JP6959535B2 - Light emitting device - Google Patents

Description

The present disclosure relates to a light emitting device.

A so-called direct type backlight in which a light source such as an LED is arranged two-dimensionally on the back surface of a liquid crystal panel is known. For example, Patent Documents 1 and 2 below disclose a backlight unit having a plurality of LEDs and an optical sheet.

In the backlight unit of Patent Document 1, a plurality of LEDs are mounted on a substrate arranged in a back chassis, and a plurality of optical sheets are arranged on the light emitting side of the LEDs at intervals from the LEDs. Patent Document 2 discloses a light guide unit in which a plurality of structures each including an LED and a light guide are connected to each other by an adhesive. Each light guide has a recess in the central portion opposite to the exit surface, and the LED as a light source is arranged in the recess of each light guide. Further, the central portion of each light guide body on the side opposite to the exit surface located on the optical sheet side is relatively thicker than the end portion.

Japanese Unexamined Patent Publication No. 2015-032373 Japanese Unexamined Patent Publication No. 2009-15152

It is advantageous if the light emitting device including a plurality of light sources represented by the LED can be made thinner because the device including the light emitting device as a backlight can be made smaller.

The light emitting devices according to the embodiments of the present disclosure are arranged in rows and columns, each having a first surface and a light guide plate having a second surface located on the side opposite to the first surface, and a plurality of light emitting elements. The first optical diffusion structure includes a plurality of optical segments including the light guide plate, and a first light diffusion structure located on the first surface side of the light guide plate and extending along the outer periphery of an array of the plurality of optical segments. It has a portion located outside the array of the plurality of optical segments.

According to the embodiments of the present disclosure, a thinner and smaller light emitting device, for example, a backlight is provided.

FIG. 5 is an exploded perspective view schematically showing an exemplary configuration of a liquid crystal display device having a light emitting device according to an embodiment of the present disclosure. It is a schematic plan view which shows an example of the appearance when the light source unit 320 is seen from the upper surface 110a side of the optical segment 110. FIG. 5 is an enlarged cross-sectional view schematically showing a part of a cross section when the light emitting device 100A is cut perpendicularly to the upper surface 110a of the optical segment 110. It is a schematic plan view which shows an example of the appearance when the optical segment 110 is seen from the upper surface 110a side. FIG. 3 is a schematic cross-sectional view showing an enlarged view of the light emitting element 130 and its periphery in FIG. It is a figure which shows an example of the wiring pattern of the wiring 160. It is a schematic cross-sectional view which shows the example of the cross-sectional shape of the 1st light diffusion structure 191. FIG. 5 is a schematic cross-sectional view showing another example of the cross-sectional shape of the first light diffusion structure 191. FIG. 5 is a schematic cross-sectional view showing still another example of the cross-sectional shape of the first light diffusion structure 191. FIG. 5 is a schematic cross-sectional view showing still another example of the cross-sectional shape of the first light diffusion structure 191. It is a schematic plan view which shows an example of the two-dimensional arrangement of an optical segment 110. It is a schematic plan view which shows another example of the two-dimensional arrangement of an optical segment 110. It is a schematic plan view which shows the structure which has the 1st light diffusion structure 191 in addition to the arrangement of the optical segment 110 shown in FIG. It is a schematic plan view which shows still another example of the shape of the 1st light diffusion structure. It is a schematic plan view which shows still another example of the shape of the 1st light diffusion structure. FIG. 16 is a schematic plan view showing a light emitting device according to another embodiment of the present disclosure. FIG. 17 is a schematic plan view showing a light emitting device according to still another embodiment of the present disclosure. FIG. 18 is a schematic cross-sectional view showing a light emitting device according to still another embodiment of the present disclosure. FIG. 5 is a schematic cross-sectional view showing another example of the shape of the light guide structure arranged between the optical segments 110. It is a schematic plan view which shows another example of the shape of the 1st light diffusion structure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following embodiments are examples, and the light emitting device according to the present disclosure is not limited to the following embodiments. For example, the numerical values, shapes, materials, steps, the order of the steps, and the like shown in the following embodiments are merely examples, and various modifications can be made as long as there is no technical contradiction.

The dimensions, shapes, etc. of the components shown in the drawings may be exaggerated for the sake of clarity, and may not reflect the dimensions, shapes, and magnitude relationships between the components in an actual light emitting device. In addition, some elements may be omitted in order to avoid overly complicated drawings.

In the following description, components having substantially the same function are indicated by common reference numerals, and the description may be omitted. In the following description, terms indicating a specific direction or position (eg, "top", "bottom", "right", "left" and other terms including those terms) may be used. However, these terms use relative orientation or position in the referenced drawings for clarity only. If the relative directions or positional relationships in terms such as "upper" and "lower" in the referenced drawings are the same, they are the same as the referenced drawings in drawings other than the present disclosure, actual products, manufacturing equipment, etc. It does not have to be an arrangement. In the present disclosure, "parallel" includes the case where two straight lines, sides, surfaces, etc. are in the range of about 0 ° to ± 5 ° unless otherwise specified. Further, in the present disclosure, "vertical" or "orthogonal" includes a case where two straight lines, sides, surfaces, etc. are in the range of about 90 ° to ± 5 ° unless otherwise specified.

(Embodiment of light emitting device)
FIG. 1 shows an exemplary configuration of a liquid crystal display device having a light emitting device according to an embodiment of the present disclosure. The liquid crystal display device 300 shown in FIG. 1 generally includes a liquid crystal panel 310 and a light source unit 320 as a backlight unit. As schematically shown in FIG. 1, the liquid crystal display device 300 typically further includes an optical sheet group 330 arranged between the liquid crystal panel 310 and the light source unit 320. In this example, the optical sheet group 330 includes a light diffusing sheet 332, a first lens sheet 334, and a second lens sheet 336, of which the light diffusing sheet 332 is located closest to the light source unit 320. In the illustrated example, the set of the first lens sheet 334 and the second lens sheet 336 is arranged between the light diffusing sheet 332 and the back surface 310b of the liquid crystal panel 310.

The light source unit 320 includes a support substrate 200 such as a glass epoxy substrate and a light emitting device 100A supported on an upper surface 200a which is one main surface of the support substrate 200. The light emitting device 100A includes a two-dimensional array of a plurality of optical segments 110 as a part thereof. As will be described later, each optical segment 110 includes a light guide plate and a plurality of light emitting elements, and provides light toward the back surface 310b of the liquid crystal panel 310. In this example, the light emitting device 100A has a layered light reflecting member 150 on the opposite side of the liquid crystal panel 310.

The upper surface 110a of each optical segment 110 has a rectangular outer shape in top view. In the illustrated example, the optical segments 110 are arranged in rows and columns, so here the overall top view of the arrangement of the optical segments 110 is rectangular.

In the configuration illustrated in FIG. 1, the light emitting device 100A has a frame body 180. FIG. 2 shows an example of the appearance of the light source unit 320 when viewed from the upper surface 110a side of the optical segment 110. As shown in FIG. 2, the frame 180 has a shape that surrounds a two-dimensional array of a plurality of optical segments 110. The shape and dimensions of the central opening of the frame 180 are typically designed to roughly match the rectangular shape formed by the collection of multiple optical segments 110, thus the frame 180 is , Can function as a regulatory structure that regulates the movement of the plurality of optical segments 110 on the top surface 200a. A part of the back chassis accommodating the light source unit 320 may function as a frame 180.

