JP2019179711A - Surface light source device, laminate used for surface light source device, and display device - Google Patents

Abstract

To provide a surface light source device which has been made thin.SOLUTION: A surface light source device 20 includes: a light source 22; a diffusion plate 50 provided being separated from the light source; an adjustment plate 45 provided between the light source and the diffusion plate, and for adjusting in-plane distribution of the transmitted light amount; and an auxiliary diffusion part 55 provided at least on one side out of on the light source side of the diffusion plate and on the opposite side from the light source of the diffusion plate. At least one of the diffusion plate and the auxiliary diffusion part is arranged adjacent to the adjustment plate. The adjustment plate adjusts the in-plane distribution of the transmitted light amount.SELECTED DRAWING: Figure 6

Description

  The present disclosure relates to a surface light source device that emits light in a planar shape, a laminate used in the surface light source device, and a display device.

  2. Description of the Related Art Surface light source devices that emit light in a planar shape are widely used as backlights in various fields, for example, illumination devices and display devices. The surface light source device is roughly classified into an edge light type and a direct type. In an edge light type surface light source device, a plurality of light sources are arranged on the side of an optical member forming a light emitting surface. This edge light type surface light source device has an advantage of being thin. On the other hand, in the edge light type surface light source device, there is a problem of a local temperature rise due to the localized light source on the side of the optical member. For this reason, there are some usage environments where the edge light type surface light source device is not suitable. For example, when a surface light source device is used as a backlight of an in-vehicle display device, the liquid crystal display device may malfunction if the heat dissipation efficiency decreases due to a temperature rise in the vehicle interior. In addition, there is a drawback that a technique called local dimming that reduces power consumption by in-plane control of the light emitting area cannot be used.

  In a direct type surface light source device, a plurality of light sources are dispersedly arranged below an optical member forming a light emitting surface. The direct type surface light source device disclosed in Patent Document 1 includes, as an optical member, a diffusion plate, and a homogenization plate that is positioned between the diffusion plate and the light source and uniformizes the in-plane distribution of the transmitted light amount. Have. In order to make the brightness distribution on the light emitting surface uniform, the homogenizing plate needs to be separated from the light emitter to some extent, and the diffusion plate needs to be separated from the homogenizing plate to some extent. That is, it is difficult to reduce the thickness of the direct type surface light source device.

International Publication No. 2007/037035

  The present disclosure has been made in consideration of the above points, and provides a thinned surface light source device.

A surface light source device according to the present disclosure includes:
A light source;
A diffusion plate provided apart from the light source;
An adjusting plate that is provided between the light source and the diffusion plate and adjusts the in-plane distribution of the transmitted light amount;
An auxiliary diffusion part provided on at least one side of the diffusion plate on the light source side and the light source side of the diffusion plate,
At least one of the diffusion plate and the auxiliary diffusion part is disposed adjacent to the adjustment plate.

In the surface light source device according to the present disclosure,
The diffusivity of the auxiliary diffusion part is stronger than the diffusivity of the diffusion plate,
The auxiliary diffusion portion has a thickness smaller than that of the diffusion plate.

In the surface light source device according to the present disclosure,
The diffusivity of the auxiliary diffusion part is stronger than the diffusivity of the diffusion plate,
The auxiliary diffusion part may be located between the light source and the diffusion plate.

  In the surface light source device according to the present disclosure, the auxiliary diffusing unit may be located between the adjustment plate and the light source.

In the surface light source device according to the present disclosure,
The adjustment plate has a transmission hole for light transmission,
The auxiliary diffusion part may be located in the transmission hole of the adjustment plate.

  In the surface light source device according to the present disclosure, the auxiliary diffusion portion may be adjacent to the adjustment plate, and the diffusion plate may be adjacent to the adjustment plate.

  In the surface light source device according to the present disclosure, the auxiliary diffusion portion may be located between the adjustment plate and the diffusion plate.

  In the surface light source device according to the present disclosure, the auxiliary diffusion portion may be adjacent to the adjustment plate, and the diffusion plate may be adjacent to the auxiliary diffusion portion.

  In the surface light source device according to the present disclosure, the auxiliary diffusing portion may be located on the opposite side of the diffusing plate from the adjusting plate.

  In the surface light source device according to the present disclosure, the diffusion plate may be adjacent to the adjustment plate, and the auxiliary diffusion portion may be adjacent to the diffusion plate.

  In the surface light source device according to the present disclosure, the diffusion plate may have an uneven surface on the side opposite to the adjustment plate.

  The surface light source device according to the present disclosure may further include a spacer that supports the adjustment plate and the diffusion plate.

A surface light source device according to the present disclosure is provided.
A spacer for supporting the adjustment plate and the diffusion plate;
The spacer includes a first support surface that supports the diffusion plate, a second support surface that is positioned closer to the light source than the first support surface and supports the adjustment plate, the first support surface, and the first support surface. A step surface that extends between the two support surfaces and faces the adjustment plate from the side and restricts the movement of the adjustment plate to the side,
Fixing means for pressing the diffusion plate toward the first support surface of the spacer may be provided.

  In the surface light source device according to the present disclosure, the length of the step surface between the first support surface and the second indicating surface is greater than the sum of the thickness of the adjustment plate and the thickness of the auxiliary diffusion portion. It may be.

  In the surface light source device according to the present disclosure, a length of the step surface between the first support surface and the second indicating surface may be larger than a thickness of the adjustment plate.

The laminate according to the present disclosure is:
A laminate used in a surface light source device,
An adjustment plate for adjusting the in-plane distribution of the transmitted light amount;
A diffusing plate arranged offset from the adjusting plate;
An auxiliary diffusing portion provided on at least one side of the diffusion plate on the side opposite to the adjustment plate and the adjustment plate on the diffusion plate,
At least one of the diffusion plate and the auxiliary diffusion part is disposed adjacent to the adjustment plate.

A display device according to the present disclosure includes:
Any of the surface light source devices according to the present disclosure described above;
A display panel illuminated by the surface light source device.

  According to the present disclosure, the surface light source device can be thinned.

FIG. 1 is a perspective view showing a display device and a surface light source device for explaining an embodiment. FIG. 2 is a perspective view for explaining a stacked configuration of the surface light source device of FIG. 1. FIG. 3 is a plan view showing the surface light source device of FIG. 2 with some components omitted. FIG. 4 is a cross-sectional view taken along line IV-IV of the surface light source device shown in FIG. FIG. 5 is a plan view showing one partition region of an adjustment plate that can be applied to the surface light source device of FIG. 6 is a diagram for explaining an example of the surface light source device of FIG. 2 in a cross section corresponding to the line IV-IV of FIG. 7 is a diagram for explaining another example of the surface light source device of FIG. 2 in a cross section corresponding to the line IV-IV of FIG. FIG. 8 is a diagram for explaining still another example of the surface light source device of FIG. 2 in a cross section corresponding to the line IV-IV of FIG. FIG. 9 is a diagram for explaining still another example of the surface light source device of FIG. 2 in a cross section corresponding to the line IV-IV of FIG. 10 is a view for explaining still another example of the surface light source device of FIG. 2 in a cross section corresponding to the line IV-IV of FIG. 11 is a longitudinal sectional view showing an example of a spacer used in the surface light source device of FIG. 2 in a section corresponding to the line XI-XI of FIG. 12 is a longitudinal sectional view showing another example of the spacer used in the surface light source device of FIG. 2 in a section corresponding to the line XI-XI of FIG. FIG. 13 is a table showing simulation targets and simulation results. FIG. 14 is a partial plan view showing an adjustment plate as a simulation target in FIG. 13. FIG. 15 is a diagram illustrating an in-plane distribution of luminance obtained as a simulation result of the first embodiment. FIG. 16 is a diagram illustrating an in-plane distribution of luminance obtained as a simulation result of the second embodiment. FIG. 17 is a diagram illustrating an in-plane distribution of luminance obtained as a simulation result of Example 3. FIG. 18 is a diagram illustrating an in-plane distribution of luminance obtained as a simulation result of Reference Example 1. FIG. 19 is a diagram illustrating an in-plane distribution of luminance obtained as a simulation result of Reference Example 2. FIG. 20 is a longitudinal sectional view illustrating the surface light source device according to the first embodiment.

  Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  In this specification, the terms “plate”, “sheet”, and “film” are not distinguished from each other only based on the difference in designation. For example, the “plate” is a concept including members that can be called “sheets” and “films”, and cannot be distinguished only by the difference in names.

  In addition, “plate surface (sheet surface, film surface)” means a target plate-like member (sheet-like shape) when the target plate-like (sheet-like, film-like) member is viewed as a whole and globally. It refers to the surface that coincides with the plane direction of the member or film-like member. In the present specification, the normal direction of a plate-like (sheet-like, film-like) member is the normal direction to the plate surface of the target surface and plate-like (sheet-like, film-like) member. Refers to that.

  Furthermore, as used in this specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “parallel”, “orthogonal”, “identical”, length and angle values, etc. Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

  FIGS. 1-19 is a figure for demonstrating one Embodiment. 1 is a perspective view schematically showing a display device 10 as an application example of the surface light source device 20. The display device 10 is a device that displays on the display panel 15 a video composed of, for example, a moving image, a still image, character information, or a combination thereof. The display device 10 can be used as, for example, an in-vehicle liquid crystal display device. The display device 10 can also be used for various purposes such as advertisements, presentations, television images, and display of various types of information indoors or outdoors. The display device 10 shown in FIG. 1 includes a surface light source device 20 having a light emitting surface 20a and a display panel 15 disposed to face the light emitting surface 20a. In the illustrated example, the display panel 15 is configured as a liquid crystal display panel, and thus the display device 10 is configured as a liquid crystal display device.

FIG. 2 is a perspective view showing a stacked configuration of the surface light source device 20. 3 and 4 are plan views and longitudinal sectional views showing the surface light source device 20, respectively. However, in FIG.3 and FIG.4, some components of the optical laminated body 40 are deleted and shown. The surface light source device 20 includes, as main components, a light source 22 (see FIG. 4) and an optical laminate 40 that adjusts an optical path of light emitted from the light source 22. The surface light source device 20 is configured as a direct type. Therefore, the light source 22, along the thickness direction d ₃ of the surface light source device 20 is arranged to face the optical stack 40.

