Liquid crystal display device having a joint portion of a wiring substrate extending from an inside to an outside of the case

According to one embodiment, a liquid crystal display device includes a liquid crystal panel and a backlight device. The backlight device includes a case with a bottom plate and a side plate, a light guide on the bottom plate, and a light source device. The light source device includes a wiring substrate and a light-emitting element on the wiring substrate. The wiring substrate includes a mounting portion on which the light-emitting element is mounted, a connection wiring portion on a back surface side of the bottom plate, and a joint portion which joints the mounting portion and the connection wiring portion together. The joint portion extends from an inside to an outside of the case through a gap between the side plate of the case and the liquid crystal panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Applications No. 2017-086614, filed Apr. 25, 2017; and No. 2018-077772, filed Apr. 13, 2018, the entire contents of all of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystal display device.

BACKGROUND

In recent years, liquid crystal display devices are widely used as a display device of smartphones, tablet computers, vehicle-navigation systems, etc. In general, a liquid crystal display device comprises a liquid crystal display panel and a backlight unit overlaid on the rear surface of the liquid crystal display panel to illuminates the liquid crystal panel. The backlight unit includes a reflective layer, a light guide, an optical sheet, a light source unit, a case (bezel) in which these members are accommodated, etc. The light source unit includes a wiring substrate and a plurality of light sources, for example, light-emitting diodes (LEDs) mounted on the wiring substrate.

The wiring substrate of the light source unit is bent to a back side of the case and is electrically connected to a relay printed circuit board. Here, in some cases, the wiring substrate is electrically and mechanically jointed to the relay printed circuit board using solder. However, when jointed with solder, the soldered portion forms relatively tall solder bumps. These solder bumps can be an obstacle in thinning the back light device and the liquid crystal device.

SUMMARY

The present application generally relates to a liquid crystal display device.

According to one embodiment, a liquid crystal display device includes a liquid crystal panel and a backlight device. The backlight device includes a case with a bottom plate and a side plate, a light guide on the bottom plate, and a light source device. The light source device includes a wiring substrate and a light-emitting element on the wiring substrate. The wiring substrate includes a mounting portion on which the light-emitting element is mounted, a connection wiring portion on a back surface side of the bottom plate, and a joint portion which joints the mounting portion and the connection wiring portion together. The joint portion extends from an inside to an outside of the case through a gap between the side plate of the case and the liquid crystal panel.

DETAILED DESCRIPTION

Various embodiments will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment, a liquid crystal display device comprises a liquid crystal panel comprising a first substrate, a second substrate opposed to the first substrate, and a liquid crystal layer between the first substrate and the second substrate; and a backlight device opposed to the first substrate. The backlight device comprises a case comprising a bottom plate and a side plate standing along a side edge of the bottom plate; a light guide on the bottom plate, comprising an emission surface and an incident surface extending to cross the emission surface; and a light source device which illuminate light to enter the incident surface of the light guide. The light source device comprises a wiring substrate including a plurality of wiring lines and a light-emitting element on the wiring substrate, the light emitting element comprising a light-emitting surface opposing the incident surface of the light guide and a mounting surface mounted on the wiring substrate. The wiring substrate comprises a mounting portion on which the light-emitting element is mounted, which opposes the incident surface with interposing the light emitting element therebetween, a connection wiring portion on a back surface side of the bottom plate, and a joint portion which joints the mounting portion and the connection wiring portion together, integrated as one body. The joint portion extends from an inside to an outside of the case through a gap between the side plate of the case and the liquid crystal panel.

Note that the disclosure is presented for the sake of exemplification, and any modification or variation conceived within the scope and spirit of the embodiments by a person having ordinary skill in the art is naturally encompassed in the scope of embodiment of the present application. Moreover, since a drawing describes more clearly, it may be typically expressed about the width of each part, thickness, form, etc., compared with an actual mode, but is an example to the last and does not limit the interpretation of the present invention. Besides, in the specification and drawings, the same elements as those described in connection with preceding drawings are denoted by like reference signs, and a detailed description thereof is omitted unless otherwise necessary.