As shown in FIGS. 1 and 2, the light emitting device 100A further has a first light diffusion structure 191 on the upper surface 110a side of the optical segment 110. The first light diffusing structure 191 is translucent and has a shape extending along the outer circumference of a two-dimensional array of a plurality of optical segments 110. It should be noted that the terms "translucency" and "translucency" in the present specification are interpreted to include exhibiting diffusivity with respect to incident light, and are not limited to "transparent".

As shown in FIGS. 1 and 2, here, the first light diffusing structure 191 includes a plurality of triangular columnar structures extending along each side of the rectangular shape defined by the upper surfaces 110a of the plurality of optical segments 110. As a whole, it has a rectangular shape with an opening in the center. As schematically shown in FIG. 2, a part of the first light diffusing structure 191 is located on the upper surface 180a of the frame body 180, and the other part of the first light diffusing structure 191 is a plurality of optical segments 110. Of these, it is located on the upper surface 110a of some of the optical segments 110. That is, the first light diffusion structure 191 includes a portion located outside the two-dimensional array of the plurality of optical segments 110.

According to the embodiment of the present disclosure, the set of the upper surfaces 110a of the plurality of optical segments 110 constitutes a light emitting surface from which light is emitted in the light emitting device. As will be described in detail later, a plurality of light emitting elements are arranged on the light guide plate of the optical segment 110 on the side opposite to the upper surface 110a of each optical segment 110. In other words, in each optical segment 110, the plurality of light emitting elements are basically not arranged apart from the light guide plate. According to the embodiment of the present disclosure, since the light from each light emitting element can be diffused by the light guide plate and then emitted from the upper surface 110a of the optical segment 110, high brightness is locally generated immediately above the light emitting element. It is possible to suppress the occurrence of uneven brightness, and it is possible to provide a light source device having a reduced thickness.

Further, according to the embodiment of the present disclosure, since the set of the upper surfaces 110a of the plurality of optical segments 110 constitutes the light emitting surface, the arrangement of the optical segments 110 can be changed or the number of the optical segments 110 included in the light emitting device can be changed. By changing the screen size, the light emitting device can be easily applied to a plurality of types of liquid crystal panels having different screen sizes. That is, it is possible to flexibly respond to changes in the screen size without having to redo the optical calculation for the light guide plate or the like in the optical segment 110 or remanufacture the mold for forming the light guide plate. be. Therefore, the change in screen size does not cause an increase in manufacturing cost and lead time.

In particular, according to the embodiment of the present disclosure, since the light emitting device has the first light diffusion structure on the upper surface 110a side of the optical segment 110, the light distribution at the outer edge of the two-dimensional array of the plurality of optical segments 110 is expanded to the outside. Can be done. Therefore, the applicability of the light emitting device can be further expanded to a liquid crystal panel having a screen size that cannot be dealt with only by changing the arrangement or number of the optical segments 110.

Hereinafter, each component of the light emitting device 100A will be described in more detail.

[Optical segment 110]
FIG. 3 schematically shows an enlarged part of a cross section when the light emitting device 100A is cut perpendicularly to the upper surface 110a of the optical segment 110, and FIG. 4 shows the optical segment 110 when viewed from the upper surface 110a side. An example of the appearance is shown.

Each optical segment 110 includes a light guide plate 120 having an upper surface 120a (first surface) and a lower surface 120b (second surface) opposite to the upper surface 120a, and a plurality of light emitting elements 130 located on the lower surface 120b side of the light guide plate 120. And include. The upper surface 120a of the light guide plate 120 constitutes the upper surface 110a of the optical segment 110 shown in FIGS. 1 and 2. In the configuration illustrated in FIG. 3, each optical segment 110 has a light reflecting member 150 and wiring 160 on the lower surface 120b side of the light guide plate 120.

[Light guide plate 120]
The light guide plate 120 is formed of a thermoplastic resin such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate or polyester, a thermosetting resin such as epoxy or silicone, or glass and has translucency. The light guide plate 120 has a function of diffusing the light from the light emitting element 130 and emitting it from the upper surface 120a. In addition to injection molding, transfer molding, thermal transfer, and the like can also be applied to the formation of the light guide plate 120. Among the above-mentioned materials, the thermoplastic resin material is advantageous because the light guide plate 120 can be efficiently manufactured by injection molding. In particular, polycarbonate can obtain high transparency while being inexpensive. The light guide plate 120 may be provided with a light diffusing function by, for example, a material having a refractive index different from that of the base material being dispersed in the base material.

In the configurations illustrated in FIGS. 3 and 4, the light guide plate 120 of each optical segment 110 has a plurality of light diffusing portions 122 on the upper surface 120a. As shown in FIG. 4, here, the light diffusing unit 122 has a two-dimensional array of 4 rows and 4 columns on the upper surface 120a, and each of the plurality of light emitting elements 130 included in each optical segment 110 has a plurality of lights. It is located directly below one of the diffusers 122.

The light diffusing unit 122 reflects the light emitted from the light emitting element 130 and incident on the light guide plate 120 at the interface with the air layer, for example, and diffuses it in the plane of the light guide plate 120. By providing the light diffusing portion 122 on the upper surface 120a of the light guide plate 120, the brightness in the region other than directly above the light emitting element 130 in the upper surface 120a is improved, and the brightness unevenness on the upper surface 110a of the optical segment 110 is more effectively suppressed. Can be done. That is, the light diffusing unit 122 contributes to thinning the light guide plate 120. The thickness of the light guide plate 120 is typically about 0.1 mm or more and 5 mm or less, and in particular, according to the embodiment of the present disclosure, it can be in the range of about 0.5 mm or more and 3 mm or less. ..

In this example, the light diffusing portion 122 is provided on the upper surface 120a in the form of a conical concave portion, and reflects light at the interface between the inclined surface 122b constituting the light diffusing portion 122 and the air layer. Of course, the shape of the light diffusing portion 122 is not limited to the conical shape. The shape of the light diffusing portion 122 may be a polygonal pyramid shape such as a quadrangular pyramid or a hexagonal pyramid. Further, the shape of the inclined surface 122b in the cross-sectional view is not limited to a straight line, and may be a curved shape, or a shape including bending and a step. The inside of the light diffusing portion 122 may be filled with a material having a refractive index different from that of the material of the light guide plate 120 main body. Alternatively, a light-reflecting member such as a reflective film made of metal or a white resin layer may be arranged on the inclined surface 122b.

The light guide plate 120 may be a single layer or may have a laminated structure including a plurality of translucent layers. When a plurality of translucent layers are laminated, a layer having a different refractive index from the others, such as an air layer, may be interposed between arbitrary layers. By interposing, for example, an air layer between arbitrary layers of the laminated structure, it becomes easier to diffuse the light from the light emitting element 130, and the uneven brightness can be further reduced.

The length of one side of the rectangular shape of the upper surface 120a of the light guide plate 120 may be, for example, in the range of 1 cm or more and 200 cm or less. In a typical embodiment of the present disclosure, one rectangular side of the upper surface 120a of the light guide plate 120 has a length of 20 mm or more and 25 mm or less.

In this example, the light guide plate 120 further has a plurality of recesses 124 on the lower surface 120b side. As shown in FIG. 3, each of the plurality of recesses 124 is located on the opposite side of one of the plurality of light diffusing portions 122, and here, the wavelength conversion member 140 is arranged in these recesses 124. .. The wavelength conversion member 140 may have a thickness comparable to the depth of the recess 124.