  In particular, the surface light source device 20 described in the present embodiment is devised to reduce the thickness of the surface light source device 20. Specifically, the optical laminated body 40 includes an adjustment plate 45, a diffusion plate 50, and an auxiliary diffusion portion 55 as will be described later, and further, the arrangement of the adjustment plate 45, the diffusion plate 50, and the auxiliary diffusion portion 55 is devised. Thus, the optical laminate 40 and the surface light source device 20 can be thinned. Hereinafter, the display device 10 and the surface light source device 20 according to the embodiment will be described with reference to the illustrated specific examples.

  First, the display panel 15 of the display device 10 will be described. In the illustrated example, the display panel 15 is arranged so that the display surface 15 a on which an image is displayed faces the opposite side to the surface light source device 20. Thereby, the display surface 15 a of the display panel 15 forms the display surface 10 a of the display device 10. The display panel 15 is formed in a rectangular shape when viewed from the normal direction of the display panel 15, that is, in a plan view from the front direction.

  The display panel 15 is configured as a transmissive liquid crystal display panel, for example, and transmits part of the light incident on the display panel 15 from the surface light source device 20 and displays an image on the display surface 15a. The display panel 15 includes a liquid crystal layer having a liquid crystal material, and the light transmittance of the display panel 15 changes according to the strength of the electric field applied to the liquid crystal layer.

  As an example of such a display panel 15, a liquid crystal display panel having a pair of polarizing plates and a liquid crystal cell (liquid crystal layer) disposed between the pair of polarizing plates can be used. In this liquid crystal display panel, the polarizing plate decomposes incident light into two orthogonal polarization components, transmits the polarization component in one direction, and absorbs the polarization component in the other direction orthogonal to one direction. A polarizer having The liquid crystal cell includes a pair of support plates and a liquid crystal disposed between the pair of support plates. In the liquid crystal cell, an electric field can be applied to each region where one pixel is formed, and the liquid crystal alignment of the liquid crystal cell to which the electric field is applied changes. As an example, a polarized light component emitted from the surface light source device 20 and transmitted through a polarizing plate disposed on the surface light source device 20 side of the liquid crystal cell is a liquid crystal cell to which no electric field is applied. The polarization direction is rotated by 90 ° when passing through the liquid crystal, and the polarization direction is maintained when passing through the liquid crystal cell to which an electric field is applied. As a result, depending on whether or not an electric field is applied to the liquid crystal cell, the polarization component in a specific direction transmitted through the polarizing plate disposed on the surface light source device 20 side of the liquid crystal cell is disposed on the side opposite to the surface light source device 20 of the liquid crystal cell. Further, it is possible to control whether the light passes through another polarizing plate or is absorbed and blocked by the other polarizing plate.

Next, the surface light source device 20 will be described. The surface light source device 20 has a light emitting surface 20a that emits planar light. Light source 22 to the light emitting surface 20a facing the region in the normal direction d ₃ of the light emitting surface 20a is provided, it is configured as a backlight of a so-called direct type. In the illustrated example, the normal direction of the display surface 10a, the normal direction of the display panel 15, the normal direction of the display surface 15a, the normal direction of the light emitting surface 20a, and each sheet shape included in the optical laminate 40 normal direction of the member are parallel to each other, in the following, also referred to as a thickness direction d ₃ in this direction. Thickness direction d ₃ is also called a front direction.

The illustrated surface light source device 20 includes a light source 22, a base laminate 30, a spacer 23, and an optical laminate 40. As shown in FIG. 4, the light source 22 is supported on the base laminate 30. The spacer 23 is provided on the base laminate 30. Optical stack 40, the spacer 23, is held at a position spaced from the base laminate 30 in the thickness direction d _3. The optical stack 40 is disposed in most display panel 15 side in the thickness direction d _3. The surface facing the display panel 15 of the optical laminate 40 forms a light emitting surface 20a.

  6 to 10, the optical laminated body 40 includes a first optical sheet 41, a second optical sheet 42, an adjustment plate 45, a diffusion plate 50, and an auxiliary diffusion unit. 55 is included. On the other hand, FIGS. 3 and 4 are a plan view and a longitudinal sectional view showing the surface light source device 20, but the components of the optical laminate 40 other than the adjustment plate 45 are omitted. 4 is a longitudinal sectional view of the surface light source device 20 taken along the line IV-IV in FIG. 3, and shows one section area Aa of the surface light source device 20 corresponding to one light source 22. FIG. 5 is a plan view showing the adjustment plate 45.

The light source 22 is composed of, for example, a light emitting diode (LED) or the like, and is disposed to face the optical laminate 40. As well shown in FIG. 3, the light sources 22 are arranged along a first direction d ₁ parallel to the plate surface of the surface light source device 20, parallel to the plate surface of the surface light source device 20 and first. Arranged along a second direction d ₂ intersecting the direction d ₁ . In particular, in the illustrated example, the first direction d ₁ and the second direction d ₂ form a right angle. That is, in the illustrated example, the plurality of light sources 22 are two-dimensionally arranged along the first direction d ₁ and the second direction d ₂ . The surface light source device 20 is not limited to this, and the surface light source device 20 may include a plurality of light sources 22 arranged in a line along the first direction d ₁ or the second direction d ₂ , or only one light source 22. You may have. In FIG. 3, single LEDs are two-dimensionally arranged. However, the present invention is not limited to this, and a plurality of LED sets may be secondarily arranged. In addition, it is preferable that the output of each light source 22, that is, the brightness when each light source 22 is turned on and off, and / or the brightness when each light source 22 is turned on, can be adjusted independently from the output of the other light sources 22.

The optical laminate 40 is disposed to face the light source 22 and adjusts the illuminance distribution and the luminance distribution of the light emitted from the light source 22. In the example shown in FIG. 3, the outline of the optical laminated body 40 has a rectangular shape in plan view. The first direction _{d 1} and the second direction _{d 2} can be arbitrarily defined. In the illustrated example, the first direction d ₁ is defined to be parallel to one side of the rectangular shape that forms the outline of the optical laminate 40. The second direction d ₂ is defined so as to form a parallel with other one side perpendicular to the one side. In particular, in the illustrated example, the first direction d ₁ is defined to be parallel to the long side of the rectangular shape that outlines the optical laminate 40, and the second direction d ₂ is parallel to the short side of the rectangular shape. It is defined to make. Details of the optical laminate 40 will be described later.

Next, the spacer 23 will be described. The spacer 23 is a member that supports the optical laminated body 40 and has a function of maintaining a predetermined distance between the base laminated body 30 and the optical laminated body 40. As shown in FIGS. 2 and 3, the spacer 23 divides the space between the base laminate 30 and the optical laminate 40 into small spaces for each light source 22, and makes the small spaces circumferential. It also functions as the surrounding wall portion 24. Wall 24 includes a partition wall portion 24a which partitions the two spaces adjacent, and an outer wall portion 24b forming a part of the peripheral wall portion located outermost in the first direction d ₁ and the second direction d _2, the Contains. Corresponding to each light source 22, an opening 25 surrounded by a wall portion 24 is formed. The spacer 23 is not limited to the mode shown in FIGS. 2 and 3 and may be a support structure such as a pin.

In the illustrated example, the spacer 23, in plan view, extends a plurality of wall portions, the first direction d ₁ are arranged in the second direction d ₂ extending in a second direction d ₂ is arranged in the first direction d ₁ The plurality of wall portions 24 are arranged so as to form a lattice. The openings 25 are provided corresponding to the arrangement pattern of the light sources 22. That is, the spacer 23 has a plurality of openings 25 arranged in the first direction d ₁ and arranged in the second direction d ₂ . In the present embodiment, each opening 25 is formed in a rectangular shape, particularly a square shape in a plan view, but is not limited thereto, and each opening 25 has another shape such as a triangle, a hexagon, or a circle shape in a plan view. You may have done.

  Such spacers 23 are, for example, polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), acrylonitrile-styrene-acrylate copolymer resin (ASA resin), acrylonitrile-butadiene-styrene copolymer resin (AES resin), Polymethyl methacrylate resin (PMMA resin), polyacetal resin, polyvinyl chloride resin, polyethylene resin, polypropylene resin, polyethylene terephthalate resin, or a mixture of two or more of these resins can be used. In particular, the spacer 23 is preferably made of a material having high reflectivity with respect to light in the visible light wavelength region. Thereby, the wall part 24 comes to have high reflectivity.

  Note that the adjustment plate 45 of the optical layered body 40 described in detail later includes a plurality of partitioned areas Aa that are partitioned corresponding to the small spaces partitioned by the spacers 23. In FIG. 3, the positions of the light source 22 and the opening 25 of the spacer 23 arranged on the back side of the adjustment plate 45 are indicated by broken lines. From the viewpoint of suppressing the power consumption of the surface light source device, it is preferable to arrange a single light source 22 at the center of each partition region Aa as shown in FIG. The adjustment plate 45 has a base material 46 on which a plurality of transmission parts for transmitting light emitted from the light source 22 are formed. In FIG. 3, the illustration of the transmission part is omitted. The base 46 of the adjustment plate 45 has one or more partitioned areas Aa corresponding to the light sources 22.

The illustrated substrate 46 has a plurality of partitioned areas Aa, and one partitioned area Aa is provided for one light source 22. Therefore, the base material 46 has a plurality of partitioned areas Aa arranged along the first direction d ₁ and arranged along the second direction d ₂ . In FIG. 3, the area | region divided with the dashed-dotted line in the base material 46 has shown each division area Aa. In the illustrated example, each partition area Aa is formed in a rectangular shape in plan view, but the shape of the partition area Aa is not limited to this. Each divided area Aa is further divided into a plurality of regularly arranged element areas Ab, as will be described later. The illustrated element regions Ab have a common shape and a common size, but the specific shape and size of the element regions Ab are not limited, and for example, the shape may be different between the element regions Ab. The specific shape and arrangement pattern of the element region Ab will be described later.