Embodiment

FIGS. 1 and 2are perspective views showing the display surface and back side of a liquid crystal display according to an embodiment, respectively.FIG. 3is a perspective view showing the back side of the liquid crystal display in the state where a main FPC in which the driver IC is mounted is folded on the back side, andFIG. 4is an exploded perspective view of the liquid crystal display.

The liquid crystal display10can be built in to be used in various kinds of electronic devices, for example, such as a smart phone, a tablet device, a cellular phone, notebook type PC, a handheld game machine, an electronic dictionary, a television device, and a car-navigation system.

As shown inFIGS. 1, 2 and 4, the liquid crystal display10comprises a liquid crystal panel12of an active-matrix shaped plate, a transparent cover panel14stacked on a display surface12a, which is one flat surface of the liquid crystal panel12and covering the entire display surface12a, and a backlight unit20as a backlight device, disposed to oppose the back surface, which is the other side of the liquid crystal panel12.

The liquid crystal panel12comprises a rectangular plate-shaped first substrate SUB, a rectangular plate-shaped second substrate SUB2disposed to oppose the first substrate SUB1, and a liquid crystal layer LQ held between the first substrate SUB1and the second substrate SUB2. A peripheral portion of the second substrate SUB2is adhered to the first substrate SUB1with a sealing material SE. A polarizer PL2is attached to a surface of the second substrate SUB2, thus forming the display surface12aof the liquid crystal panel12. A polarizer PL1is attached to a surface of the second substrate SUB2(a back surface of the liquid crystal panel12).

In the liquid crystal panel12, a rectangular display area (active area) DA is provided in a region located on an inner side of the sealing material in plan view (, which is a state where the liquid crystal panel is viewed from a normal direction of the display surface of the liquid crystal panel, to be referred to similarly hereinafter), to display images thereon. A rectangular frame area ED is provided around the display area DA. The liquid crystal panel12is a transmissive liquid crystal panel comprising a transmissive display function of displaying images by selectively transmitting or modulating the light from the backlight unit20to the display area DA. The liquid crystal panel12may have a structure provided for the lateral electric field mode which mainly utilizes a lateral electric field along a surface of the substrate, or a structure provided for the vertical electric field mode which mainly utilizes a vertical electric field crossing the main surface of the substrate.

In the example illustrated, a flexible printed circuit board FPC (main FPC)23is joined to a short side end of the first substrate SUB1and extends from the liquid crystal panel12outward. As a signal supply source which supplies a signal required to drive the liquid crystal panel12to the main FPC23, semiconductor devices of the driver IC24and the like are mounted (the structure in which the driver IC is mounted on the FPC may be referred to as a chip-on flexible printed circuit called (COF)). A sub-FPC25is joined to an extending end of the main FPC23. On the sub-FPC25, a capacitor C1, connectors26and27and the like are mounted. As shown inFIG. 3, the main FPC23and the sub-FPC25are folded back along the short-side end edge of the first substrate SUB1, and disposed on a bottom plate of the back light unit20. As will be described later, the main FPC23and the sub-FPC25are adhered to a bottom plate of the backlight unit20with an adhesive member such as a double-sided tape.

As shown inFIGS. 1 and 4, the cover panel14is formed, for example, into a rectangular plate shape from a glass plate or an acrylic transparent resin. A frame-shaped light-shielding layer RS is formed on a lower surface (a back surface, a surface on a liquid crystal panel side) of the cover panel14. In the cover panel14, a region other than the region which opposes the display area DA of the liquid crystal panel12is shielded by the light-shielding layer RS. The light-shielding layer RS may be formed on the upper surface (outer surface) of the cover panel14. Note that the cover panel14may be omitted according to the use status of the liquid crystal display device10.

The back light unit20comprises the flat rectangular case22, an optical member and a light source unit50, arranged in the case22. The backlight unit20is attached to the back surface of the liquid crystal panel12, which is, for example, the polarizer PL1with a frame-shaped adhesive member, for example, a double-sided tape TP1.