The recess 124 has, for example, a quadrangular prism shape. The length of the diagonal line of the quadrangular prism shape can be, for example, 0.05 mm or more and 10 mm or less, preferably 0.1 mm or more and 1 mm or less. The length of the diagonal line of the quadrangular prism shape may be substantially the same as the diameter of the conical bottom surface of the concave portion provided on the upper surface 120a side. Of course, the shape and size of the recess 124 are not limited to this example, and may be appropriately determined. Typical examples of the shape of the recess 124 in a plan view are a rectangular shape, a polygonal shape, or a circular shape. When a plurality of recesses 124 are evenly arranged on the lower surface 120b of the light guide plate 120, it is beneficial that the recesses 124 have a circular shape in a plan view from the viewpoint of evenly spreading light from the light emitting element 130. .. When the recess 124 has, for example, a cylindrical shape, the diameter of the bottom surface of the cylindrical shape may be substantially the same as the diameter of the conical bottom surface of the recess provided on the upper surface 120a side.

A structure having recesses on the upper surface 120a side and the lower surface 120b side can be obtained, for example, by providing a convex portion protruding toward the inside of the cavity at a predetermined position in the mold when injection molding is applied. can. According to such a method, the concave portion on the upper surface 120a side and the concave portion on the lower surface 120b side can be formed collectively, so that the concave portion on the upper surface 120a side and the concave portion on the lower surface 120b side are displaced from each other. Can be avoided. When the light diffusing portion 122 is provided on the upper surface 120a in the form of a recess, the depth of the recess 124 located on the lower surface 120b can be appropriately set as long as it does not reach the light diffusing portion 122. The depth of the recess 124 is, for example, in the range of 0.05 mm or more and 4 mm or less, preferably 0.1 mm or more and 1 mm or less.

In the configuration illustrated in FIG. 3, the region of the upper surface 120a of the light guide plate 120 other than the light diffusing portion 122 and the region of the lower surface 120b other than the recess 124 are flat surfaces. However, the shapes of the upper surface 120a and the lower surface 120b of the light guide plate 120 are not limited to this example, and for example, a structure for diffusing or reflecting light may be formed in a region other than the light diffusing portion 122 and the recess 124. .. For example, a fine uneven pattern may be provided in the region excluding the light diffusing portion 122 and the recess 124, or the region excluding the light diffusing portion 122 and the recess 124 may be made a rough surface.

[Light emitting element 130]
As shown in FIG. 4, in this example, each optical segment 110 includes 16 light emitting elements 130 arranged in 4 rows and 4 columns. As shown in FIG. 3, here, each of the plurality of light emitting elements 130 is joined to the corresponding one of the wavelength conversion members 140 arranged in the recesses 124 provided on the lower surface 120b of the light guide plate 120. Will be done.

A typical example of the light emitting element 130 is an LED. In the configuration illustrated in FIG. 3, the light emitting element 130 has an element main body 132 and an electrode 134 located on the opposite side of the upper surface 130a of the light emitting element 130. The element body 132 includes, for example, a support substrate such as sapphire or gallium nitride, and a semiconductor laminated structure on the support substrate. The semiconductor laminated structure includes an active layer, an n-type semiconductor layer and a p-type semiconductor layer sandwiching the active layer. The semiconductor laminated structure may include a light emitting capable nitride semiconductor of ultraviolet to visible range _{(In x Al y Ga 1-} xy N, 0 ≦ x, 0 ≦ y, x + y ≦ 1). Here, the upper surface 130a of the light emitting element 130 coincides with the upper surface of the element main body 132. The electrode 134 is a set of a positive electrode and a negative electrode, and has a function of supplying a predetermined current to the semiconductor laminated structure.

As schematically shown in FIG. 4, the shape of the light emitting element 130 in a top view is typically rectangular. The length of one side of the rectangular shape of the light emitting element 130 is, for example, 1000 μm or less. The rectangular vertical and horizontal dimensions of the light emitting element 130 may be 500 μm or less. Light emitting elements having vertical and horizontal dimensions of 500 μm or less are easy to procure at low cost. Alternatively, the rectangular vertical and horizontal dimensions of the light emitting element 130 may be 200 μm or less. When the length of one side of the rectangular shape of the light emitting element 130 is small, it is advantageous for high-definition image expression, local dimming operation, etc. in application to the backlight unit of the liquid crystal display device. In particular, in a light emitting element having both vertical and horizontal dimensions of 250 μm or less, the area of the upper surface is small, so that the amount of light emitted from the side surface of the light emitting element is relatively large. That is, it is easy to obtain a butt-wing type light distribution characteristic defined by a light emission intensity distribution in which the light emission intensity is high at an angle where the absolute value of the light distribution angle is larger than 0 °, where the optical axis is 0 °.

The shape of the light emitting element 130 in a top view may be rectangular. When the light emitting element 130 has a rectangular shape when viewed from above, the positive electrode and the negative electrode can be formed on the opposite side of the upper surface 130a of the light emitting element 130 so as to be separated from each other, and the wiring 160 described later can be easily formed.

As shown in FIG. 4, the plurality of light emitting elements 130 are arranged two-dimensionally along, for example, two orthogonal directions (for example, the x direction and the y direction). The arrangement pitch of the light emitting element 130 can be, for example, 0.05 mm or more and 20 mm or less, and may be in the range of 1 mm or more and 10 mm or less. Here, the arrangement pitch of the light emitting element 130 is the distance between the optical axes of the light emitting element 130. The light emitting elements 130 may be arranged at equal intervals or may be arranged at irregular intervals. The arrangement pitch of the light emitting element 130 may be the same or different between two different directions. The number and arrangement of the light emitting elements 130 are not limited to the example shown in FIG. 4, and any number and arrangement may be adopted.

Each of the plurality of light emitting elements 130 may be an element that emits blue light or an element that emits white light. Further, the plurality of light emitting elements 130 may include elements that emit light of different colors from each other. For example, the plurality of light emitting elements 130 may include an element that emits red light, an element that emits blue light, and an element that emits green light. In the following, as the light emitting element 130, an LED that emits blue light will be illustrated.

[Wavelength conversion member 140]
As described above, in this example, the optical segment 110 includes a plurality of wavelength conversion members 140 corresponding to the plurality of light emitting elements 130. The wavelength conversion member 140 is typically a member in which phosphor particles are dispersed in a resin. The wavelength conversion member 140 absorbs at least a part of the light emitted from the light emitting element 130 and emits light having a wavelength different from the wavelength of the light emitted from the light emitting element 130. For example, the wavelength conversion member 140 wavelength-converts a part of the blue light from the light emitting element 130 to emit yellow light. According to such a configuration, white light is obtained by mixing the blue light that has passed through the wavelength conversion member 140 and the yellow light emitted from the wavelength conversion member 140. As illustrated in FIG. 3, according to the configuration in which the light emitting element 130 is arranged in each of the wavelength conversion members 140, the light from the light emitting element 130 can be incident on the wavelength conversion member 140 and then diffused in the light guide plate 120. Therefore, it is advantageous to suppress the occurrence of color unevenness and make the light uniform.

The wavelength conversion member 140 is formed by arranging a resin composition in which particles such as a phosphor, which is a wavelength conversion substance, are dispersed in a recess 124 of a light guide plate 120 using a squeegee or the like, and then curing the resin composition. can. Alternatively, by adhering a plate-shaped resin piece in which particles such as a phosphor are dispersed in the recess 124, the plurality of wavelength conversion members 140 are formed so that the plurality of wavelength conversion members 140 appear in an island shape on the lower surface 120b side. It may be arranged in the recess 124. The resin piece can be obtained by injection molding, compression molding, transfer molding or the like, and can also be obtained by cutting, punching or the like after molding a resin composition in which particles such as a phosphor are dispersed into a sheet shape. .. When a recess 124 is provided on the lower surface 120b of the light guide plate 120 and a wavelength conversion member 140 is formed in each recess 124 to form a wavelength conversion member in the form of a single layer common to a plurality of light emitting elements 130. Compared with, the material of the wavelength conversion member can be saved.

