JP2011216270A - Backlight unit and liquid crystal display - Google Patents

Abstract

The present invention provides a backlight unit and a liquid crystal display device that can solve the problems caused by the expansion of the light guide plate during lighting without reducing the size and the light extraction efficiency from the LED light source.
A liquid crystal display device includes a liquid crystal panel, a backlight unit, and the like. The backlight unit is an edge type in which an LED light source 19 having a light emitter 42 is disposed in close proximity to the lower surface 13 b of the light guide plate 13. In this backlight unit, a counter member 43 is present at a position facing the lower side surface 13 b of the light guide plate 13 and where the light emitter 42 is not present, and the relative height of the counter member 43 is that of the light emitter 42. Higher than height.
[Selection] Figure 2

Description

  The present invention relates to an edge-type backlight unit in which a light source having a light emitter is disposed in close proximity to a side surface of a light guide plate, and a liquid crystal display device including the backlight unit.

  In recent years, an edge type backlight unit using a light source using a semiconductor light emitting element such as an LED element as a light emitter (hereinafter, a light source using the LED element is referred to as an “LED light source”) has been developed. In addition, by using an LED element etc., compared with the case where the conventional cold cathode lamp is utilized, power saving and size reduction (thinning) can be achieved.

  The backlight unit includes a rectangular light guide plate, a heat sink disposed along a predetermined side surface of the light guide plate (for example, a lower side surface and an upper side surface), and a predetermined side surface of the light guide plate. An LED light source mounted on a heat sink and an optical sheet disposed on the front surface of the light guide plate are provided in a housing whose front surface is open (see, for example, Patent Document 1).

  The LED light source includes, for example, a substrate, a plurality of LED elements mounted on the substrate, and a sealing body that covers and seals each of the plurality of LED elements, and the LED element sealed by the sealing body Is a light emitter.

  Here, the light guide plate and the LED light source are effectively used by downsizing the backlight unit and making most of the light from the LED light source incident on the light guide plate (hereinafter simply referred to as “effective use of light”). )) From the viewpoint.

JP 2008-227423 A

  However, as described above, when the light guide plate and the LED light source are brought close to each other, the light guide plate expands toward the LED light source due to the heat generated when the LED light source is turned on and contacts the light emitter, thereby forming the light emitter. This causes problems such as damage to the LED element to be damaged, or discoloration by further heating the light guide plate.

  In view of the above-described problems, the present invention provides a backlight unit and a liquid crystal display device capable of solving the problems caused by the expansion of the light guide plate during lighting while reducing the size (thinning) and effectively using light. With the goal.

  In order to achieve the above object, a backlight unit according to the present invention is an edge type in which a light source having a light emitter is disposed in close proximity to a side surface of a light guide plate, and a position facing the side surface of the light guide plate. The counter member is present at a position where the light emitter does not exist, and the relative height of the counter member is higher than the height of the light emitter.

  Here, the “opposing member” includes a member that faces only the side surface of the light guide plate and a member that has a portion that faces the side surface of the light guide plate. Needless to say, the opposing member only needs to be present, and the counterpart member to which the opposing member is attached does not matter.

  The “light emitter” includes, for example, a semiconductor light emitting element and a sealing body that seals the semiconductor element, a plurality of semiconductor light emitting elements and a seal that seals all of the semiconductor light emitting elements. The thing comprised from the stationary body, the thing of a SMD type, etc. are included. Semiconductor light emitting elements include LED elements and LD elements.

  Furthermore, “the relative height of the facing member is higher than the height of the light emitter” means that the height (actual size) of the facing member is higher (larger) than the height (actual size) of the light emitter. In the case where the mounting portion of the facing member in the member to which the facing member is mounted is higher than the portion where the facing member is not mounted, the height of the mounting portion of the facing portion is also included (that is, the light emitter) It is assumed that this step is also taken into account when there is a step between the portion where the component is mounted and the portion where the opposing member is mounted.

  Since the backlight unit according to the present invention has a facing member that is higher than the height of the light emitter facing the side surface of the light guide plate, the light guide plate is thermally expanded toward the light source by the heat of the light emitter when the light source is turned on. Moreover, it can suppress that a light-guide plate and a light-emitting body contact.

