阅读说明：本技术 照明装置及显示装置 (Illumination device and display device ) 是由 和田猛 大西拓也 于 2018-06-06 设计创作，主要内容包括：本发明的照明装置(12)包括：第一光源单元(U1),其具有由以列状排列的多个光源(17)构成的第一光源列(171)和供形成第一光源列(171)的光源(17)安装且热传导效率相对较低的第一光源基板(181)；第二光源单元(U2),其具有由以列状排列的多个光源(17)构成的第二光源列(172)和供形成第二光源列(172)的光源(17)安装且热传导效率相对较高的第二光源基板(182)；以及板状导光板19,其具有供从形成第一光源列(171)的光源(17)射出的光射入的第一光射入面(19c),和配置在第一光射入面(19c)的相反侧并供从形成第二光源列(172)的光源(17)的射出的光射入的第二光射入面(19d)。(The lighting device (12) of the present invention comprises: a first light source unit (U1) having a first light source array (171) composed of a plurality of light sources (17) arranged in a row, and a first light source substrate (181) on which the light sources (17) forming the first light source array (171) are mounted and which has a relatively low heat conduction efficiency; a second light source unit (U2) having a second light source array (172) formed of a plurality of light sources (17) arranged in a row, and a second light source substrate (182) on which the light sources (17) forming the second light source array (172) are mounted and which has a relatively high heat conduction efficiency; and a plate-shaped light guide plate (19) having a first light incident surface (19c) on which light emitted from the light sources (17) forming the first light source array (171) is incident, and a second light incident surface (19d) which is arranged on the opposite side of the first light incident surface (19c) and on which light emitted from the light sources (17) forming the second light source array (172) is incident.)

1. An illumination device, comprising:

a first light source unit having a first light source row composed of a plurality of light sources arranged in a row, and a first light source substrate on which the light sources forming the first light source row are mounted and which has a relatively low heat conduction efficiency;

a second light source unit having a second light source array including a plurality of light sources arranged in a row, and a second light source substrate on which the light sources forming the second light source array are mounted and which has a relatively high heat transfer efficiency; and

and a plate-shaped light guide plate having a first light incident surface and a second light incident surface, wherein the first light incident surface is formed by an end surface facing the first light source row and receives light emitted from the light sources forming the first light source row, and the second light incident surface is disposed on an opposite side of the first light incident surface and formed by an end surface facing the second light source row and receives light emitted from the light sources forming the second light source row.

2. The lighting device of claim 1,

the first light source substrate has a first wiring portion made of a metal foil electrically connected to the light sources forming the first light source column,

the second light source substrate has a second wiring portion made of a metal foil, electrically connected to the light sources forming the second light source row, and having a thickness greater than that of the first wiring portion.

3. The lighting device of claim 1,

the first light source substrate has a first supporting base material made of a metal-based material,

the second light source substrate has a second support base material made of a metal-based material and having a thickness larger than that of the first support base material.

4. The lighting device of claim 1,

the first light source substrate has a first supporting base material made of a material having a relatively low conductivity,

the second light source substrate has a second support base material made of a material having a relatively high thermal conductivity.

5. The lighting device of claim 1,

the first light source substrate has a first support base material, a first insulating layer formed on the first support base material, and a first wiring portion formed on the first insulating layer, the first wiring portion being made of a metal foil electrically connected to the light sources forming the first light source row,

the second light source substrate has a second supporting base material, a second insulating layer formed on the second supporting base material, having a smaller thickness than the first insulating layer and having a relatively small thermal resistance, and a second wiring portion formed on the second insulating layer and made of a metal foil electrically connected to the light sources forming the second light source row.

6. The lighting device of claim 1,

the first light source substrate and the second light source substrate have the same thickness,

the first light source substrate has a single-layered or multi-layered wiring portion made of a metal foil and electrically connected to the light sources forming the first light source column,

the second light source substrate has a multilayer wiring portion made of a metal foil, electrically connected to the light sources forming the second light source row, and having a larger number of layers than the wiring portion of the first light source substrate.

7. An illumination device, comprising:

a first light source unit having a first light source row including a plurality of light sources arranged in a row and a first light source substrate on which the plurality of light sources forming the first light source row are mounted, and generating a relatively large amount of heat;

a second light source unit having a second light source row including a plurality of light sources arranged in a row and a second light source substrate on which the plurality of light sources forming the second light source row are mounted, and generating relatively less heat; and

and a plate-shaped light guide plate having a first light incident surface and a second light incident surface, wherein the first light incident surface is formed by an end surface facing the first light source row and receives light emitted from the light sources forming the first light source row, and the second light incident surface is disposed on an opposite side of the first light incident surface and formed by an end surface facing the second light source row and receives light emitted from the light sources forming the second light source row.

8. The lighting device of claim 7,

the number of the light sources constituting the second light source column is smaller than the number of the light sources constituting the first light source column.

9. The lighting device of claim 7,

the supply current to the light sources constituting the second light source column is smaller than the supply current to the light sources constituting the first light source column.

10. An illumination device, comprising:

a first light source unit having a first light source row including a plurality of light sources arranged in a row and a first light source substrate on which the plurality of light sources forming the first light source row are mounted, the heat dissipation being relatively low;

a second light source unit having a second light source row including a plurality of light sources arranged in a row and a second light source substrate on which the plurality of light sources forming the second light source row are mounted, the second light source unit having a relatively high heat dissipation property; and

and a plate-shaped light guide plate having a first light incident surface and a second light incident surface, wherein the first light incident surface is formed by an end surface facing the first light source row and receives light emitted from the plurality of light sources forming the first light source row, and the second light incident surface is disposed on an opposite side of the first light incident surface and formed by an end surface facing the second light source row and receives light emitted from the light sources forming the second light source row.

11. The lighting device of claim 10,

the first light source unit has a first heat dissipation member holding the first light source substrate,

the second light source unit has a second heat dissipation member that holds the second light source substrate and has a larger outer shape and/or thickness than the first heat dissipation member.

