JP2018063919A - Surface light source device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light source device which can perform light distribution control in a longitudinal direction of a light distribution control element as well and has tolerance for thermal expansion or thermal contraction.SOLUTION: A surface light source device comprises: a substrate including a principal surface; a plurality of light sources disposed so as to be arrayed on the principal surface of the substrate; and a light distribution control element being disposed on the principal surface of the substrate so as to cover the plurality of light sources, and changing a light distribution of light emitted from the light sources. The light distribution control element includes: a first lens having a longitudinal part in an arrangement direction of the light sources; and a second lens being disposed at one end or both ends in a longitudinal direction of the first lens and having a fixed position where being disposed. Further, the first lens is held by the second lens, and the second lens has light distribution characteristics different from those of the first lens.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a surface light source device and a display device, and in particular, a surface light source device that emits planar light using a plurality of light sources, and a display panel that is illuminated from the back surface by the surface light source device to display an image on the display panel. The present invention relates to a display device for displaying.

  In recent years, an LED element is mainly used as a light source in a surface light source device of a liquid crystal display device. A direct type surface light source device in which a plurality of LED elements are arranged on the back surface of a product, that is, the bottom surface of a housing, includes a light distribution control element on the LED elements. The light emitted from the LED element is refracted by the light distribution control element and the light distribution is controlled, and then irradiates the liquid crystal panel.

  The light distribution control elements are roughly classified into a light distribution control element of a round lens and a light distribution control element of a long lens. A surface light source device including a light distribution control element of a round lens includes one light distribution control element for each LED element. FIG. 1 is a perspective view of a substrate 92 on which a light distribution control element 91 of a round lens is mounted. Each LED element 93 is disposed immediately below each light distribution control element 91. That is, the light emission center of the LED element 93 is disposed on an extension of the central axis of the light distribution control element 91. The light emitted from each LED element 93 is refracted by each light distribution control element 91, and the light distribution is changed.

  The light distribution control element of the long lens has a length in the one-dimensional direction. A surface light source device including a long lens light distribution control element collectively covers a plurality of LED elements arranged in a one-dimensional direction. FIG. 2 is a perspective view of a substrate 92 on which a long lens light distribution control element 94 is mounted. Each LED element 93 is located directly below the light distribution control element 94. The light distribution control element 94 refracts the light emitted from the plurality of LED elements 93 and changes the light distribution.

  As a method for increasing the brightness of the surface light source device, there is a method for increasing the number of LED elements 93 installed without changing the overall length and the outer shape of the substrate 92. FIG. 3 is a perspective view of the substrate 92 and the light distribution control element 91 in which the number of installed LED elements 93 is increased in a one-dimensional direction without changing the overall length and outer shape of the substrate 92 shown in FIG. As the number of installed LED elements 93 arranged on the substrate 92 increases, the number of installed light distribution control elements 91 also increases.

  On the other hand, the light distribution control element 94 of the long lens does not need to increase the number of installed light distribution control elements 94 even if the number of installed LED elements 93 arranged in the one-dimensional direction increases. 4 is a perspective view of the substrate 92 and the light distribution control element 94 in which the number of installed LED elements 93 is increased in a one-dimensional direction without changing the overall length and the outer shape of the substrate 92 shown in FIG. Despite the increase in the number of installed LED elements 93 arranged on the substrate 92, the number of installed long lens light distribution control elements 94 does not change, and the arrangement thereof does not change. That is, the configuration of the long lens light distribution control element 94 is not affected by the number of LED elements 93 installed. This is because a light distribution control element 94 having a length capable of covering a plurality of LED elements 93 may be installed, which is an advantage of the long lens light distribution control element 94.

Japanese Patent No. 5081988 JP 2009-192915 A JP 2006-286608 A JP 2007-048883 A Japanese Utility Model Publication No. 6-38267

  When the light distribution control element of the long lens is a part manufactured by injection molding, the total length is determined by the mold. Therefore, when mounting a light distribution control element produced by injection molding on a surface light source device of various sizes, from a surface light source device for a large display device to a surface light source device for a small display device, depending on the screen size. Therefore, it is necessary to prepare a mold for the light distribution control element having a certain length. Patent Document 1 discloses an illumination lens that is elongated by arranging a plurality of lenses of the same size adjacent to each other in one direction. The illumination lenses described in Patent Document 1 can be mounted on a plurality of display devices having different screen sizes by connecting a plurality of them even if they are parts manufactured by injection molding. is there. However, the length of the illumination lens described in Patent Document 1 can be adjusted only by an integral multiple of the minimum length of the lens. If the lens length of the minimum unit constituting the illumination lens is reduced, it can be mounted on more models having different screen sizes. However, as the lens length is reduced, one surface light source device can be installed. The number of necessary parts increases. Therefore, in the manufacturing process of a large display device having such an illumination lens, there is a concern that the number of work man-hours will increase significantly. Furthermore, there is a difference between the light distribution of the light emitted from the LED elements arranged immediately below the joints of the adjacent lenses and the light distribution of the light emitted from the LED elements arranged directly below the lenses, resulting in uneven brightness. Occur. In order to reduce such luminance unevenness, there are restrictions on the arrangement of the LED elements.

  When the light distribution control element of the long lens is a part produced by extrusion molding, the light distribution control element of various lengths can be adjusted by adjusting the cutting position in the extrusion process while using the same mold. Manufacturing is possible. That is, according to the method of manufacturing the light distribution control element by extrusion molding, a light distribution control element having a length suitable for each model having a different screen size can be manufactured using the same mold. This is also a cost advantage. From such a viewpoint, the surface light source device preferably includes a long lens formed by extrusion rather than injection molding.