A plurality of wavelength conversion members may be formed in an island shape on the lower surface 120b without providing the recess 124 on the lower surface 120b of the light guide plate 120. In this case, the wavelength conversion member can be formed by a method such as potting, printing, or spraying. However, from the viewpoint of making the light emitting device 100A thinner, it is advantageous to arrange the wavelength conversion member 140 in the recess 124 as shown in FIG.

Resins that disperse particles such as phosphors include silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, urea resin, phenol resin, acrylic resin, urethane resin or fluororesin, or two or more of these resins. A resin containing the above can be used. The base material of the wavelength conversion member 140 may be glass. From the viewpoint of efficiently introducing light into the wavelength conversion member 140, it is beneficial that the base material of the wavelength conversion member 140 has a higher refractive index than the material of the light guide plate 120. The wavelength conversion member 140 may be provided with a function of light diffusion by dispersing a material having a refractive index different from that of the base material in the material of the wavelength conversion member 140. For example, particles such as titanium dioxide and silicon oxide may be dispersed in the base material of the wavelength conversion member 140.

A known material can be applied to the phosphor. Examples of phosphors include fluoride-based phosphors such as YAG-based phosphors and KSF-based phosphors, nitride-based phosphors such as CASN, and β-sialone phosphors. The YAG-based phosphor is an example of a wavelength-converting substance that converts blue light into yellow light, and the KSF-based phosphor and CASN are examples of wavelength-converting substances that convert blue light into red light. Is an example of a wavelength converting substance that converts blue light into green light. The phosphor may be a quantum dot phosphor. It is not essential that the phosphors contained in the wavelength conversion member 140 are common in the same optical segment 110. For example, an optical segment 110 having a single optical segment 110 is a wavelength converter that converts incident blue light into yellow light, a wavelength converter that converts incident blue light into green light, and a wavelength converter that converts incident blue light into red light. It may be mixed inside.

[Light guide member 170]
FIG. 5 shows an enlarged view of one of the light emitting elements 130 included in the optical segment 110 and its periphery. In the illustrated example, the light emitting element 130 is joined to the wavelength conversion member 140 via the light guide member 170. As shown in FIG. 5, a part of the light guide member 170 covers at least a part of the side surface 130c of the light emitting element 130. The light guide member 170 typically has a portion located between the upper surface 130a of the light emitting element 130 and the lower surface 140b of the wavelength conversion member 140 on the light emitting element 130 side.

The light guide member 170 has a translucent structure and has a transmittance of 60% or more with respect to light having an emission peak wavelength of the light emitting element 130. From the viewpoint of effectively using light, it is beneficial that the transmittance of the light guide member 170 at the emission peak wavelength of the light emitting element 130 is 70% or more, and it is more beneficial if it is 80% or more.

In the present embodiment, one light guide member 170 is arranged on each wavelength conversion member 140 corresponding to the plurality of wavelength conversion members 140. As a result, the light emitting element 130 can be joined to the corresponding one of the wavelength conversion members 140 by one of the plurality of light guide members 170. By providing the light guide member 170 corresponding to each light emitting element 130, a part of the light emitted from the side surface 130c of the light emitting element 130 can be incidented on the light guide member 170. The light incident on the light guide member 170 is reflected toward the upper side of the light emitting element 130 at the position of the interface between the light reflecting member 150 and the light guide member 170, which will be described later, and is incident on the wavelength conversion member 140. That is, by providing the light guide member 170, the light extracted from the upper surface 120a of the light guide plate 120 via the wavelength conversion member 140 and the light guide plate 120 increases, and as a result, the light extraction efficiency is improved.

It is beneficial if the light guide member 170 covers more areas of the side surface 130c of the light emitting element 130, as more light can be directed above the light emitting element 130. The light guide member 170 may cover the entire light emitting element 130 from the lower end to the upper end of the element main body 132. The outer surface of the light guide member 170 in cross-sectional view, that is, the shape of the interface between the light reflecting member 150 and the light guide member 170 is not limited to the linear shape as shown in FIG. The shape of the outer surface of the light guide member 170 in a cross-sectional view may be a polygonal line, a curved line that is convex in the direction approaching the light emitting element 130, a curved shape that is convex in the direction away from the light emitting element 130, or the like.

Each of the plurality of light guide members 170 is provided by applying the material of the light guide member 170 on the lower surface 140b of the wavelength conversion member 140 by a dispenser or the like, and arranging the light emitting element 130 on the applied material. Can be formed by curing. As the material of the light guide member 170, a resin composition containing a transparent resin material as a base material can be used. A typical example of the base material of the light guide member 170 is a thermosetting resin such as an epoxy resin or a silicone resin. As the base material of the light guide member 170, a silicone resin, a silicone-modified resin, an epoxy resin, a phenol resin, a polycarbonate resin, an acrylic resin, a polymethylpentene resin or a polynorbornene resin, or a material containing two or more of these is used. May be good. For example, a material having a refractive index different from that of the base material may be dispersed in the material of the light guide member 170.

By adjusting the viscosity and amount of the material of the light guide member 170, the material of the light guide member 170 exceeds the outer edge of the wavelength conversion member 140 in top view in the step of applying the wavelength conversion member 140 onto the lower surface 140b. It is beneficial to prevent it from spreading. If the outer edge of the light guide member has a shape that exceeds the outer edge of the wavelength conversion member 140 in top view, light that directly enters the light guide plate 120 from the light guide member without passing through the wavelength conversion member 140 may be generated. .. Such light can cause uneven brightness and uneven color on the light emitting surface. By preventing the size of the light guide member 170 from exceeding the size of the wavelength conversion member 140 in the top view, the generation of light directly incident on the light guide plate 120 without passing through the wavelength conversion member 140 is avoided and the brightness is increased. The occurrence of unevenness and / or color unevenness can be suppressed.

Further, here, on the lower surface 120b side of the light guide plate 120, recesses 124 are provided on opposite sides of the light diffusing portions 122 located on the upper surface 120a of the light guide plate 120, and the wavelength conversion member 140 is arranged in the recess 124. There is. That is, in the present embodiment, each of the light emitting elements 130 is fixed by the light guide member 170 at a position directly below one of the plurality of light diffusing portions 122 on the lower surface 120b side of the light guide plate 120.

According to the configuration in which the light emitting element 130 is arranged on each of the wavelength conversion members 140 as illustrated in FIGS. 3 and 5, the light guide plate 120 is based on the position of the wavelength conversion member 140 directly under the light diffusion unit 122. The light emitting element 130 may be arranged on the lower surface 120b side of the above. In other words, for example, the wavelength conversion member 140 can be used for positioning the light emitting element 130 to more reliably fix the light emitting element 130 at a desired position on the lower surface 120b side of the light guide plate 120. In particular, since the recess 124 is provided at a position directly below the light diffusing portion 122, the optical axis N of the light emitting element 130 is approximately aligned with the axis of the light diffusing portion 122 that passes through the apex of the conical shape and is perpendicular to the bottom surface. The light emitting elements 130 may be arranged to match. By arranging the plurality of light emitting elements 130 with respect to the light guide plate 120 so that the center of the light diffusing portion 122 and the center of the light emitting element 130 substantially coincide with each other in the top view, for example, the substrate on which the plurality of light emitting elements are arranged is arranged. Compared with the conventional configuration in which the diffuser plate is arranged above, the positional deviation between the light emitting element 130 and the light guide plate 120 can be suppressed. Further, the light diffusing unit 122 makes it possible to more uniformly diffuse the light from the light emitting element 130 into the plane of the light guide plate 120.

