CN106990609B

CN106990609B - Backlight device and display device including the same

Info

Publication number: CN106990609B
Application number: CN201710012642.7A
Authority: CN
Inventors: 越智铁朗
Original assignee: Japan Display Inc
Current assignee: Japan Display Inc
Priority date: 2016-01-07
Filing date: 2017-01-06
Publication date: 2020-12-15
Anticipated expiration: 2037-01-06
Also published as: JP2017126553A; JP6689727B2; TWI622819B; TW201734522A; KR101950567B1; CN106990609A; KR20170082981A

Abstract

The invention provides a backlight device and a display device including the same. The backlight device according to the embodiment includes: a frame (16) formed of a transparent resin; a first diffusion adhesive layer (24a) provided on the first surface of the frame and having light diffusion properties; a second diffusion adhesive layer (24b) provided on a second surface of the frame opposite to the first surface and having light diffusion properties; a reflective sheet (RE) adhered to the frame by a first diffusion adhesive layer; a light guide plate (LG) mounted on the reflector in the frame; and a light source disposed in the frame and emitting light to the light guide plate.

Description

Backlight device and display device including the same

Cross Reference to Related Applications

This application is based on and claims the benefit of priority from Japanese patent application No. 2016-.

Technical Field

Embodiments described herein relate to a backlight device, and a display device including the same.

Background

In recent years, liquid crystal display devices have been widely used as display devices for smartphones, Personal Assistant Devices (PADs), tablet computers, car navigation systems, and the like. In general, a liquid crystal display device includes: a liquid crystal display panel, and a planar illumination device (backlight device) which is disposed so as to overlap the rear surface of the liquid crystal display panel and illuminates the liquid crystal display panel. The conventional backlight device includes: a reflective layer, a Light guide plate (Light guide), an optical sheet, an LED (Light Emitting Diode) as a Light source, and a rectangular frame made of resin. The reflective layer, the light guide plate, and the optical sheet are stacked on each other and embedded in the frame. Thus, the reflective layer, the light guide plate, and the optical sheet are held and positioned by the frame.

Further, a structure has been proposed in which a frame is fitted into a metal plate-made housing case (backlight cover), and a reflective layer, a light guide plate, and an optical sheet are further disposed in a hollow portion of the frame.

In recent years, with an increase in the size of a display area, liquid crystal display devices are increasingly required to have a narrower frame and a thinner thickness. However, the dimensions of the width, thickness, and the like of the frame of the backlight device described above are approaching the limit dimensions that can be formed by injection molding, and it has been difficult to meet such requirements.

In addition, with the narrowing of the frame, the tolerance between the effective illumination area of the backlight device and the effective liquid crystal display area becomes smaller. Therefore, when the backlight device is mounted to the liquid crystal display device, the liquid crystal display effective area is deviated from the effective illumination area, and as a result, the display quality may be degraded.

Disclosure of Invention

According to an embodiment, a backlight device includes: a frame-shaped frame formed of a transparent resin; a first diffusion adhesive layer provided on the first surface of the frame and having light diffusibility; a second diffusion adhesive layer provided on a second surface of the frame opposite to the first surface and having light diffusibility; a reflective sheet adhered to the frame by the first diffusion adhesive layer; a light guide plate placed on the reflective sheet in the frame; and a light source disposed in the frame and emitting light to the light guide plate.

Drawings

Fig. 1 is a perspective view showing a display surface side of a liquid crystal display device of an embodiment.

Fig. 2 is a perspective view showing the back side of the liquid crystal display device.

Fig. 3 is an exploded perspective view showing the liquid crystal display device.

Fig. 4 is a sectional view of the liquid crystal display device along line a-a of fig. 1.

Fig. 5 is a sectional view of the liquid crystal display device taken along line B-B of fig. 1.

Fig. 6A is a diagram schematically showing the distribution of diffusibility of the diffusible adhesive layer provided on the frame.

Fig. 6B is a diagram schematically showing the distribution of diffusibility of the diffusible adhesive layer provided on the frame.

Fig. 7 is a diagram schematically showing an example of a manufacturing apparatus of a backlight device.

Fig. 8 is a perspective view illustrating a sheet in a manufacturing process of the backlight device.

Fig. 9 is a perspective view showing a state in which the diffusion adhesive layers are formed on the first surface and the second surface of the sheet in the manufacturing process.

Fig. 10 is a perspective view showing a state where an inner window (inner hole) of a frame is perforated in the manufacturing process.

Fig. 11 is a perspective view showing a state where a reflection sheet is attached to one diffusion adhesive layer in the above-described manufacturing process.

Fig. 12 is a perspective view showing a backlight device in which an outer shape is formed by punching in the manufacturing process.

Fig. 13 is a cross-sectional view of a liquid crystal display device of the second embodiment.

Fig. 14 is a longitudinal sectional view of the liquid crystal display device of the second embodiment.

Fig. 15 is a cross-sectional view of a liquid crystal display device of a third embodiment.

Fig. 16 is a longitudinal sectional view of a liquid crystal display device of the third embodiment.

Fig. 17 is a cross-sectional view of a liquid crystal display device of a fourth embodiment.

Fig. 18 is a longitudinal sectional view of a liquid crystal display device of the fourth embodiment.

Fig. 19 is a perspective view showing the display surface side of the liquid crystal display device of the fifth embodiment.

Fig. 20 is a sectional view of the liquid crystal display device along line C-C of fig. 19.

Fig. 21 is a sectional view of a liquid crystal display device according to a first modification.

Fig. 22 is a sectional view of a liquid crystal display device according to a second modification.

Detailed Description

Various embodiments are described below with reference to the drawings.

It should be noted that the present disclosure is merely an example, and it is needless to say that appropriate modifications that are easily conceivable within the scope of the gist of the present invention by those skilled in the art are also included in the scope of the present invention. In addition, the drawings are intended to schematically show the width, thickness, shape, and the like of each part as compared with an actual form for clarity of description, and are merely examples, and do not limit the present invention. In the present specification and the drawings, the same reference numerals are given to the same parts as those described in the previous drawings, and detailed description thereof may be omitted as appropriate.

(first embodiment)

Fig. 1 and 2 are perspective views showing a display surface side and a back surface side of the liquid crystal display device of the first embodiment, respectively, and fig. 3 is an exploded perspective view of the liquid crystal display device.

The liquid crystal display device 10 can be incorporated into various electronic apparatuses such as a smartphone, a tablet terminal, a mobile phone, a notebook PC, a portable game machine, an electronic dictionary, a television device, and a car navigation system.

As shown in fig. 1 to 3, the liquid crystal display device 10 includes: an active matrix type flat liquid crystal display panel 12 (LCD panel), a cover panel 14 disposed so as to overlap a display surface 12a which is a flat plate surface of the liquid crystal display panel 12 and cover the entire display surface, and a backlight unit (backlight device) 20 disposed to face a back surface side which is the other flat plate surface of the liquid crystal display panel 12.