  The light distribution control element of the round lens has an advantage that the light emitted from the LED element can be three-dimensionally controlled by appropriately designing the shape of the lens. The light distribution control element of the long lens can control light distribution in two directions within the plane by adjusting the lens shape of the cross section orthogonal to the longitudinal direction. However, light distribution control in a one-dimensional direction parallel to the longitudinal direction of the light distribution control element is difficult, and the light distribution is determined by the optical characteristics of the LED elements. As described above, the light distribution control element of the long lens is mainly two-dimensional light distribution control. In particular, when the light distribution control element is manufactured by extrusion molding, a desired light distribution cannot be obtained with respect to light emitted in the longitudinal direction from both ends of the light distribution control element. This is because both ends of the light distribution control element are cut surfaces formed by the cutting process. Even if these cut surfaces are subjected to additional processing and a lens shape is provided, deterioration of the optical performance due to the cut surface is unavoidable, and cost increase due to the additional processing is unavoidable.

  Patent Documents 2 and 3 disclose a lens elongated in a one-dimensional direction and its optical characteristics. In each of the lenses described in Patent Document 2 and Patent Document 3, the light distribution in the in-plane direction is controlled by adjusting the shape of the cross section orthogonal to the longitudinal direction. However, these lenses cannot perform light distribution control in a direction parallel to the longitudinal direction.

  Also, when the positional relationship between the light source such as the LED element and the light output part of the light distribution control element is shifted in any of the light distribution control elements of the round lens and the long lens, that is, when the optical axis is shifted. Deterioration of brightness or color unevenness occurs. Therefore, it is important for the surface light source device to have a holding structure in which the positional relationship between the two does not collapse.

  The light distribution control element is mounted on the substrate using a dedicated jig in order to place the light distribution control element at an accurate position with respect to the LED element and to obtain a reliable bonding strength to the housing. A method of bonding is common. As shown in FIG. 1, the light distribution control element 91 of a round lens is provided with a plurality of bonding portions 91 a for bonding to a substrate 92. Even if the light distribution control element thermally expands or contracts, the distance between the bonding portions 91a is so narrow that changes in the distance do not affect the mounting. That is, the stress acting on the bonding portion 91a due to the difference between the linear expansion coefficient of the substrate and the linear expansion coefficient of the light distribution control element is small enough not to affect the mounting. Therefore, the light distribution control element 91 of the round lens can be bonded and fixed to the substrate 92. On the other hand, the longer the light distribution control element 94 of the long lens, the larger the volume becomes. Therefore, the adhesive portion is caused by the difference between the linear expansion coefficient of the substrate 92 and the linear expansion coefficient of the light distribution control element 94. The shearing force acting on is also increased. Therefore, it is not desirable to bond and fix the light distribution control element 94 of the long lens to the substrate 92 because it causes peeling of the bonded portion or dropping of the light distribution control element 94.

  In addition, when the light distribution control element of the long lens is a part manufactured by an extrusion molding method, providing the light distribution control element with a shape for fixing by screws or snap fitting requires additional processing. This is necessary and increases costs. Therefore, they are preferably provided with another fixing means.

  Patent Document 2 and Patent Document 3 do not disclose a structure for holding a lens on a substrate on which LED elements are arranged. Patent Document 4 discloses an optical element for changing light direction in which a holding shape for fixing an optical element to a substrate is provided on the optical element itself. However, when the optical element for changing the light direction described in Patent Document 4 is an optical element formed by extrusion molding, it is necessary to provide a holding shape such as a screw hole or a snap fit by secondary processing. This is undesirable because the manufacturing cost of the surface light source device increases. In addition, the above-mentioned concerns and problems regarding adhesion occur in the same manner.

  Patent Document 5 discloses an LED array light source mounting structure in which both are fixed by inserting a substrate on which LED elements are mounted into a molded lens frame formed by extrusion molding. With this structure, it is possible to fix the molded lens frame and the mounting substrate without using screws or adhesives. However, in this LED array light source mounting structure, when the substrate is inserted into the molded lens frame, the substrate scrapes the inside of the molded lens frame. The shavings remain as a foreign object between the LED element and the molded lens frame. Moreover, it is necessary to insert a thin substrate or a long substrate according to the specifications of the display device or the surface light source device, which causes a problem in automation of the manufacturing process.

  The present invention has been made to solve the above problems, and is a surface light source capable of controlling light distribution in the longitudinal direction of the light distribution control element and capable of fixing the position of the light distribution control element. The purpose is to provide a device.

  A surface light source device according to the present invention includes a substrate including a main surface, a plurality of light sources arranged in a row on the main surface of the substrate, and is disposed on the main surface of the substrate so as to cover the light source, and is emitted from the light source. A light distribution control element that changes the light distribution of the light to be transmitted. The light distribution control element includes a first lens having a longitudinal direction in the arrangement direction of the light sources, a second lens that is disposed at one or both ends in the longitudinal direction of the first lens, and the disposed position is fixed. including. The first lens is held by the second lens, and the second lens has a light distribution characteristic different from that of the first lens.

  According to the present invention, it is possible to provide a surface light source device that can perform light distribution control in the longitudinal direction of the light distribution control element and can fix the position of the light distribution control element. Further, the surface light source device according to the present invention can be reduced in cost.

