JP5578559B2 - Backlight unit and liquid crystal display device - Google Patents

Description

  The present invention relates to a backlight unit used for illumination of a liquid crystal display panel or the like and a liquid crystal display device including the backlight unit.

  Liquid crystal display devices for displaying images are widely used as displays for car navigation devices, notebook PCs (personal computers), mobile type PCs, PDAs, ATMs (automated teller machines), mobile phones and the like. This liquid crystal display device uses a backlight unit that emits light from the back side of the liquid crystal display panel to increase the brightness of the display screen.

In this backlight unit, a light guide plate that guides light from a light source such as a fluorescent tube or an LED and emits the light from the entire main surface toward the liquid crystal display panel is used.
Conventionally, as a structure for supporting such a light guide plate, for example, Patent Document 1 describes a liquid crystal display device having a storage case made of metal for storing the light guide plate. In this liquid crystal display device, a metal storage case is used to efficiently dissipate heat generated from the LEDs. This storage case has a box shape with four side surfaces so as to surround the bottom surface and the four sides of the bottom surface. By mounting an LED on one of the side surfaces, the storage case serves as a heat sink. .

JP 2009-69713 A

However, the following problems remain in the conventional technology.
That is, in the light guide plate support structure described in Patent Document 1, in order to make the storage case serve as both a support body such as a light guide plate and a heat radiating plate, it is box-shaped and the LED mounting portion and the light guide plate A complex structure was required for support. For this reason, many metal plate processes, such as a bending process and a punching process, etc. were needed for metal plates, such as SUS, and there existed a problem that member cost increased significantly.
Further, as shown in FIG. 7, in order to avoid complicated sheet metal processing, the light guide plate 3 and the frame-shaped metal body 1 are divided into a frame-shaped metal body 1 which is a front case and a bottom metal plate 2 which is a back case. It is conceivable to fit and store the bottom metal plate 2 together with the reflection sheet 4 or the like, but in this case, there is a possibility that the metal frame-like metal body 1 and the bottom metal plate 2 rub against each other at the time of fitting to generate scraps. is there. If this metal shaving residue remains inside after incorporation, there is also a risk of causing an electrical short circuit.
In FIG. 7, reference numerals 5 and 6 are a reflective polarizing film and a brightness enhancement film, and reference numeral 7 is a diffusion sheet. Reference numeral 8 denotes a flexible printed circuit board (FPC) on which a light source L, which is an LED, is mounted. Reference numeral 9 denotes a holding frame for holding the light guide plate 3.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a backlight unit and a liquid crystal display device that can reduce the member cost and can reduce the generation of metal debris when the member is incorporated. And

  The present invention employs the following configuration in order to solve the above problems. That is, the backlight unit of the present invention includes a light guide plate, a light source that irradiates light to the light guide plate, guides the light, a reflection sheet installed on the back side of the light guide plate, and a back side of the reflection sheet. Installed resin support plate and a light source mounting surface installed on the back side or front side of the resin support plate, bent on one side to be opposed to the end surface of the light guide plate and mounting the light source A metal heat sink having a frame, and a frame-shaped housing that houses and supports the reflective sheet, the light guide plate, the resin support plate, and the metal heat sink, the frame-shaped housing, It is resin-molded and has a slide groove for guiding the resin support plate so that it can be inserted from one side.

  In this backlight unit, the frame-shaped housing is resin-molded and has a slide groove that guides the resin support plate so that it can be inserted from one side, so it is not a metal-to-metal fitting structure. Since the resin member is incorporated in a sliding manner, no metal debris is generated and an electrical short circuit can be prevented. In addition, since the frame-shaped housing is resin-molded, slide grooves and other parts can be easily formed, significantly reducing the cost of components compared to sheet metal processing into a complicated box-type fitting structure. can do. Furthermore, the heat generated from the light source can be efficiently radiated by the metal heat radiating plate provided separately.

