LIGHTING APPARATUS, DISPLAY APPARATUS, AND TELEVISION RECEIVER

A backlight apparatus includes LEDs; a light guide plate; an optical member; a chassis formed by bending a metal plate material, the chassis including a bottom plate (plate portion) that extends along the light guide plate, a rising portion (first extending portion) that rises from the bottom plate on an opposite side to the light guide plate and forms a first corner portion with the bottom plate, and a height-difference portion that forms a second corner portion with the rising portion and provides a height-difference portion with respect to the bottom plate; and a heat dissipating member that dissipates heat of the LEDs, the heat dissipating member including a light source attachment portion to which the LEDs are attached and a chassis contacting portion that is contiguous with the light source attachment portion and is in contact with the height-difference portion from the opposite side to the light guide plate.

TECHNICAL FIELD

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

BACKGROUND ART

In recent years, as the display element in image display devices such as television receivers has gone from being conventional cathode-ray tubes a thin-screen display panel such as a liquid crystal panel, plasma display panel or the like, it has become possible to make image display apparatuses having a thinner profile. In liquid crystal display devices, the employed liquid crystal panel does not generate light itself, but requires a separate backlight device as an illumination device. Backlight devices can be broadly classified as being either of a direct or edge-lit type. To realize even thinner liquid crystal display devices, it is preferable to use an edge-lit backlight device, a well-known example of which is described in the below-mentioned Patent Document 1.

Patent Document 1 discloses a backlight device including a light guide plate, an optical sheet arranged on a top surface of the light guide plate, a light source arranged one side of the light guide plate, and a lower housing that houses the light guide plate and the light source. Here, the lower housing includes a light source portion fixing frame in which the light source is fixed, and a chassis (housing portion) arranged under the light guide plate and coupled to the light source portion fixing frame. Also, a portion (plate) of the light source fixing frame is arranged outward of a bottom surface of the chassis such that heat generated by the light source is discharged directly to the outer side of the lower housing, thereby enabling a increase in heat dissipation efficiency.

RELATED ART DOCUMENT

Patent Document

Problems to be Solved by the Invention

However, with heat dissipation members such as the light source fixing frame, heat is not just dissipated into the air outside the backlight device, but also transmitted inside the backlight device via the chassis. Here, for the chassis of the backlight device, it is preferable, from the point of view of mechanical strength (stiffness), cost, and the like, to use a member made of a metal such as iron. In such cases, since the thermal conductivity of the chassis is higher than air, the proportion of heat transmitted to the inside of the of backlight device from the heat dissipating member increases relative to the heat dissipated to the outside of the backlight device from the heat dissipating member.

An optical sheet is arranged inside the backlight device. In the optical sheet, the portion overlapping the heat dissipating member undergoes thermal expansion due to the heat from the heat dissipating member, putting it at risk of deformation by wrinkling, bending or the like.

SUMMARY OF THE INVENTION

The present invention was completed based on the above-described circumstances, and provides an illumination device in which deformation of an optical sheet by wrinkling, bending or the like is suppressed by suppressing transmission of heat from a heat dissipating member to inside an illumination device.

Means for Solving the Problem

The illumination device of the present invention includes: a light source; a light guide plate that faces the light source and that has a light incident face on which light from the light source is incident and a light exiting surface from which light exits; an optical sheet arranged on a side of the light guide plate adjacent to the light exiting surface thereof; a chassis formed by bending a metal plate and arranged on a side of the light guide plate opposite to the light exiting surface thereof, the chassis being constituted of a bottom plate that extends along the light guide plate, a rising portion that rises from the bottom plate to a side opposite to the light guide plate and that forms a first corner portion with the bottom plate, and a height-difference portion that forms a second corner portion with the rising portion and provides a difference in height with respect to the bottom plate; and a heat dissipating member that dissipates heat from the light source, the heat dissipating member being constituted of a light source attachment portion to which the light source is attached and a chassis contacting portion that is contiguous with the light source attachment portion and in contact with the height-difference portion from a side opposite to the light guide plate.

In the illumination device, the first corner portion and the second corner portion formed by bending a metal plated are formed in the chassis between the bottom plate and the height-difference portion. In this process, since warping and cracking occur when bending a metal, corner portions formed by bending the metal material have a higher thermal resistance than flat portions. Hence, in above-described illumination device, the conduction of heat from the height-difference portion to the bottom plate is more difficult than when the height-difference portion and the bottom plate form a continuous flat plane.

Also, since the chassis contacting portion of the heat dissipating member is in contact with the height-difference portion from the opposite side of the chassis to the light guide plate, heat is dissipated via the chassis contacting portion. In comparison to the case in which the height-difference portion and the bottom plate form a continuous flat surface, the amount of heat dissipated from the chassis contacting portion on the chassis side is reduced, and the amount of heat dissipated from the opposite side to the chassis30is increased. As a result, it becomes more difficult for the heat from the heat dissipating member to reach the optical sheet, which is disposed on the chassis side with respect to the chassis contacting portion. Hence, the occurrence of wrinkling in the optical member due to thermal expansion of the section of the optical member overlapping the chassis contacting portion can be suppressed.

Effects of the Invention

According to the present invention, it is possible to provide an illumination device or the like in which deformation of an optical sheet by wrinkling, bending, or the like is suppressed.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiment 1 is described below with reference to the drawings. The present embodiment is exemplified by a liquid crystal display device (example of a display device)10. Note that an X-axis, Y-axis and Z-axis are indicated in the drawings, and the depicted portions are depicted with common axis orientation in each drawing. Of these axes, the Y-axis direction corresponds to a vertical direction, and the X-axis direction corresponds to a horizontal direction. Where not otherwise specified, descriptions of up and down are based on the vertical direction.

The television receiver TV includes a liquid crystal display unit LDU, boards PWB, MB and CTB installed on the rear surface side (back surface side) of the liquid crystal display unit LDU, a cover member CV installed so as to cover the main boards PWB, MB and CTB on the rear surface of the liquid crystal display unit LDU, and a stand ST. The display surface of the liquid crystal display unit LDU is held in a state of alignment with the vertical direction (Y-axis direction) by the stand ST. The liquid crystal display device10according to the present embodiment is what is left after removing at least the configuration for receiving television signals (tuner of main board MB and the like) from the television receiver TV of the above-described configuration. As illustrated inFIG. 2, the liquid crystal display unit LDU has an oblong form (rectangular and extending longitudinally) as a whole, includes a liquid crystal panel11that is a display panel, and a backlight device12that is an external light source, and is held in an integrated manner by a frame13and a housing member50, which are externally visible members of the liquid crystal display device10.