It is a perspective view of the light distribution control element of a round lens. It is a perspective view of the light distribution control element of a long lens. It is a perspective view of the light distribution control element of a round lens. It is a perspective view of the light distribution control element of a long lens. 1 is a diagram illustrating a configuration of a direct type surface light source device according to Embodiment 1. FIG. 3 is a perspective view showing a configuration of a light distribution control element in Embodiment 1. FIG. 3 is a perspective view showing a configuration of a light distribution control element in Embodiment 1. FIG. 6 is a cross-sectional view of a first lens included in the light distribution control element in Embodiment 1. FIG. 6 is a cross-sectional view of a first lens included in the light distribution control element in Embodiment 1. FIG. FIG. 6 is a perspective view of a second lens included in the light distribution control element in the first embodiment. FIG. 6 is a cross-sectional view of a second lens included in the light distribution control element in the first embodiment. FIG. 6 is a cross-sectional view of a second lens included in the light distribution control element in the first embodiment. 4 is a perspective view of a light distribution control element in Embodiment 1. FIG. 4 is a cross-sectional view of a light distribution control element in Embodiment 1. FIG. 4 is a cross-sectional view of a light distribution control element in Embodiment 1. FIG. 6 is a perspective view showing a configuration of a light distribution control element in Embodiment 2. FIG. 6 is a perspective view showing a configuration of a light distribution control element in Embodiment 2. FIG. 6 is a perspective view of a second lens included in the light distribution control element in Embodiment 2. FIG. 6 is a cross-sectional view of a light distribution control element in Embodiment 2. FIG. 6 is a cross-sectional view of a light distribution control element in Embodiment 2. FIG. 6 is a cross-sectional view of a light distribution control element in Embodiment 2. FIG. FIG. 10 is a perspective view illustrating a light distribution control element fixing unit according to Embodiment 3. FIG. 10 is a perspective view illustrating a light distribution control element fixing unit according to Embodiment 3. FIG. 10 is a perspective view illustrating a light distribution control element fixing unit according to Embodiment 3.

  Embodiments of a surface light source device and a display device according to the present invention will be described. The display device in each embodiment described below will be described by taking a liquid crystal display device as an example.

<Embodiment 1>
(Surface light source device)
FIG. 5A and FIG. 5B are diagrams showing a configuration of a direct-type surface light source device 100 including the light distribution control element 1, and FIG. 5B is a plan view of the surface light source device 100. . FIG. 5A shows a cross section taken along line A1-A1 ′ of FIG. As shown in FIG. 5B, the surface light source device 100 has a rectangular shape in plan view. The surface light source device 100 includes a light distribution control element 1 and a reflection sheet 6. The reflection sheet 6 includes a rectangular bottom surface 6b and four slopes 6a in contact with each side of the bottom surface 6b. Each inclined surface 6a has a gradient from the bottom surface 6b to the outside. The substrate 2 is disposed on the bottom surface 6 b, and the light distribution control element 1 is disposed on the substrate 2. The substrate 2 is a mounting substrate, for example. The light distribution control element 1 includes a first lens 4 having a longitudinal direction, and second lenses 5 disposed at both ends of the first lens 4. In this specification, the direction in which the first lens 4 has the longitudinal direction is the X direction, the direction perpendicular to the substrate 2 on which the first lens 4 is mounted is the Z direction, and the direction perpendicular to the X direction and the Z direction is the direction. The Y direction is assumed. Further, the surface light source device 100 includes an opening that faces the bottom surface 6b and is surrounded by the outer side of the slope 6a. Although not shown, the liquid crystal display device further includes a surface light source device 100 and a diffusion plate, an optical element, a display panel, and the like on the opening side. In the first embodiment, the display panel is a liquid crystal panel. The effective screen size of the liquid crystal panel is a rectangular area having a length E1 in the X direction and a length E2 in the Y direction shown in FIGS. 5 (a) and 5 (b). The area of the bottom surface 6b of the reflection sheet 6 is smaller than the effective screen size of the liquid crystal panel.

  FIG. 6 is a perspective view of the first lens 4, the second lens 5, and the substrate 2. FIG. 7 is a perspective view showing a state in which the first lens 4 and the second lens 5 are mounted on the main surface 2 a of the substrate 2. A plurality of light sources are arranged in a row on the main surface 2 a of the substrate 2. In the first embodiment, these light sources are LED elements 3. The first lens 4 is a long lens having a length in the arrangement direction of the LED elements 3. In the first embodiment, the surface light source device 100 includes two second lenses 5, and each second lens 5 is disposed so as to cover the surface 4 a at each end of the first lens 4. As will be described in detail later, the first lens 4 is thereby held between the second lens 5 and the substrate 2. Further, the LED element 3 is disposed immediately below the first lens 4 and the second lens 5. That is, the light distribution control element 1 is arranged on the main surface 2a of the substrate 2 so as to cover the LED elements 3 arranged in alignment. The light distribution control element 1 has a function of changing the light distribution by refracting the light emitted from the LED elements 3.

(First lens)
FIG. 8 is a cross-sectional view of the first lens 4, and the cross section is a surface perpendicular to the longitudinal direction. That is, FIG. 8 is a diagram showing a YZ section of the first lens 4. FIG. 8 shows a state where the first lens 4 is mounted on the main surface 2 a of the substrate 2.

  The first lens 4 has a light emitting surface 4b in which a shape having a convex curvature on a surface orthogonal to the longitudinal direction is formed continuously in the longitudinal direction. That is, the light emitting surface 4b is a surface in which a shape having a convex curvature in the YZ section is continuous in the X direction. The first lens 4 has a light incident surface 4c in which a concave shape covering the LED element 3 in the YZ section is formed continuously in the X direction. Further, a space is provided between the light incident surface 4 c and the LED element 3.

  FIG. 9 is a view showing a cross section in a direction parallel to the longitudinal direction of the first lens 4, that is, a ZX cross section. The cross section passes through the center of the first lens 4. The shapes of the light emitting surface 4b and the light incident surface 4c are constant in the X direction. Therefore, the surface 4a located at one end of the first lens 4 shown in FIG. 7 has the same shape as the light emitting surface 4b.

  The first lens 4 spreads the light emitted from the LED element 3 in a direction orthogonal to the longitudinal direction. That is, the first lens 4 controls light distribution in the YZ plane. The light distribution can be controlled by appropriately designing the shape of the light incident surface 4c or the shape of the light exit surface 4b in the YZ plane. That is, the light distribution of the light emitted from the LED element 3 is changed in the YZ plane depending on the cross-sectional shape of the first lens 4. On the other hand, the shapes of the light emitting surface 4b and the light incident surface 4c are constant in the X direction. In particular, when the first lens 4 which is a long lens is manufactured by extrusion molding, the shapes of the light incident surface 4c and the light emitting surface 4b in the X direction are constant and cannot be appropriately changed. Therefore, the light distribution in the ZX plane is determined by the optical characteristics of the LED elements 3, that is, the light distribution characteristics. Note that the first lens 4 in the first embodiment is manufactured by extrusion molding.

