JP2014026838A - Backlight assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight assembly capable of maintaining uniform brightness.SOLUTION: There is provided a backlight assembly 120 including a lower chassis 102 having a bottom surface 102A and a side face 102B, a light guide plate 123 housed in the lower chassis 102 and having an emission surface 123B and an incident surface 123A, and a light source substrate 124A mounted with an LED 124B having its light emission surface opposed to the incidence surface 123A. The light source substrate 124A is incorporated in the lower chassis 102 to move in a direction orthogonal to the light emission surface, and the light guide plate 123 is incorporated in the lower chassis 102 to extend and contract in a spread direction of the emission surface 123B; a leaf spring which puts the LED closer to the side of the light guide plate 123 is provided between the light source substrate 124A and a side face 102B of the lower chassis, and the light source substrate 124A includes an abutting part for following up in an extension direction of the light guide plate 123, which is operated by the leaf spring and also operated reversely by the light guide plate 123.

Description

  The present invention relates to a backlight assembly, and more particularly, to a backlight assembly that maintains uniform brightness.

  The liquid crystal display device is characterized by energy saving and thinning, and has replaced the conventional CRT. The liquid crystal display device includes a liquid crystal display panel and an illumination device (backlight), and forms an image by controlling the transmittance of light emitted from the backlight on the back surface of the liquid crystal display panel. Light emitting diodes, cold cathode fluorescent lamps, and the like are known as backlight light sources. In recent years, in response to demands for further energy saving and thinning, a side backlight method has been adopted in which a light source of a backlight is attached to the side of a light guide plate.

In the side backlight method, the light utilization efficiency can be improved by reducing the distance (incident distance) between the light guide plate and the light source. However, the light guide plate expands or contracts due to changes in the surrounding environment such as temperature and humidity. Since there is a problem that the incident distance changes, there is a limit to making the distance closer.
A technique described in Patent Document 1 is known as an object that aims to maximize the light utilization efficiency and eliminate the change in incident distance with time and make the luminance of the backlight uniform. According to this technology, the light guide plate and the light source substrate on which the light source is mounted are coupled at the end of the light guide plate, and the both operate integrally, thereby solving the problem. Patent Document 2 also introduces a technique having the same gist.

JP 2011-119218 A JP 2011-150264 A

  By combining the light guide plate and the light source substrate so as to operate integrally, there arises a new problem that cannot be overlooked even if the above problem is solved. In order to couple the light guide plate and the light source substrate, it is necessary to provide a coupling means on both sides, and in order to provide an engagement protrusion or drill an engagement hole, a new processing work is required. Furthermore, since the coupling means is provided, the side end portion of the light guide plate is removed from the effective emission range, and a defective portion is generated on the emission surface of the light guide plate, which may hinder the effective use of the light guide plate.

  The present invention has been made in view of such problems, and one object is to provide a backlight assembly capable of maintaining uniform brightness. Another object is to provide a backlight assembly capable of improving the utilization efficiency of light emitted from a light source. A further object is to provide a backlight assembly that can improve the effective use of the light exit surface of the light guide plate.

The backlight assembly of the present invention includes (1) a lower chassis having a bottom surface and a housing space formed from a side surface extending in the shape of a vertical wall on the periphery of the bottom surface, and a back surface of a display panel housed in the housing space. A light guide plate that is assembled and has a light incident surface on at least a part of the light exit surface and the side surface, a light source that directs the light emission surface toward the light incident surface of the light guide plate, and one or more of the light sources are mounted. A light source substrate, wherein the light source substrate is assembled to the lower chassis so as to be movable in a direction orthogonal to the light emitting surface of the light source, and the light guide plate is disposed on the light emitting surface. A bullet which is assembled to the lower chassis so as to be expandable and contractable in the spreading direction, and exerts a force between the light source board and the side surface of the lower chassis facing the light source plate in a direction to bring the light source closer to the light guide plate. A light source board is provided with follower means for following at least the extension of the light guide plate along the direction perpendicular to the light emitting surface of the light source plate, and the distance between the light source and the light guide plate is The light source substrate is characterized in that the light source substrate receives the action from the elastic member and receives the action opposite to the action from the light guide plate through the follower means so as to be maintained constant.

