted. And the luminance as a surface light source element can be improved. When the prism array is formed on the light exit surface 33, the apex angle is preferably in the range of 80 to 100 degrees. When the prism array is formed on the back surface 34, the apex angle is 70 to 80 degrees. Alternatively, the angle is preferably in the range of 100 to 150 degrees.
[0038]
In the present invention, instead of forming the light emitting function portion on the light emitting surface 33 or the back surface 34 as described above or in combination with the light emitting function portion, the light diffusing fine particles are mixed and dispersed inside the light guide. It may have a directional light emission function. Further, the light guide 3 is not limited to the cross-sectional shape shown in FIG. 1, but may have various cross-sectional shapes such as a wedge shape and a boat shape.
[0039]
FIG. 2 is an explanatory diagram of the shape of the prism array in the light deflecting element 4. One of the main surfaces of the light deflecting element 4 is a light incident surface 41 and the other surface is a light emitting surface 42. A large number of prism rows are arranged in parallel on the light entrance surface 41. Each prism row has two prisms, a first prism face 44 located on the light source side and a second prism face 45 located on the far side from the light source. It is composed of faces. In the embodiment shown in FIG. 2, the first prism surface 44 is a plane, and the second prism surface 45 is a non-single plane composed of three planes 46 to 48 having different inclination angles from each other. These three planes have a larger inclination angle as the plane is closer to the light emitting surface 42. In the present invention, the inclination angle of the surface of the prism array refers to the inclination angle of each surface with respect to the prism array forming plane 43.
[0040]
The light deflecting element 4 sets the top distribution angle α of the first prism surface 44 to 2 to 25 degrees, the top distribution angle β of the second prism surface 45 to 33 to 40 degrees, and the absolute value of the difference between α and β (| When α-β |) is set to 8 to 38 degrees, a high light-collecting effect can be exhibited, and high luminance can be obtained as the light source device. In the present invention, the vertex distribution angles α and β are the left and right distribution angles of the vertex angles of the prism rows with respect to the normal direction of the prism row forming plane 43, and the prism row formation angles at the apex of the first prism surface 44. An angle between the normal direction of the plane 43 and the normal direction of the prism array forming plane 43 at the top of the second prism surface 45 is set as β. Further, a prism surface is formed by two or more surfaces having a larger inclination angle as the surface is closer to the light exit surface 42, and the peak angle of the light totally reflected by each surface and emitted from the light exit surface 42 is determined. Extremely high luminance can be obtained by making the same on all surfaces. At this time, the difference in the inclination angle between the surface closest to the light emitting surface and the surface farthest from the light emitting surface is in the range of 1 to 15 degrees, preferably 5 to 12 degrees, more preferably 7 to 10 degrees. Range of degrees. Further, by forming the second prism surface 45 in such a structure, it is possible to easily design a deflecting element having a desired light condensing property, and to stably provide an optical deflecting element having certain optical characteristics. It can also be manufactured.
[0041]
Next, the shape and function of the prism surface in the light deflection element of the present invention will be described in more detail. 3 to 12 show that the two prism surfaces are both formed of a single plane and have angles α and β (corresponding to the top distribution angles α and β in the present invention) with respect to the normal direction of the light emission surface, respectively. With respect to a conventional light deflecting element which is arranged symmetrically with respect to the direction and has a prism apex angle of 65.4 degrees (α = β = 32.7 degrees), the peak angle of the distribution of light emitted from the light guide is equal to the light angle. It shows how the light that is 20 degrees with respect to the exit surface exits from the light deflection element in a plane perpendicular to both the light entrance surface and the light exit surface of the light guide. It is a thing. FIGS. 3 to 12 show a state in which incident light incident from the first prism surface is totally reflected by the second prism surface and emitted from the light exit surface 42, and the second prism surface is divided into ten areas in the x direction. It is equally divided and shows the distribution of light emitted from each area. The ten areas are named Part1, Part2,... Part10 in order from the one closer to the top of the prism. In the emission light distribution of the entire light that is totally reflected and emitted from the second prism surface, as shown in FIG. 13, the peak light is emitted in the normal direction of the prism row formation plane, and the full width at half maximum of 22 degrees is reduced. Have.
[0042]
However, when these are viewed in the emission light distributions in the respective areas of Part1 to Part10, the peak angle is about -9 degrees in Part1 and Part2 (a negative angle value is a case where the normal direction is 0 degree and the light is inclined toward the light source. The peak light is sequentially shifted in the direction of 0 degrees (the normal direction of the prism array forming plane) in Part3 to Part7, and the peak light is sequentially shifted in the positive angle direction in Part8 to Part10. You can see that it is shifting. The peak angle of the emitted light totally reflected in the area (Part 10) closest to the light emitting surface 42 is 7 degrees. The peak angle has a spread of 16 degrees between the areas (Part 1 to Part 10) of the second prism surface. Further, the intensity of the peak light from each area gradually decreases from Part1 to Part10.
[0043]
Thus, it can be seen that the light totally reflected and emitted by the prism surface composed of one plane is dispersed in a considerably wide range depending on the area of the prism surface that is totally reflected. By adjusting the inclination angle of the surface of each area, the peak light in the emission light distribution from each area is emitted so that the peak angle is substantially the same direction in all areas, so that most of the emission light is reduced. It is possible to emit light concentrated in a specific direction. At this time, the inclination angle of the prism surface in each area is set to be larger in the order of Part1 to Part10, that is, the inclination angle is set larger in the area closer to the light exit surface 42. In this way, by adjusting the inclination angle of the surface of each area, the outgoing light totally reflected by the entire prism surface can be collected in a certain direction as shown in FIG. High light with high peak intensity can be emitted. The present invention has been made based on such an idea.
[0044]
However, when the apex distribution angle of the first prism surface 44 is α = 32.7 degrees, the amount of light received by the second prism surface 45 is not so large, and there is a limit in improving the peak intensity. Therefore, by setting α to 2 to 25 degrees, the amount of light impinging on the second prism surface 45 can be increased, and as a result, the peak intensity increases. This is because the effect of refraction on the first prism surface 44 is increased as shown in FIG. 16 as compared with FIG. 15, and the size of the prism is adjusted so that the prisms have the same pitch. This is because the length in the shape becomes longer. For example, assuming that α is 5 degrees and β is 38 degrees as shown in FIG. 16, the light amount of about 1.29 times as large as that of the case of α = β = 32.7 degrees as shown in FIG. The light can be received by the prism surface 45. By reducing α in this manner, the amount of light that strikes the prism surface 45 increases, but if the second prism surface 45 is a single plane, the totally reflected light cannot be efficiently directed substantially in the normal direction. This requires that the second prism surface 45 be non-planar, eg, curved, and / or comprised of several surfaces, eg, flat.
[0045]
When the number of areas of the second prism surface 45 is increased, the peak angle can be finely adjusted over the entire prism surface, and the degree of concentration of light emission as a whole can be increased. However, the planes with different inclination angles must be formed finely, which complicates the design and manufacture of a cutting die for forming the prism surface of the optical deflecting element, and has an optical deflection having a certain optical characteristic. It is also difficult to obtain a stable device. Therefore, the number of areas formed on the prism surface is preferably in the range of 3 to 20, and more preferably in the range of 4 to 15. Although it is preferable to divide the prism surface into areas uniformly, it is not always necessary to divide the area uniformly, and it can be adjusted in accordance with a desired emission light distribution on the entire prism surface.