Fig. 4 is a sectional view of the liquid crystal display device along line a-a of fig. 1, and fig. 5 is a sectional view of the liquid crystal display device along line B-B of fig. 1. As shown in fig. 3 to 5, the liquid crystal display panel 12 includes: a first substrate SUB1 in the shape of a rectangular flat plate, a second substrate SUB2 in the shape of a rectangular flat plate disposed to face the first substrate SUB1, and a liquid crystal layer LQ provided between the first substrate SUB1 and the second substrate SUB 2. The peripheral edge portion of the second substrate SUB2 is bonded to the first substrate SUB1 with a seal material SE. A polarizing plate PL1 is attached to the surface of the second substrate SUB2, thereby forming the display surface 12a of the liquid crystal display panel 12. A polarizing plate PL2 is attached to the surface of the first substrate SUB1 (the back surface of the liquid crystal display panel 12). The polarizing plate PL2 has a size slightly larger than the outer size of the first substrate SUB1 in a plan view, and covers the entire surface of the first substrate SUB 1. In addition, the plan view refers to a state in which the liquid crystal display panel is viewed from a direction normal to the surface of the liquid crystal display panel.

In the liquid crystal display panel 12, a display region (active area) DA is provided in a region inside the seal material SE in a plan view of the display surface 12 a. An image is displayed on the display area DA. A frame region (non-display region) ED is provided around the display region DA. The display area is rectangular, and the frame area is rectangular frame-shaped. The liquid crystal display panel 12 is a transmissive type that displays an image by selectively transmitting light from the backlight unit 20 to the display area DA. The liquid crystal display panel 12 can adopt various display modes. For example, the configuration may be made to correspond to a lateral electric field mode mainly using an electric field substantially parallel to the main surface of the substrate, or may be made to correspond to a longitudinal electric field mode mainly using an electric field substantially perpendicular to the main surface of the substrate.

In the illustrated example, a flexible printed circuit board (FPC)22 is bonded to an end portion on the short side of the first substrate SUB1, and extends outward from the liquid crystal display panel 12. A semiconductor element such as a driver IC chip 21 is mounted on the FPC 22 as a signal supply source for supplying a signal necessary for driving the liquid crystal display panel 12.

As shown in fig. 1 to 5, the cover panel 14 is formed in a rectangular flat plate shape by, for example, a glass plate or an acrylic transparent resin. The cover panel 14 has a width and a length larger than the dimensions (width, length) of the liquid crystal display panel 12. Thus, the cover panel 14 has a larger area than the liquid crystal display panel 12 in a plan view. A frame-shaped light-shielding layer RS is formed on the peripheral edge of the back surface of the cover panel 14 (the surface on the liquid crystal display panel 12 side or the surface opposite to the surface facing the viewer). In the cover panel 14, a region other than the region facing the display region DA is shielded from light by the light shielding layer RS. Further, a light shielding layer RS may be formed on the surface (display surface) of the cover panel 14.

The back surface (lower surface) of cover panel 14 is adhered to polarizing plate PL1 by an adhesive sheet AD having light permeability or made of a transparent adhesive or sticking agent such as an optically transparent resin. Thereby, the cover panel 14 entirely covers the display surface 12a of the liquid crystal display panel 12. Further, the adhesive sheet AD was formed in the same size as the polarizing plate PL1 and adhered in alignment to the polarizing plate PL 1. Instead of the adhesive sheet AD, an adhesive may be applied to the polarizing plate PL1 and the periphery thereof.

The peripheral edge (periphery) of the cover panel 14 protrudes outward beyond the peripheral edge (periphery) of the liquid crystal display panel 12. The long side of cover panel 14 and the long side of liquid crystal display panel 12 are substantially parallel to each other with a predetermined gap (a prescribed gap). The short side of the cover panel 14 is substantially parallel to the short side of the liquid crystal display panel 12 with a predetermined gap therebetween. In the present embodiment, the distance between the long side of the cover panel 14 and the long side of the liquid crystal display panel 12, that is, the width of the long-side peripheral edge of the cover panel 14 is formed smaller than the distance between the short side of the cover panel 14 and the short side of the liquid crystal display panel 12, that is, the width of the short-side peripheral edge of the cover panel.

Further, the cover panel and the liquid crystal display panel may be configured to have rounded corners. In this case, a configuration may be adopted in which only one or two corners are rounded without rounding all the corners. In addition, both a configuration in which only one corner portion of the cover panel and the liquid crystal display panel is rounded and a configuration in which both corner portions are rounded may be employed.

As shown in fig. 3 to 5, the backlight unit 20 includes: a rectangular frame 16 attached to the back surface of the liquid crystal display panel 12, a reflection sheet RE attached to the back surface of the frame 16, a plurality of optical members arranged in the frame 16, and a light source unit 30 that supplies light incident to the optical members.

The frame 16 is made of a sealing material having a thickness T1 of 0.40mm (400 μm) or less, for example, 0.10mm to 0.25mm (100 μm to 255 μm). The outer shape of the frame 16 is slightly larger than the outer shape of the liquid crystal display panel 12 and smaller than the outer shape of the cover panel 14 in a plan view. A translucent or transparent resin sheet such as a sheet of polyethylene terephthalate (PET) can be used as the sealing material. The resin sealing material used here is a sheet having a thickness of about 100 to 300 μm, a separator having a thickness of less than 100 μm, a film, or the like.

As described later, the frame 16 is formed by punching a resin sealing material and has a predetermined size. The frame 16 has the same thickness T1 throughout the entire circumference, and has no irregularities in the thickness direction (Z direction when viewed in cross section). In the present embodiment, the thickness T1 of the frame 16 (thickness of the sealing material) is set to 0.188mm (188 μm) or 0.25mm (250 μm). Frame 16 has a first face SF1 and a second face SF 2. The second surface SF2 faces (facing) the liquid crystal display panel 12, and the first surface SF1 is a lower surface on the opposite side (exposed to) from the second surface SF 2.

The frame 16 has a pair of long side portions (long bar)16a, 16b opposed to each other, and a pair of short side portions (short bar)16c, 16d opposed to each other. The width W1 of each

long side portion

16a, 16b is 0.6mm (600 μm) or less, for example, 0.4mm to 0.5mm (400 μm to 500 μm). The width W2 of the short side portion 16c is 0.6mm (600 μm) or less, for example, 0.4mm to 0.5mm (400 μm to 500 μm) as with the width W1. W3 on the other short side portion 16d is formed to be 0.6mm (600 μm) or less, for example, 0.4mm to 0.5mm (400 μm to 500 μm) as with the width W2. The width W3 of the short side portion 16d may be larger than the width W2. Further, a plurality of recesses 17 are provided on the inner edge side of the other short side portion 16 d.

In addition, hereinafter, there is a case where one short side portion is referred to as an upper side portion (upper bar) and the other short side portion is referred to as a lower side portion (lower bar). In addition, the pair of long sides may be called right-and-left sides (right-and-left bars). In addition, the left and right side portions and the upper side portion may be collectively referred to as a three-side portion excluding the lower side portion.

