JP4960327B2 - Light deflection element and light source device - Google Patents

Description

  The present invention relates to an edge-light-type light source device and a light deflecting element used therefor that constitute a liquid crystal display device used as a display unit in a notebook computer, a liquid crystal television, a mobile phone, a portable information terminal, etc. In particular, the present invention relates to an improvement in a light deflection element disposed on the light exit surface side of a light guide of a light source device.

  In recent years, color liquid crystal display devices have been widely used in various fields as monitors for portable notebook personal computers, personal computers, etc., or as display units for liquid crystal televisions, video integrated liquid crystal televisions, mobile phones, personal digital assistants, and the like. Yes. In addition, with the increase in the amount of information processing, diversification of needs, compatibility with multimedia, and the like, liquid crystal display devices have been increased in screen size and definition.

  The liquid crystal display device basically includes a backlight unit and a liquid crystal display element unit. As the backlight unit, there are a direct type with a primary light source arranged directly below the liquid crystal display element unit, and an edge light type with a primary light source arranged so as to face the side end face of the light guide. From the viewpoint of downsizing, the edge light method is often used.

  By the way, in recent years, in a display device having a relatively small screen size and a relatively narrow viewing direction range, for example, a liquid crystal display device used as a display unit of a mobile phone, the edge light system is used from the viewpoint of reducing power consumption. In order to effectively use the amount of light emitted from the primary light source, a backlight unit has been used that emits light by concentrating it in a required angle range by making the spread angle of the light beam emitted from the screen as small as possible. Yes.

  As a light source device that emits light in a concentrated manner in a relatively narrow range in order to increase the use efficiency of the light amount of the primary light source and reduce the power consumption, the display device has a limited observation direction range as described above. In Japanese Patent Laid-Open No. 2001-143515 (Patent Document 2), it is proposed to use a prism sheet having prism forming surfaces on both sides adjacent to the light emitting surface of the light guide. In this double-sided prism sheet, a plurality of prism rows parallel to each other are formed on the light incident surface that is one surface and the light exit surface that is the other surface, and the prism row direction is formed by the light incident surface and the light exit surface. And the prism rows are arranged at corresponding positions. Thus, the light emitted from the light exit surface of the light guide having a peak of the emitted light in a direction inclined with respect to the light exit surface and distributed in an appropriate angle range is transmitted to one of the light incident surfaces of the prism sheet. The light can be concentratedly emitted in a relatively narrow required direction by entering from the prism surface, reflecting the inner surface by the other prism surface, and further receiving the refracting action of the prism on the light exit surface.

  However, according to such a light source device, concentrated emission in a narrow angle range is possible, but a plurality of prism rows parallel to each other as a prism sheet used as a light deflecting element are arranged on a light incident surface and a light output surface. Therefore, it is necessary to match the prism row directions and to arrange the prism rows at corresponding positions, which complicates the molding.

In Japanese Patent Laid-Open No. 10-254371 (Patent Document 1), the inclination angle α of one surface constituting the prism row is 4.7 to 5.7 degrees, and the inclination angle β of the other surface is 34.2 to 35 degrees. However, since the other surface is a flat surface, a sufficient effect is not obtained.
JP-A-10-254371 JP 2001-143515 A

  Therefore, an object of the present invention is to control the distribution of the emitted light so as to be very narrow and to improve the utilization efficiency of the light quantity of the primary light source (that is, to concentrate the light emitted from the primary light source in the required observation direction). It is an object of the present invention to provide a light deflection element and a light source device that can easily improve image quality with a simplified configuration.

According to the present invention, the above object is achieved as follows:
A light incident surface on which light is incident, and a light exit surface on the opposite side that emits incident light. The light incident surface includes a plurality of prism rows each composed of two prism surfaces in parallel with each other. And at least one of the two prism surfaces is a non-single plane, and the top distribution angle α of one prism surface constituting the prism row is 2 to 25 degrees, and the top distribution angle β of the other prism surface An optical deflection element characterized in that the angle is 33 to 40 degrees,
Is provided. In the present invention, a non-single plane means a plane other than a plane consisting of a single plane.

In particular, according to the present invention,
It has a light incident surface on which light is incident and a light exit surface on the opposite side that emits incident light,
A plurality of prism rows composed of two prism surfaces are arranged in parallel on the light incident surface, and at least one of the two prism surfaces is a non-single plane,
The top portion distribution angle α of one prism surface constituting the prism row is 2 to 25 degrees, and the top portion distribution angle β of the other prism surface is 33 to 40 degrees,
The difference | α−β | between the top distribution angle α and the top distribution angle β is 8 to 35 degrees,
The pitch P of the prism row and the length L2 of the imaginary straight line connecting the prism top and the trough in the cross-sectional shape of the prism surface with the apex distribution angle β constituting the prism row are L2 / P = 1. An optical deflection element satisfying a relationship of 16 to 1.6,
Is provided.

  In one aspect of the present invention, the non-single plane includes a plurality of planes and / or convex curved surfaces, and a plane or convex curved surface located closer to the light exit surface has a larger inclination angle. In one aspect of the present invention, the non-single plane includes at least one plane at a portion near the top of the prism row, and at least one convex curved surface at a side near the valley portion of the prism row. The boundary between the plane and the convex curved surface is located at 30% or less of the height of the prism row from the top.

  In one aspect of the present invention, the prism row has a point 1 (-11.605, 65.814) and a point 2 (0.000, 0.000) when the coordinates of the vertex are the origin in the cross section. , Point 3 (9.00, 11.519), point 4 (15.000, 19.396), or a plurality of planes connecting points in the vicinity thereof, point 4 and point 5 (36.000, 50) .653) having a radius of 410.489 connecting the two points or its neighboring points, and having a radius of 629.574 connecting the two points of points 5 and 6 (44.895, 65.814) or their neighboring points. It consists of circular arcs.

  In one aspect of the present invention, the prism array has a point 1 (−6.322, 72.265) and a point 2 (0.000, 0.000) when the coordinates of the vertex are the origin in the cross section. , Point 3 (12.000, 14.687), point 4 (15.000, 18.527), or a plurality of planes connecting points in the vicinity thereof, 4 and point 5 (30.000, 39. 517) and an arc with a radius of 376.827 that connects the two points or its neighboring points, and an arc with a radius of 490.235 that connects the two points of point 5 and point 6 (50.178, 72.265) or their neighboring points. , Are connected to each other.

  In one aspect of the present invention, one of the two prism surfaces is a non-single plane and the other is a single plane.

  In one aspect of the present invention, the non-single plane is composed of at least one convex curved surface.

  In one aspect of the present invention, the non-single plane is composed of two or more planes having different inclination angles, or two or more convex curved surfaces having different inclination angles, or one or more planes. It consists of one or more convex curved surfaces. In one aspect 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 exit surface.

  In one aspect of the present invention, in the non-single plane, a difference between an inclination angle of a surface closest to the top of the prism row and an inclination angle of a surface closest to the light exit surface is 1 ° to 15 °. In one aspect of the present invention, in the light that is totally reflected by each surface of the plane and / or the convex curved surface constituting the non-single plane and is emitted from the light exit surface, The direction of the peak is a substantially normal direction of the plane on which the prism row is formed.

  In one aspect of the present invention, when the prism array has a vertex coordinate in the cross section and the length of the pitch P of the prism array is normalized to 1, 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.

  In one aspect of the present invention, when the prism array has a vertex coordinate in the cross section and the length of the pitch P of the prism array is normalized to 1, 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), point 13 (0.794, 1.168) It consists of a shape that connects.