In the example shown in FIG. 3, the partition line La that partitions adjacent partition regions Aa of the base material 46 is defined along the wall portion 24 of the spacer 23. In other words, the partition line La is defined so as to be located in a region facing the wall portion 24 of the spacer 23 along the normal direction of the adjustment plate 45. As a result, partition lines La, as a whole, a plurality of partition lines La extending in a second direction d ₂ is arranged in the first direction d _1, of the plurality extending in a first direction d ₁ are arranged in the second direction d ₂ The division lines La are defined so as to form a lattice. In the illustrated example, each partition area Aa has a width W ₁ along the first direction d ₁ and a width W ₂ along the second direction d ₂ . The width _{W 1} and the width _{W 2} may be, for example 5mm or 50mm or less.

  The base laminate 30 has a function of supporting the light source 22 and supplying power to the light source 22. In the example shown in FIG. 4, the base laminate 30 includes a base material 31, a bonding layer 32, a film substrate 33, a wiring layer 34, a resist layer 35, and a light reflection layer 36. As described above, in FIG. 4, the components of the optical laminate 40 other than the adjustment plate 45 are not shown.

  The base material 31 is a member that functions as a base material that holds the insulating substrate 33, the wiring layer 34, the resist layer 35, and the light reflection layer 36. The material of the base material 31 is not particularly limited as long as it can appropriately hold the insulating substrate 33, the wiring layer 34, the resist layer 35, and the light reflecting layer 36. For example, a metal, a resin, or the like is used. be able to. In particular, when the base material 31 formed of a metal material having good thermal conductivity such as aluminum is used, the heat generated by the light source 22 can be emitted toward the back side of the surface light source device 20 through the base material 31. Since it is possible, it is more preferable. The thickness of this base material 31 can be 0.5 mm or more and 10 mm or less, for example. The base material 31 may form part of the housing of the surface light source device 20.

  The insulating substrate 33 is a member that functions as a base material that holds the wiring layer 34, and forms a printed wiring board together with the wiring layer 34. The insulating substrate 33 may be flexible and form a flexible printed wiring board, or may not be sufficiently flexible and may form a rigid printed wiring board. The insulating substrate 33 shown in FIG. 4 is formed of a flexible resin film, whereby the insulating substrate 33 and the wiring layer 34 form a flexible printed wiring board. The thickness of the insulating substrate 33 can be, for example, 10 μm or more and 500 μm or less. By using a flexible substrate thinner than the conventional rigid substrate as the insulating substrate 33, it is preferable in that the surface light source device 20 can be thinned. The material of the film substrate 33 can be appropriately selected in consideration of insulation, heat resistance, durability, dimensional stability during heating, mechanical strength, and the like. For example, polyimide (PI), polyethylene naphthalate ( PEN) and polyethylene terephthalate (PET) can be used.

  The film substrate 33 is fixed to the base material 31 via the bonding layer 32. The bonding layer 32 is not particularly limited as long as it can appropriately fix the film substrate 33 to the base material 31. As an example, a double-sided tape can be used as the bonding layer 32. In addition, an appropriate adhesive or pressure-sensitive adhesive may be used as the bonding layer 32.

  The wiring layer 34 is provided on the film substrate 33 and has a function of supplying power to the light source 22. For this reason, the wiring layer 34 is preferably formed of a highly conductive metal material. As a metal material which forms the wiring layer 34, metal materials, such as copper, aluminum, gold | metal | money, silver, or these alloys, can be mentioned, for example. As an example, the wiring layer 34 can be formed using a subtractive method. That is, the wiring layer 34 having a desired pattern can be formed by patterning a metal layer such as a copper foil disposed on the film substrate 33 by etching using a photolithography technique. The wiring layer 34 may be formed using other methods such as an additive method and a semi-additive method. In the wiring layer 34, an electrode portion is provided at a connection portion between the light source 22 and another wiring or connector.

  A resist layer 35 is provided on the wiring layer 34 and the film substrate 33 exposed from the wiring layer 34. In particular, the resist layer 35 is provided so as to cover the wiring layer 34 and the film substrate 33 exposed from the wiring layer 34, except for a portion that becomes an electrode portion of the wiring layer 34. The resist layer 35 has a function of protecting the wiring layer 34 and preventing a short circuit between the wiring layer 34 and other members. As a material of the resist layer 35, for example, a resin material such as a polyester resin, an epoxy resin, an epoxy resin and a phenol resin, an epoxy acrylate resin, and a silicone resin can be used. As an example, the resist layer 35 is provided with a resin layer so as to cover the entire wiring layer 34 and the film substrate 33, and the electrode part is exposed at a position to be an electrode part of the wiring layer 34 by etching using a photolithography technique. It can be formed by providing an opening.

  The light reflection layer 36 is a layer provided to improve the utilization efficiency of light emitted from the light source 22, is emitted from the light source 22, is reflected by the optical laminate 40, and its optical path is directed toward the light reflection layer 36. The bent light is reflected again toward the optical laminate 40. Therefore, the light reflecting layer 36 is preferably a layer having high reflectivity with respect to light in the visible light wavelength region. The light reflecting layer 36 is disposed on the same side of the optical laminate 40 as the light source 22 and in parallel with the optical laminate 40. In the example shown in FIG. 4, the light reflecting layer 36 is laminated on the resist layer 35 except for the portion where the light source 22 is to be disposed. In the illustrated example, the light reflecting layer 36 is disposed so as to surround the light source 22 in a plan view. In the illustrated example, the light reflecting layer 36 is provided so as to expose the inner peripheral edge surrounding the light source 22 of the resist layer 35. However, the present invention is not limited to this, and in the light reflecting layer 36, for example, the inner peripheral edge of the resist layer 35 and the inner peripheral edge of the light reflecting layer 36 are aligned so that the inner peripheral edge surrounding the light source 22 of the resist layer 35 is not exposed. It may be provided in this way. Alternatively, the light reflecting layer 36 may be provided in contact with at least a part of the side surface of the light source 22. As the light reflecting layer 36, for example, a layer formed of a white resin material can be used.

  The light source 22 is connected to the electrode portion of the wiring layer 34 through the conductive connection layer 37. As the conductive connection layer 37, for example, a layer made of solder, a conductive adhesive, or the like can be used.

  Next, the optical laminate 40 will be described. The optical laminate 40 includes a first optical sheet 41, a second optical sheet 42, an adjustment plate 45, a diffusion plate 50 as a first diffusion member, and an auxiliary diffusion portion 55 as a second diffusion member. Of these, the adjustment plate 45 mainly has a function of adjusting the amount of transmitted light in each region within the surface. That is, the adjustment plate 45 has a function of adjusting the amount of light transmitted through the adjustment plate 45 in each region along the plate surface of the adjustment plate 45. In other words, the adjustment plate 45 mainly functions as an illuminance distribution adjustment plate that adjusts the in-plane distribution of illuminance on the light output side surface of the adjustment plate 45. In particular, in the surface light source device 20 applied to the display device 10, the adjustment plate 45 mainly functions as an illuminance distribution uniformizing plate that equalizes the in-plane distribution of illuminance. The adjustment plate 45 alleviates the in-plane variation of the transmitted light amount and makes the in-plane distribution of the transmitted light amount uniform.

On the other hand, the diffusion plate 50 and the auxiliary diffusion unit 55 mainly function as an optical path adjustment unit that adjusts the traveling direction of light. The diffusing plate 50 and the auxiliary diffusing unit 55 adjust the optical path to eliminate variations in the light traveling direction. Adjustment plate 45 in the thickness direction d _3, is positioned between the light source 22 and the diffusion plate 50. In the present embodiment, the adjustment plate 45, the diffusion plate 50, and the auxiliary diffusion unit 55 of the optical layered body 40 can extremely effectively uniformize the in-plane distribution of luminance when combined.

First optical sheet 41 and the second optical sheet 42 in the thickness direction d _3, located on the opposite side to the light source 22 of the diffusion plate 50. The first optical sheet 41 and the second optical sheet 42 are members that are arbitrarily installed for various purposes.

  For example, a light collecting sheet can be used as the first optical sheet 41. The first optical sheet 41 functioning as a condensing sheet changes the traveling direction of light incident from the light source 22 side and emits it from the display panel 15 side. At this time, the first optical sheet 41 can improve the luminance in the normal direction of the first optical sheet 41, typically the luminance in the front direction. The condensing sheet can be configured as a sheet having a plurality of unit prisms arranged along a certain direction on the sheet surface. As such a condensing sheet, for example, “BEF” (registered trademark) available from 3M USA can be used.

  A reflective polarizing plate can be used as the second optical sheet 42. The second optical sheet 42 serving as a reflective polarizing plate transmits a linearly polarized light component in a direction parallel to the transmission axis, and reflects a linearly polarized light component in a direction parallel to the reflection axis perpendicular to the transmission axis. That is, the second optical sheet 42 functions as a reflective polarization separation sheet. According to the second optical sheet 42, light of a linearly polarized light component that is emitted from the surface light source device 20 and cannot be effectively used by the display panel 15 enters the display panel 15 and is absorbed by the polarizing plate. Can be prevented. Therefore, the illuminance characteristics can be improved by improving the use efficiency of the light source light. As this reflective polarizing plate, for example, “DBEF” (registered trademark) available from 3M Corporation of the United States can be used.

  Hereinafter, the adjustment plate 45, the diffusion plate 50, and the auxiliary diffusion unit 55 will be described in more detail. First, the adjustment plate 45 will be described in detail.

  As described above, the adjustment plate 45 has a function of adjusting the amount of light transmitted through each region of the adjustment plate 45. FIG. 5 is a plan view showing one partition area Aa of the adjustment plate 45. In the illustrated example, one partition area Aa of the adjustment plate 45 is divided into a plurality of element areas Ab. The illustrated adjustment plate 45 adjusts the amount of light transmitted therethrough for each element region Ab. Specifically, the adjustment plate 45 has a transmission part that mainly transmits light and a non-transmission part that mainly blocks light. By adjusting the area ratio between the transmission part and the non-transmission part for each element region Ab, the amount of transmitted light in each element region Ab can be controlled. Moreover, the utilization efficiency of the light from a light source can be improved by comprising so that a non-transmissive part may have reflectivity. Furthermore, since the transmissive part has diffusibility, in addition to the in-plane distribution of illuminance, the in-plane distribution of luminance can be adjusted. In the adjustment plate 45 described below with reference to the drawings, the transmission part is a transmission hole 46a formed in the base material 46 having scattering reflectivity, and the non-transmission part is formed with the transmission hole 46a. This is a portion having the scattering reflectivity of the base material 46 that is not.