(Second lens)
FIG. 10 is a perspective view of the second lens 5, which is observed from the back side of the second lens 5, that is, the direction in which the second lens 5 is mounted on the substrate 2. The second lens 5 includes an adhesive portion 5 a on the back surface for bonding and fixing to the main surface 2 a of the substrate 2. The adhesive portion 5a is disposed at an arbitrary position on the back surface. FIG. 10 shows the second lens 5 provided with the adhesive portions 5a at three locations on the back surface as an example. Although the space | interval of each adhesion part 5a can also change when the board | substrate 2 or the 2nd lens 5 thermally expands or shrinks, each adhesion part 5a is arrange | positioned by the space | interval of the extent that the change does not affect both adhesion | attachment. That is, since the influence due to the difference in linear expansion coefficient between the substrate 2 and the second lens 5 is small, the second lens can be bonded and fixed to the main surface 2 a of the substrate 2.

  FIG. 11 is a ZX cross-sectional view of the second lens 5 and shows a cross section taken along line A2-A2 'shown in FIG. FIG. 12 is a YZ cross-sectional view of the second lens 5 and shows a cross section taken along line A3-A3 'shown in FIG. The cross section passes through the center of the LED element 3 arranged on the main surface 2 a of the substrate 2. 11 and 12 show a state where the second lens 5 is mounted on the main surface 2a of the substrate 2. FIG. The bonding portion 5a is bonded to the main surface 2a, and the position of the second lens 5 is fixed. The illustration of the first lens 4 is omitted.

  The second lens 5 includes a holding portion 5d that contacts the surface 4a (see FIG. 6) of the first lens 4. The holding portion 5d includes a first holding surface 5e parallel to an upper surface 4d (shown in FIG. 14 described later) included in the surface 4a of the first lens 4. The holding portion 5d of the second lens 5 includes a second holding surface 5f parallel to a side surface 4e (shown in FIG. 15 described later) included in the surface 4a of the first lens 4.

  In the first embodiment, the second lens 5 includes a long lens portion 5c having a function similar to that of the first lens 4 that is a long lens, and a longitudinal direction of the first lens 4, that is, an arrangement in the X direction. And a round lens portion 5b having the same function as the round lens for controlling light. As shown in FIGS. 6 and 11, the round lens portion 5b has a convex light emitting surface 5g formed of a three-dimensional curved surface. A three-dimensional curved surface refers to a surface having a curve in either the XZ section or the YZ section. Further, the long lens portion 5c is disposed between the holding portion 5d and the round lens portion 5b. Further, the round lens portion 5b, the long lens portion 5c, and the holding portion 5d are sequentially arranged in the X direction, and they are integrated.

  Similarly to the first lens 4, the long lens portion 5 c of the second lens 5 can control light distribution in the YZ direction by adjusting the cross-sectional shape in the YZ plane. The second lens 5 performs three-dimensional light distribution control by the light exit surface 5g of the round lens portion 5b. That is, the second lens 5 distributes the light emitted from the LED element 3 radially. More specifically, in the arrangement shown in FIG. 11, the round lens unit 5b performs light distribution control in the −X direction, the ± Y direction, and the + Z direction. Thus, the second lens 5 has a light distribution characteristic different from that of the first lens 4.

(Light distribution control element)
FIG. 13 is a perspective view showing the light distribution control element 1 in which the first lens 4 is held by the second lens 5, and is a view observed from the back side of the light distribution control element 1, that is, from the direction of mounting on the substrate 2. is there. FIG. 14 is a ZX cross-sectional view of the light distribution control element 1, showing a cross section taken along line A4-A4 ′ shown in FIG. 15 is a YZ cross-sectional view of the light distribution control element 1, and shows a cross section taken along line A5-A5 ′ shown in FIG.

  The second lens 5 is fixed by bonding the bonding portion 5 a to the main surface 2 a of the substrate 2. At this time, the position of the second lens 5 is determined by engaging the substrate 2 with a pin, for example. Alternatively, the second lens is fixed by bonding after being positioned by a jig at the time of bonding. As a result, the position of the second lens on the substrate 2 is fixed.

  As shown in FIGS. 14 and 15, the surface 4a located at one end of the first lens 4 includes an upper surface 4d and a side surface 4e. The inclination of the surface 4a changes gently from the upper surface 4d to the side surface 4e. In the first embodiment, the upper surface 4d is a surface whose normal vector mainly has a Z direction component, and the side surface 4e is a surface whose normal vector mainly has a Y direction component. Part of the first holding surface 5e included in the holding portion 5d of the second lens 5 is in surface contact with the upper surface 4d included in the surface 4a of the first lens 4. Thereby, the first lens 4 is held between the main surface 2 a of the substrate 2 and the second lens 5. Further, the position of the first lens 4 in the direction perpendicular to the main surface 2 a of the substrate 2, that is, the Z direction is fixed.

  Further, as shown in FIG. 15, a part of the second holding surface 5 f of the second lens 5 is in contact with the side surface 4 e included in the surface 4 a of the first lens 4. As a result, the position of the first lens 4 in a direction perpendicular to the longitudinal direction of the first lens 4 and parallel to the main surface 2a of the substrate 2 is fixed. That is, the position of the first lens 4 in the direction parallel to the Y axis is fixed.