A first diffusion adhesive layer 24a is formed on the lower surface (first face) SF1 of the frame 16. In addition, a second diffusion adhesive layer 24b is formed on the upper surface (second surface) SF2 of the frame 16. As shown in fig. 4, the first diffusion adhesive layer 24a and the second diffusion adhesive layer 24B are formed by mixing a transparent adhesive (binder) with a light-diffusing adhesive containing a plurality of beads B having a refractive index different from that of the adhesive. As the adhesive, for example, an adhesive composed of acrylic, polystyrene, polyester, epoxy resin, vinyl polymer, or the like, a UV curable adhesive, or the like can be used. As the beads B, light-transmissive hollow silica particles, glass particles, or particles made of synthetic resin can be used. As the material for forming the beads, a material having good transparency is used, such as a resin obtained by curing an ionizing radiation-curable resin, which is composed of an acrylic resin such as polymethyl methacrylate, a polyester resin such as polyethylene terephthalate or polybutylene terephthalate, a thermoplastic resin such as polystyrene resin, polycarbonate resin or methylpentene resin, an oligomer such as polyester acrylate, urethane acrylate or epoxy acrylate, and/or an acrylate monomer, with an electromagnetic radiation such as ultraviolet light or electron beam. Alternatively, glass, ceramic, etc. may be used if transparent, in addition to the resin. The light diffusibility of the diffusion adhesive layer can be appropriately adjusted by adjusting the content of the beads B, the refractive index of the beads B, and the like. In the present embodiment, the light diffusibility da of the first diffusive adhesive layer 24a is larger than the light diffusibility db of the second diffusive adhesive layer 24 b. Here, the light diffusibility db is the light diffusibility of the entire second diffusion adhesive layer 24b provided on the

long side portions

16a, 16b and the short side portion 16c, regardless of whether the second diffusion adhesive layer 24b in that portion is constituted by several layers.

The thickness T2 of the first diffusion pressure-sensitive adhesive layer 24a is, for example, 0.01 to 0.06mm (10 to 60 μm), and the thickness T3 of the second diffusion pressure-sensitive adhesive layer 24b of the

long side portions

16a, 16b and the upper side portion 16c is, for example, 0.01 to 0.06mm (10 to 60 μm). Thus, the total thickness of the frame 16, the first diffusion adhesive layer 24a, and the second diffusion adhesive layer 24b is, for example, 0.32mm to 0.52mm (320 μm to 520 μm) on the

long side portions

16a and 16b and the upper side portion 16c side, which have the maximum thickness.

In the pair of

long side portions

16a, 16b, the first diffusion adhesive layer 24a and the second diffusion adhesive layer 24b have the same width as the width W1 of the

long side portions

16a, 16b, respectively, and at least the outer surface (external surface) of the frame 16, the outer surface (external surface) of the first diffusion adhesive layer 24a, and the outer surface (external surface) of the second diffusion adhesive layer 24b are flush with each other. In the present embodiment, the inner surface (internal surface) of the first diffusion adhesive layer 24a and the inner surface (internal surface) of the second diffusion adhesive layer 24b are also flush with the inner surface (internal surface) of the frame 16. Alternatively, when viewed between the

long side portions

16a, 16b of the frame 16, the inner diameter (internal dimension) between the

long side portions

16a, 16b is equal to the inner diameter (internal dimension) between the first diffusion adhesive layers 24a and the inner diameter (internal dimension) between the second diffusion adhesive layers 24b provided in the respective

long side portions

16a, 16 b. Similarly, the outer diameter dimension between the

long side portions

16a, 16b is equal to the outer diameter dimension (external dimension) between the first diffusion adhesive layers 24a provided on the

long side portions

16a, 16b and the outer diameter dimension (external dimension) between the second diffusion adhesive layers 24b provided on the

long side portions

16a, 16 b.

In the present embodiment, the first diffusion adhesive layer 24a and the second diffusion adhesive layer 24b have the same width as the widths W2 and W3 of the

short side portions

16c and 16d, respectively, in the

short side portions

16c and 16d of the frame 16, and the outer side surfaces and the inner side surfaces of the frame 16 and the first diffusion adhesive layer 24a are flush with each other, respectively. The outer side surfaces and the inner side surfaces of the frame 16 and the second diffusion adhesive layer 24b are flush with each other. Alternatively, when viewed between the

short side portions

16c and 16d of the frame 16, the inner diameter dimension between the

short side portions

16c and 16d is equal to the inner diameter dimension between the first diffusion adhesive layers 24a and the inner diameter dimension between the second diffusion adhesive layers 24b provided on the

short side portions

16c and 16d, respectively. Similarly, the outer diameter of the

short side portions

16c and 16d is equal to the outer diameter between the first diffusion adhesive layers 24a and the outer diameter between the second diffusion adhesive layers 24b provided in the

short side portions

16c and 16 d.

In the present embodiment, a double-sided tape having an adhesive layer is used for both surfaces of the light-transmitting substrate as the first diffusion adhesive layer 24a and the second diffusion adhesive layer 24 b. The thickness of each adhesive layer can be easily adjusted by changing the thickness of each base material.

The second diffusion adhesive layer 24b on the three

side portions

16a, 16b, and 16c except the lower side portion is formed thicker than the second diffusion adhesive layer 24b on the lower side portion 16d, for example, about 2 times as thick. In this case, the second diffusion adhesive layers 24b on the three

side portions

16a, 16b, and 16c may be two layers of adhesive layers stacked to have the same thickness as the second diffusion adhesive layer 24b on the lower side portion 16 d. Further, the second diffusion adhesive layer 24b on the lower side portion 16d is made thinner than the second diffusion adhesive layer 24b on the

long side portions

16a and 16b, thereby forming a gap for passing through an FPC 32 of the light source unit 30, which will be described later.

As schematically shown in fig. 6A, the content of the beads B can be adjusted so that the light diffusion in the first diffusion adhesive layer 24a in the portion provided on the upper side portion 16c is lower than the light diffusion in the portions provided on the left and right side portions 16A and 16B. Similarly, the content of the beads B can be adjusted so that the diffusion in the second diffusion adhesive layer 24B is lower in the portion provided on the upper side portion 16c than in the portions provided on the left and right side portions 16a and 16B.

Alternatively, as schematically shown in fig. 6B, the content of the beads B may be adjusted so that the light diffusibility of the first diffusion adhesive layer 24a provided on the left and right side portions 16a, 16B gradually increases from the lower side portion 16d to the upper side portion 16 c. Similarly, the content of the beads B may be adjusted so that the light diffusibility of the second diffusion adhesive layer 24B provided on the left and right side portions 16a, 16B gradually increases from the lower side portion 16d to the upper side portion 16 c.

In addition, in the configuration in which the configuration shown in fig. 6A and the configuration shown in fig. 6B are combined, even if the light diffusibility of the first and second diffusion adhesive layers 24a and 24B in the upper side portion 16c is lower than that in any of the left and right side portions 16A and 16B, it is possible to adjust the light diffusibility. For example, the light diffusibility at the upper side portion 16c is lower than the light diffusibility at the positions closest to the light source of the left and

right side portions

16a, 16 b. Alternatively, the light diffusibility of the upper side portion 16c is made lower than the light diffusibility at the position of the left and

right side portions

16a, 16b farthest from the light source. The light diffusibility in the longitudinal center portions of the left and

right side portions

16a, 16b is made the same as that of the upper side portion 16 c.