According to this invention, the distance between the light source and the light guide plate is kept constant. As a result, since a certain amount of light emitted from the light source is incident on the incident surface of the light guide plate, uniform brightness in the backlight assembly can be maintained. Furthermore, since the distance between the light source and the light guide plate is kept constant, the distance can be made closer. As a result, the ratio of the total amount of light incident on the incident surface of the light guide plate to the total amount of light emitted from the light source can be improved (improvement of light utilization efficiency).
Furthermore, according to the present invention, since a specially processed portion is not required for the light guide plate, the effective use of the plate surface (light exit surface) of the light guide plate can be improved.

The elastic member may be a metal or resin leaf spring or coil spring, or may be formed from an elastic member such as rubber or elastomer. The elastic member is preferably provided between the light source board and the side surface of the lower chassis, and may be fixed to the light source board or the lower chassis.
The follow-up means has a structure having a butting surface that is brought into contact with the side surface of the light guide plate, for example, and may follow the movement of the light guide plate when it is extended, or it follows the light guide plate when it is extended and contracted. Such an engagement structure may be provided. At this time, the engaging means provided on the light guide plate side preferably has a structure provided on the side surface.

  Preferably, in the backlight assembly of the present invention, (2) the elastic member includes a plate-like spring having at least one end as a supporting portion, and the supporting portion is fixed to the side surface of the light source board or the lower chassis. It has a characteristic and is described in (1).

  According to the present invention, since the leaf spring is provided between the light source board and the side surface of the lower chassis, a force acting on each other acts between the light source board and the lower chassis. The leaf spring may be, for example, a cantilevered leaf spring having a plate-like one end as a support portion and the other end as an action portion, or the whole is bent into a U-shape and its apex portion becomes an action portion, It may be a leaf spring having at least one end as a support portion. The leaf spring may be made of metal or resin.

  The plate spring fixing means may be a screw type, a fitting type, a hook type, or the like. For example, when fixing to the light source substrate with a screw type, a fixing method of the end fixing portion with a clasp may be used. . In particular, when it is mounted on the lower chassis side, a fixing method for fixing the side surface of the lower chassis may be provided.

  Preferably, in the backlight assembly of the present invention, (3) the leaf spring is a dog-shaped leaf spring having both ends as support portions and a central portion as an action portion, one support portion being fixed, and the other being (2) is characterized in that the support portion is slidably supported.

According to this invention, a leaf | plate spring is a dogleg shape, the support part of one end is fixed, and the other support part is supported so that sliding is possible. Thereby, when a leaf | plate spring deform | transforms with load, the position of a support part can also be displaced. Thereby, since load is distributed to the whole leaf spring, the sag of the leaf spring is suppressed.

  Preferably, the backlight assembly of the present invention is characterized in that (4) the follow-up means is a butted portion that is butted against a part of a side surface including the incident surface of the light guide plate. Is described in one item.

  According to the present invention, the light source substrate is provided with the abutting portion, and the abutting surface provided in the abutting portion contacts the side surface of the light guide plate. Thereby, the light source substrate can move integrally following the extension of the light guide plate.

  Preferably, the backlight assembly of the present invention is characterized in that (5) the butting surface of the butting portion is provided so as to be substantially flush with the light emitting surface of the light source or shifted toward the light guide plate (4 ).

  According to this invention, the contact surface is disposed so as to be shifted toward the light guide plate with respect to the light emitting surface of the light source. As a result, the side surface of the extending light guide plate does not contact the light emitting surface of the light source but abuts against the abutting surface, so that the light source substrate can move integrally with the light guide plate without being damaged by the extension of the light guide plate. .

FIG. 1 is a configuration perspective view of a backlight assembly and a liquid crystal display device using the backlight assembly according to the first embodiment. FIG. 2 is a structural perspective view of the backlight assembly according to the first embodiment. FIG. 3 is a cross-sectional view taken along line III-III of the backlight assembly of FIG. FIG. 4 is an external perspective view of the light source unit constituting the backlight assembly according to the first embodiment. 5A and 5B are leaf springs incorporated in the backlight assembly according to the first embodiment. FIG. 5A is an external perspective view, and FIG. 5B is a plan view. FIG. 6 is a partially enlarged view of the light source substrate constituting the backlight assembly according to the first embodiment. FIG. 7 is an enlarged cross-sectional view of a main part of the backlight assembly according to the first embodiment. FIG. 8 is an enlarged cross-sectional view of a main part of the backlight assembly according to the first embodiment. FIG. 9 is an enlarged view of a main part of the backlight assembly according to the second embodiment. FIG. 10 is an enlarged cross-sectional view of a main part of the backlight assembly according to the third embodiment. FIG. 11 is an enlarged cross-sectional view of a leaf spring according to the third embodiment. FIG. 12 shows a light source unit incorporating a leaf spring according to the third embodiment. FIG. 13 is an enlarged perspective view of a leaf spring according to the fourth embodiment.