  The light source includes the light emitter on a substrate, and the facing member is provided in a portion of the substrate where the light emitter does not exist. Alternatively, the light source extends along a side surface of the light guide plate. The fixing member is attached to a heat sink that is disposed in a row and emits heat when the light emitter emits light, and the opposing member is the fixing member. Here, the “fixing member” is a concept including a screw member, a rivet member, a pin member, and the like.

  In addition, the light guide plate side end of the counter member has a hemispherical shape, or the light guide plate side end of the counter member has a flat shape. .

  On the other hand, a liquid crystal display device according to the present invention includes a backlight unit and a liquid crystal panel, and the backlight unit is a backlight unit having the above-described configuration.

It is sectional drawing which shows schematic structure of the liquid crystal display device which concerns on embodiment. It is the enlarged view which looked at the state which removed the front frame of the backlight unit from the front. It is a disassembled perspective view of a backlight unit. It is a figure which shows the state with which the LED light source was mounted | worn with the heat sink. It is the figure which looked at the X1-X1 cross section in FIG. 2 from the arrow direction. It is the figure which looked at the X2-X2 cross section in FIG. 2 from the arrow direction. It is a perspective view which shows the modification 1 of the LED light source which concerns on embodiment. It is a perspective view which shows the modification 2 of the mounting method of the LED light source which concerns on embodiment. It is sectional drawing which shows the modification 3 of the opposing member which concerns on embodiment. It is sectional drawing which shows the modification 4 of the opposing member which concerns on embodiment.

Hereinafter, a backlight unit and a liquid crystal display device according to the present embodiment will be described with reference to the drawings.
<Embodiment>
1. Configuration FIG. 1 is a cross-sectional view showing a schematic configuration of a liquid crystal display device according to an embodiment.

As shown in the figure, the liquid crystal display device 1 according to the present embodiment includes a liquid crystal panel 3, an edge type backlight unit 5, a housing 7 for housing them, and the like.
A known liquid crystal panel 3 is used. Here, it is a so-called active matrix type, and includes, for example, a screen side (also a front side), a front side polarizing plate, a glass substrate, a color filter, a liquid crystal layer, a glass substrate, a back side polarizing plate, a drive module, and the like (see FIG. Not shown).

As shown in FIG. 1, the backlight unit 5 includes a housing 9, an optical sheet 11, a light guide plate 13, a reflective sheet 15, a heat sink 17, an LED light source 19, a lighting circuit 20, and the like.
FIG. 2 is an enlarged view of the backlight unit with the front frame removed, as viewed from the front, and FIG. 3 is an exploded perspective view of the backlight unit.

  The housing 9 is made of a metal made of, for example, a galvanized steel plate, and as shown in FIG. 1, a box-shaped housing body 21 having an opening at a position corresponding to the front surface, and the front surface side of the housing body 21 A substantially square front frame 23 attached to the front frame 23, and an opening 23a of the front frame 23 serves as a light outlet.

  As shown in FIGS. 1 and 3, the reflection sheet 15, the light guide plate 13, and the optical sheet 11 are arranged (stacked) in that order from the bottom surface side of the casing body 21 inside the casing 9. In this state, the front frame 23 is fixed to the housing body 21 by the screw member 24.

  The optical sheet 11 here includes a diffusion sheet 25, a prism sheet 27, and a polarizing sheet 29. In addition, as an optical sheet, you may employ | adopt the optical sheet (for example, antireflection sheet etc.) currently used as a constituent material of flat panel displays, such as a liquid crystal display device and PDP.

  The central portion of the bottom wall of the housing body 21 is a recessed portion 21 a that is recessed into the inside (on the liquid crystal panel 3 side). Between the recessed portion 21 a and the bottom wall 7 a of the housing 7. The lighting circuit 20 is arranged in the front.

  As shown in FIGS. 1 and 3, predetermined side surfaces of the light guide plate 13 inside the housing 9, here the upper and lower side surfaces 13 a and 13 b, are operated along the side surfaces 13 a and 13 b (when lighting). A heat sink 17 for releasing heat from the LED light source 19 is arranged, and the LED light source 19 is mounted on the heat sink 17.

  In this embodiment, there are a plurality of LED light sources 19 and heat sinks 17 (specifically, four), but reference numerals “19” and “17” are used when it is not necessary to distinguish them in the description.

