Patent Application
20130033652
The present invention relates to a lighting device, a display device, and a television receiver.
In recent years, display elements of an image display device, such as a television receiver, are in a transition from the conventional cathode-ray tube to flat display panel, such as liquid crystal panel or plasma display panel, making it possible to provide a flat image display device. The liquid crystal panel of a liquid crystal display device does not emit light by itself, and therefore the display device requires a backlight unit as a separate lighting device. The backlight unit may be generally categorized by mechanism into a direct type and an edge light type. In order to further reduce the thickness of the liquid crystal display device, it is preferable to use an edge light backlight unit, as described in Patent Document 1 indicated below.
The backlight unit described in this Patent Document 1 is provided with a light guide plate; a LED disposed in an opposed manner with respect to an end of the light guide plate; a LED board on which the LED is mounted; and a lead frame electrically connecting and mechanically fixing the LED to a liquid crystal drive circuit board.
In the above backlight unit, the LED board is disposed in a chassis, and mechanically fixed by soldering the lead frame to the liquid crystal drive circuit board. This configuration may lead to the following problem. When the thermal environment within the backlight unit is varied, the LED board may be expanded or contracted due to thermal expansion or thermal contraction. When the LED board is rigidly fixed by the lead frame, the expansion or contraction at the fixed portion is restricted, whereby the LED board may be readily deformed by warping or deflection, for example. When such deformation occurs in the LED board, the LED mounted thereon is displaced relative to the end of the light guide plate. As a result, variations are caused in the efficiency with which light from the LED becomes incident on the light guide plate, possibly resulting in uneven brightness in the output light from the backlight unit.
The present invention was made in view of the above circumstances and an object of the present invention is to suppress uneven brightness in a preferred manner.
A lighting device according to the present invention includes a light source board including a light source; a light guide member having an end portion facing the light source; a chassis housing the light source board and the light guide member; a holding member fixed to the chassis with having the light source board therebetween; and a restricting portion restricting positional relationship of the holding member with respect to the light source board to provide a gap between the holding member and the light source board.
With this configuration, when the holding member is fixed to the chassis, the light source board is provided between the holding member and the chassis, and accordingly, the light source faces the end portion of the light guide member. Because the positional relationship of the holding member with respect to the light source board is restricted by the restricting portion that provides the gap between the holding member and the light source board, the light source board is allowed to be easily expanded or contracted by thermal expansion or thermal contraction due to changes in thermal environment. Thus, deformation such as warping or deflection in the light source board is unlikely to occur, resulting in the stable positional relationship between the light source on the light source board and the light guide member. Accordingly, the light incident efficiency from the light source on the light guide member can be stabilized, thereby making uneven brightness less likely to occur in the output light.
Preferably, the embodiments of the present invention may include the following configurations.
(1) The restricting portion may be disposed at a position overlapping with the light source board in a plan view, and the light source board may have a through hole through which the restricting portion is inserted. With this configuration, by inserting the restricting portion into the through hole, the light source board can be positioned with respect to the restricting portion.
(2) The holding member may include a main body portion and a fixing portion, and the main body and the chassis has the light source board therebetween, and the fixing portion protrudes from the main body portion toward the chassis and is fixed to the chassis. Both the fixing portion and the restricting portion are inserted through the through hole. With this configuration, both the restricting portion and the fixing portion can be inserted into the through hole, and this simplifies the structure of the light source board and the manufacturing cost for the light source board can be decreased compared to the case if the light source board is provided with separate through holes for the fixing portion and the restricting portion respectively.
(3) The restricting portion may be disposed adjacent to the fixing portion in a plan view. With this configuration, the size of the through hole can be decreased compared to if the restricting portion and the fixing portion are spaced apart from each other on the main body portion.
(4) The through hole may have a peripheral edge and the peripheral edge and a circumferential surface of the restricting portion have a clearance therebetween. With this configuration, the displacement of the light source board relative to the restricting portion can be allowed within the range of the clearance between the through hole and the circumferential surface of the restricting portion. Thus, when the light source board is expanded or contracted by thermal expansion or thermal contraction, deformation such as warping or deflection in the light source board is lee likely to occur. Accordingly, the development of uneven brightness can be prevented in a more preferred manner.
(5) The restricting portion may be integrally provided on a chassis side, the restricting portion protruding toward the holding member and abutted against the holding member. In this way, by abutting the restricting portion integrally provided on the portion chassis side against the holding member, the positional relationship of the holding member with respect to the light source board can be restricted in a good manner.
(6) The restricting portion may be integrally provided to the chassis. In this way, because the restricting portion is integrally provided to the chassis, the number of components and assembly steps can be decreased compared to if the restricting portion is provided as a separate component from the chassis, thus contributing to cost reduction.
(7) The restricting portion may be disposed at a position overlapping with the light source board in a plan view, and the light source board may have a through hole through which the restricting portion is inserted. With this configuration, when the light source board is disposed on the chassis, the restricting portion is inserted into the through hole, whereby the light source board can be positioned with respect to the chassis. In other words, the light source board can be positioned with respect to the chassis prior to attaching the holding member.
(8) The holding member may include a main body portion and a fixing portion, and the main body portion and the chassis may have the light source board therebetween, and the fixing portion may protrudes from the main body portion toward the chassis to be fixed to the chassis. The chassis may have an attaching hole through which the fixing portion is inserted. The restricting portion may be disposed on a peripheral edge portion of the attaching hole. With this configuration, when the fixing portion is inserted into the attaching hole of the chassis, the fixing portion can be guided by the restricting portion disposed on the edge of the attaching hole. Thus, improved workability can be achieved when attaching the holding member.
(9) The restricting portion may be formed in a ring shape extending along the peripheral edge portion of the attaching hole. With this configuration, the strength of the restricting portion can be maintained high, leading to reliable restriction in the positional relationship of the holding member with respect to the light source board.