12. The lighting device of claim 10,

the first light source unit has a first double-sided adhesive member having relatively low thermal conductivity for attaching the first light source substrate to a radiator,

the second light source unit has a second double-sided adhesive member having relatively high thermal conductivity for attaching the second light source substrate to a radiator.

13. A lighting device as recited in any one of claims 1-12,

the light guide plate is used in a standing state such that the second light source unit is disposed on the upper side and the first light source unit is disposed on the lower side.

14. A display device, comprising:

the lighting device of any one of claims 1 to 13; and

and a display panel for displaying an image using the light irradiated from the illumination device.

Technical Field

The present invention relates to an illumination device and a display device.

Background

The liquid crystal display device includes an illumination device (backlight device) that supplies light to the liquid crystal panel together with the liquid crystal panel. As such an illumination device, a so-called edge-Light (or side-Light) structure is known in which a plurality of LEDs (Light Emitting diodes) arranged in a row are arranged so as to face each other on an end surface of a Light guide plate (see, for example, patent document 1). Such an illumination device is disposed on the back surface side of the liquid crystal panel, and supplies light spread in a planar manner toward the back surface of the liquid crystal panel. An optical sheet for imparting an optical action to the emitted light is disposed on the light emitting surface side of the light guide plate of the illumination device.

Depending on the application of the liquid crystal display device, an illumination device emitting high-luminance light is required. Therefore, not only the LEDs may be disposed on one end surface of the light guide plate, but also a plurality of LEDs arranged in a row may be disposed on an opposite end surface so as to face each other, and light may be incident from the end surface located on the opposite side of the one end surface. For example, in a liquid crystal display device used in a state where a display surface is upright, since the illumination device is also in an upright state, a plurality of LEDs arranged in a row are arranged so that an upper-side end surface and a lower-side end surface of an upright light guide plate face each other.

Disclosure of Invention

Technical problem to be solved by the invention

As described above, when the liquid crystal display device is used in a standing state, heat tends to concentrate near the upper side of the light guide plate of the illumination device, which is problematic. In the above-described lighting device, since the LEDs are arranged so that the upper-side end surface and the lower-side end surface of the light guide plate face each other, the vicinity of the upper-side end surface and the vicinity of the lower-side end surface of the light guide plate are heated in accordance with light emission of the LEDs. However, when the lighting device is raised, the heat generated on the lower side is moved to the upper side by the influence of the chimney effect, and thus the heat is concentrated in the vicinity of the upper side of the light guide plate as described above.

In the lighting device, when heat is concentrated in the vicinity of the upper side of the light guide plate, a large temperature difference occurs between the upper side and the lower side of the light guide plate, and thus a portion of the optical sheet overlapping the light guide plate, which portion overlaps the upper side of the light guide plate, is thermally expanded greatly. As a result, the optical sheet cannot provide an appropriate optical function to the light emitted from the light guide plate, and a defect such as uneven brightness may occur in the light emitted from the illumination device.

In addition, if heat is concentrated in the vicinity of the upper side of the light guide plate, there is a possibility that other members constituting the lighting device exceed the rated temperature.

The invention aims to provide a lighting device and the like which can restrain the temperature difference between the upper side vicinity and the lower side vicinity of a light guide plate when the lighting device is used in a standing state in a mode that a light source is respectively arranged at the upper side and the lower side of the light guide plate.

Means for solving the problems

The lighting device of the present invention includes: a first light source unit having a first light source row composed of a plurality of light sources arranged in a row, and a first light source substrate on which the light sources forming the first light source row are mounted and which has a relatively low heat conduction efficiency; a second light source unit having a second light source array including a plurality of light sources arranged in a row, and a second light source substrate on which the light sources forming the second light source array are mounted and which has a relatively high heat transfer efficiency; and a plate-shaped light guide plate which is configured by an end surface facing the first light source row, has a first light incident surface on which light emitted from the light sources forming the first light source row is incident, and a second light incident surface which is configured by an end surface disposed on the opposite side of the first light incident surface and facing the second light source row and on which light emitted from the light sources forming the second light source row is incident.

In addition, the lighting device of another invention includes: a first light source unit having a first light source row including a plurality of light sources arranged in a row and a first light source substrate on which the plurality of light sources forming the first light source row are mounted, and generating a relatively large amount of heat; a second light source unit having a second light source row including a plurality of light sources arranged in a row and a second light source substrate on which the plurality of light sources forming the second light source row are mounted, and generating relatively less heat; and a plate-shaped light guide plate having a first light incident surface and a second light incident surface, wherein the first light incident surface is formed by an end surface facing the first light source row and receives light emitted from the light sources forming the first light source row, and the second light incident surface is disposed on an opposite side of the first light incident surface and formed by an end surface facing the second light source row and receives light emitted from the light sources forming the second light source row.

In addition, the lighting device of another invention includes: a first light source unit having a first light source row including a plurality of light sources arranged in a row and a first light source substrate on which the plurality of light sources forming the first light source row are mounted, the heat dissipation being relatively low; a second light source unit having a second light source row including a plurality of light sources arranged in a row and a second light source substrate on which the plurality of light sources forming the second light source row are mounted, the second light source unit having a relatively high heat dissipation property; and a plate-shaped light guide plate including an end surface facing the first light source row, a first light incident surface on which light emitted from the plurality of light sources forming the first light source row is incident, and a second light incident surface arranged on an opposite side of the first light incident surface and facing the second light source row, on which light emitted from the light sources forming the second light source row is incident.

Effects of the invention

According to the present invention, it is possible to provide an illumination device and the like that can suppress a temperature difference between the vicinity of the upper side and the vicinity of the lower side of a light guide plate when used in a standing state in which light sources are arranged on the upper side and the lower side of the light guide plate, respectively.

Drawings

Fig. 1 is a perspective view of a liquid crystal display device of a first embodiment.

Fig. 2 is an exploded perspective view of the liquid crystal display device.

Fig. 3 is a sectional view taken along line a-a of fig. 1.

Fig. 4 is a top view of the lighting device.

Fig. 5 is a cross-sectional view of a first LED substrate.

Fig. 6 is a sectional view of a second LED substrate.