[0046]
The value of α is in the range of 2 to 25 degrees, preferably 5 to 20 degrees, more preferably 11 to 20 degrees, most preferably 12 to 15 degrees, and the value of β is 33 to 40 degrees, preferably 33 to 40 degrees. 0.5-39.5 degrees, more preferably 33.5-38 degrees, and most preferably 34-38 degrees. The absolute value of the difference between α and β (| α−β |) is 8 to 38 degrees, preferably 13 to 35 degrees, more preferably 13 to 27 degrees, and most preferably 19 to 26 degrees. The smaller the value of α, the higher the peak intensity, but it becomes difficult to direct the peak angle in the substantially normal direction when α = 0 degrees. When α is reduced, the prism apex angle (α + β) is also reduced in order to direct the peak angle in the substantially normal direction, so that the manufacturing becomes somewhat difficult. In consideration of these, α is most preferably 5 degrees or more, and the cross-sectional shape in which the peak angle of the emitted light distribution for each surface is substantially the normal direction is most preferable.
[0047]
As a specific prism shape, when the coordinate of the vertex of the prism is set as the origin and the length of the pitch P of the prism row is normalized to 1, the point 1 (−0.111, 1) is displayed in (x, z) coordinate display. .27), point 2 (0.0, 0.0), point 3 (0.159, 0.195), point 4 (0.212, 0.260), point 5 (0.265, 0.328) ), Point 6 (0.319, 0.398), point 7 (0.372, 0.470), point 8 (0.425, 0.544), point 9 (0.478, 0.621), Point 10 (0.531, 0.699), Point 11 (0.584, 0.780), Point 12 (0.637, 0.861), Point 13 (0.690, 0.945), Point 14 (0.743, 1.030), point 15 (0.796, 1.117), point 16 (0.889, 1.27) Include those consisting of 15 planes of. Point 1 (-0.284, 1.059), point 2 (0.000, 0.000), point 3 (0.212, 0.278), point 4 (0.265, 0.350), Point 5 (0.319, 0.423), Point 6 (0.372, 0.501), Point 7 (0.425, 0.581), Point 8 (0.478, 0.663), Point 9 12 points of (0.531, 0.748), point 10 (0.584, 0.834), point 11 (0.637, 0.922), and point 12 (0.716, 1.059) are connected. A shape composed of eleven planes having an elliptical cross-sectional shape is also preferable. Further, point 1 (−0.206, 1.168), point 2 (0.000, 0.000), point 3 (0.159, 0.204), point 4 (0.212, 0.273), Point 5 (0.265, 0.343), Point 6 (0.319, 0.416), Point 7 (0.372, 0.490), Point 8 (0.425, 0.567), Point 9 (0.478, 0.646), point 10 (0.531, 0.727), point 11 (0.584, 0.810), point 12 (0.637, 0.897), point 13 (0 .794, 1.168) are also preferably formed of 12 planes having a sectional shape connecting 13 points.
[0048]
The points 16, 12, and 13 of the cross-sectional shape do not have to pass exactly all of them. A slight deviation from each point (that is, passing through a point near each point) does not significantly affect the peak intensity. However, when the length of the pitch P of the prism rows is normalized to 1, at least 5 points among the 16 points, 12 points, or 13 points have deviations from the above-mentioned predetermined coordinates of a radius of 0 around those points. 0.021, preferably within a circle of radius 0.018, more preferably within a circle of radius 0.014. Most preferably, the eight points are within a circle having a radius of 0.014.
[0049]
In the present invention, for example, as shown in FIG. 17, at least one of the prism surfaces having different inclination angles as described above may be a convex curved surface, or all surfaces may be convex curved surfaces. That is, the prism surface may be composed of one or more flat surfaces and one or more convex curved surfaces, or may be composed of two or more convex curved surfaces having different inclination angles. In FIG. 17, the second prism surface 45 is divided into four areas, and is composed of two flat surfaces 49 and 50 and two convex curved surfaces 51 and 52. The convex curved surface 51 forms a part of a circle having a center (-5.025, 4.389) radius R = 6.669 in its cross-sectional shape, and the convex curved surface 52 has a center (--6. 672, 5.537) is a part of a circle having a radius R = 8.677. As described above, when the prism surface is formed by a plurality of convex curved surfaces having different inclination angles, the number of areas is reduced to, for example, 2 to 10, preferably 2 to 5, as compared with the case where the prism surface is formed by planes having different inclination angles. can do. However, if the number of areas is too small, it becomes difficult to design each convex curved surface for adjusting a desired distribution of emitted light, so the number of areas is more preferably in the range of 3 to 4.
[0050]
The shape of the convex curved surface can be not only circular but also non-circular in XY cross section. Further, when a prism surface is formed by a plurality of convex curved surfaces, it is preferable that the shapes of the convex curved surfaces are different, and a convex curved surface having a circular cross section and a convex curved surface having a non-circular cross section can be combined. Examples of the non-circular shape include a part of an elliptical shape and a part of a parabolic shape.
[0051]
In the present invention, the angle of inclination in the case of a convex curved surface refers to the angle of inclination of the surface (corresponding to the chord of the convex curved portion in the cross-sectional shape) connecting the both edges of the convex curved surface with respect to the prism row forming plane 43. In the case where the convex curved surface forms the top portion, the apex distribution angle refers to an angle formed by the normal direction of the prism row forming plane 43 of the surface connecting both end edges of the convex curved surface.
[0052]
Regarding the relationship between the pitch P of the prism array and the length L2 connecting the top of the prism array and the valley of the prism surface 45 of the prism array, the amount of light received by the prism surface 45 is increased and the prism surface forming the prism array is increased. L2 / P = 1.1 to 1.7 in order to direct the peak angle of the emitted light distribution of each area in the normal direction so that the prism apex angle (α + β) does not become too small. preferable. More preferably, L2 / P = 1.16 to 1.6, and further preferably, L2 / P = 1.27 to 1.56. The relationship between the length L1 connecting the top of the prism array and the valley of the prism surface 44 and the length L2 connecting the top of the prism array and the valley of the prism surface 45 is L2 / L1 = 1.1. It is preferable to set it to 1.3. More preferably, L2 / L1 = 1.13 to 1.25, and still more preferably, L2 / L1 = 1.16 to 1.22.
[0053]
In the present invention, the prism row has a small cut angle at the prism valley. For this reason, burrs are likely to occur in the prism valley during manufacturing, and a defect that the prism valley looks like a streak may occur. In order to prevent such a defect from occurring, it is preferable to provide a flat portion 59 between adjacent prism rows as shown in FIG. As shown in the figure, the flat portion 59 is preferably provided at a position of 2 to 10 μm in the height direction of the prism from the trough of the prism when the flat portion is not formed, more preferably 2.5 to 5 μm. More preferably, the position is 3 to 4 μm. If the position is less than 2 μm, precise machining of the cutting tool for forming the pattern of the prism rows into a mold tends to be difficult, and if it exceeds 10 μm, the brightness tends to decrease. When the length of the pitch P of the prism rows is normalized to 1, the flat portion is formed in a range of 0.035 to 0.18 in the height direction from the prism valley where the flat portion is not formed. Alternatively, when the length L2 of a virtual straight line connecting the prism top and the prism valley is normalized to 1 in the cross-sectional shape of the prism surface at the top distribution angle β, the height from the prism valley to the height of the prism row is normalized. It may be in the range of 0.022 to 0.16.