  As shown in FIG. 14, the light distribution control element 1 includes a gap 5 h between the first lens 4 and the second lens 5 in the longitudinal direction, that is, the direction parallel to the X axis. That is, the first end face is provided so that the first end face 4g provided at one end of the first lens 4 and facing the second lens 5 does not contact the second end face 5i of the second lens 5 facing the first end face 4g. A space is provided between 4g and the second end face 5i. With such a configuration, the first lens 4 is not completely fixed in the X direction, and only its position is restricted. The gap 5h functions as a buffer space when the first lens 4, the second lens 5, or the substrate 2 is thermally expanded or contracted. For example, when the first lens or the substrate 2 is thermally expanded or contracted, the position of the first lens 4 is fixed by the first holding surface 5e and the second holding surface 5f in the YZ direction, and in the YZ direction. There is no freedom. However, the first lens 4 can be slightly slid by applying a stress larger than the frictional force between the first holding surface 5e and the upper surface 4d in the X direction. Even if the first lens 4 slightly moves in the X direction due to thermal expansion or contraction, the first lens 4 and the second lens 5 do not come into contact with each other because the gap 5h is provided. Further, the excessive stress that releases the adhesion is not applied to the adhesion portion 5a of the second lens 5 as well. The gap 5 h prevents the first lens 4 and the second lens 5 from falling off or separating from the main surface 2 a of the substrate 2. For example, when the light distribution control element 1 does not include the gap 5h, the first end surface 4g of the first lens 4 and the second end surface 5i of the second lens 5 may collide, and both may be damaged or dropped off. is there. In the first embodiment, the material of the first lens 4 and the material of the second lens 5 are the same. With such a configuration, the light distribution control element 1 can reduce the influence of the above-described thermal expansion or contraction, so that the gap 5h can be narrowed.

  Further, the holding portion 5d or the gap 5h of the second lens 5 is preferably disposed between the adjacent LED elements 3 in a plan view, that is, in the XY plane. With such a configuration, it is possible to reduce the holding portion 5d or the gap 5h from hindering the light distribution of the light emitted from the LED element 3.

(effect)
In summary, the surface light source device 100 according to the first embodiment covers the substrate 2 including the main surface 2a, the plurality of light sources arranged in a row on the main surface 2a of the substrate 2, and the light source. The light distribution control element 1 is disposed on the main surface 2a of the substrate 2 and changes the light distribution of the light emitted from the light source. In the first embodiment, the light source is the LED element 3. The light distribution control element 1 includes a first lens 4 that is long in the arrangement direction of the light sources, and a second lens that is arranged at one or both ends in the longitudinal direction of the first lens 4 and whose arrangement position is fixed. 5 and the like. The first lens 4 is held by the second lens 5, and the second lens 5 has a light distribution characteristic different from that of the first lens 4.

  With the above configuration, the surface light source device 100 can perform light distribution control in the longitudinal direction or in other directions even if an extruded molded part is used for the first lens 4 that is a long lens. In addition, for example, in the extrusion molding process, only the entire length of the first lens 4 is adjusted according to the model of the surface light source device, and the second lens is attached to both ends thereof, so that the light distribution control varies in various lengths. It is possible to prepare the element 1. That is, the light distribution control element 1 included in the surface light source device 100 has a tolerance to develop into models of different sizes. Therefore, the surface light source device 100 shown in the first embodiment can be applied to display devices of various models having different screen sizes, and cost reduction is realized. Further, the surface light source device 100 does not need to directly fix the first lens, which is a long lens, to the substrate 2 on which the LED element 3 is mounted and the temperature may rise with an adhesive means or a screw. Furthermore, the surface light source device 100 fixes the arrangement positions of the first lens 4 in directions other than the longitudinal direction by the second lenses 5 provided at both ends thereof, and regulates the longitudinal direction. Therefore, the surface light source device 100 is less susceptible to the thermal expansion or contraction of the substrate 2 or the light distribution control element 1 and has a wider tolerance for heat than before. In addition, the surface light source device 100 appropriately controls the shape of the round lens portion 5b of the second lens 5 provided at both ends of the light distribution control element 1, thereby enabling light distribution control similar to that of the round lens, that is, three-dimensional. Light distribution control is possible. As a result, the surface light source device 100 has improved brightness uniformity as compared with the prior art.

  In addition, the arrangement position of the second lens 5 included in the surface light source device 100 according to the first embodiment is fixed to the main surface 2 a of the substrate 2. With this configuration, the first lens 4 does not need to include a holding unit that is fixed with respect to the substrate 2. Therefore, the surface light source device 100 has a structure stronger than the conventional structure against thermal expansion or thermal contraction of the substrate 2 or the first lens 4. In addition, the surface light source device 100 is capable of three-dimensional light distribution control while including a long lens, that is, a first lens manufactured by extrusion molding.

  Further, the second lens 5 provided in the surface light source device 100 according to the first embodiment includes a holding portion 5 d that contacts the surface 4 a at one end or both ends of the first lens 4. The holding unit 5 d holds the first lens 4 between the main surface 2 a of the substrate 2. With this configuration, the position of the first lens 4 is fixed by the second lens 5. That is, it is not necessary for the first lens 4 to include a holding unit that fixes the position with respect to the substrate 2. Therefore, the surface light source device 100 has a tolerance for thermal expansion or thermal contraction of the substrate 2 or the first lens 4. In addition, the surface light source device 100 is capable of three-dimensional light distribution control while including a long lens, that is, a first lens manufactured by extrusion molding.

  In addition, the holding unit 5d of the second lens 5 provided in the surface light source device 100 according to the first embodiment includes a first holding surface 5e parallel to the upper surface 4d included in the surface 4a of the first lens 4. At least a part of the first holding surface 5 e of the second lens 5 is in surface contact with the upper surface 4 d of the first lens 4. With such a configuration, the surface light source device 100 can fix the position of the first lens 4 in the direction perpendicular to the main surface 2 a of the substrate 2.

  In addition, the second lens holding unit 5 d provided in the surface light source device 100 according to the first embodiment includes a second holding surface 5 f parallel to the side surface 4 e included in the surface 4 a of the first lens 4. At least a part of the second holding surface 5 f of the second lens 5 is in surface contact with the side surface 4 e of the first lens 4. With such a configuration, the surface light source device 100 can fix the position of the first lens 4 in a direction orthogonal to the longitudinal direction and parallel to the main surface 2 a of the substrate 2.