First, the configuration of the rear surface side in the liquid crystal display device10will be described. As illustrated inFIG. 2, on a rear surface of the liquid crystal display device10, a pair of stand attachment member STA at positions separated by a space along the X-axis direction are provided, each member extending in the Y-axis direction. The stand attachment members STA have a cross-sectional profile with a substantially channel-like form in which a surface on the liquid crystal display device10side is open. A pair of pillar portions STb of the stand ST is inserted into the space maintained between the stand attachment members STA and the liquid crystal display device10. Note that the spaces in the stand attachment members STA are arranged to allow wiring members (electrical wiring or the like) connected to the LED substrates (example of light source substrate)18including the backlight device12to pass through. The stand ST is formed from a pedestal portion STa that aligns with the X-axis direction and the Z-axis direction, and a pair of pillar portions STb rising from the pedestal portion STa along the Y-axis direction. A cover member CV is made from a synthetic resin and is attached so as to cover what amounts to approximately a lower half of the rear surface of the liquid crystal display device10shown inFIG. 2, while being traversed through the X-axis direction by the pair of stand attachment members STA. Between the cover member CV and the liquid crystal display device10is retained a component housing space capable of housing components such as the below-described boards PWB, MB and CTB.

As illustrated inFIG. 2, the boards PWB, MB and CTB include a power supply board PWB, a main board MB, and a control board CTB. The power supply board PWB could also be referred to as a power supply of the liquid crystal display device10, and supplies driving power to the boards MB and CTB and to the LEDs (example of light source)17included on the backlight device12. Accordingly, the power supply board PWB can be said to also serve as an LED driving substrate for driving LEDs17. The main board MB includes at least a tuner portion capable of receiving television signals and an image processing portion (which, like the tuner portion, is not shown in the drawings), and is capable of outputting processed image signals to the below-described control board CTB. Note that when the liquid crystal display device10is connected to an external image playback device not shown in the drawings, the main board MB is inputted with an image signal from the image playback device, and is capable of processing the image signal using an image processing unit and outputting the processed signal to the control board CTB. The control board CTB functions to convert the image signal input from the main board to a liquid crystal driving signal and supply the converted liquid crystal driving signal to the liquid crystal panel16.

As illustrated inFIG. 3, in the liquid crystal display unit LDU that forms a portion of the liquid crystal display device10, the main component parts are housed in a space maintained between the frame13that creates the external appearance of the display device on the front side and the housing member50that creates the external appearance on the rear side. Thus, as the frame13provides the front-side external appearance of the liquid crystal display device10, the frame13is a touchable portion of the liquid crystal display device10. The housing member50is formed from a later-described heat dissipating member19and a chassis30. The main components housed within the frame13and the housing member50include at least a liquid crystal panel11, an optical member15(optical sheet), a light guide plate16, and the LED unit LU. Of these components, the liquid crystal panel11, the optical member15, and the light guide plate16are stacked on top of each other, and arranged so as to be held in sandwiched form by the front side frame13and the rear side housing member50. The backlight device12is formed from the optical member15, the light guide plate16, the LED unit LU, and the chassis30(housing member50), which is a configuration corresponding to the above-described liquid crystal display unit LDU without the liquid crystal panel11and frame13. The LED units LU that form a portion of the backlight device12are arranged in a pair such that the light guide plate16is sandwiched from both short-side direction (Y-axis direction) sides. The LED unit LU includes LEDs17that are the light source, an LED substrate18on which the LEDs17are mounted, and a heat dissipating member19to which the LED substrate18is attached. Note that the heat dissipating member19of the present embodiment forms a portion of the LED unit LU and a portion of the housing member50. In the following, components are described.

As illustrated inFIG. 3, the liquid crystal panel11has an oblong form (rectangular and extending longitudinally) when seen in plan view, and is constructed in such a way that a pair of glass substrates11aand11bwith excellent transparency are adhered together in a state of separation across a prescribed gap and liquid crystals are contained in between the two substrates11aand11b. Provided on one substrate (array substrate)11bare switching elements (such as TFTs) connected by mutually perpendicular source wiring and gate wiring, pixel electrodes connected to the switching elements, and alignment film or the like. Provided on the other substrate (CF substrate)11aare color filters having red (R), green (G) and blue (B) colored portions arranged in a prescribed arrangement, opposite electrode, and alignment film or the like. The liquid crystal panel11is mounted by being stacked on the front side of the optical member15described below. A surface on the rear side of the liquid crystal panel11(outer surface of rear-side polarizing plate) is tightly adhered to the optical member15with almost no space therebetween. As a result, intrusions of dust or the like between the liquid crystal panel11and the optical member15is prevented. A display surface11cof the liquid crystal panel11is made up of a display region provided towards a center of the screen and capable of displaying images, and a non-display region provided towards a peripheral edge of the screen to form a bezel (frame-like area) around the periphery of the display region. The liquid crystal panel11is connected to the control board CTB via driver components for driving the liquid crystals and a flexible substrate26, and is arranged to display images in the display region of the display surface11cin accordance with signals input from the control board CTB. Note also that polarizing plates (not shown in the drawings) are provided on the outer sides of each of the substrates11aand11b.

As illustrated inFIG. 3, the optical member15, like the liquid crystal panel11, has an oblong form when seen in plan view, and a size (short-side dimension and long-side dimension) equal to that of the liquid crystal panel11. The optical member15is mounted by being layered on the front side (light-emitting side) of the later-described light guide plate16so as to be sandwiched between the above-described liquid crystal panel11and the light guide plate16. The optical member15is arranged in three mutually stacked layers, each of which has a sheet-like form. Specifically, stated in order starting at the rear side (light guide plate16side), the optical member15includes a diffusion sheet15a, a lens sheet (prism sheet)15b, and a reflection-type polarizing sheet15c. Note also that the three sheets15a,15b, and15care approximately the same size when seen in plan view.