  In one aspect of the present invention, when the prism row has a vertex coordinate in the cross section and the length of the pitch P of the prism row is normalized to 1, 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 (0.531, 0.748), It consists of 12 points of point 10 (0.584, 0.834), point 11 (0.637, 0.922), and point 12 (0.716, 1.059).

  In one aspect of the present invention, when the length of the pitch P of the prism row is normalized to 1 in the cross section of the prism row, at least 5 points selected from the 16 points, 13 points, or 12 points are used. Is formed by connecting the neighboring points in a circle having a radius of 0.021 centered on the point.

  In one aspect of the present invention, the pitch P of the prism rows and the length L2 of an imaginary straight line connecting the prism top and the valley in the cross-sectional shape of the prism surface at the apex distribution angle β constituting the prism row, Satisfies the relationship of L2 / P = 1.1 to 1.7. In one aspect of the present invention, the length L1 of the imaginary straight line connecting the prism apex and the valley in the cross-sectional shape of the prism surface at the apex distribution angle α and the prism in the cross-sectional shape of the prism surface at the apex 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.

  In one aspect of the present invention, when the ridge line formed by the two prism surfaces constituting the prism row normalizes the length of the pitch P of the prism row as 1, it is 0.018 to the reference line. It is formed in an uneven shape of 0.354. In one aspect of the present invention, when two prism surfaces constituting the prism row normalize the length of the pitch P of the prism row as 1, 0.012 to 0.334 with respect to the reference surface. It is formed in the uneven shape.

  In one embodiment of the present invention, a flat portion is provided between adjacent prism rows. In one aspect 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 trough. In one aspect of the present invention, the flat portion has a position of 0.035 to 0.18 in the height direction of the prism row from the prism valley when the length of the pitch P of the prism row is normalized to 1. Is provided. In one aspect of the present invention, when the flat portion normalizes the length L2 of the imaginary straight line connecting the prism apex and the prism trough in the cross-sectional shape of the prism surface at the apex 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 valley.

In addition, according to the present invention, the above-mentioned object is achieved as follows:
A primary light source, a light guide having a light incident surface on which light emitted from the primary light source is incident, and having a light emitting surface that guides the incident light and emits the guided light; and A light source device comprising: the light deflection element disposed so that the light incident surface is positioned opposite to the light emitting surface of a light body;
Is provided.

  In one aspect of the present invention, the light deflection element is arranged such that the prism surface with the top distribution angle α of the prism array is closer to the primary light source, and the prism surface with the top distribution angle β of the prism array is It is arranged on the side far from the primary light source.

  In one aspect of the present invention, the primary light source is disposed adjacent to a corner portion of the light guide, and the prism array of the light deflection element is disposed substantially concentrically with the primary light source as a substantial center. .

  In one aspect of the present invention, the light diffusing element is 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 the outgoing light distribution when parallel light is incident thereon. It has sex.

  According to the present invention, at least one of the prism surfaces constituting the prism array formed on the light incident surface of the light deflection element is a non-single plane, and the top distribution angle α of one prism surface is 2 to 25 degrees. A light source with good efficiency (the use efficiency of the amount of light of the primary light source) for concentrating and emitting the light emitted from the primary light source in the required observation direction by setting the apex distribution angle β of the other prism surface to 33 to 40 degrees. An apparatus can be provided.

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

  FIG. 1 is a schematic perspective view showing one embodiment of a surface light source device according to the present invention. As shown in FIG. 1, the surface light source device of the present embodiment has a light guide 3 in which at least one side end surface is a light incident surface 31 and one surface substantially orthogonal thereto is a light emitting surface 33. And a linear or bar-shaped primary light source 1 disposed opposite to the light incident surface 31 of the light guide 3 and covered with the light source reflector 2, and light disposed on the light emitting surface 33 of the light guide 3. The deflecting element 4 and the light diffusing element 6 disposed on the deflecting element 4 and the light reflecting element 5 disposed to face the back surface 34 opposite to the light emitting surface 33 of the light guide 3 are configured.

  The light guide 3 is arranged in parallel with the XY plane and has a rectangular plate shape as a whole. The light guide 3 has four side end surfaces, and at least one side end surface of the 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 disposed on other side end surfaces such as the side end surface 32 opposite to the light incident surface 31.

  The two principal surfaces substantially orthogonal to the light incident surface 31 of the light guide 3 are respectively positioned substantially parallel to the XY plane, and one of the surfaces (upper surface in the drawing) serves as the light emitting surface 33. At least one of the light exit surface 33 and the back surface 34 opposite to the light exit surface 33 is provided with a rough directional light exit function unit, a prism array, a lenticular lens array, and a number of lens arrays such as a V-shaped groove. By providing a directional light emitting function unit including a lens surface formed in parallel with the light incident surface 31, the light incident surface 31 is guided while the light incident from the light incident surface 31 is guided through the light guide 3. Light having directivity is emitted from the light distribution surface 33 (XZ plane) orthogonal to the light incident surface 31 and the light emitting surface 33. If the angle formed by the peak direction of the emitted light distribution in the XZ in-plane distribution with the light emitting surface 33 is a, this angle a is preferably 10 to 40 degrees, and the full width at half maximum of the emitted light distribution is 10 to 40. It is preferable to set the degree.

  The rough surface and the lens array formed on the surface of the light guide 3 have a luminance within the light emitting surface 33 that the average inclination angle θa according to ISO 4287 / 1-1984 is in the range of 0.5 to 15 degrees. It is preferable from the point of aiming at the degree of 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. The average inclination angle θa is preferably set in an optimum range by a ratio (L / t) between the thickness (t) of the light guide 3 and the length (L) in the direction in which the incident light propagates. That is, when the light guide 3 having a L / t of more than 20 and about 200 or less is used, the average inclination angle θa is preferably 0.5 to 7.5 degrees, and more preferably 1 to 5 It is the range of degrees, More preferably, it is the range of 1.5-4 degrees. When the light guide 3 having L / t of about 20 or less is used, the average inclination angle θa is preferably 7 to 12 degrees, and more preferably 8 to 11 degrees.

  The average inclination angle θa of the rough surface formed on the light guide 3 is obtained in accordance with ISO 4287 / 1-1984 by measuring the rough surface shape using a stylus type surface roughness meter and setting the coordinate in the measurement direction as x. From the obtained gradient function f (x), the following equation (1) and equation (2) can be used. Here, L is the measurement length, and Δa is the tangent of the average inclination angle θa.

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%, and more preferably in the range of 1 to 3%. This is because when the light emission rate is smaller than 0.5%, the amount of light emitted from the light guide 3 tends to be small and sufficient luminance cannot be obtained. When the light emission rate is larger than 5%, the vicinity of the primary light source 1 is present. This is because a large amount of light is emitted, the attenuation of light in the X direction within the light emitting surface 33 becomes significant, and the luminance uniformity on the light emitting surface 33 tends to decrease. Thus, by setting the light emission rate of the light guide 3 to 0.5 to 5%, the angle (peak angle) of the peak light in the light distribution of the light emitted from the light emission surface is the normal of the light emission surface. With a high directivity, such that the full width at half maximum of the emitted light distribution in the XZ plane perpendicular to both the light incident surface and the light emitting surface is 10 to 40 degrees. Can be emitted from the light guide 3, the emission direction can be efficiently deflected by the light deflection element 4, and a surface light source element having high luminance can be provided.

In the present invention, the light emission rate from the light guide 3 is defined as follows. The relationship between the light intensity (I ₀ ) of the emitted light at the edge on the light incident surface 31 side of the light emitting surface 33 and the emitted light intensity (I) at a distance L from the edge on the light incident surface 31 side is If the thickness (dimension in the Z direction) of the light guide 3 is t, the following relationship (3) is satisfied.