In the backlight unit of the present invention, the light guide plate has a positioning light guide plate-side convex portion or a light guide plate-side concave portion on an outer periphery, and the frame-shaped housing is provided with the light guide plate-side convex portion or the light guide plate. It has a housing side concave portion or a housing side convex portion formed integrally so as to be fitted to the optical plate side concave portion.
That is, in this backlight unit, the frame-shaped housing has a housing-side concave portion or a housing-side convex portion that is integrally formed so as to be able to be fitted to the light guide plate-side convex portion or the light guide plate-side concave portion of the light guide plate. Therefore, the built-in light guide plate can be easily positioned by the corresponding light guide plate side convex portion or the light guide plate side concave portion and the case side concave portion or the case side convex portion. Note that the housing-side concave portion or the housing-side convex portion can be easily manufactured by integral molding, and it is not necessary to separately prepare a frame for holding the light guide plate, and the member cost can be further reduced.

Further, in the backlight unit of the present invention, the resin support plate protrudes up to the metal heat dissipating plate disposed on the back surface side, and has a protruding portion that holds the metal heat dissipating plate by integral molding. It is characterized by that.
That is, in this backlight unit, since the resin support plate has a protrusion portion that protrudes up to the metal heat dissipating plate disposed on the back surface side and holds the metal heat dissipating plate by integral molding, The holding function of the heat radiating plate can be easily given to the resin support plate.

In the backlight unit of the present invention, the frame-shaped housing is integrally formed so as to protrude inward and abut against the end surface of the light guide plate to press the light guide plate toward at least the light source mounting surface side. It has a convex part and the hole for elasticity provision integrally formed on the opposite side to the protrusion direction of the convex part for pressing in the vicinity of the convex part for pressing.
That is, in this backlight unit, the frame-shaped housing includes a pressing convex portion that presses the light guide plate toward at least the light source mounting surface side, and an elasticity applying hole portion integrally formed in the vicinity of the pressing convex portion. Therefore, the light guide plate is pressed against the light source mounting surface side with elasticity by the pressing convex portion and the elasticity imparting hole portion, and the distance between the light source and the light incident end surface of the light guide plate is kept constant. Positioning. As a result, the incorporated light guide plate can be prevented from rattling in the frame-shaped housing.

Moreover, the backlight unit of the present invention is characterized in that the frame-shaped housing is formed of a black resin.
That is, in this backlight unit, since the frame-shaped housing is made of black resin, it is difficult for light from the light source to be reflected on the inner surface of the frame-shaped housing, and the light leaks from the gap to the surface side. Can be suppressed.

The backlight unit of the present invention is characterized in that the frame-shaped housing has positioning pins that are integrally formed so as to protrude to the back surface side.
That is, in this backlight unit, the frame-shaped housing has positioning pins that are integrally formed so as to protrude to the back surface side, so that positioning pins for attaching the frame-shaped housing can be easily formed. Since it is not necessary to prepare a pin separately, the member cost can be further reduced.

The liquid crystal display device of the present invention includes a liquid crystal display panel and the backlight unit of the present invention disposed on the back side of the liquid crystal display panel.
That is, since this liquid crystal display device includes the backlight unit of the present invention disposed on the back side of the liquid crystal display panel, the liquid crystal display device can be manufactured at low cost and can prevent problems such as electrical shorts.

The present invention has the following effects.
That is, according to the backlight unit and the liquid crystal display device according to the present invention, the frame-shaped housing is resin-molded, and has a slide groove that guides the resin support plate so that it can be inserted from one side. As a result, no metal debris is generated at the time of incorporation, an electrical short can be prevented, and the cost of the member can be greatly reduced. Further, it is possible to use a recycled material as the resin used for the frame-shaped housing or the resin support plate, and an environment-friendly backlight unit can be realized. And since the resin ratio of a product member can be raised, recyclability can be improved.
As described above, according to the present invention, it is possible to obtain a backlight unit and a liquid crystal display device that can prevent the occurrence of metal debris and prevent electrical shorts, and that are inexpensive and excellent in recyclability.