Fig. 7 is a sectional view of a second LED substrate included in the lighting device of the second embodiment.

Fig. 8 is a sectional view of a second LED substrate included in the lighting device of the third embodiment.

Fig. 9 is a sectional view of a second LED substrate included in the lighting device of the fourth embodiment.

Fig. 10 is a sectional view of a first LED substrate included in the lighting device of the fifth embodiment.

Fig. 11 is a sectional view of a second LED substrate included in the lighting device of the fifth embodiment.

Fig. 12 is a plan view of a lighting device of the sixth embodiment.

Fig. 13 is a sectional view of a liquid crystal display device of a seventh embodiment.

Fig. 14 is a sectional view of a liquid crystal display device of an eighth embodiment.

Detailed Description

< first embodiment >

A liquid crystal display device 10 including an illumination device 12 according to a first embodiment of the present invention will be described below with reference to fig. 1 to 6. For convenience of explanation, the X-axis, Y-axis, and Z-axis are shown in the drawings. Fig. 1 is a perspective view of a liquid crystal display device 10 according to a first embodiment, fig. 2 is an exploded perspective view of the liquid crystal display device 10, and fig. 3 is a sectional view taken along line a-a of fig. 1. As shown in fig. 1, the liquid crystal display device 10 is formed in a horizontally long rectangular shape extending long in the left-right direction as a whole, and is used in a standing state with the short side extending in the vertical direction (Y-axis direction).

The liquid crystal display device 10 mainly includes a liquid crystal panel 11 used as a display panel, an illumination device (backlight device) 12 serving as an external light source for supplying light to the liquid crystal panel 11, a frame-shaped bezel 13 for holding the liquid crystal panel 11, the illumination device 12, and the like.

The liquid crystal panel 11 mainly includes a pair of transparent substrates and a liquid crystal layer sealed between the substrates so as to be sandwiched therebetween, and is configured to display an image on the display surface 11a in a visually recognizable state using light emitted from the illumination device 12. The liquid crystal panel 11 has a rectangular shape that is horizontally long as a whole in a plan view. One of the pair of substrates constituting the liquid crystal panel 11 is an array substrate in which TFTs (Thin Film transistors) or pixel electrodes as switching elements are arranged in a matrix on a transparent glass substrate. The other substrate is a color filter (hereinafter, referred to as CF) substrate in which color filters of red, green, and blue are arranged in a matrix on a transparent glass substrate.

The illumination device 12 is a device that is disposed on the back surface 11b side of the liquid crystal panel 11 and supplies light toward the liquid crystal panel 11, and is configured to emit white light. As shown in fig. 2 and 3, the lighting device 12 mainly includes a chassis 14, an optical sheet 15, a frame 16, an LED unit (light source unit) U, a light guide plate 19, a reflective sheet 20, and the like.

The illumination device 12 is a so-called edge light type (or side light type), and the LED units U are arranged so as to face the two end surfaces 19c and 19d of the light guide plate 19, respectively. In the present specification, the LED unit U disposed so as to face the end surface 19c of the light guide plate 19 is referred to as a first LED unit U1, and the LED unit U disposed so as to face the end surface 19d of the light guide plate 19 is referred to as a second LED unit U2. When the first LED unit U1 and the second LED unit U2 are described in combination, they are referred to as an LED unit U.

The chassis 14 is formed in a substantially box shape having a shallow bottom with an opening on the front side as a whole, and is formed of a metal plate such as an aluminum plate or an electrogalvanized steel plate (SECC). The chassis 14 includes a plate-like bottom portion 14a having a substantially rectangular shape in plan view, and a plate-like side wall portion 14b rising from a peripheral edge of the bottom portion 14a and surrounding the bottom portion 14a, similarly to the liquid crystal panel 11. The portion of the side wall portion 14b that is disposed on the longer side of the bottom portion 14a and is disposed on the lower side in the upright state of the illumination device 12 is referred to as a side wall portion 14b1, and the portion that is disposed on the longer side of the bottom portion 14a and is disposed on the upper side in the upright state of the illumination device 12 is referred to as a side wall portion 14b 2. The portions of the side wall portion 14b disposed on the short sides of the bottom portion 14a are referred to as side wall portions 14b3 and 14b 4.

Various members such as the LED unit U, the reflective sheet 20, the light guide plate 19, and the optical sheet 15 are housed inside the chassis 14. A control board, an LED driving board, and other boards are mounted on the outer side of the chassis 14.

In the chassis 14, a reflective sheet 20 is disposed so as to cover the surface of the bottom portion 14 a. The reflective sheet 20 is a light-reflective thin plate-like member, and is made of, for example, white foamed polyethylene terephthalate (an example of a white plastic sheet). In addition, a light guide plate 19 is housed in the chassis 14 so as to be placed on the reflective sheet 20.

The light guide plate 19 is made of a synthetic resin material (for example, acrylic resin such as PMMA, polycarbonate resin, or the like) having a refractive index sufficiently higher than that of air and being transparent and having excellent light transmittance. The light guide plate 19 is formed of a plate-like member having a substantially rectangular shape in plan view, like the liquid crystal panel 11, and is housed in the chassis 14 such that a front surface (front plate surface) 19a faces the rear surface 11b side of the liquid crystal panel 11 and a rear surface (opposite surface) 19b faces the reflective sheet 20.

The surface 19a of the light guide plate 19 is a light emitting surface 19a that emits light toward the liquid crystal panel 11. The optical sheet 15 is disposed between the light emitting surface 19a and the liquid crystal panel 11 in a state of being placed on the frame 16. In the chassis 14, one end surface 19c of the pair of long-side end surfaces 19c and 19d of the light guide plate 19, which is disposed on the lower side in the upright state of the lighting device 12, faces the first LED unit U1, and serves as a light incident surface 19c on which light from the first LED unit U1 is incident. The other end surface 19d disposed on the upper side in the same state faces the second LED unit U2, and serves as a light incident surface 19d on which light from the second LED unit U2 is incident. In the chassis 14, one end face 19e of the pair of short-side end faces 19e and 19f of the light guide plate 19 faces the side wall portion 14b3, and the other end face 19f faces the side wall portion 14b 4.