[Light Reflecting Member 150]
The light reflecting member 150 is formed of a light reflecting material and has a layered structure located on the lower surface 120b side of the light guide plate 120. As used herein, the term "light reflectivity" means that the reflectance of the light emitting element 130 at the emission peak wavelength is 60% or more. It is more beneficial when the reflectance of the light reflecting member 150 at the emission peak wavelength of the light emitting element 130 is 70% or more, and even more beneficial when it is 80% or more. It is beneficial if the light reflecting member 150 has a white color.

As schematically shown in FIG. 5, the light reflecting member 150 covers the outer surface of the light guide member 170 and the portion of the side surface 130c of the light emitting element 130 that is not covered by the light guide member 170. Further, the light reflecting member 150 also covers a region on the lower surface of the element main body 132 of the light emitting element 130, excluding the region where the electrodes 134 are arranged. The lower surface of the electrode 134 is exposed from the lower surface 150b of the light reflecting member 150. By covering the lower surface of the element main body 132 of the light emitting element 130 with the light reflecting member 150 except for the region where the electrodes 134 are arranged, the light leakage to the lower surface 150b side of the light reflecting member 150 is suppressed and the light is emitted. The efficiency of taking out the light can be improved. Further, by forming the light reflecting member 150 in a layered manner on the lower surface 120b side of the light guide plate 120, effects such as prevention of the light emitting element 130 from falling off from the wavelength conversion member 140 and reinforcement of the light guide plate 120 can be expected.

As the material of the light reflecting member 150, for example, a resin material in which a light reflecting filler is dispersed can be used. As a base material of the resin material for forming the light reflecting member 150, a silicone resin, a phenol resin, an epoxy resin, a BT resin, a polyphthalamide (PPA) or the like can be used. As the light-reflecting filler, metal particles or particles of an inorganic material or an organic material having a higher refractive index than the base material in which the light-reflecting filler is dispersed can be used. Examples of light-reflecting fillers include titanium dioxide, silicon oxide, zirconium dioxide, potassium titanate, aluminum oxide, aluminum nitride, boron nitride, mulite, niobium oxide, barium sulfate particles, or yttrium oxide and gadolinium oxide. Particles of various rare earth oxides and the like.

For example, the material of the light reflecting member 150 is applied to the lower surface 120b of the light guide plate 120 so that the light guide member 170 and the light emitting element 130 are embedded, and then the applied material is cured. After that, the light reflecting member 150 can be formed by exposing the lower surface of the electrode 134 from the surface of the light reflecting resin layer obtained by curing the material of the light reflecting member 150 by grinding or the like. Various methods such as transfer molding, compression molding, spray coating, printing, and potting can be applied to the formation of the light-reflecting resin layer covering the light guide member 170 and the light emitting element 130. When a plurality of wavelength conversion members are formed in an island shape on the lower surface 120b without providing the recess 124 on the lower surface 120b side of the light guide plate 120, the light-reflecting resin also covers these wavelength conversion members. A layer may be formed and the electrode 134 may be exposed from the resin layer.

[Wiring 160]
The wiring 160 is provided on the lower surface 150b of the light reflecting member 150 and is electrically connected to the electrode 134 of each light emitting element 130. The wiring 160 has a function of supplying a predetermined current to each light emitting element 130. By providing the wiring 160 in each optical segment 110, for example, a plurality of light emitting elements 130 in each optical segment 110 can be electrically connected to each other by the wiring 160. That is, the light emitting element 130 can be driven, for example, in units of the optical segment 110, and the light emitting device 100A can be operated by local dimming. Further, by providing the wiring 160 on the lower surface 150b of the light reflecting member 150, the electrical connection between the light emitting element 130 in the optical segment 110 and the support substrate 200 is made by connecting the wiring 160 to the wiring on the support substrate 200. Can be formed. That is, the light emitting device 100A can be more easily mounted on the support substrate 200 as compared with the configuration in which the positive electrode and the negative electrode are connected to the wiring board for each light emitting element.

FIG. 6 shows an example of the wiring pattern of the wiring 160. For simplicity, FIG. 6 schematically shows the electrical connections of four of the plurality of optical segments 110 included in the light emitting device 100A.

In the configuration illustrated in FIG. 6, the light emitting device 100A has a wiring 160 for each optical segment 110, and the wiring 160 of each optical segment 110 electrically connects a plurality of light emitting elements 130 included in the optical segment 110 to each other. doing. Here, the wiring 160 of each optical segment 110 connects four light emitting elements 130 in series, and connects four groups of light emitting elements 130 connected in series in parallel.

As shown in FIG. 6, each of these wires 160 may be connected to a driver 210 that drives the light emitting element 130. The driver 210 may be arranged on the support board 200 and electrically connected to the wiring 160, or may be arranged on a board separate from the support board 200 and electrically connected to the wiring 160. Under such a circuit configuration, a local dimming operation in units of an optical segment 110 including 16 light emitting elements 130 is possible. Of course, the connection of the plurality of light emitting elements 130 by the wiring 160 is not limited to the example shown in FIG. 6, and each light emitting element 130 in the optical segment 110 may be connected so as to be driven independently. Alternatively, the light emitting element 130 included in the optical segment 110 may be divided into a plurality of groups, and the plurality of light emitting elements 130 may be electrically connected so that the light emitting element 130 can be driven in the unit of the group including the plurality of light emitting elements 130. good.

The wiring 160 of each optical segment 110 can be formed, for example, by forming a metal film on the lower surface 150b of the light reflecting member 150 by sputtering or the like after forming the light reflecting member 150, and patterning the metal film by, for example, laser ablation. be. The metal film may be formed on the lower surface 150b of the light reflecting member 150 in the form of a laminated film. For example, a metal film may be formed on the lower surface 150b of the light reflecting member 150 by sequentially depositing Cu, Ni, and Au.

[First light diffusion structure 191]
As shown in FIG. 1, the first light diffusion structure 191 is located on the upper surface side of the light emitting device 100A, that is, on the upper surface 120a of the light guide plate 120, and the two-dimensional arrangement of the optical segments 110 has a rectangular outer shape. Correspondingly, it has a frame shape. The first light diffusion structure 191 may be fixed to the frame body 180 by being adhered to the upper surface 180a of the frame body 180 described above. The first light diffusion structure 191 expands the light distribution of light from the upper surface 110a of the optical segment 110 located on the outermost side in the two-dimensional arrangement of the optical segment 110 to an outer region.

The first light diffusion structure 191 has translucency and can be formed by injection molding, transfer molding or the like. A typical example of the material of the first light diffusion structure 191 is a thermoplastic resin such as acrylic or polycarbonate. As the material of the first light diffusion structure 191, a material common to the material of the light guide plate 120 may be used. It is beneficial that the material of the first light diffusing structure 191 has a refractive index equal to or higher than that of the light guide plate 120. The first light diffusing structure 191 may be provided with a light diffusing function by dispersing a material having a refractive index different from that of the base material in the base material.

In the above example, the first light diffusion structure 191 has a structure in which a triangular columnar light diffusion structure is combined along four rectangular sides formed by a two-dimensional arrangement of optical segments 110. However, the cross-sectional shape when the first light diffusion structure 191 is cut perpendicularly to the upper surface 110a of the optical segment 110 and the rectangular side of the two-dimensional array of the optical segment 110 is not limited to a triangle. 7 to 10 show an example of the cross-sectional shape of the first light diffusion structure 191.