  FIG. 5 shows a specific example of the arrangement pattern of the element regions Ab and the transmission holes 46a. The adjustment plate 45 includes a base material 46 in which a plurality of transmission holes 46 a that transmit light emitted from the light source 22 are formed. By adjusting the size and arrangement of the transmission holes 46a, the adjustment ability of the illuminance in-plane distribution by the adjustment plate 45 can be controlled.

  In the example shown in FIG. 5, one partition area Aa of the adjustment plate 45 is divided into a plurality of regularly arranged element areas Ab. Each element region Ab has a hexagonal shape in plan view, and particularly has a regular hexagonal shape in plan view. The plurality of element regions Ab have the same shape with the same area. The plurality of element regions Ab are arranged at the same arrangement pitch. Specifically, the plurality of element regions Ab have gaps in the partition region Aa such that two adjacent element regions Ab share one side and three element regions Ab share one vertex. They are lined up. Thus, the plurality of element regions Ab are arranged in a so-called honeycomb shape. One adjustment plate 45 is provided in each element region Ab. In the illustrated adjustment plate 45, the in-plane distribution of the transmitted light amount and, as a result, the in-plane distribution of illuminance are adjusted by changing the size of the transmission hole 46a between the plurality of element regions Ab. .

  As shown in FIG. 5, the plurality of transmission holes 46 a are arranged in a pattern in which the opening area of each of the plurality of transmission holes 46 a increases as the distance from the center C of the partition area Aa facing directly above the light source 22 increases. . That is, as the distance from the light source 22 increases, the aperture ratio (= light transmission hole area / element area area) in the corresponding element region Ab increases. Such an adjustment plate 45 functions to make the transmitted light amount in each region uniform in the plane. In other words, the adjustment plate 45 functions to make the in-plane distribution of illuminance uniform.

Here, the dimensions of the transmission hole 46a is, to vary so as to increase toward the element region Ab ₁ to the periphery of the compartment area Aa, the size of the transmission hole 46a is directed from the element region Ab ₁ to the periphery of the compartment area Aa This includes not only the case where it always changes so as to increase, but also the case where the dimension of the transmission hole 46a does not change in some areas. In other words, the dimensions of the transmission hole 46a is, to vary so as to increase toward the element region Ab ₁ to the periphery of the compartment area Aa, the size of the transmission hole 46a is directed from the element region Ab ₁ to the periphery of the compartment area Aa This means that the region does not change so as to become smaller. In the example shown in FIG. 5, the dimension of the transmission hole 46 a changes so as to always increase from the element region Ab ₁ toward the periphery of the partition region Aa. In the illustrated example, the center of each transmission hole 46a coincides with the center of the element region Ab in which the transmission hole 46a is disposed. Accordingly, the plurality of transmission holes 46a are formed in the adjustment plate 45 so that the distance between the centers of the transmission holes 46a arranged adjacent to each other is constant.

In FIG. 5, the position of the light source 22 arranged on the back side of the adjustment plate 45 is indicated by a broken line. The plurality of element regions Ab include an element region Ab ₁ that overlaps the light source 22 when projected along the normal direction of the substrate 46. In particular, in the illustrated example, one element region Ab ₁ is located at the center C of the partition region Aa. Here, the element region Ab ₁ overlaps with the light source 22 when projected along the normal direction of the base material 46. That at least a part of the element region Ab ₁ is in the normal direction of the base material 46. It means overlapping with the light source 22 when projected along. Therefore, the relative positional relationship between the light source 22 and the partitioned area Aa is not limited to the example shown in FIG. For example, the plurality of element regions Ab may be arranged so that the vertex shared by the three element regions Ab ₁ overlaps the center of the light source 22 when projected along the normal direction of the base material 46. In this case, each of the three element regions Ab ₁ including the vertex overlaps the light source 22 when projected along the normal direction of the substrate 46.

In the example shown in FIG. 5, one transmission hole 46a is formed in each of the element regions Ab including the element region Ab ₁ located immediately above the light source. In other words, each element region Ab is defined so as to include one transmission hole 46a. Therefore, a partition line that partitions each adjacent element region Ab is positioned between two adjacent transmission holes 46a. More specifically, the dividing line that divides the adjacent element region Ab is a part of a perpendicular bisector along the plate surface of the base material 46 that connects the centers of the two adjacent transmission holes 46a. Can be defined as

The planar view shape of each element region Ab is not limited to the regular hexagonal shape shown in FIG. For example, the planar view shape of each element region Ab may be a regular square (square) shape as shown in FIG. In the example shown in FIG. 14, the plurality of element regions Ab and the plurality of transmission holes 46 a are first arranged so that each of the four sides constituting each element region Ab is shared with other adjacent element regions Ab. it can be continuously arranged in each direction d ₁ and the second direction d _2.

The shape of each element region Ab in plan view may be other shapes. For example, although not shown, a regular octagonal shape and a regular rectangular shape may be mixed. In this case, among the eight sides of each element region Ab having a regular octagon shape, the four sides extending in parallel with each of the first direction d ₁ and the second direction d ₂ are the other element regions of the adjacent regular octagon shape. The plurality of element regions are shared by Ab and the other four sides extending non-parallel to each of the first direction d ₁ and the second direction d ₂ are shared with the adjacent regular tetragonal element region Ab. Ab and a plurality of transmission holes 46a can be arranged continuously.

  In the illustrated example, each transmission hole 46a has a circular outline in plan view. However, the present invention is not limited thereto, and each transmission hole 46a may be formed to have another planar shape such as an ellipse, a triangle, a rectangle, and a hexagon in plan view.

  The adjustment plate 45 is configured to reflect light incident on the adjustment plate 45 with high efficiency and bend the optical path toward the light reflection layer 36. Such an adjustment plate 45 can effectively adjust the illuminance distribution by the arrangement and shape of the transmission holes 46a. The adjusting plate 45 functions to improve the utilization efficiency of the light emitted from the light source 22 by reflecting the light that does not pass through. Therefore, the base 46 of the adjustment plate 45 is preferably a layer having high reflectivity with respect to light in the visible light wavelength region. The base material 46 is formed of, for example, a white resin material. As an example, the base material 46 may be formed of a foamed resin such as foamed polyethylene terephthalate (foamed PET). The thickness of the adjusting plate 45 can be 50 μm or more and 700 μm or less.

  In the illustrated example, the adjustment plate 45 has a base 46 formed of a material having low light transmittance. The transmission hole 46a is a physical hole formed in the base material 46, that is, a through hole extending from one main surface to the other main surface of the two main surfaces of the opposing base material 46. The specific configuration of the transmission hole 46a is not limited to this. The transmission hole 46a only needs to be formed as a portion through which light can be transmitted from one side in the normal direction to the plate surface of the adjustment plate 45 to the other side. For example, the adjustment plate 45 is a plate having light transmittance. And a light reflecting layer provided on the transparent substrate, particularly on the main surface of the transparent substrate on the light source 22 side, and a transmission hole 46a is provided in the light reflecting layer. It may be configured as an open portion. In this case, it is not necessary to provide physical holes in the transparent substrate. That is, the concept of the light transmission hole (light transmission part) 46a includes not only a physical hole but also a part that can transmit light.

  As shown in FIG. 4, the light emitted from the light source 22 toward the adjustment plate 45 is reflected by the adjustment plate 45 and travels toward the light reflection layer 36 side. The light incident on the light reflection layer 36 is reflected by the light reflection layer 36 and travels toward the adjustment plate 45. When light that has been repeated is incident on one of the transmission holes 46a of the adjustment plate 45, the light is transmitted through the transmission holes 46a and directed from the adjustment plate 45 to the display panel 15 side (the diffusion plate 50 side in FIG. 4). And exit. As described above, the opening area of the transmission hole 46a increases as the distance from the center C of the partition area Aa facing the light source 22 immediately above the light source 22 increases. That is, in the region near the center C of the partition region Aa where the amount of light traveling through the space between the adjustment plate 45 and the light reflecting layer 36 increases, the diameter of the transmission hole 46a is small, so that the light enters the transmission hole 46a. Difficult to enter. On the other hand, in the region separated from the center C of the partition region Aa where the amount of light traveling through the space between the adjusting plate 45 and the light reflecting layer 36 is small, the hole diameter of the transmission hole 46a is increased, so that light is transmitted. It becomes easy to enter the hole 46a. Thereby, the in-plane distribution of the amount of light transmitted through each area of the adjustment plate 45 is made uniform. As a result, the in-plane distribution of illuminance can be made uniform on the light output side of the adjustment plate 45.

  When the spacer 23 is made of a material having high reflectivity with respect to light in the visible light wavelength region, the light traveling in the direction substantially parallel to the plate surface of the adjustment plate 45 and entering the wall portion 24 of the spacer 23 is The light path is reflected by the spacer 23 and bent toward the light source 22 side. Thereby, when implementing local dimming, the light emission area | region used as an element can be made narrower.

  Next, the diffusion plate 50 and the auxiliary diffusion part 55 will be described in detail. Both the diffuser plate 50 and the auxiliary diffuser 55 have a function of diffusing incident light. As described above, according to the adjustment plate 45, the in-plane distribution of illuminance in each partition area Aa can be made uniform. However, in one element region Ab, the luminance varies such that the luminance is high immediately above the transmission hole 46a and the luminance is low in other regions. The diffusing plate 50 and the auxiliary diffusing portion 55 scatter the transmitted light to eliminate in-plane luminance unevenness. Therefore, the combination of the adjustment plate 45, the diffusion plate 50, and the auxiliary diffusion unit 55 makes it possible to uniformize the in-plane distribution of luminance, typically the fine in-plane distribution of luminance of the light emitting surface 20a.

  The diffusing plate 50 and the auxiliary diffusing portion 55 can employ various configurations that can exhibit a light diffusing function. The diffusing plate 50 and the auxiliary diffusing portion 55 have, for example, a configuration having internal diffuse reflectivity, and more specifically, may include a base material and a diffusion component dispersed in the base material. The diffusion component is a component that can exhibit a function of changing the direction of the light path by reflection or refraction. As the diffusing component, a component that itself has reflectivity or a component that has a refractive index different from that of the substrate and forms a refractive interface with the substrate can be used. Specific examples of the diffusion component include a metal compound, a porous material containing gas, resin beads holding the metal compound around, white fine particles, and simple bubbles. An example of white particles forming the diffusing component is acrylic resin particles to which titanium oxide is added.