  In addition, the second lens holding unit 5d provided in the surface light source device 100 according to the first embodiment is arranged between adjacent light sources among a plurality of light sources arranged in a row in plan view. . With such a configuration, the second lens holding portion 5d is prevented from obstructing the light distribution of the light emitted from the light source.

  The first lens 4 provided in the surface light source device 100 according to the first embodiment further includes a first end surface 4 g provided at one end and facing the second lens 5. The second lens 5 further includes a second end surface 5i that faces the first end surface 4g. The surface light source device 100 further includes a gap 5h between the first end surface 4g and the second end surface 5i so that the first end surface 4g of the first lens 4 and the second end surface 5i of the second lens 5 do not contact each other. With such a configuration, even if the light distribution control element 1 or the substrate 2 is thermally expanded or contracted, the surface light source device 100 can be configured such that the first lens 4 or the second lens 5 is dropped or released from the substrate 2 To prevent slipping.

  In addition, the first lens 4 included in the surface light source device 100 according to the first embodiment has a shape in which a convex curvature is continuously formed in the longitudinal direction on a surface orthogonal to the longitudinal direction. It has an emission surface 4b (first light emission surface) and spreads light emitted from the light source in a direction orthogonal to the longitudinal direction. The second lens 5 has a convex light emitting surface 5g (second light emitting surface), and spreads the light emitted from the light source radially. With such a configuration, the surface light source device 100 can perform light distribution control also in the longitudinal direction of the light distribution control element 1. And the brightness | luminance uniformity of the illumination light radiate | emitted from the surface light source device 100 improves. In particular, the second lens 5 includes a round lens portion 5b having a light exit surface 5g having a three-dimensional curved surface. Therefore, the light distribution control element 1 can control light distribution three-dimensionally at both ends in the longitudinal direction. That is, the surface light source device 100 can control light distribution radially from the end of the light distribution control element 1. When the light distribution control element does not include the second lens, the light distribution direction is only a direction orthogonal to the longitudinal direction of the first lens. As a result, the intensity of light at both ends in the longitudinal direction of the surface light source device becomes dark, and there arises a problem that luminance unevenness occurs in the surface light emitted from the surface light source device. For such a problem, the surface light source device 100 described in the first embodiment is designed by appropriately designing the shape of the round lens portion 5b of the second lens 5 provided at both ends of the light distribution control element 1. The same light distribution control as that of the round lens, that is, the light distribution control in all the XYZ directions is possible. Even if the first lens 4 which is a long lens is a part manufactured by extrusion molding, the light distribution control element 1 according to the present embodiment does not need to additionally process the lens shape on the cut surfaces at both ends. . Therefore, the cost increase of the light distribution control element 1, that is, the surface light source device 100 can be suppressed. Moreover, the light distribution control element 1 can avoid the deterioration of the optical performance due to the additional processing.

  The liquid crystal display device according to the first embodiment further includes a surface light source device 100 and a liquid crystal display panel to which planar light emitted from the surface light source device 100 is irradiated. With such a configuration, the liquid crystal display device is irradiated with uniform illumination light from the surface light source device 100, so that the video quality is improved.

<Embodiment 2>
FIG. 16 is a perspective view of the first lens 4, the second lens 5, and the substrate 2 in the second embodiment. FIG. 17 is a perspective view showing a state in which the first lens 4 and the second lens 5 are mounted on the main surface 2 a of the substrate 2. 16 and 17 omit the illustration of the light incident surface of the first lens 4 and the LED element covered by the light distribution control element 1, they are the same as those in FIGS. FIG. 18 is a perspective view of the second lens 5 according to the second embodiment, and is a view observed from the back side of the second lens 5, that is, the direction in which the second lens 5 is mounted. FIG. 19 is a ZX cross-sectional view of the light distribution control element 1, and shows a cross section passing through the center of the light distribution control element 1 as in FIG. FIG. 20 is a YZ cross-sectional view of the light distribution control element 1, and shows a cross section including A6-A6 ′ shown in FIG.

  The first lens 4 has a concave shape on the surface 4a in a plane orthogonal to the longitudinal direction, that is, the YZ plane. And the 1st lens 4 contains the concave surface part 4h in which the concave shape is formed continuously in a longitudinal direction. The holding portion 5d of the second lens 5 includes a convex portion 5j that contacts the concave surface portion 4h of the first lens.

  The first lens 4 is held between the main surface 2 a of the substrate 2 and the second lens 5 by the convex portion 5 j of the second lens 5 contacting the concave surface portion 4 h of the first lens 4. Further, the position of the first lens 4 in the direction perpendicular to the main surface 2 a of the substrate 2, that is, the Z direction is fixed.

  As shown in FIG. 20, the concave surface portion 4h of the first lens 4 is engaged with the convex portion 5j of the second lens in the YZ plane, so that the degree of freedom in the Y direction is limited. That is, the position of the first lens 4 in a direction orthogonal to the longitudinal direction and parallel to the main surface 2a of the substrate 2 is fixed.

  On the other hand, in the second embodiment, the first lens 4 has a surface in which the shape of the concave surface portion 4h is continuous in a direction parallel to the longitudinal direction. Similarly to the first embodiment, the light distribution control element 1 includes a gap 5h between the first end face 4g and the second end face 5i. Therefore, the position of the first lens 4 in the X direction is not completely fixed and is only regulated. The gap 5h functions as a buffer space when the first lens 4, the second lens 5, or the substrate 2 is thermally expanded or contracted. Since these operations and effects are the same as those of the first embodiment, description thereof will be omitted.