The light guide plate16is formed from a synthetic resin material (for example, polycarbonate or an acrylic resin such as PMMA) that has a refractive index sufficiently higher than air and is nearly transparent (has excellent transparency). As illustrated inFIG. 3, the light guide plate16, in a similar manner to the liquid crystal panel11and the optical member15, has an oblong form when seen in plan view. Further, the light guide plate16has a plate-like form and is thicker than the optical member15. The long-side direction of the main surface is aligned with the X-axis direction, the short-side direction of the same is aligned with the Y-axis direction, and the thickness direction perpendicular to the main surface is aligned with the Z-axis direction. The light guide plate16is layered on the rear side of the optical member15, and arranged to be sandwiched between the optical member15and the chassis30. As illustrated inFIG. 4, the short-side dimension of light guide plate16is longer than the short-side dimensions of either the liquid crystal panel11or the optical member15. In the short-side direction, both edges (long-side direction) are arranged to protrude further outward than both edges of both the liquid crystal panel11and the optical member15(so as not to be overlapped when seen in plan view). The light guide plate16is arranged so as to be sandwiched in the Y-axis direction by the pair of LED units LU arranged at the two ends of the short-side direction, and so that light from the LEDs17at the two end portions of the short-side direction is guided. Further, the light guide plate16has a function for propagating therein light from the LEDs17at the two ends of the short-side direction and reorienting the light upwards towards the optical member15side (front side).

Of the main surfaces of the light guide plate16, the surface facing the front side (surface opposing the optical member15) is a light exiting surface16athat emits the internal light towards the optical member15and the liquid crystal panel11. Of the peripheral edge surfaces that are adjacent to the main surface of the light guide plate16, the two long-side edge surfaces that extend longitudinally along the X-axis direction (the two edge surfaces found at the two end portions of the short-side direction) are each arranged so as to directly oppose the respective LEDs17(LED substrate18) across a prescribed gap, thereby forming a pair of light incident faces16bon which the light generated by the LEDs17is incident. The light incident faces16bare parallel along the X-axis direction and the Z-axis direction (main plate surface of LED substrate18), and are substantially perpendicular to the light exiting surface16a. Further, an arrangement direction of the LEDs17and the light incident faces16bmatches the Y-axis direction, and is parallel to the light exiting surface16a.

As illustrated inFIG. 4, on the rear side of the light guide plate16, which is to say at the surface16con the opposite side to the light exiting surface16a(the surface facing the chassis30), is provided a reflective sheet20capable of reflecting the light emitted to the exterior on the rear side of the surface16cupwards towards the front side. The reflective sheet20is provided covering approximately the entire area of the surface16c. In other words, the reflective sheet20is provided interposed between the chassis30and the light guide plate16. The reflective sheet20is made of a synthetic resin, and the surface is white with excellent light-reflecting properties. The reflective sheet20has a short-side dimension that is larger than the short-side dimension of the light guide plate16and has edge portions that project beyond the light incident faces16btoward the LEDs17. As a result of the projecting portions of the reflective sheet20, light propagating at an angle towards the chassis30from the LEDs17can be efficiently reflected and oriented towards the light incident faces16bof the light guide plate16. Note also that at least one of the light exiting surface16aand the surface16cof the light guide plate16on the opposite side to the light exiting surface16ais patterned so as to have a prescribed internal distribution of reflective portions (not shown in the figures) that reflect the internal light and scattering portions that scatter the internal light. Consequently, the light emitted from the light exiting surface16ais controlled so as to be evenly distributed over the surface.

Next, the LEDs17that form a portion of the LED units LU, and the configuration of the LED substrate18and the heat dissipating member19will be described in the stated order. As illustrated inFIGS. 3 and 4, the LEDs17that form a portion of the LED unit LU are constructed by packing LED chips on a substrate portion fixedly attached to the LED substrate18. For LED chips mounted on the substrate portion, devices having a single main emission wavelength are use used. More specifically, devices that emit only blue light are used. Distributed in the resin material that seals the LED chips is a phosphor that emits light of a prescribed color under excitation by the blue light emitted from the LED chips. As a result, substantially white light is emitted over the entire body of material. Note that the phosphor may be an appropriate combination selected from among, for example, a yellow phosphor that emits yellow light, a green phosphor that emits green light, and a red phosphor that emits red light, or may be a single one of these. The LEDs17are of a so-called top surface-emitting type in which a surface on an opposite side to the mounting surface of the LED substrate18(in other words, the surface directly opposing the light incident face16bof the light guide plate16) forms a main light-emitting surface17a.

The heat dissipating member19that forms a portion of the LED units LU is made of a metal with excellent heat conductivity, such as aluminum or the like. As illustrated inFIGS. 3 and 4, the heat dissipating member19includes a light source attachment portion19awhere the LED substrate18is attached and a chassis contacting portion40that is in contact with the chassis30, the portions being arranged in a bent form having an approximate L-shape when seen in cross-section. The heat dissipating member19further includes a frame attachment portion19cattached to the frame13on the opposite side of the chassis contacting portion40to the light source attachment portion19a. The heat dissipating member19has a length dimension that is approximately the same as the length dimension of the above-described chassis30.

As illustrated inFIGS. 3 and 4, the light source attachment portion19ahas a plate-like form that is parallel to the plate surface of the LED substrate18and the light incident face16bof the light guide plate16. The long-side direction is aligned with the X-axis direction, the short-side direction is aligned with the Z-axis direction, and the thickness direction is aligned with the Y-axis direction. The LED substrate18is attached to an inward-facing plate surface of the light source attachment portion19a, which is to say the plate surface facing towards the light guide plate16. The light source attachment portion19ahas a long-side dimension that is approximately equal to the long-side dimension of the LED substrate18. However, the short-side dimension is larger than the short-side dimension of the LED substrate18. In addition, both short-side direction end portions of the light source attachment portion19aproject outwards along the Z-axis direction beyond the two end portions of the LED substrate18. The plate surface on the outer side of the light source attachment portion19a, which is to say the plate surface on the opposite side to the plate surface where the LED substrate18is attached, faces a later-described sidewall portion13bof the frame13. In other words, the light source attachment portion19ais provided interposed between the sidewall portion13bof the frame13and the light guide plate16. The light source attachment portion19arises towards the front side, which is to say towards the frame13side, along the Z-axis direction from a below-described chassis contacting portion40.