Although embodiments of the present invention will be described with reference to the accompanying drawings, the technical scope of the present invention is not limited by these embodiments, and can be implemented without departing from the spirit of the invention. FIG. 1 is a configuration perspective view of a backlight assembly according to the first embodiment and a liquid crystal display device using the backlight assembly. FIG. 2 is a structural perspective view of the backlight assembly according to the first embodiment. FIG. 3 is an external perspective view of a light source unit constituting the backlight assembly according to the first embodiment. The instruction direction used in the following description is
According to the definition of the direction described in the drawing.

<Outline of liquid crystal display device>
As shown in FIG. 1, the liquid crystal display device 1 in which the backlight assembly 120 according to the first embodiment is incorporated includes a liquid crystal panel assembly 110 including a liquid crystal display panel 111 and a backlight assembly 120 including a backlight. In this structure, the upper chassis 101 and the lower chassis 102 are fixed to the superposed one. The upper chassis 101 is a frame-shaped molding material that overlaps the peripheral edge of the liquid crystal display panel 111 and is made of synthetic resin or metal. The lower chassis 102 is a box-shaped molding material having an accommodation space for accommodating the liquid crystal panel assembly 110 and the backlight assembly 120.

The liquid crystal display panel 111 has a structure in which liquid crystal is sandwiched between two glass substrates, controls the alignment state of liquid crystal molecules constituting the liquid crystal, and changes the transmittance of light irradiated from the back surface. The image is displayed on the front side.
The liquid crystal display panel 111 has a source printed circuit board 113 provided with a control unit for controlling the alignment of liquid crystal molecules at the edge thereof, and a chip film package 112.

The backlight assembly 120 includes a light guide plate 123, an LED 124B (Light Emitting Diode) that emits light, and a light source unit 124 on which the LED 124B is mounted on a light source board 124A. The light source unit 124 is movably held in the lower chassis 102. ing.
Here, the instruction direction being described is defined. Based on the posture when the liquid crystal display device 1 is used, the front side of the page is down, the opposite side is up, the upper side of the page is front, the opposite side is back (also called the back), the right hand side of the page is right, The opposite side is on the left.

<Backlight assembly>
The backlight assembly 120 will be described with reference to the drawings. FIG. 2 is a structural perspective view of the backlight assembly according to the first embodiment. FIG. 3 is a cross-sectional view taken along line III-III of the backlight assembly of FIG. FIG. 4 is an external perspective view of the light source unit constituting the backlight assembly according to the first embodiment. 5A and 5B are leaf springs incorporated in the backlight assembly according to the first embodiment. FIG. 5A is an external perspective view, and FIG. 5B is a plan view. FIG. 6 is a partially enlarged view of the light source substrate constituting the backlight assembly according to the first embodiment.

As shown in FIG. 2, the backlight assembly 120 is a structure in which the light guide plate 123, the LED 124 </ b> B, and the light source unit 124 in which the LED 124 </ b> B is mounted on the light source substrate 124 </ b> A are assembled in the lower chassis 102.
As shown in FIGS. 2 and 3, the lower chassis 102 includes a bottom surface 102A that spreads in a plate shape and a side surface 102B that extends in a vertical wall shape from the peripheral edge thereof. The bottom surface 102A includes a concave recess 102C in front of the side end where the side surface 102B rises. The indented portion includes a receiving portion 102D that vertically stands inside. The side surface 102B rises substantially perpendicular to the bottom surface 102A. The tip of the side surface 102B is provided with a turn to increase the material strength of the edge.

The lower chassis 102 is a box having an accommodation space, and accommodates therein a light guide plate 123 that is a main part of the backlight assembly 120 so as to be movable in the vertical and horizontal directions.
As shown in FIG. 2, the light guide plate 123 is a thin flat rectangular body having an emission surface 123 </ b> B on the front surface, a reflection surface 123 </ b> C on the back surface, and a side surface 123 </ b> D on the periphery, and is formed on the bottom surface 102 </ b> A of the lower chassis 102. They are assembled in parallel. In the case of the first embodiment, the left side surface 123D and the right side surface 123D of the light guide plate 123 function as an incident surface 123A on which light emitted from the LED 124B is incident. Of course, an aspect in which the incident surface 123A is provided only on one side may be employed.