1 is an exploded perspective view showing a backlight unit in an embodiment of a backlight unit and a liquid crystal display device according to the present invention. In the backlight unit of this embodiment, it is sectional drawing of the surface along the insertion direction of the resin-made support plates. In the backlight unit of this embodiment, it is the perspective view seen from the back surface side in the state fractured | ruptured in the surface along the insertion direction of the resin-made support plates. It is a top view which shows a frame-shaped housing | casing in the backlight unit of this embodiment. In the backlight unit of this embodiment, it is a top view which shows the frame-shaped housing | casing of the state which incorporated the light-guide plate (hatching part). It is an expanded sectional view of the important section showing the liquid crystal display device of this embodiment. In the reference example of the backlight unit and liquid crystal display device which concerns on this invention, it is a disassembled perspective view which shows a backlight unit.

  Hereinafter, an embodiment of a backlight unit and a liquid crystal display device according to the present invention will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size.

  As shown in FIGS. 1 to 3, the backlight unit 10 in the present embodiment is installed on the light guide plate 13, the light source L that guides the light guide plate 13 by irradiating light, and the back side of the light guide plate 13. The reflection sheet 14, the resin support plate 12 installed on the back surface side of the reflection sheet 14, and installed on the back surface side of the resin support plate 12 so that one side is bent and faces the end surface of the light guide plate 13. A metal heat sink 19 having a light source mounting surface on which the light source L is mounted, and a frame that houses and supports the reflection sheet 14, the light guide plate 13, the resin support plate 12, and the metal heat sink 19. And a housing 11.

In addition, the backlight unit 10 is disposed on the diffusion sheet 17 disposed on the light guide plate 13, the brightness enhancement film 16 that is a prism sheet disposed on the diffusion sheet 17, and the brightness enhancement film 16. And a reflective polarizing film 15, which are also housed in the frame-shaped housing 11.
Further, as shown in FIG. 6, the liquid crystal display device 20 of the present embodiment includes a liquid crystal display panel 21 and the backlight unit 10 disposed on the back side of the liquid crystal display panel 21.

The light source L is an LED light source mounted on a band-shaped mounting FPC (flexible printed circuit board) 28, and a white LED is used in the present embodiment. This white LED is, for example, a semiconductor light emitting element on a substrate sealed with a resin material. As the semiconductor light emitting element, for example, a blue (wavelength λ: 470 to 490 nm) LED element or ultraviolet light (wavelength λ: less than 470 nm). An LED element is formed by laminating a plurality of semiconductor layers of a gallium nitride compound semiconductor (for example, an InGaN compound semiconductor) on an insulating substrate such as a sapphire substrate.
Further, the resin material for sealing the semiconductor light emitting element is mainly composed of a silicone resin and, for example, a YAG phosphor is added. This YAG phosphor converts white light or ultraviolet light from a semiconductor light emitting element into yellow light and generates white light by a color mixing effect. Various white LEDs other than those described above can be used.

  The mounting FPC 28 is bonded to the light source mounting surface of the metal heat radiating plate 19 with a double-sided tape, and the light source L is installed so as to be close to the light incident side end surface of the light guide plate 13. Further, the mounting FPC 28 has a base end side disposed on the back side of the metal heat sink 19, and an external terminal portion 28 a for electrical connection with the outside is provided at the base end portion.

  The light guide plate 13 is a thin plate-like or film-like light guide that changes the optical path of light incident from the light source L arranged on the side end surface that is a light incident surface and emits the light from the main surface side in a planar shape. . For example, the light guide plate 13 is made of a translucent resin material such as polycarbonate resin or acrylic resin. Note that brightness adjustment may be performed by applying a fine optical shape such as white dot printing or a prism shape to at least one of the front surface (main surface) and the back surface of the light guide plate 13.