  As another example of the diffuser plate 50 and the auxiliary diffuser 55, for example, the diffuser plate 50 and the auxiliary diffuser 55 may be formed as a surface uneven layer. Good. A surface uneven | corrugated layer is a layer with the uneven surface which expresses a light-diffusion function. As an example, the surface uneven layer can be a layer formed on the surface of the substrate by embossing. Another example of the surface uneven layer is a layer formed by fixing fine particles on the surface of a substrate with a small amount of a binder resin. Here, the trace amount of binder resin refers to an amount of the binder resin that does not completely cover the fine particles, or an amount of the binder resin that forms irregularities due to the presence of the fine particles. The diffuser plate 50 and the auxiliary diffuser 55 may have both internal diffuse reflectivity and external diffuse reflectivity.

Diffusing plate 50, a plate-like member, it extends in a region facing the adjusting plate 45 in the thickness direction d _3. The thickness of the diffusion plate 50 can be, for example, about 200 μm or more and 3000 μm or less. If it is less than 200 μm, it will be difficult to install the first optical sheet 41 and the second optical sheet 42 in a plane, and if it exceeds 3 mm, it may be difficult to make the surface light source device thinner.

Here, FIG. 20 shows the surface light source device 120 before improvement, which is not devised in the present embodiment. The surface light source device 120 includes a base laminate 30, a light source 22, a spacer 23, and an optical laminate 40 as in the present embodiment. However, the optical laminated body 40 of the surface light source device 120 includes only the first optical sheet 41, the second optical sheet 42, the adjustment plate 45, and the diffusion plate 50. In other words, the surface light source device 120 before improvement does not include the auxiliary diffusion unit 55. Between the base laminate 30 and the adjustment plate 45, a gap is formed having a length D1 in the thickness direction d _3. This length D1 can be about 1 mm or more and 10 mm or less.

Further, the before improvement of the surface light source device 120, also between the diffusion plate 50 and the adjustment plate 45, a gap having a length D2 in the thickness direction d ₃ is formed. The length D2 can be set to about 1 mm or more and 5 mm or less. As proved by the simulation results of Reference Example 1 and Reference Example 2 to be described later, the in-plane distribution of luminance is sufficiently uniformed unless a gap is provided between the adjustment plate 45 and the diffusion plate 50. I could not. More specifically, a bright portion that is observed brightly locally is generated in a portion directly above the light source 22 and in a portion directly above the transmission hole 46a. On the other hand, by providing a gap between the adjustment plate 45 and the diffusion plate 50, diffusion in the surface direction is promoted, and a bright portion is formed directly above the light source 22 and directly above the transmission hole 46a. No longer visible. For this reason, in the surface light source device 120 before the improvement, it is necessary to provide a gap having a sufficient thickness D2 between the adjustment plate 45 and the diffusion plate 50 particularly in the backlight application. This has been a cause of increasing the thickness of the surface light source device 120.

  On the other hand, in the surface light source device 20 according to the present embodiment, as shown in FIGS. 6 to 10, the optical laminated body 40 further includes an auxiliary diffusion portion 55 in addition to the diffusion plate 50. ing. Then, by arranging the auxiliary diffusing portion 55 in a specific positional relationship with the adjusting plate 45 and the diffusing plate 50, it was possible to remarkably improve the ability to uniformize the luminance in-plane distribution of the surface light source device 20. . By enhancing the function of uniforming the luminance in-plane distribution by the surface light source device 20, the need to provide a sufficient gap D2 between the adjustment plate 45 and the diffusion plate 50 is eliminated, as shown in FIGS. It became possible to do.

In this embodiment, the diffusion plate 50 is positioned on the opposite side of the light source 22 of the adjusting plate 45 in the thickness direction d _3. In other words, the adjustment plate 45 in the thickness direction d _3, is positioned between the light source 22 and the diffusion plate 50. Diffusing plate 50, a plate-like member, it extends in a region facing the adjusting plate 45 in the thickness direction d _3. Auxiliary diffusion unit 55 is arranged offset in the thickness direction d ₃ from the diffusion plate 50. At least one of the diffusing plate 50 and the auxiliary diffusing portion 55 is disposed adjacent to the adjusting plate 45. Here, “adjacent” means not only that at least one of the diffusion plate 50 and the auxiliary diffusion portion 55 is in surface contact, line contact or point contact with the adjustment plate 45, but also the diffusion plate 50 and auxiliary diffusion portion 55. That at least one of these is close to the adjustment plate 45 without interposing another member between the adjustment plate 45, in other words, at least one of the diffusion plate 50 and the auxiliary diffusion part 55 is the adjustment plate. That there is a slight gap between the adjustment plate 45 and no other member, for example, at least one of the diffusion plate 50 and the auxiliary diffusion portion 55 is between the adjustment plate 45 It also includes being close to 500 μm or less to the adjustment plate 45 without interposing other members.

  6 to 10 disclose a plurality of configuration examples related to the adjustment plate 45, the diffusion plate 50, and the auxiliary diffusion unit 55 in the present embodiment. According to the surface light source device 20 shown in FIGS. 6 to 10, none of the gaps having a constant thickness D <b> 2 is provided between the adjustment plate 45 and the diffusion plate 50 of the optical laminate 40. . Therefore, compared with the surface light source device 120 before the improvement shown in FIG. 20, the thickness can be significantly reduced.

Among these, in the example shown in FIG. 6, the auxiliary diffusion portion 55 is formed as a diffusion layer or a diffusion sheet. Auxiliary diffusion portion 55 is adjacent the side of the light source 22 to the adjusting plate 45 in the thickness direction d _3. The auxiliary diffusion part 55 may be in close contact with the adjustment plate 45. For example, the auxiliary diffusion portion 55 may be formed as a diffusion layer on the surface of the adjustment plate 45 on the light source 22 side. The diffusion plate 50 is adjacent to the adjustment plate 45 from the opposite side to the light source 22 in the thickness direction d _3.

In the example shown in FIG. 7, the auxiliary diffusion portion 55 is located in the transmission hole 46 a of the adjustment plate 45. That is, the auxiliary diffusion part 55 is provided in contact with the adjustment plate 45. Such an auxiliary diffusion part 55 can be produced by supplying an uncured resin composition containing a diffusion component into the permeation hole 46a, and then curing the resin composition within the permeation hole 46a. In the example shown in FIG. 7, the diffusion plate 50 is adjacent to the adjustment plate 45 from the opposite side to the light source 22 in the thickness direction d _3.

In the example shown in FIG. 8, the auxiliary diffusing portion 55 is located in the transmission hole 46 a of the adjustment plate 45 as in the example shown in FIG. 7. However, the auxiliary diffusing portion 55 is overflowing to the side of the light source 22 in the thickness direction _{d 3} of the adjustment plate 45 from the transmission hole 46a. As a result, the auxiliary diffusion part 55 includes a sheet part 56a that covers the surface of the adjustment plate 45 on the light source 22 side, and a protrusion part 56b that protrudes from the sheet part 56a and is located in the transmission hole 46a of the optical laminate 40. It is out. The auxiliary diffusing portion 55 shown in FIG. 8 is similar to the auxiliary diffusing portion 55 shown in FIG. 7 in that an uncured resin composition containing a diffusing component is applied to the inside of the transmission hole 46a and the light source of the adjusting plate 45. It can be produced by supplying and curing on the 22 side surface.

In the example shown in FIG. 9, the auxiliary diffusion part 55 is formed as a diffusion layer or a diffusion sheet. Auxiliary diffusion portion 55 is located between the diffusion plate 50 and the adjusting plate 45 in the thickness direction d _3. The auxiliary diffusion part 55 is adjacent to the adjustment plate 45 and also adjacent to the diffusion plate 50. The auxiliary diffusion part 55 may be in close contact with at least one of the adjustment plate 45 and the diffusion plate 50. The auxiliary diffusion part 55 may be formed as a diffusion layer on at least one of the adjustment plate 45 and the diffusion plate 50.

In the example shown in FIG. 10, the auxiliary diffusion part 55 is formed as a diffusion layer or a diffusion sheet. Auxiliary diffusion portion 55 is located on the opposite side to the side of the light source 22 of the diffusion plate 50 in the thickness direction d _3. Auxiliary diffusion portion 55 is adjacent to the diffusion plate 50 from the opposite side to the light source 22 in the thickness direction d _3. Diffuser 50 is adjacent to the adjustment plate 45 from the opposite side to the light source 22 in the thickness direction d _3. The auxiliary diffusion part 55 may be in close contact with the diffusion plate 50. The auxiliary diffusion part 55 may be formed as a diffusion layer on one surface of the diffusion plate 50.

  As in the present embodiment, in addition to the diffusing plate 50, an auxiliary diffusing portion 55 is provided, and further, at least one of the diffusing plate 50 and the auxiliary diffusing portion 55 is adjacent to the adjusting plate 45, whereby the luminance in-plane distribution is obtained. Although the details of the reason why the homogenization ability is enhanced are unknown, it is assumed that the following is one of the factors. That is, in this embodiment, the light diffused by one of the diffusion plate 50 and the auxiliary diffusion unit 55 is then incident on the other of the diffusion plate 50 and the auxiliary diffusion unit 55 and further diffused. At this time, the combination of the diffusion in the diffusion plate 50 and the diffusion in the auxiliary diffusion unit 55 promotes the in-plane spread of the light at the portion where the luminance protrudes, and thereby the in-plane luminance on the light emitting surface 20a. It is expected that the distribution can be made uniform efficiently. However, the present disclosure is not bound by this assumption.

Further, in the surface light source device 20 of the present embodiment, the diffusivity of the auxiliary diffusion portion 55 is stronger than the diffusivity of the diffusion plate 50, and the thickness along the thickness direction d ₃ of the auxiliary diffusion portion 55 is the thickness of the diffusion plate 50. it is preferable that thinner than the thickness in the thickness direction d _3. By using such an auxiliary diffusing portion 55, the ability to equalize the luminance in-plane distribution by the optical laminate 40 can be further enhanced.