In fig. 6A and 6B, the difference in light diffusibility of each diffusion adhesive layer is shown by the number of beads B, but a method for changing light diffusibility by changing the particle size or particle size distribution of beads B whose light diffusibility should be changed, or by using materials having different refractive indices/transmittances, or the like is suitably used.

Further, by performing white dot printing or the like on the rear surface of the frame 16 facing the reflective sheet RE, the light transmittance of the frame 16 can be adjusted. At this time, the density of dots printed by the white dots is gradually changed from sparse to dense from near to far in the light source unit 30, so that the frame 16 can have a light transmittance corresponding to the distance from the light source unit 30.

As shown in fig. 3 to 5, the reflection sheet RE is adhered to the lower surface SF1 of the frame 16 through the first diffusion adhesive layer 24a, and covers the lower surface side of the frame 16. The reflector RE is a reflector having a film thickness of 200 μm or less, preferably 50 μm to 90 μm, and a reflectance of 90% or more, preferably 95% or more. In addition, in either of the case of viewing through the space between the

long side portions

16a, 16b of the frame 16 and the case of viewing through the space between the

short side portions

16c, 16d of the frame 16, the reflection sheet RE is formed in a rectangular shape having a size equal to the outer dimension of the frame 16. The outer surface of the reflection sheet RE and the outer surface of the frame 16 are aligned flush with each other, and neither of them protrudes from the other.

The backlight unit 20 includes a rectangular light guide plate LG as an optical member housed in the frame 16 in a plan view, and an optical sheet OS disposed on the light guide plate LG in a superposed manner. Also, the backlight unit 20 includes a light source unit 30. The light source unit 30 is provided along one side surface (incident surface) EF of the light guide plate LG, and emits light toward the light guide plate LG.

The light guide plate LG is formed in a rectangular shape from an extremely thin resin sheet having light transmittance, and is in a square shape. The light guide plate LG includes a first main surface S1 serving as an exit surface, a second main surface S2 on the opposite side of the first main surface S1, and an entrance surface EF connecting the first main surface S1 and the second main surface S2. In the present embodiment, one side surface on the short side of the light guide plate LG is used as the incident surface EF. The light guide plate LG has an external shape slightly smaller than the inner diameter (internal dimensions) of the frame 16 and slightly larger than the display area DA of the liquid crystal display panel 12 in a plan view. The thickness of the light guide plate LG is the thickest on one side surface (incident surface) facing the light source unit 30, and the thinnest on the other side surface opposite to the one side surface. In the present embodiment, the thickness of the other side surface is set to, for example, about 0.2mm to 0.5mm (200 μm to 500 μm) as the thickness of the light guide plate LG. According to the present embodiment, the thickness T1 of the frame 16 is formed to be thinner than the thickness of the thinnest portion of the light guide plate LG. The sum of the thickness of the light guide plate LG and the thicknesses of the optical sheets OS is substantially equal to the sum of the thickness T1 of the frame 16 and the thicknesses T2 and T3 of the first diffusion adhesive layer 24a and the second diffusion adhesive layer 24 b. That is, the total thickness of the light guide plate LG and the optical sheet OS is, for example, 0.36 to 0.52mm (360 to 520 μm). Further, an extremely thin light guide plate LG having a plate thickness of 0.2mm (200 μm) or less can be used. The light guide plate LG is placed on the reflective sheet RE in a state where the second main surface S2 faces the reflective sheet RE so as to overlap. The incident surface EF of the light guide plate LG faces the short side portion 16d of the frame 16. The other side surface of the light guide plate LG faces the short side portion 16c and the

long side portions

16a and 16b of the frame 16 with a small gap of about 0.05mm to 0.2mm (50 μm to 200 μm).

The optical sheet OS has optical transparency and is superimposed on the first main surface S1 of the light guide plate LG. In the present embodiment, as the optical sheet OS, for example, a diffusion sheet OS1 and a prism sheet OS2 formed of a synthetic resin such as polyethylene terephthalate are used. The diffusion sheet OS1 and the prism sheet OS2 are sequentially stacked on the first main surface S1 of the light guide plate LG. Each optical sheet OS has a width equal to the width of the light guide plate LG and a length slightly shorter than the length of the light guide plate LG in a plan view. Each optical sheet OS is formed to have a size slightly larger than the display area DA of the liquid crystal display panel 12. At least three side edges of the optical sheet OS other than the side edge on the light source side are directly opposed to the frame 16 with a predetermined gap (0.1mm to 0.5mm) (sharpening direct). The optical sheet OS faces the back surface of the liquid crystal display panel 12 with a slight gap. Thereby, the optical sheet OS faces the entire display area DA of the liquid crystal display panel 12.

As shown in fig. 3 and 5, the light source unit 30 includes: an elongated, band-shaped flexible printed circuit substrate (FPC)32 and a light source mounted on the FPC 32. According to the present embodiment, as the light source, for example, a light source in which Light Emitting Diodes (LEDs) 34 as point light sources are arranged at predetermined intervals is used. Each of the plurality of LEDs 34 has an emission surface 34a and a mounting surface 34b perpendicular to the emission surface 34 a. The LEDs 34 are arranged at predetermined intervals along the longitudinal direction of the FPC 32 (the direction parallel to the short side portion of the frame 16). Each LED34 is mounted with mounting surface 34b facing FPC 32. The FPC 32 has a connection end portion 32a (see fig. 3) extending from one side edge.

One long side portion of the FPC 32 is overlapped with the short side portion 16d by the second diffusion adhesive layer 24b, and the other long side portion is positioned at an end portion of the light guide plate LG on the incident surface EF side. Thus, the LEDs 34 are arranged between the short side portion 16d of the frame 16 and the incident surface EF of the light guide plate LG. The emission surface 34a of each LED34 faces the incidence surface EF. In the present embodiment, the LED34 is disposed in the recess 17 of the short side portion 16 d. The height (thickness) Lh of each LED34 is preferably 0.4mm (400 μm) or less, and more preferably 0.3mm (300 μm) or less.

Further, a fluorescent tube or a cathode ray tube as a linear light source can be used as the light source. Alternatively, a line light source or a surface light source in which light sources made of organic EL are arranged very densely can be used as the light source.

As shown in fig. 5, a fourth adhesive layer such as a double-sided tape 37 is adhered at the end (end) of the optical sheet OS2 on the light source side and the end of the FPC 32 on the optical sheet side. In addition, the end of the optical sheet OS1 at the lowermost part of the light source side extends from the light source side than the end of the optical sheet OS2, and is adhered to the double-sided tape 37. Thereby, the optical sheets OS1 and OS2 are bonded to the FPC 32 by the double-sided tape 37.

As shown in fig. 3 and 5, a third adhesive layer in the form of a long and narrow tape, for example, a double-sided tape 36, is superimposed and adhered on the FPC 32 and the end of the optical sheet OS.

The backlight unit 20 configured as described above is disposed to face the back surface of the liquid crystal display panel 12, and is attached to the polarizing plate PL2 of the liquid crystal display panel 12 via the second diffusion adhesive layer 24b and the double-sided tape 36.