(10) The restricting portion may be provided separate from the chassis and the holding member, and disposed between the chassis and the holding member. With this configuration, because the restricting portion is provided separate from the chassis and the holding member, the degree of freedom in the material or shape of the restricting portion, for example, can be increased.
(11) The restricting portion may be integrally provided on a holding member side to protrude toward the chassis and abut against the chassis. With this configuration, by abutting the restricting portion integrally provided on the holding member side against the chassis, the positional relationship of the holding member with respect to the light source board can be restricted in a good manner.
(12) The restricting portion may be integrally provided to the holding member. With this configuration, the number of components and assembly steps can be decreased compared to if the restricting portion is provided as a separate component from the holding member, thus contributing to cost reduction.
(13) The holding member may include a main body portion and a fixing portion, the main body portion and the chassis may have the light source board therebetween, and the fixing portion protrudes from the main body portion toward the chassis to be fixed to the chassis. The restricting portion may be provided to the main body portion. With this configuration, when the fixing portion is fixed to the chassis, the light source board sandwiched between the main body portion and the chassis can be held in a preferred manner. At this time, the positional relationship of the holding member with respect to the light source board can be appropriately restricted by the restricting portion provided to the main body portion.
(14) The restricting portion may be formed continuously from the fixing portion. With this configuration, the strength of the restricting portion and the fixing portion can be increased compared to if the restricting portion is independent from the fixing portion.
(15) The restricting portion may surround the fixing portion. With this configuration, the strength of the restricting portion and the fixing portion can be further increased.
(16) The restricting portion may include a plurality of the restricting portions and the restricting portions may be disposed on a circumferential surface of the fixing portion intermittently with respect to a circumferential direction thereof. With this configuration, the material cost for the holding member can be decreased compared to if the restricting portion surrounds the fixing portion.
(17) The restricting portions may be disposed on the circumferential surface of the fixing portion at substantially equal angular intervals. With this configuration, the plurality of restricting portions disposed at substantially equal angular intervals can be stably abutted against the chassis, to more appropriately restrict the positional relationship of the holding member with respect to the light source board.
(18) The holding member may be made of a synthetic resin material. With this configuration, structural design and formation in manufacturing the holding member to which the restricting portion is integrally provided can be facilitated.
(19) The restricting portion may be made of a metal material. With this configuration, a smaller linear coefficient of expansion and higher heat conductivity can be generally obtained compared to the case if the restricting portion is made of a synthetic resin. Thus, expansion or contraction of the restricting portion due to thermal expansion or thermal contraction less likely to occur, resulting in more reliable restriction of the positional relationship between the holding member and the light source board. In addition, the heat generated by the light source on the light source board can be efficiently transmitted via the restricting portion to the chassis. Therefore, excellent heat dissipation property of the light source can be obtained.
(20) The light source board may have an elongated shape having a long side extending along the end portion of the light guide member. The elongated light source board tends to be expanded or contracted by thermal expansion or thermal contraction more in the long side direction, i.e., along the end of the light guide member, than in the short side direction. However, the expansion or contraction of the light source board is allowed due to a gap provided by the restricting portion. Therefore, the deformation of the light source board can be suppressed in a preferred manner and a change in the positional relationship between the light source and the light guide member is less likely to occur.
(21) The lighting device may further include a supporting portion supporting one of elongated ends of the light source board, and the supporting portion and the chassis may support the one elongated end therebetween. With this configuration, the gap is provided between the holding member and the light source board and the supporting portion and the chassis have the light source board therebetween. Accordingly, clattering of the light source board is less likely to occur. On the other hand, the other one of the elongated ends of the light source board is not supported by the supporting portion. Therefore, the expansion or contraction of the light source board due to thermal expansion or thermal contraction can be appropriately allowed, preventing deformation of the light source board, such as warping or deflection.
(22) The supporting portion may be disposed between the light guide member and the light source board. With this configuration, even when thermal expansion is caused in the light guide member, the positional relationship of the light guide member with respect to the light source board and the light source can be restricted by the supporting portion disposed between the light guide member and the light source board. Thus, the light incident efficiency from the light source on the light guide member can be stabilized, preventing uneven brightness of output light.
(23) the light source may include a plurality of the light sources and the light sources may be arranged on the light source board along the long side. With this configuration, a plurality of the light sources can be efficiently disposed on the light source board, which is preferable for obtaining high brightness.
(24) The holding member may be disposed between the adjacent light sources. With this configuration, the space between the adjacent light sources can be effectively utilized. Further, the holding member is less likely to obstruct the light emitted from the light sources.
(25) The holding member may include a main body portion and a fixing portion, and the holding member and the chassis may have the light source board therebetween, and the fixing portion may protrudes from the main body portion toward the chassis to be fixed to the chassis. With this configuration, when the fixing portion is fixed to the chassis, the light source board provided between the main body portion and the chassis can be appropriately held.
(26) The fixing portion may penetrate the chassis and be stopped by a surface of the chassis opposite to a surface on which the light source board is provided. With this configuration, by locking the fixing portion penetrating the chassis on the chassis, the holding member and the light source board can be fixed at low cost and easily without using a separate fixing means, such as an adhesive.
(27) The fixing portion may include an elastically deformable locking part penetrating the chassis and locked on a surface of the chassis opposite to a surface on which the light source board is provided. The holding member may be configured with a first component including the main body portion and the fixing portion, and a second component attached to the first component and restricting elastic deformation of the elastic locking part. When attaching the holding member to the chassis, the second component is mounted on the first component which is previously attached to the chassis, whereby the elastic deformation of the elastic locking part penetrating the chassis and locked on the other side from the light source board is restricted. Thus, the holding member is retained in an anti-falling state. When detaching the holding member from the chassis, the second component is detached from the first component to allow the elastic return of the elastic locking part into original shape, and then the first component is detached. By thus attaching or detaching the second component to or from the first component, the holding member can be easily attached to or detached from the chassis without using a special tool. Therefore, excellent workability can be obtained. Particularly, excellent working efficiency can be obtained during a disassembly operation for maintenance or discard of the lighting device.