  Although the details of the reason why the ability to uniformize the luminance in-plane distribution is enhanced by the installation of such an auxiliary diffusion part are unknown, it is assumed that the following is one of the factors. That is, according to the auxiliary diffusing portion 55 having a strong diffusing capacity, the traveling direction of light can be effectively dispersed. Thereby, it is expected that the luminance distribution can be effectively made uniform. On the other hand, since the auxiliary diffusion part 55 is relatively thin, an increase in the total thickness of the surface light source device 20 can be suppressed. However, the present disclosure is not bound by this assumption.

For example, in the example shown in FIGS. 6, 9, and 10, the thickness of the auxiliary diffusion portion 55 along the thickness direction d ₃ can be set to 50 μm or more and 1000 μm or less. In the diffusing plate 50 shown in FIG. 7, the thickness along the thickness direction d ₃ of the auxiliary diffusing portion 55 is the same as the thickness of the adjusting plate 45 and can be 50 μm or more and 700 μm or less. In the diffusion plate 50 shown in FIG. 8 and the thickness along the thickness direction _{d 3} of the auxiliary diffusion unit 55, as the total thickness of the seat portion 56a and the protrusion 56b, it is possible to 50μm or more 1700μm or less. Meanwhile, a thickness along the thickness direction d ₃ of the diffusion plate 50 is made thicker than the thickness along the thickness direction d ₃ of the auxiliary diffusion portion 55 can be set to 200μm or more 3000μm or less.

The degree of diffusivity of the diffuser plate 50 and the auxiliary diffuser 55 can be evaluated by measuring the angular distribution of luminance when transmitting parallel light and measuring the full width at half maximum [°]. The greater the full width at half maximum, the stronger the diffusivity. The angular distribution of luminance is a luminance distribution on the light emitting side surface of the diffusing plate 50 or the auxiliary diffusing portion 55 in each direction in a plane along the normal direction of the diffusing plate 50 or the auxiliary diffusing portion 55. The full width at half maximum is an angular range in a direction in which a luminance that is half or more of the peak luminance in the luminance angular distribution is obtained. The full width at half maximum is specified as an average of the full width at half maximum calculated from the angular distribution of luminance measured on two surfaces orthogonal to each other along the normal direction of the diffusion plate 50 and the auxiliary diffusion portion 55. For example, in the illustrated example, the full width at half maximum in the luminance angle distribution in the plane along the first direction d ₁ and the normal direction, and the plane in the plane along the second direction d ₂ and the normal direction. It can be an average value of the full width at half maximum in the luminance angle distribution. A goniometer GCMS-4 manufactured by Murakami Color Research Laboratory Co., Ltd. is used for measuring the angular distribution of luminance.

Furthermore, in the surface light source device 20 of the present embodiment, the diffusivity of the auxiliary diffusing unit 55 is stronger than that of the diffusing plate 50, and the auxiliary diffusing unit 55 is thicker as shown in FIGS. may be positioned between the light source 22 and the diffusion plate 50 in the direction d ₃ is. By using such an auxiliary diffusing portion 55, the ability to equalize the luminance in-plane distribution by the optical laminate 40 can be further enhanced.

Details of the reason why the ability to uniformize the luminance in-plane distribution is enhanced by the installation of the auxiliary diffusion unit 55 is unknown, but it is assumed that the following is one of the factors. In this example, the diffused light diffused by the auxiliary diffusing portion 55 having a strong diffusivity is incident on the thick diffusion plate 50 and diffused. In this case, the diffused light proceeds diffusion plate 50, in a direction perpendicular to the thickness direction d _3, spread larger. As a result, the in-plane distribution of the amount of light emitted from the diffusion plate 50 can be made uniform effectively. From these things, the ability to equalize the luminance in-plane distribution can be further effectively enhanced. However, the present disclosure is not bound by this assumption.

  Here, a simulation result carried out to investigate the in-plane distribution of brightness will be described. First, the simulation target will be described. As simulation targets, Reference Examples 1 and 2 and Examples 1 to 3 of the surface light source device were assumed. First, the surface light source device as a simulation target will be described.

<Reference Example 1>
As shown in FIG. 13, the surface light source device according to Reference Example 1 has a base laminate having a light reflection layer on the surface, a light-emitting diode as a light source disposed on the base laminate, and light emission in the thickness direction. An adjustment plate arranged to face the diode and a diffusion plate arranged on the side opposite to the light emitting diode side of the adjustment plate in the thickness direction were provided. A gap D1 between the light emitting diode and the adjustment plate was set to 2 [mm]. The gap between the adjustment plate and the diffusion plate was 1 [mm].

The diffusion plate was configured by dispersing diffusible particles in a transparent resin substrate. The refractive index of the transparent resin substrate was 1.49. The radius of the diffusible particles was 1 [μm], and the refractive index of the diffusible particles was 1.60. The particle density in the diffusion plate was 1 × 10 ⁸ [pieces / (mm ³ )]. The thickness of the diffusion plate was 500 [μm]. These values were set so that the transmittance of the diffusion plate was 62%.

The adjustment plate has a configuration shown in FIG. That is, the adjusting plate has element regions Ab arranged in a square, and one transmission hole is formed in each element region Ab. The element regions Ab are arranged at a pitch of 2 [mm] in each of the first direction d ₁ and the second direction d ₂ . The transmission hole has a circular shape in plan view. The diameter of the transmission hole formed in the central element region located immediately above the light source is 0.2 mm, and the diameter of the transmission hole formed in the central element region and the eight element regions surrounding the central element region is also 0. .2 [mm]. With respect to the other transmission holes 46a, the diameters of the holes formed in each element region were gradually increased according to the distance from the central element region. The adjusting plate is configured by dispersing particles in a resin base material so as to have high reflectivity. The particle density in the adjusting plate was 1 × 10 ¹¹ [pieces / (mm ³ )].

<Reference Example 2>
As shown in FIG. 13, the surface light source device according to Reference Example 2 has a base laminate having a light reflecting layer on the surface, a light emitting diode as a light source disposed on the base laminate, and light emission in the thickness direction. An adjustment plate arranged to face the diode and a diffusion plate arranged on the side opposite to the light emitting diode side of the adjustment plate in the thickness direction were provided. In the surface light source device according to Reference Example 2, the gap D1 between the light emitting diode and the adjustment plate was set to 2 [mm]. The adjustment plate and the diffusion plate were arranged so as to be in contact with each other in the thickness direction. That is, the surface light source device according to the reference example 2 is different from the surface light source device according to the reference example 1 in that the diffusion plate is brought into contact with the adjustment plate, and is common in others.

  The base laminate including the light reflection layer used in the surface light source device according to Reference Example 2, the light emitting diode as the light source, the adjustment plate, and the diffusion plate were the same as the components used in Reference Example 1.

<Example 1>
As shown in FIG. 13, the surface light source device according to Example 1 has a base laminate having a light reflection layer on the surface, a light emitting diode as a light source arranged on the base laminate, and light emission in the thickness direction. An adjustment plate arranged facing the diode, a diffusion plate arranged adjacent to the adjustment plate from the side opposite to the light emitting diode side of the adjustment plate in the thickness direction, and a light emitting diode of the adjustment plate in the thickness direction And an auxiliary diffusing portion disposed adjacent to the adjustment plate from the side. In the surface light source device according to Example 1, the gap D1 between the light emitting diode and the adjustment plate was set to 2 [mm]. The surface light source device according to Example 1 is different from the surface light source device according to Reference Example 2 in that an auxiliary diffusing portion is provided adjacent to the adjustment plate, and is common in others.

The auxiliary diffusing portion was configured by dispersing diffusible particles in a transparent resin base material. The refractive index of the transparent resin substrate was 1.49. The radius of the diffusible particles was 1 [μm], and the refractive index of the diffusible particles was 1.60. The particle density in the auxiliary diffusion part was 1 × 10 ⁸ [pieces / (mm ³ )]. The thickness of the auxiliary diffusion part was 100 [μm].

  The base laminate including the light reflection layer used in the surface light source device according to Example 1, the light-emitting diode as a light source, the adjustment plate, and the diffusion plate were the same as the components used in Reference Example 1.

<Example 2>
As shown in FIG. 13, the surface light source device according to Example 2 has a base laminate having a light reflection layer on the surface, a light-emitting diode as a light source disposed on the base laminate, and light emission in the thickness direction. An adjustment plate disposed facing the diode, a diffusion plate disposed adjacent to the adjustment plate from the side opposite to the light emitting diode side of the adjustment plate in the thickness direction, and a transmission hole of the adjustment plate. And an auxiliary diffusion part. In the surface light source device according to Example 2, the gap between the light emitting diode and the adjustment plate was set to 2 [mm]. The surface light source device according to Example 2 is different from the surface light source device according to Reference Example 2 in that an auxiliary diffusing portion is provided adjacent to the adjustment plate in the transmission hole of the adjustment plate, and is otherwise common. did.

The auxiliary diffusing portion was configured by dispersing diffusible particles in a transparent resin base material. The refractive index of the transparent resin substrate was 1.49. The radius of the diffusible particles was 1 [μm], and the refractive index of the diffusible particles was 1.60. The particle density in the auxiliary diffusion part was 1 × 10 ⁸ [pieces / (mm ³ )]. The thickness of the auxiliary diffusion part was the same as the thickness of the adjusting plate, and was 0.2 [mm].

  The base laminate including the light reflection layer used in the surface light source device according to Example 2, the light-emitting diode as the light source, the adjustment plate, and the diffusion plate were the same as the components used in Reference Example 1.

<Example 3>
As shown in FIG. 13, the surface light source device according to Example 3 has a base laminate having a light reflecting layer on the surface, a light emitting diode as a light source disposed on the base laminate, and light emission in the thickness direction. An adjustment plate disposed facing the diode, an auxiliary diffusion portion disposed adjacent to the adjustment plate from the side opposite to the light emitting diode side of the adjustment plate in the thickness direction, and an auxiliary diffusion portion in the thickness direction. And a diffusion plate disposed adjacent to the auxiliary diffusion portion from the side opposite to the adjustment plate side. In the surface light source device according to Example 3, the gap between the light emitting diode and the adjustment plate was set to 2 [mm]. In the surface light source device according to Example 3, the auxiliary diffusing unit is provided between the adjustment plate and the diffusion plate so as to be adjacent to both the adjustment plate and the diffusion plate, as compared with the surface light source device according to Reference Example 2. In other respects, it is common to others.