  Moreover, it is preferable that the convex part 5j and the space | gap 5h of a 2nd lens are arrange | positioned in the position away from the LED element 3. FIG. That is, it is preferable that the holding part 5d and the gap 5h of the second lens 5 are disposed between the adjacent LED elements 3 in plan view. With such a configuration, the convex portion 5j and the gap 5h can be prevented from obstructing the light distribution of the light emitted from the LED element 3.

  Further, as shown in FIG. 21, the surface light source device of the second embodiment has a configuration in which the concavo-convex relationship formed by the concave surface portion 4h of the first lens and the convex portion 5j of the second lens is reversed. A control element 1 can be provided. The first lens 4 of the light distribution control element 1 shown in FIG. 21 has a convex shape on the surface 4a in a plane orthogonal to the longitudinal direction. And the 1st lens 4 contains the convex surface part 4i in which the convex shape is formed continuously in a longitudinal direction. The holding part 5 d (not shown in FIG. 21) of the second lens 5 includes a concave part 5 k that contacts the convex part 4 i of the first lens 4.

  The concave portion 5 k of the second lens 5 is in contact with the convex surface portion 4 i of the first lens 4. Thereby, the first lens 4 is held between the main surface 2 a of the substrate 2 and the second lens 5. The first lens 4 is fixed in the Z direction with respect to the main surface 2 a of the substrate 2. Further, the convex portion 4i of the first lens 4 is engaged with the concave portion 5k of the second lens in the YZ plane, so that the degree of freedom in the Y direction is limited. That is, the position of the first lens 4 in the direction parallel to the Y axis is fixed.

  On the other hand, the convex surface portion 4i of the first lens 4 has a surface that is continuous in the direction parallel to the longitudinal direction in the X direction. Moreover, although illustration is abbreviate | omitted, the light distribution control element 1 contains the space | gap 5h similar to the above. Therefore, the installation position of the first lens 4 in the X direction is not completely fixed and is only regulated. These operations and effects are the same as those in the first embodiment.

  In summary, the first lens 4 included in the surface light source device according to the second embodiment has a concave shape on the surface 4a on the surface orthogonal to the longitudinal direction, and the concave shape is in the longitudinal direction. It includes a concave surface portion 4h formed continuously. The holding portion 5 d of the second lens 5 includes a convex portion 5 j that contacts the concave surface portion 4 h of the first lens 4. With this configuration, the concave surface portion 4h of the first lens 4 and the convex portion 5j of the second lens 5 are perpendicular to the longitudinal direction and parallel to the main surface of the substrate. The position can be fixed. When it is difficult for the first holding surface 5e of the second lens 5 described in the first embodiment to come into surface contact with the upper surface 4d of the first lens 4 and hold the first lens 4, the second lens 5 according to the second embodiment. The above configuration is effective. For example, although not shown, the above configuration is effective when the concave and convex portion 4h is provided with a fine uneven shape or when it is a shape that must avoid contact with another component. Moreover, the shape of the concave surface part 4h and the shape of the convex part 5j shown in FIG. 19 and FIG. 20 are examples, and are not limited thereto. The shape and arrangement position of the concave surface portion 4h on the surface 4a and the convex portion 5j on the holding portion 5d may be any shape and position where the position of the first lens 4 in the Y direction with respect to the LED element 3 is determined.

  The first lens 4 included in the surface light source device according to the second embodiment has a convex shape on the surface 4a on a surface orthogonal to the longitudinal direction, and the convex shape is continuous in the longitudinal direction. The convex surface part 4i formed in this way is included. The holding portion 5 d of the second lens 5 includes a concave portion 5 k that contacts the convex surface portion 4 i of the first lens 4. With such a configuration, the convex surface portion 4i of the first lens 4 and the concave portion 5k of the second lens 5 are positioned in the direction orthogonal to the longitudinal direction and parallel to the main surface of the substrate. Can be fixed.

<Embodiment 3>
A surface light source device and a liquid crystal display device according to Embodiment 3 will be described. In the third embodiment, an example of position fixing means for the second lens 5 included in the light distribution control element 1 will be described. Note that the description of the same configuration and operation as those in Embodiment 1 or Embodiment 2 is omitted.

  First, an example in which the second lens 5 is fixed to the substrate 2 by the engagement structure is shown. FIG. 22 is a perspective view of the second lens 5 fixed by the engagement structure and the substrate 2 to which the second lens 5 is fixed. The second lens 5 includes an engagement structure 5m. The engagement structure 5m is, for example, a snap fit. The substrate 2 includes a notch 2b. The position of the second lens 5 is fixed by engaging the engaging structure 5 m with the notch 2 b of the substrate 2. Note that the shape of the engagement structure 5m shown in FIG. 22 is an example, and is not limited thereto. Similar to the first embodiment, the second lens 5 holds the first lens 4 between the main surface 2 a of the substrate 2. The configuration of the first holding surface 5e of the second lens 5 and the configuration of the upper surface 4d of the first lens 4 are the same as those in the first embodiment. After the engagement structure 5m is engaged with the notch 2b, the optical performance of the light distribution control element 1 is provided between the first holding surface 5e of the second lens 5 and the upper surface 4d of the first lens 4 shown in FIG. It has a shape that does not produce a gap that would hinder the operation.

  Next, an example in which the second lens 5 is fixed to the substrate 2 with screws will be described. FIG. 23 is a perspective view of the second lens 5 fixed by screws and the substrate 2 to which the second lens 5 is fixed. The second lens 5 includes a screwing portion 5n. The substrate 2 includes a screw hole 2c. The screw 7 is screwed into the screw hole 2c of the substrate 2 through the screwing portion 5n. Thereby, the position of the second lens 5 is fixed. The second lens 5 holds the first lens 4 between the main surface 2 a of the substrate 2. It should be noted that the screwing portion 5n interferes with the optical performance of the light distribution control element 1 between the first holding surface 5e of the second lens 5 and the upper surface 4d of the first lens 4 shown in FIG. It has a shape that does not produce a significant gap.