  The light guide plate 123 reflects the light incident from the incident surface 123A by the light extraction means built inside and emits the light from the front emission surface 123B, and is made of a transparent resin material such as acrylic or polycarbonate. It may be a molding material. For the light extraction means, a fine structure or a method of dispersing a scattering material in the light guide plate is used, and light control for each region can be performed by dividing control of the emission surface 123B. In addition, the light guide plate 123 includes a reflective surface 123C on the back surface, and reflects light deviated on the back surface side in a necessary direction.

An optical sheet 122 is overlaid on the exit surface 123B of the light guide plate 123, and the optical sheet 122 can improve the uniformity of luminance by controlling the angular distribution of the emitted light, for example.
The light guide plate 123 is accommodated in the lower chassis 102 so as to be extendable in the vertical direction and the horizontal direction. The light guide plate 123 is supported by the lower chassis 102 so that the planned expansion / contraction operation is not restricted.

<Light source unit>
As shown in FIG. 4, the light source unit 124 includes LEDs 124 </ b> B as light sources, and a light source substrate 124 </ b> A having a circuit pattern for mounting the LEDs 124 </ b> B in a line direction and applying drive power to the LEDs 124 </ b> B. Furthermore, the light source unit 124 includes abutting portions 124C near both ends in the long side direction of the light source substrate 124A.
The light source unit 124 is provided at the side end of the light guide plate 123 in a posture in which the light emitting surface 124B1 of the LED 124B is opposed to the incident surface 123A of the light guide plate 123, and is attached to the lower chassis 102 so as to move in conjunction with the expansion and contraction operation of the light guide plate 123. It is supported. In the first embodiment, the left and right light source units 124 are provided as a pair, but since both have the same basic configuration, only the left light source unit 124 will be described in order to avoid redundant description.

  The light source is the LED 124B, and the LED 124B is three-dimensionally packaged with resin around the element with the built-in element (hereinafter, the packaged state is also referred to as the LED 124B). The LED 124B includes a mounting lead on the bottom surface, and the light emitting axis is oriented in the horizontal direction in the mounting posture. The light emitted from the LED 124B travels straight in parallel to the light emission axis, but there are also light that deviates from this and travels at an angle. Therefore, the distance between the LED 124B and the light guide plate 123 (hereinafter referred to as the “incident distance”) is better in order to reduce the loss of the light emitted from the LED 124B and efficiently enter the light incident surface 123A of the light guide plate 123.

As shown in FIG. 4, a plurality of LEDs 124 </ b> B are mounted on the light source substrate 124 </ b> A in parallel with the light emitting surface 124 </ b> B <b> 1 facing the incident surface 123 </ b> A of the light guide plate 123. Although LED124B which concerns on this 1st embodiment is a white light emitting diode, it is not restricted to this, You may light-emit white light combining red, blue, and green. In the case of the first embodiment, the light source unit 124 corresponding to the incident surface 123A of the light guide plate 123 is composed of one light source substrate 124A, but is not limited to this, and two or more light source substrates are used. 124A
It may be a split-type configuration constituted by:

As shown in FIG. 4, the light source substrate 124 </ b> A has a rectangular shape and a long side that is sufficiently longer than the short side, and is substantially equal to the length of the incident surface 123 </ b> A of the corresponding light guide plate 123. The short side is sufficient for mounting the LED 124B, but unnecessary space is saved as much as possible.
The light source substrate 124A may be made of a material made of, for example, an aluminum alloy in consideration of heat dissipation. In this case, the light source substrate 124A may be provided with a cooling device and heat dissipation fins. Of course, the material is not limited to a metal material, and may be composed of an epoxy resin material mixed with glass beads, or may be a ceramic-like ceramic.

<Leaf spring>
As shown in FIG. 4, the leaf spring 130 is attached to the light source substrate 124 </ b> A on the opposite side (back side) to the side (front side) where the LED 124 </ b> B is mounted. A plurality of leaf springs 130 are attached to the back surface of the light source substrate 124A so as to be along the edge on the long side. The leaf spring 130 is mounted such that the apex portion 130A faces outward (left) and the apex portion 130A does not protrude outward from the long side edge of the light source substrate 124A.