A light reflection/scattering pattern having a function of reflecting or scattering light incident into the light guide plate 19 from the light incident surface 19c and the light incident surface 19d and propagating toward the light emitting surface 19a is formed on the back surface 19b of the light guide plate 19. The light reflection/scattering pattern is formed of, for example, a plurality of coating films printed in dots.

The frame 16 is formed in a frame shape (a frame shape) covering the peripheral end of the light guide plate 19 from the front side as a whole, and is assembled to the opening portion of the chassis 14 from the front side. The frame 16 is made of, for example, synthetic resin. The frame 16 includes: a frame body 161 which is frame-shaped in plan view and whose inner peripheral side abuts from the front side against the peripheral end of the light guide plate 19 housed in the chassis 14; and a standing wall portion 162 extending from the frame body portion 161 toward the bottom portion 14a of the chassis 14 and disposed outside the side wall portion 14b of the chassis 14.

The frame body 161 is formed in a frame shape having an inner peripheral edge overlapping the peripheral end of the light guide plate 19 and an outer peripheral edge overlapping the upper end of the side wall 14b of the chassis 14 and having a predetermined width. The back surface of the inner peripheral side of the frame body 161 abuts against the peripheral end of the light guide plate 19 from the front side. The surface of the frame body 161 on the inner peripheral side is set to be further lower than the surface on the outer peripheral side, and the end of the optical sheet 15 is placed on the lowered portion. A projection, not shown, is provided on the surface of the inner peripheral edge side of the frame body 161, and the optical sheet 15 is supported by the frame body 161 by fitting the projection into a hole provided at an end of the optical sheet 15.

The standing wall portion 162 is formed in a plate shape extending from the back surface of the outer peripheral edge side of the frame body portion 161 toward the bottom portion 14a side of the chassis 14 and facing the outer peripheral surface of the side wall portion 14b of the chassis 14. The standing wall portion 162 is formed in a frame shape surrounding the side wall portion 14b as a whole.

The first LED unit (first light source unit) U1 is a device that irradiates light toward the light incident surface 19c on the lower side of the light guide plate 19, and is formed in an elongated shape extending in the longitudinal direction of the light guide plate 19 as a whole. The first LED unit U1 includes a first LED array (first light source array) 171 composed of a plurality of LEDs 17 arranged in a column (one column in the case of the present embodiment) and a first LED substrate (first light source substrate) 181 on which a plurality of LEDs 17 formed as the first LED array 171 are mounted.

The second LED unit (second light source unit) U2 is a device for irradiating light toward the light incident surface 19d on the upper side of the light guide plate 19, and is formed in an elongated shape extending in the longitudinal direction of the light guide plate 19 as a whole. The second LED unit U2 includes a second LED array (second light source array) 172 including a plurality of LEDs 17 arranged in a row (one row in the case of the present embodiment), and a second LED substrate (second light source substrate) 182 on which a plurality of LEDs 17 forming the second LED array 172 are mounted.

When the first LED board 181 and the second LED board 182 are described in combination, they are referred to as an LED board (light source board) 18.

The LED17 used in the LED units U1 and U2 is of a so-called top emission type (top view type), and is surface-mounted on the LED board 18 such that the light emitting surface 17a faces the side opposite to the LED board 18 side. The LED17 mainly includes an LED element (LED chip, light emitting element) as a light emitting source, a sealing material (translucent resin material) for sealing the LED element, and a case (housing body, frame body) for housing the LED element and filled with the sealing material. Each of the LEDs 17 of the present embodiment is configured to emit white light.

The first LED board 181 is formed in a band shape extending along the lower long side (light incident surface 19c) of the light guide plate 19. A plurality of LEDs 17 are mounted on the front surface side of the first LED board 181 in a row in the longitudinal direction. The second LED board 182 is formed in a band shape extending along the upper long side (light incident surface 19d) of the light guide plate 19. A plurality of LEDs 17 are mounted on the front surface side of the second LED board 182 in a row in the longitudinal direction. The LED substrate 18 will be described in detail later.

The first LED unit U1 is disposed in the chassis 14 along the side wall portion 14b1 in a state of being mounted on the first heat dissipation member H1. The first heat radiation member H1 is a metal elongated member having a substantially L-shaped cross section, and includes: a plate-shaped first standing wall portion H1a standing vertically with respect to the bottom portion 14a of the chassis 14 and to which the first LED unit U1 is attached; and a plate-like first placement portion H1b that is placed on the bottom portion 14a and extends from the lower end of the first standing wall portion H1a along the surface of the bottom portion 14 a. The first LED substrate 181 of the first LED unit U1 is attached to the first standing wall portion H1a of the first heat radiation member H1 via a double-sided adhesive member (e.g., double-sided tape) not shown. When the first heat radiation member H1 is installed in the chassis 14, the first standing wall portion H1a is attached so as to be in close contact with the side wall portion 14b1 of the chassis 14. When the first heat radiation member H1 is provided in the chassis 14, the first placement portion H1b is attached so as to be in close contact with the bottom portion 14a of the chassis 14. In the chassis 14, the end portion of the light guide plate 19 on the light incident surface 19c side and the end portion of the reflective sheet 20 laid on the lower side thereof are placed on the first placement portion H1b of the first heat radiation member H1. Further, the light incident surface 19c of the light guide plate 19 faces the light emitting surface 17a of the LED17 (first LED row 171) of the first LED unit U1 attached to the first standing wall portion H1a of the first heat radiation member H1. A small gap is provided between the light incident surface 19c and the light emitting surface 17 a.