As shown inFIG. 4, the non-display area ED of the liquid crystal panel12comprises sides having the same or substantially the same width. More specifically, widths WL1and WL2of the non-display area ED, which correspond to a pair of long sides of the display area DA, are equal to each other (WL1=WL2). Here, the widths WL1and WL2specifically indicates the dimension taken from the boundary between the display area DA and the non-display area ED to an outer edge of the first substrate SUB1(and the second substrate SUB2) in the long sides of the display area DA. Moreover, of a pair of short sides of the display area DA, a width of the non-display area ED on a side where the flexible printed circuit substrate23is provided (, which is also referred to as a mounting side, hereinafter) is defined as WS1and a width of the non-display area ED on a short side opposite thereto is defined as WS2, it is preferable to satisfy that WS2≤WS1and WS1/WS2≤2.0, more preferably, WS1/WS2≤1.5, and further preferably, WS1/WS2≤1.0, when adopted. Here, the width WS1of the non-display indicates the dimension taken from the boundary between the display area DA and the non-display area ED to the outer edge of the second substrate SUB2in the short sides on the mounting side of the display area DA. The width WS2of the indicates the dimension from the boundary between the display area DA and the non-display area ED to the outer edge of the first substrate SUB1(and the second substrate SUB2) in the short side opposite to the mounting side of the display side.

Moreover, in any of these structures, it is preferable to satisfy that WL1=WL2<1.5 mm and WS2<1.5 mm, and more preferably, WL1=WL2<1.0 mm and WS2<1.0 mm. Furthermore, in any of these structures, it is possible to adopt that WL1=WL2=WS2.

With the above-described structures adopted, this embodiment can achieve such a structures that the width WS1of the mounting side of the liquid crystal panel12can be remarkably narrowed more than the conventional technique, i.e., the width WS1of the non-display area on the mounting side is substantially equal to that of the other regions of the non-display area ED.

Next, the backlight unit20will be described in more detail. In particular, the structure of the light-source side portion of the backlight unit will be described in more detail.

FIG. 5is an exploded perspective view of the backlight unit20, andFIG. 6is a perspective view of the light source unit, including a partially enlarged perspective view.FIG. 7is a cross section of a wiring substrate.FIG. 8is a cross section of the light source unit-side of the liquid crystal display, taken along line A-A ofFIG. 3.

As shown inFIG. 5, the backlight unit20comprises a flat rectangular-shaped case (bezel)22, a plurality of optical members arranged in the case22, and the light source unit50which supplies light entering the optical members.

The case22is formed, for example, by subjecting a 0.1 mm-thick stainless plate member to bending process, press molding or the like, into a flat rectangle lid-shape (or a box shape with a top being open). The case22comprises a rectangular bottom plate16, a pair of long-side plates18a, and a pair of short-side plates18b, which are built to stand from the respective side edges of the bottom plate16. The long-side plates18aare built to stand substantially perpendicular to the bottom plate16, and extend over the full length of the long sides of the bottom plate16. The short-side plates18bare built to stand substantially perpendicular to the bottom plate16to the bottom plate16, and extend over the full length of the short sides of the bottom plate16. The height of these side plates18aand18bfrom the bottom16plate is, for example, about 1 mm.

As shown inFIGS. 5 and 8, in this embodiment, the end portion of the bottom plates16, which opposes the light source unit50is formed a stepped portion (convex portion)16aone step lower than the other portions. The stepped portion16aslightly projects outwards, that is, toward a direction separating from the light source unit50accommodated in the case22.

The backlight unit20comprises, as an optical member, a first reflective sheet RE, a light guide LG, and a plurality of, for example, a first optical sheet OS1and a second optical sheet OS2, which have rectangular shapes in plan view. According to this embodiment, light-transmissive diffusion sheet and prism sheet, formed from, for example, a synthetic resin such as polyethylene terephthalate are used as the first optical sheet OS1and the second optical sheet OS2. The number of optical sheets is not limited to two, but three or more optical sheets may be used.

The reflective sheet RE is formed to have outer dimensions substantially equal to the inner dimensions of the bottom plate16of the case22. The reflective sheet RE is provided to be laid on the bottom plate16to covers substantially the entire flat section of the bottom plate16. As shown inFIG. 8, the end REa on a light source side of the reflective sheet RE extends to the light source side over the display area DA of the liquid crystal panel12, and is located on a front side with respect to the incident surface EF of the light guide LG A portion of the reflective sheets RE including the end REa is attached to the bottom plate16with a double-stick tape TP6.