The diffusion plate was configured by dispersing diffusible particles in a transparent resin substrate. The refractive index of the transparent resin substrate was 1.49. The radius of the diffusible particles was 1 [μm], and the refractive index of the diffusible particles was 1.60. The particle density in the diffusion plate was 1 × 10 ⁶ [pieces / (mm ³ )]. The thickness of the diffusion plate was 400 [μm].

The auxiliary diffusing portion was configured by dispersing diffusible particles in a transparent resin base material. The refractive index of the transparent resin substrate was 1.49. The radius of the diffusible particles was 1 [μm], and the refractive index of the diffusible particles was 1.60. The particle density in the auxiliary diffusion part was 4.5 × 10 ⁷ [pieces / (mm ³ )]. The thickness of the auxiliary diffusion part was 100 [μm].

  In Example 3, the above value was set so that the total transmittance of the auxiliary diffusion part and the diffusion plate was 62%.

  The base laminate including the light reflection layer used in the surface light source device according to Example 3, the light-emitting diode as the light source, and the adjustment plate were the same as the components used in Reference Example 1.

  In the surface light source device according to each example configured as described above, on the surface opposite to the light source of the diffusion plate, that is, on the light emission side surface of the diffusion plate, in the normal direction to the surface. The in-plane distribution of luminance was simulated. The results of Example 1 are shown in FIG. 17, the results of Example 2 are shown in FIG. 18, the results of Example 3 are shown in FIG. 19, the results of Reference Example 1 are shown in FIG. 15, and the results of Reference Example 2 are shown. This is shown in FIG. The area to be the target of the simulation results shown in FIG. 15 to FIG. 19 is the light output of the diffuser that overlaps the total nine element areas Ab directly above and around the light source with a diagonal line in FIG. 14 in the thickness direction. The area on the surface. Accordingly, the area showing the in-plane distribution of luminance in FIGS. 15 to 19 has a size of 6 [mm] × 6 [mm]. 15 to 19, the coordinates in the first direction d1 and the second direction d2 are (−2, −2), (−2, 0), (−2, 2), (0, −2). , (0,0), (0,2), (2, -2), (2,0), and (2,2), nine holes were formed in the adjustment plate.

  15 to 19, a region S <b> 1 with vertical line and horizontal line patterning indicates a region where 75% or more of the peak luminance in the simulation result of each example is obtained. 15 to 19, a hatched pattern region S2 indicates a region where a luminance of 50% or more and less than 75% of the peak luminance in the simulation result of each example is obtained. 15 to 19, a region S3 to which dot patterning is applied indicates a region where a luminance of 25% or more and less than 50% of the peak luminance in the simulation result of each example is obtained. 15 to 19, a white region S3 indicates a region where a luminance of 0% or more and less than 25% of the peak luminance in the simulation result of each example is obtained.

  Further, regarding the simulation results of each example, the peak luminance with respect to the average luminance value in the normal direction of the diffusion plate in the region of 6 [mm] × 6 [mm] that is the simulation target shown in FIGS. Was calculated as a peak ratio. That is, the peak ratio is a value specified by “peak ratio = peak luminance value / 6 [mm] × 6 [mm] average luminance value in a region”. Therefore, the peak ratio takes a value of 1 or more, and the closer to 1, the more uniform the in-plane luminance distribution. The peak ratio is shown in FIG.

  Judging from the simulation results, all of Examples 1 to 3 were able to effectively equalize the in-plane distribution of brightness compared to Reference Example 2 having the same thickness. In Example 1, as compared with Reference Example 1, the surface light source device could be significantly thinned while maintaining the uniformity of the in-plane distribution of brightness. Furthermore, in Example 2, the in-plane distribution of brightness was made more uniform than in Reference Example 1, and the thickness of the surface light source device could be significantly reduced.

Although details of the reason why the surface light source devices according to Examples 1 and 2 have extremely excellent luminance in-plane distribution uniformity are unknown, it is speculated that the following two points contribute. The
Strong auxiliary diffusion unit diffusion capacity than, is more-located on the side of the light source in the thickness direction d ₃ than weak diffusion plate diffusion ability, among other things, a stronger auxiliary diffusion unit diffusion capacity is, the transmission hole in the located on the side of the light source in the thickness direction d ₃ than adjusting plate having a diffuse reflectivity even in the side surface of, or even located within the transmission hole of the adjusting plate having a diffuse reflective at transmittance hole.

  In Reference Examples 1 and 2 and Examples 1 to 3, the calculation conditions were set so that the transmittance of the component closer to the light output side than the adjustment plate was 62%. Therefore, in the surface light source devices according to Reference Examples 1 and 2 and Examples 1 to 3, the utilization efficiency of the light emitted from the light source 22 can be said to be equivalent.

In the embodiment described above, adjustment for adjusting the in-plane distribution of the transmitted light amount provided between the light source 22, the diffusion plate 50 provided apart from the light source 22, and the light source 22 and the diffusion plate 50. The light source 22 side of the diffusion plate 50 and the auxiliary diffusion part 55 provided on at least one side opposite to the light source 22 of the diffusion plate 50 are provided. At least one of the diffusing plate 50 and the auxiliary diffusing portion 55 is disposed adjacent to the adjusting plate 45. According to one such embodiment, the auxiliary diffusing portion 55 is provided at a position shifted in the thickness direction d ₃ from the diffusion plate 50. In addition to the diffusing plate 50, an auxiliary diffusing portion 55 is provided, and at least one of the diffusing plate 50 and the auxiliary diffusing portion 55 is disposed adjacent to the adjusting plate 45, so that the luminance in-plane distribution can be made uniform. Can be effectively strengthened. Accordingly, the diffusion plate 50 can be disposed close to the adjustment plate 45, and the surface light source device 20 can be effectively reduced in thickness while maintaining the uniformity of the in-plane distribution of luminance.

In the specific example of the embodiment described above, the diffusion capacity of the auxiliary diffusion portion 55 is stronger than that of the diffusion plate 50, and the thickness along the uniaxial direction d ₃ of the auxiliary diffusion portion 55 is uniaxial direction d of the diffusion plate 50. It is thinner than the thickness along ₃ . Such an auxiliary diffusion portion 55 by providing offset from the diffusion plate 50 in the thickness direction d _3, it is possible to more effectively enhance the uniformity Kano in-plane distribution of luminance. Moreover, since the thickness of the auxiliary | assistant diffusion part 55 is thin, the thickness increase of the surface light source device 20 by providing the auxiliary | assistant diffusion part 55 can be avoided effectively. Accordingly, the diffusion plate 50 can be disposed close to the adjustment plate 45, and the surface light source device 20 can be effectively reduced in thickness while maintaining the uniform distribution of luminance in the surface.

In an embodiment of the embodiment described above, the diffusion capacity of the auxiliary diffusion portion 55 is stronger than the diffusing power of the diffusing plate 50, auxiliary diffusion unit 55, between the light source 22 and the diffusion plate 50 in the axial direction d ₃ positioned. According to such an auxiliary diffusion unit 55, the ability to equalize the in-plane distribution of luminance can be further effectively enhanced. Accordingly, the diffusion plate 50 can be disposed close to the adjustment plate 45, and the surface light source device 20 can be effectively reduced in thickness while maintaining the uniformity of the in-plane distribution of luminance.

  In the specific example of the embodiment described above, the auxiliary diffusing unit 55 is located between the adjustment plate 45 and the light source 22. The auxiliary diffusing unit 55 is located closer to the light source 22 than the adjustment plate 45. Accordingly, it is possible to avoid an increase in the thickness of the surface light source device 20 due to the provision of the auxiliary diffusion portion 55.

  In the specific example of the embodiment described above, the auxiliary diffusion portion 55 is located in the transmission hole 46 a of the adjustment plate 45. According to this example, the light that passes through the adjustment plate 45 through the transmission hole 46 a is diffused by the auxiliary diffusion portion 55. Therefore, light can be efficiently diffused by the small amount of auxiliary diffusion part 55. In addition, an increase in the thickness of the surface light source device 20 due to the provision of the auxiliary diffusion portion 55 can be avoided.

  In the specific example of the embodiment described above, the auxiliary diffusion portion 55 is adjacent to the adjustment plate 45, and the diffusion plate 50 is adjacent to the adjustment plate 45. According to this example, it is possible to drastically reduce the surface light source device 20 while effectively equalizing the in-plane distribution of luminance.

  In the specific example of the above-described embodiment, the auxiliary diffusing portion 55 is located between the adjustment plate 45 and the diffusing plate 50. The surface light source device 20 can be drastically reduced in thickness while the light source 22 side of the adjustment plate 45 is configured in the same manner as the conventional one.

  In the specific example of the embodiment described above, the auxiliary diffusion portion 55 is adjacent to the adjustment plate 45, and the diffusion plate 50 is adjacent to the auxiliary diffusion portion 55. According to this example, it is possible to drastically reduce the surface light source device 20 while effectively equalizing the in-plane distribution of luminance.

  In the specific example of the embodiment described above, the auxiliary diffusion portion 55 is located on the opposite side of the diffusion plate 50 from the adjustment plate 45. The surface light source device 20 can be drastically reduced in thickness while the light source 22 side of the adjustment plate 45 is configured in the same manner as the conventional one.

  In the specific example of the embodiment described above, the diffusion plate 50 is adjacent to the adjustment plate 45, and the auxiliary diffusion portion 55 is adjacent to the diffusion plate 50. According to this example, the surface light source device can be drastically reduced in thickness while effectively equalizing the in-plane distribution of luminance.

  Although one embodiment has been described with a plurality of specific examples, these specific examples are not intended to limit the one embodiment. The embodiment described above can be implemented in various other specific examples, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, for parts that can be configured in the same manner as the specific examples described above, the same reference numerals as those used for the corresponding parts in the specific examples described above are used, and overlapping descriptions are given. Is omitted.