The second LED unit U2 is disposed in the chassis 14 along the side wall portion 14b2 in a state of being mounted on the second heat dissipation member H2. The second heat radiation member H2 is a metal elongated member having a substantially L-shaped cross section, similarly to the first heat radiation member H1, and includes: a plate-shaped second standing wall portion H2a standing vertically with respect to the bottom portion 14a of the chassis 14 and to which the second LED unit U2 is attached; and a plate-like second placement portion H2b that is placed on the bottom portion 14a and extends from the lower end of the second standing wall portion H2a along the surface of the bottom portion 14 a. The second LED substrate 182 of the second LED unit U2 is attached to the second standing wall portion H2a of the second heat radiation member H2 via a double-sided adhesive member (e.g., double-sided tape) not shown. When the second heat radiation member H2 is disposed in the chassis 14, the second standing wall portion H2a is attached so as to be in close contact with the side wall portion 14b2 of the chassis 14. When the second heat radiation member H2 is installed in the chassis 14, the second placement portion H2b is attached in close contact with the bottom 14a of the chassis 14. In the chassis 14, the end portion of the light guide plate 19 on the light incident surface 19d side and the end portion of the reflective sheet 20 laid on the lower side thereof are placed on the second placement portion H2b of the second heat radiation member H2. The light incident surface 19d of the light guide plate 19 faces the light emitting surface 17a of the LED17 (second LED row 172) of the second LED unit U2 attached to the second wall portion H2a of the second heat radiation member H2. A slight gap is also provided between the light incident surface 19d and the light emitting surface 17 a.

Fig. 4 is a top view of the illumination device 12. In fig. 4, the illumination device 12 is shown with the frame 16, the optical sheet 15, and the like removed for convenience of explanation. As shown in fig. 4, the first LED unit U1 and the second LED unit U2 are disposed so as to face each other in the chassis 14 with the light guide plate 19 interposed therebetween. As shown in fig. 1, when the lighting device 12 is used in the standing state, the first LED unit U1 facing the light incident surface 19c is disposed on the lower side, and the second LED unit U2 facing the light incident surface 19d is disposed on the upper side.

As shown in fig. 4, the LEDs 17 on the first LED board 181 (the LEDs 17 forming the first LED array 171) are arranged at equal intervals in the longitudinal direction (left-right direction) of the light guide plate 19. The LEDs 17 on the second LED board 182 (the LEDs 17 forming the second LED row 172) are also arranged at equal intervals in the longitudinal direction (left-right direction) of the light guide plate 19. In the case of the present embodiment, the same kind of LEDs 17 are mounted on both the first LED unit U1 and the second LED unit U2, and the supply current to each LED17 (the brightness of each LED17), the heat generated from each LED17, and the like are also the same. In the present embodiment, the first LED unit U1 and the second LED unit U2 have the same number of LEDs 17.

The optical sheet 15 has a substantially rectangular shape that is horizontally long in plan view, like the liquid crystal panel 11. The optical sheet 15 is disposed between the light emitting surface 19a of the light guide plate 19 and the back surface 11b of the liquid crystal panel 11 so that the peripheral end portion thereof is placed on the frame main body portion 161 of the frame 16 from the front side. The optical sheet 15 has a function of transmitting light emitted from the light guide plate 19 toward the liquid crystal panel 11 while imparting a predetermined optical function. The optical sheet 15 is formed by laminating a plurality of sheets. Specific examples of the sheet constituting the optical sheet 15 include a diffusion sheet, a lens sheet, and a reflection-type polarizing sheet. Note that the optical sheet 15 is made of a transparent plastic material.

The first LED board 181 and the second LED board 182 are explained in detail below. Fig. 5 is a sectional view of the first LED substrate 181. The first LED substrate 181 includes a first supporting base 81, a first insulating layer 82 formed on the first supporting base 81, and a first wiring portion 83 formed on the first insulating layer 82.

The first support base 81 is formed of an elongated member having excellent thermal conductivity (heat dissipation property) while ensuring rigidity of the first LED board 181. The first support base 81 is made of a metal base made of metal or alloy, for example, an aluminum alloy base (a 5052). The first insulating layer 82 is formed of a synthetic resin coating film so as to cover the surface of the first supporting base 81. The first wiring portion 83 is formed of a patterned metal foil (e.g., a copper foil) electrically connected to the LEDs 17 forming the first LED array 171.

Fig. 6 is a sectional view of the second LED substrate 182. The second LED substrate 182 includes a second supporting base 81, a second insulating layer 82 formed on the second supporting base 81, and a second wiring portion 83A formed on the second insulating layer 82. The second LED substrate 182 is the same as the first LED substrate 181 (same material, same size, etc.) except that the second wiring portion 83A has a larger thickness than the first wiring portion 83.

In the case of the present embodiment, the first wiring portion 83 of the first LED board 181 is made of copper foil having a thickness of 18 μm, and the second wiring portion 83A of the second LED board 182 is made of copper foil having a thickness of 35 μm.

In the liquid crystal display device 10 having the above configuration, when an image is displayed on the display surface 11a of the liquid crystal panel 11, the LEDs 17 of the LED units U included in the illumination device 12 emit light (light up). When each LED17 emits light, the light enters the light guide plate 19 from the light entrance surface 19c of the light guide plate 19 disposed on the lower side and the light entrance surface 19d disposed on the upper side. The incident light is reflected by a reflective sheet 20 laid on the back side of the light guide plate 19, a light reflection/scattering pattern formed on the back surface 19b of the light guide plate 19, or the like, propagates through the light guide plate 19, and is emitted from a light emitting surface 19a formed of the front side plate surface. The light emitted from the light emitting surface 19a passes through the optical sheet 15 and is diffused in a planar manner, and is irradiated to the back surface 11b of the liquid crystal panel 11. Thus, the liquid crystal panel 11 displays an image on the display surface 11a using light from the illumination device 12.

When the liquid crystal display device 10 of the present embodiment is used in a state in which the display surface 11a is erected along the vertical direction, a temperature difference between the lower side (the light incident surface 19c side) of the light guide plate 19 in which the first LED unit U1 is arranged and the upper side (the light incident surface 19d side) of the light guide plate 19 in which the second LED unit U2 is arranged can be suppressed. The first LED unit U1 generates heat when each LED17 is driven to be lit, and the lower side (the light incident surface 19c side) of the light guide plate 19 is heated by the generated heat. Further, the LEDs 17 of the first LED unit U1 generate heat, and the heat rises in the lighting device 12 due to the chimney effect, and the upper side (the light incident surface 19d side) of the light guide plate 19 is also heated. Note that the upper side (light incident surface 19d side) of the light guide plate 19 is also heated by heat generated from the LEDs 17 of the second LED unit U2.