(28) The light source and the end portion of the light guide member facing the light source may be spaced apart from each other with a space therebetween, and the lighting device may further include a pair of reflection members having the space therebetween. With this configuration, the light emitted from the light source is repeatedly reflected by the pair of reflection members within the space between the light source and the opposed end of the light guide member thereto. Therefore, the light can become incident on the end of the light guide member efficiently. Thus, the light use efficiency can be increased.
Next, to solve the above problem, a display device of the present invention includes the lighting device described above and a display panel providing a display by utilizing the light from the lighting device.
The display device can provide a display with excellent display quality because uneven brightness is less likely to occur in the output light produced by the lighting device supplying light to the display panel.
The display panel may be a liquid crystal panel including a pair of substrates with liquid crystal sealed between. The display device as a liquid crystal display device may be applied to various purposes, including displays for televisions and personal computers, and is particularly suitable for large screens.
According to the present invention, uneven brightness is less likely to occur.
A first embodiment of the present invention will be described with reference to
As illustrated in
The liquid crystal panel 11, as shown in
The backlight unit 12, as shown in
The chassis 14 is made of a metal plate, such as an aluminum plate or an electrogalvanized steel plate (SECC). As shown in
The optical members 15, as shown in
The frame 16, as shown in
The LED 17 may include LED chips sealed on a board portion fixed on the LED board 18 using a resin material, as illustrated in
The LED boards 18 are made of a synthetic resin (such as a glass epoxy resin) with a white surface for excellent light reflectivity. As shown in
The LED boards 18, as shown in
The light guide member 19 is made of a substantially transparent (capable of high light transmission) synthetic resin material (such as acrylic) with a refractive index higher than air. The light guide member 19, as shown in
The light guide member 19 has a substantially flat plate-like shape extending along the respective plate surfaces of the bottom plate 14a of the chassis 14 and the optical members 15, with main plate surfaces parallel with the X-axis direction and the Y-axis direction. Of the main plate surfaces of the light guide member 19, the one facing the front side constitutes a light output surface 19a outputting the internal light toward the optical members 15 and the liquid crystal panel 11. Of the outer peripheral end surfaces of the light guide member 19 adjacent to the main plate surfaces, the elongated end surfaces on the long sides along the X-axis direction are opposed to the LED 17 (the LED boards 18) via a predetermined interval, constituting light incident surfaces 19b on which the light emitted from the LED 17 become incident. On the front side of the space between the LEDs 17 and the light incident surfaces 19b, the first reflection sheet 20 is disposed, as shown in
A light guide reflection sheet 22, configured to reflect the light within the light guide member 19 up toward the front side, covers substantially the entire area of a surface 19c of the light guide member 19 on the opposite side to the light output surface 19a. In other words, the light guide reflection sheet 22 is sandwiched between the bottom plate 14a of the chassis 14 and the light guide member 19. On at least one of the light output surface 19a of the light guide member 19 and the opposite surface 19c thereto, a reflecting portion (not shown) reflecting the internal light or a scattering portion (not shown) scattering the internal light is patterned with a predetermined in-plane distribution. Thereby, the output light from the light output surface 19a is controlled to have a uniform distribution within its surface.
Next, the holding members 23 will be described in detail. The holding members 23, which may be made of a metal such as aluminum or iron, are so-called screw members. As shown in
The LED boards 18 have through holes 18a into which the fixing portions 25 of the holding members 23 can be inserted. The long-side side plates 14b of the chassis 14 have attaching holes 14c in which the fixing portions 25 can be threadedly fixed. By screwing the fixing portion 25 of the holding member 23 onto the respective attaching holes 14c of the long-side side plates 14b of the chassis 14 via the through hole 18a of the LED board 18, the LED board 18 can be held between the main body portion 24 and each of the long-side side plates 14b of the chassis 14. The attaching holes 14c have roughly the same diameter as the outer diameter of the fixing portions 25. The holding members 23 are provided at two positions on each of the LED boards 18 that are spaced apart from each other along the long side direction (the X-axis direction). Two through holes 18a are formed in each of the LED boards 18 at positions where the holding members 23 are attached, i.e., at respective positions overlapping with the each fixing portion 25 of the holding members 23. The through holes 18a and the holding members 23 are disposed between the adjacent LEDs 17 on the LED boards 18; specifically, between the second and the third LEDs 17 from the respective ends of the LED boards 18 in the long side direction. Two attaching holes 14c are formed in each of the long-side side plates 14b at positions aligned with the two through holes 18a in the LED boards 18.
As shown in
Specifically, the restricting portion 26 is integrally formed with the long-side side plates 14b by raising the edge of the attaching hole 14c of the respective long-side side plates 14b into a bossed shape by burring, for example. In other words, the restricting portion 26 is formed by a part of the long-side side plates 14b protruding inward, with the proximal end side of the protrusion continuous with the edges of the attaching holes 14c of the long-side side plates 14b. Thus, the restricting portion 26 is disposed at a position overlapping with the edge of the attaching hole 14c in plan view and adjacent to the fixing portion 25 inserted into the attaching hole 14c in plan view. The restricting portion 26 surrounds the entire circumference of the attaching hole 14c (the fixing portion 25), forming an endless ring along the edge of the attaching hole 14c in plan view. The restricting portion 26 has a substantially short-cylindrical shape rising from the edge of the attaching hole 14c toward the inside, and substantially the same internal diameter as the internal diameter of the attaching hole 14c. Thus, the inner circumferential surface of the restricting portion 26 and the inner circumferential surface of the attaching hole 14c form a single flush surface with no steps. Into the restricting portion 26, the fixing portion 25 can be inserted. The opening of the restricting portion 26 at the protruding end thereof constitutes an entry of the attaching hole 14c for the fixing portion 25. Thus, the restricting portion 26 also functions as a guiding structure for the fixing portion 25 to be inserted into the attaching hole 14c.