[0054]
When the length of the pitch P between the prism rows is normalized to one, the ridge formed by the two prism surfaces constituting the prism row is 0 with respect to the reference line of the ridge (the line located at the average height of the prism row). It is also possible to form irregularities of 0.018 to 0.354. The degree of unevenness of the ridgeline with respect to the reference line is preferably 0.018 to 0.177, more preferably 0.018 to 0.088, and even more preferably 0.035 to 0.063. By making the ridges uneven in the Z direction, glare is prevented, defects of the light guide plate and the light deflecting element are hardly visually recognized, and the quality is improved, such as reducing uneven brightness. On the other hand, when the ridge is made uneven, a slight gap is generated between the light guide plate and the light deflecting element. For this reason, the light emitted from the light guide plate impinges on the prism array on the side opposite to the light source from the prism array to be hit when there is no gap. In particular, the light emitted from the light guide closer to the normal line than the peak emission light is the prism array May not be able to hit the main reflecting surface (the prism surface farther from the primary light source), in which case the overall brightness may be reduced accordingly. However, in the light deflecting element of the present invention, since the luminance is greatly increased by compensating for the luminance reduction due to the unevenness of the ridge line, it is possible to prevent the overall luminance from lowering. However, in order to sufficiently exhibit the effect of the light deflecting element of the present invention, it is preferable that the degree of unevenness of the ridge line be within the above range. The method for forming the ridge lines in an uneven shape is not particularly limited. For example, a method of forming using a lens mold cut while applying a specific vibration when cutting and forming a lens pattern, or grinding a ridge line part of a lens unit of a conventional lens sheet using fine sandpaper etc. And the like.
[0055]
When the two prism surfaces constituting the prism array are normalized with the length of the pitch P of the prism array being 1, the reference surface of the prism surface (the reference line of the ridge line and the bottom of the prism surface (side on the valley side)) (A plane including the center line of the ridge line) can be formed in an uneven shape of 0.012 to 0.334, thereby improving the quality as in the case of forming the ridge line in an uneven shape. The degree of unevenness with respect to the prism reference plane is preferably 0.012 to 0.152, more preferably 0.012 to 0.076, and even more preferably 0.022 to 0.046.
[0056]
As described above, the light deflecting element 4 as described above is mounted on the light exit surface 33 of the light guide 3 such that the prism row forming surface is on the light incident surface side, whereby the light guide 3 The distribution of the directional emission light emitted from the light emission surface 33 in the XZ plane can be further narrowed, and the brightness of the light source device can be increased. That is, in the present invention, in the light source device in which the prism array forming surface of the light deflecting element 4 is arranged to face the light exit surface 33 of the light guide 3, the main reflection surface of the prism array (the side farther from the primary light source) In addition to optimizing the shape of the prism surface and increasing the length, when the light emitted from the light guide 3 enters the prism array, the incident light is refracted in a direction away from the light exit surface 42 of the light deflector 4. By setting the inclination angle of the light incident surface of the prism array (the prism surface closer to the primary light source) so that the light can be dispersed, the light use efficiency can be reduced by suppressing the dispersion of light in unnecessary directions. Thus, the light can be concentrated and emitted in a desired direction, and the luminance of the light source device can be remarkably improved.
[0057]
In the light deflecting element 4 as described above, when the prism surface is composed of a plurality of planes or convex curved surfaces having different inclination angles, the top and bottom of the prism row are connected to ensure sufficient light-collecting characteristics. It is preferable that the maximum distance (d) between the virtual plane and a plurality of planes or convex curved surfaces (actual prism surfaces) is 0.4 to 5% in terms of the ratio (d / P) to the pitch (P) of the prism rows. This is because, when d / P is less than 0.4% or more than 5%, the light-collecting characteristics tend to decrease, and it tends to be impossible to sufficiently improve the brightness, and more preferably. It is in the range of 0.4 to 4.5%, and more preferably in the range of 0.7 to 4.0%. Further, as the convex curved surface, the radius of curvature (r) thereof is preferably in a range of 2 to 50, more preferably 5 to 30, more preferably 5 to 50, in which the ratio (r / P) to the pitch (P) of the prism rows. Is in the range of 6.5 to 12. If the r / P is less than 2 or more than 50, sufficient light-collecting characteristics cannot be exhibited, and the brightness tends to decrease.
[0058]
The full width at half maximum of the emission light distribution of the emission light from the light deflecting element 4 in the XZ plane is preferably 5 degrees or more and 25 degrees or less, more preferably 10 to 20 degrees, and Preferably it is in the range of 11 to 15 degrees. This is because by setting the full width at half maximum of the emitted light distribution to 5 degrees or more, it is possible to eliminate the difficulty in viewing an image or the like due to an extremely narrow visual field, and to achieve 25 degrees or less to achieve high brightness. That's why.
[0059]
The primary light source 1 is a linear light source extending in the Y direction. As the primary light source 1, for example, a fluorescent lamp or a cold cathode tube can be used. In the present invention, the primary light source 1 is not limited to a linear light source, and a point light source such as an LED light source, a halogen lamp, a metahalo lamp, or the like may be used. In particular, when used in a display device having a relatively small screen size such as a mobile phone or a portable information terminal, it is preferable to use a small point light source such as an LED. In addition, as shown in FIG. 1, the primary light source 1 can be further installed not only on one side end face of the light guide 3 but also on the other side end face as necessary. .
[0060]
In the present invention, as shown in FIG. 1, when a linear light source is used as the primary light source 1, the prism array formed on the light deflecting element 4 extends in a direction substantially parallel to the primary light source 1. Alternatively, the primary light source 1 is formed so as to extend in a direction having an inclination of 20 ° or less, but the arrangement of the prism array formed on the light deflecting element 4 depends on the light source used and the propagation of light propagating through the light guide 3. Can be changed by direction. For example, as shown in FIG. 18, when a substantially point light source such as an LED light source is used as the primary light source 1 at a corner or the like of the light guide 3, the light incident on the light guide 3 is emitted from the light exit surface. In the same plane as 33, the light propagates through the light guide 3 radially with the primary light source 1 substantially at the center, and the light emitted from the light emitting surface 33 also emits radially with the primary light source 1 at the center. In order to efficiently deflect such emitted light in a desired direction irrespective of the emission direction, a prism array formed on the light deflecting element 4 is arranged in a substantially arc shape so as to surround the primary light source 1. It is preferable to arrange them. In this way, by arranging the prism rows in a substantially arc shape in parallel so as to surround the primary light source 1, most of the light radially emitted from the light exit surface 33 is substantially perpendicular to the prism rows of the light deflecting element 4. , The emitted light can be efficiently directed in a specific direction in the entire region of the light exit surface 33 of the light guide 3, and the uniformity of luminance can be improved. The substantially arc-shaped prism array formed on the light deflecting element 4 selects the degree of the arc according to the distribution of light propagating in the light guide 3, and most of the light radially emitted from the light exit surface 33 is light. It is preferable that the light is incident on the prism array of the deflecting element 4 substantially perpendicularly. Specifically, there are those arranged in parallel so that the radius of the substantially circular arc is gradually increased in a substantially concentric manner with a point light source such as an LED substantially at the center. It is determined by the positional relationship and size between the position of the point light source in the surface light source system and the effective area of the surface light source corresponding to the liquid crystal display area.
[0061]
The light source reflector 2 guides the light of the primary light source 1 to the light guide 3 with little loss. As the material, for example, a plastic film having a metal deposition reflective layer on the surface can be used. As shown, the light source reflector 2 is wound from the outer surface of the edge of the light reflecting element 5 to the outer surface of the primary light source 1 to the edge of the light emitting surface of the light diffusing element 6. On the other hand, the light source reflector 2 avoids the light diffusing element 6 and the light deflecting element 4 and passes from the outer surface of the edge of the light reflecting element 5 to the edge of the light emitting surface of the light guide 3 via the outer surface of the primary light source 1. It is also possible to wrap.
[0062]
A reflecting member similar to the light source reflector 2 can be attached to a side end surface other than the side end surface 31 of the light guide 3. As the light reflection element 5, for example, a plastic sheet having a metal deposition reflection layer on the surface can be used. In the present invention, instead of the reflection sheet, the light reflection element 5 may be a light reflection layer or the like formed on the back surface 34 of the light guide 3 by metal deposition or the like.