The cross-sectional shape of the first light diffusion structure 191 may be trapezoidal as shown in FIG. 7, or semicircular or semi-elliptical as shown in FIG. As can be seen from FIG. 8, the outer shape of the first light diffusing structure 191 in the cross section perpendicular to the extending direction of the first light diffusing structure 191 may be curved. As shown in FIG. 9, the first light diffusing structure 191 may include a plurality of convex portions, and as shown in FIG. 10, the surface of the first light diffusing structure 191 has fine irregularities. You may. As described above, any shape can be adopted as the cross-sectional shape of the first light diffusion structure 191. The width of the first light diffusion structure 191 may also be arbitrarily determined according to the specifications.

As described above, in the embodiment of the present disclosure, a plurality of light emitting elements 130 are joined to the lower surface 120b side of the light guide plate 120 in each optical segment 110. Therefore, it is possible to provide a light emitting device having a thickness reduced as compared with a conventional configuration in which a light guide plate or the like is arranged at intervals from a plurality of LEDs. In particular, in a direct type liquid crystal display device, since the distance between the liquid crystal panel and the backlight unit is small, the brightness unevenness on the light emitting surface of the backlight unit tends to appear as the brightness unevenness of the liquid crystal display device. In the embodiment of the present disclosure, the distance from the upper surface 130a of the plurality of light emitting elements 130 to the upper surface 120a of the light guide plate 120 is reduced as compared with the conventional case, but the light from each light emitting element 130 is diffused by the light guide plate 120. Then, since the light is emitted from the upper surface 110a of the optical segment 110, uneven brightness is less likely to occur on the light emitting surface. The light diffusing unit 122 also contributes to suppressing uneven brightness.

According to the embodiment of the present disclosure, for example, the thickness of the structure including the light reflecting member 150, in other words, the distance from the upper surface 200a of the support substrate 200 to the upper surface 110a of the optical segment is 5 mm or less, 3 mm or less, or 1 mm. It can be reduced to: The distance from the upper surface 200a of the support substrate 200 to the upper surface 110a of the optical segment may be about 0.7 mm or more and 1.1 mm or less.

Further, since the light emitting element 130 is fixed in advance not on the wiring board side but on the optical segment 110 side, it is possible to suppress the occurrence of misalignment between the light emitting element 130 and the light diffusing portion 122 of the light guide plate 120. Further, since the light diffused by the wavelength conversion member 140 and / or the light guide plate 120 is emitted from the upper surface 110a of the optical segment 110, more uniform light can be realized.

In the examples shown in FIGS. 7 to 10, the wiring 160 of the optical segment 110 is electrically connected to the wiring 212 provided on the upper surface 200a of the support substrate 200. The wiring 212 is, for example, a copper wiring having a thickness of about 5 to 50 μm. For example, a conductive material is applied on the wiring 212, the optical segment 110 is placed on the support substrate 200, and then the conductive material is melted by heating and pressurizing, and the wiring 160 of the optical segment 110 and the support substrate pass through the conductive material. The 200 wires 212 can be electrically connected to each other. The method of fixing the optical segment 110 to the support substrate 200 is not limited to a specific method, and for example, the optical segment 110 may be fixed to the support substrate 200 by a sheet having an adhesive layer. The support substrate 200 may be a rigid substrate or a flexible substrate.

[Change of screen size by recombination of optical segment 110]
Further, according to the embodiment of the present disclosure, it is possible to correspond to various screen sizes by changing the arrangement of the optical segments 110. This point will be described below.

FIG. 11 shows an example of a two-dimensional array of optical segments 110. FIG. 11 schematically shows the appearance of the two-dimensional arrangement of the optical segments 110 as viewed from the upper surface 110a side of the optical segments 110, and in order to avoid overly complicated drawings, the frame 180 and the support substrate are shown. Illustrations such as 200 are omitted.

FIG. 11 shows an example in which a total of 128 optical segments 110 are arranged in 8 rows and 16 columns. In the illustrated example, the vertical length L and the horizontal length W of the optical segment 110 in top view are, for example, approximately 24.3 mm and 21.5 mm, respectively. Therefore, the arrangement of optical segments 110 shown in FIG. 11 fits into a 15.6 inch screen size with an aspect ratio of 16: 9. For example, the arrangement of optical segments 110 shown in FIG. 11 can be suitably used for the backlight unit of a laptop personal computer having a screen size of 15.6 inches.

FIG. 12 shows a configuration in which the set of optical segments 110 shown in FIG. 11 is further arranged in 2 rows and 2 columns. In this case, a total of 512 optical segments 110 can form a surface light source with an aspect ratio of 16: 9 and suitable for a screen size of 31.2 inches. For example, the arrangement of the optical segments 110 shown in FIG. 12 can be used for a backlight unit of a liquid crystal television or the like.

In this way, according to the method of constructing the light emitting surface by combining a plurality of optical segments 110, the design of the optical system is redesigned according to the screen size, and the mold for forming the diffuser plate is remanufactured. It is possible to flexibly support liquid crystal panels of various screen sizes without having to do so. That is, it is possible to provide a backlight unit suitable for the screen size at low cost and in a short delivery time. Further, even if there is a light emitting element that does not light due to disconnection or the like, there is an advantage that the optical segment including the defective light emitting element can be replaced.

However, depending on the specifications of the display device, a light emitting area slightly larger than the rectangular shape obtained by combining the plurality of optical segments 110 may be required. For example, it can be assumed that a surface light source suitable for a screen size of 31.5 inches with an aspect ratio of 16: 9 is required. The alternate long and short dash line SS in FIG. 12 schematically shows the position of the outer edge of the screen size of 31.5 inches.

FIG. 13 shows a configuration having a first light diffusion structure 191 in addition to the arrangement of the optical segments 110 shown in FIG. According to the configuration illustrated in FIG. 13, the first light diffusing structure 191 allows the light from the upper surface 110a of the optical segment 110 to be further expanded toward the outside of the two-dimensional array of the optical segment 110. That is, the brightness in the outer region of the two-dimensional array of optical segments 110 can be compensated for without increasing the number of optical segments 110, and the configuration illustrated in FIG. 13 has a screen size of 31.5 inches. It can be applied to the backlight unit of the liquid crystal display device.

Further, for example, when the optical segment 110 has a length of about 23.0 mm in the vertical direction and a length of about 20.9 mm in the horizontal direction in the top view, such an optical segment 110 is arranged in 3 rows 6 By arranging in rows, a light emitting area with an aspect ratio of 16: 9, which is slightly smaller than the screen size of 5.8 inches, can be obtained. By combining the first light diffusing structure 191 with such an arrangement of the optical segments 110, it is possible to realize a backlight unit having an aspect ratio of 16: 9 and suitable for a screen size of 5.8 inches.

The shape of the first light diffusion structure 191 is not limited to the frame shape as shown in FIGS. 1 and 2. For example, in the configuration illustrated in FIG. 14, the light emitting device 100G includes a total of 18 optical segments 110 and a first light diffusing structure 191A. In this example, the optical segments 110 have an array of 3 rows and 6 columns, and the first light diffusion structure 191A is one of the rectangular short sides defined by the outer edges of the array of these optical segments 110. It extends linearly along it. Further, the light emitting device 100H shown in FIG. 15 includes a plurality of optical segments 110 arranged in 3 rows and 6 columns, and a first light diffusion structure 191B. In the example shown in FIG. 15, the first light diffusing structure 191B is rectangular with a first portion 191Ba extending linearly along one of the rectangular short sides defined by the outer edge of the array of optical segments 110. It has a second portion 191Bb extending linearly along the other one of the short sides of the shape.