The restricting portion 26 has substantially the same internal diameter as the diameter of the attaching hole 14c. On the other hand, the through hole 18a formed in the LED board 18 has a greater diameter than the outer diameter of the restricting portion 26, thus allowing insertion of the restricting portion 26. Specifically, the through hole 18a has a substantially circular shape that extends along the outer shape of the restricting portion 26 in plan view, with a diameter larger than the outer diameter of the restricting portion 26, such that a predetermined clearance C is provided between the inner circumferential surface of the through hole 18a and the outer circumferential surface of the restricting portion 26. Thus, the LED board 18 is allowed to be displaced relative to the restricting portion 26 and the respective long-side side plates 14b with respect to the direction along the main plate surfaces (the X-axis direction and the Z-axis direction) within the range of the clearance C. Accordingly, the fixing portion 25 as well as the restricting portion 26 can be inserted into the through hole 18a. When the restricting portion 26 is inserted into the through hole 18a, the outer circumferential surface of the restricting portion 26 can be abutted against the inner circumferential surface (edge) of the through hole 18a. Therefore, the LED board 18 can be positioned two-dimensionally relative to the chassis 14 with respect to the X-axis direction and the Y-axis direction.
As described above, the chassis 14 integral with the restricting portions 26 is made of a metal plate, such as an aluminum plate or an electrogalvanized steel plate (SECC). Thus, compared to if the chassis 14 is made of a synthetic resin, a smaller linear coefficient of expansion (rate of thermal expansion) and higher heat conductivity can be obtained. Accordingly, the amount of thermal expansion or contraction of the restricting portions 26 due to changes in thermal environment is decreased. In addition, the heat generated by the lighting of the LEDs 17 can be efficiently transmitted from the LED boards 18 to the chassis 14. Thus, the restricting portions 26 can be maintained in a stably abutted state with respect to the holding members 23, and excellent heat dissipating performance of the LEDs 17 can be obtained.
An operation of the present embodiment with the above structure will be described below. When the liquid crystal display device 10 is manufactured, the liquid crystal panel 11, the backlight unit 12, the bezel 13, and the like are separately manufactured, and then assembled. In the following, a procedure for assembling the liquid crystal display device 10 will be described.
Prior to assembly of the liquid crystal display device 10, when forming the chassis 14 from sheet metal, the edges of the attaching holes 14c in the long-side side plates 14b are formed into restricting portions 26 of a bossed shape to be inwardly risen by burring. When assembling the liquid crystal display device 10, first, the LED boards 18 with the LEDs 17 surface-mounted are attached to the chassis 14 with the restricting portions 26 previously formed. Specifically, the LED boards 18 are housed in the chassis 14 with the mount surfaces for the LEDs 17 facing inward, to fit on the inner surfaces of the long-side side plates 14b. At this time, the through holes 18a of the LED boards 18 are aligned with the restricting portions 26 rising from the edges of the attaching holes 14c of the long-side side plates 14b, such that the restricting portions 26 are inserted into the through holes 18a. In this way, the LED boards 18 are two-dimensionally positioned relative to the chassis 14 with respect to the X-axis direction and the Z-axis direction. Because the LED boards 18 are positioned relative to the chassis 14 prior to assembling the holding members 23, the holding members 23 can be smoothly assembled.
Next, the holding members 23 are fixed in the attaching holes 14c of the chassis 14. Specifically, the fixing portion 25 of the holding members 23 is inserted into the attaching holes 14c of the long-side side plates 14b while the fixing portion 25 is positioned with respect to the attaching holes 14c. At this time, because the restricting portions 26 are formed to be risen from the edges of the attaching holes 14c and to have the protruding end further inside than the LED boards 18, the worker can perform the operation smoothly using the restricting portions 26 as a guiding mark. When the fixing portion 25 is inserted into the opening at the protruding end of the restricting portion 26, the fixing portion 25 reaches the attaching hole 14c through the restricting portion 26. Thus, the insertion of the fixing portion 25 into the attaching hole 14c can be guided by the restricting portion 26. When the fixing portion 25 has reached the attaching hole 14c, the holding member 25 is rotated in a fastening direction by using a fastening tool, such as a driver, whereby the threads of the fixing portion 25 can be screwed into the edge of the attaching hole 14c. Thus, the holding members 23 are prevented from falling off the chassis 14 and are securely fixed in the attached state.
As shown in
After all of the holding members 25 are attached, the second reflection sheets 21, and the light guide member 19 with the light guide reflection sheet 22 integrally attached in advance are assembled within the chassis 14. Thereafter, the optical members 15 are layered on the light output surface 19a of the light guide member 19. The optical members 15 are layered on the light output surface 19a of the light guide member 19 in the order of the diffuser plate 15a and the optical sheet 15b (a diffuser sheet, a lens sheet, and a reflection type polarizing sheet). This is followed by attaching the frame 16 to the chassis 14, and then assembling the liquid crystal panel 11 and the bezel 13 in order, thereby obtaining the liquid crystal display device 10 shown in
When a power source to the liquid crystal display device 10 manufactured as described above is turned on, the driving of the liquid crystal panel 11 is controlled by a control circuit which is not shown, while the driving of the LEDs 17 on the LED boards 18 is controlled by drive power supplied from a power supply substrate, not shown. The light from the LEDs 17 is guided by the light guide member 19 and irradiated onto the liquid crystal panel 11 via the optical members 15 to display a predetermined image on the liquid crystal panel 11. In the following, an operation of the backlight unit 12 will be described in detail. As the LEDs 17 are turned on, the light emitted from the LEDs 17 becomes incident on the light incident surfaces 19b of the light guide member 19, as shown in
During the use of the liquid crystal display device 10, the internal temperature environment of the backlight unit 12 may be varied by the turning on and off of the LEDs 17, possibly resulting in thermal expansion or thermal contraction of the constituent components of the liquid crystal display device 10. When the LED boards 18, among the constituent components, are expanded or contracted by thermal expansion or thermal contraction, the LEDs 17 mounted on the LED boards 18 are displaced in the Y-axis direction due to warping or deflection in the LED boards 18, possibly providing change in the interval between the LEDs 17 and the light incident surfaces 19b of the light guide member 19. As a result, the light incident efficiency from the LEDs 17 on the light incident surfaces 19b may be varied, thereby producing uneven brightness. The amount of expansion or contraction of the LED boards 18 due to thermal expansion or thermal contraction is particularly large with respect to the X-axis direction, i.e., the long side direction.