  The LED light source 19 is attached to the heat sink 17 so as to face the upper and lower side surfaces 13 a and 13 b of the light guide plate 13. Light emitted from the LED light source 19 enters the light guide plate 13 from the upper and lower side surfaces 13a and 13b of the light guide plate 13, that is, the light incident surface, and the light extraction main surface 13c that is the front surface of the light guide plate 13, that is, light. The light exits from the exit surface.

  The emitted light then passes through the diffusion sheet 25, the prism sheet 27 and the polarizing sheet 29, exits from the opening 23 a of the front frame 23 to the outside of the backlight unit 5, and further enters the liquid crystal panel 3.

  The reflection sheet 15 is a substantially square sheet made of, for example, PET (polyethylene terephthalate), and is disposed on the back side of the light guide plate 13. The light reaching the back surface of the light guide plate 13 is directed to the light extraction main surface 13 c. Reflect. The reflective sheet 15 may be a metallic foil having metallic luster, an Ag sheet, or the like.

  The light guide plate 13 is, for example, a substantially square plate made of PC (polycarbonate) resin, and the incident light is incident on the main surface on the side of the reflection sheet 15 (that is, the back surface of the light guide plate 13) facing the light emission surface. A dot pattern (not shown) that is a daylighting element for emitting light from the emission surface is formed. The light emitted from the LED light source 19 enters from the upper and lower side surfaces 13a and 13b (light incident surfaces) of the light guide plate 13, and is mixed and averaged when passing through the light guide plate 13 while propagating through the inside. The light exits from the main surface 13c.

  As a lighting element formed on the light guide plate 13, a light scattering element and a prism shape such as a light scattering structure formed by printing, molding, etc. on the main surface facing the light emitting surface of the light guide plate, or Although the light-scattering element etc. which were formed in the inside of a light-guide plate are used, it does not specifically limit. In addition to this, an optical element that changes the light guiding direction can also be used as the daylighting element.

The diffusion sheet 25 is a substantially rectangular film made of, for example, PET or PC resin, and is laminated in a state of being in close contact with the light extraction main surface 13 c of the light guide plate 13.
The prism sheet 27 is a substantially rectangular optical sheet formed by forming a uniform prism pattern with an acrylic resin on one surface of a face material made of polyester resin, for example, and is laminated in close contact with the diffusion sheet 25. .

  The polarizing sheet 29 is a substantially rectangular film made of, for example, a PC film, a polyester film, and an acrylic resin, or made of PEN (polyethylene naphthalate), and is laminated in close contact with the prism sheet 27. .

  The optical sheet 11, the light guide plate 13, and the reflection sheet 15 are provided with known means within the housing 9, for example, a notch is provided in each member, and the notch is formed on the liquid crystal panel from the bottom (bottom wall) of the housing body 21. It is fixed by combining with a pin protruding to the 3 side. As described above, each member such as the light guide plate 13 is disposed in the vicinity of the LED light source 19, and thus is easily affected by the heat of the LED light source 19 when the LED light source 19 is turned on during operation. In particular, the light guide plate 13 disposed closest to the LED light source 19 is greatly affected by heat and tends to thermally expand toward the LED light source 19 side.

FIG. 4 is a diagram illustrating a state in which the LED light source is mounted on the heat sink.
The heat sink 17 is made of a material with good heat dissipation, such as an aluminum material, as shown in FIGS. 1 to 4, particularly as shown in FIG. 2, along the upper and lower side surfaces 13 a and 13 b of the light guide plate 13 and the back surfaces of the upper and lower ends. In addition, the cross-sectional shape is an “L” shape, and as shown in FIG. 4, the LED light source 19 is mounted on the inner surfaces 31 a of the two sides 31 constituting the L shape.

  Here, the inner surface 31a is a surface facing the light guide plate 13 in the heat sink 17, in other words, the angle formed by the two sides 31, 33 constituting the L shape is approximately 90 (degrees). This is the aspect.

  In order to improve heat dissipation, the heat sink 17 has a thick portion 35 extending from the center to the end opposite to the side where the other side 31 exists in the side 33 constituting the L-shaped cross section. .