According to such a configuration, the light distribution of the light from the upper surface 110a of the optical segment 110 is expanded to the outer region with respect to the direction parallel to the long side of the rectangular shape defined by the outer edge of the array of the optical segments 110. be able to. With the configuration illustrated in FIG. 14 or 15, for example, a backlight unit having an aspect ratio of 18.5: 9 and suitable for a 6.2-inch screen size can be realized. Further, for example, by arranging a total of 84 optical segments 110 in 7 rows and 12 columns and applying the first light diffusion structure 191 described above, a screen size of 12.1 inches having an aspect ratio of 16:10 can be obtained. It is also possible to realize a suitable backlight unit. As described above, according to the embodiment of the present disclosure, the light emitting device can be applied to a liquid crystal panel or the like having a screen size that cannot be dealt with only by changing the arrangement or number of the optical segments 110.

The first light diffusion structure 191A and the first portion 191Ba and the second portion 191Bb of the first light diffusion structure 191B have, for example, the shape of a triangular prism. However, with respect to each of the first portion 191Ba and the second portion 191Bb of the first light diffusing structure 191A and the first light diffusing structure 191B, the outer shape in the cross section perpendicular to the extending direction is arbitrary.

[Second light diffusion structure 192]
The light emitting device 100B shown in FIG. 16 further has a second light diffusing structure 192 located on the upper surface 110a side of the optical segment 110 as compared with the light emitting device 100A described with reference to FIG. 1 and the like.

The second light diffusing structure 192 is a translucent structure similar to the first light diffusing structure 191 and is formed by, for example, a transfer mold or the like. As the material of the second light diffusion structure 192, the same material as the material of the first light diffusion structure 191 can be used.

In the configuration illustrated in FIG. 16, the second light diffusion structure 192 is formed along the boundary formed between the optical segments 110 so as to straddle the boundary of the optical segments 110 adjacent to each other on the upper surface 120a side of the light guide plate 120. It extends. In other words, in this example, the second light diffusing structure 192 has a grid-like shape when viewed from above. The second light diffusing structure 192 may be formed integrally with the first light diffusing structure 191 or may be formed as a member separate from the first light diffusing structure 191 and arranged on the upper surface 110a side of the optical segment 110. You may.

In the configuration in which the plurality of optical segments 110 are combined, the brightness immediately above the boundary of the optical segment 110 may be slightly reduced as compared with the region on the optical segment 110. As illustrated in FIG. 16, by arranging the second light diffusion structure 192 on the boundary formed between the optical segments 110, the brightness immediately above the boundary can be improved and the boundary of the optical segment 110 can be made less noticeable. .. That is, the second light diffusion structure 192 contributes to the realization of more uniform light.

In the example shown in FIG. 16, the second light diffusion structure 192 is formed on the upper surface 110a side of the optical segment 110 in the form of a triangular columnar structure similar to the first light diffusion structure 191. However, the shape of the second light diffusion structure 192 is not limited to this example. As the shape of the second light diffusing structure 192, any shape can be adopted as in the case of the first light diffusing structure 191. It is not necessary that the cross-sectional shape of the second light diffusing structure 192 and the cross-sectional shape of the first light diffusing structure 191 are common. Further, here, an example in which the second light diffusion structure 192 is arranged on all the boundaries formed between the optical segments 110 is shown, but the second light is on all the boundaries formed between the optical segments 110. It is not essential that the diffusion structure 192 is arranged.

[Light guide frame 182]
The light emitting device 100C shown in FIG. 17 has a translucent light guide frame 182 that surrounds the two-dimensional arrangement of the optical segments 110 as compared with the light emitting device 100A described with reference to FIG. 1 and the like. In this example, the position of the outer edge of the light guide frame 182 coincides with the position of the outer edge of the first light diffusion structure 191.

The light guide frame 182 can be formed by a transfer mold or the like. Alternatively, after arranging the optical segments 110, the material of the light guide frame 182 is applied to the side surface of the optical segment 110 so as to surround the two-dimensional arrangement of the optical segments 110 by a dispenser or the like, and the applied material is cured to guide the light segment 110. The optical frame 182 may be formed. The light guide frame 182 may have a translucent structure joined to the optical segment 110. As the material of the light guide frame 182, the same material as the light guide member 170, for example, a thermosetting resin such as an epoxy resin or a silicone resin can be used. It is beneficial that a material having a refractive index equal to or higher than that of the light guide plate 120 can be used as the base material of the light guide frame 182.

By arranging the light guide frame 182 on the outer periphery of the two-dimensional arrangement of the optical segments 110, the light emitting area can be expanded more effectively as compared with the case where the light-shielding frame is used. The light guide frame 182 may be provided with a light diffusion function.

In the configuration illustrated in FIG. 17, a part of the first light diffusion structure 191 is located on the upper surface 182a of the light guide frame 182 and covers the entire upper surface 182a of the light guide frame 182. The other part of the first light diffusing structure 191 is located on the upper surface 110a of the optical segment 110. In top view, the size of the light guide frame 182 is the same as or smaller than the size of the first light diffusion structure 191 and the outer edge of the light guide frame 182 is the first light diffusion. It is beneficial not to cross the outer edge of structure 191. As a result, the light emitted from the side surface 120c located between the upper surface 120a and the lower surface 120b of the light guide plate 120 can be efficiently incident on the first light diffusion structure 191 via the light guide frame 182.

[Light guide structure 184]
FIG. 18 schematically shows an enlarged cross section of a part of a two-dimensional array of a plurality of optical segments 110. The light emitting device 100D shown in FIG. 18 has a translucent light guide structure 184 between optical segments 110 adjacent to each other.

In each of the above examples, each optical segment 110 is physically fixed to the support substrate 200, and two adjacent optical segments 110 in the row or column direction are typically in direct contact with each other. There is. However, it is not essential that the two-dimensional array is formed so that the two adjacent optical segments 110 are in direct contact with each other, and as illustrated in FIG. 18, the light guide structure 184 is formed between the optical segments 110. Alternatively, a structure having a function of optically coupling two optical segments 110 adjacent to each other may be interposed. By arranging the light guide structure 184 between two optical segments 110 adjacent to each other, the distance between the optical segments 110 in the two-dimensional array can be increased, and therefore a larger light emitting area can be easily obtained.

The light guide structure 184 can be formed, for example, by applying a translucent adhesive to the side surface of the optical segment 110 and then curing the applied adhesive. Alternatively, the light guide structure 184 can also be formed by filling the regions between the optical segments 110 arranged on the support substrate 200 at intervals from each other with a translucent resin material and then curing the resin material. As the material of the light guide structure 184, the same material as that of the light guide member 170 can be used. As the base material of the light guide structure 184, it is beneficial to be able to use a material having a refractive index equal to or higher than that of the light guide plate 120. A light diffusing function may be added to the light guide structure 184.

In the example shown in FIG. 18, the above-mentioned second light diffusion structure 192 is further arranged so as to cover the light guide structure 184. That is, the light guide structure 184 may have a grid-like shape when viewed from above. According to such a configuration, the brightness of the region directly above the light guide structure 184 can be compensated by the second light diffusion structure 192, which is advantageous from the viewpoint of obtaining uniform light.

FIG. 19 shows another example of the shape of the light guide structure arranged between the optical segments 110. Similar to the example described with reference to FIG. 18, the light emitting device 100E shown in FIG. 19 has a light guide structure 186 located between the optical segments 110 adjacent to each other. However, in this example, a part of the light guide structure 186 is raised so as to protrude from the upper surface 120a of the light guide plate 120.