As illustrated inFIGS. 3 and 4, the chassis contacting portion40has a plate-like form that is parallel to the plate surface of a later-described bottom plate31(plate portion of the chassis) and height-difference portion33of the chassis30. The long-side direction of the chassis contacting portion40is aligned with the X-axis direction, the short-side direction is aligned with the Y-axis direction, and the thickness direction is aligned with the Z-axis direction. In the chassis contacting portion40, an end portion on the rear side of the light source attachment portion19a, which is to say the end portion on the chassis30side, protrudes inwards along the Y-axis direction. In contrast to the light source attachment portion19athat is arranged on the front surface side of the chassis30, the chassis contacting portion40is arranged on the rear side of the chassis30. The chassis contacting portion40is constructed with a long-side dimension that is approximately equal to that of the light source attachment portion19a, but a short-side dimension and thickness dimension is larger than those of the light source attachment portion19a, giving the chassis contacting portion40good heat dissipating properties. The plate surface on the front side of the chassis contacting portion40, which is to say the a front surface40athat faces the chassis30, is in surface contact with a rear surface of the height-difference portion33of the chassis30.

As illustrated inFIG. 4, the frame attachment portion19chas a plate-like form that extends along the rear surface of a later-described screw attachment portion21of the frame13. In the same way as the chassis contacting portion40, the frame attachment portion19chas a long-side direction that is aligned with the X-axis direction, a short-side direction aligned with the Y-axis direction and a thickness direction aligned with the Z-axis direction. The frame attachment portion19cis further provided with through holes19dthat are position-matched with screw holes21aof the screw attachment portion21to allow passage of a shaft portion of screw members SM. According to this configuration, the heat dissipating member19(housing member50) can be attached to the frame13via the screw members SM. The frame attachment portion19cis constructed to extend in a height-difference portion-like manner towards the chassis contacting portion40and so that an end portion thereof forms a single surface with an outer surface of the sidewall portion13b. With this configuration, the liquid crystal display device10will have a clean and well-designed look.

As illustrated inFIG. 3, the chassis30is formed by bending a plate member made of a metal such as iron, and, as whole, has a oblong form for covering substantially the entire light guide plate16from the rear side. It is preferable that iron be used as the material for the chassis30for reasons of cost and workability. The chassis30is provided with a plurality of groove portions37at the two end portions of the short-side direction. The configuration of the groove portions37is described in detail in a later section. The chassis30is combined with the heat dissipating members19to form the housing member50.

As illustrated inFIG. 4, the housing member50is constructed by arranging the pair of heat dissipating members19so as to oppose each other with the chassis contacting portions40pointing inwards, and arranging the two long-side margin areas of the chassis30(portions where the groove portions37are formed) on the respective front surfaces40aof the chassis contacting portions40of the heat dissipating members19. The housing member50has a C-like shape when viewed in a cross-section in the short-side direction of the chassis30(Y-axis direction), and forms a space for housing the main components of the backlight device12. The housing member50is formed from the metal heat dissipating members19and chassis30, and therefore provides a higher mechanical strength (stiffness) than a similar synthetic resin version would offer. Note also that since the heat dissipating members19are attached to the frame13, the combination of the heat dissipating members19and the chassis30can, for example, be achieved by sandwiching the chassis30between the heat dissipating members19and the frame13, or by fixing the later-described height-difference portions33to the chassis contacting portions40using screw fixtures or another well-known method.

The frame13is formed from the metal such as aluminum, and therefore provides both a higher mechanical strength (stiffness) and thermal conductivity than a similar synthetic resin version would offer. As illustrated inFIG. 3, the frame13as a whole forms an oblong frame so as to surround the display region of the display surface11cof the liquid crystal panel11. The frame13has a cross-section that is a substantially “L”-like shape and is formed from a panel holding portion13athat is parallel with the display surface11cof the liquid crystal panel11and holds the liquid crystal panel11from the front side, and a sidewall portion13bthat protrudes towards the rear side from an outer peripheral section of the panel holding portion13a. Of these portions, the panel holding portion13aenables formation of a frame-like shape at a peripheral section (non-display region, margin section) of the liquid crystal panel11, making it possible to hold the peripheral section of the liquid crystal panel11around approximately the whole circumference from the front side. The panel holding portion13ais sufficiently wide to cover, in addition to the peripheral section of the liquid crystal panel11, the peripheral sections of the optical member15and the light guide plate16, which are disposed outward in a radial direction of the liquid crystal panel11, and the LED units LU from the front side. The outer surface of the panel holding portion13a, which faces to the front side, (the surface on the opposite side to the surface opposing the liquid crystal panel11) is exposed to the exterior at the front side of the liquid crystal display device10in the same way as the display surface11cof the liquid crystal panel11, and, together with the display surface11cof the liquid crystal panel11, forms the front of the liquid crystal display device10. Moreover, the sidewall portion13bhas a substantially plate-like form that protrudes towards the rear side from the peripheral section (specifically the peripheral edge portion) of the panel holding portion13a. The sidewall portion13bmakes it possible to surround the entire periphery of the liquid crystal panel11, optical member15, light guide plate16, and LED units LU housed within the device, and to surround almost the entire periphery of the chassis30on the rear side. With the sidewall portion13b, the outer surface around the circumference of the liquid crystal display device10is exposed to the exterior around the circumference of the liquid crystal display device10, and forms a top surface, bottom surface, and both side surfaces of the liquid crystal display device10.

The frame-like frame13having the above-described basic configuration is assembled from four split frame parts formed corresponding to the frame sides (long-side parts and short-side parts). Note that the long-side split frame parts, which cover the LED units LU (seeFIG. 4) in addition to the liquid crystal panel11, the optical member15, and the light guide plate16, are formed to be wider than the short-side split frame parts, which do not cover the LED units LU.