FIG. 5 is a view of the X1-X1 cross section in FIG. 2 as viewed from the direction of the arrow.
There is a gap between the inner surface 31a of one side 31 of the heat sink 17 and the upper and lower side surfaces 13a, 13b of the light guide plate 13, and the LED light source 19 exists in this gap.

  2 and 4, the LED light source 19 includes a long substrate 37, an LED element 39 mounted on the main surface of the substrate 37, a seal that covers the LED element 39 and seals the element. This is a module type including a stop body 41. The sealing body 41 includes a translucent material and a wavelength conversion material that converts the wavelength of light from the LED element 39 to a desired wavelength when it is necessary to convert the wavelength. The LED element 39 and the sealing body 41 constitute a single light emitter 42, and a plurality of light emitters 42 are mounted on the substrate 37.

  As shown in FIGS. 2 and 4, the LED light source 19 is attached to one side 31 of the heat sink 17 by a fixing member 43 so as to face the upper and lower side surfaces 13 a and 13 b of the light guide plate 13. When the backlight unit 5 is operating (lights on), the fixing member 43 expands the light guide plate 13 due to heat from the LED light source 19 and the like, and is a light emitting body (more precisely, a sealing body 41) 42. It also has a function of restricting (preventing) contact with the surface.

  Note that a metal (flat) screw member 45 is used as the fixing member 43 here. Further, since the fixing member 43 exists at a position facing the upper and lower side surfaces 13 a and 13 b of the light guide plate 13, it corresponds to the facing member of the present invention (hereinafter, the fixing member 43 may be referred to as the facing member 43. In addition, it can be said that the light guide plate 13 expands and contacts the light emitter 42 during lighting. The fixing member 43 is not limited to being made of metal, and may be any member having a strength capable of regulating the contact of the light emitter when the light guide plate is expanded.

6 is a view of the X2-X2 cross section in FIG. 2 as viewed from the direction of the arrow.
The opposing surface 45a (the phantom line X3 shown in FIG. 2) facing the upper and lower side surfaces 13a, 13b of the light guide plate 13 in the screw member 45 is the light guide plate 13 in the light emitter 42 (sealing body 41) of the LED light source 19. The upper and lower side surfaces 13a and 13b of the light guide plate 13 are positioned between the opposing surface 42a (the virtual line X4 in FIG. 2) and the upper and lower side surfaces 13a and 13b of the light guide plate 13.

That is, when the upper and lower side surfaces 13a and 13b of the light guide plate 13 are used as a reference, the distance L1 from the facing surface 45a of the screw member 45 is shorter than the distance L2 from the facing surface 42a of the light emitter 42. When the light guide plate 13 is thermally expanded, the screw member 45 is first contacted.
2. Example An example of the above embodiment will be described.

The liquid crystal display device 1 described as an example is for 37 inches.
As described above, the light guide plate 13 is made of PC resin, and has a length × width dimension of 450 (mm) × 840 (mm) and a thickness (B1 in FIG. 6) of 4 (mm). It is. The distance (H1 in FIG. 6) between the lower surface 13b of the light guide plate 13 that is the side facing the LED light source 19 and serves as the light incident surface and the substrate 37 of the LED light source 19 is 0.65 (mm). is there.

The LED light source 19 emits white light, for example. For this reason, the LED element 39 uses, for example, a GaN system that emits blue light. The sealing body 41 uses, for example, a silicone resin as a translucent material, and as a wavelength conversion material, for example, a YAG phosphor ((Y, Gd) ₃ Al ₅ O ₁₂ : Ce ³⁺ ), a silicate phosphor (( Sr, Ba) ₂ SiO ₄ : Eu ²⁺ ), nitride phosphor ((Ca, Sr, Ba) AlSiN ₃ : Eu ²⁺ ), oxynitride phosphor (Ba ₃ Si ₆ O ₁₂ N ₂ : Eu ²⁺ ), etc. Is used.

The sealing body 41 has a square shape in plan view, one side (B2 in FIG. 5) is 0.45 (mm), and the height (H2 in FIG. 5) is 0.1. (Mm).
As described above, the screw member 45 is a flat screw member made of stainless steel. The shape of the screw member 45 in a plan view of the head is circular, the diameter of the head (B3 in FIG. 6) is 2.5 (mm), and the height of the head (H3 in FIG. 6). ) Is 0.3 (mm).
<Modification>
1. In the module embodiment, there are four heat sinks 17 and LED light sources 19, and each LED light source 19 is mounted on the heat sink 17 and has one substrate 37, and the substrate 37 is screwed to the heat sink 17. Screwed by the member 45.