I = I ₀ · A (1-A) ^{L / t} (3)
Here, the constant A is the light output rate, and the light guide 3 per unit length (a length corresponding to the light guide thickness t) in the X direction orthogonal to the light incident surface 31 on the light output surface 33. It is the ratio (%) at which light is emitted from. The light emission rate A is obtained from the gradient by plotting the relationship between the logarithm of the light intensity of the light emitted from the light exit surface 23 on the vertical axis and (L / t) on the horizontal axis. Can do.

  Moreover, in order to control the directivity on the surface (YZ plane) parallel to the primary light source 1 of the emitted light from the light guide 3 on the other main surface to which the directional light emitting function unit is not provided, It is preferable to form a lens surface in which a large number of lens rows extending in a direction substantially perpendicular to the light incident surface 31 (X direction) are arranged. In the embodiment shown in FIG. 1, a lens surface formed by an array of a large number of lens rows, in which a rough surface is formed on the light emitting surface 33 and the back surface 34 extends in a direction substantially perpendicular to the light incident surface 31 (X direction). Is forming. In the present invention, conversely 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 a rough surface.

  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, a lenticular lens array, and a V-shaped groove extending substantially in the X direction. However, it is preferable that the YZ section has a substantially triangular prism array.

  When this prism row is formed, the apex angle is preferably in the range of 70 to 150 degrees. This is because the light emitted from the light guide 3 can be sufficiently condensed by setting the apex angle within this range, and the luminance as the surface light source device can be sufficiently improved. That is, by setting the prism apex angle within this range, the condensed emitted light including the peak light in the emitted light distribution and having a full width at half maximum of 35 to 65 degrees on the surface perpendicular to the XZ plane is emitted. The luminance as a surface light source element can be improved. When the prism row is formed on the light emitting surface 33, the apex angle is preferably in the range of 80 to 100 degrees. When the prism row is formed on the back surface 34, the apex angle is 70 to 80 degrees. Or it is preferable to set it as the range of 100-150 degree | times.

  In the present invention, light diffusing fine particles are mixed and dispersed in the light guide instead of or in combination with the light emitting surface 33 or the back surface 34 as described above. What provided the directional light emission function may be used. Further, the light guide 3 is not limited to the cross-sectional shape as shown in FIG. 1, but can have various cross-sectional shapes such as a wedge shape and a hull shape.

  FIG. 2 is an explanatory diagram of the shape of the prism row in the light deflection element 4. The light deflection element 4 has one of the main surfaces as a light incident surface 41 and the other surface as a light emission surface 42. A large number of prism rows are arranged in parallel on the light incident surface 41, and each prism row has two prisms: a first prism surface 44 located on the light source side and a second prism surface 45 located on the side far from the light source. It is composed of surfaces. 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, The inclination angle of these three planes increases as the plane is closer to the light exit surface 42. In the present invention, the angle of inclination of the surface of the prism array refers to the angle of inclination of each surface with respect to the prism array forming plane 43.

  The light deflection element 4 has a top distribution angle α of the first prism surface 44 of 2 to 25 degrees, a top distribution angle β of the second prism surface 45 of 33 to 40 degrees, and the absolute value of the difference between α and β (| By setting α-β |) to 8 to 38 degrees, a high light condensing effect can be exhibited, and high luminance as a light source device can be obtained. In the present invention, the apex distribution angles α and β are the left and right distribution angles with respect to the normal direction of the prism array forming plane 43 of the apex angle of the prism array, and the prism array formation at the top of the first prism surface 44 is performed. The angle formed with the normal direction of the plane 43 is α, and the angle formed with the normal direction of the prism array forming plane 43 at the top of the second prism surface 45 is β. Furthermore, 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 light emitted from the light exit surface 42 after being totally reflected by each surface is determined. Extremely high luminance can be obtained by matching all the surfaces. At this time, the difference in inclination angle between the surface closest to the light exit surface and the surface farthest from the light exit surface is in the range of 1 to 15 degrees, preferably in the range of 5 to 12 degrees, more preferably 7 to 10 degrees. It is a range of degrees. Further, by making 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 stabilize an optical deflecting element having a certain optical characteristic stably. It can also be manufactured.

  Next, the shape and function of the prism surface in the optical deflection element of the present invention will be described in more detail. 3 to 12 show that the two prism surfaces are both formed from a single plane and have angles α and β (corresponding to the top distribution angles α and β in the present invention), respectively, and the light exit surface normal. With respect to a conventional light deflection element that 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 light. Shows the distribution of the emitted light from the light deflecting element in a plane perpendicular to both the light incident surface and the light exit surface of the light guide, which is 20 degrees with respect to the exit surface. It is a thing. 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. The second prism surface is divided into 10 areas in the x direction. The distribution of light emitted from each area is shown by equally dividing. The ten areas were Part1, Part2,... Part10 in order from the side closest to the top of the prism. In the emission light distribution of the total light that is totally reflected and emitted by the second prism surface, as shown in FIG. 13, the peak light is emitted in the normal direction of the prism array forming plane, and the full width at half maximum of 22 degrees is obtained. Have.

  However, when these are seen in the emitted light distribution in each area of Part1 to Part10, the peak angle is about -9 degrees in Part1 and Part2 (the negative angle value is when the normal direction is 0 degrees and tilted toward the light source direction) In the case of Part 3 to Part 7, the peak light is sequentially shifted toward the 0 degree direction (the normal direction of the prism array forming plane), and in Part 8 to Part 10, the peak light is sequentially shifted in the positive angle direction. You can see that it is shifting. The peak angle of the outgoing light totally reflected in the area (Part 10) closest to the light outgoing surface 42 is 7 degrees. Between each area (Part1 to Part10) of the second prism surface, the peak angle has a spread of 16 degrees. Further, the intensity of the peak light from each area gradually decreases from Part 1 to Part 10.

  Thus, it can be seen that the light that is totally reflected and emitted by the prism surface composed of one plane is dispersed in a considerably wide range depending on the total reflection area of the prism surface. By adjusting the inclination angle of the surface of each area and emitting the peak light in the distribution of the emitted light from each area so that the peak angles are substantially in the same direction in all areas, most of the emitted light is 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 increased in the order from Part 1 to Part 10, that is, the inclination angle is increased toward the surface of the area closer to the light exit surface 42. In this way, by adjusting the inclination angle of the surface of each area, the emitted light totally reflected by the entire prism surface can be condensed in a certain direction as shown in FIG. High and high peak intensity light can be emitted. The present invention has been made based on such an idea.

  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 much, and there is a limit to the improvement of the peak intensity. Therefore, by setting α to 2 to 25 degrees, the amount of light hitting the second prism surface 45 can be increased, and as a result, the peak intensity is increased. Compared to FIG. 15, the effect of refraction at the first prism surface 44 is increased as shown in FIG. 16, and the cross section of the prism surface 45 is adjusted by adjusting the dimensions so that the prisms have the same pitch. This is because the length in the shape becomes long. For example, if α is 5 degrees and β is 38 degrees as shown in FIG. 16, the second light amount is about 1.29 times that in the case of α = β = 32.7 degrees as shown in FIG. It can be received by the prism surface 45. Thus, by reducing α, the amount of light hitting the prism surface 45 increases. However, if the second prism surface 45 is a single plane, the totally reflected light cannot be efficiently directed in the substantially normal direction. For this reason, the second prism surface 45 needs to be a non-planar surface such as a curved surface and / or a number of surfaces such as a flat surface.