However, as described above, since the second wiring portion 83A made of copper foil of the second LED board 182 of the second LED unit U2 is thicker than the first wiring portion 83 of the first LED board 181, the heat conduction efficiency (heat dissipation efficiency) of the second LED board 182 is higher than that of the first LED board 181, and the heat dissipation performance is excellent. Therefore, when the LEDs 17 of the second LED unit U2 are driven to be lit, the heat generated from the LEDs 17 can be efficiently transferred from the second LED board 182 to the outside (the second heat radiation member H2, the chassis 14). Therefore, even if the heat generated from the first LED unit U1 disposed below moves upward due to the chimney effect, the heat generated from the second LED unit U2 disposed above efficiently dissipates to the outside, and therefore, as described above, the temperature difference between the lower side and the upper side of the light guide plate 19 can be suppressed. As a result, the difference in thermal expansion between the optical sheet 15 on the lower side and the optical sheet 15 on the upper side is also suppressed, and the occurrence of wrinkles or deflection in the optical sheet 15 is suppressed.

For example, when the length of the optical sheet 15 is 720mm and a temperature difference of 15 ℃ is generated between the lower side and the upper side of the optical sheet 15, the linear expansion coefficient of the optical sheet 15 is 9 × 10^-5The difference in size between the lower side and the upper side due to thermal expansion is about 1mm (9 × 10 ═ c)^-5X 720 × 15). The thermally expanded optical sheet 15 may interfere with other members or the like to generate wrinkles or flexure. The lighting device 12 of the present embodiment can suppress such a large-size difference of the optical sheet 15 due to thermal expansion.

< second embodiment >

Next, an illumination device according to a second embodiment will be described with reference to fig. 7. Fig. 7 is a sectional view of a second LED substrate 282 included in the lighting device of the second embodiment. The basic configuration of the illumination device of the present embodiment is the same as the illumination device 12 of the first embodiment, and the configuration of only the second LED substrate 282 included in the second LED unit is different from that of the first embodiment. The second LED board 282 of the present embodiment has the same basic configuration as the first LED board (the first LED board 181 of the first embodiment), but the thickness of the second support base 81B is set to be larger than the first LED board (the first LED board 181 of the first embodiment). The second insulating layer 82 and the second wiring portion 83 in the present embodiment are the same as the first insulating layer and the first wiring portion of the first LED substrate, respectively. In the case of this embodiment, the thickness of the first support base (aluminum alloy base) of the first LED board is 1.0mm, and the thickness of the second support base (aluminum alloy base) 81B of the second LED board 282 is 1.5 mm. The first support base and the first support base are each made of an aluminum-based alloy (an example of a metal-based material) having excellent thermal conductivity. As described above, since the thickness of the second support base 81B is set to be larger than that of the first support base of the first LED board, the second LED board 282 disposed on the upper side of the light guide plate has higher heat conduction efficiency (heat radiation efficiency) than the first LED board disposed on the lower side of the light guide plate, and thus has excellent heat radiation performance. Therefore, the lighting device of the present embodiment can suppress a temperature difference between the lower side and the upper side of the light guide plate when used in the standing state, as in the first embodiment.

< third embodiment >

Next, an illumination device according to a third embodiment will be described with reference to fig. 8. Fig. 8 is a sectional view of a second LED substrate 382 included in the lighting device of the third embodiment. The basic configuration of the illumination device of the present embodiment is the same as the illumination device 12 of the first embodiment, and the configuration of only the second LED substrate 382 included in the second LED unit is different from that of the first embodiment. The second LED board 382 of the present embodiment has the same basic configuration as the first LED board (the first LED board 181 of the first embodiment), but the material constituting the second support base 81C is made of a pure aluminum base (for example, a1050, a1070, or the like), and a material having a higher thermal conductivity than the material used for the first support base of the first LED board (alloy aluminum base) is used. The second insulating layer 82 and the second wiring portion 83 in the present embodiment have the same configuration as the first insulating layer and the first wiring portion of the first LED substrate, respectively. As described above, the second LED substrate 382 of the present embodiment is configured such that the thermal conductivity of the material constituting the second support base 81C is higher than that of the first support base of the first LED substrate, and therefore the heat conduction efficiency (heat radiation efficiency) of the second LED substrate 382 arranged on the upper side of the light guide plate is higher than that of the first LED substrate arranged on the lower side of the light guide plate, and the heat radiation performance is excellent. Therefore, the lighting device of the present embodiment can suppress a temperature difference between the lower side and the upper side of the light guide plate when used in the standing state, as in the first embodiment.

< fourth embodiment >

Next, an illumination device according to a fourth embodiment will be described with reference to fig. 9. Fig. 9 is a sectional view of a second LED substrate 482 included in the lighting device of the fourth embodiment. The basic configuration of the illumination device of the present embodiment is the same as the illumination device 12 of the first embodiment, and the configuration of the second LED substrate 482 included in only the second LED unit is different from that of the first embodiment. The second LED substrate 482 of the present embodiment has the same basic configuration as the first LED substrate (the first LED substrate 181 of the first embodiment), but the second insulating layer 82D is set to have a smaller thickness than the first insulating layer of the first LED substrate. The second supporting base 81 and the second wiring portion 83 in the present embodiment have the same configuration as the first insulating layer and the first wiring portion of the first LED board, respectively. In the case of this embodiment, the thickness of the first insulating layer of the first LED substrate is 100 μm, and the thickness of the second insulating layer 82D of the second LED substrate 482 is 75 μm. Since the thickness of the second insulating layer 82D of the second LED board 482 is set to be smaller than the thickness of the first insulating layer of the first LED board as described above, the second LED board 482 arranged on the upper side of the light guide plate has lower thermal resistance than the first LED board arranged on the lower side of the light guide plate, and thus has excellent heat dissipation. Therefore, the lighting device of the present embodiment can suppress a temperature difference between the lower side and the upper side of the light guide plate when used in the standing state, as in the first embodiment.