As shown inFIGS. 5 and 8, the rectangular light guide LG comprises a first main surface S1serving as an emission surface, a second main surface S2opposing the first main surface S1, a pair of long-side surfaces and a pair of short-side surfaces. In this embodiment, one side surface on a short side of the light guide LG is an incident surface EF. The light guide LG has a thickness of about 0.23 mm to 0.32 mm. Further, the light guide LG is formed from, for example, a resin such as polycarbonate, an acrylic or silicon resin.

The light guide LG is formed to have an outer dimension (length, width) slightly less than the inner diameter of the case22, but slightly greater than the outer dimension of the display area DA of the liquid crystal panel12in plan view. The light guide LG is accommodated in the case22in such a state that a second main surface S2side thereof opposes the reflective sheet RE. Thus, the first main surface (emission surface) S1of the light guide LG is located substantially parallel to the bottom plate16of the case22, and the incident surface EF is located almost perpendicularly to the bottom plate16.

As shown inFIG. 8, the incident surface-side end portion of the light guide LG extends towards the light source side over the display area DA of the liquid crystal panel12. Further, the incident surface-side end portion of the light guide LG extends towards the light source side over the end REa of the reflective sheet RE. Thus, the incident surface EF of the light guide LG is placed to oppose the short-side side plate18bof the case22with a slight gap therebetween. It is preferable that the gap should be 1.0 mm or less, more preferably 0.8 mm or less, and particularly preferably 0.5 mm or less. Conventionally, the gap is about 3.0 mm to 4.0 mm. As compared to this, the gap in this embodiment is remarkably narrow, and the light source unit50is provided in such a narrow gap.

As shown inFIGS. 5 and 6, the light source unit50comprises, for example, a wiring substrate52formed of a flexible printed circuit board (FPC), and a plurality of light sources mounted and arranged on the wiring substrate52. The light sources are, for example, light-emitting elements such as light-emitting diodes (LEDs)54. The wiring substrate52comprises a slender belt-shaped mounting portion (mounting region)52ain which the LEDs54are mounted, a slender belt-shaped connection wiring portion52bdisposed on the back side of the case22and a plurality of bridge portions (joint portions, joint regions)52cwhich couple the mounting portion52aand the connection wiring portion52bto each other, as an integral body. The connection wiring portion52bis aligned parallel with the mounting portion52awith a gap therebetween. For example, three of the bridge portions52care formed, and the bridge portions52care arranged in a longitudinal direction of the mounting portion52aat predetermined intervals. This arrangement can be described as openings51being formed between the three bridge portions52c, respectively. Thus, in this embodiment, the wiring substrate52is formed to include the mounting portion52a, the connection wiring portion52band the bridge portion52c, integrated as one body. More specifically, the embodiment adopts such a structure that a plurality of openings51are formed in the wiring substrate52so that one side of each opening51is used by the mounting portion52aand the other side used by the connection wiring portion52b, and a bridge portion52cis built over these portions.

As shown inFIGS. 6 and 7, the wiring substrate52comprises a first surface (front surface)53aand a second surface (back surface)53bon an opposite side thereto. The wiring substrate52comprises a base layer (insulating layer)56formed from an insulating material such as polyimide, a first conductive layer58aof, for example, a copper foil formed on one surface of the base layer56, a cover layer (cover insulating layer)60astacked on the first conductive layer58a, a second conductive layer58bof, for example, a copper foil formed on the other surface of the base layer56, and a cover layer (cover insulating layer)60bformed to be stacked on the second conductive layers58b. The first conductive layer58a, when patterned, forms a plurality of contact pads62and the like, and a plurality of wiring lines. Similarly, the second conductive layer58a, when patterned, forms a plurality of contact pads and wiring lines.

In this embodiment, a number of contact pads62are formed on the mounting portion52ain the front surface53aof the wiring substrate52. The contact pads62are arranged in the longitudinal direction of the mounting portion52aat predetermined intervals. In the front surface53a, a plurality of wiring lines63are formed partially in the connection wiring portion52band the bridge portions52c. The wiring lines63extend continuously from one longitudinal end side of the connection wiring portion52bto the other end side.