As the reflection sheet 14, a metal plate having a light reflection function, a film, a foil, a film provided with a silver vapor deposition film, a film provided with an aluminum metal vapor deposition film, a white sheet, or the like can be used. For example, a reflective film having a multilayer film structure using a polyester resin is used.
The diffusion sheet 17 is a sheet in which silica particles or the like are dispersed in a transparent resin such as an acrylic resin or a polycarbonate resin.

  The brightness enhancement film 16 is a transparent sheet-like member for condensing light from the diffusion sheet 17 on the upper surface side, and is a prism sheet in which a prism shape having a plurality of parallel ridge lines is applied on the upper surface side. is there. For example, a BEF (Brightness Enhancement Firm: trade name) sheet manufactured by Sumitomo 3M Limited can be used.

  The reflective polarizing film 15 is a sheet that transmits only one of the S component and P component of light and reflects the other. The reflected component light returns to the reflective sheet 14 side and is converted into component light that passes through the reflective polarizing film 15 before entering the reflective polarizing film 15 again. As such a reflective polarizing film 15, for example, a D-BEF (trade name) sheet manufactured by Sumitomo 3M Limited can be used.

  The liquid crystal display panel 21 is a transmissive or transflective liquid crystal display panel. For example, in the case of the transmissive liquid crystal display panel 21, a TFT liquid crystal method in which a liquid crystal material is sealed with a sealing material in a gap between an upper substrate and a lower substrate each having a transparent electrode, an alignment film, and a polarizing plate, an STN liquid crystal method, and a TN A panel body such as a liquid crystal system is provided.

The frame-shaped casing 11 is resin-molded with a black resin in a rectangular frame shape by injection molding. The frame-like housing 11 has a slide groove 11a for guiding the resin support plate 12 so that it can be inserted from one side. The slide groove 11a is formed inside a pair of sides parallel to the insertion direction. 2 and 3, the insertion direction is indicated by an arrow.
The frame-shaped casing 11 has positioning pins 11b that are integrally formed so as to protrude to the back surface side.

  Further, as shown in FIGS. 4 and 5, the frame-shaped housing 11 protrudes inward and is integrally formed and abuts against the end surface of the light guide plate 13 to press the light guide plate 13 toward at least the light source mounting surface side. There are provided convex portions 11c, and elasticity imparting hole portions 11d integrally formed on the side opposite to the protruding direction of the pressing convex portions 11c in the vicinity of the pressing convex portions 11c.

  Two pressing protrusions 11c are provided on two sides of one long side and a short side perpendicular to each other, and extend in the side direction in the vicinity of these pressing protrusions 11c. The elongated hole-like elasticity imparting hole portion 11d is formed. The long side portion provided with the pressing convex portion 11c is opposite to the side where the light source L is installed. That is, the light guide plate 13 fitted in the frame-shaped casing 11 is pressed in the oblique direction from the corners by these two sides to the opposite corners by the pressing convex portions 11c of the two sides, and the light source L is It is positioned in contact with the long side portion to be arranged.

  The light guide plate 13 has a light guide plate-side convex portion 13a for positioning on the outer periphery. Moreover, the frame-shaped housing | casing 11 has the housing | casing side recessed part 11e integrally formed so that fitting with the light-guide plate side convex part 13a was possible. That is, when the light guide plate 13 is incorporated in the frame-shaped housing 11, the light guide plate-side convex portions 13a are fitted into the housing-side concave portions 11e so that they can be positioned with respect to each other.

Similarly, the diffusion sheet 17, the brightness enhancement film 16, and the reflective polarizing film 15 are formed with film-side convex portions 17a, 16a, and 15a that can be fitted into the housing-side concave portion 11e so that they can be positioned when assembled. It has become.
Note that a light guide plate-side concave portion may be formed on the light guide plate 13 side, and a housing-side convex portion integrally formed so as to be fitted to the light guide plate-side concave portion may be formed on the inside of the frame-shaped housing 11 side. .