In this respect, according to the present embodiment, as shown in
As described above, the backlight unit 12 according to the present embodiment includes the LED boards 18 having the LEDs 17, the light guide member 19 having the end portions racing the LEDs 17, the chassis 14 housing the LED boards 18 and the light guide member 19, the holding members 23 fixed to the chassis 14 having the LED boards 18 therebetween, and the restricting portions 26 restricting the positional relationship of the holding members 23 with respect to the LED boards 18 to provide the gap G therebetween.
In this way, the LED boards 18 can be held in the sandwiched state between the holding members 23 and the chassis 14 when the holding members 23 are fixed to the chassis 14. Therefore, the LEDs 17 can be maintained in the state of being opposed to the ends of the light guide member 19. The positional relationship of the holding members 23 with respect to the LED boards 18 is restricted by the restricting portions 26 to provide the gap G therebetween. Therefore, the LED boards 18 can be easily expanded or contracted by thermal expansion or thermal contraction due to changes in the thermal environment. Thus, deformation of the LED boards 18, such as warping or deflection, is unlikely to occur. As a result, change in the positional relationship between the LEDs 17 on the LED boards 18 and the light guide member 19 is less likely to occur. Accordingly, the light incident efficiency from the LEDs 17 on the light guide member 19 can be stabilized, and thereby the development of uneven brightness in output light does not easily occur.
The restricting portions 26 are disposed at positions overlapping with the LED boards 18 in plan view, and the LED boards 18 have the through holes 18a allowing insertion of the restricting portions 26. In this way, the LED boards 18 can be positioned relative to the restricting portions 26 by inserting the restricting portions 26 into the through holes 18a.
The holding member 23 is provided with the main body portion 24 sandwiching the LED board 18 with the chassis 14, and the fixing portion 25 protruding from the main body portion 24 toward the chassis 14 to be fixed to the chassis 14. The through holes 18a have a size allowing insertion of both the fixing portion 25 and the restricting portion 26 together. In this way, because both the restricting portion 26 and the fixing portion 25 can be inserted into the through holes 18a, the structure of the LED boards 18 can be simplified and the manufacturing cost for the LED boards 18 can be reduced compared to if separate through holes are formed in the LED boards for the fixing portion 25 and the restricting portion 26 individually.
The restricting portions 26 are disposed adjacent to the fixing portion 25 in plan view. In this way, the size of the through holes 18a can be decreased compared to if the restricting portions and the fixing portion are disposed apart from each other on the main body portion 24.
The through holes 18a have the clearance C from the circumferential surface of the restricting portions 26. In this way, the displacement of the LED boards 18 relative to the restricting portions 26 is allowed within the range of the clearance C provided between the through holes 18a and the circumferential surface of the restricting portions 26. Thus, deformation of the LED boards 18, such as warping or deflection, upon expansion or contraction due to thermal expansion or thermal contraction does not easily occur. Accordingly, the development of uneven brightness can be prevented in a more preferred manner.
The restricting portions 26 are integrally provided on the side of the chassis 14, the restricting portions 26 protruding toward and abutted against the holding members 23. In this way, because the restricting portions 26 integrally provided on the side of the chassis 14 are abutted against the holding members 23, the positional relationship of the holding members 23 with respect to the LED boards 18 can be restricted in a good manner.
The restricting portions 26 are integrally provided to the chassis 14. In this way, because the restricting portions 26 are integrally provided to the chassis 14, the number of components and assembly steps can be decreased, which is preferable for cost reduction purpose, compared to if the restricting portions are provided as separate components from the chassis 14.
The restricting portions 26 are disposed at positions overlapping with the LED boards 18 in plan view, and the LED boards 18 have the through holes 18a allowing insertion of the restricting portions 26. In this way, when the LED boards 18 are housed in the chassis 14, the restricting portions 26 are inserted into the through holes 18a, to be positioned relative to the chassis 14. Thus, the LED boards 18 can be positioned relative to the chassis 14 prior to attaching the holding members 23.
The holding members 23 are provided with the main body portion 24 sandwiching the LED boards 18 with the chassis 14, and the fixing portion 25 protruding from the main body portion 24 toward the chassis 14 to be fixed to the chassis 14. The chassis 14 have the attaching holes 14c allowing insertion of the fixing portion 25. The attaching holes 14c have the restricting portions 26 at the edges thereof. In this way, when the fixing portion 25 is inserted into the attaching hole 14c in the chassis 14, the fixing portion 25 can be guided by the restricting portion 26 at the edge of the attaching hole 14c. Thus, improved workability can be attained when attaching the holding members 23.
The restricting portion 26 is formed in a ring shape along the edge of the attaching hole 14c. In this way, the strength of the restricting portions 26 can be maintained high to reliably restrict the positional relationship of the holding members 23 with respect to the LED boards 18.
The restricting portions 26 are made of a metal material. In this way, compared to if the restricting portions are made of a synthetic resin, generally a smaller linear coefficient of expansion and higher heat conductivity can be obtained. Thus, the restricting portions 26 are not easily expanded or contracted by thermal expansion or thermal contraction, to reliably restrict the positional relationship between the holding members 23 and the LED boards 18. In addition, the heat generated by the LEDs 17 on the LED boards 18 can be efficiently transmitted via the restricting portions 26 to the chassis 14. Therefore, excellent heat dissipation property can be obtained with regard to the LEDs 17.