  With regard to the number of areas of the second prism surface 45, if the number is increased, the peak angle can be finely adjusted over the entire prism surface, and the concentration of the emitted light as a whole can be increased. However, it is necessary to form fine planes with different inclination angles, which complicates the design and manufacture of a cutting tool for forming a prism surface of an optical deflection element, and provides optical deflection with certain optical characteristics. It becomes difficult to obtain the element stably. For this reason, it is preferable to make the number of areas formed in a prism surface into the range of 3-20, More preferably, it is the range of 4-15. Although it is preferable to divide the prism surface into areas equally, it is not always necessary to divide the prism surface equally, and the prism surface can be adjusted according to a desired distribution of emitted light on the entire prism surface.

  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 .5 to 39.5 degrees, more preferably 33.5 to 38 degrees, and most preferably 34 to 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 is, the larger the peak intensity is. However, when α = 0 °, it becomes difficult to direct the peak angle in a substantially normal direction. If α is made small, the prism apex angle (α + β) is also made small in order to make the peak angle substantially in the normal direction. In view of these, it is most preferable that α is 5 degrees or more and the cross-sectional shape is such that the peak angle of the outgoing light distribution for each surface is in a substantially normal direction.

  As a specific prism shape, when the coordinate of the apex of the prism is the origin and the length of the pitch P of the prism array is normalized to 1, the point 1 (−0.111,1) is displayed in the (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), cross-sectional shape connecting 16 points (0.889, 1.27) It includes 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 (0.531, 0.748), point 10 (0.584, 0.834), point 11 (0.637, 0.922), point 12 (0.716, 1.059) A shape composed of eleven planes having a cross-sectional shape is also preferable. Furthermore, 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), which is composed of 12 planes having a cross-sectional shape connecting 13 points.

  The 16 points, 12 points and 13 points of the cross-sectional shape do not need to pass through all of them. Some deviation from each point (that is, passing through a point in the vicinity of each point) does not significantly affect the peak intensity. However, when the length of the pitch P of the prism row is normalized to 1, at least 5 points out of 16 points, 12 points, or 13 points have a radius of 0 centered on those points. It is desirable to be within a circle of 0.021, preferably within a circle with a radius of 0.018, more preferably within a circle with a radius of 0.014. It is most desirable that the eight points are within a circle having a radius of 0.014.

  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, and all the surfaces may be convex curved surfaces. That is, the prism surface may be composed of one or more planes 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 is in the center (−6. 672, 5.537) forming a part of a circle with a radius R = 8.677. Thus, when the prism surface is composed of a plurality of convex curved surfaces having different inclination angles, the number of areas is reduced to 2 to 10, preferably 2 to 5, for example, compared to the case where the prism surface is constituted by planes having different inclination angles. can do. However, if the number of areas is too small, it is difficult to design each convex curved surface for adjusting the desired outgoing light distribution, so the number of areas is more preferably in the range of 3 to 4.

  Further, the shape of the convex curved surface can be not only circular but also non-circular in its XY cross-sectional shape. Further, when the prism surface is formed by a plurality of convex curved surfaces, the shape of each convex curved surface is preferably 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.

  In the present invention, the inclination angle in the case of a convex curved surface refers to the inclination angle with respect to the prism array forming plane 43 of the surface connecting the both ends of the convex curved surface (corresponding to the chord of the convex curved portion in the cross-sectional shape). When the convex curved surface constitutes the top, the top distribution angle is an angle formed with the normal direction of the prism row forming plane 43 that connects the both ends of the convex curved surface.

  Regarding the relationship between the pitch P of the prism array and the length L2 connecting the top of the prism array and the trough of the prism surface 45 of the prism array, the amount of light received by the prism surface 45 is increased, and the prism surfaces constituting the prism array In order to direct the peak angle of the emitted light distribution in each area in the normal direction and prevent the prism apex angle (α + β) from becoming too small, L2 / P = 1.1 to 1.7. preferable. More preferably, L2 / P = 1.16 to 1.6, and further preferably L2 / P = 1.27 to 1.56. Further, the relationship between the length L1 connecting the top of the prism row and the valley of the prism surface 44 and the length L2 connecting the top of the prism row 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 further preferably L2 / L1 = 1.16 to 1.22.

  In the present invention, the prism row has a smaller cutting angle at the prism valley. For this reason, burrs are likely to be generated in the prism valleys during manufacturing, and defects in which the prism valleys look like lines 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 drawing, the flat portion 59 is preferably provided at a position of 2 to 10 μm from the prism valley when the flat portion is not formed, more preferably 2.5 to 5 μm, More preferably, the position is 3 to 4 μm. This is because if the position is less than 2 μm, precise machining of the cutting tool for forming the pattern of the prism row in the mold tends to be difficult, and if it exceeds 10 μm, the brightness tends to decrease. The flat portion is formed at a position in the range of 0.035 to 0.18 in the height direction from the prism valley when the flat portion is not formed when the length of the pitch P of the prism row is normalized to 1. Alternatively, when the length L2 of the imaginary straight line connecting the prism apex and the prism valley in the cross-sectional shape of the prism surface with the apex distribution angle β is normalized to 1, the prism valley extends in the height direction of the prism row. It may be in the range of 0.022 to 0.16.

  When the length of the pitch P of the prism row is normalized to 1 with respect to the ridge line formed by the two prism surfaces constituting the prism row, the ridge line is 0 with respect to the reference line of the ridge line (a line located at the average height of the prism row). It can also be formed in a concavo-convex shape of .018 to 0.354. The degree of unevenness of the ridge line with respect to the reference line is preferably 0.018 to 0.177, more preferably 0.018 to 0.088, and more preferably 0.035 to 0.063. By making the ridge line uneven in the Z direction, glare is prevented, defects in the light guide plate and the light deflection element are made difficult to visually recognize, and it is useful for improving the quality such as reducing non-uniform luminance. On the other hand, when the ridge is uneven, a slight gap is generated between the light guide plate and the light deflection element. For this reason, the light emitted from the light guide plate hits the prism array on the side opposite to the light source from the prism array to be hit when there is no gap, and particularly the light emitted from the light guide closer to the normal line than the peak output light May not be able to hit the main reflecting surface (the prism surface far from the primary light source), and in that case, the overall luminance may be reduced accordingly. However, in the optical deflecting element of the present invention, the luminance can be significantly increased by compensating for the luminance reduction caused by the unevenness of the ridge line, and thus the overall luminance can be prevented from decreasing. 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 is within the above range. The method for forming the ridge line in an uneven shape is not particularly limited. For example, when forming a lens pattern by cutting using a lens mold that has been cut while applying specific vibration, or by grinding the ridge line part of the lens unit of a conventional lens sheet using fine sandpaper etc. It can be formed by a method or the like.

  When the two prism surfaces constituting the prism row are normalized with the length of the pitch P of the prism row as 1, the reference surface of the prism surface (the reference line of the ridge line and the base of the prism surface (side on the valley side) In the same manner as in the case where the ridgeline is made uneven, the quality can be improved. The degree of unevenness with respect to the prism reference surface is preferably 0.012 to 0.152, more preferably 0.012 to 0.076, and more preferably 0.022 to 0.046.

  As described above, the light deflection element 4 as described above is placed on the light emitting surface 33 of the light guide 3 so that the prism array forming surface is on the light incident surface side. The distribution of the outgoing light in the XZ plane of the directional outgoing light emitted from the light outgoing surface 33 can be made narrower, and the luminance 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 emitting surface 33 of the light guide 3, the main reflecting surface of the prism array (on the side far from the primary light source). The shape of the prism surface) is optimized and lengthened, and when the light emitted from the light guide 3 enters the prism row, the incident light is refracted away from the light output surface 42 of the light deflection element 4. By setting the inclination angle of the light incident surface (prism surface close to the primary light source) of the prism row so that the light can be used, the light usage efficiency can be reduced by suppressing the dispersion of light in unnecessary directions. Thus, light can be emitted in a concentrated manner in a desired direction, and the luminance as a light source device can be significantly improved.