As illustrated inFIGS. 4 and 5, the inner margin section of the panel holding portion13ais provided with panel cushioning material23on the rear side, which is to say the liquid crystal panel11side. The panel holding portion13ais constructed to hold the liquid crystal panel11from the front side via the panel cushioning material23. Further, a holding projection24that projects to the rear side is integrally formed at a section of the panel holding portion13aoverlapping the light incident face16bof the light guide plate16. The holding projection24has a light guide plate cushioning material24aattached to a distal end surface thereof and holds the light guide plate16from the front side via the light guide plate cushioning material24a. The holding projection24and the light guide plate cushioning material24aare members having light-shielding properties and are capable of suppressing light from the LEDs17that is heading directly towards the display panel side. The panel cushioning material23, the holding projection24, and the light guide plate cushioning material24aare formed to extend along the sides in the split frame parts that form the frame13, and are provided as split parts corresponding to the respective sides. When the split frame parts are assembled, the panel cushioning material23, the holding projection24, and light guide plate cushioning material24a, in the complete state, have frame-like forms that extend around the entire periphery of the panel holding portion13a.

As illustrated inFIGS. 4 and 5, the sidewall portion13bhas an integrally formed screw attachment portion21at a rear side end portion, which is to say at the end portion on the opposite side to the panel holding portion13a. The screw attachment portion21is formed by a portion that projects inwards from an inner side of the sidewall portion13b, and includes screw holes21athat open at the rear surface. Note that the screw attachment portion21is formed on the long-side sections of the frame13that form the frame13and not on the short-side sections.

In the following, the configuration of the chassis30that forms a main part of the present embodiment will be described in detail. At the two long-side direction edge portions of the backlight device12illustrated inFIG. 4, the chassis30and the heat dissipating members19are symmetrical. Thus, the following explanation includes a description of the configuration of the left-side edge portion (seeFIG. 5) while omitting descriptions of the right-side edge portion.

As illustrated inFIG. 5, the chassis30includes a bottom plate31that extends along the light guide plate16, a rising portion32that rises from the bottom plate31on an opposite side to the light guide plate16and forms a first corner portion36awith the bottom plate31, and a height-difference portion33that forms a second corner portion36bwith the rising portion32and provides a height-difference portion with respect to the bottom plate31. The chassis30further includes a falling portion34that falls from the height-difference portion33to the bottom plate31, forming a third corner portion36cwith the height-difference portion33and forming a fourth corner portion36dwith the bottom plate31. In the following explanation, the first to fourth corner portions36a,36b,36cand36dare collectively referred to as corner portions36.

As illustrated inFIG. 5, the dimensions of the rising portion32and the falling portion34are preferably approximately 2 to 10 times, and more preferably approximately 2 to 5 times the plate thickness of the plate material that forms the chassis30. With the above configuration, setting the dimensions of the rising portion32and falling portion34to be at least 2 times the plate thickness of the chassis30allows the corner portions36to be easily formed. Moreover, it is possible to provide separation of a least 2 times the plate thickness of the chassis30between the chassis contacting portion40and the bottom plate31and between the height-difference portion33and light guide plate16, and to prevent the inner parts of the backlight device12reaching high temperatures as a result of heat radiating from the chassis contacting portion40and the height-difference portion33. Further, in the present embodiment, the corner portions36formed in the chassis30increase the heat resistance of the chassis30. Thus, provided that the corner portions36are formed, an amount of heat conducted from the height-difference portion33to the bottom plate31will be reduced irrespective of the distance between the chassis contacting portion40and the bottom plate31. Hence, the dimensions of the rising portion32and the falling portion34can be set to no more than 10 times the plate thickness of the plate material forming the chassis30and even more preferably to no more than 5 times the plate thickness, while continuing to reduce the heat conducted from the height-difference portion33to the bottom plate31, thereby contributing to the reduction in the thickness of the backlight device12.

As illustrated inFIG. 5, the rising portion32, the height-difference portion33, and the falling portion34are provided by forming in the bottom plate31a concave groove portion37having an open box-like form when seen in cross-section. The groove portion37is, for example, formed by pressing the plate material made of a metal such as iron. The rising portion32and the falling portion34oppose each other and are interposed by an air layer. The first corner portion36aand the second corner portion36bare formed by bending the plate material to a substantial right angle. Similarly, the third corner portion36cand the fourth corner portion36dare formed by bending the plate material to a substantial right angle. As illustrated inFIG. 3, the corner portions36are provided extending from one edge of the chassis30to the other in the long-side direction of the chassis30. According to the above configuration, the stiffness of the chassis30in the long-side direction can be increased by the groove portion37and the flatness of the plate surface of the chassis30can be increased.

As illustrated inFIG. 3, a plurality of the groove portions37are provided (in the present embodiment a total of eight grooves, four at each edge portion). The plurality of groove portions37are aligned parallel to the edge portion of the chassis30. The groove portions37are distributed with an equal spacing in positions overlapped by the chassis contacting portions40of the heat dissipating members19. The width dimension between the groove portions37is larger than the width dimension of the groove portions37(distance separating the rising portion32and falling portion34). In other words, a width dimension of the bottom plate31disposed between the groove portions37is larger than a width dimension of the height-difference portions33. In the plurality of groove portions37, the rising portion32, the height-difference portion33, the falling portion34, and the bottom plate31is arranged in a repeating pattern so as to have an undulating profile when seen in cross-section. The height-difference portions33are arranged to be coplanar. The bottom plate31is arranged to be coplanar and extend parallel to the height-difference portions33. According to the above configuration, the area of the sections at which the chassis30is in contact with the light guide plate16and the chassis30is in contact with the heat dissipating member19is reduced. At the same time, the light guide plate16, the chassis30, and the heat dissipating members19are parallel and in stable contact.

As illustrated inFIG. 4, sections of the chassis30other than the groove portions37are denoted as bottom plate31. In other words, a central portion in the short-side direction of the chassis30is denoted as the bottom plate31. Hence, the rear surface40bof the chassis contacting portion40of the heat dissipating member19is provided with an even larger level difference with respect to the bottom plate31at the central portion of the chassis30than the level difference going from the height-difference portion33to the rear surface side. According to this configuration, heating of the region in proximity to the central portion of the chassis30by the heat dissipated from the rear surface40bof the chassis contacting portion40can be suppressed to a greater extent than in the case when the rear surface40bof the chassis contacting portion40and the rear surface at the central portion of the chassis30are coplanar. Moreover, since the housing member50formed from the chassis30and the heat dissipating members19is constructed with the central portion of the rear surface (bottom plate31) recessed from the rear surface40bof the chassis contacting portion40, other components of the backlight device12can be housed in the recessed section.