  Next, an example in which the second lens 5 is fixed to the housing will be described. FIG. 24 is a perspective view of the second lens 5 fixed to the housing 8 and the housing 8. The housing 8 has a screw hole 8a. The screw 7 is screwed into the screw hole 8a through the screwing portion 5n. Thereby, the position of the second lens 5 is fixed. The substrate 2 and the first lens 4 are fixed between the second lens and the housing 8. Although illustration is omitted, a through hole may be provided in the substrate 2, and the second lens 5, the substrate 2, and the housing 8 may be screwed together through the screw 7 through the through hole. The fixing of the second lens 5 to the housing 8 with the screw 7 is an example.

(effect)
In summary, the surface light source device according to the second embodiment further includes a housing 8 that holds the substrate 2, and the arrangement position of the second lens 5 is fixed to the housing 8. With such a configuration, the surface light source device can easily replace, for example, when a problem occurs in the substrate 2 or the light distribution control element 1. Further, the first lens 4 does not need to include a holding unit that is fixed in position with respect to the substrate 2 or the housing 8. The position of the first lens 4 with respect to the substrate 2 or the housing 8 is fixed via the second lens 5. That is, it is possible to fix the position of the first lens 4 that is a long lens without providing the first lens 4 itself or the substrate 2 with an adhesive portion or holding shape for fixing the position.

  Further, the second lens provided in the surface light source device according to the second embodiment is fixed to the substrate 2 by the engagement structure 5 m or the screw 7. With such a configuration, the surface light source device can easily replace, for example, when a problem occurs in the substrate 2 or the light distribution control element 1. At this time, the positional relationship between the second lens 5 and the substrate 2 is determined by a method such as engaging the substrate 2 with a positioning pin. This positioning method is a method generally used for positioning a light distribution control element of a round lens on a mounting board. Further, when the second lens 5 is fixed by the engagement structure 5m, the manufacturing process can be simplified. That is, in the manufacturing process of the surface light source device, a jig used for bonding and a drying process are not necessary.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted. Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 Light distribution control element, 2 board | substrate, 2a main surface, 2b notch part, 2c screw hole, 3 LED element, 4 1st lens, 4a surface, 4b light emission surface, 4c light incident surface, 4d upper surface, 4e side surface, 4g 1st end surface, 4h Concave surface part, 4i Convex surface part, 5 2nd lens, 5a Adhesion part, 5b Round lens part, 5c Long lens part, 5d Holding part, 5e 1st holding surface, 5f 2nd holding surface, 5g Light exit surface, 5h Air gap, 5i Second end surface, 5j Convex part, 5k Concave part, 5m Engagement structure, 5n Screw fixing part, 6 Reflective sheet, 6a Slope, 6b Bottom face, 7 Screw, 8 Housing, 8a Screw hole 91 light distribution control element, 91a adhesion part, 92 board | substrate, 93 LED element, 94 light distribution control element, 100 surface light source device.

Claims (13)

A substrate including a main surface;
A plurality of light sources arranged in a row on the main surface of the substrate;
A light distribution control element that is disposed on the main surface of the substrate so as to cover the light source and changes a light distribution of light emitted from the light source;
The light distribution control element includes a first lens having a length in the arrangement direction of the light sources, and a second lens disposed and fixed at one or both ends of the first lens in the length direction,
The first lens is held by the second lens;
The surface light source device, wherein the second lens has a light distribution characteristic different from that of the first lens.   The surface light source device according to claim 1, wherein the position of the second lens is fixed to the main surface of the substrate. A housing for holding the substrate;
The surface light source device according to claim 1, wherein the position of the second lens is fixed to the housing.   The surface light source device according to claim 2, wherein the second lens is fixed to the substrate by an engagement structure or a screw. The second lens includes a holding portion that contacts the surface of the one end or both ends of the first lens,
The surface light source device according to any one of claims 1 to 4, wherein the holding unit holds the first lens between the main surface of the substrate. The holding portion of the second lens includes a first holding surface parallel to an upper surface included in the surface of the first lens,
The surface light source device according to claim 5, wherein at least a part of the first holding surface of the second lens is in surface contact with the upper surface of the first lens. The holding portion of the second lens includes a second holding surface parallel to a side surface included in the surface of the first lens,
The surface light source device according to claim 5, wherein at least a part of the second holding surface of the second lens is in surface contact with the side surface of the first lens. The first lens includes a concave surface portion that has a concave shape on the surface in a plane orthogonal to the longitudinal direction, and the concave shape is formed continuously in the longitudinal direction;
The surface light source device according to claim 5, wherein the holding portion of the second lens includes a convex portion that contacts the concave surface portion of the first lens. The first lens includes a convex surface portion having a convex shape on the surface on a surface orthogonal to the longitudinal direction, and the convex shape is formed continuously in the longitudinal direction,
The surface light source device according to claim 5, wherein the holding portion of the second lens includes a concave portion that contacts the convex surface portion of the first lens.   The said holding | maintenance part of a said 2nd lens is a planar view, and arrange | positions between the said adjacent light sources among these several light sources arrange | positioned in a row | line | column. The surface light source device described in 1. The first lens further includes a first end surface provided at the one end and facing the second lens;
The second lens further includes a second end surface facing the first end surface,
The air gap is further provided between the first end surface and the second end surface so that the first end surface of the first lens and the second end surface of the second lens do not contact each other. The surface light source device as described in any one of Claims. The first lens has a first light exit surface formed by extending a shape having a convex curvature on a surface orthogonal to the longitudinal direction in the longitudinal direction, and extending in the longitudinal direction. A light incident surface including a concave curved surface or a plane covering the plurality of light sources, and spreading the light emitted from the light sources in a direction perpendicular to the longitudinal direction,
The surface light source device according to any one of claims 1 to 11, wherein the second lens has a convex second light emission surface, and spreads the light emitted from the light source radially. A surface light source device according to any one of claims 1 to 12,
And a display panel that is irradiated with planar light emitted from the surface light source device.

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