The resin support plate 12 has a plurality of protrusions 12 a that protrude to the back surface of the metal heat dissipating plate 19 disposed on the back surface side and hold the metal heat dissipating plate 19 by integral molding.
The metal heat radiating plate 19 is set to an area where the heat generated from the mounted light source L can be radiated sufficiently and sufficiently, and in this embodiment, the metal heat radiating plate 19 is set to about half the size of the resin support plate 12. ing.

  When manufacturing the backlight unit 10, first, the reflective polarizing film 15, the brightness enhancement film 16, the diffusion sheet 17, the light guide plate 13, and the reflection sheet 14 are positioned in this order in the frame-shaped housing 11. Fit it. Next, in this state, the metal heat sink 19 is disposed in the frame-shaped housing 11. A mounting FPC 28 on which a light source L is mounted in advance is attached to the light source mounting surface of the metal heat sink 19.

Further, in this state, the resin support plate 12 is guided between the metal heat radiating plate 19 and the reflection sheet 14 while guiding the both sides from the one side of the frame-like housing 11 into the slide groove 11a. Insert into and set. At this time, the metal heat radiating plate 19 is held so that the protrusion 12 a protrudes to the back surface side of the metal heat radiating plate 19.
The backlight unit 10 thus manufactured is fixed by inserting the positioning pins 11b into the casing of the liquid crystal display device 20, and the liquid crystal display panel 21 is installed on the backlight unit 10 to constitute the liquid crystal display device 20. To do.

  As described above, in the backlight unit 10 of the present embodiment, the frame-shaped casing 11 is resin-molded, and the slide groove 11a that guides the resin support plate 12 so that it can be inserted from one side is parallel to the insertion direction. Since it is formed inside a pair of sides, it is not a metal-to-metal fitting structure but is incorporated by a sliding method of a resin member, so that no metal debris is generated and an electrical short can be prevented. In addition, when the metal heat sink 19 is fitted into the frame-shaped casing 11, no metal debris is generated because the frame-shaped casing 11 is made of resin.

  In addition, since the frame-shaped housing 11 is resin-molded, the slide groove 11a and the like can be easily formed, and the cost of the member is greatly increased compared to the case where the metal plate is processed into a complicated box-type fitting structure. Can be reduced. Furthermore, the heat generated from the light source L can be efficiently radiated by the metal heat radiating plate 19 provided separately.

And since the frame-shaped housing | casing 11 is formed with black resin, it becomes difficult to reflect the light from the light source L on the inner surface of the frame-shaped housing | casing 11, and it suppresses that it leaks out to the surface side from a clearance gap. Can do.
Further, since the frame-shaped housing 11 has the positioning pins 11b that are integrally formed so as to protrude toward the back surface side, the positioning pins 11b when the frame-shaped housing 11 is attached can be easily formed. Since there is no need to prepare a pin separately, the member cost can be further reduced.

  Furthermore, since the frame-shaped housing | casing 11 has the housing | casing side recessed part 11e integrally molded so that fitting with the light-guide plate side convex part 13a of the light-guide plate 13 is carried out inside, the corresponding light-guide plate side convex part 13a and The built-in light guide plate 13 can be easily positioned by the housing-side recess 11e. The housing-side recess 11e can be easily manufactured by integral molding, and it is not necessary to separately prepare a frame for holding the light guide plate, and the member cost can be further reduced.

  The frame-shaped housing 11 includes a pressing convex portion 11c that presses the light guide plate 13 toward at least the light source mounting surface side, and an elasticity applying hole portion 11d that is integrally formed in the vicinity of the pressing convex portion 11c. Therefore, the light guide plate 13 is pressed against the light source mounting surface side with elasticity by the pressing convex portion 11c and the elasticity applying hole portion 11d, and the distance between the light source L and the light incident end surface of the light guide plate 13 is increased. Positioning can be achieved while keeping it constant. As a result, it is possible to prevent the incorporated light guide plate 13 from rattling within the frame-shaped housing 11.