[0063]
The light guide 3 and the light deflecting element 4 of the present invention can be made of a synthetic resin having a high light transmittance. Examples of such a synthetic resin include a methacrylic resin, an acrylic resin, a polycarbonate resin, a polyester resin, and a vinyl chloride resin. In particular, methacrylic resin is optimal because of its high light transmittance, heat resistance, mechanical properties, and moldability. Such a methacrylic resin is a resin containing methyl methacrylate as a main component, and is preferably a resin having 80% by weight or more of methyl methacrylate. When forming the surface structure of the rough surface of the light guide 3 and the light deflecting element 4 and the surface structure such as the prism rows, the transparent synthetic resin plate is formed by hot pressing using a mold member having a desired surface structure. The shape may be provided simultaneously with the molding by screen printing, extrusion molding, injection molding, or the like. Further, the structural surface can also be formed by using a heat or light curable resin. Further, on a transparent substrate such as a transparent film or sheet made of a polyester resin, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polymethacrylimide resin, etc., a rough surface structure made of an active energy ray-curable resin. Further, a lens array structure may be formed on the surface, or such a sheet may be joined and integrated on a separate transparent substrate by a method such as adhesion or fusion. As the active energy ray-curable resin, polyfunctional (meth) acrylic compounds, vinyl compounds, (meth) acrylates, allyl compounds, metal salts of (meth) acrylic acid, and the like can be used.
[0064]
The light emitting surface (the light emitting surface 42 of the light deflecting element 4 and the light emitting surface 42) of the surface light source device including the primary light source 1, the light source reflector 2, the light guide 3, the light deflecting element 4, the light reflecting element 5, and the light diffusing element 6 as described above. Is disposed on the surface of the light diffusing element 6) to constitute a liquid crystal display device. The liquid crystal display device is observed by an observer through the liquid crystal display element from above in FIG. In addition, in the present invention, since a sufficiently collimated light with a narrow distribution can be made to enter the liquid crystal display element from the surface light source device, there is no grayscale inversion or the like in the liquid crystal display element, and the uniformity of brightness and hue is obtained. In addition to obtaining good image display, light irradiation concentrated in a desired direction can be obtained, and the efficiency of using the amount of light emitted from the primary light source for illumination in this direction can be increased.
[0065]
Further, in the present invention, in the light source device having a narrow field of view and a high luminance by the light deflecting element 4 as described above, the range of the visual field can be appropriately controlled according to the purpose without causing a reduction in the luminance as much as possible. In addition, the light diffusing element 6 can be arranged adjacent to the light exit surface of the light deflecting element 4. Further, in the present invention, by arranging the light diffusing element 6 in this way, it is possible to suppress glare, uneven brightness, and the like that cause deterioration in quality, thereby improving the quality.
[0066]
The light diffusing element 6 may be integrated with the light deflecting element 4 on the light emitting surface side of the light deflecting element 4, or the light diffusing elements 6 may be individually mounted on the light emitting surface side of the light deflecting element 4. Although it is good, it is preferable to dispose the light diffusion elements 6 individually. When the light diffusing elements 6 are individually mounted, an uneven structure is provided on the surface of the light diffusing element 6 adjacent to the light deflecting element 4 in order to prevent sticking with the light deflecting element 4. Is preferred. Similarly, it is necessary to consider the sticking between the light emitting element 6 and the liquid crystal display element disposed on the light emitting element 6. Is preferred. When the uneven structure is provided only for the purpose of preventing sticking, it is preferable that the average inclination angle be 0.7 degrees or more, more preferably 1 degree or more, and more preferably 1 degree or more. 0.5 degrees or more.
[0067]
In the present invention, it is necessary to use the light diffusing element 6 having a light diffusing property for appropriately diffusing the light emitted from the light deflecting element 4 in consideration of the balance between the luminance characteristic, the visibility and the quality. That is, when the light diffusing property of the light diffusing element 6 is low, it is difficult to sufficiently widen the viewing angle, and the visibility is reduced, and the effect of improving the quality tends to be insufficient. If it is too high, the effect of narrowing the field of view by the light deflecting element 4 will be impaired, and the total light transmittance will also decrease, tending to lower the luminance. Therefore, as the light diffusing element 6 of the present invention, a light diffusing element having a full width at half maximum of 1 to 13 degrees of the emitted light distribution when parallel light is incident is used. The full width at half maximum of the light diffusion element 6 is preferably in the range of 3 to 11 degrees, and more preferably in the range of 4 to 8.5 degrees. In the present invention, the full width at half maximum of the emission light distribution of the light diffusing element 6 indicates, as shown in FIG. 19, how much a parallel light beam incident on the light diffusing element 6 is diffused and spread at the time of emission. The full width angle (Δθ) of the divergence angle at half value with respect to the peak value in the luminous intensity distribution of the emitted light transmitted and diffused through the light diffusion element 6_H).
[0068]
Such light diffusion characteristics can be imparted by mixing a light diffusing agent into the light diffusing element 6 or imparting an uneven structure to at least one surface of the light diffusing element 6. The degree of the concavo-convex structure formed on the surface is different between the case where it is formed on one surface of the light diffusion element 6 and the case where it is formed on both surfaces. When an uneven structure is formed on one surface of the light diffusing element 6, the average inclination angle is preferably in the range of 0.8 to 12 degrees, more preferably 3.5 to 7 degrees, Preferably it is 4 to 6.5 degrees. When the uneven structure is formed on both surfaces of the light diffusing element 6, the average inclination angle of the uneven structure formed on one surface is preferably in the range of 0.8 to 6 degrees, more preferably 2 to 6. 4 degrees, more preferably 2.5 to 4 degrees. In this case, in order to suppress a decrease in the total light transmittance of the light diffusion element 6, it is preferable that the average inclination angle on the incident surface side of the light diffusion element 6 be larger than the average inclination angle on the emission surface side. Further, the haze value of the light diffusing element 6 is preferably in the range of 8 to 82% from the viewpoint of improving the luminance characteristics and the visibility, more preferably in the range of 30 to 70%, and more preferably 40 to 70%. ６５65%.
[0069]
In the light source device of the present invention, it is also required that the luminance in the display area when observed from the normal direction of the light emitting surface (the emission surface of the light diffusing element 6) is uniform. The uniformity of the luminance also depends on the size of the display area of the light source. For example, a large light source device having a large display area such as a notebook computer or a monitor may require a relatively wide viewing angle characteristic. It is required that the distribution of the light emitted from the light emitting surface be made wider. On the other hand, in a small light source device having a small display area such as a mobile phone or a portable information terminal, high brightness and improvement in display quality may be prioritized, and the distribution of light emitted from the light emitting surface may be relatively narrow. . For this reason, it is preferable to use the light diffusion element 6 having an appropriate light diffusion characteristic according to the size of the display area of the light source device.
[0070]
In the present invention, light emitted from the light guide 3 is emitted in a specific direction such as the normal direction using the light deflecting element 4, and the emitted light is emitted using the light diffusing element 6 having anisotropic diffusion property. It can also be emitted in a desired direction. In this case, both functions of the anisotropic diffusion function and the light deflection function can be provided to the light diffusion element 6. For example, in the case of using a lenticular lens array or a cylindrical lens shaped body as the concavo-convex structure, by making the cross-sectional shape asymmetrical, it is possible to provide both functions of anisotropic diffusion action and light deflection action.