  In the light deflection element 4 as described above, when the prism surface is composed of a plurality of flat surfaces or convex curved surfaces having different inclination angles, the top and bottom portions of the prism row are connected to ensure sufficient light condensing characteristics. The maximum distance (d) between the virtual plane and a plurality of planes or convex curved surfaces (actual prism surfaces) is preferably 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 exceeds 5%, the light condensing characteristic tends to be lowered, and sufficient luminance cannot be improved. It is in the range of 0.4 to 4.5%, more preferably in the range of 0.7 to 4.0%. Further, as the convex curved surface, the radius of curvature (r) is preferably in the range of 2 to 50 (r / P) with respect to the pitch (P) of the prism row, more preferably 5 to 30, and still more preferably. Is in the range of 6.5-12. If this r / P is less than 2 or exceeds 50, sufficient light condensing characteristics cannot be exhibited and the luminance tends to decrease.

  The full width at half maximum of the outgoing light distribution in the XZ plane of the outgoing light from such a light deflection element 4 is preferably 5 degrees or more and 25 degrees or less, more preferably in the range of 10 to 20 degrees, Preferably it is the range of 11-15 degree | times. This makes it possible to eliminate the difficulty of viewing images and the like due to an extremely narrow field of view by setting the full width at half maximum of this outgoing light distribution to 5 degrees or more, and to increase the brightness by setting it to 25 degrees or less. Because.

  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 can also 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 is not only installed on one side end surface of the light guide 3, but can be further installed on the other side end surface facing each other as necessary. .

  In the present invention, as shown in FIG. 1, when a linear light source is used as the primary light source 1, the prism row formed on the light deflection element 4 extends in a direction substantially parallel to the primary light source 1. Alternatively, it is formed so as to extend in a direction having an inclination of 20 ° or less with the primary light source 1, but the arrangement of the prism rows formed in the light deflection element 4 is the propagation of light propagating in the light guide 3 depending on the light source used. It can be changed depending on the 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 arranged at the corner of the light guide 3 or the like, the light incident on the light guide 3 is a light exit surface. In the same plane as 33, the light that propagates through the light guide 3 radially about the primary light source 1 and exits from the light exit surface 33 is also emitted radially about the primary light source 1. In order to efficiently deflect the emitted light emitted radially like this in a desired direction regardless of the emission direction, the prism array formed in 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. Thus, by arranging the prism rows in parallel in a substantially arc shape so as to surround the primary light source 1, most of the light emitted radially from the light emitting surface 33 is substantially perpendicular to the prism rows of the light deflection element 4. Therefore, the emitted light can be efficiently directed in a specific direction in the entire region of the light emitting surface 33 of the light guide 3, and the uniformity of luminance can be improved. The substantially arc-shaped prism row formed on the light deflecting element 4 is selected according to the distribution of the light propagating in the light guide 3, and most of the light emitted radially from the light emitting surface 33 is light. It is preferable that the light is incident substantially perpendicular to the prism row of the deflecting element 4. Specifically, those arranged in parallel so that the radius of the substantially arc is gradually increased in a substantially concentric manner with a point light source such as an LED as the center, the radius range of the prism row is, 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.

  The light source reflector 2 guides the light from the primary light source 1 to the light guide 3 with little loss. As a material, for example, a plastic film having a metal-deposited reflective layer on the surface can be used. As shown in the drawing, the light source reflector 2 is wound from the outer surface of the light reflecting element 5 to the light emitting surface edge of the light diffusing element 6 through the outer surface of the primary light source 1. 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 light reflecting element 5 to the edge of the light emitting surface of the light guide 3 through the outer surface of the primary light source 1. It can also be wound.

  A reflection 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 reflecting element 5, for example, a plastic sheet having a metal vapor deposition reflecting layer on the surface can be used. In the present invention, the light reflecting element 5 may be a light reflecting layer or the like formed on the back surface 34 of the light guide 3 by metal vapor deposition or the like instead of the reflecting sheet.

  The light guide 3 and the light deflection element 4 of the present invention can be made of a synthetic resin having a high light transmittance. Examples of such synthetic resins include methacrylic resins, acrylic resins, polycarbonate resins, polyester resins, and vinyl chloride resins. In particular, methacrylic resins are optimal because of their high light transmittance, heat resistance, mechanical properties, and molding processability. Such a methacrylic resin is a resin mainly composed of methyl methacrylate, and preferably has a methyl methacrylate content of 80% by weight or more. When forming the rough surface structure of the light guide 3 and the light deflection element 4 and the surface structure such as the prism array, the transparent synthetic resin plate is formed by hot pressing using a mold member having a desired surface structure. Alternatively, the shape may be imparted simultaneously with molding by screen printing, extrusion molding, injection molding, or the like. The structural surface can also be formed using heat or a photocurable resin. Furthermore, on a transparent substrate such as a polyester film, acrylic resin, polycarbonate resin, vinyl chloride resin, polymethacrylamide resin, or other transparent substrate or rough surface structure made of an active energy ray curable resin. Moreover, a lens array arrangement structure may be formed on the surface, or such a sheet may be bonded and integrated on a separate transparent base material by a method such as adhesion or fusion. As the active energy ray-curable resin, polyfunctional (meth) acrylic compounds, vinyl compounds, (meth) acrylic acid esters, allyl compounds, (meth) acrylic acid metal salts, and the like can be used.

  The light emitting surface of the surface light source device comprising 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 (the light exiting surface 42 of the light deflecting element 4). Is arranged 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. Further, in the present invention, a sufficiently collimated narrow distribution of light can be incident on the liquid crystal display element from the surface light source device, so that there is no gradation inversion in the liquid crystal display element and the brightness and hue uniformity. Can be obtained, and light irradiation concentrated in a desired direction can be obtained, and the utilization efficiency of the light emission amount of the primary light source for the illumination in this direction can be enhanced.

  Furthermore, in the present invention, in the light source device having a narrow field of view and a high brightness as described above by the light deflecting element 4, in order to appropriately control the field of view according to the purpose without causing a decrease in brightness as much as possible. In addition, the light diffusing element 6 can be disposed adjacent to the light exit surface of the light deflecting element 4. Further, in the present invention, by disposing the light diffusing element 6 in this manner, it is possible to suppress glare, brightness spots and the like that cause deterioration in quality and to improve quality.

  The light diffusing element 6 may be integrated with the light deflecting element 4 on the light exit surface side of the light deflecting element 4, or the light diffusing element 6 may be individually placed on the light exit surface side of the light deflecting element 4. Although it is good, it is preferable to dispose the light diffusing elements 6 individually. When the light diffusing elements 6 are individually mounted, a concavo-convex 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 sticking between the light diffusing element 6 and the liquid crystal display element disposed thereon, and an uneven structure is also provided on the light diffusing element 6. Is preferred. In the case of providing this concavo-convex structure only for the purpose of preventing sticking, the concavo-convex structure is preferably a structure having an average inclination angle of 0.7 degrees or more, more preferably 1 degree or more, and more preferably 1 .5 degrees or more.

In the present invention, it is necessary to use a light diffusing element 6 having a light diffusing characteristic for appropriately diffusing light emitted from the light deflecting element 4 in consideration of a balance of luminance characteristics, visibility, quality, and the like. That is, when the light diffusibility of the light diffusing element 6 is low, it is difficult to sufficiently widen the viewing angle and the visibility is lowered, 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 is impaired, and the total light transmittance is also lowered and the luminance tends to be lowered. Therefore, in the light diffusing element 6 of the present invention, one having a full width at half maximum of the outgoing light distribution when parallel light is incident is in the range of 1 to 13 degrees. The full width at half maximum of the light diffusing element 6 is preferably in the range of 3 to 11 degrees, more preferably in the range of 4 to 8.5 degrees. In the present invention, the full width at half maximum of the emitted light distribution of the light diffusing element 6 indicates how much the parallel rays incident on the light diffusing element 6 are diffused and spread when emitted, as shown in FIG. The full width angle (Δθ _H ) of the divergence angle at a half value with respect to the peak value in the luminous intensity distribution of the outgoing light transmitted and diffused through the light diffusing element 6.