That is, the left and right

long sides

16a, 16b of the frame 16 are respectively adhered to the long-side end of the polarizing plate PL2 via the second diffusion adhesive layer 24 b. Thus, the left and

right side portions

16a and 16b are along the long side of the polarizing plate PL 2. The upper edge 16c of the frame 16 is adhered to the short-side end of the polarizing plate PL2 via the second diffusion adhesive layer 24 b. Thus, upper edge 16c is along the short side of polarizing plate PL 2. Thus, the three side portions (three bars)16a, 16b, and 16c are positioned to overlap the frame region ED of the liquid crystal display panel 12 in a plan view. These three side portions (three bars)16a, 16b, and 16c are arranged on the same plane as the side surface of the polarizing plate PL 2.

In the present embodiment, the three sides of the frame 16 other than the light source side may be configured such that the end of the polarizing plate is flush with the end of the liquid crystal display panel, or positioned inside the end of the liquid crystal display panel.

The FPC 32 mounted on the lower side portion 16d of the frame 16 is adhered not to the polarizing plate PL2 but to the back side of the first insulating substrate SUB1 of the liquid crystal display panel 12 via the double-sided tape 36. Thus, the lower side portion 16d and the light source unit 30 are positioned to overlap the frame region ED of the liquid crystal display panel 12 and the light-shielding layer RS of the cover panel 14.

The FPC 32 is connected to the FPC 22 via a connection end portion 32a (see fig. 2). Thereby, a drive current is supplied to the LED34 through the

FPCs

22 and 32. The light emitted from the LED34 enters the light guide plate LG from the entrance surface EF of the light guide plate LG, and propagates through the light guide plate LG. The light is once emitted from the second main surface S2, reflected by the reflecting sheet RE, and again incident into the light guide plate LG. After passing through the optical path, the light from the LED34 is emitted from the first main surface (emission surface) S1 toward the liquid crystal display panel 12. The emitted light is diffused by the optical sheet OS and then irradiated to the display area DA of the liquid crystal display panel 12.

The light leaking from the side surface other than the incident surface EF of the light guide plate LG enters the left and

right side portions

16a and 16b and the upper side portion 16c of the frame 16, and propagates through the frame 16. The light is emitted from the lower surface SF1 of the frame 16 to the first diffusion adhesive layer 24a, reflected by the reflection sheet RE, and again enters the first diffusion adhesive layer 24a and the frame 16. After passing through such an optical path, the light entering the frame 16 again is diffused by the second diffusion adhesive layer 24b, and is emitted from the second diffusion adhesive layer 24b to the liquid crystal display panel 12 side, and is irradiated to the peripheral edge portion of the liquid crystal display panel 12. The peripheral portion includes a border between the frame region, the frame region and the display region and its periphery. In this way, the frame 16 and the first and second diffusion

adhesive layers

24a and 24b function as an auxiliary light source section for guiding the light leaked from the periphery of the light guide plate LG to the liquid crystal display panel 12 side. As described above, the backlight unit 20 can emit light to the liquid crystal display panel 12 from the entire first main surface S1 of the light guide plate LG and the frame 16 located around the light guide plate LG. Therefore, even when the display surface 12a of the liquid crystal display panel 12 is viewed obliquely, for example, it is possible to prevent a trouble such as a darkening of the peripheral portion of the display area DA. As a result, a liquid crystal display device having a narrower frame than conventional devices can be realized. That is, the outer shape of the backlight unit 20 including the frame 16 can be substantially set to an effective illumination region at three sides other than the side adjacent to the light source unit 30, and the liquid crystal display device 10 having a narrower frame can be realized.

In the first embodiment described above, the frame 16 is formed by a resin sealing material, but the present invention is not limited thereto, and a transparent resin mold frame can be used. In this case, the frame 16 can be used as an auxiliary light source.

Next, an example of a method for manufacturing the backlight unit (backlight device) 20 having the above-described configuration will be described. Fig. 7 is a view schematically showing an example of the manufacturing apparatus and the entire manufacturing process, and fig. 8 to 12 are perspective views each schematically showing a state of a sheet in each manufacturing process.

As shown in fig. 7, the manufacturing apparatus includes: a plurality of rollers RP, RA1, RA2a, RA2b, RS1, RS2, RR around which long pieces of sheet-like material are wound, a pair of first conveying

rollers

80a, 80b that convey the sheet drawn from these rollers along the conveying path CP, a pair of second conveying

rollers

82a, 82b, a recovery roller RC that recovers by winding a separator, a first punching machine P1 that punches holes in the sheet moving the conveying path CP, a second punching machine P2, and the like.

The plurality of rollers include a sheet material for forming a frame, such as a roller RP for winding the PET sheet 50, a roller RA1 for winding the first diffusion bonding layer, rollers RA2a, RA2b for winding the second diffusion bonding layer, respectively, and rollers RS1, RS2 for winding the separator, respectively. In this embodiment, as the first diffusion bonding layer and the second diffusion bonding layer, only a diffusion bonding layer is used, or a substrate + an adhesive is used. Further, a double-sided tape may be used as the diffusion adhesive layer. In addition, the width of each roller is equal to the size between the short sides of the backlight unit. Only roller RA2b has a slightly smaller width than the other rollers.

As shown in fig. 7, first, the sheet materials, for example, the PET sheet 50, the first diffusion adhesive layer 24a, the second diffusion adhesive layer 24b1, the second adhesive layer 24b2, and the separator drawn out from the rollers RP, RA1, RA2a, RA2b, RS1, and RS2 are conveyed between the pair of conveying

rollers

80a and 80b, and are laminated and adhered to each other. That is, as shown in fig. 8 and 9, the first diffusion adhesive layer 24a is adhered to the entire lower surface (first surface) of the PET sheet 50. Further, the second pressure-sensitive adhesive layer 24b1 was adhered to the entire upper surface (second surface) of the PET sheet 50, and the second diffusion pressure-sensitive adhesive layer 24b2 was adhered to a region other than the region along the predetermined region of the one side portion. The first diffusion adhesive layer 24a and the second diffusion adhesive layer 24b2 cover the surface opposite to the surface adhered to the PET sheet 50 with a separator.

Next, as shown in fig. 7 and 10, the first diffusion adhesive layer 24a, the sheet material 50, the second diffusion adhesive layers 24b1, 24b2, and the spacers are collectively punched by a first punching machine (such as a die) P1, and rectangular

inner holes

52a, 52b corresponding to the inner shape (inner hole) of the frame are formed in this order. Next, the separator on the first diffusion adhesive layer 24a is peeled off and wound and recovered by a recovery roll RC. In this state, as shown in fig. 7 and 11, the reflection sheet RE drawn out from the roller RR is adhered to the entire surface of the first diffusion adhesive layer 24 a. The sheet 50, the diffusion adhesive layer, and the reflective sheet RE pass between a pair of conveying

rollers

82a and 82b, and are conveyed along a conveying path CP.