A number of wiring lines64are formed on the mounting portion52aand the bridge portion52cin the back surface53bof the wiring substrate52. The wiring lines64are electrically connected to the corresponding contact pads62and wiring lines63on the front surface53aside, for example, via a plurality of plated through-holes67.

Note that the arrangement and shape of each of the wiring pattern and connection pad pattern in the wiring substrate52are not limited to those of the embodiment described above, but can be changed as needed.

As shown inFIG. 6, a length L of the mounting portion52ais substantially equal to that of the incident surface EF of the light guide LG. Each LED54comprises a substantially rectangular parallelepiped case (package)60formed of a resin, for example. The upper surface of the case60forms the light-emitting surface65, and the bottom surface of the case60, located on an opposite side to the light-emitting surface65, forms a mount surface. On the bottom surface of the case60, connection terminals66are provided (seeFIG. 7). Note that each LED54is formed into substantially a rectangular parallelepiped shape, but the shape is not limited to this. More specifically, the LEDs54may comprise uneven side surfaces or may be formed into a curvy shape.

The LEDs54are each mounted so that the bottom surface thereof meets the front surface53aof the mounting portion52a, and thus the connection terminals66are electrically jointed respectively to the contact pads62. The light-emitting surface65of each LED54is set substantially parallel to the wiring substrate52, and each LED54emits light from the light-emitting surface65in a direction substantially perpendicular to the wiring substrate52.

In this embodiment, the light source unit50contains plural LEDs54depending on the width of the display area DA. For instance, the number of the LEDs is about 2.5 to 3 times as compared to the conventional structure with a display area having the same area. These LEDs54are arranged on the mounting portion52ain one row from one longitudinal end of the mounting portion52ato the other end.

In this embodiment, an arrangement pitch P of the LEDs54is set to about 1.1 to 1.5 times of the length L1of each LED54in the arrangement direction, and an interval D between each adjacent pair of the LEDs54is set to about 10% to 50% of the length L1of each LED54. In this embodiment, the LEDs54are arranged at intervals D less than those of the conventional techniques, and thus the region where non-uniformity in luminance, which may occur between adjacent point light sources, can be narrowed.

The number of the LEDs54may be increased or decreased as needed. When LEDs having a length greater than L1are used, the loading number of LEDs may be decreased.

FIG. 9is an exploded perspective view showing a light source-side portion of the back light unit20. As shown inFIGS. 8 and 9, the light source unit50thus formed is partially located in the case22and partially in an outer surface side of the case22. The mounting portion52aand the LEDs54on the wiring substrate52are disposed between the incident surface EF of the light guide LG and the side plate18bof the case22. The light-emitting surfaces62of the LEDs54oppose or abut against the incident surface ER The mounting portion52aof the wiring substrate52is attached to an inner surface of the side plate18bwith, for example, an adhesive member such as a double-sided tape TP3. The mounting portion52aopposes the incident surface EF via the LEDs54interposed therebetween.

A belt-shaped fixing tape TP2is adhered on the side surface of each of the LEDs54(in the figure, the side surfaces54bopposing to a bottom plate16side of the case22) and the second main surface S2of the light guide LG. The LEDs54are aligned with respect to the light guide LG and fixed there with the fixing tape TP2. The fixing tape TP2is attached on the LEDs54by about half a region thereof along its width direction, and the remaining half is attached on the light guide LG The fixing tape TP2comprises a belt-like base material55aformed from, for example, polyethylene terephthalate (PET) and an adhesives layer55bor a sticky layer, formed on at least one of the surfaces of the base material55a. Further, at least one of the base material55aand the adhesives layer55bis colored in black with, for example, fine black particles, black ink or the like. Thus, the fixing tape TP2forms a light-shielding member with light-shielding properties.

Further, the fixing tape TP2is disposed along the reflective sheet RE in a plane direction of the light guide LG That is, the fixing tape TP2extends to near the light source-side end REa of the reflective sheet RE and is aligned with the reflective sheet RE along its plane direction with a slight gap therebetween. Thus, the fixing tape TP2and the reflective sheet RE are not stacked one another with relation to each other.