  Such light diffusion characteristics can be imparted by mixing a light diffusing agent in the light diffusing element 6 or imparting a concavo-convex structure to at least one surface of the light diffusing element 6. The degree of the concavo-convex structure formed on the surface differs depending on whether it is formed on one surface of the light diffusing element 6 or on both surfaces. In the case of forming a concavo-convex structure 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, and more Preferably it is 4 to 6.5 degrees. When the concavo-convex structure is formed on both surfaces of the light diffusing element 6, the average inclination angle of the concavo-convex structure formed on one surface is preferably in the range of 0.8 to 6 degrees, more preferably 2 to 2. It is 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 diffusing element 6, it is preferable to make the average inclination angle on the incident surface side of the light diffusing element 6 larger than the average inclination angle on the exit 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 luminance characteristics and improving visibility, more preferably in the range of 30 to 70%, more preferably 40. It is in the range of ~ 65%.

  The light source device of the present invention is also required to have uniform luminance in the display area when observed from the normal direction of the light emitting surface (the exit surface of the light diffusing element 6). This uniformity of brightness also depends on the size of the display area of the light source. For example, a large light source device with a large display area such as a notebook computer or a monitor may require a relatively wide viewing angle characteristic. It is required to make the distribution of outgoing light emitted from the light emitting surface wider. On the other hand, in a small light source device with a small display area such as a mobile phone or a portable information terminal, priority may be given to high brightness and display quality improvement, and the distribution of emitted light emitted from the light emitting surface may be relatively narrow. . For this reason, it is preferable to use the light diffusing element 6 having an appropriate light diffusing characteristic according to the size of the display area of the light source device.

  In the present invention, the light deflecting element 4 is used to emit light emitted from the light guide 3 in a specific direction such as a normal direction, and the light emitted from the light deflecting element 6 is anisotropically diffused. The light can be emitted in a desired direction. In this case, the light diffusing element 6 can be provided with both functions of anisotropic diffusion and light deflection. For example, in the case where a lenticular lens array or a cylindrical lens shaped body is used as the concavo-convex structure, both functions of anisotropic diffusion and light deflection can be provided by making the cross-sectional shape asymmetric.

  In the present invention, the light deflection element 4 and the light diffusion 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 refractive index different from that of the material constituting the light deflecting element 4 or the light diffusing element 6 can be used, for example, silicon beads, polystyrene, polymethyl methacrylate, fluorinated A homopolymer such as methacrylate or a copolymer may be used. As the light diffusing material, it is necessary to appropriately select the content, the particle size, the refractive index and the like so as not to impair the narrow field effect by the light deflecting element 4 and the appropriate diffusing effect by the light diffusing element 6. For example, the refractive index of the light diffusing material is such that if the difference in refractive index from the material constituting the light deflecting element 4 or the light diffusing element 6 is too small, the diffusing effect is small. The rate difference is preferably in the range of 0.01 to 0.1, more preferably 0.03 to 0.08, and more preferably 0.03 to 0.05. Further, the particle size of the light diffusing material is such that if the particle size is too large, the scattering becomes strong, causing glare and a decrease in luminance, and if it is too small, coloring occurs, so the average particle size is in the range of 0.5 to 20 μm. Preferably, it is 2-15 micrometers, More preferably, it is the range of 2-10 micrometers.

  Note that the emitted light distribution of the light source device using the light deflection element as in the present invention is sharply reduced in luminance as the emitted light distribution on the primary light source side becomes farther away from the peak light at the peak position. The outgoing light distribution on the side far from the light source may show an asymmetric outgoing light distribution in which the luminance decreases relatively slowly. For example, when such a light source device having an emitted light distribution is used in a liquid crystal display device that requires a relatively wide viewing angle, such as a notebook computer of 10 inches or more, a light diffusing element having a relatively high light diffusibility is used as a light deflection device. It is arranged on the light exit surface of the element to widen the outgoing light distribution and widen the viewing angle. In the case of using a light diffusing element having a haze value of 50% or more and having a high light diffusibility, the peak angle of the emitted light distribution is deflected to the side far from the primary light source by about 1 to 3 degrees. For this reason, when the peak angle of the outgoing light distribution from the light deflection element is located in the normal direction of the light outgoing surface, the peak angle of the outgoing light distribution is about 1 to 3 degrees from the normal direction by the light diffusing element. The light is polarized to the far side, and as a result, the luminance when observed from the normal direction is extremely reduced. This is because the use of the light diffusing element slightly relaxes the asymmetry of the outgoing light distribution emitted from the light deflecting element, but the portion of the outgoing light distribution where the brightness decreases relatively rapidly is located in the normal direction position. It is to do. In order to avoid such an extreme decrease in luminance, it is preferable that the peak angle of the distribution of light emitted from the light deflection element is previously tilted by 1 to 3 degrees from the normal direction to the light source side.

  Hereinafter, the present invention will be described specifically by way of examples. In addition, the measurement of each physical property in the following examples was performed as follows.

A cold cathode tube was used as a measurement light source for normal luminance and full width at half maximum of luminous intensity of the surface light source device, and DC12V was applied to the inverter (HIU-742A manufactured by Harrison Co., Ltd.) for high frequency lighting. The full width at half maximum of light intensity of the light guide is fixed with 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 distance was adjusted so that the gonio rotation axis was rotated about the pinhole in a direction perpendicular to and parallel to the longitudinal axis of the cold cathode tube. While rotating the rotation axis in each direction from + 80 ° to −80 ° at 1 ° intervals, the luminous intensity distribution of the emitted light is measured with a luminance meter, the peak angle, the full width at half maximum of the luminous intensity distribution (1/2 of the peak value) Distribution spread angle). 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 and positioned at the central surface portion of the surface light source device, 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 the peak angle were obtained. The peak angle was 0 ° in the normal direction with respect to the light source device, the primary light source side was negative, and the opposite side was positive.

Example 1
A light guide having one surface having a mat (average inclination angle of 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 surface side of the light guide, a prism row having a prism apex angle of 100 ° and a pitch of 50 μm is made of acrylic ultraviolet curable resin so as to be parallel to a side (short side) of 216 mm in length of the light guide. A prism layer arranged in parallel was formed. A cold-cathode tube along a side end surface (end surface on the thickness side of 2.0 mm) corresponding to the side (long side) of the light guide with a length of 290 mm is a light source reflector (silver reflection film manufactured by Reiko Co., Ltd.). Covered. Furthermore, a light diffusion reflection film (E60 manufactured by Toray Industries, Inc.) was attached to the other side end face, and a reflection sheet was placed on the prism array arrangement face (back face). The above configuration was incorporated into the 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.

  On the other hand, using an acrylic ultraviolet curable resin having a refractive index of 1.5064, the cross sections are point 1 (−16.0031, 59.828), point 2 (0.000, 0.000), point 3 (12.12). 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) (coordinate values are in μm units: the same applies to the following embodiments), a prism having a pitch of 56.5 μm composed of 11 planes. The prism row forming surface where the rows are arranged in parallel A prism sheet formed on one surface of a 188 μm polyester film was prepared.