Thereafter, as shown in fig. 7 and 12, the first diffusion adhesive layer 24a, the sheet material 50, the second diffusion adhesive layers 24b1, 24b2, and the spacers and the reflection sheet RE on the second diffusion adhesive layer 24b2 are collectively punched by a second punching machine (such as a die) P2, and the frame 16, the reflection sheet RE, and the diffusion adhesive layers 24b1 and 24b2 are formed in a single piece. Thus, the frame 16 provided with the reflective sheet RE and the diffusion adhesive layers 24b1 and 24b2 was sequentially produced. Next, as shown in fig. 7, the light guide plate LG, the optical sheet OS, and the light source unit 30 are attached and fixed to the formed frame 16, thereby obtaining the backlight unit 20. Further, the light guide plate LG, the optical sheet OS, and the light source unit 30 may be bonded to each other in advance by a diffusion adhesive layer such as a double-sided tape to be unitized.

According to the present embodiment, the frame 16 of the backlight is formed by punching a thin sheet having a thickness of 0.4mm (400 μm) or less, for example, 0.15mm to 0.25mm (150 μm to 255 μm). This makes it possible to obtain a thin frame 16 having a small side width, which is difficult to manufacture in a mold by injection molding. By using this frame 16, a thinner backlight device and a liquid crystal display device with a narrow bezel can be realized at low cost. For example, the thickness of the frame 16 can be set to 0.2mm or less, and the width of the side portion can be set to 0.45mm or less, so that a thin and narrow bezel can be easily realized. Further, by making the frame 16 thin, an extremely thin light guide plate having a plate thickness of 0.2mm or less can be used, and a thinner backlight device can be obtained.

Further, by punching the sheet, the diffusion

adhesive layers

24a and 24b on the sheet, and the reflection sheet RE together with the frame 16, the width of the diffusion

adhesive layers

24a and 24b and the outer dimension of the reflection sheet RE can be made to coincide with the frame 16 with high accuracy.

As comparative examples, the following constitutions are discussed: the frame is first formed from the monomer and then the diffusion bond layer is adhered or applied to the frame. In the case of the comparative example, if the width of each side portion of the frame is significantly narrowed, it is difficult to provide the diffusion adhesive layer on the upper and lower surfaces of each side portion, and the diffusion adhesive layer protrudes from each side portion. The adhesive thus protruded not only adversely affects the subsequent process but also causes a reduction in the light emission performance of the backlight device when attached to another structure of the backlight device. In contrast, in the backlight device of the present embodiment, the widths of the diffusion

adhesive layers

24a and 24b are equal to the width of the side portions of the frame 16, and the side surfaces (side edges) of the diffusion

adhesive layers

24a and 24b are flush with the side surfaces (side edges) of the frame 16. As a result, in the present embodiment, the dimensional accuracy of the backlight device can be improved. The sheet 50, the diffusion

adhesive layers

24a and 24b, and the reflective sheet RE are integrated by a so-called roll-to-roll process, and then perforated together. By this process, simplification of the manufacturing process and mass production are achieved. In addition, the accuracy of the respective members is improved, and moreover, the tolerance between the respective members required when they are formed separately is reduced. As a result, the present embodiment can contribute to thinning and frame narrowing.

Next, a liquid crystal display device and a backlight device according to another embodiment or modification will be described. In other embodiments and modifications described below, the same portions as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted or simplified, with portions different from those of the first embodiment being mainly described.

(second embodiment)

Fig. 13 is a cross-sectional view of the liquid crystal display device of the second embodiment, and fig. 14 is a longitudinal sectional view of the liquid crystal display device of the second embodiment.

As shown in fig. 13 and 14, according to the present embodiment, in the liquid crystal display device 10, the optical sheet OS of the backlight unit 20 is adhered to the second surface SF2 of the frame 16 via the second diffusion adhesive layer 24 b. The optical sheet OS is opposed to the light guide plate LG with a gap. The optical sheet OS includes a diffusion sheet OS1 adhered to the upper surface SF2 of the frame 16 via the second diffusion adhesive layer 24b, and a prism sheet OS2 disposed to overlap the diffusion sheet OS 1. The prism sheet OS2 is in contact with the polarizing plate PL2 of the liquid crystal display panel 12, that is, in surface contact with the entire surface of the polarizing plate PL 2. In addition, the polarizing plate PL2 is adhered to the back surface of the second substrate SUB2 by the diffusion adhesive layer 40 containing beads.

The outer side surfaces of the frame 16 and the diffusion sheet OS and prism sheet OS2 are flush with the left and

right side portions

16a, 16b and the upper side portion 16c of the frame 16. In the three

side portions

16a, 16b, and 16c, the outer side surfaces are aligned on the same plane as the side surface of the polarizing plate PL2 of the liquid crystal display panel 12 and the side surfaces of the first and second insulating substrates SUB1 and SUB 2. The width W1 of the left and

right side portions

16a, 16b and the width W2 of the upper side portion 16c are respectively equal to the width of the frame region ED of the liquid crystal display panel 12. Thus, the three

side portions

16a, 16b, and 16c overlap the frame region ED of the liquid crystal display panel 12 in a plan view.

In addition, the irregularities of the diffusion sheet OS1 are filled in by the second diffusion adhesive layer 24b, and the difference in refractive index is reduced at the interface between the diffusion sheet OS1 and the second diffusion adhesive layer 24b, thereby reducing light diffusion at the interface. However, the light from the frame 16 can be favorably emitted toward the optical sheet OS by the light diffusibility of the second diffusion adhesive layer 24 b.

According to the second embodiment configured as above, it is not necessary to consider the tolerance between the frame and the optical sheet. As a result, the frame 16 functioning as a light source can be disposed further inside the liquid crystal display panel 12, that is, at a position closer to the effective display area DA than in the first embodiment. This can further narrow the frame of the liquid crystal display device. Even when the diffusion sheet and the prism sheet are integrated with the polarizing plate PL2 of the liquid crystal display panel 12, the diffusion function is maintained by the diffusion adhesive layer 40 between the polarizing plate PL2 and the second insulating substrate SUB2 of the liquid crystal display panel 12, so that the reduction in the diffusion function of the diffusion sheet OS1 is cancelled out, and display unevenness when viewed from the cover panel 14 side can be reduced. The diffusion adhesive layer 40 is set to a size not protruding from the polarizing plate PL2, thereby preventing unwanted light from being rewound. In the second embodiment, the same operational effects as those of the first embodiment can be obtained.

(third embodiment)

Fig. 15 is a cross-sectional view of the liquid crystal display device of the third embodiment, and fig. 16 is a longitudinal sectional view of the liquid crystal display device of the third embodiment.

As shown in fig. 15 and 16, according to the present embodiment, the frame 16 functioning as a light source is disposed further inward than the liquid crystal display panel 12, that is, deeper toward the effective display area DA. The pair of

long side portions

16a and 16b of the frame 16 and the short side portion 16c on the opposite side of the light source unit 30 are located at positions overlapping with a frame region (non-display region) ED of the liquid crystal display panel 12 in the thickness direction of the liquid crystal display panel 12, and at least a part of the inner edge portion, here, facing the light guide plate LG is located at a position overlapping with the effective display region DA.

In the third embodiment, the other configurations of the liquid crystal display device 10 are the same as those of the liquid crystal display device 10 of the second embodiment described above.