  That is, each LED light source 19 is composed of one module, and one module is mounted on one heat sink. However, the LED light source mounted on each heat sink may be composed of a plurality of modules, and a plurality of modules may be mounted on one heat sink.

FIG. 7 is a perspective view showing Modification 1 of the LED light source according to the embodiment.
The LED light source 51 according to the first modification is composed of a plurality of modules.
As shown in the figure, the module 53 includes a substrate 55, an LED element (not shown), and a sealing body 41, and is fixed to the heat sink 17 via a fixing member 57. Also here, the light emitter 42 includes the LED element 39 and the sealing body 41, and a plurality of light emitters 42 are mounted on the substrate 55.

The fixing member 57 is configured by the screw member 59 as in the first embodiment, and, as described above, the light guide plate 13 and the light emitter (sealing body) due to thermal expansion of the light guide plate 13 when the LED light source 51 is turned on. 41) The contact with 42 is prevented.
2. Configuration of Opposing Member (1) In the embodiment, the LED light source 19 is mounted on the heat sink 17 by a screw member 45, and the screw member 45 has a function of restricting contact due to thermal expansion of the light guide plate when it is turned on as the opposing member. is doing. That is, the screw member 45 is both the fixing member 43 and the opposing member, and has both functions.

However, the LED light source 19 may be attached to the heat sink 17 by other known means.
FIG. 8 is a perspective view showing a second modification of the LED light source mounting method according to the embodiment.

  The LED light source 19 according to the modified example 2 is fixed to one side 31 (the inner surface 31a thereof) of the heat sink 17 via an adhesive 71 as shown in FIG. In the embodiment, the screw member 45 is used as the counter member 43, but the counter member 73 in the second modification is a member whose height is higher than that of the sealing body 41. As this member, for example, a rod member 75 having a square cross-sectional shape is used.

  Thus, the opposing member 73 only needs to prevent the light guide plate 13 and the light emitter 42 of the LED light source 19 from coming into contact when the light guide plate 13 is expanded by the heat of the LED light source 19 during the operation of the backlight unit. The shape, structure, etc. are not particularly limited.

However, depending on the shape, the following effects may be obtained.
FIG. 9 is a cross-sectional view showing Modification 3 of the facing member according to the embodiment. In FIG. 9, the lower side of the light guide plate 13 is mainly shown, and the lower side of the light guide plate 13 will be mainly described. However, the upper side of the light guide plate has the same structure.

  In the embodiment, the screw member 45 is used as the facing member 43 and the screw member 45 has a restriction function. However, other members may have the restriction function. In the third modification, the heat sink 101 has a restriction function.

  The heat sink 101 has a mounting groove 105 for the module 103 constituting the LED light source. The mounting groove 105 is provided in a portion of the heat sink 101 that faces the lower side surface 13 b of the light guide plate 13. Note that the module 103 includes a substrate 107, an LED element 108, and a sealing body 109, as in the embodiment, and the light emitting body includes the LED element 108 and the sealing body 109.

  A part 111 of the facing surface of the heat sink 101 facing the lower side surface 13b of the light guide plate 13 is the module 103 (light-emitting body) when the module 103 is mounted in the mounting groove 105 by a known means (screw member, adhesive, etc.). ) Is higher.

  That is, the distance between the lower side surface 13b of the light guide plate 13 and the part 111 of the opposing surface of the heat sink 101 is smaller than the distance between the lower side surface 13b of the light guide plate 13 and the light emitter. Thereby, a part 111 of the facing surface of the heat sink 101 has the same function as the facing member in the embodiment and the like.

  FIG. 10 is a cross-sectional view showing Modification 4 of the facing member according to the embodiment. In FIG. 10, the lower side of the light guide plate 13 is mainly shown, and the lower side of the light guide plate 13 will be mainly described, but the upper side of the light guide plate has the same structure.

In the embodiment, the screw member 45 is provided as the counter member 43, and the heat sink 101 is provided with the restriction function in the modification 4, but other members can be provided with the same function.
The facing member according to the modified example 4 includes a positioning member 131 for positioning the heat sink 17 and the LED light source 19.