  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 the 10 planes corresponding to points 2 to 12 are 52.6, 53.5, 54.3, 55.5, 56.3, 57.1, 57, respectively. .9 degrees, 58.4 degrees, 58.9 degrees, and 60.0 degrees.

  The lengths L1 and L2 of the surfaces constituting the prism row 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 unevenness of the prism ridge line with respect to the reference line was 0.053, and the degree of unevenness of the prism surface with respect to the reference surface was 0.036.

  In the obtained prism sheet, the prism array forming surface faces the light exit surface side of the light guide, the prism ridge line is parallel to the light incident surface of the light guide, and the first prism surface (point 1 and point 2 The surface light source device was obtained by placing the light source on the light source side. An outgoing light luminance distribution in a plane perpendicular to both the light incident surface and the light outgoing surface of the surface light source device is obtained, and a peak luminance ratio, a peak angle, and a peak luminance of 1 when a comparative example 1 described later is used as a reference. An angle having a luminance of / 2 (full width at half maximum) was measured, and the results are shown in Table 1.

Example 2
The prism array has cross sections of point 1 (-11.638, 66.002), point 2 (0.000, 0.000), point 3 (9.0000, 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.). 018), point 9 (27.000, 36.483), point 10 (30.000, 41.067), point 11 (33.000, 45.776), point 12 (36.000, 50.653) A prism sheet was manufactured in the same manner as in Example 1 except that the configuration was made up of 12 planes having a shape connecting 13 points (44.862, 66.002).

  In this prism sheet, the top sorting angle α was 10 degrees, and the top sorting angle β was 38 degrees. The inclination angles of the 11 planes corresponding to the points 2 to 13 are 52.0 degrees, 52.6 degrees, 52.8 degrees, 53.7 degrees, 54.5 degrees, 55.3 degrees, 56 sequentially. .1 degrees, 56.8 degrees, 57.5 degrees, 58.4 degrees, and 60.0 degrees.

  The lengths L1 and L2 of the surfaces constituting the prism row with respect to the prism row pitch P of the prism sheet were L2 / P = 1.414 and L2 / L1 = 1.192. The ratio d / P of the maximum distance d between the virtual plane connecting the top and bottom of the prism row and the actual prism surface corresponding to points 2 to 13 to the prism row pitch P was 3.3%. The degree of unevenness of the prism ridge line with respect to the reference line was 0.053, and the degree of unevenness of the prism surface with respect to the reference surface was 0.036.

  In the obtained prism sheet, the prism array forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incident surface of the light guide, and the first prism surface is the light source side. The 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

Example 3
The prism array has cross sections of point 1 (-11.605, 65.814), point 2 (0.000, 0.000), point 3 (9.00, 11.519), point 4 (15,000, 19.3), three planes connecting the four points, and a radius 410. from point 4 to point 5 (36.000, 50.653) centered on point A (-314.871, 263.703). 489 circles, two convex curved surfaces connecting points 5 to 6 (44.895, 65.814) with a circle of radius 629.574 centered on point B (-502.516, 376.787) A prism sheet was manufactured in the same manner as in Example 2 except that

  In this prism sheet, the top sorting angle α was 10 degrees, and the top sorting angle β was 38 degrees. The inclination angles of the two planes corresponding to point 2 to point 4 and the two convex curved surfaces corresponding to point 4 to point 6 are 52.0 degrees, 52.7 degrees, 56.1 degrees, 59. It was 6 degrees.

  The lengths L1 and L2 of the surfaces constituting the prism row with respect to the prism row pitch P of the prism sheet were L2 / P = 1.212 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 row and the actual prism surface corresponding to points 2 to 6 to the prism row pitch P was 3.1%. The degree of unevenness of the prism ridge line with respect to the reference line was 0.053, and the degree of unevenness of the prism surface with respect to the reference surface was 0.036.

  In the obtained prism sheet, the prism array forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incident surface of the light guide, and the first prism surface is the light source side. The 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

Example 4
The prism array has cross sections of point 1 (−6.292, 71.920), point 2 (0.000, 0.000), point 3 (9.00, 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), point 16 (50.208, 71.920) Example 1 except that it is composed of 15 planes composed of dots connected to each other. To prepare a prism sheet in the same manner.

  In this prism sheet, the top sorting angle α was 5 degrees, and the top sorting 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, respectively. It was .2 degrees, 56.0 degrees, 56.5 degrees, 57.0 degrees, 57.5 degrees, 58.0 degrees, 58.7 degrees and 59.4 degrees.

  The lengths L1 and L2 of the surfaces constituting the prism row 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 points 2 to 16 to the prism array pitch P was 3.7%. The degree of unevenness of the prism ridge line with respect to the reference line was 0.053, and the degree of unevenness of the prism surface with respect to the reference surface was 0.036.

  In the obtained prism sheet, the prism array forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incident surface of the light guide, and the first prism surface is the light source side. The 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

Example 5
The prism array has cross sections of point 1 (−6.322, 72.265), point 2 (0.000, 0.000), point 3 (12.000, 14.687), point 4 (15,000, 18.527) three planes connecting four points, and a radius from point 4 to point 5 (30.000, 39.517) centered on point A (-283.909, 247.987) 376. 827 circles, two convex curved surfaces connecting points 5 to 6 (50.178, 72.265) with a circle of radius 490.235 centered on point B (-376.959, 312.857) A prism sheet was prepared in the same manner as in Example 4 except that

  In this prism sheet, the top sorting angle α was 5 degrees, and the top sorting angle β was 39.3 degrees. The inclination angles of the two planes corresponding to points 2 to 4 and the two convex curved surfaces corresponding to points 4 to 6 are 50.7 degrees, 52.0 degrees, 54.4 degrees, 58. It was 4 degrees.

  The lengths L1 and L2 of the surfaces constituting the prism row with respect to the prism row pitch P of the prism sheet 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 row and the actual prism surface corresponding to points 2 to 6 to the prism row pitch P was 3.9%. The degree of unevenness of the prism ridge line with respect to the reference line was 0.053, and the degree of unevenness of the prism surface with respect to the reference surface was 0.036.

  In the obtained prism sheet, the prism array forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incident surface of the light guide, and the first prism surface is the light source side. The 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

Example 6
The prism array has a cross-section of a single plane connecting two points, point 1 (-11.596, 65.767) and point 2 (0.000, 0.000), and point 2 to point 3 (44.904). , 65.767) in the same manner as in Example 1 except that the first curved surface is connected by a circle having a radius of 466.137 with the point A (-361.105, 294.766) as the center. A prism sheet was prepared.

  In this prism sheet, the top sorting angle α was 10 degrees, and the top sorting angle β was 34.3 degrees. The inclination angle of one convex curved surface corresponding to points 2 to 3 was 55.7 degrees.

  The lengths L1 and L2 of the surfaces constituting the prism row with respect to the prism row pitch P of the prism sheet were L2 / P = 1.409 and L2 / L1 = 1.192. The ratio d / P of the maximum distance d between the virtual plane connecting the top and bottom of the prism row and the actual prism surface corresponding to points 2 to 3 to the prism row pitch P was 3.0%. The degree of unevenness of the prism ridge line with respect to the reference line was 0.053, and the degree of unevenness of the prism surface with respect to the reference surface was 0.036.

  In the obtained prism sheet, the prism array forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incident surface of the light guide, and the first prism surface is the light source side. The 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

Example 7
The prism array is composed of one plane connecting the two points of the point 1 (−16.005, 59.730) and the point 2 (0.000, 0.000), and the point 2 to the point 3 (30.000). , 42.238) to a circle with a radius of 456.044 centered on point A (-356.204, 284.772), and from point 3 to point 4 (40.495, 59.730) to point B (- A prism sheet was produced in the same manner as in Example 1 except that the sheet was constituted by two convex curved surfaces connected by a circle having 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.