According to the third embodiment configured as described above, by using the frame 16 functioning as a light source, the frame 16 can be disposed inside the position overlapping the effective display area DA with respect to the liquid crystal display panel 12. This can further narrow the frame of the liquid crystal display device. Further, since the frame 16 and the effective display area DA may be provided so as to overlap each other, the backlight unit 20 can be allowed to be attached to the liquid crystal display panel 12 to some extent when the liquid crystal display device is manufactured. This can improve the combination type and manufacturability of the liquid crystal display device. In the third embodiment, the same operational effects as those of the first embodiment can be obtained.

(fourth embodiment)

Fig. 17 is a cross-sectional view of a liquid crystal display device of a fourth embodiment, and fig. 18 is a longitudinal sectional view of the liquid crystal display device of the fourth embodiment.

As shown in fig. 17 and 18, according to the present embodiment, the reflection sheet RE of the backlight unit 20 has a plurality of extension end portions REE extending outward from the outer peripheral edge of the frame 16. The extended end portion REE is bent toward the cover panel 14 side and is adhered to the outer surface of the frame 16 and the outer surface of the liquid crystal display panel 12. In the present embodiment, the outer surface of the frame 16, the outer surfaces of the first and second diffusion

adhesive layers

24a and 24b, and the outer surface of the liquid crystal display panel 12 are covered with the extended end portions of the reflective sheet RE in the pair of

long side portions

16a and 16b and the short side portion 16c of the frame 16. Accordingly, light leaking from the outer surface of the frame 16, the side surfaces of the first and second diffusion

adhesive layers

24a and 24b, and the side surfaces of the optical sheet OS is reflected by the extended end REE of the reflection sheet RE, returns into the frame 16 and the first and second diffusion

adhesive layers

24a and 24b, and can be irradiated to the liquid crystal display panel 12 side. This can improve the light utilization efficiency of the backlight unit 20.

In the fourth embodiment, the other configurations of the liquid crystal display device 10 are the same as those of the second embodiment or the third embodiment.

(fifth embodiment)

Fig. 19 is a perspective view showing a liquid crystal display device of a fifth embodiment, and fig. 20 is a sectional view of the liquid crystal display device taken along line C-C of fig. 19.

Since the liquid crystal display device of the present embodiment is extremely thin, at least a part of the liquid crystal display device can be bent in the out-of-plane direction. As shown in fig. 19 and 20, in the fifth embodiment, both end portions on the long side of the liquid crystal display device 10 are formed as bent portions CA bent downward, that is, toward the backlight device 20.

In one example, both end portions on the long side of the cover panel 14 are formed by bending in advance toward the backlight 20. The liquid crystal display panel 12 including the polarizing plates PL1 and PL2 is adhered to the cover panel 14 by an adhesive sheet AD made of an optically transparent resin. Thereby, both end portions on the long side of the liquid crystal display panel 12 are bent along the cover panel 14. In the present embodiment, both ends of the liquid crystal display panel 12 on the long side extend to positions flush with both end edges of the cover panel 14 on the long side. The degree of curvature of the curved portion CA, for example, the radius of curvature, can be arbitrarily adjusted.

In the backlight unit 20, an optical sheet (diffusion sheet) OS1 is placed on the light guide plate LG and is disposed inside the frame 16. The optical sheet (prism sheet) OS2 is placed on the optical sheet OS1, and the peripheral edge portion of the optical sheet OS2 is adhered to the second surface SF2 of the frame 16 via the second diffusion adhesive layer 24 b. In the present embodiment, the optical sheet OS2 is formed to have a size slightly smaller than the outer size of the frame 16. Thus, the long-side edge of the optical sheet OS2 is positioned inside the outer edges of the long-

side portions

16a and 16b of the frame 16.

The backlight unit 20 is disposed opposite to the flat portion of the liquid crystal display panel 12. The light guide plate LG and the optical sheet OS1 face the display region DA of the liquid crystal display panel 12. The peripheral edge of the optical sheet OS2, i.e., the portion overlapping the frame 16, was adhered to the polarizing plate PL2 via the transparent diffusion adhesive layer 40. Thereby, the backlight unit 20 is adhered to the liquid crystal display panel 12. The diffusion adhesive layer 40 contains microbeads and has light diffusion properties. In the polarizing plate PL2, the diffusion adhesive layer 40 is provided on the surface of the polarizing plate PL2 from a position facing the frame 16 to a position facing the inner edge of the sheet SE.

The curved portions CA of the cover panel 14 and the liquid crystal display panel 12 extend outward beyond both side edges on the long side of the frame 16, cover the outer side surface 16f of the frame 16, and diagonally face the outer side surface 16 f. In addition, the backlight unit 20 is formed in a flat plate shape, and does not protrude to the bent portion CA. In this state, the outer side surface of the frame 16 is opposed to the bent portion CA by mounting the backlight unit 20.

According to the fifth embodiment configured as described above, by bending both end portions on the long side of the liquid crystal display panel 12 to form the bent portions CA, it is possible to diversify the panel design and expand the range of use of the liquid crystal display device. In addition, by extending both side edge portions of the liquid crystal display panel 12 beyond the frame 16 to the side edge of the cover panel 14, the effective display area DA of the liquid crystal display panel 12 can be enlarged to the area DA 2. That is, according to the present embodiment, since the frame 16 positioned around the light guide plate LG can function as an auxiliary light source portion for irradiating light to the liquid crystal display panel 12 side, light can be irradiated from the frame 16 to the display region DA2 positioned outside the light guide plate LG. Therefore, an image can be displayed using the display area DA2 as an effective display area. In this way, the outside of the backlight unit 20 including the frame 16 can be substantially set as an effective illumination region at both side edge portions on the long side of the liquid crystal display panel 12, and the liquid crystal display device 10 having a narrower peripheral edge can be realized.

In the fifth embodiment, the same operational effects as those of the first embodiment can be obtained. In the fifth embodiment, the bending portion is not limited to both side portions on the long side, and the entire liquid crystal display device may be bent.

(first modification)

Fig. 21 is a sectional view showing a part of a liquid crystal display device of a first modification.

In the fifth embodiment, the frame 16 may be formed to have a wide width, and a part of the frame 16 may be bent along the liquid crystal display panel 12.

As shown in fig. 21, in the first modification, the

long side portions

16a and 16b of the frame 16 are formed to be wide, and extend from the vicinity of the side surface of the light guide plate LG to the vicinity of the inner edge of the sheet SE of the liquid crystal display panel 12. The end of the reflective sheet RE is adhered to the lower surface SF1 of the frame 16 through the first diffusion adhesive layer 24a, covering the lower surface SF1 of the frame 16. An end of the optical sheet (prism sheet) OS2 is adhered to the upper surface SF2 of the frame 16 through the second diffusion adhesive layer 24b, covering the upper surface SF2 of the frame 16. In this modification, the side surfaces of the reflective sheet RE, the optical sheet OS2, and the outer side surface of the frame 16 are flush with each other.