The present embodiment has the above-described structure. Next, aspects of assembly and the effects of the embodiment will be described. To manufacture the liquid crystal display device10, separately manufactured components (the frame13, the chassis30, the liquid crystal panel11, the optical member15, the light guide plate16, the LED units LU, and the like) are attached to one another. During manufacturing, spaces are formed between the sidewall portion13bof the frame13and the light source attachment portion19aof the heat dissipating members19, and a layer of air is interposed therein. At assembly, the components are all attached in an upside down state, which is the state illustrated inFIG. 4but with the Z-axis direction reversed. First, the frame13from the components is set up on a work stand not shown in the drawings with the rear side surface facing vertically upwards.

Next, the liquid crystal panel11, the optical members15, and the chassis30are layered in the stated order, directly on the rear side surface of the frame13. Then, the LED units LU, each formed in advance by combining the LEDs17, the LED substrate18, and the heat dissipating member19, are attached to the frame13. The LED units LU are mounted so that the LEDs17face towards the center (inside) of the frame13and the chassis contacting portions40of the heat dissipating members19are seated on the height-difference portions33of the chassis30. Here, spaces corresponding to the heights of the rising portion32and falling portion34are formed between the chassis contacting portions40and the bottom plate31, and layers of air are interposed between the chassis contacting portions40and the bottom plate31. With frame attachment portion19cof the heat dissipating member19arranged to face the screw attachment portion21of the frame13, through holes19b1provided in the frame attachment portion19ccommunicate with the screw holes21ain the screw attachment portion21. Next, the screw members SM are inserted into the through holes19dfrom the rear side and screwed into the screw holes21aof the screw attachment portion21. The LED units LU are held in a state of attachment to the screw attachment portions21by the screw members SM.

This completes the attachment of the liquid crystal display unit LDU. Thereafter, the stand attachment members STA and the boards PWB, MB and CTB are attached to the rear surface side of the liquid crystal display unit LDU. Then, the liquid crystal display device10and the television receiver TV are produced by attaching the stand ST and the cover member CV. In the liquid crystal display device10manufactured in the manner described, the liquid crystal panel11and the optical members15are layered directly on one another. Hence, in comparison to devices having a panel receiving member interposed between the liquid crystal panel11and the optical members15to prevent contact, the number of parts and the amount of assembly is reduced. Thus, in addition to promoting thinner and lighter liquid crystal display devices, the liquid crystal display device10also serves to reduce production costs.

When the liquid crystal display device10manufactured in the manner described is powered ON, the liquid crystal panel11is supplied with power from the power supply board PWB, and with signals from the control board CTB via the substrate27and the flexible substrate26(drivers), and the driving of the LEDs17that make up the backlight device12is controlled accordingly. The light from the LEDs17is guided by the light guide plate16to pass through the optical member15, and is thereby converted to uniform planar light. Thus, the liquid crystal panel11is illuminated by uniform planar light and prescribed images are displayed on the liquid crystal panel11. The following describes the effects of the backlight device12in more detail. As illustrated inFIG. 4, when the LEDs17are lit, the light emitted from the LEDs17is incident on the light incident faces16bof the light guide plate16. The light incident on the light incident faces16bis totally reflected by the boundary surfaces with the external air layer of the light guide plate16or by the reflective sheet20, and is thereby propagated within the light guide plate16. In this process, the light is reflected or scattered by reflective portions or scattering portions not shown in the drawings and emitted from the light exiting surface16a, thereby illuminating the optical member15.

However, as the liquid crystal display device10is used, the LEDs17illuminate and generate heat. The heat generated by the LEDs17is initially transmitted to the light source attachment portions19aof the heat dissipating members19via the LED substrates18. The heat is then conducted from the light source attachment portions19ato the chassis contacting portions40and efficiently dissipated by the air layers on rearward side of the rear surfaces40bof the chassis contacting portions40. Thus, the above-described configuration promotes heat dissipation from the backlight device12. In addition, since each chassis contacting portion40has the front surface40athat is in contact with the height-difference portions33of the chassis30, a portion of the heat is transmitted from the chassis contacting portion40to the height-difference portions33.

In the backlight device12according to the present embodiment, the chassis30is made of metal and the first corner portions36aand second corner portions36bare present between the height-difference portions33and the bottom plate31on the rising portion32side. Hence, the conduction of heat from the height-difference portion33side to the bottom plate31side is more difficult than when the height-difference portions33and bottom plate31form a continuing flat plane. Similarly, the third corner portions36cand the fourth corner portions36dare present on the falling portion34side, inhibiting the conduction of heat from the height-difference portion33side to the bottom plate31side. Consequently, in comparison to the case in which the height-difference portions33and the bottom plate31form a continuing flat surface, the amount of heat transmitted from the chassis contacting portions40of the heat dissipating members19to the bottom plate31is reduced, and the amount of heat dissipated from the chassis contacting portions40to the rear surface side is increased. According to this configuration, the backlight device12can appropriately dissipate internal heat to the rear surface side.

As described above, the backlight device12includes an LED17; a light guide plate16that opposes the LEDs17and includes a light incident face16bwhere light from the LEDs17is incident and a light exiting surface16athat emits the incident light; an optical member15arranged on the light exiting surface16aside of the light guide plate16; a chassis30formed by bending a metal plate material and arranged on an opposite side of the light guide plate16to the light exiting surface16a, the chassis30including a bottom plate31that extends along the light guide plate16, a rising portion32that rises from the bottom plate31on an opposite side to the light guide plate16and forms a first corner portion36awith the bottom plate31, and a height-difference portion33that forms a second corner portion36bwith the rising portion32and provides a height-difference portion with respect to the bottom plate31; and a heat dissipating member19that dissipates heat of the LEDs17, the heat dissipating member19including a light source attachment portion19ato which the LEDs17are attached and a chassis contacting portion40that is contiguous with the light source attachment portion19aand is in contact with the height-difference portion33from the opposite side to the light guide plate16.

In the above-described backlight device12, the first corner portion36aand the second corner portion36bare formed between the bottom plate31and the height-difference portion33in the chassis30by bending the metal material. In this process, since warping and cracking occur when bending a metal, corner portions formed by bending the metal material have a higher thermal resistance than flat portions. Hence, in the above-described backlight device12, the conduction of heat from the height-difference portion33to the bottom plate31is more difficult than when the height-difference portion33and the bottom plate31form a continuous flat plane.