According to this embodiment, the fixing tape TP2is formed thicker than the reflective sheet RE, and is placed in the stepped portion16aof the bottom plate16. The fixing tape TP2is provided to abut the inner surface of the bottom plate16. The fixing tape TP2is not limited to one continuous tape, but may be of a plurality of divided fixing tapes.

As shown inFIGS. 8 and 9, on the mounting side, a gap G is defined between the side plate18bof the case22and the end edge of the first substrate SUB1. The bridge portions52cof wiring substrate52extend form the inside to the outside of the case22through the gap G Each bridge portion52cis bent outward along an upper end edge of the side plate18bto extend along the outer surface of the side plate18b. More specifically, each bridge portion52cextends from the inside to the outside of the case22with being turned along the end edge of the side plate18b. The connection wiring portion52bis disposed on the back surface of the bottom plate16of the case22. In this embodiment, a spacer70is interposed between each bridge portion52cand the side plate18b. The spacer70is formed into a belt-shape from a synthetic resin to extend over substantially the full length of the side plate18b(seeFIG. 4). Thus, the spacer70is disposed between the three bridge portions52cand the side plate18b. The spacer70is provided to adjust the longitudinal dimension of the backlight unit20.

The double-sided tape TP3described above is attached on the back surface53bof the wiring substrate52. In this embodiment, the double-sided tape TP3is formed into substantially the same shape and dimensions to those of the wiring substrate52and attached on the entire back surface53b(seeFIG. 5). Thus, the bridge portions52care attached on the upper end edge of the side plate18band the outer surface of the spacer70with the double-sided tape TP3. Further, the connection wiring portion52bis attached on the back surface (outer surface) of the bottom plate16of the case22with the double-sided tape TP3.

The double-sided tape TP3is electrically insulative. Therefore, the double-sided tape TP3does not only attach the wiring substrate52to the case22and the spacer70, but also it ensures the electric insulation between the wiring substrate52and the case22. Further, with the double-sided tape TP3provided between the upper end edge (edge portion) of the side plate18band the wiring substrate52, damage which may be caused by the edge portion to the wiring substrate52can be prevented to protect the wiring substrate52.

As shown inFIG. 8, the wiring substrate52may be structured as well so that the wiring lines (conductive layer) are provided only on the back surface53bside the bridge portions52c(the structure without the first conductive layer and the cover layer). In this case, the thickness of the bridge portions52ccan be set thinner than that of the mounting portion52aand the connection wiring portion52b. Thus, it becomes possible to easily bend the bridge portion52c, and thus to amount and arrange the wiring substrate52. Moreover, in the wiring substrate52of this embodiment, the bridge portions52care bending portions. Here, the bending portions are the openings51except for the bridge portion52c, and therefore the bend stress (elastic restorability) is remarkably low. As a result, it is only natural that the wiring substrate52can be easily bent, and also the bent state can be maintained in an excellent way.

As shown inFIGS. 8 and 9, a short-side end portion of a first optical sheet OS1extends over the incident surface EF of the light guide LG to a position opposing the LEDs54. In this embodiment, the light-shading tape TP4is attached on the end portion of the first optical sheet OS1to oppose the LEDs54. The light source-side end of the second optical sheet OS2projects from the display area DA towards the non-display area ED and is located to overlap the end portion of the first optical sheet OS1and the light-shading tape TP4.

Thus, also in the non-display area ED, the first optical sheet OS1and the second optical sheet OS2of a prism sheet are stacked one on another to oppose the end portion of the light guide LG and the incident surface EF, the light-emitting surfaces65of the LEDs54and the end portion of the light-shading tape TP4. With this arrangement, of the unexpected leaking light, which may easily occur in a space close to this type of light-emitting portions, the light traveling towards the liquid crystal panel12passes through the first optical sheet OS1and the second optical sheet OS2as in the display area AD, thus making it possible to suppress the turbulence of the emitted light of the back light device, especially, in the end portion of the display area (the light-emitting side end).

As shown inFIGS. 4 and 9, the backlight unit20is adhered to the back surface of the liquid crystal panel12with the frame-shaped double-sided tape TP1. The double-sided tape TP1is attached on the peripheral portion of the second optical sheet OS2. In the light source side, the double-sided tape TP1is attached also on the bridge portions52cof the wiring substrate52and the spacer70. Further, on a liquid crystal panel12side, the double-sided tape TP1is adhered to the peripheral portion of the polarizer PL1and the peripheral portion of the first substrate SUB1interposing a spacer72therebetween.