The peripheral edge portions of the frame 16 and the optical sheet OS2 are adhered to the polarizing plate PL2 of the liquid crystal display panel 12 via the light-diffusing adhesive layer 40. Thus, the frame 16, the peripheral edge of the reflection sheet RE, and the peripheral edge of the optical sheet OS2 are bent along the liquid crystal display panel 12, and face the bent portion CA and the display area DA2 of the liquid crystal display panel 12. According to the first modification, the frame 16 functioning as an auxiliary light source is provided in the entire region of the curved portion CA and the display region DA2, and thus more light can be emitted to the display region DA 2. In this case, the frame 16 functions as an auxiliary light source, and thus the frame of the liquid crystal display device is not prevented from being narrowed. Further, it is found that the display area DA2 is slightly lower in luminance than the display area DA by being irradiated with light from the auxiliary light source. On the other hand, the display area DA2 formed by the curved portion CA is used for the auxiliary use of the sub-window when the display area DA is used as the main window. When the display area DA2 is used as such an auxiliary application, it can be effectively used even in a state of lower luminance than the display area DA.

(second modification)

Fig. 22 is a sectional view showing a part of a liquid crystal display device of a second modification.

In the present modification, only the peripheral edge portion of the optical sheet OS2 extends to the vicinity of the sheet SE of the liquid crystal display panel 12, and is adhered to the polarizing plate PL2 by the diffusion adhesive layer 40. The peripheral edges of the

long side portions

16a and 16b of the frame 16, the first diffusion adhesive layer 24a, the second diffusion adhesive layer 24b, and the reflection sheet RE are formed to be slightly shorter than the optical sheet OS2 and extend to the vicinity of the sheet SE.

In this configuration, the light emitted from the frame 16 is diffused by the optical sheet OS2 and the diffusion adhesive layer 40, and can be irradiated to the entire display area DA 2. In addition, since the width of the backlight unit 20 can be reduced, it contributes to miniaturization of the entire liquid crystal display device.

While several embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel methods and systems described herein may be embodied in other specific forms and may be variously omitted, replaced, or modified without departing from the spirit of the invention. These embodiments and modifications are included in the scope and spirit of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

It is also within the scope of the present invention that all structures and manufacturing processes that can be implemented by those skilled in the art by appropriately designing and modifying based on the various structures and manufacturing processes described above as embodiments of the present invention include the gist of the present invention. For example, it is possible to adopt a configuration in which the liquid crystal display panel is accommodated in the accommodating case of the backlight unit without first being mounted on the cover panel, and then the cover panel is mounted together with the peripheral edge of the accommodating case. Further, the liquid crystal display panel may be configured to be slightly movable in the housing case without being bonded to the cover panel. Further, it is also possible to adopt a configuration in which the backlight unit is fixed to the liquid crystal display panel, and the backlight unit and the liquid crystal display panel fixed to each other are accommodated in the accommodating case.

It is to be understood that the other operational effects obtained by the above-described embodiments are apparent from the description of the present specification or are easily conceivable by those skilled in the art.

The optical sheets of the backlight unit are not limited to two sheets, and can be increased or decreased as needed. The outer shape and the inner shape of the liquid crystal display panel, the constituent members of the backlight unit, and the frame are not limited to a rectangular shape, and one or both of the outer shape and the inner diameter may be other shapes such as a polygonal shape, a circular shape, an elliptical shape, and a shape obtained by combining these shapes in a plan view. The material of the constituent members is not limited to the above examples, and various choices can be made.

Claims

1. A backlight device, comprising:

a frame-shaped frame formed of a transparent resin and through which light passes;

a first diffusion adhesive layer provided on the first surface of the frame and having light diffusibility;

a second diffusion adhesive layer provided on a second surface of the frame opposite to the first surface and having light diffusibility;

a reflective sheet adhered to the frame by the first diffusion adhesive layer;

a light guide plate placed on the reflective sheet in the frame; and

a light source disposed in the frame and emitting light to the light guide plate;

wherein the first diffusive adhesive layer has a higher light diffusivity than the second diffusive adhesive layer.

2. The backlight device according to claim 1,

the backlight device further includes an optical sheet disposed on the light guide plate within the frame.

3. The backlight device according to claim 1,

the backlight device further comprises an optical sheet,

the optical sheet is adhered to the frame through the second diffusion adhesive layer and is opposite to the light guide plate.

4. The backlight according to any one of claims 1 to 3,

the first diffusion adhesive layer and the second diffusion adhesive layer are formed to include a binder and microbeads which have a different refractive index from the binder and are dispersed in the binder.

5. The backlight device according to claim 1,

the frame is formed by a transparent resin sheet, the frame has a width corresponding to the width of the first diffusion adhesive layer in at least a part of the frame, and at least the outer side face of the frame is aligned flush with the outer side face of the first diffusion adhesive layer.

6. The backlight device according to claim 5,

in at least a portion of the frame, a side surface of the reflective sheet is aligned flush with an outer side surface of the first diffusion adhesive layer and an outer side surface of the frame.

7. The backlight device according to claim 5 or 6,

the thickness of the frame is less than 0.4 mm.

8. The backlight device according to claim 1,

the frame has at least four sides including a first side adjacent to the light source and a second side opposite the first side,

the first diffusion adhesive layer provided on the second side portion has a higher diffusivity than the first diffusion adhesive layer provided on the other side portion.

9. The backlight device according to claim 1,

the reflection sheet has an extended end portion covering an outer side surface of the frame, and an outer side surface of the first diffusion adhesive layer and an outer side surface of the second diffusion adhesive layer.

10. A liquid crystal display device comprising:

a liquid crystal display panel; and

the backlight device according to claim 1, which is disposed opposite to the liquid crystal display panel.

11. The liquid crystal display device according to claim 10,

the frame is adhered to the liquid crystal display panel through the second diffusion adhesive layer, and the backlight device includes an optical sheet disposed on the light guide plate within the frame.

12. The liquid crystal display device according to claim 10,

the backlight device includes an optical sheet adhered to the frame via the second diffusion adhesive layer,

the optical sheet abuts against the liquid crystal display panel.

13. The liquid crystal display device according to any one of claims 10 to 12,

the liquid crystal display panel has a display area and a non-display area located around the display area,

the frame is located at a position overlapping with the non-display region in a thickness direction of the liquid crystal display panel, and at least a part of the frame is located at a position overlapping with the display region.

14. The liquid crystal display device according to any one of claims 10 to 12,

the first diffusion bonding layer is formed by a binder and microbeads which have a different refractive index from the binder and are dispersed in the binder.

15. The liquid crystal display device according to claim 14,

the second diffusion bonding layer is formed by a binder and microbeads which have a different refractive index from the binder and are dispersed in the binder,

the first diffusive adhesive layer has a higher light diffusivity than the second diffusive adhesive layer.

16. The liquid crystal display device according to any one of claims 10 to 12,

17. The liquid crystal display device according to any one of claims 10 to 12,

the liquid crystal display panel has a curved portion at least a part of which is curved toward the backlight device side.

18. The liquid crystal display device according to claim 17,

the liquid crystal display panel has a pair of long sides opposite to each other and a pair of short sides opposite to each other,

a bent portion bent toward the backlight device is formed at a side edge portion on the long side of the liquid crystal display panel,

the frame has a long side portion opposite to the bent portion.

19. The liquid crystal display device according to claim 18,

the long side portion of the frame is adhered to the bent portion via the diffusion adhesive layer with the optical sheet interposed therebetween, and is bent along the bent portion.