[0071]
In the present invention, the light deflecting element 4 and the light diffusing element 6 may contain a light diffusing material for the purpose of adjusting the viewing angle as the light source device and improving the quality. As such a light diffusing material, transparent fine particles having a different refractive index from the material constituting the light deflecting element 4 and the light diffusing element 6 can be used. For example, silicon beads, polystyrene, polymethyl methacrylate, fluorinated Homopolymers or copolymers such as methacrylate are exemplified. As the light diffusing material, it is necessary to appropriately select the content, the particle diameter, the refractive index, and the like so as not to impair the narrow visual field effect by the light deflecting element 4 and the appropriate diffusion effect by the light diffusing element 6. For example, the refractive index of the light diffusing material is small if the difference between the refractive index of the light deflecting element 4 and the material forming the light diffusing element 6 is too small. The rate difference is preferably in the range of 0.01 to 0.1, more preferably 0.03 to 0.08, and still more preferably 0.03 to 0.05. In addition, the particle size of the light diffusing material is such that if the particle size is too large, scattering becomes strong, causing glare and a decrease in brightness, and if too small, coloring occurs, so that the average particle size is in the range of 0.5 to 20 μm. Preferably, it is in the range of 2 to 15 μm, more preferably 2 to 10 μm.
[0072]
The emission light distribution of the light source device using the light deflecting element as in the present invention is such that, at the peak position, as the emission light distribution on the primary light source side becomes farther from the peak light, the brightness rapidly decreases, and The outgoing light distribution on the side far from the light source may exhibit an asymmetric outgoing light distribution in which the luminance decreases relatively slowly. For example, when a light source device having such an emitted light distribution is used for a liquid crystal display device requiring a relatively wide viewing angle, such as a notebook personal computer having a size of 10 inches or more, a light diffusing element having a relatively high light diffusing property is subjected to light deflection. 2. Description of the Related Art It has been practiced to dispose on an outgoing light surface of an element to widen an outgoing light distribution to widen a viewing angle. When a light diffusing element having a light diffusing property with a haze value of 50% or more is used, the peak angle of the emitted light distribution is deflected about 1 to 3 degrees farther from the primary light source. Therefore, when the peak angle of the light distribution emitted from the light deflecting element is located in the normal direction of the light exit surface, the peak angle of the light distribution emitted by the light diffusion element is about 1 to 3 degrees from the normal direction from the light source. The light is polarized to the far side, and as a result, the brightness when viewed from the normal direction is extremely reduced. This is because, although the asymmetry of the distribution of the emitted light emitted from the light deflecting element is somewhat reduced by using the light diffusing element, the portion of the emitted light distribution where the luminance decreases relatively sharply is positioned in the normal direction. To do that. In order to avoid such an extreme decrease in luminance, it is preferable that the peak angle of the light distribution emitted from the light deflecting element is inclined in advance by 1 to 3 degrees from the normal direction toward the light source.
[0073]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples. In addition, the measurement of each physical property in the following Examples was performed as follows.
[0074]
Measurement of normal luminance and full width at half maximum of luminous intensity of surface light source device
A cold cathode tube was used as a light source, and DC 12 V was applied to an inverter (HIU-742A manufactured by Harrison) to perform high-frequency lighting. The full width at half maximum luminous intensity of the light guide is fixed to black paper having a pinhole of 4 mmφ on the surface of the light guide so that the pinhole is located at the center of the surface, and the measurement circle of the luminance meter is 8 to 9 mm. The gonio rotation axis was adjusted so as to rotate around the pinhole in a direction perpendicular to and parallel to the longitudinal axis of the cold cathode tube. The luminous intensity distribution of the emitted light was measured with a luminance meter while rotating the rotation axis at an interval of 1 ° from + 80 ° to −80 ° in each direction, and the peak angle and the full width at half maximum of the luminous intensity distribution (1/2 of the peak value) were measured. Angle of distribution). Further, the full width at half maximum of the luminance of the surface light source device was adjusted so that the viewing angle of the luminance meter was 0.1 degree, the central position of the surface light source device was adjusted, and the gonio rotation axis was rotated. While rotating the rotation axis in each direction from + 80 ° to -80 ° at 1 ° intervals, the luminance distribution of the emitted light was measured with a luminance meter, and the peak luminance and peak angle were determined. The peak angle was 0 ° in the normal direction to the light source device, the primary light source side was negative, and the opposite side was positive.
[0075]
Example 1
A light guide having one surface mat (average inclination angle 1.1 degrees) was produced by injection molding using an acrylic resin (Acrypet VH5 # 000 manufactured by Mitsubishi Rayon Co., Ltd.). The light guide had a wedge plate shape of 216 mm × 290 mm and a thickness of 2.0 mm-0.7 mm. On the mirror side of the light guide, a prism row having a prism apex angle of 100 ° and a pitch of 50 μm is formed by an acrylic ultraviolet curing resin so as to be parallel to a side (short side) of the light guide having a length of 216 mm. The prism layers arranged in parallel were formed. A cold-cathode tube is illuminated with a light source reflector (silver reflection film manufactured by Reiko Co., Ltd.) along one side end surface (end surface on the side having a thickness of 2.0 mm) corresponding to the side (long side) having a length of 290 mm of the light guide. Covered and arranged. Further, a light diffusion reflection film (E60 manufactured by Toray Industries, Inc.) was attached to the other side end surface, and a reflection sheet was disposed on the prism array side (back surface). The above configuration was incorporated in a frame. In this light guide, the maximum peak angle of the emitted light luminous intensity distribution in a plane perpendicular to both the light incident surface and the light emitting surface is 70 degrees with respect to the normal direction of the light emitting surface, and the full width at half maximum is 22.5 degrees. Met.
[0076]
On the other hand, using an acrylic ultraviolet curable resin having a refractive index of 1.5064, the cross sections are point 1 (-16.031, 59.828), point 2 (0.000, 0.000), and point 3 (12. 000, 15.695), point 4 (15,000, 19.750), point 5 (18,000, 23.925), point 6 (21,000, 28.320), point 7 (24.000, 32.818), point 8 (27.000, 37.455), point 9 (30.000, 42.238), point 10 (33.000, 47.114), point 11 (36.000, 52. 087) and 12 points (40.469, 59.828) and 12 points (coordinate values are in μm units; the same applies to the following embodiments). The prism row forming surface where the rows are A prism sheet formed on one surface of a polyester film having a thickness of 188 μm was prepared.
[0077]
In this prism sheet, the top distribution angle α was 15 degrees, and the top distribution angle β was 37.4 degrees. The inclination angles of 10 planes corresponding to points 2 to 12 are 52.6 degrees, 53.5 degrees, 54.3 degrees, 55.5 degrees, 56.3 degrees, 57.1 degrees, and 57 degrees, respectively. 9.9, 58.4, 58.9, and 60.0 degrees.
[0078]
The lengths L1 and L2 of the surfaces forming the prism rows with respect to the prism row pitch P of the prism sheet were L2 / P = 1.279 and L2 / L1 = 1.167. The ratio d / P of the maximum distance d between the virtual plane connecting the top and bottom of the prism array and the actual prism surface corresponding to points 2 to 12 to the prism array pitch P was 2.7%. The degree of irregularity of the prism ridge line with respect to the reference line was 0.053, and the degree of irregularity of the prism surface with respect to the reference surface was 0.036.
[0079]
The obtained prism sheet is placed on the first prism surface (point 1 and point 2) with the prism row forming surface facing the light exit surface side of the light guide and the prism ridge line parallel to the light entrance surface of the light guide. (Corresponding to the line connecting... Also in the following examples) on the light source side to obtain a surface light source device. An emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of the surface light source device is obtained, and a peak luminance ratio, a peak angle, and a peak luminance are calculated based on Comparative Example 1 described later. The angle (full width at half maximum) having a luminance of / 2 was measured, and the results are shown in Table 1.