  The lengths L1 and L2 of the surfaces constituting the prism row with respect to the prism row pitch P of the prism sheet 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 row and the actual prism surface corresponding to points 2 to 4 to the prism row pitch P was 2.5%. The degree of unevenness of the prism ridge line with respect to the reference line was 0.053, and the degree of unevenness of the prism surface with respect to the reference surface was 0.036.

  In the obtained prism sheet, the prism array forming surface faces the light exit surface side of the light guide of Example 1, the prism ridge line is parallel to the light incident surface of the light guide, and the first prism surface is the light source side. The 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

Example 8
The prism array has a cross section of a plane connecting point 2 (−14.1776, 61.4101) and point 2 (0.000, 0.000), and point 2 to point 3 (42.3224). 61.4101), a prism sheet was fabricated in the same manner as in Example 1, except that the circle was formed with a circle having a radius of 504.3237 centered on the point A (−392.9609, 316.1078). The lengths L1 and L2 of the surfaces constituting the prism row with respect to the prism row pitch P of the prism sheet were L2 / P = 1.320 and L2 / L1 = 1.183.

Example 9
A prism sheet was produced in the same manner as in Example 8 except that the prism row was provided with a flat portion at a position 3 μm in the height direction of the prism from the prism valley.

Example 10
A prism sheet was produced in the same manner as in Example 8 except that the prism row was provided with a flat portion at a position of 5 μ in the prism height direction from the prism valley.

Example 11
A prism sheet was produced in the same manner as in Example 8 except that the prism row was provided with a flat portion at a position of 7 μ in the height direction of the prism from the valley portion of the prism.

Example 12
A prism sheet was produced in the same manner as in Example 8 except that the prism row was provided with a flat portion at a position of 10 μm in the height direction of the prism from the prism valley.

Example 13
The prism array has a cross-section of one plane connecting point 2 (−19.7523, 54.2691) and point 2 (0.000, 0.000), and point 2 to point 3 (36.74747). , 54.2691) was made in the same manner as in Example 1 except that it was composed of a circle with a radius of 468.9151 centered on the point A (−3688.9514, 2899.466). The lengths L1 and L2 of the surfaces constituting the prism row with respect to the prism row pitch P of the prism sheet were L2 / P = 1.160 and L2 / L1 = 1.135.

Comparative Example 1
The prism row of the prism sheet is the same as in Example 1 except that the two prism surfaces are both flat and the isosceles triangle section (α = β = 32.7 degrees) having a prism apex angle of 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 outgoing surface of the surface light source device is obtained, the peak luminance is set to 1.00, the peak angle, and the angle having a luminance half of the peak luminance. (Full width at half maximum) was measured, and the results are shown in Table 1.

Comparative Example 2
The prism row of the prism sheet is the same as in Example 1 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

Comparative Example 3
The prism row of the prism sheet is the same as in Example 1 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 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 the surface light source device is obtained, and the peak luminance ratio, peak angle, and ½ of the peak luminance when Comparative Example 1 is used as a reference. The angle having the brightness of (full width at half maximum) was measured, and the results are shown in Table 1.

It is a typical perspective view which shows the light source device by this invention. It is explanatory drawing of the shape of the prism row | line | column of the light-incidence surface of the optical deflection | deviation element of this invention. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the various emitted light distribution from an optical deflection | deviation element. It is explanatory drawing which shows the difference in the refraction of light by the difference in the inclination angle of a prism surface, and the length of a prism cross section. It is explanatory drawing which shows the difference in the refraction of light by the difference in the inclination angle of a prism surface, and the length of a prism cross section. It is explanatory drawing of the shape of the prism row | line | column of the light-incidence surface of the optical deflection | deviation element of this invention. It is the perspective view which has arrange | positioned the substantially point light source adjacent to the corner part of a light guide. It is explanatory drawing of the full width at half maximum of emitted light distribution. It is explanatory drawing of the shape of the prism row | line | column of the light-incidence surface of the optical deflection | deviation element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Primary light source 2 Light source reflector 3 Light guide 4 Light deflecting element 5 Light reflecting element 6 Light diffusing element 31 Light incident end surface 32 End surface 33 Light emitting surface 34 Back surface 41 Light incident surface 42 Light emitting surface 43 Prism array forming plane 44 First Prism surface 45 Second prism surfaces 46 to 50 Planar surfaces 51 and 52 Convex surface 59 Flat portion

Claims (6)

A primary light source, a light guide having a light incident surface on which light emitted from the primary light source is incident, and having a light emitting surface that guides the incident light and emits the guided light; and A light source device comprising: a light incident surface on which light emitted from the light emitting surface of a light body is incident; and a light deflecting element located on the opposite side and having a light emitting surface that emits incident light.
The distribution of the emitted light from the light emitting surface of the light guide in a plane orthogonal to both the light incident surface and the light emitting surface is such that the angle between the peak direction and the light emitting surface is 10 to 40 degrees. The full width at half maximum is 10 to 40 degrees,
A plurality of prism rows composed of two prism surfaces are arranged in parallel with each other on the light incident surface of the light deflection element ,
The top portion distribution angle α of one prism surface constituting the prism row is 2 to 25 degrees, and the top portion distribution angle β of the other prism surface is 33 to 40 degrees,
The difference | α−β | between the top distribution angle α and the top distribution angle β is 8 to 35 degrees,
The prism surface of the prism array at the top distribution angle α is disposed on the side closer to the primary light source, and the prism surface of the prism array at the top distribution angle β is disposed on the side far from the primary light source;
The prism surface of the top distribution angle β is a non-single plane;
The pitch P of the prism row and the length L2 of the imaginary straight line connecting the prism top and the trough in the cross-sectional shape of the prism surface with the apex distribution angle β constituting the prism row are L2 / P = 1. A light source device satisfying a relationship of 16 to 1.6. The ratio d / P of the maximum distance d between the non-single plane connecting the top and bottom of the prism row and the virtual plane connecting the top and bottom to the pitch P of the prism row is 0.7 to 5%. The light source device according to claim 1, wherein the light source device is provided . The said non-single plane consists of a several plane and / or convex curved surface, and the inclination angle is large as the plane or convex curved surface located in the side near the said light emission surface is characterized by the above-mentioned. Light source device . The non-single plane is composed of at least one plane at a portion close to the top of the prism row, and is formed of at least one convex curved surface at a side near the valley portion of the prism row, the plane and the convex curved surface. 4. The light source device according to claim 3 , wherein the boundary is positioned at 30% or less of the height of the prism row from the top. 5. In the cross section of the prism row, when the coordinates of the vertex are the origin, point 1 (-11.605, 65.814), point 2 (0.000, 0.000), point 3 (9.0,000, 11.519), point 4 (15.000, 19.396), or a plurality of planes connecting the neighboring points, and point 4 and point 5 (36.000, 50.653) or two points thereof It has a shape connecting a circular arc with a radius of 410.489 connecting neighboring points and a circular arc with a radius of 629.574 connecting the two points of the points 5 and 6 (44.895, 65.814) or its neighboring points. The light source device according to claim 1, wherein: In the cross section of the prism row, when the coordinates of the vertex are the origin, point 1 (−6.322, 72.265), point 2 (0.000, 0.000), point 3 (12.000, 14.687), four planes of point 4 (15.000, 18.527) or their neighboring points, and two points of point 4 and point 5 (30.000, 39.517) or It consists of a circular arc with a radius of 376.827 that connects neighboring points, and a circular arc with a radius of 490.235 that connects the two points of the points 5 and 6 (50.178, 72.265) or its neighboring points. The light source device according to claim 1, wherein:

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