  The plate spring 130 may be a rigid plate or wire. For example, it is preferable if an iron-based alloy such as stainless has characteristics such as spring steel by appropriate heat treatment. In the first embodiment, the leaf spring 130 is used as the elastic member, but is not limited to the leaf spring 130. For example, it may be a coil spring or may be formed from an elastic material such as rubber or elastomer.

  As shown in FIG. 5, the leaf spring 130 is shaped like a band in a plan view and extends in a band shape, and both ends are curved inward. The curved portions 130 </ b> B and 130 </ b> C support the light source substrate 124 </ b> A with a support member and a fixing member. And fixed. The curved portion is U-shaped, one curved portion 130B (fixed portion) is fixed in a fixed state by a fixing member, and the other curved portion 130C (support portion) slides along the U-shaped parallel piece. It is supported by a support member as possible. The leaf spring 130 has a partly flat surface at the apex portion 130 </ b> A of the U shape, and elastically contacts the corresponding side surface 102 </ b> B of the lower chassis 102 with this flat surface. In the case of the first embodiment, one end of the leaf spring 130 is fixed and the other end is slidably supported, so that the load applied to the leaf spring 130 can be dispersed throughout the leaf spring. However, it is of course not limited to this form, and both ends may be fixed, or both ends may be slidably supported. Good.

As shown in FIG. 4, the leaf spring 130 has a posture in which the central portion including the apex portion 130A does not protrude outward (leftward) from the side surface on the long side of the light source substrate 124A. The curved portion is fixed and supported as a fixed portion 130B and a support portion 130C on the back surface. When the leaf spring 130 receives an inward (rightward) force from the outside at the apex 130A, the leaf spring 130 supports the curved portions 130B and 130C at both ends while accumulating an outward (leftward) repulsive force around the apex 130A. The whole is deformed inward (rightward) while making it a point.
When the load is released or weakened, the leaf spring 130 can apply this repulsive force to the outside and displace the light source unit 124 integrally.

<Matching section>
The abutting portion 124C receives a pressing force generated by the extension of the light guide plate 123 and integrally displaces the light source unit 124 in the direction in which the force is applied. The abutting portion 124C is preferably provided at both ends of the light source substrate 124A so as not to obstruct the emission of the LED 124B and considering the balance of force, but is not limited to this embodiment.
The abutting portion 124C may be, for example, a block-like structure having a flat abutting surface 124C1 described in the first embodiment on one side, or a thin metal plate, as long as it meets the purpose. It may be an L-shaped metal piece which is bent 90 degrees to make one piece a fixed part and one piece to be abutting surface. In any case, the connection means to the light source substrate 124A may be a solder mounting method, a screw method, or a connection means using an adhesive substance such as tape or glue. Alternatively, a part or the whole of the side surface (cut surface) of the light source substrate 124A may function as the butting surface 124C1.

As shown in FIGS. 3 and 4, the abutting portion 124 </ b> C is provided on the front surface of both upper and lower ends of the light source substrate 124 </ b> A. The abutting portion 124C is a block-like structure having a flat abutting surface 124C1 on one side surface, and is fixed to the light source substrate 124A by a screw method. The abutting portion 124C is provided such that the abutting surface 124C1 is located on the light guide plate 123 side (right side) with respect to the LEDs 124B arranged side by side to some extent from the light emitting surface 124B1. Thereby, it is possible to avoid collision between the light guide plate 123 and the LED 124B, which may occur depending on assembly tolerances of the LED 124B and variations in package dimensions. However, as the distance (incident distance) between the light guide plate 123 and the LED 124B increases, the light use efficiency decreases, and it is of course desirable to reduce these tolerances and errors to reduce the incident distance.

<Assembly>
The assembly of the backlight assembly 120 will be described with reference to the drawings.
As shown in FIGS. 2 and 3, the light source unit 124 elastically contacts the vertex portion 130A of the leaf spring 130 with the receiving portion 102D provided in the recess portion 102C of the bottom surface 102A, while the butting portion 124C. Are assembled into the lower chassis 102 in a posture facing the side surface 123D of the light guide plate 123 to be assembled later. At this time, the light emitting surface 124B1 of the LED 124B is adjusted to a height toward the incident surface 123A of the light guide plate 123 so that the emitted light is efficiently incident on the light guide plate 123. As shown in FIG. 6, the light source substrate 124 </ b> A is supported by a clasp 124 </ b> A <b> 2 so as to be movable in the left-right direction through elongated holes 124 </ b> A <b> 1 drilled at both ends thereof. The leaf spring 130 makes the apex portion 130A elastically contact the receiving portion 102D of the bottom surface 102A of the lower chassis 102, and stores a repulsive force corresponding to a slight deformation.