The LED boards 18 have an elongated shape with the long side direction extending along the ends of the light guide member 19. The elongated LED boards 18 are more readily expanded or contracted by thermal expansion or thermal contraction in the long side direction, i.e., along the ends of the light guide member 19, than in the short side direction. Because the expansion or contraction of the LED boards 18 is allowed due to the gap generated by the restricting portions 26, deformation of the LED boards 18 is suppressed in a preferred manner, and changes in the positional relationship between the LEDs 17 and the light guide member 19 is unlikely to occur.
On the LED boards 18, a plurality of the LEDs 17 is disposed side by side in a line along the long side direction. In this way, the plurality of the LEDs 17 can be efficiently disposed on the LED boards 18, which is preferable for achieving high brightness.
The holding members 23 are disposed between the adjacent LEDs 17. In this way, the space between the adjacent LEDs 17 can be effectively utilized. Further, the holding members 23 can avoid obstructing the light emitted by the LEDs 17.
The holding members 23 are provided with the main body portion 24 sandwiching the LED boards 18 with the chassis 14, and the fixing portion 25 protruding from the main body portion 24 toward the chassis 14 to be fixed to the chassis 14. In this way, by fixing the fixing portion 25 to the chassis 14, the LED boards 18 sandwiched between the main body portion 24 and the chassis 14 can be appropriately held.
The LEDs 17 and the ends of the light guide member 19 opposed thereto are spaced apart from each other with a space therebetween. The space is enclosed between the pair of reflection sheets 20 and 21. In this way, the light emitted by the LEDs 17 is repeatedly reflected by the pair of reflection sheets 20 and 21 in the space provided between the LEDs 17 and the opposed ends of the light guide member 19. Therefore, the light can become incident on the ends of the light guide member 19 efficiently. Thus, the light utilization efficiency can be improved.
The light sources are the LEDs 17. In this way, high brightness and low power consumption can be achieved.
While the first embodiment of the present invention has been described above, the present invention is not limited to the embodiment and may include the following modifications. In the following modifications, components similar to those of the embodiment will be designated by the same reference signs and their description and illustration may be omitted.
A first modification of the first embodiment will be described with reference to
As shown in
A second modification of the first embodiment will be described with reference to
As shown in
As described above, according to the present modification, the one end of the LED boards 18 in the long side direction is sandwiched between the sandwiching portions 27 and the chassis 14. By thus holding the LED boards 18 with the gap G from the holding members 23 between the sandwiching portions 27 and the chassis 14, clattering of the LED boards 18 is less likely to occur. On the other hand, the other end of the LED boards 18 in the long side direction is not sandwiched by the sandwiching portions 27, and therefore, the expansion or contraction of the LED boards 18 due to thermal expansion or thermal contraction can be appropriately allowed. As a result, deformation of the LED boards 18, such as warping or deflection is unlikely to occur.
A third modification of the first embodiment will be described with reference to
As shown in
As described above, according to the present modification, the sandwiching portion 27-3 is disposed between the light guide member 19 and the LED board 18. In this way, when thermal expansion is caused in the light guide member 19, the positional relationship of the light guide member 19 with respect to the LED boards 18 and the LEDs 17 can be restricted by the sandwiching portions 27-3 disposed between the light guide member 19 and the LED boards 18. Thus, the light incident efficiency from the LEDs 17 on the light guide member 19 can be stabilized, and therefore, uneven brightness in output light is less likely to occur.
A second embodiment of the present invention will be described with reference to
As shown in
As described above, according to the present embodiment, the restricting portion 126 is integrally provided on the side of the holding member 123, to protrude toward and abutted against the chassis 14. By thus abutting the restricting portion 126 integrally provided on the side of the holding members 123 against the chassis 14, the positional relationship of the holding members 123 with respect to the LED boards 18 can be restricted in a good manner.
Further, the restricting portion 126 is integrally provided to the holding member 123. In this way, compared to if the restricting portion is provided as a separate component from the holding member 123, the number of components and assembly steps can be decreased, which is preferable for cost reduction.
The holding member 123 is provided with the main body portion 124 sandwiching the LED boards 18 with the chassis 14, and the fixing portion 125 protruding from the main body portion 124 toward the chassis 14 to be fixed to the chassis 14. The restricting portion 126 is provided to the main body portion 124. In this way, when the fixing portion 125 is fixed to the chassis 14, the LED boards 18 sandwiched between the main body portion 124 and the chassis 14 are retained in a preferred manner. At this time, the positional relationship of the holding members 123 with respect to the LED boards 18 can be appropriately restricted by the restricting portion 126 provided to the main body portion 124.
The restricting portion 126 is continuous with the fixing portion 125. In this way, compared to the case if the restricting portion is independent from the fixing portion 125, the strength of the restricting portion 126 and the fixing portion 125 can be increased.
The restricting portion 126 surrounds the fixing portion 125. In this way, the strength of the restricting portion 126 and the fixing portion 125 can be further increased.
While the second embodiment of the present invention has been described, the present invention is not limited to the embodiment and may also include the following exemplary modifications. In the following modifications, members similar to those of the embodiment will be designated with similar reference signs and their description and illustration may be omitted.
A first modification of the second embodiment will be described with reference to
As shown in
As described above, according to the present modification, a plurality of the restricting portions 126-1 is disposed on the circumferential surface of the fixing portion 125 intermittently along the circumference thereof. In this way, compared to if the fixing portion 125 is surrounded by the restricting portion, the material cost for the holding members 123-1 can be decreased.