[0080]
Example 2
The cross sections of the prism rows are shown as points 1 (-11.638, 66.002), point 2 (0.000, 0.000), point 3 (9,000, 11.519), point 4 (12,000, 15.443), point 5 (15,000, 19.396), point 6 (18,000, 23.480), point 7 (21,000, 27.686), point 8 (24,000, 32.000). 018), point 9 (27.000, 36.483), point 10 (30.000, 41.067), point 11 (33,000, 45.776), point 12 (36.000, 50.6553) A prism sheet was produced in the same manner as in Example 1 except that the surface was composed of twelve planes having a shape connecting 13 points of point 13 (44.862 and 66.002).
[0081]
In this prism sheet, the top distribution angle α was 10 degrees, and the top distribution angle β was 38 degrees. The inclination angles of the eleven planes corresponding to points 2 to 13 are 52.0 degrees, 52.6 degrees, 52.8 degrees, 53.7 degrees, 54.5 degrees, 55.3 degrees, and 56, respectively. 0.1 degrees, 56.8 degrees, 57.5 degrees, 58.4 degrees, and 60.0 degrees.
[0082]
With respect to the prism row pitch P of the prism sheet, the lengths L1 and L2 of the surfaces forming the prism rows were L2 / P = 1.414 and L2 / L1 = 1.192. The ratio d / P of the maximum distance d between the imaginary plane connecting the top and bottom of the prism array and the actual prism surface corresponding to points 2 to 13 to the prism array pitch P was 3.3%. The degree of irregularity of the prism ridge line with respect to the reference line was 0.053, and the degree of irregularity of the prism surface with respect to the reference surface was 0.036.
[0083]
The prism sheet thus obtained is arranged such that the prism row forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incidence surface of the light guide, and the first prism surface faces the light source side. And a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0084]
Example 3
The prism array is divided into points 1 (-11.605, 65.814), point 2 (0.000, 0.000), point 3 (9,000, 11.519), and point 4 (15,000, 19.396), and a radius from point 4 to point 5 (36.000, 50.6553) centered on point A (-314.871, 263.703). 489 circle, two convex curved surfaces connected from point 5 to point 6 (44.895, 65.814) by a circle with a radius of 629.574 centered on point B (−502.516, 376.7787). A prism sheet was produced in the same manner as in Example 2, except that the above configuration was adopted.
[0085]
In this prism sheet, the top distribution angle α was 10 degrees, and the top distribution angle β was 38 degrees. The inclination angles of two planes corresponding to points 2 to 4 and two convex curved surfaces corresponding to points 4 to 6 are 52.0 degrees, 52.7 degrees, 56.1 degrees, and 59.degree. 6 degrees.
[0086]
With respect to the prism row pitch P of the prism sheet, the lengths L1 and L2 of the surfaces forming the prism rows were L2 / P = 1.412 and L2 / L1 = 1.194. The ratio d / P of the maximum distance d between the virtual plane connecting the top and bottom of the prism array and the actual prism surface corresponding to points 2 to 6 to the prism array pitch P was 3.1%. The degree of irregularity of the prism ridge line with respect to the reference line was 0.053, and the degree of irregularity of the prism surface with respect to the reference surface was 0.036.
[0087]
The prism sheet thus obtained is arranged such that the prism row forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incidence surface of the light guide, and the first prism surface faces the light source side. And a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0088]
Example 4
The prism rows were cross-sectioned at point 1 (-6.292, 71.920), point 2 (0.000, 0.000), point 3 (9,000, 10.996), point 4 (12,000, 14.687), point 5 (15,000, 18.527), point 6 (18,000, 22.494), point 7 (21,000, 26.563), point 8 (24.000, 30. 753), point 9 (27.000, 35.070), point 10 (30.000, 39.517), point 11 (33,000, 44.050), point 12 (36.000, 48.669). , Point 13 (39.000, 53.378), point 14 (42,000, 58.179), point 15 (45,000, 63.114), and point 16 (50.208, 71.920). Example except that it was composed of 15 planes having a shape connecting 16 points To prepare a prism sheet in the same manner as.
[0089]
In this prism sheet, the top distribution angle α was 5 degrees, and the top distribution angle β was 39.3 degrees. The inclination angles of the 14 planes corresponding to points 2 to 16 are 50.7 degrees, 50.9 degrees, 52.0 degrees, 52.9 degrees, 53.6 degrees, 54.4 degrees, and 55 degrees, respectively. 0.2, 56.0, 56.5, 57.0, 57.5, 58.0, 58.7, and 59.4 degrees.
[0090]
The lengths L1 and L2 of the surfaces forming the prism rows with respect to the prism row pitch P of the prism sheet were L2 / P = 1.555 and L2 / L1 = 1.217. The ratio d / P of the maximum distance d between the virtual plane connecting the top and bottom of the prism array and the actual prism surface corresponding to the points 2 to 16 to the prism array pitch P was 3.7%. The degree of irregularity of the prism ridge line with respect to the reference line was 0.053, and the degree of irregularity of the prism surface with respect to the reference surface was 0.036.
[0091]
The prism sheet thus obtained is arranged such that the prism row forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incidence surface of the light guide, and the first prism surface faces the light source side. And a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0092]
Example 5
The prism rows were cross-sectioned at point 1 (−6.322, 72.265), point 2 (0.000, 0.000), point 3 (12,000, 14.687), and point 4 (15,000, 18.527) and three planes connecting the four points, and a radius 376. from the point 4 to the point 5 (30.000, 39.517) centered on the point A (-283.909, 247.987). 827, two convex curved surfaces connected from point 5 to point 6 (50.178, 72.265) by a circle having a radius of 490.235 centered on point B (-376.959, 312.857) A prism sheet was manufactured in the same manner as in Example 4, except that the above configuration was adopted.
[0093]
In this prism sheet, the top distribution angle α was 5 degrees, and the top distribution angle β was 39.3 degrees. The inclination angles of two planes corresponding to points 2 to 4 and two convex curved surfaces corresponding to points 4 to 6 are 50.7 degrees, 52.0 degrees, 54.4 degrees, and 58.degree. 4 degrees.
[0094]
With respect to the prism row pitch P of the prism sheet, the lengths L1 and L2 of the surfaces forming the prism rows were L2 / P = 1.560 and L2 / L1 = 1.215. The ratio d / P of the maximum distance d between the virtual plane connecting the top and bottom of the prism array and the actual prism surface corresponding to points 2 to 6 to the prism array pitch P was 3.9%. The degree of irregularity of the prism ridge line with respect to the reference line was 0.053, and the degree of irregularity of the prism surface with respect to the reference surface was 0.036.
[0095]
The prism sheet thus obtained is arranged such that the prism row forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incidence surface of the light guide, and the first prism surface faces the light source side. And a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0096]
Example 6
The prism array is formed by connecting a plane having a cross section connecting two points 1 (-11.596, 65.767) and 2 (0.000, 0.000), and a point 2 to a point 3 (44.904). , 65.767) in the same manner as in the first embodiment except that a single convex curved surface connected by a circle having a radius of 466.137 centered on the point A (-361.105, 294.766) is used. A prism sheet was produced.
[0097]
In this prism sheet, the top distribution angle α was 10 degrees, and the top distribution angle β was 34.3 degrees. The inclination angle of one convex surface corresponding to points 2 to 3 was 55.7 degrees.
[0098]
With respect to the prism row pitch P of the prism sheet, the lengths L1 and L2 of the surfaces forming the prism rows were L2 / P = 1.409 and L2 / L1 = 1.192. The ratio d / P of the maximum distance d between the imaginary plane connecting the top and bottom of the prism array and the actual prism surface corresponding to the points 2 to 3 to the prism array pitch P was 3.0%. The degree of irregularity of the prism ridge line with respect to the reference line was 0.053, and the degree of irregularity of the prism surface with respect to the reference surface was 0.036.