  As the positioning member 131, a pin member 133 is used, and is protruded at a predetermined position of the housing body 21. Specifically, the pin member 133 is welded (welded) to the housing body 21 in a state where the pin member 133 is inserted from the outside into the through hole 135 formed in the housing body 21.

  The LED light source 19 and the heat sink 17 have through holes 19a and 17a at positions corresponding to the pin member 133, and the through hole 19a of the LED light source 19 and the through hole 17a of the heat sink 17 are fitted into the pin member 133 at the time of assembly. It is done.

  The opposing surface 133 a of the pin member 133 that faces the lower side surface 13 b of the light guide plate 13 is higher than the LED light source 19 (light emitter) when the LED light source 19 is mounted on the heat sink 17.

That is, the distance between the lower side surface 13b of the light guide plate 13 and the facing surface 133a of the pin member 133 is smaller than the distance between the lower side surface 13b of the light guide plate 13 and the light emitter. Thereby, the opposing surface 133a of the pin member 133 has the same function as the opposing member in embodiment etc.
(2) Shape The opposing member 43 of the embodiment and the opposing member such as a modification or a member having a regulating function (these members are hereinafter referred to as “opposing member 43 etc.”) are light guide plates that thermally expand during driving. The part which contacts 13 has a flat shape. When the contact portion is flattened in this way, when the light guide plate 13 and the facing member 43 or the like come into contact, the stress received by the light guide plate 13 from the contact portion such as the facing member 43 or the like has a sharp shape or dome. As a result, the load applied to the light guide plate 13 by the counter member can be reduced.

On the other hand, when the surface facing the upper and lower side surfaces 13a, 13b of the light guide plate 13 in the facing member of the embodiment has, for example, a hemispherical shape or a dome shape, the facing member has a flat shape (for example, in the embodiment) Compared with the counter member 43.), the light from the LED light source 19 can be prevented from being blocked by the corners of the counter member, and as a result, the light extraction efficiency from the LED light source 19 can be improved.
(3) State Before Driving The facing member 43 and the like of the embodiment has the facing surface 45a closer to the light guide plate 13 than the facing surface of the LED light source 19, for example, before driving, the LED The facing surface of the light source is located closer to the light guide plate than the facing surface of the facing member or the like, and the facing surface of the facing member is closer to the light guide plate than the facing surface of the LED light source during driving. good.

Specifically, it can be implemented by configuring the facing member with a material having a higher thermal expansion coefficient than that of the LED element or sealing body (that is, the light emitting body) used for the LED light source.
(4) Material Although materials such as the facing member are not particularly described in the embodiments, etc., rigidity and hardness that can restrict further thermal expansion of the light guide plate toward the light emitter when contacting the light guide plate during driving. As long as it has.
(5) Others In addition to the above-described facing member, for example, a dummy LED element that does not contribute to light emission may be used as the facing member. Needless to say, this dummy LED element is larger (higher) than the light emitter used as the light source, or the side of the light guide plate is larger than the surface of the light emitter used as the light source. It needs to be convex so that it is close to. That is, the dummy LED element needs to be relatively higher than the light emitter.
3. LED Light Source The LED light source 19 of the embodiment or the like is a module type, and includes a substrate 37, a plurality of LED elements 39 mounted on the substrate 37, and a sealing body 41 that seals each LED element 39. However, the sealing body may be configured to collectively seal a plurality of LED elements, or to collectively seal several of the plurality of LED elements.

  Further, the LED light source 19 according to the embodiment is formed by mounting a plurality of LED elements 39 on the substrate 37 in a row. For example, a plurality of LED elements may be mounted in a plurality of rows in a staggered manner. Also in this case, the sealing body may seal one LED element or a plurality of LED elements.

  Moreover, the LED light source 19 of embodiment etc. has two with respect to each side surface of the upper-and-lower side surfaces 13a and 13b of the light-guide plate 13, and it is distribute | arranged along each side surface 13a and 13b. However, the LED light source may be a long shape in which two LED light sources are combined into one.

  Furthermore, although the LED light source 19 is configured by mounting the LED element 39 on the substrate 37, for example, an insulation process may be performed on the heat sink, and the LED element may be directly mounted on the heat sink.