Also, since the chassis contacting portion40of the heat dissipating member19is in contact with the height-difference portion33from the opposite side to the light guide plate16, heat is dissipated via the chassis contacting portion40. In comparison to the case in which the height-difference portion33and the bottom plate31form a continuous flat surface, the amount of heat dissipated from the chassis contacting portion40on the chassis30side is reduced, and the amount of heat dissipated from the opposite side to the chassis30(the rear surface40bside) is increased. As a result, it becomes more difficult for the heat from the heat dissipating member19to reach the optical member15, which is disposed on the chassis30side with respect to the chassis contacting portion40. Hence, the generation of wrinkling in the optical member15due to thermal expansion of the section of the optical member15overlapping the chassis contacting portion40can be suppressed.

Specifically, in the present embodiment, as illustrated inFIG. 5, the edge of the optical member15on the LEDs17side overlaps approximately ⅔ of the chassis contacting portion40. Here, if the chassis contacting portion40were to be arranged on the front side of the chassis30(light guide plate16side), heat from the chassis contacting portion40would be transmitted to the optical member15via the reflective sheet20and the light guide plate16. Moreover, if the chassis contacting portion40were arranged on the rear side of the chassis30(opposite side to the light guide plate16) but the configuration did not include the rising portion32and the height-difference portion33, heat from the chassis contacting portion40would be easily transmitted from the chassis contacting portion40to the chassis30, and then via the chassis30, the reflective sheet20, and the light guide plate16to the optical member15. However, in the present embodiment, the chassis contacting portion40is provided on the rear side of the chassis30(opposite side to the light guide plate16), and the chassis30includes both the rising portion32and the height-difference portion33. Thus, the thermal resistance of the first corner portion36aand the second corner portion36bis high, and heat is not easily conducted from the height-difference portion33to the bottom plate31. Hence, with an extremely simple configuration in which the rising portion32and the height-difference portion33are formed by bending the chassis30, it is made more difficult for heat to be transferred to the edge of the optical member15.

Further, in the backlight device12of the present embodiment, the chassis30further includes a falling portion34that falls from the height-difference portion33to the bottom plate31, forming a third corner portion36cwith the height-difference portion33and forming a fourth corner portion36dwith the bottom plate31. The rising portion32, the height-difference portion33, and the falling portion34are provided by forming a concave groove portion37in the bottom plate31. With the above configuration, the height-difference portion33can be supported with respect to the bottom plate31by the rising portion32and the falling portion34, and the strength of the height-difference portion33can be set to be high. Further, since the third corner portion36cand the fourth corner portion36dare formed between the height-difference portion33and the bottom plate31by bending the metal material, heat is not easily conducted from the height-difference portion33to the bottom plate31via the falling portion34.

In the backlight device12of the present embodiment, a plurality of the groove portions37are provided and the plurality of groove portions37are aligned parallel to the edge of the chassis30. According the above configuration, an area of plate surface of the height-difference portions33is smaller than in the case that the height-difference portion33is formed by a single groove portion37, with the height-difference portions33being in contact with the chassis contacting portion40over a wide area with gaps therebetween. Hence, the chassis30can be stably in contact with the heat dissipating members19with reduced heat being transferred from the chassis contacting portion40to the height-difference portions33.

In the backlight device12of the present embodiment, the rising portion32and the falling portion34are interposed by an air layer. According to the above configuration, the height-difference portions33and the light guide plate16are interposed by a layer of air and can therefore be thermally insulated from each other.

Further, in the backlight device12of the present embodiment, the first corner portion36aand the second corner portion36bare formed by bending the plate material to a substantial right angle. According to the above configuration, a higher level of the thermal insulation can be achieved between the first corner portion36aand the second corner portion36band the conduction of heat from the height-difference portion33to the bottom plate31can, advantageously, be made even more difficult, than in the case that the material is bent to an obtuse angle.

In the backlight device12of the present embodiment, the chassis30can be made of metal. According the above configuration, it is generally possible to contribute to reducing manufacturing costs through the use of a cheaper metal while still suppressing wrinkling, deflection and the like in the optical member15. Such effects are possible even when the chassis30made of a metal with lower thermal conductivity than aluminum or the like is used.

The liquid crystal display device10(display device) of the present embodiment includes the above-described backlight device12and the liquid crystal panel11(display panel) that performs display using the light from the backlight device12.

According to the above liquid crystal display device10, the backlight device12that supplies light to the liquid crystal panel11suppresses deformation such as wrinkling and deflection of the optical member15. Hence, it is possible to realize a display having excellent display quality.

The liquid crystal display device10of the present embodiment further includes the frame13arranged on the display surface side of the liquid crystal panel11and housing, in a sandwich with the heat dissipating members19, the liquid crystal panel11, the LEDs17, the light guide plate16, and the chassis30. The heat dissipating members19include the frame attachment portion19cattached to the frame13on the side of the chassis contacting portion40opposite to the light source attachment portion19a. According to the above configuration, heat from the light source attachment portion19ais dissipated by the chassis contacting portion40. Hence, heat is less easily conducted to the frame attachment portion19cside, and the transmission of the heat from the heat dissipating member19from the frame attachment portion19cto the frame13can be suppressed.

In the liquid crystal display device10of the present embodiment, the frame13has an L-shape when viewed in cross-section, and includes a panel holding portion13athat holds the liquid crystal panel11from the display surface11cside, and a sidewall portion13bthat protrudes from an outer side section of the panel holding portion13atowards an opposite side to the display surface side. The light source attachment portion19afaces the sidewall portion13band an air layer is interposed between the light source attachment portion19aand the sidewall portion13b. According to the above configuration, the light source attachment portion19aand the sidewall portion13bcan be thermally insulated from each other, and the transmission of the heat from the heat dissipating member19from the light source attachment portion19ato the frame can be suppressed even further.

In the present embodiment, the liquid crystal panel11is provided as an example of a display panel. Display devices such as the as the liquid crystal display device10can be applied in various applications, including televisions and PC displays, and are especially suitable for large screen applications.