Further, the plurality of the restricting portions 126-1 is disposed at substantially equal angular intervals on the circumferential surface of the fixing portion 125. In this way, the plurality of the restricting portions 126-1 can be stably abutted against the chassis 14, and therefore, the positional relationship of the holding members 123-1 with respect to the LED boards 18 can be more appropriately restricted.
A second modification of the second embodiment will be described with reference to
As shown in
As described above, according to the present modification, the holding members 123 2 are made of a synthetic resin material. In this way, structural design and formation can be simplified when manufacturing the holding member 123-2 integral with the restricting portion 126-2.
The fixing portion 125-2 penetrates the chassis 14 and is locked on the chassis 14 from an opposite side to the LED boards 18. In this way, by locking the fixing portion 125-2 through and on the chassis 14, the holding members 123-2 and the LED boards 18 can be fixed at low cost and simply without using other fixing means, such as an adhesive.
A third modification of the second embodiment will be described with reference to
As shown in
The second component 29 has a substantially T-shaped cross section and includes a base portion 29a parallel with the main body portion 124-3 of the first component 28 in an assembled state, and a shaft portion 29b protruding from the base portion 29a toward the rear side. The base portion 29a has a substantially circular shape in plan view and is of substantially the same size as the main body portion 124-3 of the first component 28. On the other hand, the shaft portion 29b has a substantially cylindrical shape with a substantially constant diameter along its entire length. The length of protrusion of the shaft portion 29b from the base portion 29a is substantially same as the size of the first component 28 in the Z-axis direction. The shaft portion 29b has a diameter slightly smaller than the mount opening 28a of the first component 28, allowing the shaft portion 29b to be inserted into or pulled out of the mount opening 28a.
Next, an attachment of the holding members 123-3 with the above configuration to the chassis 14 will be described. First, as shown in
As described above, according to the present modification, the fixing portion 125-3 includes the elastic locking parts that can be elastically deformed and locked on the opposite side to the LED boards 18 while penetrating the chassis 14. The holding members 123-3 include the first component 28 with the main body portion 124-3 and the fixing portion 125-3, and the second component 29 mounted on the first component 28 and restricting the elastic deformation of the elastic locking parts 125b-3. When attaching the holding members 123-3 to the chassis 14, the second component 29 is mounted on the first component 28 which is previously attached to the chassis 14. In this way, the holding members 123-3 can be retained in an anti-falling state as the elastic deformation of the elastic locking parts 125b-3 penetrating the chassis 14 and locked on the opposite side to the LED boards 18 is restricted. When detaching the holding members 123-3 from the chassis 14, the second component 29 is removed from the first component 28 to allow the elastic deformation of the elastic locking parts 125b-3 into their original shapes, and thereafter the first component 28 is detached. Thus, the holding members 123-3 can be easily attached to or detached from the chassis 14 by attaching or detaching the second component 29 to or from the first component 28 without using a special tool, thereby providing excellent workability. Particularly, excellent working efficiency can be obtained during a disassembling operation for maintenance or discard of the backlight unit 12, for example.
A third embodiment of the present invention will be described with reference to
As shown in
When the LED boards 18 are attached to the chassis 14, the restricting portions 226 are inserted into the through holes 18a to fit on the side plates 14b, with communication between the respective through holes 18a of the LED boards 18 and the respective attaching holes 14c of the side plates 14b of the chassis 14, as shown in
As described above, according to the present embodiment, the restricting portion 226 is separate from the chassis 14 and the holding members 23 and is disposed between the chassis 14 and the holding member 23. In this way, because the restricting portion 226 is separate from the chassis 14 and the holding members 23, the degree of freedom in the material or shape, for example, of the restricting portion 226 can be increased. Specifically, when iron is selected as the material of the chassis 14 for manufacturing cost reason, for the restricting portions 226, it is preferable to use a metal material with a smaller linear coefficient of expansion and larger heat conductivity than iron, such as aluminum. In this way, the positional relationship of the holding members 23 with respect to the LED boards 18 can be reliably restricted and excellent heat dissipating performance can be obtained.
The present invention is not limited to the embodiments above described and illustrated with reference to the drawings, and the following embodiments may be included in the technical scope of the present invention.
(1) While in the foregoing embodiments other than the first modification of the second embodiment, the restricting portions have a circular endless ring-shape in plan view, the restricting portions may have a quadrangular or elliptical endless ring-shape in plan view, or a ring-shape with terminal ends (such as C-shape) in plan view, and such configurations are also included in the present invention. The present invention further includes configurations in which the restricting portions are in the form of dots or lines (such as straight lines or curved lines) in plan view. The present invention also includes configurations in which the restricting portions are cylindrical, rectangular-columnar, conical, or pyramidal, and configurations in which the restricting portions have a mountain-like (triangular), semicircular, or elliptical cross sectional shape.
(2) While in the first modification of the second embodiment, the four block-shaped restricting portions are disposed on the circumferential surface of the fixing portion at equal angular intervals, the number of the restricting portions may be three or less or five or more, or the restricting portions may be disposed on the circumferential surface of the fixing portion at non-equal angular intervals, and such configurations are also included in the present invention.
(3) While in the foregoing embodiments the restricting portions are disposed adjacent to the fixing portion in plan view, the restricting portions may be disposed at a position spaced apart from the fixing portion in plan view, and such a configuration is also included in the present invention. In this case, when the restricting portions are integrally formed with the holding member, as in the second embodiment, the restricting portions and the fixing portion are disposed separately and independently from each other. Further, as the restricting portions and the fixing portion are spaced apart from each other, the LED boards need to have separate through holes for the restricting portions and the fixing portion respectively.
(4) In the foregoing embodiments the fixing portion and the restricting portions are disposed at positions overlapping with the LED boards in plan view, with the corresponding through holes provided in the LED boards. Preferably, the fixing portion and the restricting portions may be disposed at positions that do not overlap with the LED boards in plan view. In this case, the LED boards may not have the through holes.