The LED light source 19 is arranged on the two side surfaces of the upper and lower side surfaces 13a and 13b of the light guide plate 13. However, the LED light source 19 may be arranged on one side surface of the upper and lower side surfaces, Alternatively, it may be arranged with respect to one of the two left and right side surfaces.
4). Positional relationship between the light guide plate and the opposing member In order to prevent the LED light source from being damaged by being pressed by the light incident surface of the light guide plate, as described above, the surface of the light emitter (facing the light incident surface of the light guide plate). It suffices if the head of the facing member (the facing portion facing the light incident surface of the light guide plate) is higher than the surface) (the position close to the light incident surface of the light guide plate).

  For example, when the height from the substrate 37 to the head (opposing surface) of the light emitter (H2 in FIG. 5) is 0.65 (mm), the opposing portion (mostly) of the opposing member from the surface of the substrate 37 The height to the light guide plate side (the portion located at the light guide plate side) (H3 in FIG. 6) may be 0.65 (mm) or more.

  However, when the height of the facing member extending from the substrate is high and the facing portion of the facing member is too close to the light incident surface of the light guide plate, when the light guide plate is thermally expanded, A new problem may occur that the light guide plate comes into contact with the light guide plate easily and the light guide plate is warped.

  On the other hand, when the height of the opposing member is low and the distance between the surface (opposing surface) of the light emitter and the head (opposing portion) of the opposing member is short, when the light guiding plate thermally expands, the light guiding plate And the illuminant may come into contact with each other, and the LED light source may be damaged. Therefore, the distance (before expansion) between the LED light source (light emitting body) and the head (opposed portion) of the opposing member is preferably 0.2 (mm) or more and 0.3 (mm) or less.

  Further, when designing the distance between the LED light source and the head of the opposing member, it is preferable to consider the extension amount of the light guide plate. The extension of the light guide plate is equal to the length of the side of the light guide plate perpendicular to the LED light source (the length in the short (vertical) direction when the light guide plate is viewed from the liquid crystal panel side). It can be calculated by integrating the linear expansion coefficient.

For example, 37 inches (840 (mm) × 470 (mm)) of acrylic resin (linear expansion coefficient in consideration of temperature at lighting is 7 to 8 × 10 ⁻⁵ ) is used as a light guide plate in the short direction. When adopting the edge light system in which the LED light sources are arranged vertically, that is, along the longitudinal direction, 470 × 7 × 10 ⁻⁵ = 0.03 (mm) is calculated as the extension amount of the light guide plate, and the length In consideration of the light extraction efficiency from the LED light source and the like. The distance from the head of the opposing member to the light incident surface of the light guide plate is preferably designed to be larger than the design tolerance of the side of the light guide plate facing the LED light source.

  The present invention is applicable to a backlight unit and a liquid crystal display device that are not easily affected by thermal expansion of the light guide plate during operation.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 3 Liquid crystal panel 5 Backlight unit 7 Case 9 Case 11 Optical system sheet 13 Light guide plate 17 Heat sink 19 Light source 37 Substrate 39 LED element 41 Sealing body 43 Fixing member (opposing member)
45 Screw member

Claims (6)

In an edge type backlight unit in which a light source having a light emitter is disposed in close proximity to the side surface of the light guide plate,
The back is characterized in that there is a counter member at a position facing the side surface of the light guide plate and where the light emitter does not exist, and the relative height of the counter member is higher than the height of the light emitter. Light unit. The light source includes the light emitter on a substrate,
The backlight unit according to claim 1, wherein the facing member is provided in a portion of the substrate where no light emitter exists. The light source is mounted along a side surface of the light guide plate and attached to a heat sink that emits heat when the light emitter emits light by a fixing member,
The backlight unit according to claim 1, wherein the facing member is the fixing member. The backlight unit according to any one of claims 1 to 3, wherein an end of the facing member on the light guide plate side has a hemispherical shape. The backlight unit according to claim 1, wherein an end of the facing member on the light guide plate side has a flat shape. In a liquid crystal display device having a backlight unit and a liquid crystal panel,
The said backlight unit is a backlight unit of any one of Claims 1-5. The liquid crystal display device characterized by the above-mentioned.

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