In the example shown in FIG. 19, the portion 188 of the light guide structure 186 protruding from the upper surface 120a of the light guide plate 120 can function as the second light diffusion structure. In this way, a part of the light guide structure 186 may function as a second light diffusion structure. For example, in the process of forming the light guide structure 186, by adjusting the viscosity and amount of the applied resin material or adhesive, a structure exhibiting the same function as the second light diffusion structure 192 is provided on the upper surface 120a of the light guide plate 120. It can be formed on the side.

FIG. 20 shows another example of the shape of the first light diffusion structure. FIG. 20 schematically shows an example of the appearance of the light emitting device when viewed from the upper surface 110a side of the optical segment 110, as in FIG. 2 and the like. Note that FIG. 20 shows an example in which the four optical segments 110 are arranged in 2 rows and 2 columns in order to avoid making the figure excessively complicated. It is similar to the examples described so far that the number and arrangement of the optical segments 110 are not limited to this example.

Compared with the light emitting device 100A described with reference to FIG. 2 and the like, the light emitting device 100F shown in FIG. 20 has a first light diffusing structure 191R instead of the first light diffusing structure 191. In the configuration illustrated in FIG. 20, a part of the first light diffusion structure 191R is located on the upper surface 110a of these optical segments 110. Further, in FIG. 20, in order to avoid the drawing from becoming excessively complicated, the frame 180 is not shown, but the other part of the first light diffusion structure 191R is the upper surface 180a of the frame 180. It may be located on top.

As schematically shown in FIG. 20, the first light diffusion structure 191R has a quadrangular outer shape with rounded corners in a plan view. As in this example, the outer shape of the first light diffusion structure 191R in a plan view is not limited to a figure similar to the outer shape (here, a rectangular shape) formed by a two-dimensional array of a plurality of optical segments 110. The outer shape of the first light diffusion structure in a plan view may be a rectangular shape, a rounded square shape, a circular shape, an elliptical shape, or the like.

As described above, in the embodiment of the present disclosure, the outer shape of the first light diffusion structure in a plan view is not limited to a rectangular shape. The light emitting device according to the embodiment of the present disclosure includes not only a display having a rectangular outer shape but also a variety of instrument panels, smart watches, smart speakers, etc. mounted on automobiles and the like, which may require a circular or elliptical surface light source. Can be applied advantageously to various parts and products.

As described above, according to the embodiment of the present disclosure, it is possible to provide a light source device capable of flexibly adapting to various screen sizes or shapes while further reducing the thickness. In each of the above-described embodiments, the arrangement of the optical segments 110 shown in the figure is merely an example, and the number and arrangement of the optical segments 110 in the light emitting device can be arbitrarily set. In addition, each of the above-described embodiments is merely an example, and various combinations are possible as long as there is no technical contradiction.

The embodiment of the present disclosure is applicable not only to the direct method but also to the edge lit method. For example, light may be introduced from the side surface 120c of the light guide plate 120 to optically couple the light emitting element such as an LED and the first light diffusion structure arranged on the upper surface 110a side of the optical segment 110 to each other. In this case, the plurality of recesses 124 on the lower surface 120b of the light guide plate 120 may be omitted. That is, the lower surface 120b of the light guide plate 120 may be a flat surface.

The embodiments of the present disclosure are useful for various lighting light sources, vehicle-mounted light sources, display light sources, and the like. In particular, it can be advantageously applied to a backlight unit directed to a liquid crystal display device. The light emitting device according to the embodiment of the present disclosure can be suitably used for a backlight for a display device of a mobile device, which is strictly required to reduce the thickness, a surface light emitting device capable of local dimming control, and the like. Since the local dimming control can be easily applied, the embodiment of the present disclosure is also advantageous for HDR (High Dynamic Range).

100A-100H Light emitting device 110 Optical segment 120 Light guide plate 122 Light diffuser 124 Recessed 130 Light emitting element 140 Wavelength conversion member 150 Light reflection member 160 Wiring 170 Light guide member 180 Frame body 182 Light guide frame 184, 186 Light guide structure 191, 191A , 191B, 191R 1st light diffusion structure 192 2nd light diffusion structure 200 Support board 210 Driver 212 Wiring 300 Liquid crystal display device 310 Liquid crystal panel 320 Light source unit 330 Optical sheet group

Claims (13)

A plurality of optical segments arranged in rows and columns, each having a first surface and a second surface located on the opposite side of the first surface, and a plurality of optical segments including a plurality of light emitting elements.
It has a first light diffusing structure that is located on the first surface side of the light guide plate and extends along the outer circumference of an array of the plurality of optical segments.
The first light diffusion structure has a frame shape having an opening in the center, and has a portion located outside the array of the plurality of optical segments and a portion located on the first main surface of the light guide plate. , Light emitting device. A plurality of optical segments arranged in rows and columns, each having a first surface and a second surface located on the opposite side of the first surface, and a plurality of optical segments including a plurality of light emitting elements.
With a first light diffusion structure located on the first surface side of the light guide plate and extending along the outer circumference of an array of the plurality of optical segments.
With
The first light diffusion structure has a linear shape extending along the outer circumference of the array of the plurality of optical segments, a portion located outside the array of the plurality of optical segments, and a first main surface of the light guide plate. A light emitting device having a portion located above. The light emitting device according to claim 1 or 2 , further comprising a second light diffusion structure located on the first surface side of the light guide plate, straddling the boundary of optical segments adjacent to each other, and extending along the boundary. .. A frame body surrounding the outer periphery of the plurality of optical segments is further provided.
1. A part of the first light diffusing structure is located on the upper surface of the frame, and the other part of the first light diffusing structure is located on the first surface of the optical segment. The light emitting device according to any one of 3 to 3. The light emitting device according to any one of claims 1 to 4 , further comprising a light guide structure located between optical segments adjacent to each other and optically coupling the optical segments adjacent to each other. The light emitting device according to any one of claims 1 to 5 , further comprising a light reflecting member located on the second surface side of the light guide plate and covering the side surface of each light emitting element. The first surface of the light guide plate has a plurality of light diffusing portions arranged in two dimensions.
The light emitting device according to any one of claims 1 to 6 , wherein each light emitting element is fixed at a position directly below one of the plurality of light diffusing portions on the second surface side of the light guide plate. The second surface of the light guide plate has a plurality of recesses.
Each of the plurality of recesses is located on the opposite side of the corresponding one of the plurality of light diffusers.
The light emitting device according to claim 7 , further comprising a wavelength conversion member arranged inside each recess. Further equipped with multiple light guide members,
Each light-emitting element, the plurality of which by one of the light guide member is joined to a corresponding one of the wavelength conversion member, the light emitting device according to claim 8. The light emitting device according to any one of claims 7 to 9 , wherein the plurality of light diffusing portions of the light guide plate are a plurality of second recesses. The light emitting device according to any one of claims 1 to 10 , further comprising a plurality of wirings, each of which electrically connects the plurality of light emitting elements of each optical segment to each other. The shape of each optical segment in the top view is rectangular.
The light emitting device according to any one of claims 1 to 11 , wherein the length of one side of the rectangular shape is in the range of 20 mm or more and 25 mm or less. It has a linear shape extending along the outer circumference of the array of the plurality of optical segments, and has a portion located outside the array of the plurality of optical segments and a portion located on the first main surface of the light guide plate. , Further equipped with another first light diffusion structure,
The shape of the plurality of optical segments in the top view of the arrangement is rectangular.
The first light diffusing structure is located along the rectangular side of the array.
The light emitting device according to claim 2 , wherein the other first light diffusion structure is located along the other side facing the rectangular side of the array.

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