The bridge portions52coppose to the first substrate SUB1through the double-sided tape TP1. More detail, the bridge portions52coppose to the first substrate SUB1via the double-sided tape TP1and the spacer72. The bridge portions52care partially covered with the double-sided tape TP1and protected thereby. By providing the double-sided tape TP1between the bridge portions52cand the first substrate SUB1, the first substrate SUB1and the like do not directly contact the bridge portions52c, when the backlight unit20is attached to the liquid crystal panel12. Thus, frequency in occurrence of inferior devices at the assembling can be lowered.

As shown inFIG. 3, the main FPC23and the sub-FPC25extending from the liquid crystal panel12are folded back to the back surface side of the bottom surface16along the side plate18bof the case22. The main FPC23and the sub-FPC25are attached on the bottom plate16with an adhesion member (not shown). As shown inFIGS. 2 and 3, the connection wiring portion52bof the wiring substrate52includes an extending portion extending in the longitudinal direction of the case22. A connector74provided in the end of the extending portion is connected to the connector27on the sub-FPC25.

According to the liquid crystal display10configured as described above, the wiring substrate52of the light source unit50is a printed circuit board including the mounting portion52aon which the LEDs54are mounted, the connection wiring portion52bprovided on the bottom plate of the case22, and the joint portion (bridge portion)52cwhich connects them as one body. With this structure, the switching between upper and lower wiring lines can be conducted in the wiring substrate52, and the relay wiring substrate for switching the connection is no longer needed. Further, the mounting portion52aand the connection wiring portion52bneed no longer be jointed to each other with solder or the like, and thus the solder joint portion (solder bump) can be removed. As a result, the portion corresponding to the height of the solder bump can be removed, thereby making it possible to slim down the backlight unit20.

Thus, according to this embodiment, a thinner backlight device and the liquid crystal display device with narrowed frame can be provided.

Now, modifications of the liquid crystal display device will be described. Note that in the modifications described below, the same reference symbols are given to the same parts as those of the embodiment described above, and detailed described therefor will be omitted or simplified and items different from those of the first embodiment described above will be mainly explained in detail.

FIG. 10is a cross-section of the light source-side portion of a liquid crystal display device of a first modification. According to the first modification, the spacer70is omitted. In this case, the bridge portions52cof the wiring substrate52are attached on the outer surface of the side plate18bwith the double-sided tape TP3. As described above, the bridge portions52care formed to be comparatively thin as a layer, and can be easily bent along the side plate18b. Further, since the spacer70is omitted, the entire length of the backlight unit20, and the other dimensions can be reduced.

FIG. 11is a cross-section of the light source-side portion of a liquid crystal display device of a first modification. An adhesive member (double-sided tape TP3) to adhere the wiring substrate52may not be provided on the entire surface of the wiring substrate52. According to the second modification, the double-sided tape TP3is provided between the side plate18including the upper end edge portion thereof and the mounting portion52aof the wiring substrate52, and between the connection wiring portion52band the bottom plate16. Here, the double-sided tape between the bridge portion52cand the spacer70is omitted. Also such a structure as well, with the double-sided tape TP3, the electric insulation between the wiring substrate52and the case22can be ensured, and also the wiring substrate52can be protected against the edge portion of the side plate18b.

Note that all the structures which can be carried out by any modification and variation conceived within the scope and spirit of the invention by a person having ordinary skill in the art based on each structural elements described in the embodiments are naturally encompassed in the scope of invention of the present application. Further, regarding the present embodiments, any advantage and effect which would be obvious from the description of the specification or arbitrarily conceived by a skilled person are naturally considered achievable by the present invention.

The outer and inner shapes of the structure members of a liquid crystal panel and a backlight unit are not limited to rectangular, but one or both of the outer and inner shapes may be of some other forms such as polygonal, circular, elliptical or any combination of these in plan view. The liquid crystal panel and backlight unit are not limited to a flat shape, but they may be at least partially or entirely curved. The materials of the structural members are not limited to those listed in the examples, but may be selected from various options.