[0099]
The prism sheet thus obtained is arranged such that the prism row forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incidence surface of the light guide, and the first prism surface faces the light source side. And a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0100]
Example 7
The prism array is composed of one plane having a cross section connecting two points, point 1 (-16.005, 59.730) and point 2 (0.000, 0.000), and point 2 to point 3 (30.000). , 42.238) to a circle of radius 456.044 centered at point A (-356.204, 284.772), and point B (−0.495, 59.730) to point B (− A prism sheet was produced in the same manner as in Example 1, except that the prism sheet was composed of two convex curved surfaces connected by a circle with a radius of 660.857 centered on (531.365, 390.952).
In this prism sheet, the top distribution angle α was 15 degrees, and the top distribution angle β was 35.4 degrees. The inclination angles of the two convex curved surfaces corresponding to points 2 to 4 were 54.6 degrees and 59.0 degrees, respectively.
[0101]
With respect to the prism row pitch P of the prism sheet, the lengths L1 and L2 of the surfaces forming the prism rows were L2 / P = 1.277 and L2 / L1 = 1.167. The ratio d / P of the maximum distance d between the virtual plane connecting the top and bottom of the prism array and the actual prism surface corresponding to points 2 to 4 to the prism array pitch P was 2.5%. The degree of irregularity of the prism ridge line with respect to the reference line was 0.053, and the degree of irregularity of the prism surface with respect to the reference surface was 0.036.
[0102]
The prism sheet thus obtained is arranged such that the prism row forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incidence surface of the light guide, and the first prism surface faces the light source side. And a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0103]
Example 8
A prism array is formed by connecting a plane having a cross section connecting two points, point 1 (−14.1776, 61.4101) and point 2 (0.000, 0.000), and a point from point 2 to point 3 (42.3224). , 61.4101) was formed in the same manner as in Example 1 except that a circle having a radius of 504.3237 centered on point A (-392.9609, 316.1078). The lengths L1 and L2 of the surfaces forming the prism rows with respect to the prism row pitch P of the prism sheet were L2 / P = 1.320 and L2 / L1 = 1.183.
[0104]
Example 9
A prism sheet was manufactured in the same manner as in Example 8, except that the prism row was such that a flat portion was provided at a position 3 μm from the trough of the prism in the height direction of the prism.
[0105]
Example 10
A prism sheet was produced in the same manner as in Example 8, except that the prism array was such that a flat portion was provided at a position 5 μm from the trough of the prism in the height direction of the prism.
[0106]
Example 11
A prism sheet was manufactured in the same manner as in Example 8, except that the prism row was such that a flat portion was provided at a position 7 μm from the trough of the prism in the height direction of the prism.
[0107]
Example 12
A prism sheet was produced in the same manner as in Example 8, except that the prism row was such that a flat portion was provided at a position 10 μm from the trough of the prism in the height direction of the prism.
[0108]
Example 13
The prism array is formed by connecting a plane having a cross section connecting two points, point 1 (-19.7523, 54.2691) and point 2 (0.000, 0.000), and a point from point 2 to point 3 (36.76767). , 54.2691), except that a circle with a radius of 468.9151 centered on point A (-368.9514, 289.4066) was used, to produce a prism sheet in the same manner as in Example 1. With respect to the prism row pitch P of the prism sheet, the lengths L1 and L2 of the surfaces forming the prism rows were L2 / P = 1.160 and L2 / L1 = 1.135.
[0109]
Comparative Example 1
Example 1 was the same as Example 1 except that the prism row of the prism sheet was an isosceles triangle in cross section (α = β = 32.7 degrees) in which the two prism surfaces were both flat and the prism apex angle was 65.4 degrees. Similarly, a surface light source device was obtained. An outgoing light luminance distribution in a plane perpendicular to both the light incident surface and the light emitting surface of the surface light source device is obtained, the peak luminance is set to 1.00, the peak angle, and the angle having half of the peak luminance. (Full width at half maximum) was measured, and the results are shown in Table 1.
[0110]
Comparative Example 2
The prism array of the prism sheet is the same as that of the first embodiment except that the two prism surfaces are both flat, the top distribution angle α of one surface is 5 degrees, and the top distribution angle β of the other surface is 38 degrees. Thus, a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0111]
Comparative Example 3
The same as Example 1 except that the prism array of the prism sheet was such that the two prism surfaces were both flat, the top distribution angle α of one surface was 5 degrees, and the top distribution angle β of the other surface was 35 degrees. Thus, a surface light source device was obtained. The emission light luminance distribution in a plane perpendicular to both the light incident surface and the light emission surface of this surface light source device is obtained, and the peak luminance ratio, peak angle, and 1/2 of the peak luminance based on Comparative Example 1 are determined. Were measured (full width at half maximum), and the results are shown in Table 1.
[0112]
[Table 1]

[0113]
【The invention's effect】
As described above, according to the present invention, at least one of the prism surfaces constituting the prism array formed on the light entrance surface of the light deflecting element is a non-single plane, and the top distribution angle α of one of the prism surfaces is α. Is set to 2 to 25 degrees, and the apex distribution angle β of the other prism surface is set to 33 to 40 degrees, so that the light emitted from the primary light source is concentrated and emitted in a required observation direction (the efficiency of the light amount of the primary light source). A light source device with good utilization efficiency) can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a light source device according to the present invention.
FIG. 2 is an explanatory diagram of a shape of a prism array on a light incident surface of the light deflecting element of the present invention.
FIG. 3 is an explanatory diagram illustrating various light distributions emitted from a light deflection element.
FIG. 4 is an explanatory view showing various light distributions emitted from a light deflection element.
FIG. 5 is an explanatory diagram showing various light distributions emitted from a light deflection element.
FIG. 6 is an explanatory diagram showing various light distributions emitted from a light deflection element.
FIG. 7 is an explanatory diagram showing various light distributions emitted from a light deflection element.
FIG. 8 is an explanatory diagram illustrating various distributions of emitted light from a light deflection element.
FIG. 9 is an explanatory diagram illustrating various distributions of emitted light from a light deflection element.
FIG. 10 is an explanatory diagram showing various light distributions emitted from a light deflection element.
FIG. 11 is an explanatory diagram showing various light distributions emitted from a light deflecting element.
FIG. 12 is an explanatory diagram showing various light distributions emitted from a light deflection element.
FIG. 13 is an explanatory diagram illustrating various light distributions emitted from a light deflection element.
FIG. 14 is an explanatory diagram showing distributions of various emitted lights from the light deflection element.
FIG. 15 is an explanatory diagram showing a difference in refraction of light and a difference in length of a prism cross section due to a difference in the inclination angle of the prism surface.
FIG. 16 is an explanatory diagram showing a difference in refraction of light and a difference in length of a prism cross section due to a difference in the inclination angle of the prism surface.
FIG. 17 is an explanatory diagram of the shape of a prism array on the light incident surface of the light deflecting element of the present invention.
FIG. 18 is a perspective view in which a substantially point light source is disposed adjacent to a corner of a light guide.
FIG. 19 is an explanatory diagram of the full width at half maximum of the emitted light distribution.
FIG. 20 is an explanatory diagram of the shape of a prism array on the light incident surface of the light deflection element of the present invention.