  When the light source unit 124 is assembled at a predetermined position of the lower chassis 102, as shown in FIGS. 2 and 3, a light guide plate 123 with necessary members mounted thereon is assembled. The light guide plate 123 itself expands and contracts mainly in the vertical direction and the horizontal direction due to changes in the surrounding environment, in particular, due to changes in humidity and heat generated from the LEDs 124B. The light guide plate 123 is supported by the lower chassis 102 in a state where it can move in such a manner. The light guide plate 123 assembled in the lower chassis 102 has the side surface 123D abutted against the abutting portion 124C in a state where the incident surface 123A provided on the left and right side surfaces 123D is opposed to the light emitting surface 124B1 of the LED 124B. In the first embodiment, the light guide plate 123 is assembled in such a state that the side surface 123D is in contact with the abutting portion 124C as described above. However, the present embodiment is not limited to this, and a slight gap is provided between the two. It may be provided and assembled.

  In a state where the light source unit 124 and the light guide plate 123 are assembled to the lower chassis 102, the light source unit 124 receives the repulsive force of the leaf spring 130 between the light receiving unit 102D and the receiving portion 102D of the bottom surface 102A of the lower chassis 102. The contact pressure is received from the light guide plate 123 by 124C.

<Action>
As shown in FIG. 3, the light source unit 124 receives a force applied in the left direction at the abutting portion 124 </ b> C when the light guide plate 123 expands. This force is transmitted to the leaf spring 130 and contracts the leaf spring 130, and the light source unit 124 moves by the contracted amount. Therefore, the displacement of the light guide plate 123 due to the expansion moves the light source unit 124 integrally with the light guide plate 123, whereby the incident distance between the light guide plate 123 and the LED 124B is kept constant. At this time, the leaf spring 130 is elastically deformed, and a repulsive force is applied to the light source unit 124.

As described above, the light source unit 124 always abuts the abutting portion 124 </ b> C against the light guide plate 123 while receiving a rightward force from the plate spring 130, but the repulsive force of the plate spring 130 is the expansion force of the light guide plate 123. Therefore, the light source unit 124 moves in conjunction with its movement without restricting the expansion of the light guide plate 123. On the other hand, the light guide plate 123 is changed by the change of the surrounding environment.
Since the light source unit 124 receives a repulsive force from the leaf spring 130, the light source unit 124 can move following the rightward movement of the light guide plate 123.

  Therefore, as shown in FIGS. 7 and 8, the light source unit 124 is not interlocked with the movement of the light guide plate 123 both when it is expanded and contracted, although no fixing means is provided between the light source unit 123 and the light guide plate 123. And move as one. Thereby, the incident distance between the incident surface 123A of the light guide plate 123 and the light emitting surface 124B1 of the LED 124B can always be kept constant. Here, FIG. 7 is an enlarged cross-sectional view of a main part of the backlight assembly according to the first embodiment. FIG. 8 is an enlarged cross-sectional view of a main part of the backlight assembly according to the first embodiment.

<Principle, action>
The light guide plate 123 is made of a resin such as acrylic, and is easily deformed by changes in the surrounding environment, particularly humidity and temperature, and the LED 124B is disposed near the entrance surface 123A. Is even bigger.

  In the case of the present invention, when considering the light utilization efficiency, the inventor is desirable that the incident distance between the light emitting surface 124B1 of the LED 124B and the incident surface 123A of the light guide plate 123 is closer, and the luminance of the backlight is uniform. However, in order to effectively use the entire plate surface of the light guide plate 123 constituting the irradiation surface of the backlight, a part of this surface is considered to be desirable. However, for example, under the policy of avoiding the occurrence of a defective portion by opening a hole or groove for the coupling means, as a result of repeated thinking, a coupling means is provided between the light guide plate 123 and the light source unit 124. Thus, the inventors have conceived the technical idea of the present invention in which the light guide plate 123 and the light source unit 124 move in association with each other while keeping the proximity distance constant.

  When the light guide plate 123 expands, as shown in FIG. 7, the light source unit 124 receives the force at the butting portion 124C and moves so as to contract the leaf spring 130 by the amount of displacement caused by the expansion. Accordingly, the expansion of the light guide plate 123 is moved in cooperation with the light source unit 124 without being limited by the abutting portion 124C. Therefore, the incident distance between the light emitting surface 124B1 of the LED 124B and the incident surface 123A of the light guide plate 123 is kept constant.