Embodiment 2 of the present invention is described below based onFIG. 6. Embodiment 2 differs from Embodiment 1 in that heat dissipating fins141are provided on the chassis contacting portion140of the heat dissipating members119. Repetitious descriptions of structures, operations and effects similar to the above described Embodiment 1 will be omitted.

The chassis contacting portion140is provided with heat dissipating fins141on a surface on the opposite side to the chassis30(rear surface40b) at a section that overlaps the height-difference portions33. The heat dissipating fins141are integrally provided with the chassis contacting portion140and are formed by cutting a plurality of parallel grooves in the plate-like chassis contacting portion140. Specifically, the chassis contacting portion140is constructed so that a thickness dimension at portions where the heat dissipating fins141are not provided is the same as the protruding dimension of the heat dissipating fins141. According to the above configuration, portions where the heat dissipating fins141are not provided secure the cross-sectional area of the chassis contacting portion140, improving the ease with which heat is conducted from sections near the light source attachment portion19ato sections far away from the same.

The heat dissipating fins141are formed by a plurality of ribs that extend along corner portions142formed between the light source attachment portion19aand the chassis contacting portion140. In the present embodiment, three ribs are provided in correspondence to each height-difference portion33. According to the above configuration, the surface area of the chassis contacting portion140can be increased, thereby promoting heat dissipation from the chassis contacting portion140.

In a backlight device112of the present embodiment, the chassis contacting portion140is provided with the heat dissipating fins141on the surfaces on the opposite side to the chassis30at sections overlapping with the height-difference portions33. According to the above configuration, heat dissipation efficiency can be improved on the side of the chassis contacting portion140opposite to the chassis30(rear surface40bside) at sections overlapping the height-difference portions33. Hence, transmission of heat from the chassis contacting portion140to the chassis30can, advantageously, be further reduced.

Moreover, in the backlight device112of the present embodiment, the heat dissipating member119is formed so that the light source attachment portion19aand the chassis contacting portion140form an L-shape when seen in cross-section. The heat dissipating fins141are formed by the plurality of ribs that extend along the corner portions142formed between the light source attachment portion19aand the chassis contacting portion140. According to the above configuration, the heat dissipating fins141can be formed simultaneously with the chassis contacting portion140and the light source attachment portion19awhen extruding the heat dissipating member119.

Embodiment 3 of the present invention is described below based onFIG. 7. Embodiment 3 differs from Embodiment 1 in that a single groove portion237is provided at edge portions of a chassis230. Repetitious descriptions of structures, operations and effects similar to the above described Embodiment 1 will be omitted.

A single groove portion237is provided at each first and second end portions of the short-side direction of the chassis230, such that two groove portions237are provided in the chassis230as a whole. The groove portions237are arranged along edge portions of the chassis230. The groove portions237are arranged in positions overlapping the chassis contacting portions40of the heat dissipating members19, and a width dimension of the height-difference portion33is set to be slightly smaller that the width dimension of the chassis contacting portion40. According to the above configuration, the rising portion32, the height-difference portion33, and the falling portion34can be provided while reducing the number of bends in the chassis230.

Other Embodiments

The present invention is not limited the embodiments explained in the above descriptions and drawings. For example, the following embodiments are also included in the technological scope of the present invention.

(1) In the above-described embodiments, examples in which the chassis includes groove portions were described. However, configurations in which the chassis does not have a falling portion, but rather has a height-difference portion form including the bottom plate, the rising portion, and the height-difference portion are also included in the present invention.

(2) In the above-described embodiments, examples in which the first corner portion and second corner portion and the third corner portion and fourth corner portion were formed by bending a plate member to substantial right-angles were described. However, the bending angle at the corner portions is not limited to being a right angle.

(3) In the above-described embodiments, examples in which the height-difference portions were provided along both long-side direction edge portions of the chassis were described. However, it is sufficient that the height-difference portions are arranged in proximity to the LED units, and the arrangement and configuration of the height-difference portion in the chassis is not otherwise limited.

(4) In the above-described embodiments, examples in which two corner portions were provided between the bottom plate and the height-difference portion were described. However, a plurality of height-difference portions formed using three or more corner portions may be provided between the bottom plate and the height-difference portion.

(5) In addition to the above-described embodiments, appropriate modifications can also be made to the material, form, configuration of the chassis, to the arrangement or form of the height-difference portion or groove portions, or the like.

(6) In addition to the above-described embodiments, appropriate modifications can also be made to the form and configuration of the heat dissipating members. For example, a configuration may be used in which a member of lower thermal conductivity than the heat dissipating members, made of polycarbonate or the like, is provided on the chassis-side surface of the chassis contacting portion.

(7) In the above-described embodiments, examples were described in which the heat dissipating members were exposed at the rear surface, but the heat dissipating members may instead be covered by a cover member or the like. Alternatively, to promote heat dissipation form the rear surface of the heat dissipating members, a configuration including fins or the like on the rear surface of the heat dissipating member to generate air currents may be used.

(8) In the above-described embodiments, examples of a liquid crystal display device using the liquid crystal panel as a display panel were described, but the present invention can also be applied to a display device using other types of display panel.

(9) In above-described embodiments, examples were described in which the LED units (LED substrates) were arranged to face each other at respective long-side edge portions of the light guide plate. However, configurations in which the LED units are arranged to face each other at respective short-side edge portions of the light guide plate are also included in the present invention.

(10) Besides the example of (9), arrangements in which opposing LED unit (LED substrate) pairs were arranged at both long-side edge portions and short-side end portions of the light guide plate so as to provide a total of four LED units, and in which a single LED unit is provided at one of the long-side edge portions or one of the short-side end portions are also included in the present invention. Moreover, arrangements in which LED units are provided in opposition at any three sides of the light guide plate are also included in the present invention.

(11) In above-described embodiments, an arrangement was described in which a single LED unit (LED substrate) was disposed on a given side of the light guide plate. However, arrangements in which two or more LED units are provided on a given side of the light guide plate may also be used.

(12) In above-described embodiments, an arrangement was described in which LEDs were used as the light source, but a different light source such as organic EL is also possible.

The above has described embodiments of the present invention in detail, but these are to be construed as mere examples and do not limit the scope of the patent claims. The technologies of the patent claims include arrangements resulting from various modifications and changes to the examples described in the above examples.

DESCRIPTION OF REFERENCE CHARACTERS