  For example, in the above-described embodiment, the optical laminate 40 includes the first optical sheet 41 and the second optical sheet 42. However, the first optical sheet 41 and the second optical sheet 42 are not essential. In addition, each component included in the optical laminate 40, for example, the adjustment plate 45, the diffusion plate 50, the auxiliary diffusion unit 55, the first optical sheet 41 and the second optical sheet 42 may be bonded to each other, It may be simply laminated. When two adjacent components are simply placed one on top of the other, it is effective to make at least one of the two faces of the two components facing each other in order to avoid problems such as the occurrence of Newton rings. It is.

Further, as shown in FIGS. 11 and 12, the spacer 23 forming the outer wall portion 24b may have a different configuration from the spacer 23 forming the partition wall portion 24a shown in FIGS. In the example shown in FIGS. 11 and 12, the spacer 23 includes a first supporting surface 23a for supporting the diffusion plate 50, located on the side of the light source 22 in the thickness direction d ₃ than the first supporting surface 23a Adjustment and it includes a second supporting surface 23b which supports the plate 45, a stepped surface 23c which extends in the thickness direction _{d 3} between the first supporting surface 23a and the second supporting surface 23b, a. It stepped surface 23c is facing the side surface of the adjustment plate 45 from the side perpendicular to the thickness direction d _3, to restrict the movement of the side of the adjusting plate 45. That is, the step surface 23 c connects the first support surface 23 a and the second support surface 23 b and faces the side surface of the adjustment plate 45. Further, a fixing means 60 for pressing the diffusion plate 50 toward the spacer 23 is provided. The fixing means 60 is constituted by a clip or the like, for example. According to this example, the adjustment plate 45 and the diffusion plate 50 can be stably held. As a result, the optical function expected by the adjusting plate 45 and the diffusing plate 50 can be stably exhibited with respect to the light source light. The spacer 23 has a protrusion configured to protrude from the second support surface 23b, and the top surface of the protrusion is configured as the first support surface 23a. The protrusion of the spacer 23 may be configured to have a through hole into which the spacer 23 can be inserted, and the movement of the adjustment plate 45 may be restricted by the protrusion and the through hole. In this case, the step surface 23c corresponds to the side surface of the projection, that is, the side surface of the through hole faces the side surface of the projection.

  11 shows an example in which the spacer 23 including the first support surface 23a and the second support surface 23b is applied to the stacked body 40 shown in FIG. However, the spacer 23 shown in FIG. 11 can be applied not only to the laminated body 40 shown in FIG. 6 but also to the laminated body 40 shown in FIGS. In this case, in the surface light source device 20 illustrated in FIGS. 6 to 8, the diffusion plate 50, the first optical sheet 41, and the second are supported by the first support surface 23 a of the spacer 23 that forms the outer wall portion 24 b illustrated in FIG. 11. The optical sheet 42 is supported. The fixing means 60 presses and fixes the diffusion plate 50, the first optical sheet 41, and the second optical sheet 42 toward the spacer 23. On the other hand, the adjustment plate 45 and the auxiliary diffusion part 55 are supported by the second support surface 23 b of the spacer 23.

In addition, in the example of applying the spacers 23 of FIG. 11 with respect to the laminate 40 shown in FIG. 6, the length in the thickness direction d ₃ of the stepped surface 23c is, the adjustment plate 45 the thickness direction d ₃ is preferably larger than the sum of the thickness along the thickness direction d ₃ of the auxiliary diffusion portion 55. In the example of applying the spacers 23 of FIG. 11 with respect to the laminate 40 shown in FIG. 7, the length along the thickness direction d ₃ of the stepped surface 23c is, the adjustment plate 45 the thickness direction d It is preferable that the thickness is larger than ₃ . Further, in the example of applying the spacers 23 of FIG. 11 with respect to the laminate 40 shown in FIG. 8, the length along the thickness direction d ₃ of the stepped surface 23c is, the adjustment plate 45 the thickness direction d the thickness along the _3, the thickness in the thickness direction d ₃ of the seat portion 56a of the auxiliary diffusion portion 55, is preferably larger than the sum of. The adjustment plate 45 includes a base material 46 formed of, for example, a foamed resin. When the adjustment plate 45 receives a compressive force from the fixing means 60, the adjustment plate 45 may be crushed. By adjusting the length of the step surface 23c, a very slight gap is formed between the adjustment plate 45 and the components such as the diffusion plate 50 adjacent to the adjustment plate 45, and the adjustment plate 45 is crushed. It can be effectively prevented.

  FIG. 12 shows an example in which the spacer 23 including the first support surface 23a and the second support surface 23b is applied to the stacked body 40 shown in FIG. However, the spacer 23 shown in FIG. 12 can be applied not only to the laminated body 40 shown in FIG. 10 but also to the laminated body 40 shown in FIG. In this case, in the surface light source device 20 shown in FIGS. 9 and 10, the diffusion plate 50, the auxiliary diffusion portion 55, and the first optical are formed by the first support surface 23 a of the spacer 23 that forms the outer wall portion 24 b shown in FIG. 12. The sheet 41 and the second optical sheet 42 are supported. The fixing means 60 presses and fixes the diffusion plate 50, the auxiliary diffusion unit 55, the first optical sheet 41, and the second optical sheet 42 toward the spacer 23. On the other hand, the adjustment plate 45 is supported by the second support surface 23 b of the spacer 23.

In addition, in the example of applying the spacers 23 of FIG. 12 with respect to the laminated body 40 shown in FIGS. 9 and 10, the length along the thickness direction d ₃ of the stepped surface 23c is, the thickness of the adjustment plate 45 it is preferably larger than the thickness along the direction d ₃ is. By adjusting the length of the stepped surface 23c in this way, a very small gap is formed between the adjustment plate 45 and components such as the diffusion plate 50 adjacent to the adjustment plate 45, and the adjustment plate 45 Can be effectively prevented.

  Further, when the surface light source device 20 emits light, the diffusion plate 50 and the spacer 23 are expected to rise in temperature. In the above-described embodiment, the diffusion plate 50 is fixed to the spacer 23 that forms the wall portion 24. If there is a large difference between the thermal expansion amount of the diffusion plate 50 and the thermal expansion amount of the spacer 23, the surface light source device 20 is deformed. In this case, the optical laminated body 40 may not be able to exert the expected optical action on the light from the light source 25. In order to prevent such deformation such as distortion at the time of temperature rise of the surface light source device 20, the ratio of the thermal expansion coefficient of the resin material forming the diffusion plate 50 to the thermal expansion coefficient of the resin material forming the spacer 23 is 80% or more. It is preferably 120% or less, and in particular for in-vehicle applications, it is preferably 90% or more and 110% or less because it is placed in an environment where the temperature rises more easily. Further, the resin material forming the diffusion plate 50 and the resin material forming the spacer 23 are preferably the same type, for example, both are preferably polycarbonate.

  In addition, although the some modification with respect to embodiment mentioned above was demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

d ₁ first direction d ₂ second direction d ₃ thickness direction Aa partition area Ab element area 10 display device 10a display surface 15 display panel 20 surface light source device 20a light emitting surface 22 light source 23 spacer 23a first support surface 23b second support Surface 23c Stepped surface 24 Wall portion 24a Partition wall portion 24b Outer wall portion 25 Opening 30 Base laminate 31 Base material 32 Bonding layer 33 Film substrate 34 Wiring layer 35 Resist layer 36 Light reflecting layer 37 Conductive connection layer 40 Optical laminate 41 First Optical sheet 42 Second optical sheet 45 Adjustment plate
46 Base material 46a Transmission hole 50 Diffusion plate 55 Auxiliary diffusion part 56a Sheet part 56b Projection part 60 Fixing means

Claims (13)

A light source;
A diffusion plate provided apart from the light source;
An adjusting plate that is provided between the light source and the diffusion plate and adjusts the in-plane distribution of the transmitted light amount;
An auxiliary diffusion part provided on at least one side of the diffusion plate on the light source side and the light source side of the diffusion plate,
A surface light source device in which at least one of the diffusion plate and the auxiliary diffusion portion is disposed adjacent to the adjustment plate. The diffusivity of the auxiliary diffusion part is stronger than the diffusivity of the diffusion plate,
The surface light source device according to claim 1, wherein a thickness of the auxiliary diffusion portion is thinner than a thickness of the diffusion plate. The diffusivity of the auxiliary diffusion part is stronger than the diffusivity of the diffusion plate,
The surface light source device according to claim 1, wherein the auxiliary diffusion unit is located between the light source and the diffusion plate.   The surface light source device according to claim 1, wherein the auxiliary diffusing unit is located between the adjustment plate and the light source. The adjustment plate has a transmission hole for light transmission,
The surface light source device according to claim 1, wherein the auxiliary diffusing portion is located in the transmission hole of the adjustment plate.   The surface light source device according to claim 4, wherein the auxiliary diffusing unit is adjacent to the adjustment plate, and the diffusion plate is adjacent to the adjustment plate.   The surface light source device according to claim 1, wherein the auxiliary diffusing unit is located between the adjusting plate and the diffusing plate.   The surface light source device according to claim 7, wherein the auxiliary diffusion unit is adjacent to the adjustment plate, and the diffusion plate is adjacent to the auxiliary diffusion unit.   The surface light source device according to claim 1, wherein the auxiliary diffusing unit is located on a side of the diffusing plate opposite to the adjusting plate.   The surface light source device according to claim 9, wherein the diffusion plate is adjacent to the adjustment plate, and the auxiliary diffusion portion is adjacent to the diffusion plate. A spacer for supporting the adjustment plate and the diffusion plate;
The spacer includes a first support surface that supports the diffusion plate, a second support surface that is positioned closer to the light source than the first support surface and supports the adjustment plate, the first support surface, and the first support surface. A step surface that extends between the two support surfaces and faces the adjustment plate from the side and restricts the movement of the adjustment plate to the side,
The surface light source device according to claim 1, further comprising a fixing unit that presses the diffusion plate toward the first support surface of the spacer. A laminate used in a surface light source device,
An adjustment plate for adjusting the in-plane distribution of the transmitted light amount;
A diffusing plate arranged offset from the adjusting plate;
An auxiliary diffusing portion provided on at least one side of the diffusion plate on the side opposite to the adjustment plate and the adjustment plate on the diffusion plate,
A laminate in which at least one of the diffusion plate and the auxiliary diffusion portion is disposed adjacent to the adjustment plate. A surface light source device according to any one of claims 1 to 11,
A display panel illuminated by the surface light source device.