In addition, since the resin support plate 12 has a protrusion 12a that protrudes up to the back surface of the metal heat sink 19 and holds the metal heat sink 19, the holding function of the metal heat sink 19 is also achieved. The resin support plate 12 can be easily provided.
Therefore, the liquid crystal display device 20 of the present embodiment provided with the backlight unit 10 is inexpensive and excellent in recyclability, and can prevent problems such as electrical shorts.

  In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.

  For example, in the liquid crystal display device of the above embodiment, a diffusion sheet is used, but a backlight unit in which the diffusion sheet is omitted may be used. Further, although one prism sheet, which is a brightness enhancement film, is used, a configuration using two sheets may be used. Further, the reflective polarizing film may be omitted.

Moreover, in the said embodiment, although the metal heat sink is arrange | positioned at the back surface side of the resin support plate, a metal heat sink is provided on the surface side (between the reflective sheet and the resin support plate) of the resin support plate. You may arrange.
Furthermore, as described above, it is preferable to form the pressing convex portion integrally with the frame-shaped housing, but only the pressing convex portion is separately made of an elastic material such as rubber, and the frame-shaped casing is used as a component. You may attach to the groove | channel etc. which were formed in the internal peripheral surface.

  3, 13 ... Light guide plate, 4, 14 ... Reflective sheet, 10 ... Backlight unit, 11 ... Frame-shaped housing, 11a ... Sliding groove, 11b ... Positioning pin, 11c ... Pressing convex part, 11d ... Elasticity imparting Hole 11e: housing side recess, 12: resin support plate, 12a ... projection, 13a ... light guide plate side projection, 19 ... metal heat sink, 20 ... liquid crystal display device, 21 ... liquid crystal display panel, L …light source

Claims (6)

A light guide plate;
A light source that irradiates and guides light to the light guide plate;
A reflective sheet installed on the back side of the light guide plate;
A resin support plate installed on the back side of the reflective sheet;
A metal heat sink having a light source mounting surface on which the light source is mounted while being placed on the back side of the resin support plate and bent on one side to be opposed to the end surface of the light guide plate,
A frame-shaped housing that houses and supports the reflection sheet, the light guide plate, the resin support plate, and the metal heat dissipation plate;
The frame-shaped housing is resin-molded, and has a slide groove for guiding the resin support plate so that it can be inserted from one side .
The backlight unit according to claim 1, wherein the resin support plate has a protrusion that protrudes up to the metal heat dissipating plate disposed on the rear surface side and holds the metal heat dissipating plate by integral molding . The backlight unit according to claim 1,
The light guide plate has a light guide plate side convex portion or a light guide plate side concave portion for positioning on the outer periphery,
The frame-shaped housing has a housing-side concave portion or a housing-side convex portion formed integrally with the light guide plate-side convex portion or the light guide plate-side concave portion so as to be fitted therein. unit. The backlight unit according to claim 1 or 2 ,
A pressing convex portion for pressing the light guide plate toward at least the light source mounting surface side by contacting the end surface of the light guide plate and integrally forming the frame-shaped housing protruding inward;
A backlight unit having an elasticity imparting hole integrally formed on the side opposite to the protruding direction of the pressing projection in the vicinity of the pressing projection. In the backlight unit according to any one of claims 1 to 3 ,
The backlight unit, wherein the frame-shaped housing is formed of a black resin. In the backlight unit according to any one of claims 1 to 4 ,
The backlight unit characterized in that the frame-shaped housing has positioning pins that are integrally formed so as to protrude to the back surface side. A liquid crystal display panel;
A backlight unit according to any one of claims 1 to 5 , which is disposed on the back side of the liquid crystal display panel.

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