  When the light guide plate 123 contracts, as shown in FIG. 8, the light source unit 124 acts on the light guide plate 123 moving away from the butt portion 124 </ b> C by the repulsive force of the compressed leaf spring 130. Move together. Therefore, the incident distance between the light emitting surface 124B1 of the LED 124B and the incident surface 123A of the light guide plate 123 is kept constant.

<Effect> In the first embodiment, the following effects can be obtained.
The backlight assembly 120 according to the first embodiment includes a butt portion 124 </ b> C in the light source unit 124. Thereby, the light source unit 124 can be moved in conjunction with the expansion of the light guide plate 123.
In the backlight assembly 120 according to the first embodiment, the light source unit 124 includes the abutting portion 124C, and the abutting surface 124C1 is located closer to the light guide plate 123 than the light emitting surface 124B1 of the LED 124B. Then, the side surface 123D hits the butting surface 124C1. Thereby, the possibility that the leading end of the light guide plate 123 collides with the LED 124B and is damaged due to the expansion of the light guide plate 123 is suppressed.

The backlight assembly 120 according to the first embodiment includes the leaf spring 130 in the light source unit 124. Thereby, the light source unit 124 can be moved in conjunction with the contraction of the light guide plate 123.
In the backlight assembly 120 according to the first embodiment, the incident distance between the light emitting surface 124 </ b> B <b> 1 of the LED 124 </ b> B and the incident surface 123 </ b> A of the light guide plate 123 is maintained constant even when the light guide plate 123 extends and contracts. Thereby, the brightness | luminance of the liquid crystal display panel 111 and a backlight is kept constant.

In the backlight assembly 120 according to the first embodiment, the incident distance between the light emitting surface 124B1 of the LED 124B and the incident surface 123A of the light guide plate 123 is maintained constant by the expansion and contraction of the light guide plate 123. The incident distance with the optical plate 123 can be set short. Thereby, the utilization efficiency of light is improved.
-The backlight assembly 120 which concerns on this 1st embodiment is provided with the leaf | plate spring 130, and the leaf | plate spring 130 is provided with the support structure which can guide one of the fixed parts in two places. Thereby, since the force concerning the leaf spring 130 due to the expansion of the light guide plate 123 can be ideally dispersed and received, the temporal deformation of the leaf spring 130 can be suppressed.

-Since the backlight assembly 120 which concerns on this 1st embodiment does not require a process for the light-guide plate 123, the output area of the light-guide plate 123 can be utilized effectively.
The backlight assembly 120 according to the first embodiment includes only the leaf springs 130 and the butting portions 124C on the light source substrate 124A, so that the cost can be minimized and the problem can be solved.
In the backlight assembly 120 according to the first embodiment, since the light source substrate 124A only includes the leaf spring 130 and the butting portion 124C, the problem can be solved without impairing workability.
The backlight assembly 120 according to the first embodiment includes only the leaf spring 130 and the butting portion 124C on the light source substrate 124A, so that the problem can be solved without sacrificing space efficiency.

  As mentioned above, although this invention was demonstrated based on 1st embodiment, this invention is not restricted to 1st embodiment mentioned above, A various change is possible within the range of the invention thought.

<Second embodiment>
The backlight assembly 120 according to the second embodiment will be described with reference to FIG. FIG. 9 is an enlarged view of a main part of the backlight assembly according to the second embodiment. In order to avoid redundant description, description of the same configuration as that of the invention according to the first embodiment is omitted, and description is added only to a different configuration.
The backlight assembly 120 according to the second embodiment is characterized in that the leaf spring 130 is provided on the side surface 102B of the lower chassis 102. The plate spring 130 has a cross-sectional shape in plan view, and the main portion has the same configuration as the plate spring of the first embodiment. Even when such a configuration is adopted, the above-described effects are generally achieved.

<Third embodiment>
A backlight assembly 120 according to a third embodiment will be described with reference to FIGS. FIG. 10 is an enlarged cross-sectional view of a main part of the backlight assembly according to the third embodiment. FIG. 11 is an enlarged cross-sectional view of a leaf spring according to the third embodiment. FIG. 12 shows a light source unit incorporating a leaf spring according to the third embodiment. In order to avoid redundant description, description of the same configuration as that of the invention according to the first embodiment is omitted, and description is added only to a different configuration.
The backlight assembly 120 according to the third embodiment is characterized in that the leaf spring 230 is provided on the side surface 102B of the lower chassis 102.