[Explanation of symbols]
1 Primary light source
2 Light source reflector
3 Light guide
4 Light deflection element
5 Light reflection element
6 Light diffusion element
31 Light incident end face
32 end face
33 Light exit surface
34 Back
41 Light incident surface
42 Light emitting surface
43 Prism row forming plane
44 First prism surface
45 Second prism surface
46-50 plane
51,52 convex curved surface
59 Flat part

Claims (27)

It has a light incident surface on which light is incident and a light exit surface which is located on the opposite side and emits incident light, and the light incident surface is provided with a plurality of prism rows composed of two prism surfaces in parallel with each other. And at least one of the two prism surfaces is formed of a non-single plane, and the top distribution angle α of one of the prism surfaces constituting the prism array is 2 to 25 degrees and the top distribution angle β of the other prism surface Is 33 to 40 degrees. The light deflecting element according to claim 1, wherein one of the two prism surfaces is formed of a non-single plane and the other is formed of a single plane. The light deflecting element according to claim 1, wherein the non-single plane includes at least one convex curved surface. The optical deflecting element according to claim 1, wherein the non-single plane includes two or more planes having different inclination angles. The light deflecting element according to claim 1, wherein the non-single plane includes two or more convex curved surfaces having different inclination angles. The light deflecting element according to claim 1, wherein the non-single plane includes one or more planes and one or more convex curved surfaces. The light deflecting element according to any one of claims 4 to 6, wherein the non-single plane has a larger inclination angle as the plane or the convex curved surface located closer to the light exit surface. The difference between the inclination angle of the surface closest to the top of the prism array and the inclination angle of the surface closest to the light exit surface in the non-single plane is 1 ° to 15 °. The light deflecting element according to any one of claims 1 to 7. In the light that is totally reflected on each of the planes and / or the convex curved surfaces constituting the non-single plane and exits from the light exit surface, the direction of the peak of the exit light distribution for each surface is the direction of the prism row. The light deflecting element according to claim 3, wherein the light deflecting element is in a direction substantially normal to a plane formed. In the cross section of the prism array, when the coordinates of the vertex are set as the origin and the length of the pitch P of the prism array is normalized to 1, point 1 (−0.111, 1.27) and point 2 (0 0.0, 0.0), point 3 (0.159, 0.195), point 4 (0.212, 0.260), point 5 (0.265, 0.328), point 6 (0.319 , 0.398), point 7 (0.372, 0.470), point 8 (0.425, 0.544), point 9 (0.478, 0.621), point 10 (0.531, 0 .699), point 11 (0.584, 0.780), point 12 (0.637, 0.861), point 13 (0.690, 0.945), point 14 (0.743, 1.030). ), Point 15 (0.796, 1.117), and point 16 (0.889, 1.27), or a shape connecting the points in the vicinity thereof. Characterized in that the light deflecting element according to claim 1. When the length of the pitch P of the prism array is normalized to 1 in the cross section of the prism array, at least five points selected from the points 1 to 16 have a radius of 0.021 centered on that point. The light deflecting element according to claim 10, wherein the light deflecting element has a shape connected by using the neighboring points in the circle. In the cross section of the prism array, when the coordinates of the apex are set as the origin and the length of the pitch P of the prism array is normalized to 1, point 1 (−0.206, 1.168) and point 2 (0 .000, 0.000), point 3 (0.159, 0.204), point 4 (0.212, 0.273), point 5 (0.265, 0.343), point 6 (0.319 , 0.416), point 7 (0.372, 0.490), point 8 (0.425, 0.567), point 9 (0.478, 0.646), point 10 (0.531, 0 .727), point 11 (0.584, 0.810), point 12 (0.637, 0.897), point 13 (0.794, 1.168), or a shape connecting 13 points in the vicinity thereof The light deflecting element according to claim 1, comprising: When the length of the pitch P of the prism rows is normalized to 1 in the cross section of the prism row, at least five points selected from the points 1 to 13 have a radius of 0.021 centered on the point. 13. The light deflecting element according to claim 12, wherein the light deflecting element has a shape connected by using the neighboring points in the circle. In the cross section of the prism array, when the coordinates of a vertex are set as the origin and the length of the pitch P of the prism array is normalized to 1, point 1 (−0.284, 1.059) and point 2 (0 .000, 0.000), point 3 (0.212, 0.278), point 4 (0.265, 0.350), point 5 (0.319, 0.423), point 6 (0.372) , 0.501), point 7 (0.425, 0.581), point 8 (0.478, 0.663), point 9 (0.531, 0.748), point 10 (0.584, 0 .834), a point 11 (0.637, 0.922), and a point 12 (0.716, 1.059), or a point in the vicinity thereof, and a point connected thereto. The light deflecting element as described in the above. When the length of the pitch P of the prism array is normalized to 1 in the cross section of the prism array, at least five points selected from the points 1 to 12 have a radius of 0.021 around the point. 15. The light deflecting element according to claim 14, wherein the light deflecting element has a shape connected by using the neighboring points in the circle. The pitch P of the prism rows and the length L2 of an imaginary straight line connecting the prism tops and valleys in the cross-sectional shape of the prism surface at the top distribution angle β constituting the prism rows are L2 / P = 1. The light deflecting device according to claim 1, wherein a relationship of 1 to 1.7 is satisfied. In the cross-sectional shape of the prism surface at the top distribution angle α, the length L1 of a virtual straight line connecting the prism top and the valley is connected, and at the cross-sectional shape of the prism surface at the top distribution angle β, the prism top and the valley are connected. 17. The optical deflection element according to claim 1, wherein a length L2 of the virtual straight line satisfies a relationship of L2 / L1 = 1.1 to 1.3. When the length of the pitch P between the prism rows is normalized to 1, the ridge formed by the two prism surfaces forming the prism row is formed in an uneven shape of 0.018 to 0.354 with respect to the reference line. The light deflecting element according to claim 1, wherein: When the length of the pitch P of the prism array is normalized to 1, the two prism surfaces forming the prism array are formed in an uneven shape of 0.012 to 0.334 with respect to the reference surface. The light deflecting element according to claim 1, wherein: 20. The light deflecting element according to claim 1, wherein a flat portion is provided between adjacent prism rows. 21. The optical deflecting element according to claim 20, wherein the flat portion is provided at a position of 2 to 10 [mu] m from the prism valley in the height direction of the prism row. The flat portion is provided at a position of 0.035 to 0.18 in the height direction of the prism row from the prism trough when the length of the pitch P of the prism row is normalized to 1. The light deflecting element according to claim 20, wherein When the flat portion normalizes the length L2 of an imaginary straight line connecting the prism top and the prism valley to 1 in the cross-sectional shape of the prism surface at the top distribution angle β, the height of the prism row from the prism valley The light deflecting element according to claim 20, wherein the light deflecting element is provided at a position of 0.022 to 0.16 in the direction. A light guide having a primary light source, a light incident surface on which light emitted from the primary light source is incident, and a light exit surface for guiding the incident light and emitting the guided light; A light source device comprising: the light deflecting element according to any one of claims 1 to 23, wherein the light deflecting element is disposed so as to face the light exit surface of the light body. The light deflecting element is arranged such that the prism surface having a top distribution angle α of the prism array is closer to the primary light source, and the prism surface having a top distribution angle β of the prism array is farther from the primary light source. The light source device according to claim 24, wherein the light source device is provided. The said primary light source is arrange | positioned adjacent to the corner part of the said light guide, The prism row of the said light deflection element is arrange | positioned substantially concentrically centering on the said primary light source substantially, The Claims characterized by the above-mentioned. The light source device according to 24 or 25. The light deflecting element further includes a light diffusing element disposed adjacent to the light exit surface, wherein the light diffusing element has an anisotropic full width at half maximum of an emitted light distribution when parallel light is incident. The light source device according to any one of claims 24 to 26, wherein the light source device has a feature.

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