< fifth embodiment >

Next, an illumination device according to a fifth embodiment will be described with reference to fig. 10 and 11. Fig. 10 is a sectional view of a first LED substrate included in the lighting device of the fifth embodiment, and is a sectional view of a second LED substrate included in the lighting device of the fifth embodiment. The basic configuration of the illumination device of the present embodiment is the same as that of the illumination device 12 of the first embodiment, and the first LED substrate 581 included in the first LED unit and the second LED substrate 582 included in the second LED unit are different from those of the first embodiment. The thickness (total thickness) of the first LED substrate 581 and the thickness (total thickness) of the second LED substrate 582 of the present embodiment are set to be the same. The first LED board 581 of the present embodiment is formed of a printed board (single-sided board), and includes a first supporting base 81E1 made of an insulating synthetic resin and a single-layer wiring portion 83E formed on the first supporting base 81E 1. The wiring portion 83E is formed of a patterned metal foil (e.g., copper foil) electrically connected to each LED formed in the first LED row. The second LED board of the present embodiment is formed of a printed circuit board (double-sided board), and includes a second supporting base 81E2 made of an insulating synthetic resin and wiring portions 83E formed on both sides of the second supporting base 81E 2. The second support substrate 81E2 is made of the same material as the first support substrate 81E1, but has a smaller thickness than the first support substrate 81E 1. In addition, the second LED substrate 582 has a two-layer wiring portion 83E. That is, the second LED substrate 582 has the multilayer wiring portion 83E as a whole. The thickness of each layer of the wiring portion 83E in the second LED substrate 582 is set to be the same as the thickness of the wiring portion 83E in the first LED substrate 581. In the case of this embodiment, since the ratio of the multilayer (two-layer) wiring portion 83E to the second LED substrate 582 is higher than the ratio of the single-layer (one-layer) wiring portion 83E to the first LED substrate 581, the heat conduction efficiency (heat radiation efficiency) of the second LED substrate 582 disposed on the upper side of the light guide plate is higher than that of the first LED substrate 581 disposed on the lower side of the light guide plate, and the heat radiation performance is excellent. Therefore, the lighting device of the present embodiment can suppress a temperature difference between the lower side and the upper side of the light guide plate when used in the standing state, as in the first embodiment.

< sixth embodiment >

Next, an illumination device according to a sixth embodiment will be described with reference to fig. 12. Fig. 12 is a plan view of a lighting device 12F of the sixth embodiment. Fig. 12 shows the illumination device 12F with the frame, the optical sheet, and the like removed for convenience of explanation. The lighting device 12F of the present embodiment is different from the lighting device 12 of the first embodiment in the configuration of the second LED unit U2F. The number of LEDs 17 forming the second LED column 172 in the second LED unit U2F of the present embodiment is smaller than the first LED column 171 of the first LED unit U1. In the present embodiment, on the upper side (the light incident surface 19d side) of the light guide plate 19, which is likely to become high in temperature, the amount of heat generated from the second LED unit U2F is made smaller than that of the first LED unit U1 by reducing the number of LEDs 17 used. The number of LEDs 17 used in the second LED array 172F is preferably smaller than that of the LEDs 17 in the first LED array 171, so that the light emitted from the lighting device 12F does not cause luminance unevenness. By appropriately setting the light reflection/scattering pattern formed on the back surface 19b side of the light guide plate 19, the influence (decrease in luminance) of the LEDs 17 of the second LED array 172F can be suppressed from being reduced. As shown in this embodiment, the number of LEDs 17 for supplying light to the light incident surface 19d on the upper side of the light guide plate 19 can be reduced to reduce the heat generation source, thereby suppressing the temperature difference between the lower side and the upper side of the light guide plate 19.

< seventh embodiment >

Next, a liquid crystal display device 10G including the illumination device 12G of the seventh embodiment will be described with reference to fig. 13. Fig. 13 is a sectional view of a liquid crystal display device 10G of the seventh embodiment. The liquid crystal display device 10G of the present embodiment is different from the liquid crystal display device 10 of the first embodiment only in the configuration of the second heat radiation member H2G included in the lighting device 12G. In the lighting device 12G of the present embodiment, the size (outer shape) of the second heat radiation member H2G disposed on the upper side (the light incident surface 19d side) of the light guide plate 19 is set to be larger than the first heat radiation member H1 disposed on the lower side (the light incident surface 19c side). Specifically, the second heat radiation member H2G has a plate-shaped second placement portion H2bG that is larger than the first placement portion H1b of the first heat radiation member H1. The second standing wall portion H2aG of the second heat radiation member H2G is set to have the same size as the first standing wall portion H1a of the first heat radiation member H1. As shown in this embodiment, on the upper side of the light guide plate 19 which is likely to become high in temperature, the size (outer shape) of the second heat radiation member H2G used is increased to increase the contact area between the second heat radiation member H2G and the chassis 14, so that the heat generated from the second LED unit U2 can be efficiently released to the outside (the chassis 14 and the like) using the second heat radiation member H2G. As shown in the present embodiment, on the upper side of the light guide plate 19, the temperature difference between the lower side and the upper side of the light guide plate 19 can be suppressed by improving the heat conduction efficiency of the heat generated from the LEDs 17 of the second LED unit U2. In other embodiments, the outer shape and/or thickness (one or both of the outer shape and the thickness) of the second heat radiation member H2G may be larger than that of the first heat radiation member H1.

< eighth embodiment >

Next, an illumination device according to an eighth embodiment will be described. The basic configuration of the lighting device of the present embodiment is the same as the lighting device 12 of the first embodiment, and in the lighting device (the configuration of the first support substrate and the configuration of the second support substrate are the same), the power (LED current value) supplied to each LED of the second LED unit is made smaller than the power (LED current value) supplied to each LED of the first LED unit. In the case of this embodiment, the current supplied to each LED of the first LED unit disposed on the lower side of the light guide plate is 80mA, and the current supplied to each LED of the second LED unit disposed on the upper side of the light guide plate is 70 mA. In this way, by reducing the current supplied to the LEDs on the upper side of the light guide plate, which is likely to become high in temperature, the amount of heat generated from the LEDs of the second LED unit can be made smaller than that of the first LED unit, so that the temperature difference between the lower side and the upper side of the light guide plate can be suppressed.