The leaf spring 230 has a hinge shape and includes an engaging portion 230B that engages with the side surface 102B of the lower chassis 102 at the corner, and one piece extending therefrom is an elastic piece 230A. The tip of the elastic piece 230A is an elastic contact surface that elastically contacts the side surface of the light source substrate 124A. The displacement of the light source unit 124 is received by the elastic contact surface, and the repulsive force of the leaf spring 230 is transmitted from the elastic contact surface to the light source unit 124. Even when such a configuration is adopted, the above-described effects can be obtained.

<Fourth embodiment>
A backlight assembly 120 according to a fourth embodiment will be described with reference to FIG. FIG. 13 is an enlarged perspective view of a leaf spring of the backlight assembly according to the fourth embodiment. In order to avoid redundant description, description of the same configuration as that of the invention according to the first embodiment is omitted, and description is added only to a different configuration.
The leaf spring backlight assembly 120 according to the fourth embodiment is characterized in that the leaf spring 330 is provided on the side surface 102B of the lower chassis 102.

  The leaf spring 330 has a hinge shape and includes an engaging portion 330B that engages with the side surface 102B of the lower chassis 102 at a corner portion, and includes an elastic piece 330A that extends from the engaging portion 330B and extends in the extending direction of the side surface. The elastic piece 330A is bent into a square shape, and the apex portion elastically contacts the side surface of the light source substrate 124A. The displacement of the light source unit 124 is received at the apex, and the repulsive force of the leaf spring 330 is transmitted to the light source unit 124 from the elastic contact surface. Even when such a configuration is adopted, the above-described effects can be obtained.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 101 Upper chassis 102 Lower chassis 102A Bottom surface 102B Side surface 102C Recessed part 102D Receiving part 110 Liquid crystal panel assembly 111 Liquid crystal display panel 112 Chip film package 113 Source printed circuit board 120 Backlight assembly 121 Mold frame 122 Optical sheet 123 Light guide plate 123A Incident surface 123B Outgoing surface 123C Reflective surface 123D Side surface 124 Light source unit 124A Light source substrate 124A1 Elongated hole 124A2 Clasp 124C Butt portion 124C1 Butt surface 124B LED
124B1 Light emitting surface 125 Reflector 130, 230, 330 Elastic member 130A Vertex 130B Fixing part 130C Supporting part 130D Spring part

Claims (5)

A lower chassis provided with a housing space formed from a bottom surface and a side surface extending like a vertical wall on the periphery of the bottom surface;
A light guide plate that is housed in the housing space, is assembled on the back surface of the display panel, and has a light incident surface on at least a part of the emission surface and the side surface;
A light source that directs a light emitting surface to the incident surface of the light guide plate;
A light source substrate on which one or more of the light sources are mounted;
A backlight assembly comprising:
The light source substrate is assembled to the lower chassis so as to be movable at least in a direction perpendicular to the light emitting surface of the light source;
The light guide plate is assembled to the lower chassis so that it can be expanded and contracted in the direction in which the exit surface spreads,
An elastic member is provided between the light source substrate and the side surface of the lower chassis opposite to the light source substrate to apply a force in a direction in which the light source approaches the light guide plate,
The light source substrate includes tracking means for following at least the extension of the light guide plate along the direction perpendicular to the light emitting surface of the light source, and the distance between the light source and the light guide plate is maintained constant. Thus, the light source substrate is characterized in that it receives the action from the elastic member and receives the action opposite to the action from the light guide plate via the follower.   The backlight assembly according to claim 1, wherein the elastic member includes a plate-like spring having at least one end as a support portion, and the support portion is fixed to the side surface of the light source board or the lower chassis.   The leaf spring is a U-shaped leaf spring having both ends as support portions and a central portion as an action portion, where one support portion is fixed and the other support portion is slidably supported. The backlight assembly of claim 2 having features.   4. The backlight assembly according to claim 1, wherein the follower is a butting portion that is butted against a part of a side surface including the incident surface of the light guide plate. 5.   The backlight assembly according to claim 4, wherein a butting surface of the butting portion is provided so as to be substantially flush with the light emitting surface of the light source or shifted toward the light guide plate.

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