(5) Other than (4), one of the fixing portion and the restricting portions may be disposed at a position overlapping with the LED boards in plan view while the other may be disposed at a position not overlapping with the LED boards in plan view.
(6) While in the first and the second embodiments, the restricting portions are provided to either the chassis or the holding members, the restricting portions may be provided to both the chassis and the holding members. In this case, the respective restricting portions on both sides may be disposed in such a manner as to overlap with each other in plan view and configured to be abutted against each other such that the positional relationship between the holding members and the extending members can be restricted.
(7) While in the foregoing embodiments only the LED boards are disposed between the main body portion of the holding members and the side plates of the chassis, another member may be disposed therebetween together with the LED boards. For example, when a reflection sheet with excellent light reflectivity is placed on the side of the LED boards on which the LEDs are mounted, the LED boards and the reflection sheet are disposed between the main body portion and the side plates. Further, when a sheet-like heat dissipating member for facilitating heat dissipation is disposed between the LED boards and the side plates of the chassis, the LED boards and the heat dissipating member are disposed between the main body portion and the side plates.
(8) While in the foregoing embodiments the LED boards are disposed on the long sides of the chassis and attached to the long-side side plates with the holding members, the LED boards may be disposed on the short sides of the chassis and attached to the short-side side plates with the holding members. In this case, the short-side side plates may have the attaching holes.
(9) While in the foregoing embodiments a pair of LED boards is disposed on the long sides of the chassis, the LED boards may be disposed on only one of the long sides. Similarly, the LED boards may be disposed on only one of the short sides of the chassis.
(10) While in the foregoing embodiments the LED boards of the one-side mounted type are used, the LED boards of a double-side mounted type may be used.
(11) While in the foregoing embodiments one LED board is attached to each side plate of the chassis, a plurality of LED boards may be attached to each side plate, and such a configuration is also included in the present invention. In this case, preferably at least one holding member is attached to each LED board.
(12) While in the foregoing embodiments two holding members are attached to one LED board, one holding member may be attached to one LED board, or three or more holding members may be attached to one LED board, which are also included in the present invention.
(13) While in the foregoing embodiments other than the second and the third modifications of the second embodiment, the holding members made of a metal are used, the holding members made of a synthetic resin may be used in the embodiments other than the second and the third modifications of the second embodiment. Similarly, the holding members made of a metal may be used in the second and the third modifications of the second embodiment.
(14) The shape of the main body portion of the holding member may be appropriately modified from the foregoing embodiments. Specifically, the main body portion may have an elliptical shape or a quadrangular shape (a rectangular shape or a square shape) in plan view, which is also included in the present invention.
(15) While in the foregoing embodiments the holding members are disposed between the adjacent LEDs on the LED boards, the holding members may be disposed closer to the end of the LED boards than the endmost LED, which is also included in the present invention.
(16) The attaching position of the holding members with respect to the LED boards may be appropriately modified from the foregoing embodiments.
(17) In the second modification of the second embodiment, as the attaching structure of the holding members made of a synthetic resin to the chassis, the fixing portion of insertion type is adopted. A sliding type of attaching structure may be adopted. The sliding type of attaching structure refers to the structure including a hook-shaped fixing portion, of which a main body portion is pushed toward the bottom plate of the chassis and then slide along the bottom plate, thereby causing the hook-shaped portion of the fixing portion to be locked on the edges of the attaching hole.
(18) In the second modification of the second embodiment, the fixing portion of the holding members made of a synthetic resin is locked on the chassis through the attaching hole. The specific method of fixing the fixing portion on the chassis may be appropriately modified. For example, the attaching hole and the elastic locking part may be omitted, and the base portion inserted into the through hole of the LED boards may be fixedly attached to the inner wall surface of the chassis by using an adhesive, which is also included in the present invention. In this case, means other than an adhesive, such as deposition or welding, may be adopted.
(19) In the foregoing embodiments, the LEDs are of the type including the LED chips that emits light of the single color of blue and configured to emit white light by using a phosphor. The present invention also includes a configuration in which the LEDs are of the type including LED chips that emits light of the single color of ultraviolet and configured to emit white light by using a phosphor.
(20) In the foregoing embodiments, the LEDs are of the type including an LED chips that emits light of the single blue color and configured to emit white light by using a phosphor. However, the present invention also includes a configuration in which the LEDs are of the type including three types of LED chips that emit light of the single color of R (red), G (green), or B (blue), respectively. In addition, the present invention also includes a configuration in which the LEDs are of the type including three types of LED chips that emit the single colors of C (cyan), M (magenta), or Y (yellow), respectively.
(21) While in the foregoing embodiments the LEDs that emit white light are used, a LED that emits red light, a LED that emits blue light, and a LED that emits green light may be used in an appropriate combination.
(22) While in the foregoing embodiments the LEDs are used as light sources by way of example, a configuration in which a point light source other than a LED is used is also included in the present invention.
(23) In the foregoing embodiments, the liquid crystal panel and the chassis are vertically disposed with their short side directions aligned with the vertical direction, by way of example. The present invention also includes a configuration in which the liquid crystal panel and the chassis are vertically disposed with their long side directions aligned with the vertical direction.
(24) In the foregoing embodiments, as the switching elements of the liquid crystal display device, TFTs are used. The present invention, however, may be applied to liquid crystal display devices using switching elements other than TFTs (such as thin-film diodes (TFD)). Further, the present invention may be applied not only to a liquid crystal display device for color display but also to a liquid crystal display device for monochrome display.
(25) While in the foregoing embodiments liquid crystal display devices using a liquid crystal panel as a display panel has been described by way of example, the present invention may be applied to display devices using other types of display panels.
(26) While in the foregoing embodiments a television receiver with a tuner has been described by way of example, the present invention may be applied to a display device without a tuner.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-097982 | Apr 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/054705 | 3/2/2011 | WO | 00 | 10/15/2012 |