< ninth embodiment >

Next, a lighting device of a ninth embodiment will be described. In the lighting device of the present embodiment, basically, the same configuration as the lighting device 12 of the first embodiment (the configuration of the first support substrate and the configuration of the second support substrate are the same), when the first LED substrate of the first LED unit is attached to the first standing wall portion of the first heat radiation member (heat radiating body), a normal double-sided tape (first double-sided adhesive member having relatively low thermal conductivity) is used. On the other hand, when the second LED substrate of the second LED unit is attached to the second wall portion of the second heat radiation member (radiator), a thermally conductive double-sided tape (second double-sided adhesive member having relatively high thermal conductivity) is used. In this way, a structure having excellent thermal conductivity (for example, a structure in which a thermally conductive filler is dispersed in an adhesive layer) is used as a double-sided tape for fixing the second LED board on the upper side of the light guide plate which is likely to become high temperature, and the heat generated from the second LED unit is likely to efficiently escape to the second heat dissipation member or the like, and a temperature difference between the lower side and the upper side of the light guide plate can be suppressed.

< tenth embodiment >

Next, an illumination device 10H of the tenth embodiment is explained. In the lighting device 10H of the present embodiment, as in the first embodiment, the thickness of the second wiring portion (not shown) of the second LED board 182H included in the second LED unit U2H is set to be larger than the thickness of the first wiring portion (thickness) of the first LED board 181H included in the first LED unit U1H. The illumination device 10H of the present embodiment differs from the first embodiment in the arrangement, shape, and the like of the respective members such as the optical sheet 15H and the reflective sheet 20H. Specifically, the optical sheet 15H of the present embodiment is configured such that the optical sheet 15H is directly placed on the light emitting surface 19a of the light guide plate 19, and heat generated from the first LED unit U1H and the second LED unit U2H is more easily transmitted to the optical sheet 15H through the light guide plate 19, air, or the like, as compared with the first embodiment or the like. The frame body 161H of the frame 16H abuts on the peripheral edge of the light exit surface 19a of the light guide plate 19, and a portion of the inner peripheral edge side thereof facing the light exit surface 19a of the light guide plate 19 is recessed. The end of the optical sheet 15H placed on the light guide plate 19 is accommodated in the recessed portion. The standing wall portion 162H of the frame 16H is provided on the outer peripheral edge side of the frame body portion 161H so as to surround the side wall portion of the chassis 14 from the outside. The reflective sheet 20H is interposed between the back surface 19b of the light guide plate 19 and the bottom 14aH of the chassis 14H. Further, the lower and upper portions 14bH1 and 14bH2 of the chassis 14H protrude outward from the bottom portion 14aH, and the first heat radiation member H1H for holding the first LED unit U1H and the second heat radiation member H2H for holding the second LED unit U2H are housed in a space inside the upper portion. The liquid crystal panel 11 is disposed so that its peripheral edge portion is sandwiched between the frame main body portion 161H and the bezel 13H of the frame 16H. In the LED substrate 18H (the first LED substrate 181H and the second LED substrate 182H) according to the present embodiment, the dimension in the thickness direction (Z-axis direction) of the lighting device 10H is larger than that of the first embodiment, and the width of the first heat radiation member H1H and the second heat radiation member H2H (the dimension in the thickness direction (Z-axis direction) of the lighting device 10H) holding each LED substrate 18H is also larger. In the lighting device 10H of the present embodiment, even if the heat generated from the first LED unit U1H disposed below moves upward due to the chimney effect, the heat generated from the second LED unit U2H disposed above is efficiently dissipated to the outside by the second LED board 182H having high heat conduction efficiency (heat dissipation efficiency). As a result, the difference in thermal expansion between the optical sheet 15H on the lower side and the optical sheet 15H on the upper side is also suppressed, and the occurrence of wrinkles or deflection in the optical sheet 15H is suppressed.

< other embodiments >

The present invention is not limited to the embodiments described above and illustrated in the drawings, and for example, the following embodiments are also included in the technical scope of the present invention.

(1) In the third embodiment, the first LED substrate used for the first LED unit may be a printed substrate, and the second LED substrate used for the second LED unit may be an aluminum substrate, thereby improving the heat conduction efficiency (heat radiation efficiency) at the upper side of the light guide plate, which is likely to become high temperature.

(2) In the fifth embodiment, as the second LED substrate used for the second LED unit, a multilayer substrate such as a four-layer substrate may be used. In other embodiments, the wiring portion may be a single layer or a plurality of layers in the first LED substrate (first light source substrate) used as the first LED unit. In this case, as the second LED substrate (second light source substrate) used for the second LED unit, a multilayer wiring portion having a larger number of layers than the wiring portion of the first LED substrate is used.

(3) In the above embodiments, the illumination device having the horizontally long rectangular shape in a plan view is exemplified, but the illumination device may have another shape such as a vertically long rectangular shape in a plan view as long as the object of the present invention is not impaired.

(4) In other embodiments, the display device (liquid crystal display device) may be a television receiver having a tuner or the like, an electronic signboard (digital signage) or the like.

(5) In another embodiment, the techniques exemplified in the first to ninth embodiments and the like can be applied to the illumination device having the configuration in which the optical sheet exemplified in the tenth embodiment is directly placed on the light emitting surface of the light guide plate.

Description of the reference numerals

A10 … display device, a 12 … lighting device, a 13 … bezel, a 14 … chassis, a 15 … optical sheet, a 16 … frame, a 17 … light source, a 171 … first light source row, a 172 … second light source row, a 181 … first light source substrate, an 81 … first supporting substrate, a second supporting substrate, a 82 … first insulating layer, a second insulating layer, an 83 … first wiring portion, an 83a … second wiring portion, a 182 … second light source substrate, a U1 … first light source unit, and a U2 … second light source unit.